JP5186282B2 - Density detector and image forming apparatus - Google Patents

Description

  The present invention relates to a density detection apparatus and an image forming apparatus.

Conventionally, as a concentration detection device for detecting the concentration of a solute or a dispersoid in a liquid, a device as described in Patent Document 1 is known. In this concentration detection apparatus, a slit is provided in the liquid reservoir. The slit is formed between the moving body and the wall surface, and a liquid layer is formed in the slit by moving the moving body so as to be close to the wall surface. Then, the liquid layer is irradiated with light, and the concentration is detected by the attenuation rate of the light transmitted through the liquid layer.
JP 2005-315948 A

  In the above-described concentration detection apparatus, in order to improve the accuracy of concentration detection, it is necessary to move the moving body to a predetermined position with high accuracy. However, when the moving body is inclined with respect to the wall surface, or when the inclination angle of the moving body with respect to the wall surface is changed every time the concentration is detected, the thickness of the liquid layer is not stable. As a result, the density detection accuracy decreases.

  In the concentration detection apparatus, the upper part of the liquid storage container is opened. For this reason, when the moving body is moved, the liquid in the storage container may be scattered outside the storage container.

  An object of the present invention is to provide a density detection device and an image forming apparatus that can improve the accuracy of density detection and prevent scattering of liquid.

  The concentration detection apparatus according to the first invention includes a casing part, a first liquid layer forming surface, a movable member, a concentration detection part, and a closing member. The casing portion has an internal space into which liquid flows and an opening that communicates with the internal space above the internal space. The first liquid layer forming surface is provided in the internal space. The movable member has a second liquid layer forming surface facing the first liquid layer forming surface above the first liquid layer forming surface, and the second liquid layer forming surface is close to the first liquid layer forming surface and It can move up and down so as to separate. The concentration detecting unit is formed between the second liquid layer forming surface and the first liquid layer forming surface in a state where the second liquid layer forming surface is close to the first liquid layer forming surface with a predetermined distance. Concentration detection is performed on the liquid layer. The closing member has a hole into which the movable member is inserted, restricts the movement of the movable member in the horizontal direction by the edge of the hole, and closes the opening of the casing portion together with the movable member.

  In this concentration detection apparatus, the movable member is inserted into the hole provided in the closing member, and the movement of the movable member in the horizontal direction is restricted by the edge of the hole. For this reason, when the movable member is moved to the predetermined detection position and the second liquid layer formation surface is brought close to the first liquid layer formation surface, the second liquid layer formation surface is shifted or inclined with respect to the predetermined detection position. Can be suppressed. Thereby, the accuracy of density detection can be improved. The closing member closes the opening of the casing portion together with the movable member by inserting the movable member into the hole. Thereby, it is possible to prevent the liquid passing through the internal space from being scattered outside the casing portion.

  A concentration detection apparatus according to a second aspect of the present invention is the concentration detection apparatus according to the first aspect of the present invention, further comprising a regulating member. The restricting member is provided below the closing member in the internal space, and restricts the movement of the movable member in the horizontal direction.

  In this concentration detection device, the movement of the movable member in the horizontal direction can be restricted by the restricting member in addition to the edge of the hole of the closing member. As a result, the movable member can be accurately moved from the predetermined detection position, and the accuracy of density detection can be improved.

  A concentration detection apparatus according to a third aspect of the present invention is the concentration detection apparatus of the second aspect, wherein the restriction member has a plurality of pin-shaped members. The plurality of pin-shaped members are arranged so as to protrude from the side of the movable member toward the movable member in a state where the second liquid layer forming surface is close to the first liquid layer forming surface.

  In this concentration detection apparatus, the movement of the movable member in the horizontal direction is restricted by a plurality of pin-like members. For this reason, a regulating member can be constituted with a simple structure.

  An image forming apparatus according to a fourth aspect of the present invention includes an image forming portion, a casing portion, a first liquid layer forming surface, a movable member, a concentration detecting portion, and a closing member. The image forming unit forms an image on the medium using a liquid developer containing toner and carrier liquid. The casing portion has an internal space into which the liquid developer flows and an opening that communicates with the internal space above the internal space. The first liquid layer forming surface is provided in the internal space. The movable member has a second liquid layer forming surface facing the first liquid layer forming surface above the first liquid layer forming surface, and the second liquid layer forming surface is close to the first liquid layer forming surface and It can move up and down so as to separate. The concentration detecting unit is formed between the second liquid layer forming surface and the first liquid layer forming surface in a state where the second liquid layer forming surface is close to the first liquid layer forming surface with a predetermined distance. Concentration detection is performed on the liquid developer layer. The closing member has a hole into which the movable member is inserted, restricts the movement of the movable member in the horizontal direction by the edge of the hole, and closes the opening of the casing portion together with the movable member.

  In this image forming apparatus, the movable member is inserted into the hole provided in the closing member, and the movement of the movable member in the horizontal direction is restricted by the edge of the hole. For this reason, when the movable member is moved to the predetermined detection position and the second liquid layer formation surface is brought close to the first liquid layer formation surface, the second liquid layer formation surface is shifted or inclined with respect to the predetermined detection position. Can be suppressed. Thereby, the accuracy of density detection can be improved. The closing member closes the opening of the casing portion together with the movable member by inserting the movable member into the hole. Thereby, it is possible to prevent the liquid developer passing through the internal space from being scattered outside the casing portion.

  In the concentration detection apparatus according to the present invention, the movable member is inserted into the hole provided in the closing member, and the movement of the movable member in the horizontal direction is restricted by the edge of the hole. For this reason, when the movable member is moved to the predetermined detection position and the second liquid layer formation surface is brought close to the first liquid layer formation surface, the second liquid layer formation surface is shifted or inclined with respect to the predetermined detection position. Can be suppressed. Thereby, the accuracy of density detection can be improved. The closing member closes the opening of the casing portion together with the movable member by inserting the movable member into the hole. Thereby, it is possible to prevent the liquid passing through the internal space from being scattered outside the casing portion.

  Hereinafter, an embodiment of an image forming apparatus of the present invention will be described based on the drawings. For convenience of explanation, the position and size of the members are drawn with emphasis as appropriate in the drawings. In the following embodiments, a printer will be described as an example of the image forming apparatus of the present invention, but the present invention is not limited to this. That is, the image forming apparatus of the present invention may be a so-called multi-function peripheral (MFP) having a function as a copying machine or a facsimile machine or an apparatus having only a copying function. Specific configurations of these members described below, other members, and the like can be appropriately changed.

1. Configuration 1-1. Overall Configuration FIG. 1 shows a color printer 1 as an image forming apparatus according to an embodiment of the present invention. The color printer 1 includes an image forming unit 2, a paper storage unit 3, a secondary transfer unit 4, a fixing unit 5, a paper transport unit 6, and a discharge unit 7. The image forming unit 2 is of a tandem type that forms a toner image based on image data. The paper storage unit 3 stores paper that is an example of a recording medium. The secondary transfer unit 4 transfers the toner image formed by the image forming unit 2 onto a sheet. The fixing unit 5 fixes the toner image transferred to the paper on the paper. The paper transport unit 6 transports the paper from the paper storage unit 3 to the discharge unit 7. The discharge unit 7 discharges the paper on which fixing has been completed.

  The image forming unit 2 includes an intermediate transfer belt 21, a cleaning unit 22, and a plurality of image forming units FB, FY, FC, and FM.

  The intermediate transfer belt 21 has conductivity and is an endless member, that is, a loop member. The intermediate transfer belt 21 is driven to circulate clockwise as indicated by an arrow in FIGS. The intermediate transfer belt 21 is wider than the width of the largest sheet that can be used in the color printer 1. Here, the “width” refers to the length in the direction perpendicular to the paper transport direction. Hereinafter, the surface facing the outside of the intermediate transfer belt 21 is referred to as a front surface, and the other surface is referred to as a back surface. The intermediate transfer belt 21 is stretched around a driving roller 41, a driven roller 23, and a tension roller 24. When the driving roller 41 is rotated by driving a driving motor (not shown), the intermediate transfer belt 21 is driven. When the intermediate transfer belt 21 is driven, the driven roller 23 and the tension roller 24 are driven to rotate with respect to the intermediate transfer belt 21. The tension roller 24 is a member that applies an appropriate tension to the intermediate transfer belt 21 so that the intermediate transfer belt 21 does not loosen.

  The cleaning unit 22 cleans the intermediate transfer belt 21. The cleaning unit 22 includes a cleaning roller 22a and a cleaning blade 22b.

  Four image forming units FB, FY, FC, and FM are arranged in the vicinity of the intermediate transfer belt 21 and arranged between the cleaning unit 22 and the secondary transfer unit 4 of the intermediate transfer belt 21. The image forming units FB, FY, FC, and FM correspond to black (Bk), yellow (Y), cyan (C), and magenta (M), respectively. Note that the order of arrangement of the image forming units FB, FY, FC, and FM is not limited to this, but this arrangement is preferable in consideration of the influence of the color mixture on the completed image.

  In addition, liquid developer circulating devices LB, LY, LC, LM, toner tanks TB, TY, TC, TM and a main carrier tank MT are provided corresponding to the image forming units FB, FY, FC, FM, respectively. The liquid developer of each color is supplied and collected. The liquid developer circulating devices LB, LY, LC, and LM will be described in detail later.

  As shown in FIG. 2, the image forming units FB, FY, FC, and FM include a photosensitive drum 10, a charging device 11, an exposure device 12, a developing device 14, a primary transfer roller 20, and a cleaning device 26. , A static elimination device 13 and a carrier liquid removal roller 30 are provided. Further, among the image forming units, the image forming unit FB closest to the secondary transfer unit 4 is not provided with the carrier liquid removing roller 30, but the other configurations are the same as those of the other image forming units.

  The photosensitive drum 10 is a cylindrical member, and can carry a toner image charged on its surface (charged to a positive polarity in this embodiment). The photosensitive drum 10 is a member that can rotate counterclockwise as indicated by a broken-line arrow in FIG.

  The charging device 11 is a device that can uniformly charge the surface of the photosensitive drum 10 to a predetermined polarity and potential.

  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, the charge at the exposed portion is removed, and an electrostatic latent image is formed on the surface of the photosensitive drum 10.

  The developing device 14 holds the liquid developer containing the toner and the carrier liquid so as to face the electrostatic latent image on the surface of the photosensitive drum 10, thereby attaching the toner to the electrostatic latent image. Thereby, the electrostatic latent image is developed as a toner image.

  The developing device 14 includes a developing container 140, a developing roller 141, a supply roller 142, a support roller 143, a supply roller blade 144, a development cleaning blade 145, a developer recovery device 146, and a development roller charger 147.

  The developing container 140 is a container that receives supply of a liquid developer composed of toner and a carrier liquid. As will be described later, the liquid developer is supplied from the supply nozzle 278 into the developing container 140 in a state where the ratio of the toner to the carrier liquid is adjusted in advance. The liquid developer is supplied toward a portion of the support roller 143 near the nip portion between the supply roller 142 and the support roller 143. The surplus of the supplied liquid developer falls below the support roller 143 and is stored at the bottom of the developing container 140. The stored liquid developer is recovered by the liquid developer circulating device through the flow path R2.

  The support roller 143 is disposed substantially at the center of the developing container 140 and abuts against the supply roller 142 from below to form a nip portion. The supply roller 142 is disposed obliquely above the support roller 143, and is displaced from the position directly above the support roller 143 in a direction away from the supply nozzle 278. A groove for holding the liquid developer is provided on the surface of the supply roller 142. 2, the support roller 143 rotates counterclockwise and the supply roller 142 rotates clockwise.

  The liquid developer supplied from the supply nozzle 278 is temporarily retained on the upstream side in the rotation direction of the rollers 142 and 143 in the nip portion. As the rollers 142 and 143 rotate, the rollers are carried upward while being held in the groove of the supply roller 142. The supply roller blade 144 is pressed against the surface of the supply roller 142 and regulates the amount of liquid developer so that the amount of liquid developer held on the supply roller 142 becomes a predetermined amount. Excess liquid developer scraped off by the supply roller blade 144 is stored at the bottom of the developing container 140. The stored liquid developer is recovered by the liquid developer circulating device through the flow path R2.

  The developing roller 141 is disposed in contact with the supply roller 142 at an opening provided in the upper portion of the developing container 140. The developing roller 141 is rotated in the same direction as the supply roller 142. That is, at the nip portion where the developing roller 141 and the supply roller 142 abut, the surface of the developing roller 141 moves in the opposite direction to the surface of the supply roller 142. As a result, the liquid developer held on the surface of the supply roller 142 is delivered to the surface of the developing roller 141. Here, since the layer thickness of the liquid developer on the supply roller 142 is regulated to a predetermined value, the layer thickness of the liquid developer layer formed on the surface of the developing roller 141 is also maintained at the predetermined value.

  The developing roller charger 147 moves the toner in the liquid developer layer carried on the developing roller 141 to the surface side of the developing roller 141 by applying an electric field having the same polarity as the charging polarity of the toner. This improves the development efficiency. The developing roller charger 147 is downstream of the developing roller 141 in the rotation direction when viewed from the contact portion between the developing roller 141 and the supply roller 142, and is developed when viewed from the contact portion between the developing roller 141 and the photosensitive drum 10. The roller 141 is provided on the upstream side in the rotation direction so as to face the surface of the developing roller 141.

  The developing roller 141 is in contact with the photosensitive drum 10, and the toner is caused to adhere to the surface of the photosensitive drum 10 by the potential difference between the electrostatic latent image potential on the surface of the photosensitive drum 10 and the developing bias applied to the developing roller 141. Of the electrostatic latent image, it adheres to the portion where the charge is removed by the exposure device 12. As a result, a toner image corresponding to the image data is formed on the surface of the photosensitive drum 10.

  The developing cleaning blade 145 is on the downstream side in the rotation direction of the developing roller 141 when viewed from the contact portion between the developing roller 141 and the photosensitive drum 10, and the developing roller 141 when viewed from the contact portion between the developing roller 141 and the supply roller 142. Is arranged in contact with the surface of the developing roller 141 on the upstream side in the rotation direction. The developing cleaning blade 145 removes the liquid developer on the surface of the developing roller 141 that has completed the developing operation on the photosensitive drum 10.

  The developer recovery device 146 recovers the liquid developer removed by the development cleaning blade 145, and sends the liquid developer to the flow path R1 of the liquid developer circulation device. The liquid developer flows down along the surface of the development cleaning blade 145. However, since the viscosity of the liquid developer is high, the developer recovery device 146 is provided with delivery rollers 34 and 35 for assisting the delivery of the liquid developer. ing.

  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 (minus in this embodiment) 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 cleaning device 26 is a device for removing the liquid developer remaining without being transferred to the intermediate transfer belt 21 from the photosensitive drum 10, and includes a cleaning blade 262 and a conveying screw 261.

  The cleaning blade 262 is a member for scraping off the liquid developer remaining on the surface of the photosensitive drum 10 and is a plate-like member extending in the direction of the rotation axis 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 conveying screw 261 is disposed in the cleaning device 26. The transport screw 261 is scraped off by the cleaning blade 262 and transports the liquid developer stored in the cleaning device 26 to a first recovery container 279 (described later) outside the cleaning device 26. Further, the conveying screw 261 also conveys the carrier liquid removed from the intermediate transfer belt 21 by a carrier liquid removing roller 30 described later and stored in the cleaning device 26 to the first recovery container 279.

  The static eliminator 13 has a light source for static elimination, and neutralizes the surface of the photosensitive drum 10 with light from the light source. The neutralization device 13 performs neutralization after the liquid developer is removed from the surface of the photosensitive drum 10 by the cleaning blade 262 in preparation for the next image formation.

  The carrier liquid removal roller 30 is a substantially cylindrical member that can rotate around a rotation axis parallel to the rotation axis of the photosensitive drum 10. The carrier liquid removal roller 30 rotates in the same direction as 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. The member to be removed. The carrier liquid removed by the carrier liquid removal roller 30 is stored in the cleaning device 26.

  A paper storage unit 3 shown in FIG. 1 is a part for storing paper for fixing a toner image, and is disposed at the lower part of the color printer 1. The paper storage unit 3 includes a paper supply cassette 31 that stores paper, a paper supply roller 32, and a paper separation roller pair 33.

  The secondary transfer unit 4 is a part that transfers the toner image formed on the intermediate transfer belt 21 to a sheet. The secondary transfer unit 4 and the primary transfer roller 20 described above constitute a transfer device that transfers a toner image onto a sheet. The secondary transfer unit 4 includes a drive roller 41 that drives the intermediate transfer belt 21 and a secondary transfer roller 42. The secondary transfer roller 42 is pressed toward the drive roller 41 with the intermediate transfer belt 21 interposed therebetween.

  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 51 and a pressure roller 52. The pressure roller 52 is disposed to face the heating roller 51 and presses the heating roller 51.

  The paper transport unit 6 includes a plurality of transport roller pairs 74 and registration roller pairs 75, and transports the paper from the paper storage unit 3 to the secondary transfer unit 4, the fixing unit 5, and the discharge unit 7. In FIG. 1, only one pair of transport rollers 74 is shown, but the other transport roller pairs are arranged side by side in a direction perpendicular to the paper surface in FIG.

  The discharge portion 7 is a portion from which the toner image is transferred by the secondary transfer portion 4 and the paper fixed by the fixing portion 5 is discharged. The discharge portion 7 is provided on the upper surface of the plurality of discharge roller pairs 71 and the color printer 1. A tray 72 is provided. In FIG. 1, only the pair of discharge rollers 71 is shown, but the other discharge roller pairs are arranged side by side in a direction perpendicular to the paper surface in FIG.

1-2. Configuration of Liquid Developer Circulation Devices LB, LY, LC, LM FIG. 3 shows an outline of the entire liquid developer circulation device LY. The liquid developer circulation device LY is a device for circulating and reusing the liquid developer. Although the structure of the liquid developer circulating device LY will be described here, the other liquid developer circulating devices LB, LC, and LM have the same configuration. Examples of the liquid developer circulated by the liquid developer circulation device LY include a developer (a mixture of toner and carrier liquid) scraped from the surface of the developing roller 141 by the developing cleaning blade 145, and a developing roller from the supply roller 142. There is a developer that has not been supplied to 141, a developer that has been supplied from the supply nozzle 278 to the support roller 143 but becomes excessive, and a developer that has been scraped off from the photosensitive drum 10 by the cleaning device 26.

  The liquid developer circulation device LY includes a second recovery container 271, an adjustment container 272, a first concentration detection device 15, a carrier tank CY, a toner tank TY, a reserve tank 277, a supply nozzle 278, A recovery container 279, a separation and extraction device 82, a second concentration detection device 60, and a plurality of pumps P1 to P12 are provided.

  The second collection container 271 is connected to the developing device 14 by a flow path R1. The second collection container 271 is a tank that can store the developer scraped off from the surface of the developing roller 141 by the developing cleaning blade 145. A pump P1 is attached in the middle of the flow path R1. The pump P <b> 1 moves the liquid developer scraped from the surface of the developing roller 141 to the second collection container 271. The second collection container 271 is connected to the bottom of the developing container 140 by a flow path R2, and a pump P5 is attached to the flow path R2. The pump P5 sends the liquid developer from the developing container 140 to the second recovery container 271.

  The adjustment container 272 is connected to the second collection container 271 and is a part for preparing the developer to be replenished to the developing device 14 (toner density adjustment). The adjustment container 272 is connected to the second recovery container 271 by a flow path R3, and a pump P2 is attached to the flow path R3. The pump P2 sends the liquid developer from the second collection container 271 to the adjustment container 272.

  The first concentration detection device 15 is a device for detecting the toner concentration of the liquid developer in the adjustment container 272, and is connected to an annular flow path R <b> 4 connected to the adjustment container 272. A pump P4 is attached upstream of the first concentration detection device 15 in the annular flow path R4. The pump P4 circulates the liquid developer through the flow path R4. The first concentration detection device 15 will be described in detail later.

  The carrier tank CY stores a carrier liquid. This carrier liquid is used to lower the concentration of toner in the liquid developer in the adjustment container 272 (hereinafter simply referred to as “density”). The carrier tank CY is connected by a flow path R5 to which the adjustment container 272 and the pump P3 are attached. The pump P3 sends the carrier liquid from the carrier tank CY to the adjustment container 272. A carrier tank similar to the carrier tank CY is also provided in each of the other liquid developer circulation devices LB, LC, and LM. These carrier tanks are supplied with carrier liquid from a main carrier tank MT (see FIG. 1) common to each color. The carrier tank and the main carrier tank MT are connected to each other by a branch pipe for each color (not shown). A pump (not shown) is attached to each branch pipe. When the carrier liquid in each carrier tank falls below a predetermined amount, a predetermined amount of carrier liquid is sent from the main carrier tank MT to each carrier tank.

  The toner tank TY contains a liquid developer having a higher concentration than the liquid developer used in the developing device 14. This liquid developer is used to increase the concentration in the adjustment container 272. The toner tank TY is connected by a flow path R6 to which the adjustment container 272 and the pump P8 are attached. The pump P8 sends the liquid developer described above from the toner tank TY to the adjustment container 272.

  The reserve tank 277 stores a liquid developer to be supplied to the developing device 14. The reserve tank 277 is connected to the adjustment container 272 by a flow path R7 to which the pump P6 is attached. The pump P6 sends the liquid developer from the adjustment container 272 to the reserve tank 277. The reserve tank 277 is connected to the supply nozzle 278 by a flow path R8 to which a pump P7 is attached. The pump P7 sends the liquid developer from the reserve tank 277 to the supply nozzle 278.

  The supply nozzle 278 is a device for supplying the liquid developer to the developing device 14.

  The first recovery container 279 is a container for temporarily storing the liquid developer removed from the photosensitive drum 10 by the cleaning device 26.

  The separation and extraction device 82 is a device for separating the liquid developer into toner and carrier liquid, and separately extracting the carrier liquid and toner. The separation / extraction device 82 is connected to the first recovery container 279 by a flow path R9. A pump P9 is attached to the flow path R9, and the liquid developer stored in the first recovery container 279 is sent to the separation and extraction device 82. The separation and extraction device 82 separates the liquid developer conveyed from the first recovery container 279 into toner and carrier liquid, and extracts the carrier liquid and toner. Further, the separation / extraction device 82 is connected to the carrier tank CY by a flow path R10. A pump P10 is attached to the flow path R10. The pump P10 sends the carrier liquid separated in the separation / extraction device 82 to the carrier tank CY.

  Here, the separation and extraction device 82 mainly includes an electrode roller 82a, a weir roller 82b, a liquid container 82c, and a cleaning blade 82d. The electrode roller 82a rotates counterclockwise in FIG. The dam roller 82b is in contact with the electrode roller 82a and rotates clockwise in FIG. Further, a minute interval is provided between the liquid container 82c and the electrode roller 82a. The cleaning blade 82d is in contact with the electrode roller 82a. At least the surfaces of the electrode roller 82a, the weir roller 82b, and the liquid container 82c are formed of a member (for example, a metal or a resin imparted with conductivity) to which a voltage can be applied. Further, a second concentration detection device 60 is connected to the separation and extraction device 82, and the concentration of the liquid developer, here, the carrier liquid extracted by the separation and extraction device 82 is detected. The second concentration detection device 60 is connected to the upstream side of the separation and extraction device 82, that is, the flow channel R9 by the flow channel R12. The second concentration detection device 60 is connected to the downstream side of the separation and extraction device 82, that is, the flow channel R10 by the flow channel R11. A pump P11 is provided in the flow path R11. The pump P <b> 11 is provided to send the liquid developer discharged from the second concentration detection device 60 to the second concentration detection device 60. The flow path R12 is provided with a pump P12. The pump P12 is provided to return the liquid developer whose concentration has been measured by the second concentration detection device 60 to the upstream side of the separation and extraction device 82.

1-3. First concentration detector 15
An exploded perspective view of the first concentration detection device 15 is shown in FIG. 4, and a side sectional view thereof is shown in FIG. The first concentration detection device 15 includes a casing body 16, a spacer 17, a first base member 18, a closing member 19, a movable member 27, a driving mechanism 28, a second base member 29, and a regulating member 36. And a light emitting member 37 and a light receiving member 38.

  The casing body 16 includes a casing part 39, an inflow path 43 (see FIG. 5), an outflow path 44 (see FIG. 5), and a base part 45.

  The casing part 39 has an internal space through which the liquid developer passes. As shown in FIG. 6, a concave portion 39a that is recessed downward is formed at the center of the upper surface of the casing portion 39, and the space surrounded by the concave portion 39a is the internal space. Therefore, the upper part of the internal space is opened, and an opening communicating with the internal space is formed on the upper surface of the casing portion 39. FIG. 6 is a top view of the casing part 39.

  A first fixing portion 39b and a second fixing portion 39c for fixing the spacer 17 are provided on the side of the concave portion 39a. The first fixing portion 39 b and the second fixing portion 39 c are portions that are recessed downward from the upper surface of the casing portion 39. Protrusions 40a and 40b projecting upward are provided on the bottom surfaces of the first fixing portion 39b and the second fixing portion 39c. The first fixing portion 39b is positioned on the side of the inflow passage 43 with respect to the recess 39a, and the second fixing portion 39c is positioned on the side of the outflow passage 44 with respect to the recess. As shown in FIG. 5, the bottom surfaces of the first fixing portion 39 b and the second fixing portion 39 c are located at the same height as the upper surface 45 a of the base portion 45.

  The casing portion 39 has four side surfaces from the first side surface 391 to the fourth side surface 394. The first side surface 391 and the second side surface 392 are facing each other, and the third side surface 393 and the fourth side surface 394 are facing each other. A plurality of holes 39d communicating with the internal space are formed in the first side surface 391 and the second side surface 392. Specifically, the first side surface 391 is provided with two holes 39d arranged in the horizontal direction. Similarly, the second side surface 392 is also provided with two holes 39d arranged in the horizontal direction. The holes 39d on the first side surface 391 and the holes 39d on the second side surface 392 are arranged to face each other. A pin-shaped member 46 described later is inserted into these holes 39d (see FIG. 11).

  An inflow path 43 shown in FIG. 5 is a flow path through which the liquid developer flowing into the internal space passes. One end of the inflow passage 43 communicates with the internal space at the inflow port 43a facing the internal space. The inflow port 43a is provided in the lower part of the side surface of the recess 39a. The other end of the inflow passage 43 communicates with an opening provided at the tip of the inflow portion 39e. The inflow portion 39e is provided so as to protrude from the third side surface 393 of the casing portion 39, and a flow path that connects the pump P4 (see FIG. 3) and the first concentration detection device 15 is connected.

  The outflow path 44 is a flow path through which the liquid developer flowing out from the internal space passes. One end of the outflow passage 44 communicates with the internal space at an outlet 44a facing the internal space. The outflow path 44 is provided on the opposite side of the inflow path 43 with respect to the recess 39a, and the outflow port 44a is provided in the lower part of the side surface on the opposite side of the inflow port 43a in the recess 39a. The other end of the outflow passage 44 communicates with an opening provided at the tip of the outflow portion 39f. The outflow portion 39f is provided so as to protrude from the fourth side surface 394 of the casing portion 39, and a flow path connecting the adjustment container 272 (see FIG. 3) and the first concentration detection device 15 is connected.

  The pedestal 45 projects upward from the bottom surface of the recess 39a in the internal space, and is provided substantially at the center of the internal space as shown in FIG. The base part 45 is located between the first fixing part 39b and the second fixing part 39c. Moreover, the base part 45 is located between the inflow port 43a and the outflow port 44a, and is provided so that the liquid which flows in from the inflow port 43a may be interrupted | blocked. The height of the pedestal 45 is determined by the amount and viscosity of the liquid developer, and is about 6.5 mm, for example. Around the pedestal 45, flow paths 47 and 48 that connect the inflow port 43a and the outflow port 44a are provided.

  The upper surface 45a of the pedestal 45 is a horizontal flat surface and serves as a first liquid layer forming surface for forming a liquid developer layer. As shown in FIG. 5, the upper surface 45a of the pedestal 45 is located above the inflow port 43a and the outflow port 44a, and is located at the same height as the bottom surfaces of the first fixing portion 39b and the second fixing portion 39c. ing. In addition, as shown in FIG. 6, a pair of groove portions 48 a and 48 b are provided on the upper surface 45 a of the base portion 45. The pair of grooves 48a and 48b are arranged at a distance from each other in the direction connecting the inflow port 43a and the outflow port 44a. That is, the pair of grooves 48a and 48b are provided along the flow direction of the liquid flowing into the internal space from the inflow port 43a. One groove 48a reaches the end on the inflow port 43a side on the upper surface 45a of the base 45, and the other groove 48b reaches the end on the outflow port 44a side on the upper surface 45a of the base 45. A portion between the pair of groove portions 48a and 48b in the upper surface 45a of the base portion 45 serves as a transmission portion 48c through which light from the light emitting member 37 described later is transmitted. As shown in FIG. 4, the pedestal portion 45 includes a separate pedestal main body portion 49 and an upper surface portion 50. The base body portion 49 is provided with a hole 49 a that penetrates to the bottom surface of the casing portion 39. The upper surface portion 50 is attached to the base body portion 49 so as to cover the upper portion of the hole 49a. The upper surface portion 50 is made of a light transmissive material, and is made of, for example, a transparent resin.

  The spacer 17 shown in FIG. 4 is in contact with the bottom surface 27a of the movable member 27 and the top surface 45a of the pedestal 45, so that the distance between the bottom surface 27a of the movable member 27 and the top surface 45a of the pedestal 45 is a minute predetermined distance. It is a member hold | maintained. The spacer 17 is a thin metal plate-like member, and has a uniform thickness of about several tens of μm. The thickness of the spacer 17 is adjusted according to the color of the liquid developer that is the target of density detection, the image formation setting, and the like.

  As shown in FIG. 7, both end portions 17a and 17b in the longitudinal direction of the spacer 17 have a wide shape, and are fixed to the first fixing portion 39b and the second fixing portion 39c, respectively. Specifically, holes 17c and 17d are formed in the end portions 17a and 17b, and the protrusions 40a and 40b of the first fixing portion 39b and the second fixing portion 39c are inserted into these holes 17c and 17d. . And fixing member 53a, 53b (refer FIG. 4) is attached from the upper direction of each edge part 17a, 17b of the spacer 17, and each edge part 17a, 17b is respectively set to the 1st fixing part 39b and the 2nd fixing part 39c. Fixed.

  When the end portions 17a and 17b of the spacer 17 are fixed to the first fixing portion 39b and the second fixing portion 39c as described above, the central portion 17e of the spacer 17 is in contact with the upper surface 45a of the base portion 45. It becomes. The central portion 17 e of the spacer 17 is narrower than the end portions 17 a and 17 b and has a linear shape along the longitudinal direction of the spacer 17. Further, a hole 17f extending along the longitudinal direction of the spacer 17 is provided in the central portion 17e. The hole 17f faces the groove portions 48a and 48b and the transmission portion 48c of the pedestal portion 45, and protrudes from the pedestal portion 45 toward the inflow port 43a and the outflow port 44a. Therefore, a part of the liquid developer that has flowed into the internal space from the inflow port 43a passes through the hole 17f, passes through the groove portion 48a, rides on the upper surface 45a of the base portion 45, and flows from the upper surface 45a of the base portion 45 through the groove portion 48b. It flows to the outlet 44a. In FIG. 7, only the spacers 17 are hatched to make the drawing easier to see.

  The first base member 18 shown in FIG. 4 is a plate-like member that supports the casing body 16. The casing body 16 is fixed to the upper surface of the first base member 18. The first base member 18 is formed with a hole 18a penetrating in the plate thickness direction, and the hole 18a is provided at a position facing the hole 49a in the base body 49 described above.

  The closing member 19 has a hole 19a into which the movable member 27 is inserted. The hole 19a has a shape that matches the outer shape of the movable member 27, and the movement of the movable member 27 in the horizontal direction is restricted by the edge of the hole 19a. That is, the movable member 27 is guided in the vertical direction by the closing member 19. The closing member 19 is attached to the upper surface of the casing portion 39 and closes the opening of the casing portion 39 together with the movable member 27. Thereby, the internal space of the casing part 39 is sealed. A concave portion 19b corresponding to the outer shape of the bottom surface of the second lift member 86 to be described later is provided in a portion around the hole 19a on the upper surface of the closing member 19. The bottom surface of the second lift member 86 is inserted into the recess 19b. In addition, a hole 19c to which the liquid adjustment unit 54 (see FIG. 5) is attached is provided on the side of the recess 19b. The hole 19c penetrates the closing member 19 at a position facing the first fixing portion 39b described above. As shown in FIG. 5, a flow path 54a through which the liquid developer passes is provided in the liquid adjustment unit 54, and the liquid adjustment is performed when the liquid developer in the internal space is insufficient. The liquid developer is added to the internal space through the portion 54.

  As shown in FIG. 5, the movable member 27 has a bottom surface 27 a that opposes the upper surface 45 a of the pedestal 45 above the pedestal 45, so that the bottom surface 27 a approaches and separates from the upper surface 45 a of the pedestal 45. In addition, it is a movable member. The bottom surface 27a of the movable member 27 is a second liquid layer forming surface for forming a liquid developer layer. As shown in FIG. 4, the movable member 27 has a movable main body 55 and a bottom surface 56 formed separately.

  The movable main body 55 has a cylindrical shape, and has a hole 55a penetrating in the axial direction. Further, as shown in FIG. 8, a groove portion 55 b is formed in the upper portion of the outer peripheral surface of the movable main body portion 55. The groove portion 55 b is provided along the circumferential direction of the movable main body portion 55.

  The bottom surface portion 56 is attached to the movable main body portion 55 so as to cover the lower portion of the hole 55a. The bottom surface 27a of the bottom surface portion 56 is the above-described second liquid layer forming surface. The bottom surface portion 56 is made of a light-transmitting material, and is made of, for example, a transparent resin.

  The drive mechanism 28 is a mechanism for moving the movable member 27 in the vertical direction, and includes a drive motor 57, a link mechanism 58, a holding portion 59, and an urging member 76.

  The drive motor 57 is controlled by the control unit 77 (see FIG. 3) and generates a driving force that moves the movable member 27. The drive motor 57 is fixed to the upper surface of the second base member 29 via a bracket 57a.

  The link mechanism 58 is a mechanism for transmitting the driving force of the drive motor 57 to the movable member 27 via the holding portion 59, and includes an inner cylindrical portion 78, an outer cylindrical portion 79, an eccentric shaft 81, and a link arm 83. And a first lift member 84.

  The inner cylindrical portion 78 is fixed to the rotation shaft 57 b of the drive motor 57.

  As shown in FIGS. 8 to 10, the outer cylindrical portion 79 is attached to the inner cylindrical portion 78 so as to cover the outer peripheral surface of the inner cylindrical portion 78. 8 and 9 are side cross-sectional views in a plane perpendicular to the cross section in FIG. As will be described later, FIG. 8 shows the first concentration detection device 15 in the standby state, and FIG. 9 shows the first concentration detection device 15 in the detection state. FIG. 10 is a perspective view showing the drive mechanism 28.

  The outer cylindrical portion 79 is provided with a pair of wing portions 79a and 79b. The pair of wing portions 79a and 79b protrude from the outer peripheral surface of the outer cylindrical portion 79 and are arranged in parallel to each other. The pair of wings 79 a and 79 b rotate as the drive motor 57 rotates. Further, a position detection sensor 85 is disposed so as to face the passing positions of the wing parts 79a and 79b, and the operation of the wing parts 79a and 79b is detected. The control unit 77 (see FIG. 3) detects the position of the movable member 27 based on the detection result by the position detection sensor 85.

  The eccentric shaft 81 is eccentric from the rotation axis of the inner cylindrical portion 78 and is fixed to the end surface of the inner cylindrical portion 78. In the following description, the “axial direction” means a direction parallel to the axial direction of the eccentric shaft 81, that is, the axial direction of the rotation shaft 57 b of the drive motor 57.

  The link arm 83 has a shape extending in the vertical direction. A hole 83 a penetrating in the axial direction is formed at the upper end of the link arm 83. An eccentric shaft 81 is inserted into the hole 83a, and the link arm 83 is rotatably attached to the eccentric shaft 81. As shown in FIG. 10, a recess 83 b that is recessed upward is formed at the lower end of the link arm 83. In addition, a hole 83c penetrating in the axial direction is formed at the lower end of the link arm 83 so as to be orthogonal to the recess 83b.

  The first lift member 84 has a bar-shaped horizontal portion 84a extending in the horizontal direction, and a mounting portion 84b provided on the upper surface of the horizontal portion 84a. The horizontal portion 84a is formed with a hole 84c penetrating along the longitudinal direction. A hole 84d penetrating in the axial direction is formed in the mounting portion 84b. As shown in FIG. 10, the attachment portion 84 b is inserted into the recess 83 b of the link arm 83. Then, the pin member 84e is inserted across the hole 84d (see FIGS. 8 and 9) of the mounting portion 84b and the hole 83c (see FIG. 10) of the link arm 83. Accordingly, the first lift member 84 is attached to the link arm 83 so as to be rotatable. The first lift member 84 is located above the second base member 29.

  The holding part 59 holds the movable member 27 so as to be freely movable. The holding part 59 has a second lift member 86 and a locking member 87.

  The second lift member 86 has a pair of arm portions 86a and 86b and a support portion 86c.

  The pair of arm portions 86a and 86b are plate-like members extending in the vertical direction, and are arranged at a distance in the horizontal direction. Holes 86d and 86e penetrating in the horizontal direction are formed at the upper ends of the pair of arm portions 86a and 86b. The arm portions 86 a and 86 b are inserted into a pair of holes 29 a and 29 b formed in the second base member 29, and the upper end portions of the arm portions 86 a and 86 b are positioned above the second base member 29. Further, the horizontal portion 84a of the first lift member 84 is disposed between the upper ends of the pair of arm portions 86a and 86b. Then, the second lift member 86 is attached to the first lift member 84 by inserting the pin member 84f over the holes 86d and 86e of the arm portions 86a and 86b and the hole 84c of the horizontal portion 84a.

  The support portion 86 c has a ring shape and is a portion that supports the movable member 27 via the locking member 87. The support portion 86c is located between the pair of arm portions 86a and 86b, and is connected to the lower ends of the arm portions 86a and 86b. As shown in FIGS. 8 and 9, a hole 86 f having an inner diameter slightly larger than the outer shape of the movable member 27 is formed in the support portion 86 c.

  The locking member 87 is a plate-like member having a ring shape. The locking member 87 is disposed on the upper side of the support portion 86c. The outer diameter of the locking member 87 is slightly smaller than the outer diameter of the support portion 86c and larger than the inner diameter of the support portion 86c. Further, the inner diameter of the locking member 87 is smaller than the outer diameter of the movable member 27 and larger than the outer diameter of the groove portion 55 b of the movable member 27. The locking member 87 is fitted in the groove 55b of the movable member 27 and is locked to the groove 55b. The plate thickness of the locking member 87 is smaller than the width of the groove 55b of the movable member 27 (here, the vertical dimension). That is, the movable member 27 is not fixed to the locking member 87, and play is provided between the groove portion 55 b and the locking member 87. Thereby, the movable member 27 can move by a minute distance in the vertical direction with respect to the locking member 87. Further, since the inner diameter of the support portion 86c is larger than the outer diameter of the movable member 27, the movable member 27 can be slightly swung so that the axis is inclined with respect to the vertical direction.

  The urging member 76 is a coil spring, and is a member for urging the movable member 27 via the locking member 87. The biasing member 76 is located between the pair of arm portions 86 a and 86 b and is located between the lower surface of the second base member 29 and the locking member 87. The outer diameter of the biasing member 76 is smaller than the outer diameter of the locking member 87, and the lower end of the biasing member 76 is in contact with the upper surface of the locking member 87. Further, the inner diameter of the biasing member 76 is larger than the outer diameter of the movable member 27. The upper end portion of the movable member 27 is inserted inside the urging member 76, and the movable member 27 can move inside the urging member 76 in the vertical direction. The urging member 76 urges the locking member 87 downward, that is, toward the spacer 17 side. The biasing member 76 biases the movable member 27 toward the spacer 17 via the locking member 87 in a state where the bottom surface 27a of the movable member 27 is in contact with the spacer 17.

  The second base member 29 supports the drive motor 57. As described above, the second base member 29 has a pair of holes 29a and 29b penetrating in the vertical direction, and the arm portions 86a and 86b are inserted into these holes 29a and 29b. Further, a hole 29c through which an upper end portion 37a of a light emitting member 37 described later is passed is formed between the pair of holes 29a and 29b. The second base member 29 is supported by the first base member 18 via a plurality of support members 18b (see FIG. 4). Here, the four support members 18 b are arranged so as to support the four corners of the second base member 29, and the upper ends of the support members 18 b are inserted into holes 29 a provided in the second base member 29. .

  The regulation member 36 shown in FIG. 4 has a plurality of pin-like members 46. As shown in FIG. 11, the pin-shaped member 46 is inserted into the hole 39d in the first side surface 391 and the second side surface 392 of the casing portion 39 so that the tip of the pin-shaped member 46 protrudes into the internal space. . For this reason, the pin-shaped member 46 is directed from the side of the movable member 27 (see the two-dot chain line in FIG. 11) toward the movable member 27 in a state where the bottom surface 27 a of the movable member 27 is close to the upper surface 45 a of the base 45. It arrange | positions so that it may protrude. In this state, the tip of the pin-shaped member 46 is positioned below the closing member 19 so as to surround the periphery of the movable member 27. Thereby, the pin-shaped member 46 regulates the movement of the movable member 27 in the horizontal direction.

  The light emitting member 37 is fixed to the lower surface of the second base member 29 as shown in FIG. The light emitting member 37 is disposed between the lower surface of the second base member 29 and the movable member 27, and is disposed inside the urging member 76. The light emitting member 37 has an upper end portion 37a, a flange portion 37b, and a main body portion 37c. The upper end portion 37a has a cylindrical outer shape and is inserted into the hole 29c of the second base member 29 described above. The flange portion 37b has a disk-like outer shape and has an outer diameter larger than that of the upper end portion 37a. The main body portion 37c has a smaller outer shape than the flange portion 37b, and is provided below the flange portion 37b. The main body portion 37 c is inserted into the hole 55 a of the movable member 27. A light emitting element 37d is provided at the lower end of the main body 37c, and light can be emitted downward. Light irradiation by the light emitting element 37d is controlled by the control unit 77 (see FIG. 3).

  The light receiving member 38 is provided below the upper surface 45 a of the base 45. The light receiving member 38 has a main body portion 38a and a flange portion 38b. The main body portion 38 a is inserted into the hole 18 a of the first base member 18 described above, and is located inside the base portion 45. A light receiving element 38 c is provided at the upper end of the main body 38 a and receives light emitted from the light emitting member 37. The light emitted from the light emitting element 37d passes through the bottom surface part 56 of the movable member 27, passes through the internal space of the casing part 39 and the upper surface part 50 of the base part 45, and reaches the light receiving element 38c. The light receiving element 38c converts the received light into a voltage. The control unit 77 (see FIG. 3) receives the signal from the light receiving element 38c, and calculates the light attenuation rate from the intensity of the light emitted from the light emitting element 37d and the intensity of the light received by the light receiving element 38c. Calculate and obtain the concentration of the liquid developer from the attenuation rate. As described above, the light receiving member 38 and the light emitting member 37 constitute a density detecting unit that detects the density of the liquid developer.

2. Operation 2-1. Image Forming Operation First, the image forming operation of the color printer 1 will be described with reference to FIGS. 1 and 2. Upon receiving an image formation instruction from a personal computer (not shown) connected to the color printer 1, the color printer 1 converts the toner images of the respective colors corresponding to the image data received with the creation instruction into image forming units FB, FY, FC, It is formed using FM. Specifically, an electrostatic latent image based on image data is formed on the photosensitive drum 10, and toner is supplied to the electrostatic latent image from the developing device 14. The toner images formed by the image forming units FB, FY, FC, and FM in this way are transferred to the intermediate transfer belt 21 and are superimposed on the intermediate transfer belt 21 to form a color toner image.

  In synchronism with the formation of the color toner image, the paper stored in the paper feed cassette 31 of the paper storage unit 3 is taken out from the paper feed cassette 31 by the paper feed roller 32, and one by one by the separation roller pair 33. It is sent to the transport unit 6. The paper is fed to the registration roller pair 75 by the conveyance roller pair 74 of the paper conveyance unit 6. The sheet conveying posture is corrected by the registration roller pair 75 and the sheet is temporarily stopped. Then, the paper is fed from the registration roller pair 75 to the secondary transfer unit 4 in synchronization with the primary transfer to the intermediate transfer belt 21, and the color toner image on the intermediate transfer belt 21 is transferred to the paper by the secondary transfer unit 4. Next transferred. The sheet on which the color toner image is transferred is sent to the fixing unit 5 and the color toner image is fixed on the sheet by the action of heat and pressure.

  The sheet on which the color toner image is fixed is further sent to the discharge unit 7 and discharged by a discharge roller pair 71 to a discharge tray 72 provided outside the color printer 1.

  The residual liquid developer remaining on the intermediate transfer belt 21 after the secondary transfer is removed by the cleaning roller 22a and the cleaning blade 22b of the cleaning unit 22 of the intermediate transfer belt 21.

2-2. Next, the operation of supplying the liquid developer to the developing device 14, that is, the operation of circulating the liquid developer will be described with reference to FIG.

  The liquid developer remaining on the developing roller 141 without being supplied to the photosensitive drum 10 during the image forming operation is scraped off by the developing cleaning blade 145, and the second recovery container 271 is passed through the flow path R1 by the action of the pump P1. To be recovered. Further, the liquid developer received in the developing container 140 is also sent to the second collection container 271 via the flow path R2 by the action of the pump P5. When the liquid developer in the adjustment container 272 is exhausted, the liquid developer is supplied from the second recovery container 271 to the adjustment container 272 via the flow path R3 by the action of the pump P2. Further, the liquid developer remaining on the photosensitive drum 10 without being transferred to the intermediate transfer belt 21 is scraped off by the cleaning blade 262 and stored in the first recovery container 279.

  The liquid developer recovered in the first recovery container 279 is conveyed to the separation / extraction device 82 via the flow path R9 by the action of the pump P9. Then, in the separation and extraction device 82, separation and extraction processing of toner and carrier liquid is performed.

  In the separation and extraction process, first, the liquid developer is injected into the space between the electrode roller 82a and the liquid container 82c by operating the pump P9. Here, for example, when the electrode roller 82a and the dam roller 82b rotate in a state where -500V is applied to the electrode roller 82a and + 500V is applied to the dam roller 82b and the liquid container 82c, the surface of the electrode roller 82a is subjected to liquid development The toner in the agent is attracted and adhered. Then, only the toner adhered to the electrode roller 82a passes through the contact portion between the electrode roller 82a and the blocking roller 82b, and this toner is removed from the surface of the electrode roller 82a by the cleaning blade 82d. As a result, the carrier liquid of the liquid developer is extracted into the space between the electrode roller 82a and the liquid container 82c. After the carrier liquid is extracted for a predetermined time, the carrier liquid extracted in the separation and extraction device 82 is sent to the second concentration detection device 60 via the flow path R11 by the action of the pump P11, and the concentration is detected. Is called. When the toner concentration of the extracted carrier liquid exceeds the specified value, the extracted carrier liquid is returned to the separation / extraction device 82 via the flow path R12 by the action of the pump P12, and the separation / extraction process is performed again. Is called. When the toner concentration of the extracted carrier liquid becomes equal to or less than the specified value, the extracted carrier liquid is sent to the carrier tank CY via the flow path R10 by the action of the pump P10.

  On the other hand, the concentration of the liquid developer in the adjustment container 272 is detected by the first concentration detection device 15, and the concentration of the liquid developer in the adjustment container 272 is adjusted. Here, when the concentration is high, the carrier liquid is supplied from the carrier tank CY to the adjustment container 272 via the flow path R5 by the action of the pump P3. When the concentration is low, a liquid developer having a higher concentration than the liquid developer used in the developing device 14 is supplied from the toner tank TY to the adjustment container 272 via the flow path R6 by the action of the pump P8. The The concentration detection operation by the first concentration detector 15 will be described in detail later.

  Then, the liquid developer whose concentration is adjusted from the adjusting container 272 to the reserve tank 277 as needed is supplied via the flow path R7 by the action of the pump P6. Then, the liquid developer stored in the reserve tank 277 is sent to the supply nozzle 278 via the flow path R8 by the action of the pump P7, and is supplied from the supply nozzle 278 to the developing device 14.

2-3. Liquid Developer Concentration Detection Operation by the First Concentration Detection Device 15 The first concentration detection device 15 is in a standby state shown in FIG. 8 when the liquid developer concentration detection operation is not performed. In this state, the eccentric shaft 81 is positioned above the center of the inner cylindrical portion 78, and the locking member 87 is pulled upward against the biasing force of the biasing member 76 by the second lift member 86. . For this reason, the locking member 87 is pressed against the support portion 86 c of the second lift member 86 by the biasing member 76. In this case, the bottom surface 27 a of the movable member 27 is not in contact with the spacer 17, and the bottom surface 27 a of the movable member 27 and the upper surface 45 a of the base portion 45 are in a state of being largely separated. Further, the upper end of the groove 55b of the movable member 27 and the upper surface of the locking member 87 are in contact (see FIG. 12). For this reason, transmission of the urging force from the urging member 76 to the movable member 27 is blocked, and the urging force is not applied to the movable member 27. Thereby, the movable member 27 is locked to the locking member 87 so as to be freely movable within a predetermined range.

  When the liquid developer concentration detection operation is performed by the first concentration detection device 15, the liquid developer flows into the internal space of the first concentration detection device 15 by driving the pump P <b> 4 (see FIG. 3). It is. At this time, the liquid developer flows into the internal space from the inflow port 43a (see FIG. 5). A part of the liquid developer rides on the platform 45, passes through the upper surface 45a of the platform 45, and is discharged from the outlet 44a. Further, the remaining liquid developer flows separately in the flow paths 47 and 48 (see FIG. 6) around the pedestal 45 and is discharged from the outlet 44a. The pump P4 is driven while the concentration adjustment of the liquid developer in the adjustment container 272 is being performed, and is stopped when the concentration adjustment is completed.

  Next, the first concentration detection device 15 shifts from the standby state shown in FIG. 8 to the detection state shown in FIG.

  Here, when the drive motor 57 is driven, the inner cylindrical portion 78 rotates. As a result, the eccentric shaft 81 rotates around the center of the inner cylindrical portion 78 and moves below the center of the inner cylindrical portion 78. The operation of the eccentric shaft 81 is transmitted to the second lift member 86 via the link arm 83 and the first lift member 84, and the second lift member 86 moves downward from the position in the standby state of FIG. The operation when the second lift member 86 moves from the standby state position shown in FIG. 8 to the detection state position shown in FIG. 9 will be described with reference to FIGS. For easy understanding, the spacer 17 is drawn larger than the actual scale in FIGS.

  First, in the standby state, the second lift member 86 is located at the position shown in FIG. When the second lift member 86 moves downward from this state, the locking member 87 moves downward while being pressed against the support portion 86c of the second lift member 86 by the biasing member 76. When the locking member 87 moves downward, the movable member 27 moves downward together with the locking member 87. As shown in FIG. 13, the bottom surface 27a of the movable member 27 comes into contact with the spacer 17, and the bottom surface 27a of the movable member 27 and the top surface 45a of the pedestal 45 are close to each other with a predetermined distance. When the second lift member 86 further moves downward from this state, the locking member 87 also moves downward while being pressed by the second lift member 86 as shown in FIG. However, since the movable member 27 is in contact with the spacer 17, it cannot move downward. For this reason, the locking member 87 moves away from the upper end of the groove 55b of the movable member 27, moves downward relative to the movable member 27, and contacts the lower end of the groove 55b.

  When the second lift member 86 moves further downward, the second lift member 86 moves away from the locking member 87 as shown in FIG. As a result, the support of the locking member 87 by the second lift member 86 is released, and the urging force from the urging member 76 is applied to the movable member 27 via the locking member 87. As a result, the movable member 27 is urged downward, that is, toward the spacer 17 side. Here, since the movable member 27 is movably held by the holding portion 59, the posture of the movable member 27 can be adjusted when the bottom surface 27 a of the movable member 27 contacts the spacer 17. For this reason, when the bottom surface 27 a of the movable member 27 is pressed against the spacer 17, the bottom surface 27 a of the movable member 27 contacts the spacer 17 uniformly.

  As described above, the first concentration detection device 15 shifts to the detection state shown in FIG. 9, and the bottom surface 27a of the movable member 27 comes close to the upper surface 45a of the base portion 45 with a predetermined distance. The light emitting member 37 irradiates the liquid developer layer formed between the bottom surface 27a of the movable member 27 and the upper surface 45a of the base 45, and the light receiving member 38 applies the liquid developer layer. By receiving the transmitted light, the concentration of the liquid developer is detected.

  When the detection of the concentration of the liquid developer is completed, the second lift member 86 is lifted upward, and the first concentration detection device 15 shifts from the detection state to the standby state.

3. Features In the first concentration detection device 15 described above, the upper surface 45a of the base portion 45 on which the liquid developer layer is formed is located above the inflow port 43a and the outflow port 44a. Further, since the channels 47 and 48 are provided around the pedestal 45, the liquid developer that has not run on the upper surface 45a of the pedestal 45 is divided into these channels 47 and 48 toward the outlet 44a. Flowing. Thereby, it is possible to suppress the liquid developer layer formed on the upper surface 45a of the base 45 from being affected by the flow of the liquid developer from the inlet 43a toward the outlet 44a.

  Further, as described above, the spacer 17 is provided with the holes 17f (see FIG. 7) so as to protrude from the pedestal portion 45 toward the inlet 43a and the outlet 44a. Furthermore, grooves 48a and 48b are formed on the upper surface 45a of the base 45 on the inlet 43a side and the outlet 44a side, respectively. For this reason, the liquid developer flowing in from the inflow port 43a can easily run on the upper surface 45a of the platform 45.

  Further, the distance between the bottom surface 27 a of the movable member 27 and the upper surface 45 a of the base 45 in the detection state is defined to a predetermined size by the spacer 17. Furthermore, since the spacer 17 is formed separately from the pedestal 45, the spacer 17 having a high thickness can be easily manufactured. Further, the end portions 17 a and 17 b of the spacer 17 are fixed to the first fixing portion 39 b and the second fixing portion 39 c and are not directly fixed to the base portion 45. For this reason, it is not necessary to apply an adhesive or the like to the upper surface 45a of the base portion 45. Thereby, it is possible to prevent the distance between the bottom surface 27a of the movable member 27 and the top surface 45a of the base 45 from becoming uneven due to the influence of the thickness of the adhesive.

  As described above, in the first concentration detection device 15, the thickness of the liquid developer layer changes every time the liquid developer layer does not have a desired thickness or the liquid developer layer is formed. Can be suppressed. Further, when the liquid developer flows so as to run on the platform 45, the toner contained in the liquid developer can be diffused. Thereby, the accuracy of density detection can be improved.

4). Other embodiments (a)
In the above-described embodiments, the concentration detection apparatus for detecting the concentration of the liquid developer is exemplified. However, the present invention is applicable to various liquid concentration measurements. For example, measuring the amount of pollutants in river water and seawater in which particulate pollutants are dispersed, measuring the concentration of dyes in which dyes are dissolved, measuring the amount of colored liquids dissolved in water, etc. Measurement of liquid after chemical reaction is an application example.

(B)
In the above embodiment, the light emitting member 37 is provided on the movable member 27 side and the light receiving member 38 is provided on the base 45 side. However, even if the light emitting member 37 and the light receiving member 38 are provided at opposite positions. Good. Further, the light emitting member 37 and the light receiving member 38 may be provided on the same side. In this case, either the bottom surface 27 a of the movable member 27 or the top surface 45 a of the base portion 45 is configured as a reflection surface, and the light reflected on the reflection surface is received by the light receiving member 38.

  The present invention has an effect of improving the accuracy of density detection and preventing the scattering of liquid, and is useful as a density detection device and an image forming apparatus.

1 is an overall schematic cross-sectional view of a color printer according to the present invention. The expanded sectional view of an image forming unit. 1 is an overall schematic cross-sectional view of a liquid developer circulating device. The disassembled perspective view of a 1st density | concentration detection apparatus. Side surface sectional drawing of a 1st density | concentration detection apparatus. The top view of a casing part. The top view which shows the state which attached the spacer to the casing part. Side surface sectional drawing in a surface perpendicular | vertical to the cross section of FIG. 5 of a 1st density | concentration detection apparatus (standby state). Side surface sectional drawing in a surface perpendicular | vertical to the cross section of FIG. 5 of a 1st density | concentration detection apparatus (detection state). The perspective view which shows the structure of a drive mechanism. The top view which shows the positional relationship of a movable member and a control member. The enlarged view of the movable member vicinity in a standby state. The enlarged view of the movable member vicinity in the state in the middle of changing to a detection state from a standby state. The enlarged view of the movable member vicinity in the state in the middle of changing to a detection state from a standby state. The enlarged view of the movable member vicinity in a detection state.

Explanation of symbols

1 Color printer (image forming device)
2 Image forming unit 15 First density detection device (density detection device)
19 Closing member 27 Movable member 36 Restricting member 37 Light emitting member (concentration detection unit)
38 Light receiving member (concentration detector)
39 Casing part 45a Upper surface of the base part (first liquid layer forming surface)
46 Pin-shaped member

Claims (2)

A casing portion having an internal space into which a liquid flows and an opening communicating with the internal space above the internal space;
A first liquid layer forming surface provided in the internal space;
A second liquid layer forming surface facing the first liquid layer forming surface above the first liquid layer forming surface, wherein the second liquid layer forming surface is adjacent to the first liquid layer forming surface; A movable member movable up and down so as to separate;
Liquid formed between the second liquid layer forming surface and the first liquid layer forming surface in a state in which the second liquid layer forming surface is close to the first liquid layer forming surface at a predetermined distance. A concentration detection unit for detecting the concentration of the layer,
A closing member that has a hole into which the movable member is inserted, restricts movement of the movable member in the horizontal direction by an edge of the hole, and closes the opening of the casing portion together with the movable member;
A regulating member provided below the closing member in the internal space and regulating movement of the movable member in a horizontal direction ,
The regulating member has a plurality of pin-like shapes arranged so as to protrude from the side of the movable member toward the movable member in a state where the second liquid layer forming surface is close to the first liquid layer forming surface. A concentration detection apparatus having a member . An image forming unit that forms an image on a medium using a liquid developer containing toner and a carrier liquid;
A casing portion having an internal space into which the liquid developer flows, and an opening communicating with the internal space above the internal space;
A first liquid layer forming surface provided in the internal space;
A second liquid layer forming surface facing the first liquid layer forming surface above the first liquid layer forming surface, wherein the second liquid layer forming surface is adjacent to the first liquid layer forming surface; A movable member movable up and down so as to separate;
Liquid formed between the second liquid layer forming surface and the first liquid layer forming surface in a state in which the second liquid layer forming surface is close to the first liquid layer forming surface at a predetermined distance. A density detector for detecting the density of the developer layer;
A closing member that has a hole into which the movable member is inserted, restricts movement of the movable member in the horizontal direction by an edge of the hole, and closes the opening of the casing portion together with the movable member;
A regulating member provided below the closing member in the internal space and regulating movement of the movable member in a horizontal direction ,
The regulating member has a plurality of pin-like shapes arranged so as to protrude from the side of the movable member toward the movable member in a state where the second liquid layer forming surface is close to the first liquid layer forming surface. An image forming apparatus having a member .

Images