JP5083018B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus that can accurately know the degree of toner deterioration.

In the cartridge type developing device, the toner deteriorates with long-term use, and therefore it is necessary to replace the toner with a new toner as appropriate. Therefore, it is necessary to know the degree of toner deterioration. Conventionally, for example, the degree of toner deterioration is determined based on the state of an image formed on a photoreceptor.
Japanese Patent Laid-Open No. 10-339888

  However, the conventional method has a problem that it cannot be determined whether the defect appearing in the image is caused by the deterioration of the photoreceptor or the toner.

  An object of the present invention is to provide a developing device and an image forming apparatus capable of accurately knowing the degree of toner deterioration.

  The developing device of the present invention supplies a toner containing at least colored particles and an external additive to a latent image carrier to develop the latent image. In the developing device, the toner has a number average primary particle diameter of 50 to 1000 nm. A toner carrier that contains at least an external additive, and that carries the toner and develops the latent image formed on the latent image carrier, and temporarily stores the toner while stirring. And a supply member that supplies toner in the storage space to the toner carrier, and further includes detection means for detecting a change in the color tone of the toner in the storage space. It is characterized by that.

  The detecting means includes an irradiating means for irradiating the toner in the storage space with light, a transmitted light generated by the irradiated light passing through the toner, or a reflected light generated by reflecting the irradiated light by the toner. A lightness detecting means for detecting the lightness of the toner, a color difference between the detected lightness and a predetermined reference value, determining whether the color difference falls within a predetermined range, and indicating a determination result; And a determination unit.

  Both the irradiation means and the lightness detection means may be provided inside the apparatus.

  At least one of the irradiation unit and the brightness detection unit may be provided outside the apparatus.

  The image forming apparatus of the present invention is characterized by including one or more of the developing devices described above.

[About toner]
The toner used in the present invention contains at least colored particles and an external additive, and particularly contains at least an external additive having a number average primary particle diameter of 50 to 1000 nm. The colored particles contain at least a resin and a colorant. The external additive is attached to the surface of the colored particles. From the viewpoint of improving the fluidity of the toner, it is preferable to further contain an external additive having a number average primary particle size of 4 to 30 nm. Moreover, it is preferable to contain a wax from a viewpoint of improving mold release property.

  Since the present invention is an apparatus that can accurately know the degree of toner deterioration based on the change in toner color tone, in the present invention, in particular, a one-component developer, further a non-magnetic one-component developer, Is preferably used. In the present invention, a two-component developer may be used.

  When a two-component developer is used in the present invention, a full-color image can be formed at a high speed using a tandem image forming apparatus.

  Moreover, as a carrier which is a magnetic particle used with a two-component developer, the following material can be used, for example. Metals such as iron, ferrite, and magnetite; alloys of these metals with metals such as aluminum and lead. Of these, ferrite is most preferred. As a volume average particle diameter of a carrier, 15-100 micrometers is preferable and 25-80 micrometers is more preferable.

  Hereinafter, each component of the toner used in the present invention will be described.

(1) Colored particles The colored particles are not particularly limited, and can be produced by a conventionally known production method such as a pulverization method or a polymerization method. The pulverization method is a method through a kneading step, a pulverization step, and a classification step. The polymerization method is a method of forming particles while polymerizing a polymerizable monomer and simultaneously controlling the shape and size. Examples thereof include an emulsion polymerization method, a suspension polymerization method, and a polyester elongation method.
The colored particles contain at least a resin and a colorant.

(1-1) Colorant The colorant is not particularly limited, but specifically, the following can be used.

(1-1-1) Black colorant for black toner Carbon black, titanium black, etc.
As carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like can be used.

(1-1-2) Yellow colorant for yellow toner C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, etc. In addition, C.I. I. Pigment Yellow 14, 17, 17, 74, 93, 94, 138, 155, 180, 185, etc. Also a mixture of these.

(1-1-3) Magenta Colorant for Magenta Toner C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, etc. In addition, C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, etc. Also a mixture of these.

(1-1-4) Cyan colorant for cyan toner C.I. I. Pigment Blue 15: 3 etc.

  The number average primary particle diameter of the colorant in the toner in a dispersed state varies depending on the type, but is preferably about 10 to 200 nm.

  The addition amount of the colorant is 1 to 10% by mass, preferably 2 to 8% by mass in the toner. If it is less than 1% by mass, the coloring power of the toner may be insufficient. If it exceeds 10% by mass, the colorant is liberated, which may affect the chargeability.

(1-2) Resin The resin is not particularly limited, but is typically a polymer formed by polymerizing a polymerizable monomer. The polymer is formed using only one type of polymerizable monomer or a plurality of types thereof. A representative example of the polymerizable monomer is a vinyl monomer. Specific examples of vinyl monomers are shown below.

(1-2-1) Styrene or styrene derivatives Styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-chloro styrene, 3,4-dichloro styrene, p-phenyl styrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn -Dodecyl styrene and the like.

(1-2-2) Methacrylic acid ester derivatives Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate , Stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and the like.

(1-2-3) Acrylic acid ester derivatives Methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate , Stearyl acrylate, lauryl acrylate, phenyl acrylate and the like.

(1-2-4) Olefin Ethylene, propylene, isobutylene, etc.

(1-2-5) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate, etc.

(1-2-6) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether, etc.

(1-2-7) Vinyl ketones Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like.

(1-2-8) N-vinyl compounds N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like.

(1-2-9) Other Vinyl compounds such as vinyl naphthalene and vinyl pyridine; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

(1-2-10) Having an ionic dissociation group Since the colorant of the present invention has weak alkalinity, the ionic dissociation group such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group can be substituted with a side chain. When the vinyl monomer contained in is used as a resin, the dispersibility of the colorant in the resin can be improved. A specific example is shown below.

(1-2-10-1) Those having a carboxyl group Acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, and the like.
(1-2-10-2) Those having a sulfonic acid group Styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, and the like.
(1-2-10-3) Those having a phosphate group Acid phosphooxyethyl methacrylate and the like.

(1-2-11) Polyfunctional vinyl monomer By using this monomer, a resin having a crosslinked structure can be produced. A specific example is shown below.
Divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, and the like.

(2) External additive (2-1) External additive having a number average primary particle diameter of 50 to 1000 nm For example, fine particles of the following materials can be used.
Metal oxides such as titanium oxide, alumina, zirconia and silica; titanate compounds such as strontium titanate, barium titanate and calcium titanate; silicone resins; vinyl resins such as methyl methacrylate, styrene and styrene acrylic copolymers ; Urethane and the like.

  From the viewpoint of evaluating the change in color tone, a titanic acid compound is particularly preferable.

  As addition amount, 0.1-2 mass% is preferable. When the addition amount is too small, it becomes difficult to measure a change in toner color tone. When the addition amount is excessive, a large amount of external additive having a large particle size is liberated from the colored particles, and as a result, there is a risk of damaging the photoreceptor or the toner carrier.

(2-2) External additive having a number average primary particle size of 4 to 30 nm When this external additive is added, the fluidity and chargeability of the toner are improved, and the cleaning property is improved.

For example, the following inorganic fine particles can be used.
Silica, titania, alumina, strontium titanate, etc. Moreover, what hydrophobized these inorganic substances can also be used as needed.

(2-2-1) Silica R-805, R-976, R-974, R-972, R-812, R-809, etc., which are commercial products manufactured by Nippon Aerosil Co., Ltd. HVK-2150 and H-200, which are commercial products manufactured by Hoechst. TS-720, TS-530, TS-610, H-5, MS-5, etc., which are commercially available products manufactured by Cabot Corporation.

(2-2-2) Titania Commercial products manufactured by Nippon Aerosil Co., Ltd., such as T-805 and T-604. MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, JA-1, etc., which are commercially available products from Teica. TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T, etc., which are commercial products manufactured by Fuji Titanium. IT-S, IT-OA, IT-OB, IT-OC, etc., which are commercial products manufactured by Idemitsu Kosan Co., Ltd.

(2-2-3) Alumina RFY-C, C-604, etc., which are commercial products manufactured by Nippon Aerosil Co., Ltd. Ishihara Sangyo's commercial product, TTO-55, etc.

  As addition amount, 0.1-10.0 mass% is preferable. Moreover, as an addition method, the method of adding using various well-known mixers, such as a turbuler mixer, a Henschel mixer, a Nauta mixer, and a V-type mixer, can be used.

(3) Wax For example, the following wax can be used.

(3-1) Polyolefin wax Polyethylene wax, polypropylene wax and the like.

(3-2) Long-chain hydrocarbon wax Paraffin wax, sazol wax, etc.

(3-3) Dialkyl ketone waxes such as distearyl ketone.

(3-4) ester wax Carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, Glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate and the like.

(3-5) Amide wax Ethylenediamine dibehenylamide, trimellitic acid tristearylamide and the like.

  The content of the wax is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass.

  According to the developing device of the present invention, by appropriately setting “predetermined reference value” and “predetermined range” in the determination unit, the state immediately before excessive toner deterioration is indicated as a determination result indicating “belongs”. be able to. Therefore, according to the developing device of the present invention, it is possible to know in advance the excessive deterioration of the toner, and therefore it is possible to accurately know when the toner is replaced.

  According to the image forming apparatus of the present invention, by appropriately setting the “predetermined reference value” and the “predetermined range” in the determining unit, the state immediately before the excessive deterioration of the toner is determined as the determination result that “belongs”. Can show. Therefore, according to the image forming apparatus of the present invention, it is possible to know in advance the excessive deterioration of the toner, and therefore it is possible to accurately know when the toner is replaced. In particular, when the image forming apparatus of the present invention is a tandem type, the toner is excessively deteriorated for each developing device by appropriately setting “predetermined reference value” and “predetermined range” in the determination unit. You can know in advance. Therefore, according to the image forming apparatus of the present invention, it is possible to accurately know the toner replacement time for each developing device.

  First, the developing device of the present invention will be described.

[Developer]
(First embodiment)
FIG. 1 is a longitudinal sectional view of the developing device of the present embodiment, and FIG. 2 is a transverse sectional view. The developing device 10A of this embodiment is a cartridge type, and an upper screw 1, a lower screw 2, a supply roller (supply member) 3, a development roller (toner carrier) 4, and a storage space are provided in a housing 100. Part 5.

  In the developing device 10A, the toner replenished into the housing 100 from a toner hopper (not shown) above the upper screw 1 is temporarily stored while being stirred in the storage space 5 by the upper screw 1 and the lower screw 2. Thereafter, the toner is supplied to the developing roller 4 by the supply roller 3 and is carried on the surface of the developing roller 4. The toner is regulated to a certain thickness on the surface of the developing roller 4 by the regulating blade 6. The toner carried on the surface of the developing roller 4 is attached to the photoreceptor (latent image carrier) 7. Thereby, the latent image on the photoconductor 7 is developed by the developing device 10A.

  The developing device 10 </ b> A according to the present embodiment further includes a detection unit that detects a change in the color tone of the toner in the storage space 5. Specifically, the detection means detects the lightness of the toner based on the irradiation means 81 for irradiating the toner in the storage space 5 with light and the transmitted light generated by the irradiation light passing through the toner. A lightness detection means 82A, a determination means (not shown) for obtaining a color difference between the detected lightness and a predetermined reference value, determining whether the color difference is within a predetermined range, and indicating a determination result; It has. The irradiation means 81 and the lightness detection means 82A are provided in the housing 100. The determination unit is provided outside the housing 100. As the determination means, for example, a lamp or a display that is turned on when the obtained color difference “belongs” within a predetermined range can be adopted.

  Incidentally, the toner used in this embodiment contains at least colored particles and an external additive, and particularly contains at least an external additive having a number average primary particle diameter of 50 to 1000 nm. From the viewpoint of improving the fluidity of the toner, it is preferable to further contain an external additive having a number average primary particle size of 4 to 30 nm. The colored particles contain at least a resin and a colorant. The external additive is attached to the surface of the colored particles. When such toner is used in the developing device 10A for a long time, the following changes occur in the toner. That is, the toner is stressed while moving while being stirred. Therefore, a part of the external additive on the surface of the colored particles falls off or is buried in the colored particles. As a result, the amount of external additives present on the surface of the colored particles is reduced, and as a result, the fluidity and chargeability of the toner are lowered, and the developability is lowered. That is, when the external additive present on the surface of the colored particles is reduced, the toner is deteriorated.

  On the other hand, an external additive having a number average primary particle size of 50 to 1000 nm has a property of reflecting a certain amount of light. Accordingly, when the amount of the external additive present on the colored particle surface decreases, that is, when the toner deteriorates, the reflection of light on the toner surface becomes dull.

  Incidentally, in the developing apparatus 10A having the above-described configuration, the irradiation unit 81, the lightness detection unit 82A, and the determination unit are further operated. That is, the irradiation unit 81 irradiates the toner in the storage space 5 with light. The lightness detection means 82A detects the lightness of the toner based on the transmitted light generated when the irradiated light passes through the toner. The determination means obtains a color difference between the detected brightness and a predetermined reference value, determines whether or not the color difference belongs to a predetermined range, and indicates a determination result.

  As described above, when the toner deteriorates, the reflection of light on the toner surface becomes dull, so that the brightness of the toner detected by the brightness detection means 82A becomes small. As a result, the brightness and the predetermined reference value The color difference increases, and the possibility that the color difference falls within a predetermined range increases. That is, when the toner deteriorates, the determination unit indicates a determination result indicating “belongs”. Therefore, according to the developing device 10A having the above-described configuration, the toner deterioration can be indicated as a determination result by the determination unit, and therefore the toner deterioration can be accurately determined.

  Therefore, according to the developing device 10A having the above-described configuration, by appropriately setting the “predetermined reference value” and the “predetermined range” in the determination unit, it is determined that the state immediately before excessive toner deterioration is “belonging”. As a result can be shown. Therefore, according to the developing device 10A of the present embodiment, it is possible to know in advance the excessive deterioration of the toner, and therefore it is possible to accurately know when the toner is replaced.

(Second Embodiment)
FIG. 3 is a longitudinal sectional view of the developing device 10B of the present embodiment. 3, the same reference numerals as those in FIGS. 1 and 2 denote the same or corresponding components.

  In the developing device 10B of the present embodiment, the detection unit includes a lightness detection unit 82B that detects the lightness of the toner based on the reflected light that is generated when the irradiated light is reflected by the toner. The brightness detection means 82B is also provided in the housing 100. Other configurations of the developing device 10B of the present embodiment and the toner used in the developing device 10B are the same as those in the first embodiment.

  Also in the developing device 10B of the present embodiment, the irradiation unit 81, the lightness detection unit 82B, and the determination unit operate. That is, the irradiation unit 81 irradiates the toner in the storage space 5 with light. The lightness detection means 82B detects the lightness of the toner based on the reflected light generated by the irradiation light being reflected by the toner. The determination means obtains a color difference between the detected brightness and a predetermined reference value, determines whether or not the color difference belongs to a predetermined range, and indicates a determination result.

  As described above, when the toner deteriorates, the reflection of light on the toner surface becomes dull. Therefore, the brightness of the toner detected by the brightness detection means 82B becomes small. As a result, the brightness and a predetermined reference value are obtained. And the color difference is likely to fall within a predetermined range. That is, when the toner deteriorates, the determination unit indicates a determination result indicating “belongs”. Therefore, also with the developing device 10B of the present embodiment, the toner deterioration can be shown as a determination result by the determining means, and therefore the toner deterioration can be accurately determined.

  Therefore, even with the developing device 10B of the present embodiment, excessive setting of the toner can be known in advance by appropriately setting the “predetermined reference value” and the “predetermined range” in the determination unit. It is possible to accurately know when the toner is replaced.

(Third embodiment)
FIG. 4 is a longitudinal sectional view of the developing device 10C according to the present embodiment. 4, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding components.

  In the developing device 10 </ b> C of the present embodiment, the irradiation unit 81 and the lightness detection unit 82 </ b> B of the detection unit are provided outside the housing 100. Other configurations of the developing device 10C of the present embodiment and the toner used in the developing device 10C are the same as those of the second embodiment.

  The operation of the developing device 10C of the present embodiment is the same as that of the second embodiment.

  Therefore, even with the developing device 10C of the present embodiment, excessive setting of the toner can be known in advance by appropriately setting the “predetermined reference value” and the “predetermined range” in the determination unit. It is possible to accurately know when the toner is replaced or when new toner is replenished.

  Further, according to the developing device 10C of the present embodiment, since the irradiation unit 81 and the lightness detection unit 82B are provided outside the housing 100, it is possible to prevent the internal configuration of the housing 100 from becoming complicated, and accordingly, the second embodiment. Compared with the developing device 10B, the manufacturing operation can be simplified and the manufacturing cost can be reduced.

(Fourth embodiment)
This embodiment is a modification of the first embodiment. In this developing device, only one of the irradiation unit 81 and the lightness detection unit 82A is provided outside the housing 100.

(Fifth embodiment)
This embodiment is a modification of the second embodiment or the third embodiment. In this developing apparatus, only one of the irradiation unit 81 and the lightness detection unit 82B is provided outside the housing 100.

  Next, the image forming apparatus of the present invention will be described.

[Image forming apparatus]
(First embodiment)
The image forming apparatus of the present embodiment is a tandem type having four units of the developing device 10A of the first embodiment described above along the paper path. Four photoconductors 7 are also provided facing the developing device 10A. A transfer unit, a fixing unit, and the like are also provided.

  The toner used in the four developing devices 10A has the same component composition as the toner used in the developing device 10A of the first embodiment described above, but the colorant in the colored particles is different for each developing device 10A. Specifically, a black toner containing a black colorant, a yellow toner containing a yellow colorant, a magenta toner containing a magenta colorant, and a cyan toner containing a cyan colorant are used.

  According to the image forming apparatus of the present embodiment, a full color image is obtained by operating the four developing devices 10A.

  In the image forming apparatus of the present embodiment, the irradiation unit 81, the lightness detection unit 82A, and the determination unit are further operated for each developing device 10A. That is, the irradiation unit 81 irradiates the toner in the storage space 5 with light. The lightness detection means 82A detects the lightness of the toner based on the transmitted light generated when the irradiated light passes through the toner. The determination means obtains a color difference between the detected brightness and a predetermined reference value, determines whether or not the color difference belongs to a predetermined range, and indicates a determination result.

  As described above, when the toner deteriorates, the light reflection on the toner surface becomes dull, so that the brightness of the toner detected by the brightness detection means 82A becomes small. As a result, the brightness and a predetermined reference value are obtained. And the color difference is likely to fall within a predetermined range. Therefore, according to the image forming apparatus of the present embodiment, the toner deterioration can be indicated as the determination result by the determination unit for each developing device 10A, and therefore the toner deterioration can be accurately determined.

  Therefore, according to the image forming apparatus of the present embodiment, by appropriately setting the “predetermined reference value” and the “predetermined range” in the determination unit, the excessive deterioration of the toner is known in advance for each developing device 10A. be able to. Therefore, according to the image forming apparatus having the above configuration, it is possible to accurately know when the toner is replaced for each developing device 10A.

(Second Embodiment)
The image forming apparatus according to the present embodiment is a tandem type having four developing devices 10B according to the second embodiment described above along the paper path. Other configurations are the same as those of the image forming apparatus according to the first embodiment.

  The toner used in the four developing devices 10B is the same as that of the image forming apparatus of the first embodiment.

  According to the image forming apparatus of the present embodiment, a full color image is obtained by operating the four developing devices 10B.

  In the image forming apparatus of this embodiment, the irradiation unit 81, the lightness detection unit 82B, and the determination unit are further operated for each developing device 10B. That is, the irradiation unit 81 irradiates the toner in the storage space 5 with light. The lightness detection means 82B detects the lightness of the toner based on the reflected light generated by the irradiation light being reflected by the toner. The determination means obtains a color difference between the detected brightness and a predetermined reference value, determines whether or not the color difference belongs to a predetermined range, and indicates a determination result.

  As described above, when the toner deteriorates, the reflection of light on the toner surface becomes dull. Therefore, the brightness of the toner detected by the brightness detection means 82B becomes small. As a result, the brightness and a predetermined reference value are obtained. And the color difference is likely to fall within a predetermined range. Therefore, according to the image forming apparatus of the present embodiment, for each developing device 10B, the toner deterioration can be indicated as a determination result by the determination unit, and therefore the toner deterioration can be accurately determined.

  Therefore, according to the image forming apparatus of the present embodiment, by appropriately setting the “predetermined reference value” and the “predetermined range” in the determination unit, it is possible to know in advance the excessive toner deterioration for each developing device 10B. be able to. Therefore, according to the image forming apparatus having the above configuration, it is possible to accurately know the time of toner replacement for each developing device 10B.

(Third embodiment)
The image forming apparatus of the present embodiment is a tandem type having four units of the developing device 10C of the third embodiment described above along the paper path. Other configurations are the same as those of the image forming apparatus according to the first embodiment.

  The toner used in the four developing devices 10C is the same as that of the image forming apparatus of the first embodiment.

  According to the image forming apparatus of the present embodiment, a full color image is obtained by operating the four developing devices 10C.

  In the image forming apparatus of this embodiment, the irradiation unit 81, the lightness detection unit 82B, and the determination unit are further operated for each developing device 10C. That is, the irradiation unit 81 irradiates the toner in the storage space 5 with light. The lightness detection means 82B detects the lightness of the toner based on the reflected light generated by the irradiation light being reflected by the toner. The determination means obtains a color difference between the detected brightness and a predetermined reference value, determines whether or not the color difference belongs to a predetermined range, and indicates a determination result.

  As described above, when the toner deteriorates, the reflection of light on the toner surface becomes dull. Therefore, the brightness of the toner detected by the brightness detection means 82B becomes small. As a result, the brightness and a predetermined reference value are obtained. And the color difference is likely to fall within a predetermined range. Therefore, according to the image forming apparatus of the present embodiment, the toner deterioration can be indicated as the determination result by the determination unit for each developing device 10C, and therefore the toner deterioration can be accurately determined.

  Therefore, according to the image forming apparatus of the present embodiment, by appropriately setting the “predetermined reference value” and the “predetermined range” in the determination unit, it is possible to know in advance the excessive toner deterioration for each developing device 10C. be able to. Therefore, according to the image forming apparatus configured as described above, it is possible to accurately know when the toner is replaced for each developing device 10C.

(Fourth embodiment)
The image forming apparatus of the present embodiment is a tandem type that has four developing devices of the fourth embodiment described above along the paper path. Other configurations are the same as those of the image forming apparatus according to the first embodiment.

  Also in the image forming apparatus of the present embodiment, as in the first embodiment, the toner is excessively deteriorated for each developing device by appropriately setting “predetermined reference value” and “predetermined range” in the determination unit. Can know in advance. Therefore, according to the image forming apparatus of the present embodiment, it is possible to accurately know the toner replacement time for each developing device.

(Fifth embodiment)
The image forming apparatus of the present embodiment is a tandem type that includes four developing devices of the fifth embodiment described above along the paper path. Other configurations are the same as those of the image forming apparatus according to the first embodiment.

  Also in the image forming apparatus of the present embodiment, as in the first embodiment, the toner is excessively deteriorated for each developing device by appropriately setting “predetermined reference value” and “predetermined range” in the determination unit. Can know in advance. Therefore, according to the image forming apparatus of the present embodiment, it is possible to accurately know the toner replacement time for each developing device.

(Another embodiment)
In the image forming apparatus of the present invention, the number of developing devices provided is not limited to four as in the first to fifth embodiments, and may be one, two, three, or five or more. Also good.

  Examples of the present invention will be described below.

[Example 1]
A full color image was formed with the following image forming apparatus using the following toner under the following conditions and evaluated by the following evaluation method.

(1) Image forming apparatus An image forming apparatus according to the first embodiment.

(2) Toner (2-1) Yellow toner (Toner Y1)
[1] The following toner composition was put into a Henschel mixer (manufactured by Mitsui Miike Mining Co., Ltd.) and mixed for 5 minutes with a stirring blade set at a peripheral speed of 25 m / sec.
-Toner composition-100 parts by weight of polyester resin
(Bisphenol A-ethylene oxide adduct, terephthalic acid, trimellitic acid condensate: weight average molecular weight 20000)
-Colorant (CI Pigment Yellow 74) 5 parts by mass-Release agent (pentaerythritol tetrastearate) 6 parts by mass-Charge control agent (calixarene) 1 part by mass [2] Biaxial extrusion of the above mixture After kneading with a kneader and then roughly pulverizing with a hammer mill, the mixture was pulverized with a turbo mill pulverizer (manufactured by Turbo Kogyo Co., Ltd.), and further finely classified with an airflow classifier utilizing the Coanda effect. Thereby, colored particles having a volume-based median diameter of 5.5 μm were obtained.
[3] Next, the following external additives were added to the colored particles, and external addition processing was performed with a Henschel mixer (manufactured by Mitsui Miike Mining Co., Ltd.) to produce "Toner Y1".
-External additive-Hexamethylsilazane-treated silica (number average primary particle size 12 nm) 0.6 parts by mass-Strontium titanate (number average primary particle size 350 nm) 0.8 parts by mass Was carried out under the conditions of a peripheral speed of 35 m / sec, a treatment temperature of 35 ° C., and a treatment time of 15 minutes.

(2-2) Magenta toner (Toner M1)
“Toner M1” was obtained in the same manner as “Toner Y1” except that “CI Pigment Red 122” was used instead of “CI Pigment Yellow 74”.

(2-3) Cyan toner (Toner C1)
“Toner C1” was obtained in the same manner as “Toner Y1” except that “CI Pigment Blue 15: 3” was used instead of “CI Pigment Yellow 74”.

(2-4) Black toner (Toner Bk1)
“Toner Bk1” was obtained in the same manner as “Toner Y1” except that “Carbon Black” was used instead of “CI Pigment Yellow 74”.

(3) Conditions-A full-color image was set so that each toner pixel was 5%.
・ Printing was executed in 1-sheet intermittent mode.
The amount of toner was set to an amount that can execute printing for 4000 sheets. Specifically, since the consumption amount of each toner at 25% pixel rate is 25 mg / sheet, each toner amount is set to 120 g. In each toner, 20 g is extra, but this is in anticipation of the amount remaining in the storage space of the developing device.
The end of the printing operation is when the predetermined deterioration of the toner, that is, the state immediately before the excessive deterioration of the toner is indicated as the determination result.

(4) Evaluation method (4-1) Solid images (2 cm × 2 cm) of yellow, magenta, cyan, red, blue, and green in an environment of temperature 20 ° C. and humidity 50% RH. The color gamut was expressed in a * -b * coordinates, and the color gamut area was measured and compared with the color gamut area of the first image.
(4-2) In the first blank sheet printing and the blank sheet printing at the end of the printing operation, the relative reflection density with the paper reflection density set to “0” was measured to evaluate the fog.
The evaluation results are shown in Table 1.

[Example 2]
A full-color image was formed by the following image forming apparatus using the following toner under the following conditions, and the following evaluation was performed.

(1) Image forming apparatus An image forming apparatus according to a second embodiment.

(2) Toner Same as Example 1.

(3) Conditions The same as in Example 1.

(4) Evaluation method The same as in Example 1.
The evaluation results are shown in Table 1.

[Example 3]
A full-color image was formed by the following image forming apparatus using the following toner under the following conditions, and the following evaluation was performed.

(1) Image forming apparatus An image forming apparatus according to a third embodiment.

(2) Toner Same as Example 1.

(3) Conditions The same as in Example 1.

(4) Evaluation method The same as in Example 1.
The evaluation results are shown in Table 1.

[Comparative example]
A full-color image was formed by the following image forming apparatus using the following toner under the following conditions, and the following evaluation was performed.

(1) Image Forming Apparatus Each developing device does not have a detection unit, and the rest is the same as the image forming apparatus of the first embodiment.

(2) Toner Same as Example 1.

(3) Conditions • The printing operation was ended when the number counter showed 4000 sheets.
-Others are the same as Example 1.

(4) Evaluation method The same as in Example 1.
The evaluation results are shown in Table 1.

[effect]
According to the image forming apparatuses of the first to third embodiments of the present invention, since the state immediately before the excessive toner deterioration is detected and the printing operation is finished, the excessive toner deterioration can be prevented in advance. It is possible to accurately know when the toner is replaced. Therefore, according to the present invention, it is possible to prevent a defective image from being continuously formed even though the toner is excessively deteriorated, and thus a stable image can be formed. .

  Since the developing device or the image forming apparatus of the present invention can accurately know the degree of toner deterioration, it has great industrial utility value.

It is a longitudinal cross-sectional view of the developing device of 1st Embodiment. FIG. 2 is a transverse sectional view of the developing device of FIG. 1. It is a longitudinal cross-sectional view of the developing device of 2nd Embodiment. It is a longitudinal cross-sectional view of the developing device of 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 Supply roller (supply member) 4 Developing roller (toner carrier) 5 Storage space part 7 Photoconductor (latent image carrier) 81 Irradiation means 82A, 82B Lightness detection means 10A, 10B, 10C Developing device

Claims (5)

In a developing device for developing a latent image by supplying a toner containing at least colored particles and an external additive to a latent image carrier,
The toner contains at least an external additive having a number average primary particle size of 50 to 1000 nm,
A toner carrier that carries toner and develops the latent image formed on the latent image carrier with toner.
A storage space for temporarily storing the toner while stirring;
A supply member for supplying toner in the storage space to the toner carrier;
At least,
A developing device, further comprising detection means for detecting a change in toner color tone in the storage space. The detection means is
Irradiating means for irradiating the toner in the storage space with light;
A lightness detecting means for detecting the lightness of the toner based on transmitted light generated by the irradiated light passing through the toner or reflected light generated by reflecting the irradiated light by the toner;
Determining means for obtaining a color difference between the detected brightness and a predetermined reference value, determining whether the color difference is within a predetermined range, and indicating a determination result;
The developing device according to claim 1, further comprising:   The developing device according to claim 2, wherein both the irradiation unit and the brightness detection unit are provided inside the apparatus.   The developing device according to claim 2, wherein at least one of the irradiation unit and the lightness detection unit is provided outside the apparatus.   An image forming apparatus comprising at least one developing device according to claim 1.

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