JPH11194601A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous decision in the case of detecting the residual amount of developer by providing a developer damming means and preventing the inflow of the developer which is not desired for the purpose of detecting the existence of the developer in the detection area by a developer detector in the developing device. SOLUTION: The toner sensor 26 is positioned below a 1st agitator in the developing device, attached to a lower casing 27 and has a width (a) as a sensor. A partition plate 50 having a width (b) larger than the width (a) is provided at a right angle to a toner carrying direction at a position where the horizontal surface of the casing 27 is crossed with an R surface. The plate 50 exists between the 2nd agitator and the 1st agitator in the developing device. In a area where the plate 50 exists, toner temporarily carried on the left side of the plate 50 and existing at the height of the plate 50 or under it is not restored toward the 1st agitator even by the rotating operation of the 2nd agitator. Namely, the needless inflow of the toner to the sensor 26 is prevented by the plate 50 of the sensor 26 part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art FIG. 1 is a front view showing a schematic structure of a conventionally proposed copying machine. This copier has first and second
The two developing devices 10 and 20 are provided. The second developing device 20 includes a casing 27 having an opening facing the surface of the photosensitive drum 1 serving as an image bearing member, a part exposed through the opening, and a counterclockwise arrow at a predetermined linear velocity. Developing roller 21 as a toner carrier, which is rotationally driven, toner supply roller 3 which is rotationally driven clockwise as indicated by an arrow, and a hopper section which is rotationally driven clockwise as indicated by an arrow to form a right side in a casing. The first and second agitators 23 and 24 as developer agitating means for agitating the toner as a non-magnetic one-component developer contained in the toner supply roller and transporting the toner to the toner supply roller 3, and the rotation of the developing roller 21. A blade 28 for regulating the thickness of the toner layer on the developing roller 2 conveyed to the developing area, which is a part facing the photosensitive drum 1, so as to make the thickness uniform.

In this developing device, when the toner on the developing roller 21 is consumed by the development, the toner in the hopper is agitated by the first and second agitators 23 and 24 and the toner supply roller 3 is agitated. Is supplied to the developing roller 21 from the toner supply roller 3. When the toner is consumed in this way and the remaining amount of toner in the hopper decreases, it becomes necessary to replenish the hopper with toner at an appropriate time. Therefore, in the developing device 20, a piezoelectric toner sensor 2 for detecting the presence or absence of toner in the casing 27 of the hopper portion formed in the inner surface along the miracle of movement of the tip of the first agitator 23 is used.
6, the presence or absence of toner is detected by the sensor.
Then, when the remaining amount of toner is exhausted, the toner near end is displayed, and further, the development is repeated in the toner near end state, and when it is determined that the toner is almost exhausted in the developing device, the toner end is displayed. The output of the above sensor is used.

[0004]

However, as shown in the figure, the portion of the casing 27 to which the toner sensor 27 is attached is connected to the toner supply roller 22 side, for example, the second portion.
It has been found that the following inconvenience occurs when the slope portion is inclined so as to ascend toward the inner surface portion of the horizontal casing 27, which is one step higher below the agitator 24. In other words, the toner conveyed to the horizontal portion of the casing 27 by the rotation of the first agitator 23 falls down in the direction of the toner sensor 26 by the rotation of the second agitator 24 and is stacked on the sensor. It may be determined that toner is present.
In this case, there is no problem if a large amount of toner is present in the hopper on the first agitator 24 side. However, if there is not much toner present in the hopper, the above determination is erroneous. . This erroneous determination is made by the developing device 20
Although "toner end" or "toner end" is not displayed in spite of the fact that there is almost no toner inside the printer. As a result, problems such as a decrease in density due to a shortage of the remaining amount of toner are caused. If the uniformity of the remaining amount of toner in the longitudinal direction (width direction of the developing device) of the first agitator 23 of the developing device 20 cannot be obtained (for example, when the main body of the image forming apparatus is tilted back and forth), the same length is used. There is a difference between the toner sensor 26 in the direction and the remaining amount of toner at that location. In this case, the toner on the toner sensor 26 is
Even if the toner is conveyed in the direction of the agitator 24, the toner may flow from the higher side to the lower side in the same longitudinal direction (the height of the upper surface of the toner reservoir) and may be loaded on the toner sensor 26. At this time, the same erroneous determination as in the above case is made, and a problem such as a partial lack of density in the longitudinal direction occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent an undesired inflow of a developer into a detection region of a developer detector in a developing device from being detected in the device. An object of the present invention is to provide a developing device capable of preventing an erroneous determination in detecting a remaining amount of a developer due to the occurrence and an image forming apparatus employing the developing device.

[0006]

According to another aspect of the present invention, there is provided a developing device having a developer detector for detecting a developer, wherein the developer detector is provided in the developing device. The present invention is characterized in that an agent blocking means is provided for preventing an undesired developer from flowing into the detection area when detecting the presence or absence of an agent in the apparatus. Further, in the developing device according to claim 1, in the developing device according to claim 1, the detection region is set in a region where the developer is transported in an upward direction by a developer transport unit in an upwardly inclined portion of the inner surface of the device,
It is characterized in that the agent blocking means is constituted by an agent flow preventing plate provided above the detection area. According to a third aspect of the present invention, in the developing device of the first aspect, the detection region is set in a part of the device in the width direction, and the agent blocking means is moved from both sides in the width direction. It is characterized by comprising a width direction agent movement prevention plate provided so as to sandwich the agent to prevent movement of the agent from the outside in the width direction toward the detection region side. Further, a developing device according to a fourth aspect is characterized in that, in the developing device according to the first aspect, the anti-flowing-down plate according to the second aspect and the width-direction anti-migration plate according to the third aspect are provided. Claim 5
The developing device according to claim 1 is the developing device according to claim 1.
And / or at least one of the width direction agent movement preventing plate of claim 3 is provided so as to be adjustable in height. An image forming apparatus according to a sixth aspect is characterized in that the developing device according to the first, second, third, fourth, or fifth aspect is used as a developing device.

According to the first to sixth aspects of the present invention, the agent blocking means prevents an undesired developer from flowing into the detection area of the agent detector in the developing device when the presence or absence of the agent in the device is detected. I do.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] Referring to FIGS. 1 and 2, in an electrophotographic image forming apparatus, in a developing apparatus having a piezoelectric sensor for detecting the presence or absence of toner, toner is conveyed. A description will be given of an embodiment in which a partition plate, which is slightly larger than the width of the sensor and which is slightly larger than the width of the sensor, is provided at the same position in the direction at right angles to the toner conveying direction. The image forming apparatus shown in FIGS. 1 and 2 has a partition plate 50 provided on the casing 27 of the second developing device 20 in the copying machine shown in FIG. 1 as shown in FIG.

First, a schematic configuration and operation of the copying machine will be described with reference to FIG. The photoconductor drum 1 as a latent image carrier rotates clockwise in the figure, and the surface of the photoconductor drum 1 is charged by the first charger 2 of the first latent image forming means. Then, the semiconductor laser of the optical writing device (not shown) is turned on according to the image signal of the first color portion sent from the image reading unit (not shown). The light 3 from the semiconductor laser is reflected by a polygon mirror (not shown) rotating at a predetermined rotation speed and is irradiated on the surface of the photosensitive drum 1, thereby forming a first electrostatic latent image on the surface of the photosensitive drum 1. Form. The first electrostatic latent image is developed by a first developing device that performs black development using a two-component developer obtained by mixing a black toner and a carrier.

Next, the second charger 4 of the second latent image forming means
As a result, the surface of the photoconductor 1 including the portion of the black toner image is recharged. Then, 2 sent from the image reading unit
An optical writing device (not shown) is driven in accordance with the image signal of the color portion of the color, and a second electrostatic latent image is formed on the surface of the photosensitive drum 1 with light 5 from this. This second electrostatic latent image is
The image is developed by the second developing device 20, thereby forming the first color and the second color toner images on the surface of the photosensitive drum 1.

A two-color toner image on the photoreceptor 1 is transferred to a transfer device 3 having a paper conveying belt 31, a transfer bias roller 32, and the like.
0, the toner image is collectively transferred onto a transfer sheet as an image holding member sent from a paper feed tray or a manual feed table (not shown), and then fixed by a fixing roller of a fixing device (not shown). Is discharged. On the other hand, the surface of the photoconductor 1 after the transfer is cleaned by the cleaning device 6 to remove the remaining toner, and is prepared for the next image formation.

Then, in FIG. 2, the second developing device 20
The toner sensor 26 is located below the first agitator 23 in the developing device 20, is attached to the lower casing 27, and has a width a as a sensor. As shown in the figure, a partition plate 50 having a width b larger than the width a is provided at a position where the horizontal surface of the lower casing 27 intersects with the R surface, at a right angle to the toner conveying direction. The partition plate 50 is provided between the second agitator 24 and the first agitator 23 in the developing device 20 shown in FIG.
Exists between

The first agitator 23 uses the second agitator 24
Is transported in the direction of the first agitator 23 again by the rotation of the second agitator 24 at the longitudinal position where the partition plate 50 does not exist, and returns. In the range where the partition plate 50 exists, the toner that has been conveyed to the left side of the partition plate 50 (on the side of the second agitator 24) is less than the height of the partition plate 50 and the first agitator 23 is rotated by the rotation of the second agitator 24. It is not returned to the direction. That is, the partition plate 50 of the toner sensor 26 prevents unnecessary toner from flowing into the toner sensor 26. Therefore, it is possible to prevent the toner sensor from being erroneously detected due to the avalanche of the toner as described above, and to prevent a problem such as a decrease in density due to a decrease in the remaining amount of toner in the developing device.

Unlike the present embodiment, when there is no partition plate 50 in the toner sensor 26, the remaining amount of toner near the first agitator 23 decreases due to the operation in the range where the partition plate 50 does not exist. However, the toner flows into the toner sensor 26 and detects that toner is present. For this reason, the image forming apparatus main body does not display "toner end" or "toner end", and the density is reduced due to the lack of the remaining amount of toner in the normal use state.

[Embodiment 2] Referring to FIGS. 1 and 3, in an electrophotographic image forming apparatus, in a developing device having a piezoelectric sensor for detecting the presence or absence of toner, the developing device is parallel to the toner conveying direction. And the sensor is sandwiched with a width slightly larger than the sensor.
An embodiment will be described in which two partitions are provided as agent blocking members in a shape surrounded by a circle. 1 and 3
Is a second developing device 2 in the copying machine shown in FIG.
The partition plates 51, 52 shown in FIG.
Is provided.

In FIG. 2, two partition plates 51 and 52 are provided in parallel with the toner conveying direction so as to sandwich the toner sensor 26 so that the width b is larger than the width a of the sensor 26. At this time, naturally, the first agitator 23 has a shape such that the partition plates 51 and 52 are avoided. The two partition plates 51 and 52 prevent unnecessary toner from flowing into the toner sensor 26 due to bias of the toner in the longitudinal direction of the first agitator 23. Therefore, it is possible to prevent the erroneous detection of the toner sensor due to the toner flow in the longitudinal direction as described above, and to prevent a problem such as a partial density decrease due to a partial shortage of the remaining amount of toner in the longitudinal direction in the developing device. it can.

[Embodiment 3] Referring to FIGS. 1 and 4, a developing device having a piezoelectric sensor for detecting the presence or absence of toner in an electrophotographic image forming apparatus will be described. An embodiment will be described in which three partition plates of Embodiment 2 are provided so as to surround three sides of the sensor. The copying machine shown in FIGS. 1 and 4 includes a partition plate 5 in a casing 27 of the second developing device 20 in the copying machine shown in FIG.
0, 51, and 52 are provided.

In FIG. 4, a pair of partitioning plates 5 horizontal to the toner conveying direction and a horizontal to the same direction.
1 and 52 are provided so as to have a width b larger than the width a of the sensor. Thus, the inflow of the toner from the second agitator 24 direction and the inflow of the toner from the longitudinal direction of the first agitator 23 are prevented. Therefore, it is possible to prevent both the insufficient density and the partial insufficient density.

[Embodiment 4] Referring to FIGS. 5 and 6, a developing device having a piezoelectric sensor for detecting the presence or absence of toner in an electrophotographic image forming apparatus will be described. An embodiment in which the height of the partition plate of the second embodiment is adjustable will be described. The copying machine shown in FIG. 1 and FIG. 5 or FIG. 6 includes a partition plate 54, as shown in FIG.
57 and 58 are provided.

FIG. 5 shows a case of a partition plate perpendicular to the toner conveying direction, and FIG. 6 shows a case of a parallel partition plate.
Numeral 58 is supported by support plates 53, 55, 56 so as to be slidable up and down, respectively. To adjust the slidable partition plate, for example, screws or the like that can be adjusted to appear outside the developing device 20 are attached to the partition plates 54, 57, 58, and the partition plate is adjusted by adjusting the height of the screws. May be adjusted from the outside of the apparatus (this method can be variously conceived).

Normally, even if the height is set to a certain value, the toner sensor 26 itself has a sensitivity variation with respect to the weight, so that the remaining amount of toner in the apparatus varies. Further, since the volume of the toner changes due to the variation in the degree of aggregation of the toner, the remaining amount also varies. Furthermore, since the main body itself is inclined depending on the installation location of the main body of the image forming apparatus,
This also causes variations (especially in the longitudinal direction). When the variation in the remaining amount of toner in the apparatus is large, the height of the partition plate is adjusted to make the remaining amount appropriate. In this way, the correspondence between the developing device or the image forming device to the variation in the remaining amount of toner in the developing device due to the variation in the sensitivity of the toner sensor, the variation in the cohesion of the toner, the variation in the inclination of the image forming device main body, and the like. Can be improved.

[0022]

According to the first to fifth aspects of the present invention, the remaining amount of the developer due to the undesired inflow of the developer into the detection area of the developer detector in the developing device in the detection of the presence or absence of the developer in the device occurs. A developing device capable of preventing erroneous determination upon detection can be provided.

In particular, in the second aspect of the present invention, the developer detecting area is set at a region where the developer is conveyed in the upward direction by the developer conveying means in the upwardly inclined portion of the inner surface of the apparatus. The agent is prevented from flowing down from the side by a plate for preventing the agent from flowing down. Therefore, it is possible to prevent erroneous determination of the presence / absence of the developer due to accumulation of the falling developer in the detection area.

According to the third aspect of the present invention, the widthwise agent movement preventing plate prevents the agent from moving from the outside in the width direction into the agent detection region set in a part of the device in the width direction. I do. Therefore, for example, even when the device is inclined such that a difference in height occurs in the width direction, erroneous determination of the presence or absence of the agent due to the movement of the agent from the outside in the width direction to the detection region can be prevented. As a result, it is possible to prevent the occurrence of uneven development density in the width direction in the width direction based on the erroneous determination when the amount of the developer in the apparatus is small.

Further, according to the invention of claim 4, according to claim 2,
The erroneous determination of the presence / absence of the agent due to accumulation of the flowing-down developer in the detection region of the agent can be prevented by the agent-falling-preventing plate of (3). It is also possible to prevent erroneous determination of the presence or absence of the agent due to the movement of the agent to the detection area.

According to a fifth aspect of the present invention, in the developing device of the first aspect, at least one of the plate for preventing the agent from flowing down and the agent for preventing the widthwise agent from moving in the width direction is adjustable. The adjustment can be made so as to eliminate the variation in the remaining amount of toner in the developing device due to the variation in the sensitivity of the toner sensor, the variation in the cohesion of the toner, the variation in the inclination of the image forming apparatus main body, and the like. Therefore, it is possible to prevent erroneous determination due to such variations, and to improve the compatibility of each developing device or each image forming device.

According to the sixth aspect of the present invention, an erroneous detection of the remaining amount of the developer due to an undesired flow of the developer into the detection area of the agent detector in the developing device, which is undesirable in detecting the presence or absence of the agent in the device, occurs. An image forming apparatus that can prevent the determination can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire copying machine according to an embodiment.

FIG. 2 is a partially enlarged perspective view of the developing device according to the first embodiment.

FIG. 3 is a partially enlarged perspective view of a developing device according to a second embodiment.

FIG. 4 is a partially enlarged perspective view of a developing device according to a third embodiment.

FIG. 5 is a partially enlarged perspective view of an example of a developing device according to a fourth embodiment.

FIG. 6 is a partially enlarged perspective view of another example of the developing device according to the fourth embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 10 first developing device 20 second developing device 21 developing roller 22 toner supply roller 23 first agitator 24 second agitator 26 toner sensor 27 casing 28 blade 50 partition plate 51 partition plate 52 partition plate 53 support plate 54 partition Plate 55 Support plate 56 Support plate 57 Partition plate 58 Partition plate

Claims (6)

[Claims] 1. A developing device having a developer detector for detecting a developer, which prevents an undesired developer from flowing into a detection region of the developer detector in the developing device when the presence or absence of the developer in the device is detected. A developing device provided with a developer blocking means. 2. The developing device according to claim 1, wherein the detection region is set in a region where the developer is conveyed in an ascending direction by a developer conveying device in an ascending slope of an inner surface of the device, and the developer blocking means is provided. A developing device provided above the detection area. 3. The developing device according to claim 1, wherein the detection region is set in a part of the device in the width direction, and the agent blocking means is provided so as to sandwich the detection region from both sides in the width direction. And a width direction agent movement preventing plate for preventing the agent from moving from the outside in the width direction toward the detection area. 4. The developing device according to claim 1, further comprising the agent flow preventing plate according to claim 2 and the width direction agent moving preventing plate according to claim 3. 5. The developing device according to claim 1, wherein at least one of the agent flow preventing plate according to claim 2 and the width direction agent moving preventing plate according to claim 3 is provided so as to be adjustable in height. apparatus. 6. An image forming apparatus using the developing device according to claim 1, 2, 3, 4, or 5 as a developing device.