Hereinafter, an embodiment of the invention is described in detail with reference to the accompanying drawings.
An image forming apparatus shown in
The process cartridges 30 (30Y, 30M, 30C, and 30K) are disposed so that the process cartridge 30Y adapted to form yellow (Y) toner images, the process cartridge 30M adapted to form magenta (M) toner images, the process cartridge 30C adapted to form cyan (C) toner images, the process cartridge 30K adapted to form black (K) toner images are serially arranged from the upstream side (the bottom side, as viewed in
An exposure device 15, which is common to the process cartridges 30, is disposed opposite to the conveying path 12 across each of the process cartridges 30. The exposure device 15 turns on and drives an associated one of semiconductor lasers (not shown) respectively corresponding to the four colors according to image data corresponding to an associated one of the four colors. Then, light beams outputted from each of the four semiconductor lasers are deflected and scanned by an associated one of polygon mirrors (not shown). Subsequently, the laser beams are guided to an exposure point on each of the photoreceptor drums 14 through an fθ-lens and a plurality of reflection mirrors. Thus, a light image is formed on each of the photoreceptor drums 14.
A conveying belt 16 performing circulation movement along the conveying path 12 is disposed to pass through places respectively corresponding to the photoreceptor drums 14 of the process cartridges 30. The conveying belt 16 is formed of a belt material that can electrostatically adsorb the recording paper P. The conveying belt 16 is laid across a pair of a drive roller 17A and a driven roller 17B. Also, an adsorption roller 18 adapted to cause the conveying belt 16 to electrostatically adsorb the recording paper P is disposed on the conveying path 12.
A transfer roller 19 is disposed at each of places on the rear surface side of the conveying belt 16, which respectively correspond to the photoreceptor drums 14 of the process cartridges 30. Each of the transfer rollers 19 brings an associated one of the photoreceptor drums 14 to be in close contact with the recording paper P on the conveying belt 16 to thereby transfer a toner image, which is formed on the associated photoreceptor drum 14, onto the recording paper P.
A fixing device 20 is provided on the conveying path 12 above (or downstream from) the highest (most downstream) process cartridge 30K. A paper ejection portion 21 adapted to accommodate the ejected recording paper P, to which a toner image is fixed by the fixing device 20, is provided integrally with the body 10a. Also, a reverse conveying path 22 adapted to reverse the front surface and the back surface of the recording paper P, on one of the surfaces of which the image is fixed by the fixing device 20, and to feed the reversed paper to the conveying path 12 is placed in the body 10a.
As shown in
The conveying belt 16, the drive roller 17A, the driven roller 17B, the adsorption roller 18, the transfer roller 19 and the reverse conveying path 22 are attached to the front cover 25. Therefore, when the front cover 25 is opened, these components follow the front cover 25 and are moved away from the body 10a. Thus, the process cartridge 30 is exposed by opening the front cover 25. This facilitates a user's access to the conveying path 12.
Incidentally, each of the process cartridges 30 is detachably attached in a substantially horizontal direction to the body 10a, similarly to the process cartridge 30K shown in
Thus, the process cartridges 30 can be exposed and replaced by opening the front cover 25. Also, a paper jam can be handled (that is, jam clearance can be achieved) by exposing the photoreceptor drum 14.
The image forming apparatus 10 of the above configuration forms an image by performing the following operation.
First, when image data is inputted to the image forming apparatus 10 from an image reading apparatus (a scanner (not shown)) or a computer system (not shown), the image data respectively corresponding to the colors (Y, M, C, K) are outputted the exposure devices 15 after an image processing apparatus (not shown) performs predetermined image processing thereon.
The exposure devices 15 irradiate exposure beams, which are outputted from the semiconductor lasers according to input image data respectively corresponding to the colors, onto the photoreceptor drums 14 of the process cartridges 30. In each of the process cartridges 30, an electrostatic latent image formed on the photoreceptor drums 14 by exposure is developed by toner of the associated color to thereby form a toner image.
Subsequently, toner images respectively formed on the photoreceptor drums 14 of the process cartridges 30 are serially superimposed and transferred onto the recording paper P, which is supplied from a cassette paper feed portion 26 by being adsorbed to the conveying belt 16 by the action of the adsorption roller 18, by a transfer portion abutting against the transfer rollers 19.
Then, the recording paper P, onto which the toner images are electrostatically transferred, is conveyed to the fixing device 20. Subsequently, the fixing device 20 fixes the toner images thereonto by heat and pressure. Thereafter, the recording paper P is ejected to the paper ejection portion 21 provided in the upper portion of the image forming apparatus 10. Thus, a sequence of an image forming process is finished.
Next, the process cartridge 30 embodying an image forming unit according to the invention is described in detail below.
Each of the process cartridges 30 has the photoreceptor drum 14, an electrification device 31, a developing device 32, a neutralization device 33, a cleaning device 34, and an auxiliary toner replenishing portion 35, which are provided in a housing 30A.
The outer shape of each of the process cartridges 30 is a flat hexahedron as shown in
The electrification device 31, the cleaning device 34, and the auxiliary toner replenishing portion 35 are configured in the upper layer, while the developing device 32 is configured in the lower layer. The photoreceptor drum 14 is placed at the right end of the space between the upper and the lower layers, as viewed in
Hereinafter, description is made by assuming that the direction of the axis of each of the photoreceptor drums 14 is a lateral direction, that a horizontal direction perpendicular to the direction of the axis thereof is an anteroposterior direction (a side, at which each of the photoreceptor drums 14 is disposed, is a frontward direction), and that a direction perpendicular to the anteroposterior direction and to the lateral direction is an up-down direction.
Each of the photoreceptor drums 14 has a part whose predetermined range extending in an up-down direction is exposed through an opening portion 30B formed in a front-side portion of the housing 30A. Each of the photoreceptor drums 14 is in contact with the recording paper at this part and transfers the toner image thereonto.
Additionally, knobs 36 serving as held portions are provided at both lateral ends of each of the front sides of the process cartridges 30, respectively. The knobs 36 are placed at the left side and the right side of the opening portion 30B through which each of the photoreceptor drums 14 is exposed from the housing 30A. When the process cartridge 30 is mounted or replaced, an operator holds the knob 36. Each of the knobs 36 has the function of fixing the process cartridge 30 to a predetermined place by a swinging operation. That is, operations of mounting and replacing the process cartridge 30 are performed by holding the knob 36.
Next, each of operating portions of the process cartridge 30 is described below.
The photoreceptor drum 14 is rotatably disposed therein and is rotationally driven by a drive motor (not shown) in the direction of an arrow shown in
Additionally, as the photoreceptor drum 14 rotates, the photoreceptor provided on the circumference surface is electrified by the electrification device 31. The developing device 32 develops an electrostatic latent image, which is formed by the exposure device 15, into a toner image. Also, the neutralization device 33 eliminates the charging hysteresis of the photoreceptor after the toner image is transferred onto the recording paper. The cleaning device 34 mechanically removes toner remaining on the photoreceptor.
The electrification device 31 is constructed by disposing a charging roll 31a, to which a charging bias is applied, to be in contact with the photoreceptor drum 14. Thus, the photoreceptor drum 14 is charged to a predetermined electric potential (of a negative polarity in the present embodiment).
The developing device 32 is constructed by integrating a developing portion 40, which is adapted to develop an electrostatic latent image on the photoreceptor drum 14 by using toner, with a main toner replenishing portion 60 in a horizontal direction. Additionally, the auxiliary toner replenishing portion 35 constitutes a part of the developing device 32 and is adapted to replenish the main toner replenishing portion 60 with toner. Incidentally, the developing device 32 is of the two-component type that uses developer including toner and carrier.
The developing portion 40 has a developing roll 43, a pair of augers including a supply auger 44 and a stirring auger 45, and a layer thickness regulating member 50.
The supply auger 44 is disposed in a supply region adjoining the developing roll 43. The stirring auger 45 is disposed in a stirring region 47, which is separated from the supply region by a partitioning wall 48. Incidentally, the partitioning wall 48 is not provided in a predetermined range from each of both the left and right end portions. In this portion, developer can circulate between the supply region 46 and the stirring region 47.
The main toner replenishing portion 60 has a toner accommodating chamber 61, which is separated from a partitioning wall 61a, and a toner replenishing chamber 64.
Agitators 62 and 63 are provided in the toner accommodating chamber 61. Also, a replenishment auger 65 is provided in the toner replenishing chamber 64.
The toner accommodating chamber 61 and the toner replenishing chamber 64 communicate with each other through a toner carry-in port 67. Further, the toner replenishing chamber 64 and the stirring region 47 communicate with each other through a toner replenishing port 68. Consequently, the toner accommodated in the toner accommodating chamber 61 can be supplied to the developing portion 40 through the toner carry-in port 67, the toner replenishing chamber 64, and the toner replenishing port 68.
The auxiliary toner replenishing portion 35 has auxiliary agitators 35b and 35c provided in an auxiliary toner accommodating chamber 35a. The auxiliary toner replenishing portion 35 is connected to the main toner replenishing portion 60 through a connecting passage 66.
Further, the developing device 32 of the above configuration performs the following operation when an image is formed.
In the developing portion 40, the developer is circulated and conveyed by the supply auger 44 and the stirring auger 45 while stirred. The developer is electrified by the friction between the toner and the carrier. Then, the developer is supplied to the developing roll 43. Consequently, the toner is transferred to the electrostatic latent image on the photoreceptor drum 14 through the developing roll 43 to thereby visualize the latent image (into a toner image).
The toner is consumed as a development operation is performed. Thus, when the concentration of toner in the developer is reduced, the main toner replenishing portion 60 supplies to the toner replenishing chamber 64 the toner accommodated in the toner accommodating chamber 61 through the toner carry-in port 67. The toner held in the toner replenishing chamber 64 is conveyed by the replenishing auger 65. Thus, the toner is supplied to the stirring region 47 of the developing portion 40 through the toner replenishing port 68. The toner is replenished to the toner accommodating chamber 61 from the auxiliary toner replenishing portion 35 through the connecting passage 66.
The neutralization device 33 is placed on the upper edge part of the opening portion 30B formed in the housing 30A to face the photoreceptor drum 14. Then, after the transfer process is finished, the photoreceptor of the photoreceptor drum 14 is irradiated with neutralization light at the upstream side of the cleaning device 34. The characteristic configuration according to the invention is applied to the neutralization device 33. The neutralization device 33 is described in detail later.
The cleaning device 34 has a cleaning blade 34a and a toner collection mechanism 34b.
The cleaning blade 34a is formed of a urethane rubber and is shaped like a plate. The cleaning blade 34a is supported like a bracket 34d, and is disposed by being press-contacted in a direction opposite to the direction of rotation of the photoreceptor drum 14. Then, the toner remaining on the surface of the photoreceptor drum 14 upon completion of the transfer is removed by being scraped by the cleaning blade 34a. The toner scraped by the cleaning blade 34a is transported to a collection portion 34c by the toner collection mechanism 34b.
Next, the neutralization device 33 having a configuration characteristic to the present embodiment is described in detail below.
The neutralization device 33 has a light guide 33a serving as a light irradiating section that guides neutralization light, and also has an accommodating case 33b serving as a case member adapted to accommodate the light guide 33a. The outer shape of the neutralization device 33 is like a bar extending over the entire length in the longitudinal direction of the photoreceptor drum 14. The neutralization device 33 is attached to the bottom surface of an upper edge part of the opening portion 30B of the housing 30A. Incidentally, reference numeral 37 designates a seal member adapted to divide off the neutralization device 33 from the cleaning device 34 located downstream therefrom in the downstream side in the direction of rotation of the photoreceptor drum 14. The seal member 37 is fixed to the housing 30A on the upper base edge portion. The seal member 37 is provided so that the free edge part of the other end portion thereof is in contact with the photoreceptor drum 14. Thus, the seal member 37 prevents dust, such as toner cloud, from flowing into the neutralization device 33 from the cleaning device 34.
The light guide 33a is shaped like a cylinder, which has a predetermined diameter and also has a length corresponding to that of the photoreceptor drum 14, and is formed of glass or a resin (such as an acrylic resin or a polycarbonate resin) which excels in translucency. Although the details of the light guide 33a are not shown, the light guide 33a is configured so that light having been incident from an end surface thereof is reflected to a circumferential surface thereof. For example, unevenness is formed in a part of the light guide 33a, which is opposite to a side facing the photoreceptor drum 14. Due to this unevenness, substantially uniform light is axially irradiated over the photoreceptor drum 14.
The accommodating case 33b is cross-sectionally substantially-U-shaped, which has an irradiation opening portion whose width corresponds to the diameter of the light guide 33a. The accommodating case 33b is formed of, for example, a white resin by injection-molding so that at least an inner surface has high light reflection efficiency. Also, buffer members 33c are respectively provided on the end surfaces of both the side plates 33br and 33bl of the irradiation opening portion, which face the photoreceptor drum 14.
The buffer members 33c are formed of a material, for example, urethane foam sponge that does not damage the photoreceptor of the photoreceptor drum 14 even when the buffer member 33c is brought into contact with the photoreceptor. Preferably, the color of each of the buffer members 33c is black, which has light shielding property so as to prevent light from leaking to the outside.
Further, the neutralization device 33 is configured so that the accommodating case 33b accommodates the light guide 33a in the irradiation opening portion thereof to cover the light guide 33a, and that the accommodating case 33b is attached to the bottom surface of the upper edge part of the opening portion 30B of the housing 30A to make the irradiation opening side thereof face the photoreceptor drum 14.
The light guide 33a is adapted so that an end surface thereof is exposed to the side of the side surface of the associated process cartridge 30, as shown in
Incidentally, in the body 10a (see
Consequently, light outputted from the LED lamp is incident upon the end surface of the light guide 33a of the associated process cartridge 30, which is mounted in the body 10a of the image forming apparatus 10. Additionally, the incident light is reflected as neutralization light by the light guide 33a to the photoreceptor provided on the circumferential surface of each of the photoreceptor drums 14. Thus, electricity is removed by irradiating the neutralization light.
That is, the LED lamp serving as a light source is provided in the body 10a of the image forming apparatus 10. A device (that is, the neutralization device 33) adapted to guide light from the LED lamp to each of the photoreceptor drums 14 is provided in the associated process cartridge 30.
Meanwhile, preferably, the light guide 33a is placed as close as possible to the photoreceptor provided on the circumferential surface of each of the photoreceptor drums 14 to enhance neutralization efficiency (that is, to obtain a high-degree neutralization effect by a small amount of light). Incidentally, the light guide 33a and the accommodating case 33b are spaced by an appropriate distance (ranging from about 2 mm to about 3 mm) so as not to touch and damage the photoreceptors.
However, because the neutralization device 33 is provided on the upper edge part of the opening portion 30B of the housing 30A, as described above, there is a fear that when the housing 30A is pressed, the housing 30A may bend, and that thus the light guide 33a and the accommodating case 33b may touch the photoreceptor. In the present embodiment, the knobs 36 (see
Even in such a case, according to the present embodiment, the buffer members 33c attached to the accommodating case 33b abut against the photoreceptor drum 14. Consequently, the accommodating case 33b and the light guide 33a can be prevented from abutting directly against and damaging the photoreceptor drum 14.
Incidentally, preferably, for example, a gap of about 1 mm is set to be the distance between the buffer member 33c and the surface of the photoreceptor drum 14 to prevent the remaining toner from adhering thereto. Further, it is unnecessary that a region, in which the buffer members 33c are disposed, extends over the entirety in the axial direction of the photoreceptor drum 14. It is sufficient that an amount of elastic deformation is large, and that the accommodating case 33b and the light guide 33a are provided only in a central portion, in which the accommodating case 33b and the light guide 33a easily abut against the photoreceptor drum 14, to have a predetermined length. Also, the buffer member 33c may be provided only on one of the side plates 33br and 33bl, instead of being provided on both the side plates 33br and 33bl.
Next, another example of the configuration of the buffer member is described below.
The buffer sheet 33d shown in
Additionally, the buffer sheet 33d prevents the light guide 33a and the accommodating case 33b due to the stiffness (or what is called the elasticity) of the buffer sheet 33d from touching the photoreceptor. Also, the buffer sheet 33d prevents toner cloud from flowing into the neutralization device 33 from the cleaning device 34. Thus, the buffer sheet 33d can prevent an amount of light from being reduced due to the adhesion of the toner cloud to the light guide 33a. That is, the buffer sheet 33d of this configuration has both of a buffering function and a dust proofing function of preventing the toner cloud from flowing into the neutralization device 33 from the cleaning device 34. Additionally, preferably, the color of the buffer sheet 33d is, for example, black, which has light shielding property so as to prevent light from leaking to the outside.
In this example of the configuration of the buffer member, a buffer member 33c, which is similar to that of the above example of the configuration of the buffer member, is provided on the end surface of the other side plate 33br of the accommodating case 33b. This buffer member 33c may be omitted. However, the provision of this buffer member 33c can enhance a buffering effect still more.
Incidentally, the invention is not limited to the above embodiments. The invention can be applied to operating components other than the neutralization device 33. Also, the invention can be applied to devices other than the process card serving as the image forming unit. Additionally, the configuration of the image forming apparatus, to which the invention is applied, is not limited to the above embodiment.
Number | Date | Country | Kind |
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2006-128426 | May 2006 | JP | national |