JP2001027840A - Developing device, process cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the circulation of developer in the width direction of a developing chamber excellent without decreasing the supply amount of the developer to a developing roller nor making loud noise by simple constitution by making developer carrying performance higher at a center part in the longitudinal direction of an aperture part than at both ends in the longitudinal direction. SOLUTION: Toner carrying ability from a toner storing chamber 52 to the developing chamber 57 is made higher at the center part than at both ends in the longitudinal direction. In the chamber 57, the toner is supplied to the center part in the width direction of the chamber 57 by a 2nd agitator 91, and the toner is supplied all over the area in the width direction of the chamber 57 by a 1st agitator 90 soon after that, whereby the push-in pressure of the toner into the chamber 57 is higher only at the center part in the width direction of the chamber 57. When the push-in pressure of the polymerized toner gets higher at the center part, the polymerized toner pushed inside the chamber 57 passes both end part sides of the chamber 57 and is restored to the chamber 52 from the aperture A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for transporting a developer in a developer accommodating chamber to a developing chamber by means of a developer transporting device to perform development, a process cartridge having the developing device, and the developing device. Alternatively, it belongs to the technical field of an image forming apparatus provided with a process cartridge.

[0002]

2. Description of the Related Art In an image forming apparatus provided with a non-magnetic one-component type developing device, a layer thickness regulating blade is brought into pressure contact with a developing roller for carrying and transporting a developer, and the layer thickness regulating blade contacts the developing roller. A thin layer of developer is formed. And, with the developer thinned in this way,
Printing is performed by visualizing the electrostatic latent image on the photoreceptor as a developer image, and transferring the visualized developer image to printing paper.

Therefore, the printable width in such an image forming apparatus is determined by the width of the thin layer of the developer in the longitudinal direction of the developing roller, that is, the width of the pressing portion between the layer thickness regulating blade and the developing roller. Usually, the width of the pressing portion is configured to be larger than the maximum width of the printing paper set as the printing paper usable in the image forming apparatus. That is, the developing device is configured by making the width of the layer thickness regulating blade larger than the width of the maximum print paper, and further using a developing roller having a length exceeding the width of the layer thickness regulating blade.

However, since printing using the maximum printable width is not usually performed, most of the developer thinned on the developing roller is located at both ends of the developing roller. It is not used and passes through the layer thickness regulating blade and the pressing portion of the developing roller many times.

[0005] In general, a developer used for non-magnetic one-component development includes a fine powder of silica, alumina, titanium oxide or the like, which is called an external additive for improving fluidity, externally added to toner base particles. Therefore, as described above, the external additive is embedded in the toner base particles by passing the layer thickness regulating blade and the pressing portion of the developing roller many times. As a result, the fluidity of the developer is reduced, and the deteriorated developer stays at both ends of the developing device accommodating the developing roller, and the image quality of printing is sequentially reduced from both ends in the longitudinal direction of the developing roller. There was a problem that it deteriorated.

[0006] An opening is provided between a developing chamber provided with a developing roller and a developer accommodating chamber accommodating the developer, and the developer is supplied from the developer accommodating chamber to the developing chamber. ,
This is performed by rotating a toner conveying member (agitator) provided in the developer accommodating chamber and further projecting a part of the toner conveying member from the opening.

In order to prevent the stagnation of the developer at both ends of the developing roller in such a configuration, the width of the opening is set to be substantially equal to or larger than the printing width. A developing device has been proposed in which the width of the toner conveying member is set to be substantially the same as the opening width while being substantially equal to the width of the toner conveying member.

[0008]

However, according to the conventional developing device, although the developer circulates in the reciprocating direction between the developing chamber and the developer accommodating chamber, the developer does not move in the longitudinal direction of the developing roller. That is, the developer rarely moves in the width direction of the developing chamber or the developer accommodating chamber, and the deterioration of the developer at both ends of the developing chamber or the developer accommodating chamber cannot be prevented.

In addition, when the width of the opening is substantially the same as the printing width as in the developing device, if the supply of the developer becomes uneven, the toner on the developing roller at the portion where the supply is insufficient becomes insufficient. In some cases, there is a problem that image density unevenness occurs in the form of vertical stripes in printing.

In order to solve the above problems, a method of providing a stirring member in the developing chamber has been considered. According to this method, the circulation of the developer in the developing chamber, particularly in the width direction of the developing chamber, was improved, and it was possible to prevent the developer from staying at both ends of the developing chamber.

However, such a configuration requires a drive system for the agitating member of the developing chamber, so that the configuration is complicated and the manufacturing cost is increased.

Therefore, by lowering the position of the lower end of the opening, that is, the height of the partition wall from the developer accommodating chamber to the developing chamber, the developer is supplied from the developer accommodating chamber to the developing chamber. A method has been conceived in which the developer is returned to the developer accommodating chamber by gravity again to improve the circulation of the developer between the developing chamber and the developer accommodating chamber.

However, in this method, although the circulation of the developer is certainly promoted, the supply amount of the developer to the developing roller is reduced, and there is a problem that the image is easily blurred with a high print area ratio. .

Further, as another method, a thick PET sheet is used for the toner conveying member, and the amount of bending of the PET sheet is increased, so that the ability of supplying the developer into the developing chamber is increased, and the developer is forcibly discharged. A method has been conceived in which the developer is easily pushed back into the developer accommodating chamber after the toner conveying member has passed through the opening position.

However, this method has a problem that a loud noise is generated when the bending of the PET sheet of the toner conveying member is released.

The present invention solves the above-mentioned problems, and has a simple structure, without reducing the supply amount of the developer to the developing roller and without generating a loud noise. An object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus that can improve circulation in the width direction.

[0017]

According to a first aspect of the present invention, there is provided a developing device, comprising: a developer accommodating chamber for accommodating a polymerized toner produced by a polymerization method as a developer therein; A developing chamber provided with a carrier and a developer supply unit for supplying a developer to the developer carrier; an opening communicating the developer chamber with the developer chamber; and an interior of the developer chamber. The developer transfer performance from the developing chamber to the developing chamber at the longitudinal center of the opening is higher than the developer transferring performance at both ends in the longitudinal direction of the opening. And a developer conveying means.

According to the first aspect of the present invention, the polymerized toner in the developer accommodating chamber is conveyed to the developing chamber side through the opening by the developer conveying means by rotating the developer conveying means. Is done. At this time, the developer conveying performance of the developer conveying means is higher at the center in the longitudinal direction of the opening than at both ends in the longitudinal direction. Is higher at the center than at both ends in the width direction. As a result, the polymerized toner pressed from the center toward both ends in the developing chamber is returned to the developer accommodating chamber from both ends of the developing chamber due to its high fluidity. in this way,
According to the present invention, the polymerized toner circulates in the width direction of the developing chamber in the developing chamber, that is, in the longitudinal direction of the developer supporting body. There is no deterioration.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to the first aspect, the developer transport means includes a plurality of rotary transport members having a common rotation axis. The longitudinal width of at least one rotary transport member is equal to or greater than the longitudinal width of the opening, and at least another rotary transport member is
It is characterized in that it is provided only in the central part in the longitudinal direction with respect to the rotating part.

According to the second aspect of the present invention, the developer in the developer accommodating chamber is transported by the plurality of rotary transport members having a common rotation axis. Is formed to have a size equal to or larger than the longitudinal width of the opening, so that the developer is sufficiently supplied over the entire area of the opening. as a result,
The developer is sufficiently supplied over the entire width of the developing chamber, so that the supply of the developer to the developer carrier is not insufficient. Further, since at least the other rotary conveying member is provided only in the central portion in the longitudinal direction with respect to the rotating portion, the developer conveying performance from the developer accommodating chamber to the developing chamber is in the width direction of the developing chamber. The central portion is higher than the both ends, and the pressure of the polymerized toner in the developing chamber is higher at the central portion than at both ends in the width direction of the developing chamber. As a result, the polymerized toner pressed from the center toward both ends in the developing chamber is returned to the developer accommodating chamber from both ends of the developing chamber due to its high fluidity. As described above, according to the present invention, the polymerized toner circulates in the width direction of the developing chamber in the developing chamber, that is, in the longitudinal direction of the developer supporting body. And no deterioration of the toner is caused.

According to a third aspect of the present invention, there is provided a developing device, comprising: a developer accommodating chamber for accommodating a polymerized toner produced by a polymerization method therein as a developer; A developing chamber provided with a developer supply unit for supplying a developer to the carrier; an opening for communicating the developer storage chamber with the development chamber; and a rotating shaft common to the inside of the developer storage chamber. A plurality of rotary transport members, the longitudinal width of at least one rotary transport member is equal to or greater than the longitudinal width of the opening, and at least another rotary transport member However, the present invention is characterized in that a developer conveying means provided only at a central portion in the longitudinal direction with respect to the rotating portion is provided.

According to the third aspect of the present invention, the polymerized toner in the developer accommodating chamber is transported to the developing chamber side through the opening by the developer transporting means when the developer transporting means is rotated. Is done. At this time, since the longitudinal width of the at least one rotary conveying member is formed to be equal to or greater than the longitudinal width of the opening, the developer can be sufficiently spread over the entire area of the opening. Supply. As a result, the developer is sufficiently supplied over the entire width direction of the developing chamber, and the supply of the developer to the developer carrier is not insufficient. Further, since at least the other rotary conveying member is provided only in the central portion in the longitudinal direction with respect to the rotating portion, the developer conveying performance from the developer accommodating chamber to the developing chamber is in the width direction of the developing chamber. The central portion is higher than the both ends, and the pressure of the polymerized toner in the developing chamber is higher at the central portion than at both ends in the width direction of the developing chamber. As a result, the polymerized toner pressed from the center toward both ends in the developing chamber is returned to the developer accommodating chamber from both ends of the developing chamber due to its high fluidity. As described above, according to the present invention, the polymerized toner circulates in the width direction of the developing chamber in the developing chamber, that is, in the longitudinal direction of the developer supporting body. And no deterioration of the toner is caused.

According to a fourth aspect of the present invention, in order to solve the above problem, in the developing device according to any one of the first to third aspects, the developer transporting means has a tip portion which extends from the opening. It is characterized in that it is set so as to enter the developing chamber.

According to the fourth aspect of the present invention, when the developer conveying means is driven to rotate and reaches the opening position, the tip of the developer conveying means is moved from the opening to the developing chamber. enter in. As a result, the polymerized toner is suitably pushed into the developing chamber, and the above-described toner circulation performance in the width direction of the developing chamber is further improved.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to any one of the first to fourth aspects, the height of the upper surface of the lower end wall of the opening is set to the height. It is characterized in that it is formed to be higher than the upper surface of the developer supply means.

According to the fifth aspect of the present invention, the polymerized toner conveyed from the developer accommodating chamber is supplied to the developing chamber through the opening. The height is higher than the upper surface of the developer supply means provided in the developing chamber. As a result, the return of the polymerized toner from the developing chamber to the developer accommodating chamber due to gravity can be suppressed, and a shortage of toner supply to the developer carrying member does not occur. Moreover, according to the present invention, even if the height of the lower end wall of the opening is not so low, good toner circulation occurs in the width direction of the developing chamber as described above, so that the deteriorated toner stays there. Sure to prevent

According to a sixth aspect of the present invention, in order to solve the above-mentioned problems, in the developing device according to the first aspect, the developer conveying means is formed of a resin sheet. The sheet is provided with a rotating conveyance member, and the sheet is 50 μm.
It is characterized by being formed to a thickness greater than m and less than 100 μm.

According to a sixth aspect of the present invention, the rotary conveying member formed of a resin sheet of the developer conveying means is formed to be thicker than 50 μm, so that the toner from the developer accommodating chamber to the developing chamber is formed. It was found that the supply power was sufficiently obtained. Further, by forming the rotary conveying member to a thickness smaller than 100 μm, the bending of the sheet is released, so that there is no unusual sound when the sheet is popped and a quiet developing operation is performed.

According to a seventh aspect of the present invention, there is provided a process cartridge comprising:
7. A process cartridge detachably formed in an image forming apparatus, comprising: a carrier of an electrostatic latent image; and a developing device according to claim 1. It is characterized by having.

According to a seventh aspect of the present invention, in the process cartridge, the developing device according to any one of the first to sixth aspects is provided in addition to the electrostatic latent image carrier. In this case, good circulation of the polymerized toner occurs, and a good developing operation without toner deterioration is performed.

According to an eighth aspect of the present invention, there is provided an image forming apparatus including the developing device according to any one of the first to sixth aspects, or the process cartridge according to the seventh aspect, in order to solve the above problem. I do.

The image forming apparatus according to the present invention includes the developing device according to any one of the first to sixth aspects or the process cartridge according to the seventh aspect.
Good circulation of the polymerized toner in the longitudinal direction of the developer carrier occurs, and by a good developing operation without toner deterioration,
High quality images will be formed.

[0033]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The following description is an embodiment in which the present invention is applied to an image forming apparatus including a developing device. 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 image forming apparatus to which the present invention is applied. 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 conveying direction by the rotation of the sheet 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 composed of 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 accommodating chamber 52 as a developer accommodating chamber is formed in a case 51, and a first agitator 90 and a second agitator 91 as a developer conveying means are provided in the toner accommodating chamber 52. , The cleaning member 54, and the light shielding member 80 provided therebetween are rotatably provided around the rotation shaft 55. Note that this toner storage chamber 5
The toner 2 is a positively charged non-magnetic one-component developer having an electrical insulating property. Further, light transmitting windows 56 are provided on side walls of the toner storage chamber 52 located on both ends of the rotation shaft 55. Further, the toner storage chamber 52
On the photosensitive drum 20 side, a developing chamber 57 that communicates with the toner storage chamber 52 through the opening A to perform development is formed, and a supply roller 58 and a developing roller 59 are rotatably pivotally supported.
The toner on the developing roller 59 is regulated to a predetermined layer thickness by a thin plate-like elastic layer thickness regulating blade 64 and is used for development.

The transfer roller 21 is pivotally supported rotatably.
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 paper transport rollers 73 and a paper discharge roller 74 for paper transport are respectively provided downstream of the fixing unit 70 in the transport direction, and a paper discharge tray 75 is provided downstream 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 process cartridge 2a, and the process cartridge 2a is detachably attached to the laser beam printer 1. Is provided. Further, the developing device 50 is provided as a developing device cartridge detachably from the process 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.

(Structure of Developing Apparatus) Next, a detailed structure of the developing apparatus 50 according to the present embodiment which has solved the above-described conventional problem will be described with reference to FIGS.

FIG. 2 is a cross-sectional view of the developing device 50 of this embodiment taken along line YY ′ shown in FIG. 3. FIG. 3 is a cross-sectional view of the developing device 50 of this embodiment taken along line XX ′ of FIG. FIG. 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, the light emitting means 60, the light receiving means 61, and the substrates 60b, 61b are illustrated as cross sections, but these are cross sections along the line ZZ 'in FIG.

The developing device 50 in this embodiment is similar to the developing device 50 shown in FIG.
As shown in FIG. 5, the case 51 is detached from the process cartridge 2a shown in FIG. 3 or mounted on the process cartridge 2a with the other components provided in the case 51. 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. In addition,
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).
Are configured to have a predetermined potential difference between them.

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 support portion 64a fixed to the case 51 of the above, and an insulating or conductive silicone rubber, an insulating or conductive fluorine-containing rubber, or an insulating or conductive urethane rubber provided at the tip of the support portion 64a. And a contact portion 64b formed by the above. The contact portion 64b is a support portion 64
It is pressed against the developing roller 59 by the elastic force a. 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 chargeable 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 hydrophobic treatment using a silane coupling agent or the like, has an average particle diameter of 10 nm, and is added in an amount of 0.6% by weight (wt)% of the toner base particles. It is. in this way,
The toner is a suspension-polymerized toner having an extremely spherical shape.
Since 6% by weight (wt) is added as an external additive, it is extremely excellent in fluidity. As a result, a sufficient charge amount can be obtained by frictional charging, so that an image with high transfer efficiency and extremely high image quality can be formed.

A first agitator 9 as a developer conveying means
Reference numeral 0 denotes a 75 μm-thick sheet-like slide formed of PET (polyethylene terephthalate) as a rotary conveyance member on the tip of a support member 90 a formed of a resin such as ABS (acrylonitrile-butadiene-styrene) resin. The contact portion 90b is attached. As shown in FIG. 3, the support member 90a is formed integrally with a rotary shaft 55 supported by both side walls 51a and 51b of the case 51, and a gear 63 is attached to a shaft end of the rotary shaft 55. ing. As shown in FIG. 2, the sliding contact portion 90 b has a width (length in the rotational radius direction) such that the sliding contact portion 90 b has a bending and sliding contact when at least slidingly contacting the cylindrical bottom portion 52 a of the toner storage chamber 52. )have. Therefore, when a rotational driving force from a motor (not shown) is transmitted to the gear 63, the first agitator 90 including the support member 90a and the sliding contact portion 90b rotates in the direction of the arrow shown in FIG. 2, and the sliding contact portion 90b is bent. In this state, the bottom surface 52a of the toner storage chamber 52 is brought into sliding contact, and the toner is pushed up to the opening A by the transport surface. Note that in FIG. 3, the opening A is blacked out, and the portion hidden by the support member 90 a in FIG. 3 is indicated by a dotted line. As shown in FIG. 3, the sliding contact portion 90b is provided with cuts 90d corresponding to both end positions of the opening A.
The main transport portion of the sliding contact portion 90b sandwiched between the notches 90d enters the opening A so as to be elastically repelled, and repels the toner toward the developing chamber 57 side. Further, not only the sliding contact portion 90b but also the surface of the support member 90a pushes up the toner. Therefore, the support member 90a has an opening 90c as shown in FIG.
The surface a is configured to reduce the resistance received from the toner during rotation. Further, the longitudinal length of the support member 90a and the sliding contact portion 90b is set to be shorter than the longitudinal length of the case 51, and as shown in FIG. The side portions are arranged so as to have a predetermined interval so as not to contact the light transmission windows 56a and 56b on both sides.

Further, in the present embodiment, a second agitator 91 which constitutes a developer conveying means together with the first agitator 90 is provided. The second agitator 91 is
A support member 91a formed integrally with the support member 90a of the first agitator 90 and made of a resin such as ABS resin.
And a transport unit 91b in the form of a PET sheet as a rotary transport member attached to the support member 91a. The support member 91a formed integrally with the support member 90a is, as is apparent from FIG.
a is attached only to the central portion in the longitudinal direction. The support member 91a rotates with the rotation of the support member 90a, and the transport unit 91b pushes the toner in the toner storage chamber 52 to the opening A prior to the sliding contact portion 90b. As described above, in the present embodiment, the toner carrying capacity from the toner storage chamber 52 to the developing chamber 57 is configured to be stronger at the central portion than at both ends in the longitudinal direction.

The cleaning member 54 includes the first agitator 90
Support member 54a formed integrally with the support member 90a of FIG.
And wipers 54b attached to both ends of the support member 54a as shown in FIG. Wiper 5
4b is formed of urethane rubber,
The surface of the light transmitting windows 56a and 56b is rubbed along with the rotation of 4a, and is mounted at a position where the toner on the surface can be wiped off. In addition, as an example, the support member 54a is parallel to the support member 90a of the first agitator 90 in the opposite direction, that is, the support member 90a of the first agitator 90.
Are set to be 180 degrees.

The light transmitting window 56 is a transparent or translucent member made of acrylic, polycarbonate, polypropylene, or the like. As shown in FIG. 3, the light transmitting window 56 is attached to the side wall 51a on the light emitting means 60 side of the case 51. Window 5
6a 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 as shown in FIG.
The wiper 54b of the cleaning member 54 is securely connected to the light transmitting window 5
The surfaces of 6a and 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 90 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 transmission windows 56a, 5
At the position corresponding to 6b, as shown in FIG.
a and 62b are formed, the opening 62a allows light to enter the light transmitting window 56a, and the opening 62b allows light to exit from the light transmitting window 56b.

As shown in FIG. 3, light emitting means 60 and light receiving means 61 are provided on both sides of the developing device 50 in correspondence with the positions where the light transmitting windows 56a and 56b 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.

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, and the opening 62 of the process cartridge 2a described above.
a, light transmission window 56a, light transmission window 56b, opening 62b of process cartridge 2a, plastic lens 61
3, and the light receiving element 61c is set so as to be substantially aligned on a straight line as shown in FIG. 3, and the light emitted from the light emitting element 60c is made substantially parallel by the plastic lens 60d, and the aperture 62a Through the light transmission 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. 4, 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.

Next, the light shielding member 80 will be described. As shown in FIG. 2, the light shielding member 80 includes a first agitator 90.
Is provided between the supporting member 90a of the cleaning member 54 and the supporting member 54a of the cleaning member 54, and is a plate-shaped member formed of a resin such as ABS resin, and is integrally formed with the rotating shaft 55 together with the first agitator 90 and the cleaning member 54. And is configured to rotate around a rotation axis 55. In addition, in the axial direction of the rotation shaft 55, as shown in FIG. 3, it is provided only on the light emitting means 60 side.

The light shielding member 80 is set immediately after the first agitator 90 has passed the position of the light transmitting window 56b (, 56a).
As shown in FIG. 2, it has a light-shielding surface large enough to block light to the light-transmitting window 56b and release the light-blocking immediately before the cleaning member 54 starts cleaning the light-transmitting window 56b (56a). .

With this configuration, while the light shielding member 80 blocks the optical path, the toner around the light transmitting window 56b (, 56a) is scraped off by the scraping operation of the first agitator 90. Even in this case, the output from the light receiving element 60c is not obtained, so that the remaining amount of the developer can be accurately detected regardless of the environmental conditions or the usage period. Further, since the light shielding member 80 is configured to rotate around the common rotation axis 55 with the cleaning member 54 and the first agitator 90, the configuration can be simplified.

(Operation Example) Hereinafter, an operation example of the present embodiment will be described in detail focusing on the operation of the first agitator 90, the second agitator 91, and the cleaning member 54, detecting the remaining amount of toner.

First, the uppermost surface of the toner (hereinafter, referred to as a 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, first, before the first agitator 90 is rotated, the transport unit 91b pushes out the toner in the central portion in the width direction of the toner storage chamber 52 by the rotation of the second agitator 91 as shown in FIG. As described above, the toner in the central portion in the width direction of the toner storage chamber 52 is transported to the developing chamber 57 with the movement reaching the vicinity of the opening A and further passing through the opening A. At this time, as shown in FIG. 7, the sliding portion 90b of the first agitator 90 conveys the toner in the entire widthwise direction of the toner storage chamber 52 while slidingly contacting the wall surface of the toner storage chamber 52 and transfers the toner to the opening A. As the sliding contact portion 90b of the first agitator 90 reaches the opening A as shown in FIG. 2 and further passes through the opening A, as shown in FIG. The toner is transported to the developing chamber 57.

Therefore, in the developing chamber 57, first, the second
The agitator 91 supplies the toner to the central portion in the width direction of the developing chamber 57, and immediately thereafter, the first agitator 90 supplies the toner over the entire area in the width direction of the developing chamber 57, so that the toner is supplied to the developing chamber. The pushing pressure is increased only at the center of the developing chamber 57 in the width direction. In the present embodiment, as described above, the polymer toner having an extremely high fluidity is used. Therefore, when the indentation pressure of the polymer toner is increased in the central portion, the polymer toner pressed in the developing chamber 57 becomes 57 is returned to the toner accommodating chamber 52 from the opening A through both end sides. That is, in the developing device of the present embodiment, the toner circulates in the developing chamber 57 in the width direction of the developing chamber 57, that is, in the longitudinal direction of the developing roller 59, so that the toner is not significantly consumed by printing. Even at both ends in the longitudinal direction, the stagnation of the toner can be reliably prevented. As a result, good printing can be performed without causing deterioration of the toner.

However, if the width of the second agitator 91 is smaller than 1/4 of the width of the opening A, the toner does not circulate to the end. If it is larger than 3/4, the toner does not circulate in the longitudinal direction. As a result of the experiment, it was found that the width of the second agitator 91 with respect to the width of the opening A was preferably about 1/2, but in the present embodiment, it was set to about 4/9. In an experiment conducted to examine the relationship between the width of the opening A and the width of the second agitator 91, a developing device in which the ceiling of the developing chamber was cut was prepared, and the internal toner circulation was visually checked. Further, a durability test (for example, printing of 10,000 sheets) was performed to evaluate the image.
In the case of the agitator or the second agitator larger than ／, print fog occurred at the end of the paper after the endurance. 1
With the second agitator having a size of ４ and ／, fogging was slightly generated at the end of the sheet after running, but it was barely endurable. For a new toner, the second agitator smaller than 1/4 or 3 /
Even when the second agitator larger than 4 was used, the circulation was sometimes performed. However, when the fluidity of the toner decreased after the endurance, it was visually observed that the circulation became unstable or stopped. I was able to confirm.

As described above, it has been found that the width of the second agitator 91 is preferably not less than １ ／ and not more than ／ of the width of the opening A.

According to the method of this embodiment, FIGS.
Even if the height of the partition wall (the lower end wall of the opening A) 53 between the toner storage chamber 52 and the developing chamber 57 shown in FIGS. Therefore, a decrease in density due to an insufficient amount of toner supplied to the developing roller 59 does not occur. In addition, since the first agitator 90 is configured to have a width larger than the width of the opening A, the supply of toner does not become insufficient over the entire width of the developing chamber 57.

Further, since the toner circulates favorably in the longitudinal direction of the developing roller 59, there is no toner supply unevenness, and no vertical stripe-like image density unevenness occurs in printing.

The sliding portion 91b of the second agitator 91
And the leading end of the sliding contact portion 90b of the first agitator 90 are configured to enter the developing chamber 57 from the opening A, so that the toner is preferably pushed into the developing chamber 57,
The above-described circulation performance can be further improved.

The rubbing portion 91b of the second agitator 91
And the sliding contact portion 90b of the first agitator 90 is made of PET.
Etc., and its thickness is 50μ.
m thicker. As a result of the experiment, it has been found that when the thickness is smaller than 50 μm, the supply of the toner to the developing chamber 57 becomes insufficient.
Since the thickness is larger than μm, the toner can be sufficiently supplied to the developing chamber 57. In the present embodiment, the thickness of the sliding contact portion 90b is smaller than 100 μm. As a result of the experiment, when the sheet is thicker than 100 μm, when the sheet is deflected, an unusual sound is generated when the sheet pops. However, according to the present embodiment, the thickness of the sliding contact portion 90 b is made thinner than 100 μm. Therefore, such abnormal noise does not occur. As a result of the experiment, it was found that the optimum thickness of the sliding contact portion 90b was 75 μm.

Further, for example, when the toner carrying capacity at both ends in the width direction of the developing chamber 57 is made stronger than that at the center, toner supplied from both ends comes to meet at the center. In this case, there is a problem that image density unevenness occurs. However, according to the configuration of the present embodiment, since there is no such collision of the toner in the central portion, it is possible to reliably prevent such image density unevenness.

The first agitator 90 described above is used.
Passes through the vicinity of the light transmission windows 56a and 56b, so that toner near the light transmission windows 56a and 56b may be conveyed. However, in the present embodiment, the first
When the agitator 90 moves from the position shown in FIG. 7 to the position shown in FIG. 2, the light shielding member 80 blocks the optical path between the light transmitting window 56a and the light transmitting window 56b as shown in FIG. Therefore,
When passing through the first agitator 90, the light transmitting windows 56a, 56
b, the light receiving element 61c
Keeps the output at a high level and does not cause a noise-like change in the output signal as in the conventional device. And
When 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. 5, the light transmitting windows 56a and 56b are covered with the toner immediately after wiping by the wiper 54b. However, when the wiper 54b rotates from the position shown in FIG. 5 to the position shown in FIG. 6, the sliding contact portion 90b of the first agitator 90
6, the toner is pushed out in the direction of arrow B shown in FIG.
a, 56b. Thus, the sliding contact portion 9
0b through the light transmitting window 56
The time during which a and 56b are covered depends on the amount of toner. That is, the larger the amount of toner, the longer the light transmission window 5
6a and 56b are blocked, and the time for blocking the light transmitting windows 56a and 56b becomes shorter as the toner amount becomes 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.
The low level period T1 of the output of the light receiving element 61c shown in FIG. In the present embodiment, the control unit (not shown) samples and stores the value of the output voltage of the light receiving element 61c at a predetermined sampling period, and the ratio of the total of the low-level period T1 within the predetermined measurement unit period T2 is: When a predetermined ratio is exceeded, it is determined that the toner is in the empty state.

As described above, the developing device 50 of the present embodiment
In the above, the surfaces of the light transmitting windows 56a and 56b are wiped by the wiper 54b of the cleaning member 54, and the toner in the toner storage chamber 52 is pushed out by the first agitator 90, so that the light transmitting windows 56a and 56b Between the first agitator 90 and the first agitator 90.
Immediately after passing through the light transmitting windows 56a and 56b.
By blocking the optical path between the light transmitting window 56a and the light transmitting window 56b with 0, a change in the output of the light receiving element 61c caused by the behavior of the first agitator 90 is prevented, so that accurate toner remaining amount detection is performed. be able to.

In the above description, the second agitator 91 is provided so that the toner conveying capacity at the central portion in the longitudinal direction of the developing roller 59 is made higher than that at both end portions. The configuration is not limited to this, and for example, more agitators may be provided in the central portion. Also, it is not necessary to have a plurality of agitators, and even if a single agitator is used, the length from the rotating shaft to the free end of the sliding contact portion is
You may comprise so that a center part may become longer than both ends. Alternatively, the surface of the sliding contact portion of the agitator may be processed into a mesh shape, and the mesh roughness may be configured such that both end portions are rougher than the central portion.

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

[0079]

According to the first aspect of the present invention, there is provided a developing device using a polymerized toner produced by a polymerization method as a developer, and a central portion in the longitudinal direction of an opening for communicating the developer storing chamber with the developing chamber. The developer carrying means from the developing chamber to the developing chamber is higher than the developer carrying performance at both ends of the opening in the longitudinal direction. In the width direction, the height of the central portion is higher than that of both ends, so that the polymerized toner can be circulated in the width direction of the development chamber, that is, in the longitudinal direction of the developer carrying member. as a result,
It is possible to prevent stagnation at both ends of the developer carrying member, and to perform favorable development without toner deterioration.

According to a second aspect of the present invention, the developer transport means includes a plurality of rotary transport members having a common rotation axis, and the width of at least one of the rotary transport members in the longitudinal direction is reduced by the opening. Is formed in a size equal to or greater than the width in the longitudinal direction, and at least another rotary conveying member is provided only in the central portion in the longitudinal direction with respect to the rotating portion, so that insufficient supply of the developer to the developer carrying member is ensured. In addition, by circulating the polymerized toner in the width direction of the developing chamber, that is, in the longitudinal direction of the developer carrier, stagnation at both ends of the developer carrier is prevented, and good development without toner deterioration is performed. be able to.

According to a third aspect of the present invention, there is provided a developing device, wherein a plurality of rotary conveying members having a common rotation axis in a developer accommodating chamber are used, using a polymerized toner produced by a polymerization method as a developer. The longitudinal width of at least one of the rotary conveying members is formed to be equal to or greater than the longitudinal width of the opening,
Since at least the other rotary transporting member includes the developer transporting means provided only in the central portion in the longitudinal direction with respect to the rotating portion, it is possible to reliably prevent insufficient supply of the developer to the developer carrier. In addition, by circulating the polymerized toner in the width direction of the developing chamber, that is, in the longitudinal direction of the developer carrying member, stagnation at both ends of the developer carrying member can be prevented, and good development without toner deterioration can be performed.

According to the fourth aspect of the present invention, since the distal end of the developer conveying means enters the developing chamber through the opening, the polymerized toner can be suitably pushed into the developing chamber. Thus, the toner circulation performance in the width direction of the developing chamber can be further improved.

According to the fifth aspect of the present invention, the height of the upper surface of the lower end wall of the opening is made higher than the upper surface of the developer supply means. The return of the polymerized toner to the chamber can be suppressed, and the insufficient supply of the toner to the developer carrier can be reliably prevented. Moreover, according to the present invention, even if the height of the lower end wall of the opening is not so low, good toner circulation occurs in the width direction of the developing chamber as described above, so that the deteriorated toner stays there. Can be prevented.

According to the developing device of the present invention, the developer conveying means is provided with a rotary conveying member formed of a resin sheet, and the sheet is formed to have a thickness of more than 50 μm and less than 100 μm. A sufficient toner supply force from the developer accommodating chamber to the developing chamber can be obtained, and at the same time, bending of the sheet is released, and abnormal noise at the time of popping can be reliably prevented.

According to the process cartridge of the present invention, since the developing device of any one of the first to sixth aspects is provided in addition to the electrostatic latent image carrier, the process cartridge in the longitudinal direction of the developer carrier is provided. Good circulation of the polymerized toner occurs, and a good developing operation without toner deterioration can be performed.

According to the eighth aspect of the present invention, since the image forming apparatus includes the developing device according to any one of the first to sixth aspects, or the process cartridge according to the seventh aspect, the image forming apparatus is provided in the longitudinal direction of the developer carrier. Good circulation of the polymerized toner can be generated, and a high quality image can be formed by a good developing operation without toner deterioration.

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

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 3);

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser beam printer 50 Developing devices 51a, 51b Side wall 52 Toner storage chamber 54 Cleaning member 54b Wiper 56 Light transmission window 57 Developing room 59 Developing roller 60 Light emitting means 61 Light receiving means 80 Light shielding member 90 First agitator 90a Support member 90b Sliding contact portion 91 second agitator 91a support member 91b transport section

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2H071 BA04 BA13 BA42 DA08 DA09 DA15 DA23 2H077 AA12 AA20 AA26 AA35 AB04 AB07 AB13 AB15 AB18 AC03 AC04 AD02 AD06 AD13 AD17 BA02 BA03 BA09

Claims (8)

[Claims] 1. A developer accommodating chamber for accommodating a polymerized toner produced by a polymerization method as a developer therein, a developer carrier, and a developer supply unit for supplying the developer to the developer carrier. A developing chamber, an opening for communicating the developer accommodating chamber with the developing chamber, and a rotatably provided interior of the developer accommodating chamber, from the developing accommodating chamber at a longitudinal central portion of the opening. And a developer transporting means for enhancing the developer transporting performance to the developing chamber than the developer transporting performance at both ends in the longitudinal direction of the opening. 2. The developer conveying means includes a plurality of rotary conveying members having a common rotation axis, and a longitudinal width of at least one of the rotational conveying members is equal to or greater than a longitudinal width of the opening. The developing device according to claim 1, wherein at least another rotary conveyance member is provided only at a central portion in a longitudinal direction with respect to the rotating portion. 3. A developer accommodating chamber for accommodating therein a polymerized toner produced by a polymerization method as a developer, a developer carrier, and a developer supply unit for supplying the developer to the developer carrier. A developing chamber, an opening for communicating the developer storage chamber with the development chamber, and a plurality of rotary transport members having a common rotation axis inside the developer storage chamber, and at least one rotary transport The longitudinal width of the member is formed to be equal to or greater than the longitudinal width of the opening, and at least another rotary conveying member is provided only in the central portion in the longitudinal direction with respect to the rotating portion. And a developer conveying means provided. 4. The developing device according to claim 1, wherein said developer conveying means is set so that a front end thereof enters said developing chamber from said opening. 5. The height of the upper surface of the lower end wall of the opening is
The developing device according to claim 1, wherein the developing device is formed so as to be higher than an upper surface of the developer supply unit. 6. The developer conveying means includes a rotary conveying member formed of a resin sheet, and the sheet has a thickness of 50 μm.
The developing device according to claim 1, wherein the developing device is formed to be thicker and thinner than 100 μm. 7. A process cartridge detachably formed in an image forming apparatus, comprising: a carrier for the electrostatic latent image; and a developing device according to claim 1. A process cartridge characterized by the above-mentioned. 8. An image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 7.