JP3971867B2 - Wet image forming device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wet image forming apparatus such as a copying machine, a facsimile machine, or a printer. Specifically, a latent image on a latent image carrier is developed using a developer in which toner is dispersed in a liquid, and the development is performed. The present invention relates to a wet image forming apparatus for transferring a visualized image to a recording medium directly or via an intermediate transfer member, and collecting and cleaning the residual liquid remaining on the latent image carrier or the intermediate transfer member. is there.
[0002]
[Prior art]
Conventionally, in this type of wet image forming apparatus, untransferred developer remaining on the latent image carrier or intermediate transfer member is scraped off by a cleaning means. The untransferred developer thus scraped off may be discarded without being reused. In particular, in a full-color wet image forming apparatus, since color toners are mixed, it may be difficult to reuse and often discarded. Therefore, there is a possibility that effective use of resources cannot be achieved.
[0003]
Further, in the wet image forming apparatus, the influence of the developer concentration on image formation is large. In particular, when developing an image having an image area ratio of, for example, about 30% or less using a high-concentration developer, the carrier liquid component in the developer adheres to the non-image area on the latent image carrier. The carrier liquid component is consumed more than the toner component. Therefore, the concentration of the developer may increase as the image is formed. Therefore, when the developer exceeds a predetermined concentration, the concentration must be adjusted by supplying a new carrier solution.
On the contrary, when a large number of images having an image area ratio of, for example, more than about 30% are developed, the concentration of the developer is reduced. Therefore, when the developer becomes thinner than a predetermined concentration, it is necessary to replenish new toner components to adjust the concentration.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above background, and an object of the present invention is to provide a wet image forming apparatus capable of effectively utilizing resources and adjusting the developer concentration.
[0005]
The present applicant has proposed a wet image forming apparatus in Japanese Patent Application No. 11-42788.
According to this, the carrier liquid component can be separated and extracted from the developer removed and collected from the cleaning means, and the carrier liquid component can be reused. However, there is no mention of adjusting the concentration of the developer.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 develops a latent image on a latent image carrier using a developer in which toner is dispersed in a liquid, and develops an image visualized by the development. In a wet type image forming apparatus that transfers directly to or via an intermediate transfer member to a recording medium, and collects and cleans the residual liquid remaining on the latent image carrier or the intermediate transfer member, it is removed by the cleaning means that performs the cleaning described above. a separation extraction unit for separating and extracting a liquid component from the collected residual liquid, the liquid component extracted by said separating and extracting means, provided an additive means for adding to the developing solution in the developing unit.
[0007]
In the above configuration, the residual liquid remaining on the latent image carrier or the intermediate transfer body without being transferred to the recording medium in image formation is recovered by the cleaning means, and the recovered residual liquid is separated and extracted. Send to means. The separation and extraction means separates and extracts liquid components from the residual liquid. Then, the concentration of the developer is adjusted by adding the liquid component extracted by the separation and extraction unit to the developing unit. As a result, the liquid component in the residual liquid can be reused without being discarded.
[0008]
Further, the invention of claim 1, upper Symbol developing means includes a concentration detection means for detecting the concentration of the developer, based on the detection result of the concentration detecting means, the developing solution by the addition means Control means for controlling the amount of the liquid component to be added was provided .
[0009]
Upper Symbol control means based on a detection result of the density detection means provided in the developing unit performs control of adding the liquid components. For example, in the developing unit, when the detection result indicates that the developer concentration is higher than a predetermined concentration, the liquid component is added to adjust the developer concentration to a predetermined concentration.
[0010]
Further, the invention of claim 1 is based on the detection result of the upper Symbol concentration detector, provided a control means for controlling the interval to be transferred to the recording medium.
[0011]
Upper Symbol control means based on a detection result from the concentration detector, to control the interval to be transferred to the recording medium. For example, in the case of a detection result that the developer concentration is lower than a predetermined concentration, by performing control to widen the interval, the developing operation is not performed in the interval, and only the liquid component of the developer is Coating on the image carrier. As a result, the ratio of the liquid component in the developer is decreased, and the developer concentration is adjusted to a predetermined concentration.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
Hereinafter, an embodiment in which the present invention is applied to a printer will be described.
First, an outline of the printer according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of a main part of the printer according to the present embodiment. Around the photosensitive drum 1 as a latent image carrier, a charging roller 2, a developing unit 3, an intermediate transfer member 4, a photosensitive drum cleaning unit 5 and the like are disposed. Further, a transfer roller 6 and an intermediate transfer body cleaning unit 7 are also provided as transfer means for transferring the developed image to a transfer sheet (not shown) as a final transfer material, facing the intermediate transfer body 4. Further, a carrier liquid separation unit 9 is provided for separating and extracting the carrier liquid component 8a from the developer 8 collected by the photosensitive drum cleaning unit 5 and the intermediate transfer body cleaning unit 7.
[0013]
The developing unit 3 is installed on a movable table (not shown) that can move in parallel, and development units for yellow, magenta, cyan, and black toner are arranged on the movable table. In addition, a carrier liquid tank 10 for supplying the carrier liquid 8a to each developing unit is provided. Since these developing units have the same structure, the black toner developing unit 3B will be described.
[0014]
The developing portion 3B for black toner is provided with a developing sleeve 11B that faces the photosensitive drum 1 and develops the latent image on the photosensitive drum 1 to visualize it. An application roller 12B for applying the developer 8 to the developing sleeve 11B is disposed in the developer storage tank 13B so that the lower part of the application roller 12B is immersed in the developer 8. The developer storage tank 13B is provided with a doctor blade 14B for regulating the amount of developer on the surface of the coating roller 12B.
A cleaning blade 15B for scraping off the developer 8 that has not been used for development from the surface of the developing sleeve 11B is disposed so as to contact the surface of the developing sleeve 11B. The developer 8 scraped off by the cleaning blade 15B is collected by a developer adjusting unit 16B provided below. The developer adjusting unit 16B is provided with a developer concentration sensor and a liquid amount sensor which will be described later. Based on the detection signals of these sensors, the carrier liquid 8a is supplied from the carrier liquid tank 10 to the developer adjustment unit 16B via the carrier liquid supply electromagnetic valve 17B by the pressure of the carrier liquid supply pump 19. The developer adjusting unit 16B is provided with a stirring means (not shown) so that the replenished carrier liquid 8a and the developer 8 can be stirred to keep the concentration constant.
An appropriate amount of the developer 8 is supplied to the developer storage tank 13B from the developer adjusting unit 16B by the gear pump 18B.
[0015]
FIG. 2 is a schematic configuration diagram of an example of the carrier liquid separation unit 9. The carrier liquid separating unit 9 separates and extracts the carrier liquid 8a by separating the carrier liquid 8a and the toner solid content 8b from the collected developer 8 in which the color toners sent from the cleaning units are mixed. It is. The carrier liquid separation unit 9 is mainly composed of a carrier liquid separation unit 20, a developer recovery tank 21 and a carrier liquid recovery tank 22. The carrier liquid separation unit 20 applies an electric field to the open cell foam 23 as a liquid diffusion suppressing member that suppresses the diffusion of the recovered developer 8 and the recovered developer 8 passing through the open cell foam 23. Therefore, it has a pair of planar electrodes 24a and 24b to which different potentials are applied.
The collected developer 8 is passed through the open cell foam 23 disposed between the pair of flat electrodes 24 a and 24 b from the developer collecting tank 21 by the pressure of the supply pump 25. As a result, for example, only the positively charged toner solid content 8b is electrodeposited and held on the flat electrode 24a side to which the negative voltage of the open cell foam 23 is applied, and only the carrier liquid component 8a is stored in the carrier liquid recovery tank 22. It can be separated and extracted.
[0016]
The carrier liquid 8a separated and extracted as described above is sent to and stored in the carrier liquid tank 10 shown in FIG. 1 by the transport pump 26, and is developed based on a control signal from the main controller 40 (see FIG. 4). The toner is replenished to the portion and reused for adjusting the density of the developer 8.
[0017]
Next, an operation of forming an image with the printer having the above configuration will be described.
As shown in FIG. 1, the photosensitive drum 1 is rotationally driven in the direction of arrow D at a constant speed during printing by a driving means such as a motor (not shown). Then, after being uniformly charged in the dark by the charging roller 2, the writing light LB is irradiated and imaged based on the image information by an optical writing unit (not shown), and the electrostatic latent image is formed on the photosensitive drum 1. It is formed. This image information is monochromatic image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The electrostatic latent image is transferred to a predetermined yellow, magenta, and magenta when the developing unit 3 installed on a movable table (not shown) moves in parallel and the developing unit of a desired color contacts the photosensitive drum 1. Each color image is formed on the photosensitive drum 1 by developing with cyan and black toners.
[0018]
Each color image formed on the photoconductive drum 1 is transferred onto the intermediate transfer body 4 that is driven at the same speed as that of the photoconductive drum 1 for each of the yellow, magenta, cyan, and black colors. The yellow, magenta, cyan, and black images superimposed on the intermediate transfer body 4 are collectively transferred by a transfer roller 6 onto transfer paper (not shown) conveyed from a paper feed cassette (not shown) to a transfer unit. After the transfer is completed, the transfer sheet (not shown) is fixed by a fixing unit (not shown) and discharged to a discharge tray (not shown). The developer 8 remaining on the photosensitive drum 1 that has not been transferred onto the intermediate transfer member 4 is removed from the photosensitive drum 1 by the photosensitive drum cleaning unit 5. Further, the developer 8 remaining on the intermediate transfer body 4 is removed by the intermediate transfer body cleaning unit 7. Thereafter, the residual potential on the surface of the photosensitive drum 1 is removed by a neutralizing lamp (not shown) and the surface is prepared for the next printing.
[0019]
As described above, a small amount of the untransferred developer 8 remaining on the photosensitive drum 1 and the intermediate transfer body 4 is scraped off by the photosensitive drum cleaning unit 5 and the intermediate transfer body cleaning unit 6, respectively, and the carrier liquid separation unit. Sent to 9. In this embodiment, as the developer 8, a developer having a high viscosity of 100 to 10,000 mPa · s in which toner is dispersed in an insulating carrier liquid is used. Therefore, as described above, as the image area ratio is 30% or less, for example, as the image formation is performed, the developer concentration in the developing portion becomes higher.
[0020]
Next, the characteristic part of this embodiment is demonstrated.
FIG. 3 is an explanatory diagram showing an example of a detection sensor for detecting the concentration and amount of the developer 8 in the developer adjusting unit 16B in the black developing unit 3B. Each of these detection sensors should just be arrange | positioned in at least one of the developing solution adjustment part 16B or the developing solution storage part 13B. In the present embodiment, an example in which the developer adjusting unit 16B is disposed will be described. It is assumed that the detection sensor is also provided in each of the yellow, magenta, and cyan developing units.
[0021]
As a sensor for detecting the concentration of the developing solution 8, for example, a light transmission type sensor 30B composed of a light emitting unit 30t and a light receiving unit 30r each incorporated in a Teflon case can be used.
The light emitting unit 30t and the light receiving unit 30r are provided in the developer adjusting unit 16B so as to be immersed in the developer 8, and the light emitted from the light emitting unit 30t is received by the light receiving unit 30r and developed by the amount of received light. The concentration of the liquid 8 is detected. When the concentration of the developer 8 is high, the amount of transmitted light is reduced, so that the amount of received light is also reduced. On the contrary, when the density is low, the amount of transmitted light increases, so the amount of received light also increases. When the light receiving unit 30r receives the light emitted from the light emitting unit 30t, the light receiving unit 30r outputs an analog signal proportional to the amount of received light, and the analog signal is A / D converted by the density detection sensor controller 31B. The A / D converted conversion value is compared with a numerical value stored in a memory (not shown) in the density detection sensor controller 31B. For example, when the developer concentration is high, the dark signal K, when standard, the standard signal N, when thin, A three-stage signal of the thin signal U is transmitted to the main controller 40.
[0022]
In addition, as the liquid amount detection sensor of the developer 8, for example, a capacitive proximity switch can be used. In the present embodiment, the upper limit detecting capacitive proximity switch 33B and the lower limit detecting capacitive proximity switch 34B are arranged in the pipe 32B provided in the developer adjusting unit 16B.
The upper limit detection capacitive proximity switch 33B outputs an upper limit detection signal H from the liquid amount detection sensor controller 35B when the liquid level is equal to or higher than the upper limit. In addition, the lower limit detection capacitive proximity switch 34B outputs a lower limit detection signal L from the liquid amount detection sensor controller 35B when the liquid level is equal to or higher than the lower limit.
[0023]
FIG. 4 is a block diagram showing the electrical connection of the printer with the main controller 40 as the center. The main controller 40 is configured as a logic circuit centered on a microcomputer. Specifically, the CPU 41 executes predetermined calculations according to a preset control program, and is necessary for the CPU 41 to execute various calculation processes. Signals from a ROM 42 in which control programs and control data are stored in advance, a RAM 43 in which various data necessary for executing various arithmetic processes in the CPU 41 are temporarily read and written, a developer concentration detection sensor controller 31B, and the like And an output processing circuit 45 that outputs a drive signal to the carrier liquid supply pump 19, the carrier liquid supply electromagnetic valve 17B, and the like.
[0024]
Next, the concentration control of the developer 8 will be described. Since the control of each color developing unit is the same, the black toner developing unit 3B will be described. FIG. 5 is an example of a control flowchart.
Density control starts at the same time as the operation power of the printer is turned on or the development operation is started.
First, the main controller 40 determines whether or not the concentration of the developing solution 8 in the developing solution adjusting unit 16B of the developing unit 3B is high (step 1). Specifically, it is determined that the density is high when the dark signal K is output from the density detection sensor controller 31B. If it is determined that the concentration of the developing solution 8 is high, the process proceeds to step 2 in order to perform a control for reducing the concentration by replenishing the carrier solution 8a.
[0025]
Then, it is determined whether or not the amount of the developer 8 does not exceed the upper limit (step 2). It is determined that the liquid amount does not exceed the upper limit because the upper limit detection signal H is not output from the liquid amount sensor controller 35B. When it is determined that the liquid amount does not exceed the upper limit, the carrier liquid 8a is replenished so as to lower the concentration of the developer 8 by operating the carrier liquid supply pump 19 and the carrier liquid supply electromagnetic valve 17B (step 3). In step 2, when the amount of the developer 8 exceeds the upper limit (the upper limit detection signal H is output), if the carrier liquid 8a is replenished, the developer adjuster 16B overflows. Then, an alarm is output and a warning is issued to the user (step 4). This alarm continues to issue a warning until the user resets (step 5).
[0026]
When a predetermined volume of carrier liquid 8a is replenished (step 3), it is determined from the standard signal N of the concentration detection sensor controller 31B whether the concentration is a standard value (step 6). If the concentration is not at the standard value, it is determined again whether the amount of the developer 8 does not exceed the upper limit (step 2), and then the carrier liquid 8a is replenished (step 3). However, when it is the standard value, the carrier liquid 8a is not replenished, and it is determined whether or not the control is stopped (step 7). If the control is not stopped, the process returns to step 1 again. If the control is stopped, the control is stopped.
[0027]
If it is determined in step 1 that the concentration of the developer 8 is not high, it is determined whether or not the concentration is low (step 8). Here, when it is determined that the density is low, control is performed to widen the paper gap (step 9). In the present embodiment, the control for widening the sheet interval is a control for increasing the time interval from the transfer of the image from the intermediate transfer body 4 to the transfer sheet (not shown) to the transfer of the image to the next transfer sheet. is there. Since no image is formed between the sheets, only the carrier liquid 8a is applied to the photosensitive drum 1, and the ratio of the carrier liquid 8a in the developer 8 decreases. Thereby, the density of the developer 8 can be increased.
After performing the control to increase the gap between the sheets (step 9), it is determined whether or not the concentration of the developer 8 is standard (step 10). If the density is not standard, control is performed to widen the paper interval again (step 9). If the density is standard, it is determined whether or not the control is stopped (step 7). If the control is not stopped, the process returns to step 1 again. If the control is stopped, the control is stopped.
[0028]
If it is determined in step 8 above that the concentration of the developer 8 is not low, it means that the concentration is standard. Therefore, it is determined whether or not the control is stopped (step 7). If the control is not stopped, the process returns to step 1 again. If the control is stopped, the control is stopped.
[0029]
Paper was actually passed through the printer having the above configuration, and printing was repeated. As a result, the image was good, the quality was good, and there were no problems such as uneven density and background stains.
The amount of toner 8b and carrier liquid 8a consumed by development varies depending on the area of the electrostatic latent image on the photosensitive drum 1 per unit area (specifically, the area of the visible image to which the toner has adhered). As for the ratio of the toner 8b and the carrier liquid 8a, which is desirable as the developing solution 8, the carrier liquid 8a was always insufficient. Therefore, the developer 8 can be maintained at a predetermined concentration by supplying the carrier liquid 8a. In the present embodiment, the concentration of the developer 8 used for development can be easily adjusted simply by replenishing the carrier liquid 8a separated and extracted from the developer 8 collected by each cleaning unit. .
[0030]
In this embodiment, a full-color printer using an intermediate transfer member has been described. However, the present invention is not limited to this, and can be applied to a full-color wet image forming apparatus or a monochrome wet image forming apparatus that directly transfers to a recording medium. .
[0031]
In the present embodiment, the carrier liquid tank 10 is disposed on a movable table (not shown) that can move in parallel. However, if the carrier liquid introduction pipe 36 extending from the carrier liquid tank 10 to the developing solution adjusting section of each developing section can be expanded and contracted and can be adapted to the movement of the movable table, the carrier liquid tank 10 has the movable table. It does not have to be disposed on the top.
[0032]
Furthermore, in the present embodiment, the configuration in which the light transmission type sensor is provided in the developer adjustment unit as the developer concentration detection sensor has been described. However, the standard image formed on the latent image carrier is a light reflection type. It may be detected by a sensor.
[0033]
[Embodiment 2]
In the first embodiment, the configuration in which the developing unit is installed on the movable table that can be moved in parallel has been described. However, the developing unit may be arranged around the latent image carrier and the movable table may not be used. . FIG. 6 is a schematic configuration diagram of a main part of the printer according to the present embodiment.
[0034]
In the printer according to the present embodiment, a yellow developing unit 51Y, a magenta developing unit 51M, a cyan developing unit 51C, and a black developing unit 51B are disposed around a photosensitive drum 50 as a latent image carrier. Each of these developing sections is configured to be able to contact and separate from the photosensitive drum 50 as shown by an arrow in FIG. 6 by a driving means such as a solenoid (not shown). Then, a predetermined developing unit is controlled in contact with the photosensitive drum 50 in accordance with the electrostatic latent image formed on the photosensitive drum 50, and a developing operation is performed. In addition, a carrier liquid separation unit 56 is provided to separate and extract the carrier liquid 55a from the developer 55 collected from the photosensitive drum cleaning unit 52 and the intermediate transfer body 53, and the intermediate transfer body cleaning unit 54. The carrier liquid 55 a separated and extracted by the carrier liquid separation unit 56 is stored in the carrier liquid tank 57.
[0035]
Each developing unit is provided with a developer concentration detection sensor and a liquid amount detection sensor (not shown). Based on the detection results from these detection sensors, the carrier liquid supply pump 58 and the carrier liquid supply electromagnetic valve 59 disposed in each developing section are operated to supply the developing section with the carrier liquid 55a from the carrier liquid tank 56. To do. Thereby, the developing solution 55 of each developing unit can be maintained at a predetermined concentration. Since the concentration control of the developer 55 is the same as that in the first embodiment, the description thereof is omitted.
The carrier liquid separation unit 56, the carrier liquid tank 57, the carrier liquid supply pump 58, and the carrier supply electromagnetic valve 59 are fixed to the printer body, but each carrier supply electromagnetic valve 59 and each developing unit 51 are flexible piping. Therefore, even if each developing unit performs a contact / separation operation with respect to the photosensitive drum 50 for a developing operation, there is no problem.
[0036]
Paper was actually passed through the printer having the above configuration, and printing was repeated. As a result, the image was good, the quality was good, and there were no problems such as uneven density and background stains.
Further, the concentration of the developer 55 used for development can be easily adjusted simply by replenishing the carrier liquid 55a separated and extracted from the developer 55 collected by each cleaning unit.
[0037]
In this embodiment, an example in which a flexible pipe is provided between each developing unit and each carrier supply solenoid valve has been described. However, a configuration in which the flexible pipe is provided between each carrier supply solenoid valve and the carrier liquid supply pump. It is good. This configuration is desirable when each carrier supply electromagnetic valve is disposed in the vicinity of each developing unit and performs a contact / separation operation integrally with the photosensitive drum.
[0038]
【The invention's effect】
According to the first aspect of the invention, the liquid component is separated and extracted from the residual liquid that has not been transferred to the recording medium by the separation and extraction means. Then, the liquid component is added to the developing unit by an adding unit . Thus, the efficient use of resources, it is possible to ing to adjust the developer solution concentration of the developing means.
[0039]
Furthermore, the control means based on a detection result of the density detection means, since the addition of the liquid components, can be ing density adjustment more precise developer.
[0040]
Further , by controlling the interval at which the control means transfers to the recording medium based on the detection result from the density detection means, it is possible to adjust the density by controlling the consumption of the liquid component in the developer. to be able to ing.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a main part of a printer according to an embodiment.
FIG. 2 is an explanatory diagram showing a schematic configuration of a carrier liquid separation unit according to the embodiment.
FIG. 3 is an explanatory diagram of a developer concentration detection sensor and a liquid amount sensor according to the embodiment.
FIG. 4 is a block diagram showing an electrical connection of the printer according to the embodiment with a control device as a center.
FIG. 5 is a flowchart of density control according to the embodiment.
FIG. 6 is an explanatory diagram of a main part of a printer according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Developing unit 3Y, M, C, B Developing part 4 Intermediate transfer body 5 Photosensitive drum cleaning unit 7 Intermediate transfer belt cleaning unit 8 Developer 8a Carrier liquid 8b Toner 9 Carrier liquid separation unit 10 Carrier Liquid tanks 11Y, M, C, B Developing sleeves 12Y, M, C, B Coating rollers 13Y, M, C, B Developer storing units 16Y, M, C, B Developer adjusting units 17Y, M, C, B Carriers Liquid supply solenoid valve 19 Carrier liquid supply pump 30Y, M, C, B Concentration detection sensor 31Y, M, C, B Concentration detection sensor controller 33Y, M, C, B Capacitance proximity switch 34Y, M for upper limit detection , C, B Lower limit detection capacitive proximity switch 35Y, M, C, B Liquid level detection sensor controller 40 Main controller 51Y M, C, B developing unit 55 developer 55a carrier liquid 56 carrier-liquid separation unit 57 the carrier liquid tank 58 the carrier liquid supply pump 59Y, M, C, B carrier liquid supplying solenoid valve 60Y, M, C, B flexible pipe

Claims (1)

A latent image on the latent image carrier is developed using a developer in which toner is dispersed in a liquid, and an image visualized by the development is transferred to a recording medium directly or via an intermediate transfer member. In a wet image forming apparatus for recovering and cleaning the residual liquid remaining on the latent image carrier or the intermediate transfer member,
Separation and extraction means for separating and extracting a liquid component from the residual liquid removed and recovered by the cleaning means for performing the cleaning ;
An adding means for adding the liquid component extracted by the separating and extracting means to the developer in the developing means;
A concentration detecting means for detecting the concentration of the developer in the developing means;
Control means for controlling the amount of the liquid component added to the developer by the adding means based on the detection result of the concentration detecting means;
A wet image forming apparatus, comprising: a control unit that controls a transfer interval to the recording medium based on a detection result of the density detection unit .

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