JPH11344855A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device using a small-sized developing device, which even when a quantity of toner remaining in the developing device decreases, maintains the ability to supply the developer to a developing roller and obtains an image having satisfactory density. SOLUTION: This image forming device develops a latent image on a photoreceptor by the use of the developing device 21, equipped with the developing roller 35 for holding the toner on itself, a toner supply roller 36 for supplying the toner to the developing roller, agitators 37 and 38 for carrying the toner to the toner supply roller, and a remaining-toner quantitative sensor 41 for detecting the quantity of remaining toner. In this case, according to the result of the detection by the remaining-toner quantitative sensor, the number of the rotations of each of the agitators is increased to enhance the ability for carrying the toner to the vicinity of the toner supply roller. Therefore, even if the toner in the developing device decreases, the quantity of toner carried to the vicinity of the toner supply roller tends not to decrease, which makes it possible to maintain the quantity of toner which the toner supply roller supplies to the developing roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, a printer, and the like. The present invention relates to an image forming apparatus that develops an electrostatic latent image on a latent image carrier using a developing device having a developer remaining amount detecting unit that detects a remaining amount of developer.

[0002]

2. Description of the Related Art In the above-mentioned image forming apparatus, a developing device using a one-component developer is used in view of downsizing, cost reduction and high reliability of the developing device. Such a developing device contains a one-component developer therein, carries the developer, and transports the developer to a development area facing the latent image carrier, and a developer on the developer carrier. A developer supply member that supplies the developer, a developer transport member that transports the developer to the developer supply member, and a developer remaining amount detection unit that detects the remaining amount of the developer in the developing device. .

[0003] The developer transport member transports the developer to the vicinity of the developer supply member. The developer supply member conveys the developer nearby and supplies it to the developer carrier. The developer carrier carries the developer on its surface and transports the developer to a development area facing the latent image carrier, where development based on the latent image on the latent image carrier is performed. With such a developing operation, the developer in the developing device is consumed. However, based on the detection result of the developer remaining amount detecting means, the remaining amount of the developer decreases and it is determined that the remaining amount is insufficient. When it reaches, it indicates that the developer is low,
The user is urged to supply the developer. Further, even if the remaining amount does not become insufficient, if the remaining amount of the developer decreases, the image density may become insufficient. That is, when the remaining amount of the developer decreases, the amount of the developer conveyed to the vicinity of the developer supply member decreases, and the amount of the developer conveyed by the developer supply member decreases. For this reason, the ability of the developer supply member to supply the developer to the developer carrying member is reduced, and the developer carrying member cannot carry a sufficient amount of the developer.

In order to solve such a problem, there has been known a developing device having a structure in which a space is increased near a developer supply member and a large amount of developer can be stored near the developer supply member. In this developing device, even when the remaining amount of the developer in the entire developing device decreases, a large amount of the developer is already stored in the vicinity of the developer supply member. The quantity is hard to decrease. For this reason, it is possible to prevent a decrease in the ability of the developer supply member to supply the developer to the developer carrier.

Further, the apparatus is provided with a high-sensitivity developer remaining amount detecting means. When the amount of the developer in the developing device decreases to a level at which the amount of the developer conveyed by the developer supply member starts to decrease,
There is also known a developing device in which the detection is performed by the high-sensitivity detecting means, and at this stage, the remaining amount of the developer is set to be displayed. As described above, before the amount of the developer conveyed by the developer supply member in the developing device starts to decrease, the remaining amount of the developer is displayed and the user is urged to supply the developer. A decrease in the ability of the supply member to supply the developer to the developer carrier can be prevented.

[0006]

However, as described above, in the developing device in which the space is increased in the vicinity of the developer supply member, the size of the device is increased and the advantage that the one-component developing device can be reduced in size is sufficient. I can't. Also,
There is a disadvantage that the amount of unusable toner, that is, dead toner is increased. Further, when the force of the developer supply member acts on the toner in the space near the developer supply member, blocking tends to occur, and the developer supply capability may be reduced.

Further, even in an apparatus using a highly sensitive developer remaining amount detecting means, it is necessary to increase a developer accommodating space of the developing apparatus in order to maintain an interval of replenishing the developer by a user. It becomes large. Further, when the developer remaining amount detecting means is made to have high sensitivity, there is a disadvantage that erroneous detection is likely to occur.

The present invention has been made in view of the above problems, and has as its object to reduce the amount of developer conveyed by a developer supply member even when the remaining amount of developer in a developing device is reduced. It is an object of the present invention to provide an image forming apparatus using a small-sized developing device capable of preventing a decrease in the image density, maintaining a developer supply capability to a developer carrying member, and obtaining an image having a good density.

[Means for Solving the Problems]

According to another aspect of the present invention, there is provided a developer carrying member carrying a one-component developer, a developer supply member for supplying a developer to the developer carrying member, and a developing device. A developer transport member that transports the developer to the vicinity of the developer supply member;
An image forming apparatus for developing an electrostatic latent image on a latent image carrier using a developing device having a developer remaining amount detecting means for detecting a remaining amount of the developer in the developing device. The number of rotations of the developer conveying member is increased according to a detection result of the detecting means.

According to the first aspect of the present invention, when it is determined that the remaining amount of the developer has decreased according to the detection result of the remaining amount of the developer, the rotation speed of the developer conveying member is increased and the developer is increased. The ability to transport the developer to the vicinity of the supply member is improved. For this reason, even if the remaining amount of the developer in the developing device is reduced, the amount of the developer conveyed to the vicinity of the developer supply member is hard to decrease, and the developer supplied to the developer carrier by the developer supply member is hardly reduced. Can be maintained.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the number of rotations of the developer conveying member is increased,
When it is determined that the remaining amount of the developer is further reduced based on the detection result of the remaining amount of the developer, a near end is displayed,
The present invention is characterized in that the user is encouraged to supply the developer.

According to the second aspect of the present invention, it is determined whether the remaining amount of the developer has reached a level at which the number of rotations of the developer transport member is increased and then the level indicating the near end is determined. In addition, it is possible to reduce the probability of near-end erroneous display due to erroneous detection of the remaining amount.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, a near end is displayed, a user is urged to replenish the developer, and further development is performed based on a detection result of the developer remaining amount detecting means. When it is determined that the remaining amount of the agent has decreased to a predetermined value or less, an end is displayed and the image forming operation is stopped.

According to the third aspect of the present invention, when it is determined that the remaining amount of the developer has decreased to a predetermined value or less, the end is displayed and the image forming operation is forcibly stopped. To prevent image formation while the shortage occurs. For this reason, the fluctuation amount of the density of the image formed by the present apparatus can be reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a two-color digital image forming apparatus which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a two-color digital image forming apparatus according to the present embodiment. First, the basic configuration and operation of the image forming unit of the two-color digital image forming apparatus will be described. The two-color digital image forming apparatus shown in FIG. 1 includes a first charging device 24, a first exposing device 25 for exposing a black image, and a first exposing device 25 for black developing around a photoreceptor 11 as a latent image carrier. A developing device 20, a second charging device 27,
A second exposure device 28 for red image exposure, a second development device 21 for red development, a transfer device 17 for transferring a toner image on the photoconductor onto transfer paper, and removal of residual toner from the surface of the photoconductor 1 A cleaning device 22 and a static elimination device 23 are provided. First exposure device 25 and second exposure device 28
As the light source, a laser diode or an LED is used.

After the photosensitive member 11 is uniformly charged by the first charging device 24, optical writing is performed on the surface of the photosensitive member 11 by the first exposure device 25 to form an electrostatic latent image of a black image.
This electrostatic latent image is supplied with black toner by the first developing device 20 for black development to form a toner image as a visible image. Further, after the photoconductor 11 is substantially uniformly charged by the second charging device 27, optical writing is performed on the surface of the photoconductor 11 by the second exposure device 28, and an electrostatic latent image of a red image is formed. This electrostatic latent image is supplied with red toner by a second developing device 21 for red development, and forms a two-color toner image on the photoconductor 11. The two-color toner image on the photoconductor 11 is transferred to transfer paper by a transfer device 17, separated from the photoconductor 11 by a separation device 18, and fixed by a fixing device 19. On the other hand, the untransferred toner is collected from the photoreceptor 11 after the transfer by the photoreceptor cleaning device 22, and the residual charge is removed by the charge removing device 23 in preparation for the next charging.

FIG. 2 is a schematic configuration diagram of a second developing device 21 for developing red in the two-color digital image forming apparatus according to the present embodiment. The second developing device 21 contains a non-magnetic red toner as a one-component developer, a toner supply roller 36 as a developer supply member, a development roller 35 as a developer carrier, and a surface of the development roller 35. A thinning blade 39 as a developer regulating member for regulating the toner, a spacer roller 40 for keeping a gap between the developing roller 35 and the photoconductor 1, and an agitator for stirring the red toner in the second developing device 21 38, and an agitator 37 as a developer conveying member for conveying the red toner from the toner container to the toner supply roller 36 while stirring.

In the second developing device 21, the red toner contained in the developing device is agitated by the rotation of the agitator 38 in the direction of the arrow, and further stirred by the rotation of the agitator 37 in the direction of the arrow. The toner is further conveyed to the vicinity of the toner supply roller 36. The red toner conveyed to the vicinity of the toner supply roller 36 is conveyed to a portion facing the developing roller 35 by the rotation of the toner supply roller 36 in the direction of the arrow. The toner supply roller 36 and the developing roller 35 are arranged so as to contact each other at the opposing portion.
A predetermined potential difference is formed between the toner supply roller 36 and the developing roller 35 by a bias applying unit (not shown).
An electrostatic force is generated that causes the transition to By this electrostatic force, the red toner of the toner supply roller 36 is
5 Transfer to the surface. The red toner transferred to the surface of the developing roller 35 is caused by the rotation of the developing roller 104 in the direction of the arrow, and the thinning blade 39 in contact with the developing roller 35.
And is triboelectrically charged to a desired polarity. Then, the toner transferred to the surface of the developing roller 35 is conveyed to a portion facing the photoconductor 11 as a latent image carrier by rotation of the developing roller 35 in the direction of the arrow. Photoconductor 1
A gap of about 0.15 mm is maintained between the developing roller 1 and the developing roller 35 by a spacer roller 40. When a developing bias is applied to the developing roller 35 from a developing bias power supply (not shown), an electrostatic latent image on the surface of the photoconductor 11 is formed. Are developed with the red toner. Here, a DC bias is applied to the developing roller 35 of the second developing device 21 so as not to disturb the black toner image developed on the surface of the photoconductor 11 by the first developing device 20.

Further, the second developing device 21 has a toner remaining amount sensor 41 for detecting the remaining amount of red toner in the device, and the agitator is provided on the lower surface of the developing device 38 below. When it is determined from the detection result of the toner remaining amount sensor 41 that the remaining amount of red toner in the developing device has decreased below a certain level, the rotation speed of the agitators 37 and 38 is increased. As a result, the ability to transport the toner from the toner container to the vicinity of the toner supply roller 36 is increased. For this reason, even if the remaining amount in the apparatus is reduced, the amount of the red toner conveyed to the vicinity of the toner supply roller 36 is hard to decrease, and the amount of the red toner supplied to the developing roller 35 by the toner supply roller 36 is maintained. It is possible to do. Since the amount of red toner carried by the developing roller 35 is maintained, it is possible to prevent a decrease in image density during development. FIG. 3 shows the relationship between the remaining amount of toner and the image density when the rotation speed of the agitators 37 and 38 is increased (a) and when the number of rotations is not increased (b), based on the detection result of the toner remaining amount sensor 41 described above. . It can be seen that the image density is less likely to decrease even when the remaining amount of toner decreases, as compared with the case where the number of rotations is increased and the case where the number of rotations is not increased.

Also, as described above, the agitators 37, 38
When it is determined that the amount of red toner has further decreased based on the detection result of the toner remaining amount sensor 41 after the rotation speed of is increased, the near end is displayed and the user is urged to supply toner. As described above, it is determined whether the remaining amount of the red toner has reached the level at which the rotation speed of the agitators 37 and 38 is increased, and then whether or not the remaining amount has reached the level at which the near end is displayed. Can be reduced. This is more effective when it is necessary to make the toner remaining amount sensor highly sensitive and to perform the remaining amount detection at a fine level.

Further, a near end is displayed to urge the user to replenish the developer, and when it is determined that the remaining amount of the red toner has decreased to a specified value or less, the end is displayed and the image forming operation is performed. To stop. As described above, by forcibly stopping the image forming operation, it is possible to form an image having a reduced density due to a shortage of the remaining amount of toner. For this reason, the image formed by the present image forming apparatus has a small amount of fluctuation in density.

[0022]

According to the first to third aspects of the present invention,
Even when the remaining amount of the developer in the developing device is reduced, the developer supply member prevents the amount of the developer to be conveyed from decreasing, maintains the developer supply capability to the developer carrier, and achieves a good density. There is an excellent effect that an image can be obtained.

In particular, according to the second aspect of the invention, there is an excellent effect that the probability of a near-end erroneous display due to erroneous detection of the remaining amount can be reduced, and the burden on the user can be reduced.

In particular, according to the third aspect of the present invention, there is an excellent effect that the amount of change in density of an image to be formed can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment.

FIG. 2 is a schematic configuration diagram of a second developing device employed in the image forming apparatus according to the embodiment.

FIG. 3 is an explanatory diagram of a relationship between a remaining amount of toner and an image density in the image forming apparatus according to the embodiment and the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 photoconductor 17 transfer device 20 first developing device 21 second developing device 22 cleaning device 23 static elimination device 24 first charging device 25 first exposure device 27 second charging device 28 second exposure device 35 developing roller 36 toner supply roller 37 Agitator 38 Agitator 39 Thinning blade 40 Spacer roller 41 Remaining toner sensor

Claims (3)

[Claims] A developer carrying member carrying a one-component developer;
A developer supply member for supplying a developer to the developer carrier,
A developer conveying member for conveying the developer to the developer supply member; and a developing device having a developer remaining amount detecting unit for detecting the remaining amount of the developer in the developing device. An image forming apparatus for developing an electrostatic latent image, wherein the number of rotations of the developer conveying member is increased in accordance with a detection result of the developer remaining amount detecting means. 2. The image forming apparatus according to claim 1, wherein the number of rotations of the developer conveying member is increased, and when it is determined from the detection result of the remaining amount of developer that the remaining amount of developer is further reduced, An image forming apparatus, wherein a near-end is displayed and a user is urged to supply developer. 3. An image forming apparatus according to claim 2, wherein a near end is displayed, a user is urged to replenish the developer, and the remaining amount of the developer is further set to a predetermined value based on a detection result of the developer remaining amount detecting means. An image forming apparatus characterized in that an end is displayed and the image forming operation is stopped when it is determined that the number has decreased below.