JP2012048112A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable use of a 2-component developer with an appropriate carrier ratio according to a toner amount consumed by printing operation.SOLUTION: In a development apparatus, while an electrostatic latent image formed on a photoreceptor is developed using a developer containing a carrier and a toner, at least some of the carrier is disposed with supplying the developer from a replaceable supply bottle. When a replacement timing of a supply bottle is detected, a toner consumption tendency of printing operation carried out in a prescribed period until the replacement timing is determined and information for the appropriate carrier ratio of the developer supplied from the supply bottle is generated on the basis of the determination result to display on a display panel part.

Description

  The present invention relates to an image forming apparatus including a developing device that develops an electrostatic latent image on a photoreceptor using a two-component developer.

A developing device of an electrophotographic image forming apparatus such as a printer or a copying machine includes a method of forming a toner image on a photosensitive drum using a one-component developer composed only of toner, and a toner and magnetic material. There is a method of forming using a two-component developer containing a carrier.
In a method using a one-component developer (toner), a load such as pressure is applied to the toner when various members come into contact with the toner in supplying the toner to the developing device, applying a charge to the toner, collecting the toner, and the like. The toner is coated with inorganic fine particles as a fluidity modifier. When a load such as pressure is applied, the toner surface may change thermally, and the toner deteriorates due to the inorganic fine particles embedded in the toner surface. May be promoted.

  In particular, in order to increase the image forming speed of the image forming apparatus, it is necessary to supply toner at a high speed. For this reason, various members in contact with the toner are rotated at high speed, and a larger load is applied to the toner. Thereby, the deterioration of the toner is further promoted, and the quality of the formed toner image may be lowered. For this reason, when a one-component developer is used, there is a limit to increasing the image forming speed by the image forming apparatus.

Further, in order to improve the image quality of the formed toner image, for example, the diameter of the toner has been reduced to a diameter of 6 μm or less. However, as the diameter of the toner is reduced, a large amount of external additive is required and the fluidity is also deteriorated. For this reason, with a small diameter toner, when a load is applied, aggregation, embedding of an external additive, and the like are likely to occur.
Further, the toner fixing temperature is lowered to save power. However, when the fixing temperature of the toner is lowered, the thermal resistance of the toner is lowered. For this reason, when heat is applied to the toner surface by applying a load to the toner, the deterioration of the toner is promoted.

  In contrast to such a system using a one-component developer, in a system using a two-component developer, the toner is charged by stirring and mixing the magnetic carrier particles and the toner in the developing device, and the charged state. The toner is conveyed together with the carrier by a rotating magnetic roller. The two-component developer forms a magnetic brush having a uniform height on the outer peripheral surface of the magnetic roller, and develops the electrostatic latent image on the photoreceptor with toner.

The developer on the magnetic roller after developing the electrostatic latent image is circulated in the developing device and separated from the magnetic roller by a magnetic field, a scraper, or the like that repels the magnetic roller. The separated developer is used again for developing the electrostatic latent image.
As described above, in the method using the two-component developer, the toner is charged by mixing with the particulate carrier, so that the load applied to the toner is smaller than the method using the one-component developer in which various members are in contact. Become. Thereby, the lifetime of the toner is longer than that of the one-component developer, and the deterioration of the toner is suppressed even when the image is formed at a high speed.

  However, in the case of a two-component developer, when the carrier is used for a long time in the developing device, a carrier spent in which the toner components gradually move to the carrier is generated, and the work function difference of the carrier with respect to the toner is reduced. is there. As a result, the ability of the carrier to charge the toner is reduced, and toner scattering from the developer conveyed on the magnetic roller may occur, and background fogging on which the toner adheres in addition to the electrostatic latent image on the photoreceptor may occur. There is.

When the charge imparting ability of the carrier is lowered, the developer in the developing device is conventionally replaced by a service person. However, the user needs to notify the service person that the developer needs to be replaced, which is troublesome for the user.
Further, in order to suppress the carrier spent in which the toner component is transferred to the carrier, for example, the surface of the carrier is coated with a low surface energy silicone resin, a fluorinated resin, a polyethylene resin, or the like. Thereby, the lifetime of a carrier can be lengthened and the replacement frequency of a developer can be reduced. However, even with such a configuration, it is difficult to extend the lifetime of the carrier to the same level as the lifetime of the developing device itself, and it is necessary to replace the developer several times before the developing device reaches its lifetime. is there.

Also, in the method using a two-component developer, as in the method using a one-component developer, if a large amount of external additive is used as the diameter of the toner is reduced, the fixing temperature is lowered. Extending the life of the carrier has become more difficult due to a decrease in thermal resistance and the like, and the frequency of changing the developer tends to increase.
In order to solve such a problem, Patent Document 1 discloses that the toner and the carrier are individually replenished into the developing device individually while discarding the carrier used in the developing device in small amounts. A configuration has been proposed in which a deteriorated carrier in the developing device is replaced with a carrier that has not deteriorated. In this manner, by separately supplying the carrier and the toner, the carrier and the toner can be maintained at a desired mixing ratio in the developing device. However, in the configuration in which the carrier and the toner are individually replenished to the developing device, there are problems that the configuration and control for replenishing each become complicated, and that the entire apparatus becomes large.

  In Patent Documents 2 and 3, in a rotary developing device in which a plurality of color developing devices rotate about a rotation axis, when the color developing device rotates to a reversal position, the developer in the developing device is fixed by gravity. A configuration is disclosed in which the amount is discarded. With such a configuration, the carrier in the developer containing the carrier and the toner in the color developer can be replaced without interrupting the developing operation.

However, such a configuration can be applied to a rotary type developing device in which each color developing device is reversed, but is applied to a high-speed tandem color image forming apparatus in which each color developing device is not reversed. Can not do it.
Patent Document 4 discloses a trickle developing device. In a trickle type developing device, an undegraded carrier is replenished into the developing device together with the toner, and when the developer level in the developing device exceeds a certain level, the developer is discarded little by little. It has become. Therefore, it is possible to suppress the carrier in the developing device from deteriorating to a certain level or less.

JP 2007-477111 A JP-A-10-161420 JP 2000-231250 A JP 2000-81787 A

  In a trickle-type developing device, a replenishing container such as a replenishing bottle containing developer is usually attached to the developing device so that the developer in the replenishing container is replenished into the developing device. The developer toner and the carrier in the replenishing container are mixed at a predetermined ratio, and the carrier ratio in the developer (toner and carrier) (% by weight, hereinafter, this carrier ratio is referred to as trickle rate). Is normally set to a constant value of about 5 to 30%. Therefore, the developer having a constant trickle rate is always supplied into the developing device.

In the developing device having such a configuration, if a developing operation (printing operation) with a high printing rate that consumes a large amount of toner, such as a solid image, continues, the amount of toner consumed increases. Developer is replenished frequently. In this case, in the developing device, a part of the developer is discarded by increasing the amount of the developer by supplying the developer.
Therefore, the developer supplied from the supply container into the developing device is discarded in a relatively short time. Since the developer to be discarded contains a large number of undegraded carriers, there is a risk that economic efficiency may be impaired by unnecessarily discarding undegraded carriers.

  On the other hand, when a developing operation with a low printing rate with a small amount of toner consumption, such as a character image, continues, the amount of consumed toner decreases, and the number of times the developer is replenished to the developing device decreases. The amount of developer to be replenished also decreases. In this case, since the amount of developer to be discarded is reduced, the replenished carrier stays in the developing device for a relatively long time, and the deterioration of the toner and the carrier is promoted. It will be.

In particular, when the chargeability of the carrier is reduced due to toner spent, depletion, or the like, there is a possibility that toner scattering increases, toner granularity decreases, image quality decreases due to fogging, and the like.
Depending on the user who uses the image forming apparatus, there are a case where the number of printed images with a high printing rate is large and a case where the number of printed images with a low printing rate is large. In the case of a user who has a large number of images printed with a high printing rate, a large amount of undegraded carrier is discarded, and in the case of a user with a large number of images printed with a low printing rate, development is performed. The deterioration of the carrier in the apparatus is promoted.

  The present invention has been made in view of such problems, and an object of the present invention is to use a developer containing a carrier in an appropriate ratio corresponding to the toner consumption of an image that is frequently printed. An object is to provide a possible image forming apparatus.

  In order to achieve the above object, the image forming apparatus according to the present invention is replaceable during development of an electrostatic latent image formed on a photoreceptor using a developer containing a carrier and toner. An image forming apparatus provided with a developing device that discharges at least a part of a carrier while replenishing a developer from a replenishing container, wherein the replacement time detecting unit detects a replacement time of the replenishing container, and the replacement time detecting unit Suitable as a developer to be replenished from the replenishing container based on the determination result of the determination means and the determination result of the determination means in the printing operation executed within a predetermined period until the replacement time detected by And a developer information generating means for generating information relating to the carrier ratio, and an output means for outputting information generated by the developer information generating means.

  In the image forming apparatus according to the present invention, when the supply container is replaced, the tendency of the toner consumption amount of the printing operation executed within a predetermined period until then is determined, and the supply container is determined with respect to the determined trend of the toner consumption amount. Since the information on the appropriate carrier ratio of the developer replenished from the printer is generated and output, it is possible to use the developer having the carrier ratio corresponding to the printing operation to be executed thereafter. As a result, it is possible to suppress the waste of the carrier or the deterioration of the image quality due to the deterioration of the carrier.

Preferably, the determination unit calculates a printing rate for each printing operation, classifies all the printing operations executed in the predetermined period based on a preset printing rate range, Based on the number of printing operations classified into the printing rate range, the tendency of the printing rate is determined as the trend of toner consumption of the executed printing operation.
Preferably, the developer information generation unit generates information on a low carrier ratio when the determination unit determines that the tendency is high toner consumption, and the determination unit determines that the tendency is low toner consumption. If so, it is characterized in that information on a high carrier ratio is generated.

Preferably, the developing device is characterized in that a plurality of types of replenishing containers each containing a developer set to a different carrier ratio are selectively removable.
Preferably, the developer information generating unit generates information on the type of supply container suitable for the tendency of toner consumption determined by the determining unit.
Preferably, the developing device includes an acquisition unit that acquires information relating to a carrier ratio of the developer in the replenishment container that is mounted.

  Preferably, the information processing apparatus further includes warning means for issuing a warning when the information on the carrier ratio of the developer acquired by the acquisition means is different from the information on the type of supply container generated by the developer information generation means. It is characterized by.

1 is a schematic diagram illustrating a configuration of a monochrome printer which is an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram showing a flat cross section of a developing device provided in an image process section of the monochrome printer. It is a longitudinal cross-sectional view of the principal part in the developing device. It is a block diagram which shows the structure of the control system of a monochrome printer. 6 is a flowchart illustrating an example of a processing procedure of developer information display control executed by a CPU of a monochrome printer. 6 is a graph showing that the amount of discarded carrier can be reduced by using a developer having a low trickle rate. (A) to (d) conceptually show the effect of continuing to use a replenishing bottle containing a high trickle rate (30%) developer when the tendency of the entire printing operation is low printing rate. It is the graph shown.

[Printer configuration]
FIG. 1 is a schematic diagram illustrating a schematic configuration of a monochrome printer which is an example of an image forming apparatus according to an embodiment of the present invention. This printer includes an image processing unit 10 that forms a toner image on a recording sheet by an electrophotographic method based on image data input from an external terminal device and the like, and a paper feed that supplies the recording sheet to the image processing unit 10 And a fixing unit 33 that fixes the toner image transferred onto the recording sheet in the image processing unit 10 onto the recording sheet.

  The image processing unit 10 is provided with a photosensitive drum 11 that is rotatably arranged in a direction indicated by an arrow X in FIG. 1. A recording supplied from a paper feeding unit 31 is provided above the photosensitive drum 11. A conveyance path 34 through which the sheet is conveyed is provided along the horizontal direction. The recording sheet in the sheet feeding unit 31 is conveyed by the timing roller 32 through the conveyance path 34 at a predetermined timing, and is supplied to the photosensitive drum 11.

  A cleaning unit 12 and a charging roller 13 are sequentially arranged along the rotation direction of the photosensitive drum 11 on the downstream side in the rotation direction with respect to the upper surface of the photosensitive drum 11 facing the conveyance path 34. The cleaning unit 12 cleans the surface of the photosensitive drum 11 with a plate-like blade 12a. The charging roller 13 uniformly charges the surface of the photosensitive drum 11.

  A laser beam L is applied to a surface position downstream of the charging roller 13 in the rotation direction of the photosensitive drum 11 from an exposure scanning device 14 disposed below the photosensitive drum 11. The exposure scanning device 14 irradiates the surface of the photosensitive drum 11 with a laser beam L modulated according to the image data, and the electrostatic latent image corresponding to the image data is applied to the charged surface of the photosensitive drum 11. Form.

  A developing device 20 is disposed opposite the photosensitive drum 11 on the downstream side in the rotation direction of the photosensitive drum 11 with respect to the irradiation position of the laser beam L from the exposure scanning device 14. The developing device 20 is formed on the surface of the photosensitive drum 11 using a two-component developer including a non-magnetic toner (hereinafter simply referred to as “toner”) and a magnetic carrier (hereinafter simply referred to as “carrier”). The electrostatic latent image is developed with toner. A specific configuration of the developing device 20 will be described later.

  A transfer roller 16 is disposed above the photosensitive drum 11 so as to face each other with a recording sheet conveyance path 34 interposed therebetween. The transfer roller 16 is in contact with the surface of the photosensitive drum 11, and a transfer nip TN is formed between the surface of the photosensitive drum 11 and the transfer roller 16. A recording sheet is conveyed to the transfer nip TN in synchronization with the timing at which the toner image on the photosensitive drum 11 is conveyed.

The toner image on the photosensitive drum 11 is transferred to the recording sheet S passing through the transfer nip TN by the electrostatic force of the electric field formed by the transfer roller 16.
The recording sheet that has passed through the transfer nip TN is conveyed to the fixing unit 33. The fixing unit 33 includes a heating roller 33a and a pressure roller 33b that are in pressure contact with each other, and a fixing nip FN is formed between the heating roller 33a and the pressure roller 33b. A heater lamp 33c is disposed at the axial center of the heating roller 33a, and the heating roller 33a is heated by the heater lamp 33c.

The toner image of the recording sheet that passes through the transfer nip TN and is conveyed to the fixing unit 33 is fixed on the recording sheet by being heated and pressurized while the recording sheet passes through the fixing nip FN. The recording sheet on which the toner image is fixed in the fixing unit 33 is discharged onto a paper discharge tray (not shown).
The toner that forms the toner image on the photosensitive drum 11 may not be completely transferred onto the recording sheet by the electrostatic force from the transfer roller 16, and a part of the toner may remain on the photosensitive drum 11. The toner is removed by the blade 12 a in the cleaning unit 12.

  The printer is provided with a control unit 51 for controlling the entire printer including the image processing unit 10. The control unit 51 modulates the laser light emitted from the exposure scanning device 14 based on image data input from an external terminal or the like. Further, the control unit 51 controls a panel display unit 52 a provided on the operation panel 52. The operation panel 52 is provided with warning lights 52b and 52c, a speaker 52d, and the like around the panel display section 52a.

  In the image processing unit 10, the photosensitive drum 11 is charged by the charging roller 13, but instead of such a configuration, a rotary or fixed brush charging device, a corona discharge charging device, A proximity charging member or the like that does not contact the surface of the photosensitive drum 11 may be used. Further, in place of the configuration in which the toner image on the photosensitive drum 11 is transferred to the recording sheet by the transfer roller 16, an intermediate transfer body such as a wire discharge type transfer device or an intermediate transfer belt is arranged to transfer in two or more stages. A method of performing the above may be used. Further, the cleaning unit 12 may use a rotary brush, a fixed brush, or the like instead of the configuration using the plate-like blade 12a.

[Developer configuration]
The developing device 20 includes a developing roller 27, a supply screw 25, and a stirring screw, which are disposed in a housing 21 in which a two-component developer containing toner and a carrier is accommodated, and are substantially parallel to the photosensitive drum 11. 24 is provided. The developing roller 27 is disposed in the vicinity of the photosensitive drum 11, and the supply screw 25 and the stirring screw 24 are sequentially disposed on the opposite side of the developing roller 27 from the photosensitive drum 11.

Above the supply screw 25, a hopper 22 for replenishing developer in the housing 21 is provided. A cylindrical supply bottle 41 containing a two-component developer containing a carrier and toner is mounted on the hopper 22 in a horizontal state. The supply bottle 41 is detachable from the hopper 22.
The supply bottle 41 has one end portion (tip portion) formed in a tapered shape, and an opening is provided at the tip thereof. The replenishing bottle 41 is held in a horizontal state by the tip portion being mounted on the upper portion of the hopper 22 and the other end portion (bottom portion) being engaged with the bottle holder 28.

The bottle holder 28 is rotated by a bottle rotation motor 43, and the supply bottle 41 in a horizontal state is rotated by the rotation of the bottle holder 28. A spiral groove is formed on the peripheral surface of the supply bottle 41, and the developer inside is conveyed toward the opening by the rotation of the supply bottle 41 and supplied into the hopper 22.
The replenishment bottle 41 contains a developer having a predetermined trickle rate (weight% ratio of the carrier in the developer) in which the mixing ratio of the toner and the carrier is set in advance. In the hopper 22, for example, three types of supply bottles 41 each containing developer having a trickle rate of 5% (for high printing rate), 15% (standard), and 30% (for low printing rate) are respectively provided. Detachable.

Each replenishing bottle 41 is provided with an IC chip 41a in which information on trickle rate in the stored developer is stored. The bottle holder 28 is provided with an IC chip reader 28 a that reads information stored in the IC chip 41 a attached to the supply bottle 41.
The hopper 22 is provided with a level sensor 22 a that detects the level of the developer in the hopper 22. The level sensor 22a outputs a predetermined signal when the developer in the hopper 22 falls below a predetermined level. The bottle rotation motor 43 is rotationally driven when the level sensor 22a detects that the developer in the hopper 22 has become a predetermined level or less, and the developer in the replenishment bottle 41 is supplied into the hopper 22. .

  A replenishing screw 22 c for supplying the developer in the hopper 22 into the housing 21 of the developing device 20 is provided at the lower end of the hopper 22 in parallel with the stirring screw 24. The replenishment screw 22c is rotated by the replenishment motor 44 and conveys the developer to a replenishment port 21p (see FIG. 2) provided above one end of the stirring screw 24. The developer conveyed to the supply port 21p passes through the supply port 21p and is supplied to one end of the stirring screw 24 in the housing 21.

The developer replenished to one end of the stirring screw 24 in the housing 21 is conveyed from the other end of the stirring screw 24 to a supply screw 25 parallel to the stirring screw 24, and is supplied to the supply screw 25. Is conveyed in a direction opposite to the conveying direction of the stirring screw 24.
A discharge port 21m (see FIG. 2) for discharging the developer is provided on the bottom surface of the housing 21 so as to face the end of the supply screw 25 on the downstream side in the developer transport direction. Below the housing 21, a developer collection container 23 that collects the developer discharged from the discharge port 21 m is provided detachably with respect to the housing 21.

  FIG. 2 is a schematic cross-sectional view when the circulation conveyance path of the developing device 20 is viewed from above. As shown in FIGS. 1 and 2, the inside of the housing 21 is divided by a partition wall 21c into a mixing chamber 21a in which the stirring screw 24 is accommodated and a developing chamber 21b in which the developing roller 27 and the supply screw 25 are accommodated. ing. The partition wall 21c is arranged in a vertical state (see FIG. 1) along the stirring screw 24 and the supply screw 25.

The stirring screw 24 is a spiral screw in which spiral blades 24b having a constant pitch are provided over almost the entire area of the shaft 24a. The supply screw 25 is a spiral screw in which first spiral blades 25b having a constant pitch are provided in a region along the partition wall 21c in the shaft 25a.
The stirring screw 24 is rotated in a predetermined direction by the spiral blade 24b so that the developer in the mixing chamber 21a is conveyed in the direction indicated by the arrow A in FIG. Further, the supply screw 25 is rotated in the direction opposite to the rotation direction of the stirring screw 24 so that the developer in the developing chamber 21b is conveyed in the direction indicated by the arrow B in FIG. Is done.

  At the bottom of the mixing chamber 21a, a magnetic sensor 29 is provided for detecting the toner concentration of the developer conveyed in the mixing chamber 21a. Based on the toner concentration in the mixing chamber 21a detected by the magnetic sensor 29, the replenishing screw 22c provided at the lower portion of the hopper 22 is rotated, and the developer in the hopper 22 is supplied into the mixing chamber 21a. The Accordingly, when the toner concentration in the mixing chamber 21a is lowered, a carrier having a predetermined trickle ratio is supplied to the mixing chamber 21a together with the toner.

  Inside the housing 21, on the downstream side of the developer conveying direction by the stirring screw 24, as shown by an arrow F in FIG. 2, a first opening 21d that allows the developer to flow from the mixing chamber 21a to the developing chamber 21b. Is provided. An end portion of the shaft 24a of the stirring screw 24 on the downstream side in the developer conveyance direction faces the first opening 21d. At the end of the agitating screw 24 facing the first opening 21d, a reversely wound spiral blade 24c having a spiral direction opposite to that of the spiral blade 24b is provided on the shaft 24a.

  Further, in the housing 21, a second opening portion 21e that flows from the developing chamber 21b to the mixing chamber 21a is provided adjacent to the partition wall 21c in the downstream portion of the developer conveying direction by the supply screw 25. Yes. A part of the developer conveyed in the developing chamber 21b by the supply screw 25 is conveyed to the mixing chamber 21a through the second opening 21e as shown by an arrow E in FIG.

  The shaft 24a and the spiral blade 24b of the stirring screw 24 disposed in the mixing chamber 21a extend further to the upstream side in the developer conveying direction than the second opening 21e, and the development in the shaft 24a and the spiral blade 24b. The upstream end portion in the developer transport direction is located in the developer inflow portion 21f protruding toward the upstream side in the developer transport direction in the mixing chamber 21a. The developer inflow portion 21f has a cylindrical shape that accommodates the end of the spiral blade 24b, and a replenishment port 21p through which the developer from the hopper 22 is supplied into the housing 21 is provided above the developer inflow portion 21f. It has been.

  The shaft 25a of the supply screw 25 disposed in the developing chamber 21b extends further downstream in the developer transport direction than the second opening 21e, and the downstream end of the shaft 25a in the developer transport direction. Is located in the developer discharge portion 21g protruding toward the downstream side in the developer conveying direction in the stirring chamber 21b. The developer discharge portion 21g is configured in a cylindrical shape coaxial with the shaft 25a of the supply screw 25.

The shaft 25a of the supply screw 25 is provided with a reversely wound spiral blade 25c having a spiral direction opposite to that of the first spiral blade 25b at a portion facing the second opening 21e. The reverse spiral spiral blade 25c has a spiral pitch smaller than the spiral pitch of the first spiral blade 25b.
The shaft 25a of the supply screw 25 located in the developer discharge portion 21g has a second spiral blade 25d having the same spiral direction as the first spiral blade 25b and a smaller spiral pitch than the first spiral blade 25b. Is provided.

On the shaft 25a of the supply screw 25, a disk-shaped partition plate 25e that is orthogonal to the shaft 25a is coaxial with the shaft 25a between the reversely wound spiral blade 25c and the second spiral blade 25d. Is provided.
A developer discharge port 21m is provided on the bottom surface of the developer discharge portion 21g, and a developer recovery container 23 is mounted below the developer discharge port 21m.

The reverse spiral spiral blade 25c of the supply screw 25, the partition plate 25e, the second spiral blade 25d, and the developer discharge portion 21g provide a trickle discharge mechanism that discharges from the developer discharge port 21m when the amount of developer in the housing 21 increases. It is composed.
The developing roller 27 provided in the developing chamber 21b is disposed between the supply screw 25 and the photosensitive drum 11 in a state where a predetermined developing gap is formed with respect to the outer peripheral surface of the photosensitive drum 11 ( (See FIG. 1). The developing roller 27 has a cylindrical developing sleeve 27a rotatably supported by the housing 21 and a cylindrical magnet body 27b fixed therein so as not to rotate with respect to the housing 21. It is.

The developing sleeve 27a is rotationally driven so that the respective surface positions are opposite to each other (counter direction) at the position facing the photosensitive drum 11.
As shown in FIG. 1, the magnet body 27b provided inside the developing sleeve 27a is provided with a first N pole (N1) at a position close to the photosensitive drum 11, and this first N pole (N1). The first S pole (S1), the second N pole (N2), the third N pole (N3), and the second S pole (on the upstream side in the rotation direction of the developing sleeve 27a (opposite to the rotation direction) S2) are arranged in order. The first N pole (N1) close to the photosensitive drum 11 is adapted to attract the carrier to the developing sleeve 27a.

Above the developing sleeve 27a, a strip-shaped regulating plate 21n extending in parallel along the developing sleeve 27a is disposed in a state where a predetermined regulating gap is formed with the outer peripheral surface of the developing sleeve 27a. The regulating plate 21n regulates the thickness of the developer layer attached to the outer peripheral surface of the developing sleeve 27a so that a predetermined amount of developer is conveyed by the developing sleeve 27a.
While the developer in the mixing chamber 21a is conveyed to the first opening 21d by the spiral blade 24b of the stirring screw 24, the toner and the carrier are stirred and mixed. As a result, the toner is charged. The developer charged with toner is supplied into the developing chamber 21 b through the first opening 21 d and is conveyed along the developing roller 27 by the first spiral blade 25 b of the supply screw 25. The developer is supplied to the outer peripheral surface of the developing sleeve 27 a while being conveyed along the developing roller 27.

The developer supplied to the outer peripheral surface of the developing sleeve 27a forms a magnetic brush on the outer peripheral surface of the developing sleeve 27a, and toner develops the electrostatic latent image formed on the photosensitive drum 11 with the magnetic brush. The toner that does not adhere to the electrostatic latent image is returned to the developing chamber 21b together with the carrier.
The developer conveyed in the developing chamber 21 b without being supplied to the outer peripheral surface of the developing sleeve 27 a or the developer returned to the developing chamber 21 b without adhering to the photosensitive drum 11 is supplied to the supply screw 25. The first spiral blade 25b conveys the reverse wound spiral blade 25c.

FIG. 3 is a longitudinal sectional view of the peripheral portion of the reversely wound spiral blade 25c. As shown in FIG. 3, the reverse spiral spiral blade 25c is opposite to the transport direction by the first spiral blade 25b with respect to the developer transported by the first spiral blade 25b (the direction indicated by the arrow D in FIG. 3). Add transport force to
As a result, the developer conveyed by the first spiral blade 25b is in a state of being blocked by the reversely wound spiral blade 25c and the partition plate 25e. In this case, the developer that does not overflow the partition plate 25e is conveyed to the mixing chamber 21a through the second opening 21e as indicated by an arrow E in FIG.

  However, when the amount of developer in the developing chamber 21b is increased by replenishing the developer from the developer replenishing bottle 41, a part of the developer overflows the partition plate 25e as shown by an arrow C in FIG. Then, it flows into the developer discharge portion 21g. The developer that has flowed into the developer discharge portion 21g is conveyed to the developer discharge port 21m by the second spiral blade 25d, and discharged (discarded) into the developer recovery container 23 through the developer discharge port 21m. Is done.

[Configuration of developer]
The toner and carrier of the two-component developer used in the developing device 20 are not particularly limited, and known toners and carriers that are generally used can be used.
In general, a toner is mixed with a colorant in a binder resin, and if necessary, a charge control agent, a release agent and the like are mixed and granulated to a predetermined particle size, and then an external additive is coated. Manufactured by. The toner can be produced by a generally known method such as a pulverization method, an emulsion polymerization method, or a suspension polymerization method. The particle size of the toner is not particularly limited, but is preferably about 3 to 15 μm.

  The binder resin used in the toner is not particularly limited. For example, styrene resin (monopolymer or copolymer containing styrene or a styrene substitution product), polyester resin, epoxy resin, chloride Vinyl resin, phenol resin, polyethylene resin, polypropylene resin, polyurethane resin, silicone resin and the like can be used. In particular, it is preferable that the softening temperature is in the range of 80 to 160 ° C. and the glass transition point is in the range of 50 to 75 ° C. by the resin alone or the composite.

  In addition, as the colorant, commonly known ones can be used, such as carbon black, aniline black, activated carbon, magnetite, benzine yellow, permanent yellow, naphthol yellow, phthalocyanine blue, first sky blue, Ultramarine blue, rose bengal, lake red, etc. can be used. The colorant is usually preferably used in a ratio of 2 to 20 parts by weight with respect to 100 parts by weight of the binder resin.

  As the charge control material, known materials can be used. Examples of the charge control material for the positively chargeable toner include nigrosine dyes, quaternary ammonium salt compounds, and triphenylmethane compounds. , Imidazole compounds, and polyamine resins. Examples of the charge control material for negatively chargeable toners include azo dyes containing metals such as Cr, Co, Al, and Fe, salicylic acid metal compounds, and curixarene compounds. In general, the charge control material is preferably used at a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  In addition, as the above-mentioned mold release material, publicly known known materials can be used. For example, polyethylene, polypropylene, carnauba wax, sazol wax and the like are used alone or in combination of two or more. be able to. As a mold release material, it is preferable to use it in the ratio of 0.1-10 weight part with respect to 100 weight part of said binder resin.

  As the particles externally added to the toner, commonly used known particles can be used. For the purpose of improving fluidity, fluidizing agents such as silica, titanium oxide, and aluminum oxide can be used. In particular, water repellency is achieved with a silane coupling agent, a titanium coupling agent, silicon oil, or the like. A fluidizing agent is preferred. Such a fluidizing agent is usually used by adding 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner. The average primary particle size of the external additive is preferably 10 to 100 nm.

The carrier is not particularly limited, and a commonly used binder-type carrier, coat-type carrier, or the like that is generally used can be used. Although it does not specifically limit as a carrier particle size, 15-100 micrometers is preferable.
The binder-type carrier can be fixed with magnetic fine particles or provided with a surface coating layer. The charging characteristics such as the polarity of the binder type carrier can be controlled by the material of the binder resin, the charged fine particles, and the type of the surface coating layer.

Examples of the binder resin used for the binder-type carrier include thermoplastic resins such as vinyl resins, polyester resins, nylon resins, polyolefin resins, and the like represented by polystyrene resins, and thermosetting resins such as phenol resins. The
Magnetic fine particles of the binder-type carrier include spinellar ferrites such as magnetite and gamma iron oxide, spinelar ferrites containing one or more metals other than iron (Mn, Ni, Mg, Cu, etc.) and barium. Magnetoplumbite-type ferrite such as ferrite, iron having an iron oxide on the surface, particles such as an alloy can be used. The shape may be any of granular, spherical and acicular. In particular, when high magnetization is required, it is preferable to use iron-based ferromagnetic fine particles. In consideration of chemical stability, it is preferable to use ferromagnetic fine particles of a magnetite, pumbitite type ferrite such as spinel ferrite containing gamma iron oxide and barium ferrite. A magnetic resin carrier having desired magnetism can be obtained by appropriately selecting the type and content of the ferromagnetic fine particles. The magnetic fine particles are preferably added in an amount of 50 to 90% by weight in the magnetic resin carrier.

Silicone resin, acrylic resin, epoxy resin, fluorine resin, etc. are used as the surface coating material for the binder type carrier, and these resins are coated on the surface and cured to form a coating layer, thereby providing a charge imparting ability. Can be improved.
For example, the charging fine particles or the conductive fine particles can be fixed to the surface of the binder-type carrier by, for example, mixing the magnetic resin carrier and the fine particles uniformly, and adhering these fine particles to the surface of the magnetic resin carrier. By applying a strong impact force and fixing the fine particles so as to be driven into the magnetic resin carrier.

  In this case, the fine particles are not completely embedded in the magnetic resin carrier, but are fixed so that a part thereof protrudes from the surface of the magnetic resin carrier. As the chargeable fine particles, an organic or inorganic insulating material is used. Specifically, organic insulating fine particles such as polystyrene, styrene copolymer, acrylic resin, various acrylic copolymers, nylon, polyethylene, polypropylene, fluororesin, and cross-linked products thereof can be used as an organic system. Regarding the charge level and polarity, a desired level of charge and polarity can be obtained by a material, a polymerization catalyst, a surface treatment, and the like. Further, as the inorganic type, negatively charged inorganic fine particles such as silica and titanium dioxide, and positively charged inorganic fine particles such as strontium titanate and alumina are used.

  On the other hand, a coated carrier is a carrier in which a carrier core particle made of a magnetic material is coated with a resin, and in a coated carrier, positive or negative chargeable fine particles are fixed on the surface of the carrier, like a binder carrier. It can also be made. The chargeability such as the polarity of the coat type carrier can be controlled by the type of the surface coating layer and the chargeable fine particles, and the same material as the binder type carrier can be used. In particular, the same resin as the binder resin of the binder type carrier can be used as the coating resin.

Charge polarity of toner and reverse polarity particles by combination of reverse polarity particles, toner and carrier can be easily from the direction of the electric field to separate the toner or reverse polarity particles from the developer after mixing and stirring each to make the developer I can know.
In the housing 21 of the developing device 20, the mixing ratio of the toner and the carrier may be adjusted so as to obtain a desired toner charge amount, and the toner ratio is 3 to 30% with respect to the total amount of the toner and the carrier. %, Preferably 4 to 20% by weight is suitable.

[Control system configuration]
FIG. 4 is a block diagram showing the configuration of the printer control system. The control unit 51 includes a CPU 51a, a communication I / F (interface) unit 51b, a RAM 51c, a ROM 51d, and the like.
The communication I / F unit 51b is a LAN card, a LAN board, or the like for connecting a LAN with an external client terminal, and receives print job data transmitted from the client terminal via the LAN and sends it to the CPU 51a.

The RAM 51c is a volatile memory and serves as a work area when the CPU 51a executes a program.
The ROM 51d stores a program for controlling the operation of each unit in the printer.
The CPU 51a reads a necessary program from the ROM 51d based on the acquired image data, controls the operations of the image processing unit 10, the paper feeding unit 31, and the fixing unit 33 uniformly, and smoothly executes the image forming operation.

  In the developing device 20, the CPU 51a rotates the replenishment motor 44 based on the toner concentration in the mixing chamber 21a detected by the magnetic sensor 29 to supply the developer in the hopper 22 into the mixing chamber 21a. . Further, the CPU 51a rotates the supply motor 44 based on the developer amount in the hopper 22 detected by the level sensor 22a to supply the developer in the supply bottle 41 into the hopper 22.

  Further, when the level of the developer in the hopper 22 detected by the level sensor 22a does not increase even when the bottle rotation motor 43 is rotated for a predetermined time based on the detection result of the level sensor 22a, the CPU 51a The display panel unit 52a, the warning lamp 52b, the speaker 52d, and the like provided on the operation panel 52 are controlled so that a predetermined warning is issued on the assumption that the developer in the supply bottle 41 has run out.

Further, the CPU 51a acquires the information stored in the IC chip 41a attached to the newly mounted supply bottle 41 when the supply bottle 41 is replaced by the IC chip reader 28a, and based on the read information. The display panel 52a, the warning lamp 52b, the speaker 52d and the like provided on the operation panel 52 are controlled.
Further, in the present embodiment, the CPU 51a calculates the printing rate from the printing history in a predetermined period until the replacement bottle 41 is replaced, and the printing operation that is mainly executed based on the calculated printing rate. An appropriate value of the trickle rate is obtained, and developer information display control for displaying the obtained appropriate value of the trickle rate on the display panel unit 52a of the operation panel 52 is executed.

  For this reason, when a print job is input from an external client terminal or the like, the CPU 51a calculates a print rate based on the image data for each print operation included in the print job, and calculates the calculated print rate. Based on the above, it is determined whether each printing operation is a high printing rate, a standard printing rate, or a low printing rate. Information regarding the printing rate of each determined printing operation is stored in the RAM 51c.

[Developer information display control]
FIG. 5 is a flowchart illustrating an example of a processing procedure of developer information display control executed by the CPU 51a. When the developer information display control is instructed, the CPU 51a confirms whether or not the initial flag F indicating that the printer is in the initial state is in the set state (F = 1) (see step S11 in FIG. 5, and so on). ). The initial flag F is set (F = 1) when the replenishment bottle 41 is mounted on the hopper 22 in the initial state of the printer. Thereafter, the supply bottle 41 is removed, and the reset state (F = 0) is established.

The process (steps S12 to S15) when the initial flag F is in the reset state (F = 0) (“NO” in step S11) will be described later.
When the printer is in the initial state, since the initial flag F is in the set state (F = 1) (“YES” in step S11), the process proceeds to step S16 and the output of the level sensor 22a provided in the hopper 22 is set. Based on this, it is determined whether the supply bottle 41 attached to the hopper 22 is in an empty (empty) state.

When the printer is in the initial state, since the supply bottle 41 is not empty (“NO” in step S16), the process proceeds to step S17. The CPU 51a controls the image forming unit 10, the paper feeding unit 31, and the fixing unit 33 each time a print job instruction is given, and executes a normal printing operation.
In step S17, when a print job is instructed, the CPU 51a sequentially stores print histories such as image data, paper size, and print count data included in the print job in the RAM 51c.

When a normal printing operation is performed, the replenishment motor 44 is rotated based on the toner concentration in the mixing chamber 21 a in the developing device 20 detected by the magnetic sensor 29. As a result, the replenishment screw 22 c is rotated and the developer in the hopper 22 is replenished into the housing 21.
When the amount of the developer in the developing device 20 increases, a part of the carrier is discharged (discarded) together with the toner to the developer collecting container 23 through the discharge port 21m by the trickle discharge mechanism.

  By executing such a normal printing operation, the developer in the supply bottle 41 is consumed. Thereafter, it is detected by the level sensor 22a that the developer level in the hopper 22 has decreased, and further, even when the bottle rotation motor 43 is rotated, the level of the developer detected by the level sensor 22a does not increase. Then, the CPU 51a determines that it is time to replace the supply bottle 41 when the developer in the supply bottle 41 runs out (“YES” in step S16).

  In such a state, the CPU 51a proceeds to step S18, and acquires a print history from the RAM 51c for a predetermined period set up to this point. As a predetermined period in which the print history is acquired in this case, for example, a predetermined number of times of printing is executed in a period in which the developer in the supply bottle 41 attached to the hopper 22 is consumed or just before the developer runs out. Period. In the present embodiment, it is assumed that the print history of the period during which the developer in one supply bottle 41 attached to the hopper 22 is consumed is acquired.

Next, based on the acquired print history, the printing rate in one printing operation is calculated, and the calculated printing rate is classified into one of high printing rate, standard printing rate, and low printing rate. (Step S19). The printing rate in one printing operation is calculated by the number of dots per unit area based on the size of the recording sheet and the number of dots.
In this case, for example, the range of 5 to 15% of the printing rate in each print is determined as the “standard printing rate”, and when the printing rate is larger than 15%, the “high printing rate” is smaller than 5%. Judged as “low printing rate”.

  In this way, when each print image is classified into one of the high print rate, standard print rate, and low print rate, the high print rate is higher than the total number of print operations (total number of prints). The ratio of the number of times of printing operations (number of printed sheets) classified into the standard printing rate and the low printing rate is calculated, and the tendency of the printing rate of the printing operation in the entire period of the acquired printing history is determined (step S20).

  The tendency of the printing rate of the printing operation is, for example, that the ratio of the number of printing times of “high printing rate” to the total number of printings is larger than the rate of printing times of “standard printing rate” and “low printing rate”. % Or more, it is judged as “High printing rate trend”, and the ratio of the number of printing times of “Low printing rate” is higher than the number of printing times of “Standard printing rate” and “High printing rate”. If it is large and is 40% or more, it is determined as “low printing rate tendency”. In other cases, it is determined as “standard printing rate trend”. Therefore, when the ratio of the number of times of printing of “high printing rate” and “low printing rate” is 40%, it is determined as “standard printing rate trend”.

  Next, the process proceeds to step S21, where it is confirmed whether the tendency of the printing rate in the determined printing operation is “high printing rate tendency”. In the case of “high printing rate tendency” (“YES” in step S21), the fact that the low trickle rate supply bottle 41 is appropriate is displayed on the display panel unit 52a provided on the operation panel 52 (step S22). ). Thereafter, the process proceeds to step S26.

When the printing rate tendency of the printing operation is “high printing rate tendency”, the amount of toner consumed for each printing operation is large, so the developer is frequently replenished. As a result, the developer in the housing 21 in the developing device 20 is discharged to the developer recovery container 23 in a relatively short time in which the deterioration of the carrier has not progressed.
However, if the developer replenished to the housing 21 of the developing device 20 is a low trickle-rate developer having a low carrier ratio, the amount of carrier staying in the housing 21 is reduced. The residence time of the carrier becomes relatively long. This relatively increases the time during which the individual carriers are subjected to stirring and mixing. Accordingly, it is possible to reduce the proportion of carriers discharged to the developer recovery container 23 in a state where the individual carriers are not deteriorated.

From this, when the tendency of the printing rate of the printing operation in the predetermined period is “high printing rate tendency”, in order to reduce the rate at which undegraded carriers are discharged into the developer recovery container 23, The display panel unit 52a displays that a trickle-rate developer is suitable.
If the printing rate tendency of the determined printing operation is not “high printing rate trend” in step S21 (“NO” in step S21), the process proceeds to step S23, and the printing rate tendency of the determined printing operation is determined. Confirms whether or not it is “low printing tendency”. In the case of “low printing rate tendency” (“YES” in step S23), the fact that the high trickle rate supply bottle 41 is appropriate is displayed on the display panel 52a provided on the operation panel 52 (step S24). ). Thereafter, the process proceeds to step S26.

When the tendency of the printing rate of the printing operation is “low printing rate tendency”, the amount of consumed toner decreases and the amount of developer to be replenished decreases. Thereby, the carrier in the housing 21 in the developing device 20 stays in the housing 21 for a relatively long time, and the deterioration of the carrier is promoted.
However, if the developer replenished to the housing 21 of the developing device 20 is a high trickle-rate developer having a high carrier ratio, the total carrier amount in the housing 21 increases, so that the discharge of the carrier is promoted. The residence time of the carrier in the housing 21 is shortened. Thereby, the time for which each carrier is subjected to stirring and mixing becomes relatively short, and the progress of deterioration of the individual carrier can be suppressed.

From this, when the tendency of the printing rate of the printing operation in the predetermined period is “low printing rate tendency”, in order to suppress the progress of the deterioration of the carrier in the housing 21, a high trickle rate developer is used. The fact that it is suitable is displayed on the display panel unit 52a.
In step S23, if the trend of the printing rate of the entire printing operation in the predetermined period is not “low printing rate trend” (“NO” in step S23), it is determined as “standard printing rate trend” and the standard trickle rate is changed. The fact that the replenishment bottle 41 is appropriate is displayed on the display panel unit 52a provided on the operation panel 52 (step S25). Thereafter, the process proceeds to step S26.

  In step S26, it is determined whether or not the initial flag F is set (F = 1). If the initial flag F is in the set state (F = 1) (“YES” in step S26), the process proceeds to step S27, the initial flag F is set to the reset state (F = 0), and the process proceeds to step S28. Whether to end the developer information display control is confirmed.

In step S26, if the initial flag F is not set (F = 1), the process proceeds directly to step S28. In step S28, it is confirmed whether or not the developer information display control needs to be ended by an operation of a switch or the like for forcibly terminating the developer information display control, an instruction from the CPU 51a, or the like.
In step S28, when it is not necessary to end the developer information display control (“NO” in step S28), the process returns to step S11. If it is necessary to end the developer information display control in step S28 ("YES" in step S28), the developer information display control is ended.

When the initial flag F is set to the reset state (F = 0) in step S27, it is determined as “NO” in step S11, proceeds to step S12, and is in a standby state until the supply bottle 41 is replaced.
When information related to the trickle rate of the developer to be supplied is displayed on the display panel unit 52a of the operation panel 52, the user usually selects a low trickle rate (5%), standard based on the display on the display panel unit 52a. A replenishment bottle 41 containing either a trickle rate (15%) or a high trickle rate (30%) developer is mounted on the hopper 22.

  When the IC bottle reader 28a detects that the supply bottle 41 is attached to the hopper 22 (“YES” in step S12), the attached supply bottle 41 is displayed on the display panel unit 52a. It is determined whether the replenishment bottle 41 containing the developer is attached (step S31). This determination is based on whether the IC chip reader 28a reads information on the IC chip of the attached supply bottle 41, and the trickle rate of the attached supply bottle 41 matches the trickle rate displayed on the display panel 52a. Based on.

  When the trickle rate of the developer in the attached supply bottle 41 does not match the trickle rate displayed on the display panel unit 52a, the attached supply bottle 41 is not appropriate ("NO" in step S31). A warning is issued (step S32). In this case, the process returns to step S <b> 12 and a warning is issued until the appropriate trickle rate supply bottle 41 is mounted on the hopper 22.

As a warning in this case, for example, the warning lamp 52b provided on the operation panel 52 is turned on. Further, it may be displayed that the supply bottle 41 attached to the display panel portion 52a of the operation panel 52 is not appropriate, or a warning sound may be generated by the speaker 52d. Furthermore, these may be combined.
Note that the warning in step S32 may be stopped after a predetermined time has elapsed. Further, the developer information display control may be terminated without returning to step S12 after the warning is issued in step S32.

Further, in step S32, instead of a configuration for issuing a warning, a configuration for prohibiting the printing operation may be employed.
If the supply bottle 41 attached to the hopper 22 is in an appropriate state that matches the trickle rate displayed on the display panel 52a (“YES” in step S31), the process proceeds to step S33, where a warning is given. Check if is issued. If a warning is issued (“YES” in step S33), the warning is terminated (step S34), and the process proceeds to step S15. If no warning is issued (“NO” in step S33), The process proceeds directly to step S15. In step S15, the information regarding the trickle rate displayed on the display panel unit 52a is cleared.

  After that, the CPU 51a controls each of the image forming unit 10, the paper feeding unit 31, and the fixing unit 33 each time a print job instruction is given until the attached supply bottle 41 becomes empty. The print operation is executed, and the print history such as the image data for each print job, the paper size, the number of prints, and the like is sequentially stored in the RAM 51c (step S17). When the attached supply bottle 41 becomes empty, the processing from step S18 onward is executed.

As described above, when the printing rate tendency of the printing operation within a predetermined period determined based on the printing history is a high printing rate tendency, the supply bottle 41 containing the low trickle-rate developer is attached to the hopper 22. When the printing operation is performed, the amount of carrier contained in the amount of developer to be discarded can be reduced.
FIG. 6 is a graph showing that the amount of discarded carrier can be reduced by using a developer having a low trickle rate. In this graph, when a printing operation is continuously executed at a printing rate of 80% using a developer with a trickle rate of 20%, 15%, 10%, and 5%, the developer is discharged into the developer collection container 23 ( The ratio of the amount of carrier contained in the developer to be discarded (the amount of discarded carrier) is shown with the amount of discarded carrier in the developer having a trickle rate of 20% as 1, respectively.

  As is apparent from the graph of FIG. 6, when the printing operation is performed at a high printing rate of 80%, the amount of waste carrier is reduced as the developer has a lower trickle rate. Therefore, when the printing operation within a predetermined period tends to have a high printing rate, by using a developer having a trickle rate lower than 20%, it is possible to reduce the amount of discarded carrier and improve economy. be able to.

Further, when the printing operation within a predetermined period tends to have a low printing rate, if the replenishing bottle 41 containing the developer with a high trickle rate is mounted on the hopper 22 and the printing operation is executed, the image quality of the printed image is improved. Reduction and toner scattering can be suppressed.
FIG. 7A shows a case where a replenishment bottle containing a high trickle rate (30%) developer is continuously used when a printing operation with a low printing rate of 3% is continuously executed. 8 is a graph conceptually showing that it is possible to prevent the occurrence of fogging in a printed image. In this case, as shown by a solid line in FIG. 7A, low printing is performed with a developer having a high trickle rate (30%). In the case where the rate printing operation is continuously executed, the printed image is not fogged.

  In contrast, when a printing operation with a low printing rate of 3% is continuously performed, a replenishment bottle containing a low (5%) or standard (15%) trickle rate developer is used. If it continues to be used, after the replacement with the third supply bottle, as shown by the broken line in FIG. In addition, the dashed-dotted line in Fig.7 (a) is an average value of the range shown with a broken line.

  FIG. 7B shows a case where a replenishment bottle containing a high trickle rate (30%) developer is continuously used when a printing operation with a low printing rate of 3% is continuously executed. FIG. 7 is a graph conceptually showing that it is possible to prevent a drop in the granularity of dots in a print image. In this case, as shown by a solid line in FIG. There is no decline in sex.

  In contrast, when a printing operation with a low printing rate of 3% is continuously performed, a replenishment bottle containing a low (5%) or standard (15%) trickle rate developer is used. If it continues to be used, after it is replaced with the third supply bottle, as shown by the broken line in FIG. In addition, the dashed-dotted line in FIG.7 (b) is an average value of the range shown with a broken line.

  FIG. 7C shows a case where a replenishment bottle containing a high trickle rate (30%) developer is continuously used when a printing operation with a low printing rate of 3% is continuously executed. 7 is a graph conceptually showing that toner scattering can be prevented from occurring around the developing device 20, and in this case, toner scattering does not occur as shown by a solid line in FIG. 7C.

  In contrast, when a printing operation with a low printing rate of 3% is continuously performed, a replenishment bottle containing a low (5%) or standard (15%) trickle rate developer is used. If it continues to be used, after the replacement with the third supply bottle, as shown by the broken line in FIG. 7C, toner scattering occurs. In addition, the dashed-dotted line in FIG.7 (c) is an average value of the range shown with a broken line.

  FIG. 7D shows a case where a replenishment bottle containing a high trickle rate (30%) developer is continuously used when a printing operation with a low printing rate of 3% is continuously executed. FIG. 7 is a graph conceptually showing that a reduction in fine line reproducibility in a printed image can be prevented. In this case, as shown by a solid line in FIG. Absent.

  In contrast, when a printing operation with a low printing rate of 3% is continuously performed, a replenishment bottle containing a low (5%) or standard (15%) trickle rate developer is used. If it continues to be used, the thin line reproducibility in the printed image decreases after the replacement with the third supply bottle, as indicated by the broken line in FIG. In addition, the dashed-dotted line in FIG.7 (d) is an average value of the range shown with a broken line.

As described above, when the printing rate tendency of the printing operation is a low printing rate tendency, the use of a high trickle-rate developer can suppress degradation of the image quality of the printed image and toner scattering.
The numerical values such as “printing rate” and “trickle rate” in the above description are merely examples, and are not limited to these numerical values.

[Modification]
In the above-described embodiment, the overall tendency of the printing operation in a predetermined period is determined based on the printing rate. However, based on the toner consumption amount per unit area obtained by the toner density or the like, in the predetermined period. The overall tendency of the printing operation may be determined.

In the above-described embodiment, the supply bottle 41 is provided with the IC chip 41a in which information related to the trickle rate, which is the carrier ratio of the stored developer, is provided. However, the present invention is not limited to such a configuration.
For example, a detecting unit that detects the shape of the replenishment bottle 41 attached to the hopper 22 of the developing device 20 by changing the shape of the replenishment bottle 41 according to the carrier ratio of the stored developer is provided. The attached replenishment bottle 41 may be configured to issue a warning when the determined trickle-rate developer is not stored.

Furthermore, when it is determined that the replenishment bottle 41 containing a predetermined trickle-rate developer is appropriate, only the replenishment bolt 41 containing the trickle-rate developer can be attached to the hopper 22. The replenishing bolt 41 containing another trickle-rate developer may not be attached to the hopper 22.
For example, the developer contained therein has differently shaped protrusions at different positions with respect to the supply bolts 41 of low trickle rate (5%), standard trickle rate (15%), and high trickle rate (30%). A recess is provided in the hopper 22 so that each protrusion can be inserted. Further, each of the recesses is provided with a shielding plate that is displaced between a state in which no projection is inserted and a state in which the projection is inserted, and a displacement means that displaces each shielding plate.

  In this case, it is provided in each recess so that the corresponding protrusion of the replenishment bottle 41 is not inserted into each of the recesses other than the recess corresponding to the protrusion of the replenishment bottle 41 containing the appropriate trickle-rate developer. Each of the shield plates is displaced. As a result, the supply bottles 41 of a type other than the supply bottle 41 in which an appropriate trickle-rate developer is accommodated cannot be attached to the hopper 22.

  The image forming apparatus according to the present invention can be applied not only to a printer that forms a monochrome image, but also to a copying machine, a FAX, an MFP (Multiple Function Peripheral) that can form a color or monochrome image. In the case of an image forming apparatus that forms a color image, the tendency of toner consumption in the entire printing operation in a predetermined period is determined for each color developing device based on information on the toner consumption. .

  INDUSTRIAL APPLICABILITY The present invention is useful as a technique capable of setting a replenished developer to a carrier ratio corresponding to a printing operation in an image forming apparatus having a developing device using a two-component developer having a toner and a carrier.

DESCRIPTION OF SYMBOLS 10 Image process part 11 Photoconductor drum 20 Developing apparatus 21 Housing 21a Mixing chamber 21b Developing chamber 21c Partition 21d 1st opening 21e 2nd opening 21f Developer inflow part 21g Developer discharge part 21m Discharge port 21n Restriction board 22 Hopper 22a Level sensor 22c Replenishment screw 23 Developer recovery container 24 Stirring screw 24a Shaft 24b Spiral blade 25 Supply screw 25a Shaft 25b First spiral blade 25c Reverse winding spiral blade 25d Second spiral blade 25e Partition plate 27 Developing roller 27a Developing sleeve 27b Magnet body 28 Bottle holder 28a IC chip reader 41 Supply bottle 41a IC chip 43 Bottle rotation motor 51 Control unit 52 Operation panel 52a Display panel unit

Claims (7)

While developing the electrostatic latent image formed on the photoconductor using a developer containing a carrier and toner, at least a part of the carrier is supplied while replenishing the developer from a supply container that can be replaced. An image forming apparatus including a developing device for discharging,
Replacement time detection means for detecting the replacement time of the replenishing container;
Determination means for determining a tendency of toner consumption in a printing operation executed within a predetermined period until the replacement time detected by the replacement time detection means;
Developer information generating means for generating information relating to a carrier ratio suitable as a developer replenished from the replenishing container based on the determination result of the determining means;
Output means for outputting the information generated by the developer information generating means;
An image forming apparatus comprising:   The determination means calculates a printing rate for each printing operation, classifies all printing operations executed during the predetermined period based on a preset printing rate range, and sets each printing rate. The image forming apparatus according to claim 1, wherein a tendency of the printing rate is determined as a tendency of toner consumption of the executed printing operation based on the number of printing operations classified into the range.   The developer information generation unit generates information on a low carrier ratio when the determination unit determines that the toner consumption tends to be high and the determination unit determines that the toner consumption tends to be low The image forming apparatus according to claim 1, wherein information on a high carrier ratio is generated.   4. The developing device according to claim 1, wherein a plurality of types of replenishing containers each containing a developer set at a different carrier ratio are selectively detachable. 5. The image forming apparatus described in 1.   The image forming apparatus according to claim 4, wherein the developer information generation unit generates information related to a type of supply container suitable for a tendency of toner consumption determined by the determination unit.   The image forming apparatus according to claim 5, wherein the developing device includes an acquisition unit configured to acquire information related to a carrier ratio of the developer in the attached supply container.   The apparatus further comprises warning means for issuing a warning when the information on the carrier ratio of the developer acquired by the acquiring means is different from the information on the type of supply container generated by the developer information generating means. The image forming apparatus according to claim 6.

Images