JP2000258986A - Image forming apparatus and developing apparatus - Google Patents

Abstract

[PROBLEMS] To provide an image forming apparatus capable of stably detecting the remaining amount of a non-magnetic one-component developer and a developing apparatus used in the image forming apparatus. SOLUTION: Of the side walls of a case 51 forming a toner storage chamber 52 of a developing device 50, light transmitting windows 56b (and 56a (FIG. 2)
Are provided, and a light-emitting element and a light-receiving element (not shown) are provided outside the case 51 so as to face the light transmission windows 56b. The toner in the toner storage chamber 52 is transported to the developing chamber 57 through the opening A by the rotation of the agitator 53, and the toner in the developing chamber 57 is supplied to the supply roller 58.
Is carried on a developing roller 59 formed of silicone rubber. The carried toner is held between the contact portion 64b of the layer thickness regulating member 64 and the developing roller 59, and the contact portion 64b is formed of silicone rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a developer remaining amount detecting means for optically detecting a remaining amount of a developer in a developer chamber, and a developing device used in the image forming apparatus. It belongs to the technical field.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, the remaining amount of developer in a developing device is detected, and when the remaining amount falls below a predetermined value, the developer is urged to be replenished. Things are common. There are various types of methods for detecting the remaining amount of the developer, but, as an example, a pair of light transmission windows are arranged opposite to each other in a developer chamber of a developing device.
A light-emitting element and a light-receiving element are arranged outside the developing device so as to face the light-transmitting window, and light having substantially parallel optical axes emitted from the light-emitting element and transmitted through the light-transmitting window is received by the light-receiving element. Then, there is a method of detecting the remaining amount of the developer in the developer chamber according to the light receiving state.

In a developing apparatus employing such a method, if the developer adheres to the light transmitting window of the developer chamber, it becomes impossible to accurately detect the remaining amount of the developer. Cleaning member is provided in the developer chamber.
Further, the developer chamber is provided with a developer stirring and conveying member for stirring and conveying the developer in the developer chamber while rotating, and the cleaning member is formed integrally with the developer stirring and conveying member. Then, it is configured to perform cleaning by slidingly contacting the light transmitting window while rotating.

[0004]

However, even when such a cleaning member is provided, it is difficult to accurately detect the remaining amount of the developer in the developer chamber by the above-described method.

For example, conventionally, as described in JP-A-7-56431 or JP-A-9-34238, after a light transmitting window is cleaned with a cleaning member, the developer is agitated and transported from a developer stirring and conveying member. In general, a method of measuring the time until the light falls and interrupts the optical path has been used. However, in such a method, as described in Japanese Patent Application Laid-Open No. Due to the difference, the fluidity of the developer changes, so that the timing at which the developer drops from the developer stirring and conveying member changes, and it is not possible to detect the remaining amount of the developer stably.

In particular, in a developing method using a non-magnetic one-component developer, it is necessary to rub the developer between the layer thickness regulating member and the developing roller in order to uniformly charge the developer. Therefore, the external additive added to the developer for the purpose of imparting fluidity is embedded in the base particles of the developer over a long period of use, and the fluidity of the developer gradually decreases. Then, the developer having such reduced fluidity is returned from the side of the developing chamber in which the developing roller is disposed to the side of the developer chamber by following the circulation path of the developer. As a result, when the amount of the developer having reduced fluidity in the developer chamber increases, the time during which the developer falls from the developer stirring and conveying member fluctuates as described above, and it becomes impossible to stably detect the remaining amount of the developer. There was a problem.

Accordingly, the present invention solves such a problem, and an image forming apparatus and an image forming apparatus capable of stably detecting the remaining amount of developer even when a non-magnetic one-component developer is used. It is an object of the present invention to provide a developing device used for the above.

[0008]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a developer chamber for storing a non-magnetic one-component developer; A developing chamber provided in the developing chamber for carrying and transporting a developer, a light transmitting window provided in the developer chamber, a light emitting element and a light receiving element, and a light emitting element and a light receiving element. Developer remaining amount detecting means for detecting a remaining amount of developer in the developer chamber based on a light receiving state of the irradiated light transmitted through the light transmitting window in the light receiving element, and a rubber pressed against the developer carrier A pressure member formed of a member; and a layer thickness regulating member for forming a thin layer of the developer on the developer carrier.

According to the image forming apparatus of the first aspect, the nonmagnetic material supplied from the developer chamber to the developing chamber via the opening is provided.
The component developer is carried by the developer carrier, and is conveyed to a pressing portion between the layer thickness regulating member and the developer carrier. In the pressing portion, a pressing member of the layer thickness regulating member is pressed against the developer carrier, and the developer is conveyed while being sandwiched between the pressing member and the developer carrier. The developer is transferred to the developer chamber from the developer chamber, or is carried on the developer carrier in the developer chamber, and further, due to the contact between the pressing member and the developer carrier in the pressing portion, triboelectric charge is generated. Is given. Then, a part of the developer that has passed through the pressing portion is used for development and consumed, and the rest is a developing chamber.
Alternatively, the developer is returned to the developer chamber and is again subjected to development. On the other hand, in the non-magnetic one-component developer, an external additive is generally externally added to the toner base particles, and in the pressing portion, the external additive is externally added to the toner base particles. The pressing member receives the pressing force. However, since the pressing member is formed of a rubber member, the pressing member having rubber elasticity is deformed in accordance with the shape of the external additive slightly projecting from the toner base particles, and the pressing member against the external additive is deformed. The pressure will be reduced. Therefore, the embedding of the external additive into the toner base particles is significantly reduced, and the developer that has passed through the pressing portion circulates as described above without decreasing the fluidity. As described above, since the developer in the developer chamber does not decrease in fluidity, the developer does not shift in the developer chamber, and even when the developer is stirred in the developer chamber along with the transport operation to the developer chamber. The time required to return to a stable state is kept substantially constant. As a result, the developer remaining amount detection means detects the remaining amount of the developer in the developer chamber based on the light receiving state of the light emitted from the light emitting element and transmitted through the light transmitting window in the light receiving element. It is performed accurately and stably without depending on the length of the use period.

According to a second aspect of the present invention, there is provided an image forming apparatus according to the first aspect, wherein the developer carrying member is formed of a conductive rubber member. Features.

According to the image forming apparatus of the present invention,
The developer conveyed to the pressing portion between the layer thickness regulating member and the developer carrier is pressed by the pressing member of the layer thickness regulating member and the developer carrier at the pressing portion. Since the developer carrier is formed of a rubber member and the developer carrier is also formed of a rubber member, the pressing member and the developer carrier having rubber elasticity in the shape of the external additive slightly projecting from the toner base particles are provided. As a result, the pressure from the pressing member against the external additive is further reduced. Therefore, the embedding of the external additive into the toner base particles is significantly reduced, and the developer that has passed through the pressing portion is circulated and returned to the developer chamber as described above without decreasing the fluidity. As a result, the fluidity of the developer in the developer chamber does not decrease, and the detection of the remaining amount of the developer in the developer chamber can be performed more accurately and stably without depending on the length of use of the image forming apparatus. Done.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, in the image forming apparatus according to the first or second aspect, the image forming apparatus is rotatably provided inside the developer chamber, and is provided inside the developer chamber. The image forming apparatus further includes a developer stirring and conveying member that stirs the developer and conveys the developer to the developing chamber through the opening.

According to the third aspect of the present invention, when the developer stirring / conveying member rotates inside the developer chamber, the developer contained in the developer chamber is agitated, and some of the developer is opened. The developer is conveyed from the developer chamber to the developing chamber through the section, and the remaining developer falls from the developer stirring and conveying member and returns to the original position. A part of the developer transported to the developing chamber is circulated and returned to the developer chamber as described above. Therefore, the developer agitated and transported by the developer agitating and transporting member includes the developer pressed by the pressing portion between the layer thickness regulating member and the developer carrying member. Since the property does not decrease even after the pressing, the time required for the developer to fall from the developer stirring / conveying member and return to the original position does not change even when the image forming apparatus is used for a long period of time. Also,
It does not cause the bias of the developer in the developer chamber. As a result, the detection of the remaining amount of the developer in the developer chamber is performed accurately and stably without depending on the length of use of the image forming apparatus.

According to a fourth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to third aspects, wherein the developer has at least two kinds of particles having different particle diameters. Is externally added.

According to the image forming apparatus of the present invention, the external additive having a large particle diameter functions as a spacer for the external additive having a small particle diameter, and the external additive having a small particle diameter is applied to the toner base particles. Burying is more reliably prevented. Therefore,
A decrease in the fluidity of the developer is more reliably prevented, and the remaining amount of the developer in the developer chamber is accurately and stably detected regardless of the length of the use period of the image forming apparatus.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, an external additive having a minimum particle diameter is added to the developer. At least two types of externally-added developer combined with an external additive having a minimum particle size and another external additive such that the fluidity thereof is lower than that of the externally-added developer alone It is characterized in that an external additive is externally added.

According to the image forming apparatus of the fifth aspect, of the at least two types of external additives, the external additive having the minimum particle size is
Other external additives that keep the flowability of the developer good and reduce the flowability of the developer by using in combination with an external additive having a minimum particle size include:
It has a spacer effect of preventing the external additive having a large particle diameter and the minimum particle diameter from being embedded in the toner. As a result, even when the image forming apparatus is used for a long time, the embedding of the external additive into the toner in the layer thickness regulating member and the pressing portion of the developer carrier is reduced, and the fluidity of the developer is good. Is kept. Therefore, the bias of the developer in the developer chamber is prevented, and the time required to return to a stable state is kept substantially constant even when the developer moves in the developer chamber with the transfer operation to the developer chamber. . As a result, the detection of the remaining amount of the developer in the developer chamber by the remaining developer amount detecting means is performed accurately and stably without depending on the length of the use period of the image forming apparatus.

According to a sixth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to fifth aspects, wherein at least the pressing member is made of silicone. It is characterized by being formed of rubber.

According to the image forming apparatus of the sixth aspect, in the pressing portion between the layer thickness regulating member and the developer carrier, the developer is contacted with the pressing member of the layer thickness regulating member and the developer carrier. , Provided with a triboelectric charge. The charging characteristics at this time vary depending on the materials of the pressing member and the developer carrying member. Among them, silicone rubber has particularly good charging characteristics with respect to the developer. Therefore, when the pressing member is formed of silicone rubber, a sufficient triboelectric charge is applied to the developer with a lower pressing force than when the pressing member is formed of another rubber member. Then, when the pressing force from the pressing member to the developer is reduced, the embedding of the external additive into the toner base particles is more reliably prevented,
A decrease in the fluidity of the developer is more reliably prevented. As a result, the detection of the remaining amount of the developer in the developer chamber by the remaining developer amount detecting means is performed accurately and stably without depending on the length of the use period of the image forming apparatus.

According to a seventh aspect of the present invention, there is provided an image forming apparatus according to any one of the first to sixth aspects, wherein the developer is a polymer prepared by a polymerization method. It is a toner.

According to the image forming apparatus of the present invention,
By using a polymerized toner produced by a polymerization method as a developer, extremely high fluidity can be obtained,
The detection of the remaining amount of the developer in the developer chamber by the developer remaining amount detecting means is performed more accurately and stably. The polymerized toner generally has low mechanical strength and easily embeds an external additive. However, according to the present invention, as described above, the polymer toner does not adhere to the toner base particles at the pressing portion between the layer thickness regulating member and the developer carrier. Since the embedding of the additive is reliably prevented, the polymer toner can maintain extremely high fluidity.

In order to solve the above problem, the developing device according to the present invention includes a light emitting element and a light receiving element, and the developer remaining based on a light receiving state of the light emitted from the light emitting element in the light receiving element. A developing device attached to an image forming apparatus including a developer remaining amount detecting unit that detects an amount,
A developer chamber accommodating a non-magnetic one-component developer, a developing chamber communicating with the developer chamber via an opening, a developer carrier provided in the developing chamber for carrying and transporting a developer; A light transmitting window that is provided in the developer chamber and transmits light received from the light emitting element and received by the light receiving element; and a pressing member formed of a rubber member pressed against the developer carrier, A layer thickness regulating member for forming a thin layer of the developer on the developer carrier.

According to the developing device of the present invention, the non-magnetic one-component developer supplied from the developer chamber to the developing chamber via the opening is carried by the developer carrier, and the layer thickness regulating member is provided. And the developer carrying member. In the pressing portion, a pressing member of the layer thickness regulating member is pressed against the developer carrier, and the developer is conveyed while being sandwiched between the pressing member and the developer carrier. The developer is transferred to the developer chamber from the developer chamber, or is carried on the developer carrier in the developer chamber, and further, due to the contact between the pressing member and the developer carrier in the pressing portion, triboelectric charge is generated. Is given. Then, a part of the developer that has passed through the pressing portion is used for development and consumed, and the rest is returned to the developing chamber or the developer chamber and is again used for development. on the other hand,
In the non-magnetic one-component developer, an external additive is generally added to the toner base particles. In the pressing portion, the external member is externally added to the toner base particles, and the pressing member of the layer thickness regulating member is pressed. Will be pressed. However, since the pressing member is formed of a rubber member, the pressing member having rubber elasticity is deformed in accordance with the shape of the external additive slightly projecting from the toner base particles, and the pressing member against the external additive is deformed. The pressure will be reduced. Therefore, the embedding of the external additive into the toner base particles is significantly reduced, and the developer that has passed through the pressing portion circulates as described above without decreasing the fluidity. As described above, since the developer in the developer chamber does not decrease in fluidity, the developer does not shift in the developer chamber, and even when the developer is stirred in the developer chamber along with the transport operation to the developer chamber. The time required to return to a stable state is kept substantially constant. As a result, the remaining amount of the developer in the developer chamber is determined by the remaining amount of the developer in the image forming apparatus based on the light receiving state of the light emitted from the light emitting element and transmitted through the light transmitting window in the light receiving element. The detection is performed accurately and stably without depending on the length of the use period of the developing device.

According to a ninth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to the eighth aspect, the developer carrier is formed of a conductive rubber member. And

According to the developing device of the ninth aspect, the developer conveyed to the pressing portion between the layer thickness regulating member and the developer carrier is pressed by the pressing member of the layer thickness regulating member and the developer at the pressing portion. Although the pressing member is pressed, the pressing member is formed of a rubber member, and the developer supporting member is also formed of a corresponding rubber member. The pressing member and the developer carrier having rubber elasticity in the shape of the additive are deformed, and the pressure from the pressing member on the external additive is further reduced.
Therefore, embedding of the external additive into the toner base particles is as follows.
The developer that has been significantly reduced and passed through the pressing portion is circulated and returned to the developer chamber as described above without reducing the fluidity. As a result, the flowability of the developer in the developer chamber does not decrease, and the detection of the remaining amount of the developer in the developer chamber can be performed more accurately and stably without depending on the length of the use period of the developing device. Let it do.

According to a tenth aspect of the present invention, in order to solve the above problem, in the developing device according to the eighth or ninth aspect, the developing device is rotatably provided inside the developer chamber, and the developer in the developing chamber is provided. And a developer stirring / conveying member for conveying the developer to the developing chamber via the opening.

According to the tenth aspect of the present invention, when the developer stirring / conveying member rotates inside the developer chamber, the developer contained in the developer chamber is stirred, and a part of the developer is opened. The developer is conveyed from the developer chamber to the developing chamber via, and the remaining developer falls from the developer stirring and conveying member and returns to the original position. A part of the developer transported to the developing chamber is circulated and returned to the developer chamber as described above. Therefore, the developer agitated and transported by the developer agitating and transporting member includes the developer pressed by the pressing portion between the layer thickness regulating member and the developer carrying member. Since the property does not decrease even after the pressing, the time required for the developer to fall from the developer stirring and conveying member to return to the original position does not change even when the developing device is used for a long period of time. Further, the bias of the developer is not caused in the developer chamber. As a result, the remaining amount of the developer in the developer chamber is accurately and stably detected regardless of the length of the use period of the developing device.

According to an eleventh aspect of the present invention, in order to solve the above problem, the developing device according to any one of the eighth to tenth aspects, wherein the developer has at least two particles having different particle diameters.
It is characterized in that various kinds of external additives are externally added.

According to the developing device of the eleventh aspect, the external additive having a large particle diameter functions as a spacer for the external additive having a small particle diameter, and the external additive having a small particle diameter is buried in the toner base particles. Is more reliably prevented. Accordingly, a decrease in the fluidity of the developer is more reliably prevented, and the remaining amount of the developer in the developer chamber is accurately and stably detected regardless of the length of the use period of the developing device.

According to a twelfth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to any one of the eighth to tenth aspects, the developer comprises only an external additive having a minimum particle diameter. At least two types of external additives that are combined so that the external additive having a minimum particle size and another external additive are used in combination with the external additive so that the fluidity is lower than the external additive. It is characterized in that the agent is externally added.

According to the developing device of the twelfth aspect, out of the at least two types of external additives, the external additive having the minimum particle diameter can maintain good flowability of the developer and can have the minimum particle diameter. Other external additives that reduce the fluidity of the developer when used in combination with the above have a large particle size and exhibit a spacer effect of preventing the external additive having the minimum particle size from being embedded in the toner. As a result, even when the image forming apparatus is used for a long time, the embedding of the external additive into the toner in the layer thickness regulating member and the pressing portion of the developer carrier is reduced, and the fluidity of the developer is good. Is kept. Therefore, the bias of the developer in the developer chamber is prevented, and the time required to return to a stable state is kept substantially constant even when the developer moves in the developer chamber with the transfer operation to the developer chamber. . As a result, the remaining amount of the developer in the developer chamber can be accurately and stably detected by the developer remaining amount detecting means regardless of the length of the use period of the developing device.

According to a thirteenth aspect of the present invention, in order to solve the above problem, in the developing device according to any one of the eighth to twelfth aspects, at least the pressing member is made of silicone rubber. It is characterized by being formed.

According to the developing device of the thirteenth aspect, in the pressing portion between the layer thickness regulating member and the developer carrier, the developer is brought into contact with the pressing member of the layer thickness regulating member and the developer carrier. , Provided with a triboelectric charge. The charging characteristics at this time vary depending on the materials of the pressing member and the developer carrying member. Among them, silicone rubber has particularly good charging characteristics with respect to the developer. Therefore, when the pressing member is formed of silicone rubber, a sufficient triboelectric charge is applied to the developer with a lower pressing force than when the pressing member is formed of another rubber member. Then, when the pressing force from the pressing member to the developer is reduced, the embedding of the external additive into the toner base particles is more reliably prevented,
A decrease in the fluidity of the developer is more reliably prevented. As a result, the remaining amount of the developer in the developer chamber can be accurately and stably detected by the developer remaining amount detecting means regardless of the length of the use period of the developing device.

According to a fourteenth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to any one of the eighth to thirteenth aspects, the developer is produced by a polymerization method. Characterized by being a polymerized toner.

According to the developing device of the present invention, an extremely high fluidity can be obtained by using a polymerized toner produced by a polymerization method as the developer, and the developer is detected by the developer remaining amount detecting means. The remaining amount of the developer in the room is more accurately and stably detected. The polymerized toner generally has low mechanical strength and easily embeds an external additive. However, according to the present invention, as described above, the polymer toner does not adhere to the toner base particles at the pressing portion between the layer thickness regulating member and the developer carrier. Since the embedding of the additive is reliably prevented, the polymer toner can maintain extremely high fluidity.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First, an overview of the entire image forming apparatus according to the present embodiment will be described.

FIG. 1 is a sectional view showing a schematic configuration of a laser beam printer 1 as an embodiment of the image forming apparatus of the present invention. In FIG. 1, the laser beam printer 1 includes a feeder unit for feeding paper (not shown) at the bottom of a main body case 2. The feeder unit includes a paper pressing plate 10 that is pressed by a spring (not shown), a paper feeding roller 11, and a friction separating member 14. The uppermost sheet is separated between the feed roller 11 and the friction separating member 14 by the rotation of the roller, and the sheet is supplied at a predetermined timing.

A pair of registration rollers 12 and 13 are rotatably supported on the downstream side in the sheet transport direction by the rotation of the paper supply roller 11 rotating in the direction of the arrow in FIG. The sheet is conveyed to a transfer position formed by the transfer roller 21 at a predetermined timing.

The photosensitive drum 20 is made of a positively chargeable material, for example, an organic photoreceptor mainly composed of positively chargeable polycarbonate. More specifically, the photosensitive drum 20 has, for example, a cylindrical aluminum sleeve as a main body, and has a predetermined thickness (for example, about 20 μm) in which a photoconductive resin is dispersed in polycarbonate on an outer peripheral portion thereof. It is composed of a hollow drum on which a conductive layer is formed, and is rotatably supported by the main body case 2 with the cylindrical sleeve grounded. Further, the photosensitive drum 20 is driven to rotate in a direction indicated by an arrow by driving means (not shown).

The charger 30 is constituted by a scorotron type charger for positive charging for generating corona discharge from a charging wire made of, for example, tungsten.

The laser scanner unit 40 includes a laser generator (not shown) for generating a laser beam L for forming an electrostatic latent image on the photosensitive drum 20, and a polygon mirror (pentahedral mirror) 41 that is driven to rotate. , A pair of lenses 42 and 4
5 and reflection mirrors 43, 44 and 46.

In the developing device 50, a toner storage chamber 52 as a developer chamber is formed in a case 51, and the toner storage chamber 5 is formed.
Inside 2, an agitator 53 as a stirring and conveying member and a cleaning member 54 are provided rotatably around a rotation shaft 55. The toner accommodating chamber 52 accommodates a positively chargeable nonmagnetic one-component developer having electrical insulation. Further, the rotation shaft 5 of the toner storage chamber 52 is provided.
Light-transmitting windows 56 are provided on the side walls located at both ends of 5. On the photosensitive drum 20 side of the toner accommodating chamber 52, a developing chamber 57 for performing development by communicating with the toner accommodating chamber 52 through an opening A is formed, and a supply roller 58 and a developing roller 59 are rotatably supported. . The toner on the developing roller 59 is a thin plate-shaped elastic layer regulating blade 64 having elasticity.
Is regulated to a predetermined layer thickness, and is subjected to development.

The transfer roller 21 is rotatably pivotally supported,
It is made of a conductive foamed elastic body made of silicone rubber or urethane rubber. The transfer roller 21 is configured to reliably transfer the toner image on the photosensitive drum 20 to the paper by the applied voltage.

The fixing unit 70 includes the registration roller 12
The heating roller 71 and the pressing roller 72 are provided on the further downstream side in the sheet conveyance direction from the sheet feeding roller 13 to the pressure contact portion between the photosensitive drum 20 and the transfer roller 21. The toner image transferred to the sheet is heated and pressed while being conveyed by the heating roller 71 and the pressing roller 72 and is fixed on the sheet.

A pair of transport rollers 73 and a discharge roller 74 for transporting the paper are provided on the downstream side of the fixing unit 70 in the transport direction, and a discharge tray 75 is provided on the downstream side of the paper discharge roller 74. Have been.

The above-described photosensitive drum 20, transfer roller 21, charger 30, and developing device 50 are housed in a drum cartridge 2a, and the drum cartridge 2a is detachably attached to the laser beam printer 1. Is provided. Further, the developing device 50 is provided detachably as a developing device cartridge with respect to the drum cartridge 2a.

In the laser beam printer 1 of the present embodiment as described above, the surface of the photosensitive drum 20 is
When the laser beam L modulated according to image information is emitted from the laser scanner unit 40, an electrostatic latent image is formed on the surface of the photosensitive drum 20.
This electrostatic latent image is visualized with toner by the developing device 50, and the visible image formed on the photosensitive drum 20 is transported by the photosensitive drum 20 to a transfer position. At the transfer position, the paper is supplied via the paper feed roller 11 and the registration rollers 12 and 13, and the visible image is transferred to the paper by a transfer bias applied by the transfer roller 21. The toner remaining on the photosensitive drum 20 after the transfer is collected in the developing chamber 57 by the developing roller 59.

Next, the sheet is conveyed to the fixing unit 70, is nipped and conveyed by the heating roller 71 and the pressing roller 72 of the fixing unit 70, and the visible image on the sheet is pressed and heated to be fixed on the sheet. You. Then, the sheet is discharged to the discharge tray 75 above the laser beam printer 1 by the pair of transport rollers 73 and the discharge rollers 74, and the image forming operation is completed.

(Structures of Developing Device and Developer Remaining Detecting Means) According to the laser beam printer 1 of the present embodiment, the toner in the toner accommodating chamber 52 is consumed with the image forming operation as described above. In order to prevent a decrease in image quality due to a shortage of toner, it is necessary to detect a decrease in the remaining amount of toner at an appropriate timing and supply toner as needed. Therefore, in the present embodiment, the developing device 50 is configured as described below, and includes the following developer remaining amount detecting means. Hereinafter, a detailed configuration of the developing device 50 and the developer remaining amount detecting unit according to the present embodiment will be described with reference to FIGS.

FIG. 2 is a cross-sectional view of the developing device 50 of this embodiment taken along the line YY ′ shown in FIG. 3, and FIGS. 3 and 4 are XX ′ of FIG. 2 of the developing device 50 of this embodiment. It is a figure which shows the cross section of a line. However, FIG. 3 is a diagram when the agitator 53 and the cleaning member 54 are at positions shown by two-dot chain lines in FIG. Also, in FIG. 3, the frame 2b,
Light emitting means 60, light receiving means 61, and substrates 60b, 61b
Are drawn as cross-sections, but these are Z in FIG.
It is a cross section in the -Z 'line.

As described above, the developing device 50 according to the present embodiment has a case 51 as shown in FIG. 2 in which other components are provided in a case 51 as a developing device cartridge.
4 is detached from the drum cartridge 2a shown in FIG. 4, or is attached to the drum cartridge 2a. Accordingly, the case 51 forms the toner storage chamber 52 and the developing chamber 57 and also functions as a frame that supports each component.

Next, components other than the case 51 will be described. First, a developing roller 5 as a developer carrier
9, a cylindrical base 59b formed of conductive silicone rubber containing fine particles of conductive carbon is provided on a cored bar 59a formed of stainless steel or the like. A coat layer 59c of a resin or rubber material containing fluorine is formed on 59b. The base of the developing roller 59 does not necessarily have to be made of conductive silicone rubber, and may be made of conductive urethane rubber. A predetermined voltage is applied to the developing roller 59 by a power supply (not shown), and the developing roller 59 has a predetermined potential difference with the photosensitive drum 20.

Layer thickness regulating blade 6 as layer thickness regulating member
4 is made of stainless steel or the like, and has a developing device 50 at its base end.
A supporting portion 64a fixed to the case 51, and a contact portion 64b provided at a tip of the supporting portion 64a and serving as a pressing member formed of insulating or conductive silicone rubber.
And The contact portion 64b is pressed against the developing roller 59 by the elastic force of the support portion 64a. In the present embodiment, the contact portion 64b is formed to have a substantially half-moon-like convex shape in cross section as shown in FIG. 2, but may be formed in a plate shape.

The supply roller 58 is a roller in which a cylindrical base member 58b formed of a conductive sponge is formed on a metal core 58a formed of stainless steel or the like. They are arranged so as to be pressed by elastic force. In addition, as the supply roller 58, an appropriate member such as conductive silicone rubber or urethane rubber can be used.

The toner accommodated in the toner accommodating chamber 52 is a positively-charged non-magnetic one-component developer, and a styrene-acrylic resin formed into a spherical shape by a suspension polymerization method, such as carbon black or the like. The toner base particles have a particle diameter of 6 μm to 10 μm and an average particle diameter of 8 μm to which a well-known coloring agent and a charge control agent such as nigrosine, triphenylmethane, and quaternary ammonium salt are added. The toner is configured by adding silica as an external additive to the surface of the toner base particles. The silica as the external additive is subjected to a well-known hydrophobizing treatment using a silane coupling agent or the like, and a silica having a BET value of 150 is added to the silica base particles by 1.0% by weight (wt). A toner having a value of 50 was added in an amount of 0.5% by weight (wt) of the toner base particles.

Here, the BET value is a specific surface area measured by adsorbing nitrogen, and is represented by an area per unit weight (unit: m ² / g). Therefore, as the BET value increases, the particle size decreases, and as the BET value decreases, the particle size increases. In the present embodiment, a BET value is measured by a normal BET measurement method, and a specific surface area measurement device FlowSor manufactured by Shimadzu Corporation is used.
b2-2300 was used.

As described above, the toner is a suspension polymerization toner having an almost spherical shape, and 1.0% by weight of hydrophobically treated silica having a BET value of 150 is added as an external additive. Excellent fluidity. As a result, a sufficient charge amount can be obtained by frictional charging, so that an image with excellent transfer efficiency and extremely high image quality can be formed. Further, silica having a BET value of 50 lowers the fluidity of the toner as compared with silica having a BET value of 150. Thus, an image with excellent transfer efficiency and extremely high image quality can be formed over a long period of time.

The agitator 53 as a stirring and conveying member is
A support member 53a formed of a resin such as BS (acrylonitrile-butadiene-styrene) resin is provided with a PE
A sheet-like sliding portion 53b made of T (polyethylene terephthalate) is attached. Support member 53
As shown in FIGS. 3 and 4, a is integrally formed with a rotating shaft 55 supported on both side walls 51a and 51b of the case 51, and a gear 63 is attached to a shaft end of the rotating shaft 55. Have been. Further, as shown in FIG. 2, the sliding contact portion 53b has at least a cylindrical bottom portion 52a of the toner storage chamber 52.
Has a width (length in the direction of the radius of rotation) so as to bend when sliding. Therefore, when the rotational driving force from the motor (not shown) is transmitted to the gear 63, the agitator 53 including the support member 53a and the sliding portion 53b is provided.
Is rotated in the direction of the arrow shown in FIG. 2, and the sliding contact portion 53b is in sliding contact with the bottom surface portion 52a of the toner storage chamber 52 in a bent state.
The toner is pushed up to the opening A by the conveying surface having the width W1 shown in FIG. Further, not only the sliding contact portion 53b but also the support member 53
The surface a also pushes up the toner. The supporting member 53a has an opening 53c as shown in FIGS.
Are formed, and the resistance of the surface of the support member 53a received from the toner during rotation is reduced.
Further, the longitudinal lengths of the support member 53a and the sliding contact portion 53b are set to be shorter than the longitudinal length of the case 51, and as shown in FIG. The side portions are light transmission windows 56a, 56b on both sides.
Are arranged so as to have an interval W2 so as not to contact with.

The cleaning member 54 comprises a support member 54a formed integrally with the support member 53a of the agitator 53, and wipers 54b attached to both ends of the tip of the support member 54a as shown in FIG. Is done. The wiper 54b is formed of urethane rubber, and is attached at a position where the wiper 54b slides on the surface of the light transmission window 56 with the rotation of the support member 54a and can wipe off the toner on the surface. The support member 54a of the cleaning member 54 is, for example, in a direction opposite to and parallel to the support member 53a of the agitator 53, that is, the support member 53a of the agitator 53.
Is set to be 180 °.

The light transmission window 56 is a transparent or translucent member made of acrylic, polycarbonate, polypropylene, or the like, and is attached to the side wall 51a of the case 51 on the light emitting means 60 side as shown in FIGS. And a light transmitting window 56b attached to the side wall 51b on the light receiving means 61 side. The light transmitting windows 56a and 56b are provided so as to protrude into the toner storage chamber 52, and the wiper 54b of the cleaning member 54 can surely make the light transmitting windows 56a and 56b.
The surface of 56b can be wiped off.
Further, as shown in FIG. 2, the light transmission window 56b (56a) is a plane including the rotation center line of the agitator 53 and the cleaning member 54, and is larger than a plane G (hereinafter referred to as a vertical plane) extending in the vertical direction. It is provided at a position on the opening A side. Further, the light transmitting windows 56a, 56b of the drum cartridge 2a
3 and 4, openings 62a and 62b are formed as shown in FIGS. 3 and 4. The opening 62a allows light to enter the light transmission window 56a, and the opening 62b transmits light. The light can be emitted from the window 56b.

As shown in FIGS. 3 and 4, light emission as developer remaining amount detecting means is provided on both sides of the developing device 50 corresponding to the positions where the light transmitting windows 56a and 56b are provided. Means 60 and light receiving means 61 are provided.

The light emitting means 60 includes a holder 60a attached to the frame 2b, a substrate 60b supported by the holder 60a, and a light emitting element 60 provided on the substrate 60b.
c. The holder 60a is formed of plastic, and the light transmitting window 5 of the holder 60a is formed.
On the side facing 6a, a plastic lens 60d is formed by integral molding. Note that a light emitting diode is used as the light emitting element 60c as an example.

Similarly, the light receiving means 61 includes a holder 61a attached to the frame, a substrate 61b supported by the holder 61a, and a light receiving element 61c provided on the substrate 61b. Also, the holder 61a
Is formed of plastic, and a plastic lens 61d is formed by integral molding on the side of the holder 61a facing the light transmission window 56b. Note that a phototransistor is used as an example of the light receiving element.

The light emitting element 60c, the plastic lens 60d, the opening 62a of the drum cartridge 2a,
The light transmission window 56a, the light transmission window 56b, the opening 62b of the drum cartridge 2a, the plastic lens 61d, and the light receiving element 61c are set so as to be substantially aligned as shown in FIGS. The light emitted from the light emitting element 60c is made substantially parallel by the plastic lens 60d, passes through the opening 62a, and passes through the light transmitting window 56a.
Incident on. Therefore, the light transmitting window 56a and the light transmitting window 56b
In the state where no toner is present, the light transmitted through the light transmission window 56a enters the opposite light transmission window 56b, passes through the light transmission window 56b, passes through the opening 62b, and passes through the opening 62b. 61d. The incident light is collected by the plastic lens 61d and received by the light receiving element 61c.

As shown in FIG. 5, the light receiving element 61c is an element whose output voltage value changes according to the amount of light received.
In this embodiment, when the amount of received light is minimum, the voltage value is approximately 5V.
And the voltage value is almost 0 when the amount of received light is maximum.
It becomes a value close to V. In this range, the voltage value changes according to the amount of received light. In the present embodiment, the output of the light receiving element 61c is read by a control unit (not shown) including a microprocessor or the like, a predetermined voltage value is set as a threshold, and an output voltage value higher than the threshold is high. Level, an output voltage value lower than the threshold value is determined to be low level, and the sum of the low level period (hereinafter referred to as low level period) T1 in the measurement unit period T2 is determined by the measurement. The remaining amount of toner is detected by calculating the ratio of the toner in the unit period T2.

(Operation Example) Hereinafter, an operation example of the developing device 50 in the present embodiment will be described in detail.

First, the uppermost surface of the toner (hereinafter, referred to as the toner surface) is connected to the light transmitting window 56 as shown by a dotted line in FIG.
a, 56b, which is much higher than
A case where a sufficient amount of toner is stored in the printer will be described. In this case, the rotation of the agitator 53 causes the sliding contact portion 53b to agitate the toner in the toner storage chamber 52 while slidingly contacting the wall surface of the toner storage chamber 52.
As the sliding contact portion 53b reaches the opening A and further passes through the opening A as shown in FIG.
The toner inside is transported to the developing chamber 57. On the other hand, the wiper 54b of the cleaning member 54 performs an operation of wiping the surfaces of the light transmitting windows 56a and 56b.
6b, a sufficient amount of toner is stored, so that the light transmitting windows 56a, 56 wiped by the wiper 54b are removed.
The surface of b is immediately again covered with the surrounding toner. Therefore, the light emitted from the light emitting element 60c does not pass through the inside of the toner storage chamber 52, and the output of the light receiving element 61c does not change.

Next, a case where the remaining amount of toner decreases and the toner surface approaches the positions of the light transmitting windows 56a and 56b as shown by the solid line in FIG. 6 will be described. In such a case, the light transmitting windows 56a and 56b will not be covered with the toner immediately after wiping by the wiper 54b.
When the wiper 54b rotates from the position shown in FIG. 6 to the position shown in FIG. 7, the sliding contact portion 5 of the agitator 53
3b also rotates while sliding on the bottom surface 52a of the toner storage chamber 52 in a bent state, so that the toner is pushed out in the direction of arrow B shown in FIG. 56b. The time during which the light transmitting windows 56a and 56b are covered with the toner pushed out by the sliding contact portion 53b in this manner depends on the amount of toner. That is, the light transmission windows 56a and 56b are blocked for a longer time as the toner amount is larger, and the time for blocking the light transmission windows 56a and 56b is shorter as the toner amount is smaller. Therefore, as the amount of toner increases, the low level period T1 of the output of the light receiving element 61c shown in FIG. 5 decreases, and as the amount of toner decreases, the low level period T1 of the output of the light receiving element 61 illustrated in FIG. Therefore, in the present embodiment, the light receiving element 61 is controlled by a control unit (not shown) at a predetermined sampling cycle.
The output voltage value c is sampled and stored, and when the ratio of the total of the low level periods T1 within the predetermined measurement unit period T2 exceeds the predetermined ratio, it is determined that the toner is in the empty state. did.

On the other hand, the toner supplied from the toner storage chamber 52 to the developing chamber 57 through the opening A is provided with a certain amount of triboelectric charge at a pressing portion between the supply roller 58 and the developing roller 59, The developing roller 59 is carried by the electrostatic force, and is conveyed to a pressing portion between the developing roller 59 and a contact portion 64 b of the layer thickness regulating blade 64 by the rotation of the developing roller 59. Then, the toner externally added with the external additive comes into contact with the contact portion 64b of the layer thickness regulating blade 64 and the developing roller 59 at the pressing portion, so that a triboelectric charge is given, and the toner is externally added. The agent contacts 64
b and the pressure from the developing roller 59. However, since the contact portion 64b of the layer thickness regulating blade 64 is formed of a member having rubber elasticity, when the toner to which the external additive is externally added is conveyed to the pressing portion, the contact portion 64b becomes the toner. Deforms according to the shape of the external additive slightly projecting from the base particles. Similarly, since the developing roller 59 is also formed of a member having rubber elasticity, it is deformed according to the shape of the external additive. As a result, the pressure on the external additive is reduced, and the embedding of the external additive into the toner base particles is reduced.

The toner, which has been sufficiently triboelectrically charged at the pressing portion between the layer thickness regulating blade 64 and the developing roller 59, passes through the pressing portion and passes through the photosensitive drum 20.
To the developing area opposite to the developing area. Part of the toner conveyed to the developing area selectively adheres to the surface of the photosensitive drum 20 according to the electrostatic latent image formed on the surface of the photosensitive drum 20, and the remaining part develops with the rotation of the developing roller 59. It is returned to the chamber 57. A part of the toner returned to the developing chamber 57 follows a toner circulation path formed by the rotation of the developing roller 59 and the rotation of the supply roller 58 as indicated by a dotted arrow in FIG. Is returned from the developing chamber 57 to the toner accommodating chamber 52.

As described above, the external additive is prevented from being buried in the pressing portion between the layer thickness regulating blade 64 and the developing roller 59 as described above. Therefore, even when the toner is used for a long time, the fluidity of the toner in the toner storage chamber 52 does not decrease. In the toner accommodating chamber 52, the toner pushed out by the agitator 53 as described above is again stabilized at the bottom of the toner accommodating chamber 52 after a predetermined time, but since the fluidity of the toner does not decrease, The time until this stabilization is not affected by the change in the fluidity of the toner from the start of use to the stage where it is determined that the toner is empty. As a result, in the developing device 50 of the present embodiment, accurate and stable toner remaining amount detection is performed.

In particular, in the present embodiment, since the contact portion 64b of the layer thickness regulating blade 64 is formed of silicone rubber, the frictional charging characteristics with respect to the toner are extremely good, and the contact portion 64b is formed of another rubber member. As compared with the case, the pressing force of the layer thickness regulating blade 64 against the developing roller 59 can be reduced, and the embedding of the external additive into the toner base particles can be more reliably prevented.

Note that the present invention is not limited to such a configuration, and the contact portion 64 of the layer thickness regulating blade 64
b may be formed of fluorine-containing rubber or urethane rubber. When fluorine-containing rubber or urethane rubber is used, the triboelectric charging characteristics with respect to the toner are reduced. Therefore, it is necessary to increase the pressing force of the layer thickness regulating blade 64 against the developing roller 59 as compared with the case where silicone rubber is used. However, even when the pressing force is increased in this manner, the contact portion 64b is deformed in accordance with the shape of the external additive due to rubber elasticity, so that compared to a case where the contact portion is formed of a metal such as stainless steel. The embedding of the external additive into the toner base particles is far less, can be suppressed to a practically sufficient level, and the remaining toner amount can be detected stably.

Further, since the decrease in the fluidity of the toner is reduced, the bias of the toner in the toner storage chamber 52 can be quickly eliminated only by rotating the agitator 53 in the toner storage chamber 52. Therefore, even when the main body of the laser beam printer 1 is moved or the developing unit cartridge is inserted into or removed from the laser beam printer 1, the toner in the toner accommodating chamber 52 is not biased and always accurate. The remaining toner amount can be detected.

When the width of the opening communicating the toner storage chamber 52 and the developing chamber 57 is narrower than the width of the developing chamber 57, or when a large number of narrow envelopes or postcards are continuously printed. , The toner tends to be offset, but according to the present embodiment, as described above, a decrease in the fluidity of the toner can be suppressed. be able to.

In the present embodiment, since silica having a BET value of 150 and having a small particle diameter is externally added as an external additive, the fluidity of the toner can be further increased.
Deviation of toner can be prevented more reliably. In addition, if only the external additive having a small particle diameter is used for a long period of time up to the vicinity of the toner empty, the external additive becomes embedded in the toner base particles, and the fluidity of the toner may be reduced. However, in this embodiment, not only silica having a BET value of 150 and a small particle size is externally added, but two types of silica having a BET value of 150 and a large particle size of 50 are used. Since silica is externally added, embedding of silica having a BET value of 150 with a small particle size in the toner base particles is reliably prevented by the spacer effect of silica having a BET value of 50 and a particle size of 50 is determined as toner empty. The fluidity of the toner can be kept good up to this point. That is, by externally adding silica having a BET value of 50 and a large particle diameter, the BET value is 1
Initially, the fluidity of the toner is reduced as compared with the case where only silica having a small particle size of 50 is externally added.
In the long term, embedding of silica having a BET value of 150 with a small particle diameter into the toner base particles is prevented, and the fluidity of the toner is always kept good. As a result, the time until the toner pushed out by the sliding portion 53b of the agitator 53 as described above stabilizes at the bottom of the toner storage chamber 52 is always kept constant, and the bias of the toner in the toner storage chamber 52 is reduced. Since the prevention can be surely performed, the detection of the remaining amount of toner is performed stably and accurately from the beginning of use until the toner is determined to be empty.

On the other hand, in the conventional apparatus, the thickness regulating blade is generally made of stainless steel or the like for reasons such as cost reduction, and an external additive is provided at the contact portion between the thickness regulating blade and the developing roller. Large pressure is applied to
Embedding of the external additive into the toner base particles occurred, resulting in a decrease in the fluidity of the toner. Then, when the toner having such reduced fluidity is returned from the developing chamber to the toner containing chamber by circulation of the toner between the developing chamber and the toner containing chamber, the toner having reduced fluidity is stirred by the agitator. The time from when the toner stabilizes to the bottom of the toner storage chamber fluctuates depending on the length of the use period, and stable detection of the remaining amount of toner cannot be performed. Further, when the amount of the toner having a decreased fluidity increases in the toner storage chamber, the toner is biased in the toner storage chamber, so that accurate detection of the remaining toner amount cannot be performed.

Therefore, according to this embodiment, it is possible to provide an excellent image forming apparatus capable of detecting the remaining amount of toner extremely accurately and stably as compared with the related art.

(Experimental Example) Next, an experimental example in which the relationship between the external additive and the fluidity of the toner and the relationship between the fluidity and the accuracy of the detection of the remaining amount of the toner were examined using the apparatus of the present embodiment. explain.

In the experiment, a positively chargeable non-magnetic one-component toner was used.
Acrylic resin containing carbon black and wax, added with Nigrosine charge control agent
A toner having toner base particles having a particle size of 10 to 10 μm and an average particle size of 8 μm was used. Then, a BET value of 15 is added to this toner.
0 silica only 1.0% by weight (wt)% of the toner base particles
What was added, silica with a BET value of 150 and a BET value of 50
Of each of the toner base particles is 1.0 weight (wt).
%, Only silica having a BET value of 50 and 1.0% by weight (wt) of the toner base particles, a BET value of 1
The fluidity of the toner was measured for each of silica 50 and silica having a BET value of 100 to which 1.0% by weight (wt) of the toner base particles were added.

For the measurement, a powder tester PTN type manufactured by Hosokawa Micron Corporation was used.
When three types of sieves of μm and 44 μm are stacked in three stages and shaken for 15 seconds with a toner amount of 4 g, the total of the residual% of the toner remaining on the three sieves is defined as the cohesion degree, and 100-cohesion degree is defined as the fluidity Index.

Further, the state of the remaining amount of toner in the toner accommodating chamber 52 when printing was continuously performed using each toner until it was determined that the toner was empty was examined. In the developing device used in the experiment, when 70 g of new toner is stored in the toner storage chamber 52, the low-level period of the output of the light receiving element 61c is 2.times. 22 seconds, or 37%. Therefore, in the experiment, the total of the low-level periods was calculated every 6 seconds, which is the measurement unit period, and the setting was made such that the toner empty was determined when the ratio of the total to 6 seconds reached 37%. Therefore, if the fluidity of the toner does not decrease, the remaining amount of toner in the toner storage chamber 52 when it is determined that the toner is empty is 70 g. FIG. 8 shows the experimental results.

FIG. 8 shows that when only an external additive having a BET value of 150 was externally added, the fluidity index was 89, and the BET value was 89.
Is extremely higher than the fluidity index 66 when only the external additive having the value 50 is externally added, and the BET value is 100.
It can be seen that the fluidity of the toner can be extremely increased by externally adding the above external additives.

When an external additive having a BET value of 150 and an external additive having a BET value of 50 are used in combination, the index of fluidity is 80, which is lower than the case where only the external additive having a BET value of 150 is externally added. And the fluidity is slightly reduced. That is, when the external additive having a BET value of 100 or more and the external additive having a BET value of 100 or less are used, the fluidity is lower than when only the external additive having a BET value of 100 or more is used. This is presumably because external additives smaller than the BET value of 100 are caught when the toners rub against each other.

On the other hand, an external additive having a BET value of 150 and B
When an external additive having an ET value of 100 is used in combination, the fluidity index is 90, indicating that the fluidity is slightly higher than when only an external additive having a BET value of 150 is externally added. This is because the external additive having a BET value of 100 is not so large that the toner is less likely to be caught when the toner rubs against each other.
It is thought that this is because the fluidity of the 50 external additives is sufficiently exhibited without being impaired.

Next, a description will be given of the result of checking the bias of the toner when continuous printing is performed using the respective toners and the remaining amount of the toner when the toner is empty.

First, in the case of using a toner to which only the external additive having a high fluidity BET value of 150 was used, the remaining amount of the toner when it was determined that the toner was empty was 60 g.
This is because at the beginning of printing, the fluidity of the toner was high and the bias of the toner was small, but as the toner approached the toner, an external additive with a small particle size was embedded in the toner base particles, and the fluidity of the toner decreased. It is considered that the deviation of the toner occurred and the accuracy of detecting the remaining amount of the toner was slightly reduced although it was within the allowable range.

Next, in the case where a toner externally added with two kinds of external additives, that is, an external additive having a BET value of 150 and an external additive having a BET value of 50, is used. The amount was 70 g. Further, it was confirmed that the toner did not shift from the beginning of printing until the toner was empty. By externally adding an external additive having a BET value of 50, the fluidity of the toner is reduced as compared with the case where only an external additive having a BET value of 150 is used, but the BET value of 50 having a large particle size is reduced.
A good spacer effect can be exhibited by the external additive, and the external additive having a BET value of 150 having the smallest particle diameter can be reliably prevented from being embedded in the toner base particles, and the fluidity of the toner is long. It is probable that it did not decrease over the period.

Next, when a toner externally added only with an external additive having a BET value of 50, which has the lowest fluidity, is used, the fluidity of the toner decreases, and the remaining amount of toner when it is determined that the toner is empty is determined. Was 50 g. Further, when the inside of the toner storage chamber 52 was observed, the bias of the toner was largest.

Next, when a toner externally added with two kinds of external additives, that is, an external additive having a BET value of 150 and the external additive having a BET value of 100 having the highest fluidity is used, it is determined that the toner is empty. The remaining toner amount was 65 g. When two types of external additives are used, the embedding of the external additive having the smallest particle diameter among the two types of external additives into the toner mother particles is slightly suppressed by the external additive having a large particle diameter. Although,
A small external additive having a BET value of about 100 has a small spacer effect, causing the external additive to be slightly embedded in the toner base particles, and the fluidity of the toner slightly decreases as the toner approaches the empty state. It is considered that the accuracy of the toner remaining amount detection has slightly decreased.

From the results of the above experiments, it was found that the contact portion 64b of the layer thickness regulating blade 64 was formed of silicone rubber, the developing roller 59 was formed of silicone rubber, and a polymer toner having an average particle diameter of 8 μm was used. Is to improve the fluidity of the toner over a long period of time by using two kinds of external additives, an external additive having a BET value of 150 and an external additive having a BET value of 50. Keep
It has been found that accurate detection of the remaining amount of toner can always be performed.

When a blade is used in which stainless steel is bent and its corners are used as contact portions, the offset and the remaining amount are worse than any of the cases in FIG. 8, and it is difficult to detect the remaining amount with high accuracy. .

However, the present invention is not limited to such a combination of external additives, and the types of external additives to be combined are not limited to two, but may be many more. May be combined.

The above-mentioned experiments explain the difference in the effect due to the combination of external additives, and the present invention is not limited to the combination of these external additives.

The present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. Can easily be inferred.

[0096]

According to the image forming apparatus of the first aspect,
Developer remaining amount detecting means for detecting the remaining amount of the developer in the developer chamber based on the light receiving state of the light emitted from the light emitting element and transmitted through the light transmitting window, and a rubber member pressed by the developer carrier And a layer thickness regulating member for forming a thin layer of the developer on the developer carrier, so that embedding of the external additive into the toner base particles can be significantly reduced. As a result, it is possible to reliably prevent the fluidity of the developer returned into the developer chamber from decreasing. As a result, it is possible to reliably prevent the occurrence of the deviation in the developer chamber, and to return to a stable state even when the developer chamber moves along with the transfer operation to the developing chamber. Since it can be kept substantially constant, the developer remaining amount detecting means detects the amount of the developer remaining in the developer chamber based on the light receiving state of the light emitted from the light emitting element and transmitted through the light transmitting window in the light receiving element. Can be performed accurately and stably without depending on the length of use of the image forming apparatus.

According to the image forming apparatus of the second aspect, since the developer carrier is formed of the conductive rubber member, the pressure from the pressing member against the external additive can be further reduced. Therefore, the embedding of the external additive into the toner base particles can be further remarkably reduced, and the decrease in the fluidity of the developer in the developer chamber can be more reliably prevented. As a result, the remaining amount of the developer in the developer chamber can be detected more accurately and stably without depending on the length of the use period of the image forming apparatus.

According to the image forming apparatus of the third aspect, the developer stirring / conveying member is rotatably provided inside the developer chamber, agitates the developer in the developing chamber, and the developer through the opening. Although the developer is conveyed to the developing chamber, since the decrease in the fluidity of the developer is reliably prevented as described above, the fluctuation in the time required to fall from the developer stirring and conveying member to return to the original position is reduced. In addition, even when the image forming apparatus is used for a long period of time, it can be reliably prevented. Also,
Deviation of the developer in the developer chamber can be reliably prevented. As a result, the remaining amount of the developer in the developer chamber can be accurately and stably detected without depending on the length of use of the image forming apparatus.

According to the image forming apparatus of the present invention, at least two types of external additives having different particle diameters are externally added to the developer. By functioning as a spacer for the external additive, it is possible to more reliably prevent the external additive having a small particle diameter from being embedded in the toner base particles. Therefore, the fluidity of the developer can be more reliably prevented from lowering, and the detection of the remaining amount of the developer in the developer chamber can be accurately and stably performed regardless of the length of use of the image forming apparatus. It can be carried out.

According to the image forming apparatus of the fifth aspect, the external additive having the minimum particle diameter and the other external additives are more than the developer in which only the external additive having the minimum particle diameter is externally added to the developer. Since at least two types of external additives combined so that the fluidity of the developer externally added by using in combination with the external additive becomes lower, the fluidity of the developer is reduced by the external additive having the minimum particle size. Is kept good, and the external additive having a large particle diameter which tends to decrease the fluidity can be prevented from being embedded in the developer of the external additive having the minimum particle diameter. As a result, even when the image forming apparatus is used for a long period of time, the embedding of the external additive into the toner in the layer thickness regulating member and the pressing portion of the developer carrier can be reduced, and the flow of the developer can be reduced. Properties can be kept good. Therefore, the bias of the developer in the developer chamber can be prevented, and even when the developer moves in the developer chamber along with the transport operation to the developer chamber, the time required to return to a stable state is substantially constant. Since the remaining amount can be maintained, the detection of the remaining amount of the developer in the developer chamber by the remaining amount of the developer can be performed accurately and stably without depending on the length of the use period of the image forming apparatus.

According to the image forming apparatus of the present invention, since at least the pressing member of the layer thickness regulating member is formed of silicone rubber, it is possible to apply a lower pressing force to the developer than a case where it is formed of another rubber member. And a sufficient triboelectric charge can be imparted to the toner, and a reduction in the pressing force of the developer from the pressing member can more reliably prevent the external additive from being embedded in the toner base particles. Fluidity can be more reliably prevented from lowering. As a result, it is possible to accurately and stably detect the remaining amount of the developer in the developer chamber by the remaining developer amount detecting means regardless of the length of the use period of the image forming apparatus.

According to the image forming apparatus of the present invention, even when a polymerized toner produced by a polymerization method is used as the developer, it is possible to reliably prevent the external additive from being embedded in the toner base particles. Therefore, the extremely high fluidity of the polymerized toner can be maintained, and the remaining amount of the developer in the developer chamber can be more accurately and stably detected by the developer remaining amount detecting means.

According to the developing device of the present invention, there is provided a pressing member formed of a rubber member pressed against the developer carrier, and a layer thickness for forming a thin layer of the developer on the developer carrier. Since the regulating member is provided, embedding of the external additive into the toner base particles can be significantly reduced, and a decrease in the fluidity of the developer returned into the developer chamber can be reliably prevented. As a result, it is possible to reliably prevent the occurrence of the deviation in the developer chamber, and to return to a stable state even when the developer chamber moves along with the transfer operation to the developing chamber. Since it can be kept substantially constant, the developer remaining amount detecting means provided in the image forming apparatus performs the developer chamber based on the light receiving state of the light emitted from the light emitting element and transmitted through the light transmitting window in the light receiving element. Can be accurately and stably performed without depending on the length of the use period of the developing device.

According to the ninth aspect of the present invention, since the developer carrier is formed of a conductive rubber member, the pressure of the external additive from the pressing member can be further reduced. Therefore, the embedding of the external additive into the toner base particles can be further remarkably reduced, and the decrease in the fluidity of the developer in the developer chamber can be more reliably prevented. As a result, the remaining amount of the developer in the developer chamber can be detected more accurately and stably without depending on the length of the use period of the developing device.

According to the tenth aspect of the present invention, the developer stirring and conveying member is provided rotatably inside the developer chamber,
The developer in the developing chamber is agitated and transported to the developing chamber through the opening. However, since the flowability of the developer is reliably prevented as described above, Variations in the time required to drop from the transport member and return to the original position can be reliably prevented even when the use period of the developing device is long. Further, it is possible to reliably prevent the occurrence of the bias of the developer in the developer chamber. As a result, it is possible to accurately and stably detect the remaining amount of the developer in the developer chamber regardless of the length of use of the developing device.

According to the developing device of the present invention, since at least two kinds of external additives having different particle diameters are externally added to the developer, an external additive having a large particle diameter is added to an external additive having a small particle diameter. By functioning as a spacer for the additive, the embedding of the external additive having a small particle size into the toner base particles can be more reliably prevented. Therefore, a decrease in the fluidity of the developer can be prevented more reliably, and the detection of the remaining amount of the developer in the developer chamber can be performed accurately and stably without depending on the length of the use period of the developing device. Can be made.

According to the developing device of the twelfth aspect, the external additive having the minimum particle diameter and the other external additives are smaller than the external additive having only the external additive having the minimum particle diameter. Since at least two kinds of external additives combined so that the fluidity of the developer externally added is lower than that of the external additive, the fluidity of the developer is reduced by the external additive having the minimum particle size. While keeping good,
The external additive having a large particle diameter which tends to decrease the fluidity can prevent the external additive having the minimum particle diameter from being buried in the developer. As a result, even when the developing device is used for a long period of time, the embedding of the external additive into the toner in the layer thickness regulating member and the pressing portion of the developer carrier can be reduced, and the fluidity of the developer can be reduced. Can be kept good. Therefore, the bias of the developer in the developer chamber can be prevented, and even when the developer moves in the developer chamber along with the transport operation to the developer chamber, the time required to return to a stable state is substantially constant. Since the remaining amount of developer can be maintained, the detection of the remaining amount of the developer in the developer chamber by the remaining amount of the developer provided in the image forming apparatus can be performed accurately and stably without depending on the length of use of the developing device. Can be done.

According to the thirteenth aspect of the present invention, since at least the pressing member of the layer thickness regulating member is formed of silicone rubber, the developing device can be pressed against the developer with a lower pressing force than when formed of another rubber member. Sufficient triboelectric charge can be provided, and the reduction of the pressing force of the developer from the pressing member can more reliably prevent the external additive from being embedded in the toner base particles. It is possible to more reliably prevent the deterioration of the properties. as a result,
The detection of the remaining amount of the developer in the developer chamber by the remaining amount of the developer in the image forming apparatus can be performed accurately and stably without depending on the length of the use period of the developing device.

According to the developing device of the present invention, even when a polymerized toner produced by a polymerization method is used as the developer, the external additive can be reliably prevented from being embedded in the toner base particles. Therefore, the extremely high fluidity of the polymerized toner can be maintained, and the detection of the remaining amount of the developer in the developer chamber by the remaining developer amount detecting means provided in the image forming apparatus can be performed more accurately and stably. Can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a developing device in the image forming apparatus of FIG.

FIG. 3 is a view showing a cross section taken along line XX in FIG. 2;

FIG. 4 is a view showing a cross section taken along line XX ′ in FIG. 2;
FIG. 4 is a diagram illustrating a state in which the agitator and the cleaning member have been rotated by 180 degrees from the position illustrated in FIG. 3.

5 is a diagram for explaining an output voltage waveform of a light receiving element and a method of detecting a remaining amount of a developer in the image forming apparatus of FIG. 1;

FIG. 6 is a view for explaining an operation of an agitator and a cleaning member of a developing device and an operation of detecting a remaining amount of developer in the image forming apparatus of FIG. 1 (part 1);

FIG. 7 is a view for explaining the operation of the agitator and the cleaning member of the developing device and the operation of detecting the remaining amount of the developer in the image forming apparatus of FIG. 1 (part 2);

FIG. 8 is a diagram showing the results of an experimental example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser beam printer 50 Developing device 51a, 51b Side wall 52 Toner storage chamber 53 Agitator 56 Light transmission window 57 Developing chamber 59 Developing roller 60 Light emitting means 61 Light receiving means 64 Layer thickness regulating blade 64b Contact part

Claims (14)

[Claims] A developer chamber accommodating a non-magnetic one-component developer; a developer chamber communicating with the developer chamber via an opening; and a developer carrier provided in the developer chamber for carrying and transporting the developer. A light-transmitting window provided in the developer chamber; and a light-emitting element and a light-receiving element. The light-emitting element emits light transmitted from the light-emitting element and passing through the light-transmitting window. A developer remaining amount detecting unit that detects a remaining amount of the developer in the developer chamber; and a pressing member formed of a rubber member pressed against the developer carrying member. An image forming apparatus, comprising: a layer thickness regulating member for forming a layer. 2. The image forming apparatus according to claim 1, wherein the developer carrier is formed of a conductive rubber member. 3. A developer stirring and conveying member rotatably provided inside the developer chamber, for stirring the developer in the developing chamber and conveying the developer to the developing chamber through the opening. The image forming apparatus according to claim 1, wherein: 4. The image forming apparatus according to claim 1, wherein at least two types of external additives having different particle diameters are externally added to said developer. 5. A developing method in which an external additive having a minimum particle diameter and another external additive are used in combination, compared to a developer in which only an external additive having a minimum particle diameter is externally added. 4. The image forming apparatus according to claim 1, wherein at least two types of external additives combined so that the agent has lower fluidity are externally added. 6. The image forming apparatus according to claim 1, wherein at least the pressing member of the layer thickness regulating member is formed of silicone rubber. 7. The image forming apparatus according to claim 1, wherein the developer is a polymerized toner produced by a polymerization method. 8. An image forming apparatus comprising: a light emitting element and a light receiving element; and a developer remaining amount detecting means for detecting a remaining amount of the developer based on a light receiving state of the light emitted from the light emitting element in the light receiving element. A developing device mounted on the device, comprising: a developer chamber for storing a non-magnetic one-component developer; a developing chamber communicating with the developer chamber through an opening; and a developer provided in the developing chamber. A developer carrier that carries and conveys; a light transmission window provided in the developer chamber and transmitting light emitted from the light emitting element and received by the light receiving element; and a rubber member pressed by the developer carrier. And a layer-thickness regulating member for forming a thin layer of developer on the developer-carrying member. 9. The developing device according to claim 8, wherein the developer carrier is formed of a conductive rubber member. 10. A developer stirring and conveying member rotatably provided inside the developer chamber, for stirring the developer in the developing chamber and conveying the developer to the developing chamber through the opening. The developing device according to claim 8, wherein: 11. The developing device according to claim 8, wherein at least two types of external additives having different particle diameters are externally added to said developer. 12. A developing method in which an external additive having a minimum particle diameter is used in combination with another external additive, as compared with a developer in which only an external additive having a minimum particle diameter is externally added. The developing device according to any one of claims 8 to 10, wherein at least two kinds of external additives combined so that the agent has lower fluidity are externally added. 13. The developing device according to claim 8, wherein at least the pressing member of the layer thickness regulating member is formed of silicone rubber. 14. The method according to claim 8, wherein the developer is a polymerized toner produced by a polymerization method.
3. The developing device according to any one of 3.