JP2007271777A - Liquid toner concentration measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid toner concentration measuring device which copes with a plurality of kinds of liquid toner with common specification, and also has good operability. <P>SOLUTION: The liquid toner concentration measuring device 93 includes: a fixed member 97 having a first counter surface 97s; a rotating member 98 having a second counter surface 98s; a gap 94 formed by the first counter surface 97s and the second counter surface 98s; an optical sensor 95 for detecting the light transmittance of the liquid toner in the gap 94; and a toner particle concentration calculation part 96 for calculating toner particle concentration based on the detection value by the optical sensor. The rotating position of the rotating member 98 is changed in accordance with the light transmittance of the liquid toner, then, a distance of the gap 94 is changed, and the light transmittance of the liquid toner in the gap 94 is detected by the optical sensor 95. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid toner concentration measuring apparatus.

  As an electrophotographic image forming apparatus, for example, there is a liquid developing type image forming apparatus that supplies a liquid toner to a photosensitive drum on which an electrostatic latent image is formed to develop the electrostatic latent image. The liquid toner used in this image forming apparatus is a liquid in which toner particles are dispersed in a carrier liquid, and a liquid toner having a desired toner particle concentration can be obtained by adjusting the amount of toner particles and the amount of carrier liquid. Can do. The toner particle concentration of the liquid toner is measured by, for example, an optical sensor.

For example, in the liquid toner concentration measuring apparatus described in Patent Document 1, an extremely thin toner layer of several μ to several tens μm is produced, the light transmission state of the toner layer is detected by an optical sensor, and the toner particle concentration is measured. Yes.
JP 2002-278304 A

  In the liquid toner concentration measuring device described in Patent Document 1, the toner particle concentration is measured by measuring the light transmittance of a toner layer having a constant thickness. By the way, when multiple types of toner other than black toner are used, such as when the image forming apparatus supports color printing, the light transmittance of each toner is different, so it is most suitable for each toner. The toner layer thickness is different. For this reason, in an image forming apparatus using multicolor toner, the thickness of the toner layer must be changed in accordance with the color of the toner used.

  An object of the present invention is to provide a liquid toner concentration measuring apparatus that can deal with a plurality of types of liquid toner with a common specification and is easy to use. is there.

  In order to achieve the above object, a first aspect of the present invention is a concentration measuring apparatus for measuring a toner particle concentration of a liquid toner in which toner particles are dispersed in a carrier liquid, the fixing member having a first facing surface. And a liquid member formed by the rotating member having the second facing surface whose distance from the first facing surface changes depending on the rotational position, and the first facing surface and the second facing surface. A liquid sensor, a light sensor for detecting a light transmittance of the liquid toner in the gap, and a calculation means for calculating a toner particle concentration based on a detection value of the light sensor. It is a concentration measuring device.

According to this configuration, the rotational position of the rotating member having the second facing surface is changed, so that the first facing surface and the second facing surface for measuring the toner particle concentration of the liquid toner are formed. The gap distance can be changed.
For example, in the case of a liquid toner having low light transmittance such as black toner, the toner particle concentration of the liquid toner can be measured better when the gap distance is shortened. On the other hand, when measuring the density of a liquid toner having a high light transmittance such as yellow toner, the toner particles of the liquid toner can be obtained even if the gap distance is made longer than when measuring the density of a liquid toner having a low light transmittance. The concentration can be measured satisfactorily.

  In the present invention, for example, the rotational position of the rotating member is changed in order to change the gap distance according to the light transmittance of the liquid toner. As a result, the detection value (for example, output voltage or current) at the distance of the gap formed by the first facing surface and the second facing surface can be detected. As a result, the toner particle concentration of the liquid toner can be reduced. Can be measured. Therefore, the present invention can deal with a plurality of types of liquid toner with a common specification, and can deal with toners having the same configuration and different colors.

Of course, by further changing the rotational position of the rotating member, it is also possible to detect detection values at positions where the gap distance is different.
According to a second aspect of the present invention, the fixed member and the rotating member are both transparent, and the light sensor is provided on a light projecting element provided on one opposing surface side and on the other opposing surface side. A transmissive sensor having a light receiving element is preferable. For example, when a light projecting element is provided on the first facing surface side, the light emitted from the light projecting element passes through the liquid toner in the gap and is provided on the second facing surface side. Received. Then, the light receiving element outputs a detection value (for example, voltage or current) based on the received light amount to a calculation means for calculating the toner particle concentration.

According to this configuration, the configuration of the liquid toner concentration measuring device that changes the gap distance is simplified by using the transmission type sensor as described above to measure the toner particle concentration at a predetermined gap distance. be able to.
According to a third aspect of the present invention, one of the fixed member and the rotating member is transparent, and the other is a mirror surface that forms a facing surface, and the optical sensor is provided on the facing surface side of the transparent member. Further, it may be a reflective sensor having a pair of a light projecting element and a light receiving element. In this case, the light projecting element and the light receiving element included in the photosensor are arranged on either the first facing surface side or the second facing surface side.

  For example, when the second facing surface is a mirror surface, the optical sensor is provided on the first facing surface side of the transparent member. At this time, the light emitted from the light projecting element of the optical sensor passes through the liquid toner in the gap from the first facing surface side and reaches the mirror surface as the second facing surface. The light reflected by the mirror surface (reflected light) again passes through the liquid toner in the gap and is received by the light receiving element.

By adopting such an optical sensor arrangement, the structure of the liquid toner concentration measuring device can be further simplified.
Of course, the same effect can be obtained by providing the first facing surface as a mirror surface and providing the optical sensor on the second facing surface side.
Further, the second facing surface is formed by an outer peripheral surface of a cylindrical body having an eccentric rotation center as in claim 4, and an outer peripheral surface of an elliptical cylindrical body as in claim 5. The formed shape is formed by the outer peripheral surface of a polygonal cylinder as described in claim 6, and the distance from the rotation center to each outer peripheral surface is different, or the rotation center as described in claim 7. Preferably, the shape is formed on the outer surface of the distal end of the light guide path extending radially from the center, and the distance from the rotation center to the outer surface of the distal end is different. If the rotating member having the second opposing surface having such a shape is used, the distance of the gap to be measured can be easily changed by changing the rotational position of the rotating member.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view of a liquid developing type image forming apparatus including a liquid toner concentration measuring apparatus according to an embodiment of the present invention.
The image forming apparatus 1 is for forming an image on a sheet P based on predetermined image data, and includes a housing 2 and a supply / discharge for storing and transporting the sheet P provided in the housing 2. Various paper-related devices (31 to 36), an image forming unit 4 (4y, 4c, 4m, and 4k), a developing device 5 (5y, 5c, 5m, and 5k), a transfer device 6, and a fixing device 7 It has.

In the image forming apparatus 1, the paper P is taken out from the paper feed tray 31 one by one by the paper feed roller 32 according to the image forming operation. The paper P is conveyed to the secondary transfer roller 66 by the feed roller 33 and the registration roller 34.
On the other hand, an electrostatic latent image based on image data is generated in the image forming unit 4y for yellow toner, the image forming unit 4c for cyan toner, the image forming unit 4m for magenta toner, and the image forming unit 4k for black toner. A toner image is formed by applying toner from each developing device 5 (5y, 5c, 5m, or 5k) to the formed electrostatic latent image. Then, this toner image rotates in contact with the intermediate transfer driving roller 65, the intermediate transfer tension roller 64, and the intermediate transfer driven roller 63 at a position close to each primary transfer roller 62 (62y, 62c, 62m or 62k). The images are sequentially transferred onto the intermediate transfer belt 61.

Then, the toner image on the intermediate transfer belt 61 is transferred to the paper P at a position where the intermediate transfer belt 61 and the secondary transfer roller 66 are close to each other.
The residual toner that is not transferred from the intermediate transfer belt 61 to the paper P and is not transferred is removed from the intermediate transfer belt 61 by the intermediate transfer belt cleaning device 67 including the intermediate transfer belt cleaning roller 67a and the intermediate transfer belt cleaning blade 67b. It is.

The paper P on which the toner image has been transferred is sent to the fixing device 7 and heated and pressurized to fix the toner image. Then, the paper P is discharged to the discharge tray 36 by the discharge roller 35.
FIG. 2 is a schematic diagram illustrating a schematic configuration of the developing device 5, the image forming unit 4, and the stirring device 9 provided in the image forming apparatus 1. These devices 5, 4, and 9 have the same configuration regardless of the difference in toner color.

The developing device 5 includes a liquid toner storage tank 56 that stores liquid toner, a pumping roller 51, a supply roller 52, and a developing roller 53 in order to supply toner particles contained in the liquid toner to the image forming unit 4. ing. The developing device 5 applies liquid toner to the peripheral surface of the developing roller 53 by the rotational movement of the drawing roller 51 and the supply roller 52.
Further, the developing device 5 is provided with an agitation spiral 54 for agitating the liquid toner stored in the liquid toner storage tank 56 to uniformly mix the toner particles and the carrier liquid.

Further, the supply roller doctor blade 52 b is in contact with the supply roller 52, and the development roller cleaning blade 53 b is in contact with the development roller 53. The blades 52b and 53b remove unnecessary liquid toner from the peripheral surfaces of the rollers 52 and 53, respectively.
Further, the developing device 5 is provided with a liquid level sensor 55 for detecting the amount of liquid toner stored in the liquid toner storage tank 56.

The image forming unit 4 includes a cylindrical photosensitive drum 41, a static elimination device 42, a charging device 43, an exposure device 44, and a cleaning device 45 arranged so as to surround the photosensitive drum 41.
On the peripheral surface of the photosensitive drum 41, as the drum rotates, the charge is removed by the static eliminator 42, uniformly charged by the charging device 43, and exposed by the exposure device 44 based on predetermined image data. An electrostatic latent image is formed.

To the electrostatic latent image formed on the photoconductive drum 41, toner particles in the liquid toner applied on the peripheral surface of the developing roller 53 are selectively attached to form a toner image. This toner image is transferred onto the intermediate transfer belt 61 as described above.
Incidentally, the toner particles may not be transferred to the intermediate transfer belt 61 and may remain on the peripheral surface of the photosensitive drum 41. At this time, the toner is removed from the photosensitive drum 41 by the cleaning device 45 including the cleaning roller 45a and the cleaning blade 45b.

  The stirring device 9 includes a stirring tank 91, a stirring blade 92, and a liquid toner concentration measuring device 93 in order to generate liquid toner. Each toner container 81 (81y for yellow toner, cyan toner, magenta toner, or black toner is passed through a path (not shown) in the stirring tank 91 of each stirring device 9 (9y, 9c, 9m, or 9k). , 81c, 81m or 81k) and the carrier liquid tank 82 are connected (see FIG. 1). Then, a predetermined amount of the toner particles from each toner container 81 and the carrier liquid from the carrier liquid tank 82 are mixed and stirred by the stirring blade 92, whereby liquid toner is generated. The agitation tank 91 is also connected to the liquid toner storage tank 56, and the generated liquid toner flows into the liquid toner storage tank 56 side.

Incidentally, the image forming apparatus 1 is controlled so as to have a suitable toner particle concentration in order to perform good image formation. In order to maintain a suitable toner particle concentration, a liquid toner concentration measuring device 93 for measuring the toner particle concentration is provided at a position through the side wall of the stirring tank 91 of the stirring device 9.
FIG. 3 is a side sectional view of the liquid toner concentration measuring device 93.

  The liquid toner concentration measuring device 93 includes a fixing member 97 having a first facing surface 97s continuously formed on the wall surface forming the stirring tank 91, and a second member, in order to measure the toner particle concentration of the liquid toner. A rotating member 98 having an opposing surface 98s, a gap 94 formed by the first opposing surface 97s and the second opposing surface 98s, into which liquid toner enters, and the toner particle concentration of the liquid toner in the gap 94 And an optical sensor 95 that outputs a detection value.

  Both the fixing member 97 and the rotating member 98 are formed of transparent members. The optical sensor 95 includes a light projecting element 95a that emits light provided on the second facing surface 98s side, and a light receiving element 95b that receives light from the light projecting element 95a provided on the first facing surface 97s side. I have. Here, the optical sensor 95 functions as a transmissive sensor that emits light from the light projecting element 95a toward the light receiving element 95b via the transparent member and the liquid toner in the gap 94.

  Further, the second facing surface 98s is formed by an outer peripheral surface of a cylindrical body in which the rotation shaft 99 is eccentric. Thereby, by changing the rotational position of the rotating member 98, the distance of the gap 94 between the first facing surface 97s and the second facing surface 98s can be changed in a range from about 0.05 mm to about 10 mm. it can. Therefore, the optical sensor 95 can detect the light transmittance at a plurality of distances of the gap 94. The distance of the gap 94 at which the light transmittance can be detected favorably differs depending on the light transmittance (the light transmittance increases in the order of black, cyan, magenta, and yellow) due to the difference in toner color. Specifically, the distance of the gap 94 is a value in the range of about 0.05 to 1.0 mm for black toner, and a value in the range of about 1.0 to 2.0 mm for cyan toner. In the case of magenta toner, the value is in the range of about 1.5 to 3.0 mm, and in the case of yellow toner, the value is in the range of about 3.0 to 5.0 mm.

The optical sensor 95 is connected to a toner particle concentration calculation unit 96 that calculates the toner particle concentration based on the detection value from the light receiving element 95b. The toner particle concentration calculation unit 96 can measure the toner particle concentration of the liquid toner based on a detection value (for example, voltage or current) from the light receiving element 95b based on a calculation method described later.
4A and 4B are diagrams showing the characteristics of toner particle concentration-output voltage. FIG. 4A is a diagram when a cyan toner liquid toner is used, and FIG. 4B is a yellow toner liquid toner. It is a diagram when used.

  FIG. 4A shows toner particle concentration-output voltage characteristics when the distance of the gap 94 is changed to 0.1 mm, 1.5 mm, and 3.0 mm when the liquid toner of cyan toner is used. Yes. As shown in FIG. 4A, when the distance of the gap 94 is 3.0 mm, the output voltage becomes extremely low when the toner particle concentration exceeds about 30%. Therefore, good toner particle concentration-output voltage characteristics cannot be obtained.

Therefore, in the case of cyan toner, if the distance of the gap 94 is about 1.0 to 2.0 mm at a desired toner particle concentration (20%), the toner particle concentration-output voltage characteristic is stable, and the liquid is liquid. It can be seen that the toner particle concentration of the toner can be measured almost accurately.
On the other hand, FIG. 4B shows the toner particle concentration-output voltage characteristics when the distance of the gap 94 is changed to 0.1 mm, 1.5 mm, and 3.0 mm when the liquid toner of yellow toner is used. Show. As shown in FIG. 4B, it can be seen that the yellow toner exhibits good toner particle concentration-output voltage characteristics even when the distance of the gap 94 is 3.0 mm.

Therefore, in the case of yellow toner, since the light transmittance is higher than that of the above-mentioned cyan toner, even if the distance of the gap 94 is 3.0 mm or more, it seems to be suitable for measuring the toner particle concentration of the liquid toner. .
Therefore, as described above, the distance of the gap 94 at which the toner particle concentration-output voltage characteristic can be satisfactorily measured varies depending on the difference in light transmittance. It turns out that it is better to change.

  Since the distance of the gap 94 measured by the optical sensor 95 can be changed by changing the rotational position of the rotary member 98 as described above, the detection values of the optical sensor at a plurality of distances of the gap 94 (in this case) , Output voltage). Therefore, according to the present invention, it is possible to cope with the common specifications according to the light transmittance of each liquid toner (that is, the type of the liquid toner), and it is possible to cope with toners having different colors with the same configuration.

FIG. 5 is a diagram for explaining a calculation method performed by the toner particle concentration calculation unit 96 when the cyan toner liquid toner shown in FIG. 4A is used.
FIG. 5 shows the relationship between the distance of the gap 94 and the photosensor output voltage difference. This optical sensor output voltage difference is a difference from the voltage value output at the distance of the reference gap 94 (the distance at this time is 0.1 mm). The toner particle concentration calculation unit 96 stores the relationship between the distance of the gap 94 and this photosensor output voltage difference.

  As shown in FIG. 5, there is a relationship in which the slope of the graph increases when the toner particle concentration shows a high value, and the slope of the graph decreases when the toner particle concentration shows a low value. By using this relationship, the toner particle concentration of each liquid toner is increased or decreased by detecting the detection value from the optical sensor 95 by changing the distance of the gap 94 according to the light transmittance of each liquid toner. It can be measured.

  For example, in the measurement of the toner particle concentration of cyan toner, detection by the optical sensor 95 is performed within the distance range of the gap 94 as shown in FIG. Further, although not shown in the measurement of the toner particle concentration of the yellow toner having higher light transmittance than the cyan toner, the distance of the gap 94 that can be measured is a value of about 3.0 mm or more (for example, 3.0 to 5. 0 mm), detection by the optical sensor 95 is performed. In the measurement of the toner particle concentration of the black toner whose light transmittance is lower than that of the cyan toner, although not shown, a value that does not exceed about 1.0 mm in the distance of the gap 94 that can be measured (for example, 0.05 to 1). .0 mm), detection by the optical sensor 95 is performed.

  Note that the photosensor output voltage difference stored in the toner particle concentration calculation unit 96 is preferably stored as a value detected when liquid toner having a reference toner particle concentration is filled at the time of shipment. In this case, since the photosensor output voltage difference can be obtained from the distance of the gap 94 in each image forming apparatus 1, even if the sensitivity of each of the photosensors 95 provided in each image forming apparatus 1 varies. Based on the photosensor output voltage difference stored in the image forming apparatus 1, it is possible to almost accurately measure whether the toner particle concentration is higher or lower than the desired toner particle concentration.

  Further, the second facing surface is not limited to the shape (98s) formed by the outer peripheral surface of the cylindrical body in which the rotation shaft 99 is eccentric like the liquid toner concentration measuring device 93 shown in FIG. A shape (198 s) formed by the outer peripheral surface of an elliptical cylinder such as the liquid toner concentration measuring device 193 shown in FIG. 6, and a polygonal cylinder like the liquid toner concentration measuring device 293 shown in FIG. Are formed on the outer peripheral surface, and have different shapes (298 s) from the rotation shaft 299 to the respective outer peripheral surfaces, or light guide paths extending radially from the rotation shaft 399 like the liquid toner concentration measuring device 393 shown in FIG. The distance from the rotating shaft 399 to the outer surface of the tip may be a different shape (398 s). If a rotating member having such a second opposing surface is used, the distance of the gap to be measured can be easily changed by changing the rotational position of the rotating member.

  Further, as in the liquid toner concentration measuring device 493 shown in FIG. 9, one of the fixing member 497 and the rotating member 498 is transparent, and the other forms a facing surface with a mirror surface, and the optical sensor 495 is transparent. A reflective sensor having a pair of light projecting element 495a and light receiving element 495b may be provided on the opposing surface side of the member. In this case, the light projecting element 495a and the light receiving element 495b included in the optical sensor 495 can be arranged on either the first facing surface 497s side or the second facing surface 498s.

  For example, referring to FIG. 9, when second facing surface 498s is a mirror surface, optical sensor 495 is provided on the first facing surface 497s side. At this time, the light emitted from the light projecting element 495a of the optical sensor 495 passes through the liquid toner in the gap 494 from the first facing surface 497s side and reaches the mirror surface as the second facing surface 498s. Then, the light (reflected light) reflected by the mirror surface (second facing surface 498s) again passes through the liquid toner in the gap 494 and is received by the light receiving element 495b.

By adopting such an arrangement of the optical sensor 495, the structure of the liquid toner concentration measuring device 493 can be further simplified.
Of course, the same effect can be obtained by providing the optical sensor 495 in the rotating member 498 on the second facing surface 498s side with the first facing surface 497s as a mirror surface.
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments. For example, in order to measure the toner particle concentration according to the environment in which each image forming apparatus 1 is placed, it is possible to change the distance range of the gap 94 to be measured.

  In addition, various design changes can be made within the scope of matters described in the claims.

1 is a schematic view of a liquid development type image forming apparatus including a liquid toner concentration measuring apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a schematic configuration of a developing device, an image forming unit, and a stirring device provided in the image forming apparatus. It is side surface sectional drawing of a liquid toner density | concentration measuring apparatus. FIG. 4 is a diagram showing the characteristics of toner particle concentration-output voltage, where (a) is a diagram when a cyan toner liquid toner is used, and (b) is a diagram when a yellow toner liquid toner is used. FIG. FIG. 5 is a diagram for explaining a calculation method performed by a toner particle concentration calculation unit when the cyan toner liquid toner shown in FIG. 4A is used. It is side surface sectional drawing of the liquid toner density | concentration measuring apparatus of other embodiment. It is side surface sectional drawing of the liquid toner density | concentration measuring apparatus of other embodiment. It is side surface sectional drawing of the liquid toner density | concentration measuring apparatus of other embodiment. FIG. 6 is a side cross-sectional view of the liquid toner concentration measuring device when a second facing surface is formed by a mirror surface.

Explanation of symbols

93, 193, 293, 393, 493 Liquid toner concentration measuring devices 94, 194, 294, 394, 494 Gap 95, 195, 295, 395, 495 Light sensors 95a, 195a, 295a, 395a, 495a Light projecting elements 95b, 195b , 295b, 395b, 495b Light receiving element 96, 196, 296, 396, 496 Toner particle concentration calculation unit 97, 197, 297, 397, 497 Fixing member 97s, 197s, 297s, 397s, 497s First facing surface 98, 198 , 298, 398 Rotating members 98s, 198s, 298s, 398s Second facing surface 498s Second facing surface (mirror surface)
99, 199, 299, 399, 499 Rotation axis (Rotation center)

Claims (7)

A concentration measuring device for measuring a toner particle concentration of a liquid toner in which toner particles are dispersed in a carrier liquid,
A fixing member having a first facing surface;
A rotating member having a second opposing surface, the distance of which varies with the first opposing surface depending on the rotational position;
A gap into which the liquid toner formed by the first facing surface and the second facing surface enters,
An optical sensor for detecting the light transmittance of the liquid toner in the gap;
An arithmetic means for calculating a toner particle concentration based on a detection value of the optical sensor;
A liquid toner concentration measuring apparatus comprising: The fixing member and the rotating member are both transparent,
2. The liquid toner according to claim 1, wherein the optical sensor is a transmissive sensor having a light projecting element provided on one opposing surface side and a light receiving element provided on the other opposing surface side. Concentration measuring device. One of the fixed member and the rotating member is transparent, and the other is a mirror surface that creates a facing surface.
2. The liquid toner concentration measuring apparatus according to claim 1, wherein the optical sensor is a reflective sensor provided on the opposite surface side of a transparent member and having a pair of a light projecting element and a light receiving element.   4. The liquid toner concentration measuring apparatus according to claim 2, wherein the second facing surface is formed by an outer peripheral surface of a cylindrical body whose center of rotation is eccentric.   4. The liquid toner concentration measuring apparatus according to claim 2, wherein the second facing surface is formed by an outer peripheral surface of an elliptical cylindrical body.   4. The liquid toner density measurement according to claim 2, wherein the second facing surface is formed by an outer peripheral surface of a polygonal cylinder, and a distance from the rotation center to each outer peripheral surface is different. apparatus.   The said 2nd opposing surface is formed in the front-end | tip outer surface of the light guide path extended radially from a rotation center, and the distance from the said rotation center to the said front-end | tip outer surface differs, respectively. Liquid toner concentration measuring device.

Images