JPH08211729A - Image forming device - Google Patents

Abstract

PURPOSE: To obtain an image forming device capable of maintaining development conditions under which optimum development can be obtained and capable of ensuring stable image quality over a long period of time. CONSTITUTION: The image forming device holds two-component developer, comprising a mixture of toner and carrier, on a developer carrier and develops an electrostatic latent image, formed on an image carrier opposite a developer layer on the developer carrier, by sticking the toner to it. The device is equipped with a means 34 for detecting an amount of the developer carried to a developing area, a data storage means 30 for storing a signal from the means 34, and a development bias control means 32 for controlling an output image by varying a development bias based on the data in the data storage means 30.

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 which develops an electrostatic latent image on an image bearing member by using a two-component type developer, and more particularly to a developing device. The present invention relates to a technique for controlling an output image by changing image forming conditions according to the amount of developer conveyed to an area.

[0002]

2. Description of the Related Art In recent years, colorization has progressed in electrophotographic apparatus, and various recording methods are known, and one of them is a superimposing development / collective transfer method. The overlapping development and batch transfer method, by developing superimposed the image bearing successively a plurality of colors image on member such as a photosensitive member to form a plurality of color images in the image bearing member, of the plurality of colors A color image is obtained by batch-transferring a color image onto a recording sheet. This method requires only one image bearing member such as a photoconductor drum and does not require a transfer drum, so that the apparatus can be downsized.

When the normal contact developing method is used in the above-mentioned overdevelopment / batch transfer method, the problem that the developed toner image has a developing brush mark, which is peculiar to the contact developing method, and the image carrying by the preceding developing step is carried out. When the toner image developed on the body passes through the next development step, it is scraped from the image carrier, and the density of the image in the former stage decreases, or the scraped toner develops in the developing unit in the latter stage. There is a problem in that the life of the developer at the subsequent stage is remarkably reduced by being mixed in the developer, and further, a problem such as color mixing occurs.

Therefore, in the overlap development / collective transfer method, how to carry out the subsequent development without disturbing or scraping off the toner image already developed on the image carrier is a very important issue. Therefore, various proposals regarding the developing method have been made.

Among them, a non-contact developing method has been proposed, which is disclosed in Japanese Patent Publication No. 2-4903, in which a magnetic brush is not brought into contact with an image portion. Japanese Patent Publication No. 2-490
The technique disclosed in Japanese Patent Laid-Open No. 3 is a technique for forming an electrostatic latent image on a drum-shaped recording medium having photoconductivity and a plurality of electrostatic latent image forming means for visualizing the electrostatic latent image. In the electrophotographic recording apparatus composed of the developing means, the gap between the surface of the magnetic developer and the surface of the drum-shaped recording medium, which is adhered and conveyed on the outer peripheral surface of the conveying rotary member of the developing means, is set to 0.05 to
By maintaining the range of 0.5 mm and applying an alternating electric field, the overlap developing method is enabled.

As described above, the non-contact developing method is suitable for the superimposing image method since there is no contact of the developer and therefore there is no reduction in image density, mixing or color mixture due to scraping due to contact of the developer layer. It has excellent characteristics. However,
In the non-contact developing method as described above, since the thickness of the developer layer on the developer carrier varies, the striped development unevenness in the image finally obtained on the recording sheet may cause the conveyance of the recording sheet. There is a problem that it occurs remarkably repeatedly in the direction.

In order to prevent this uneven development, Japanese Patent Laid-Open No.
Techniques such as those disclosed in JP-A-208957 and JP-A-5-333685 have been proposed. The developing device disclosed in Japanese Unexamined Patent Publication (Kokai) No. 4-208957 is not in contact with the electrostatic latent image on the photoconductor under the bias applied to the roller member that supplies the developer to the developing roller while charging the developer. In the developing device for developing, the bias is adjusted according to the gap between the developing roller and the photoconductor.

The image forming apparatus disclosed in Japanese Unexamined Patent Publication No. 5-333685 is an image forming apparatus that forms an image by repeatedly charging, exposing and developing a photoconductor, and the image forming device includes a photoconductor drum surface and a developing device. By developing gap detecting means for detecting the gap between the agent carriers, data storing means for storing the signal detected by the developing gap detecting means in the memory, and changing the image forming condition based on the data storing means. The configuration is such that an image correction means for controlling the output image is provided.

[0009]

However, the above-mentioned prior art has the following problems. JP-A-4-208957 and JP-A-5-333685.
In the non-contact developing method disclosed in the publication, the distance between the surface of the image bearing member and the surface of the developer bearing member (hereinafter, referred to as the developing gap) is changed by using a one-component developer, for example,
The thickness of the developer layer is set to 0.11 mm, for example, to 0.03 mm, and the developer layer is configured to be a thin layer in which variations in the thickness can be ignored.

However, in the case of a non-contact developing system using a two-component developer, both the developing gap and the developer layer thickness are usually wider than those in the case of using a one-component developer. . The setting range of the non-contact developing method using such a two-component developer is, for example, Japanese Patent Application Laid-Open No. 1-1728.
No. 82, the development gap is 0.
In the range of 3 to 0.7 mm, the developer layer thickness is 0.15 to 0.
It is set to a range of 4 mm and used under the condition that the developer layer does not come into contact with the image carrier. Since development efficiency in this non-contact developing method is lower than that in the contact developing method, when a two-component developer is used, the developer necessary for obtaining sufficient image density is supplied to the developing area. In addition, while the electric field in the developing gap is sufficiently strong, the developing gap is set relatively large and the developer layer thickness is set thick.

Here, the developing area will be described. The area where the toner effectively acts on the image carrier is called the development area.Specifically, the toner is imaged by applying the same electric field applied during development with the developing sleeve and the image carrier stopped. The area flying to the carrier is defined as the developing area.

As described above, in the non-contact developing method using the two-component developer, the developing gap is configured to be wider than that in the case of using the one-component developer, so that the development caused by the variation amount of the developing gap affects the development. It is considered that the influence on the electric field is smaller than that in the case of one-component development. On the other hand, in the non-contact developing method using a two-component developer, the developer, which is a mixture of toner and carrier having different particle sizes, is held on the developing sleeve by the magnetic force of the magnetic force generating means installed inside the sleeve, It is configured so that a gap is formed between the developer and the image bearing member by the regulating member to regulate the developer layer thickness. Due to the roundness of the developing sleeve and the accuracy of the supporting structure, the developer layer thickness and hence the developer are It is very difficult to control the transport amount with high precision.

Here, the developer carrying amount will be described. The weight of the developer that effectively acts on the image bearing member is referred to as the developer transport amount, and specifically, the weight of the developer per unit area on the developing sleeve in the developing area is defined as the developer transport amount.

As a result of an experiment conducted by the present inventors paying attention to the relationship between the developer carrying amount and the developing density, there is a characteristic shown in FIG. 13 between the developer carrying amount and the developing density. I found that. Further, it was found that the variation of the developer transport amount was distributed along the circumferential direction of the developing sleeve and was the same as the pitch of the striped density unevenness generated on the image obtained on the recording sheet. That is, it was found that the striped density unevenness that occurs in the image on the recording sheet is caused by the variation in the developer transport amount along the circumferential direction of the developing sleeve. FIG. 14 shows the relationship between the position on the developing sleeve and the developer transport amount, and FIG. 15 shows the relationship between the position on the developing sleeve and the obtained developing density.
Are shown respectively.

The present invention has been made on the basis of such a background, and in an image forming apparatus having a developing device using a two-component developer, it is possible to prevent density unevenness that repeatedly occurs in the conveying direction on a recording sheet. However, it is an object of the present invention to provide an image forming apparatus capable of maintaining a developing condition capable of forming an optimum developed state and obtaining a uniform and stable image quality for a long period of time.

[0016]

To achieve the above object, the invention according to claim 1 holds a two-component developer, which is a mixture of a toner and a carrier, on a developer carrying member in a layered manner. An image forming apparatus having a developing device for adhering toner to an electrostatic latent image formed on an image bearing member opposite to the developer layer on the developer bearing member to develop the electrostatic latent image A developer carrying amount detecting means for detecting the amount of the developer, a data storing means for storing the developer carrying amount data from the developer carrying amount detecting means, and a relationship between the developer carrying amount and the developing bias condition are determined. Storage means for storing a table, calculation means for calculating an appropriate developing bias condition for keeping the developing density constant while referring to the data in the data storing means and the table in the storing means,
And a developing bias control means for controlling the developing bias based on the output of the control means.

According to a second aspect of the present invention, the developer carrying amount detecting means detects the pressure applied to a developer carrying amount regulating member for regulating the developer layer thickness on the developer carrying member. It is characterized by being constituted by a detection means.

A piezoelectric element is used as the pressure detecting means, but it goes without saying that another pressure detecting means may be used as long as it can detect the pressure. As the developer transport amount detecting means, for example, a combination of a light emitting element and a light receiving element may be used.

[0019]

According to the above-mentioned technical means, the developer carrying amount detected by the developer carrying amount detecting means composed of the piezoelectric element or the combination of the light emitting element and the light receiving element and the developer carrying amount in the storing means. -While referring to the developing bias condition correspondence table, the control means calculates an appropriate developing bias condition for keeping the developing density constant. In the developing bias control means, in response to a command from this controlling means, the amplitude of the AC component of the developing bias voltage is changed, or the frequency of the AC component of the developing bias voltage is changed. The output image is controlled by changing both the amplitude and the frequency.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram around an image forming unit of an image forming apparatus in this embodiment. In the figure, 1 is an image carrier, 2 is a scorotron charger, 3 is image exposure means such as a semiconductor laser device, 4a, 4b, 4c and 4d are each yellow,
The developing device 5 containing magenta, cyan, and black toners separately is a pre-transfer corotron, and the pre-transfer corotron charger 5 controls the amount of charge of the toner image formed on the image carrier 1. It has become. Reference numeral 6 denotes a transfer corotron charger for transferring the toner on the image carrier 1 to an image receptor (recording sheet), 7 denotes a peeling corotron charger for peeling the image receptor from the image carrier 1, and 8 Is a cleaning means using a cleaning blade, 9 is a light erasing means, and 10 is a recording sheet as an image receptor.

As the image carrier 1, a negatively charged organic photoreceptor (hereinafter referred to as OPC) was used. The outer diameter of the image carrier 1 is 100 mm, and the linear velocity of movement of the image carrier surface is 160 mm.
/ S. The developer of each color is composed of toner of each color and an average particle diameter of 40 μm in which magnetic powder is dispersed in resin.
A two-component developer comprising the carrier of

First, in the first cycle, the image carrier 1 is destaticized by the optical static eliminator 9, and the cleaning device 8 is attached to the image carrier 1.
The cleaning blade of 1 is brought into contact with the surface to clean the surface. After that, the blade is separated from the image carrier 1. The optical static eliminator 9 subsequently neutralizes the image carrier 1. Next, the surface of the image carrier 1 is uniformly charged to −700 V using the scorotron charger 2. After that, when the image exposure means 3 performs the first image exposure to form an image latent image,
The potential of the image area rises to -450V. Then, in the yellow developing device 4a, a DC voltage of -650V, an amplitude of 800V,
A developing bias in which an AC voltage having a frequency of 6 kHz is superposed is applied to adhere the yellow toner onto the image carrier 1. As the exposing means, any means such as a laser writing device, an LED array, a liquid crystal light valve including a uniform light source and a liquid crystal micro shutter can be used according to the purpose.

Then, in the second cycle, the surface of the image carrier 1 is uniformly charged to -700V by the scorotron charger 2. After that, when the image exposure means 3 performs the second image exposure to form an image latent image, the potential of the image portion is -45.
It rises to 0V. Then, a developing bias in which an AC voltage having an amplitude of 800 V and a frequency of 6 kHz is superposed on a DC voltage of −650 V is applied to the magenta developing device 4 b, and the magenta toner is attached onto the image carrier 1.

Thereafter, the same steps are repeated until Sian,
It is formed by overlapping black images. After that, the pre-transfer corotron charger 5 gives the toner a charge amount necessary for transfer.
Finally, the image carrier 1 is transferred to the image carrier transported by the transfer transport belt 10 by using the transfer corotron charger 6.
The toner attached to is collectively transferred. Further, the image receptor peeled off from the image carrier 1 is fixed by passing through a fixing device (not shown), while the toner remaining on the image carrier 1 and the history of charging are cleaned by the cleaning unit 8 and the light erasing unit. By removing by 9, the main image forming cycle is completed.

The construction of the essential parts of the developing device and the developer carrying amount detecting means in the present invention will be described with reference to FIGS. 2 and 3 by taking the developing device 4c for cyan toner as an example. The same applies to developing devices for toners of other colors. FIG. 2 is an enlarged view of a main part of the developing device according to the first embodiment, and FIG. 3 is a block diagram of the developer transport amount detecting means. First, in FIG. 2, the magnet roll 12 is arranged in a rotatable non-magnetic cylindrical developing sleeve 11. The magnet roll 12 has a magnetic pole 14 a (N pole) and a magnetic pole 15 with respect to a line connecting the centers of the image carrier 1 and the magnet roll 12.
It is fixed so that substantially the middle of a (S pole) faces each other. The developer is regulated to a constant thickness by the layer thickness regulating member (developer transport amount regulating member) 13, and is transported to the developing area by the rotation of the developing sleeve 11.

In this embodiment, the gap between the image carrier 1 and the developing sleeve 11 is set to 450 μm, and the developer layer thickness at the portion facing the image carrier 1 is set to 200 μm. The outer diameter of the developing sleeve 11 is 18 mm, and the angle between the magnetic pole 14a (N pole) and the magnetic pole 15a (S pole) is 20 degrees. The developing sleeve 11 is rotationally driven in the direction of the arrow by a driving unit (not shown). A developing bias is applied to the developing sleeve 11 by a developing bias power source. The developing bias is a DC voltage superimposed with an AC voltage. The DC component of the developing bias was set to -650V. The AC component of the developing bias has a frequency of 6 kHz and an amplitude of 800.
It was set to a rectangular wave of V.

Next, the developer carrying amount detecting means used in this embodiment will be described. As shown in FIG. 2, between the layer thickness regulating member 13 and the developing region, and between the N pole 14b and the S pole 15
In order to irradiate the laser beam to the point located in the middle of b,
A light emitting element 16 such as a laser diode and a reflecting mirror 18 are arranged. The laser light is applied to a position which is not in contact with the image receptor at the end portion in the axial direction of the developer carrier so that the laser beam does not affect the finally obtained image even if it is scattered on the image carrier 1.
Further, the light receiving element 17 is arranged at a position for receiving the reflected light reflected by the developing sleeve 11 through the developer and returning again through the developer. The developer transport amount detecting means 34 is
The light emitting element 16, the light receiving element 17, and the reflecting mirror 18
It is composed by. The transport amount of the developer detected by the light receiving element 17 is sent to the CPU 22 described later.

Next, in FIG. 3, the data of the developer conveyance amount detected by the light receiving element 17 is the CPU which will be described later.
The data is stored in the data storage means 30 sequentially by the control operation 22.

FIG. 4 shows the relationship between the thickness of the developer layer on the developing sleeve 11 and the intensity (reflectance) of the reflected light on the developing sleeve 11 holding the toner of each color, which is detected by the light receiving element 17. It was In FIG. 4, Y, M, C, B
Indicates the characteristics of each color of yellow, magenta, cyan, and black, respectively. Further, the relationship between the thickness of the developer layer and the developer transport amount has a proportional relationship as shown in FIG. The data shown in FIGS. 4 and 5 are stored in the ROM 21 shown in FIG. As shown in FIG. 3, the CPU 22 uses the intensity of the reflected light detected by the light receiving element 17 to cause the ROM
The developer conveyance amount is calculated with reference to the data in 21, and the calculated data is output to the data storage unit 30.

FIG. 6 is a block diagram showing the image forming condition correcting means 31. Referring to FIG.
As shown in FIG. 5, for each color toner, a developer conveyance amount-development bias condition correspondence table showing the relationship between the developer conveyance amount when the development density is kept constant and the amplitude of the AC component of the development bias voltage. Is stored. In FIG.
Y, M, C, and B represent the characteristics of each color of yellow, magenta, cyan, and black, respectively. Further, in FIG. 6, a CPU 35, a D / A converter 36, and a developing bias control unit 32 are provided in the order of data flow.
The developing bias control means 32, the ROM 33,
The CPU 35 and the D / A converter 36 constitute the image forming condition correction means 31. The image forming condition correcting means 31 corrects the image forming conditions such as the developing bias according to the developer carrying amount detected by the developer carrying amount detecting means 34.

In such a configuration, based on the fluctuation amount of the developer transport amount stored in the data storage means 30,
The CPU 35 calculates the proper developing bias condition by referring to the developer conveyance amount-developing bias condition correspondence table stored in advance in the ROM 33, and the calculated proper developing bias condition is converted into an analog signal by the D / A converter 36. Then, the developing bias voltage control means 32 controls the developing bias power source (not shown) based on the analog signal, and the developing bias voltage having an appropriate amplitude of the AC component is output. That is, the developer transport amount detecting means 34
The variation amount of the developer sequentially detected by the data storage unit 30 is sequentially sent to the CPU 35, and the CP
In U35, as described above, the proper developing bias condition is calculated with reference to the developer transport amount-developing bias condition correspondence table stored in advance in the ROM 33. When the amount of the developer conveyed to the developing area by the developing sleeve 11 changes, the density of the electrostatic latent image on the image carrier 1 to be developed changes, as shown in FIG. 7B. Therefore, even if the amount of the developer conveyed to the developing area by the developing sleeve 11 changes, the developing bias is determined from the relationship between the image density and the developing bias shown in FIG. 7C so that the developing density becomes constant. Is to control. Figure 7
7A is obtained from the relationship between the developer transport amount and the development density shown in FIG. 7B, and the relationship between the development density and the development bias shown in FIG. 7C. The CPU 35 is
The developing bias voltage obtained based on FIG.
The voltage is applied to the developing sleeve 11 via the D / A converter 36 and the developing bias control means 32. By doing so, even if the amount of the developer conveyed to the developing area by the developing sleeve 11 changes, the developing density can be kept constant. In the image formed by the above steps, remarkable development unevenness due to fluctuations in the developer transport amount was eliminated, the image was improved to a level where there was no practical problem, and high image quality could be achieved.

(1) Modification 1 Next, the developing bias voltage control means 32 adjusts the output image by the frequency of the AC component of the developing bias voltage. In the present modification, as shown in FIG. 8, the ROM 33 shows the relationship between the developer carrying amount and the frequency of the AC component of the developing bias voltage when the developing density is kept constant for each color toner. A developer conveyance amount-development bias condition correspondence table is stored, and the frequency of the AC component of the development bias voltage is adjusted by the development bias voltage control means 32.

In FIG. 8, Y, M, C and B respectively represent yellow, magenta, cyan and black colors. All other conditions and the order of the image forming steps were the same as in Example 1. In the formed image, remarkable development unevenness due to fluctuations in the developer transport amount was eliminated, the level was improved to a level that poses no practical problem, and high image quality could be achieved.

(2) Modified Example 2 Next, the light emitting element 1 as an essential part of the developer carrying amount detecting means.
6 is installed in the developing sleeve 11 as shown in FIG.
Will be explained. A part or all of the developing sleeve 11 is made of a transparent member, and laser light is irradiated from the light emitting element 16 provided inside the developing sleeve 11 toward the irradiation position, and passes through the developing sleeve 11 and the developer layer. The developer conveyance amount was detected by detecting the intensity of the transmitted light with the light receiving element 17. All other conditions and the order of the image forming steps were the same as in Example 1. In the formed image, remarkable development unevenness due to fluctuations in the developer transport amount was eliminated, the level was improved to a level that poses no practical problem, and high image quality could be achieved. Of course, the light emitting element 16 and the light receiving element 1
The positional relationship of 7 may be reversed.

(Embodiment 2) In Embodiment 2, as the developer carrying amount detecting means, a structure is adopted in which the pressure applied to the layer thickness regulating member 13 is measured to detect the developer carrying amount. In this example, the same configuration and image forming process as in Example 1 shown in FIG. 1 were used. The structure of the essential parts of the developing device and the structure of the developer transport amount detecting means in this embodiment will be described with reference to FIGS. The same applies to developing devices for toners of other colors.

FIG. 10 is a block diagram of the essential parts of the developing device according to the second embodiment.
FIG. 11 is a block diagram of the developer transport amount detecting means. In FIG. 10, a magnet roll 12 is arranged in a rotatable non-magnetic cylindrical developing sleeve 11. The magnet roll 12 has a magnetic pole 14a (N pole) and a magnetic pole 15a (S pole) with respect to a line connecting the centers of the image carrier 1 and the magnet roll 12.
Are fixed so that substantially the middle of them face each other. The developer is regulated to a constant thickness by the layer thickness regulating member 13, and is transported to the developing area by the rotation of the developing sleeve 11.

In this embodiment, the gap between the image carrier 1 and the developing sleeve 11 is set to 450 μm, and the developer layer thickness at the portion facing the image carrier 1 is set to 200 μm. The outer diameter of the developing sleeve 11 is 18 mm, and the angle between the magnetic pole 14a (N pole) and the magnetic pole 15a (S pole) is 20 degrees. The developing sleeve 11 is rotationally driven in the direction of the arrow by a driving unit (not shown). A developing bias is applied to the developing sleeve 11 by a developing bias power source. The developing bias is a DC voltage superimposed with an AC voltage. The DC component of the developing bias was set to -650V. The AC component of the developing bias has a frequency of 6 kHz and an amplitude of 800.
It was set to a rectangular wave of V.

Next, the developer carrying amount detecting means used in this embodiment will be described. As shown in FIG. 10, the piezoelectric element 19 for detecting the pressure applied to the layer thickness regulating member 13 is sandwiched between the layer thickness regulating member 13 and the developing device frame 20. The relationship between the pressure applied to the layer thickness regulating member 13 detected by the piezoelectric element 19 and the developer transport amount is a proportional relationship as shown in FIG. The data shown in FIG. 12 is stored in the ROM 21 shown in FIG.

As shown in FIG. 11, the CPU 22 controls the ROM 21 by using the magnitude of the pressure detected by the piezoelectric element 19.
The developer conveyance amount is calculated with reference to the data therein, and the calculated data is output to the data storage unit 30. Also in this embodiment, similarly to the first embodiment, the piezoelectric element 19, the ROM
The CPU 21 and the CPU 22 constitute a developer transport amount detecting means 34. The data flow in the image forming condition correction means 31 is as shown in FIG.

(1) Modification 1 Next, the output image is adjusted by the developing bias voltage control means 32 according to the frequency of the AC component of the developing bias voltage. In the present modification, as shown in FIG. 8, the ROM 33 shows the relationship between the developer carrying amount and the frequency of the AC component of the developing bias voltage when the developing density is kept constant for each color toner. A developer conveyance amount-development bias condition correspondence table is stored, and the frequency of the AC component of the development bias voltage is adjusted by the development bias voltage control means 32.

In FIG. 8, Y, M, C and B represent the characteristics of each color of yellow, magenta, cyan and black, respectively. All other conditions and the order of the image forming steps were the same as in Example 2. In the formed image, remarkable development unevenness due to fluctuations in the developer transport amount was eliminated, the level was improved to a level that poses no practical problem, and high image quality could be achieved.

(2) Modification 2 Next, as the developer transport amount detecting means, the layer thickness regulating member 13 is used.
Using a strain gauge pressure-bonded to the layer thickness regulating member 13, the strain of the layer thickness regulating member 13 is measured to measure the strain from the surface of the developing sleeve 11.
The developer transport amount was detected by calculating the distance to the tip of No. 3. All other conditions and the order of the image forming steps were the same as in Example 2. The formed image contains
The remarkable uneven development due to the fluctuation of the developer conveyance amount is eliminated,
It has been improved to a level where there is no practical problem, and high image quality could be achieved.

The non-contact development method using a two-component developer has been mainly described above. However, even in the case of the contact development method, the fluctuation of the developer carrying amount causes uneven development. It is also applicable to a developing method using a method and is effective in eliminating uneven development.

[0044]

According to the present invention, since the developer carrying amount on the developer carrying member is always detected and the developing bias is adjusted according to the fluctuation, the image density of the image density due to the fluctuation of the developer carrying amount is adjusted. It is possible to provide an image forming apparatus capable of reducing fluctuation and stably obtaining a high-quality image without uneven development.

[Brief description of drawings]

FIG. 1 is a configuration diagram around an image forming unit of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is an enlarged configuration diagram of a main part of the developing device in Embodiment 1 of the present invention.

FIG. 3 is a block diagram of a developer conveyance amount detection unit according to the first exemplary embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between the thickness of the developer layer on the developing sleeve and the reflectance of laser light.

FIG. 5 is a characteristic diagram showing the relationship between the thickness of the developer layer on the developing sleeve and the developer transport amount.

FIG. 6 is a block diagram of image forming condition correcting means in the embodiment of the present invention.

FIG. 7A is a characteristic diagram showing the relationship between the developer conveyance amount and the amplitude of the AC component of the developing bias voltage when the development concentration is kept constant, and FIG. 7B is the relation between the developer conveyance amount and the image density. FIG. 3C is a characteristic diagram showing the relationship between the image density and the developing bias.

FIG. 8 is a characteristic diagram showing the relationship between the developer transport amount and the frequency of the AC component of the developing bias voltage when the developing density is kept constant.

FIG. 9 is an enlarged configuration diagram of a main part of a developing device in the case where the light emitting element has another form in Example 1 of the present invention.

FIG. 10 is an enlarged configuration diagram of a main part of a developing device in Embodiment 2 of the present invention.

FIG. 11 is a block diagram of a developer conveyance amount detection unit according to the second exemplary embodiment of the present invention.

FIG. 12 is a characteristic diagram showing the relationship between the pressure applied to the layer thickness regulating member and the developer transport amount.

FIG. 13 is a characteristic diagram showing the relationship between the developer transport amount and the development density.

FIG. 14 is a characteristic diagram showing the relationship between the position on the developing sleeve and the developer transport amount.

FIG. 15 is a characteristic diagram showing the relationship between the position on the developing sleeve and the obtained developing density.

[Explanation of symbols]

1 ... Image bearing member, 11 ... Developing sleeve (developer bearing member),
30 ... Data storage means, 32 ... Development bias voltage control means, 33 ... ROM (storage means), 34 ... Developer conveyance amount detection means, 35 ... CPU (control means).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 15/09 Z (72) Inventor Shigenori Ando 2274 Hongo, Ebina-shi, Kanagawa Prefecture, Fuji Xerox stock In-house (72) Inventor Shinji Sasahara, 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Heiwa Koren, 2274, Hongo Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd.

Claims (2)

[Claims] 1. A two-component developer obtained by mixing a toner and a carrier is held on a developer carrier in a layered form, and
In an image forming apparatus having a developing device for adhering toner to an electrostatic latent image formed on an image carrier opposite to the developer layer on the developer carrier to develop the developer, the developer conveyed to a developing area. And a data storage means for storing the developer transport amount data from the developer transport amount detecting means, and a table for determining the relationship between the developer transport amount and the developing bias condition. Is stored in the storage means, a calculation means for calculating an appropriate developing bias condition for keeping the developing density constant while referring to the data in the data storing means and the table in the storing means, and the output of the control means. An image forming apparatus comprising: a developing bias control unit that controls a developing bias based on the image forming apparatus. 2. The developer carrying amount detecting means is constituted by pressure detecting means for detecting a pressure applied to a developer carrying amount regulating member for regulating the developer layer thickness on the developer carrying member. The image forming apparatus according to claim 1, wherein: