JP5358480B2 - Developing device and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of forming a toner image having desired image density by suppressing an increase of concentration of a solid component of liquid developer; and to provide an image forming apparatus including the developing device. <P>SOLUTION: The developing device 14 includes: a developer carrier 31 that carries the liquid developer obtained by dispersing the solid component into liquid, and supplies the liquid developer to an image carrier 10 to form the toner image on the image carrier 10; supply parts 32 and 33 that supply the liquid developer to the developer carrier 31; a regulation member 35 that regulates an amount of the liquid developer to be supplied from the supply parts 32 and 33 to the developer carrier 31; and collection parts 40 and 45 that collect the liquid developer, regulated by the regulation member 35 and not supplied to the developer carrier 31, so as not to come into contact with the developer carrier 31 again. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a developing device that forms a toner image using a liquid developing device, and a wet image forming apparatus including the developing device.

  As an image forming apparatus, a wet type apparatus that forms a toner image using a liquid developer is known. The wet image forming apparatus supplies an image carrier on which a toner image is formed and a liquid developer to the image carrier and forms a toner image on the image carrier, and supplies the liquid developer to the developer. It includes a liquid developer supply device, a transfer unit that transfers a toner image on an image carrier onto a sheet, a fixing unit that fixes the toner image on the sheet onto the sheet, and the like.

  For example, as disclosed in Patent Document 1, the developing device supplies a liquid developer to the photosensitive drum and forms a toner image on the photosensitive drum, and a storage unit that stores the liquid developer. And a supply roller that pumps the liquid developer from the storage unit and supplies the liquid developer to the developing roller, and a regulating member that regulates the amount of the liquid developer supplied from the supply roller to the developing roller.

  In the developing device of Patent Document 1, the liquid developer that is regulated by the regulating member and not supplied from the supply roller to the developing roller is returned to the storage unit. The liquid developer returned to the storage unit is again drawn up by the supply roller and supplied to the developing roller.

JP 2009-122630 A

  The liquid developer is obtained by dispersing a solid content as a toner in a dielectric liquid as a carrier, and the mixing ratio of the toner and the carrier is adjusted to a predetermined solid content concentration. However, it is known that the solid content concentration of the liquid developer regulated by the regulating member and not supplied to the developing roller is higher than the predetermined solid content concentration. For this reason, as the development operation proceeds, if the regulation of the liquid developer by the regulating member and the supply to the developing roller are repeated, the solid content concentration of the liquid developer in the storage container becomes higher than the predetermined solid content concentration. End up. When a liquid developer having a solid content concentration higher than the predetermined solid content concentration is supplied to the developing roller to form a toner image, the image density of the toner image becomes higher than a desired image density. In the above-mentioned Patent Document 1, such inconvenience occurs.

  Accordingly, in view of the above circumstances, the present invention provides a developing device capable of forming a toner image having a desired image density by suppressing an increase in the solid content concentration of the liquid developer, and an image forming apparatus including the developing device. The purpose is to provide.

In order to achieve the above object, a developing apparatus according to the present invention supplies a liquid developer to a predetermined image carrier while carrying a liquid developer in which a solid content is dispersed in a liquid. A developer carrier that forms a toner image on the carrier, a supply roller that supplies the liquid developer to the developer carrier, and a supply roller and a liquid developer that are disposed below the supply roller A nip forming roller for forming a supply nip portion for receiving the liquid, a regulating member for regulating an amount of the liquid developer supplied from the supply roller to the developer carrier, the developer carrier, the supply roller, A housing for housing the nip forming roller and the regulating member, and a time for collecting the liquid developer regulated by the regulating member and not supplied to the developer carrying body so as not to contact the developer carrying body again. Comprising a part, the said housing is provided with upper groove portion for rotatably accommodating the nip forming roller and a lower groove portion continuous to the lower side of the upper groove portion extends the upper groove portion and the same direction, the The recovery part is disposed in the lower groove part and disposed in the lower groove part, the wall of the housing defining the upper groove part and the lower groove part, a discharge port communicating with the lower groove part, and the liquid development in the lower groove part a conveying screw for conveying the material to the discharge port includes a first gear attached to one end of the conveying screw, the said scraped liquid developer by the regulating member, the upper groove portion according to the natural fall and then received by the lower groove portion, the conveying screw, below the nip forming rollers, arranged in parallel with said nip forming roller, wherein the nip forming rollers, the conveyance screw An end portion corresponding to the end portion has a second gear that directly meshes with the first gear, and when the rotational driving force is applied to the second gear, the nip forming roller rotates, and accordingly the conveyance is performed. The screw also rotates.

  According to the developing device of the present invention, the liquid developer that is regulated by the regulating member and not supplied to the developer carrier is collected by the collection unit so as not to contact the developer carrier again. The liquid developer having a concentration higher than a predetermined solid content concentration is prevented from being supplied to the developer carrying member. Thereby, it is possible to form a toner image having a desired image density.

  In a preferred embodiment of the present invention, the collection unit includes a conveyance unit that conveys the collected liquid developer in a predetermined direction.

  According to this configuration, since the liquid developer has a predetermined viscosity, the liquid developer tends to stay, but since the recovery unit has the conveying means, the recovered liquid developer is positively transferred to the predetermined level. Can be conveyed in the direction.

  The developing device further includes a housing that houses the developer carrier, the supply unit, the regulating member, and the recovery unit. In another preferred embodiment of the present invention, the recovery portion further includes a groove portion that is defined by the wall portion of the housing and receives the recovered liquid developer, and a discharge port that communicates with the groove portion. The conveying means is a conveying screw that is arranged in the groove and conveys the liquid developer in the groove to the discharge port.

  According to this configuration, the liquid developer having a predetermined viscosity can be reliably conveyed to the discharge port by the rotation of the conveyance screw.

  In still another preferred embodiment of the present invention, the groove portion is inclined so that the recovered liquid developer is guided to the discharge port, and the transport means is the liquid guided to the discharge port. This is a pump capable of sucking the developer to the outside.

  Since the liquid developer has a predetermined viscosity, it tends to stay in the groove only with the suction force of the pump, but since the groove is inclined toward the discharge port, the liquid developer is conveyed to the discharge port. can do.

  An image forming apparatus according to the present invention includes the developing device configured as described above, and further, after processing the liquid developer recovered in the recovery container so that the liquid developer can be supplied again to the developing device, A liquid developer circulating device configured to be capable of being supplied to the supply unit;

  According to the image forming apparatus of the present invention, the discharged liquid developer can be regenerated by the liquid developer circulating device, and the regenerated liquid developer can be supplied again to the developing device. In addition, the printing cost can be reduced.

  According to the developing device and the image forming apparatus including the same according to the present invention, it is possible to form a toner image having a desired image density while suppressing an increase in the solid content density of the liquid developer.

1 is a schematic configuration diagram of a wet image forming apparatus. 1 is a schematic cross-sectional view of a wet image forming apparatus excluding a liquid developer circulating device. It is the perspective view which looked at the developing device from the one side, and shows the whole structure of the developing device in the longitudinal direction. It is the perspective view which looked at the developing device from the other side, and shows the whole structure of the developing device in the longitudinal direction. It is sectional drawing cut | disconnected along XX of FIG. It is sectional drawing cut | disconnected along the YY line | wire of FIG. FIG. 2 is a schematic configuration diagram showing a circulation system of a liquid developer. It is sectional drawing of the developing device which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a wet image forming apparatus, and FIG. 2 is a schematic cross-sectional view of the wet image forming apparatus excluding a liquid developer circulating device. The image forming apparatus 1 shown in FIGS. 1 and 2 is a color printer. However, the image forming apparatus 1 is a copier, a facsimile machine, a multifunction machine including these functions, or another apparatus capable of forming an image on paper. You can also.

  As shown in FIG. 1, a color printer 1 is disposed in an upper main body 1A that stores various units and parts for image formation, and a lower portion of the upper main body 1A, and a liquid developer circulation for each color. It is comprised from the lower main-body part 1B in which apparatus LY, LM, LC, LB is accommodated. Here, the piping connecting the upper main body 1A and the lower main body 1B is not shown.

  As shown in FIG. 2, the upper main body 1 </ b> A is formed by a tandem-type image forming unit 2 that forms a toner image based on image data, a paper storage unit 3 that stores paper, and an image forming unit 2. A secondary transfer unit 4 for transferring the transferred toner image onto the paper, a fixing unit 5 for fixing the transferred toner image on the paper, a discharge unit 6 for discharging the fixed paper, and a paper storage unit A paper transport unit 7 for transporting paper from 3 to the discharge unit 6 is arranged.

  The image forming unit 2 includes an intermediate transfer belt 21, a cleaning unit 22 for the intermediate transfer belt 21, and an image forming unit corresponding to each of yellow (Y), magenta (M), cyan (C), and black (Bk). Includes FY, FM, FC, and FB.

  The intermediate transfer belt 21 is a belt-like member that has conductivity and is wider than the paper having the maximum length in the direction orthogonal to the paper conveyance direction, that is, an endless belt shape. Is circulated and driven clockwise. In the circulation driving of the intermediate transfer belt 21, the surface facing outward is hereinafter referred to as a front surface, and the other surface is referred to as a back surface.

  Four image forming units FY, FM, FC, and FB are arranged near the intermediate transfer belt 21 and disposed between the cleaning unit 22 and the secondary transfer unit 4 of the intermediate transfer belt 21. Note that the order of arrangement of the image forming units FY, FM, FC, and FB is not limited to this, but this arrangement is preferable in consideration of the influence of the color mixture on the completed image.

  Each of the image forming units FY, FM, FC, and FB includes a photosensitive drum 10 (image carrier), a charger 11, an LED exposure device 12, a developing device 14, a primary transfer roller 20, and a cleaning device 26. And a static elimination device 13 and a carrier liquid removal roller 30. Further, among the image forming units FY, FM, FC, and FB, the image forming unit FB located closest to the secondary transfer unit 4 is not provided with the carrier liquid removal roller 30, but the other configurations are as follows. Are the same.

  Corresponding to the image forming units FY, FM, FC, FB, liquid developer circulating devices LY, LM, LC, LB are provided, respectively, so that supply and recovery of the liquid developers of the respective colors are performed. Yes. The liquid developer circulating devices LY, LM, LC, and LB will be described in detail later.

  The photosensitive drum 10 is a cylindrical member, and can carry a toner image including charged toner on the surface thereof. The photosensitive drum 10 is a member that can rotate counterclockwise in FIGS. 1 and 2. The charger 11 is a device that can uniformly charge the surface of the photosensitive drum 10. The exposure device 12 has a light source such as an LED and irradiates light onto the surface of the uniformly charged photoreceptor drum 10 in accordance with image data input from an external device. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 10.

  The developing device 14 has a liquid developer in which a toner (dispersoid) as a solid content is dispersed in a carrier (dispersion medium) of a dielectric liquid so as to face the electrostatic latent image on the surface of the photosensitive drum 10. Holding the toner causes the toner to adhere to the electrostatic latent image. Thereby, the electrostatic latent image is developed as a toner image. The liquid developer has a viscosity of, for example, about 50 to 200 mPa · s. The developing device 14 will be described in detail later.

  The primary transfer roller 20 is disposed on the back surface of the intermediate transfer belt 21 so as to face the photosensitive drum 10. A voltage having a polarity opposite to that of the toner in the toner image is applied to the primary transfer roller 20 from a power source (not shown). That is, the primary transfer roller 20 applies a voltage having a polarity opposite to that of the toner to the intermediate transfer belt 21 at a position in contact with the intermediate transfer belt 21. Since the intermediate transfer belt 21 has conductivity, the applied voltage attracts toner to the surface side of the intermediate transfer belt 21 and its periphery. The intermediate transfer belt 21 functions as an image carrier that carries a toner image and conveys it to a sheet.

  The cleaning device 26 is a device for cleaning the liquid developer remaining without being transferred from the photosensitive drum 10 to the intermediate transfer belt 21, and cleaning for scraping off the residual liquid developer on the surface of the photosensitive drum 10. A blade 262 (FIG. 6) and a liquid developer carrying screw 261 (FIG. 6) for carrying the residual liquid developer scraped by the cleaning blade 262 to the outside of the cleaning device 26 are provided.

  The cleaning blade 262 is a plate-like member extending in the rotation axis direction of the photosensitive drum 10. The end of the cleaning blade 262 is in sliding contact with the surface of the photosensitive drum 10, and scrapes off the liquid developer remaining on the photosensitive drum 10 as the photosensitive drum 10 rotates.

  The static eliminator 13 has a light source for static elimination, and removes the liquid developer by the cleaning blade 262 and removes the surface of the photosensitive drum 10 with light from the light source in preparation for the next round of image formation.

  The carrier liquid removal roller 30 is a substantially cylindrical member that can rotate in the same direction as the photosensitive drum 10 around a rotational axis parallel to the rotational axis of the photosensitive drum 10. The carrier liquid removing roller 30 is disposed on the side where the secondary transfer unit 4 is disposed with respect to the position where the photosensitive drum 10 and the intermediate transfer belt 21 are in contact with each other, and the carrier liquid is removed from the surface of the intermediate transfer belt 21. The member to be removed.

  The paper storage unit 3 is a part for storing a paper for fixing a toner image, and is disposed below the upper main body 1A. The paper storage unit 3 has a paper feed cassette that stores paper.

  The secondary transfer unit 4 is a part that transfers the toner image formed on the intermediate transfer belt 21 to a sheet, and is disposed opposite to the support roller 41 that supports the intermediate transfer belt 21 and the support roller 41. And a secondary transfer roller 42.

  The fixing unit 5 is a part for fixing the toner image on the sheet, and is disposed on the upper side of the secondary transfer unit 4. The fixing unit 5 includes a heating roller 43 and a pressure roller 44 disposed to face the heating roller 43.

  The discharge unit 6 is a portion from which the paper on which the toner image has been fixed by the fixing unit 5 is discharged, and is disposed at the top of the color printer 1. The paper transport unit 7 includes a plurality of transport roller pairs, and transports the paper from the paper storage unit 3 to the secondary transfer unit 4, the fixing unit 5, and the discharge unit 6.

(First embodiment)
Next, the developing device 14 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a perspective view of the developing device as seen from one side surface, and shows the overall structure of the developing device in the longitudinal direction. FIG. 4 is a perspective view of the developing device as viewed from the other side surface, and shows the overall structure of the developing device in the longitudinal direction. FIG. 5 is a cross-sectional view taken along line XX of FIG. The developing device 14 includes a developing container 50 (housing) that accommodates components to be described later. The developing container 50 is a member having a shape extending along the longitudinal direction of the developing device 14, that is, the rotational axis direction of the photosensitive drum 10. , 53.

  The main body frame 51 is a container-like member extending in the longitudinal direction of the developing device 14 and opens upward as shown in FIG. The main body frame 51 defines two-stage groove portions 51 a and 51 b extending in the longitudinal direction of the developing device 14 by the wall portion. A nip forming roller 33 described later is rotatably disposed in the upper groove 51a. A first conveying screw 45 is rotatably disposed in the lower groove 51b. The upper groove portion 51a and the lower groove portion 51b communicate with each other.

  The intermediate frame 55 is a container-like member extending in the longitudinal direction of the developing device 14. The intermediate frame 55 opens upward, and is attached to the main body frame 51 from above so as to cover a part of the opening of the main body frame 51. Yes. A groove 55 a extending in the longitudinal direction of the developing device 14 is formed at the bottom of the intermediate frame 55. The second conveying screw 47 is rotatably disposed in the groove portion 55a.

  The upper frame 54 is a member extending in the longitudinal direction of the developing device 14, and is attached to the intermediate frame 55 from above so as to cover the opening of the intermediate frame 55. The main body frame 51, the intermediate frame 55, and the upper frame 54 have substantially the same longitudinal dimension.

  The pair of side frames 52 and 53 cover both side surfaces of the main body frame 51 and both side surfaces of the intermediate frame 55 at both longitudinal ends of the developing container 50. From one side frame 52, a first recovery path 40 described later protrudes in the longitudinal direction of the developing device 14.

  As shown in FIG. 4, a liquid developer supply device 38 for supplying the liquid developer to the developing device 14 is attached to the outer surface of the main body frame 51. The liquid developer supply device 38 has a plurality of supply pipes 39 (five in FIG. 4) extending into the developing device 14. The liquid developer supply device 38 is connected to the liquid developer reserve tank 277 (FIG. 6) by a supply tube 872 and receives supply of the liquid developer from the liquid developer reserve tank 277.

  As shown in FIG. 5, the developing device 14 includes a developing roller 31, a supply roller 32, a nip forming roller 33, a regulating blade 35, a developing roller charger 34, a cleaning roller 37, and a cleaning blade 36 in the developing container 50. .

  The nip forming roller 33 is a roller that is rotatably disposed in the upper groove 51a of the main body frame 51 as described above. The supply roller 32 is a roller extending along the rotational axis direction of the nip forming roller 33 at a position obliquely above the nip forming roller 33. The nip forming roller 33 is disposed in contact with the supply roller 32. Thereby, a supply nip portion NP is formed between the nip forming roller 33 and the supply roller 32. In the present embodiment, the nip forming roller 33, the supply roller 32, and the liquid developer supply device 38 constitute a supply unit. The plurality of supply pipes 39 of the liquid developer supply device 38 described above are arranged side by side in the rotational axis direction of the nip forming roller 33, and the discharge ports 39a thereof face the supply nip portion NP. Therefore, the liquid developer is discharged to the supply nip NP by the liquid developer supply device 38. In FIG. 5, the nip forming roller 33 is rotated counterclockwise, and the supply roller 32 is rotated clockwise.

  The liquid developer discharged from the discharge port 39a to the supply nip NP temporarily stays in the supply nip NP, and then passes through the supply nip NP as the nip forming roller 33 and the supply roller 32 rotate. , And conveyed upward while being held on the peripheral surface of the supply roller 32. A groove for holding the liquid developer is formed on the peripheral surface of the supply roller 32.

  The regulation blade 35 (regulation member) is made of a material such as urethane rubber, for example, and the tip thereof is in pressure contact with the peripheral surface of the supply roller 32. Depending on the pressure contact state, the regulating blade 35 regulates the amount of the liquid developer on the peripheral surface of the supply roller 32 to be a predetermined amount. The excess liquid developer scraped off by the regulating blade 35 is received by the upper groove 51a and then the lower groove 51b according to the natural fall. As will be described later, the lower groove portion 51b constitutes a part of the first recovery path 40, and the liquid developer that is regulated by the regulating blade 35 and not supplied to the later-described developing roller 31 is first transported. The screw 45 is conveyed to the liquid developer recovery container 70 (FIG. 6) by rotation.

  The developing roller 31 (developer carrier) is disposed in contact with the supply roller 32 at an opening formed between the main body frame 51, the intermediate frame 55, and the upper frame 54. The developing roller 31 extends parallel to the nip forming roller 33 and the supply roller 32, and is rotated clockwise in FIG. Accordingly, at the nip portion where the developing roller 31 and the supply roller 32 are in contact, the peripheral surface of the developing roller 31 moves in the opposite direction to the peripheral surface of the supply roller 32. As a result, the liquid developer held on the peripheral surface of the supply roller 32 is delivered to the peripheral surface of the developing roller 31. Since the layer thickness of the liquid developer on the supply roller 32 is regulated to a predetermined value, the layer thickness of the liquid developer layer formed on the peripheral surface of the developing roller 31 is also maintained at the predetermined value.

  The developing roller charger 34 moves the toner in the liquid developer layer carried on the developing roller 31 to the peripheral surface side of the developing roller 31 by applying a charging potential having the same polarity as the charging polarity of the toner, thereby developing efficiency. The effect | action which improves is improved. The developing roller charger 34 is located downstream of the nip portion between the developing roller 31 and the supply roller 32 as viewed from the rotation direction of the developing roller 31 and from the nip portion between the developing roller 31 and the photosensitive drum 10. Is also provided on the upstream side so as to face the peripheral surface of the developing roller 31.

  The developing roller 31 is in contact with the photosensitive drum 10 and forms a nip portion with the photosensitive drum 10. Due to the potential difference between the potential of the electrostatic latent image on the peripheral surface of the photosensitive drum 10 and the developing bias applied to the developing roller 31, the toner moves on the peripheral surface of the photosensitive drum 10 and the electrostatic latent image is developed. Is done. As a result, a toner image is formed on the peripheral surface of the photosensitive drum 10.

  The cleaning roller 37 is disposed on the downstream side of the photosensitive drum 10 when viewed from the rotation direction of the developing roller 31, and the peripheral surface thereof is in contact with the peripheral surface of the developing roller 31. Thereby, the liquid developer remaining on the peripheral surface of the developing roller 31 is scraped off. The liquid developer thus scraped off is received by a groove 55 a formed in the intermediate frame 55.

  The cleaning blade 36 is disposed on the downstream side of the cleaning roller 37 when viewed from the rotation direction of the developing roller 31, and the tip thereof is in contact with the peripheral surface of the developing roller 31. As a result, the liquid developer remaining on the peripheral surface of the developing roller 31 that has not been scraped off by the cleaning roller 37 is further scraped off. The liquid developer thus scraped down flows down along the surface of the cleaning blade 36 and is received by a groove 55 a formed in the intermediate frame 55. As will be described later, the groove portion 55a constitutes a part of the second recovery passage 46, and the liquid developer passes through the combined passage 48 (FIG. 6) by the rotation of the second conveying screw 47, and the liquid developer recovery container. It is conveyed to 70.

  Next, the details of the first recovery path and the second recovery path will be described with reference to FIG. 6 is a cross-sectional view taken along line YY of FIG. As described above, the first collection path 40 is a path that receives the liquid developer that is regulated by the regulation blade 35 and not supplied from the supply roller 35 to the developing roller 31. On the other hand, the second recovery path 46 is a path that receives the liquid developer that is not supplied from the developing roller 31 to the photosensitive drum 10 but is scraped off from the peripheral surface of the developing roller 31 by the cleaning roller 37 and the cleaning blade 36. .

  The first recovery path 40 includes a lower groove 51b and a first extending pipe 56. As described above, the lower groove portion 51 b is defined by the wall portion of the main body frame 51 and extends in the longitudinal direction of the developing device 14. The first extending pipe 56 is fitted into the main body frame 51 so as to communicate with the lower groove portion 51 b and protrudes in the longitudinal direction of the developing device 14 through the side frame 52. In addition, the 1st extension pipe | tube 56 can be abbreviate | omitted by setting it as the structure which extended the lower side groove part 51a further.

  The first conveying screw 45 is rotatably disposed in the lower groove portion 51b and the first extending tube 56, and conveys the liquid developer from the lower groove portion 51b to the first extending tube 56. It is configured. The first conveying screw 45 has a shaft portion 45a and a blade portion 45b. The blade portion 45 b is located with a slight gap with respect to the peripheral surface 51 bb of the lower groove portion 51 b and the inner peripheral surface 56 a of the first extending pipe 56. A driven gear 58a is attached to one end of the first conveying screw 45 (the right end in FIG. 6). A gear 58b that meshes with the driven gear 58a is attached to one end (right end in FIG. 6) of the nip forming roller 33, and the gear shaft 58c of the gear 58b is connected to a drive source (not shown). Therefore, when the gear 58b is rotated by a drive source (not shown), the nip forming roller 33 is rotated, and accordingly, the first conveying screw 45 is also rotated.

  The first recovery path 40 having the above configuration communicates with the liquid developer recovery container 70 via the first extending pipe 56. A case tube 59 is externally fitted to the first extending tube 56. The case tube 59 is a cylindrical member and has a discharge port 69 at one end. When the case tube 59 is externally fitted to the first extending tube 56, the case tube 59 communicates with the first extending tube 56 and constitutes a part of the first recovery path 40. In a state where the case tube 59 is attached to the first extending tube 56, the other end of the first conveying screw 45 extends into the case tube 59. The case tube 59 can be omitted by adopting a structure in which the first extending tube 56 is further extended.

  A closing member 60 is disposed in the case tube 59. The closing member 60 includes a closing portion 61 having a shape capable of closing the discharge port 69 of the case tube 59 and a support portion 62 that supports the closing portion 61. The closing portion 61 is configured to close the discharge port 69 when the developing device 14 is not attached to the upper main body portion 1A. On the other hand, when the developing device 14 is attached to the upper main body portion 1A, the closing portion 61 is discharged. It is configured to retreat from the outlet 69. When the blocking portion 61 is retracted from the discharge port 69, the first recovery path 40 and the liquid developer recovery container 70 are communicated with each other. A groove portion (not shown) is formed in the support portion 62, and the liquid developer in the first collection path 40 is passed through the groove portion and then the discharge port 69 by the rotation of the first conveying screw 45, and the liquid developer. It is conveyed to the collection container 70. In the first embodiment, the first recovery path 40 and the first conveying screw 45 constitute a recovery unit.

  On the other hand, the second recovery path 46 includes a groove portion 55a and a second extending pipe 65. As described above, the groove 55 a is formed in the intermediate frame 55 and extends in the longitudinal direction of the developing device 14. On the other hand, the second extending pipe 65 is fitted into the intermediate frame 55 so as to communicate with the groove portion 55a, and protrudes in the longitudinal direction of the developing device 14 through the side frame 52.

  The second conveying screw 47 is rotatably disposed in the groove portion 55a and the second extending tube 65, and is configured to convey the liquid developer from the groove portion 55a to the second extending tube 65. The second conveying screw 47 has a shaft portion 47a and a blade portion 47b. The blade portion 47b is located with a slight gap with respect to the peripheral surface 55aa of the groove portion 55a and the inner peripheral surface 65a of the second extending pipe 65. A coupling 63 is fixed to one end of the second conveying screw 47, and the coupling 63 is connected to a drive source (not shown). The other end of the second conveying screw 47 is supported by a bearing 64.

  The second extending pipe 65 is integrally formed with a lower pipe section 66 extending downward, and the lower pipe section 66 is connected to the first extending pipe 56 of the first recovery path 40. The inner peripheral surface 66 a of the lower pipe portion 66 defines a combined flow path 48, and the combined flow path 48 allows the first extended pipe 56 and the second extended pipe 65, that is, the first recovery path 40 and the second recovery path 46. And communicate with each other. The liquid developer transported in the second recovery path 46 by the second transport screw 47 passes through the combined flow path 48 by natural fall and moves into the first extending pipe 56 of the first recovery path 40. The second conveying screw 47 has a blade portion 47 c in the vicinity of the combined channel 48. The blade portion 47b is configured to convey the liquid developer to the left in FIG. 6, whereas the blade portion 47c is configured to convey the liquid developer to the right.

  In the developing device 14 of the first embodiment described above, the liquid developer that has been regulated by the regulating blade 35 and not supplied to the developing roller 31 falls from the peripheral surface of the supply roller 32 and falls to the upper groove 51a and then to the bottom. It is received in the side groove 51b. Then, the liquid developer in the lower groove 51b is conveyed by the first conveying screw 45 in the order of the lower groove 51b and the first extending pipe 56, and is discharged from the discharge port 69 to the liquid developer recovery container 70. .

  As described above, the liquid developer that is regulated by the regulation blade 35 and not supplied to the developing roller 31 is collected in the liquid developer collecting container 70 without coming into contact with the developing roller 31 again. This prevents the liquid developer having a solid content concentration higher than a predetermined solid content concentration from being supplied to the developing roller 31. As a result, a toner image having a desired image density can be formed.

  Further, since the liquid developer has a predetermined viscosity, it tends to stay in the lower groove 51b and the first extending pipe 56, but the liquid developer is actively developed by the first conveying screw 45. It can be conveyed to the agent storage container 70.

  The liquid developer RD recovered in the liquid developer recovery container 70 is reused by the liquid developer circulation device. The liquid developer circulating device can adjust the solid content concentration of the discharged liquid developer RD to a predetermined solid content concentration and then supply the adjusted liquid developer to the supply unit of the developing device 14 again. It is configured. FIG. 7 is a schematic configuration diagram of one liquid developer circulation device LC, schematically showing a liquid developer circulation system. The other liquid developer circulating devices LY, LM, and LB have the same configuration.

  The liquid developer circulation device LC includes a liquid developer recovery container 70, a developer adjustment container 272, a carrier tank 274, a toner tank 275, a developer reserve tank 277, a liquid developer separation device 28, and a plurality of pumps P1 to P10. .

  The liquid developer recovery container 70 is connected to the developer adjustment container 272 via the first pipe 83. The first pipe 83 is provided with a first pump P1, and the liquid developer RD recovered in the liquid developer recovery container 70 is sent to the developer adjustment container 272 by driving the first pump P1.

  The developer adjusting container 272 adds a developer having a toner concentration higher than that of the developer used in the developing device 14 or a carrier liquid to the collected liquid developer, thereby setting the solid content concentration (toner concentration) to a predetermined level. It adjusts to the solid content concentration range.

  The solid content concentration detection device 273 is a device for detecting the solid content (toner) concentration of the liquid developer in the developer adjustment container 272. A solid concentration detector 273 is connected to an annular second pipe 84 connected to the developer adjustment container 272. A third pump P3 is attached to the second pipe 84. The liquid developer in the developer adjustment container 272 is guided from the inlet end of the second pipe 84 to the solid concentration detector 273 by driving the third pump P3, and then the developer adjustment from the outlet end of the second pipe 84. Returned to container 272.

  The carrier tank 274 is a tank that stores a carrier liquid. When the solid concentration detector 273 determines that the toner concentration in the developer adjustment container 272 is higher than the appropriate range, the carrier liquid is supplied from the carrier tank 274 into the developer adjustment container 272, and the developer. The solid content concentration of the liquid developer in the adjustment container 272 is lowered. The carrier tank 274 and the developer adjustment container 272 are connected by a third pipe 85, and the second pump P2 is disposed in the third pipe 85. The carrier liquid is supplied from the carrier tank 274 to the developer adjusting container 272 by driving the second pump P2.

  The toner tank 275 is a tank that stores a liquid developer having a solid content concentration higher than that of the developer used in the developing device 14. When the solid content concentration detection device 273 determines that the solid content concentration in the developer adjustment container 272 is lower than the appropriate range, liquid development with a high solid content concentration from the toner tank 275 to the developer adjustment container 272 is performed. The agent is supplied, and the solid content concentration of the liquid developer in the container 272 is increased. The toner tank 275 and the developer adjustment container 272 are connected by a fourth pipe 86, and a fifth pump P5 is disposed in the fourth pipe 86. The liquid developer is supplied from the toner tank 275 to the developer adjusting container 272 by driving the fifth pump P5.

  In the developer adjusting container 272, a stirring device 276 for stirring the liquid developer is disposed. The purpose of stirring by the stirring device 276 is to allow the toner or carrier liquid introduced into the developer adjusting container 272 for density adjustment to be uniformly mixed with the existing liquid developer in the developer adjusting container 272. Also, the toner that may aggregate in the liquid developer contained in the developer adjustment container 272 is redispersed. The stirring device 276 includes a rotating shaft and a stirring blade attached to the tip of the rotating shaft.

  The developer reserve tank 277 is a tank that stores a liquid developer to be replenished to the developing device 14. The developer reserve tank 277 is connected to the developer adjustment container 272 by a fifth pipe 871, and a fourth pump P4 is disposed in the fifth pipe 871. The liquid developer is supplied from the developer adjusting container 272 to the developer reserve tank 277 by driving the fourth pump P4.

  Further, the developer reserve tank 277 is connected to the carrier tank 274 by a first direct connection pipe 910 and by a toner tank 275 and a second direct connection pipe 920, respectively. A seventh pump P7 and a sixth pump P6 are disposed in the first and second direct connection pipes 910 and 920, respectively, and the carrier and the toner can be directly supplied from each tank 274 and 275 to the developer reserve tank 277. ing. The carrier and toner supply system from the first and second direct connection pipes 910 and 920 is a liquid developer quickly according to a known blending ratio at the start of use of the color printer 1 where the recovered liquid developer has not yet been generated. It is utilized when generating.

  Further, the developer reserve tank 277 is connected to the liquid developer supply device 38 (FIG. 5) by a supply tube 872. An eighth pump P8 is disposed in the supply tube 872, and the liquid developer is supplied from the developer reserve tank 277 to the liquid developer supply device 38 by driving the eighth pump P8. Then, the liquid developer is discharged from the discharge port 39a of the branch supply pipe 39 to the supply nip portion NP.

  Although not shown, liquid levels for detecting the liquid level in these tanks are provided at appropriate positions of the liquid developer recovery container 70, the carrier tank 274, the toner tank 275, and the developer reserve tank 277. A detection device is provided.

  The liquid developer separating device 28 is a device that separates the residual liquid developer collected from the photosensitive drum 10 by the cleaning device 26 into toner and carrier liquid, and separately extracts the toner and carrier liquid. . The cleaning device 26 and the liquid developer separating device 28 are connected by a sixth pipe 881 to which a ninth pump P9 is attached. By driving the ninth pump P9, the liquid developer in the cleaning device 26 is sent to the liquid developer separating device 28.

  Furthermore, a seventh pipe 882 to which a tenth pump P10 is attached is provided between the liquid developer separating device 28 and the carrier tank 274. The carrier liquid extracted by the liquid developer separating device 28 is sent to the carrier tank 274 by driving the tenth pump P10. The separated toner is discharged to the outside.

  The carrier tank 274 is connected to a developer adjusting container for each color of black, magenta and yellow, and is connected to a developer reserve tank for each color of black, magenta and yellow. Further, the photosensitive drum 10 for each color of black, magenta and yellow is connected to the liquid developer separating device 28 via a cleaning device.

  As is clear from the above description, the image forming apparatus provided with the liquid developer circulation devices LY, LM, LC, LB is configured to transfer the discharged liquid developer RD to the liquid developer circulation devices LY, LM, LC, LB. Since the regenerated liquid developer can be supplied again to the developing device 14, it is possible to reduce the waste developer and the printing cost.

(Second Embodiment)
Next, the developing device 14 according to the second embodiment will be described with reference to FIG. In the second embodiment, the collection unit is composed of an inclined lower groove 51b and a pump 75 as a conveying means. This will be specifically described below.

  At the bottom of the main body frame 51, a discharge port 72 is formed at a substantially intermediate position in the longitudinal direction. That is, the discharge port 72 is formed at a substantially intermediate position in the longitudinal direction of the lower groove portion 51b. The lower groove 51b has an inclined surface 51bb that is gradually inclined obliquely downward from each of both ends in the longitudinal direction toward the discharge port 72.

  In FIG. 8 of the lower groove 51b, a third extending pipe 71 is fitted into the right end. Thereby, the lower groove part 51b and the 3rd extension pipe | tube 71 are connected. The peripheral surface 71a of the third extending pipe 71 and the peripheral surface 51bb of the lower groove portion 51b are set to be smoothly continuous so that the liquid developer does not stay between them. Note that the third extending pipe 71 may be omitted by further extending the lower groove 51b.

  A lower pipe 66 of the second extension pipe 65 is connected to the third extension pipe 71 from above via a receiving part 67. Therefore, the combined flow path 48, and hence the second recovery path 46, communicates with the lower groove portion 51 b via the third extending pipe 71.

  The discharge port 72 is in communication with a discharge path 74 defined by a tube or a tube, and the discharge path 74 is in communication with the liquid developer recovery container 70. A pump 75 is disposed in the discharge path 74. In the second embodiment, the lower groove 51b and the pump 75 constitute a recovery unit.

  In the developing device 14 of the second embodiment, the liquid developer that is regulated by the regulating blade 35 and is not supplied to the developing roller 31 falls from the peripheral surface of the supply roller 32 and falls into the upper groove 51a and then the lower groove. 51b is accepted. The liquid developer in the lower groove 51b moves toward the discharge port 72 according to the inclination of the inclined surface 51bb. In addition, the liquid developer from the second recovery path 46 flows into the third extending pipe 71 through the joint path 48, and enters the lower groove 51b according to the inclination of the inclined surface 71a of the third extending pipe 71. Moving. Since the pump 75 is disposed in the discharge path 74 communicated with the discharge port 72, the liquid developer moving toward the discharge port 72 by the suction operation of the pump 75 is discharged to the discharge port 72. Then, the liquid developer is recovered in the liquid developer recovery container 70 through the discharge path 74.

  As described above, also in the developing device 14 according to the second embodiment, the liquid developer that is regulated by the regulating blade 35 and is not supplied to the developing roller 31 does not come into contact with the developing roller 31 again, and the liquid developer collecting container 70 is recovered. This prevents the liquid developer having a solid content concentration higher than a predetermined solid content concentration from being supplied to the developing roller 31. As a result, a toner image having a desired image density can be formed.

  Further, since the liquid developer has a predetermined viscosity, the liquid developer tends to stay in the lower groove 51b and the third extending pipe 71 only by the suction force of the pump 75, but the lower groove 51b and the third extension Since each of the installation pipes 71 has the inclined surface 51bb and the inclined surface 71a, the liquid developer can be positively conveyed to the liquid developer container 70 along the inclined surface 51bb and the inclined surface 71a.

1 Image forming apparatus 10 Photosensitive drum (image carrier)
14 Developing Device 31 Developing Roller (Developer Carrier)
32 Supply roller (supply unit)
33 Nip forming roller (supply section)
38 Liquid developer supply device (supply unit)
40 First collection path (collection unit)
45 1st conveying screw (recovery part)
51b Lower groove 56 First extending pipe 70 Liquid developer recovery container 74 Discharge path 75 Pump NP Supply nip

Claims (2)

A developer carrying member that forms a toner image on the image carrier by supplying the liquid developer to a predetermined image carrier while carrying a liquid developer in which a solid content is dispersed in a liquid;
A supply roller for supplying the liquid developer to the developer carrier;
A nip forming roller that is disposed below the supply roller and forms a supply nip portion that receives the supply of the liquid developer with the supply roller;
A regulating member that regulates the amount of the liquid developer supplied from the supply roller to the developer carrier;
A housing for housing the developer carrier, the supply roller, the nip forming roller, and the regulating member;
A recovery unit that recovers the liquid developer that has been regulated by the regulating member and has not been supplied to the developer carrier so as not to contact the developer carrier again;
With
The housing includes an upper groove portion that rotatably accommodates the nip forming roller, and a lower groove portion that extends in the same direction as the upper groove portion and continues below the upper groove portion ,
The recovery part is disposed in the wall part of the housing defining the upper groove part and the lower groove part, a discharge port communicating with the lower groove part, and the liquid in the lower groove part disposed in the lower groove part. A transport screw that transports the developer to the discharge port, and a first gear attached to one end of the transport screw ,
The liquid developer scraped off by the restriction member is received by the upper groove portion and then the lower groove portion according to natural fall ,
The conveying screw is disposed below the nip forming roller and in parallel with the nip forming roller,
The nip forming roller has a second gear that meshes directly with the first gear at an end corresponding to one end of the conveying screw, and a rotational driving force is applied to the second gear, whereby the nip forming is performed. A developing device in which a roller rotates and the conveying screw rotates with the rotation of the roller . An image forming apparatus comprising the developing device according to claim 1, further processing the liquid developer recovered in the recovery container so that the liquid developer can be supplied again to the developing device, and then supplying the liquid developer to the supplying unit. An image forming apparatus including a liquid developer circulating device configured to be supplied.

Images