JP2003287950A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device and an image forming apparatus capable of stably detecting toner concentration at high precision even when the quantity of developer pooled on the upstream side of a developer restricting means inside a developing container is reduced. <P>SOLUTION: Pooling of the developer is formed in a communicating part from an agitating chamber 4 to a developing chamber 3 by installing the agitating chamber 4 below the developing chamber 3. A developer concentration detecting device 100 is installed in the communicating part. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine and a laser beam printer using an electrophotographic system or an electrostatic recording system in which a developer is attached to a latent image formed on an image carrier to form a visible image. And the like regarding the image forming apparatus.

[0002]

2. Description of the Related Art An image forming apparatus employing an electrophotographic system or an electrostatic recording system, especially a color image forming apparatus for forming a full-color or multi-color image by the electrophotographic system,
Most developing devices use a two-component developer in which a non-magnetic toner and a magnetic carrier are mixed in terms of color developability and color mixture.

As is well known, the developing method using this two-component developer imparts an electric charge to the toner by frictional electrification generated between carrier particles and toner particles, and the charged toner is applied to the latent image. It is a method of forming an image by electrostatically adhering.

For example, as shown in FIG. 6, a developing device 1 using a two-component developer (hereinafter referred to as "developer") D.
Is equipped with a developing sleeve 8 as a developer bearing member so as to face the electrostatic latent image formed on the surface of the photosensitive drum 30 which is an image bearing member.

The developing sleeve 8 is rotatably supported in the developing container 2 in the direction of the arrow in the figure, and a fixed magnet roller 9 as a magnetic field generating means is provided therein.

The developer D is so-called, that is, the carrier to which the toner is attached stands up due to the magnetic force of the magnet roller 9.
The latent image is developed by being carried by the developing sleeve 8 in the state of a magnetic brush and conveyed to the developing nip N which is a developing area facing the electrostatic latent image on the photosensitive drum 30.

By the way, the toner concentration of the developer D is detected by a developer concentration detecting device (hereinafter referred to as "ATR") 100, and the inside of the developing device is controlled to have a desired toner concentration. This makes it possible to stably form a high-quality image.

Several methods have been proposed so far for detecting the concentration of the developer. However, the magnetic detection method and the optical detection method have been most widely used because of their low cost. is there. Among them, in the magnetic detection method, a magnetic sensor is provided as an ATR in the developing device, and the toner concentration of the developer is detected by detecting a change in magnetic permeability due to a difference in toner concentration of the developer in the sensor section.

More specifically, since the magnetic sensor responds to the difference in magnetic flux density of the magnetic substance to be detected, it is possible to detect how much magnetic substance is present on the detection surface of the magnetic sensor, and Since the toner is a non-magnetic substance, but the carrier is a magnetic substance, the amount of the carrier in the developer can be detected, and as a result, the toner concentration can be relatively detected.

However, in the magnetic detection method, not the amount of toner is directly detected but the amount of carrier is detected. Therefore, not only when the toner concentration in the developer changes, but also the bulk density of the developer changes. In some cases, the output value of the magnetic sensor changes. Therefore, the detection accuracy may be slightly inferior to other methods, and erroneous detection may occur. In a color image forming apparatus that forms a color image using multicolor toners, for example, when the toner density deviates from a set value due to erroneous detection of only one color, the image density changes by that color, resulting in a change in color appearance. The problem of occurring can occur.

Therefore, conventionally, in a color image forming apparatus which is required to have higher image quality, an optical detecting means as described below is often used as a developer concentration detecting apparatus.

FIG. 7 shows an ATR100 using optical detection means.
The schematic configuration of is shown.

As shown in FIG. 7, the ATR 100 has a light-transmissive detection window 102 at the opening of a box-shaped main body 101, and infrared rays are emitted on the back side of the detection window 102 (inside the main body 101). It has a unit 103 and a light receiving unit 104. This ATR 100 is arranged so as to face the surface of the developing sleeve 8 of the developing device 2, and the toner concentration of the developer D carried on the surface of the developing sleeve 8 and used for development is detected by the ATR 100.

That is, the light from the light emitting portion 103 is detected by the detection window 10.
After passing through 2, the developer D on the surface side of the detection window 102 is irradiated. Then, the reflected light from the developer D is detected by the detection window 1
After passing through 02, it reaches the light receiving unit 104. Depending on the amount of the reflected light reaching the light receiving unit 104 at this time, the developer D
The toner concentration inside is detected.

Here, the developer D is mainly composed of a carrier and a toner, but the carrier has almost no infrared ray reflecting ability, and the reflected light received by the light receiving section 104 is mostly due to the toner. . Therefore, when the developer D contains a large amount of toner (that is, the toner concentration is high), the reflected light is large, and conversely, when the toner is small (that is, the toner concentration is low), the reflected light is small. There is a correlation between the concentrations. Therefore, by knowing the relationship between the reflected light amount and the toner density in advance, the toner density at that time can be accurately detected based on the reflected light amount.

By the way, the toner in the developer D is easily charged on the surface of the detection window 102 because it is charged to a predetermined polarity (positive or negative). Since the amount of reflected light is detected by the light passing through the detection window 102, when toner adheres to the surface of the detection window 102, the adhered toner blocks the light at the time of irradiation and reflection, so that the amount of reflected light is accurately detected. Is hindered.

Therefore, although a cleaning mechanism for cleaning the toner adhering to the surface of the detection window 102 is required, conventionally, a complicated cleaning member is not newly provided, and the ATR 100 is opposed to the developing sleeve 8. Place and develop sleeve 8
There are many methods in which the toner adhering to the surface of the detection window 102 is cleaned by rubbing the detection window 102 with the developer D conveyed on the surface of the detection window 102.

At this time, it is preferable that the mounting position of the ATR 100 is opposed to the position where the developer D is being compressed while being conveyed to some extent. At the position where the developer D is not transported, the cleaning ability is poor in the first place, but at the position where the developer D is not compressed even when the developer D is transported, the force for scraping the toner on the detection window 102 of the developer D is weak, The scraping is uneven and the detection accuracy is not stable.

From the above points, if the ATR 100 is attached to the position on the developing sleeve 8 where the regulating blade 10 as the developer regulating means regulates the developer D, the developer D becomes
Since it is regulated and accumulated, it is conveyed by the developing sleeve 8 while being compressed to a certain degree, and the developer D
The toner concentration in the developer D can be stably detected by rubbing and cleaning the detection window 102 of the TR 100.

As described above, as the amount of the developer D accumulated on the upstream side of the developer regulating blade 8 in the developer container 2 increases, the toner concentration detection accuracy increases and becomes stable, but the following problems occur. .

The magnet roller 9 of the conventional developing device 1 shown in FIG. 6 has five magnetic poles N1, S1, N2, N3 and S.
Have two. Developer D housed in developer container 2
Is supplied to the developing sleeve 8 while being circulated in the container 2 by stirring and carrying the carrying screws 5 and 6. The developer D supplied to the developing sleeve 8 is drawn up onto the developing sleeve 8 by the magnetic pole N2 of the magnet roller 9,
With the rotation of the developing sleeve 8, the developing sleeve 8 is conveyed in the order of magnetic pole S2 → magnetic pole N1 → magnetic pole S1, and reaches the developing nip N where the developing sleeve 8 and the photosensitive drum 30 face each other. During the conveyance, the developer D is magnetically regulated in layer thickness by the regulating blade 10 in cooperation with the magnetic pole N1, and a thin layer of the developer D is formed on the developing sleeve 8.

In the above-described conventional developing device, the developer D that has been removed from the developing sleeve 8 due to the regulation by the regulating blade 10 is on the upstream side in the rotational direction of the developing sleeve 8 of the regulating blade 10 due to the magnetic force of the magnetic poles N2 and S2. It is kept nearby and accumulates in large quantities.

Since the developer D is successively conveyed by the developing sleeve 8 to the developer accumulated in the vicinity of the regulation blade 10, a large pressure is applied to the accumulated developer D, and the developer D becomes a magnetic carrier of the developer. When the toner and the toner are pressed, a phenomenon occurs in which fine particles such as silica (SiO ₂ ) externally added to the toner are embedded in the toner.

Furthermore, due to the friction between the toner and the magnetic carrier, the particle shape of the toner itself becomes rounded and rounded. Further, when it is used for a long time, the toner adheres to the surface of the magnetic carrier and cannot be removed, so-called a spent phenomenon occurs.

When such deterioration of the developer occurs, the triboelectric charge amount of toner (so-called tribo) changes with use time, the developability of the toner changes, and the image density changes, and the magnetic carrier and the photosensitive drum. The adhesion of the toner to the toner increases, and it becomes difficult to perform development and transfer corresponding to the electric field, resulting in image unevenness in which the toner is partially lost. That is, with use, there is a possibility that the image will have an extremely poor impression as compared with the initial image.

As measures against the above problems, some methods for reducing the amount of accumulated developer D have been proposed. In Japanese Laid-Open Patent Publication No. 11-338259, FIG.
As shown in FIG. 3, by causing the regulating blade 10 to face one side of the N2 pole and the N3 pole that form the repulsive magnetic field, only the developer D retained at the N2 pole is accumulated on the upstream side of the regulating blade 10, which is different from the conventional case. This prevents large developer pools.

As a result, no large pressure is applied to the developer, and deterioration of the magnetic carrier and the non-magnetic toner of the developer can be largely prevented even when used for a long time.

The technology for preventing the deterioration of the developer by reducing the agent accumulation as described above is in the process of further speeding up and improving the image quality of printers and copying machines using the electrophotographic method. It will be an important technology. In particular,
When the rotation speed of the developing sleeve exceeds 350 mm / sec, it further increases to 500 mm / sec, which becomes particularly important.

[0029]

However, if the restricting blade 10 is simply opposed to the N2 pole that forms the repulsive magnetic field, there is no space for mounting the ATR 100 upstream of the restricting portion as shown in FIG.

In order to mount the ATR100, N
When the two poles and the regulating blade 10 are arranged above, the N2 pole is on one side of the repelling pole, so that the developer is hard to collect, so that it is difficult to scoop up the developer D from the developing chamber 5 to the N2 pole, and the developer D on the developing sleeve 8. The amount of developer conveyed tends to be uneven.

Even if the ATR 100 could be attached, since the amount of the developer pool upstream of the regulating portion is reduced as a measure against the developer deterioration, as described above, the toner attached to the developer detection window is removed. The power to scrape is weakened,
There is a problem that uneven scraping tends to occur and it is not stable. A member for cleaning the detection window of the ATR may be provided separately, but it is costly, and there are many problems such as securing a place for attachment and life.

The present invention has been made in view of the above problems, and an object of the present invention is to stably maintain even when the amount of the developer accumulated upstream of the developer regulating means in the developing container is reduced. It is an object of the present invention to provide a developing device and an image forming apparatus capable of accurately detecting a toner density.

[0033]

The above object is achieved by the developing device and the image forming apparatus according to the present invention. In summary, according to one aspect of the present invention, a rotatable developing device incorporating magnetic field generating means for carrying a developer containing toner and a magnetic carrier for developing a latent image formed on an image carrier. An agent carrying member, a developer restricting means for restricting the layer thickness of the developer carried on the developer carrying member and conveyed to a developing area facing the image carrying member, and a developer being supplied to the developer carrying member. A developing chamber, an agitating chamber disposed below the developing chamber, for collecting the developer after passing through the developing area from the developer carrying member, and the developing chamber and the both ends of the agitating chamber in the longitudinal direction. Includes a first communication portion and a second communication portion that communicate with each other, and first and second conveying members that convey the developer while stirring the developer chamber and the stirring chamber. And these first and second communicating members are connected by these conveying members. The developer is conveyed between the developing chamber and the stirring chamber via the second communicating portion, and the developer is dropped from the developing chamber to the stirring chamber via the second communicating portion. In the developing device for supplying the developer to the developer carrying member while circulating the magnetic field,
A first magnetic pole located downstream of the developing region in the rotation direction of the developer carrier and inside the developing container; and a first magnetic pole downstream of the first magnetic pole in the direction of rotation of the developer carrier. A second magnetic pole of the same polarity located adjacent to
The developer regulating means is disposed in the vicinity of the facing position of the second magnetic pole, and a developer concentration detecting device for detecting the toner concentration in the developer is installed in the vicinity of the first communicating portion. A developing device is provided. The stirring chamber may be arranged obliquely below the developing chamber.

According to another aspect of the present invention, a rotatable developing device incorporating magnetic field generating means for carrying a developer containing a toner and a magnetic carrier for developing a latent image formed on an image carrier. An agent carrying member, a developer restricting means for restricting the layer thickness of the developer carried on the developer carrying member and conveyed to a developing area facing the image carrying member, and a developer being supplied to the developer carrying member. A developing chamber, an agitating chamber disposed above the developing chamber, for collecting the developer after passing through the developing area from the developer carrier, and the developing chamber and the agitating chamber in the vicinity of both longitudinal ends thereof. Includes a first communication portion and a second communication portion that communicate with each other, and first and second conveying members that convey the developer while stirring the developer chamber and the stirring chamber. And these conveying members enable the first continuous The developer is conveyed between the developing chamber and the agitating chamber through the second section, and the developer is dropped from the agitating chamber to the developing chamber through the second communicating section, thereby developing between the developing chamber and the agitating chamber. In a developing device that supplies the developer to the developer carrying member while circulating the developer, the magnetic field generating means is located in the developing container at a position downstream of the developing area in the rotation direction of the developer carrying member. And a second magnetic pole having the same polarity, which is located on the downstream side of the first magnetic pole in the rotation direction of the developer carrier and adjacent to the first magnetic pole. Is provided in the vicinity of the facing position of the second magnetic pole, and a developer concentration detecting device for detecting the toner concentration in the developer is installed in the vicinity of the first communicating portion. It The developing chamber is
It can be arranged diagonally below the stirring chamber.

According to one embodiment of the present invention, the detection surface of the developer concentration detecting device faces obliquely upward.

According to another embodiment of the present invention, the first
And the second conveying member is a first screw and a second screw, respectively, and the developer concentration detecting device is disposed between a plane including the axis of the first screw and a plane including the axis of the second screw. Is located in.

According to another embodiment of the present invention, the developer concentration detecting device is present on the front surface side of the detection window by a light emitting portion and a light receiving portion arranged on the back surface side of the light transmitting detection window. An optical detection device for detecting the toner concentration in the developer. According to another embodiment, the developer concentration detecting device may be a magnetic detecting device that detects magnetic permeability with a magnetic sensor, and the developing device may develop with a developer containing black toner.

According to another embodiment of the present invention, the moving speed of the developer carrying member is 350 mm / sec or more.

According to another aspect of the present invention, there is provided an image forming apparatus characterized in that an electrostatic latent image is formed on an image carrier and the latent image is made a visible image by the developing device. To be done.

According to another aspect of the present invention, electrostatic latent images are formed on a plurality of image bearing members, and the latent images are converted into visible images by the above-mentioned developing devices each having a different color developer. A magnetic detection device is used as a developer concentration detecting device for a developing device that develops with a developer containing black toner, and a developing device that develops with a developer containing toner of other colors There is provided an image forming apparatus characterized by using an optical detection device as the agent concentration detection device.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION A developing device and an image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 FIG. 3 schematically shows the overall structure of an electrophotographic full-color image forming apparatus which is an embodiment of the image forming apparatus of the present invention.

In this embodiment, the full-color image forming apparatus is yellow Y, magenta M, cyan C, black Bk.
Each station has substantially the same configuration and forms a yellow (Y), magenta (M), cyan (C), and black (Bk) image in a full-color image, respectively. In the following description, for example, the term “developing device 1” refers to the developing device 1Y, the developing device 1M, the developing device 1C, and the developing device 1K in each station.

In the full-color image forming apparatus of this embodiment,
The photosensitive drum 30, which is an image carrier, is rotatably provided. The photosensitive drum 30 is uniformly charged by a primary charger 21, and is modulated by a light emitting element 22 such as a laser according to an information signal. Exposed to light to form an electrostatic latent image. The electrostatic latent image is visualized as a toner image by the developing device 1. Next, the visible image is transferred to the transfer charger 2
3, the transfer sheet 27 is transferred onto the transfer sheet 27 conveyed by the transfer sheet conveying sheet 24, and further fixed by the fixing device 25 to obtain a permanent image. Further, the transfer residual toner on the photosensitive drum 30 is removed by the cleaning device 26. Further, the toner consumed by the image formation is replenished from the toner replenishing tank 20.

As described above, the charging device 2 is provided around one photosensitive drum 30 along the rotation direction of the photosensitive drum 30.
1, an exposure device 22, a developing device 1, a transfer device 23, and a cleaning device 26 are sequentially arranged. The fact that the image forming means is configured by these is the same as in the prior art.

The feature of this embodiment lies in the construction of the developing device 1. FIG. 1 shows an embodiment of the developing device 1.

Referring to FIG. 1, in the present embodiment, the developing device 1 includes a photosensitive drum 30 of a developing container 2 in which a two-component developer containing a non-magnetic toner and a magnetic carrier is stored, as in the conventional developing device. At the position corresponding to the development area facing
The developing sleeve 8 as a developer carrying means is rotatably arranged so as to be partially exposed. A magnet roller 9 composed of five poles, that is, N1, S1, N3, N2, and S2 is fixedly arranged in the developing sleeve 8 so as to substantially oppose to the N2 pole of N2 and N3 forming a repulsive magnetic field. A regulating blade 10 as a developer regulating means is arranged in the. As a result, the amount of developer accumulated on the upstream side of the regulation blade 10 is reduced and the deterioration of the developer is suppressed. However, as described in the related art, when the optical ATR 100 is attached at this position, it becomes unstable.

The mounting position of the ATR 100 is preferably arranged so as to face the position where the developer is conveyed while being compressed to some extent, but in the structure of the developing device described in the conventional example as shown in FIG. There is no place that meets the conditions.

Therefore, in this embodiment, the structure of the developing device described in the conventional example is changed in the following points.

That is, in this embodiment, the developing container 2
The developing chamber 3 and the agitating chamber 4, which are partitioned by a partition wall 7 extending in the vertical direction to the inside of the drawing, are not arranged substantially horizontally as in the conventional technique, but the developing chamber 3 and the agitating chamber 4 are almost the same. They are arranged vertically above and below. The first conveying screw 5 is arranged at the bottom of the developing chamber 3 substantially parallel to the axial direction of the developing sleeve 8 and rotates to convey the developer in the developing chamber 3 in one direction along the axial direction. To do. The second conveying screw 6 is arranged at the bottom of the stirring chamber 4 substantially parallel to the first conveying screw 5 and conveys the developer in the stirring chamber 4 in the opposite direction to the first conveying screw 5.

In this manner, the developer is conveyed by the rotation of the first and second conveying screws 5 and 6, and the developer passes through the openings 11 and 12 at both ends of the partition wall 7 to the developing chamber 3 and the stirring chamber 4. Circulated between.

FIG. 2 is a schematic sectional view of the developing device 1 taken in the direction of the developing sleeve 8, that is, taken along line II-II in FIG.

As shown in FIG. 2, the developing device 1 of this embodiment.
Since the developing chamber 3 and the agitating chamber 4 are arranged in the vertical direction, the developer from the developing chamber 3 to the agitating chamber 4 is opened by the opening 12
The developer from the stirring chamber 4 to the developing chamber 3 passes through the opening 11 and from the bottom to the top. In particular, the developer is delivered from the stirring chamber 4 to the developing chamber 3 so as to be pushed upward from below by the pressure of the developer accumulated at the end. Therefore, the developer is conveyed while being considerably compressed in the transfer section (communication section) 11.

When the developer is used as a cleaning means for the detection window 102 of the ATR 100, the optical ATR 10
As described above, the position suitable for the attachment of 0 is the place where the developer is conveyed while being compressed to some extent, but the delivery unit 11 satisfies this condition.

Therefore, in this embodiment, as in the conventional example, the AT is provided in the developer reservoir portion on the upstream side of the developer regulating blade 10.
Instead of arranging R100, the developing chamber 3 and the agitating chamber 4 are arranged vertically, and the ATR1 is provided in the developer delivering portion 11 from the agitating chamber 4 arranged below to the developing chamber 3 arranged above.
00 was placed.

More specifically, the mounting position of the ATR 100 will be described. Basically, the ATR 100 may be mounted at any position of the transfer unit 11, but the following points should be noted.

First, in order to stably control the concentration, A
It is necessary for the developer to be stably present on the detection surface 102 of the TR 100, and if the detection window 102 of the ATR 100 is provided near the developer surface above the transfer section 11, the temperature and humidity change and the flow of the developer flows. When the developer surface changes due to a change in properties, and especially when the developer surface lowers, the cleaning of the detection window 102 with the developer becomes insufficient and the density control becomes unstable.

In general, the screw is somewhat eccentric with respect to the shaft regardless of the material and structure.
In this embodiment as well, a gap is provided between the blade of the screw 6 and the bottom of the stirring chamber 4 so as not to contact the bottom of the stirring chamber 4. However, due to this gap, the developer at the bottom of the stirring chamber 4 is not directly conveyed by the screw 6 and tends to stay. Therefore, when the detection window 102 of the ATR 100 is provided at the bottom of the stirring chamber 4, the ability to clean the detection window 102 of the developer is poor and it is not suitable as the mounting position of the ATR 100.

Further, the fact that the toner is slightly staying means that the amount of the developer is not changed and the response to the concentration fluctuation is weak. From this point as well, the bottom of the stirring chamber 4 is A.
Not very suitable as a mounting position for TR100.

Considering the stability, it is preferable that the ATR 100 is installed above the second conveying screw 6 in the stirring chamber 4 and below the first conveying screw 5 in the developing chamber 3. That is, the ATR 100 is arranged between the plane including the axis of the first conveying screw 5 and the plane including the axis of the second conveying screw 6.

Embodiment 2 The second embodiment is almost the same in configuration and operation as the first embodiment except for the points described in detail below, so that it will be described with reference to FIGS. 1 and 2.

Regarding the ATR 100, the case where the optical detection system is used as the ATR has been described in the first embodiment, but in the present embodiment, the magnetic detection system is used as the ATR 100.

As described in the prior art, in the case of the magnetic detection system, the carrier density which is not the toner in the developer but the magnetic substance is detected to indirectly detect the toner concentration. If the density changes, false detection will occur. For example, when the bulk density of the developer increases due to the influence of temperature and humidity, the number of carriers in the magnetic detection range increases even if the toner concentration is the same, and therefore it is falsely detected that the toner concentration is relatively lower than the actual value.

Therefore, in a place where the developer is compressed in advance such as the developer delivering section 11, even if the magnetic detection method ATR is used, the bulk density change of the developer is small and the density can be stably detected. .

Although the magnetic detection method is inferior in detection accuracy to the optical detection method, it has an advantage that the cost is low, and the magnetic detection method may be used properly according to the required image quality and price of the product. Further, when a developer composed of black (Bk) toner and a carrier is used, since the color of the carrier is mostly brown or black, it is difficult to distinguish the toner and the carrier in the optical detection method. However, in that case, the magnetic detection method ATR is used only for the black (Bk) station, and the yellow (Y), magenta (M), and cyan (C) stations use the optical detection ATR by giving priority to stability. It is valid.

Third Embodiment FIG. 4 shows a third embodiment. Except for the points described in detail below, the structure and operation are almost the same as those of the first embodiment, and therefore, the same components are designated by the same reference numerals and the description thereof is omitted.

While the developer circulates, the developer is transferred from the stirring chamber 4 to the developing chamber 3 by being pushed up from the bottom to the top by the pressure of the developer accumulated at the end. Here, since the developer is compressed to some extent, the optical ATR could be used, but if the pressure here becomes too strong, the developer may deteriorate in this portion. In particular, when the developing chamber 3 and the agitating chamber 4 are vertically arranged substantially vertically as in the first embodiment, the pressure of the developer transfer portion 11 becomes too strong and the developer is apt to deteriorate.

In the recent trend of increasing the speed of copying machines and printers, there is an increasing number of cases in which a toner that is softer than the conventional one is used so that fixing can be performed easily. It is believed that

In the developing device of this embodiment, the developing chamber 3 and the agitating chamber 4, which are defined by the partition wall 7 extending in the direction perpendicular to the surface of the paper in the developing container 2, are substantially vertical as in the first embodiment. It is characterized in that the agitating chamber 4 is not arranged vertically but in a diagonally lower position closer to the developing sleeve 8 as compared with the developing device of the first embodiment. Further, the first and second conveying screws 5 and 6 as a developer stirring / conveying means are also provided in the developing chamber 3 and the stirring chamber 4, respectively.
It is arranged at the bottom along the axial direction of the developing sleeve 8.

By arranging the developing chamber 3 and the agitating chamber 4 at an angle, the transfer from the lower agitating chamber 4 to the upper developing chamber 3 can be carried out as compared with the case of vertically arranging as in the first embodiment. It will be easier and the pressure will be somewhat relieved. This suppresses the deterioration of the developer. The effect can be expected if the upper and lower screws 5 and 6 are tilted at 30 ° or more with 0 ° when they are arranged vertically.

Here, when the pressure received by the developer in the developer transfer portion 11 becomes small, the cleaning ability of the detection window by the developer becomes weak when the transfer portion 11 is equipped with an optical ATR, and the density detection is stabilized. There is concern that it will not do so.

Therefore, in the present embodiment, as shown in FIG. 4, in the transfer section 11 from the stirring chamber 4 to the developing chamber 3, the optical ATR 100 connects the developing chamber 3 and the stirring chamber 4 to the outer wall of the developing container 2. Diagonally along the (detection window 10
It is preferable to mount it so that 2 faces diagonally upward,
As a result, the detection window 102 is directly subjected to the gravity due to the weight of the developer in addition to the pressure due to the conventional pushing up.
In the vicinity of the detection window, the developer is conveyed while being compressed, which is an ideal state.

Fourth Embodiment FIG. 5 shows a fourth embodiment. Except for the points to be described in detail below, the structure and operation are almost the same as those of the first to third embodiments, and therefore, the same components are designated by the same reference numerals and the description thereof is omitted.

In the present embodiment, unlike the first to third embodiments, the developing chamber 3 for supplying the developer to the developing sleeve 8 is provided on the lower side, and the stirring chamber 4 for collecting the developer is provided on the upper side.
Was set up. Along with this, the rotation direction of the developing sleeve 8 is also opposite to that of the first to third embodiments, and the regulating blade 10 as the developer regulating member is also the opposite of the repelling poles from the first to third embodiments. It was made to face the N3 pole on the side.

Even in such a structure, since the regulating blade 10 faces one side (N3 pole) of the pole forming the repulsive magnetic field, the developer accumulation in the vicinity of the regulating blade 10 is small and the deterioration of the developer is reduced. On the other hand, the blade 1
Since there is no space for mounting the ATR 100 in the vicinity of 0, in the present embodiment, the developer delivering section 11 for pushing up the ATR 100 from the developing chamber 3 to the stirring chamber 4 is provided.
It is provided in.

In the structure as in this embodiment, the developer is pushed up from the lower developing chamber 3 to the upper stirring chamber 4 in the developer transfer section 11 provided at the ends of the developing chamber 3 and the stirring chamber 4. Not only is the developing sleeve 8 carrying the developer on the surface thereof, but the developer is being pumped up to the upper stirring chamber 4, so that the pressure due to the pushing up at the transfer portion 11 at the end is the first to third embodiments. This is effective when the developer deterioration is small compared to the example and the developer deterioration is a concern.

[0077]

As described above, according to the present invention, the stirring chamber is moved from the stirring chamber to the developing chamber by disposing the stirring chamber below the developing chamber or by disposing the developing chamber below the stirring chamber. Alternatively, a developer pool is formed in a communication part from the developing chamber to the stirring chamber, and a developer concentration detecting device is provided in the communication part, so that the developer pooled upstream of the developer regulating means in the developing container. Even when the amount of toner is reduced, it is possible to stably and accurately detect the toner density.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a developing device of the present invention.

2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 is a schematic sectional view showing a schematic configuration of an embodiment of the image forming apparatus of the present invention.

FIG. 4 is a schematic cross-sectional view showing another embodiment of the developing device of the invention.

FIG. 5 is a schematic cross-sectional view showing another embodiment of the developing device of the invention.

FIG. 6 is a schematic sectional view of a conventional developing device.

FIG. 7 is a schematic cross-sectional view showing a schematic configuration of an ATR (developer concentration detecting device).

FIG. 8 is a schematic sectional view of a conventional developing device.

[Explanation of symbols]

1 Development device 2 Development container 3 development room 4 stirring chamber 5, 6 Conveyor screw 7 partition 8 developing sleeve 9 Magnet roll 10 regulation blade 11, 12 Communication part 30 photosensitive drum 100 developer concentration detector 102 detection window

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Claims (12)

[Claims] 1. A developer carrying a toner and a magnetic carrier for developing a latent image formed on an image carrier is carried.
A rotatable developer carrying member having a built-in magnetic field generating means; and a developer restricting device for restricting the layer thickness of the developer carried on the developer carrying member and conveyed to a developing area facing the image carrying member, A developing chamber for supplying the developer to the developer carrying member; a stirring chamber disposed below the developing chamber for collecting the developer after passing through the developing area from the developer carrying member; A first communication part and a second communication part are provided near both ends of the stirring chamber in the longitudinal direction, respectively. The first communication part and the second communication part communicate with each other, and the developer is stirred and conveyed into the developing chamber and the stirring chamber. And a second transport member, which transports the developer from the stirring chamber to the developing chamber via the first communicating portion, and the developing chamber via the second communicating portion. From the developer into the stirring chamber In the developing device for supplying the developer to the developer carrying member while circulating the developer between the developing chamber and the agitating chamber, the magnetic field generating means includes a rotating direction of the developer carrying member from the developing area. A first magnetic pole located on the downstream side and inside the developing container; and a second magnetic pole located on the downstream side of the first magnetic pole in the rotation direction of the developer carrier and adjacent to the first magnetic pole. A developer concentration detecting device that has a magnetic pole, the developer regulating means is disposed in the vicinity of the facing position of the second magnetic pole, and detects the toner concentration in the developer in the vicinity of the first communicating portion. A developing device that is installed. 2. The developing device according to claim 1, wherein the stirring chamber is arranged obliquely below the developing chamber. 3. A developer containing a toner and a magnetic carrier for developing the latent image formed on the image carrier is carried.
A rotatable developer carrying member having a built-in magnetic field generating means; and a developer restricting device for restricting the layer thickness of the developer carried on the developer carrying member and conveyed to a developing area facing the image carrying member, A developing chamber for supplying the developer to the developer carrying member; a stirring chamber disposed above the developing chamber for collecting the developer after passing through the developing area from the developer carrying member; A first communication part and a second communication part are provided near both ends of the stirring chamber in the longitudinal direction, respectively. The first communication part and the second communication part communicate with each other, and the developer is stirred and conveyed into the developing chamber and the stirring chamber. And a second conveying member, which conveys the developer from the developing chamber to the stirring chamber via the first communicating portion, and the stirring chamber via the second communicating portion. By dropping the developer from the In the developing device for supplying the developer to the developer carrying member while circulating the developer between the developing chamber and the agitating chamber, the magnetic field generating means includes a rotating direction of the developer carrying member from the developing area. A first magnetic pole located on the downstream side and inside the developing container; and a second magnetic pole located on the downstream side of the first magnetic pole in the rotation direction of the developer carrier and adjacent to the first magnetic pole. A magnetic pole, the developer regulating means is disposed in the vicinity of the facing position of the second magnetic pole, and a developer concentration detecting device for detecting the toner concentration in the developer is installed in the vicinity of the first communicating portion. A developing device characterized in that 4. The developing device according to claim 3, wherein the developing chamber is arranged obliquely below the stirring chamber. 5. The developing device according to claim 2, wherein the detection surface of the developer concentration detecting device faces obliquely upward. 6. The first and second conveying members are first and second screws, respectively, and the developer concentration detecting device includes a plane including an axis of the first screw and the second screw. The developing device according to claim 1, wherein the developing device is arranged between planes including a shaft of a screw. 7. The developer concentration detecting device detects the toner concentration in the developer existing on the front surface side of the detection window by a light emitting portion and a light receiving portion arranged on the back surface side of the light transmissive detection window. An optical detection device.
6. The developing device according to any one of item 6. 8. The developing device according to claim 1, wherein the developer concentration detection device is a magnetic detection device that detects magnetic permeability with a magnetic sensor. 9. The developing device according to claim 8, wherein the developing device develops with a developer containing black toner. 10. The moving speed of the developer carrying member is 350.
It is mm / sec or more, It is characterized by the above-mentioned.
The developing device according to any one of 1. 11. An image characterized in that an electrostatic latent image is formed on an image carrier, and the latent image is made into a visible image by the developing device according to any one of claims 1 to 10. Forming equipment. 12. An electrostatic latent image is formed on a plurality of image carriers,
An image forming apparatus for forming the latent image into a visible image by the developing device according to any one of claims 1 to 10 having different color developer, wherein the developer contains black toner. A magnetic detecting device is used as a developer concentration detecting device for a developing device for developing, and an optical detecting device is used as a developer concentration detecting device for a developing device for developing with a developer containing toner of other colors. Image forming apparatus.