Patent Application
20190129359
The present invention relates to an image forming apparatus and a duct unit.
In general, an electrophotographic image forming apparatus includes a drum unit, a developing unit, a laser scanning unit, and a transfer device. For example, the drum unit includes a photoconductor, a charging device, and a drum cleaning device. In addition, a tandem-type image forming apparatus includes a plurality of drum units and a plurality of developing units.
The temperature of the photoconductor rises due to the following factors: a voltage is applied from the charging device; a laser beam is irradiated from the laser scanning unit; and the photoconductor is scraped by a blade of the drum cleaning device.
When the temperature of the photoconductor rises excessively, the developing performance is degraded. As a result, the image forming apparatus is provided with an air blower that sends air for cooling the drum unit or the like.
In addition, there is known a tandem-type image forming apparatus that includes a duct that branches from the air blower to a plurality of drum units (see, for example, PTL 1).
[PTL 1] Japanese Patent Application Publication No. 2009-271237
Meanwhile, it is desired that the air blown out from the air blower is efficiently guided to the plurality of drum units or the like by using a duct whose pressure loss is as low as possible. Adoption of a duct with low pressure loss produces advantageous effects such as the power saving and miniaturization of the air blower.
On the other hand, the duct desirably has a simple structure so as to facilitate the molding and reduce the cost of the duct.
The present invention has been made in view of such conventional circumstances, and it is an object of the present invention to provide a duct unit that, with a simple structure, allows air to be guided efficiently from an air blowing unit to a plurality of drum units and a plurality of developing units, and to provide an image forming apparatus including the duct unit.
An image forming apparatus according to an aspect of the present invention includes an air blowing unit, a plurality of drum units, a plurality of developing units, and a duct unit. The air blowing unit stores one or more air blowers, and an air inlet port and one or more air outlet ports are formed in the air blowing unit. Each of the plurality of drum units supports a photoconductor on whose surface an electrostatic latent image is formed. In each of the plurality of drum units, a first air inlet is formed at one of opposite ends in a first direction that extends along a longitudinal direction of the photoconductor, and a first flow path is formed so as to be communicated with the first air inlet and extend along the first direction. Each of the plurality of developing units stores a developing roller configured to develop the electrostatic latent image as a toner image. In each of the plurality of developing units, a second air inlet is formed at one of opposite ends of it in the first direction, and a second flow path is formed so as to be communicated with the second air inlet and extend along the first direction. The duct unit forms air flow paths from the air blowing unit to the plurality of drum units and the plurality of developing units. The duct unit includes an upstream plate portion, a downstream plate portion, a pair of side plate portions, and a partition wall portion. In the upstream plate portion, one or more flow-in openings are formed so as to be communicated with the one or more air outlet ports. The downstream plate portion is disposed to face the upstream plate portion at an interval in a second direction perpendicular to the first direction. In the downstream plate portion, a plurality of flow-out openings are formed at intervals in a third direction to be communicated with the first air inlets and the second air inlets, the third direction being perpendicular to the first direction and the second direction. The pair of side plate portions are disposed to face each other at an interval in the first direction, and are formed to continue from the upstream plate portion to the downstream plate portion. The partition wall portion partitions a space between the pair of side plate portions into branch flow paths and the other area. The branch flow paths branch from the one or more flow-in openings and reach the plurality of flow-out openings. The plurality of flow-out openings are smaller than the one or more flow-in openings in area and width in the first direction. The pair of side plate portions are formed to extend along edges of the one or more flow-in openings and edges of the plurality of flow-out openings. The edges of each of the one or more flow-in openings and the plurality of flow-out openings are opposite to each other in the first direction. The interval between the pair of side plate portions in the first direction becomes gradually narrower from the upstream plate portion toward the downstream plate portion.
A duct unit according to another aspect of the present invention forms air flow paths from an air blowing unit storing an air blower to one or more drum units and one or more developing units, wherein each of the one or more drum units includes a photoconductor on whose surface an electrostatic latent image is formed, and each of the one or more developing units includes a developing roller configured to develop the electrostatic latent image as a toner image. The duct unit includes the upstream plate portion, the downstream plate portion, the pair of side plate portions, and the partition wall portion.
According to the present invention, it is possible to provide a duct unit that, with a simple structure, allows air to be guided efficiently from an air blowing unit to a plurality of drum units and a plurality of developing units, and to provide an image forming apparatus including the duct unit.
The following describes embodiments of the present invention with reference to the accompanying drawings. It should be noted that the following embodiments are examples of specific embodiments of the present invention and should not limit the technical scope of the present invention.
An image forming apparatus 10 according to a first embodiment forms a toner image on a sheet by an electrophotographic system. The sheet is a sheet-like image formation medium such as a sheet of paper or an envelope.
The image forming apparatus 10 includes, in a main body 1, a sheet supply portion 2, a sheet conveying portion 3, and an image forming portion 4. The image forming portion 4 executes a printing process of forming a toner image on the sheet. Furthermore, the image forming apparatus 10 includes a control portion 8, an operation/display portion 80, and an environment sensor 800.
The image forming apparatus 10 is a tandem-type image forming apparatus, and is a color printer. Accordingly, the image forming portion 4 includes four image creating portions 4x that respectively correspond to black toner, magenta toner, cyan toner, and yellow toner, and includes an intermediate transfer belt 46, a belt cleaning device 47, and a sheet transfer device 48.
The image forming portion 4 further includes an optical scanning unit 4s, a sheet transfer device 48, and a fixing device 49.
Each of the image creating portions 4x includes a cylindrical photoconductor 41, a charging device 42, a developing unit 43, a belt transfer device 44, and a drum cleaning device 45. On the four photoconductors 41, toner images of different colors are developed. For example, the photoconductors 41 may be organic photoconductors.
The sheet supply portion 2 feeds the sheet to a sheet conveyance path 30, and the sheet conveying portion 3 conveys the sheet along the sheet conveyance path 30.
In each of the image creating portions 4x, the photoconductor 41 rotates, and the charging device 42 charges the outer circumferential surface of the photoconductor 41. Furthermore, the optical scanning unit 4s writes an electrostatic latent image on the outer circumferential surface of the photoconductor 41 by scanning a light beam BO thereon. In general, the optical scanning unit 4s is referred to as a laser scanning unit.
In addition, a developing roller 43a of the developing unit 43 supplies the toner to the photoconductor 41 so as to develop the electrostatic latent image as the toner image. Subsequently, the belt transfer device 44 transfers the toner images from the surfaces of the photoconductors 41 to the intermediate transfer belt 46. With this operation, a color toner image is formed, from the overlaid toner images of a plurality of colors, on the surface of the intermediate transfer belt 46.
The intermediate transfer belt 46 is an endless belt onto which the toner images are transferred from the four photoconductors 41. The intermediate transfer belt 46 is rotatably supported by a pair of belt support rollers 461 and 462 in a state of passing a transfer path along the four photoconductors 41.
The drum cleaning device 45 removes waste toner from the outer circumferential surface of the photoconductor 41. The drum cleaning device 45 includes a blade 45a that comes into contact with the outer circumferential surface of the photoconductor 41. The blade 45a scrapes off the toner from the outer circumferential surface of the photoconductor 41. It is noted that the waste toner on the photoconductor 41 is toner that has remained on the outer circumferential surface of the photoconductor 41 after the toner image was transferred to the intermediate transfer belt 46.
The sheet transfer device 48 transfers the toner image from the intermediate transfer belt 46 to the sheet. The fixing device 49 fixes the toner image to the sheet by heating the toner image. For this purpose, the fixing device 49 includes a heater 49a.
The belt cleaning device 47 removes waste toner that has remained on the intermediate transfer belt 46 after the toner image was transferred therefrom to the sheet.
In each of the image creating portions 4x, the photoconductor 41, the charging device 42, and the drum cleaning device 45 are unitized as a drum unit 40.
As shown in
Similarly, a first developing unit 43k, a second developing unit 43m, a third developing unit 43c, and a fourth developing unit 43y that respectively correspond to the black toner, the magenta toner, the cyan toner, and the yellow toner are arranged in the stated order from the downstream side to the upstream side in the belt forward direction D0.
It is noted that the first drum unit 40k corresponds to a black drum unit for developing with the black toner. In addition, the second drum unit 40m, the third drum unit 40c, and the fourth drum unit 40y correspond to three color drum units for developing with color toners. In addition, the first developing unit 43k corresponds to a black developing unit for developing with the black toner. In addition, the second developing unit 43m, the third developing unit 43c, and the fourth developing unit 43y correspond to three color developing units for developing with the color toners.
In each of the image creating portions 4x, the drum unit 40 is disposed on the downstream side of the developing unit 43 in the belt forward direction D0. Among the four drum units 40 and the four developing units 43, the first drum unit 40k is closest to the fixing device 49, and the first developing unit 43k is second closest to the fixing device 49.
In
The operation/display portion 80 is a user interface device including an operation portion and a display portion, the operation portion being configured to receive user operations, the display portion being configured to display information.
The control portion 8 executes various types of data processing, and controls various types of electric equipment included in the image forming apparatus 10. For example, the control portion 8 may be realized by a processor such as a MPU (Micro Processing Unit) or a DSP (Digital Signal Processor). In addition, the control portion 8 may be realized by a circuit such as an ASIC (Application Specific Integrated Circuit).
The environment sensor 800 is configured to detect the temperature and humidity in an environment in which the image forming apparatus 10 is installed. A detection signal from the environment sensor 800 is input to the control portion 8.
When the temperature of the photoconductors 41 rises excessively, the developing performance is degraded. As a result, the image forming apparatus 10 is provided with an air blowing unit 5 that sends air for cooling the four drum units 40 and the four developing units 43 (see
The air blowing unit 5 includes one or more air blowers 51 and an air blowing housing 50. The air blowers 51 shown in
The air blowing housing 50 is a hollow member made of synthetic resin and stores the air blowers 51 therein. For example, the air blowing housing 50 may be formed by combining two members.
The air blowing housing 50 includes an air inlet port 50a and the same number of air outlet ports 52 as the air blowers 51. In the example shown in
In the present embodiment, the air blowing unit 5 includes a first air blower 51a and a second air blower 51b. The air blowing housing 50 includes a first air outlet port 52a and a second air outlet port 52b, the first air outlet port 52a being communicated with an air blow-out port of the first air blower 51a, the second air outlet port 52b being communicated with an air blow-out port of the second air blower 51b.
Furthermore, the image forming apparatus 10 includes a duct unit 6 that forms air flow paths from the air blowing unit 5 to the four drum units 40 and the four developing units 43. The duct unit 6 is a member made of synthetic resin forming air flow paths in an interior thereof. For example, the duct unit 6 may be formed by combining two members.
As shown in
In addition, as shown in
The duct unit 6 guides the air sent from the air outlet ports 52 of the air blowing unit 5 to the first air inlets 401 of the four drum units 40 and the second air inlets 431 of the four developing units 43.
Meanwhile, it is desired that the air blown out from the air blowers 51 is efficiently guided to the plurality of drum units 40 or the like by using the duct unit 6 whose pressure loss is as low as possible. Adoption of the duct unit 6 with low pressure loss produces advantageous effects such as the power saving and miniaturization of the air blowers 51.
On the other hand, the duct unit 6 desirably has a simple structure so as to facilitate the molding of the duct unit 6 and reduce the cost of the duct unit 6.
The duct unit 6 of the present embodiment has a structure described below that, with a simple structure, allows air to be guided from the air blowing unit 5 to the four drum units 40 and the four developing units 43 efficiently. The following describes the structure of the duct unit 6.
In the following description, a direction extending along the longitudinal direction of the photoconductor 41 is referred to as the first direction D1, a direction perpendicular to the first direction D1 is referred to as the second direction D2, and a direction perpendicular to the first direction D1 and to the second direction D2 is referred to as a third direction.
In the present embodiment, the first direction D1 and the third direction D3 are horizontal directions, and the second direction is a vertical direction. In addition, the first direction D1 is a depth direction of the image forming apparatus 10.
[Structure of Duct Unit 6]
As shown in
In the upstream plate portion 61, one or more flow-in openings 61a and 61b are formed so as to be communicated with the air outlet ports 52 of the air blowing unit 5. In the present embodiment, the upstream plate portion 61 forms a bottom surface of the air blowing unit 5.
The number of the flow-in openings 61a and 61b is the same as the number of the air outlet ports 52. In the present embodiment, the flow-in openings 61a and 61b include a first flow-in opening 61a and a second flow-in opening 61b, wherein the first flow-in opening 61a is communicated with the first air outlet port 52a, and the second flow-in opening 61b is communicated with the second air outlet port 52b. The first air outlet port 52a and the second flow-in opening 61b are aligned at an interval in the third direction D3.
The downstream plate portion 62 is disposed to face the upstream plate portion 61 at an interval in the second direction D2. As a result, the downstream plate portion 62 of the present embodiment forms an upper surface of the air blowing unit 5.
In the downstream plate portion 62, eight flow-out openings 621k, 621m, 621c, 621y, 622k, 622m, 622c, and 622y are formed at intervals in the third direction D3, to be communicated with the first air inlets 401 of the drum units 40 and the second air inlets 431 of the developing units 43.
The eight flow-out openings 621k, 621m, 621c, 621y, 622k, 622m, 622c, and 622y include two first flow-out openings 621k and 621m, two second flow-out openings 622k and 622m, two third flow-out openings 621c and 621y, and two fourth flow-out openings 622c and 622y.
The two first flow-out openings 621k and 621m are respectively communicated with the first air inlets 401 of the first drum unit 40k and the second drum unit 40m. The two second flow-out openings 622k and 622m are respectively communicated with the second air inlets 431 of the first developing unit 43k and the second developing unit 43m.
The two third flow-out openings 621c and 621y are respectively communicated with the first air inlets 401 of the third drum unit 40c and the fourth drum unit 40y. The two fourth flow-out openings 622c and 622y are respectively communicated with the second air inlets 431 of the third developing unit 43c and the fourth developing unit 43y.
It is noted that the second drum unit 40m, the third drum unit 40c, and the fourth drum unit 40y are an example of the three color drum units. Similarly, the second developing unit 43m, the third developing unit 43c, and the fourth developing unit 43y are an example of the three color developing units.
The pair of side plate portions 63a and 63b are disposed to face each other at an interval in the first direction D1, and are formed to continue from the upstream plate portion 61 to the downstream plate portion 62 (see
The partition wall portion 64 partitions a space between the pair of side plate portions 63a and 63b into branch flow paths 65 and 66 and the other area, wherein the branch flow paths 65 and 66 branch from the flow-in openings 61a and 61b and reach the eight flow-out openings 621k, 621m, 621c, 621y, 622k, 622m, 622c, and 622y. The partition wall portion 64 is formed to stand from an inner surface of one of the pair of side plate portions 63a and 63b.
The partition wall portion 64 forms independent branch flow paths 65 and 66 respectively for the flow-in openings 61a and 61b. As a result, the branch flow paths 65 and 66 include a first branch flow path 65 and a second branch flow path 66, wherein the first branch flow path 65 is communicated with the first flow-in opening 61a, and the second branch flow path 66 is communicated with the second flow-in opening 61b.
As shown in
On the other hand, the second branch flow path 66 branches into two branches at a position close to the second flow-in opening 61b, and further branches into four branches, thereby forming flow paths toward the four flow-out openings 621c, 621y, 622c, and 622y.
As shown in
More specifically, the first flow-in opening 61a is located on the upstream side, in the belt forward direction D0, of the range in the third direction D3 in which the two first flow-out openings 621k and 621m and the two second flow-out openings 622k and 622m are formed.
As shown in
On the other hand, the second flow-in opening 61b is located at an intermediate position in a range in the third direction D3 in which are formed the four flow-out openings 621c, 621y, 622c, and 622y that are communicated with each other via the second branch flow path 66.
As shown in
In addition, a sum of the areas of the four flow-out openings 621k, 621m, 622k, and 622m that are communicated with the first branch flow path 65 is smaller than the area of the first flow-in opening 61a. Similarly, a sum of the areas of the four flow-out openings 621c, 621y, 622c, and 622y that are communicated with the second branch flow path 66 is smaller than the area of the second flow-in opening 61b.
Accordingly, the air that has flowed in the two flow-in openings 61a and 61b is accelerated in the duct unit 6, and flows out from the eight flow-out openings 621k, 621m, 621c, 621y, 622k, 622m, 622c, and 622y.
The air accelerated in the duct unit 6 travels far to a distant place along the first flow path 402 of the drum housing 400 and the second flow path 432 of the developing housing 430. As a result, with a configuration where the air blowing unit 5 is provided at one of opposite ends of the drum units 40 in the first direction D1, it is possible to cool the drum units 40 and the developing units 43 over the whole length in the longitudinal direction thereof.
As shown in
The air flow paths in the duct unit 6 do not have a portion at which the cross-sectional area is narrowed suddenly, namely, a portion having a large pressure loss. As a result, the air that flows in the two flow-in openings 61a and 61b is efficiently accelerated in the duct unit 6. This produces advantageous effects such as the power saving and miniaturization of the air blowers 51.
Furthermore, the duct unit 6 can be realized by combining two members formed from synthetic resin and having extremely simple structures. For example, a first resin member constituting a part of the duct unit 6 may include one of the pair of side plate portions 63a and 63b and the partition wall portion 64, and a second resin member may include the other of the pair of side plate portions 63a and 63b. In that case, each of the upstream plate portion 61 and the downstream plate portion 62 may be included in any of the first resin member and the second resin member. The first resin member and the second resin member can be manufactured by a simple ejection molding.
In the present embodiment, an inner surface of the first side plate portion 63a is a vertical flat surface, and an inner surface of the second side plate portion 63b is a flat surface inclined with respect to the vertical direction. In this case, members constituting the duct unit 6 can be molded more easily.
In addition, as shown in
Similarly, widths W2k and W2m of two second branch portions in the third direction D3 that branch from the trunk flow path 65a of the first branch flow path 65 to the two second flow-out openings 622k and 622m, become larger as the second branch portions are located farther from the first flow-in opening 61a. That is, W2k>W2m.
The above-described relationships among widths of the branch portions make it possible to prevent the flow rate of air flowing toward the two first flow-out openings 621k and 621m from being deviated in one direction, and prevent the flow rate of air flowing toward the two second flow-out openings 622k and 622m from being deviated in one direction.
In addition, the second branch flow path 66 is independent of the first branch flow path 65 that is communicated with the first drum unit 40k and the first developing unit 43k for the black toner. In this case, when the operation mode of the printing process has been set to a monochrome print mode, the control portion 8 can stop the second air blower 51b. This makes it possible to restrict power consumption of the second air blower 51b.
It is noted that the monochrome print mode is an operation mode in which application of a charging voltage and scanning of the light beam BO are not performed on the photoconductors 41 of the second drum unit 40m, the third drum unit 40c, and the fourth drum unit 40y for the three color toners. The control portion 8 sets the monochrome print mode in accordance with the user's setting operation performed on the operation/display portion 80.
In a case where the monochrome print mode has not been set, the image forming apparatus 10 operates in the color print mode. In the color print mode, application of a charging voltage and scanning of the light beam BO are performed on the photoconductors 41 of all drum units 40.
In addition, as shown in
In the example shown in
The duct unit 6 can stand by itself by using the flat surfaces that are flush with each other, as ground contact surfaces. With this configuration, during a process in which the duct unit 6 is attached to the image forming apparatus 10, when the duct unit 6 is temporarily placed on a work table or the like, the duct unit 6 stands stably by itself. This facilitates the handling of the duct unit 6.
Next, a description is given of a duct unit 6A provided in an image forming apparatus 10A according to a second embodiment with reference to
In
The duct unit 6A has a configuration which is made by adding a movable partition wall portion 640 and a displacement mechanism 68 to the duct unit 6.
The movable partition wall portion 640 is a part of the partition wall portion 64, and is displaceably supported. Specifically, the movable partition wall portion 640 includes a partition plate portion 641 and a rotation shaft 642 that is formed to project from an end of the partition plate portion 641. The rotation shaft 642 is rotatably supported by the pair of side plate portions 63a and 63b.
The movable partition wall portion 640 can be displaced around the rotation shaft 642 between a reference position and a communication position. At the reference position, the movable partition wall portion 640 closes an opening 64a that is formed in a portion of the partition wall portion 64 that partitions between the trunk flow path 65a of the first branch flow path 65 and a part of the second branch flow path 66. That is, at the reference position, the movable partition wall portion 640 partitions between the trunk flow path 65a of the first branch flow path 65 and the part of the second branch flow path 66 (see
On the other hand, at the communication position, the movable partition wall portion 640 opens the opening 64a. That is, at the communication position, the movable partition wall portion 640 forms an air flow path from the part of the second branch flow path 66 to the trunk flow path 65a.
The displacement mechanism 68 is configured to displace the movable partition wall portion 640 between the reference position and the communication position in accordance with a control signal input from the control portion 8.
For example, the displacement mechanism 68 may include a gear mechanism and a motor, wherein the gear mechanism is coupled with the rotation shaft 642, and the motor drives the gear mechanism. In this case, the control portion 8 outputs the control signal to the motor.
In addition, the displacement mechanism 68 may include an arm portion and an electric actuator such as a solenoid actuator, wherein the arm portion is coupled with the rotation shaft 642, and the electric actuator displaces the arm portion. In this case, the control portion 8 outputs the control signal to the electric actuator.
When a predetermined temperature condition is satisfied, the control portion 8 outputs, as the control signal, a communication signal so as to displace the movable partition wall portion 640 to the communication position, the temperature condition being determined based on the temperature detected by the environment sensor 800. Otherwise, the control portion 8 controls the displacement mechanism 68 so as to displace the movable partition wall portion 640 to the reference position.
For example, when the temperature condition is not satisfied, the control portion 8 may output, as the control signal, a reference signal so as to displace the movable partition wall portion 640 to the reference position. In addition, the control portion 8 may displace the movable partition wall portion 640 to the reference position by not outputting the control signal.
When the movable partition wall portion 640 is displaced to the communication position in a state where the first air blower 51a and the second air blower 51b are operating, a part of the air flowing the second branch flow path 66 flows out to the trunk flow path 65a of the first branch flow path 65. This increases the amount of air that cools the first drum unit 40k and the first developing unit 43k that are close to the fixing device 49.
The temperature condition includes a condition that the temperature detected by the environment sensor 800 has exceeded an upper limit of a predetermined normal range.
In general, due to closeness to the fixing device 49, the first drum unit 40k and the first developing unit 43k tend to be higher in temperature than the other drum units 40m, 40c, and 40y and the other developing units 43m, 43c, and 43y.
In addition, the first drum unit 40k and the first developing unit 43k operate in both the monochrome print mode and the color print mode. This is also one of factors for increasing the temperatures of the first drum unit 40k and the first developing unit 43k.
In general, the capacity of the air blowers 51 is determined based on the assumed temperature environment of the photoconductor 41 of the first drum unit 40k. In this case, the temperature of the photoconductor 41 of the first drum unit 40k may temporarily exceed an allowable temperature depending on the use environment of the image forming apparatus 10.
However, always sending an excessive amount of air to the first drum unit 40k and the first developing unit 43k is not preferable since it may adversely affect the developing quality. In addition, in many cases, temperatures of the other drum units 40m, 40c, and 40y and the other developing units 43m, 43c, and 43y that are arranged to be farther from the fixing device 49, have a margin with respect to the allowable temperature.
Therefore, when the amount of cool air sent to the first drum unit 40k and the first developing unit 43k is increased when the temperature condition is satisfied, the photoconductor 41 of the first drum unit 40k is prevented from exceeding the allowable temperature.
In addition, in the present embodiment, when the temperature condition is not satisfied, the control portion 8 may operate the second air blower 51b so as to blow air with an air volume smaller than a rated air volume. In this case, when the temperature condition is satisfied, the control portion 8 may operate the second air blower 51b so as to blow air with the rated air volume. This makes it possible to restrict power consumption of the second air blower 51b when the temperature condition is not satisfied.
In the image forming apparatus 10, the second air blower 51b may have a smaller blowing amount than the first air blower 51a. This makes it possible to restrict power consumption of the air blowers 51.
In the image forming apparatuses 10, 10A, inner surfaces of both the side plate portions 63a and 63b may be flat surfaces inclined with respect to the vertical direction. Similarly, in the image forming apparatuses 10, 10A, the inner surface of the first side plate portion 63a may be a flat surface inclined with respect to the vertical direction, and the inner surface of the second side plate portion 63b maybe a vertical flat surface. In addition, either or both of the inner surfaces of the side plate portions 63a and 63b may be curved surfaces curved in the second direction D2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-028986 | Feb 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/040364 | 11/9/2017 | WO | 00 |
