Embodiments described herein relate generally to a developing device and an image forming apparatus.
An image forming apparatus includes a developing device that accommodates toner, and supplies the toner to a surface of a photoconductive drum. The developing device includes a mixer inside a casing. The developing device causes developer containing toner to circulate inside the casing using the mixer. End portions of the mixer are rotatably supported by the casing. There is some possibility that the developer in the casing may leak from the casing through the end portion of the mixer. When the developer leaks from the inside of the casing, a rotational failure of the mixer can occur as the leaked developer adheres to and then binds the moving portions of the mixer on the outside of the casing.
A developing device includes a casing for accommodating a developer, the casing extending in a first direction and including a first insertion portion and a first through-hole that extends from the first insertion portion in a second direction, a first sealing member inside the first insertion portion, and a first rotating body extending in the first direction through the first insertion portion and configured to transport and agitate the developer in the casing. The first sealing member is in contact with an outer surface of the first rotating body and configured to slide along the outer surface of the first rotating body.
Hereinafter, an image forming apparatus and the developing device according to the embodiment will be described with reference to drawings.
As illustrated in
The scanning unit 2 reads image information of an target to be copied as brightness and darkness of light. The scanning unit 2 outputs the read image information to the control unit 11.
The printing unit 3 forms an output image (hereinafter, referred to as “toner image”) using a developer containing toner and a carrier, based on image information from the scanning unit 2, or received from outside of the image forming apparatus 1. The printing unit 3 transfers the toner image onto the surface of a sheet S. The printing unit 3 fixes the toner image onto the sheet S by applying heat and a pressure to the toner image on the surface of the sheet S.
The sheet accommodating unit 4 supplies the sheet S to the printing unit 3 sheet by sheet. The sheet accommodating unit 4 includes a plurality of sheet feeding cassettes 20A and 20B. Each of the sheet feeding cassettes 20A and 20B accommodates sheets S whose size and types can be preset. Each of the sheet feeding cassettes 20A and 20B includes pickup rollers 21A and 21B, respectively. Each of the pickup rollers 21A and 21B takes out the sheet S individually from each of the sheet feeding cassettes 20A and 20B. The pickup rollers 21A and 21B supply the sheet S which is taken out to the transport unit 5.
The transport unit 5 includes a transport roller 23, and a registration roller 24. The transport unit 5 transports the sheet S supplied by the pickup rollers 21A and 21B to the registration roller 24. The registration roller 24 transports the sheet S according to a timing in which the printing unit 3 transfers the toner image to the sheet S. The transport roller 23 causes a tip end of the sheet S in the transport direction to be in contact with a nip N of the registration roller 24. The transport roller 23 adjusts a position of the sheet S at the tip end in the transport direction by bending the sheet S. The registration roller 24 aligns the tip end of the sheet S which is sent from the transport roller 23 in the nip N. In addition, the registration roller 24 transports the sheet S to a transfer unit 28.
Toner cartridges 16Y, 16M, 16C, and 16K each of which accommodates a toner are mounted on the toner supply unit 6. Toners of colors of yellow, magenta, cyan, and black are respectively accommodated in the toner cartridges 16Y, 16M, 16C, and 16K. A supply tube 17 is provided in the toner supply unit 6. Toners discharged from the toner cartridges 16Y, 16M, 16C, and 16K circulate in the supply tube 17.
As illustrated in
The control unit 11 controls the devices which are connected to each other through the system bus 19. The ROM 12 stores various control programs which are necessary for operations of the control unit 11. The DRAM 13 is used as a temporary storage region of data when the control unit 11 executes a program. The HDD 14 stores data which is used for the control. The HDD 14 stores a reference value of a toner ratio concentration in a developing device 44, for example. The HDD 14 stores various messages to be displayed on the display unit 7, for example. The HDD 14 stores data obtained by the control unit 11 executing a program, for example.
Hereinafter, the printing unit 3 will be described in further detail.
As illustrated in
The intermediate transfer belt 27 is an endless belt (a loop). Tension is applied to the intermediate transfer belt 27 using a plurality of rollers in contact with the inner peripheral faces of the intermediate transfer belt 27. The intermediate transfer belt 27 is flatly stretched. The inner peripheral face of the intermediate transfer belt 27 is in contact with a support roller 28a and a transfer belt roller 30 at a position farthest from the support roller 28a in the stretching direction.
The support roller 28a is a part of the transfer unit 28 which will be described later. The support roller 28a guides the intermediate transfer belt 27 to a secondary transfer position.
The image forming portions 25Y, 25M, 25C, and 25K are disposed in this order on the lower side of the intermediate transfer belt 27 from the transfer belt roller 30 toward the transfer unit 28 side. The image forming portions 25Y, 25M, 25C, and 25K are spaced from each other in a region between the transfer belt roller 30 and the support roller 28a. The image forming portion 25Y forms a toner image of yellow which is transferred to the sheet S on the intermediate transfer belt 27. The image forming portion 25M forms a toner image of magenta which is transferred to the sheet S on the intermediate transfer belt 27. The image forming portion 25C forms a toner image of cyan which is transferred to the sheet S on the intermediate transfer belt 27. The image forming portion 25K forms a toner image of black which is transferred to the sheet S on the intermediate transfer belt 27. Each of the image forming portions 25Y, 25M, 25C, and 25K is similarly formed. In the following descriptions of configurations of the image forming portions 25Y, 25M, 25C, and 25K, the image forming portion 25Y will be described as an example.
The image forming portion 25Y includes an image forming unit 32, and a primary transfer roller 34.
As illustrated in
The photoconductive drum 41 is disposed below the intermediate transfer belt 27. The photoconductive drum 41 faces the lower face of the intermediate transfer belt 27.
In a periphery of the photoconductive drum 41, the charger 42, the exposure unit 43, the developing device 44, the primary transfer roller 34, the cleaning unit 45, and the static eliminator 46 are disposed in a clockwise direction in the front view.
The charger 42 charges the photoconductive drum 41. The charger 42 includes a discharging wire or a needle electrode as a charging electrode.
The exposure unit 43 radiates LED light in accordance with image information on the surface of the photoconductive drum 41. The exposure unit 43 can also be a laser light source which emits laser light. Image information of yellow is supplied to the exposure unit 43 of the image forming portion 25Y. The exposure unit 43 radiates LED light based on image information to the photoconductive drum 41 which has been charged. The exposure unit 43 forms an electrostatic latent image based on the image information of yellow on the surface of the photoconductive drum 41.
The developing device 44 of the image forming portion 25Y accommodates a developer D containing a yellow toner. The developing device 44 charges the accommodated toner. The toner accommodated in the developing device 44 is supplied from the toner cartridge 16Y. The developing device 44 supplies the charged toner to the surface of the photoconductive drum 41 which the developing device faces. The toner adheres to the surface of the photoconductive drum 41 according to the electrostatic latent image. The developing device 44 develops the electrostatic latent image which is formed by the exposure unit 43.
As illustrated in
The casing 100 is a container which accommodates the developer D. When the developer D is agitated, toner is frictionally charged. The toner adheres to the surface of a carrier in the developer D.
The casing 100 extends over the longitudinal direction from a first end portion E1 to a second end portion E2 of the developing device 44. Here, the first end portion E1 of the developing device 44 is an end portion which faces the rear side of the printing unit 3. The second end portion E2 of the developing device 44 is an end portion which faces the front side of the printing unit 3.
As illustrated in
The first mixer 101 and the second mixer 102 are disposed inside the groove portions 111 and 113 of the casing 100, respectively. Center axial lines of the respective first mixer 101 and the second mixer 102 extend along the longitudinal direction of the developing device 44. That is, the axial direction of the respective first mixer 101 and the second mixer 102 matches the longitudinal direction. The first mixer 101 and the second mixer 102 include a spiral impeller.
As illustrated in
The second mixer 102 has the same configuration as that of the first mixer 101. The gear 138 of the first mixer 101 and a gear 138 of the second mixer 102 engage with each other. A coupler which is connected to a driving source 36, depicted in
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The first cover 106 covers the surface of the developing roller 105 except for a portion proximate to the photoconductive drum 41 at the upper part of the groove portion 113.
As illustrated in
Hereinafter, the first end portion E1 of the developing device 44 will be described in further detail. The first end portion E1 of the developing device is the same as the second end portion E2, detailed descriptions of the second end portion E2 will be omitted.
As illustrated in
As illustrated in
The bearing holding portion 119b holds the bearing 104. The bearing holding portion 119b is provided on the outer side of the seal holding portion 119a in the insertion hole 119. The bearing holding portion 119b is adjacent to the seal holding portion 119a. The bearing holding portion 119b is formed by the peripheral face which extends in a fixed inner diameter in the anteroposterior direction, and a stepped face which extends from an end edge in the inside of the peripheral face in the anteroposterior direction toward the inside in the radial direction. The inner diameter of the bearing holding portion 119b is larger than that of the seal holding portion 119a. The bearing 104 is in contact with the stepped face of the bearing holding portion 119b.
As illustrated in
The developer receiver 108 is disposed under the dropping hole 121. The developer receiver 108 receives the developer D which falls from the dropping hole 121. The developer receiver 108 is formed in a box shape which is open to the upper part. The developer receiver 108 is formed of a transparent material such as a resin, for example. The developer receiver 108 is provided under the pair of dropping holes 121 on the left and right by straddling thereof. The developer receiver 108 can slide along the horizontal direction with respect to the casing 100 when being detached. A partition wall 125 is provided inside the developer receiver 108. The partition wall 125 extends from the lower face in the developer receiver 108 toward the upper part. The partition wall 125 also extends along the anteroposterior direction. The partition wall 125 is provided between the dropping holes 121 on the left and right when viewed in the vertical direction. The partition wall 125 divides the inside of the developer receiver 108 into a lower space of the dropping hole 121 on the left side and a lower space of the dropping hole 121 on the right side.
As illustrated in
The static eliminator 46 radiates light onto the surface of the photoconductive drum 41 which passed through the cleaning unit 45. The static eliminator 46 eliminates charges on the photoconductive drum 41.
The sensor 47 is disposed under the developing device 44. The sensor 47 is provided under each of the dropping holes 121. The sensor 47 detects the developer D in the developer receiver 108. The sensor 47 is an optical sensor, for example. The sensor 47 detects a change in light which is transmitted through the developer receiver 108, for example. The sensor 47 is connected to the system bus 19, and is controlled by the control unit 11, depicted in refer
The primary transfer roller 34 is a conductive roller. The primary transfer roller 34 is in contact with the photoconductive drum 41 in a pressing manner through the intermediate transfer belt 27. A transfer bias voltage is applied to the primary transfer roller 34. In this manner, a toner image is primarily transferred to the intermediate transfer belt 27.
As illustrated in
The fixing unit 29 fixes the toner image to the sheet S using heat and pressure applied to the sheet S.
Hereinafter, operations of a developing device according to the embodiment will be described.
The developer D in the casing 100 may leak from inside of the casing 100 through a portion between the first mixer 101, or the second mixer 102, and the sealing member 103. However, according to an embodiment, the dropping hole 121 which extends downward from the seal holding portion 119a is formed in the casing 100 on the outer side of the sealing member 103. Thus, the developer D which leaks from inside of the casing 100 by passing through the portion between the first mixer 101, or the second mixer 102, and the sealing member 103 falls in the dropping hole 121. Therefore, it is possible to prevent the developer D leaked from inside of the casing 100 from remaining inside the insertion hole 119. It is possible to reduce adhering of the developer D to a movable portion at the periphery of the insertion hole 119. Accordingly, it is possible to suppress an occurrence of a rotation failure of the first mixer 101 or the second mixer 102.
In particular, the first mixer 101 includes the gear 138 at the end portion, which also applies to the second mixer 102. Thus, it is possible to suppress a situation in which the developer D leaked from the inside of the casing 100 adheres to the gear 138, causing the gear 138 to be chipped. Accordingly, it is possible to suppress an occurrence of a rotation failure of the first mixer 101 or the second mixer 102.
The dropping hole 121 is formed inside the bearing 104. Thus, the developer D leaked from the inside of the casing 100 falls in the dropping hole 121 before reaching the bearing 104. Accordingly, it is possible to prevent the developer D leaked from the inside of the casing 100 from adhering to the bearing 104. Therefore, it is possible to suppress fixing or lock-up of the bearing 104 that would otherwise be caused by the adhering of the developer D.
The developing device 44 includes the developer receiver 108 which can receive the developer D which falls through the dropping hole 121. In this manner, it is possible to suppress scattering of the developer D which falls through the dropping hole 121. It is possible to check whether or not the developer D falls from the dropping hole 121, by checking a presence or absence of the developer D which is received in the developer receiver 108. In this manner, it is possible to check whether or not the developer D leaks from the inside of the casing 100.
The developer receiver 108 is formed so as to be detachable from the casing 100. Thus, the developer D is removed from the developer receiver 108 when the developer D leaks, and re-attached to the casing 100 when the developer receiver 108 is used.
The developer receiver 108 is attached to and detached from the casing 100 along the horizontal direction. Thus, it is possible to suppress scattering of the developer D when the developer receiver 108 moves in the vertical direction, when the developer receiver 108 receives the developer D. Accordingly, it is possible to suppress a situation in which the developer D scatters at the periphery of the developing device 44, and adheres to the developing device.
The developer receiver 108 is formed of a transparent material. Thus, it is possible to check a presence or absence of the developer D which is received in the developer receiver 108, without detaching the developer receiver 108 from the casing 100. Accordingly, it is possible to easily check whether or not the developer D leaks from the casing 100.
The developer receiver 108 is provided by straddling the lower part of the pair of dropping holes 121 on the left and right. Thus, it is possible to reduce the number of components compared to a case in which the developer receiver 108 is individually provided at the respective lower part of the pair of dropping holes 121 on the left and right.
The developer receiver 108 includes the partition wall 125 which is provided between the pair of dropping holes 121 on the left and right, when viewed in the vertical direction. For this reason, it is possible to discriminate from which dropping holes 121 on the left and right the developer D falls, by checking in which partition wall 125 on the left and right the developer D is received. Accordingly, it is possible to discriminate from which insertion holes 119 on the left and right the developer D leaks.
The image forming apparatus 1 includes the sensor 47 which detects falling of the developer D into the developer receiver 108. For this reason, the image forming apparatus 1 can inform a user of an occurrence of leaking of the developer D, without causing the user to check the developer receiver 108.
The sensor 47 detects falling of the developer from under the dropping hole 121. For this reason, it is possible to discriminate from which dropping hole 121 the developer D falls, when the plurality of insertion holes 119 are aligned in a line. Accordingly, it is possible to exactly inform a user of a portion at which leaking of the developer D has occurred.
A position at which the dropping hole 121 is formed is not limited to the position in the above described embodiment. In the dropping hole, at least a part thereof may be open to the outer side of the sealing member 103 in the anteroposterior direction, on the lower face of the insertion hole 119. In the dropping hole, at least a part thereof may be open to inside of the bearing 104 in the anteroposterior direction, on the lower face of the insertion hole 119.
According to at least one of the above described embodiments, the dropping hole which extends downward from the insertion hole on the outer side of the sealing member is formed in the casing. For this reason, it is possible to prevent the developer leaked from the inside of the casing from remaining in the insertion hole. Accordingly, it is possible to suppress adhering of the developer to the movable portion at the periphery of the insertion hole. Accordingly, it is possible to suppress an occurrence of a rotation failure of the first mixer and the second mixer.
While certain embodiments have been described these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms: furthermore various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
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Number | Date | Country |
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2003316154 | Nov 2003 | JP |