JP2002005829A - Liquid-concentration detecting device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid-concentration detecting device, where a liquid membrane is formed in a prescribed membrane thickness, a liquid concentration regarding the liquid membrane can be detected with good accuracy by an optical sensor and the stay of a liquid or a foreign body can be prevented in a region between a liquid carrying member and a layer regulating member, and to provide an image formation apparatus which is provided with the liquid- concentration detecting device. SOLUTION: A liquid-carrying roller 3 is formed by sandwiching a disk part 2, whose diameter is smaller than that of two identical-diameter reference disk parts 1, between the disk parts 1. Discharge grooves 1a, with which the liquid staying in a region between the surface of the roller 3 and a metering blade not indicated in the figure, is discharged to end face sides, opposite to the end faces of the reference disk parts coming into contact with the disk part 2 sandwiched and held by the reference disk parts 1 are formed on the outer circumferential faces of the reference disk parts 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid concentration detecting device and an image forming apparatus such as a copying machine, a facsimile, a printer, etc., provided with the liquid concentration detecting device. The present invention relates to an image forming apparatus provided with the liquid concentration detecting device.

[0002]

2. Description of the Related Art Conventionally, a latent image is developed using a liquid developer (hereinafter referred to as a developer) in which a toner as a solid component is dispersed in a liquid solvent as a carrier, and a toner image is formed on the surface of a transfer material. Various image forming apparatuses are known.

As a method for detecting the concentration of a developer in this type of image forming apparatus, for example, a liquid film of the developer is formed,
A method of detecting the developer concentration of the liquid film with a transmission type or reflection type optical sensor has been studied. For example, in a detection method using a transmission optical sensor, light emitted from a light emitting unit passes through a liquid film, light transmitted through the liquid film is received by a light receiving unit, and a detection value corresponding to the amount of received light is output. Is done. Therefore, there is a characteristic that the output decreases as the developer concentration increases. Further, the sensor output changes according to the film thickness of the developing solution, but the sensor output shows a saturation characteristic in the thin film portion and the thick film portion, and the sensitivity may be lowered. For this reason, it has been difficult to accurately detect the liquid concentration over a wide range using an optical sensor.

Accordingly, the present applicant has filed Japanese Patent Application No. 11-529.
In No. 48, in order to detect a wide range of liquid concentration using an optical sensor, a constant film thickness is not formed, and based on the output of the optical sensor for a plurality of different thicknesses of the liquid to be detected. A method for detecting liquid concentration was proposed.

A liquid concentration detecting apparatus to which this detecting method is applied has a schematic structure as shown in FIG. 7, for example. 2
A liquid carrying roller 3 having an eccentric disk portion 2 smaller in diameter than the reference disk portion 1 between two reference disk portions 1 having the same diameter.
And a metering blade 5 as a layer regulating member that abuts against the liquid carrying roller 3 to regulate the liquid carried by the liquid carrying roller 3 to reduce the thickness, and the optical characteristics of the thinned liquid thin film And a cleaning blade 6 as a cleaning member that contacts the eccentric disk portion 2 and scrapes the liquid film after detection to clean the surface of the eccentric disk portion 2. .

[0006] Then, the liquid carrying roller 3 is moved to the developing solution tank 2.
4 is rotated by being partially immersed in the developing solution 7, and the developing solution 7 to be subjected to the concentration detection is filled in a circumferential recess formed at a step between the eccentric disk portion 2 and the two reference disk portions 1. Then, the developing solution 7 is formed in a plurality of different film thicknesses corresponding to the concave portions. The light emitted from the light emitting portion of the optical sensor 4 irradiates the developer liquid film formed in the concave portion. The light applied to the developer liquid film passes through the developer liquid film and is reflected on the outer peripheral surface of the eccentric disk portion 2. The reflected light is received by the light receiving section of the optical sensor 4, and an analog value corresponding to the intensity of the reflected light is output. In this liquid concentration detection device, since the sensor outputs for the plurality of thicknesses are used, the plurality of thicknesses are set so that the entire region of the concentration range to be detected can be accurately detected at any one of the thicknesses. In this case, the sensor output always includes a sensor output in a region where the sensitivity of the optical sensor is high. By using the sensor outputs for a plurality of thicknesses as described above, even when the sensor does not show an accurate output when performing detection for a single thickness, it is possible to appropriately process the sensor output as described above. This allows accurate detection of the liquid concentration over a wide range.

[0007]

PROBLEM TO BE SOLVED [Problem 1] In the above configuration, the metering blade 5 is brought into contact with the liquid carrying roller 3, and the developing solution 7 is
To fill the recess with the developer 7. At this time, a part of the developer 7 scraped off by the metering blade 5 returns to the developer tank 24 via the end face of the reference disk portion 1 and the metering blade 5, but the other part is metered. It stays in the wedge-shaped region between the blade 5 and the liquid carrying roller 3. When the developer 7 stays in this way, the responsiveness to the developer concentration that changes every moment may decrease. Specifically, when the developer concentration in the developer tank 24 changes abruptly, and the developer stays in the wedge-shaped region, the developer concentration in the concave portion is reduced. There is a possibility that the accumulated developer before the change will be mixed in and the accurate response will be hindered. Further, in the case where, for example, foreign matters or toner aggregates floating in the apparatus adhere to the outer peripheral surface of the reference disk portion 1, the foreign matters move to the wedge-shaped area by the rotation of the liquid carrying roller 3. It will be pinched. The trapped foreign matter or aggregates of the toner may lift the metering blade 5 from the surface of the reference disk 1 and hinder the formation of a thin layer of the developer 7.

In addition to the structure in which the contact angle of the metering blade 5 with the liquid carrying roller 3 is an acute angle as shown in FIG. There is a possibility that the developer may stay in the region between the carrier roller 3. Further, not only when a blade-shaped metering blade is used as the layer regulating member, it is brought into contact with the liquid carrying roller to regulate the layer thickness of the liquid carried on the liquid carrying roller to reduce the thickness, for example, Even when a roller-shaped layer regulating member is used, there is a possibility that the developer may stay in a region between the roller-shaped regulating member and the liquid carrying roller.

[Problem 2] As a material of the metering blade 5 and the cleaning blade 6, a metal plate material having a small thickness, such as stainless steel, is generally used. Such a metal plate material is generally
By passing a metal material between a pair of rollers, it is manufactured to a desired thickness. However, in such a method for manufacturing a plate material, a large stress is applied to the metal material when the metal material passes through the roller, so that residual stress due to the stress may appear as warpage of the plate material. Therefore, conventionally, in order to suppress the warpage of the plate material, each blade is swingably mounted, and is brought into contact with the liquid carrying roller 3 at a predetermined pressure by a biasing means such as a plate spring (not shown). As a mechanism for swingably attaching these blades, for example, as shown in FIG. 8, the metering blade 5 or the cleaning blade 6 is sandwiched between the swing support member 30 and the opposing support member 31 and screwed. There is something.

However, the configuration shown in FIG. 8 has a disadvantage that the number of parts increases and the cost increases. Also, for example, as shown in FIG.
When the developer 7 is caused to flow on the vertically upward surface of the cleaning blade 6 using gravity, and the detected developer 7 is returned to the developer tank 24, the above-described swinging motion is generated on the flow path of the developer 7. If the support member 30, the opposed support member 31, or a protrusion such as a screw is present, the flow of the developer 7 is hindered, and the developer 7 stays on the cleaning blade 6. When the developer 7 stays, as described above, the responsiveness to the developer concentration that changes every moment may decrease.

As a liquid concentration detecting method using an optical sensor, a concentric disk is used instead of the eccentric disk, and the liquid concentration is formed at a step between the two reference disks and the concentric disk. A method is considered in which a liquid to be detected is filled in a circumferential concave portion, the liquid is formed to have a constant film thickness corresponding to the concave portion, and the liquid concentration for the constant film thickness is detected. In this method, although the liquid concentration range in which accurate detection by the optical sensor is possible is narrowed as compared with the case of using the eccentric disk, the film thickness of the liquid is set to a film thickness such that the optical sensor does not show saturation characteristics. If it is set, detection will be performed in the high sensitivity region of the optical sensor, and accurate detection will be possible. The above problem may also occur in a liquid concentration detection device to which such a detection method is applied.

The present invention has been made in view of the above background, and a first object of the present invention is to form a liquid film having a predetermined thickness and accurately measure the liquid concentration of the liquid film using an optical sensor. By providing a liquid concentration detecting device capable of detecting and preventing stagnation of liquid or foreign matter in a region between the liquid carrying member and the layer regulating member, and an image forming apparatus provided with the liquid concentration detecting device is there.

A second object is to form a liquid film having a predetermined thickness, and to accurately detect the liquid concentration of the liquid film by an optical sensor, and to prevent warpage and liquid flow. A liquid concentration detecting device that can reduce cost and prevent stagnation of liquid on the blade-like member by using a blade-shaped member having a simple configuration without a liquid, and an image forming apparatus equipped with the liquid concentration detecting device It is to provide a device.

[0014]

In order to achieve the first object, the present invention is directed to a liquid holding member which rotates while holding a liquid whose concentration is to be detected, and which is in contact with the liquid holding member. hand,
A layer thickness regulating member that regulates the thickness of the liquid carried by the liquid carrying member to reduce the thickness thereof, and detects the liquid concentration of the liquid film carried by the liquid carrying member using an optical sensor. In the liquid concentration detecting device, the liquid carrying member has a disk portion smaller in diameter than the reference disk portion sandwiched between two reference disk portions having the same diameter, and the outer peripheral surface of the reference disk portion has Forming a discharge groove for discharging the liquid staying in the region between the surface of the liquid carrying member and the layer thickness regulating member to the end face side opposite to the end face of the reference disc portion abutting on the disc portion sandwiched between the reference disc portions. It is characterized by having done.

In this liquid concentration detecting device, the rotation of the liquid carrying member causes the circumferential direction formed at the step between the two reference disk portions and the disk portion sandwiched between the reference disk portions. The concave portion is filled with a liquid, and the liquid forms a liquid film having a predetermined thickness corresponding to the concave portion. By setting the predetermined film thickness so that the optical sensor does not exhibit saturation characteristics, the liquid concentration of the liquid film can be accurately detected by the optical sensor. Further, in this liquid concentration detecting device, with the rotation of the liquid carrying member,
The liquid staying in the region between the liquid carrier and the layer regulating member is discharged to the reference disk portion end face side along the discharge groove. In addition, foreign matter that has moved to the area due to the rotation of the liquid carrying member is discharged along the discharge groove along with the liquid to the end face side of the reference disk portion, or is caught in the discharge groove. As a result, it is possible to prevent the liquid or foreign matter from staying in the area.

According to a second aspect of the present invention, in the liquid concentration detecting device of the first aspect, the discharge groove has a groove position in a rotation axis direction in a region between the surface of the liquid carrying member and the layer thickness regulating member. It is characterized in that it is formed obliquely with respect to the surface movement direction of the reference disk so as to move outward with the rotation of the liquid carrying member.

In this liquid concentration detecting device, the position of the diagonal groove formed in the reference disk portion in the rotation axis direction moves outward with the rotation of the liquid carrying member. Due to this movement, the liquid or foreign matter staying in the above-mentioned area is discharged to the reference disk end face side along the oblique groove, so that smooth discharge becomes possible.

According to a third aspect of the present invention, in the liquid concentration detecting device of the second aspect, the reference disk portion is a helical gear, and the helical gear is driven to apply a rotational driving force to the liquid carrying member. The present invention is also characterized in that it is also used as a driven gear that meshes with a gear for use and transmits a rotational driving force to the liquid carrying member.

In this liquid concentration detecting device, the helical gear serving as the reference disk also serves as the driven gear, so that the driven gear is coaxial with the rotation axis of the liquid carrying member, for example. It is possible to reduce the number of components and to save space as compared with the case where the device is separately provided.
Further, in this liquid concentration detecting device, when the helical gear as the reference disk portion meshes with the driving gear, the liquid existing in the tooth groove as the discharge groove is discharged,
The liquid can be more effectively discharged.

In order to achieve the second object,
According to a fourth aspect of the present invention, there is provided a liquid holding member which rotates while holding a liquid to be subjected to concentration detection, and a blade-like member which comes into contact with the liquid holding member and dams the liquid on the liquid holding member. In a liquid concentration detection device that detects a liquid concentration of a liquid film carried on a carrying member by using an optical sensor, a cylindrical portion formed by curling one end of the blade-like member is attached to the blade-like member. It is characterized in that it is used as a support part.

Here, the blade-like member includes a layer thickness regulating member for regulating the layer thickness of the liquid carried on the liquid carrying member to make it thinner, and a cleaning member for cleaning the surface of the liquid carrying member. It is a thing.

In this liquid concentration detecting device, with the rotation of the liquid carrying member, a circumferential direction formed at a step between the two reference discs and the disc sandwiched between the reference discs is formed. The concave portion is filled with a liquid, and the liquid forms a liquid film having a predetermined thickness corresponding to the concave portion. By setting the predetermined film thickness so that the optical sensor does not exhibit saturation characteristics, the liquid concentration of the liquid film can be accurately detected by the optical sensor. Further, in this liquid concentration detecting device, with the rotation of the liquid carrying member,
The liquid on the liquid carrying member is blocked by the blade-shaped member. Since this blade-shaped member uses a cylindrical portion formed by curling one end of the blade-shaped member as a support portion of the blade-shaped member, it is necessary to separately provide a support member for supporting the blade-shaped member. Absent. Also, if the cylindrical portion is formed by curling one end of both ends deformed in a curved shape due to the warpage generated during manufacturing, rigidity is generated at the one end, and the warpage is corrected,
A screw or a support member, which has been conventionally used, for suppressing the warpage of the blade-shaped member is not required, and no protrusion that hinders the flow of the liquid is generated. By using such a blade-shaped member having a simple configuration without a warp or a protrusion that hinders the flow of liquid, it is possible to reduce the cost and prevent the liquid from staying on the blade-shaped member. .

According to a fifth aspect of the present invention, in the liquid concentration detecting apparatus of the first, second, third or fourth aspect, the disk portion sandwiched between the reference disk portions has an outer peripheral surface whose distance from the center of rotation changes. It is characterized by the following.

In this liquid concentration detecting device, with the rotation of the liquid carrying member, a circumferential direction formed at a step between the two reference disk portions and the disk portion sandwiched between the reference disk portions is formed. The recess is filled with a liquid, and the liquid is formed into a plurality of different film thicknesses corresponding to the recess. In this liquid concentration detecting device, the sensor outputs for the plurality of thicknesses are used, so that the plurality of thicknesses are set so that the entire region of the concentration range to be detected can be accurately detected at any one of the thicknesses. In this case, the sensor output always includes a sensor output in a region where the sensitivity of the optical sensor is high. Therefore, even when the sensor does not show an accurate output when the detection is performed for a single thickness, by appropriately processing the sensor output as described above, it is possible to accurately detect the liquid concentration over a wide range.

According to a sixth aspect of the present invention, there is provided an image forming apparatus for forming an image using a liquid developer, wherein the liquid concentration detecting device detects the liquid concentration of the liquid developer.
An image forming apparatus using 2, 3, 4, or 5 liquid concentration detecting devices.

According to this image forming apparatus,
By using the liquid concentration detecting device of 3, 4, or 5, it is possible to obtain a highly accurate detection result that quickly responds to a change in the concentration of the liquid developer. In particular, by using the liquid concentration detecting device of the fourth aspect, the liquid concentration of the liquid developer can be detected by an inexpensive liquid concentration detecting device.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a liquid concentration detecting device for detecting a toner concentration of a developing solution in a wet image forming apparatus will be described below. First, an outline of a wet electrophotographic copying machine (hereinafter, referred to as a copying machine) which is a wet image forming apparatus according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of a main part of a copying machine according to the present embodiment.

A charging unit 12, a developing unit 13, an intermediate transfer member 14, a photosensitive drum cleaning unit 15 and the like are arranged around a photosensitive drum 11 as a latent image carrier. Further, a transfer roller 17 is provided as a transfer unit for transferring the developed image to a transfer paper 16 as a final transfer material, facing the intermediate transfer body 14.

The developing unit 13 contains a high-viscosity developer 7 in which toner particles of each color as visualized particles are dispersed in a carrier liquid as an insulating solvent. The electrostatic latent image formed on the photosensitive drum 11 is developed. In addition, the developing unit 13 is provided with a liquid concentration detecting device (not shown),
The toner concentration of the developer 7 is detected.
The liquid concentration detecting device will be described later in detail.

In the above configuration, the photosensitive drum 11 is driven to rotate at a constant speed in the direction of the arrow at the time of copying by a driving means such as a motor (not shown). After being uniformly charged in the dark by the charging unit 12,
The optical writing unit (not shown) irradiates and forms the writing light LB on the basis of the image information to form an electrostatic latent image on the photosensitive drum 1.
1 is formed. Then, the electrostatic latent image is developed by the developing unit 13, and an image is formed on the photosensitive drum 11. The image formed on the photoconductor drum 11 is transferred onto an intermediate transfer body 14 that is driven at the same speed as the photoconductor drum 11. The image on the intermediate transfer body 14 is transferred to a transfer paper 16 conveyed from a paper feed cassette (not shown) to a transfer section.
Is transferred by the transfer roller 17. After the transfer is completed, the transfer paper 16 is fixed by a fixing unit (not shown) and is discharged. The developer 7 on the photosensitive drum 11 that has not been transferred onto the intermediate transfer member 14 is removed from the photosensitive drum 11 by the photosensitive drum cleaning unit 15. The remaining developer on the intermediate transfer member 14 is removed by an intermediate transfer belt cleaning unit (not shown). Thereafter, the surface of the photoreceptor drum 11 is removed from the residual potential by a discharge lamp (not shown) to prepare for the next copy.

As shown in FIG. 1, the developing unit 13 includes a developing roller 14 as a developer carrier and a developing solution 7.
, A coating roller 25 for applying the developing solution 7 to the developing roller 14, and a pair of screws 26 a and 26 b for supplying the developing solution 7 to the applying roller 25.
And a regulating blade 27 for regulating the amount of the developer 7 on the surface of the application roller 25. When the pair of screws 26a and 26b are driven, the liquid level of the developer 7 in the developer tank 24 rises, and the raised portion contacts the application roller 25, so that the developer 7 is supplied to the application roller 25. You. The amount of the developer 7 supplied to the application roller 25 is regulated by the regulating blade 27, and a predetermined amount of the developer 7 is applied to the development roller 14.

Next, the above-mentioned liquid concentration detecting device, which is a feature of the present invention, will be described. FIG. 2 is a schematic configuration diagram of the liquid concentration detection device according to the present embodiment, and FIG. 3 is an exploded perspective view of the liquid concentration detection device. Note that FIG. 3 is obtained by reversing the left and right of the configuration diagram of FIG. This liquid concentration detecting device includes a liquid carrying roller 3 serving as a liquid carrying member that carries and rotates a developer 7, and a layer of the developer 7 that is in contact with the liquid carrying roller 3 and carried on the liquid carrying roller. A metering blade 5 as a layer thickness regulating member for regulating the thickness and making the layer thinner;
An optical sensor 4 for detecting the optical characteristics of the liquid film thinned on the liquid carrying roller 3, a cleaning blade 6 for coming into contact with the liquid carrying roller 3 and scraping and cleaning the liquid film; Leaf spring members 9 and 1 as pressing means for ring blade 5 and cleaning blade 6
It mainly consists of 0. Each of these members is supported by a fixing bracket 20, as shown in FIG. The leaf spring member 9 presses at two points so that the metering blade 5 abuts against each reference disk portion 1 at a predetermined pressure. Pressure is applied at one point so as to contact with pressure. The leaf spring member 10 is provided with an opening so as not to obstruct the flow of the developer 7 flowing on the vertical upper surface of the cleaning blade 6.

FIG. 4 is an enlarged perspective view of the liquid carrying roller 3. Two reference disks 1 of the same diameter, each with a thickness,
An eccentric disk portion 2 having a smaller diameter than the reference disk portion 1 is sandwiched therebetween, and these three disk portions are integrally rotated around a point O shown in FIG. In addition, the side surface of the eccentric disk portion 2 is a mirror-finished glossy surface for reflecting light from the light emitting portion of the optical sensor 4.

The optical sensor 4 has a light emitting portion for irradiating the eccentric disk portion 2 with light, and a light receiving portion for receiving light reflected from the eccentric disk portion 2. The toner concentration of the developer 41 is detected by measuring the intensity.

Then, the liquid carrying roller 3 is partially immersed in the developing solution 7 and rotated, and the density is detected in the circumferential concave portion formed at the step between the eccentric disk portion 2 and the two reference disk portions 1. The target developer 7 is filled, and the developer 7 is formed into a plurality of different film thicknesses corresponding to the concave portions. The light emitted from the light emitting portion of the optical sensor 4 irradiates the developer liquid film formed in the concave portion. The light applied to the developer liquid film passes through the developer liquid film and is reflected on the outer peripheral side surface of the eccentric disk portion 2. The reflected light is received by the light receiving section of the optical sensor 4, and an analog value corresponding to the intensity of the reflected light is output.

In this liquid concentration detecting device, the sensor outputs for the plurality of thicknesses are used, so that the plurality of thicknesses can be accurately detected at any one of the thicknesses in the entire region of the concentration range to be detected. If you set it to
The sensor output always includes the sensor output in a region where the sensitivity of the optical sensor is high. Therefore, even when the sensor does not show an accurate output when the detection is performed for a single thickness, by appropriately processing the sensor output as described above, it is possible to accurately detect the liquid concentration over a wide range.
The developer 7 after the detection of the toner concentration is scraped off by the cleaning blade 6 and is cleaned.

Further, in the liquid concentration detecting device of the present embodiment,
As shown in FIG. 2, on the outer peripheral surface of the reference disk portion 1, the developing solution 7 and foreign matters staying in the wedge-shaped region between the metering blade 5 and the liquid carrying roller 3 are brought into contact with the eccentric disk portion 2. The discharge groove 1a for discharging to the end face side opposite to the end face is
A plurality are formed at a predetermined pitch. The discharge groove 1 a is formed obliquely to the surface moving direction of the reference disk 1 so that the groove position in the rotation axis direction in the wedge-shaped region moves outward with the rotation of the liquid carrying roller 3. ing. Such a discharge groove 1a can be formed by the same gear cutting and forming method as used for manufacturing a helical gear or a worm. By forming the discharge groove 1a so that the groove does not open on the eccentric disk portion 2 side as shown in the figure, the developer 7 filled in the concave portion can be prevented from flowing out to the discharge groove 1a,
It does not hinder liquid film formation. Also, the discharge groove 1a
Is formed so as to extend toward the eccentric disk portion 2 and open a groove on the eccentric disk portion side, for example, the eccentric disk portion 2 of the metering blade 5 like the cleaning blade 6 shown in FIG. This can be dealt with by making the portion in contact with the reference disk portion 1 longer than the portion in contact with the reference disk portion 1 and forming the liquid film filled in the concave portion at a position lower than the bottom of the discharge groove 1a. The discharge speed increases as the groove width of the discharge groove 1a increases. However, a collision with the tip of the metering blade 5 may occur.

In the above configuration, the position of the discharge groove 1a formed in the reference disk portion 1 in the rotation axis direction in the wedge-shaped region moves outward with the rotation of the liquid carrying roller 3. Due to this movement, the developer 7 staying in the wedge-shaped region
Is discharged along the discharge groove 1a to the end face side of the reference disk portion, and the foreign matter moved to the wedge-shaped area by the rotation of the liquid carrying roller 3 is discharged to the outside along with the developer 7 along the discharge groove 1a. Alternatively, it is sandwiched between the discharge grooves 1a. Then, the discharged developer 7 is quickly returned to the developer tank 24.

As described above, according to the present embodiment, the developing solution 7 and foreign matter staying in the wedge-shaped region between the liquid carrying roller 3 and the metering blade 5 are quickly transmitted along the discharge groove 1a to the reference disk end face. As a result, the developer 7 and foreign matter in the wedge-shaped region can be prevented from staying there. As a result, the responsiveness to a change in the liquid concentration can be improved, and the developer 7 carried on the liquid carrying roller 3 can be satisfactorily thinned. Further, since a highly accurate detection result corresponding to the change in the density of the developing solution 7 can be obtained quickly, it is possible to promptly deal with the change in the density, to maintain a stable image density, and to obtain a good image. Will be able to Further, by forming the discharge groove 1a obliquely to the surface moving direction of the reference disk portion 1, the rotation of the liquid carrying roller 3 allows the liquid or foreign matter staying in the wedge-shaped region to be more smoothly discharged to the outside. Can be discharged to

In the liquid concentration detecting device according to the present embodiment, a helical gear is used as the reference disk portion 1 so that the helical gear can be used as a drive for applying a rotational driving force to the liquid carrying roller 3. It can also be used as a driven gear that meshes with a gear and transmits a rotational driving force to the liquid carrying roller 3. FIG. 4 shows an example of such a configuration. In the configuration shown in FIG. 4, a helical gear which is cut so as not to open a tooth groove on the eccentric disk portion 2 side is used as the reference disk portion 1. In this liquid concentration detecting device, the liquid carrying roller 3 is rotationally driven by a rotational driving force transmitted from a driving motor (not shown) to a driven gear serving as the reference disk unit 1 via a driving gear 8. As described above, by using the helical gear as the reference disk unit 1 also as the driven gear, the configuration of the driven gear is compared with a case where the driven gear is separately provided coaxially with the rotation axis of the liquid carrying roller, for example. Parts can be reduced and space can be saved. In the illustrated example, the helical gear as the reference disk unit 1 is a driving gear 8.
Since the developing solution 7 existing in the tooth groove as the discharging groove 1a is discharged at the time of the engagement, the developing solution 7 can be more effectively discharged to the end face of the reference disk portion.

Next, the metering blade 5 and the cleaning 6 used in the liquid concentration detecting device of this embodiment will be described. In the present embodiment, stainless steel is used for the metering blade 5 and the cleaning blade 6. Then, as shown in FIGS. 2 and 3, one ends of the metering blade 5 and the cleaning blade 6 are respectively curled to form cylindrical portions 5a and 6a in the temporary portions. The cylindrical portions 5a and 6a are used as swing support portions of the respective blades, are inserted into fitting holes respectively formed in the fixed bracket 20, and swingably support the respective blades. . As a method of manufacturing such a metering blade and the cleaning blade 6, for example, as shown in FIG. 6A, the T-shaped stainless steel plate is formed by curling a hatched portion in the figure. it can. As shown in FIG. 6 (b), this T-shaped stainless steel has one end indicated by A in the figure deformed into a curved shape due to warpage generated during the manufacture of a rectangular plate, and the cylindrical portion described above. If cut and formed so as to constitute, the one end is curled, so that the one end has rigidity, and the warpage can be corrected.

In the above configuration, the cylindrical portions 5a and 6a formed by curling one end of each blade are formed.
By using as a swing support part of each blade,
It is not necessary to separately provide a supporting member for swinging and supporting each blade. Further, by curling one end of both ends deformed in a curved shape due to the warp generated during manufacturing to form the cylindrical portion 5a, the warp can be corrected, so that the warpage of the blade is suppressed. This eliminates the need for screws and support members as conventionally used, and eliminates the occurrence of protrusions that hinder the flow of liquid. Therefore, in the liquid concentration detecting device of the present embodiment, the cost can be reduced by using such a blade having a simple configuration without the warp or the protrusion that hinders the flow of the liquid. This makes it possible to detect the liquid concentration of the developing solution 7 using an inexpensive liquid concentration detecting device. Particularly, in the cleaning blade 6, since the developer 7 can be prevented from staying on the blade, it is possible to prevent a decrease in responsiveness to the developer concentration caused by the stay. This makes it possible to obtain an accurate detection result corresponding to the change in the density of the developer quickly, so that it is possible to quickly perform the treatment for the change in the density, to maintain a stable image density, and to obtain a good image. it can.

[0043]

According to the first, second, third and fifth aspects of the present invention, a liquid film having a predetermined thickness can be formed, and the liquid concentration of the liquid film can be accurately detected by the optical sensor. In addition, since the liquid or foreign matter staying in the region between the liquid carrying member and the layer regulating member is quickly discharged to the end face side of the reference disk portion along the discharge groove, the stay of the liquid or foreign matter in the region is prevented. can do. Thereby, the responsiveness to the change in the liquid concentration can be improved, and the liquid carried on the liquid carrying member can be satisfactorily thinned.

In particular, according to the second aspect of the present invention, it is possible to more smoothly discharge the liquid or foreign matter staying in the region between the liquid carrying member and the layer regulating member to the end face of the reference disk portion. There is.

In particular, according to the third aspect of the invention, the number of components is reduced and the space is saved as compared with the case where the driven gear is separately provided, for example, coaxially with the rotation axis of the liquid carrying member. There is an effect that can be. Further, the helical gear as the reference disk portion meshes with the driving gear to discharge the liquid present in the tooth groove as the discharge groove, so that the liquid is more effectively applied to the end surface of the reference disk portion. There is also an effect that it can be discharged to

According to the fourth and fifth aspects of the present invention, there is an effect that the cost can be reduced by using a blade-like member having a simple structure without a warp or a protrusion that hinders the flow of liquid. In addition, there is an effect that stagnation of the liquid on the blade-shaped member can be prevented, and responsiveness to a change in the liquid concentration can be improved.

In particular, according to the fifth aspect of the present invention, since the liquid concentrations of a plurality of different thicknesses of the liquid to be subjected to the concentration detection are detected, an accurate output can be obtained when the detection is performed for a single thickness. Is effective, the liquid concentration can be accurately detected over a wide range.

According to the invention of claim 6, claims 1, 2,
By using the liquid concentration detecting device of 3, 4, or 5, an accurate detection result can be obtained that quickly responds to a change in the concentration of the liquid developer. As a result, it is possible to quickly perform the treatment for the change in density, so that there is an effect that a stable image density can be maintained and a good image can be obtained.
Further, in particular, by using the liquid concentration detecting device of the fourth aspect, there is an effect that the liquid concentration of the liquid developer can be detected using an inexpensive liquid concentration detecting device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a wet image forming apparatus according to an embodiment.

FIG. 2 is a schematic configuration diagram of a liquid concentration detection device according to the embodiment.

FIG. 3 is an exploded perspective view of the liquid concentration detecting device.

FIG. 4 is an enlarged perspective view of a liquid carrying roller.

FIG. 5 is an explanatory diagram illustrating another configuration example of the liquid concentration detection device.

FIGS. 6A and 6B are explanatory views illustrating an example of a blade manufacturing method.

FIG. 7 is an explanatory diagram of a liquid concentration detection device proposed by the present applicant.

FIG. 8 is an explanatory diagram for explaining a problem with a metering blade and a cleaning blade in the liquid concentration detection device proposed by the present applicant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference disk part 1a Discharge groove 2 Eccentric disk part 3 Liquid carrying roller 4 Optical sensor 5 Metering blade 5a Swing support part 6 Cleaning blade 6a Swing support part 7 Developing liquid 8 Driving gear 9 Leaf spring (for metering blade) Pressure means) 10 leaf spring (pressure means for cleaning blade) 11 photoreceptor drum 13 developing unit 14 developing roller 20 fixing bracket 24 developer tank

Claims (6)

[Claims] A liquid holding member which rotates while holding a liquid to be subjected to a concentration detection, and abuts against the liquid holding member to regulate a layer thickness of the liquid held by the liquid holding member to make the liquid thinner. A liquid thickness detection device for detecting the liquid concentration of the liquid film carried on the liquid carrying member by using an optical sensor, wherein the liquid carrying member has two reference disks having the same diameter. A disc portion having a smaller diameter than the reference disc portion is sandwiched between them, and the liquid remaining in an area between the surface of the liquid carrying member and the layer thickness regulating member is formed on the outer peripheral surface of the reference disc portion. A liquid concentration detecting device, wherein a discharge groove is formed on an end surface side opposite to an end surface of the reference disk portion abutting on the disk portion sandwiched between the reference disk portions. 2. The liquid concentration detecting device according to claim 1, wherein the discharge groove has a groove position in a rotation axis direction in a region between the surface of the liquid holding member and the layer thickness regulating member. A liquid concentration detection device characterized by being formed obliquely with respect to the surface movement direction of the reference disk so as to move outward with rotation. 3. The liquid concentration detecting device according to claim 2, wherein the reference disk portion is a helical gear, and the helical gear is
A liquid concentration detecting device, which is also used as a driven gear that transmits a rotational driving force to the liquid carrying member by meshing with a driving gear that applies a rotational driving force to the liquid carrying member. 4. A liquid holding member, comprising: a liquid holding member that rotates while holding a liquid to be subjected to concentration detection; and a blade-like member that abuts on the liquid holding member and dams the liquid on the liquid holding member. In a liquid concentration detection device for detecting the liquid concentration of a liquid film carried on an optical sensor using an optical sensor, a cylindrical portion formed by curling one end of the blade-like member is supported by the blade-like member. A liquid concentration detection device characterized by being used as a part. 5. The liquid concentration detecting device according to claim 1, wherein the disk portion sandwiched between the reference disk portions has an outer peripheral surface whose distance from the center of rotation changes. Liquid concentration detector. 6. An image forming apparatus for forming an image using a liquid developer, wherein the liquid concentration detecting device for detecting the liquid concentration of the liquid developer according to claim 1, 2, 3, 4 or 5. An image forming apparatus using a detection device.