JP2007271776A - Liquid toner concentration measuring device and liquid toner concentration measuring method using the 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 gap 94 formed by a first counter surface member 97a and a second counter surface member 97b; an optical sensor 95 for detecting the light transmittance of the liquid toner in the gap 94; and a toner particle concentration calculating part 96 for calculating the toner particle concentration, based on the detection value by the optical sensor 95. Regarding the gap 94, the thickness as a distance of the gap 94 is varied from the thicker part to the thinner part. The optical sensor 95 includes a moving device 98 that moves the optical sensor 95 along the thickness changing direction of the gap 94 in order to detect the light transmittance of the liquid toner at the desired thickness in the gap 94. The moving device 98 moves the optical sensor 95 in accordance with the light transmittance of the liquid toner, so that the thickness of the gap 94 to be measured by the optical sensor 95 is changed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid toner concentration measuring apparatus and a liquid toner concentration measuring method using the 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.
Another object of the present invention is to provide a method for satisfactorily measuring the concentration of liquid toner using the liquid toner concentration measuring apparatus.

  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, wherein the first opposing surface member and the second toner are measured. The toner particle concentration is calculated on the basis of a gap formed by the opposite surface member, the gap into which the liquid toner enters, an optical sensor for detecting the light transmittance of the liquid toner in the gap, and a detection value of the optical sensor. The gap is changed from a thick portion to a thin portion, which is the gap interval, and the light transmittance of the liquid toner at a desired thickness in the gap is detected. Thus, the liquid toner concentration measuring apparatus includes a moving device that moves the optical sensor along a change direction of the thickness of the gap.

According to this configuration, the moving device that moves the optical sensor along the change direction of the gap thickness can change the thickness in the gap to be measured according to the light transmittance of the toner.
For example, in the case of a liquid toner having a low light transmittance such as a black toner, the toner particle concentration of the liquid toner can be measured more favorably by reducing the thickness of the gap. 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 thickness of the gap is increased compared to the case of measuring the density of a liquid toner having a low light transmittance. The concentration can be measured satisfactorily.

In the present invention, since the optical sensor is provided in the moving device, as described above, the optical sensor can be moved to a desired position, and detection values (for example, output voltage and Current) can be detected. 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.
According to a second aspect of the present invention, the gap may be formed so that the thickness changes stepwise. In this case, since the area having the predetermined gap thickness to be measured is wide, even if there is some blurring in the movement of the moving device that moves the optical sensor, the light transmittance of the liquid toner at the predetermined gap thickness can be reduced. It can be detected well.

  According to a third aspect of the present invention, the first facing surface member and the second facing surface member are both transparent, and the light sensor includes a light projecting element provided on one facing surface member side, A transmissive sensor having a light receiving element provided on the other facing surface member side is preferable. In this case, the light emitted from the light projecting element of the optical sensor passes through the first opposing surface member, the liquid toner in the gap, and the second opposing surface member in order, and is received by the light receiving element of the optical sensor. 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, for example, since the moving device that moves the optical sensor is provided separately from the liquid toner intrusion path, it is possible to prevent problems such as adhesion and solidification of toner particles. Therefore, it is possible to provide an easy-to-use toner concentration measuring device.
According to a fourth aspect of the present invention, one of the first facing surface member and the second facing surface member is transparent, and the other forms a facing surface with a mirror surface. A reflective sensor having a pair of a light projecting element and a light receiving element may be provided on the opposite surface member side. In this case, the light emitted from the light projecting element of the optical sensor reaches the first opposing surface member, the liquid toner in the gap, and the mirror surface as the second opposing surface member, and is reflected. Then, the reflected light reflected there passes through the liquid toner in the gap and the first opposing surface member in order, and is received by the light receiving element of the optical sensor. 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, for example, since the moving device that moves the optical sensor is provided separately from the liquid toner intrusion path, it is possible to prevent problems such as toner particles adhering and solidifying. An easy-to-use toner concentration measuring apparatus can be obtained.
Further, in this configuration, the light projecting element and the light receiving element included in the optical sensor are located on one opposing surface member side with respect to the gap, and the light path is doubled by the mirror surface. As a result, space saving of the toner concentration measuring device can be achieved.

  In order to achieve the above object, a fifth aspect of the present invention is a liquid toner concentration measuring method using the liquid toner concentration measuring apparatus according to any one of the first to fourth aspects, wherein the first opposed surface is used. Light transmission at a desired thickness of the liquid toner that has entered the gap is a gap formed by the member and the second facing surface member, and the gap between them is changed from a thick part to a thin part. The degree of toner is detected by an optical sensor, the toner particle concentration is calculated by an arithmetic means based on the detection value of the optical sensor, and the optical sensor is moved by a moving device along the change direction of the thickness of the gap. The liquid toner concentration measurement method is characterized in that the toner particle concentration is measured by obtaining at least two outputs at different thicknesses.

According to this method, the moving device that moves the optical sensor along the change direction of the gap thickness changes the thickness of the gap measured by the optical sensor according to the light transmittance of each liquid toner, and the liquid toner The toner particle concentration can be measured.
For example, in the measurement of liquid toner having a low light transmittance, detection by the optical sensor is performed in a range where the thickness is thinner than the thickness of the gap measured in the liquid toner having a high light transmittance.

  In this way, the moving device moves the optical sensor to the position of the thickness of the gap in order to output the detection value of the optical sensor satisfactorily according to the light transmittance of the toner (that is, the type of liquid toner). Can do. Therefore, this method can cope with a plurality of types of liquid toner with a common specification.

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 development 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 onto the paper P from the intermediate transfer belt 61 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 toner particles and the carrier liquid are mixed evenly by stirring the liquid toner stored in the liquid toner storage tank 56 by the stirring spiral 54 provided in the developing device 5.

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.

By the way, 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, the stirring tank 91 is provided with a liquid toner concentration measuring device 93 for measuring the toner particle concentration.
FIG. 3 is a side sectional view of the liquid toner concentration measuring device 93.
The liquid toner concentration measuring device 93 includes first and second opposing surface members 97a and 97a continuously formed on the wall surface forming the stirring tank 91 in order to measure the toner particle concentration of the liquid toner generated by the stirring device 9. Two opposing surface members 97b, a gap 94 formed by the first opposing surface member 97a and the second opposing surface member 97b, into which liquid toner enters, and the light transmittance of the liquid toner in the gap 94 is detected. And an optical sensor 95.

Both the first facing surface member 97a and the second facing surface member 97b are formed of transparent members. In addition, due to these facing surface members 97a and 97b, the thickness of the gap 94 is changed from a thin portion (for example, a thickness of 0.05 mm) to a thick portion (for example, a thickness of 10 mm).
The optical sensor 95 includes a light projecting element 95a that emits light, and a light receiving element 95b that receives light from the light projecting element 95a. Here, the optical sensor 95 functions as a transmissive sensor that emits light from the light projecting element 95a provided on the first facing surface member 97a side to the light receiving element 95b provided on the second facing surface member 97b side. is doing.

  Further, the optical sensor 95 is provided with a moving device 98 that moves along the changing direction of the thickness of the gap 94 in order to detect the light transmittance of the liquid toner at a desired thickness in the gap 94. By this moving device 98, the optical sensor 95 is positioned to detect the light transmittance at a predetermined thickness of the gap 94. The position at which the light transmittance in the thickness of the gap 94 can be detected well 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 thickness 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.

Further, 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 level of 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 three thicknesses of the gap 94 are changed to 0.1 mm, 1.5 mm, and 3.0 mm when liquid toner is used as cyan toner. ing. As shown in FIG. 4A, when the thickness of the gap 94 becomes 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 thickness 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 constant, and the liquid toner It can be seen that the toner particle concentration can be measured almost accurately.
On the other hand, FIG. 4B shows toner particle concentration-output voltage characteristics when the three thicknesses of the gap 94 are changed to 0.1 mm, 1.5 mm, and 3.0 mm when liquid toner is used as yellow toner. Is shown. As shown in FIG. 4B, it can be seen that the yellow toner exhibits good toner particle concentration-output voltage characteristics even when the gap 94 has a thickness of 3.0 mm.

Therefore, since the yellow toner has higher light transmittance than the above-described cyan toner, it seems that it is suitable for the measurement of the toner particle concentration of the liquid toner even if the thickness of the gap 94 is 3.0 mm or more.
Therefore, as described above, the thickness of the gap 94 at which the toner particle concentration-output voltage characteristics can be satisfactorily measured varies depending on the difference in light transmittance. Therefore, the thickness of the gap 94 depends on the color (type) of the liquid toner. It turns out that it is better to change.

  In the present invention, since the optical sensor 95 is provided in the moving device 98, the optical sensor 95 can be moved to a predetermined position. As a result, the detection values (in this case, the positions of the gaps 94 having different thicknesses) Output voltage) can be detected. 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.

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 thickness of the gap 94 and the optical sensor output voltage difference. This optical sensor output voltage difference is a difference from the voltage value output at the thickness of the gap 94 as a reference (the thickness of the gap 94 at this time is 0.1 mm). The toner particle concentration calculation unit 96 stores the relationship between the thickness 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, it is possible to measure whether the toner particle concentration of each liquid toner is increased or decreased by changing the thickness of the gap 94 to be measured according to the light transmittance of each liquid toner. .

  For example, in the measurement of the toner particle concentration of cyan toner, detection by the optical sensor 95 is performed with the thickness of the gap 94 as shown in FIG. Further, when measuring the toner particle concentration of yellow toner having higher light transmittance than cyan toner, the thickness 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), and the optical sensor Detection by 95 is performed. On the other hand, in the measurement of the toner particle concentration of the black toner whose light transmittance is lower than that of the cyan toner, the thickness of the gap 94 that can be measured is a value not exceeding about 1.0 mm (for example, 0.05 to 1.0 mm). Detection by the sensor 95 is performed.

As described above, the moving device 98 has an optical sensor at the position of the thickness of the gap 94 that can output the detection value of the optical sensor 95 satisfactorily according to the light transmittance of the toner (that is, the type of liquid toner). 95 can be moved. As a result, it is possible to deal with a plurality of types of liquid toner with a common specification.
Note that the photosensor output voltage difference stored in the toner particle concentration calculation unit 96 preferably stores a value detected when liquid toner having a reference toner particle concentration is filled at the time of shipment. In this case, the difference in the photosensor output voltage of the desired toner particle concentration in each image forming apparatus 1 is obtained. Therefore, even if the optical sensor 95 provided in each image forming apparatus 1 varies in sensitivity, this image formation is performed. Based on the photosensor output voltage difference stored in the apparatus 1, it is possible to measure whether the concentration is higher or lower than the desired toner particle concentration.

In addition, since the moving device 98 for moving the optical sensor 95 is provided separately from the liquid toner intrusion portion, problems such as toner particles adhering and solidifying can be prevented, and as a result, it is easy to use. The toner concentration measuring device 93 can be used.
As in the toner concentration measuring device 193 shown in FIG. 6, the gap may be formed so that the thickness changes stepwise. In this case, even if there is some blurring in the movement of the moving device 198 that moves the optical sensor 195, the area having the thickness of the predetermined gap 194 to be measured is wide, so that the liquid toner at the predetermined gap 194 thickness is large. The light transmittance can be detected well.

  Further, in the liquid toner concentration measuring device 293 shown in FIG. 7, the first opposing surface member 297a is transparent, the second opposing surface member 297m forms an opposing surface with a mirror surface, and the optical sensor 295 includes A reflective sensor 295 that is provided on the one opposing surface member 297a side and forms a pair of the light projecting element 295a and the light receiving element 295b may be used. According to this configuration, these elements included in the optical sensor 295 are on the first facing surface member 297a side with respect to the gap, and the light path is doubled by the second facing surface member 297m (mirror surface). Therefore, the spread of the gap 294 in the thickness direction can be suppressed, and as a result, space saving of the liquid toner concentration measuring device 293 can be achieved.

  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. In the above-described embodiment, the optical sensor 95 provided in the moving device 98 is moved. However, for example, the stirring tank 91 provided with the first opposing surface member 97a and the second opposing surface member 97b is optically connected. It is good also as a form which moves with respect to the sensor 95. FIG. Further, the thickness of the gap 94 to be measured can be changed according to the environment in which the individual image forming apparatus 1 is placed.

  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 developing type image forming apparatus including a liquid toner concentration measuring device 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 which concerns on other embodiment. FIG. 5 is a side sectional view of a liquid toner concentration measuring apparatus according to still another embodiment.

Explanation of symbols

93, 193, 293 Liquid toner concentration measuring devices 94, 194, 294 Gaps 95, 195, 295 Light sensors 95a, 195a, 295a Light projecting elements 95b, 195b, 295b Light receiving elements 96, 196, 296 Toner particle concentration calculating section 97a, 197a, 297a First opposing surface member 97b, 197b Second opposing surface member 297m Second opposing surface member (mirror surface)
98, 198, 298 mobile device

Claims (5)

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 gap formed by the first facing surface member and the second facing surface member, into which the liquid toner enters,
An optical sensor for detecting the light transmittance of the liquid toner in the gap;
Comprising calculating means for calculating toner particle concentration based on the detection value of the photosensor,
The gap is changed from a thick part to a thin part, which is a gap interval,
A moving device that moves the optical sensor along a change direction of the thickness of the gap so as to detect light transmittance of the liquid toner at a desired thickness in the gap;
A liquid toner concentration measuring apparatus comprising:   2. The liquid toner concentration measuring apparatus according to claim 1, wherein the gap is formed so that its thickness changes stepwise. The first opposing surface member and the second opposing surface member are both transparent,
3. The transmissive sensor having a light projecting element provided on one opposing surface member side and a light receiving element provided on the other opposing surface member side, wherein the optical sensor is a transmissive sensor. The liquid toner concentration measuring apparatus as described. One of the first facing surface member and the second facing surface member is transparent, and the other is a mirror surface that creates a facing surface.
3. The liquid toner concentration measuring apparatus according to claim 1, wherein the optical sensor is a reflective sensor provided on one opposing surface member side and having a pair of a light projecting element and a light receiving element. . A liquid toner concentration measurement method using the liquid toner concentration measurement device according to claim 1,
Desirable liquid toner that has entered the gap formed by the first facing surface member and the second facing surface member and has a gap that is changed from a thick portion to a thin portion. The light transmittance at the thickness of the toner is detected by a light sensor, the toner particle concentration is calculated by the calculation means based on the detection value of the light sensor, and the light sensor is moved along the direction of change in the thickness of the gap. A liquid toner concentration measurement method, wherein the toner particle concentration is measured by moving with an apparatus and obtaining at least two outputs of portions having different thicknesses.

Images