JP5233856B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention provides a copying machine, a printer, a facsimile machine, or the like that forms an electrostatic latent image on an electrostatic latent image carrier by an electrophotographic method or an electrostatic recording method, and develops the toner image to develop a toner image. In particular, the present invention relates to an image forming apparatus such as a multifunction peripheral in which two or more of them are combined, and particularly relates to a developing device.

  An image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination machine combining two or more of these, which forms an electrostatic latent image on an electrostatic latent image carrier and develops it to form a toner image. Various types of developing devices are known, and the following are among them.

  A developer carrying rotator for applying toner to an electrostatic latent image corresponding to a target image formed on the electrostatic latent image carrier of the image forming apparatus, and facing the developer carrying rotator for development. A buffer unit that holds the developer, a first rotary transport body that is disposed in the buffer unit and that is rotationally driven to transport the developer in the direction of the rotation axis, and is disposed above the first rotary transport body, The developing device includes a second rotary transport body that transports the developer in the direction of the rotation axis when rotated and in the direction opposite to the first rotary transport body.

  In this type of developing device, the developer is allowed to move from the developer sending side end of the second rotating transport body to the developer feeding side end of the first rotating transport body and the developer sending of the first rotating transport body. The developer is stirred and circulated by the first and second rotary conveyance bodies while allowing the developer to move from the side end portion to the developer feeding side end portion of the second rotary conveyance pair, and the developer from the first rotary conveyance body. The developer can be supplied to the carrying rotor side. Hereinafter, this type of developing device may be referred to as a “developer circulation type developing device”.

  In the developer circulation type developing device, a partition member is provided between the first rotating transport body and the second rotating transport body, and the developer of the first rotating transport body from the developer sending side end of the second rotating transport body. The developer movement to the feeding side end is performed through the first opening formed in the partition member, and the developer feeding side of the second rotating conveyance pair from the developer sending side end of the first rotating conveyance body. In general, the developer moves to the end through a second opening formed in the partition member.

  A developer supplying rotator for supplying the developer to the developer carrying rotator may be disposed in the buffer unit.

  In developing devices that develop electrostatic latent images and form toner images, including the developer circulation type developing device, the amount of developer in the device decreases over time, so the amount of developer in the device is detected. A developing device is known in which toner can be replenished when the amount of developer decreases from a predetermined amount.

  For example, in the developing devices described in JP-A-2006-11226 and JP-A-2006-184711, in terms of the developer circulation type developing device, the toner is supplied to the first rotary conveyance body and the electrostatic latent image carrier. A developer amount detection device is provided in a buffer unit in which a developer carrying rotator to be supplied is disposed.

JP 2006-11226 A JP 2006-184711 A

  However, according to the developing devices described in JP-A-2006-11226 and JP-A-2006-184711, the developer amount detection device controls the amount of developer through a light-transmitting developer detection window provided in the buffer unit. An optical sensor for detection and a cleaning device for cleaning the inner surface of the detection window are included, and the configuration of the portion including the detection device is complicated in combination with the portion where the detection device is provided.

  Further, in the developing device described in Japanese Patent Application Laid-Open No. 2006-11226, the developer replenishing port is separated from the detecting device, and the response of the detecting device to the developer replenishment is likely to be shifted, so that excess developer is replenished. There was something that would end up.

  In the developing device described in Japanese Patent Application Laid-Open No. 2006-184711, the cleaning device for cleaning the inner surface of the detection window constituting the detection device is located near the extension line of the rotation shaft of the lower first rotary conveyance body. , Because the rotating carrier cannot be installed in a certain area of the detection device, the developer circulation is deteriorated by that amount, and the developer whose fluidity is deteriorated thereby accumulates, causing image noise, and a large variation in the detection of the developer amount. I was doing.

  In addition, in the developing device described in Japanese Patent Application Laid-Open No. 2006-184711, since the space around the developer amount detection device is narrow, the optical sensor that detects the developer amount is actually separated from the detection window through the detection window. The light from the detection window must be guided to the sensor by the light guide member, which may reduce the detection sensitivity, complicate the configuration of the part including the detection device, and increase the cost. Was.

  SUMMARY OF THE INVENTION A first object of the present invention is to provide a developer circulation type developing device used for developing an electrostatic latent image in an image forming apparatus, and capable of detecting a developer amount easily and inexpensively with high accuracy. Let it be an issue.

  Here, as described above, the “developer circulation type developing device” refers to a developer carrying rotator that imparts toner to an electrostatic latent image, and a buffer that holds the developer that faces the developer carrying rotator and is used for development. And a first rotary transport body that is disposed in the buffer section and is rotationally driven to transport the developer in the direction of the rotational axis, and is disposed on the upper side of the first rotational transport body and is rotationally driven. A second rotary transport body that transports the developer in a direction of the rotation axis and in a direction opposite to the first rotary transport body, wherein the first and second rotary transport bodies include the second rotary transport body. The developer is allowed to move from the developer delivery side end of the rotary carrier to the developer delivery side end of the first rotary carrier, and from the developer delivery side end of the first rotary carrier. The developer is stirred and circulated while allowing the developer to move to the developer feeding side end of the rotating carrier. A developing device capable of supplying the developer to said developer carrying rotor side from the first rotary transfer member.

  The present invention also provides an image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image. The second problem is to provide an image forming apparatus that can detect the amount of developer in the developing device easily and inexpensively with high accuracy and can form a good image as much as possible in at least one developing device. .

In order to solve the above problems, the present invention provides the following developing device and image forming apparatus.
(1) Developing device A developing device used for developing an electrostatic latent image in an image forming apparatus capable of forming an electrostatic latent image on an electrostatic latent image carrier and developing the electrostatic latent image to form a toner image.
A developer carrying rotator for applying toner to the electrostatic latent image;
A buffer unit that holds the developer that faces the developer carrying rotor and is used for development;
A first rotary transport body that is disposed in the buffer unit and that is rotationally driven to transport the developer in the rotational axis direction;
A second rotary transport body that is disposed on the upper side of the first rotary transport body and is driven to rotate in the direction of the rotation axis and in the opposite direction to the first rotary transport body;
A developer reservoir,
A developer amount detection device,
The first and second rotary transport bodies allow the developer to move from the developer delivery side end of the second rotary transport body to the developer feed side end of the first rotary transport body and the first rotary transport body. The developer is stirred and circulated while allowing the developer to move from the developer delivery side end of the one-rotation conveyance body to the developer delivery-side end of the second rotation conveyance body, and the development from the first rotation conveyance body is performed. Can be supplied to the agent-carrying rotor
The first and second rotary transport bodies include a developer delivery side end portion of the first rotary transport body and a developer feed side end portion of the second rotary transport body located above the end portion. Extending to the outside of the developer carrying rotator in the direction of the axis of rotation of the developer carrying rotator,
The developer reservoir is continuously provided above the extension of the second rotary transport body;
The developer amount detector includes a translucent detection window for detecting the developer amount in the developer reservoir, and a developer amount detection sensor for detecting the developer amount in the developer reservoir through the detection window. And a cleaning body that holds the cleaning member and rubs and cleans the inner surface of the detection window with the cleaning member. The developer transport capability of the first rotating transport body is the developer transport of the second transport rotating body. Development device larger than the capacity.

(2) Image forming apparatus An image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image. An image forming apparatus in which at least one developing device is a developing device according to the present invention.

  According to the developing device of the present invention, the developer reservoir is continuously provided above the developer feeding side end of the second rotary transport body in the developer transport direction of the upper second rotary transport body. In addition, a certain amount of developer required for the electrostatic latent image developing operation can be transported to the second rotary transport body, while a larger amount of developer can be retained in the developer reservoir. In other words, a certain amount of developer required for the electrostatic latent image developing operation can be transported to the second rotary transport body in a state where the developer is retained in the developer reservoir.

  Then, the lower first rotating transport body is equivalent to the amount of developer supplied from the developer sending side end of the upper second rotating transport body to the developer feeding side end of the first rotating transport body. The developer circulation is balanced when the developer is conveyed.

  At this time, since the developer transport capability of the first rotary transport body is greater than that of the second rotary transport body, the upper second rotary transport body transports the amount of developer required for the developing operation and the first rotational transport. And the first rotary transport body transports the developer in an amount equal to the amount of developer supplied from the second rotary transport body, so that a gap is formed above the first rotary transport body in the buffer unit. It is possible to adjust the amount of developer in the developing device so that By doing so, the developer amount required for the electrostatic latent image developing operation can be stably supplied to the developer-carrying rotating body in a state where the increase in the developer powder pressure is suppressed, and as a result, the electrostatic latent image can be satisfactorily improved. The image can be developed.

  When the developer is consumed by the developing operation, the developer upper surface in the buffer portion in which the first rotation conveyance body is disposed is lowered by the consumed amount, and the developer movement amount from the first rotation conveyance body to the second rotation conveyance body Is lowered, and the developer circulation amount is decreased to cause poor supply of the developer to the developer-carrying rotating body. However, the developer is located above the developer feeding side end of the second rotating transport body. Since there is a reservoir, the second rotary transport body supplies the developer amount necessary for development to the first rotary transport body side, so that the developer amount in the buffer section is maintained at the amount required for development, and as a result, the developer supply Generation of image noise due to defects is suppressed.

  When the amount of the developer in the developing device becomes insufficient, the developer pool and the developer to the developer carrying rotator are utilized by utilizing the developer reservoir that is less affected by the presence of the first and second rotary transport members. The supply of toner consumed for development can be easily performed on the developer reservoir without disturbing the supply.

  According to the developing device of the present invention, the developer amount detection device in the development device is provided in the developer reservoir, and the detection device transmits light for detecting the developer amount in the developer reservoir. A property detection window, a developer amount detection sensor for detecting the amount of developer in the developer reservoir through the detection window, and a cleaning body that holds the cleaning member and rubs and cleans the inner surface of the detection window with the cleaning member. Therefore, the developer amount in the developer reservoir can be accurately detected by the developer amount detection sensor while cleaning the inner surface of the detection window with the cleaning member.

  Since this developer amount detecting device is provided using a developer reservoir that is less affected by the presence of the first and second rotary transporters, it can be provided as easily and inexpensively as it is.

  Further, as described above, when the amount of the developer in the developing device becomes insufficient, the toner can be replenished to the developer reservoir, and by doing so, the developer circulation and the developer carrying rotator can be supplied. The toner consumed for development can be easily replenished without hindering the supply of the developer, but the toner replenishment portion and the developer amount detection device can be provided in the vicinity in this way, Responsiveness to toner replenishment of the developer amount detection device is improved, the developer amount can be detected with high accuracy, and the toner can be replenished in a state where the excess or deficiency is suppressed. The amount of developer inside can be made constant and stabilized.

  In order to more accurately detect the developer amount by the developer detection device, the developer to be detected by the developer amount detection sensor of the detection device when the developer in the development device is not yet short is supplied to the detection window. In order to make it exist more reliably, the said cleaning body may further be equipped with the developer holding member. The developer holding member has an opening facing the second rotary conveyance body, and the developer is placed at the front end on the opposite side of the cleaning member in the reciprocating direction of the cleaning member with the opening therebetween. It has a hugging part for hugging.

  Further, in order to detect the developer amount with higher accuracy, the developer to be detected by the developer amount detection sensor is smoothly directed to the level of the sensor at the portion of the second rotary conveyance body facing the developer holding member. A paddle for moving up and down may be provided.

  The developing device according to the present invention may be either one using a so-called one-component developer mainly composed of toner or one using a two-component developer mainly composed of toner and carrier.

  In the developing device according to the present invention, a partition member can be provided between the first rotary transport body and the second rotary transport body, and at least from the developer delivery side end of the second rotary transport body to the partition member. A first opening that allows the developer to move to the developer feed side end of the first rotary carrier, and a developer feed side of the second rotary carrier from the developer feed side end of the first rotary carrier A second opening that allows the developer to move to the end can be provided.

  In addition, a developer supplying rotator for supplying the developer to the developer carrying rotator can be disposed in the buffer portion according to the type of developer to be used. The developer supply rotator contacts and rotates with the developer carrying rotator, and scrapes the developer that is not consumed but returned to the buffer unit by being transported to the developer carrying rotator from the developer carrying rotator. At the same time, the developer may be supplied to the developer carrying rotor.

  The developing device according to the present invention includes a developer regulating member that regulates or further charges the amount of developer conveyed to the developing area where the electrostatic latent image is developed according to the type of developer used. Can do.

  The developing device according to the present invention may include a static eliminating device that eliminates charge from the developer that is not consumed and is returned to the buffer unit without being consumed, depending on the type of developer to be used. .

  Examples of the first and second rotary transport bodies in the developing device according to the present invention include a screw transport member having a spiral blade provided around the rotation shaft as a representative example, but is not limited thereto. As long as the developer can be conveyed, it may be in a paddle shape or other shapes.

  In the image forming apparatus according to the present invention, since at least one developing device is the developing device according to the present invention, the developing device can easily and inexpensively detect the amount of developer in the developing device, As a result, a suitable image can be formed by supplying an appropriate amount of developer.

  As described above, according to the present invention, there is provided a developer circulation type developing device used for electrostatic latent image development in an image forming apparatus, which can detect the amount of developer easily and inexpensively with high accuracy. can do.

  According to the present invention, there is also provided an image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image. Thus, in at least one developing device, it is possible to provide an image forming apparatus that can detect the amount of developer in the developing device easily and inexpensively with high accuracy, and thus can form a good image.

1 is a diagram schematically illustrating a configuration of an example of an image forming apparatus according to the present invention. FIG. 2 is a diagram illustrating an outline of a cross-sectional structure of an example of a developing device according to the present invention in the image forming apparatus of FIG. 1. FIG. 3 is a diagram schematically showing the developing device shown in FIG. 2 as viewed from the right side in FIG. 2, but the developing roller and the supply roller are only indicated by their broken lines. It is a figure which shows roughly the structure of a developer pool part and a developer amount detection apparatus seeing from upper direction. 5A shows a state in which the amount of developer is substantially sufficient in the developing device shown in FIGS. 2 and 3, and FIG. 5B shows that the developer is consumed in the developing device shown in FIGS. It shows a state where the dosage is decreasing. FIGS. 6A to 6C are views showing the relationship between the developer in the developer reservoir, the position of the detection window cleaning body, and the developer holding member provided thereon. FIG. 7A is a perspective view of the developer amount detection window cleaning body shown in FIG. 3 and the like and a developer holding member combined therewith, and FIG. 7B shows another example of the developer holding member. It is a perspective view. FIG. 4 is a diagram illustrating a schematic configuration of a reference example developing device in which a developer holding member is not provided on a cleaning body of a developer amount detection window in the developing device illustrated in FIG. 3. It is a figure which shows schematically the structure of the developer pool part and developer amount detection apparatus in the developing device of FIG. 8 seeing from upper direction. It is a figure explaining the difficulty of the developer amount detection apparatus shown in FIG.8 and FIG.9.

Hereinafter, an example of an image forming apparatus according to the present invention and a developing device used therein will be described with reference to the drawings.
FIG. 1 schematically shows the configuration of an example 100 of an image forming apparatus. The image forming apparatus 100 is a tandem type full color printer.

  The printer 100 includes an endless intermediate transfer belt 7 wound around a driving roller 71 and a roller 72 facing the driving roller 71. The transfer belt 7 is rotated in the counterclockwise direction (arrow direction in the figure) CCW by a driving roller 71 driven by a belt driving unit (not shown).

  A cleaning device 73 that cleans secondary transfer residual toner and the like on the transfer belt 7 faces the roller 72, and a secondary transfer roller 8 faces the drive roller 71. The toner or the like collected by the cleaning device 73 is sent to a waste container by a conveying means (not shown).

  The surface layer portion of the secondary transfer roller 8 is formed of an elastic material, and is pressed against a portion of the intermediate transfer belt 7 supported by the driving roller 71 by a pressing unit (not shown), so that a nip is formed between the secondary transfer roller 8 and the intermediate transfer belt 7. And can be rotated by being driven or driven by the movement of the recording medium S fed into the nip as will be described later. A secondary transfer bias can be applied to the secondary transfer roller 8 from a power supply (not shown).

  A fixing device 9 is disposed above the intermediate transfer belt 7 and the secondary transfer roller 8, a timing roller pair 11 is disposed below, and a recording medium S such as recording paper is accommodated below the fixing device 9. The recording medium storage cassette 10 is disposed.

The fixing device 9 includes a fixing heating roller having a heat source such as a halogen lamp heater and a pressure roller pressed against the fixing heating roller.
The recording medium S accommodated in the recording medium accommodating cassette 10 can be pulled out one by one by the medium supply roller 101 and supplied to the timing roller pair 11.

  Between the rollers 71 and 72 around which the intermediate transfer belt 7 is wound, the yellow image forming unit Y, the magenta image forming unit M, and the cyan image forming unit C are arranged along the transfer belt 7 from the roller 72 toward the roller 71. And the black image forming portion K are arranged in this order.

  Each of the image forming units Y, M, C, and K includes a drum-type photosensitive member 1 as an electrostatic latent image carrier, and a charger 2, an exposure device 3, a developing device 4 and the like around the photosensitive member. The cleaning devices 5 are arranged in this order.

  A primary transfer roller 6 is disposed opposite to the photoreceptor 1 of each image forming unit with a belt 7 therebetween. The primary transfer roller 6 is pressed in the direction of the photosensitive member 1 by a pressing unit (not shown), contacts the belt 7 and rotates in a driven manner, and can bring the belt 7 into contact with the photosensitive member 1.

  A primary transfer bias for primary transfer of the toner image formed on the photoreceptor 1 to the belt 7 can be applied to the primary transfer roller 6 from a power supply (not shown).

  The exposure device 3 can perform image exposure by dot (point) exposure on the photosensitive member 1 by blinking of a laser beam in accordance with image information provided from a personal computer (not shown), an image reading device, or the like.

  The photoconductor 1 in each image forming unit is a negatively chargeable photoconductor here, and can be driven to rotate clockwise in the drawing by a photoconductor drive motor (not shown).

  The charger 2 in each image forming unit is a scorotron charger in this example, and a charging voltage is applied from a power supply (not shown) at a predetermined timing. The charger 2 may be one using a charging roller.

  In this example, the developing device 4 in each image forming unit applies a developing bias to an electrostatic latent image formed on the photoreceptor 1 using a one-component developer mainly composed of toner from a power supply (not shown). The developer carrying rotating body (hereinafter referred to as “developing roller”) 41 (see FIG. 2) in the form of a roller can be used for reversal development. The developing device 4 will be further described later.

According to this printer, an image can be formed using one or more of Y, M, C, and K image forming units.
Taking a case where a full color image is formed using all of the image forming portions Y, M, C, and K as an example, first, a yellow toner image is formed in the yellow image forming portion Y, and this is formed on the transfer belt 7 as a primary. Transcript.

  That is, in the yellow image forming portion Y, the photosensitive member 1 is rotationally driven in the clockwise direction in the drawing, and the surface is uniformly charged to a predetermined potential by the charger 2, and the exposure device 3 corresponds to the yellow image in the charged area. Thus, an electrostatic latent image corresponding to the yellow image is formed on the photoreceptor 1. This electrostatic latent image is developed by a developing roller 41 to which a developing bias of the developing device 4 having yellow toner is applied, and becomes a visible yellow toner image. The yellow toner image is primarily transferred onto the transfer belt 7 by the primary transfer roller 6. At this time, a primary transfer bias is applied to the primary transfer roller 6 from a power supply (not shown).

  Similarly, a magenta toner image is formed in the magenta image forming unit M and transferred to the transfer belt 7. A cyan toner image is formed in the cyan image forming unit C and transferred to the transfer belt 7. In the black image forming unit K. A black toner image is formed and transferred to the transfer belt 7.

Yellow, magenta, cyan, and black toner images are formed at a timing when these toner images are transferred onto the intermediate transfer belt 7 in an overlapping manner.
Thus, the multiple toner image formed on the transfer belt 7 moves toward the secondary transfer roller 8 by the rotation of the transfer belt 7.

  On the other hand, the recording medium S is pulled out from the recording medium accommodation cassette 10 by the medium supply roller 101 and is supplied to the timing roller pair 11 and is on standby.

  Thus, the recording medium S waiting at the timing roller pair 11 is supplied to the nip portion between the transfer belt 7 and the secondary transfer roller 8 in accordance with the multiple toner image sent by the intermediate transfer belt 7. . The multiple toner image is secondarily transferred onto the recording medium S by a secondary transfer roller 8 to which a secondary transfer bias is applied from a power supply (not shown).

  Thereafter, the recording medium S is passed through the fixing device 9 where the multiple toner images are fixed on the recording medium S under heat and pressure. The recording medium S is continuously discharged to the discharge tray 13 by the discharge roller pair 12.

  In the primary transfer of the toner image to the belt 7, transfer residual toner or the like remaining on the photoreceptor 1 is cleaned by the cleaning device 5, and secondary transfer residual toner or the like remaining on the belt 7 by the secondary transfer is cleaned by the cleaning device 73. It is cleaned with. Each of these cleaned and removed toners is sent to a waste container by a conveying means (not shown).

  Although the image is formed as described above, the developing device 4 will be further described. The developing device 4 is shown in FIG. 2, FIG. 3, FIG. 5 and the like, and is an example of the developing device according to the present invention.

  FIG. 2 schematically shows a cross-sectional structure of the developing device 4. FIG. 3 schematically shows the developing device 4 as viewed from the right in FIG. 2, but the developing roller 41 and the supply roller 42 are only indicated by their positions with broken lines.

The developing device 4 includes a developing roller 41 and a supply roller 42 that supplies developer to the developing roller 41. The supply roller 42 is an example of a developer supply rotating body.
The developing roller 41 has a conductive rubber layer to which a roughening agent is added and is provided around a metal shaft. However, the developing roller 41 may be made of an aluminum pipe whose surface is blasted.
Here, the supply roller 42 is a metal shaft provided with an elastic polyurethane foam layer around it.

  The developing device 4 also includes a first rotary transport body 46 and a second rotary transport body 47 that supply the developer with stirring to the supply roller 42 side. Here, each of the first and second rotary transport bodies is a screw transport member in which screw blades (spiral blades) are provided around the rotation shaft.

  The developing roller 41, the supply roller 42, and the first and second screw conveying members 46 and 47 are accommodated in the developing device housing 40, and are rotatably supported by the housing. A part of the developing roller 41 protrudes outside the housing 40 so as to face the photoreceptor 1 when the developing device 4 is mounted on the image forming apparatus 100. The conveying members 46 and 47 are accommodated in the developing device housing 40.

  In the housing 40, there is formed a buffer 43 that holds a developer (toner T in this example) (see FIG. 5) for development and faces the supply roller 42 and the development roller 41.

  The first screw conveying member 46 is disposed in the buffer unit 43 above the supply roller 42 and at a position behind the roller 42. The second screw conveying member 47 is disposed above the first screw conveying member 46 and above the supply roller 42 with a plate-like partition member 48 therebetween.

  The first screw conveying member 46 is arranged in parallel with the developing roller 41, and the second screw conveying member 47 is arranged in parallel with the first screw conveying member 46 with the partition member 48 in between.

  The first screw conveying member 46 is rotationally driven by a rotation driving unit (not shown), so that the developer can be conveyed in the rotation axis direction from the right side to the left side in FIG. By being rotationally driven by a rotational drive unit (not shown), the developer can be conveyed in the direction of the rotational axis from the left side to the right side in FIG.

  As the first and second screw conveying members 46 and 47 are driven to rotate as described above, the developer is developed on the right side in FIG. The developer feeding side end (developer feeding side end) is conveyed to the left developer sending side end (developer sending side end), and the left side end of the partition member 48 from the developer sending side end. Through the opening (second opening) 482 of the second conveying member 47, the second conveying member 47 moves upward to the developer feeding side end, and is further conveyed by the second conveying member 47 toward the developer sending side end. From the delivery side end portion, the partition member 48 passes through the opening portion (first opening portion) 481 at the right end portion of the partition member 48 and drops and moves to the developer feeding side end portion of the first conveying member 46 while being assisted by gravity. . In this way, the developer is supplied to the supply roller 42 and, consequently, the developing roller 41 side from the first transport member 46 while being stirred and circulated by the first and second transport members 46 and 47.

  As can be seen from FIG. 3, in order to facilitate such a circulating movement of the developer, the developer transport side end of the first transport member 46 has an original developer transport direction (see FIG. A reverse spiral spiral blade portion 460 that pushes the developer slightly in the direction from right to left in FIG. 5 is formed, and the original developer conveyance of the conveyance member 47 is provided at the developer delivery side end of the second conveyance member 47. A reverse winding spiral blade portion 471 is formed to push back the developer slightly in the direction (left to right in the figure).

  The developing roller 41 and the supply roller 42 are driven to rotate counterclockwise in FIG. 2 by a rotation driving unit (not shown). Accordingly, at the nip portion where the rollers 41 and 42 face each other, both roller surfaces move in opposite directions. As a result, the supply roller 42 scrapes off the developer that returns to the developing device housing 40 without being consumed by the development from the development roller 41 and supplies the developer to the development roller 41 anew.

  When the developer thus supplied passes through the blade-shaped developer regulating member 44 that is in contact with the developing roller 41, the amount of the developer is properly regulated and charged, and the developer faces the photoreceptor 1. It is used for developing the electrostatic latent image on the photoreceptor 1 in the developing area (toner is applied to the electrostatic latent image). The developer that has not been consumed by the development returns to the case 40 as the developing roller 41 rotates. At this time, the developer is neutralized by a neutralization member 45 to which a neutralization bias is applied from a neutralization power supply (not shown) in order to facilitate scraping of the development roller 41 by the supply roller 42.

As a noteworthy point of the developing device 4,
(1) The developer conveying ability of the first screw conveying member 46 is larger than that of the second screw conveying member 47,
(2) The first and second screw conveying members 46 and 47 rotate the developing roller 41 at the developer feeding side end of the conveying member 46 and the developer feeding side end of the conveying member 47 located above the first and second screw conveying members 46 and 47. The developer extends to the outside of the developing roller 41 in the axial direction, and a developer reservoir 49 is provided above the extended portion of the second conveying member 47, and
(3) The developer amount detecting device TS is provided in the developer reservoir 49.

  Although not limited thereto, in this example, the first screw conveying member 46 has a rotating shaft diameter of 3.5 mm, an outer diameter of 8 mm, and a screw lead of 15 mm. The second screw conveying member 47 has a rotating shaft diameter of 3.5 mm, an outer diameter of 8 mm, and a screw lead of 8 mm. Both conveying members are rotated at 200 revolutions per minute by a driving unit (not shown). The conveyance member 46 has a conveyance capacity about twice that of the conveyance member 47. The screw lead of the spiral blade (screw) portion facing the developer reservoir 49 in the second conveying member 47 is slightly larger than 8 mm and 10 mm in order to make the developer easily rise to the developer amount detection window dw described later. is there.

  Although not limited thereto, in this example, in the longitudinal direction of the developing device 4 in FIG. 3, the development reservoir 49 is about 50 mm, the portion between the developer reservoir 49 and the buffer 43 is about 40 mm, and the buffer 43 Is about 230 mm to 320 mm, and the length of the developing roller 41 in the longitudinal direction is about 220 mm to 310 mm.

In FIG. 3, for example, a transparent resin (for example, polystyrene) for detecting the amount of developer (here, the upper surface position of the developer in the reservoir) on each of the front and back walls facing each other of the developer reservoir 49. ), A translucent detection window dw.
When the developer reservoir 49 is formed of a transparent material such as transparent polystyrene resin, a part of the developer reservoir 49 can be used as a detection window.

  Here, the detection window dw constitutes a part of the developer amount detection device TS for detecting the developer amount in the developing device 4. The detection device TS further includes a developer amount detection sensor that detects the amount of developer in the developer reservoir 49 through the detection window dw.

  In this example, the developer amount detection sensor is a light transmission type optical developer detection sensor having a light emitting element s1 and a light receiving element s2. The light emitting element s1 faces one detection window dw from the outside, and the light receiving element s2 faces the other detection window dw from the outside. When the light receiving element s2 receives a predetermined amount of light from the light emitting element s1, it is determined that the amount of developer in the developing device 4 is insufficient, and the light from the light emitting element s1 is blocked by the developer, so that the light receiving element s2 has a predetermined amount. If the light is not received, it is determined that the developer amount is sufficient. As shown in FIG. 3, a toner replenishing portion TB can be detachably attached to the developer reservoir 49. When the detection device TS detects an insufficient amount of developer, the toner replenishing portion TB receives toner. Can be replenished.

  The developer amount detection device TS further includes a cleaning body 51. As shown also in FIG. 4, the cleaning body 51 includes a main body member 510 having cleaning members 511 on both sides for rubbing and cleaning the inner surface of the detection window dw in conjunction with the rotation of the second transport member 47 by an unillustrated interlocking mechanism. The conveying member 47 reciprocates in the direction of the rotation axis. In relation to the operation, action, and the like of the cleaning member 511, the inner surface of the detection window dw may be subjected to a coating process for at least one of preventing developer adhesion, preventing charging, and improving wear resistance. .

  As shown in FIG. 4, the main body member 510 is a member having a rectangular groove shape with a tip opened when viewed from above. The cleaning member 511 is made of a flexible elastic foam material (for example, foamed urethane rubber) in this example, but is a flexible sheet that protrudes from the side surface of the main body member 510 and rubs against the detection window. (For example, PET sheet: polyethylene terephthalate sheet) may be used.

  The cleaning body 51 is further provided with a developer holding member 52 as shown in FIG. The holding member 52 includes a pair of spaced apart arm portions 521 that provide an opening facing the second conveying member 47 and a developer holding portion 522 held at the tip of the arm portion. The opening provided by the arm portion 521 communicates with the groove-shaped opening portion 510 a opened to the second transport member 47 of the main body member 510.

  The arm portion 521 protrudes from the distal end and upper end portion of the main body member 510 of the cleaning body, and the hugging portion 522 projects from the distal ends of the pair of arm portions, turns downward while being curved, and is further straightened. It is in the form of a plate extending downward. The holding unit may be a flat plate-shaped member 523 shown in FIG. 7B, or the like, as long as it can hold the developer to the developer detection window dw.

  In any case, the developer holding member 52 may be formed integrally with the cleaning body 51 or may be provided later on the cleaning body 51. For example, the arm member 521 may be formed integrally with the main body member 510 of the cleaning body, or may be formed later. The developer holding portion 522 (523, etc.) may be formed integrally with the arm portion 521 or may be formed later.

  Further, in order to detect the developer amount by the detection device TS with higher accuracy, the development to be detected by the developer amount detection sensor (s1, s2) at the site of the second screw conveying member 47 facing the developer holding member 52. A paddle 472 is also provided to smoothly move the agent up and down toward the sensor level.

  As described above, in the developing device 4, the developer reservoir 49 is continuously provided above the developer feeding side end of the conveying member in the main developer conveying direction of the upper second screw conveying member 47. The second conveying member 47 conveys a certain amount of developer T required for the developing operation of the electrostatic latent image on the photoreceptor 1, while a larger amount of developer stays in the developer reservoir 49. I can leave it to you. In other words, a certain amount of developer T required for the electrostatic latent image developing operation can be transported to the second transport member 47 in a state where the developer T is retained in the developer reservoir 49.

  Then, the lower first conveying member 46 supplies an amount of developer equivalent to the amount of developer supplied from the developer delivery side end of the upper second conveying member 47 through the first opening 481 of the partition member 48. A balance of developer circulation can be achieved at the time of conveyance.

  At this time, since the developer transport capability of the first transport member 46 is greater than that of the second transport member 47, the upper second transport member 47 transports the developer amount required for the electrostatic latent image developing operation. The first transport member 47 transports the developer in an amount equal to the amount of developer supplied from the second transport member 47 and the first transport member 47 transports the first transport member 46 to the first transport member 46. It is possible to adjust the amount of developer in the developing device so that a gap is formed above the member 46. Here, the amount of developer T in the device 4 is adjusted in this way (FIG. 5A). reference). Thus, the developer amount required for the electrostatic latent image developing operation can be stably supplied to the developing roller 41 in a state where the increase in the developer powder pressure is suppressed, and the electrostatic latent image can be developed as well.

  When the developer is consumed by the developing operation, the upper surface of the developer T in the buffer 43 having the first transport member 46 is lowered by the consumed amount (FIG. 5B). 2 The amount of developer movement to the conveying member 47 is reduced, thereby reducing the amount of developer circulation and causing a failure in supplying the developer to the developing roller 41, but the developer conveying side of the second conveying member 47 There is a developer reservoir 49 above the end, and the second conveying member 47 supplies the developer amount necessary for development to the first conveying member 46, so that the amount of developer in the buffer 43 is required for development. The amount of image noise that would occur if there was a poor supply of developer to the developing roller 41 is suppressed.

  When the amount of developer in the developing device 4 is insufficient, the developer pool 49 and the developing roller 41 are used by utilizing the developer reservoir 49 that is less affected by the presence of the first and second transport members 46 and 47. The toner consumed for development can be easily supplied to the developer reservoir 49 without hindering the supply of the developer.

  According to the developing device 4, the developer amount detection device TS in the development device is provided in the developer reservoir 49, and the detection device TS transmits light for detecting the developer amount in the developer reservoir 49. And a developer amount detection sensor (s1, s2) that detects the developer amount in the developer reservoir through the detection window dw, and a cleaning member 511 that holds the inner surface of the detection window dw. Therefore, the cleaning member 511 cleans the inner surface of the detection window dw with the cleaning member 511, and the developer amount in the developer reservoir is detected by the developer amount detection sensors (s1, s2). Thus, the amount of developer in the developing device 4 can be detected with high accuracy.

  In the developing device 4, the developer holding member 52 is provided on the cleaning body 51. However, if the developer holding member 52 is not provided as shown in FIGS. 8 and 9, as shown in FIG. In addition, as the cleaning body 51 reciprocates, the developer T may be pressed against the wall 491 on the downstream side in the developer transport direction of the developer reservoir 49 to be in the aggregated state T ′. When the toner particles agglomerate, the movement of the developer in the developer reservoir 49 deteriorates, and the amount of developer detected through the detection window dw varies. In order to solve this problem, the distance between the cleaning body 51 and the wall 491 at the most advanced position may be increased. However, this increases the size of the developing device 4.

  However, in the developing device 4, as described above, the developer holding member 52 is provided in the cleaning body 51, so that the developer can be held in the holding member 52 as shown in FIGS. 6A and 6B. Since it is easy to enter the opening provided by the pair of arm portions 521 and the developer that has entered is easily moved toward the detection window dw by the holding portion 522, the development in the developer reservoir 49 is performed. Aggregation of the agent hardly occurs, and the developer to be detected by the sensor can face the detection window dw, so that the amount of the developer can be detected more accurately. 6A and 6B show a state where the developer reaches the detection window dw and the amount of the developer is sufficient, and FIG. 6C shows that the developer reaches the detection window dw. In other words, the developer amount is insufficient. As described above, when the amount of the developer is insufficient, the toner is supplied to the developer reservoir 49.

  The developing device 4 is further provided with the paddle 472 at a portion of the second conveying member 47 facing the developer holding member 52, and the developer to be detected by the developer amount detection sensors (s1, s2). Since the level can be smoothly moved upward and downward, the developer amount can be detected with higher accuracy in this respect.

  In any case, since the developer amount detection device TS is provided using the developer reservoir 49 that is less affected by the presence of the first and second transport members 46 and 47, the developer amount detection device TS is provided simply and inexpensively. be able to.

  Further, as described above, when the amount of developer in the developing device becomes insufficient, the toner can be replenished to the developer reservoir 49, so that the developer circulation and development to the developing roller 41 can be performed. The toner consumed for development can be easily replenished without hindering the supply of the developer, but the toner replenishment portion and the developer amount detection device TS can be provided in this manner, and by doing so, Responsiveness to the toner replenishment of the developer amount detection device TS is improved, the developer amount can be detected with high accuracy, and the toner can be replenished in a state where excess or deficiency is suppressed, and further development The developer amount in the apparatus 4 can be made constant and stabilized.

  Since the printer 100 employs the developing device 4 described above as the developing device, each developing device 4 can detect the amount of developer in the developing device easily and inexpensively with high accuracy. A good image can be formed by supplying an appropriate amount.

  The image forming apparatus described with reference to FIG. 1 is a tandem type full-color printer 100. However, the present invention can also be applied to a monochrome image forming apparatus, and also to other types of multicolor image forming apparatuses. it can. Further, in an image forming apparatus provided with a plurality of developing devices, the present invention may be applied only to a smaller number of developing devices than the total number of the developing devices.

  The present invention provides a developing device that can detect the amount of developer in the developing device easily and inexpensively with high accuracy, and thus can appropriately supply the developer so as to form a good image, and so on. By providing such a developing device, the present invention can be used to provide an image forming apparatus that can form a good image.

DESCRIPTION OF SYMBOLS 100 Printer Y Yellow image formation part M Magenta image formation part C Cyan image formation part K Black image formation part 1 Photoconductor 2 Charger 3 Image exposure apparatus 4 Developing apparatus 40 Developing apparatus housing 41 Developing roller 42 Developer supply roller 43 Buffer part 44 Developer regulating member 45 Static elimination member 46 First screw conveying member 460 Reverse-winding spiral blade portion 47 Second screw conveying member 470 A portion where the screw lead is slightly large 471 Reverse-winding spiral blade portion 472 Paddle 48 Partition members 481, 482 Developer of partition member Distribution opening 49 Developer reservoir TS Developer amount detection device s1 Light emitting element s2 Light receiving element dw Detection window 51 Cleaning body 510 Main body member 510a of cleaning body Groove opening 511 of main body member Cleaning member 52 Developer holding member 521 Arm 522, 523 Developer embrace TB toner replenishing section 5 cleaning device 6 primary transfer roller 7 intermediate transfer belt 71 driving roller 72 counter roller 73 cleaning device 8 secondary transfer roller 9 fixing device 10 recording medium supply cassette 101 recording medium supply roller 11 timing roller pair 12 recording medium Discharge roller pair 13 Recording medium discharge tray S Recording medium T Developer

Claims (4)

A developing device used for electrostatic latent image development in an image forming apparatus capable of forming an electrostatic latent image on an electrostatic latent image carrier and developing the electrostatic latent image to form a toner image;
A developer carrying rotator for applying toner to the electrostatic latent image;
A buffer unit that holds the developer that faces the developer carrying rotor and is used for development;
A first rotary transport body that is disposed in the buffer unit and that is rotationally driven to transport the developer in the rotational axis direction;
A second rotary transport body that is disposed on the upper side of the first rotary transport body and is driven to rotate in the direction of the rotation axis and in the opposite direction to the first rotary transport body;
A developer reservoir,
A developer amount detection device,
The first and second rotary transport bodies allow the developer to move from the developer delivery side end of the second rotary transport body to the developer feed side end of the first rotary transport body and the first rotary transport body. The developer is stirred and circulated while allowing the developer to move from the developer delivery side end of the one-rotation conveyance body to the developer delivery-side end of the second rotation conveyance body, and the development from the first rotation conveyance body is performed. Can be supplied to the agent-carrying rotor
The first and second rotating transport bodies are at the developer sending side end of the first rotating transport body and the developer feeding side end of the second rotating transport body located above the end, Extending to the outside of the developer carrying rotator in the direction of the axis of rotation of the developer carrying rotator,
The developer reservoir is continuously provided above the extension of the second rotary transport body;
The developer amount detection device includes a translucent detection window for detecting the developer amount in the developer reservoir, and a developer amount detection sensor for detecting the developer amount in the developer reservoir through the detection window. And a cleaning member that holds the cleaning member and rubs and cleans the inner surface of the detection window with the cleaning member. The developer conveying ability of the first rotating conveying member is the developer conveying ability of the second conveying rotating member. Larger developing device.   The cleaning body reciprocates in the direction of the rotation axis of the second rotary transport body and rubs and cleans the inner surface of the detection window with the cleaning member. The cleaning body further includes a developer holding member. The member has an opening opposed to the second rotary conveyance body, and holds the developer to the detection window at the tip end opposite to the cleaning member in the reciprocating direction of the cleaning body with the opening therebetween. The developing device according to claim 1, further comprising:   3. The developing device according to claim 2, wherein a paddle for lifting and transporting the developer to the developer reservoir is provided at a portion of the second rotary transport body facing the developer holding member.   An image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image, at least one developing device An image forming apparatus comprising the developing device according to claim 1.

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