JP2002091154A - Developing unit and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hardly cause faulty development even when a developing unit is inclined in the longitudinal direction of a developing roller and to prevent a toner end from being detected even though some toner remains more than necessary. SOLUTION: A toner sensor 21 is provided nearly at a center part C in the longitudinal direction of the developing roller in a case 11, and the internal shape of the developing unit is formed so that toner capacity may be smaller on both sides than at the center part. As for the internal shape, the inner wall shape of the case 11 is made to differ between at the center part and on both sides thereof or the shape of an agitator is made to differ between at the center part and on both sides thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and a developing device in an image forming apparatus such as a printer, a facsimile, and a copying machine for forming an image by using an electrophotographic technique. In particular, the present invention relates to a technique for detecting the remaining amount of toner.

[0002]

2. Description of the Related Art Generally, an image forming apparatus for forming an image by using an electrophotographic technique has a photosensitive member as an image carrier having a photosensitive layer on an outer peripheral surface, and uniformly charges the outer peripheral surface of the photosensitive member. A charging unit, an exposure unit for selectively exposing the outer peripheral surface of the photoreceptor uniformly charged by the charging unit to form an electrostatic latent image, and an electrostatic latent image formed by the exposure unit. And a developing device having a developing device that applies a toner as a developer to form a visible image (toner image).

[0003] A developing device includes a case containing toner,
A developing roller rotatably supported by the case and applying toner to the photoconductor is provided. If the amount of toner in the case becomes too small, development failure occurs. Therefore, the case is provided with a toner sensor for detecting the remaining amount of toner contained in the case.

[0004]

In the conventional developing device described above, the mounting position of the toner sensor is based on the idea that the amount of toner in the case is not so small that there is no need to cause development failure. On the premise that the image forming apparatus is installed in a horizontal state by a user, the image forming apparatus is mounted at a position that is easy to design according to the shape and structure of the developing device. For this reason, the toner sensor is not provided at a substantially central portion in the longitudinal direction of the developing roller in the case, but is provided at a position deviated leftward or rightward from the central portion. On the other hand, it is rare that an image forming apparatus provided with a developing device (developing device) is reliably installed in a horizontal state by a user.
The installation state usually has a slight inclination. In such a situation, it has been found that if the image forming apparatus is installed in a state where the image forming apparatus is inclined in the longitudinal direction of the developing roller of the developing device, the following problem occurs.

FIGS. 11A and 11B are conceptual diagrams for explaining the above problem. FIGS. 11A, 11B, and 11C show cases 1 of the developing device.
Is a cross-sectional view of the developing roller (not shown),
(E) is a plan view of (a), and (f) is a side view of (e). In the drawing, reference numeral 1 denotes a case, 2 denotes a toner sensor, and a portion T indicated by oblique lines denotes toner. As shown in FIG. 1A, the toner sensor 2 is provided at a position deviated leftward from a center C in the longitudinal direction (left-right direction in the figure) of the developing roller. FIG. 1A shows the case where the image forming apparatus, that is, the developing device (and thus the case 1) is installed horizontally with respect to the longitudinal direction of the developing roller (the left-right direction in the figure), and FIG. The side opposite to the side (right side) is inclined downward, and FIG. 3C shows the case where the side where the sensor 2 is biased is inclined downward.

As shown in FIG. 1A, when the image forming apparatus, that is, the case 1 is set horizontally with respect to the longitudinal direction of the developing roller, no problem occurs. For example, as shown in FIG. × 20cm, depth 10c
m, and the mounting position of the sensor 2 is 3 cm from the bottom surface 1 a of the case 1 and 5 cm to the left from the center C in the left-right direction. The remaining amount of toner T is 600cm
It becomes ³ .

On the other hand, when the unit is omitted in the following description, for example, as shown in FIG. 1B, the case 1 is formed so that the side opposite to the side where the sensor 2 is biased (right side) is lower.
When the toner is inclined by 5 °, the remaining amount of toner becomes 1300,
Conversely, when the case 1 is inclined by 45 ° so that the side where the sensor 2 is biased is downward as shown in FIG. In other words, in the case of FIG. 9A, when the remaining amount of toner reaches 600, the sensor 2 detects that the remaining amount of toner has decreased (this detection is referred to as toner end detection). In the case of b), it is detected when the remaining amount of toner reaches 1300, and in the case of FIG. Therefore, the case of FIG.
Is 900, the difference between the remaining amounts of toner in the case of FIG. (A) and FIG. (C) is 280, and the case of FIG. (B) and FIG. And the difference between the remaining toner amounts is 980, which is the maximum. In the case of FIG. 3C, the toner end is not detected even though the toner is exhausted on the side 1c opposite to the side where the sensor 2 is biased. Conversely, in the case shown in FIG. 2B, a problem occurs that the toner end is detected even though a large amount of toner remains. Further, in the case of FIG. 2B, a developing failure occurs on the side 1b where the sensor 2 is biased.

In the illustrated example, the angle of inclination of the case 1 is set to 45 ° in order to easily understand such a problem. However, the same problem occurs even when the angle of inclination is small. In particular, when the width of the image forming area (the left-right direction in the figure) is wide (therefore, when the developing roller is long), or when the case 1 of the developing device is flat as shown in FIG.
No. -152303), the above-mentioned problem appears remarkably even when the inclination angle is small. In FIG. 13, 3 is a developing roller,
Reference numeral 4 denotes a photosensitive member that carries a latent image to be developed.

The above problem will be described from another point of view. As shown in FIG. 12B, when the developing device is inclined downward by more than about 30 ° to the right, toner end is not detected. Nevertheless, development failure occurs on the left side 1b (the remaining amount of toner at the time of toner end detection is about 115
0), as shown in FIG. 7C, if the inclination is about 11 ° or more downward to the left, development failure occurs on the right side 1c even though the toner end is not detected (the remaining amount of toner at the time of toner end detection). Is about 400). That is, the magnitude of the inclination angle at the time when the development failure occurs greatly differs depending on the difference in the inclination direction. Also, the developing device is
As shown in FIG. 12 (b), the amount of remaining toner at the time of toner end detection is about 1150 when inclined to the lower right by about 30 °, and about 11 to the lower left as shown in FIG. 12 (c). °
The remaining amount of toner at the time of detecting the toner end when inclined is about 400, and a large difference (1150-400 =
750) occurs. In other words, in the case of FIG. 2B, even if the case 1 is relatively large and tilts by about 30 °, no developing failure occurs. In this case, the remaining toner amount at the time of detecting the toner end is about 1150. That is, the toner end detection is performed even though an unnecessarily large amount of toner remains. However, in practice,
The number of developing units (that is, image forming apparatuses) is 30 by the user.
Since it is difficult to imagine that the developing unit is inclined at an angle of about 15 °, when the developing unit is inclined by about 15 ° as shown in FIG.
It becomes 0. Therefore, when compared with the case of FIG.
The difference between the remaining toner amounts is 850−400 = 450, but the difference is still large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, so that even if the developing device is inclined with respect to the longitudinal direction of the developing roller, poor development is unlikely to occur, and the amount of toner is unnecessarily large. An object of the present invention is to provide a developing device and a developing device in which toner end detection is not performed despite remaining toner.

[0011]

According to a first aspect of the present invention, there is provided a developing device, comprising: a case; a developing roller rotatably provided with respect to the case; A toner sensor for detecting a remaining amount of toner, wherein the toner sensor is provided in the case at a substantially central portion with respect to a longitudinal direction of the developing roller. The shape is
It is characterized in that the toner capacity on both sides of the central portion where the toner sensor is provided is smaller than that of the toner sensor. According to a second aspect of the present invention, there is provided a developing device.
In the developing device described above, the inner shape is configured such that the inner wall shape of the case is changed between the central portion and both sides thereof so that the toner capacity on both sides is reduced. According to a third aspect of the present invention, in the developing device according to the first aspect, an agitator for agitating the toner is provided in the case, and the internal shape includes the shape of the agitator, the central portion and the central portion. By changing between the two sides, the toner capacity on both sides is reduced. According to a fourth aspect of the present invention, there is provided the developing device according to the first, second or third aspect.
In the developing device described above, the case has a flat shape. The developing device according to claim 5, wherein the case, a developing roller rotatably provided with respect to the case, a plurality of agitators that convey toner stored in the case toward the developing roller, In a developing device having a plurality of developing devices having a toner sensor for detecting a remaining amount of toner stored in a case, and a plurality of developing devices provided at different inverted angles, the toner sensor includes: For a developing device which is provided substantially at the center with respect to the longitudinal direction of the developing roller and has a relatively large inverted angle, the shape of the inner wall of the case is changed between the center and both sides thereof, so that the developing device at both sides is formed. For a developing device that is configured to have a small toner capacity and has a relatively small inverted angle, the shape of the agitator is changed to the central portion and both sides thereof. By varying in, characterized in that it is configured so that the toner capacity is reduced at the both sides.

[0012]

According to a first aspect of the present invention, there is provided a developing device including a case, a developing roller rotatably provided with respect to the case, and a toner sensor for detecting a remaining amount of toner contained in the case. A developing device, wherein the toner sensor is provided at a substantially central portion in the case in the longitudinal direction of the developing roller, and an inner shape of the developing device is a central portion provided with the toner sensor. Therefore, even if the developing device is tilted in either the left or right direction in the longitudinal direction of the developing roller, the toner at the time when the toner end is detected is reduced. Is smaller than before. Therefore, it is possible to reduce the degree of occurrence of a situation in which the toner end is detected even though the toner remains in an unnecessarily large amount due to the difference in the inclination direction of the developing device (when the developing unit is inclined to any direction). It becomes possible. In addition, it is possible to reduce the degree of occurrence of a situation where the remaining amount of toner at the time of toner end detection becomes too small. Therefore, as a result, even when the developing device is inclined to the left or right with respect to the longitudinal direction of the developing roller, it is possible to make it difficult to cause defective development (that is, to increase the range of inclination where no defective development occurs). Is possible). According to the developing device according to claim 2, in the developing device according to claim 1, the inner shape is obtained by changing an inner wall shape of the case between the central portion and both sides thereof.
Since the toner capacity on both sides is reduced, it is possible to easily reduce the toner capacity on both sides as compared with the case where the shape of the agitator is changed as in claim 3. Become. Therefore, the degree of freedom of the agitator shape can be ensured. According to a third aspect of the present invention, in the developing device of the first aspect, an agitator for stirring the toner is provided in the case, and the inner shape is the same as that of the agitator. By changing between the two sides, the toner capacity on both sides is reduced, so that the shape of the inner wall of the case can be shared. In the case where the case has a plurality of agitators and the inner wall shape of the case is changed as described in claim 2, there is a possibility that the toner is not smoothly transported by the agitator. In addition, if the configuration is such that the toner capacity on both sides is reduced by changing the shape of the agitator, such a possibility is eliminated. According to the developing device of the fourth aspect, in the developing device of the first, second, or third aspect, the case has a flat shape.
When the image forming apparatus forms a full-color image, for example, a plurality of developing units can be easily arranged in the vertical direction. As described above, when the case has a flat shape, the above-described problem is likely to occur. According to the developing device of the fourth aspect, as described in the first, second, or third aspect, Since the case has a flat shape,
Developing defects due to the inclination in the longitudinal direction of the developing roller are less likely to occur regardless of the inclination direction, and toner end is detected even though a large amount of toner remains unnecessarily. It is possible to reduce the degree of occurrence of a situation in which the remaining amount of toner becomes too small. That is, the configuration of claim 1, 2, or 3 is particularly effective when the case has a flat shape. According to the developing device of the fifth aspect, since the plurality of developing devices are provided at different inverted angles, it is possible to reduce the size of the photosensitive member or the like which is a carrier of the latent image to be developed. It becomes possible. Each of the developing devices includes a case, a developing roller rotatably provided with respect to the case, a plurality of agitators for conveying the toner stored in the case toward the developing roller, And a toner sensor for detecting the remaining amount of toner stored in the developing device. The toner sensor is provided at a substantially central portion in the case in the longitudinal direction of the developing roller, and has an internal shape of each developing device. However, since the toner capacity on both sides is reduced as compared with the central portion where the toner sensor is provided, these developing units are inclined in either the left or right direction in the longitudinal direction of the developing roller. Even in this case, the difference in the remaining amount of toner at the time when the toner end is detected is smaller than in the conventional case. Therefore, due to the difference in the inclination direction of the developing device (when the developing device is inclined to any direction), the toner end is detected even though the toner remains in an unnecessarily large amount. It is possible to reduce the degree of occurrence of a situation where the remaining amount becomes too small. Therefore, as a result, even when the developing device is inclined to the left or right with respect to the longitudinal direction of the developing roller, it is possible to make it difficult to cause defective development (that is, to increase the range of inclination where no defective development occurs). Is possible). Further, the developing device having the relatively large inverted angle is configured such that the inner wall shape of the case is changed between the central portion and both sides thereof so that the toner capacity on both sides is reduced. As compared with the case where the shape is changed, the toner capacity on both sides can be easily reduced, and the degree of freedom of the agitator shape can be secured. As described above, when the developing device has a plurality of agitators and the inner wall shape of the case is changed, the toner may not be smoothly transported by the agitator as described above. Since the developing device in which the inner wall shape of the case is changed is a developing device having a relatively large inverted angle, even when the inner wall shape of the case is changed, the toner can be smoothly transported with the help of the free fall. Will be done. On the other hand, for a developing device in which the inverted angle is relatively small, the shape of the agitator is
By changing between the central portion and both sides, the toner capacity on both sides is reduced, so that the shape of the inner wall of the case can be made common. In addition, the toner is smoothly transported.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a schematic front sectional view showing a main part of an example of an image forming apparatus using a developing device and a developing device according to a first embodiment of the present invention.

The image forming apparatus includes a photosensitive member 5 as an image carrier having a photosensitive layer on the outer peripheral surface, a charging unit (not shown) for uniformly charging the outer peripheral surface of the photosensitive member 5, and one charging unit. Exposure means (not shown) for selectively exposing the outer peripheral surface of the photoreceptor 5 charged in the above manner to form an electrostatic latent image, and a developing agent on the electrostatic latent image formed by the exposure means A plurality of (four in the illustration) developing units 10 (Y, C, M,
K).

Each of the developing devices 10 is mounted on a mounting table 30 and is swingably attached to a frame (not shown), and only a developing device corresponding to the color of an image to be formed has a driving mechanism (not shown). Thereby, the photosensitive member 5 can be contacted. Reference numeral 40 (Y, C, M, K) denotes a toner cartridge for replenishing toner to the case of the developing device 10, which is detachably attached to the developing device 10.

Since the basic structure of each developing unit 10 is the same, the developing unit 10C for cyan will be described as a representative with reference to FIGS. The developing device 10 includes a case 11 and a developing roller 1 that is rotatably supported by side plates 11 a and 11 a of the case 11 about a shaft 12 b and applies toner to the photoconductor 5.
2 and a toner sensor 21 for detecting the remaining amount of toner (see T in FIG. 1) stored in the case 11. The case 11 includes a lower case 11e and an upper case 11f, and has a flat shape as a whole.

The developing roller 12 is rotationally driven in a direction indicated by an arrow in FIG. 2 by a driving means (not shown) at a peripheral speed of, for example, about 360 mm / s. The case 11 has first and second agitator chambers 13 and 14 and a developing chamber 15 for storing toner to be supplied to the developing roller 12. In the first and second agitator chambers 13 and 14, there are provided first and second agitators 16 and 17 which are driven to rotate in the direction of the arrow in FIG. 2 by driving means (not shown). The agitator constitutes a feeding unit that feeds the toner toward the developing roller 12 (toward the developing chamber 15). In the developing chamber 15, a supply roller 18 for supplying toner to the surface 12a of the developing roller 12 is provided. The supply roller 18 is driven to rotate in a direction indicated by an arrow in FIG. 2 by a driving unit (not shown) at a peripheral speed of, for example, about 240 mm / s.

The first and second agitator chambers 13 and 14 communicate with each other through a toner flow path (communication port) 13a, and the second agitator chamber 14 and the developing chamber 15 communicate with each other through a toner flow path (communication port) 14a.
In communication.

A blade 19 for regulating the amount of toner supplied thereto is in contact with the surface 12a of the developing roller 12. The blade 19 is attached to the case 11 via the support plate 20. On the opposite side of the blade 19, between the surface 12 a of the developing roller 12 and the case 11, there is provided a seal member 23 made of a thin sheet that slides on the developing roller surface 12 a. Seal member 2
3 is fixed to the case 11.

The toner sensor 21 is, as shown in FIG.
In the case 11, the developing roller 12 is provided substantially at the center with respect to the longitudinal direction (the left-right direction in FIG. 3) of the developing roller 12. In FIG. 1, a cross-hatched portion T (Y,
C, M, and K) are toners remaining in the case 11 at the time of toner end detection. As shown in FIG.
As shown in FIG. 2, the toner cartridge 4 is provided at a position far away from the developing roller 12 in the developing device 10, in this embodiment, at a substantially central portion C in the width direction at the rear end.
The toner supply port 10 a from 0 to the case 11 is provided on the side of the toner sensor 21. Toner sensor 21
Can be constituted by a known sensor, for example, a piezoelectric powder level sensor using piezoelectric ceramics as a sensor element.

The toner cartridge 40 includes a case 41 containing toner (not shown), two agitators 42 and 43 provided in the case 41, and a case 41.
The agitators 42 and 43, which are rotationally driven in the direction of the arrow in FIG. 2 by driving means (not shown), provide a feeding means for feeding toner toward the developing device 10. Make up. Such a toner cartridge 40 is connected to the side plate rear portions 11b, 11b of the developing device 10.
2 (only one is shown in FIG. 2), the supply port 44 faces the toner supply port 10 a provided in the developing device 10, and the toner in the toner cartridge 40 loses its own weight and the agitator 42. , 43 are supplied to the developing device 10 through the supply port 44 and the toner supply port 10a.

Therefore, the toner in the toner cartridge 40 is supplied to the toner supply port 10 as indicated by the arrow t1.
a into the first agitator chamber 13 of the developing device 10 from
As shown by an arrow t1a (see FIG. 3), it spreads right and left in the first agitator chamber 13, and flows into the second agitator chamber 14 through the communication port 13a as shown by an arrow t2 while being stirred by the first agitator 16. And the second agitator 17
The developer is supplied into the developing chamber 15 through the communication port 14a as indicated by an arrow t3 while being stirred by the supply roller 18, and flows with the developing roller 12 by the supply roller 18 while flowing along the rotation of the supply roller 18 as indicated by an arrow t4. The contact portion 18a rubs against the surface 12a of the developing roller 12, and the amount of adhesion to the surface of the developing roller is regulated by the blade 19, so that the toner is applied from the developing roller surface 12a to the surface of the photosensitive member 5. The toner that has not been rubbed against the surface 12a of the developing roller 12 by the supply roller 18 flows along the rotation of the developing roller 12 as shown by an arrow t5, and further, the blade 19 as shown by arrows t6, t7 and t8. It circulates along the inner surface and the inner surface of the developing chamber. The remaining toner that has not been transferred to the photoconductor 5 among the toners adhered to the developing roller surface 12a is the sealing member 2
3 and returns into the developing chamber 15 and flows along the rotation direction of the developing roller 12 and the supply roller 18 as shown by arrows t10 and t11.

The developing device 10 (Y, C, M,
K) and toner cartridge 40 (Y, C, M, K)
As shown in FIG. 1, are arranged substantially radially around the photoreceptor 5 with different inverted angles.

If no measures are taken in such a developing device, if the image forming apparatus is installed so that the developing device is inclined with respect to the longitudinal direction of the developing roller, defective development may occur. Easier, or
As described above, there is a problem that the toner end is detected even though the toner remains in an unnecessarily large amount. Therefore, in this embodiment, the inner shape of the developing device 10 is configured such that the toner capacity on both sides of the central portion where the toner sensor 21 is provided is reduced. Specifically, as shown in FIGS. 3 and 4, bulging portions 13 b, 13 b, 14 b, 14 b are provided on both sides of a central portion C where the toner sensor 21 is provided in the first and second agitator chambers 13, 14. , The toner capacity on both sides is reduced.

Further, as described above, the plurality of developing devices 10
In the case where (Y, C, M, K) are arranged around the photoconductor 5 in different postures, if no measures are taken, the toner sensor 21 will not detect toner. At the time point, that is, when the toner remaining amount is reduced (toner end), the remaining toner amount greatly differs depending on the developing device. Therefore, in this embodiment, as shown in FIG.
The toner T (Y, C, M, T) in the developing device 10 at the time when the toner is no longer detected by the toner sensor 21
The internal shape of each developing device 10 (Y, C, M, K), that is, the toner is no longer detected, so that the remaining amount of K) is substantially the same in each developing device 10 (Y, C, M, K). At this point, the internal volume of the developing device 10 is changed according to the attitude of the developing device. More specifically, in this embodiment, the inner volume of the developing chamber 15 is substantially the same for each developing device, but the attitude angle of each developing device (the counterclockwise direction around the photoconductor 5 in FIG. 1 is positive). The larger the size of the developing device, the smaller the internal volume of the second agitator chamber 14 is. That is, the magnitude relationship of the internal volumes of the second agitator chambers 14 (Y, C, M, K) of each developing device is 1
4Y <14C <14M <14K.

The internal shape of each developing device 14 is configured such that the remaining amount of toner at the time when the toner is no longer detected by the toner sensor 21 is larger than the remaining amount at which toner deterioration is accelerated. For example, if the deterioration acceleration point of the toner occurs when the remaining amount is about 60 to 80 g, the toner is not detected when the remaining amount is about 100 g.

Further, the toner supply from the toner cartridge 40 to the developing device 10 is performed even after the toner is detected by the toner sensor 21. More specifically, when the toner is no longer detected by the toner sensor 21, a display of a toner end is displayed on a display unit (not shown) of the image forming apparatus main body (for example, the toner cartridge 40Y is replaced because the remaining amount of yellow toner is low). When the user replaces the toner cartridge 40 and closes the cover of the image forming apparatus based on the message, at least the toner cartridge 40 is displayed.
(Y) Agitator 43 and First Unit of Developing Unit 10 (Y)
When the agitator 16 rotates and toner is supplied from the toner cartridge 40 to the developing device 10, and the toner sensor 21 detects toner, the display of the toner end disappears. However, after that, the agitator continues to rotate. Toner supply.

According to the developing device described above, the following operation and effect can be obtained. (A) The case 11 includes a case 11, a developing roller 12 rotatably provided with respect to the case 11, and a toner sensor 21 for detecting a remaining amount of the toner accommodated in the case 11. In the case 11, the developing roller 10 is provided at a substantially central portion C with respect to the longitudinal direction of the developing roller 12, and the inner shape of the developing device 10 is smaller than the central portion C at which the toner sensor 21 is provided. Is configured to reduce
Even when the developing device 10 is tilted in the left or right direction (the direction of the arrow A shown in FIG. 4) in the longitudinal direction of the developing roller 12, the difference in the remaining amount of toner at the time when the toner end is detected is the same as the conventional one. It is smaller than the one. Therefore, depending on the difference in the inclination direction of the developing device 10 (when inclined to any direction), the toner end is detected even though the toner remains in an unnecessarily large amount, or the toner end at the time of the toner end detection is detected. It is possible to reduce the degree of occurrence of a situation where the amount of remaining toner becomes too small. Therefore, as a result, the developing device 1
Even when 0 is inclined to the left or right with respect to the longitudinal direction of the developing roller 12, it is possible to make it difficult to cause defective development (that is, it is possible to increase the range of inclination where no defective development occurs). .

This will be described with reference to FIG. FIG. 5 is an exemplary conceptual diagram for explaining the function and effect of the present invention in comparison with the conceptual diagram 12 described above, wherein (a), (b), (c) and (d) are all developer units. 3 is a schematic cross-sectional view of the case 1 (corresponding to the case 11 of the above embodiment) viewed from the direction of its developing roller (corresponding to the developing roller 12 of the above embodiment). FIG. 7E is a plan view of FIG. 7A, and FIG. 7F is a side view of FIG. As shown in FIG. 1A, the toner sensor 2 (corresponding to the toner sensor 21 in the above embodiment) is provided at the center C of the developing roller in the longitudinal direction (the left-right direction in the figure). Further, bulging portions B, B (corresponding to the bulging portions 13b, 13b, 14b, 14b of the above-described embodiment) are formed on both sides of the central portion C where the toner sensor 2 is provided in the case 1. , The toner capacity on both sides is reduced. FIG. 3A shows a case where the image forming apparatus, that is, the developing device (and thus the case 1) is installed horizontally with respect to the longitudinal direction of the developing roller (the left-right direction in the drawing), and FIG. (C) shows a case where the left side is inclined downward. As in the case shown in FIG. 12, for example, the width of the case 1 is 20 cm, the height (thickness) is 10 cm, the depth is 10 cm, and the width of the bulging portion B is 8 cm and the height is 6
If the depth of the toner T is 5 cm, the remaining amount of the toner T when the toner 2 is no longer detected by the sensor 2 in the case of FIG.
In order to make 0 cm ³ , the mounting position of the sensor 2 is 5 cm from the bottom surface 1 a of the case 1.

Next, a description will be given by omitting the unit. As shown in FIG. 3B, the toner 2 is detected by the sensor 2 when the case 1 is inclined by about 27 ° so that the right side is downward.
Is no longer detected, the amount of toner remaining is about 680. Conversely, when the case 1 is inclined by about 27 ° so that the left side is downward as shown in FIG. Becomes That is, in either case of FIGS. 9B and 9C, when the remaining amount of toner becomes about 680, the sensor 2 detects that the remaining amount of toner has decreased (toner end).

In other words, in the example of FIG. 5, if the inclination is within about 27 ° even if the developing unit is inclined to the left or right, no developing failure occurs, and the developing unit at the time of toner end detection is not detected. If the amount of remaining toner becomes unnecessarily large,
Conversely, it will not be too low. That is, in the conventional device shown in FIG. 12, when the angle is inclined downward to the left as shown in FIG. In this case, no defective development occurs if the inclination is within about 27 ° (> 11 °) regardless of the inclination to the left or right. Regarding the remaining amount of toner, in the conventional device shown in FIG. 12, when the toner is inclined downward to the right as shown in FIG. While the end is detected, in the case of FIG.
Until 80 (<1150) or less, the toner end is not detected, and the toner remaining amount at the time of toner end detection does not become unnecessarily large. Also, FIG.
12 is about 400 (the difference from the horizontal state is about 200, which is too small) in the conventional apparatus shown in FIG. 12, whereas it is about 680 in the apparatus shown in FIG.
(The difference from the horizontal state is about 80 (<200)), and the toner remaining amount at the time of toner end detection does not become too small. Further, in practice, it is difficult to imagine that the developing device (that is, the image forming apparatus) is installed at an angle of 27 ° by the user, so that FIG.
Assuming that the developing device is tilted by about 15 ° (same to the left or right) as shown in (2), the remaining amount of toner at the time of toner end detection is about 630 (the difference from the horizontal state is about 30).
Thus, the difference in the remaining amount of toner becomes smaller than before.

As can be seen from the above description, according to the developing device 10 of this embodiment, even when the developing roller 12 is inclined in the left or right direction in the longitudinal direction, the toner at the time when the toner end is detected is determined. Is smaller than before. Therefore, depending on the difference in the inclination direction of the developing device 10 (when inclined to any direction), the toner end is detected even though the toner remains in an unnecessarily large amount, or the toner end at the time of the toner end detection is detected. It is possible to reduce the degree of occurrence of a situation in which the remaining amount of toner becomes too small. Therefore, as a result, even when the developing device 10 is inclined leftward or rightward with respect to the longitudinal direction of the developing roller 12, it is possible to make it difficult for defective development to occur (that is, to set the range of inclination where no defective development occurs). Can be increased).

(B) The inner shape of the developing device 10 is the case 1
By changing the shape of the inner wall at the central portion C where the toner sensor 21 is provided and at both sides thereof, the toner capacity on both sides is reduced, so that the agitator 16 and the / Or 1
As compared with the case where the shape of the toner cartridge 7 is changed, the toner capacity on both sides can be easily reduced. Therefore, the degree of freedom of the shapes of the agitators 16 and 17 can be ensured.

(C) When the remaining amount of toner in the case 11 in the height direction of the case 11 becomes substantially half the maximum amount of toner that can be accommodated in the case 11, (In FIG. 5, the sensor 2 is not provided at such a position for comparison with FIG. 12 in FIG. 5), so that the developing device 10 is tilted to the left or right with respect to the longitudinal direction of the developing roller 12. In this case, it is possible to further reduce the occurrence of development failure (that is, the range of the inclination angle at which development failure does not occur is further increased).

(D) Since the toner cartridge 40 for replenishing toner is provided in the case 11 so as to be detachable, when the toner end is detected, the toner cartridge 40 is replaced so that new toner is put in the case 11. Can be replenished. Therefore, the toner remaining in the case at the time when the toner end is detected is not wasted. Also,
As compared with the case where the developing unit is replaced at the time of toner end, components of the developing unit 10 other than the toner cartridge are not wasted.

(E) Since the case 11 has a flat shape, if the image forming apparatus is to form a full-color image as shown in FIG.
(Y, C, M, K) can be easily arranged vertically. As mentioned above, when the case 11 has a flat shape, the above-described problem is likely to occur. However, according to the developing device 10 of this embodiment, the inner shape is smaller than that of the central portion C. And the toner capacity on both sides is reduced.
Although the developing roller 1 has a flat shape, development failure due to the inclination of the developing roller 12 in the longitudinal direction is less likely to occur, and the toner end is detected even though a large amount of toner remains unnecessarily. Will not be lost. Further, the toner remaining amount at the time of toner end detection does not become too small. That is, a configuration in which the inner shape of the developing device 10 is such that the toner capacity on both sides thereof is smaller than the central portion C where the toner sensor 21 is provided is particularly effective when the case has a flat shape. .

(F) Since the toner is supplied from the toner cartridge 40 to the case 11 even after the toner is detected by the toner sensor 21, the toner is not detected by the toner sensor 21 immediately after the cartridge is replaced. The situation is prevented.

(G) Developing roller 1 in each developing unit 10
2 a toner supply port 10a located far away from
A toner sensor 21 for detecting the presence or absence of toner is provided near the developing device 10 and the remaining amount of toner in the developing device 10 at the time when the toner sensor 21 stops detecting toner (see FIG. 1). (Y, C, M, K)
, Each developing device 10 (Y, C,
Since the internal shape of M, K) is changed according to the attitude of the developing device, the above configuration and operation are such that the internal shape of the developing device 10 has a smaller toner capacity on both sides of the central portion C than in the central portion C. Together with the effect, the following operation and effect can be further obtained. (G1) The toner sensor 21 is connected to the toner supply port 1 located at a position far away from the developing roller 12 in the developing device.
Since it is provided near 0a, it is possible to prevent the toner remaining amount in the developing device 10 from being too small when the toner remaining amount is detected to be small. Therefore, when the developing device 10 is inclined in the longitudinal direction of the developing roller 12, the range of the inclination angle at which the developing failure does not occur is further increased. Further, the toner sensor 21
Is provided near the toner supply port 10a located far from the developing roller 12 for all the developing devices 10 (Y, C, M, K).
At 0, a difference in the toner pressure on the toner sensor 21 hardly occurs. Therefore, accurate detection is possible.
In addition, since the toner sensor 21 is provided near the toner supply port 10a, the toner sensor 21 receives the relatively fresh toner in a smooth state supplied from the toner cartridge 40 through the toner supply port 10a. They come into contact with each other (see arrows t1 and t1a in FIG. 3). Therefore, the possibility that toner adheres to the surface of the toner sensor 21 due to toner packing or the like is reduced, and as a result, erroneous detection hardly occurs. (G2) A point in time when toner is no longer detected by the toner sensor 21 even though the toner sensor 21 is provided near the toner supply port 10a of the developing device 10 that is far away from the developing roller 12. The remaining amount of toner in the developing device 10 at each of the developing devices 10 (Y,
C, M, K) so that each developing device 1
0 is changed in accordance with the attitude of the developing device, the remaining amount of toner in the developing device 10 at the time when the toner is no longer detected by the toner sensor 21 is determined by each developing device 10 (Y, C, M, K) are almost the same.
Therefore, despite having a plurality of developing devices 10 having different postures, After the toner cartridge 40 is replaced after the detection, there is no large difference in the total amount of toner in the developing device 10 and the toner cartridge 40, that is, the total weight of the developing device 10 and the toner cartridge 40. Therefore, when the plurality of developing devices 10 are configured to be movable, and when the development target is selectively developed by the selective movement thereof, the movement operation of each of the developing devices 10 with respect to the development target (for example, the contact / separation operation). A large difference does not occur in the driving load required for the image processing, and a difference does not easily occur in the movement operation timing of each of the developing units 10 (Y, C, M, and K). As a result, a decrease in image quality is prevented. 2. After the above detection, when the toner cartridge 40 is replaced, there is no large difference in the toner supply time from the cartridge 40 to the developing device 10, so that the user is not worried. (H) The internal shape of each developing device 10 is such that the remaining amount of toner is
Since the developing device 10 is configured to be larger than the remaining amount at which the toner deterioration is accelerated, the above-described configuration, the operation and the effect that the inner shape of the developing device 10 is smaller in the toner capacity on both sides of the central portion C than the central portion C are. In addition, the following operation and effect can be further obtained. That is, the toner in the developing device 10 deteriorates in the process of flowing while contacting the developing roller 12 and the inner wall of the developing device 10. The toner remaining in the developing device 10 without being supplied to the object to be developed via the developing roller 10 continues to flow in the developing device 10 and deteriorates mainly in contact with the developing roller 12 in the process. Becomes Deterioration of the toner, that is, a change in the shape of the toner, embedding or peeling of the external additive, deteriorates the chargeability and fluidity of the toner. When the charging property is deteriorated, the adhesive force to the developing roller 12 is reduced, so that toner scattering, toner leakage, transfer efficiency deterioration (accordingly, waste toner rate is increased), and the like are likely to occur. When the fluidity deteriorates, the developing roller 12
The uniformity of image quality is likely to be impaired since the uniformity of adhesion to the image is impaired. When the toner amount in the developing device 10 falls below a certain amount, the deterioration speed of the toner is exponentially accelerated. On the other hand, according to the developing device of this embodiment, the toner sensor 2
1 so that the remaining amount of toner in the developing device 10 at the time when the toner is no longer detected by the number 1 becomes larger than the remaining amount (the above-mentioned fixed amount) at which the toner deterioration is accelerated.
, The inner shape of the developing device 10 is combined with the above-described configuration and the operation and effect that the toner capacity on both sides of the developing device 10 is smaller than that of the central portion C. Before the remaining amount falls below the predetermined amount, the toner cartridge 40 is surely replaced and new toner is supplied. Thereby, the new toner is mixed with the toner remaining in the developing device 10, and
Since the amount of toner in the developing device 10 exceeds the above-mentioned fixed amount, as a result, according to this developing device, the developing device 10
The remarkable deterioration of the toner inside is surely prevented. Therefore, scattering of toner, leakage of toner, deterioration of transfer efficiency (accordingly, increase of waste toner rate) and the like are less likely to occur, and uniformity of adhesion to the developing roller 12 is also maintained, so that uniformity of image quality is also maintained. The Rukoto.

<Second Embodiment> FIG. 6 is a schematic front sectional view showing a second embodiment of the developing device (or developing device) according to the present invention. In the figure, the same or corresponding parts as those in the first embodiment (FIGS. 1 and 2) are denoted by the same reference numerals or the same reference numerals with "". This embodiment differs from the first embodiment in that the inner shape of the developing device 10 is changed by changing the shape of the agitator 16 'and / or 17' between the central portion C and both sides thereof. The configuration is such that the toner capacity on both sides is reduced, and there is no other difference. For example, as shown in FIG. 7, by increasing the outer diameter of the shafts 16 a and 17 a of the first and / or second agitators 16 ′ and 17 ′ on both sides of the central portion C, the inner shape of the developing device 10 is changed. , The central portion C and both sides thereof. The thicker part is denoted by reference numeral 1.
This is indicated by 6a1 (17a1). By changing the shape of the agitator between the central portion C and both sides thereof so as to reduce the toner capacity in the developing device on both sides, it is possible to make the inner wall shape of the case 11 common. Become. When the inner wall shape of the case 11 is changed as in the first embodiment in the case where the agitator has a plurality of agitators 16, 17, the agitator 16, 1 is used.
7 may not be carried smoothly. For example, as shown in FIG. 8, the first and second agitator chambers 13 and 14 are configured to be small on both sides of the central portion where the toner sensor 21 is provided, so that the toner capacity on both sides is reduced. In this case, as can be seen from the rotation trajectories of the first and second agitators 16 and 17, areas where the agitator and the toner do not contact each other are formed on both sides of the central portion, and the toner is smoothly transported by the agitators 16 and 17. As a result, the toner (T1) may be stagnated between the first agitator chamber 13 and the second agitator chamber 14, or between the second agitator chamber 14 and the developing chamber 15, as indicated by reference numeral T1. On the other hand, as in this embodiment (see FIGS. 6 and 7),
If the configuration is such that the toner capacity on both sides is reduced by changing the shape of the agitator, such a fear is eliminated.

<Another Embodiment of Developing Apparatus> This embodiment is another embodiment of the developing apparatus.
As described above, the toner sensor 21 includes a plurality of developing devices provided at substantially the center portion C with respect to the longitudinal direction of the developing roller 12 in the case 11 at different angles of inversion. Relatively large developing units 10Y, 1
0C (see FIG. 1) is, for example, shown in FIG.
As shown in the example of Y, the inner wall shape of the case 11 is changed between the central portion C and both sides thereof, for example, as shown in FIG. 4, so that the toner capacity on both sides is reduced. For the developing units 10M and 10K having a relatively small inverted angle (see FIG. 1), for example, as shown in FIGS. 6 and 7, the shapes of the agitators 16 and 17 are changed between the central portion C and both sides thereof. Thus, the configuration is such that the toner capacity on both sides is reduced.

With this configuration, the following operation and effect can be obtained. That is, the developing devices 10Y and 10C having relatively large inverted angles are configured such that the inner wall shape of the case 11 is changed between the central portion C and both sides thereof, so that the toner capacity on both sides is reduced. Therefore, as compared with the case where the shapes of the agitators 16 and 17 are changed, it is possible to easily make the configuration such that the toner capacity on both sides is reduced, and the degree of freedom of the agitator shape can be secured. As described above, when the developing device has a plurality of agitators and the inner wall shape of the case 11 is changed, the toner may not be smoothly transported by the agitator as described above. Developing devices 10Y and 10C in which the inner wall shape of case 11 is changed in the developing device
Is a developing device having a relatively large inverted angle, so that even when the inner wall shape of the case 11 is changed, the toner is smoothly transported with the aid of the free fall.
That is, as shown in FIG. 9, for example, even if the toner T1 is stuck between the first agitator chamber 13 and the second agitator chamber 14, or between the second agitator chamber 14 and the developing chamber 15, T1 moves smoothly to the second agitator chamber 14 or the developing chamber 15 with the help of free fall.

On the other hand, the developing device 10 having a relatively small inverted angle
For M and 10K, as shown in FIGS. 6 and 7, for example, the shape of the agitators 16 and 17 is changed between the central portion C and both sides thereof so that the toner capacity on both sides is reduced. Case 11
Of the inner wall can be made common. In addition, the toner is smoothly transported.

<Third Embodiment> FIG. 10 is an essential part of an image forming apparatus using a developing device (or developing device) according to a third embodiment of the present invention, which is different from that of FIG. FIG. In the figure, the same or corresponding parts as those in the first embodiment (FIGS. 1 and 2) are denoted by the same reference numerals or the same reference numerals with "". In this image forming apparatus, a photoreceptor carrying a latent image to be developed is constituted by a photoreceptor belt 6 stretched over a roller 6a. Developing units 10 '(Y, C, M, K) having a shape are arranged in the same posture in the vertical direction. As in the first embodiment, the toner sensor 21 is disposed inside the case 11 'in the longitudinal direction of the developing roller 12 (the direction perpendicular to the plane of FIG. 6).
The developing device 10 'is configured such that the toner capacity on both sides thereof is smaller than that of the central portion C. Therefore, also in this embodiment, (a), (b), (c), (d), and (e) obtained by the first embodiment are obtained.
The effect (f) is obtained. Although the attitudes of the developing units are not different, (g1) and (g2)
The same effect as (h) can be obtained. Further, when the configuration is the same as that of the second embodiment, the same operation and effect as those of the second embodiment can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the present invention. For example, the shape (size) of the bulging portion of the case 11 or the shape of the agitator can be appropriately set according to the remaining amount of toner at the time of toner end detection.

[0045]

According to any one of the first to fourth aspects of the present invention, it is difficult for defective development to occur, and toner end is detected even though toner remains in an unnecessarily large amount. Can be reduced. In addition, it is possible to reduce the degree of occurrence of a situation where the remaining amount of toner at the time of toner end detection becomes too small. Further, according to the developing device of the second aspect, it is possible to easily reduce the toner capacity on both sides of the developing device, and it is possible to secure the degree of freedom of the agitator shape.
According to the developing device of the third aspect, the inner wall shape of the case can be made common, and the toner can be smoothly transported by the agitator. Claim 4
According to the developing device described above, when the image forming apparatus is to form a full-color image, it is possible to easily arrange a plurality of developing devices in the vertical direction, and furthermore, in the longitudinal direction of the developing roller. Developing failure due to the inclination is less likely to occur irrespective of the direction of the inclination, and the toner end is detected even though the toner remains in an unnecessarily large amount. It is possible to reduce the degree of occurrence of a situation in which the number becomes too small. According to the developing device of the fifth aspect, even when the developing device is inclined with respect to the longitudinal direction of the developing roller, poor developing hardly occurs, and the toner remains in an unnecessarily large amount. It is possible to reduce the degree of occurrence of a situation in which toner end is detected or the amount of toner remaining at the time of toner end detection becomes too small. Further, a developing device having a relatively large inverted angle can be configured so that the toner capacity on both sides of the developing device can be easily reduced as compared with a case where the shape of the agitator is changed. As for the developing device having a relatively small inverted angle, the shape of the inner wall of the case can be made common, and the toner can be transported smoothly.

[0046]

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view showing a main part of an example of an image forming apparatus using a developing device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partially omitted plan view of the developing device 10.

FIG. 4 is a partially omitted perspective view of the developing device 10.

5 (a), 5 (b), 5 (c) and 5 (d) are conceptual views for explaining the operation, FIG. 5 (e) is a plan view of FIG. 5 (a), and FIG. 5 (f) is a side view of FIG.

FIG. 6 is a schematic front sectional view showing a second embodiment of the developing device according to the present invention.

FIG. 7 is a sectional view of a shaft of the agitator.

FIG. 8 is an explanatory diagram of the same operation.

FIG. 9 is a front sectional view showing an example of a developing device in the embodiment of the developing device.

FIG. 10 is a schematic front sectional view showing a main part of an example different from that of FIG. 1 of an image forming apparatus or a developing device using a third embodiment of the developing device according to the present invention.

11 (a), (b) and (c) are conceptual diagrams for explaining a problem, (e) is a plan view of FIG. (A), and (f) is a diagram (e)
Side view.

12 (a), (b), (c), and (d) are conceptual diagrams for explaining a problem, (e) is a plan view of FIG. (A), and (f) is a side view of FIG.

FIG. 13 is an explanatory diagram of an example of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Developing device 11 Case 12 Developing roller 16, 17 Agitator C Central part 21 Toner sensor 40 Toner cartridge

Claims (5)

[Claims] 1. A developing device comprising: a case; a developing roller rotatably provided with respect to the case; and a toner sensor for detecting a remaining amount of toner contained in the case, In the case, a toner sensor is provided at a substantially central portion with respect to the longitudinal direction of the developing roller, and an inner shape of the developing device is such that a toner capacity on both sides of the central portion where the toner sensor is provided is provided. A developing device characterized in that the developing device is configured to reduce the number of toner images. 2. The image forming apparatus according to claim 1, wherein the inner shape of the case is configured such that the inner wall shape of the case is changed between the central portion and both sides thereof so that the toner capacity on both sides is reduced. 2. The developing device according to 1. 3. An agitator for agitating the toner is provided in the case, and the inner shape of the case is changed by changing the shape of the agitator between the central portion and both sides thereof, so that the toner capacity on both sides is reduced. 2. The developing device according to claim 1, wherein the developing device is configured to reduce the number. 4. The developing device according to claim 1, wherein said case has a flat shape. 5. A case, a developing roller rotatably provided with respect to the case, a plurality of agitators for transporting toner contained in the case toward the developing roller, and a case contained in the case. A developing device having a plurality of developing devices having a toner sensor for detecting the remaining amount of toner is provided at different inverted angles, wherein the toner sensor is disposed in the case in a longitudinal direction of the developing roller. The developing device is provided at a substantially central portion with respect to the direction, and for the developing device having the relatively large inverted angle, by changing the inner wall shape of the case between the central portion and both sides thereof, the toner capacity on both sides is reduced. In the developing device having a relatively small inverted angle, the shape of the agitator can be changed between the central portion and both sides thereof. Wherein the toner capacity on both sides is reduced.