Patent Grant
10534306
1. Field of the Invention
The present invention relates to a base body, an electrophotographic photoreceptor, and an image forming apparatus including the same.
2. Description of the Related Art
An electrophotographic photoreceptor used in an image forming apparatus, for example, an electrophotographic photoreceptor having a cylindrical base body and a photoconductive layer is known (for example, Japanese Unexamined Patent Publication JP-A 2017-155269).
Such an image forming layer is required to stabilize printing quality.
A cylindrical base body of the present disclosure includes an outer peripheral surface and an end surface connected to the outer peripheral surface. The outer peripheral surface has a first inclined surface which is inclined inwardly toward the end surface, the end face has a second inclined surface which is inclined inwardly toward the outer peripheral surface and is connected to the first inclined surface, and a connecting portion of the first inclined surface and the second inclined surface has a radiused surface.
An electrophotographic photoreceptor of the present disclosure includes the above-described cylindrical base body and a photoconductive layer which is disposed on the cylindrical base body from the end surface to the outer peripheral surface of the cylindrical base body.
An image forming apparatus of the present disclosure includes the above-described electrophotographic photoreceptor and an exposure device which irradiates the electrophotographic photoreceptor with light.
According to the cylindrical base body, the electrophotographic photoreceptor, and the image forming apparatus of the present disclosure, it is possible to stabilize the printing quality in the image forming apparatus.
Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:
Hereinafter, a base body and an electrophotographic photoreceptor according to an embodiment of the invention and an image forming apparatus including the same will be described with reference to drawings. The following contents illustrate the embodiments of the invention, and the invention is not limited to the example of the embodiment.
An electrophotographic photoreceptor 10 has a cylindrical shape and is incorporated into an image forming apparatus to be described later, and may form an image by rotating around a rotation axis extending along a longitudinal direction of the cylindrical shape.
Referring to
The electrophotographic photoreceptor 10 may be formed by sequentially forming the voltage resistance layer 11, the charge injection blocking layer 12, the photoconductive layer 13, and the surface protective layer 14 on the base body 1 using a deposition film forming apparatus, for example.
The base body 1 may support the plurality of layers 2. At least the surface of the cylindrical base body 1 has conductivity. The cylindrical base body 1 may be formed to have conductivity as a whole by a metal material such as aluminum (Al), stainless steel (SUS), zinc (Zn), copper (Cu), iron (Fe), Titanium (Ti), nickel (Ni), chromium (Cr), tantalum (Ta), tin (Sn), gold (Au), silver (Ag), magnesium (Mg), and manganese (Mn), or an alloy including these exemplified metal materials.
The cylindrical base body 1 may be coated with a conductive film made of the exemplified metal material and a transparent conductive material such as indium tin oxide (ITO) or SnO2 (tin dioxide) on a surface of a resin, glass, ceramics, or the like.
When the base body 1 is formed of an aluminum (Al) based material, the electrophotographic photoreceptor 10 may be produced lightweight at low cost. When the charge injection blocking layer 12 and the photoconductive layer 13 are formed of an amorphous silicon (a-Si) based material, the adhesion between the charge injection blocking layer 12, the photoconductive layer 13, and the base body 1 is increased, thereby improving the reliability.
Referring to
The outer peripheral surface 1a is a mirror surface or a rough surface. When the outer peripheral surface 1a is a mirror surface, the surface roughness of the outer peripheral surface 1a may be, for example, an arithmetic mean height Sa of less than 25 nm. In the embodiment, a region (surface region) where the arithmetic mean height Sa of the surface is less than 25 nm is referred to as a “mirror surface”.
On the other hand, when the outer peripheral surface 1a is a rough surface, the surface roughness of the outer peripheral surface 1a may have, for example, the arithmetic mean height Sa of 50 nm or more and 140 nm or less. In the embodiment, a region (surface region) where the arithmetic mean height Sa of the surface is 25 nm or more is called “rough surface”.
The arithmetic mean height Sa used in the specification is one of parameters representing a three-dimensional surface texture defined by ISO 25178 and represents the arithmetic average (nm) of the absolute value of the height from the average plane of the surface in the measurement target region. For this measurement, the surface shape has been measured by three-dimensional roughness parameters according to ISO 25178 by a three-dimensional measurement laser microscope OLSA 4100 manufactured by Olympus Corporation.
The surface roughness of the base body 1 does not necessarily have to fall within a predetermined range on the entire outer peripheral surface 1a. For example, the surface texture may fall outside the range at both axial ends of the cylindrical base body 1.
The outer peripheral surface of the base body 1 according to the embodiment is a mirror surface.
The base body 1 further includes an end surface 1b connected to the outer peripheral surface 1a. The end surface 1b is a surface which intersects a direction of the rotation axis of the cylindrical base body 1. That is, when the base body 1 is regarded as a cylindrical column, the surface of the portion corresponding to the bottom surface of the cylindrical column is defined as the end surface 1b.
The outer peripheral surface 1a of the base body 1 includes a first inclined surface 1c. The first inclined surface 1c is inclined inwardly toward the end surface 1b. In other words, the first inclined surface 1c is inclined so that a length in a radial direction of the cylindrical base body 1 is reduced.
The end surface 1b of the base body 1 includes a second inclined surface 1d. The second inclined surface 1d is inclined inwardly toward the outer peripheral surface 1a. In other words, the second inclined surface 1d is inclined so that a length in an axial direction of the cylindrical base body 1 is reduced.
The first inclined surface 1c and the second inclined surface 1d are connected to each other. A connecting portion of the first inclined surface 1c and the second inclined surface 1d has a radiused surface.
The plurality of layers 2 are disposed on the base body 1 from the end surface 1b to the outer peripheral surface 1a of the base body 1. More specifically, the plurality of layers 2 are disposed at least from the second inclined surface 1d to the outer peripheral surface 1a.
Here, for example, when the outer peripheral surface or the end surface of the base body has no inclined surface, or when the connecting portion of the outer peripheral surface and the end surface has no radiused surface, for example, due to a difference in thermal expansion amount between the base body and the plurality of layers, a part of the plurality of layers may be peeled off from the connecting portion of the outer peripheral surface and the end surface. The part of the plurality of peeled layers is mixed during printing, which sometimes deteriorates the printing quality.
On the contrary, since the invention of the present disclosure includes the above-described configuration, it is possible to increase an angle of the connecting portion of the outer peripheral surface 1a and the end surface 1b, thereby reducing stress concentration at the connection portion due to thermal expansion of the base body and the plurality of layers 2. Also, since the connecting portion of the outer peripheral surface 1a and the end surface 1b has the radiused surface in the invention of the present disclosure, it is possible to further reduce stress concentration at the connection portion due to thermal expansion of the base body 1 and the plurality of layers 2. Therefore, it is possible to reduce peeling of a part of the plurality of layers 2 and to further stabilize the printing quality in the image forming apparatus.
An angle (a first angle θ1) with respect to a first direction D1 along the rotation axis of the base body 1 of the first inclined surface 1c is set to, for example, 10° or more and 30° or less. The first angle θ1 of the first inclined surface 1c may be 25° or less. In this case, as shown in Table 1, it is possible to reduce the peeling of a part of a plurality of layers 2 at a connecting portion of the first inclined surface 1c and a first non-inclined surface 1e of the outer peripheral surface 1a.
The “first angle” in Table 1 indicates the first angle θ1 of the first inclined surface 1c, and “presence or absence of peeling off” is a result of observing whether or not a part of the plurality of layers 2 has peeled off when the first angle θ1 is changed. The presence or absence of peeling off is determined by visual observation or observation using a microscope. A ratio of peeling off in the circumferential direction indicates an area ratio of the film peeling on the circumference at the first inclined surface 1c. For example, when the film peeling is not observed on the circumference at the first inclined surface 1c, the ratio of peeling off in the circumferential direction is defined as 0%. When the film peeling is observed on half of the circumference in terms of area ratio, the ratio of peeling off in the circumferential direction is defined as 50%. When the film peeling is observed on the entire circumference, the ratio of peeling off in the circumferential direction is defined as 100%.
The first angle θ1 of the first inclined surface 1c may be 15° or more. In this case, it is possible to shorten the dimension in the first direction D1 and ensure a wide image area.
In the embodiment, the first angle θ1 of the first inclined surface 1c is set to 20°.
The first inclined surface 1c is flat. As a result, in the case of roughening the outer circumferential surface of the base body 1 or mirror surface processing, it is possible to reduce the influence of variation in a turning tool contact position and maintain the first angle θ1.
A second angle θ2 with respect to a second direction D2 orthogonal to the rotation axis (or the first direction D1) of the base body 1 of the second inclined surface 1d is set to, for example, 5° or more and 10° or less. By having the second inclined surface 1d on the end surface 1b, it is possible to reduce wraparound of the plurality of layers 2. In the embodiment, the second angle θ2 of the second inclined surface 1d is set to 7°.
The second inclined surface 1d is flat. As a result, it is possible to reduce wraparound of the plurality of layers 2.
A third angle θ3 at which the virtual straight line of the first inclined surface 1c intersects the virtual straight line of the second inclined surface 1d may be 90° or more and 180° or less. In the embodiment, the third angle θ3 is set to 117°.
The first angle θ1 of the first inclined surface 1c may be larger than the second angle θ2 of the second inclined surface 1d. As a result, it is possible to reduce wraparound of the plurality of layers 2 with respect to the second direction D2.
The radius of the radiused surface of the connecting portion of the first inclined surface 1c and the second inclined surface 1d may be, for example, 0.05 mm to 0.5 mm. In the embodiment, the radius of the radiused surface is set to 0.08 mm.
A linear component along the first direction D1 of the first inclined surface 1c may be larger than a linear component along the second direction D2 of the second inclined surface 1d in the side sectional view passing through the rotation axis. As a result, even when the surface of the base body 1 is cut during the processing of the surface of the base body 1 or the like, it is possible to reduce the loss of the first inclined surface 1c. At least a linear component L1 along the first direction D1 of the first inclined surface 1c may be larger than a linear component L2 along the first direction D1 of the second inclined surface 1d before forming the plurality of layers 2.
In the base body 1 according to the embodiment, the linear component along the first direction D1 of the first inclined surface 1c before forming the plurality of layers 2 is, for example, 0.1 mm to 0.6 mm when the rotation axis is viewed from the side section. The linear component along the second direction D2 of the first inclined surface 1c is, for example, 0.05 mm to 0.4 mm. The linear component along the first direction D1 of the second inclined surface 1d is, for example, 0.02 mm to 0.1 mm. The linear component along the second direction D2 of the second inclined surface 1d is, for example, 0.2 mm to 0.5 mm.
The base body 1 may be formed by a well-known method in the related art.
Each layer of the plurality of layers 2 will be described below.
The voltage resistance layer 11 may improve the withstand voltage characteristics of the surface coating layer. The voltage resistance layer 11 may be a layer containing amorphous silicon nitride (a-SiN). The ratio (N/(Si+N)) of the number of nitrogen atoms to the total number of nitrogen atoms and silicon atoms in the voltage resistance layer 11 may be set to 0.32 or less. By setting the ratio of silicon atoms and nitrogen atoms in such a range, it is possible to appropriately ensure withstand voltage characteristics in a plurality of layers 2 and appropriately suppress generation of residual potential. For the voltage resistance layer 11, for example, amorphous silicon (a-Si) containing at least nitrogen (N) as a dopant may be used. The thickness of the voltage resistance layer 11 is, for example, 0.5 to 15 μm. The voltage resistance layer 11 is also referred to as a withstand voltage layer or a withstand voltage holding layer.
The charge injection blocking layer 12 may reduce the injection of carriers (electrons or holes) from the cylindrical base body 1. The charge injection blocking layer 12 may be formed of, for example, an amorphous silicon (a-Si) based material. For the charge injection blocking layer 12, for example, amorphous silicon (a-Si) containing boron (B) as a dopant and optionally nitrogen (N) or oxygen (O) or both, or amorphous silicon (a-Si) containing phosphorus (P) and optionally nitrogen (N) or oxygen (O) or both may be used. A thickness of the charge injection blocking layer 12 is, for example, 2 to 10 μm.
The photoconductive layer 13 may generate carriers by light irradiation such as laser light. The photoconductive layer 13 may be formed of, for example, an amorphous silicon (a-Si) based material and an amorphous selenium (a-Se) based material such as Se—Te or As2Se3. The photoconductive layer 13 of the present example is formed of amorphous silicon (a-Si) and an amorphous silicon (a-Si) based material obtained by adding carbon (C), nitrogen (N), oxygen (O) and the like to amorphous silicon (a-Si), and boron (B) or phosphorus (P) is contained as a dopant. In the case of forming the photoconductive layer 13 using an amorphous silicon (a-Si) based material, a thickness thereof may be set to about 5 to 100 μm, or more specifically 10 to 80 μm.
The surface protective layer 14 may protect the surface of the photoconductive layer 13. For example, an amorphous silicon (a-Si) based material such as amorphous silicon carbide (a-SiC) or amorphous silicon nitride (a-SiN) or amorphous carbon (a-C) may be used for the surface protective layer 14, or a multilayer structure thereof may be adopted. In the present example, amorphous carbon (a-C) with high durability is adopted for the surface protective layer 14, which is the outermost surface after formation of the layers, in terms of the wear resistance against rubbing in the image forming apparatus. A thickness of the surface protective layer 14 may be adjusted according to the required number of durable sheets of the electrophotographic photoreceptor 10, and it is not necessary to make the surface protective layer 14 thicker than necessary. For example, the thickness should be set to 0.1 to 2 μm, or more specifically 0.5 to 1.5 μm.
The plurality of layers 2 may be formed using a plasma chemical vapor deposition (CVD) apparatus. More specifically, a plurality of base bodies 1 may be placed to be stacked in the first direction D1, and gases are introduced for formation of each layer, whereby the plurality of layers 2 may be formed.
Next, an image forming apparatus according to the embodiment of the invention will be described with reference to
An image forming apparatus 100 employs the Carlson process as an image forming process and includes the electrophotographic photoreceptor 10, a charging device 111, an exposure device 112, a developing device 113 including a developing roller 113A, a transfer device 114, a fixing device 115 (115A and 115B), a cleaning device 116 including a cleaning roller 116B and a cleaning blade 116A in contact with the electrophotographic photoreceptor 10, and a static eliminating device 117. An arrow x in the drawing indicates a moving direction of a paper sheet which is a recording medium P.
The charging device (charging roller) ill has a function of charging the surface of the electrophotographic photoreceptor 10 with negative polarity. In the embodiment, the charging device 111 employs, for example, a contact-type charging device configured by covering a core metal with a conductive rubber or polyvinylidene fluoride (PVDF).
The exposure device 112 has a function of forming an electrostatic latent image on the electrophotographic photoreceptor 10. As the exposure device 112, for example, a light emitting diode (LED) head where a plurality of LED elements (wavelength: 680 nm) are arrayed may be adopted.
The developing device 113 has a function of developing an electrostatic latent image of the electrophotographic photoreceptor 10 to form a toner image. The developing device 113 in the present example includes the developing roller 113A magnetically holding a developer (toner) T.
The developer (toner) T is configured to have a toner image formed on the surface of the electrophotographic photoreceptor 10 and is frictionally charged in the developing device 113. Examples of the toner T include a two-component type developer containing a magnetic carrier and an insulating toner and a one-component developer containing a magnetic toner.
A magnetic roller 113A has a function of transporting the toner T to the surface (development area) of the electrophotographic photoreceptor 10. The magnetic roller 113A transports the frictionally charged developer T in the developing device 113 in the form of a magnetic brush adjusted to a constant length. The transported toner T adheres to the surface of the electrophotographic photoreceptor 10 due to the electrostatic attraction with the electrostatic latent image in the development area of the electrophotographic photoreceptor 10 to form a toner image (to visualize the electrostatic latent image).
In the present example, the developing device 113 employs a dry developing process, but a wet developing process using a liquid developer may be adopted. In some cases, a transporting screw (spiral type) for stirring unused toner T may be disposed in the developing device 113.
The transfer device 114 has a function of transferring the toner image of the electrophotographic photoreceptor 10 to the recording medium P such as a paper supplied to a transfer area between the electrophotographic photoreceptor 10 and the transfer device 114. The transfer device 114 in the present example includes a transfer charger 114A and a separating charger 114B.
As the transfer device 114, it is also possible to use a transfer roller driven by the rotation of the electrophotographic photoreceptor 10 and disposed with a minute gap (for example, 0.5 mm or less) from the electrophotographic photoreceptor 10. The transfer roller is configured to apply a transfer voltage which attracts the toner image on the electrophotographic photoreceptor 10 onto the recording medium P by, for example, a DC power supply.
The fixing device 115 has a function of fixing the toner image transferred onto the recording medium P and includes a pair of fixing rollers 115A and 115B. The fixing rollers 115A and 115B are, for example, metal rollers coated with tetrafluoroethylene or the like.
The cleaning device 116 has a function of removing the toner T remaining on the surface of the electrophotographic photoreceptor 10 and includes the cleaning roller 116B and the cleaning blade 116A. The cleaning roller 116B has a crown shape with a large diameter at the center, and is in sliding contact with the outer periphery of the electrophotographic photoreceptor 10 to form a toner film for surface cleaning formed of a residual toner T therebetween. The cleaning blade 116A has a function of scraping the residual toner from the surface of the electrophotographic photoreceptor 10. The cleaning blade 116A is formed of, for example, a rubber material containing polyurethane resin as a main component.
The static eliminating device 117 has a function of removing the surface charge of the electrophotographic photoreceptor 10 and is capable of emitting light having a specific wavelength (for example, 630 nm or more). The static eliminating device 117 is configured to remove the surface charge (residual electrostatic latent image) of the electrophotographic photoreceptor 10 by irradiating the entire axial direction of the surface of the electrophotographic photoreceptor 10 with light from a light source such as an LED.
In the image forming apparatus 100 of the embodiment, the above-described effects of the electrophotographic photoreceptor 10 may be exerted.
It is needless to say that the invention is not limited only to the above-described embodiments, and thus various changes, modifications and improvements are possible without departing from the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-236341 | Dec 2017 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20080003016 | Nakano | Jan 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 2017-155269 | Sep 2017 | JP |
| Entry |
|---|
| International Search Report dated Jun. 6, 2017, in corresponding International Application No. PCT/JP2017/009280. |
| Number | Date | Country | |
|---|---|---|---|
| 20190179248 A1 | Jun 2019 | US |
