JP2001117361A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact developing device constituted so that toner concentration near a developer carrier can be kept constant and changed in the lapse of time and according as environment is fluctuated and the finish of an image is set and an image forming device having this developing device. SOLUTION: This developing device is provided with a 1st and a 2nd developer quantity regulation members 4 and 5 regulating the quantity of developer on a developing sleeve 3a and a developer housing chamber 6a housing the developer scraped from the surface of the sleeve 3a by the 1st regulation member 4. Then, the 2nd regulation member 5 is supported so that it can made to approach and separated with respect to the surface of the sleeve 3a. Besides, the approach and the separation of the 2nd regulation member 5 with respect to the surface of the sleeve 3a can be set by operating the operation member of the image forming device.

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, a printer, a facsimile, etc., for forming an image by an electrophotographic process.

[0002]

2. Description of the Related Art As a method for developing an electrostatic latent image formed on an image carrier using a toner, a one-component developing method using a one-component developer composed of a toner and a two-component developing method using a toner and a carrier are known. A two-component developing method using an agent is known. In the two-component development method, the toner is held on the surface of the magnetic carrier by an electrostatic force generated by friction between the magnetic carrier and the toner, and the toner is brought close to an electrostatic latent image in which an electric field is formed, thereby staticizing the toner. The toner image is formed by being attracted to the latent image. In recent years, from the standpoint of environmental preservation or economic considerations, the two-component developer used in the above-described developing method also employs a method of repeatedly using while replenishing toner lost by consumption, As for the developing device, a device for realizing cost reduction and miniaturization has been developed. As such an apparatus, for example, a developing apparatus in which a developer storage chamber is provided around a developer carrier and toner is taken in and replenished by movement of the developer on the developer carrier is known.

However, in such a developing device,
At the time of replenishing the toner, the toner density temporarily exceeds the appropriate density, and an excessively high toner density causes a problem that an abnormal image such as toner scattering or background contamination occurs. In order to solve this problem, it is necessary to maintain the toner concentration within a certain range, and a developing device that controls the toner concentration by installing a toner replenishing member and a toner concentration sensor is used. Thus, it is possible to prevent scattering of toner and background contamination, and to obtain a stable image. However, since such a developing device is equipped with a toner density sensor and a toner replenishing member, the size of the device cannot be reduced.

In order to solve this problem, there has been proposed a developing device for maintaining a constant toner density without providing a toner replenishing member or a toner density sensor. For example, Japanese Patent Application Laid-Open Nos. 9-22178 and 9-197833 disclose systems in which toner concentration is self-controlled with a small amount of developer. In this system, a developer accommodating chamber is provided around the developer carrier between the first developer amount regulating member and the second developer amount regulating member, and toner is supplied from the toner supply port onto the developing sleeve. When the toner concentration increases, the transport resistance provided by the developer in the developer accommodating chamber increases, and a ball-throwing phenomenon occurs in the transport of the developer, so that a developer pool is formed in the second developer regulating member. Then, the developer closes the toner supply port, and the toner supply is stopped. As a result, the toner is consumed and the toner concentration is reduced. When the toner on the developing sleeve decreases and the toner concentration decreases, the toner supply port is opened, the toner is supplied from the toner hopper, and the toner concentration on the developer carrier increases.

As described above, in this system, the toner concentration is controlled by the bulk of the developer, and the amount of the two-component developer contained in the developer containing section is small. Are uniformly supported in the axial direction. further,
The two-component developer used in this system has a smaller amount of magnetic carriers than the two-component developer used in a normal two-component development system, so that the torque of the device is greatly reduced. Further, since the toner is taken in by the movement of the magnetic carrier, it is possible to simplify the means for detecting and adjusting the toner concentration indicating the mixing ratio of the toner and the magnetic particles, and to omit a stirring member such as a paddle screw. ,
Thereby, it is possible to cope with downsizing and cost reduction of the device. In such a system, by changing the initial amount of the magnetic carrier contained in the developer containing section, the bulk of the developer is changed, whereby the toner concentration can be adjusted.

[0006]

However, the above-mentioned prior art has the following problems. In the system that performs the self-control of the toner concentration with a small amount of the developer by the method described above, the toner concentration is controlled by changing the initial amount of the magnetic carrier stored in the developer storage unit. It is difficult to make corrections to prevent image deterioration such as background contamination and image density reduction due to environmental fluctuations, and to change the image finish. Accordingly, environmental fluctuations are dealt with by adjusting the initial developer physical properties and adjusting the latent image conditions, so that optimum conditions cannot be obtained, and it is difficult to maintain good image finish. Met.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to maintain a constant toner concentration in the vicinity of a developer carrying member and to cope with aging and environmental changes. It is another object of the present invention to provide a small-sized developing device capable of changing the toner density according to the setting of the image finish, and an image forming apparatus having such a developing device.

[0008]

In order to solve the above problems, the invention according to claim 1 is supported rotatably,
A developer carrier having a magnetic field generating means therein, for carrying and transporting a two-component developer including a toner and a magnetic carrier,
A first developer amount regulating member that is arranged close to the surface of the developer carrier and regulates the amount of a two-component developer carried on the surface of the developer carrier; and the first developer. A second developer amount regulating member disposed on a rotation direction upstream side of the developer carrier with respect to the amount regulating member, wherein the first developer amount regulating member is arranged in a circumferential direction of the developer carrier. And L
A second developer amount regulating member disposed at an interval of 1 and close to the developer carrying member; and a first developer amount regulating member and the second developer amount regulating member. A developer accommodating chamber provided in a partitioned space and accommodating a two-component developer scraped from the surface of the developer carrying member by the first developer amount regulating member; and In a developing device having a toner hopper to be supplied to a developer carrier side, a developing device is provided in which the second developer amount regulating member is supported so as to be able to approach and separate from the developer carrier.

According to a second aspect of the present invention, there is provided a driving means for driving the second developer amount regulating member, wherein the second developer amount regulating member is supported via the driving means. The developing device according to claim 1, wherein the developing device is moved toward and away from the developer carrier.

According to a third aspect of the present invention, the image forming apparatus further comprises a temperature detecting means, wherein the second developer amount regulating member approaches and closes to the developer carrier in accordance with a detection result of the temperature detecting means. A developing device according to claim 1 or 2 which is separated.

According to a fourth aspect of the present invention, the image forming apparatus further comprises a humidity detecting unit, wherein the second developer amount regulating member approaches and closes to the developer carrier in accordance with a detection result of the humidity detecting unit. A developing device according to claim 1, 2 or 3, which is separated.

According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect, the second developer amount regulating member is movable within a predetermined range. The present invention provides a developing device.

According to a sixth aspect of the present invention, there is provided an image reading unit, a photoreceptor, an image forming unit including a developing unit, a transferring unit, and a fixing unit, a sheet feeding unit, and an operating unit. An image forming apparatus, wherein the developing means is rotatably supported, has a magnetic field generating means therein, and carries and transports a two-component developer including a toner and a magnetic carrier. A first developer amount regulating member that is arranged close to the surface of the developer carrier and regulates the amount of the two-component developer carried on the surface of the developer carrier;
A second developer amount regulating member disposed on a rotation direction upstream side of the developer carrier with respect to the first developer amount regulating member, wherein the first developer amount regulating member is arranged in a circumferential direction of the developer carrier. A second developer amount regulating member disposed at an interval between the developer amount regulating member and L1 and in close proximity to the developer carrying member;
The first developer amount regulating member is provided in a space partitioned by the first developer amount regulating member and the second developer amount regulating member, and is scraped off from the surface of the developer carrier by the first developer amount regulating member. An image forming apparatus comprising: a developer accommodating chamber for accommodating a two-component developer; and a toner hopper for accommodating toner and supplying the developer to the developer carrier. For the carrier,
Provided is an image forming apparatus which is supported so as to be able to approach and separate, and in which the approach and separation of the second developer amount regulating member to and from the developer carrier are set by operating the operation unit.

According to a seventh aspect of the present invention, the developing means includes a driving means for moving the second developer amount regulating member toward and away from the developer carrying member; The image forming apparatus according to claim 6, wherein a developer amount regulating member is supported via the driving unit, and is moved toward and away from the developer carrier.

The invention according to claim 8 is provided with a temperature detecting means for detecting a temperature in the vicinity of the developing device, wherein the second developer amount regulating member is provided in accordance with a detection result of the temperature detecting means. The image forming apparatus according to claim 6, wherein the image forming apparatus is moved toward and away from the developer carrier.

According to a ninth aspect of the present invention, there is provided a humidity detecting means for detecting humidity in the vicinity of the developing device, wherein the second developer amount regulating member is provided in accordance with a detection result of the humidity detecting means. An image forming apparatus according to any one of claims 6, 7 or 8, wherein the image forming apparatus is moved toward or away from the developer carrier.

According to a tenth aspect of the present invention, in the sixth, seventh, eighth or ninth aspect, the second developer amount regulating member is movable within a predetermined range. An image forming apparatus is provided.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) An embodiment of the developing device according to claim 1 will be described. FIG. 1 is a schematic configuration diagram showing the developing device, and FIG. 2 is a diagram showing the vicinity of a developer carrier in a state where a doctor 4 and a pre-doctor 5 are provided. The developing device includes a cylindrical photosensitive drum 1 serving as a latent image carrier.
And a developing casing 2 having an opening at a position facing the photosensitive drum 1.
Inside, a developer carrier 3 partially exposed from the opening and carrying a two-component developer composed of a toner and a magnetic carrier on the surface, a developer carried on the surface of the developer carrier 3 and conveyed A doctor 4 as a first developer regulating member, a pre-doctor 5 as a second developer regulating member, a developer accommodating case 6, a toner hopper 7 as a toner accommodating section, and the like.

The developer carrier 3 includes a magnet roller 3b as a magnetic field generating means fixedly disposed inside, and a developing sleeve 3a formed of a non-magnetic material around the magnet roller 3b. They are arranged in parallel and supported rotatably in the direction of the arrow. A magnetic pole 3c is arranged in a region between the doctor 4 and the pre-doctor 5 on the upstream side of the developing position, which is the opposing portion of the photosensitive drum 1 and the developer carrier 3, of the magnet roller 3b. The doctor 4 moves the developing sleeve 3 to the developing area.
a free end is located at a position upstream of the rotation of the developing sleeve 3a.
And at predetermined intervals. The pre-doctor 5 is disposed further upstream than the doctor 4 on the rotation side of the developing sleeve 3b, and the pre-doctor fixing member 5a
And a pre-doctor plate 5b. The pre-doctor plate 5b is fixed to the pre-doctor fixing member 5a such that a free end can move in a direction of approaching and separating from the surface of the developing sleeve 3a. Distance Gd between free end of doctor plate 5b and developing sleeve 3a
2 is variable. The developer storage case 6
Is provided above the developing sleeve 3a on the upstream side of rotation of the developing sleeve 3a with respect to the developing position, and is not used for developing the electrostatic latent image, and contains the developer which is prevented from moving by the doctor 4. The housing part 6a is formed. The toner hopper 7 is disposed adjacent to and upstream of the developer accommodating portion 6a in the developer transport direction, and has a toner supply port 7a facing the surface of the developing sleeve 3a. Also, the toner hopper 7
An agitator 8 serving as a toner stirring member for sending out new toner while stirring it toward the toner supply port 7a is arranged inside and is rotatably supported. The position of the rotating shaft and the length of the blades of the agitator 8 are adjusted so that the outermost track of the agitator 8 does not come into contact with the developer, as indicated by the broken line in the figure.

Next, the operation of the developing device of this embodiment will be described. The developer carried on the developing sleeve 3a is conveyed to the doctor 4 side with the rotation of the developing sleeve 3a rotating in the direction of arrow a, and the amount of the developer is regulated by the doctor 4 to form a thin layer. The developer thinned on the developing sleeve 3a is transported to a developing area facing the photosensitive drum 1 rotating in the direction of arrow b. In the developing area, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1, and the electrostatic latent image is developed to form a toner image. Thereafter, the developer on the developing sleeve 3a is
As the developing sleeve 3a rotates, it is conveyed to the toner supply port 7a side, sent out by the agitator 8, and
After taking in the new toner in the toner hopper 8 supplied from a, the flow returns to the developer accommodating section 6a. The developer mixed with the new toner and stored in the developer storage unit 6a increases the internal pressure in the developer amount control unit by the doctor 4, and
The toner is triboelectrically charged. As described above, the developer container 6
By a, the toner on the developing sleeve 3a can be charged, so that a complicated developer stirring and conveying mechanism using a paddle, a screw, or the like for charging or stirring the developer is not required.

On the other hand, a part of the developer which is not supplied to the developing area and whose movement is blocked by the doctor 4 is removed from the developer accommodating portion 6.
The toner hopper 7 moves toward the toner supply port 7a by the gravity and internal pressure of the developer itself. The developer that has moved to the toner supply port 7a is regulated to a certain layer thickness by a pre-doctor 5 which is a second developer regulating member disposed upstream of the doctor 4 from the position where the doctor 4 is disposed, and the magnet roller 3b The magnetic pole 5a attracts the developing sleeve 3a and is conveyed again to the doctor 4 side with the rotation of the developing sleeve 3a, formed into a thin layer and moved to the developing position, and used for developing an electrostatic latent image. In this way,
The developer in the developer device circulates through the developing device.

In the above-described developing device, when the toner is replenished in the developer and the toner concentration increases, the developer moves toward the pre-doctor 5 and is regulated by the pre-doctor 5, but does not form the developer layer. The surplus developer forms the developer stagnant portion 6b and covers the opening of the toner supply port 7a, so that the amount of toner taken into the developer on the side of the developing sleeve 3a decreases. And, due to the suspension of toner intake,
An increase in toner concentration is prevented. Conversely, when the toner is consumed by the development and the toner concentration decreases, the bulk of the developer decreases on the side of the developing sleeve 3a, the developer does not fill the developer retaining portion 6b, and the toner supply port 7a is opened. Therefore, a predetermined amount of toner is taken into the developer on the side of the developing sleeve 3a from here, and the toner concentration increases.

A method of arbitrarily changing the toner density in the above-described developing device will be described. In the above configuration,
The distance Gd between the pre-doctor plate 5b and the developing sleeve 3a
When the width 2 is widened, the amount of the developer regulated by the predoctor plate 5b decreases, the amount of the developer staying in the developer staying portion 6b decreases, the toner supply port 7a is opened, and the developing sleeve 3a is opened. The amount of toner taken into the developer increases, and as a result, the toner density increases. When the distance Gd2 between the pre-doctor plate 5b and the developing sleeve 3a is reduced, the amount of the developer regulated by the pre-doctor plate 5b increases, and the amount of the developer staying in the developer staying portion 6b increases. The toner density becomes lower. As described above, in the developing device of the present embodiment, the toner density can be arbitrarily changed by adjusting the distance between the predoctor plate 5b and the developing sleeve 3a.

Next, a conventional developing device will be described for comparison with the developing device of the present embodiment. FIG. 8 is a schematic configuration diagram showing a conventional developing device. This developing device
The configuration is the same as that of the developing device of the present embodiment shown in FIG. In this developing device, the toner concentration can be changed by changing the amount of the magnetic carrier contained in the developer containing portion 36a and increasing or decreasing the bulk of the developer. For example, by changing the amount of the carrier from the initial amount, it is possible to reduce the bulk of the developer, increase the intake of the toner from the toner supply port 37a, and increase the toner concentration. Similarly, the toner concentration can be reduced by increasing the amount of the carrier from the initial amount. As described above, by changing the amount of the magnetic carrier in the developer accommodating portion 36a, the toner concentration can be kept within a substantially constant range without using a complicated toner concentration control mechanism using a toner concentration sensor or a toner replenishing member. It is possible to control.

However, in this developing device, since the toner concentration is controlled only by the amount of the magnetic carrier contained in the developer containing portion 36b, the toner concentration is measured by using the toner concentration detecting means. Adjust to the value corresponding to the characteristic fluctuation of the agent, stabilize the image quality,
In addition to the latent image conditions for forming the image set by the user, it is impossible to change the toner density to change the image finish. On the other hand, in the developing device of the present embodiment, the pre-doctor plate 5b is movably supported and the distance Gd2 between the pre-doctor plate 5b and the developing sleeve 3a is made variable, so that the pre-doctor plate 5b is accommodated in the developer accommodating portion 6a. The amount of toner can be changed without increasing or decreasing the amount of magnetic carrier.

Hereinafter, a specific example in which an image is formed using the developing device of the present embodiment will be described. Using the developing device of the present embodiment, the amount of the magnetic carrier accommodated in the developer accommodating portion 6a is set to 50 g, the predoctor plate 5b and the developing sleeve 3 are set.
a is fixed to 0.5 mm, and the developing sleeve 3
A continuous image is formed by using a test chart such that the toner consumption becomes uniform in the longitudinal direction of a as a document, and
When the toner density of the developer was measured after forming the image on the sheet, it was 9 wt%, and the image density at this time was slightly insufficient. Next, the amount of the magnetic carrier accommodated in the developer accommodating portion 6a was fixed to 50 g, Gd2 was changed to 0.8 mm, an image was formed again in the same procedure, and the toner concentration was measured. However, the content was 13 wt%, and a good image without image density shortage could be obtained. FIG. 6 shows the relationship between the gap Gd2 between the predoctor plate and the developing sleeve and the toner density in the developing device of the present embodiment.

The developing conditions of the present embodiment are as follows. Mechanical conditions Photoreceptor linear velocity 120 mm / sec Gap between developing sleeve and photoreceptor drum Gp 0.3 ~
0.5 mm Gd1 between developing sleeve and doctor blade
0.3 to 0.5 mm Gd2 between developing sleeve and predoctor 0.3 to 0.5 mm
1.5 mm Developing sleeve diameter 16φ Linear speed ratio of developing roller to photoconductor linear speed 1.5-3.
0 Developer carrier Magnetite or iron 40 to 50 μm Toner Magnetic substance amount 15 to 40 wt% Silica amount 0.5 to 1.0 wt% Toner carrier coverage 50 to 120% Q / M 10 to 30 μc / g Inside developer container Amount of magnetic carrier accommodated in
150g

In the present embodiment, the pre-doctor plate is arbitrarily approached and separated from the surface of the developing sleeve. However, the pre-doctor plate is movable within the movable range of the pre-doctor plate, that is, the interval between the pre-doctor plate and the developing sleeve. Upper and lower limits can also be set. As this method, a fixing member such as a screw may be used, or the control unit may set upper and lower limit values (limiters). For example, by setting Gd2 to 0.5 or more and 1.0 or less, the toner concentration can be controlled between 9 wt% and 16 wt%. As described above, by setting the upper limit and the lower limit for the interval Gd2 between the predoctor plate and the developing sleeve, it is possible to make the toner density closer to the target toner density, and to obtain a good image in accordance with aging and environmental changes. be able to.

(Second Embodiment) Claim 1 or Claim 2
An embodiment of the developing device described in 1 above will be described. This developing device has a mechanism for electrically driving the predoctor plate 25b. FIG. 3 shows the pre-doctor plate 25b and the driving means 22 of the developing device. As shown in FIG. 3, in this developing device, a gear 25c is provided on the pre-doctor plate 25b, and the driving unit 22 having a worm gear electrically drives the pre-doctor plate 25b. Pre-doctor plate 25 per rotation of drive unit
The moving amount of b is set to 0.05 mm, for example,
If it is desired to move by 0.3 mm, six rotations may be performed. The drive unit is capable of normal and reverse rotation, and by changing the rotation direction, the distance Gd2 can be increased or decreased. By electrically driving the pre-doctor plate 25b by providing the driving unit in this manner, it is possible to cope with a case where the toner density is to be changed according to a notice, a change in environment, or a user setting. The configuration of the present embodiment except for the pre-doctor plate 25b and the driving means 22 is the same as that of the first embodiment. Further, as means for moving the pre-doctor plate 25b, in addition to the above, a solenoid or the like may be used, and the pre-doctor plate 25b may be mechanically moved.

(Third Embodiment) An embodiment of the developing device according to claim 1, 2, or 3 will be described. This developing device has substantially the same configuration as the developing device described in the second embodiment, and the predoctor plate is electrically driven by a predoctor driving unit that is a driving unit, so that the predoctor plate is close to and close to the developing sleeve surface. Separation takes place. A temperature detecting means for detecting a temperature near the developing means is provided near the developing device, and the movement of the predoctor plate is controlled in accordance with the result of the temperature detection. That is, as shown in FIG. 4, the developing device has a system in which the control unit performs an arithmetic process in accordance with the detection result of the temperature detecting unit, and performs control by the pre-doctor driving unit. When it is necessary to change the set value of the toner density according to the change of the environment, the above-described temperature detection is executed, and the distance G between the predoctor plate and the developing sleeve is determined.
It is possible to adjust the toner density by changing d2 to an appropriate value.

Using the developing device of the present embodiment and the conventional developing device, an image was formed as follows, and a change in toner density and a formed image were investigated. The environmental temperature was set to 23 ° C. and 10 ° C., and the amount of the magnetic carrier contained in the developer accommodating portion was set to 50 g using a conventional developing device having no temperature detecting means. Was fixed at 0.8 mm. Under these different temperature conditions, continuous image formation is performed using a test chart as a document in which toner consumption is uniform in the longitudinal direction of the developing sleeve, and the developer accommodated in the developer accommodating chamber after 250 images have been formed. Was measured. FIG. 7 is a correction table of the gap Gd2 between the predoctor plate and the developing sleeve corresponding to the detected temperature. As a result, the toner concentration was 13 at the environmental temperature of 23 ° C.
wt%, but when the temperature changed to 10 ° C, 16 wt%
%, And at the same time, background smearing of the image occurred. As described above, it was found that the toner density fluctuated due to the fluctuation of environmental conditions, and image defects occurred.

Next, the environmental temperature is set to 23 ° C. and 10 ° C.
Using the developing device of the present embodiment, the same experiment was performed by setting the amount of the magnetic carrier in the developer accommodating section and the interval between the predoctor plate and the developing sleeve in the same manner as above.
Even in an environment of 10 ° C., good images without background contamination could be obtained. In the developing device of the present embodiment, the distance Gd2 between the predoctor plate and the developing sleeve is changed from 0.8 mm to 0.6 mm based on the detection result of the temperature detecting means, and image formation is performed in the same procedure. The measurement was performed. As a result, the toner concentration was 13 wt%, and a good image was obtained. In the present embodiment, the temperature detecting means is provided, and the proximity and the separation of the pre-doctor plate to and from the developing sleeve are controlled in accordance with the temperature change in the vicinity of the developing means. A configuration that performs similar control according to changes in humidity,
Alternatively, a configuration including both a temperature detecting unit and a humidity detecting unit is also possible.

(Fourth Embodiment) An embodiment of the image forming apparatus according to the sixth, seventh or eighth aspect will be described. This image forming apparatus includes an image reading unit, a photoconductor, a developing unit, a transfer unit, and an image forming unit including a fixing unit, a paper feeding unit, and an operation unit. The developing unit has substantially the same configuration as that of the developing device described in the third embodiment, and the predoctor plate is electrically driven by a predoctor driving unit that is a driving unit, so that the predoctor plate can be moved close to the developing sleeve surface. Separation takes place. Further, the image forming section is provided with temperature detecting means for detecting a temperature in the vicinity of the developing means, and the movement of the predoctor plate is controlled in accordance with the temperature detection result. That is, in this image forming apparatus, as shown in FIG. 5, there is a system in which the control unit performs arithmetic processing in accordance with the detection result of the temperature detection unit and performs control by the pre-doctor drive unit. When it is necessary to change the set value of the toner density according to the change of the usage environment, the above-described temperature detection is performed, and the gap Gd2 between the pre-doctor plate and the developing sleeve is set to an appropriate value to adjust the toner density. It is possible to adjust.

The image forming apparatus has an operation section in the apparatus main body. As shown in FIG. 5, the control section performs arithmetic processing in accordance with an input signal from the operation section, and controls the pre-doctor driving section. Has a system. To change the finish of an image according to the user's preference, it is necessary to change the toner density target value in accordance with the finish of the image. However, according to this system, the distance Gd2 between the predoctor plate and the developing sleeve is set to an appropriate value. It is possible to change to the target toner density by setting to a value. As described above, according to the image forming apparatus of the present embodiment, it is possible to adjust the toner density corresponding to the environmental fluctuation and to achieve the toner density according to the finish desired by the user. In addition,
The image forming apparatus of the present embodiment includes a temperature detecting unit, and controls the proximity and separation of the predoctor plate to and from the developing sleeve according to a temperature change near the developing unit.
It is also possible to provide a humidity detecting means in place of the temperature detecting means and perform the same control in accordance with a change in humidity, or to provide both a temperature detecting means and a humidity detecting means.

[0035]

As described above, the developing device according to the first aspect has the first developer amount regulating member and the second developer amount regulating member for regulating the amount of the developer on the developing sleeve. In a developing device including a developer accommodating chamber for accommodating the developer scraped off from the surface of the developing sleeve by the first developer amount regulating member, the second developer amount regulating member is moved closer to the surface of the developing sleeve. And, by supporting the developer so as to be separable, the distance between the second developer amount regulating member and the developing sleeve can be changed, whereby the developer amount can be changed without changing the initial amount of the magnetic carrier in the developer accommodating portion. It is possible to easily change the toner density and always obtain a good image.

According to a second aspect of the present invention, in the configuration of the first aspect, a driving unit for driving the second developer amount regulating member is provided, and the second developer amount regulating member is provided.
The toner density is controlled according to the temporal variation and the environmental variation by supporting via the driving means and moving toward and away from the developing sleeve by the driving means.

According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, wherein a temperature detecting means or a humidity detecting means is provided near the apparatus. By moving the second developer amount regulating member close to and away from the developer carrier in accordance with the detection result of the detecting means or the humidity detecting means, an appropriate toner concentration corresponding to environmental fluctuations such as temperature and humidity can be obtained. By performing the adjustment, it is possible to obtain a good image without a decrease in image density.

According to a fifth aspect of the present invention, there is provided the developing device according to the first aspect.
In the developing device according to claim 2, the moving range of the second developer amount regulating member close to or away from the developing sleeve is within a predetermined range. A good image can be obtained by accurately setting an appropriate toner density in accordance with a change over time or an environmental change.

The image forming apparatus according to the present invention comprises an image reading unit, an image forming unit including a photoreceptor, a developing unit, a transfer unit and a fixing unit, a paper supply unit, and an operation unit. In the image forming apparatus, the developing unit is configured to perform development by a first developer amount regulating member, a second developer amount regulating member, and a first developer amount regulating member that regulate an amount of the developer on the developing sleeve. In an image forming apparatus including a developer accommodating chamber for accommodating the developer scraped off from the surface of the sleeve, by supporting the second developer amount regulating member to be close to and away from the surface of the developing sleeve, It is possible to change the distance between the second developer amount regulating member and the developing sleeve, thereby easily changing the toner concentration of the developer without changing the initial amount of the magnetic carrier in the developer accommodating portion, and always changing the toner concentration. Get a good image In both cases, the proximity and separation of the second developer amount regulating member with respect to the developing sleeve can be set by operating the operation unit, so that the toner density can be adjusted to an appropriate toner density according to the image finish set by the user. Become.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, a driving means for driving the second developer amount regulating member is provided in the developing means, and the second developing means is provided. The agent amount regulating member is supported via a driving unit, and is moved toward and away from the developing sleeve by the driving unit to control toner concentration according to aging and environmental fluctuations and to achieve an image finish set by a user. It is possible to adjust the toner concentration to an appropriate value.

The image forming apparatus according to claim 8 and the image forming apparatus according to claim 9 are, in the image forming apparatus according to claim 6 or 7, a temperature detecting means or a humidity detecting means near the developing means. Provided, according to the detection result of the temperature detecting means or the humidity detecting means, by moving the second developer amount regulating member closer to and away from the developer carrier,
Performs appropriate toner density adjustment in accordance with environmental fluctuations such as temperature and humidity to obtain a good image without image density reduction, and adjusts to an appropriate toner density according to the image finish set by the user. Becomes

According to a tenth aspect of the present invention, in the image forming apparatus according to the sixth, seventh, eighth, or ninth aspect, the second developer amount regulating member is attached to the developing sleeve. By setting the moving range of the proximity and the separation within a predetermined range, it is possible to accurately set an appropriate toner concentration according to aging and environmental fluctuations, obtain a good image, and obtain an image finish set by a user. It is possible to adjust the toner concentration to an appropriate value according to the above.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of a developing device according to claim 1.

FIG. 2 is a view showing a state in which a doctor and a pre-doctor are arranged near a developing sleeve of the developing device shown in FIG. 1;

FIG. 3 is a view showing a pre-doctor plate and a driving means constituting one embodiment of the developing device according to claim 1 or 2;

FIG. 4 is a block diagram showing control of movement of a pre-doctor plate in the embodiment of the developing device according to claim 1, 2 or 3;

FIG. 5 is a block diagram showing control of movement of a pre-doctor plate in the image forming apparatus according to an embodiment of the present invention.

6 is a diagram showing a relationship between a gap Gd2 between a pre-doctor plate and a developing sleeve in the developing device shown in FIG. 1 and a toner density.

FIG. 7 is a correction table of a distance Gd2 between a pre-doctor plate and a developing sleeve corresponding to a detected temperature detected in one embodiment of the developing device according to claim 1, 2 or 3.

FIG. 8 is a schematic configuration diagram showing a conventional developing device.

[Explanation of symbols]

 1, 31 photosensitive drum 2, 32 developing casing 3, 33 developer carrier 3a developing sleeve 3b magnet roller 3c magnetic pole 4, 34 doctor (first developer amount regulating member) 5, 35 pre-doctor (second developer) Amount regulating member) 5a Pre-doctor fixing member 5b, 25b Pre-doctor plate 6, 36 Developer storage case 6a, 36a Developer storage section 6b, 36b Developer retention section 7, 37 Toner hopper 7a, 37a Toner supply port 8, 38 Agitator 22 Drive means 25c gear

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshihiko Yamanaka 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H027 DA01 DA11 DA14 DD07 ED08 EF09 2H077 AA11 AB04 AD02 AD06 AD13 AD18 AD32 BA01 BA08 CA03 DA10 DA18 DA72 DA80 EA03 EA16

Claims (10)

[Claims] 1. A developer carrier rotatably supported, having a magnetic field generating means therein, carrying and transporting a two-component developer containing a toner and a magnetic carrier, and a surface of the developer carrier. A first developer amount regulating member that is disposed close to and regulates the amount of the two-component developer carried on the surface of the developer carrying member, with respect to the first developer amount regulating member,
A second developer amount regulating member disposed on the upstream side in the rotation direction of the developer carrying member, wherein at a distance between the first developer amount regulating member and L1 in a circumferential direction of the developer carrying member, A second developer amount regulating member disposed in proximity to the developer carrier; and a space partitioned by the first developer amount regulating member and the second developer amount regulating member. A developer accommodating chamber provided for accommodating a two-component developer scraped from the surface of the developer carrier by the first developer amount regulating member; accommodating toner and supplying the toner to the developer carrier side A developing device having a toner hopper, wherein the second developer amount regulating member is supported so as to be able to approach and separate from the developer carrier. 2. A driving device for driving the second developer amount regulating member, wherein the second developer amount regulating member is supported via the driving unit, and the developer carrier The developing device according to claim 1, wherein the developing device is moved toward and away from the developing device. 3. The image forming apparatus according to claim 1, further comprising a temperature detecting unit, wherein the second developer amount regulating member is moved toward and away from the developer carrier in accordance with a detection result of the temperature detecting unit. The developing device according to claim 1 or 2, wherein 4. A method according to claim 1, further comprising a humidity detecting unit, wherein the second developer amount regulating member is moved toward and away from the developer carrier in accordance with a detection result of the humidity detecting unit. The developing device according to claim 1, 2 or 3, wherein 5. The apparatus according to claim 1, wherein the second developer amount regulating member is movable within a predetermined range. Developing device. 6. An image forming unit including an image reading unit, a photoconductor, a developing unit, a transfer unit, and a fixing unit.
An image forming apparatus including a paper feeding unit and an operation unit, wherein the developing unit is rotatably supported, has a magnetic field generating unit inside, and has a two-component developer including a toner and a magnetic carrier. A developer carrying member that carries and transports the first developer, and a first developer that is disposed close to the surface of the developer carrying member and regulates an amount of a two-component developer carried on the surface of the developer carrying member. A developer amount regulating member, a second developer amount regulating member disposed on a rotation direction upstream side of the developer carrier with respect to the first developer amount regulating member, At an interval between the first developer amount regulating member and L1 in the circumferential direction,
A second developer amount regulating member disposed in proximity to the developer carrier; and a space partitioned by the first developer amount regulating member and the second developer amount regulating member. A developer accommodating chamber provided for accommodating a two-component developer scraped from the surface of the developer carrier by the first developer amount regulating member; accommodating toner and supplying the toner to the developer carrier side The second developer amount regulating member, the second developer amount regulating member is supported so as to be able to approach and separate from the developer carrier, and the developing amount of the second developer amount regulating member is The image forming apparatus is characterized in that proximity to and separation from the agent carrier is set by operating the operation unit. 7. The developing means comprises a driving means for moving the second developer amount regulating member toward and away from the developer carrier, and wherein the second developer amount regulating member comprises: The image forming apparatus according to claim 6, wherein the image forming apparatus is supported via the driving unit, and is moved toward and away from the developer carrier. 8. A temperature detecting means for detecting a temperature in the vicinity of the developing device, wherein the second developer amount regulating member is provided on the developer carrier in accordance with a detection result of the temperature detecting means. The image forming apparatus according to claim 6, wherein the image forming apparatus is moved toward and away from the image forming apparatus. 9. A humidity detecting means for detecting humidity near the developing device, wherein the second developer amount regulating member is provided on the developer carrier in accordance with a detection result of the humidity detecting means. 9. The image forming apparatus according to claim 6, wherein the image forming apparatus is approached and separated from the image forming apparatus. 10. The apparatus according to claim 6, wherein the second developer amount regulating member is movable within a predetermined range. Image forming device.