Image forming apparatus with a drive motor to drive a toner conveyance part and overcurrent prevention thereof

An image forming apparatus includes an image forming part, a toner storage part, a toner conveyance part, a drive motor and a control part. The image forming part forms an image on a sheet using a toner. The toner storage part stores the toner replenished to the image forming part. The toner conveyance part conveys the toner. The drive motor generates a drive force by which the toner conveyance part conveys the toner. The control part generates a control signal for controlling the drive motor, based on information showing a rotational speed of the drive motor. The control part executes a determination processing for determining whether a driving of the drive motor is stopped, based on the control signal.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese patent application No. 2020-053224 filed on Mar. 24, 2020, which is incorporated by reference in its entirety.

BACKGROUND

In an electrophotographic type image forming apparatus, a development process is performed by supplying a toner from a development device to an electrostatic latent image formed on a surface of a photosensitive drum. The toner is stored in a toner storage part (a toner container). In the toner storage part, a toner conveyance part having a rotating blade is disposed.

The toner conveyance part is driven by a drive motor. The toner is conveyed while being agitated by the toner conveyance part driven by the drive motor to be rotated. The toner conveyed while being rotated is replenished through an opening formed in the toner storage part to the development device.

By the way, the toner in the toner storage part may be aggregated during transportation to a user. When the toner is aggregated, the drive motor which agitates the toner is applied with an overload. Owing to the overload, an overcurrent may flow through the drive motor.

For example, an image forming apparatus may be configured to stop the drive motor in a case where a rotation of the drive motor is not detected within a predetermined time after a drive instruction signal is sent to the drive motor.

By the way, in the above described image forming apparatus, it takes time to determine that the drive motor and the rotational blade are not rotated. Then, there is s possibility that the overcurrent follows through the drive motor before the determination is made. Therefore, there is room for improvement in the processing for stopping the drive motor.

SUMMARY

In accordance with an aspect of the present disclosure, an image forming apparatus includes an image forming part, a toner storage part, a toner conveyance part, a drive motor and a control part. The image forming part forms an image on a sheet using a toner. The toner storage part stores the toner replenished to the image forming part. The toner conveyance part conveys the toner. The drive motor generates a drive force by which the toner conveyance part conveys the toner. The control part generates a control signal for controlling the drive motor, based on information showing a rotational speed of the drive motor. The control part executes a determination processing for determining whether a driving of the drive motor is stopped, based on the control signal.

The other features and advantages of the present disclosure will become more apparent from the following description. In the detailed description, reference is made to the accompanying drawings, and preferred embodiments of the present disclosure are shown by way of example in the accompanying drawings.

DETAILED DESCRIPTION

Hereinafter, with reference to the attached drawings, an embodiment in the present disclosure will be described. In the drawings, the same or corresponding portions are marked with the same reference numerals, and the description will not be repeated.

With reference toFIG. 1andFIG. 2, a configuration and an operation of an image forming apparatus100in the present embodiment will be described.FIG. 1is a view showing a configuration of the image forming apparatus100, andFIG. 2is a block diagram showing the configuration of the image forming apparatus100.

The image forming apparatus100is a copying machine or a multifunctional peripheral, for example. The image forming apparatus100shown inFIG. 1includes an apparatus main body1which forms an image on a sheet S and fixes the image on the sheet S, an image reading part2and an operation panel60.

The image reading part2is an image reading device (a scanning device), for example. The image reading part2is connected to the apparatus main body1. The operation panel60includes a display part61and an operation reception part62.

As shown inFIG. 1andFIG. 2, the apparatus main body1includes a sheet feeding part10, a sheet conveyance part11, an image forming part20, a fixing part30and a discharge part31as a configuration for image formation. Further, the apparatus main body1includes a toner replenishment part41, a toner storage part42, a toner conveyance part43, a drive motor70and a code reading part45as a configuration for replenishment of toner to the image forming part20. Further, the apparatus main body1includes a control part50and a memory part51.

The sheet feeding part10feeds the sheet S to the sheet conveyance part11. The sheet feeding part10includes a lift-up type sheet tray and a pickup rollers pair.

The sheet tray stores a plurality of the sheets S. The pickup rollers pair picks up the sheet S one by one from the sheet tray, and feeds it to the sheet conveyance part11.

The sheet conveyance part11includes a plurality of guide plates and a plurality of conveyance rollers pairs. The plurality of guide plates and the plurality of conveyance rollers pairs are disposed along a conveyance path for the sheet S.

The sheet conveyance part11conveys the sheet S fed from the sheet feeding part10to the discharge part31through the image forming part20and the fixing part30.

The image forming part20forms an image on the sheet S. In the present embodiment, the image forming part20forms the image on the sheet S in an electrophotographic manner. Specifically, the image forming part20includes a photosensitive drum21(an image carrier), a charging device, an exposure device, a development part22, a transferring device, a cleaning device and an erasing device.

The sheet conveyance part11conveys the sheet S on which the image is formed, to the fixing part30.

The fixing part30fixes the image on the sheet S. The fixing part30includes a pressure member and a heating member. The fixing part30heats and presses the sheet S to fix the image on the sheet S.

The sheet conveyance part11conveys the sheet S on which the image is fixed, to the discharge part31.

The discharge part31discharges the sheet S outside the apparatus main body1. The discharge part31includes a discharge rollers pair.

With reference toFIG. 1,FIG. 2andFIG. 3, the configuration for replenishment of the toner to the image forming part20will be described.FIG. 3is a view showing the configuration for replenishment of the toner from the toner replenishment part41to the image forming part20in the image forming apparatus100in the present embodiment.

As shown inFIG. 1, the image forming apparatus100in the present embodiment includes a unit40and a unit attachment part44. The unit40is attached to the unit attachment part44in an attachable and detachable manner. The unit40is a replacement member of the image forming apparatus100.

The unit40includes a unit case40a, the development part22which is one part of the image forming part20, and the toner replenishment part41. The unit case40astores the development part22and the toner replenishment part41. The unit case40ais a case made of resin, for example. To the unit attachment part44, the unit case40ais attached.

The toner replenishment part41replenishes the toner to the development part22. Specifically, the toner replenishment part41includes the toner storage part42and the toner conveyance part43.

The toner storage part42stores the toner. The toner conveyance part43includes a screw43a. When the screw43ais rotated, the toner is suppled from the toner storage part42to the development part22. Further, when the screw43ais rotated, the toner in the toner storage part42is agitated.

As shown inFIG. 3, the drive motor70generates a drive force for driving the toner conveyance part43. The drive force generated from the drive motor70is transmitted to one end of the screw43ato rotate the screw43a.

Specifically, the image forming apparatus100further includes a drive force transmission mechanism71. The drive force transmission mechanism71transmits the drive force generated from the drive motor70to the one end portion of the screw43a.

In detail, the drive force transmission mechanism71includes a plurality of gears, for example. The plurality of gears of the drive force transmission mechanism71contains a gear disposed at a tip end of a drive shaft of the drive motor70.

The unit40includes a drive coupling part40bcoupled to the one end portion of the screw43a. One of the plurality of gears of the drive force transmission mechanism71(hereinafter, refer to as “a coupling gear”) faces the drive coupling part40b.

The drive force transmission mechanism71includes a shaft71acoupled to the coupling gear. When the unit case40ais attached to the unit attachment part44, one end of the shaft71ais coupled to the drive coupling part40b. Then, a drive (a rotation) of the coupling gear is transmitted to the screw43a.

As shown inFIG. 3, an opening42ais formed in one end portion of the toner storage part42. Specifically, the opening42ais formed on the other end side of the screw43a. The screw43aincludes a rotating shaft (a shaft) and a spiral rotating blade (a conveyance blade or an agitating blade). The rotating blade is provided around an outer circumferential face of the shaft.

The shaft extends in the longitudinal direction of the toner storage part42. When the drive force of the drive motor70is transmitted to the one end portion of the screw43athrough the drive force transmission mechanism71, the screw43ais rotated by the drive force.

When the screw43ais rotated, the conveyance blade or the agitating blade of the screw43aconveys the toner in the toner storage part42in one direction (the left direction inFIG. 3).

Specifically, the screw43aconveys the toner to the other end side of the screw43a. Therefore, the toner is conveyed to the side of the opening42a. The toner conveyed to the opening42ais replenished to the development part22through the opening42a.

The code reading part45shown inFIG. 3is disposed in a position adjacent to the predetermined one face of the unit case40aattached to the unit attachment part44. The code reading part45reads identification information of the unit40.

The code reading part45magnetically reads the identification information, for example. The identification information is a serial number assigned to the unit40, for example. In a case where the code reading part45magnetically reads the identification information, an IC tag is disposed on the one face of the unit case40a, for example. The IC tag stores the identification information.

In this case, the code reading part45includes an RFID reader. The RFID reader is disposed so as to face the IC tag. The RFID reader reads the identification information from the IC tag when disposed so as to face the IC tag.

Therefore, when the unit case40ais attached to the unit attachment part44, the RFID reader of the code reading part45reads the identification information from the IC tag of the unit case40a.

The RFID reader sends a signal showing information read from the IC tag to the control part50. The code reading part45is an example of a detection part.

The code reading part45may optically read the identification information. In this case, a seal on which a two-dimensional bar code showing the identification information is printed is adhered on the one face of the unit case40a.

In a case where the two-dimensional bar code is used, the code reading part45includes an imaging device. The control part50causes the code reading part45to image the two-dimensional bar code when the unit case40ais attached to the unit attachment part44. When the two-dimensional car code is imaged, the code reading part45outputs a signal showing the imaged image to the control part50.

Alternatively, it may be a one-dimensional bar code in place of the two-dimensional bar code. In a case where the one-dimensional bar code is adhered on the unit case40a, the code reading part45includes a bar code reader.

As shown inFIG. 3, the drive motor70includes a motor main body70aand a rotation number detection part70b. The motor main body70ais a DC brush motor or a DC brushless motor, for example. The control part50includes a drive circuit for adjusting the rotation of the motor main body70a.

The rotation number detection part70bis an incremental encoder, for example. The rotation number detection part70bdetects a rotation number per unit time (rpm) or a rotational speed for the motor main body70a.

The rotation number detection part70boutputs a signal showing the detected rotation number per unit time (rpm) or rotational speed for the motor main body70a, to the control part50. The control part50executes a feedback control on the motor main body70abased on the signal showing the detected rotation number per unit time (rpm) or rotational speed for the motor main body70a.

As shown inFIG. 2, the image forming apparatus100includes the control part50and the memory part51. The operation panel60includes the display part61and the operation reception part62.

The control part50includes a processer such as a CPU (a Central Processing Unit). The control part50executes computer program stored in the memory part51to control each component of the image forming apparatus100.

The control part50controls the drive motor70based on the signal showing the detected rotation number per unit time (rpm) or rotational speed for the motor main body70a. Specifically, the control part50generates a control signal for controlling the motor main body70asuch that a rotational number of the drive motor70approaches a target value, based on the rotational number (rpm) of the drive motor70.

In detail, the control part50generates the control signal for controlling a current value of a current supplied to the motor main body70a.

The control part50executes a determination processing for determining whether the driving of the drive motor70and the driving of the screw43adriven by the drive motor70are stopped, based on the control signal.

Specifically, the control part50monitors a current value of a current supplied to the motor main body70a. Hereinafter, the current supplied to the motor main body70ais sometimes referred to as “a motor drive current”. The current value of the motor drive current is sometimes referred as “a motor drive current value”.

The control part50determines whether the motor drive current value is larger than a threshold value. The threshold value shows a value smaller than a current value at which the motor main body70ais in an overload state. The threshold value is stored in the memory part51.

Further, the control part50generates a control signal depending on the attachment of the unit case40ato the unit attachment part44, and drives the drive motor70.

In other words, the control part50rotates the screw43aof the toner conveyance part43depending on the attachment of the unit case40ato the unit attachment part44. Therefore, the control part50executes the determination processing depending on the attachment of the unit case40ato the unit attachment part44.

That is, the control part50determines whether the motor drive current value is equal to or larger than the threshold value, depending on the attachment of the unit case40ato the unit attachment part44.

Specifically, when the code reading part45reads the identification information of the unit40depending on the attachment of the unit case40ato the unit attachment part44, the control part50determines whether the unit40is replaced with a new unit40.

When it is determined that the unit40is replaced with the new unit40, the control part50generates the control signal, rotates the screw43aand executes the determination processing.

When the motor drive current value is equal to or larger than the threshold value before a predetermined time elapses after the rotating of the screw43ais started, the control part50stops the generation of the control signal and stops the driving of the drive motor70. In other words, the control part50stops the driving of the toner conveyance part43(the rotation of the screw43a) before the overcurrent flows through the motor.

As a result of the determination processing, when the driving of the toner conveyance part43is stopped, the control part50displays an error message on the display part61. The error massage notifies of a possibility that the toner in the toner storage part42is aggregated, for example. The display part61is an example of a notification part in the present disclosure.

The control part50stops the generation of the control signal and stops the drive motor70after the predetermined time elapses even when the motor drive current value is not equal to or larger than the predetermined value within the predetermined time.

In a case where the motor main body70ais a DC motor, the control part50may generate a control signal for controlling a voltage value of a voltage (hereinafter, referred to as “a motor drive voltage”) applied to the motor main body70aand monitor a voltage value of the motor drive voltage.

The memory part51includes a main storage device such as a ROM (a Read Only Memory) and a RAM (a Random Access Memory). The memory part51may include an auxiliary storage device such as HDD (a Hard Disk Drive). The memory part51stores various computer programs and various data.

The memory part51stores a target value of a rotation number (rpm) or a rotational speed of the drive motor70.

Further, the memory part51stores the identification information of the unit40read by the code reading part45.

When the code reading part45reads the identification information of the unit40depending on the attachment of the unit case40ato the unit attachment part44, the control part50determines whether the identification information matched the identification information read this time is stored in the memory part51.

When it is determined that the identification information matched the identification information read this time is stored in the memory part51, the control part50determines that the unit attached this time is not new.

On the other hand, when it is determined that the identification information matched the identification information read this time is not stored in the memory part51, the control part50determines that the unit40attached this time is new.

The display part61is a liquid crystal display device (LCD), for example. The display part61displays various screen.

In a case where the display part61is a touch display, a user operation is received by touching with a finger or the others.

The operation reception part62is a hard key, for example. The hard key receives various operation form the user.

Next, with reference toFIG. 4, the determination processing executed by the control part50when the unit40is replaced will be described.FIG. 4is a flowchart showing the determination processing executed at a time of replacing of the unit.

The processing shown inFIG. 4starts depending on the attachment of the unit case40ato the unit attachment part44.

As shown inFIG. 4, when the unit case40ais attached to the unit attachment part44, in step S1, the control part50determines whether the replaced unit40by the attachment and detachment is new.

In step S1, when it is determined that the replaced unit40is not new (S1: No), the control part50completes the processing (end).

On the other hand, in step S1, when it is determined that the replace unit40is new (S1: Yes), the processing proceeds to step S2.

In step S2, the control part50drives the toner replenishment part41. Specifically, the control part50rotates the screw43a. In detail, the control part50generates the control signal, starts to supply a current to the drive motor70and executes the feedback control on the drive motor70.

When the toner replenishment part41is started to be driven, in step S3, the control part50determines whether the motor drive current value W is larger than the threshold value X.

The motor drive current value W continues to increase by the feedback control if the toner in the toner storage part42is aggregated during transportation of the unit40.

Specifically, when the aggregation of the toner is not loosened even if the screw43ais rotated, the motor drive current value W continues to increase. As a result, an overcurrent flows through the drive motor70, and the drive motor70may be in an overload state.

As described above, the threshold value X is a value smaller than a current value at which the motor main body70ais in the overload state.

When it is determined that the motor drive current value W is larger than the threshold value X in step S3(S3: Yes), in step S6, the control part50stops the driving of the toner replenishment part41. Specifically, the control part50stops the driving of the drive motor70, and stops the driving of the screw43a.

When the driving of the screw43ais stopped, in step S7, the control part50displays the error message on the display part61, and the determination processing shown inFIG. 4is completed (end).

On the other hand, when it is determined that the motor drive current W is not larger than the threshold value X in step S3(is smaller, S3: No), in step S4, the control part50determines whether a period elapsed after the driving of the drive motor70is started (hereinafter, referred to as “a monitoring period”) exceeds a predetermined period T.

The predetermined period T is equal to or smaller than 3 minutes, for example. In the present embodiment, the predetermined period T is 60 seconds.

When the monitoring period does not exceed the predetermined period T (S4: No), the control part50returns the processing to step S3. In other words, the control part50repeats the processing for determining whether the motor drive current value W is larger than the threshold value X until the monitoring period exceeds the predetermined period T.

When the monitoring period exceeds the predetermined period T in step4(S4: Yes), in other words, when the toner loosening period elapses, the control part50stops the driving of the drive motor70, stops the driving of the toner replenishment part41in step S5, and completes the processing shown inFIG. 4(end).

According to the embodiment described above, in the image forming apparatus100, when the unit40is replaced, even if the toner aggregation occurs in the toner storage part42, it becomes possible to suppress the flowing of an overcurrent through the drive motor70driving the screw43a. Since the toner tends to aggregate during transportation and storage, the control part50executes the determination processing depending on the attachment of the toner storage part42to the unit attachment part44, so that the determination processing can be executed efficiently. Further, even when a degree of the toner aggregation is high, such as during transportation or storage, since the determination processing is executed for a predetermined period of time after the toner storing part42is attached to the unit attachment part44, it becomes possible to suppress the flowing of the overcurrent through the drive motor70surely. Furthermore, since the error message is displayed on the display part61after the drive motor70is stopped, maintenance can be performed quickly.

The embodiments of the present disclosure have been described with reference to the drawings. However, the present disclosure is not limited to the above embodiments, and may be performed in various embodiments without departing from the gist thereof. For example, some components may be removed from all components shown in the embodiments. The drawings schematically show the respective components mainly for convenience of easy understanding, and the thickness, length, number, interval, and the like of each component shown are different from the actual ones for convenience of drawing preparation. The material, shape, dimension, and the like of the component shown in the above embodiments are only examples, and are not particularly limited, and various changes can be made without substantially departing from the structure of the present disclosure.

For example, in the embodiment described with reference toFIG. 1toFIG. 4, the determination processing executed when the toner is loosened immediately after the unit40(a toner container) is replaced is described, but the determination processing of the present disclosure may be executed on other occasions when aggregation of the toner is concerned. For example, when the image forming apparatus100is not used for a long period of time or when vibration is applied to the apparatus main body1by displacing the installation place of the image forming apparatus100, the determination processing of the embodiment may be performed.

The present disclosure is applicable to the field of an image forming apparatus.