Patent Application
20170031269
This application claims priority under 35 USC 119 to Japanese Patent Application No. 2015-147588 filed on Jul. 27, 2015, the entire contents which are incorporated herein by reference.
This invention relates to a development device, an image forming unit, and an image forming apparatus.
In general, used in an image forming apparatus such as a printer, a facsimile machine, and a multifunction peripheral (MFP) is a developer amount detection device that detects the amount of a toner as a developer contained in a development device. For example, proposed is a developer amount detection device that detects the amount of a toner inside a development device by using the rotation time (cycle) of a rotating part (stirring bar) of the developer amount detection device that changes according to the amount of the toner inside the development device (for example, see Patent Document 1).
[Patent Document 1] Unexamined Japanese Patent Application 2012-53348
However, depending on the state of the developer inside the development device, the developer could adhere onto a rotating part of the developer amount detection device, thereby disabling an appropriate detection of the amount of the developer inside the development device. In this case, the amount of the developer inside the development device could not be appropriately maintained, inducing deterioration in print quality.
Then, the objective of this invention is to suppress deterioration in print quality by appropriately maintaining the amount of the developer inside the development device.
A development device disclosed in the application includes a developer accommodating part that accommodates a developer, a developer detection member that is rotatably supported inside the developer accommodating part and is for detecting an amount of the developer accommodated inside the developer accommodating part, a rotational drive member that rotates the developer detection member around an rotational axis, and a conductive contact member that is formed of a conducive material. Wherein, defining a rotary track through which the developer detection member passes while rotating, a free edge of the contact member is arranged within the rotary track such that the contact member comes in contact with the developer detection member once while the developer detection member makes one rotation, the free edge being distal from where the contact member is fixed.
An image forming unit disclosed in the application includes the development device discussed above, and an image carrier to which the developer is supplied from the development device.
An image forming apparatus disclosed in the application is provided with the image forming unit discussed above.
According to this invention, deterioration in print quality can be suppressed by appropriately maintaining the amount of the developer inside the development device.
<Structure of image forming apparatus 100>
The image forming apparatus 100 comprises image forming units 1K, 1Y, 1M, and 1C that form images on a medium 15 such as a sheet of paper. The image forming apparatus 100 can perform color printing by an electrophotographic system using toners as developers in black color (K), yellow color (Y), magenta color (M), and cyan color (C). Specifically, the image forming units 1K, 1Y, 1M, and 1C form images on the medium 15 using black color, yellow color, magenta color, and cyan color.
Also, the image forming apparatus 100 comprises exposure heads 2K, 2Y, 2M, and 2C as exposure parts, a tray 3, a medium carrying path 4, a sheet feeding roller 5, a carrying roller 6, a transfer belt unit 7, a fuser 8, ejection rollers 9 and 10, a stacker cover 11, toner cartridges 12K, 12Y, 12M, and 12C as developer cartridges, a control part 13, and a drive part 14. The image forming units 1K, 1Y, 1M, and 1C, the sheet feeding roller 5, the carrying roller 6, the transfer belt unit 7, the fuser 8, and the ejection rollers 9 and 10 are disposed along the medium carrying path 4.
The exposure heads 2K, 2Y, 2M, and 2C are provided so as to oppose the image forming units 1K, 1Y, 1M, and 1C, respectively. The exposure heads 2K, 2Y, 2M, and 2C form electrostatic latent images based on image data by irradiating image carriers inside the image forming units 1K, 1Y, 1M, and 1C with light (for example, laser light), respectively.
The tray 3 accommodates the medium 15. The medium 15 is carried by the sheet feeding roller 5 and the carrying roller 6 toward the image forming units 1K, 1Y, 1M, and 1C.
The medium carrying path 4 is a carrying path where the medium 15 is carried.
The sheet feeding roller 5 is provided in a connecting part between the tray 3 and the medium carrying path 4 and forwards the medium 15 from the tray 3.
The carrying roller 6 is provided on the medium carrying path 4 and carries the medium 15 forwarded by the sheet feeding roller 5.
The transfer belt unit 7 comprises a transfer belt 7a that is an endless belt, a drive roller 7b, a driven roller 7d, and transfer rollers 7k, 7y, 7m, and 7c. The transfer belt 7a forms part of the medium carrying path 4 and carries the medium 15. The drive roller 7b rotates by a drive force from the drive part 14 and has the transfer belt 7a rotate. The driven roller 7d is rotatable and movably supports the transfer belt 7a. The transfer rollers 7k, 7y, 7m, and 7c transfer images formed in the image forming units 1K, 1Y, 1M, and 1C to the medium 15, respectively.
The fuser 8 comprises a heat application roller 8a and a pressure application roller 8b. The fuser 8 has images transferred onto the medium 15 fused to the medium 15 using the heat application roller 8a and the pressure application roller 8b.
The ejection rollers 9 and 10 carry the medium 15 and eject the medium 15 to the outside of the image forming apparatus 100.
The stacker cover 11 holds the medium 15 ejected by the ejection rollers 9 and 10.
The toner cartridges 12K, 12Y, 12M, and 12C are detachably provided to the image forming apparatus 100 and stores toners to replenish the image forming units 1K, 1Y, 1M, and 1C, respectively. Also, stored in the toner cartridges 12K, 12Y, 12M, and 12C are toners used by the image forming units 1K, 1Y, 1M, and 1C, respectively. For example, stored in the toner cartridges 12K, 12Y, 12M, and 12C are toners in black color, yellow color, magenta color, and cyan color, respectively.
The control part 13 controls individual components inside the image forming apparatus 100. The drive part 14 comprises a drive force generation part such as a motor, and a drive force transmission mechanism (such as a gear) that transmits the drive force to the individual components inside the image forming apparatus 100.
Next, explained are the structures of the image forming units 1K, 1Y, 1M, and 1C, and the structures of the toner cartridges 12K, 12Y, 12M, and 12C. Note that because the image forming units 1K, 1Y, 1M, and 1C have the same structure with one another, the structure of the image forming unit 1K is explained as the representative structure of the image forming units 1K, 1Y, 1M, and 1C. Also, because the toner cartridges 12K, 12Y, 12M, and 12C have the same structure with one another, the structure of the toner cartridge 12K is explained as the representative structure of the toner cartridges 12K, 12Y, 12M, and 12C.
The toner cartridge 12K comprises a replenishing toner receiving region 12a, a waste toner receiving region 12b, a stirring member 12c, and an opening 12d (first opening). Stored in the replenishing toner receiving region 12a is a toner Ta (replenishing toner) for replenishing the image forming unit 1K. Stored in the waste toner receiving region 12b is a used waste toner Tb. The stirring member 12c is rotatably supported within the replenishing toner receiving region 12a and stirs the stored toner Ta by rotating. The opening 12d forms a toner supply port 16 for replenishing the image forming unit 1K with the toner Ta.
The image forming unit 1K comprises a photosensitive drum 20 as an image carrier, a charging device 30 that charges the surface of the photosensitive drum 20, a development device 50 that supplies the toner Ta to the surface of the photosensitive drum 20, and a cleaning device 40 that cleans the surface of the photosensitive drum 20.
The photosensitive drum 20 rotates in the direction of an arrow R20 by receiving a drive force from the drive part 14.
The charging device 30 comprises a charging roller 31 and a cleaning roller 32. The charging roller 31 is controlled by the control part 13, and a charging bias is applied to it. The charging device 30 charges the surface of the photosensitive drum 20 by having the charging roller 31 to which the charging bias is applied contact with the surface of the photosensitive drum 20. The cleaning roller 32 cleans the surface of the charging roller 31 by rotating in contact with the surface of the charging roller 31.
The cleaning device 40 comprises a cleaning blade 41 and a waste toner carrying member 42. The cleaning device 40 cleans the surface of the photosensitive drum 20 by having the tip of the cleaning blade 41 contact with the surface of the photosensitive drum 20. The waste toner carrying member 42 is disposed below the cleaning blade 41 and carries the waste toner Tb scraped off the surface of the photosensitive drum 20 toward the waste toner receiving region 12b.
The development device 50 comprises a toner accommodating part 51 as a developer accommodating part that accommodates the toner Ta, the toner amount detection member 52 (rotational body) as a developer detection member, a rotational drive member 70 (rotational member) that rotates the toner amount detection member 52, and the contact member 53 that contacts with the toner amount detection member 52.
Also, the development device 50 comprises stirring members 54a and 54b that stir the toner Ta accommodated in the toner accommodating part 51, a development roller 55 (also called “toner carrier”) as a developer carrier, a toner supply roller 56 that supplies the toner Ta to the development roller 55, a development blade 57 for thinning the toner Ta supplied to the development roller 55, a supporting member 58 that supports the contact member 53 and the development blade 57, and an opening 59 (second opening). The development roller 55 rotates in the direction of an arrow R55. The toner supply roller 56 rotates in the direction of an arrow R56.
The opening 59 forms the toner supply port 16 for replenishment of the toner Ta from the toner cartridge 12K. The image forming unit 1K (specifically, the development device 50) and the toner cartridge 12K are connected via the toner supply port 16.
The toner amount detection member 52 is used for detecting the amount of the toner Ta accommodated inside the toner accommodating part 51. The toner amount detection member 52 is rotatably supported inside the toner accommodating part 51.
As shown in
As shown in
The contact member 53 is configured of a film having conductivity (conductive film) and electrically grounded via the supporting member 58 or the like for example. The contact member 53 should desirably have flexibility. Specifically, the contact member 53 should desirably be a plastic film containing carbon (for example, carbon black). In this embodiment, used as the contact member 53 is a plastic film of 0.125 mm in thickness and 80 mΩ in area resistance value (surface resistance). However, although a plastic film of 80 mΩ in area resistance value is used as the contact member 53 in this embodiment, the area resistance value of the contact member 53 only needs to be 80 mΩ or lower.
As shown in
The development roller 55 is disposed so as to contact with the surface of the photosensitive drum 20. The development roller 55 is controlled by the control part 13, and a development bias is applied to it. The development device 50 supplies a toner to the surface of the photosensitive drum 20 by having the development roller 55, to which the development bias is applied, contact with the surface of the photosensitive drum 20. The development blade 57 is disposed so as to contact with the surface of the development roller 55.
Next, the structures of the toner amount detection member 52 and its surroundings are explained.
The toner amount detection member 52 is connected to the supporting member 60. The toner amount detection member 52 is rotatably supported in one unit with the supporting member 60 inside the toner accommodating part 51. The supporting member 60 comprises a protrusion 60a (first protrusion).
The rotational drive member 70 as a drive source of the toner amount detection member 52 is fitted around the supporting member 60. The toner amount detection member 52 rotates in correspondence with a rotation of the rotational drive member 70. The rotational drive member 70 comprises a protrusion 70a (second protrusion) that engages with the protrusion 60a of the supporting member 60. The protrusion 70a is formed in a semi-cylindrical shape. The protrusion 70a rotates around the rotation center 60X of the supporting member 60 with a constant speed.
The reflective plate 80 is connected to the tip part of the supporting member 60. In a position opposing the reflective plate 80, a sensor 90 is provided. The sensor 90 is provided on the inner wall of the chassis of the image forming apparatus 100 for example. However, the sensor 90 may be provided on the inner wall of the toner accommodating part 51. The sensor 90 comprises a light emitting part 90a and a light receiving part 90b. The sensor 90 emits light from the light emitting part 90a and detects the position of the toner amount detection member 52. Specifically, the position of the toner amount detection member 52 is detected by light emitted from the light emitting part 90a reaching the reflective plate 80, and the light receiving part 90b receiving light reflected by the reflective plate 80 (reflected light).
<Operations of the image forming apparatus 100> Upon receiving a print command from a host such as a computer, the control part 13 issues print operation commands to individual components. The medium 15 is separated into single pieces by the sheet feeding roller 5 and carried to the image forming units 1K, 1Y, 1M, and 1C by the carrying roller 6. When color printing is executed, toner images are formed on image carries of the individual image forming units 1K, 1Y, 1M, and 1C, and the toner images are transferred onto the medium 15 by the transfer rollers 7k, 7y, 7m, and 7c. The medium 15, to which the toner images are transferred, has the toner images fused by the fuser 8. The medium 15 having the toner images fused is ejected by the ejection rollers 9 and 10 to the stacker cover 11.
Next, explained is a development process in the individual image forming units. However, because the image forming units 1K, 1Y, 1M, and 1C have the same basic operations with one another, the operations of the image forming unit 1K are explained as the representative operation example of the image forming units 1K, 1Y, 1M, and 1C.
Upon receiving a print command from a host device such as a computer, the control part 13 has the toner supply roller 56 rotated by the drive part 14. As shown in
The surface of the photosensitive drum 20 is charged by the charging roller 31. The exposure head 2K irradiates the surface of the charged photosensitive drum 20 with light (for example, laser light) based on image data to form an electrostatic latent image on the photosensitive drum 20. By the toner Ta being supplied from the development roller 55 onto the photosensitive drum 20 where the electrostatic latent image is formed, a toner image is formed on the photosensitive drum 20. The toner image formed on the photosensitive drum 20 is transferred to the medium 15 by the transfer roller 7k.
The toner Ta remaining on the photosensitive drum 20 without being transferred to the medium 15 is scraped off by the cleaning blade 41. The toner Ta scraped off by the cleaning blade 41 is carried by the waste toner carrying member 42 and stored in the waste toner receiving region 12b.
By rotating, the stirring member 12c inside the replenishing toner receiving region 12a stirs the toner Ta inside the replenishing toner receiving region 12a and supplies the toner Ta into the toner accommodating part 51.
Nest, explained is a toner amount detection process.
The toner amount detection member 52 rotates in the direction of an arrow R52 so as to go through the track T52 by receiving a drive force from the drive part 14.
In this embodiment, the tip part of the contact member 53 (specifically, the free edge 53a or distal edge) is positioned inside a shaded region Al in
The rotational drive member 70 continues to rotate receiving a drive force from the drive part 14 even after the toner amount detection member 52 reached the lowest point P1 from the highest point P2 (fell by its self weight). By the rotational drive member 70 continuing to rotate, once the protrusion 70a of the rotational drive member 70 and the protrusion 60a of the supporting member 60 engage again, as shown in
As shown in
As shown in
As shown in
Also, even if the toner Ta is compressed inside the toner accommodating part 51, by the operation of the contact member 53 energetically returning from the warped state to the original position, the toner Ta inside the toner accommodating part 51 is stirred. That is, because the contact member 53 has a function to stir the toner Ta in the track T52 of the toner amount detection member 52, occurrences of voids in the track T52 (that is, a state where the toner Ta is not present in the track T52) can be prevented. By preventing the occurrences of voids in the track T52, the rotation operation of the toner amount detection member 52 can be appropriately maintained, preventing misdetections by the sensor 90. In this invention, the free edge 53a of the contact member 53 is arranged within the track T52 from the side view.
Also, because the contact member 53 is conductive and electrically grounded, once the toner amount detection member 52 contacts with the contact member 53, the toner amount detection member 52 is electrically grounded via the contact member 53. Even if the toner amount detection member 52 is charged, because the toner amount detection member 52 is neutralized when the toner amount detection member 52 contacts with the contact member 53, electrical adhesion of the toner Ta to the toner amount detection member 52 can be suppressed.
As shown in
On the other hand, as shown in
When the toner amount detection member 52 is positioned at the lowest point P1, the reflective plate 80 opposes the sensor 90 (specifically, the light emitting part 90a and the light receiving part 90b). When the reflective plate 80 and the sensor 90 oppose each other, once the sensor 90 emits light from the light emitting part 90a, light from the sensor 90 is reflected by the reflective plate 80. Light reflected by the reflective plate 80 (reflected light) is received by the light receiving part 90b of the sensor 90, and the position of the toner amount detection member 52 is detected.
(a) and (b) of
As shown in (a) of
As show in (b) of
As explained above, according to Embodiment 1, by the toner amount detection member 52 contacting with the conductive contact member 53, physical or electrical agglomeration of the toner Ta to the toner amount detection member 52 can be suppressed, and toner amount detection accuracy using the toner amount detection member 52 can be appropriately maintained. By the amount of the toner Ta inside the development device 50 being maintained appropriately, deterioration in print quality by the image forming apparatus 100 can be suppressed.
Because the contact member 53 has flexibility, it warps when contacting with the toner amount detection member 52, and when the contact member 53 returns from the warped state to the original position, the contact member 53 can strongly scrape off the toner Ta adhering to the toner amount detection member 52.
By separating from the contact member 53 before reaching the highest point P2 after starting a rotation from the lowest point P1, the toner amount detection member 52 never has its self-weight fall operation from the highest point P2 obstructed by the contact member 53.
An image forming apparatus in Embodiment 2 is provided with a contact member 253 that is different from the contact member 53 provided in the image forming apparatus 100 of Embodiment 1. That is, the structure and operations of the image forming apparatus in Embodiment 2 are the same as the structure and operations of the image forming apparatus 100 in Embodiment 1 except that their contact members are different from each other. Therefore, the components of the image forming apparatus in Embodiment 2 that are identical or correspond to the components of the image forming apparatus 100 in Embodiment 1 are given the same codes as the components of the image forming apparatus 100 in Embodiment 1 in their explanations.
The contact member 253 comprises regions A21 (first regions) and regions A22 (second regions) formed by the multiple incisions 253c. The regions A21 and the regions A22 should desirably disposed alternately in the longitudinal direction of the contact member 253. The regions A21 comprise free edges 253d and fixed edges 253e. The regions A22 comprise free edges 253f and fixed edges 253g. The free edge 253a of the contact member 253 includes the free edges 253d in the regions A21 and the free edges 253f in the regions A22. The fixed edge 253b of the contact member 253 includes the fixed edges 253e in the regions A21 and the fixed edges 253g in the regions A22.
The distances between the free edge 253a and the fixed edge 253b of the contact member 253 in the regions A21 and the regions A22 are different from each other. Specifically, in a separated state where the toner amount detection member 52 is separated from the contact member 253, the distance L21 between the free edges 253d and the toner amount detection member 52 in the regions A21 is shorter than the distance L22 between the free edges 253f and the toner amount detection member 52 in the regions A22.
As shown in
As shown in
As shown in
As shown in
As explained above, according to Embodiment 2, because the contact member 253 comprises multiple regions having different distances to the toner amount detection member 52, while the toner amount detection member 52 makes one rotation, the contact member 253 can perform multiple stirring operations when part of the regions of the contact member 253 separate from the toner amount detection member 52.
Because the stirring operations of the contact member 253 can give vibrations to the toner Ta inside the toner accommodating part 51 (for example, the toner Ta around the track of the toner amount detection member 52), agglomeration of the toner Ta inside the toner accommodating part 51 (including agglomeration of the toner Ta to the toner amount detection member 52) can be prevented.
By preventing agglomeration of the toner Ta inside the toner accommodating part 51 (including agglomeration of the toner Ta to the toner amount detection member 52), toner amount detection accuracy using the toner amount detection member 52 can be appropriately maintained. By the amount of the toner Ta inside the development device 50 being maintained appropriately, deterioration in print quality by the image forming apparatus can be suppressed.
An image forming apparatus in Embodiment 3 is provided with a different contact member 353 that is different from the contact member 53 provided in the image forming apparatus 100 of Embodiment 1. That is, the structure and operations of the image forming apparatus in Embodiment 3 are the same as the structure and operations of the image forming apparatus 100 in Embodiment 1 except that their contact members are different from each other. Therefore, the components of the image forming apparatus in Embodiment 3 that are identical or correspond to the components of the image forming apparatus 100 in Embodiment 1 are given the same codes as the components of the image forming apparatus 100 in Embodiment 1 in their explanations.
The contact member 353 comprises multiple contact regions A31 formed by the multiple incisions 353c. In each of the multiple contact regions A31, the free edge 353a is inclined relative to a virtual line VL along the longitudinal direction of the contact member 353. Specifically, the contact member 353 is configured so that in each of the multiple contact regions A31, the distance from the fixed edge 353b to the free edge 353a becomes shorter toward one end side (or one of two side ends) from the central (or central side) in the longitudinal direction of the contact member 353. In other words, in each of the contact regions A31, the distance L31 from the fixed edge 353b to the free edge 353a in the central side of the longitudinal direction of the contact member 353 is longer than the distance L32 from the fixed edge 353b to the free edge 353a in the one end side of the longitudinal direction of the contact member 353. In
When the toner amount detection member 52 contacts with the contact member 353, the toner amount detection member 52 contacts with the contact regions A31 of the contact member 353 sequentially from the central side in the longitudinal direction of the contact member 353. Thereby, the contact regions A31 of the contact member 353 warp sequentially from the central side in the longitudinal direction of the contact member 353 and return to the original positions (stationary positions) sequentially from the central side. By such operations of the contact member 353, the contact member 353 realizes a stirring function for the longitudinal direction of the contact member 353. Thereby, a toner Ta around the contact member 353 (including the toner Ta adhering to the toner amount detection member 52) can be moved (stirred) in the longitudinal direction of the contact member 353.
As explained above, according to Embodiment 3, while the toner amount detection member 52 makes one rotation, the contact member 353 can also execute a stirring function when each of the contact regions A31 of the contact member 353 separates from the toner amount detection member 52 in the longitudinal direction of the contact member 353 in addition to a direction perpendicular to the longitudinal direction of the contact member 353.
Because the contact member 353 realizes the stirring function of the toner Ta in the track of the toner amount detection member 52 in the longitudinal direction and a direction perpendicular to the longitudinal direction of the contact member 353, occurrences of voids in the track of the toner amount detection member 52 (that is, a state where the toner Ta is absent in the track of the toner amount detection member 52) can be prevented. By preventing the occurrences of voids in the track of the toner amount detection member 52, the rotation operation of the toner amount detection member 52 can be appropriately maintained, and misdetections by a sensor 90 can be prevented.
By the amount of the toner Ta inside the development device 50 being maintained appropriately, deterioration in print quality by the image forming apparatus can be suppressed.
The development device 50 explained in the above embodiments can be applied to various kinds of image forming apparatuses using an electrophotographic system (such as copiers, light emitting diode printers, laser beam printers, facsimile machines, and multifunction machines).
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-147588 | Jul 2015 | JP | national |
