JP6484138B2 - Image forming unit and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming unit having a container for storing a developer, and a main body that forms an image using the developer supplied from the container, and an image forming apparatus including the image forming unit.

  There has been proposed an electrophotographic developing device including a main body and a developer supply container detachably attached to the main body (see, for example, Patent Document 1).

JP 2005-250362 A

  In the developing device disclosed in Patent Document 1, when the amount of developer stored in the developer storage chamber of the main body becomes smaller than a predetermined amount, the developer is supplied from the developer supply container to the developer storage chamber, and the developer storage chamber When the developer storage amount becomes a predetermined amount or more, the supply of developer from the developer supply container to the developer storage chamber is stopped. However, when the developer is replenished and stopped only in accordance with the amount of developer accommodated in the developer accommodating chamber as in the developing device disclosed in Patent Document 1, depending on the printing speed, the supply amount is insufficient (developer). There is a risk that a developer supply amount cannot keep up with the usage amount) or an excessive supply amount state (a state where a developer exceeding the developer usage amount is supplied excessively).

  The present disclosure has been made in view of such problems, and an object of the present disclosure is to provide an image forming unit and an image forming apparatus in which an appropriate amount of developer is supplied and a good image can be formed.

An image forming unit according to an embodiment of the present invention includes a container that stores a developer, a main body that forms an image using the developer supplied from the container, and a remaining amount of developer in the main body. A detection unit that detects every cycle, a supply unit that supplies developer from the container to the main unit, and a control unit that controls the main unit and the detection unit so that the first cycle varies according to the image formation speed in the main unit. And a control unit that controls the supply unit so that the supply amount of the developer per first period is constant .

  An image forming apparatus as an embodiment of the present invention includes the image forming unit.

  In the image forming unit and the image forming apparatus according to an embodiment of the present invention, a detection unit that detects the remaining amount of the developer in the main body that performs image formation is provided for each first period, and the control unit performs the first period. The supply unit was controlled to adjust the supply amount of the developer. For this reason, it is easy to avoid a state where the developer supply amount is insufficient or a state where the developer supply amount is excessive.

  According to the image forming unit and the image forming apparatus as an embodiment of the present disclosure, it is possible to supply an appropriate amount of developer and to form a good image.

1 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating an internal configuration of a main body portion of the image forming unit illustrated in FIG. 1. FIG. 2 is a perspective view illustrating an internal configuration of the toner cartridge illustrated in FIG. 1. FIG. 2 is a perspective view illustrating an external configuration of the toner cartridge illustrated in FIG. 1. FIG. 6 is another perspective view illustrating an external configuration of the toner cartridge illustrated in FIG. 1. FIG. 2 is a perspective view illustrating an external configuration of a main body portion of the image forming unit illustrated in FIG. 1. FIG. 5 is another perspective view illustrating an external configuration of a main body portion of the image forming unit illustrated in FIG. 1. FIG. 2 is a perspective view illustrating an internal configuration of a main body portion of the image forming unit illustrated in FIG. 1. It is an expansion perspective view which expands and represents a part of Drawing 5C. FIG. 2 is a cross-sectional view illustrating an internal configuration of a main body portion of the image forming unit illustrated in FIG. 1. FIG. 5C is a perspective view illustrating an overall configuration of a remaining toner amount detection sensor illustrated in FIGS. 5C to 5E. FIG. 6B is an enlarged perspective view showing a main part of the toner remaining amount detection sensor shown in FIG. 6A. FIG. 6B is an enlarged perspective view showing the detection operation of the toner remaining amount detection sensor shown in FIG. 6A. FIG. 6B is another enlarged perspective view showing the detection operation of the toner remaining amount detection sensor shown in FIG. 6A. FIG. 2 is a block diagram illustrating a configuration example of a control mechanism of the image forming apparatus illustrated in FIG. 1. FIG. 10 is an explanatory diagram illustrating a state in an operation example of a toner remaining amount detection sensor when the remaining amount of toner is relatively large. FIG. 9B is an explanatory diagram illustrating another state subsequent to FIG. 9A in the operation example of the toner remaining amount detection sensor. FIG. 9D is an explanatory diagram illustrating another state subsequent to FIG. 9B in the operation example of the toner remaining amount detection sensor. FIG. 9D is an explanatory diagram illustrating another state subsequent to FIG. 9C in the operation example of the toner remaining amount detection sensor. FIG. 9D is an explanatory diagram illustrating another state subsequent to FIG. 9D in the operation example of the toner remaining amount detection sensor. 6 is a time chart showing a change in the amount of received light in the light receiving element when the remaining amount of toner is relatively large. 6 is a time chart showing a change in the amount of received light in the light receiving element when the remaining amount of toner is relatively small. 6 is a time chart illustrating a detection operation of a remaining toner detection sensor and a supply operation of a supply unit when a printing speed is relatively high. 6 is a time chart illustrating a detection operation of a toner remaining amount detection sensor and a supply operation of a supply unit when a printing speed is relatively slow. 6 is a time chart illustrating a supply operation of a supply unit when a plurality of supply operations are performed with respect to one detection operation of a toner remaining amount detection sensor. FIG. 6 is an explanatory diagram illustrating a state in an operation example of a toner remaining amount detection sensor when the remaining amount of toner is relatively small. FIG. 12B is an explanatory diagram illustrating another state subsequent to FIG. 12A in the operation example of the toner remaining amount detection sensor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is an example of the present invention, and the present invention is not limited to the following embodiment. Further, the present invention is not limited to the arrangement, dimensions, dimensional ratios, and the like of the components shown in the drawings. The description will be made in the following order.
1. One Embodiment (Image Forming Apparatus Provided with Basic Structure Image Forming Unit)
2. Modified example

<1. Embodiment>
[Configuration of Image Forming Apparatus]
FIG. 1 schematically illustrates an overall configuration example of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus corresponds to a specific example of the “image forming apparatus” of the present invention. For example, an image (for example, a color image) is printed on a medium PM to be printed, such as paper or film, using an electrophotographic method. It is a printer which forms. The image forming apparatus includes a medium supply unit 1, a transport unit 2, an image forming unit 3, a transfer unit 4, a fixing unit 5, a discharge unit 6, and a control unit 7 inside a housing 100. The control unit 7 controls operations of the medium supply unit 1, the conveyance unit 2, the image forming unit 3, the transfer unit 4, the fixing unit 5, and the discharge unit 6. In this specification, a path through which the medium PM is transported is referred to as a transport path. In the transport path, a direction toward the medium supply unit 1 or a position closer to the medium supply unit 1 when viewed from an arbitrary component is referred to as upstream. In the transport path, a direction opposite to the direction toward the medium supply unit 1 when viewed from any component or a position further away from the medium supply unit 1 is referred to as downstream. A direction in which the medium PM travels (that is, a direction from upstream to downstream) in the transport path is referred to as a transport direction F. A direction (for example, the X-axis direction in FIG. 1) that is parallel to the medium PM being conveyed on the conveyance path and orthogonal to the conveyance direction F is referred to as a width direction. The dimension in the conveyance direction F is called a length, and the dimension in the width direction is called a width.

(Media supply unit 1)
The medium supply unit 1 supplies the medium PM to the transport unit 2 one by one. The medium supply unit 1 includes, for example, a tray 1A, a pickup roller 1B, and a feed roller 1C. In the tray 1A, a plurality of media PM are stored in a stacked state. The tray 1A is detachably attached to the lower part of the image forming apparatus, for example. The pickup roller 1 </ b> B and the feed roller 1 </ b> C function to sequentially feed the medium PM stored in the tray 1 </ b> A to the conveyance path that reaches the conveyance unit 2. The pickup roller 1 </ b> B and the feed roller 1 </ b> C rotate under the control of the control unit 7 in the direction in which the medium PM is fed out toward the downstream transport unit 2. The pickup roller 1B is disposed at a position where it can come into contact with the upper surface of the uppermost medium PM. The feed roller 1C is disposed downstream of the pickup roller 1B.

(Transport unit 2)
The transport unit 2 transports the medium PM from the medium supply unit 1 to the transfer unit 4 while restricting skew feeding. The transport unit 2 includes, for example, two pairs of registration rollers 2A and 2B.

(Image forming unit 3)
The image forming unit 3 forms a toner image IMG (see FIG. 2 described later) on the medium PM conveyed from the conveying unit 2. For example, as shown in FIG. 1, the image forming unit 3 includes four image forming units 30Y, 30M, 30C, and 30K. The image forming units 30Y, 30M, 30C, and 30K form toner images (images) IMG of the respective colors using the corresponding toners T of the respective colors, that is, yellow toner, magenta toner, cyan toner, and black toner. is there. For example, the image forming unit 30 is arranged in the order of the image forming unit 30Y, the image forming unit 30M, the image forming unit 30C, and the image forming unit 30K in the transport direction F. In this specification, when the four image forming units 30Y, 30M, 30C, and 30K are not distinguished, they are collectively referred to as an image forming unit 30. Each image forming unit 30 includes, for example, a main body 301, a toner cartridge 302 provided above the main body 301, and a toner conveyance path 303 that connects the main body 301 and the toner cartridge 302. The toner cartridge 302 contains toner T, and the main body 301 forms an image using the toner T supplied from the toner cartridge 302. The toner cartridge 302 is separate from the main body 301 and the toner conveyance path 303 positioned below the toner cartridge 302 and is configured to be detachable from the main body 301 and the toner conveyance path 303. The main body 301, the toner cartridge 302, and the toner conveyance path 303 may be integrally formed. Here, the image forming unit 30 corresponds to a specific example of the “image forming unit” of the invention, and the toner T corresponds to a specific example of the “developer” of the invention.

  FIG. 2 shows a schematic configuration of the main body 301, the toner cartridge 302, and the toner conveyance path 303. FIG. 2 also shows some components of the transfer unit 4. The main body 301 includes a cover 31, a photosensitive drum 32 surrounded by the cover 31, a charging roller 33, a developing roller 35, a supply roller 36, a cleaning blade 37, a waste toner conveying spiral 38, a doctor blade 39, and a toner remaining amount sensor. 40. Further, the main body 301 has an exposure head 34 including an LED (Light Emitting Diode) provided so as to be able to expose the photosensitive drum 32 from the outside of the cover 31. Details of the image forming unit 30 will be described later.

(Transfer part 4)
The transfer unit 4 is also called a transfer belt unit. The transfer unit 4 includes a transfer belt 4A, a driving roller 4B that drives the transfer belt 4A, an idle roller 4C that is a driven roller, and a transfer roller 4D that is disposed to face the photosensitive drum 32 with the transfer belt 4A interposed therebetween. And have. Each of the driving roller 4B and the idle roller 4C is a substantially cylindrical member that can rotate around a rotation shaft portion extending in the width direction W. The transfer unit 4 transports the medium PM transported from the transport unit 2 along the transport direction F, and the toner image IMG formed in each of the image forming units 30Y, 30M, 30C, and 30K on the surface of the medium PM. This is a mechanism for transferring images sequentially.

  The transfer belt 4A is an endless elastic belt made of a resin material such as polyimide resin. The transfer belt 4A is stretched (strung) by a drive roller 4B and an idle roller 4C. The drive roller 4B is rotationally driven in the direction in which the medium PM is conveyed in the conveyance direction F based on the control of the control unit 7, and circulates and rotates the transfer belt 4A. The drive roller 4B is disposed upstream of the image forming units 30Y, 30M, 30C, and 30K. The idle roller 4C adjusts the tension applied to the transfer belt 4A by the urging force of the urging member. The idle roller 4C rotates in the same direction as the drive roller 4B, and is disposed downstream of the image forming units 30Y, 30M, 30C, and 30K.

  The transfer roller 4D rotates in the direction opposite to that of the photosensitive drum 32 to convey the medium PM along the conveyance direction F and transfer the toner image formed in each of the image forming units 30Y, 30M, 30C, and 30K to the medium PM. It is a member for electrostatically transferring onto the top. The transfer roller 4D is made of, for example, a foaming semiconductive elastic rubber material.

(Fixing unit 5)
The fixing unit 5 is a member for fixing the toner image onto the medium PM by applying heat and pressure to the toner image transferred onto the medium PM that has passed through the transfer unit 4. The fixing unit 5 includes, for example, an upper roller 5A and a lower roller 5B.

  Each of the upper roller 5A and the lower roller 5B includes a heat source that is a heater such as a halogen lamp, and functions as a heating roller that applies heat to the toner image on the medium PM. The upper roller 5 </ b> A is controlled to rotate in the direction in which the medium PM is transported in the transport direction F under the control of the control unit 7. The heat sources in the upper roller 5A and the lower roller 5B are supplied with a bias voltage controlled by the control unit 7, and control the surface temperatures of the upper roller 5A and the lower roller 5B. The lower roller 5B is disposed to face the upper roller 5A so that a pressure contact portion is formed between the lower roller 5A and functions as a pressure roller that applies pressure to the toner image on the medium PM. To do. The lower roller 5B may have a surface layer made of an elastic material.

(Discharge unit 6)
The discharge unit 6 discharges the medium PM on which the toner image is fixed by the fixing unit 5 to the outside. The discharge unit 6 includes, for example, transport rollers 6A and 6B. The transport rollers 6A and 6B are configured to discharge the medium PM to the outside through the transport path and store it on the external stacker 100A. The transport rollers 6 </ b> A and 6 </ b> B are configured to rotate in a direction in which the medium PM is transported in the transport direction F under the control of the control unit 7.

[Configuration of Image Forming Unit 30]
Next, the detailed configuration of the image forming unit 30 will be described with reference to FIGS.

(Toner cartridge 302)
FIG. 3 is a perspective view illustrating an appearance and a partial internal configuration of the toner cartridge 302. However, the illustration of the toner T is omitted in FIG. 4A and 4B are perspective views showing the external configuration of the toner cartridge 302. FIG. 4A shows the toner cartridge 302 viewed from the opposite side to FIG. 4B. The toner cartridge 302 has a housing 302A as a specific example of the “container” of the present invention that accommodates the toner T. The housing 302A further accommodates a toner conveying spiral 302B extending in the width direction and a toner stirring member 302C extending in the width direction. The toner conveyance spiral 302B rotates about the axis J1 extending in the width direction, thereby conveying unused toner T contained in the housing 302A of the toner cartridge 302 in the width direction (+ X direction or -X direction). To do. A discharge port 302K is provided in the lower portion of the housing 302A, and the toner T conveyed by the rotation of the toner conveyance spiral 302B is discharged from the discharge port 302K to the main body 301. Therefore, the toner conveyance spiral 302B corresponds to a specific example of the “supply unit” of the invention. Note that a fitting portion 302BT is provided at one end of the toner conveyance spiral 302B, and the toner conveyance spiral 302B and the fitting portion 302BT are integrally rotatable. The fitting portion 302BT is a portion that fits with the gear 52G in the motor driving portion 52B shown in FIGS. 4A and 4B, and the driving force from the motor driving portion 52B is transmitted thereto. The toner agitating member 302C agitates unused toner T accommodated in the housing 302A by rotating around the axis J2 extending in the width direction. The driving force from the motor driving unit 52B is transmitted to the toner stirring member 302C through the fitting portion 302BT. Therefore, the toner stirring member 302C performs the toner T stirring operation in conjunction with the toner T transporting operation in the toner transport spiral 302B.

(Main body 301)
5A to 5C are perspective views showing the appearance of the main body 301. FIG. FIG. 5D is an enlarged view of a portion surrounded by a broken line VD in FIG. 5C. Further, FIG. 5E is a cross-sectional view illustrating the internal configuration of the main body 301. The main body 301 corresponds to a specific example of “main body” of the present invention. A shutter 301A is provided on the upper portion of the cover 31 in the main body 301 so as to be movable along the width direction (X-axis direction). Is exposed. When the toner cartridge 302 is mounted on the main body 301, the discharge port 302K of the housing 302A and the input port 301K of the cover 31 are in communication with each other via the toner conveyance path 303 (FIG. 1). Further, as shown in FIG. 5C, a toner remaining amount detection sensor 40 for detecting the remaining amount of toner T remaining in the main body 301 is provided inside the cover 31. The operation of the remaining toner detection sensor 40 is controlled by a detection control unit 55 described later. The toner remaining amount detection sensor 40 and the detection control unit 55 correspond to a specific example of “detection unit” of the invention.

  FIG. 6A is a perspective view illustrating the entire configuration of the toner remaining amount detection sensor 40, and FIG. 6B is a partially enlarged perspective view illustrating an enlarged main part of the toner remaining amount detection sensor 40. As shown in FIGS. 6A and 6B, the remaining toner detection sensor 40 includes, for example, a shaft 41 having a rotation shaft 41J extending in the width direction, a disk 42, a blade member 43, a locking member 44, and a light emission. It has an element 45, a light receiving element 46, and a waveguide 47. The shaft 41 is configured to rotate around the rotation axis 41J under the control of the detection control unit 55. The disc 42 is a member that is rotatably attached to one end of the shaft 41, is a member that rotates integrally with the blade member 43, for example, in the direction of R40 about the rotation shaft 41J, and is cut out at a part near the outer edge thereof. 42K (FIG. 6B). The blade member 43 is rotatably provided with respect to the shaft 41 so as to surround the periphery of the shaft 41, and has a protrusion 43T in a part thereof. The locking member 44 is a member that is fixed to the outer peripheral surface of the shaft 41 and rotates integrally with the shaft 41 in the direction of R40, for example, around the rotation shaft 41J, and a part of the blade member 43 (for example, the protrusion 43T). Is to lock. The light emitting element 45 is, for example, a light emitting diode (LED), and lights up continuously or intermittently under the control of the detection control unit 55. The light receiving element 46 is an optical sensor that receives light emitted from the light emitting element 45. The waveguide 47 is a transparent body such as a prism that returns the light from the light emitting element 45 by, for example, 180 ° and guides it to the light receiving element 46. Here, the light receiving element 46 and the waveguide 47 are arranged to face each other so as to sandwich the disc 42 in the X-axis direction. The toner remaining amount detection sensor 40 detects the remaining amount of toner T remaining in the main body 301 once per rotation of the shaft 41, for example. That is, the time required for one rotation of the shaft 41 is the detection cycle T1. The detection period T1 corresponds to a specific example of “first period” of the present invention.

  7A and 7B show the detection operation of the toner remaining amount detection sensor 40. FIG. FIG. 7A shows a state in which the notch 42K of the disk 42 is in the upward position and the protrusion 43T of the blade member 43 is in the downward position due to the rotation of the shaft 41. In this case, a notch 42K exists between the light receiving element 46 and the waveguide 47. For this reason, the light LA emitted from the light emitting element 45 passes through the waveguide 47 and is then emitted from the waveguide 47 as light LB. The light LB enters the light receiving element 46 without being blocked by the disc 42. Become. That is, the state of FIG. 7A is a state in which the light receiving element 46 can receive the light LB.

  On the other hand, FIG. 7B shows a state in which the notch 42K of the disc 42 is in the downward position and the protrusion 43T of the blade member 43 is in the upward position due to the rotation of the shaft 41. In this case, the disc 42 exists between the light receiving element 46 and the waveguide 47. For this reason, the light LA emitted from the light emitting element 45 passes through the waveguide 47 and is then emitted from the waveguide 47 as light LB. However, since the light LB is blocked by the disc 42, the light LB is transmitted to the light receiving element 46. Does not enter.

  Next, components other than the toner remaining amount detection sensor 40 in the main body 301 will be described with reference to FIGS. 2 and 5E.

  The photosensitive drum 32 is a cylindrical member capable of carrying an electrostatic latent image on the surface (surface layer portion), and is configured using a photosensitive member (for example, an organic photosensitive member). Specifically, the photosensitive drum 32 has a conductive support and a photoconductive layer covering the outer periphery (surface) thereof. The conductive support is made of, for example, a metal pipe made of aluminum. The photoconductive layer has, for example, a structure in which a charge generation layer and a charge transport layer are sequentially stacked. Under the control of the control unit, the photosensitive drum 32 is rotated at a predetermined peripheral speed in the direction in which the medium PM is transported in the transport direction F (the direction of the arrow R32).

  The charging roller 33 is a member (charging member) that charges the surface (surface layer portion) of the photosensitive drum 32, and is disposed in contact with the surface (circumferential surface) of the photosensitive drum 32. The charging roller 33 has, for example, a metal shaft and a semiconductive rubber layer (for example, a semiconductive epichlorohydrin rubber layer) covering the outer periphery (surface) thereof. The charging roller 33 is controlled by the control unit to rotate in the same direction as the photosensitive drum 32, for example.

  The exposure head 34 is an exposure device that forms an electrostatic latent image on the surface (surface layer portion) of the photosensitive drum 32 by exposing the surface of the photosensitive drum 32. The exposure head 34 has a plurality of LED light emitting units arranged in the width direction W with respect to one photosensitive drum 32. Each LED light emitting unit includes, for example, a light source such as a light emitting diode that emits irradiation light, and a lens array that forms an image of the irradiation light on the surface of the photosensitive drum 32.

  The developing roller 35 is a member that carries on its surface a toner T that develops an electrostatic latent image, and is disposed in contact with the surface (circumferential surface) of the photosensitive drum 32. The developing roller 35 has, for example, a metal shaft and a semiconductive urethane rubber layer covering the outer periphery (surface). The developing roller 35 is controlled by the control unit, and rotates at a predetermined peripheral speed in a direction opposite to the photosensitive drum 32 (direction of arrow R35).

  The supply roller 36 is a member (supply member) for supplying the toner T to the developing roller 35 and is disposed so as to be in contact with the surface (circumferential surface) of the developing roller 35. The supply roller 36 has, for example, a metal shaft and a foamable silicone rubber layer covering the outer periphery (surface) thereof. The supply roller 36 is controlled by the control unit and rotates in a direction opposite to the developing roller 35 (direction of arrow R36).

  The cleaning blade 37 scrapes off the toner T remaining on the surface of the photosensitive drum 32. The cleaning blade 37 is made of, for example, a flexible rubber material or a plastic material.

  The waste toner conveying spiral 38 is, for example, a member in which spiral blades are erected around the shaft, and is a member that rotates in the direction of an arrow R38, for example, under the control of the control unit. The waste toner conveyance spiral 38 functions to convey the toner T scraped off by the cleaning blade 37 in the + X direction, for example, by rotating.

  The doctor blade 39 is a member that regulates the amount of toner T that adheres to the surface of the developing roller 35.

[Control mechanism of image forming apparatus]
FIG. 8 illustrates an example of a control mechanism in the image forming apparatus of the present embodiment. The image forming apparatus further includes, for example, an interface unit 51, motor drive units 52A and 52B, an exposure control unit 53, a high voltage power supply unit 54, and a detection control unit 55.

  The interface unit 51 receives print data from, for example, an external host computer and exchanges various control signals with the host computer.

  The motor drive unit 52A controls the operation of each motor in the image forming apparatus. Accordingly, the motor control unit 52A operates, for example, the medium supply unit 1, the conveyance unit 2, each image forming unit 30, the transfer unit 4, the fixing unit 5, and the discharge unit 6, respectively. However, the operation of the toner conveying spiral 302B for supplying the toner T in each image forming unit 30 may be controlled by the motor driving unit 52B. The motor drive unit 52A is a specific example corresponding to the “first drive source” of the present invention, and the motor drive unit 52B is a specific example corresponding to the “second drive source” of the present invention.

  The exposure control unit 53 controls the exposure operation in each exposure head 34.

  The high-voltage power supply unit 54 applies voltages to the charging roller 33, the developing roller 35, the doctor blade 39, the supply roller 36, and each transfer roller 4D of each image forming unit 30.

  The detection control unit 55 controls the light emission operation of the light emitting element 45 based on an instruction from the control unit 7, and the toner T remaining in the main body 301 of each image forming unit 30 based on the signal D supplied from the light receiving element 46. The amount is to be detected.

[Action / Effect]
(A. Basic operation)
In this image forming apparatus, the toner image is transferred to the medium PM as follows.

  When print image data and a print command are input to the control unit 7 from an external device such as a PC to the activated image forming apparatus, the control unit 7 starts a print operation of the print image data according to the print command. .

  For example, as shown in FIG. 1, the medium PM accommodated in the tray 1A is picked up one by one from the uppermost portion by the pickup roller 1B, and is fed to the downstream conveying portion 2 while the skew is corrected by the feed roller 1C. . Next, the medium PM is conveyed to the image forming unit 3 by the two pairs of registration rollers 2A and 2B. In the image forming unit 3, the toner image IMG is transferred onto the medium PM as follows.

  In the image forming unit 3, each color toner image IMG is formed by the following electrophotographic process in accordance with the print command of the control unit 7. Specifically, the control unit 7 puts the toner T contained in the toner cartridge 302 into the cover 31 of the main body 301 and rotates the photosensitive drum 32 at a constant speed in the direction of arrow R32. Accordingly, the charging roller 33, the developing roller 35, and the supply roller 36 also start rotating in a predetermined direction.

  On the other hand, the control unit 7 applies a predetermined voltage to the charging roller 33 for each color to uniformly charge the surface of the photosensitive drum 32 for each color. Next, the control unit 7 activates the LED head 34 to irradiate the photosensitive drums 32 of the respective colors with light corresponding to the color components of the print image based on the image signal, and to form an electrostatic latent image on the surface of the photosensitive drum 32 of each color. Form each one.

  The toner T is supplied to the developing roller 35 via the supply roller 36 and is carried on the surface of the developing roller 35. The developing roller 35 attaches the toner T to the electrostatic latent image formed on the photosensitive drum 32 to form a toner image IMG. Further, a predetermined voltage is applied to the transfer roller 44 in the transfer unit 4, and an electric field is generated between the photosensitive drum 32 and the transfer roller 44. In this state, when the medium PM runs between the photosensitive drum 32 and the transfer roller 44, the toner image IMG formed on the photosensitive drum 32 is transferred onto the medium PM.

  Thereafter, the toner image IMG on the medium PM is fixed on the medium PM by applying heat and pressure in the fixing unit 5. Finally, the medium PM on which the toner image IMG is fixed by the discharge unit 6 is discharged to a stacker 100A outside the image forming apparatus.

(B. About detection operation of toner remaining amount detection sensor 40 and supply operation of toner T)
Next, the operation of the toner remaining amount detection sensor 40 will be described with reference to FIGS. Hereinafter, a case 1 in which the remaining amount of toner T in the cover 31 is relatively large will be described as case 1, and a case in which the remaining amount of toner T in the cover 31 is relatively small will be described as case 2.

((Case 1))
9A to 9E are schematic views showing a series of operations of the toner remaining amount detection sensor 40 in the case 1, and show a state in which the disc 42 and the like are viewed from the light receiving element 46 in the −X direction. FIG. 10A is an explanatory diagram schematically showing a change with time in the amount of light LB received by the light receiving element 46 in case 1.

  When print image data and a print command are input to the control unit 7 from an external device such as a PC to the activated image forming apparatus, the control unit 7 starts the detection operation of the toner remaining amount detection sensor 40. Specifically, the motor for the toner remaining amount detection sensor 40 provided in the image forming apparatus is driven by the motor drive unit 52A, and the shaft 41 is rotated in the direction of the arrow R40 at a constant speed, for example, and the detection control unit. The light emitting element 45 is turned on by 55. As the shaft 41 rotates, the locking member 44 rotates together with the shaft 41. Further, since part of the blade member 43 (for example, the protrusion 43T) is locked by the locking member 44, as shown in FIG. 9A, the blade member 43 and the circle until the protrusion 43T reaches a position immediately above. The plate 42 also rotates integrally with the shaft 41 in the direction of the arrow R40. In the state of FIG. 9A, the light LB is blocked by the disc 42 and does not enter the light receiving element 46. When the shaft 41 further rotates and the projection 43T exceeds the position directly above the shaft 41, the projection 43T falls away from the locking member 44 by its own weight as shown in FIG. 9B. That is, the blade member 43 and the disc 42 do not follow the shaft 41 but rotate alone in the direction of the arrow R40 at a speed faster than the rotation speed of the locking member 44. The rotation of the blade member 43 and the disk 42 is temporarily stopped at the position where the protrusion 43T contacts the surface TS of the accumulated toner T. Even in the state of FIG. 9B, the light LB is blocked by the disc 42 and does not enter the light receiving element 46. After that, the rotation of the blade member 43 and the disk 42 is stopped until the locking member 44 rotates and catches up with the protrusion 43T. Since the remaining amount of the toner T is relatively large, the notch 42K of the disk 42 is buried in the toner T at most positions. For example, when the protrusion 43T of the blade member 43 reaches a position below the shaft 41, The notch 42K is exposed from the toner T. 9C, after the locking member 44 rotates in the direction of the arrow R40 from the state shown in FIG. 9B and catches up with the protrusion 43T, the shaft 41, the disc 42, and the blade member 43 are further integrated into the direction of the arrow R40. This shows a state in which a part of the notch 42K is exposed above the surface TS of the toner T by rotating in the direction. In the state of FIG. 9C, a part of the periphery of the notch 42K overlaps with the light LB traveling in the + X direction. For this reason, although a part of the light LB is blocked by the disk 42, another part of the light LB passes through the notch 42K and enters the light receiving element 46. Further, when rotating in the direction of the arrow R40 from the state shown in FIG. 9C, as shown in FIG. It becomes. Further, when rotating in the direction of the arrow R40 from the state shown in FIG. 9D, a part of the disc 42 comes to a position corresponding to the light LB as shown in FIG. 9E. In the state of FIG. 9E, as in the state of FIG. 9C, a part of the periphery of the notch 42K overlaps the light LB traveling in the + X direction. For this reason, a part of the light LB is blocked by the disk 42, and another part of the light LB passes through the notch 42K and enters the light receiving element 46.

  FIG. 10A is a time chart showing a change in the amount of light received by the light receiving element 46 in Case 1. FIG. In FIG. 10A, symbol T1 represents a rotation cycle of the shaft 41, that is, a detection cycle of the remaining amount of toner T by the toner remaining amount detection sensor 40, and symbol t1 represents a light shielding period in which the light receiving element 46 does not receive the light LB. t2 represents a light receiving period t2 in which the light receiving element 46 receives the light LB. As shown in FIG. 10A, the light receiving element 46 is shielded from light during most of the light shielding period t1 in the detection cycle T1, and the light receiving period t2 is small. In FIG. 10A, symbols P9A to P9E represent timings corresponding to the states of FIGS. 9A to 9E, respectively.

  Based on the signal D (FIG. 8) supplied from the light receiving element 46, the detection control unit 55 calculates, for example, that the ratio of the light receiving period t2 to the detection cycle T1 is equal to or less than a reference value, and the toner T in the main body 301. It is determined that the remaining amount is sufficient. In that case, the toner transport spiral 302B does not rotate, and the toner T is not supplied from the toner cartridge 302 to the main body 301. On the other hand, if the detection control unit 55 calculates that the ratio of the light receiving period t2 to the detection cycle T1 exceeds the reference value based on the signal D supplied from the light receiving element 46, the remaining amount of toner T in the main body 301 is not sufficient. Judge that it is enough. If so, the toner conveying spiral 302B is rotated by the motor driving unit 52B, and the toner T is supplied from the toner cartridge 302 to the main body 301. At that time, the control unit 7 performs the supply operation by the toner conveying spiral 302B so as to adjust the supply amount of the toner T per detection cycle T1 (for example, the supply amount of the toner T per detection cycle T1 becomes constant). Control. Specifically, for example, the control unit 7 adjusts the supply amount of the toner T per unit time by changing the rotation speed of the toner conveyance spiral 302B, and changes the operation time for performing the rotation operation of the toner conveyance spiral 302B. Thus, the supply time for supplying the toner T can be adjusted.

  The upper part of FIG. 11A represents a time chart as an example of the signal D from the toner remaining amount detection sensor 40, and the lower part of FIG. 11A represents a time chart as an example of the operation of the motor driving unit 52B that drives the toner conveyance spiral 302B. Represents. The upper part of FIG. 11A shows that the light receiving period t2 is in the on state and the light shielding period t1 is in the off state. The lower part of FIG. 11A shows the drive period t3 during which the motor drive unit 52B is driving as the on state and the stop period t4 when the motor drive unit 52B is stopped as the off state. Further, a lower symbol T2 in FIG. 11A represents a supply cycle of the supply of the toner T by the toner conveyance spiral 302B accompanying the rotation of the motor driving unit 52B. As shown in FIG. 11A, the detection cycle T1 of the toner remaining amount detection sensor 40 and the supply cycle T2 of the toner T supply by the toner transport spiral 302B accompanying the rotation of the motor driving unit 52B are synchronized with each other. Here, the supply of the toner T by the toner cartridge 302 to the main body 301 is performed once every detection period T1 in the example of FIG. 11A. At that time, the supply amount V of toner T is supplied to the main body 301 every detection cycle T1. In the example of FIG. 11A, the supply amount V of toner T is supplied to the main body 301 during the drive period t3 by one supply operation for each detection cycle T1. The supply cycle T2 corresponds to a specific example of “second cycle” of the present invention.

  Here, the driving period t3 and the light receiving period t2 do not need to coincide with each other. For example, as shown in the upper part of FIG. 11B, when the printing speed is 1/3 of FIG. 11A, the detection cycle T1 is tripled. Accordingly, the light receiving period t2 also becomes longer. However, even in this case, as shown in the lower part of FIG. 11B, the supply operation of the toner T by the toner cartridge 302 is supplied during the driving period t3 having the same length as the lower part of FIG. 11A regardless of the slow printing speed. An amount V of toner T may be supplied to the main body 301. In the example of FIG. 11B, the start time of the light receiving period t2 and the start time of the drive period t3 are made to coincide with each other, but they may be made different.

  In the example of FIGS. 11A and 11B, the detection cycle T1 and the supply cycle T2 are made to coincide with each other. However, in this embodiment, the supply cycle T2 is set to 1 / n (n is a natural number) times the detection cycle T1. Also good. That is, as shown in FIG. 11C, the toner T supply operation per detection period T1 may be divided into a plurality of times. However, even in this case, the total supply amount of toner T per detection cycle T1 is set to V (V = V1 + V2 +... + Vn).

  Further, the control unit 7 controls the main unit 301 via the motor driving unit 52 </ b> A and detects the remaining toner amount detection sensor 40 so that the detection cycle T <b> 1 varies according to the image formation speed in the main unit 301. It is good to control the operation. This is because an appropriate amount of toner T can be supplied to the main body 301 at an appropriate timing in accordance with the printing speed, that is, depending on the amount of toner T used per hour. Further, it is desirable that the control unit 7 independently controls the adjustment of the supply amount of the toner T per detection cycle T1 in the toner conveyance spiral 302B and the adjustment of the image forming speed in the main body unit 301. That is, it is desirable to control the motor drive unit 52A and the motor drive unit 52B independently. Regardless of the driving speed of the photosensitive drum 32 or the like in the main body 301, the toner conveying spiral 302B can be rotated at a constant speed, for example, so that a general-purpose motor can be used as the motor driving section 52B. As a result, the toner T can be stably supplied to the main body 301 easily.

((Case 2))
12A and 12B are schematic diagrams illustrating a series of operations of the toner remaining amount detection sensor 40 in Case 2. FIG. FIG. 10B is an explanatory view schematically showing a change with time of the amount of light LB received by the light receiving element 46 in case 1.

  As in the case 1, when the control unit 7 starts the detection operation of the toner remaining amount detection sensor 40, the locking member 44 rotates integrally with the shaft 41 as the shaft 41 rotates. Since part of the blade member 43 (for example, the protrusion 43T) is locked by the locking member 44, as shown in FIG. 12A, the blade member 43 and the disc 42 until the protrusion 43T reaches a position immediately above. Also rotates integrally with the shaft 41 in the direction of the arrow R40. In the state of FIG. 12A, the light LB is blocked by the disc 42 and does not enter the light receiving element 46. When the shaft 41 further rotates and the protrusion 43T exceeds the position directly above the shaft 41, the protrusion 43T falls away from the locking member 44 by its own weight as shown in FIG. 12B. That is, the blade member 43 and the disc 42 do not follow the shaft 41 but rotate alone in the direction of the arrow R40 at a speed faster than the rotation speed of the locking member 44. The rotation of the blade member 43 and the disk 42 is temporarily stopped at the position where the protrusion 43T contacts the surface TS of the accumulated toner T. In the state of FIG. 12B, since the notch 42K exists at a position corresponding to the traveling direction of the light LB, the light LB enters the light receiving element 46 without being blocked by the disk 42. After that, the rotation of the blade member 43 and the disk 42 is stopped until the locking member 44 rotates and catches up with the protrusion 43T. Accordingly, the light receiving element 46 receives the light LB from the state of FIG. 12B until the locking member 44 catches up with the protrusion 43T. The behavior after the locking member 44 rotates and catches up with the protrusion 43T from the state of FIG.

  FIG. 10B is a time chart showing a change in the amount of light received by the light receiving element 46 in Case 2. Each symbol in FIG. 10B is the same as what is meant in FIG. 10A. As shown in FIG. 10B, unlike case 1, in case 2, the light receiving period t2 in which the light receiving element 46 receives the light LB is significantly increased, while the light shielding period t1 is significantly decreased. In FIG. 10B, reference numerals P12A and P12B represent timings corresponding to the states of FIGS. 12A and 12B, respectively.

  In Case 2, since the ratio of the light receiving period t2 to the detection cycle T1 exceeds the reference value based on the signal D supplied from the light receiving element 46, the detection control unit 55 has an insufficient remaining amount of toner T in the main body 301. Judge that there is. Therefore, the control unit 7 rotates the toner conveying spiral 302B by the motor driving unit 52B and supplies the toner T from the toner cartridge 302 to the main body unit 301. The toner T supply operation in this case is performed in the same manner as in the case 1. That is, the control unit 7 controls the supply operation by the toner conveyance spiral 302B so as to adjust the supply amount of the toner T per detection cycle T1 (for example, the supply amount of the toner T per detection cycle T1 is constant). To do. The supply of the toner T by the toner cartridge 302 may be performed once every detection cycle T1, or may be performed a plurality of times every detection cycle T1.

(C. Effects of the image forming apparatus)
As described above, in the present exemplary embodiment, in each image forming unit 30, the remaining amount of toner T in the main body 301 is detected for each detection cycle T1 by the toner remaining amount detection sensor 40, and toner T per detection cycle T1 The amount of supply was adjusted. For this reason, in the main body 301, a state where the supply amount of the toner T is insufficient or a state where the supply amount of the toner T is excessive is easily avoided. Therefore, an appropriate amount of toner T is supplied from the toner cartridge 302 to the main body 301, and printing density is insufficient (blurred printed image), printing density unevenness in the same medium PM, or so-called fogging. It is possible to prevent toner from adhering to a non-printing area and form a good toner image IMG.

  On the other hand, if the remaining amount of toner is only detected, and the amount of toner supply per detection cycle is not adjusted appropriately, for example, depending on the printing speed, the supply amount may be insufficient (developer supply amount of developer). There is a risk that the amount may not catch up) or an excessive supply amount (a state where a developer exceeding the amount of developer used is supplied excessively). If the toner supply amount is insufficient, the printing operation cannot be performed in the first place. In addition, when the amount of toner supply is excessive, the physical properties of the toner existing in the main body may be biased, which may impair the quality of the printed toner image. Therefore, the toner quality distribution can be relaxed by extending the time for stirring the toner in the main body, but the preparation time until the start of printing increases, which hinders rapid printing operation. . Therefore, in the present embodiment, the supply amount of the toner T per detection cycle T1 is adjusted so as to avoid a state where the supply amount is insufficient or a state where the supply amount is excessive, so that the above problem can be solved.

<2. Modification>
Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to these embodiments and the like, and various modifications are possible. For example, in the above-described embodiment, an image forming apparatus that forms a color image has been described. However, the present invention is not limited to this. For example, an image forming apparatus that forms a monochrome image by transferring only a black toner image. There may be. In the above embodiment, the primary transfer type image forming apparatus has been described. However, the present invention can also be applied to a secondary transfer type.

  The series of processes described in the above embodiments may be performed by hardware (circuit), or may be performed by software (program). When performed by software, the software is composed of a group of programs for causing each function to be executed by a computer. Each program may be used by being incorporated in advance in the computer, for example, or may be used by being installed in the computer from a network or a recording medium.

  In the above-described embodiment and the like, an LED head using a light emitting diode as a light source is used as the exposure device. However, for example, an exposure device using a laser element or the like as a light source may be used.

  Furthermore, in the above-described embodiment and the like, an image forming apparatus having a printing function has been described as a specific example of the “image forming apparatus” in the present invention. That is, in addition to such a printing function, for example, the present invention can also be applied to an image forming apparatus that functions as a multifunction peripheral having a scanning function and a fax function.

  DESCRIPTION OF SYMBOLS 1 ... Medium supply part, 1A ... Tray, 1B ... Pickup roller, 1C ... Feed roller, 2 ... Conveyance part, 2A, 2B ... Registration roller pair, 3 ... Image formation part, 30 (30Y, 30M, 30C, 30K) ... Image forming unit 301... Main body 302. Toner cartridge 303 303 Toner transport path 31 Cover 31 32 Photosensitive drum 33 33 Charging roller 34 Exposure head 35 Developing roller 36 Supply roller 37 ... Cleaning blade, 38 ... Waste toner conveying spiral, 39 ... Doctor blade, 40 ... Toner level sensor, 41 ... Shaft, 42 ... Disc, 43 ... Blade member, 44 ... Locking member, 45 ... Light emitting element, 46 ... Light receiving element, 47 ... waveguide, 4 ... transfer section, 4A ... transfer belt, 4B ... drive roller, 4C ... idle roller, 4D ... transfer roller, 5 Fixing portion, 6 ... discharge unit, 7 ... controller, 100 ... housing, PM ... medium.

Claims (7)

A container for containing a developer;
A main body for forming an image using the developer supplied from the container;
A detection unit for detecting the remaining amount of the developer in the main body for each first period;
A supply unit for supplying the developer from the container to the main body;
The main body and the detection unit are controlled so that the first period varies according to the image forming speed in the main body, and the supply amount of the developer per the first period is constant. the image forming unit and a control unit for controlling the supply portion. A first drive unit, and a second drive unit independent of the first drive unit,
The controller is
By controlling the first drive unit, adjusting the image forming speed in the main body unit and detecting the remaining amount of the developer in the detection unit,
The supply amount of the developer in the supply unit is adjusted by controlling the second drive unit.
The image forming unit according to claim 1 . The control unit makes the driving time of the second driving unit constant regardless of a change in the image forming speed in the main body unit.
The image forming unit according to claim 2. The supply unit supplies the developer by one or more supply operations every second period that is 1 / n (n is a natural number) times the first period.
The image forming unit according to claim 1. Wherein the control unit, the supply amount of the developer per unit time and any one of the preceding claims 1 to control the supply unit so as to adjust said supply time for supplying the developer The image forming unit described in 1. The main body is
A developer carrying member carrying the developer;
The image forming unit according to any one of claims 1 to 5 , further comprising: an image carrier including a photosensitive layer that carries a latent image on a surface thereof. Image forming apparatus having an image forming unit according to any one of claims 6 claim 1.

Images