JP2003215900A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device which prevents a density decrease, white-base fog, scatter of toner into the device even when images with a high proportion of images are consecutively output. <P>SOLUTION: The image forming device has a two-component developing unit which stores two-component developer containing at least toner and carrier, has a circulation path for circulating the two-component developer, and is used for a developing operation in which an electrostatic latent image on a photoreceptor drum is developed to form a toner image. The image forming device also has a rotary developing device 1 for rotatably holding the two- component developing unit by means of a rotational support shaft, and a drive means for rotating the rotary developing device 1. In the circulation path of the two-component developing unit, a stir member which is rotatable in relation to the two-component developing unit is not disposed. The image forming device is provided with a toner consumption estimating means which estimates an amount of toner consumed by the two-component developing unit due to the operation of forming a toner image. As an estimated amount of consumed toner, estimated by the estimating means, increases, the frequency of the rotation of the rotary developing unit 1 by the drive means is increased. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to a multicolor or full color image forming apparatus.

[0002]

2. Description of the Related Art Various methods are used to form toner images of a plurality of colors in a full-color image forming apparatus using an electrophotographic method. Among them, a method in which a developing device for three or four colors is housed in a rotating body and sequentially rotated to face the photoconductor is advantageous in terms of downsizing of the apparatus, and various types of products are manufactured. ing.

FIG. 7 shows an example of such a full-color image forming apparatus using the rotary developing method.

In FIG. 7, a rotary developing device 101 is arranged to face a photosensitive drum 128, which is an image carrier, and develops an electrostatic latent image formed on the photosensitive drum 128 to form a toner image. To do.

The rotary developing device 101 has developing devices 102Y, 102M, 102C and 102K for forming toner images of yellow, magenta, cyan and black, respectively.
Are accommodated, and each face the photosensitive drum 128 by the rotation of the rotary developing device 102.

The formation of a full-color image is performed as follows.

By exposing the surface of the photosensitive drum 128 charged by the charger 121 with the laser 122, an electrostatic latent image is formed on the photosensitive drum 128. This latent image is first developed by the developing device 102K to obtain a black toner image.

This toner image is electrostatically transferred to the intermediate transfer drum 123. The residual toner remaining on the photosensitive drum 128 after the transfer is removed by the cleaner 126.

Here, the photosensitive drum 128 is charged again and exposed by the laser 122. During this time, the rotary developing device 101 rotates, and the photosensitive drum 128 has a developing unit 102C.
Are opposed to each other, the formed latent image is transferred to the developing device 102C.
To develop a cyan toner image. This toner image
The black toner image is transferred onto the intermediate transfer drum 123 onto which the black toner image has already been transferred. Thereafter, magenta and yellow toner images are successively developed and transferred.

The toner images of four colors transferred onto the intermediate transfer drum 123 are collected on the transfer paper 127 fed from the direction A in the figure due to the potential difference between the intermediate transfer drum 123 and the transfer conveyor belt 124. Transcribed. After that, the transfer paper 127 is conveyed to the fixing device 125 by the transfer conveying belt 124, and is heated by the fixing device 125, so that the toner image is fixed on the transfer paper 127. In this way, the transfer paper 127
The toner images of four colors are fixed and fixed on the top, and a permanent image is obtained.

The developing device 102 will be described in detail.

The two-component developing method, which uses a mixture of a non-magnetic toner and a magnetic carrier as a developer, is more advantageous than other methods in terms of image stability and durability of a developing device. It is used in the full-color image forming apparatus.

In FIG. 8, a developing device 102 accommodates a two-component developer consisting of a non-magnetic toner and a magnetic carrier, and a developing sleeve 103 as a developer carrying and conveying means rotatably arranged in the opening thereof. Have

The developing sleeve 103 is made of a non-magnetic material, rotates in the direction of the arrow in the drawing during the developing operation, and has a magnet 104 as a magnetic field generating means fixed therein. The developing sleeve 103 containing the magnet 104 carries and conveys the layer of the two-component developer whose layer thickness is regulated by the blade 105 to the developing area, and supplies the developer to the photosensitive drum 128 in the developing area facing the photosensitive drum 128. The electrostatic latent image formed on the photoconductor is developed.

After the electrostatic latent image on the photosensitive drum 128 is developed in the developing area and the toner is consumed, the two-component developer is removed from the developing area by the rotation of the developing sleeve 103.
It is transported into 02. Here, the magnet 104 has adjacent magnetic poles having the same pole, and a region (repulsive magnetic field region) in which the magnetic flux density is approximately 0 gauss is provided between the magnetic poles, and the two-component developer has the developing sleeve 10 in this repulsive magnetic field region.
3 is peeled off, and is accommodated in the developing device 102.

After that, the two-component developer that has consumed the toner is
The two-component developer in the developing device 102 is mixed and agitated, and again provided for development.

The consumed toner is replenished from the toner cartridge 109 as the toner replenishing screw 110 rotates. The replenished toner is triboelectrically charged with the carrier by being mixed and stirred with the two-component developer in the developing device 102, and provided with a predetermined charge for development.

The mixing and agitation of the two-component developer will be described. The rotatable first agitating member for agitating the two-component developer accommodated in each of the two compartments defined by the partition wall 106 in the developing device 102. 107, second stirring member 108
Is arranged and rotates by receiving drive from the developing sleeve 103 to mix and stir the two-component developer in the developing device 102, and further circulates in the developing device 102.

In a developing system using a two-component developer,
Circulating the two-component developer as described above is
This is because the toner concentration in the developer (weight percentage of toner with respect to the developer) is greatly related to the image density. For example, with respect to the axial direction of the developing sleeve 103, if there is a portion where the toner is partially consumed, only the toner density in the periphery of the developing sleeve 103 becomes lower than the other portions, and the image density is lowered. Therefore, the developer whose toner concentration has decreased must be promptly mixed and stirred with the developer in the developing device 102 and supplied to the developing sleeve 103 as a developer having a uniform toner concentration. Therefore, it is necessary not only to convey the developing device 102 in the cross-sectional direction (planar direction in FIG. 8) but also to convey the developing sleeve 103 in the rotation axis direction (perpendicular to the paper surface in FIG. 8).

Further, since the toner replenished from the toner replenishing screw 110 has almost no electric charge, it must be mixed with the two-component developer and brought into contact with the carrier to rapidly give the electric charge by frictional charging. For this reason,
The two-component developer is mixed and stirred by the rotational force of the first stirring member 107 and the second stirring member 108.

Concerning the conveyance and mixing and agitation of the two-component developer, in addition to the method shown in this prior art example, a conveying member whose feed direction is reversed is arranged coaxially and rotated, so that the center side of the shaft is rotated. A method of circulating a two-component developer on the outside and a method of arranging two stirring members vertically as in the conventional example are known.

When resin powder such as toner that easily softens enters the bearing portion of such a stirring member, agglomerates are generated by rubbing and fusion of the bearing portion is caused. Therefore, in the developing device 102 as in the conventional example, various measures have been taken to prevent the toner from entering the bearing portion. For example, there is a method in which the shaft of the stirring member is made of metal and its surface is mirror-finished, and then a bearing is formed of a resin material with high slipperiness so as to adhere to the mirror surface, and a method of applying grease or the like to the bearing portion. there were. In addition, the vicinity of the end of the shaft of the stirring member is formed of a magnetic material, and a ring-shaped magnet is arranged so as to surround the circumference of the stirring member. There is also known a method of supporting a shaft by a bearing or the like.

The conventional two-component developing device as described above has a complicated structure by disposing a rotatable stirring member inside, and is disadvantageous in comparison with other systems in terms of manufacturing cost. It has been thought that there is, but various challenges are being used to overcome the problem.

For example, Japanese Patent Application 2000-
According to the second embodiment of 196117, the “developer container 10
A developer stirring member 19 is fixedly provided inside the developing container 10. FIG. 5 shows the inside of the developing container 10Y of the developing device 2 (developing device 2Y in FIG. 4) facing the photosensitive drum 28, viewed from substantially the upper left of FIG.
The developer stirring member 19 is made up of several tens of triangular pillar-shaped members, and the triangular pillar-shaped members are arranged in three rows at substantially equal intervals in the left-right direction of FIG. By arranging the adjacent columns so that the triangular columnar members do not overlap each other when viewed from the lower left direction in FIG. 4, “two-component developer moves in the developing container 10 by rotation of the rotary developing device 1. Then, the effect of mixing and stirring the two-component developer when passing through the gap of the developer stirring member 19 can be obtained, and development can be performed with an inexpensive structure without disposing a rotatable stirring member inside. The function of stirring the agent can be obtained.

Further, for example, Japanese Patent Application No. 200 by the present applicant
According to 1-222961, "containing a two-component developer,
A two-component developing device having a rotatable developer carrier for carrying the two-component developer and transporting the two-component developer on the surface of the photoconductor, wherein the two-component developer is circulated therein. In a two-component developing device having a circulation path for rotating the two-component developing device, the two-component developing device is rotatably held by a rotation supporting shaft provided outside the two-component developing device, and at least a part of the circulation path is twisted with respect to the rotation supporting shaft. So, in that circulation path,
Required for a conventional two-component developing device by a two-component developing device in which a rotatable stirring member is not arranged with respect to the two-component developing device, and a rotary developing device and an image forming apparatus using the two-component developing device. It has been proposed to remove the developer stirring member rotating in the developing container and to obtain the stirring and circulation of the developer, which is the function of the developer stirring member, by the rotating force of the rotating body. There is.

[0026]

However, in the developing device having no rotatable stirring member as described above, when images with a high image ratio are continuously output, the toner density in the vicinity of the developing sleeve 103 is reduced. In some cases, the drop was too strong and the density dropped. Also, when replenishing the consumed toner, if the image ratio is high, the amount of replenishment also increases, and when operating in an extreme environment of temperature and humidity, or when the developer deteriorates due to long-term use. In some cases, a sufficient amount of charge cannot be applied to the replenishment toner, and white background fogging or toner scattering into the machine may occur.

Therefore, an object of the present invention is to continuously output images having a high image ratio in a low-priced full-color image forming apparatus in which a developing device having no rotatable stirring member is housed in a rotary developing device. Even in such a case, it is an object of the present invention to provide an image forming apparatus that does not cause a decrease in density, fogging on a white background, and scattering of toner into the apparatus.

[0028]

The above-mentioned problems are solved by the image forming apparatus according to the present invention.

The image forming apparatus of the present invention is provided with a circulation path for accommodating and circulating a two-component developer, and performs a developing operation of developing an electrostatic latent image on the photoconductor to form a toner image. An image forming apparatus including a two-component developing device, a rotary developing device that rotatably holds the two-component developing device by a rotary support shaft, and a drive unit that rotationally drives the rotary developing device. In the circulation path of the developing device, a stirring member that is rotatable with respect to the two-component developing device is not disposed, and the image forming apparatus uses a toner for estimating the amount of toner consumed by the two-component developing device by the toner image forming operation. An image forming apparatus comprising a consumption amount estimating means, wherein the drive means increases the frequency of rotationally driving the rotary developing device as the estimated toner consumption amount estimated by the toner consumption amount estimating means increases. A.

By adopting such a constitution, in a low-priced full-color image forming apparatus in which a developing device having no rotatable stirring member is housed in a rotary developing device, images having a high image ratio are continuously output. Even in such a case, the rotation of the rotary developing device can sufficiently stir the developer having the lowered toner concentration with the other developers in the developing device, thereby suppressing the reduction in the concentration. Further, by rotating the rotary developing device, a sufficient amount of replenishment toner can be provided with an appropriate amount of charge by sufficiently stirring it with the developer in the developing device, and white background fogging and toner scattering into the device can be suppressed. You can

Preferably, at least a part of the circulation path in the two-component developing device is twisted with respect to the rotation support shaft.

With such a structure, the circulation of the developer by the rotation of the rotary developing device can be more efficiently performed.

As the toner consumption amount estimating means, a method of detecting the exposure amount of the exposing means for exposing the photoconductor and estimating the toner consumption amount based on the result, the potential of the electrostatic latent image on the photoconductor is determined. Method of estimating toner consumption based on detection result of potential measuring means to be measured Method of estimating toner consumption based on detection result of toner concentration in two-component developer, toner adhesion of toner image after development A method of estimating the toner consumption amount based on the amount detection result, a method of estimating the toner consumption amount based on the result of detecting the toner amount replenished by the toner replenishing means, or a method combining any of the above .

The above-mentioned configuration is again described below in (1) to (7)
Shown in order.

(1) A circulation path for accommodating and circulating a two-component developer containing at least a toner and a carrier is provided to perform a developing operation of developing an electrostatic latent image on a photoconductor to form a toner image. An image forming apparatus comprising: a component developing device; a rotary developing device that rotatably holds the two-component developing device by a rotary support shaft; and a drive unit that rotationally drives the rotary developing device. A stirring member rotatable with respect to the two-component developing device is not disposed in the circulation path of the component developing device, and the toner consumed by the two-component developing device in the toner image forming operation is not provided in the image forming apparatus. A toner consumption amount estimating means for estimating the amount, and the driving means rotationally drives the rotary developing device as the estimated toner consumption amount estimated by the toner consumption estimating means increases. Image forming apparatus characterized by a higher frequency.

(2) The image forming according to the above (1), wherein at least a part of the circulation path in the two-component developing device is arranged to be twisted with respect to the rotation supporting shaft. apparatus.

(3) An exposure unit for exposing the photosensitive member according to image information, and an exposure amount detection unit for detecting an exposure amount by the exposure unit are provided, and the toner consumption amount estimation unit is for the exposure amount detection. The image forming apparatus according to (1) or (2) above, wherein the toner consumption amount is estimated based on the exposure amount detected by the means.

(4) Equipped with potential measuring means for measuring the potential of the electrostatic latent image on the photoconductor, the toner consumption estimating means displays the potential measurement result of the electrostatic latent image detected by the potential measuring means. The image forming apparatus according to any one of (1) to (3) above, wherein the toner consumption amount is estimated based on the original.

(5) The toner density detecting means for detecting the toner density in the two-component developer is provided, and the toner consumption estimating means is based on the toner density detecting result detected by the toner density detecting means. The image forming apparatus according to any one of the above (1) to (4), wherein the consumption amount is estimated.

(6) The toner adhesion amount detection means for detecting the toner adhesion amount of the toner image after being developed by the developing device is provided, and the toner consumption amount estimation means is the toner detected by the toner adhesion amount detection means. The image forming apparatus according to any one of the above (1) to (5), wherein the toner consumption amount is estimated based on the result of detection of the amount of adhesion.

(7) Toner replenishing means for replenishing at least toner to the developing device and toner replenishment amount detecting means for detecting the amount of toner replenished by the toner replenishing means are provided, and the toner consumption amount estimation is performed. The image forming apparatus according to any one of (1) to (6) above, wherein the means estimates the toner consumption amount based on the toner replenishment amount detection result detected by the toner replenishment amount detection means. .

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on examples with reference to the drawings.

[0043]

(First Embodiment) A first embodiment of the image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, the rotary developing device 1 is arranged so as to face the photosensitive drum 28 which is an image carrier, and develops the electrostatic latent image formed on the photosensitive drum 28 to form a toner image. To do.

The rotary developing device 1 has yellow,
The developing devices 2Y, 2M, 2C, and 2K for forming magenta, cyan, and black toner images are housed, and face the photosensitive drum 28 by the rotation of the rotary developing device 1.

The formation of a full-color image is performed as follows under the control of each section by a control device (not shown) built in the image forming apparatus.

By exposing the surface of the photosensitive drum 28 charged by the charger 21 with the laser 22, an electrostatic latent image is formed on the photosensitive drum 28. This latent image is first developed by the developing device 2K to obtain a black toner image.

This toner image is electrostatically transferred to the intermediate transfer drum 23. The residual toner remaining on the photosensitive drum 28 after the transfer is removed by the cleaner 26.

Here, the photosensitive drum 28 is charged again and exposed by the laser 22. During this time, the rotary developing device 1 rotates and the developing device 2C faces the photosensitive drum 28. Therefore, the formed latent image is developed by the developing device 2C to obtain a cyan toner image. This toner image is transferred onto the intermediate transfer drum 23 onto which the black toner image has already been transferred. Thereafter, magenta and yellow toner images are successively developed and transferred.

The four color toner images transferred onto the intermediate transfer drum 23 are transferred to the intermediate transfer drum 23 and the transfer / conveying belt 2.
Due to the potential difference with respect to No. 4, they are collectively transferred onto the transfer paper 27 fed from the direction A in the figure. After that, the transfer paper 27 is conveyed to the fixing device 25 by the transfer conveying belt 24, and is heated by the fixing device 25, so that the toner image is fixed on the transfer paper 27. In this way, the toner images of four colors are fixed and fixed on the transfer paper 27, and a permanent image is obtained.

Now, the developing device 2 will be described in detail.

In FIG. 2, the developing device 2 is a non-magnetic toner.
A two-component developer composed of a magnetic carrier and a developing sleeve 3 serving as a developer carrying / conveying means is rotatably disposed in the opening of the two-component developer.

The developing sleeve 3 is made of a non-magnetic material,
During the developing operation, the magnet 4 rotates in the direction of the arrow in the figure, and the magnet 4 serving as a magnetic field generating means is fixed inside thereof. The developing sleeve 3 containing the magnet 4 carries and conveys the layer of the two-component developer whose layer thickness is regulated by the blade 5 in the developing area, and supplies the developer to the photosensitive drum 28 in the developing area facing the photosensitive drum 28. The electrostatic latent image formed on the photoconductor is developed.

The two-component developer after developing the electrostatic latent image on the photosensitive drum 28 in the developing area and consuming the toner is conveyed from the developing area into the developing device 2 by the rotation of the developing sleeve 3. Here, the magnet 4 has adjacent magnetic poles having the same pole, and a region (repulsive magnetic field region) having a magnetic flux density of approximately 0 gauss is provided between the magnetic poles, and the two-component developer is in the repulsive magnetic field region. Peeled from
It is accommodated in the developing device 2. Then consumed toner 2
The component developer is mixed with the two-component developer in the developing device 2 and agitated, and again provided for development.

The consumed toner is replenished from the toner cartridge 9 to the developing device 2 as the toner replenishing screw 10 rotates. The rotation amount of the toner supply screw 10 is determined as follows. First, the photosensitive drum 2
8 forms a reference latent image on the surface, and the reference latent image is developed by the developing device 2 to form a density patch 12. This density patch 1
The reflected light amount of 2 is detected by the optical patch sensor 11 provided so as to face the photosensitive drum 28, and is compared with the reference value. Based on the comparison result, the toner concentration increase / decrease of the two-component developer in the developing device 2 is detected, and the toner supply screw 10
Is rotated for a time corresponding to the decrement, and the insufficient toner is replenished.

The replenished toner is frictionally charged with the carrier by being mixed and stirred with the two-component developer in the developing device 2, and is provided with a predetermined charge for development.

The mixing and stirring of the two-component developer will be described. Inside the developing device 2, a developer stirring member 15 is fixedly provided in the developing device 2. FIG. 3 shows the photosensitive drum 28.
2 is a view of the inside of the developing device 2 of the developing device 2 at a position facing to, viewed from substantially the upper left of FIG. The developer stirring member 15 is made up of several tens of triangular prismatic members.
They are arranged in the left-right direction of FIG. 3 at substantially equal intervals. Adjacent rows are arranged so that triangular prism-shaped members do not overlap each other when viewed from the lower left direction in FIG. When the two-component developer moves in the developing device 2 by the rotation of the rotary developing device 1, the two-component developer is mixed and stirred when passing through the gap of the developer stirring member 15, and the rotatable stirring member is placed inside. It is possible to obtain the function of stirring the developer with an inexpensive structure without disposing it.

Next, a characteristic part of the present invention will be described.

In the developing device having no rotatable stirring member as in the present embodiment, when images having a high image ratio are continuously output, the toner density near the developing sleeve 3 is excessively lowered. There was a case where the concentration was reduced. Also, when replenishing the consumed toner, if the image ratio is high, the amount of replenishment also increases, and when operating in an extreme environment of temperature and humidity, or when the developer deteriorates due to long-term use. In some cases, a sufficient amount of charge cannot be applied to the replenishment toner, and white background fogging or toner scattering into the machine may occur.

Therefore, in the present embodiment, a toner consumption amount estimating means for estimating the amount of toner consumed by the two-component developing device due to the toner image forming operation is provided, and as the estimated toner consumption amount increases, the rotation is performed. The developing device 1 is rotated many times. As a result, the two-component developer in the vicinity of the developing sleeve 3 in which the toner concentration has decreased is removed by the developing device 2.
It is possible to suppress a decrease in image density by stirring with the two-component developer therein. Further, even when a large amount of replenishment toner is sufficiently stirred with the developer in the developing device 2, an appropriate amount of charge can be imparted and white background fogging and toner scattering into the device can be suppressed.

The above operation will be described in more detail with reference to FIG.

In FIG. 4, first, an image output start instruction is given to the image forming apparatus (step S1), and the image output operation is started (step S2). Next, in step S3, the photosensitive drum 28 is charged, exposed and developed to form a black toner image.

Although step S4 is shown after step S3 in FIG. 4, it is actually performed in parallel with the exposure step of step S3. The image forming apparatus according to the present exemplary embodiment includes an exposure amount counter 13 that detects the amount of light emitted by the laser 22 as a toner consumption amount estimation unit. In the image forming apparatus of the present embodiment, the photosensitive drum 28 is negatively charged, and a voltage is applied so that the developing sleeve 3 is further moved to the negative side with respect to the portion where the negative potential is close to 0 due to the exposure, and development is performed.
The so-called "reversal development method" is used. Therefore, as the amount of light emitted from the laser 22 increases, the amount of toner attached to the photosensitive drum 28 also increases. That is, the toner consumption amount can be predicted by the light emission amount of the laser 22 detected by the exposure amount counter 13.

As a method of predicting the toner consumption amount from the exposure amount of the photosensitive drum 28, the laser 2 as in this embodiment is used.
In addition to the method of measuring the light emission amount of No. 2, various methods such as a method of calculating the image ratio at the stage of the digital signal input to the image forming apparatus and using the result can be considered.

The detection result of the exposure amount counter 13 is output as a ratio of 100% when the output image has the maximum density on the entire surface. In step S4, the detection result of the exposure amount counter 13 when the black toner image is formed is set as a variable l_cnt of a memory device (not shown) in the image forming apparatus.
Store in (K). After steps S3 and S4, the rotary developing device 1 is rotated 90 ° (step S5), and the cyan developing device 2C is opposed to the photosensitive drum 28. After that, the toner image forming operation for each color (steps S6, S9, S12), variables l_cnt (C), l_cnt (M), l_cnt
Storing operation of each exposure amount detection result in (Y) (step S
7, S10, S13) and the rotation operation of the rotary developing device 1 (steps S8, S11) are repeated to form an image of four colors.

To supplement the toner replenishing operation which is not described in FIG. 4, the density patch 12 is formed in an area outside the image area on the photosensitive drum 28 in parallel with the toner image forming operation, and the toner image density of each color is detected by the patch sensor 11. Detection is done. The result of the patch density detection is stored for each color in the memory device, and is converted into the number of rotations of the toner replenishing screw 10 by a predetermined mathematical expression or table at the time of the next toner image formation, and the insufficient toner is transferred from the toner cartridge 9 to the developing device. Replenished to 2. Further, the transfer operation and the like are performed in parallel with the image forming operation, but the description thereof is omitted here.

After step S13, the controller (not shown) uses variables l_cnt (K), l_cnt (C), l_cnt.
The one having the maximum value is selected from (M) and l_cnt (Y) and stored in the variable max_l_cnt (step S14). Next, case classification is performed according to the value of max_l_cnt (step S15, step S17). If max_l_cnt is 20% or less in step S15,
The rotary developing device 1 rotates 90 ° (1/4 rotation) (step S16) and prepares for the next toner image formation (step S2).
0). When max_l_cnt exceeds 20%, the process proceeds to step S17, and when the value is 60% or less, the rotary developing device 1 rotates 450 ° (1/4 rotation plus 1 rotation) (step S18). When the value exceeds 60%, the rotary developing device 1 rotates 810 ° (1/4).
In addition to rotation, rotation is performed twice (step S19).

That is, when the max_l_cnt value is larger than 20% and the toner consumption amount is large, the rotary developing device 1 performs 1 or 2 before the operation for preparing the next toner image formation.
Rotate more by the amount of rotation. By this rotation, the developing sleeve 3
A two-component developer with a low toner density in the vicinity is used as a developing device 2.
By mixing with other two-component developer in the mixture and stirring, a decrease in density can be suppressed.

If such an image is continuously formed,
As the amount of consumed toner increases, the density of the density patch 12 also decreases, so that the toner replenishment screw 10 also increases toner replenishment based on the detection result of the patch sensor 11. However, in the image forming apparatus according to the present exemplary embodiment, when the toner replenishment is increased, it is detected as described above, and the rotary developing device 1 is rotated a lot, so that the replenishment toner can be sufficiently stirred. . That is, a large amount of replenishment toner can be sufficiently stirred with the developer in the developing device 2 to give an appropriate amount of charge, and fogging on a white background and toner scattering into the device can be suppressed.

(Second Embodiment) The image forming apparatus according to the present embodiment has substantially the same structure as the image forming apparatus described in the first embodiment, but the image forming apparatus according to the present invention is provided in the rotary developing device 1. At least a part of the circulation path in the two-component developing device, as proposed in Japanese Patent Application No. 2001-229061, accommodates the developing device 2 in the twist direction with respect to the rotation support shaft. With this configuration, the two-component developer can be stirred in a more preferable form than the image forming apparatus of the first embodiment,
It is possible to more effectively achieve the object of the present invention to reduce the density, fogging on a white background, and suppression of toner scattering in the machine.

(Third Embodiment) The image forming apparatus of this embodiment has substantially the same structure as the image forming apparatus described in the first and second embodiments, but the photosensitive drum is used as a toner consumption amount estimating means. It is characterized in that the detection result of the potential sensor 14 for measuring the potential of the electrostatic latent image on 28 is used.

In FIG. 5, the potential sensor 14 faces the surface of the photosensitive drum 28 and is located between the exposure position of the laser 22 and the developing position of the developing device 2. As a result, the stability of the density can be obtained by detecting and controlling the latent image potential on the photosensitive drum 28. Potential sensor 1 as in this embodiment
In the image forming apparatus provided with No. 4, the image ratio can be detected to some extent by measuring the latent image potential during image formation, and thus it can also be used as a toner consumption amount estimating unit.

(Fourth Embodiment) The image forming apparatus of the present embodiment has substantially the same structure as the image forming apparatus described in the first embodiment, but the image forming apparatus in the developing device 2 is used when estimating the toner consumption amount. It is characterized in that the result of toner density detection is used.

As a method of directly detecting the toner concentration of the two-component developer in the rotary developing device 1, the two-component development in the developing device 2 by the optical fiber as used in the color laser copiers CLC1 and CLC500 by the applicant is carried out. A method of detecting the amount of reflected light of the agent can be mentioned. According to this method, even if the developing device 2 moves with respect to the main body of the image forming apparatus due to the rotation of the rotary developing device 1, the optical fiber cross section of the main body side and the optical fiber cross section of the developing device 2 side when returning to the developing position. The toner concentration can be detected by making the above coincide with each other and transmitting and receiving an optical signal in a non-contact manner. Even in the image forming apparatus of this embodiment, the toner density is detected by this method.

As a concrete method, Japanese Patent Publication No. 08-01
Japanese Patent No. 4730 has the following description. “FIG. 5” in the reference is cited as FIG. 6 of the present case.

The outline of the developer concentration detecting device shown in FIG. 5 is roughly classified into the developer of each color of yellow (Y), magenta (M), cyan (C) and black (B). And four developing unit side detection units 30, one for each of the four developing units that individually store
Each of these is attached to the side plate of the image forming apparatus main body at a position where it does not come into contact with the developing unit side detection unit 30.
And a unit 40 for detecting outside the developing device.

However, since the developing unit side detection unit 30 has the same structure,
Here, the unit 3 attached to the developing device 25Y
0 and the outside-developing-device detection unit 40 will be described. As is apparent from FIG. 5, the developing device side detection unit 30 has a vertical cross section of a substantially delta shape, and the developing device 2 has a substantially delta shape.
5Y, a unit support body is provided near the upper part of the developing sleeve 251Y so as to face the projecting portion, and has a substantially V shape along the two long sides of the unit support body. Two optical fibers attached to 3
2, 34 and a reflection mirror 31 disposed near a contact point where these two optical fibers 32, 34 contact each other.
And a developer concentration detection window 33 formed in a position near the position where the reflection mirror 31 of the unit support is disposed and at a position facing the outer peripheral surface of the developing sleeve 251Y. On the other hand, the outside-developing unit detection unit 40 is attached to the main body of the image forming apparatus so as to face the developing-unit-side detection unit 30 of the developing unit stopped at the developing position at the above-described developing position. A support body 41, a light source 42 attached to a portion of the support body 41 facing the end of the optical fiber 32, and a support body 41.
An opening 43 formed at a portion facing the end of the optical fiber 34 and an axial extension extending between the end of the optical fiber 34 and the opening 43 and the support 41 are provided in a predetermined manner. A light receiving element 45 such as a photodiode arranged at a distance, the support 41 and the light receiving element 45.
The color separation filter 44 is configured to move up / down in the space between the color separation filter 44 and the solenoid 49 for moving the color separation filter 44 up / down. The above-mentioned configuration will be described below in more detail. That is, the light source 42 emits white light as the irradiation light, and the optical fiber 32 receives the white light emitted from the light source 42 and transmits the white light to the reflection mirror 31. Has become. The reflection mirror 31 receives the white light transmitted through the optical fiber 32, reflects the white light, and illuminates the developer concentration detection window 33. At the same time, the reflection mirror 31
The light that has entered through the developer concentration detection window 33 is received, reflected, and given to the optical fiber 34. The developer concentration detection window 33 described above is composed of a dichroic mirror that reflects the spectral energy light A shown in FIG. 5 and transmits the spectral energy light B different from the spectral energy light A, In the white illumination light, for example, a visible light component having a wavelength of about 700 nm or less is reflected and a near infrared light component having a wavelength of about 700 nm or more is transmitted. At the same time, the developer concentration detection window 33 transmits near-infrared light components having a wavelength of about 700 nm or more that are transmitted through the detection window 33, collide with the developer on the developing sleeve 251Y, and are reflected by the developer. It is configured to be transmitted and directly applied to the reflection mirror 31 or the optical fiber 34. The optical fiber 34
Is the reflection mirror 31 or the developer concentration detection window 3
3 receives the near-infrared light component having a wavelength of about 700 nm or more and transmits it, and the infrared light component is transmitted through the opening 4
3. It is given to the light receiving element 45 through the color separation filter 44. At the same time, the optical fiber 34
Is a light receiving element in the same manner as described above by receiving the spectral energy light A reflected by the surface of the dichroic mirror without passing through the dichroic mirror through the reflection mirror 31 or directly. It is supposed to be given to 45. The color separation filter 44 described above is integrally formed by a filter member 47 having an area sufficient to cover the light receiving portion of the light receiving element 45 and a filter member 48 having an area substantially the same as the filter member 47. The filter member 47 is configured to transmit only a visible light component having a wavelength of about 700 nm or less reflected by the surface of the dichroic mirror, and the visible light component is used as a reference light γ. On the other hand, the filter member 48 transmits only the near-infrared light component having a wavelength of about 700 nm or more transmitted through the dichroic mirror, and the filter member 48 transmits the near-infrared light component. The infrared light component is applied to the light receiving element 45 as the developer concentration detection light d. Further, the color separation filter 44 described above will be explained.
As described above, 4 is configured to move up / down in the direction of the arrow in FIG. 5 by the solenoid 49 and a spring (not shown). At the initial stage of development, the light receiving portion of the light receiving element 45 and the opening portion are connected. The filter member 47 is provided on the connecting axis.
To make the reference light γ incident on the light-receiving element 45, and at the latter stage of development, the filter member 48 is arranged on the axis connecting the light-receiving portion of the light-receiving element 45 and the opening portion. d is incident on the light receiving element 45. The above-mentioned light receiving element 45 has the developer concentration detection light d whose light amount increases as the developer concentration of each developing device increases, while the light amount decreases as the developer concentration decreases.
Is incident through the filter member 48, an electric signal corresponding to the incident light amount is output as a developer concentration detection signal, and the reference light r is transmitted through the filter member 47.
When is incident, an electric signal corresponding to the light amount of the reference light r is output as a reference signal for detecting the deterioration of the light source 42 and the dirt of the detection optical system. When the image ratio is high, the toner density in the developing device 2 is also greatly changed. Therefore, when the detection result is larger than a predetermined value, the rotation amount of the rotary developing device 1 is increased to achieve the object of the present invention. To be done. Further, since the toner concentration detection result is reflected on the rotation speed of the toner supply screw 10 as described above, it is possible to estimate the toner consumption amount by detecting this rotation speed.

(Fifth Embodiment) The image forming apparatus of this embodiment has substantially the same structure as the image forming apparatus described in the first embodiment, but the photosensitive drum 2 is used when estimating the toner consumption amount.
This is the result of using the detection result of the patch density on No. 8 above. As in the third embodiment, the output signal of the patch sensor 11 also greatly changes in accordance with the image ratio, so that it is possible to estimate the toner consumption amount. Further, the patch sensor 11 does not necessarily have to be installed so as to face the photosensitive drum 28. For example, the patch sensor 11 may face the intermediate transfer drum 23 and detect the reflected light amount of the density patch 12 transferred to the intermediate transfer drum 23. .

Although the image forming apparatus of the present invention has been described in accordance with the above five embodiments, the present invention is not necessarily limited to the configuration as described above, and various configurations can be made within the scope intended by the present invention. It is possible to take.

For example, the developing device 2 is provided with a magnet 4 having a repulsive magnetic field region, but the magnetic field from the developing sleeve 3
The peeling of the component developer does not have to use the magnetic force, but may be a scraping member or the like which is substantially in contact with the developing sleeve 3.

For example, the rotation frequency of the rotary developing device 1 and the threshold value for determining the rotation frequency described with reference to FIG. 4 can be determined in accordance with various forms of the image forming apparatus, or can be determined by, for example, a temperature / humidity detection result. The threshold value may be changed. Further, when the predetermined relationship between the rotation direction of the rotary developing device 1 and the circulating direction of the two-component developer in the developing device 2 is not required as in the first embodiment, the rotary developing device 1 is rotated in the reverse direction. You can also let them do it.

It is also possible to improve the detection accuracy by combining some of the toner consumption estimation methods mentioned above or by making a determination based on the history of the detection results of the respective estimation means.

[0083]

As described above, the image forming apparatus of the present invention is provided with the circulation path for accommodating and circulating the two-component developer, and the electrostatic latent image on the photoconductor is developed to form the toner image. Image formation including a two-component developing device for performing a developing operation of performing a rotation operation, a rotary developing device that rotatably holds the two-component developing device by a rotation support shaft, and a drive unit that rotationally drives the rotary developing device. In the apparatus, a stirring member rotatable with respect to the two-component developing device is not arranged in the circulation path of the two-component developing device, and the two-component developing device is consumed by the toner image forming operation in the image forming apparatus. A toner consumption amount estimating means for estimating the amount of toner to be used, and as the estimated toner consumption amount estimated by the toner consumption amount estimating means increases, the frequency of driving the rotational developing device by the driving means increases. The image forming apparatus according to claim.

By adopting such a structure, a low-priced full-color image forming apparatus in which a developing device having no rotatable stirring member is housed in a rotary developing device and continuously outputs images with a high image ratio. Even in such a case, the rotation of the rotary developing device can sufficiently stir the developer having the lowered toner concentration with the other developers in the developing device, thereby suppressing the reduction in the concentration. Further, by rotating the rotary developing device, a sufficient amount of replenishment toner can be provided with an appropriate amount of charge by sufficiently stirring it with the developer in the developing device, and white background fogging and toner scattering into the device can be suppressed. You can

[Brief description of drawings]

FIG. 1 is a diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating in detail the developing device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating in detail the developing device according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation of the image forming apparatus according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a diagram illustrating a conventional image forming apparatus.

FIG. 8 is a diagram illustrating in detail a developing device of an image forming apparatus of a conventional example.

[Explanation of symbols]

1 rotation developing device 2 developer 2Y, 2M, 2C, 2K developing device 3 Development sleeve 4 magnets 5 blades 9 toner cartridge 10 Toner supply screw 11 patch sensor 12 density patch 13 Exposure counter 14 Potential sensor 15 Developer stirring member 21 Charger 22 laser 23 Intermediate transfer drum 24 Transfer conveyor belt 25 fixer 26 Transfer paper 28 Photosensitive drum (image carrier) 101 rotary developing device 102 rotary developing device (developing device) 102Y, 102M, 102C, 102K developing unit 103 Development sleeve 104 magnet 105 blade 106 bulkhead 107 First stirring member 108 Second stirring member 109 toner cartridge 110 Toner supply screw 121 Charger 122 laser 123 Intermediate transfer drum 124 Transfer Conveyor Belt 125 fixer 126 cleaner 127 transfer paper

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/14 G03G 15/08 507Z F term (reference) 2H027 DA02 DA04 DA07 DA10 DB01 DD01 DD07 DE07 DE10 EA06 EC09 ED10 EE02 2H030 AD12 AD16 AD17 BB24 BB38 BB42 BB63 2H077 AA02 AA35 AB02 AB06 AB12 AD06 BA01 BA09 DA04 DA05 DA08 DA10 DA12 DA24 DA42 DA47 DA63 DB03 DB14 EA01 GA13

Claims (7)

[Claims] 1. A two-component developer for carrying out a developing operation of forming a toner image by developing an electrostatic latent image on a photoconductor, comprising a circulation path for accommodating and circulating a two-component developer containing at least a toner and a carrier. An image forming apparatus comprising: a developing device; a rotary developing device that rotatably holds the two-component developing device by a rotary support shaft; and a drive unit that rotationally drives the rotary developing device, wherein the two-component In the circulation path of the developing device, a stirring member that is rotatable with respect to the two-component developing device is not arranged, and the image forming apparatus has a toner amount consumed by the two-component developing device due to a toner image forming operation. A toner consumption amount estimating unit for estimating the toner consumption amount, and the driving unit rotationally drives the rotary developing device as the estimated toner consumption amount estimated by the toner consumption amount estimating unit increases. Image forming apparatus characterized by a higher degree. 2. The image forming apparatus according to claim 1, wherein at least a part of the circulation path in the two-component developing device is arranged to be twisted with respect to the rotation support shaft. 3. An exposure unit for exposing the photosensitive member according to image information, and an exposure amount detection unit for detecting an exposure amount by the exposure unit, wherein the toner consumption amount estimation unit is the exposure amount detection unit. The image forming apparatus according to claim 1 or 2, wherein the toner consumption amount is estimated based on the detected exposure amount of. 4. A potential measuring means for measuring the potential of the electrostatic latent image on the photoconductor is provided, and the toner consumption amount estimating means also includes a potential measurement result of the electrostatic latent image detected by the potential measuring means. 4. The image forming apparatus according to claim 1, wherein the toner consumption amount is estimated. 5. A toner density detecting means for detecting a toner density in the two-component developer, wherein the toner consumption amount estimating means consumes toner based on a toner density detection result detected by the toner density detecting means. The image forming apparatus according to claim 1, wherein the amount is estimated. 6. A toner adhesion amount detecting means for detecting a toner adhesion amount of a toner image after being developed by the developing device, wherein the toner consumption amount estimating means detects the toner adhesion amount detected by the toner adhesion amount detecting means. The image forming apparatus according to claim 1, wherein the toner consumption amount is estimated based on the amount detection result. 7. A toner replenishment unit for replenishing at least toner to the developing device, and a toner replenishment amount detection unit for detecting the amount of toner replenished by the toner replenishment unit. 7. The image forming apparatus according to claim 1, wherein the toner consumption amount is estimated based on a toner replenishment amount detection result detected by the toner replenishment amount detection means.