JP2014106434A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing a risk of excessively replenishing toner, even when a mis-detection in which the toner does not exist is performed.SOLUTION: The image forming apparatus includes a stirring member stirring a developer in a developing container, a stirring torque detection part detecting the torque of the stirring member, and a control part controlling the replenishment operation of a developer replenishing part, so as to replenish the developer up to a predetermined position in the developing container, based on the detection result of a detection sensor, the developing container including the detection sensor detecting the presence or absence of the developer in the predetermined position in the developing container and a cleaning member cleaning the detection part of the detection sensor. In the image forming apparatus, when it is detected that the developer does not exist in the predetermined position and the detection result of the stirring torque detection part is within a predetermined range, the control part performs controlling so as to execute a mode in which an image forming operation is continued in such a state that the replenishment of the developer into the developing container is forcibly stopped, based on the detection result of the detection sensor.

Description

  The present invention relates to an image forming apparatus such as a copying machine and a laser beam printer, and more particularly to an image forming apparatus that replenishes a developer container with a developer replenishing device.

  A developing container mounted on an image forming apparatus such as a copying machine or a laser beam printer is disposed long along the photosensitive drum. The developer replenishing device (hereinafter referred to as “toner replenishing device”) for replenishing the developer in the developer container includes a transport supply member for replenishing the developer substantially uniformly over the longitudinal direction of the developer container, and a developer on the transport supply member. Some of them are constituted by a developer storage and discharge device to be replenished.

  Here, the toner amount in the developing container is detected by a toner remaining amount detection sensor. Further, a wiper that scrapes off the toner adhering to the detection unit is provided so that the detection unit of the remaining amount detection sensor can surely detect it. The wiper is formed integrally with the conveyance supply member, and is configured to be interlocked with the rotation of the conveyance supply member.

  In this case, immediately after the wiper passes the detection unit of the remaining amount detection sensor, the toner attached to the detection unit is scraped, and thus no toner exists in the detection unit. Then, although the time is very short, the remaining amount detection sensor detects “no toner”. For this reason, even if the toner is sufficient in the developing device, the toner supply operation from the developer storage / discharge device is performed.

  In order to solve such a problem, an invention has been proposed in which toner detection is not performed when the wiper passes the detection unit of the remaining amount detection sensor in accordance with the rotation period of the wiper (for example, see Patent Document 1). .

JP 7-084445 A

  However, in the developing container of Patent Document 1, when an image with a small amount of toner consumption is output continuously on both sides of a large basis weight transfer material at high speed, the toner consumption amount with respect to the driving time of the developing device is reduced. Then, the temperature in the developing device rises, and the toner fluidizing external additive is easily embedded in the toner base.

  As a result, the fluidity of the toner decreases and the degree of aggregation of the toner increases. As a result, a void is easily formed in the toner in the developing device casing. When a cavity is generated, the remaining amount detection sensor may erroneously detect that the cavity is insufficient. Then, when the toner is replenished with this erroneous detection, the stirring torque is excessively increased. Then, there is a problem that the image forming operation is stopped.

  Next, this phenomenon will be described in detail with reference to FIG. FIG. 15 is a diagram showing a process of forming a cavity in the toner in the conventional example.

  First, the degree of toner aggregation will be described. Depending on factors such as durability of the apparatus and temperature rise, the toner may deteriorate and the degree of aggregation may increase. The degree of aggregation here is an index indicating the deterioration of the toner.

  The degree of aggregation is measured using a powder tester manufactured by Hosokawa Micron Corporation. First, a 200-mesh sieve with 75 μm sieve is set up, a 390-mesh sieve with 38 μm sieve inside, and a 635-mesh sieve with 25 μm sieve set down. Then, 5 g of developer aged overnight at 23 ° C. in a 50% environment was measured for 15 seconds by applying a vibration with an amplitude of 0.6 mm to the table, and calculated using the following formula.

First, (a), (b), (c) are changed as follows:
(A) Mass% of toner remaining on a sieve having a sieve mesh of 75 μm × 1
(B) Mass% of toner remaining on sieve having a sieve size of 38 μm × 0.6
(C) Mass% of toner remaining on sieve having a sieve size of 25 μm × 0.2
It is defined as

The degree of aggregation at this time is expressed by the following equation:
Aggregation degree = (a) + (b) + (c) (%)
As follows. Here, the case where the degree of aggregation was 30% or more was determined as toner deterioration.

  FIG. 15 is a diagram showing a process of forming a cavity in the toner in the conventional example. FIG. 15A is a diagram in which the wiper 112 has just passed through the detection unit of the remaining amount detection sensor 110. At this time, the toner (T) does not exist in the detection unit of the remaining amount detection sensor 110. Therefore, the remaining amount detection sensor 110 detects “no toner”.

  Here, if the toner (T) is not deteriorated, the wiper 112 passes through the detection unit of the remaining amount detection sensor 110, and then the state shown in FIG. That is, since the toner in the developing container 102 has high fluidity, the toner moves to the detection unit of the remaining amount detection sensor 110. As a result, immediately after the wiper 112 passes, the remaining amount detection sensor 110 detects “toner present”.

  However, when the toner is deteriorated, the fluidity of the toner is lowered. In this state, when the wiper 112 passes the detection unit of the remaining amount detection sensor 110, a state as shown in FIG. That is, the trace S of the wiper 112 remains in the detection unit of the remaining amount detection sensor 110, and the state where no toner exists in the detection unit of the remaining amount detection sensor 110 continues. As the toner aggregation degree increases, the time for which the state shown in FIG. 15C continues becomes longer.

  In this conventional example, the rotation period of the wiper 112 and the stirring blade 113 is 3 seconds. For this reason, even a certain degree of cohesion returns from the state of FIG. 15B after 3 seconds. If the toner weight in the developing unit is around 400 to 500 g, the toner having a high degree of aggregation is known to return to the state shown in FIG.

  In the state of FIG. 15C, the remaining amount detection sensor 110 continues to detect “no toner”. For this reason, although the toner amount in the developing container 102 is sufficient, the toner supply operation from the hopper 101 is continued, and the toner amount in the developing container 102 becomes excessive. If the toner is continuously replenished when the amount of toner in the developing container 102 is excessive, the rotational loads on the wiper 112 and the stirring blade 113 are greatly increased.

  Furthermore, if the toner is partially replenished at a high density before the toner (T) is sufficiently stirred in the developing container 102, the toner conveyance is hindered. Then, the toner in the screw guide 107 and the hopper 101 becomes excessive, and the rotational loads on the screw 106 and the hopper screw 109 in the screw guide 107 are greatly increased. Finally, the wiper 112 and the stirring blade 113 in the developing container may be damaged, the screw 106 and the hopper screw 109 may be damaged, or the drive motor (not shown) may be locked.

  This phenomenon occurs remarkably in a high-temperature and high-humidity environment, and particularly easily occurs when an image with a low printing rate is continuously fed.

  The toner in the developing container 102 in the state as shown in FIG. 15C is not always in that state, and a certain amount of time is required due to the consumption of the toner in the developing container 102 and the stirring operation of the stirring blade 113. When the time has elapsed, the state returns to the state of FIG.

  However, a replenishment method that always performs a supply operation in the “no toner” state as in the background art, or a replenishment method that does not detect the remaining amount only for a short time when the wiper 112 passes the detection unit of the remaining amount detection sensor 110. Then, it was not a sufficient countermeasure.

  An object of the present invention is to provide an image forming apparatus capable of suppressing the possibility that toner is excessively replenished even when it is erroneously detected that there is no toner.

A typical configuration of the present invention for achieving the above object is as follows.
An agitation member for agitating the developer in the developing container; an agitation torque detection unit for detecting the torque of the agitation member; a detection sensor for detecting the presence or absence of the developer at a predetermined position in the developer container; A control unit that controls a replenishment operation of the developer replenishment unit so that the developer is replenished to the predetermined position based on a detection result of the detection sensor with respect to a developing container having a cleaning member that cleans the detection unit; In an image forming apparatus having
The control unit detects that the developer is not present at the predetermined position based on the detection result of the detection sensor, and the developer container when the detection result of the stirring torque detection unit is within a predetermined range. The mode is characterized in that the mode in which the image forming operation is continued in a state where the supply of the developer to the inside is forcibly stopped is executable.

  According to the above configuration, reliable toner detection can be performed even in a high temperature and high humidity state.

1 is a configuration diagram illustrating a configuration of an image forming apparatus. Sectional drawing of a developing container and a toner replenishing device. The side view of a developing container and a toner replenishment apparatus. The schematic diagram of the stirring member which attached the wiper. 1 is a block diagram related to an image forming apparatus. 6 is a graph showing the relationship between the amount of toner in the developing container and the stirring drive motor current value. The flowchart which concerns on 1st Embodiment. The flowchart which concerns on 1st Embodiment. Aggregation degree table in stirring drive motor current value and toner-free count. 6 is a graph showing a change in current value of a stirring drive motor in the developing container according to the first embodiment. 6 is a graph showing a change in current value of a stirring drive motor in the developing container according to the first embodiment. 6 is a graph showing a change in current value of a stirring drive motor in the developing container according to the first embodiment. The flowchart which concerns on a comparative example. The graph which shows the agitation drive motor current value transition in the developing container concerning a comparative example. The figure which shows the process in which a cavity is made in a toner in a prior art example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, schematic configurations of the image forming apparatus and the developing device will be described.

[Image forming apparatus]
FIG. 1 is a configuration diagram showing the configuration of the image forming apparatus. In FIG. 1, the image forming apparatus A has a structure in which a primary charger 24, a developing container 2, a transfer unit 21, a cleaning unit 22, and a pre-exposure unit 23 are arranged around a photosensitive drum 20. In the present embodiment, the transfer unit 21 is configured to be a linear roller transfer, but is not limited thereto.

  The image forming apparatus A performs electrophotographic image formation in which a toner image obtained by developing the electrostatic latent image formed on the photosensitive drum 20 is transferred to a transfer sheet. The photosensitive drum 20 is an image carrier that carries an electrostatic latent image, and is rotated in the direction of arrow R by a drive mechanism (not shown).

  In the exposure step, laser light L corresponding to the image to be formed is exposed on the surface of the photosensitive drum by a laser driving unit (not shown), and an electrostatic latent image is formed.

  The developing container 2 includes a developing sleeve 3, an agitating member 13 (first agitating member), an agitating member 14 (second agitating member), a developing blade 5, and contains a developer made of magnetic toner. With this configuration, the electrostatic latent image on the surface of the photosensitive drum 20 is developed.

  The developing sleeve 3 is a developing carrier that carries toner (developer), and is disposed to face the photosensitive drum 20. In the development process, a development bias is applied to the development sleeve 3 from a development high-pressure substrate (not shown) in order to form a development electric field between the photosensitive drum 20 and the development sleeve 3. Along with this, the electrostatic latent image formed on the surface of the photosensitive drum 20 is developed by the developing container 2 and visualized as a toner image. In this embodiment, the toner is charged with a negative polarity.

  In the transfer process, the toner image on the photosensitive drum 20 is transferred by the transfer unit 21 to a transfer sheet conveyed by a sheet conveyance mechanism (not shown).

  Transfer residual toner on the photosensitive drum 20 is removed by a cleaning unit 22 having a cleaning blade 22 a pressed against the photosensitive drum 20. The transfer sheet onto which the toner image has been transferred is conveyed to a fixing device (not shown).

  In the fixing process, the toner image on the transfer sheet is fixed by the fixing device. The transfer sheet on which the toner image is fixed is discharged out of the image forming apparatus A. Thereafter, the photosensitive drum 20 is discharged by the pre-exposure unit 23 and used for image formation again.

[Outline of developing device]
2 and 3 show the configuration of the hopper 1 which is a toner replenishing device. FIG. 2 is a cross-sectional view of the developing container and the toner supply device. More specifically, it is a cross-sectional view seen from the front. FIG. 3 is a side view of the developing container and the toner supply device.

  As shown in FIGS. 2 and 3, the developing container 2 is disposed below the hopper 1 (developer supply part). The toner stored in the developing container 2 is agitated and conveyed as described later, and after the toner amount is regulated by the developing blade 5 (developer layer thickness regulating plate), the toner is supplied to the developing sleeve 3 (developer carrier). Is done.

  The toner in the hopper 1 is discharged to part A in FIG. 2 by the hopper screw 9 and further conveyed in the direction of arrow P by the conveying screw 6. The conveying screw 6 is accommodated in a screw guide 7. Part of the screw guide 7 in the circumferential direction of the conveying screw 6 is released, and the toner conveyed by the conveying screw 6 is supplied substantially uniformly in the P direction (longitudinal direction) of the supply roller 4.

  A magnet roller (not shown) having a magnetic force is disposed in the supply roller 4, and toner that is a magnetic material is held on the supply roller 4 by the magnetic force of the magnet roller. The supply roller 4 rotates in the direction of arrow Q in FIG. 3 and conveys the toner on the supply roller 4 to the scraper 8 part. The scraper 8 is disposed close to the supply roller 4, scrapes off the toner conveyed into the developing container 2 and supplies the toner into the developing container 2.

  The toner in the developing container 2 is conveyed through the developing container by the stirring member 13 and the stirring member 14. The toner that has reached the developing sleeve 3 is held by the developing sleeve 3. In addition, the stirring member 13, the stirring member 14, and the conveyance screw 6 are each connected with a gear (not shown), and are driven by a motor described later.

  2 and 3, a detection sensor 10 that detects the presence or absence of toner at a predetermined position is disposed outside the developing container 2 in the longitudinal direction of the stirring member 13. The detection sensor 10 detects the amount of toner in the developing container 2. When the toner is empty in the developing container 2, the detection sensor 10 detects “no toner”. While “no toner” is detected, toner is continuously supplied from the hopper 1 to the developing container 2. When the developing container 2 is filled with toner, the detection sensor 10 detects “there is toner”. When the detection sensor 10 detects “toner present”, the supply of toner from the hopper 1 is stopped.

  When the toner in the developing container 2 is consumed by continuing the image forming operation, the detection sensor 10 detects “no toner” again. Then, the toner supply from the hopper 1 is resumed. By this operation, the toner in the developing container 2 is controlled to become a predetermined amount or more.

  FIG. 4 is a schematic view of a stirring member attached with a wiper. As shown in FIG. 4, a wiper 12 for scraping off toner adhering to the detection unit 10 a of the detection sensor 10 is attached to the end of the stirring member 13 on the side where the detection sensor 10 is disposed.

  The wiper 12 (cleaning member) incorrectly detects that the toner is stagnant in the detection unit 10a of the detection sensor 10 and the toner in the developing container 2 is actually decreasing, but the detection sensor 10 is “toner present”. This is to prevent detection. Since the wiper 12 is installed integrally with the stirring member 13, the wiper 12 is cleaned by scraping off the toner in the vicinity of the detection unit 10a of the detection sensor 10 in accordance with the rotation of the stirring member 13.

  FIG. 5 is a block diagram according to the image forming apparatus. In the image forming apparatus A, the stirring member 13, the stirring member 14, and the conveying screw 6 are rotated by driving from the stirring drive motor 34 shown in FIG. The agitation drive motor 34 is connected to the power source 31 and grounded via a resistor 36. The torque applied to the stirring drive motor 34 is detected as a current value by the stirring torque detector 37.

  Moreover, the hopper screw 9 rotates by the drive from the hopper motor 33 shown in FIG. The hopper motor 33 is connected to the power source 31 and grounded via the resistor 35. The hopper motor 33 is controlled to be turned on and off by a transistor 32 disposed between the power source 31 controlled by the CPU 30 (control unit) and the hopper motor 33.

  The output from the detection sensor 10 is monitored by the CPU 30 as a detection result. As a result, the CPU 30 constantly detects the states of “with toner” and “without toner”. However, even if “no toner” is detected, it is not determined that there is no toner for 0.8 seconds in consideration of the wiper 12 passing over the detection surface of the detection sensor 10.

  In the present embodiment, the detection cycle of the detection sensor 10 is monitored 10 times at 100 m intervals. The threshold value is determined to be “toner present” in the developing container at that time when receiving a signal of “toner present” three or more times among the signals monitored ten times, and the toner from the hopper 1 to the developing container 2 is determined. Stop supplying. When the toner presence signal is 2 times or less, the replenishment of the developing container 2 from the hopper 1 is continued. In this embodiment, the “no toner” state indicates a state in which the number of toner detections is two times or less in one second.

  By performing the above control, the toner weight in the developing container 2 is always stable at around 500 g. A state in which toner in a toner bottle (not shown) that supplies toner to the hopper 1 and toner in the hopper 1 have been consumed, that is, a state where there is only about 500 g of toner in the developing container is referred to as toner low. If the toner is low, the user is prompted to replace the toner bottle. At this time, the image forming operation is continued. The toner low period is a period during which 150 g of toner in the developing container 2 is used.

  The state in which the image forming operation is continued in the toner low state and the toner amount in the developing container 2 becomes 350 g or less is referred to as “toner end”. In the toner end state, the image forming operation is prohibited.

  If 150 g is continuously fed at a printing rate of 5%, 3k sheets or more can be printed on one side of A4. The specification of the image forming apparatus in the present embodiment enables printing of 100 sheets per minute. At that time, it takes about 30 minutes to consume 150 g.

  The toner detection sensor 10 receives a toner-less signal 10 times in 1 second until the toner End is reached after the toner Low is turned on, and is 1 time 600 times in 1 minute and 18000 times in 30 minutes (600 times * 30 minutes). Receives no toner signal.

  Further, the CPU 30 monitors the current value of the stirring drive motor 34 (current applied to the stirring torque detection unit 37) as a detection result. This is because the current value increases as the load torque of the agitation drive motor 34 increases, and the current value also decreases as the load torque decreases, so the current value is monitored as an alternative to the torque of the agitation drive motor 34.

  In this embodiment, the motor current is used as an alternative to the stirring torque, but the present invention is not limited to this. For example, a method of directly detecting the agitation torque using a tolometer or the like may be used.

  FIG. 6 is a graph showing the relationship between the toner amount in the developing container and the stirring drive motor current value. As shown in FIG. 6, when the toner is not deteriorated, the current value of the stirring drive motor 34 is 0.3 A or less even in the “toner present” state. On the other hand, when the toner is deteriorated, the current value of the agitation drive motor 34 is always higher than when the toner is not deteriorated. Specifically, it becomes 0.3 A or more even in the “no toner” state.

  Further, when the toner is supplied exceeding the upper limit value of the toner that can be stored in the developing container 2, the current value of the agitation drive motor 34 increases rapidly and reaches an error of 0.6A. Therefore, in this embodiment, 0.3 A, which is lower than 0.6 A at which the stirring drive motor 34 causes an error, is set as the predetermined value for determining the current value. If it is 0.3 A or more, the current value is determined to be “high”, and if it is less than 0.3 A, it is determined to be “low”.

  Thus, the case where the current value of the agitation drive motor 34, that is, the detection result of the agitation torque detector 37 is within a predetermined range is used as a reference. In the present embodiment, when the detection result of the agitation torque detector 37 is within a predetermined range, the mode in which the image forming operation is continued with the toner supply in the developing container 2 being forcibly stopped is controlled to be executable. . On the other hand, when the detection result of the agitation torque detector 37 is below a predetermined range, control is performed so as to execute a replenishment operation for continuing the replenishment of the developer into the developer container 2. Next, a specific description will be given.

  7 and 8 are flowcharts according to the first embodiment.

  When forming an image, first, the power source of the image forming apparatus main body is turned on [S100], and the stirring drive motor 34 is driven [S101, S102]. At this time, the current value of the stirring drive motor 34 is monitored [S103].

  Here, if the current value is higher than a predetermined value (0.6 A in the present embodiment), it is determined that the stirring drive motor 34 is abnormal or the stirring member in the developing container is abnormal (for example, broken stirring or missing). [S104]. Then, an error message is displayed on the operation unit or the like of the image forming apparatus main body [S105], and the image forming operation is stopped [S106, S107] to the user (service call is urged).

  On the other hand, when the current value is lower than the predetermined value, that is, when the stirring drive motor current value is 0.6 A or less [S103], the remaining toner amount information is extracted from the CPU 30 disposed in the image forming apparatus main body. . Then, it is determined whether or not the toner End was in a state where there was no toner in the toner bottle or the developing container at the previous power-off [S108, S109].

  Here, if the toner is End, a message to replace the toner bottle is displayed on the operation unit or the like of the image forming apparatus main body, and the image forming operation is stopped [S110, S111].

  On the other hand, if it is not the toner End, the image forming operation is started [S112]. During the image forming operation, the toner amount in the developing container 2 is detected by the detection sensor 10 monitored by the CPU 30 [S113].

  If the detection sensor 10 determines that there is no toner, a toner-less counter is activated [S115, S116], and the number of times that no toner is continuously detected (count T) is stored in the CPU 30 [S116]. The count T returns to 0 when a “toner present” signal is received during the image forming operation.

In the present embodiment, the predetermined value of the number of continuous toner-free detections (count T) is set to
T0 = No toner detected number of times,
T1 = no-toner detection count continuously 9000 times (first predetermined number of times),
T2 = toner-free detection number of continuous times 18000 times (second predetermined number),
And At this time, T2 is the number of times of toner End.

  The toner-free count T depends on the toner filling amount in the developing container. When the weight in the developing container is large (about 500 g) as in this case, the number of detections (from T0 to T2) increases.

  At this time, it is determined whether the count T is larger or smaller than the predetermined value T1, the number of times is smaller than T1 [S117], and the stirring drive motor current value is 0.6 A or less [S118]. It is determined that the toner aggregation degree (developer aggregation degree) in the developing container is low [S119].

  That is, when the number of toner-free continuous detections is small (T1 or less), there is no vacant wall (gap) between the toner detection sensor and the wiper, or a vacant wall has just been formed. Therefore, the toner aggregation degree is low.

  The toner aggregation degree based on the no-toner count T and the stirring drive motor current value I is calculated by the CPU 30 referring to FIG. FIG. 9 is a cohesion degree table in the stirring drive motor current value and the toner-free count.

  The image forming operation is continued [S120], the hopper motor 33 is driven, and toner replenishment into the developing container 2 is started [S121].

  When the no-toner counter is equal to or less than T1, toner replenishment into the developing container 2 is continued until the detection sensor 10 detects the presence of toner. When the presence of toner is detected in this flow, the toner-free counter is cleared [S122]. That is, T = 0.

  However, when the stirring drive motor current value exceeds 0.6 A during the image forming operation [S118], an error message is displayed on the operation unit of the image forming apparatus main body at the same time as when the power is turned on. Display [S124]. Then, the image forming operation is stopped [S125] an announcement is made to the user (prompt for service call).

  FIGS. 10 and 11 show the flow up to this point in a graph. 10 and 11 are graphs showing the transition of the developer drive agitator motor current value according to the first embodiment, in which the number of no-toner counters and the agitator drive motor current value are plotted.

  The graph E1 in FIG. 10 shows a state where the current value is low when the toner runs out (T = 0), and the current value suddenly increases after the toner supply between T0 and T1. This is likely to occur when the toner supply control fails. The toner replenishment amount per unit time is remarkably increased, and the toner amount in the developing container is increased as the amount is abnormal. This is also a phenomenon that occurs because the detection sensor 10 in the developing container 2 cannot detect the presence of toner due to a failure, and the toner supply is not completed.

  Similarly, the graph of E3 in FIG. 10 shows that the current value is already high (0.3 A or more) at the stage when no toner is detected (T = 0), and the toner is replenished between T <T1. As with E1, the current value suddenly increases. E3 is a case that is observed when the stirring in the developing container 2 is abnormal because the current value is high in the state of T = 0.

  The states such as E1 and E3 are failures of the image forming apparatus main body as shown in the above-described flowchart, and it is difficult for the user to deal with them. In general, it is generally a service person.

  Further, the relationship between the toner-free count and the stirring drive motor current value obtained by the image forming apparatus having no failure is shown by a graph N2 in FIG.

  The stirring drive motor current value at T = 0 is low (0.3 A or less), and the current value increase is very slight even after the start of toner supply. The graph ends before T1 because the detection sensor 10 in the developing container 2 detects the presence of toner.

  Next, a flow when the tonerless continuous detection counter exceeds T1 and is smaller than T2 will be described with reference to FIG.

  First, when the toner-free counter is T1 <T <T2 [S126] and the stirring drive motor current value I is 0.6 or more, an error display [S124] is similarly performed. On the other hand, when the stirring drive motor current value I is 0.3 A or less, normal toner replenishment [S129] is performed.

  When the toner-free counter is T1 <T <T2 [S126] and the stirring drive motor current value I is 0.6A> I> 0.3A [S127, S128]. That is, even if the toner is replenished more than a certain level, if the detection sensor 10 does not detect the presence of toner and the agitation torque in the developing device is high, the degree of aggregation of the toner in the developing container 2 becomes extremely high [S130]. At this time, a state where an empty wall is generated between the wiper in the developing container 2 and the detection sensor 10 is shown.

  The developing container 2 in which the empty wall is generated is in a state in which the deterioration of the toner inside is promoted, and the detection sensor 10 detects the absence of toner despite the presence of the toner in the developing container 2 due to the influence of the empty wall. Resulting in. Therefore, when this flow is reached, the toner supply into the developing container 2 is stopped [S131].

  At this time, the toner weight in the developing device exceeds 500 g, and there is a margin of 150 g or more up to 350 g of the toner weight for detecting the absence of toner. When the printing rate per A4 sheet is 5%, it is possible to print 3k sheets or more on one side. That is, even if the toner absence is detected, the replenishment of the developer can be stopped and the image forming operation can be continued [S132]. Thereby, it is possible to eliminate the disadvantage of downtime for the user.

  Further, during the image forming operation while the toner supply is stopped [S132], the empty wall formed between the detection sensor 10 and the wiper 12 disappears due to the toner stirring of the stirring member 13 and the stirring member 14 in the developing container 2. . When the presence of toner is detected, it indicates that the toner state in the developing container 2 has returned to an appropriate state. In this embodiment, the number of A4 single-sided sheets is 3k from when the toner replenishment operation is stopped until the toner in the developing container 2 runs out. However, the number of sheets that can be passed varies depending on the image printing rate and the toner consumption of the product.

  Next, a flow when the tonerless continuous detection counter reaches T2 is shown.

  First, when the stirring drive motor current value I is 0.6 A or more, error display [S134] [S145] is performed in the same manner.

  During execution of the above-described mode, when the toner-less continuous detection counter is T2 [S133] and the agitation drive motor current value I is 0.6A> I> 0.3A [S135]. In this case, even if the above-described toner replenishment is stopped and the image forming operation is performed (even if the stirring member 13 and the stirring member 14 in the developing container 2 are rotated), the empty space generated between the wiper 12 and the detection sensor 10 is generated. Indicates that the wall could not be removed.

  In the image forming operation in which toner supply is stopped further, there is a risk of image whiteout. For this reason, the image forming operation is stopped here [S136]. Then, the mode shifts to a mode in which only the agitating member 13 and the agitating member 14 in the developing container 2 are idly rotated [S137], and the toner in the developing container 2 is smoothed (releasing the toner).

  The idling time by stirring is 1 minute in this embodiment. The idling time may be changed according to the degree of toner aggregation in the developing container 2. If the presence of toner [S138] is detected in this sequence, the image forming operation is resumed.

  However, when the detection sensor 10 cannot detect the presence of toner even by the sequence, if the stirring drive motor current value I is 0.3 A or more [S144], the toner aggregation degree is too high. Therefore, it is determined that the toner in the developing container 2 cannot be loosened only by idling with the stirring member 13 and the stirring member 14, and an error display is displayed [S145].

  If the current value after idling is lower than 0.3 A [S144], the toner aggregation in the developing container 2 is low, and the absence of toner is detected for a certain period [S133]. For this reason, it is determined that there is no normal toner [S144], and while the image forming operation is stopped, the toner supply operation into the developing container 2 is performed until the detection sensor 10 detects the presence of toner [S146].

  When the toner-free counter is T2 [S133] and the stirring drive motor current value I is I <0.3A [S140]. That is, the toner aggregation degree is low, and even if the replenishment is continued (when this <I, the toner is replenished between T0 and T2). . Then, the user is prompted to replace the toner bottle [S142], and the image forming operation is stopped [S143].

  FIG. 12 shows the flow up to this point in a graph. FIG. 12 is a graph showing a change in current value in the developing container stirring drive motor according to the first embodiment. FIG. 12 is a plot of the number of counters without continuous toner and the stirring drive motor current value.

  The graph of N1 in FIG. 12 shows the following behavior. First, the current value gradually increases after toner supply is performed between T0 and T1. Next, the image forming operation is performed in a state where the toner supply operation is stopped between T1 and T2. Then, the presence of toner is detected by stirring and loosening the toner in the developing container 2. During this period, the toner in the developing container 2 is consumed by continuing to form an image, the stirring torque is reduced, and the stirring drive motor current value is reduced.

  When the presence of toner is detected, the toner-free count T is cleared (disappears from the graph).

  The graph E4 in FIG. 12 shows the following behavior. First, the current value gradually increases after toner supply is performed between T0 and T1. Next, even when the image forming operation is performed in a state where the toner replenishment operation is stopped between T1 and T2, the toner in the developing container 2 cannot be loosened by stirring (because there was no decrease in current value). . Since the presence of toner could not be detected and the current value did not become 0.3 A or less, the mode shifts to the stirring idle rotation mode.

  The graph of N3 in FIG. 12 shows that the toner-free count is T2, the current value is 0.3 A or less, the stirring torque is small, and the toner-free state continues. That is, there is no toner in the toner bottle.

  Next, for comparison with the present invention, a conventional example will be described as a comparative example. FIG. 13 is a flowchart according to a comparative example.

  Even in the conventional zero, as shown in FIG. 13, the power source of the image forming apparatus main body is turned on [S201], and the stirring drive motor 34 is driven [S202].

Then, the remaining toner amount information is extracted from a CPU (not shown) arranged in the image forming apparatus main body. Then, it is determined whether or not the toner End (the state where there is no toner in the toner bottle or the developing container) at the last power-off. [S203, S204]
If it is toner end, a message to replace the toner bottle is displayed on the operation unit of the image forming apparatus main body and the image forming operation is stopped [S205, S206].

  If it is not the toner End, the image forming operation is started [S207]. During the image forming operation, the amount of toner in the developing container is detected by a detection sensor monitored by the CPU [S208].

  When the detection sensor determines that there is no toner, a toner-free counter is activated [S201, S211] and the CPU 30 stores the number of times that no toner has been detected [hereinafter T] [S211].

  At this time, it is determined whether or not the toner-free count is less than a predetermined value T3. If the count is less than T2 [S212], the image forming operation is continued [S207], and the hopper motor is driven to enter the developing container. Toner supply is started [S213].

  When the no-toner counter is equal to or less than T2, toner supply to the developing container is continued until the detection sensor detects the presence of toner. When the presence of toner is detected in this flow, the toner-free counter is cleared [S209]. That is, T = 0.

  When T = T2 [S214], it is determined that there is no toner in the hopper and in the toner bottle, and the image forming operation is stopped as toner End [S215, S218].

  As described above, even if the toner aggregation degree in the developing container is increased due to the durability state or the use environment variation and the stirring torque is increased, it cannot be detected by the conventional configuration. At this time, if an empty wall is generated between the detection sensor and the wiper and it is detected that there is no toner, the toner is replenished even though the developing container is sufficiently filled [S208]. ~ 213]. For this reason, the toner may be excessive and the main body may stop due to an error.

  FIG. 14 shows the flow up to this point in a graph. FIG. 14 is a graph showing changes in the developer drive agitator drive motor current value according to the comparative example. In FIG. 14, the number of counters without toner and the stirring drive motor current value are plotted.

  The graph E2 in FIG. 14 shows a state in which replenishment is continued after the toner runs out and the current value is 0.6 A or more and an error is stopped.

  As described above, in the conventional configuration, there is no means for detecting the degree of aggregation of the toner in the developing container, and the detection sensor in the developing container and the empty wall of the wiper cannot be recognized.

  On the other hand, in the present embodiment, an image forming apparatus free from failure can be provided by detecting the degree of aggregation in the developing container and optimizing replenishment control.

  In the above-described embodiment, the mode for controlling the image forming operation and the replenishing operation on the basis of a predetermined number of times or a predetermined value is executed. However, the present invention is not limited to this. For example, the CPU 30 may detect that there is no developer at a predetermined position, assuming that the detection result of the detection sensor 10 is greater than or equal to a predetermined ratio and that there is no developer.

A ... Image forming apparatus 1 ... Hopper 2 ... Developing container 10 ... Detection sensor 10a ... Detection unit 12 ... Wiper 13 ... Stirring member 14 ... Stirring member 30 ... CPU
37. Stirring torque detector

Claims (6)

An agitation member for agitating the developer in the developing container; an agitation torque detection unit for detecting the torque of the agitation member; a detection sensor for detecting the presence or absence of the developer at a predetermined position in the developer container; A control unit that controls a replenishment operation of the developer replenishment unit so that the developer is replenished to the predetermined position based on a detection result of the detection sensor with respect to a developing container having a cleaning member that cleans the detection unit; In an image forming apparatus having
The control unit detects that the developer is not present at the predetermined position based on the detection result of the detection sensor, and the developer container when the detection result of the stirring torque detection unit is within a predetermined range. An image forming apparatus, wherein a mode in which an image forming operation is continued in a state where developer supply to the inside is forcibly stopped is executable.   Based on the detection result of the detection sensor, the control unit detects that there is no developer at the predetermined position, and when the detection result of the stirring torque detection unit is below the predetermined range, The image forming apparatus according to claim 1, wherein the replenishment operation is controlled so as to continue the replenishment of the developer into the developing container.   The image forming apparatus according to claim 1, wherein the agitation torque detection unit is calculated from an agitation drive motor current value.   The control unit executes the mode when it is continuously detected that there is no developer at the predetermined position based on a detection result of the detection sensor for a first predetermined number of times. The image forming apparatus according to any one of claims 1 to 3.   The control unit performs an image forming operation when the absence of the developer at the predetermined position is continuously detected a second predetermined number of times based on the detection result of the detection sensor during the execution of the mode. The image forming apparatus according to claim 1, wherein a mode for stopping and driving the stirring member is executed.   6. The control unit according to claim 1, wherein the control unit detects that there is no developer at the predetermined position by detecting the absence of the developer when the detection result of the detection sensor is equal to or greater than a predetermined ratio. The image forming apparatus according to claim 1.

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