JP2024078125A - Image forming device - Google Patents

Abstract

[Problem] To achieve both sufficient stirring of developer and prevention of adhesion of developer. [Solution] When the remaining amount of toner is near the end, the printer 1 stops the stirrer 50 within the separation range AF based on the detection signal obtained from the toner sensor 36. This allows the printer 1 to keep the stirrer 50 away from the outer surface of the toner cartridge 13, and effectively prevents toner from adhering to the outer surface. As a result, when the toner cartridge 13 is removed by the user from the ID unit 14, the printer 1 effectively prevents toner from peeling off from the outer surface and soiling the inside and surroundings of the printer housing 2. [Selected Figure] Figure 13

Description

The present invention relates to an image forming apparatus, and is suitable for use in, for example, electrophotographic image forming apparatuses (so-called printers).

Conventionally, printers that print images by generating a toner image using toner (also called a developer) in an image forming section that performs exposure processing, etc., and then transferring and fixing the toner image onto paper, have been widely used.

As an example of this image forming unit, a toner cartridge that is detachable from an image drum unit having an image drum and contains powder toner, which is a consumable item, is known, and the toner is replenished from the toner cartridge to a toner storage section in the image drum unit. Another proposed image forming unit is one that is provided with a stirring member that stirs the toner in the toner storage section, thereby ensuring a stable supply of toner and preventing the toner from coagulating in the toner storage section (see, for example, Patent Document 1).

JP 2021-196534 A (FIG. 2, etc.)

However, in a printer with this configuration, the agitating member agitates the toner even in the area immediately adjacent to the toner cartridge inside the toner storage unit, which can cause the toner to adhere to the outer surface of the toner storage unit. In this case, when the toner cartridge is removed for replacement, the toner that has been adhering to the outer surface of the toner cartridge can peel off and fall, causing damage to the surrounding area.

The present invention was made in consideration of the above points, and aims to propose an image forming device that can achieve both sufficient stirring of the developer and suppression of adhesion of the developer.

In order to solve this problem, the image forming apparatus of the present invention is provided with a developing unit that develops an electrostatic latent image formed on a developer carrier with a developer, a developer storage unit that is provided in the developing unit and stores developer for developing the electrostatic latent image, a developer container that is detachable from the developing unit, stores developer, and supplies the developer from a supply port to the developer storage unit, a stirrer that is provided in the developing unit and can be displaced to multiple positions within the developer storage unit, including a supply port proximity range that is close to the supply port in the developer container and a supply port separation range that is distant from the supply port, and stirs the developer in the developer storage unit, a position detection unit that detects the position of the stirrer in the developer storage unit or a position linked to the stirrer, a drive unit that supplies a drive force to the stirrer, and a control unit that controls the drive unit to stop the stirrer that has passed the position detection unit in the supply port separation range based on the detection result by the position detection unit.

The present invention stops the agitator of the image forming unit in the range away from the supply port, so that the agitator can be sufficiently separated from the developer container, and the agitator can prevent developer from adhering to the vicinity of the supply port on the outer surface of the developer container. As a result, the present invention can effectively prevent developer from peeling off from the outer surface of the developer container and soiling the surroundings when the developer container is removed from the image forming device and replaced.

The present invention makes it possible to realize an image forming device that can achieve both sufficient stirring of the developer and suppression of adhesion of the developer.

FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus. FIG. 2 is a schematic diagram illustrating a circuit configuration of the image forming apparatus. FIG. 2 is a schematic diagram illustrating a configuration of an image forming unit. FIG. 2 is a schematic perspective view showing a configuration of a stirring unit. 4 is a schematic diagram showing a displacement caused by rotation of a stirring body. FIG. 5 is a schematic diagram showing transmission of a driving force to a stirrer by a drive transmission body. FIG. 6 is a timing chart showing the state of each part when the remaining amount of toner is relatively large. 11 is a schematic diagram illustrating a state of the stirring unit when the remaining amount of toner is relatively large. 6 is a timing chart showing the state of each part when the remaining amount of toner is relatively small. 11 is a schematic diagram illustrating a state of the stirring unit when the remaining amount of toner is relatively small. 11 is a schematic diagram showing a separation range and a proximity range in a stirring unit. FIG. 13 is a flowchart showing a printing process procedure. 13 is a flowchart showing a separation range stop processing procedure according to the first embodiment. 13 is a flowchart showing a separation range stop process procedure according to the second embodiment.

Below, the form for implementing the invention (hereinafter referred to as embodiment) will be explained with reference to the drawings.

1. First embodiment
[1-1. Printer configuration]
1, the printer 1 according to the first embodiment is an electrophotographic image forming apparatus that can form, i.e., print, a monochrome image on paper P. Incidentally, the printer 1 does not have an image scanner function for reading an original document or a communication function using a telephone line, and is a single-function SFP (Single Function Printer) that has only a printer function.

The printer 1, which serves as an image forming device, has various parts arranged inside the printer housing 2, which is formed in a roughly box shape. In the following description, the right-hand end portion in FIG. 1 is regarded as the front of the printer 1, and the up-down, left-right, and front-rear directions are defined when viewed from the front. In addition, the portion of the printer housing 2 that mainly constitutes the top surface is configured to be openable and closable relative to the remaining portion.

The printer 1 is controlled as a whole by the printer control unit 3. This printer control unit 3 has a CPU (Central Processing Unit) and a memory unit (neither shown), and performs various processes by executing various programs. The printer control unit 3 also has a timer circuit (not shown), and can obtain the current time and the elapsed time from a specified start time, etc.

The printer control unit 3 is further connected wirelessly or by wire to a host device (not shown) such as a computer device. When the printer control unit 3 is provided with image data representing the image to be printed from this host device and is instructed to print the image data, it executes a print process to form a print image on the surface of the paper P. A display unit 4 is provided on the front side of the top surface of the printer housing 2. The display unit 4 is, for example, a liquid crystal panel, and displays various information based on the control of the printer control unit 3.

At the bottom of the printer housing 2, a paper cassette 5 is provided to store stacked paper P. A paper feed section 6 is provided above and in front of the paper cassette 5. The paper feed section 6 is made up of a paper feed roller 7 arranged above and in front of the paper cassette 5, a transport guide 8 that guides the paper P upward along the transport path W, and registration rollers 9 and 10 arranged in contact with the transport path W. Of these, the paper feed roller 7 and the registration rollers 9 and 10 are rotated by the supply of driving force from a paper feed motor 31 shown in FIG. 2 under the control of the printer control section 3.

The paper feed unit 6 (Fig. 1) picks up the paper P stored in the paper cassette 5 one sheet at a time by appropriately rotating the paper feed roller 7 etc. based on the control of the printer control unit 3. The paper feed unit 6 then advances the paper P forward and upward along the transport path W by the transport guide 8, and eventually turns back backward to abut against the registration roller 10. The registration roller 10 is appropriately restricted in rotation, and applies frictional force to the paper P to correct the side edge of the paper P being inclined relative to the direction of travel (so-called skew), and sends the paper P backward after aligning the leading and trailing edges to the left and right.

A transport path W is formed behind the registration rollers 10, running roughly in the front-to-rear direction, and an intermediate transport section 11 is disposed below the transport path W. The intermediate transport section 11 has a drive roller, a transport belt, a transport guide, and the like (not shown), and by running the transport belt, the paper P is advanced roughly in the rear direction along the transport path W.

An image forming unit 12 is provided above the intermediate conveying unit 11. This image forming unit 12 is roughly divided into a toner cartridge 13, an ID (image drum) unit 14, and an LED (Light Emitting Diode) head 15, etc.

The toner cartridge 13, which serves as a developer container, is detachably attached to the ID unit 14 and contains toner as a developer. The toner cartridge 13 has a toner supply port (described in detail below) formed at the connection point with the ID unit 14, and supplies toner to the ID unit 14 through the toner supply port.

The ID unit 14, which serves as a developing section, is detachably attached to the printer housing 2 and includes a cylindrical photoconductor drum 17 and various rollers. The ID unit 14 creates an electrostatic latent image on the peripheral surface of the photoconductor drum 17 based on image data supplied from a higher-level device, and develops the image using toner supplied from the toner cartridge 13 to create a toner image on the peripheral surface of the photoconductor drum 17 (described in more detail below).

The transfer roller 16 is formed in a cylindrical shape with its central axis aligned in the left-right direction, and is arranged to sandwich the transport path W between itself and the photosensitive drum 17 of the ID unit 14. When paper P is transported along the transport path W, the transfer roller 16 transfers the toner image from the peripheral side surface of the photosensitive drum 17 onto the paper P.

The fixing unit 20 is provided near the rear end of the intermediate transport unit 11. The fixing unit 20 has a heating roller 21 and a pressure roller 22 arranged to face each other across the transport path W. The heating roller 21 is formed in a cylindrical shape with its central axis facing left and right, and has a heater inside. The pressure roller 22 is formed in the same cylindrical shape as the heating roller 21, and presses its upper surface against the lower surface of the heating roller 21 with a predetermined pressure force. The fixing unit 20 is also provided with a temperature sensor (not shown) that detects temperature.

When the fixing unit 20 receives driving force from the fixing motor 32 under the control of the fixing control unit 33 shown in FIG. 2, it heats the heating roller 21 and rotates the heating roller 21 and the pressure roller 22 in a predetermined direction. In this way, the fixing unit 20 applies heat and pressure to the paper P received from the intermediate conveying unit 11, i.e., the paper P on which the toner image has been transferred, to fix the toner, and then passes it on to the rear.

The paper discharge section 25 is disposed behind the fixing section 20. Like the paper feed section 6, the paper discharge section 25 is composed of a combination of a guide 26 that guides the paper P, a transport roller 27, a paper discharge roller 28, etc. This paper discharge section 25 appropriately rotates the transport roller 27, the paper discharge roller 28, etc., to transport the paper P delivered from the fixing section 20 upward and rearward along the guide 26, then turns it around toward the front and discharges it onto a discharge tray 29 formed on the top surface of the printer housing 2.

Next, the circuit configuration of the printer 1 will be described with reference to FIG. 2. The printer control unit 3 is the part that controls the printer 1 overall, and has a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a storage unit (not shown). The printer control unit 3 performs various processes by using the RAM as a work area and executing various programs read from the ROM, storage unit, etc. by the CPU. The storage unit is a non-volatile storage medium such as an SSD (Solid State Drive) or HDD (Hard Disk Drive), and stores various programs, various information, etc.

In addition to the display unit 4 and LED head 15 described above, the printer control unit 3 is connected to a paper feed motor 31, a fixing motor 32, a fixing control unit 33, an ID motor 34, a high-voltage circuit 35, a toner sensor 36, etc.

The paper feed motor 31 generates driving force and supplies it to the paper feed rollers 7 of the paper feed unit 6 under the control of the printer control unit 3. The LED head 15 is provided with multiple LED elements, and emits light toward the peripheral side of the photosensitive drum 17 (Figure 1) under the control of the printer control unit 3 (details will be described later).

The fixing motor 32 generates driving force and supplies it to the heating roller 21 of the fixing unit 20 and the conveying roller 27 of the paper discharge unit 25 under the control of the fixing control unit 33. The fixing control unit 33 controls the amount of current supplied to the heater in the heating roller 21 of the fixing unit 20, the rotation of the fixing motor 32, etc.

The ID motor 34, which serves as a drive unit, generates a drive force based on the control of the printer control unit 3 and supplies it to the photosensitive drum 17 and each roller in the ID unit 14. Based on the control of the printer control unit 3, the high-voltage circuit 35 generates a high voltage to be supplied to each roller of the ID unit 14 and the transfer roller 16. The toner sensor 36 is installed near the ID unit 14 and supplies a signal regarding the remaining amount of toner contained in the ID unit 14 (described in detail below).

When printing an image on paper P of normal thickness, the printer 1 increases the number of prints per unit time as much as possible by setting the transport speed of the paper P in the transport path W to a relatively high speed. On the other hand, when printing an image on paper P of a relatively large thickness, the printer 1 sets the transport speed of the paper P in the transport path W to a low speed in order to prevent a decrease in the fixing performance of the fixing unit 20.

For example, when the thickness of the paper P is set to a relatively large value by the user's operation, the printer control unit 3 controls the transport speed of the paper P in the transport path W during printing to be slow, and accordingly controls the paper feed motor 31, the fixing motor 32, and the ID motor 34 to each be driven at a slow speed.

[1-2. Configuration of image forming unit]
Next, the configuration of the image forming unit 12 will be described with reference to a schematic side view of Fig. 3. As described above, the image forming unit 12 includes the toner cartridge 13, the ID unit 14, the LED head 15, the transfer roller 16, etc.

The toner cartridge 13, which serves as a developer container, has an outer shell formed by the toner cartridge housing 13A, and is formed as a rectangular parallelepiped that is long in the left-right direction as a whole. The bottom of the toner cartridge housing 13A is formed as a curved surface that is curved in an arc shape when viewed from the left-right direction.

A storage space 13B, which is a sufficiently large space, is formed inside the toner cartridge housing 13A, and toner is stored in this storage space 13B. A toner cartridge supply port 13C is formed at the bottom of the toner cartridge housing 13A, which connects the storage space 13B to the external space. This toner cartridge supply port 13C can be opened and closed by a shutter 13D formed in a thin plate shape. The shutter 13D is linked to a lever (not shown), and opens or closes the toner cartridge supply port 13C based on the user's operation of the lever.

As a result, when the toner cartridge 13 is attached to the ID unit 14 and the shutter 13D is opened, the toner contained in the storage space 13B can fall downward through the toner cartridge supply port 13C.

The outer shell of the ID unit 14 is formed by the ID unit housing 40. A toner cartridge mounting section 41 for mounting the toner cartridge 13 is formed in the upper part of the ID unit housing 40. An ID unit supply hole 42 is formed in a portion corresponding to the toner cartridge supply port 13C at the bottom of the toner cartridge mounting section 41. Below the ID unit supply hole 42, a toner storage space 43 is formed, and an agitator 44, a detection window 45, a supply roller 46, a developing roller 47, a developing blade 48, a photoconductor drum 17, a charging roller 49, etc. are appropriately arranged.

The toner storage space 43 is connected to the upper space, i.e., the space inside the toner cartridge mounting section 41, via the ID unit supply hole 42. Therefore, the toner that falls from the toner cartridge 13 through the ID unit supply hole 42 is stored in the toner storage space 43.

Toner is a powder whose specific gravity is greater than that of air, so it accumulates toward the bottom within the toner storage space 43. As a result, in the toner storage space 43, the higher the position of the toner surface TS, which is the surface of the stored toner, the more toner remains, and the lower the position of the toner surface TS, the less toner remains. In addition, a supply roller 46 (described in detail below) is provided below the toner storage space 43, and when the toner is supplied to the development roller 47 by the supply roller 46, the amount of remaining toner decreases.

The agitator 44 is disposed within the toner storage space 43 and agitates the toner stored within the toner storage space 43 (details will be described later). The detection window 45 is located to the left of the agitator 44 on the left side surface of the ID unit housing 40 and allows light to pass through.

The supply roller 46 is disposed below the agitator 44 in the toner storage space 43. The developing roller 47 is disposed diagonally above and behind the supply roller 46, in a position that abuts the supply roller 46 and the photosensitive drum 17, respectively. The supply roller 46 and the developing roller 47 are both formed in a cylindrical shape with their central axes aligned in the left-right direction, and are supported so as to be rotatable about their respective central axes. The developing blade 48 is formed in a thin plate shape, and one end abuts against the peripheral side surface of the developing roller 47 under the action of an elastic force.

The photoconductor drum 17, which serves as a developer carrier, is formed in a cylindrical shape with its central axis aligned in the left-right direction, and is supported so as to be rotatable around the central axis. A thin-film charge generating layer and a charge transport layer are successively formed on the peripheral side of the photoconductor drum 17, so that the photoconductor drum 17 can be charged. The charging roller 49 is formed in a cylindrical shape with its central axis aligned in the left-right direction, is supported so as to be rotatable, and is provided so as to abut against the upper rear side of the photoconductor drum 17.

The LED head 15, also called the exposure head or exposure section, is formed in a long, thin rod shape that runs along the left-right direction and is located above the photosensitive drum 17. This LED head 15 has multiple LED elements, lenses, etc. arranged roughly along the left-right direction. When the LED elements of the LED head 15 are appropriately illuminated under the control of the printer control section 3 (Figure 2), the light is irradiated downward while converging, and the light is focused near the upper end of the peripheral side surface of the photosensitive drum 17.

In this configuration, when the image forming unit 12 performs printing processing, a driving force is supplied from the ID motor 34 (Figure 2) based on the control of the printer control unit 3. As a result, the image forming unit 12 rotates the developing roller 47, the charging roller 49, and the transfer roller 16 of the ID unit 14 in the direction of the arrow R2, and rotates the photosensitive drum 17 and the supply roller 46 in the direction of the arrow R1.

In addition, under the control of the printer control unit 3 (Fig. 2), the image forming unit 12 applies a predetermined bias voltage from the high voltage circuit 35 (Fig. 2) to the supply roller 46, the development roller 47, the charging roller 49, and the transfer roller 16, thereby charging them. The supply roller 46 adheres the toner in the toner storage space 43 to its peripheral side by charging, and the toner adheres to the peripheral side of the development roller 47 by rotating. After excess toner is removed from the peripheral side of the development roller 47 by the development blade 48, the peripheral side of the development roller 47 is brought into contact with the peripheral side of the photosensitive drum 17.

Meanwhile, the charging roller 49 contacts the photoconductor drum 17 in a charged state, uniformly charging the peripheral surface of the photoconductor drum 17. The LED head 15 emits light in a light emission pattern based on image data supplied from the printer control unit 3 (Figure 2), exposing the photoconductor drum 17. As a result, an electrostatic latent image is formed on the peripheral surface of the photoconductor drum 17 near its upper end.

The photoconductor drum 17 then rotates in the direction of arrow R1, bringing the area where the electrostatic latent image is formed into contact with the developing roller 47. This causes toner to adhere to the peripheral surface of the photoconductor drum 17 based on the electrostatic latent image, and a toner image based on image data is developed. The developed toner image reaches the nip between the photoconductor drum 17 and the transfer roller 16, i.e., the transport path W, as the photoconductor drum 17 rotates. At this time, if paper P is being transported along the transport path W, the image forming unit 12 transfers the toner image from the peripheral surface of the photoconductor drum 17 to the paper P. In this way, the image forming unit 12 (Figure 1) can form a toner image based on the print data and transfer the toner image to paper P being transported from the front along the transport path W.

[1-3. Configuration of the stirring section]
Next, a detailed configuration of the stirring unit 44 will be described. As shown in the schematic exploded perspective view of Fig. 4, the stirring unit 44 is broadly composed of a stirring body 50 and a drive transmission body 60. The stirring body 50 is further broadly composed of a bent columnar body 51, a detection plate 52, and an engagement protrusion 53.

The bent column 51 is formed by bending a thin, elongated cylindrical member along the left-right direction at multiple points, each at approximately 90 degrees, to form a crank shape as a whole. Specifically, the bent column 51 is provided, from left to right, with a central portion 51A, a radius portion 51B, an outer portion 51C, a radius portion 51D, and a central portion 51E, in that order. Of these, the central portions 51A and 51E and the outer portion 51C are all straight cylinders along the left-right direction. On the other hand, the radius portions 51B and 51D are all straight cylinders along the up-down direction, and are suspended downward from the central portions 51A and 51C (hereinafter also referred to as the radial direction).

The detection plate 52, which serves as the object to be detected, is formed as a thin plate that is long in the vertical direction and short in the horizontal direction overall. The detection plate 52 also has a round hole 52H drilled through it in the horizontal direction near its upper end. The left end portion of the center portion 51A of the bent column 51 is inserted into this round hole 52H and fixed in place. Furthermore, the longitudinal direction of the detection plate 52 is aligned approximately parallel to the radius portions 51B and 51D, and the length along the longitudinal direction is approximately equal to the longitudinal length of the radius portions 51B and 51D.

A reflective member 55 is provided on the left side surface at the lower end of the detection plate 52. The reflective member 55 has the property of reflecting light with a high reflectance. The reflective member 55 is located just to the left of the outer casing 51C of the bent columnar body 51. Therefore, in FIG. 5(A), which is a schematic diagram showing the agitator 50 as viewed from the left, the reflective member 55 and the outer casing 51C are shown overlapping. The engagement protrusion 53 is formed in a tiny rectangular parallelepiped shape and is provided on the lower side surface near the center in the left-right direction at the center portion 51A of the bent columnar body 51 so as to protrude downward.

The agitator 50 is supported so that the central portions 51A and 51E of the bent columnar body 51 can rotate. Therefore, as shown in Figures 5(A) and (B), the agitator 50 can rotate around a virtual agitation central axis X44 that passes through the centers of the central portions 51A and 51E, with the outer shell 51C revolving around the agitation central axis X44.

For ease of explanation, in the following, point 50Q, which corresponds to the center of outer shell 51C, is regarded as an index for indicating the direction and position of agitator 50, and the relative position and direction of point 50Q with respect to agitator central axis X44 is regarded as the position and direction of agitator 50.

For example, Figure 5(A) shows a state in which point 50Q is located almost directly below the central axis X44 of the agitation, with the agitator 50 facing downward. Hereinafter, the position of point 50Q at this time will be referred to as bottom dead center, and the position of the agitator 50 at this time will also be referred to as the detection position. Figure 5(B) shows a state in which point 50Q is located almost directly above the central axis X44 of the agitation, with the agitator 50 facing upward. Hereinafter, the position of point Q50 at this time will be referred to as top dead center.

In addition, in the ID unit 14 (Fig. 3), the positioning of each part is adjusted so that when the agitator 50 is at or very close to the bottom dead center (Figs. 4 and 5(A)), the detection window 45 (Fig. 3) is located to the left of the reflecting member 55.

On the other hand, toner sensor 36 (Fig. 2) is disposed on the left side of detection window 45 in printer housing 2 (Fig. 1). This toner sensor 36 has a light-emitting element that emits a predetermined detection light toward the right side (i.e., the detection window 45 side), and a light-receiving element that receives the detection light traveling from the right side. Based on the control of printer control unit 3, toner sensor 36 causes the light-emitting element to emit detection light, and generates a toner detection signal based on the amount of detection light received by the light-receiving element.

When the ID unit 14 is attached to the printer housing 2 and the reflecting member 55 is located to the right of the detection window 45, the detection light emitted from the light-emitting element of the toner sensor 36 passes through the detection window 45, is reflected by the reflecting member 55, passes through the detection window 45 again, and is received by the light-receiving element. At this time, the toner sensor 36 generates a light-receiving signal that indicates the amount of light received by the light-receiving element and supplies this to the printer control unit 3 (Figure 2).

If the signal level of the acquired light receiving signal exceeds a predetermined detection threshold, the printer control unit 3 judges it as "detected", meaning that the agitator 50 has been detected, and if it falls below the detection threshold, it judges it as "not detected", meaning that the agitator 50 has not been detected. In practice, the printer 1 judges it as "detected" when the agitator 50 is located at a detection position facing downward (i.e., at the bottom dead center) depending on the relationship between the size of the detection window 45 and the reflecting member 55, the distance from the agitation central axis X44, and the detection threshold, etc. Hereinafter, this type of judgment process will be referred to as the detection judgment process.

That is, the printer control unit 3 can use the detection and judgment process to determine whether the reflective member 55, which is part of the agitator 50 and is linked to the bent column 51, is located within the detection range, i.e., whether the agitator 50 is in the detection position, as "detected" or "not detected," based on the light receiving signal obtained from the toner sensor 36. The printer control unit 3 then determines the remaining amount of toner in the ID unit 14 (hereinafter referred to as the "toner remaining amount") based on the length and percentage of the period during which it was determined to be "detected" (more details will be described later).

The drive transmission body 60 (Figure 4) is formed into a cylindrical shape overall, and has a cylindrical portion 61 and a transmission protrusion 62. The cylindrical portion 61 is formed into a cylindrical shape centered on the central stirring axis X44. The transmission protrusion 62 is formed into a tiny rectangular parallelepiped shape, and stands upright from the inner surface of the cylindrical portion 61 toward the central stirring axis X44.

As shown in the schematic cross-sectional view of FIG. 6(A), the drive transmission body 60 is inserted into the center portion 51A of the agitator 50. When a driving force is transmitted from the ID motor 34 (FIG. 2) via a gear or the like (not shown), the drive transmission body 60 rotates in the direction of arrow R2 (counterclockwise in the figure).

With this configuration, as shown in FIG. 6A, when the transmission protrusion 62 of the drive transmission body 60 is separated from the engagement protrusion 53 of the agitator 50, the driving force of the ID motor 34 (FIG. 2) is not transmitted to the agitator 50. Therefore, the operation and position of the agitator 50 are determined according to gravity acting on the outer casing 51C, contact between the toner contained in the toner storage space 43 and the outer casing 51C, etc.

On the other hand, FIG. 6(B), which corresponds to FIG. 6(A), shows the state in which the transmission protrusion 62 of the drive transmission body 60 is in contact with the engagement protrusion 53 of the agitator 50 in the agitator 44. In the state shown in FIG. 6(B), the driving force of the ID motor 34 (FIG. 2) is transmitted to the agitator 50 in the agitator 44, and the drive transmission body 60 and the agitator 50 rotate together.

For ease of explanation, in the following, point 60Q, which is the lowest point of the drive transmission body 60 in the state shown in FIG. 6(B), is regarded as an index for indicating the direction and position of the drive transmission body 60, and the relative position and direction of point 60Q with respect to the agitation central axis X44 is the position and direction of the drive transmission body 60. For example, FIG. 6(B) shows a state in which the drive transmission body 60 faces downward. Also, FIG. 6(A) shows a state in which the drive transmission body 60 faces diagonally downward and rearward. Furthermore, in the following, with regard to the position of point 60Q relative to the agitation central axis X44, as in the case of point 50Q, the position almost directly below the agitation central axis X44 is called the bottom dead center, and the position almost directly above the agitation central axis X44 is called the top dead center.

In this way, the agitator 44 rotates the agitator 50 within the toner storage space 43, and transmits the driving force of the ID motor 34 (Figure 2) from the drive transmission body 60 to the agitator 50, thereby agitating the toner within the toner storage space 43.

[1-4. Toner detection and determination of remaining toner amount]
Next, a process will be described in which the printer control unit 3 (FIG. 2) performs a test determination process based on the detection signal obtained from the toner sensor 36, and determines the amount of toner remaining in the ID unit 14 based on the obtained detection result. In addition, the following describes the cases where the remaining amount of toner stored in the toner storage space 43 is relatively large and relatively small.

In either case, the initial state is that the agitator 50 of the agitator 44 is positioned at the bottom dead center, and the drive transmission body 60 is rotated at a constant speed by the driving force supplied from the ID motor 34.

[1-4-1. When the toner remaining amount is relatively large]
First, a case will be described where the remaining amount of toner contained in the toner containing space 43 in the ID unit 14 is relatively large. Fig. 7 is a schematic timing chart showing (A) the rotation or stop of the ID motor 34, (B) the position of the drive transmission body 60, (C) the position of the agitator 50, and (D) the detection and determination result by the printer control unit 3 based on the light receiving signal obtained from the toner sensor 36.

Figures 8 (A) to (F) also show schematic diagrams of the relationship between the positions of the agitator 50 and drive transmission body 60, the position of the detection window 45, and the toner surface TS, which represents the surface of the toner stored in the toner storage space 43, at each point in time in Figure 7. In Figure 8, of the circular arc-shaped arrows based on the agitation central axis X44, the arrow on the inner circumference represents the magnitude of the rotational speed of the drive transmission body 60, and the arrow on the outer circumference represents the magnitude of the rotational speed of the agitator 50.

At the first time T0, the agitator 44 is in the state shown in FIG. 8(A). That is, the drive transmission body 60 continues to rotate at a constant speed and is located at the bottom dead center. The agitator 50 is located at the bottom dead center, and the engagement protrusion 53 abuts the transmission protrusion 62, allowing the drive force to be transmitted. In addition, a portion of the reflecting member 55 is located to the right of the detection window 45, and the agitator 50 is in the detection position, so the detection judgment result is "detected."

At time T1, the agitator 44 is in the state shown in FIG. 8(B). That is, the drive transmission body 60 and the agitator 50 rotate as a unit at a constant speed, and both are located slightly away from the bottom dead center. In addition, most of the reflecting member 55 is removed from the right side of the detection window 45, so the detection result switches to "not detected."

At time T2, the agitator 44 is in the state shown in FIG. 8(C). That is, the drive transmission body 60 and the agitator 50 continue to rotate as a unit at a constant speed, and both are located at the top dead center. Also, since the reflecting member 55 is completely removed from the right side of the detection window 45, the detection result continues to be "not detected."

After time T2, the agitator 50 rotates at a faster rotational speed than the drive transmission body 60, causing the outer shell 51C to fall due to gravity acting mainly on the outer shell 51C, and as a result, the engagement protrusion 53 separates from the transmission protrusion 62 of the drive transmission body 60. Thereafter, as shown in FIG. 8(D), when the outer shell 51C comes into contact with the toner surface TS, the toner impedes the agitator 50's progress and generates resistance, so the agitator 50 comes to rest with part of the outer shell 51C buried in the toner.

At time T3, the agitator 44 is in the state shown in FIG. 8(D). That is, the drive transmission body 60 continues to rotate at a constant speed, but is significantly behind the agitator 50. The agitator 50 is stationary and slightly embedded in the toner surface TS. In addition, the reflective member 55 remains completely removed from the right side of the detection window 45, so the detection result remains "not detected."

At time T4, the agitator 44 is in the state shown in FIG. 8 (E). That is, the drive transmission body 60 continues to rotate at a constant speed, catching up with the agitator 50 and bringing the transmission protrusion 62 into contact with the engagement protrusion 53. The agitator 50 remains stationary, slightly buried in the toner surface TS. Furthermore, because the reflective member 55 remains completely removed from the right side of the detection window 45, the detection determination result remains "not detected."

After time T4, the agitator 50 rotates with the outer casing 51C mainly moving inside the toner as the driving force is transmitted from the transmission protrusion 62 of the drive transmission body 60 to the engagement protrusion 53, thereby agitating the toner.

At time T5, the agitator 44 is in the state shown in FIG. 8(F). That is, the drive transmission body 60 and the agitator 50 rotate as a unit at a constant speed, and both are located slightly before the bottom dead center. Also, a portion of the reflecting member 55 is located to the right of the detection window 45, and the agitator 50 is in the detection position, so the detection result switches to "detected."

After that, at time T6, the stirring unit 44 goes into the state shown in FIG. 8(A) as at time T0. That is, in the stirring unit 44, the state from time T0 to time T6 is repeated periodically while the ID motor 34 continues to rotate. Therefore, at time T7, the stirring unit 44 goes into the state shown in FIG. 8(B) as at time T1, and the detection judgment result switches to "non-detection."

[1-4-2. When the remaining toner amount is relatively low]
Next, a case where the remaining amount of toner contained in the toner containing space 43 in the ID unit 14 is relatively small will be described. Figure 9, which corresponds to Figure 7, shows a schematic timing chart of (A) the rotation or stop of the ID motor 34, (B) the position of the drive transmission body 60, (C) the position of the agitator 50, and (D) the detection and determination result by the printer control unit 3 based on the light receiving signal obtained from the toner sensor 36.

Figures 10A-E, which correspond to Figures 8A-F, respectively, show schematic diagrams of the relationship between the positions of the agitator 50 and drive transmission body 60, the position of the detection window 45, and the toner surface TS, which represents the surface of the toner stored in the toner storage space 43, at each point in time in Figure 9. In Figure 10, as in Figure 8, of the circular arc-shaped arrows based on the agitation central axis X44, the arrow on the inner circumference represents the magnitude of the rotational speed of the drive transmission body 60, and the arrow on the outer circumference represents the magnitude of the rotational speed of the agitator 50.

At times T10, T11, and T12, the agitation unit 44 is in the same state as at times T0, T1, and T2 (Figures 7 and 8), respectively, when the remaining amount of toner is relatively large.

That is, at time T12, the agitator 44 is in the state shown in FIG. 10(C). That is, the drive transmission body 60 and the agitator 50 rotate as a unit at a constant speed, and both are located at the top dead center. Also, since the reflecting member 55 is completely removed from the right side of the detection window 45, the detection judgment result remains "not detected."

After time T12, the agitator 50 rotates at a faster rotational speed than the drive transmission body 60, causing the outer shell 51C to fall due to gravity acting mainly on the outer shell 51C, and as a result, the engagement protrusion 53 separates from the transmission protrusion 62 of the drive transmission body 60. Thereafter, as shown in FIG. 10(D), when the outer shell 51C comes into contact with the toner surface TS, the toner impedes the agitator 50's progress and generates resistance, so the agitator 50 comes to rest with part of the outer shell 51C buried in the toner.

At time T13, the agitator 44 is in the state shown in FIG. 10(D). That is, the drive transmission body 60 continues to rotate at a constant speed, but is significantly behind the agitator 50. The agitator 50 is stationary and slightly buried in the toner surface TS. Also, unlike FIG. 8(D), a portion of the reflective member 55 is located to the right of the detection window 45, and the agitator 50 is in the detection position, so the detection result switches to "detected."

At time T14, the agitator 44 is in the state shown in FIG. 10(E). That is, the drive transmission body 60 continues to rotate at a constant speed, catching up with the agitator 50 and bringing the transmission protrusion 62 into contact with the engagement protrusion 53. The agitator 50 is stationary and slightly buried in the toner surface TS. In addition, because most of the reflective member 55 remains positioned to the right of the detection window 45, the detection result remains "detected."

After time T14, the agitator 50 rotates with the outer casing 51C mainly inserted into the toner as the driving force is transmitted from the transmission protrusion 62 of the drive transmission body 60 to the engagement protrusion 53, thereby agitating the toner.

At time T15, the stirring unit 44 goes into the state shown in FIG. 10(A), similar to time T10. That is, in the stirring unit 44, the state of times T10 to T15 is repeated periodically while the ID motor 34 continues to rotate. Therefore, at time T16, the stirring unit 44 goes into the state shown in FIG. 10(B), similar to time T11, and the detection determination result switches to "non-detection."

[1-4-3. Determining remaining toner amount]
Incidentally, when the remaining amount of toner (i.e. the remaining amount of toner contained in the toner containing space 43) is relatively large, the detection determination result by the printer control unit 3 (FIG. 7D) shows that the detection period DT1, which is the period during which "detection" occurred, is a relatively short period from time T5 to time T7. On the other hand, when the remaining amount of toner is relatively small, the detection determination result by the printer control unit 3 (FIG. 9D) shows that the detection period DT2 is a relatively long period from time T13 to time T16. Thus, in the printer 1, there is a relationship in which when the remaining amount of toner in the ID unit 14 becomes relatively small, the detection period DT obtained by the printer control unit 3 becomes longer.

In the ID unit 14, the rotational speed of the drive transmission body 60 changes according to the rotational speed of the ID motor 34, and the length of the period required for one rotation (hereinafter referred to as the drive period CT) also changes. Therefore, even if the remaining amount of toner is constant, if the drive period CT changes, the detection period will also change. This drive period CT is the period from time T0 to time T6 in FIG. 7, and the period from time T10 to time T15 in FIG. 9.

Because of this relationship, the printer 1 expresses the detection period DT as a ratio (i.e., a relative ratio) to the drive period CT, and by comparing this with a predetermined threshold value, it becomes possible to determine the remaining toner amount based on the detection period DT, regardless of the rotation speed of the ID motor 34 or the drive period CT.

Specifically, the printer control unit 3 calculates the detection ratio, which is the detection period DT divided by the drive cycle CT, and then compares the detection ratio with the near-end threshold and empty threshold that are set in advance.

First, when the amount of toner remaining in the toner storage space 43 is relatively large (e.g., Figures 7 and 8) and printing processing can be performed without problems, the detection ratio value will be a relatively small value. Hereinafter, such a toner remaining amount will also be referred to as a sufficient remaining amount.

In contrast, the near-end threshold is set to a value that is slightly larger than the detection ratio when the remaining amount of toner is sufficient, and is capable of determining that the remaining amount of toner is relatively low. In the printer 1, when the detection ratio exceeds the near-end threshold, the printer 1 enters a near-end state. In this near-end state, although printing is possible using the toner in the toner storage space 43, printing will soon become impossible due to a lack of toner, and the user must prepare to replace the toner cartridge 13. Hereinafter, this type of remaining amount of toner will also be referred to as a near-end amount.

On the other hand, the empty threshold is set to a value that is greater than the near-end threshold and can determine that the remaining toner amount is extremely low. In the printer 1, when the detection rate exceeds the empty threshold, the printer 1 enters an empty state. In this empty state, there is not enough toner in the toner storage space 43, so printing is no longer possible and the user must replace the toner cartridge 13. Hereinafter, this type of remaining toner amount will also be referred to as the empty remaining amount.

In this way, in the printer 1, the printer control unit 3 determines the remaining amount of toner in the toner storage space 43 in the ID unit 14 based on the detection signal obtained from the toner sensor 36 in response to the rotation status of the agitator 50 in the agitator 44. At this time, the printer control unit 3 determines that the remaining amount is sufficient if the detection ratio is equal to or greater than the near-end threshold, determines that the remaining amount is near-end if the detection ratio is less than the near-end threshold and equal to or greater than the empty threshold, and determines that the remaining amount is empty if the detection ratio is less than the empty threshold.

In addition, in the printer 1, the printer control unit 3 can detect whether the agitator 50 is located at or near the bottom dead center based on the detection signal obtained from the toner sensor 36. Therefore, hereinafter, the printer control unit 3 and the toner sensor 36 are collectively referred to as the remaining amount detection unit.

[1-4-4. Proximity and Distance Ranges]
In the ID unit 14, as described above, the toner contained in the toner containing space 43 is stirred as the stirrer 50 rotates. When the stirrer 50 moves from the bottom dead point to the top dead point, it raises the toner around the outer portion 51C (FIG. 4) of the bent column 51, and when the stirrer moves from the top dead point to the bottom dead point, it lowers the toner around the outer portion 51C.

For this reason, in the ID unit 14, as shown in FIG. 11A, when the agitator 50 is moving from bottom dead center to top dead center and is located near the center or toward the top in the vertical direction, the agitator 50 moves closer to the ID unit supply hole 42 or is located in a close position. At this time, in the ID unit 14, there is a high possibility that a portion of the toner that has risen in the toner storage space 43 due to the movement or position of the agitator 50 will come into contact with the lower surface of the toner cartridge 13 through the ID unit supply hole 42 and adhere to the toner cartridge 13.

On the other hand, in the ID unit 14, as shown in FIG. 11B, when the agitator 50 is moving from the top dead center to the bottom dead center, or when the agitator 50 is positioned downward in the vertical direction, the agitator 50 moves away from the ID unit supply hole 42, or is located at a position sufficiently separated from it. In this case, in the ID unit 14, the toner that has descended in the toner storage space 43 due to the movement or position of the agitator 50 is sufficiently separated from the ID unit supply hole 42 and the lower side of the toner cartridge 13, and is extremely unlikely to adhere to the toner cartridge 13.

In this embodiment, therefore, in the ID unit 14, a virtual direction line L1 is defined that is centered on the mixing central axis X44 and points upward, and a virtual direction line L2 is defined that is rotated 120 degrees clockwise from the direction line L1 and points diagonally downward toward the front. In this embodiment, of the two ranges separated by the direction lines L1 and L2, the 120-degree angle range located on the front side is defined as the proximity range AN, and the 240-degree angle range located on the rear or lower side is defined as the separation range AF. For convenience of explanation, the proximity range AN is also referred to as the supply port proximity range, and the separation range AF is also referred to as the supply port separation range.

In this case, when the agitator 50 is stopped in the proximity range AN in the image forming unit 12 (FIG. 11A), there is a high possibility that the toner that has risen from the toner storage space 43 is adhering to the outside of the toner cartridge 13. If the toner cartridge 13 is replaced in this image forming unit 12, the toner that was adhering to the outside of the toner cartridge 13 may peel off and fall during the replacement work, causing damage to the inside of the printer 1 and its surroundings. For this reason, it is preferable not to perform the replacement work of the toner cartridge 13 in the image forming unit 12.

On the other hand, in the image forming unit 12, when the agitator 50 is stopped in the separation range AF (FIG. 11B), the toner is contained within the toner storage space 43, and it is highly unlikely that the toner adheres to the outside of the toner cartridge 13. In this case, no problems will occur in the image forming unit 12 even if the toner cartridge 13 is replaced.

When replacing the toner cartridge 13 in the image forming unit 12, the printer 1 controls the ID motor 34 in advance by the printer control unit 3 to stop the agitator 50 in the ID unit 14 of the image forming unit 12 in the separation range AF (details will be described later).

[1-5. Printing process]
Next, a printing process according to the remaining amount of toner in the printer 1 will be described. When the power is turned on, the printer control unit 3 (FIG. 2) of the printer 1 performs a predetermined initialization process. In this initialization process, the printer control unit 3 determines and stores the remaining amount of toner at this time. The remaining amount of toner stored at this time is either a sufficient amount, a near-end amount, or an empty amount. After performing this initialization process, the printer control unit 3 starts a printing process procedure RT1 shown in FIG. 12 and proceeds to the first step SP1.

In step SP1, the printer control unit 3 receives a print command from a host device (not shown), such as a computer device, connected via a specified network, and then proceeds to the next step SP2. This print command includes, for example, print data representing the image to be printed, the size of the paper to be printed on, and information indicating the print density and enlargement/reduction settings. In step SP2, the printer control unit 3 checks the most recent amount of remaining toner stored, i.e., the amount of remaining toner at this time, and then proceeds to the next step SP3.

In step SP3, the printer control unit 3 determines whether the remaining amount of toner is sufficient. If a positive result is obtained here, this indicates that a sufficient amount of toner is contained in the toner storage space 43 of the ID unit 14, the printing operation can be performed, and there is no need to replace the toner cartridge 13 for the time being. At this time, the printer control unit 3 moves to the next step SP4.

At this time, the operation of the ID motor 34, the position of the drive transmission body 60, the position of the agitator 50, and the detection results of the agitator 50 repeatedly show fluctuations such as those shown in the timing chart of Figure 7 from time T0 to T6.

In step SP4, the printer control unit 3 starts the printing operation based on the received print command, and then proceeds to the next step SP5. That is, the printer control unit 3 starts a series of operations, such as separating paper P one by one from the paper cassette 5 (Figure 1) and transporting it along the transport path W, forming a toner image based on the print data using the image forming unit 12 and transferring it to the paper P, and fixing the toner image to the paper P using the fixing unit 20. The printer control unit 3 also repeats this series of operations for the number of pages included in the print data.

At this time, when the printer control unit 3 starts the printing operation, it starts driving the ID motor 34 together with each motor, rotating the photosensitive drum 17 and each roller of the ID unit 14, and also appropriately rotating the drive transmission body 60 and the agitator 50 (Figure 4) of the agitator 44.

In step SP5, when the printer control unit 3 has finished printing all pages included in the print data, it ends the printing operation and proceeds to the next step SP6. In step SP6, the printer control unit 3 stops the operation of each motor, such as the paper feed motor 31 and the fixing motor 32, as well as the ID motor 34, and proceeds to the next step SP7.

In step SP7, the printer control unit 3 determines the remaining toner amount based on the latest detection signal obtained from the toner sensor 36, stores the obtained determination result, and proceeds to the next step SP21. Specifically, the printer control unit 3 identifies the detection period DT (FIGS. 7 and 9) based on the latest detection signal obtained from the toner sensor 36, calculates the detection ratio by dividing this detection period DT by the drive cycle CT, compares this detection ratio with the near-end threshold and the empty threshold, and determines the remaining toner amount based on the obtained comparison result.

On the other hand, if a negative result is obtained in step SP3, this indicates that the remaining toner amount is either near-end or empty, and that the toner cartridge 13 will need to be replaced soon or immediately. In this case, the printer control unit 3 proceeds to the next step SP8.

In step SP8, the printer control unit 3 causes the display unit 4 to display a predetermined message indicating that it is soon time to replace the toner cartridge 13, and then proceeds to the next step SP9. In response to this, the user can visually confirm this message and prepare to replace the toner cartridge 13, such as by arranging for a new toner cartridge 13.

In step SP9, the printer control unit 3 determines whether the remaining toner is near the end. If a negative result is obtained here, this indicates that the remaining toner is empty, that is, an extremely small amount of toner is contained in the toner storage space 43 of the ID unit 14, and printing cannot be performed. In this case, the printer control unit 3 proceeds to the next step SP10.

In step SP10, the printer control unit 3 causes the display unit 4 to display a predetermined message indicating that printing has been stopped due to a lack of toner, and then proceeds to the next step SP11. In step SP11, the printer control unit 3 stops printing based on the print command received in step SP1, and proceeds to the next step SP21 without starting the printing operation.

On the other hand, if a positive result is obtained in step SP9, this indicates that although the remaining amount of toner contained in the toner storage space 43 of the ID unit 14 is relatively low, printing is possible. In this case, since the time to replace the toner cartridge 13 was notified in step SP8, there is a possibility that the user will replace the toner cartridge 13 after the current printing operation is completed. In this case, the printer control unit 3 proceeds to the next step SP12.

At this time, the operation of the ID motor 34, the position of the drive transmission body 60, the position of the agitator 50, and the detection results of the agitator 50 repeatedly show fluctuations such as those shown in the timing chart of FIG. 9 from time T10 to T15.

In step SP12, the printer control unit 3 starts the printing operation based on the received print command, as in step SP4, and then proceeds to the next step SP13. At this time, the printer control unit 3 also starts driving the ID motor 34, as in step SP4, and also appropriately rotates the drive transmission body 60 and the agitator 50 (Figure 4) of the agitator 44.

In step SP13, when the printer control unit 3 has finished printing all pages included in the print data, it ends the printing operation as in step SP5 and proceeds to the next step SP14. In step SP14, the printer control unit 3 stops the operation of each motor, such as the paper feed motor 31 and the fixing motor 32 (Figure 2), while continuing to drive the ID motor 34, and proceeds to the next step SP15.

In step SP15, the printer control unit 3 executes a subroutine called a separation range stop process (described in detail below) to stop the agitator 50 of the ID unit 14 within the separation range AF and to notify the user to replace the agitator 50, and then proceeds to the next step SP16. In step SP16, the printer control unit 3 ends the printing process procedure RT1.

Next, the separation range stop processing will be described. When the printer control unit 3 moves to step SP15 in the print processing procedure RT1 (FIG. 12), it starts the separation range stop processing procedure RT2 shown in FIG. 13 as a subroutine and moves to the first step SP21.

In step SP21, the printer control unit 3 determines whether the drive speed (i.e., rotation speed) of the ID motor 34 is low. If a negative result is obtained here, this indicates that the transport speed of the transport path W during the printing operation is normal, and accordingly, the ID motor 34 is also driven at a normal speed, so that the agitator 50 is rotating at a relatively high speed. At this time, the printer control unit 3 proceeds to the next step SP22.

In step SP22, the printer control unit 3 switches the drive speed of the ID motor 34 to a low speed, and then proceeds to the next step SP23. This allows the printer control unit 3 to improve the detection accuracy of the timing of "detection," i.e., the timing when the signal level of the detection signal exceeds the detection threshold, based on the detection signal obtained from the toner sensor 36.

On the other hand, if a positive result is obtained in step SP21, this indicates that the ID motor 34 is already at a low speed and should continue to be driven at the current speed. In this case, the printer control unit 3 proceeds to the next step SP23.

In step SP23, the printer control unit 3 obtains the current time from an internal clock circuit (not shown) and proceeds to the next step SP24. In step SP24, the printer control unit 3 determines whether or not a "detection" has occurred based on the detection signal obtained from the toner sensor 36, that is, whether or not the signal level of the detection signal has exceeded the detection threshold. If a positive result is obtained here, this indicates that the position of the agitator 50 can be determined according to the subsequent time, based on the point in time at which the signal level of the detection signal exceeded the detection threshold. At this point, the printer control unit 3 proceeds to the next step SP25.

In step SP25, the printer control unit 3 determines that the agitator 50 has passed the bottom dead center when the signal level of the detection signal changes from "detected" to "not detected," updates the relationship between time and the position of the agitator 50, and proceeds to the next step SP26. Here, the point when the signal level of the detection signal changes to "not detected" corresponds to time T16 in Figure 9, and the agitator 44 is in the state shown in Figure 10 (B).

On the other hand, if a negative result is obtained in step SP24, this indicates that "detection" has not occurred at this point in time, and the position of the agitator 50 cannot be updated according to the time. In this case, the printer control unit 3 proceeds to the next step SP26.

In step SP26, the printer control unit 3 calculates the position of the agitator 50 at the current time based on the relationship between the position of the agitator 50 and the time obtained up to that point, and proceeds to the next step SP27. Specifically, the printer control unit 3 pre-stores the rotational speed of the agitator 50 when the ID motor 34 is driven at a low speed, and calculates the position of the agitator 50 at the current time using the past position and time of the agitator 50, the elapsed time, and the rotational speed.

In step SP27, the printer control unit 3 determines whether the position of the agitator 50 at the current time is within the separation range AF (Figure 11). If a negative result is obtained here, this indicates that the agitator 50 is located within the proximity range AN (Figure 11) at this time, and therefore the agitator 50 should not be stopped. At this time, the printer control unit 3 returns to step SP23 again, and repeats the series of processes in a state after the position of the agitator 50 has changed over time.

On the other hand, if a positive result is obtained in step SP27, this indicates that if the agitator 50 is stopped at this point, the agitator 50 is within the separation range AF, and therefore the possibility of toner adhering to the outside of the toner cartridge 13 is extremely low. At this time, the printer control unit 3 proceeds to the next step SP28. In step SP28, the printer control unit 3 immediately stops the ID motor 34, and proceeds to the next step SP29. As a result, in the agitator 44 of the ID unit 14, the drive transmission body 60 and the agitator 50 immediately stop at their positions at that time, i.e., within the separation range AF.

In step SP29, the printer control unit 3 determines the remaining toner amount (whether it is full, near-end, or empty) based on the latest detection signal obtained from the toner sensor 36, stores the obtained determination result, and proceeds to the next step SP30. Specifically, the printer control unit 3 identifies the detection period DT (FIGS. 7 and 9) based on the latest detection signal obtained from the toner sensor 36, calculates the detection ratio by dividing this detection period DT by the drive cycle CT, compares this detection ratio with the near-end threshold and empty threshold, respectively, and determines the remaining toner amount based on the obtained comparison result. In step SP30, the printer control unit 3 ends the separation range stop processing procedure RT2 as a subroutine, and returns to the original print processing procedure RT1 (FIG. 12).

[1-6. Effects, etc.]
In the above configuration, when the remaining amount of toner in the ID unit 14 is near the end during the printing process (FIG. 12), the printer 1 according to the first embodiment performs the separation range stop process (FIG. 13) and stops the agitator 50 within the separation range AF (FIG. 11(B)). This makes it possible for the printer 1 to avoid a situation in which "toner rising with the movement of the outer shell 51C adheres to the outer surface of the toner cartridge 13," which may occur when the agitator 50 is stopped within the approach range AN (FIG. 11(A)).

As a result, when the user removes the toner cartridge 13 from the ID unit 14, the printer 1 can effectively prevent toner from peeling off from the outer surface of the toner cartridge 13 and soiling the inside and surroundings of the printer housing 2.

From another perspective, in the printer 1, in order to thoroughly stir the toner in the toner storage space 43, it is desirable for the outer shell 51C of the stirrer 50 to reach the vicinity of the ID unit supply hole 42, i.e., the vicinity of the bottom surface of the toner cartridge 13. However, in the printer 1, when replacing the toner cartridge 13, if the outer shell 51C of the stirrer 50 is located within the proximity range AN (Figure 11), i.e., in the vicinity of the toner cartridge 13, there is a risk of the toner adhering to the outer surface, as described above.

In the printer 1, the stopping position of the agitator 50 is controlled without changing the position of the agitator 44 in the ID unit 14 or the configuration of the agitator 50, so that the outer shell 51C is separated from the toner cartridge 13 when the toner cartridge 13 is replaced. This allows the printer 1 to achieve both good agitation of the toner in the toner storage space 43 by the agitator 44 and prevention of toner adhesion and peeling off from the outer surface when the toner cartridge 13 is replaced.

In addition, in the printer 1, when the reflective member 55 (FIG. 4) of the agitator 50 is detected by the toner sensor 36, the position of the agitator 50 is associated with the time, and based on this relationship and the rotational speed of the agitator 50 and the elapsed time, it is determined whether the agitator 50 is located within the separation range AF. As disclosed in Patent Document 1, the configuration of the agitator 44 and toner sensor 36 has been previously adopted by the applicant, and while being a relatively simple configuration, it is capable of agitating the toner in the toner storage space 43 and detecting the amount of remaining toner.

In other words, the printer 1 of the present invention can stop the agitator 50 within the separation range AF, but achieves this without adding a new position sensor or the like, by devising a control for the ID motor 34 that drives the agitator 44. Therefore, the printer 1 can use the agitator 44 and toner sensor 36 as before, without changing the design.

From another perspective, the printer 1 determines the timing when the toner sensor 36 receives the reflected light from the reflecting member 55 on the rotating agitator 50 as the timing when the agitator 50 is at the bottom dead center, i.e., the timing when it is at the detection position, and associates the time with the position. Therefore, even if the agitator 50 passes the bottom dead center (i.e., the detection position) without coinciding with the timing when the detection light is received by the toner sensor 36 and cannot be detected within one cycle, it is sufficient to be able to detect the agitator 50 when it reaches the vicinity of the bottom dead center the next time onwards. In other words, the printer 1 can ultimately associate the position of the agitator 50 with the time with an extremely high degree of accuracy, and can accurately calculate the position of the agitator 50 at each time.

In addition, in the printer 1, if the driving speed of the ID motor 34 is normal during the separation range stop process (FIG. 13), it is switched to low speed (steps SP21 and SP22). This significantly reduces the possibility that the timing of the emission and reception of detection light by the toner sensor 36 will differ from the timing at which the reflecting member 55 reaches the vicinity of the bottom dead center, and the agitator 50 can be detected reliably.

Furthermore, in the printer 1, the drive speed of the ID motor 34 is switched to a low speed only when the separation range stop process is performed, and the agitator 50 is stopped within the separation range AF (Figure 13). Therefore, in the printer 1, when the toner cartridge 13 is not replaced, such as when the remaining toner amount is sufficient, the ID motor 34 is not switched to a low speed unnecessarily and is stopped regardless of the position of the agitator 50, so the process can be completed in a short time and power consumption can be reduced.

With the above configuration, the printer 1 according to the first embodiment stops the agitator 50 within the separation range AF based on the detection signal obtained from the toner sensor 36 when the remaining toner amount is near the end. This allows the printer 1 to keep the agitator 50 away from the outer surface of the toner cartridge 13, effectively preventing toner from adhering to the outer surface. This allows the printer 1 to effectively prevent toner from peeling off from the outer surface and soiling the inside and surroundings of the printer housing 2 when the toner cartridge 13 is removed from the ID unit 14 by the user.

2. Second embodiment
A printer 201 (FIGS. 1 and 2) according to the second embodiment differs from printer 1 according to the first embodiment in that it has a printer control unit 203 instead of printer control unit 3, but is otherwise configured in the same manner.

The printer control unit 203, like the printer control unit 3 according to the first embodiment, has a CPU, a memory unit, etc. (not shown), and executes various programs. However, the printer control unit 203 executes some programs that are different from those of the printer control unit 3. In addition, when the printer control unit 203 drives the ID motor 34 to rotate the agitator 50, it stores the time when the agitator 50 was last detected based on the detection signal obtained from the toner sensor 36.

When performing printing processing, the printer control unit 203 executes the printing processing procedure RT1 (FIG. 12) in the same manner as in the first embodiment. However, when performing the separation range stop processing in step SP15 of the printing processing procedure RT1, the printer control unit 203 executes the separation range stop processing procedure RT22 shown in FIG. 14, which corresponds to FIG. 13, as a subroutine.

When the printer control unit 203 starts the separation range stop processing procedure RT22, in step SP221, it performs the same processing as step SP23 of the separation range stop processing procedure RT2 (Figure 13), and then proceeds to the next step SP222. In other words, the printer control unit 203 maintains the current drive speed of the ID motor 34 without slowing it down.

In step SP222, the printer control unit 203 calculates the position of the agitator 50 at the current time based on the time when the agitator 50 was last detected, and proceeds to the next step SP223. Specifically, the printer control unit 203 pre-stores the rotation speed of the agitator 50, and calculates the position of the agitator 50 at the current time using the time when the agitator 50 was last detected, the elapsed time, and the rotation speed.

In step SP223, the printer control unit 203 calculates the time at which the agitator 50 is located within the separation range AF (Figure 11) as the separation time based on the position of the agitator 50 at the current time, and proceeds to the next step SP224.

In step SP223, the printer control unit 203 performs, for example, the following calculation process. First, if the agitator 50 is located within the separation range AF at the current time, the printer control unit 203 sets the current time as the separation time. Also, if the agitator 50 is located within the proximity range AN, the printer control unit 203 calculates the future time at which the agitator 50 will reach top dead center and enter the separation range AF, and sets this as the separation time.

In step SP224, the printer control unit 203 determines whether the current time is the separation time. If a negative result is obtained here, this indicates that the agitator 50 has not yet entered the separation range AF, and therefore the ID motor 34 should not be stopped. At this time, the printer control unit 203 repeats this step SP224, continuing to rotate the agitator 50 over time while waiting for the separation time to arrive.

On the other hand, if a positive result is obtained in step SP224, this indicates that if the agitator 50 is stopped at this point, the agitator 50 is within the separation range AF, and therefore the possibility of toner adhering to the outside of the toner cartridge 13 is extremely low. In this case, the printer control unit 203 proceeds to the next step SP225.

Then, in steps SP225 and SP226, the printer control unit 203 performs the same processes as steps SP28 and SP29, respectively, of the separation range stop processing procedure RT2 (Figure 13), and then proceeds to the next step SP227 to end the separation range stop processing procedure RT22.

In the above configuration, in the printer 201 according to the second embodiment, when the remaining toner amount is near-end during the separation range stop process, the printer 201 calculates the position of the agitator 50 at the current time based on the time when the agitator 50 was last detected. Furthermore, the printer 201 calculates the separation time when the agitator 50 is located within the separation range AF, and stops the ID motor 34 at the separation time, thereby stopping the agitator 50 within the separation range AF.

As a result, the printer 201 allows the user to replace the toner cartridge 13, similar to the first embodiment, and at that time, the adhesion of toner to the outer surface of the toner cartridge 13 can be effectively prevented.

In particular, the printer 201 calculates the separation time when the agitator 50 is within the separation range AF and stops the agitator 50, so there is no need to continuously monitor the detection signal from the toner sensor 36 as in the first embodiment. As a result, the printer 201 does not need to switch the drive speed of the ID motor 34 to a low speed, so the separation time is reached in a relatively short time, which is expected to reduce the time the user has to wait.

In other respects, the printer 201 according to the second embodiment can achieve the same effects as the printer 1 according to the first embodiment.

3. Other embodiments
In the above-described first embodiment, in steps SP21 and SP22 of the separation range stop process (FIG. 13), if the driving speed of the ID motor 34 is normal, it is switched to a low speed, and then the processes from step SP23 onwards are performed. However, the present invention is not limited to this. For example, if the driving speed of the ID motor 34 is normal and the detection plate 52 of the agitator 50 cannot be detected within a predetermined period of time, it may be switched to a low speed. Alternatively, for example, the driving speed of the ID motor 34 may be maintained unchanged and each process from step SP23 onwards may be performed. In this case, when the position of the agitator 50 is calculated in step SP26, the rotation speed of the agitator 50 corresponding to the driving speed of the ID motor 34 may be used.

In the second embodiment described above, the separation time is calculated based on the position of the agitator 50 in the separation range stop process (FIG. 14) without changing the drive speed of the ID motor 34. However, the present invention is not limited to this. For example, before step SP221, a process similar to that of the first embodiment may be performed, and the drive speed of the ID motor 34 may be switched to a low speed if it is normal. In this case, the rotation speed of the agitator 50 when switched to low speed is stored in advance, and in step SP222, the position of the agitator 50 is calculated using the rotation speed based on the detection signal obtained from the toner sensor 36 after the drive speed of the ID motor 34 is switched to low speed.

Furthermore, in the above-mentioned first embodiment, the angle of the proximity range AN is described as 120 degrees. However, the present invention is not limited to this, and the proximity range AN may be set to any angle. In other words, the range in which toner may adhere to the toner cartridge 13 when the agitator 50 is stopped can be appropriately set depending on the relative positions of the agitator 44 and the toner cartridge 13 and the position and size of the ID unit supply hole 42, etc. The same applies to the second embodiment.

Furthermore, in the first embodiment described above, a form was described in which if the remaining amount of toner is near the end at the start of the printing process (FIG. 12), the separation range stop process (FIG. 13) is performed after the printing operation is completed. However, the present invention is not limited to this. For example, even if the remaining amount of toner is sufficient at the start of the printing process, if the remaining amount of toner is near the end at the end of the printing process, the separation range stop process may be performed after the printing operation is completed. Alternatively, for example, this may be the case when an initialization process is performed in the printer 1 or when the printer returns from a power saving state. In other words, after the ID motor 34 is driven to rotate the agitator 50 of the agitator 44, if the remaining amount of toner is near the end, the separation range stop process may be performed. The same applies to the second embodiment.

Furthermore, in the first embodiment described above, the remaining toner amount is determined based on the light receiving signal obtained by the toner sensor 36 during the printing process (FIG. 12), and if the remaining toner amount is near the end, the separation range stop process (FIG. 13) is performed. However, the present invention is not limited to this, and for example, the amount of toner consumed, which is the amount of toner consumed during the printing process, may be calculated based on the image data to be printed, and the remaining toner amount may be determined based on the integrated value of the amount of toner consumed. The point is that it is sufficient to be able to determine that there is a possibility that the toner cartridge 13 will be replaced by the user. The same applies to the second embodiment.

Furthermore, in the first embodiment described above, the bent columnar body 51 of the agitator 50 is configured by bending a cylindrical member into a crank shape (FIG. 4). However, the present invention is not limited to this, and the agitator 50 may have various shapes, such as a shape in which a linear trunk body along the agitator central axis X44 has multiple branches protruding downward, i.e., a comb-like shape. In this case, it is desirable to have a shape that protrudes in only one direction from the agitator central axis X44, so that when the agitator 50 is located at the bottom dead center, there is no part protruding above the agitator central axis X44. The same applies to the second embodiment.

Furthermore, in the above-mentioned first embodiment, a configuration was described in which the agitator 50, which has the function of agitating the toner in the agitator 44, is provided with a detection plate 52 and a reflective member 55 for detection by the toner sensor 36, that is, a configuration in which the remaining toner amount is detected using a part of the agitator 44. However, the present invention is not limited to this, and for example, a reflective member may be provided on a specific part (not shown) that is separate from the agitator 50 and is linked to the agitator 50, and the remaining toner amount may be detected based on the position of the reflective member. Alternatively, for example, the remaining toner amount may be detected by a toner sensor that does not use the agitator 44. In this case, the drive transmission body 60 may be omitted from the agitator 44, and the driving force of the ID motor 34 may be constantly transmitted to the agitator 50. The same applies to the second embodiment.

Furthermore, in the above-mentioned first embodiment, a light-emitting element that emits detection light and a light-receiving element that receives the detection light are provided in the toner sensor 36, and the detection light is reflected by a reflecting member 55 provided on the detection plate 52 of the agitator 50, thereby detecting the position of the agitator 50. However, the present invention is not limited to this, and the position of the agitator 50 may be detected, for example, by providing a magnet on the detection plate 52 and providing a magnetic sensor on the toner sensor 36. In other words, in the present invention, various sensors based on various detection principles can be used as the toner sensor 36. The same applies to the second embodiment.

Furthermore, in the above-mentioned first embodiment, the toner in the toner storage space 43 is stirred by rotating the agitator 50 around the agitation central axis X44 of the agitator 44 and moving it to draw a circular trajectory (FIGS. 3 to 5). However, the present invention is not limited to this, and the agitator 50 may be moved to draw various trajectories within the toner storage space 43, for example, by moving it back and forth to draw a linear trajectory along the vertical direction within the toner storage space 43. The point is that it is sufficient to be able to stir the toner by periodically displacing the agitator 50 within the toner storage space 43 based on the driving force transmitted from the ID motor 34. The same applies to the second embodiment.

Furthermore, in the first embodiment described above, a configuration in which the printer 1 is provided with one image forming unit 12, i.e., a configuration in which monochrome images are printed, has been described. However, the present invention is not limited to this, and for example, the printer 1 may be provided with two or more image forming units 12 so that color images can be printed. The same applies to the second embodiment.

Furthermore, in the above-mentioned first embodiment, the printer 1 is configured as a single-function SFP. However, the present invention is not limited to this, and the printer 1 may be an image forming device having various other functions, such as an MFP (Multi Function Peripheral) having the functions of a copier or facsimile machine. The same applies to the second embodiment.

Furthermore, the present invention is not limited to the above-mentioned embodiments and other embodiments. In other words, the scope of application of the present invention extends to embodiments in which the above-mentioned embodiments are combined in part or in whole with any of the above-mentioned other embodiments. The scope of application of the present invention also extends to cases in which a part of the configuration described in any of the above-mentioned embodiments and other embodiments is extracted and replaced or diverted with a part of the configuration of any of the above-mentioned embodiments and other embodiments, or a part of the extracted configuration is added to any of the embodiments.

Furthermore, in the above-mentioned first embodiment, the printer 1 as an image forming apparatus is described as being configured by the ID unit 14 as a developing unit, the toner storage space 43 as a developer storage unit, the toner cartridge 13 as a developer container, the agitator 50 as an agitator, the toner sensor 36 and the printer control unit 3 as position detection units, the ID motor 34 as a drive unit, and the printer control unit 3 as a control unit. However, the present invention is not limited to this, and the image forming apparatus may be configured by a developing unit, a developer storage unit, a developer container, an agitator, a position detection unit, a drive unit, and a control unit having various other configurations.

The present invention can be used, for example, in electrophotographic printers that have a stirring section in the ID unit.

1, 201...printer, 3, 203...printer control unit, 4...display unit, 12...image forming unit, 13...toner cartridge, 14...ID unit, 34...ID motor, 36...toner sensor, 40...ID unit housing, 42...ID unit supply hole, 43...toner storage space, 44...agitating unit, 45...detection window, 50...agitating body, 52...detection plate, 55...reflective member, 60...drive transmission body, 61...cylindrical portion, 62...transmission protrusion, AF...separation range, AN...proximity range, CT...driving period, W...transport path, X44...agitating central axis.

Claims (11)

a developing section that develops the electrostatic latent image formed on the developer carrier with a developer;
a developer container provided in the developing section and configured to contain the developer for developing the electrostatic latent image;
a developer container that is detachable from the developing unit, that contains the developer, and that supplies the developer from a supply port to the developer accommodating unit;
a stirring body provided in the developing unit, displaceable to a plurality of positions within the developer accommodating unit, including a supply port proximity range close to the supply port in the developer container, a supply port distant range away from the supply port, and a predetermined detection position, and configured to stir the developer within the developer accommodating unit;
a position detection unit that detects a position of the stirring body relative to the detection position in the developer accommodating unit or a position linked to the stirring body;
A drive unit that supplies a driving force to the stirring body;
and a control unit that controls the drive unit based on a detection result by the position detection unit so as to stop the agitator that has passed the detection position in the supply port separation range. the agitator rotates around a virtual agitation central axis located between the supply port adjacent range and the supply port distant range in the developer accommodating unit by the driving force supplied from the drive unit,
The supply port approach range represents a partial angular range in one revolution around the central axis of the stirring,
2. The image forming apparatus according to claim 1, wherein the control unit controls the drive unit to stop supplying the driving force when the position of the agitator detected by the position detection unit falls within the supply port separation range. the agitator rotates around a virtual agitation central axis located between the supply port adjacent range and the supply port distant range in the developer accommodating unit by the driving force supplied from the drive unit,
The supply port approach range represents a partial angular range in one revolution around the central axis of the stirring,
The image forming apparatus according to claim 1, characterized in that the control unit calculates a separation time when the agitator is within the supply port separation range based on the position of the agitator detected by the position detection unit, and controls the drive unit to stop supplying the driving force at the separation time. The image forming apparatus according to claim 1, characterized in that the control unit switches the drive speed of the drive unit to a low speed and then controls the drive unit to stop the agitator in the supply port separation range based on the detection result obtained by the position detection unit. a remaining amount detection unit that detects a remaining amount of the developer in the developer container,
2. The image forming apparatus according to claim 1, wherein the control unit controls the drive unit to stop the agitator at an arbitrary position when the remaining amount is equal to or greater than a predetermined threshold, and to stop the agitator within the supply port separation range when the remaining amount is less than the threshold. a drive transmission body that transmits the drive force from the drive unit to the stirring body only during a part of a predetermined period,
a period during which the agitator stays in the supply port separation range changes depending on the remaining amount of the developer in the developer accommodating portion,
The position detection unit detects whether the stirring body is located at the detection position,
6. The image forming apparatus according to claim 5, wherein the remaining amount detection unit detects the remaining amount of the developer in the developer accommodating unit based on a period during which the position detection unit detects that the stirring body is located at the detection position. the agitator rotates around a virtual agitation central axis located between the supply port approaching range and the supply port separating range in the developer accommodating section based on the driving force supplied from the drive unit, and has a detection object provided at a position corresponding to the agitator with respect to the agitation central axis,
The image forming apparatus according to claim 5 , wherein the remaining amount detection unit detects the remaining amount of the developer based on a detection result of the detection target. The image forming apparatus according to claim 7, characterized in that if the position detection unit is unable to detect the object to be detected within one cycle required for the stirring body to rotate once, the control unit causes the position detection unit to detect the object to be detected in a subsequent cycle. 8. The image forming apparatus according to claim 7, wherein the control unit switches the drive speed of the drive unit to a low speed when the position detection unit is unable to detect the detection target. The detection object has a reflective member that reflects light,
The image forming apparatus according to claim 7, characterized in that the position detection unit has a light-emitting element that emits light and a light-receiving element that receives light, and when the light emitted from the light-emitting element is reflected by the reflecting member and received by the light-receiving element, notifies the control unit that the reflecting member has been detected. The stirring body has a center portion located on the stirring central axis and an outer shell portion spaced apart from the center portion in a predetermined radial direction,
8. The image forming apparatus according to claim 7, wherein the detection object is provided at a position spaced apart from the central stirring axis in the radial direction.

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