KR100370214B1 - Liquid electrophotographic image forming apparatus having squeeze roller for charging and printing method used the same - Google Patents

Liquid electrophotographic image forming apparatus having squeeze roller for charging and printing method used the same Download PDF

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KR100370214B1
KR100370214B1 KR10-2000-0026706A KR20000026706A KR100370214B1 KR 100370214 B1 KR100370214 B1 KR 100370214B1 KR 20000026706 A KR20000026706 A KR 20000026706A KR 100370214 B1 KR100370214 B1 KR 100370214B1
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South Korea
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developing
potential
charging
voltage
photosensitive medium
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KR10-2000-0026706A
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Korean (ko)
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KR20010105784A (en
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경명호
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삼성전자 주식회사
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
    • B41J2/47—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light
    • B41J2/471—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light using dot sequential main scanning by means of a light deflector, e.g. a rotating polygonal mirror
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J13/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets
    • B41J13/02—Rollers
    • B41J13/025—Special roller holding or lifting means, e.g. for temporarily raising one roller of a pair of nipping rollers for inserting printing material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/0457—Power supply level being detected or varied
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
    • B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
    • B41J2/325—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads by selective transfer of ink from ink carrier, e.g. from ink ribbon or sheet
    • B41J2/33—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads by selective transfer of ink from ink carrier, e.g. from ink ribbon or sheet from ink roller
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/385—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material
    • B41J2/39—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material using multi-stylus heads
    • B41J2/40—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material using multi-stylus heads providing current or voltage to the multi-stylus head
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J25/00—Actions or mechanisms not otherwise provided for
    • B41J25/304—Bodily-movable mechanisms for print heads or carriages movable towards or from paper surface
    • B41J25/308—Bodily-movable mechanisms for print heads or carriages movable towards or from paper surface with print gap adjustment mechanisms
    • B41J25/3088—Bodily-movable mechanisms for print heads or carriages movable towards or from paper surface with print gap adjustment mechanisms with print gap adjustment means on the printer frame, e.g. for rotation of an eccentric carriage guide shaft
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0806—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller
    • G03G15/0808—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller characterised by the developer supplying means, e.g. structure of developer supply roller
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0806—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller
    • G03G15/0815—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller characterised by the developer handling means after the developing zone and before the supply, e.g. developer recovering roller

Abstract

대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치 및 인쇄방법이 개시된다. 개시된 화상형성장치는, 감광매체 표면을 소정 레벨의 대전전위로 대전시키는 메인대전기와; 상기 감광매체에 광을 주사하여 그 대전전위를 부분적으로 노광시킴으로써 정전잠상을 형성하는 광주사유니트; 및 상기 정전잠상 영역에 현상액을 현상시키기 위한 현상롤러와, 상기 현상된 현상액을 스퀴징하여 액상의 캐리어를 제거하기 위한 스퀴지롤러를 각각 구비한 Y, C, M, K 현상유니트;를 포함하는 습식 화상형성장치에 있어서, 상기 스퀴지롤러에 직류전압 및 교류전압을 중첩 인가하는 전원;을 포함하여, 상기 스퀴지롤러를 통과한 감광매체의 전위를 균일하게 추가 대전시킴으로써, 상기 현상된 현상액 중 토너가 다음에 통과하는 현상유니트의 현상롤러로 옮겨지는 것을 방지하도록 한다.Disclosed are a wet electrophotographic image forming apparatus and a printing method including a charging squeegee roller. The disclosed image forming apparatus includes: a main charger for charging a surface of a photosensitive medium to a charging potential of a predetermined level; A photowangju unit for scanning the photosensitive medium to form an electrostatic latent image by partially exposing the charge potential; And Y, C, M, K developing units each having a developing roller for developing a developer in the latent electrostatic image region and a squeegee roller for removing a liquid carrier by squeezing the developed developer. An image forming apparatus, comprising: a power source for superimposing a DC voltage and an AC voltage on the squeegee roller, and uniformly charging the potential of the photosensitive medium that has passed through the squeegee roller, thereby causing toner to be developed in the developed solution. Prevent transfer to the developing roller of the developing unit through.

Description

대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치 및 이를 이용한 인쇄방법{Liquid electrophotographic image forming apparatus having squeeze roller for charging and printing method used the same}Liquid electrophotographic image forming apparatus having a squeegee roller and a printing method using the same

본 발명은 감광매체에 화상을 형성시키는 현상유니트에서 감광벨트를 대전시킴과 동시에 현상시 사용된 액상의 캐리어를 제거하는 대전용 스퀴즈롤러를 구비한 습식 전자사진방식 화상형성장치 및 이를 이용한 인쇄방법에 관한 것이다.The present invention relates to a wet electrophotographic image forming apparatus having a charging squeeze roller for charging a photosensitive belt in a developing unit for forming an image on a photosensitive medium and removing a liquid carrier used during development, and a printing method using the same. It is about.

일반적으로, 전자사진방식 화상형성장치는 감광벨트와 같은 감광매체에 화상을 형성하여 인쇄용지에 프린팅하기 위해 제전 →대전 →노광 →현상 →전사단계로 이어지는 기본 프로세스를 갖는다. 감광벨트에 칼라화상을 형성하기 위해서는 상기 대전, 노광 및 현상단계를 통상 4번 반복하게 되며, 화상형성장치의 고속화 추세에 따라 감광벨트의 1회전시 즉, 원사이클에 상기 현상단계를 4번 반복하도록 4개의 현상유니트가 구비된다. 따라서, 각 현상유니트는 Y(옐로우), C(시안), M(마젠타), K(블랙)의 각 칼라별로 현상단계를 반복 수행하여 칼라화상을 형성시킨다.In general, an electrophotographic image forming apparatus has a basic process of forming an image on a photosensitive medium such as a photosensitive belt and printing it on a printing paper. In order to form a color image on the photosensitive belt, the charging, exposing, and developing steps are usually repeated four times, and the developing step is repeated four times in one cycle, that is, in one cycle, according to the high speed trend of the image forming apparatus. Four developing units are provided. Therefore, each developing unit repeats the developing step for each color of Y (yellow), C (cyan), M (magenta), and K (black) to form a color image.

한편, 건식 화상형성장치와는 달리 습식 화상형성장치의 경우에는 토너와,이 토너를 이송하기 위한 액상의 캐리어를 혼합한 현상액을 현상제로 사용한다. 상기 캐리어는 토너와 함께 감광벨트에 현상된 후, 현상된 화상으로부터 제거되어야 한다. 따라서, 습식 화상형성장치의 현상유니트에는 감광벨트에 현상된 현상액으로부터 캐리어를 제거하기 위한 스퀴지장치의 일 예로 스퀴지롤러가 채용되기도 한다. 이러한 스퀴지롤러가 채용된 종래의 습식 전자사진방식 화상형성장치가 도 1에 도시되어 있다.On the other hand, unlike a dry image forming apparatus, in the case of a wet image forming apparatus, a developer in which a toner and a liquid carrier for conveying the toner are mixed is used as a developer. The carrier must be developed on the photosensitive belt together with the toner and then removed from the developed image. Therefore, a squeegee roller may be employed as an example of a squeegee device for removing a carrier from a developer developed on a photosensitive belt as a developing unit of a wet image forming apparatus. A conventional wet electrophotographic image forming apparatus employing such a squeegee roller is shown in FIG.

도 1을 참조하면, 복수의 롤러(11)에 감광벨트(10)가 주행 가능하게 설치되어 있다. 감광벨트(10) 주위에는 상술한 기본 프로세스를 수행하기 위한 제전기(8), 메인 대전기(9), 각 칼라별로 교번되게 설치된 4개의 광주사유니트(12a∼12d)와 4개의 현상유니트(13a∼13d), 드라이유니트(17) 및 전사유니트(19)가 감광벨트(10)의 주행방향으로 순차적으로 설치되어 있다. 감광벨트(10)에 현상된 현상액으로부터 캐리어를 제거하기 위한 스퀴즈롤러(14)와, 현상액을 감광벨트(10)에 현상시키기 위한 현상롤러(15a∼15d)는 각 현상유니트(13a∼13d)에 구비되어 있다. 또한, 감광벨트(10)에 인접하여 각 현상유니트(13a∼13d)의 하류에는 감광벨트(10)를 추가 대전시켜 자연감쇄된 대전전위 레벨을 보상하기 위한 토핑코로나(16)가 설치되어 있다.Referring to FIG. 1, the photosensitive belt 10 is provided on the plurality of rollers 11 so as to travel. Around the photosensitive belt 10, the static eliminator 8 for carrying out the above-described basic process, the main charger 9, four photoreceptor units 12a-12d and four developing units alternately installed for each color ( 13a to 13d, the dry unit 17 and the transfer unit 19 are sequentially provided in the traveling direction of the photosensitive belt 10. The squeeze roller 14 for removing the carrier from the developer developed on the photosensitive belt 10 and the developing rollers 15a to 15d for developing the developer onto the photosensitive belt 10 are provided to each of the developing units 13a to 13d. It is provided. Further, a topping corona 16 is provided downstream of each developing unit 13a to 13d adjacent to the photosensitive belt 10 to further charge the photosensitive belt 10 to compensate for the naturally reduced charge potential level.

상기 구성에 있어서의 인쇄동작을 살펴보면, 감광벨트(10)는 일정속도로 주행되면서 제전기(8)에 의해 잔류 전하성분이 제거되고, 메인 대전기(9)에 의해 그 표면이 약 600-700V의 대전전위로 대전된다. 이어서 감광벨트(10)의 표면에는 하부에 칼라별로 순차적으로 설치된 각 광주사유니트(12a∼12d)에서 주사된 광에 의해순차적으로 노광됨으로써 각 칼라별 화상테이터에 대응되는 정전잠상이 형성된다. 그리고, 각 칼라별 정전잠상은 각 현상유니트(13a∼13d)를 지나면서 메니폴더(7)를 통해 공급된 현상액이 옮겨져 현상된다. 현상된 현상액 중 약 60-70%정도의 캐리어는 스퀴즈롤러(14)에 의해 스퀴징되어 감광벨트(10)에서 제거되고, 나머지는 드라이유니트(17)에서 베이퍼라이징(Vaporizing)된다. 또한, 현상된 현상액 중 분말상의 토너는 스퀴지롤러(14)에 의해 필름화되어 토너화상이 된 후, 전사유니트(19)를 통해 인쇄용지(P)로 최종 인쇄된다.Looking at the printing operation in the above configuration, the photosensitive belt 10 is driven at a constant speed while the residual charge component is removed by the static eliminator 8, and the surface thereof is about 600-700V by the main charger 9. It is charged by the charging potential of. Subsequently, the electrostatic latent image corresponding to the image data for each color is formed on the surface of the photosensitive belt 10 by being sequentially exposed by the light scanned from each of the photoreceptor units 12a to 12d sequentially provided for each color. Then, the electrostatic latent image for each color is developed by transferring the developer supplied through the manifold 7 while passing through each of the developing units 13a to 13d. About 60-70% of the developed developer is squeezed by the squeeze roller 14 to be removed from the photosensitive belt 10, and the rest is vaporized in the dry unit 17. Further, the powdered toner in the developed developer is filmed by the squeegee roller 14 to become a toner image, and then finally printed onto the printing paper P through the transfer unit 19.

한편, 각 칼라별 현상유니트(13a∼13d)에서의 화상형성방법을 대전특성과 관련된 전위모델을 참조하여 구체적으로 설명하면 다음과 같다.On the other hand, the image forming method in each of the color development units 13a to 13d will be described in detail with reference to the potential model associated with the charging characteristic.

즉, 도 2a에 도시된 바와 같이, 약 650V의 대전전위(Vc)로 대전된 감광벨트(10)에는 1차적으로 옐로우 광주사장치(13a)에서 주사된 광에 의해 약 120V의 노광전위(Ve)로 다운되어 옐로우 화상데이터에 대응되는 정전잠상이 형성된다. 이렇게 형성된 옐로우 정전잠상에 옐로우 현상롤러(15a)를 통해 옐로우 현상액을 공급하면서, 그 현상롤러(15a)에 약 450V의 현상전위(Vd)를 인가하면, 노광전위(Ve)와 현상전위(Vd)의 전위차에 의해 현상액 중 하전된 토너성분들이 옐로우 정전잠상으로 옮겨짐으로써 옐로우화상(10a)이 형성된다. 정전잠상으로 이동한 토너성분들의 전위가 현상전위(Vd)와 거의 동일하게 되면, 더 이상의 현상은 생기기 않고 전하평형이 이루어진다. 한편, 현상된 옐로우화상(10a)은 스퀴지롤러(14)에 의한 스퀴지과정에서 필름화됨으로써 캐리어가 약 60-70%정도 제거되어 감광벨트(10)에 남는다.That is, as shown in FIG. 2A, the photosensitive belt 10 charged with the charging potential Vc of about 650V is primarily exposed to an exposure potential Ve of about 120V by the light scanned by the yellow optical scanning device 13a. Down), an electrostatic latent image corresponding to the yellow image data is formed. When the yellow developing solution is supplied to the yellow electrostatic latent image formed through the yellow developing roller 15a, and the developing potential Vd of about 450 V is applied to the developing roller 15a, the exposure potential Ve and the developing potential Vd are applied. The yellow image 10a is formed by transferring the charged toner components in the developing solution to the yellow electrostatic latent image by the potential difference of. When the potentials of the toner components shifted to the electrostatic latent image become almost equal to the developing potential Vd, no further phenomenon occurs and charge balance is achieved. On the other hand, the developed yellow image 10a is filmed in the squeegee process by the squeegee roller 14, so that about 60-70% of the carrier is removed and remains on the photosensitive belt 10.

이어서, 시안 칼라화상 형성단계로 넘어가는데, 그 전에 보조 대전장치인 토핑코로나(16)에서 감광벨트(10)를 추가 대전시킴으로써 옐로우 현상유니트(13a)를 지나면서 자연감쇄된 감광벨트(10)의 대전전위 레벨을 보상시킨다. 그런데, 이 때에는 토핑코로나(16)가 간접접촉방식에 의하여 감광벨트(10)를 대전시킴으로 옐로우화상(10a) 부분과 비화상 부분 사이에는 도 2b에 도시된 바와 같이, 계단형의 전위레벨 상태로 전위차가 발생하게 된다. 이와 같이 감광벨트(10)의 전위가 균일하기 않은 상태에서 시안 광주사장치(12b)로부터 광을 주사하여 시안용 정전잠상을 형성시키면, 감광벨트(10)는 옐로우화상(10a) 부분과 시안용 정전잠상 사이에 큰 전위차가 발생하게 된다. 따라서, 이러한 상태에서 시안 현상액을 현상하게 되면, 옐로우화상(10a) 부분의 전위레벨이 시안 현상롤러(15b)의 현상 바이어스 전위보다 높게 되므로 옐로우화상(10a)으로부터 토너성분이 전위가 낮은 시안 현상롤러(15d)로 역전되는 소위 워시 오프(Wash-off) 현상이 발생된다.Subsequently, the process proceeds to the cyan color image forming step. Before that, the photosensitive belt 10 is additionally charged in the topping corona 16, which is an auxiliary charging device, to pass through the yellow developing unit 13a, thereby reducing the natural state of the photosensitive belt 10. Compensate for the potential level. However, at this time, the topping corona 16 charges the photosensitive belt 10 by an indirect contact method, so that a stepped potential level is shown between the yellow image 10a portion and the non-image portion, as shown in FIG. 2B. The potential difference is generated. In this way, when the potential of the photosensitive belt 10 is not uniform, the light is scanned from the cyan optical scanning device 12b to form an electrostatic latent image for cyan, and the photosensitive belt 10 is used for the yellow image 10a portion and cyan. A large potential difference occurs between the electrostatic latent images. Therefore, when the cyan developer is developed in such a state, the potential level of the portion of the yellow image 10a becomes higher than the development bias potential of the cyan developer roller 15b. The so-called wash-off phenomenon that occurs is reversed to 15d.

또한, 다음의 마젠타 현상액 현상단계에서는 도 2c에 도시된 바와 같이, 옐로우 화상(10a)과 시안 화상(10b) 모두의 전위레벨이 마젠타 현상롤러(15c)의 현상 바이어스 전위보다 크게 된다. 특히 옐로우 화상(10a)은 시안 화상(10b)보다 현상롤러(15c)와의 전위차가 더 커진다. 그리고, 다음의 블랙 현상액의 현상단계에서도 도 2d에 도시된 바와 같이, 각 화상(10a)(10b) 및 마젠타 화상(10c) 각각은 블랙 현상롤러(15d)의 바이어스 전위레벨보다 크게 된다. 따라서, 상기 워시 오프 현상은 각 현상유니트(13a∼13d)를 통과할 때마다 점진적으로 강하게 발생된다.In the following magenta developer development step, as shown in Fig. 2C, the potential level of both the yellow image 10a and the cyan image 10b becomes larger than the development bias potential of the magenta developer roller 15c. In particular, the yellow image 10a has a larger potential difference with the developing roller 15c than the cyan image 10b. Also in the following development step of the black developer, as shown in Fig. 2D, each of the images 10a, 10b and the magenta image 10c is larger than the bias potential level of the black developer roller 15d. Therefore, the wash-off phenomenon is gradually generated strongly each time it passes through each of the developing units 13a to 13d.

그런데, 이와 같이 워시 오프 현상이 발생되면, 각 현상유니트(13a∼13d)에서 적정농도로 현상된 각 화상(10a∼10c)의 토너성분이 현상롤러(15a∼15d)로 씻겨 내려오게 되어 화상(10a∼10c)은 적정농도를 벗어나게 되고, 화상(10a∼10c)에 부분적으로 얼룩이 지거나 화상이 누락된다. 따라서 칼라화상을 인쇄용지에 출력시 불완전한 칼라를 출력하게 된다.By the way, when the wash-off phenomenon is generated in this way, the toner components of the images 10a to 10c developed at the proper concentration in each of the developing units 13a to 13d are washed down with the developing rollers 15a to 15d. 10a to 10c are out of proper concentrations, and the images 10a to 10c are partially stained or missing. Therefore, incomplete color is outputted when printing a color image on printing paper.

또한, 각 화상(10a∼10c)에서 씻겨 내려온 토너가 각 현상유니트(13a∼13d)에 담긴 본연의 현상액과 섞이게 되므로, 각 현상유니트(13a∼13d)의 현상액을 적정농도로 유지시키기 힘들게 된다. 이 경우, 현상액을 교체해 주어야만 하는 번거로움 및 그 교체에 따른 비용이 증가하는 문제점이 있다.In addition, since the toner washed off from each of the images 10a to 10c is mixed with the original developer contained in each of the developing units 13a to 13d, it is difficult to maintain the developer of each of the developing units 13a to 13d at an appropriate concentration. In this case, there is a problem in that the trouble of having to replace the developer and the cost of the replacement increase.

또한, 감광벨트(10)에 인가되는 전압이 각 칼라별 토핑코로나(16)에 의한 추가 대전에 의해 필요이상으로 높아지므로, 감광벨트(10)의 감광특성이 저하되고, 감광벨트(10)의 수명이 단축된다. 따라서, 감광벨트(10)의 잦은 교체에 따른 유지비용이 증가하는 문제점이 있다.In addition, since the voltage applied to the photosensitive belt 10 becomes higher than necessary by the additional charging by the topping corona 16 for each color, the photosensitive characteristic of the photosensitive belt 10 is lowered and the photosensitive belt 10 Life is shortened. Therefore, there is a problem in that the maintenance cost due to frequent replacement of the photosensitive belt 10 increases.

본 발명은 상기와 같은 문제점을 해결하기 위해 창안된 것으로, 감광벨트의 표면전위를 각 칼라 현상단계별로 일정하게 유지시켜서 각 칼라 현상유니트에서의 현상시 워시 오프 발생을 방지함과 동시에 액상의 캐리어를 제거할 수 있도록 개선된 대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치 및 이를 이용한 인쇄방법을 제공하는데 그 목적이 있다.The present invention has been made to solve the above problems, by maintaining the surface potential of the photosensitive belt for each color development step to prevent the wash-off occurs during development in each color development unit and at the same time the liquid carrier It is an object of the present invention to provide a wet electrophotographic image forming apparatus having an improved charging squeegee roller and a printing method using the same.

도 1은 일반적인 습식 화상형성장치의 개략적인 구성도.1 is a schematic configuration diagram of a general wet image forming apparatus.

도 2a 내지 도 2d는 도 1에 도시된 화상형성장치의 현상시 감광벨트의 대전특성을 각 칼라 현상단계별로 나타내 보인 개략적인 도면.2A to 2D are schematic views showing charging characteristics of the photosensitive belt in each color development step when developing the image forming apparatus shown in FIG. 1;

도 3은 본 발명의 실시예에 따른 대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치의 개략적인 구성도.3 is a schematic configuration diagram of a wet electrophotographic image forming apparatus having a charging squeegee roller according to an embodiment of the present invention.

도 4는 본 발명의 실시예에 따른 인쇄방법을 설명하기 위한 흐름도.4 is a flowchart illustrating a printing method according to an embodiment of the present invention.

도 5a 내지 도 5d는 감광벨트에 옐로우 화상을 현상하는 단계에서 감광벨트의 대전특성을 나타내 보인 개략적인 도면.5A to 5D are schematic views showing the charging characteristics of the photosensitive belt in the step of developing a yellow image on the photosensitive belt;

도 6a 및 도 6b는 감광벨트에 시안 화상을 현상하는 단계에서의 감광벨트의 대전특성을 나타내 보인 개략적인 도면.6A and 6B are schematic views showing charging characteristics of the photosensitive belt in the step of developing a cyan image on the photosensitive belt;

도 7a는 감광벨트에 마젠타 화상을 현상하는 단계에서의 감광벨트의 대전특성을 나타내 보인 개략적인 도면.Figure 7a is a schematic diagram showing the charging characteristics of the photosensitive belt in the step of developing a magenta image on the photosensitive belt.

도 7b는 감광벨트에 블랙 화상을 현상하는 단계에서의 감광벨트의 대전특성을 나타내 보인 개략적인 도면.7B is a schematic diagram showing the charging characteristics of the photosensitive belt in the step of developing a black image on the photosensitive belt;

< 도면의 주요부분에 대한 부호의 설명 ><Description of Symbols for Major Parts of Drawings>

20..감광벨트 21..메인대전기20. Photosensitive belt 21. Main electric

22a∼22d..광주사유니트 23a∼23d..현상유니트22a ~ 22d..Gwangju scanning unit 23a ~ 23d .. Developing unit

24..전원 25a∼25d..현상롤러24. Power supply 25a ~ 25d. Develop roller

26a∼26d..스퀴지롤러 27..메니폴더26a ~ 26d..Squeegee roller 27..Mini folder

28..샤프트 29..전도성 고무층28. Shaft 29. Conductive rubber layer

상기 목적을 달성하기 위한 본 발명에 따른 대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치는, 감광매체 표면을 소정 레벨의 대전전위로 대전시키는 메인대전기와; 상기 감광매체에 광을 주사하여 그 대전전위를 부분적으로 노광시킴으로써 정전잠상을 형성하는 광주사유니트; 및 상기 정전잠상 영역에 현상액을 현상시키기 위한 현상롤러와, 상기 현상된 현상액을 스퀴징하여 액상의 캐리어를 제거하기 위한 스퀴지롤러를 각각 구비한 Y, C, M, K 현상유니트;를 포함하는 습식 화상형성장치에 있어서, 상기 스퀴지롤러에 직류전압 및 교류전압을 중첩 인가하는 전원;을 포함하여, 상기 스퀴지롤러를 통과한 감광매체의 전위를 균일하게 추가 대전시킴으로써, 상기 현상된 현상액 중 토너가 다음에 통과하는 현상유니트의 현상롤러로 옮겨지는 것을 방지하도록 된 것을 특징으로 한다.A wet electrophotographic image forming apparatus having a charging squeegee roller according to the present invention for achieving the above object comprises: a main charging unit for charging a surface of a photosensitive medium to a charging potential of a predetermined level; A photowangju unit for scanning the photosensitive medium to form an electrostatic latent image by partially exposing the charge potential; And Y, C, M, K developing units each having a developing roller for developing a developer in the latent electrostatic image region and a squeegee roller for removing a liquid carrier by squeezing the developed developer. An image forming apparatus, comprising: a power source for superimposing a DC voltage and an AC voltage on the squeegee roller, and uniformly charging the potential of the photosensitive medium that has passed through the squeegee roller, thereby causing toner to be developed in the developed solution. It is characterized in that it is prevented from being transferred to the developing roller of the developing unit passing through.

또한, 상기 목적을 달성하기 위한 본 발명에 따른 인쇄방법은, 메인대전기로부터 감광매체로 전압을 인가하여 그 감광벨트의 표면을 소정 대전전위로 유지시키는 단계; 상기 감광매체에 광주사유니트로부터 광을 주사하여 상기 대전전위를 부분적으로 노광시켜 정전잠상을 형성시키는 단계; 상기 정전잠상 영역과 소정 현상전위가 인가되는 현상롤러 사이의 전위차를 이용하여 상기 정전잠상 영역에 현상액을 현상시키는 단계; 및 상기 현상된 현상액을 스퀴지롤러를 이용하여 스퀴징하는 단계;를 포함하는 인쇄방법에 있어서, 상기 스퀴징단계와 동시에 상기 감광벨트의 전위가 균일하게 대전되도록 그 감광벨트에 교류전압과 직류전압을 중첩 인가하는 단계;를 포함하는 것을 특징으로 한다.In addition, the printing method according to the present invention for achieving the above object, the step of applying a voltage from the main charge to the photosensitive medium to maintain the surface of the photosensitive belt at a predetermined charge potential; Scanning the photosensitive medium with light from a photoreceptor unit to partially expose the charge potential to form an electrostatic latent image; Developing a developer in the latent electrostatic image area by using a potential difference between the latent electrostatic image area and a developing roller to which a predetermined developing potential is applied; And squeezing the developed developer by using a squeegee roller. The printing method of claim 1, wherein an AC voltage and a DC voltage are applied to the photosensitive belt such that the potential of the photosensitive belt is uniformly charged at the same time as the squeegeeing step. And applying an overlap.

이하 첨부된 도면을 참조하여 본 발명의 실시예에 따른 대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치를 자세히 설명하기로 한다.Hereinafter, a wet electrophotographic image forming apparatus having a charging squeegee roller according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

도 3을 참조하면, 본 발명의 실시예에 따른 화상형성장치는 감광매체인 감광벨트(20)의 주행방향에 따라 순차적으로 설치된 메인 대전기(21), 복수의 광주사유니트(22a∼22d), 옐로우(Y), 시안(C), 마젠타(M), 블랙(K) 칼라용 현상유니트(23a∼23d) 및 전원(24)을 구비한다.Referring to FIG. 3, the image forming apparatus according to an exemplary embodiment of the present invention includes a main charger 21 and a plurality of photoreceptor units 22a to 22d sequentially installed in accordance with a driving direction of a photosensitive belt 20 as a photosensitive medium. And yellow (Y), cyan (C), magenta (M), black (K) color developing units (23a to 23d), and a power supply (24).

상기 대전기(21)는 감광벨트(20)를 소정 레벨의 대전전위로 대전시킨다. 상기 각 광주사유니트(22a∼22d)는 각 현상유니트(23a∼23d)와 교번되게 설치된다. 각 광주사유니트(22a∼22d)는 감광벨트(20)에 광을 주사하여 감광벨트(20)의 대전전위를 부분적으로 노광시켜 각 칼라별 화상테이타에 대응되는 정전잠상을 형성한다.The charger 21 charges the photosensitive belt 20 to a charging potential of a predetermined level. Each of the photowangsa units 22a to 22d is alternately provided with each of the developing units 23a to 23d. Each photoreceptor unit 22a to 22d scans the photosensitive belt 20 with light to partially expose the charging potential of the photosensitive belt 20 to form an electrostatic latent image corresponding to the image data for each color.

상기 각 현상유니트(23a∼23d)에는 각 칼라에 해당하는 현상액을 상기 각 칼라별로 형성된 정전잠상에 현상시키기 위한 현상롤러(25a∼25d)와, 현상액 중에서 액상의 캐리어를 스퀴징하기 위한 스퀴지롤러(26a∼26d) 및 현상액을 분사하는 메니폴더(27)가 구비된다. 여기서, 상기 현상액은 분말상 토너와 액상의 캐리어가 소정비율로 혼합된 현상제이며, 각 현상유니트(23a∼23d)마다 서로 다른 칼라가 선택적으로 공급된다.Each of the developing units 23a to 23d includes a developing roller 25a to 25d for developing a developing solution corresponding to each color and an electrostatic latent image formed for each of the colors, and a squeegee roller for squeezing a liquid carrier in the developing solution. 26a to 26d) and a manifold 27 for injecting the developer. Here, the developer is a developer in which a powdered toner and a liquid carrier are mixed at a predetermined ratio, and different colors are selectively supplied to each of the developing units 23a to 23d.

상기 현상롤러(25a∼25d)에는 현상시 소정 전원공급부(미도시)로부터 소정 레벨의 바이어스 전압이 인가된다. 따라서, 메니폴더(27)에서 현상롤러(25a∼25d)로 공급된 현상액은 정전잠상의 노광전위와 현상롤러(25)에 바이어스 된 현상전위와의 전위차에 의해 정전잠상으로 옮겨진다.To the developing rollers 25a to 25d, a bias voltage of a predetermined level is applied from a predetermined power supply (not shown) during development. Therefore, the developer supplied from the manifold 27 to the developing rollers 25a to 25d is transferred to the latent electrostatic image by the potential difference between the exposure potential of the electrostatic latent image and the developing potential biased by the developing roller 25.

상기 스퀴지롤러(26a∼26d)는 현상롤러(25a∼25d)에 인접하여 감광벨트(20)에 접촉회전되도록 설치됨으로써, 현상된 현상액을 스퀴징하여 현상액 중 토너를 필름화하고 액상의 캐리어를 제거한다. 또한, 스퀴지롤러(26a∼26d)는 각 현상유니트(23a∼23d)를 통과하면서 자연 감쇄된 감광벨트(20)의 대전전위를 보상하기 위해 감광벨트(20)를 추가 대전시키는 기능을 가진다. 이을 위해 스퀴지롤러(26a∼26d)는 상기 전원(24)으로부터 전압을 인가 받는 금속재질의 샤프트(28)와, 샤프트(28)의 외주에 마련된 도전성 고무층(29)으로 구성된다. 따라서, 전원(24)에서 공급된 전압은 샤프트(28)와 도전성 고무층(29)을 통해 감광벨트(20)에 직접접촉에 의한 대전방식으로 인가된다. 또한, 도전성 고무층(29)은 샤프트(28)에 공급된 전압을 감광벨트(20)로 원활하게 전달할 수 있도록 약 10^7 ∼ 10^12Ω사이의 전기 저항값을 갖는 것이 좋다.The squeegee rollers 26a to 26d are installed to be rotated in contact with the photosensitive belt 20 adjacent to the developing rollers 25a to 25d, thereby squeezing the developed developer to film toner in the developer and removing the liquid carrier. do. In addition, the squeegee rollers 26a to 26d have a function of further charging the photosensitive belt 20 to compensate for the charging potential of the naturally attenuated photosensitive belt 20 while passing through each of the developing units 23a to 23d. To this end, the squeegee rollers 26a to 26d are composed of a metal shaft 28 to which a voltage is applied from the power source 24, and a conductive rubber layer 29 provided on the outer circumference of the shaft 28. Therefore, the voltage supplied from the power source 24 is applied by the charging method by direct contact to the photosensitive belt 20 through the shaft 28 and the conductive rubber layer 29. In addition, the conductive rubber layer 29 may have an electrical resistance value of about 10 ^ 7 to 10 ^ 12 kW so that the voltage supplied to the shaft 28 can be smoothly transmitted to the photosensitive belt 20.

한편, 상기 전원(24)에 스퀴지롤러(26a∼26d)로 인가되는 전압은 추가 대전된 감광벨트(20)의 대전전위가 균일해질 수 있도록 교류전압(DC)과 교류전압(AC)을 중첩하여 인가하는 중첩전압이다. 상기 전원(24)은 복수개가 각 현상유니트(23a∼23d)마다 연결될 수 있다.On the other hand, the voltage applied to the power supply 24 to the squeegee rollers 26a to 26d overlaps the alternating voltage DC and the alternating voltage AC so that the charging potential of the additionally charged photosensitive belt 20 becomes uniform. This is an overlapping voltage to be applied. A plurality of power sources 24 may be connected to each developing unit 23a to 23d.

상기와 같은 구성의 화상형성장치를 이용한 인쇄방법을 자세히 설명하기로 한다.The printing method using the image forming apparatus having the above configuration will be described in detail.

먼저 도 3 내지 도 5a를 참조하면, 인쇄모드 초기에는 감광벨트(20)는 일방향으로 주행되면서 메인대전기(21)에 의해 약 650V의 대전전위(VcY)로 대전된다(S10). 이어서, 옐로우 화상을 형성하는 단계를 수행한다(S11). 이를 위해 먼저, 옐로우 광주사유니트(22a)에서 감광벨트(20)로 광을 주사하면, 도 5b에 도시된 바와 같이, 감광벨트(20)의 대전전위(VcY)가 부분적으로 약 120V의 노광전위(Ve)로 다운되어 옐로우 화상데이타에 대응되는 정전잠상이 형성된다(S12). 이어서, 옐로우 현상롤러(25a)에 약 450V의 현상전위(Vd)를 인가한 상태에서 분사노즐(31)로부터 현상롤러(25a)로 옐로우 현상액을 공급한다. 그러면, 현상롤러(25a)로 옮겨진 현상액은 도 5c에 도시된 바와 같이, 상기 현상전위(Vd)와 상기 노광전위(Ve)와의 전위차에 의해 옐로우 정전잠상으로 옮겨져 옐로우화상(20a)을 형성한다(S13). 옐로우화상(20a)은 감광벨트(20)에 접촉회전되는 옐로우 스퀴즈롤러(26a)에 의해 이미 잘 알려진 방법대로 스퀴징되어 현상액 중 약 60∼70%의 캐리어가 제거된다. 스퀴즈롤러(26a)의 스퀴징과정 중에, 전원(24)에서 스퀴즈롤러(26a)로 교류전압(AC)과 직류전압(DC)이 중첩된 중첩전압을 인가한다. 그러면, 중첩전압은 샤프트(28)와 고무층(29)을 통해 방전되면서 감광벨트(20)를 직접접촉방식으로 대전시킨다(S14). 따라서, 옐로우 현상유니트(23a)를 통과하면서 자연감쇄된 감광벨트(20)의 대전전위가 대략 초기상태와 같이 보상된다. 또한, 감광벨트(20)를 대전시키는 중첩전압은 교류전압(AC)과 직류전압(DC)의 두 가지 주파수특성을 모두 가지므로, 감광벨트(20)의 옐로우 화상(20a)이 형성된 부분과 그 외 비화상부분의 전위를 도 5d에 도시된 바와 같이 균일하게 대전시키게 된다. 이와 같이 스퀴즈롤러(26a)에 전압을 중첩인가하여 감광벨트(20)를 균일하게 대전시킴으로써, 종래의 토핑코로나(16; 도1참조)를 배제한 간단한 구조를 가질 수 있다. 한편, 상술한 바와 같은 중첩전압의 직접접촉에 의한 대전특성은 일본 공개특허 소63-149668호에 개시되어 있으므로 자세한 설명은 생략한다.First, referring to FIGS. 3 to 5A, in the initial stage of the printing mode, the photosensitive belt 20 is charged at a charging potential VcY of about 650 V by the main charging unit 21 while traveling in one direction (S10). Subsequently, a step of forming a yellow image is performed (S11). To this end, first, when the light is scanned from the yellow photonic yarn unit 22a to the photosensitive belt 20, as shown in FIG. 5B, the charging potential VcY of the photosensitive belt 20 is partially exposed to an exposure potential of about 120V. Down to Ve, an electrostatic latent image corresponding to yellow image data is formed (S12). Subsequently, the yellow developing solution is supplied from the injection nozzle 31 to the developing roller 25a in a state in which a developing potential Vd of about 450 V is applied to the yellow developing roller 25a. Then, the developing solution transferred to the developing roller 25a is transferred to the yellow electrostatic latent image by the potential difference between the developing potential Vd and the exposure potential Ve to form a yellow image 20a as shown in FIG. 5C ( S13). The yellow image 20a is squeezed by a well-known method by the yellow squeeze roller 26a which is rotated in contact with the photosensitive belt 20 to remove about 60 to 70% of the carrier in the developer. During the squeegeeing process of the squeeze roller 26a, an overlapping voltage in which the AC voltage AC and the DC voltage DC are superposed is applied from the power supply 24 to the squeeze roller 26a. Then, the overlapping voltage is discharged through the shaft 28 and the rubber layer 29 to charge the photosensitive belt 20 in a direct contact method (S14). Therefore, the charging potential of the naturally reduced photosensitive belt 20 passing through the yellow developing unit 23a is compensated as in the initial state. In addition, since the overlapping voltage for charging the photosensitive belt 20 has both frequency characteristics of AC voltage and DC voltage, the portion where the yellow image 20a of the photosensitive belt 20 is formed and its The potential of the external non-image portion is uniformly charged as shown in FIG. 5D. In this way, by applying a voltage to the squeeze roller 26a to uniformly charge the photosensitive belt 20, it is possible to have a simple structure excluding the conventional topping corona 16 (see FIG. 1). On the other hand, since the charging characteristic by the direct contact of the overlapping voltage as described above is disclosed in Japanese Patent Laid-Open No. 63-149668, detailed description thereof will be omitted.

계속해서, 시안 화상을 형성하는 단계를 진행하게 된다(S20). 이를 위해, 스퀴즈롤러(26a)를 지난 후에 그 표면전위가 균일해진 감광벨트(20)에 시안 광주사유니트(22b)에서 광을 주사하면, 도 6a에 도시된 바와 같이, 감광벨트(20)의 대전전위(Vcc)가 부분적으로 노광전위(Ve)로 다운되어 시안 화상데이타에 대응되는 시안 정전잠상이 형성된다. 그리고, 시안 정전잠상에는 현상전위(Vd)가 인가되는 시안 현상롤러(25b)로 공급된 시안 현상액이 옮겨져 도 6b에 도시된 바와 같이 시안화상(20b)이 형성된다. 이 때, 종래와는 달이 옐로우 화상(20a)과 현상전위(Vd)와의 전위차가 미소하고, 감광벨트(20)의 비 정전잠상 영역이 계단형인 아닌 균일한 대전전위 특성을 갖기 때문에 옐로우 화상(20a)의 토너성분이 현상롤러(25b)로 재역전되는 워시 오프(Wash- Off) 현상은 발생하지 않게 된다. 한편, 형성된 시안 화상(20b)은 시안 스퀴지롤러(26b)를 거치면서 스퀴징되고, 감광벨트(20)는 스퀴지롤러(26b)에 의해 추가 대전된다. 이 과정에서 옐로우 현상유니트(23a)에서와 마찬가지로 스퀴지롤러(26b)를 통해 감광벨트(20)에 중첩전압이 인가됨으로써, 감광벨트(20)의 대전특성은 균일한 상태가 된다.Subsequently, a step of forming a cyan image is performed (S20). To this end, when the light is injected from the cyan photocopier unit 22b to the photosensitive belt 20 whose surface potential is uniform after passing through the squeeze roller 26a, as shown in FIG. 6A, the photosensitive belt 20 The charge potential Vcc is partially lowered to the exposure potential Ve to form a cyan electrostatic latent image corresponding to the cyan image data. The cyan developing solution supplied to the cyan developing roller 25b to which the developing potential Vd is applied is transferred to the cyan electrostatic latent image, thereby forming a cyan image 20b as shown in FIG. 6B. At this time, since the potential difference between the yellow image 20a and the development potential Vd is minute and the non-electrostatic latent image region of the photosensitive belt 20 has a uniform charge potential characteristic rather than a step shape, the yellow image ( The wash-off phenomenon in which the toner component of 20a) is reversed to the developing roller 25b does not occur. On the other hand, the formed cyan image 20b is squeezed while passing through the cyan squeegee roller 26b, and the photosensitive belt 20 is further charged by the squeegee roller 26b. In this process, as in the yellow developing unit 23a, an overlapping voltage is applied to the photosensitive belt 20 through the squeegee roller 26b, whereby the charging characteristic of the photosensitive belt 20 becomes uniform.

계속해서, 마젠타 현상유니트(23c)에서는 마젠타화상을 형성한다(S30). 이를 위해 먼저, 마젠타 광주사장치(22c)에서 감광벨트(20)에 광을 주사하면, 감광벨트(20)는 도 7a에 도시된 바와 같이 마젠타 화상데이터에 대응되는 부분이 대전전위(VcM)에서 노광전위(Ve)로 다운되어 마젠타 정전잠상이 형성된다. 이 경우에도, 마젠타 정전잠상을 제외한 각 화상(20a,20b)과 비화상부분의 전위가 균일한 상태이다. 따라서, 현상전위(Vd)가 인가되는 마젠타 현상롤러(25c)를 통해 공급되는 마젠타 현상액은 전위차에 의해 마젠타 정전잠상으로 옮겨져 마젠타화상(20c)을 형성한다. 이 때에도, 각 화상(20a)(20b)의 토너성분이 현상롤러(25c)로 다시 이동하는 워시 오프 현상은 발생하지 않게 된다. 이어서, 마젠타 스퀴지롤러(26c)에서 마젠타화상(20c)을 스퀴징하고, 감광벨트(20)를 중첩전압으로 추가 대전시킨다. 그러면, 감광벨트(20)의 전체표면 즉, 각 화상(20a,20b,20c)이 형성된 부분과 비화상부분 모두가 대략 균일한 레벨로 대전된다.Subsequently, the magenta developing unit 23c forms a magenta image (S30). To this end, first, when the magenta optical scanning device 22c scans the light to the photosensitive belt 20, the photosensitive belt 20 is a portion corresponding to the magenta image data as shown in Figure 7a at the charge potential (VcM) Down to the exposure potential Ve, a magenta electrostatic latent image is formed. Also in this case, the potentials of the respective images 20a and 20b and the non-image portions except for the magenta electrostatic latent image are in a uniform state. Therefore, the magenta developer supplied through the magenta developing roller 25c to which the developing potential Vd is applied is transferred to the magenta electrostatic latent image by the potential difference to form the magenta image 20c. Even at this time, the wash off phenomenon in which the toner component of each image 20a, 20b moves back to the developing roller 25c does not occur. Subsequently, the magenta image 20c is squeezed in the magenta squeegee roller 26c, and the photosensitive belt 20 is further charged with an overlapping voltage. Then, the entire surface of the photosensitive belt 20, that is, both the portion where the images 20a, 20b, and 20c are formed and the non-image portion are charged to a substantially uniform level.

마지막 현상단계로서 블랙 현상유니트(23d)에서는 블랙화상을 형성한다(S40). 이를 위해 블랙 광주사유니트(22d)에서 감광벨트(20)로 광을 주사한다. 그러면, 도 7b에 도시된 바와 같이, 주사된 광이 블랙 대전전위(VcB)를 부분적으로 노광전위(Ve)로 다운시킴으로써, 감광벨트(20)에 블랙 화상테이타에 대응되는 블랙 정전잠상을 형성시킨다. 이러한 상태에서 블랙 현상롤러(25d)에 현상전위(Vd)를 인가하면서 그 현상롤러(25d)에 블랙 현상액을 공급하면, 공급된 블랙 현상액이 현상전위(Vd)와 노광전위(Ve)와의 전위차에 의해 블랙 정전잠상으로 옮겨짐으로써 브랙 화상(20d)이 형성된다. 이와 같이 블랙 화상(20d)이 형성되는 과정에서도 각 화상(20a,20b,20c)은 균일한 대전특성을 가지고 있기 때문에 워시 오프 현상은 발생하지 않게 된다. 그리고, 이와 같이 형성된 블랙 화상(20d)은 블랙 스퀴지롤러(26d)를 통과하면서 최종 스퀴징되고, 감광벨트(20)는 최종 추가 대전된다. 그리고, 상술한 바와 같이 형성된 각 화상(20a,20b,20c,20d)을 하나의 기본 화상으로 하는 칼라화상은 이미 알려진 방법대로 건조단계(S50) 및 전사단계(S60)를 거쳐 인쇄용지로 인쇄되어 출력된다.As a final developing step, a black image is formed in the black developing unit 23d (S40). For this purpose, light is scanned from the black photonic yarn unit 22d to the photosensitive belt 20. Then, as shown in FIG. 7B, the scanned light partially lowers the black charging potential VcB to the exposure potential Ve, thereby forming a black electrostatic latent image corresponding to the black image data on the photosensitive belt 20. . If the black developer is supplied to the developing roller 25d while the developing potential Vd is applied to the black developing roller 25d in this state, the supplied black developer is applied to the potential difference between the developing potential Vd and the exposure potential Ve. The black image 20d is formed by being transferred to the black electrostatic latent image. Thus, even in the process of forming the black image 20d, since each image 20a, 20b, and 20c have uniform charging characteristics, the wash-off phenomenon does not occur. The black image 20d thus formed is squeezed while passing through the black squeegee roller 26d, and the photosensitive belt 20 is finally charged. In addition, the color image having each of the images 20a, 20b, 20c, and 20d formed as described above as one basic image is printed on printing paper through a drying step (S50) and a transfer step (S60) according to a known method. Is output.

이상에서 설명한 바와 같이, 스퀴지롤러(26a∼26d)의 직접접촉방식으로 감광벨트(20)를 추가 대전시킴으로써, 칼라별 현상단계에서의 감광벨트(20)는 균일한 대전특성을 나타내게 되었으며, 이로 인해 앞선 단계에서 형성된 화상의 토너들이 씻겨저내려가 화상이 누락되거나, 화상농도가 저하되는 문제점을 해결할 수 있게 된다. 또한, 종래와 같이 워시 오프 현상에 의해 화상으로부터 씻겨져 나간 토너성분이 다음 단계의 현상액을 오염시키는 문제까지도 자연스럽게 해결할 수 있게 된다.As described above, by further charging the photosensitive belt 20 in the direct contact method of the squeegee rollers 26a to 26d, the photosensitive belt 20 in the color-specific developing step exhibits uniform charging characteristics, thereby The toners of the image formed in the previous step may be washed off, and the problem of missing images or lowering of image density may be solved. In addition, it is possible to naturally solve even the problem that the toner component washed out from the image by the wash-off phenomenon contaminates the developer in the next step.

결론적으로, 상술한 바와 같은 본 발명에 따른 대전용 스퀴지롤러를 구비한 습식 전자사진방식 화상형성장치 및 인쇄방법에 따르면, 종래 기술의 토핑대전기를 사용하지 않고 스퀴즈롤러를 통해 감광벨트에 중첩전압을 직접접촉방식에 의해 인가함으로써 장치를 간소화할 수 있고, 감광벨트를 균일하게 대전시킬 수 있다.In conclusion, according to the wet electrophotographic image forming apparatus and printing method including the charging squeegee roller according to the present invention as described above, the superposition voltage is applied to the photosensitive belt through the squeeze roller without using the conventional topping charger. By applying the direct contact method, the apparatus can be simplified, and the photosensitive belt can be uniformly charged.

따라서, 종래의 계단식 대전특성에 따른 토너성분의 워시 오프 현상을 방지하여 화상의 누락 및 농도저하에 따른 화상의 품질저하를 예방하여 장치의 신뢰성을 향상시킬 수 있다.Therefore, by preventing the wash-off phenomenon of the toner component according to the conventional stepped charging characteristics, it is possible to prevent the deterioration of the image due to the missing image and the density decrease, thereby improving the reliability of the apparatus.

또한, 워시 오프에 의한 현상제의 오염을 방지함으로써 현상제를 재 보충하거나 교체하는 주기를 길게 가져갈 수 있으므로 장치의 유지 및 보수비용이 절감되는 장점이 있다.In addition, by preventing the contamination of the developer due to the wash off can take a long period of refilling or replacing the developer has the advantage of reducing the maintenance and repair costs of the device.

또한, 감광벨트를 직접접촉에 의해 대전시킴으로써, 저전력으로 고압을 인가할 수 있으므로 감광벨트의 고전압에 따른 수명단축을 억제시켜 그 교환주기를 늘릴 수 있다.In addition, since the photosensitive belt is charged by direct contact, high voltage can be applied at low power, so that the life cycle of the photosensitive belt due to the high voltage can be suppressed and the replacement cycle thereof can be increased.

Claims (5)

감광매체 표면을 소정 레벨의 대전전위로 대전시키는 메인대전기와; 상기 감광매체에 광을 주사하여 그 대전전위를 부분적으로 노광시킴으로써 정전잠상을 형성하는 광주사유니트; 및 상기 정전잠상 영역에 현상액을 현상시키기 위한 현상롤러와, 상기 현상된 현상액을 스퀴징하여 액상의 캐리어를 제거하기 위한 스퀴지롤러를 각각 구비한 Y, C, M, K 현상유니트;를 포함하는 습식 화상형성장치에 있어서,A main charging unit for charging the surface of the photosensitive medium to a charging potential of a predetermined level; A photowangju unit for scanning the photosensitive medium to form an electrostatic latent image by partially exposing the charge potential; And Y, C, M, K developing units each having a developing roller for developing a developer in the latent electrostatic image region and a squeegee roller for removing a liquid carrier by squeezing the developed developer. In the image forming apparatus, 상기 스퀴지롤러는,The squeegee roller, 금속재로 이루어지며 상기 전원에 연결되어 중첩전압을 인가받는 샤프트와;A shaft made of a metal material and connected to the power source to receive an overlapping voltage; 도전성 고무재질로 형성되어 상기 샤프트의 외주에 마련되며, 상기 감광매체에 접촉되는 고무층;을 포함하며,And a rubber layer formed of a conductive rubber material and provided on an outer circumference of the shaft and in contact with the photosensitive medium. 상기 스퀴지롤러에 직류전압 및 교류전압을 중첩 인가하는 전원;을 구비하여,And a power source for superimposing a DC voltage and an AC voltage on the squeegee roller. 상기 스퀴지롤러를 통과한 감광매체의 전위를 균일하게 추가 대전시킴으로써, 상기 현상된 현상액 중 토너가 다음에 통과하는 현상유니트의 현상롤러로 옮겨지는 것을 방지하도록 된 것을 특징으로 하는 습식 화상형성장치.And uniformly charging the potential of the photosensitive medium that has passed through the squeegee roller to prevent transfer of the toner from the developed developer to the developing roller of the developing unit passing therethrough. 삭제delete 제1항에 있어서,The method of claim 1, 상기 고무층은 10^7∼10^12Ω 사이의 저항값을 갖는 것을 특징으로 하는 습식 화상형성장치.The rubber layer has a resistance value between 10 ^ 7 and 10 ^ 12Ω. 메인대전기로부터 감광매체로 전압을 인가하여 그 감광매체의 표면을 소정 대전전위로 유지시키는 단계; 상기 감광매체에 광주사유니트로부터 광을 주사하여 상기 대전전위를 부분적으로 노광시켜 정전잠상을 형성시키는 단계; 상기 정전잠상 영역과 소정 현상전위가 인가되는 현상롤러 사이의 전위차를 이용하여 상기 정전잠상 영역에 현상액을 현상시키는 단계; 및 상기 현상된 현상액을 스퀴지롤러를 이용하여 스퀴징하는 단계;를 포함하는 인쇄방법에 있어서,Applying a voltage from the main charger to the photosensitive medium to maintain the surface of the photosensitive medium at a predetermined charge potential; Scanning the photosensitive medium with light from a photoreceptor unit to partially expose the charge potential to form an electrostatic latent image; Developing a developer in the latent electrostatic image area by using a potential difference between the latent electrostatic image area and a developing roller to which a predetermined developing potential is applied; And squeezing the developed developer using a squeegee roller. 상기 스퀴징단계와 동시에 상기 감광매체의 전위가 균일하게 대전되도록 그 감광매체에 교류전압과 직류전압을 중첩 인가하는 단계;를 포함하며,And superimposing an AC voltage and a DC voltage on the photosensitive medium at the same time as the squeezing step so that the potential of the photosensitive medium is uniformly charged. 상기 중첩인가단계는,The overlap application step, 소정 전원으로부터 상기 스퀴지롤러의 샤프트로 직류전압과 교류전압을 중첩인가하여, 그 샤프트에 인가된 중첩 전압이 그 샤프트의 외측에 마련된 도전성 고무층을 통해 상기 감광매체로 인가되도록 하는 것을 특징으로 하는 인쇄방법.A method of printing comprising: superimposing a direct current voltage and an alternating current voltage from a predetermined power source to a shaft of the squeegee roller such that an overlapping voltage applied to the shaft is applied to the photosensitive medium through a conductive rubber layer provided on an outer side of the shaft . 삭제delete
KR10-2000-0026706A 2000-05-18 2000-05-18 Liquid electrophotographic image forming apparatus having squeeze roller for charging and printing method used the same KR100370214B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8189024B2 (en) 2009-05-12 2012-05-29 Kabushiki Kaisha Toshiba Neutralization apparatus and printer having neutralization apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8189024B2 (en) 2009-05-12 2012-05-29 Kabushiki Kaisha Toshiba Neutralization apparatus and printer having neutralization apparatus
KR101196928B1 (en) 2009-05-12 2012-11-05 가부시끼가이샤 도시바 Neutralization apparatus and printer having neutralization apparatus

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