JP2006220890A - Liquid toner concentration detecting device, image forming apparatus using the same and concentration control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid toner concentration detecting device capable of always stably detecting the concentration of liquid toner with simple constitution and having high detecting accuracy, and to provide an image forming apparatus using the same and a liquid toner concentration control method. <P>SOLUTION: In the detecting device for detecting the concentration of the liquid toner, a light emitting means is arranged on the outside of a liquid toner reservoir case communicating with a developing device through a liquid toner supply path and a liquid toner reflux path and communicating with a concentrated toner tank and a carrier tank through valves respectively, and a member whose surface is moved is arranged in the liquid toner reservoir case as a reflection means, then a light receiving means for receiving reflected light from the reflection means is arranged on the outside of the liquid toner reservoir case, whereby the concentration of the liquid toner is detected according to the reflected light quantity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid toner concentration detection device for detecting the concentration of toner particles of a liquid toner used for development processing of a photoreceptor having an electrostatic latent image formed on a photosensitive layer, an image forming apparatus using the same, and a liquid toner The present invention relates to a density control method.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus using a liquid toner in which fine toner resin particles including a pigment are dispersed in a liquid carrier such as an organic solvent, silicon oil, mineral oil, and edible oil is known.

  An electrophotographic image forming apparatus using liquid toner forms an electrostatic latent image by scanning a laser beam on the surface of an image carrier such as a photoconductor, and the electrostatic latent image is mixed with toner and a liquid carrier. A toner image is formed by developing with liquid toner mixed in a ratio.

  In a developing device using liquid toner, in order to form a high-quality image, the concentration of toner particles in the liquid toner is measured. By replenishing, the toner concentration in the liquid toner is kept within a predetermined range.

In Japanese Patent Laid-Open No. 2001-356608, a measuring head is arranged in a tank containing liquid toner, the measuring head is connected to a light emitting part and a light receiving part by a fiber cable, and light emitted from the light emitting part is transmitted to the measuring head. A portion of the light emitted from the injection port into the liquid toner is scattered by the toner particles in the liquid toner, enters the light receiving port of the measurement head, and is received by the light receiving unit. A liquid toner concentration detection device for detecting the above is disclosed.
Japanese Patent Application Laid-Open No. 2001-5300 discloses a liquid toner oil film forming unit that provides a liquid toner supply unit that connects a liquid toner storage tank and a developing unit, and forms an oil film of the liquid toner in the housing. A light source unit that irradiates an oil film of the selected color liquid toner with color light corresponding to a wavelength region having a relatively low light transmittance with respect to the color liquid toner, and the light source unit provided corresponding to the light source unit There has been disclosed a liquid toner concentration detecting device provided with a photodetector for receiving light transmitted through a liquid toner oil film.
JP 2001-356608 A JP 2001-5300 A

  In recent years, the toner particle size is smaller and higher than that of dry toner due to the demand for downsizing the image forming apparatus that can be installed and moved by the user at any position within the office and the demand for higher quality output images. It is desired that an image forming apparatus using liquid toner capable of obtaining image quality be introduced into an office. In such a request, it is assumed that the image forming apparatus is inclined when the image forming apparatus is installed or moved, or that the image forming apparatus is vibrated. Therefore, the liquid toner concentration detection device disclosed in Japanese Patent Application Laid-Open No. 2001-5300 is a reflection type photosensor itself or a detection window provided in front of the sensor due to inclination or vibration when the image forming apparatus is installed or moved. There is a risk that the liquid toner will adhere to the surface and the desired detection accuracy cannot be obtained. In addition, the liquid toner concentration detection device disclosed in Japanese Patent Application Laid-Open No. 2001-356608 discloses a case where the measurement head is exposed and cannot be detected when the liquid toner in the tank is reduced to a predetermined amount or less, or the exposed measurement head. It is assumed that the liquid toner adhering to the tip of the toner solidifies and the detection function cannot be restored even if the liquid toner is replenished.

  Furthermore, in the case of forming a photographic image in an image forming apparatus using a liquid toner in which fine toner resin particles containing a pigment are dispersed in a liquid carrier, a large amount of toner resin particles are consumed. In some cases, a large amount of liquid carrier is consumed, and it is indispensable to always obtain a high-quality image by keeping the mixing ratio of the toner resin particles and the liquid carrier constant.

  The present invention provides a liquid toner concentration detection device capable of always stably detecting liquid toner concentration detection with a simple configuration and having high detection accuracy, an image forming apparatus using the same, and a liquid toner concentration control method. The purpose is to do.

  In order to solve the above-mentioned problems, the first invention is a detection device for detecting the concentration of liquid toner, wherein the developing device communicates with a liquid toner supply path and a liquid toner circulation path, and further includes a toner tank, a carrier tank, A light emitting means is arranged outside the liquid toner storage case that communicates with each other via a valve, a member whose surface moves within the liquid toner storage case is arranged as a reflecting means, and a light receiving device that receives reflected light from the reflecting means. The means is disposed outside the liquid toner storage case, and the density of the liquid toner is detected from the amount of reflected light.

  According to a second aspect of the present invention, in the liquid toner concentration detecting device according to the first aspect of the present invention, the inner wall curvature of the outer wall of the liquid toner storage case is different from the curvature of the surface of the reflecting means, and the inner surface of the outer wall of the liquid toner storage case. In addition, the light emitting means and the light receiving means are arranged by forming a transparent window on the outer wall of the liquid toner storage case in the vicinity of the proximity point on the surface of the reflecting means.

  According to a third aspect of the present invention, in the liquid toner concentration detecting device according to the first or second aspect of the invention, the inner surface of the outer wall of the liquid toner storage case is slidably brought into contact with a reflecting member that is disposed in the liquid toner storage case and whose surface moves. A sliding contact member is provided.

  According to a fourth aspect of the present invention, in the liquid toner concentration detecting device according to any one of the first to third aspects of the present invention, the reflecting member whose surface is disposed in the liquid toner storage case moves the liquid in the liquid toner storage case. A stirring means for stirring the toner is provided.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus for developing an electrostatic latent image formed on a photosensitive member with liquid toner, comprising the liquid toner concentration detecting device according to any one of the first to fourth aspects of the present invention. .

  According to a sixth aspect of the present invention, in the liquid toner concentration control method, the value of the density detection signal obtained by the liquid toner concentration detection device according to any one of the first to fourth aspects is an upper limit set in advance within a predetermined time. When the value or the lower limit value is exceeded a predetermined number of times or more, the carrier liquid or the concentrated toner is replenished, and the concentration of the liquid toner is maintained within a predetermined range.

  According to a seventh aspect of the present invention, in the liquid toner concentration control method, the concentration detection signal obtained by the liquid toner concentration detection device according to any one of the first to fourth aspects of the present invention is detected at predetermined time intervals, When the average time or the accumulated time exceeds a preset upper limit value or lower limit value, the carrier liquid or the concentrated toner is replenished, and the concentration of the liquid toner is maintained within a predetermined range.

  According to the eighth aspect of the present invention, in the liquid toner concentration control method, a result obtained by integrating the concentration detection signal obtained by the liquid toner concentration detection device according to any one of the first to fourth aspects for a predetermined time is preset. When the upper limit value or the lower limit value is exceeded, the toner or carrier liquid is replenished, and the concentration of the liquid toner is maintained within a predetermined range.

  According to a ninth aspect of the present invention, in the concentration control method for liquid toner concentration, a time during which the concentration detection signal obtained by the liquid toner concentration detection device according to any one of the first to fourth aspects exceeds a preset value is calculated. When the time obtained by averaging the times over an arbitrary number of times exceeds a preset upper limit time or lower limit time, the toner or carrier liquid is replenished to maintain the liquid toner concentration within a predetermined range. To do.

  According to a tenth aspect of the present invention, in the concentration control method for liquid toner concentration, a time during which the concentration detection signal obtained by the liquid toner concentration detection device according to any one of the first to fourth aspects exceeds a preset value is calculated. When the time obtained by adding the number of times exceeds a preset upper limit time or lower limit time, the toner or carrier liquid is replenished to maintain the liquid toner concentration within a predetermined range. To do.

The light emitting means is disposed outside the liquid toner storage case that communicates with the developing device of the present invention through the liquid toner supply channel and the liquid toner circulation channel, and further communicates with the toner tank and the carrier tank via valves, respectively. A member whose surface moves inside the toner storage case is arranged as a reflection means, and a light receiving means for receiving reflected light from the reflection means is arranged outside the liquid toner storage case, and the density of the liquid toner is detected by the amount of reflected light. With this configuration, when the image forming apparatus is tilted when the image forming apparatus is installed or moved, or even if vibration is applied to the image forming apparatus, the reflection type photosensor itself or the front surface of the sensor is used as in Patent Document 1. The liquid toner does not adhere to the provided detection window and the desired detection accuracy cannot be obtained. In addition, since the concentration detection device is installed in a liquid toner storage case separate from the developing device, the concentration control of the liquid toner is facilitated.
The reflective member disposed in the liquid toner storage case and having a moving surface is provided with a sliding contact member that slides on the inner surface of the outer wall of the liquid toner storage case, so that the transparent window portion is in sliding contact with the transparent window portion. Since the liquid toner adhered to the portion is wiped, even when the liquid toner is reduced to a predetermined amount or less, the detection function can be easily restored after the liquid toner is replenished, and the detection can be resumed with high accuracy.
The curvature of the inner surface of the outer wall of the liquid toner storage case is different from the curvature of the surface of the reflecting means, and the outer wall of the liquid toner storing case near the inner surface of the outer wall of the liquid toner storing case and the surface of the reflecting means The configuration in which the light emitting means and the light receiving means are arranged and formed by forming a transparent window part promotes the fluidity of the liquid toner between the reflecting member whose surface moves and the inner wall surface of the container, and the liquid toner concentration in the density detection part As a result, the concentration can be detected.
The reflecting member whose surface is arranged in the container is configured as a stirring means for stirring the liquid toner in the container, so that the liquid toner concentration in the container is made uniform and an accurate liquid toner concentration can be detected. .
Since the image forming apparatus includes the liquid toner concentration detection device as described above, it is possible for the user himself / herself to install or relocate the high-quality image forming apparatus at an arbitrary position in the office. Can be reduced.
Carrier liquid or concentrated toner can be replenished according to the detected light quantity value of the liquid toner concentration detection device obtained with a simple configuration, and the concentration of the liquid toner can be maintained within a predetermined range.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of an embodiment of an image forming apparatus equipped with the liquid toner concentration detection device of the present invention. As shown in FIG. 1, the image forming apparatus according to this embodiment includes yellow, magenta, and cyan below an intermediate transfer belt 400 stretched around a drive roller 401, a cleaner backup roller 402, and auxiliary rollers 403 and 404, respectively. The image forming units Y, M, C, and K for black are arranged in a tandem configuration.

  An image forming procedure of the image forming apparatus according to the present embodiment will be described by using the black image forming unit K as a representative. The image forming units Y, M, and C for yellow, magenta, cyan, and black have the same configuration as the image forming unit for black, and description thereof is omitted.

  The photoconductor 100 formed of an organic photoconductor or an amorphous silicon photoconductor is a charging roller 110 that rotates in contact with the photoconductor 100 while being applied with a bias having the same polarity as the charging polarity of the liquid toner from a power supply device (not shown). As a result, the surface is uniformly charged.

  The charging roller 110 is preferably an elastic roller in which an elastic member such as conductive urethane rubber and a fluororesin surface layer are arranged on the surface of a metal core. Further, a cleaning pad 111 is slidably contacted with the charging roller 110 to remove dirt from the charging roller.

  Next, an electrostatic latent image for black image is written on the uniformly charged photoreceptor 100 by a laser scanning optical system 200 disposed below each color image forming unit.

  On the other hand, in the developing device 300, a uniform liquid toner layer is formed on the developing roller 301 by a structure described later in FIG. 2, and the developing roller 301 to which a developing bias having the same polarity as the liquid toner is applied from a power supply device (not shown) is photosensitive. The black image electrostatic latent image is visualized with liquid toner by rotating in contact with the black image electrostatic latent image formed on the body 100.

  In the liquid toner used in this embodiment, a solid particle having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin is dispersed in a liquid solvent such as an organic solvent, silicon oil, mineral oil, or edible oil. About 20% by weight dispersed while being added.

  The developing roller 301 may have a structure in which an elastic member such as conductive urethane rubber and a resin layer or a rubber layer are provided on the outer periphery of a metal core.

  The liquid toner image immediately after being formed on the photoconductor 100 by the developing roller 301 has a high ratio of the liquid solvent, and if the color is superimposed on the intermediate transfer belt 400 by a transfer device described later, image flow may occur. In this case, an excess liquid solvent is copied by a squeezing roller 330 that rotates in contact with the photosensitive member 100 while applying a bias having the same polarity as the charging characteristics of the toner, thereby increasing the solid particle ratio in the visible image. The liquid solvent copied onto the squeezing roller 330 is scraped off by the squeezing roller cleaner 331.

  The squeezing roller 330 is preferably an elastic roller in which an elastic member such as conductive urethane rubber and a fluororesin surface layer are arranged on the surface of a metal core.

  Next, the visible image on the photoconductor 100 is applied to a primary transfer roller 405 that rotates in contact with the intermediate transfer belt 400 by applying a bias having a polarity opposite to the charging characteristic of the liquid toner from a power supply device (not shown). The image is primarily transferred to the transfer belt 400, and is superposed on a visible image of another color formed on the upstream side in the rotational direction of the intermediate transfer belt 400 by a similar image forming procedure to form a full color image.

  After the primary transfer, the electrostatic latent image is erased by the static elimination lamp 120 formed of a rod-shaped light source, and the liquid toner remaining in the primary transfer is scraped off by the photosensitive member cleaning blade 130 that is in contact with the photosensitive member 100. Again, the charging roller 110 is uniformly charged.

  The used liquid toner scraped off by the photoreceptor cleaning blade 130 is transported in the depth direction of FIG. 1 by the transport screw 131 and collected in a waste toner container (not shown).

  Each color visible image formed on the intermediate transfer belt 400 proceeds to a secondary transfer portion constituted by the intermediate transfer belt 400, a driving roller 401, and a secondary transfer roller 430.

  Corresponding to the timing of image formation, a recording medium 501 such as paper stacked in a paper feed cassette 500 is separated by a pickup roller 502 and a separation pad 503, and a pair of conveying rollers 504, skew feeding of the recording medium, and the like. The sheet is fed to the secondary transfer section through a registration roller pair 505 that corrects the feeding timing.

  The secondary transfer roller 430 is urged by an urging means (not shown) to the driving roller 401 via the intermediate transfer belt 400, and an intermediate transfer is performed by applying a bias having a polarity opposite to the charging characteristics of the liquid toner from a power supply device (not shown). The full color image on the belt 400 is secondarily transferred to the recording medium 501.

  The secondary transfer roller 430 is an intermediate transfer belt 400 between the paper dust and the recording medium attached to the surface of the secondary transfer roller 420 by the secondary transfer roller cleaning blade 421 that is in contact with the secondary transfer roller 430 by the secondary transfer roller cleaner 420. The liquid toner adhering to is scraped off. Paper dust and liquid toner scraped off by the secondary transfer roller cleaning blade 421 are conveyed in the depth direction of FIG. 1 by the conveying screw 422 and collected in a waste toner container (not shown).

  After the secondary transfer, the intermediate transfer belt 400 is subjected to secondary transfer residual toner and paper dust remaining on the surface of the intermediate transfer belt 400 by a belt cleaning blade 411 in a belt cleaner 410 that contacts the cleaner backup roller 402 via the intermediate transfer belt 400. Is scraped off. The secondary transfer residual toner and paper dust scraped off by the belt cleaning blade 411 are transported in the depth direction of FIG. 1 by the transport screw 412 and collected in a waste toner container (not shown).

  A recording medium 501 carrying a secondary-transferred full-color image passes through a fixing device 600 including a heat roller 601 having a heating means inside and a pressure roller 602 having an elastic member such as rubber outside. While the thermoplastic resin in the full-color image is melted, it is pressure-fixed to the recording medium 501 to obtain a desired image.

  After the fixing, the recording medium 501 is discharged from the upper surface of the image forming apparatus by a pair of discharge rollers 506. When forming an image on the back side of the same recording medium 501, the recording medium 501 is switched back by a pair of discharge rollers 506 that can be rotated in the forward and reverse directions, and registered by a pair of refeed rollers 507, 508, and 509. The image is again transferred to the back surface of the recording medium 501 by the secondary transfer unit via the roller pair 505, and after the image is fixed by the fixing device 600, the upper surface of the image forming apparatus is discharged by the paper discharge roller pair 506.

FIG. 2 is a partially enlarged view of the black image forming portion K of the image forming apparatus shown in FIG.
The configuration of the developing device of the image forming apparatus of the present invention will be described with reference to FIG.

  FIG. 2 is a partially enlarged view of the black image forming portion K in the image forming apparatus of FIG. The configuration of the developing device of the image forming apparatus will be described in detail with reference to FIG.

  The developing device 300 has a primary reservoir 315 for liquid toner below the container 320. An agitator 303 having a flexible plate-like stirring member 304 is disposed in the primary storage unit 315.

  The plate-like stirring member 304 is made of a flexible metal plate such as stainless steel or phosphor bronze or a flexible resin plate such as polyethylene terephthalate, and its free end is in sliding contact with the inner periphery of the container 320 of the primary reservoir 315. As the agitator 303 rotates, the liquid toner is agitated, and at the same time, the liquid toner is scraped up to the secondary reservoir 302.

  The liquid toner that has been scraped up and overflowed to the secondary reservoir 302 falls to the primary reservoir due to gravity.

  The secondary reservoir 302 is provided with a toner supply roller 305 provided with fine irregularities such as spiral grooves on the surface, and urethane rubber is provided at the tip of a flexible metal plate so as to contact the rotating toner supply roller 305. The toner toner is rubbed off within the irregularities on the surface of the toner supply roller 305 by the toner regulating blade 306.

  The liquid toner contained in the irregularities on the surface of the toner supply roller 305 is transferred to the surface of the developing roller 301 by bringing the developing roller 301 having an elastic member such as conductive urethane rubber into contact with the surface of the metal core. An uneven pattern on the surface of the toner supply roller 305 by the leveling roller 308 applied to the developing roller 301 and rotated in contact with the developing roller 301 and applied with a bias having the same polarity as the charging polarity of the liquid toner higher than that of the developing roller 301 from a power supply device (not shown). Erasing and making the liquid toner film thickness uniform.

  The leveling roller 308 is preferably a metal roller or a structure in which a conductive resin layer or rubber layer is provided on the surface layer of the metal roller. In this embodiment, the leveling roller 308 counter-rotates with respect to the developing roller 301. However, a speed difference may be provided with respect to the outer peripheral speed of the developing roller 301 to rotate in the driven direction.

  By applying a bias having the same polarity as the charging polarity of the liquid toner higher than that of the developing roller 301 to the leveling roller 308, the solid toner moves to the surface layer of the developing roller 301 and the liquid toner on the developing roller 301 is loosely coupled. Wake up. This loose coupling has an effect of accelerating the rapid movement of solid particles in the liquid toner from the developing roller 301 to the latent image forming portion of the photosensitive member 100 at the developing nip where the developing roller 301 contacts the photosensitive member 100. The image density can be improved.

  The leveling roller blade 309 contacts the leveling roller 308 in the counter direction, and scrapes off the liquid toner adhering to the leveling roller 308. The liquid toner scraped off by the leveling roller blade 309 is returned to the primary storage unit 315 via the recovery port 310 by gravity.

  The developing roller blade 307 is brought into contact with the surface of the developing roller 301 on the downstream side of the developing nip portion, and the remaining development—the liquid toner is scraped off to clean the surface of the developing roller 301. The liquid toner scraped off by the developing roller blade 307 is returned to the primary storage unit 315 via the recovery path 311 by gravity.

  The toner returned to the primary storage unit 315 via the recovery port 310 and the recovery path 311 is agitated by the agitator 303 and scraped up to the secondary storage unit 302 again.

  FIG. 3 is a sectional view showing Embodiment 1 of the liquid toner concentration detecting apparatus of the present invention. As shown in FIG. 3, the liquid toner concentration detection device 700 communicates with the developing device 300 through a toner reflux path 701 and a toner supply path 703. Liquid toner is conveyed by pumps P1 and P2, and a filter 702 is provided in the middle of the toner recirculation path 701 to remove coarse toner solid particles and foreign matters mixed in for some reason.

  In this embodiment, the liquid toner is transported by the pumps P1 and P2. However, when the liquid toner concentration detecting device 700 can be arranged at a height different from the toner liquid level of the primary storage portion 315 of the developing device 300, the pump is used. It is possible to replace either P1 or P2 with a valve. As the pumps P1 and P2, a tube pump, a diaphragm pump, a gear pump, or the like can be used.

  A stirring screw 705 and a stirring roller 706 for stirring the liquid toner are provided in the case 704 for storing the liquid toner. The outer periphery of the stirring roller 706 and the inner surface of the case 704 have different curvatures R1 and R2, and the distance between them is preferably 0.5 mm or less, and 0.1 mm or less when high-concentration liquid toner is used. It is desirable to arrange. Further, it is desirable that the surface of the stirring roller 706 is made of metal or a metal plating film so as to have a high light reflectance.

  The case 704 at the position where the outer periphery of the stirring roller 706 and the inner surface of the case 704 are closest is provided with an opening, and the opening 704a is sealed with a window member 707 made of a transparent member such as glass or resin, A reflective photosensor 708 is arranged so that irradiation light and reflected light can be obtained between the surface of the stirring roller 706 through the window member 707.

  In the case 704, the liquid toner is stirred by the stirring screw 705 and the stirring roller 706, and the liquid toner is guided to the window member 707 by the rotation of the stirring roller 706. At this time, the reflected light of the reflection type photosensor is detected, and solid particle concentration information in the liquid toner is obtained by a liquid toner detection method (described in FIGS. 7, 8, and 9) described later in the control circuit 709.

  According to the obtained concentration information, the concentner is stored by the valves 713 and 711 from the conch toner tank 710 storing conch toner having a solid particle concentration higher than that of the liquid toner or the carrier tank 712 storing liquid mixture of the liquid solvent and the dispersant. Alternatively, an appropriate amount of carrier is supplied, and the liquid toner concentration in the case 704 is kept substantially constant.

  In the present embodiment, a suitable amount of the toner or carrier is replenished by gravity from the toner tank 710 or carrier tank 712 with the valves 711 and 713, but the valve 711 or 713 is replaced with a pump such as a tube pump, a diaphragm pump, or a gear pump. It is also possible.

  As described above, in the present invention, the liquid toner is sandwiched between the outer periphery of the stirring roller 706 and the inner surface of the window member 707, and the density of the liquid toner is detected by the reflective photosensor 709 provided outside the window member 707. When the image forming apparatus is tilted during installation or movement, or even if vibration is applied to the image forming apparatus, liquid is applied to the reflection type photosensor itself or the detection window provided on the front surface of the sensor as disclosed in Patent Document 1. The toner does not adhere and a desired detection accuracy cannot be obtained. Further, the outer periphery of the stirring roller 706 and the inner surfaces of the case 704 and the window member 707 have different curvatures, and both are arranged close to each other, so that the outer periphery of the stirring roller 706, the case 704 and the window member are rotated during the rotation of the stirring roller 706. The liquid toner pressure in the proximity portion 707 is increased.

  Due to this pressure, the inner peripheral surface of the window member 707 is refreshed. For example, even when the image forming apparatus is not used for a long time or when the liquid toner in the case 704 is exhausted, the toner concentration can be easily detected. It is possible to return to a possible state, and even if the liquid toner is reduced to a predetermined amount or less, the detection function can be easily restored after replenishment of the liquid toner, and the detection can be resumed with high accuracy.

  Furthermore, the liquid toner concentration detection device of this example can perform mixing and mixing for reusing liquid toner and liquid toner concentration detection in one device, and the entire image forming apparatus can be miniaturized. is there.

  FIG. 4 is a cross-sectional view showing Embodiment 2 of the liquid toner concentration detecting apparatus of the present invention. The main configuration and operation of the present embodiment are the same as those of the first embodiment, and the description thereof is omitted.

  A component different from that of the first embodiment is that the liquid toner stirring member in the case 704 is composed of a stirring plate 705 (a) and a stirring roller 706a, and both of them are rotated when the stirring plate 705 (a) and the stirring roller 706a rotate. The agitation performance of the liquid toner is improved as compared with the first embodiment because the concave and convex shapes on the outer peripheral portion of the liquid toner face each other.

  In addition, since the stirring roller 706a having projections and depressions rotates with respect to the window member 707, the pressure fluctuation of the liquid toner at the proximity point between both members is larger than that in the first embodiment, and the inner peripheral surface of the window member 707 is increased. It becomes easy to refresh.

  5A and 5B are cross-sectional views showing Embodiments 3 and 4 of the liquid toner concentration detection device of the present invention. The main configuration and operation of the present embodiment are the same as those of the first embodiment, and the description thereof is omitted.

  In FIG. 5A, a component different from that of the first embodiment is that a stirring roller blade 714 that contacts the stirring roller 706a is provided. The stirring roller blade 714 is preferably a flexible metal plate such as urethane rubber, stainless steel, phosphor bronze, or the like, and has a function of cleaning the surface by contacting the stirring roller 706a. With this cleaning function, it is possible to obtain a stable output signal of the reflective photosensor 708 even when liquid toner having a high concentration of solid particles is used.

  In FIG. 5B, a component different from that in the first embodiment is that a refresh blade 715 is provided on the outer periphery of the stirring roller 706. The refresh blade 715 is preferably a soft member such as urethane rubber or polyethylene resin, and is brought into sliding contact with the window member 707 by the rotation of the stirring roller 706 to clean the inner surface side of the window member 707. With this cleaning function, even when liquid toner having a high solid particle concentration is used, the inner surface side of the window member 707 is always refreshed, so that a stable output signal of the reflective photosensor 708 can be obtained.

  FIG. 6 is a flowchart for explaining a liquid toner concentration control method (part 1) in the liquid toner concentration detection apparatus of FIG. In this example, a description will be given on the assumption that the lower the liquid toner density, the larger the amount of reflected light returning to the reflective photosensor 708, and the greater the signal obtained by the reflective photosensor 708.

  A signal obtained by the reflection type photosensor 708 in FIG. 3 is amplified by an amplification circuit 720 provided in the reflection type photosensor 708 or the control circuit 709, and a high-frequency component in the signal is removed by a low-pass filter.

  Next, the number of times that the value of the signal exceeds a predetermined allowable upper limit value and allowable lower limit value within a predetermined time is counted. If the number of times that the signal value exceeds the allowable upper limit exceeds the predetermined number, it is determined that the liquid toner concentration has decreased, and the valve 711 in FIG. Then, the signal is replenished into 704 and the signal amplification process, the low-pass filter process, and the count exceeding the allowable upper limit value and the allowable lower limit value are performed again.

  If the number of times that the signal value exceeds the allowable upper limit value is equal to or less than the predetermined number of times, it is next determined whether the number of times that the signal value exceeds the allowable lower limit value is equal to or less than the predetermined number of times.

  If the number of times the signal value exceeds the allowable lower limit exceeds the predetermined number, it is determined that the concentration of the liquid toner has increased, the valve 713 in FIG. 3 is opened for a predetermined time, and the carrier is removed from the carrier tank 712 into the case 704. The signal amplification process, the low-pass filter process, and the number of times exceeding the allowable upper limit value and the allowable lower limit value are counted again.

  If both determination processes are equal to or less than the predetermined number, the signal amplification process, the low-pass filter process, and the count exceeding the allowable upper limit value and the allowable lower limit value are performed again.

  In the case 704, the carrier or toner supplied by the above control is mixed with the liquid toner in the case 704 by the stirring screw 705 and the stirring roller 706. By repeating these controls, the liquid toner concentration in the case 704 is set to a predetermined value. Keep within the range.

  The liquid toner control method of the present embodiment can also be applied to the liquid toner concentration detection device described with reference to FIGS. 4 and 5B. In this case, the stirring roller 706a and FIG. It is necessary to perform the above control at a timing at which reflected light is obtained in synchronization with the rotation period of the stirring roller 706.

  By adopting such a configuration, it is possible to control the density of the liquid toner with a simple circuit and software configuration.

  FIG. 7 is a flowchart for explaining a liquid toner concentration control method (part 2) in the liquid toner concentration detection apparatus of FIG. In this example as well, the description will be made on the assumption that the lower the liquid toner density, the larger the amount of reflected light returning to the reflective photosensor 708, and the greater the signal obtained by the reflective photosensor 708.

  A signal obtained by the reflection type photosensor 708 in FIG. 3 is amplified by an amplification circuit 720 provided in the reflection type photosensor 708 or the control circuit 709, and a high-frequency component in the signal is removed by a low-pass filter.

  Next, the signal is sampled at a predetermined interval time, and the value of the signal is averaged. If the average value of the signal exceeds the allowable upper limit value, it is determined that the concentration of the liquid toner has decreased, the valve 711 in FIG. 3 is opened for a predetermined time, and the toner is supplied from the toner tank 710 into the case 704. Again, signal amplification processing, low-pass filter processing, and signal value averaging are performed.

  If the average value of the signal is equal to or lower than the allowable upper limit value, it is next determined whether the average value of the signal is equal to or higher than the allowable lower limit value. If the average value of the signal is less than the allowable lower limit value, it is determined that the concentration of the liquid toner has increased, the valve 713 in FIG. 3 is opened for a predetermined time, and the carrier is replenished from the carrier tank 712 into the case 704. Again, signal amplification processing, low-pass filter processing, and signal value averaging are performed.

  In the case 704, the carrier or toner supplied by the above control is mixed with the liquid toner in the case 704 by the stirring screw 705 and the stirring roller 706. By repeating these controls, the liquid toner concentration in the case 704 is set to a predetermined value. Keep within the range.

  The liquid toner control method of the present embodiment can also be applied to the liquid toner concentration detection device described with reference to FIGS. 4 and 5B. In this case, the stirring roller 706a and FIG. It is necessary to perform sampling at a timing at which reflected light is obtained in synchronization with the rotation period of the stirring roller 706.

  The reflective photosensor 708 only needs to emit and receive light intermittently only during sampling. By performing the intermittent operation, deterioration of the reflective photosensor 708 is prevented, and the concentration of the liquid toner is continuously increased with high accuracy. It is possible to control.

  With this configuration, it is only necessary to operate the reflective photosensor intermittently only during sampling, and it is possible to prevent deterioration of the reflective photosensor and to control the liquid toner concentration continuously and accurately. It is.

  FIG. 8 is a flowchart for explaining a liquid toner concentration control method (part 3) in the liquid toner concentration detection apparatus of FIG. In this example as well, the description will be made on the assumption that the lower the liquid toner density, the larger the amount of reflected light returning to the reflective photosensor 708, and the greater the signal obtained by the reflective photosensor 708.

  A signal obtained by the reflective photosensor 708 in FIG. 3 is amplified by an amplifier circuit 720 provided in the reflective photosensor 709 or the control circuit 709, and a high-frequency component in the signal is removed by a low-pass filter.

  Next, the difference between the signal and a predetermined reference value is calculated, and the difference value is integrated within an arbitrary unit time. If the integral value exceeds the allowable upper limit value, it is determined that the concentration of the liquid toner has decreased, the valve 711 in FIG. 3 is opened for a predetermined time, and the toner is supplied from the toner tank 710 into the case 704, and again. , Signal amplification processing, low-pass filter processing, and integration of difference values within a unit time.

  If the integral value is less than or equal to the allowable upper limit value, it is next determined whether or not the integral value is greater than or equal to the allowable lower limit value. If the integrated value is less than the allowable lower limit value, it is determined that the concentration of the liquid toner has increased, the valve 713 in FIG. 3 is opened for a predetermined time, the carrier is supplied from the carrier tank 712 into the case 704, and again. Signal amplification processing, low-pass filter processing, and integration of difference values within a unit time are performed.

  In the case 704, the carrier or toner supplied by the above control is mixed with the liquid toner in the case 704 by the stirring screw 705 and the stirring roller 706. By repeating these controls, the liquid toner concentration in the case 704 is set to a predetermined value. Keep within the range.

  The liquid toner control method of the present embodiment can also be applied to the liquid toner concentration detection device described with reference to FIGS. 4 and 5B. In this case, the stirring roller 706a and FIG. It is necessary to perform the above control at a timing at which reflected light is obtained in synchronization with the rotation period of the stirring roller 706.

  In this example, the difference calculation is performed before the integral calculation. However, this difference calculation can be omitted. With such a configuration, the liquid toner density can be continuously controlled. For example, when the initial setting of the liquid toner density is performed when the image forming apparatus is activated, the liquid toner density can be accurately controlled. it can.

1 is a diagram illustrating an overall configuration of an image forming apparatus of the present invention. FIG. 2 is a partially enlarged view of a black image forming unit in FIG. 1. 1 is a diagram illustrating a liquid toner concentration detection device according to a first embodiment of the present invention. FIG. 6 is a diagram illustrating a second embodiment of the liquid toner concentration detection device of the present invention. (A) (b) It is a figure which shows Embodiment 3, 4 of the liquid toner detection apparatus of this invention. 4 is a flowchart for explaining a liquid toner concentration control method (part 1) in the liquid concentration detection apparatus of FIG. 4 is a flowchart for explaining a liquid toner concentration control method (part 2) in the liquid concentration detection apparatus of FIG. 6 is a flowchart for explaining a liquid toner concentration control method (part 3) in the liquid concentration detection apparatus of FIG.

Explanation of symbols

100: photoconductor, 110: charging roller, 111: cleaning pad, 120: static elimination lamp, 130: photoconductor cleaning blade, 131: conveying screw, 200: laser scanning optical system, 300: developing device, 301: developing roller, 302 : Secondary storage unit, 303: agitator, 304: plate-like stirring member, 305: toner supply roller, 306: toner regulating blade, 307: developing roller blade, 308: leveling roller, 309: leveling roller blade, 310: Collection port, 311: collection path, 315: primary storage section, 320: primary storage section container, 400: intermediate transfer belt, 401: drive roller, 402: cleaner backup roller, 403, 404: auxiliary roller, 405: primary transfer Roller, 410: Belt cleaner, 411: Belt cleaning blur 412: Conveying screw, 420: Secondary transfer roller cleaner, 421: Secondary transfer roller cleaning blade, 422: Conveying screw, 430: Secondary transfer roller, 501: Recording medium, 502: Pickup roller, 503: Separation pad 504: conveying roller, 505: registration roller, 506: discharge roller pair, 507, 508, 509: refeed roller pair, 600: fixing device, 601: heat roller, 602: pressure roller, 700: liquid toner Concentration detection device, 701: toner circulation channel, 702: filter, 703: toner supply channel, 704: case, 704a: opening, 705: stirring screw, 706: stirring roller, 705 (a): stirring plate, 706a: stirring Roller, 707: window member, 708: reflection type photosensor, 709: control circuit, 7 0: concentrated toner tank 711, 713: Valve, 712: carrier tank, 714: stirring roller blade 715: refresh blade 716: concentrated toner supply path, 717: carrier supply path, 720: amplifier

Claims (10)

In the detection device for detecting the concentration of the liquid toner, the developer unit communicates with the liquid toner supply channel and the liquid toner circulation channel, and further, outside the liquid toner storage case which communicates with the concentrated toner tank and the carrier tank via respective valves. A light emitting means is disposed, a member whose surface moves in the liquid toner storage case is disposed as a reflecting means, a light receiving means for receiving reflected light from the reflecting means is disposed outside the liquid toner storing case, and the reflection thereof A liquid toner concentration detection device that detects the concentration of liquid toner based on the amount of light. The curvature of the inner surface of the outer wall of the liquid toner storage case is different from the curvature of the surface of the reflecting means, and the outer wall of the liquid toner storing case near the inner surface of the outer wall of the liquid toner storing case and the surface of the reflecting means 2. The liquid toner concentration detecting means according to claim 1, wherein the light emitting means and the light receiving means are disposed in a transparent window portion. 3. The liquid toner concentration according to claim 1, wherein a slidable contact member that slidably contacts an inner surface of an outer wall of the liquid toner storage case is provided on a reflection member that is disposed in the liquid toner storage case and whose surface moves. Detection device. The reflection member on which the surface arranged in the liquid toner storage case moves serves as a stirring means for stirring the liquid toner in the liquid toner storage case. Liquid toner concentration detection device. 5. An image forming apparatus for developing an electrostatic latent image formed on a photoreceptor with liquid toner, comprising the liquid toner concentration detecting device according to claim 1. 5. The carrier liquid or the concrete when the value of the concentration detection signal obtained by the liquid toner concentration detection device according to claim 1 exceeds a predetermined upper limit value or lower limit value within a predetermined time by a predetermined number of times or more. A liquid toner concentration control method comprising: replenishing toner and maintaining the concentration of liquid toner within a predetermined range. A density detection signal obtained by the liquid toner concentration detection device according to claim 1 is detected at predetermined time intervals, and an average time or an integration time of the detection signal is set to a preset upper limit value or lower limit value. The liquid toner concentration control method is characterized by replenishing the carrier liquid or the concentrated toner to maintain the liquid toner concentration within a predetermined range. When the result obtained by integrating the concentration detection signal obtained by the liquid toner concentration detection device according to any one of claims 1 to 4 for a predetermined time exceeds a preset upper limit value or lower limit value, the toner or carrier liquid is added. A liquid toner concentration control method comprising replenishing and maintaining a liquid toner concentration within a predetermined range. A time when the concentration detection signal obtained by the liquid toner concentration detection device according to any one of claims 1 to 4 exceeds a preset setting value is calculated, and a time obtained by averaging the time at an arbitrary number of times is preset. A method for controlling the concentration of liquid toner, wherein the toner or carrier liquid is replenished when the upper limit time or the lower limit time is exceeded, and the concentration of the liquid toner is maintained within a predetermined range. A time when the concentration detection signal obtained by the liquid toner concentration detection device according to any one of claims 1 to 4 exceeds a preset set value is calculated, and a time obtained by integrating the time an arbitrary number of times is preset. A method for controlling the concentration of liquid toner, wherein the toner or carrier liquid is replenished when the upper limit time or the lower limit time is exceeded, and the concentration of the liquid toner is maintained within a predetermined range.

Images