The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2013-027993, filed Feb. 15, 2013. The contents of this application are incorporated herein by reference in their entirety.
The present disclosure relates to image forming apparatuses, such as electrographic copiers, printers, and facsimile machines, as well as multifunction peripherals combining their functions.
Recent years, amorphous silicon (a-Si) photosensitive drums have been widely used as an image bearing member for an image forming apparatus utilizing an electrographic process. An a-Si photosensitive drum has high hardness and excellent durability, and its characteristics as a photosensitive member are substantially without degradation even after a prolonged usage. Therefore, high image quality can be maintained. That is to say, an a-Si photosensitive drum is an excellent image bearing member for its low running cost, easy handling characteristics, and high level of safety to the environment.
An image forming apparatus using such an a-Si photosensitive drum is known to involve a greater risk of image deletion owing to the characteristics of the a-Si photosensitive member. Image deletion refers to a phenomenon in which an image is blurred or smudged. Image deletion occurs when ion products adhere to the surface of the photosensitive drum and the ion products absorb moisture from the atmosphere. In particular, when the surface of the photosensitive drum is charged by a charging unit, nitrogen oxide (NOx) adheres to the surface of the photosensitive drum. The nitrogen oxide absorbs moisture, causing the latent charges to flow along the surface on which the latent image is formed. As a result, image deletion occurs in the electrostatic latent image formed on the surface of the photosensitive drum. Image deletion tends to occur especially at the edge portions of an electrostatic latent image.
Various methods have been suggested to reduce occurrence of image deletion. In one example, a heating element (heater) is provided inside the photosensitive drum, and a hygrothermograph sensor is provided inside the image forming apparatus. The heating element is heated based on the temperature and humidity measured by the hygrothermograph sensor. With this arrangement, even if moisture adheres to the surface of the photosensitive drum, the moisture can be evaporated. Consequently, occurrence of image deletion can be prevented.
Unfortunately, in the case where the heater is provided inside the photosensitive drum, a sliding electrode is required to connect the heater and the power supply. Therefore, there is a sliding portion connecting the heater to the power supply. As the total rotation time of the photosensitive drum is prolonged, connection failure may occur at the sliding portion.
In view of the above, a suggestion is made to provide the heating element in a static eliminating section. In particular, the static eliminating section includes a substrate, a light-emitting element, and a heating element. The light-emitting element is attached to one main surface of the substrate and emits light toward the photosensitive drum. The light irradiation by the light-emitting element eliminates the charges on the photosensitive drum. The heating element is disposed on the other main surface of the substrate. The heating element heats the photosensitive drum.
An image forming apparatus according to one aspect of the present disclosure includes an image bearing member, a developing unit, a cleaning unit, and a heating element. The image bearing member includes a photosensitive layer. The developing unit forms a toner image by supplying a developing agent containing toner to the image bearing member to cause the toner to adhere to a surface of the image bearing member in conformity with an electrostatic latent image formed on the image bearing member. The cleaning unit removes residual toner from the surface of the image bearing member. The heating element heats the image bearing member. The heating element includes a substrate having a length corresponding to an entire region of the image bearing member in a longitudinal direction of the image bearing member, and a plurality of resistor chips mounted on the substrate. At least either resistance values or spacing intervals of the resistor chips vary in a longitudinal direction of the substrate, thereby causing the image bearing member to have a uniform temperature distribution when heated by the heating element.
The following describes embodiments of the present disclosure, with reference to the accompanying drawings. In the figures, the same or corresponding parts are denoted by the same reference sings, and a description of such parts is not repeated.
The sheet feed cassette 2 is provided with a sheet stacking plate 12. The sheet stacking plate 12 is supported to be freely pivotable about a pivotal fulcrum 12a relative to the sheet feed cassette 2. The pivotal fulcrum 12a is disposed on the rear edge in the sheet conveyance direction. Sheets are stacked on the sheet stacking plate 12. As the sheet stacking plate 12 pivots, the stack of sheets on the sheet stacking plate 12 comes to be pressed by the pickup roller 5. Disposed at a location forward of the sheet feed cassette 2 is a retard roller 13. The retard roller 13 is pressed against the feed roller 6. In the event that the pickup roller 5 simultaneously feeds a plurality of sheets, the sheets are separated by the feed roller 6 and the retard roller 13 so that only the topmost sheet is forwarded.
Having passed through the roller pair made up of the feed roller 6 and the retard roller 13, the sheet is conveyed to the intermediate conveyance roller 7. The intermediate conveyance roller 7 changes the sheet conveyance direction (the recording medium conveyance direction) from the direction toward the front side to the direction toward the rear side of the apparatus. Having passed the intermediate conveyance roller 7, the sheet is conveyed to the image forming section 9 via the registration roller pair 8. The registration roller pair 8 is provided for adjusting the timing for feeding the sheet to the image forming section 9.
The image forming section 9 forms a predetermined toner image on the sheet through an electrographic process. The image forming section 9 includes a photosensitive drum 14, which is one example of an image bearing member, a charging unit 15, a developing unit 16, a cleaning unit 17, a transfer roller 18, which is one example of a transfer member, and a laser scanning unit (LSU) 19. The photosensitive drum 14 is axially supported to be rotatable in the clockwise direction in
In this embodiment, the photosensitive drum 14 is an amorphous silicon (a-Si) photosensitive member. The a-Si photosensitive drum includes a conductive substrate (tubular body) made, for example, of aluminum, an a-Si based photoconductive layer, and a surface protective layer. The a-Si based photoconductive layer is disposed as a photosensitive layer over the conductive substrate (tubular body). The surface protective layer is disposed on the upper surface of the photoconductive layer. The surface protective layer is made from an inorganic insulator or an inorganic semiconductor, such as a-Si based SiC, SiN, SiO, SiON, or SiCN.
When image data is input to the CPU 30 from a higher-level device, such as a personal computer, first, the charging unit 15 uniformly charges the surface of the photosensitive layer included in the photosensitive drum 14. Next, the laser scanning unit (LSU) 19 emits a laser beam based on the inputted image data so as to form an electrostatic latent image on the surface of the photosensitive layer included in the photosensitive drum 14. Then, the developing unit 16 supplies toner to the surface of the photosensitive drum 14. As a result, toner adheres to the surface of the photosensitive drum 14 in conformity with the electrostatic latent image. This forms a toner image on the surface of the photosensitive drum 14. The toner image is then transferred to the sheet fed to a nip portion (transfer position). The nip portion is formed at the contact point between the photosensitive drum 14 and the transfer roller 18. The sheet is fed to the nip portion by the transfer roller 18.
The sheet onto which the toner image has been transferred is separated from the photosensitive drum 14 and conveyed toward the fixing unit 10. The fixing unit 10 is disposed downstream from the image forming section 9 in the sheet conveyance direction. The fixing unit 10 includes a heating roller 22 and a pressure roller 23. The heating roller 22 is one example of a heating member, and the pressure roller 23 is one example of a pressure member. The pressure roller 23 is pressed against the heating roller 22. The sheet to which the toner image has been transferred is heated and pressed by the heating roller 22 and the pressure roller 23. As a result, the toner image transferred to the sheet is fixed. In the manner described above, an image is formed on the sheet by the image forming section 9 and the fixing unit 10. The sheet on which an image has been formed is ejected to the sheet ejecting section 3 by the ejection roller pair 11.
Note that some toner may remain on the surface of the photosensitive drum 14 even after the image transfer. The residual toner is removed by the cleaning unit 17. In addition, after the image transfer, a static eliminating unit 25 (see
As the photosensitive drum 14 rotates in the clockwise direction in
The fixing unit 16 includes a developing roller 16a. The developing roller 16a is one example of a developing-agent bearing member. The developing roller 16a supplies toner to the surface of the photosensitive drum 14. The supplied toner adheres to the surface of the photosensitive drum 14 in conformity with the electrostatic latent image. To the developing unit 16, toner is supplied (fed) from the toner container 20 (see
The cleaning unit 17 includes a slide-and-friction roller 45, a cleaning blade 47, and a toner collecting roller 50. The slide-and-friction roller 45 is one example of a polishing member. The slide-and-friction roller 45 is pressed against the photosensitive drum 14 at a predetermine pressure. In addition, the slide-and-friction roller 45 rotates in the counterclockwise direction shown in
The linear velocity of the slide-and-friction roller 45 is higher than that of the photosensitive drum 14. For example, the linear velocity of the slide-and-friction roller 45 is 1.2 times higher than the linear velocity of the photosensitive drum 14. As an example of its structure, the slide-and-friction roller 45 may adopt a structure in which, for example, a roller body is wrapped around a metal shaft. A foam layer made of EPDM rubber having an Asker C hardness of 55° is usable as a martial of the roller body.
The material of the roller body is not limited to the EPDM rubber mentioned above. The roller body may be made of rubber or foam rubber of a different material. As the material of the roller body, one having an Asker C hardness ranging from 10° to 90° is suitably used. Note that Asker C is one of the durometers (spring type hardness meters) specified in the standard by the Society of Rubber Science and Technology, Japan. In short, Asker C is a device for measuring hardness (hardness meter). The Asker C hardness refers to a hardness measured by Asker C, and a greater value of Asker C hardness indicates material of higher hardness.
The cleaning blade 47 is disposed downstream from the slide-and-friction roller 45 in the rotation direction of the photosensitive drum 14 at the abutment surface between the slide-and-friction roller 45 and the photosensitive drum 14. The cleaning blade 47 is secured in abutment with the photosensitive drum 14. In one example of the cleaning blade 47, a blade made of polyurethane rubber having a JIS hardness of 78° is used. The cleaning blade 47 is secured so as to form a predetermined angle with the tangent to the surface of the photosensitive drum 14 at the point of abutment between the cleaning blade 47 and the photosensitive drum 14. The cleaning blade 47 removes toner remaining on the surface of the photosensitive drum 14 (residual toner) from the surface of the photosensitive drum 14. The material of the cleaning blade 47, the hardness of the cleaning blade 47, the dimensions of the cleaning blade 47, the amount by which the cleaning blade 47 bites into the photosensitive drum 14, the pressure under which the cleaning blade 47 is pressed against the photosensitive drum 14, and so on may be appropriately set according to the specifications of the photosensitive drum 14. Note that the JIS hardness refers to the hardness specified in the Japanese Industrial Standards (JIS).
The toner collecting roller 50 rotates in the clockwise direction in
The transfer roller 18 transfers the toner image formed on the surface of the photosensitive drum 14 to the sheet P being conveyed along the sheet conveyance path 4, without disturbing the toner image. The transfer roller 18 is connected to a transfer bias supply and also to a bias control circuit (both not shown). By the transfer bias supply and the bias control circuit, a transfer bias which is of a reversed polarity to the toner is applied to the transfer roller 18.
The sheet conveyance path 4 has a conveyance surface that is formed by a conveyance-path resin member 51. A heating element 53 is disposed on the conveyance-path resin member 51. The heating element 53 heats the photosensitive drum 14. In
As described above, the heating element 53 that heats the photosensitive drum 14 is disposed outside the photosensitive drum 14. Therefore, a sliding electrode is no longer required to connect the heating element 53 to the power supply, and thus the risk of connection failure is eliminated. In addition, since the heating element 53 is disposed at the opposite side from the developing unit 16 across the straight line L1, heat generated by the heating element 53 is conducted less easily to the developing unit 16. This is effective to prevent precipitation and agglomeration of the toner in the developing unit 16.
In addition, the heating element 53 is accommodated in a concave portion 51a formed in the conveyance-path resin member 51. The concave portion 51a is located closer to the transfer roller 18 than to the photosensitive drum 14. Such disposition of the heating element 53 ensures that the heating element 53 does not obstruct the conveyance of the sheet P along the sheet conveyance path 4. Such disposition is also effective in that the heating element 53 is more distant from the cleaning unit 17. Thus, precipitation and agglomeration of the waste toner in the cleaning unit 17 can be prevented.
In addition, in the image forming apparatus 100 of a horizontal conveyance type as shown in
As shown in
In this way, the substrate 53a is located between the resistor chips 53b and the first inner wall surface of the concave portion 51a. Therefore, the temperature rise of the inner wall surfaces of the concave portion 51a is lessened. In addition, since the space is left between the resistor-chip mounting surface and the partition wall 51b, the air warmed by heat generated by the resistor chips 53b is assisted to flow toward the photosensitive drum 14 (upward in
As shown in
To prevent occurrence of image deletion on the photosensitive drum 14, it has been empirically confirmed that the relative humidity in the vicinity of the photosensitive drum 14 needs to be 60% or below. When the outside air temperature is from 10° C. to 40° C. and the relative humidity is 80%, keeping the relative humidity in the vicinity of the surface of the photosensitive drum 14 below 60% requires that the surface temperature of the photosensitive drum 14 be raised higher than the atmospheric temperature by 6° C. The output power of the heating element 53 required for raising the temperature by 6° C. or more is on the order of 1 W to 3 W.
In addition, the heating element 53 is connected to a power supply circuit 60. The power supply circuit 60 is provided with a switch 55 that can be turned on and off. The switch 55 turns off the conduction of electric current to the heating element 53 during the heating period (conduction period) of the heating roller 22 of the fixing unit 10 (see
The image forming apparatus 100 is provided with intake fans for drawing ambient air into the image forming apparatus 100 for cooling heating members, namely, the fixing unit 10, the laser scanning unit 19, and the like, disposed inside the image forming apparatus 100. According to the first embodiment, the intake fans (not shown) are disposed one on each of the opposing side surfaces (two side surfaces vertical to the plane of
In addition, in the case where the resistor chips 53b having the same resistance value are evenly spaced in the longitudinal direction of the substrate 53a, the heating element 53 involves the following possibility. That is, when the resistance value is determined to sufficiently raise the temperature of the edge portions of the photosensitive drum 14, the central portion of the photosensitive drum 14 may undergo an excessive temperature rise. In this case, the heat may cause precipitation and/or agglomeration of toner in the developing unit 16, which may risk that operation of the developing unit 16 to will be locked. Similarly, a risk may arise that the heat causes precipitation and/or agglomeration of toner in the cleaning unit 17, which may cause operation of the cleaning unit 17 to be locked.
In view of the above, the resistor chips 53b according to the first embodiment are disposed as shown in
The amount of heat generation by the individual resistor chip 53b is proportional to the power consumption W. When I is defined as the electric current flowing upon application of the voltage E to the resistor chip 53b having a resistance value R, the power consumption W is given by the expression W=EI. According to the Ohm's law, E=IR, and thus W=I2R is given. From the above, it can be determined that the amount of heat generation by each resistor chip 53b is proportional to the resistance value R.
That is to say, the 11Ω resistor chips 53b disposed in the edge portions of the substrate 53a each generate more heat than that generated by the individual 10Ω resistor chips 53b disposed in the central portion of the substrate 53a. This arrangement achieves to more effectively heat the edge portions of the photosensitive drum 14. The edge portions tend to have a lower temperature as a result of exposure to the air flow produced by the intake fans. Consequently, the temperature rise variations across the photosensitive drum 14 in the longitudinal direction of the photosensitive drum 14 can be eliminated to reduce occurrence of image deletion.
The heating element 53 shown in
The applicability of the disposition of the resistor chips 53b as shown in
In addition, instead of disposing the resistor chips 53b to have varying resistance values in the longitudinal direction of the substrate 53a, it is applicable to vary the spacing intervals between the resistor chips 53b in the longitudinal direction of the substrate 53a. That is, the density of the resistor chips 53b may be made different from one location to another. In the first embodiment, the resistor chips 53b may be disposed with a smaller spacing interval at the edge portions of the substrate 53a than at the central portion of the substrates 53a. This arrangement achieves to more effectively heat the edge portions of the photosensitive drum 14.
Preferably, the conveyance-path resin member 51 is made from a material having a relative temperature index (hereinafter, RTI) greater than the surface temperature of the heating element 53. The RTI is an index of degradation of the mechanical characteristics (tensile strength and tensile impact strength) and the electrical characteristics (disruptive strength) after prolonged use in an environment associated with exposure to high temperature. The RTI is defined based on UL 746B (the UL Standard for Safety for Polymeric Materials—Long Term Property Evaluations) by Underwriters Laboratories Inc. in the United States of America. For example, a resin having an RTI of 110 means that the resin will have 50% of the initial mechanical characteristics and of the initial electrical characteristics after a 100,000-hour exposure at 110° C. Thus, by keeping the surface temperature of the heating element 53 below the RTI of the conveyance-path resin member 51, the mechanical characteristics and the electrical characteristics of the conveyance-path resin member 51 can be maintained until the end of the useful life of the image forming apparatus 100.
In addition to the polyphenylene sulfide resin mentioned above, examples of the material usable for the conveyance-path resin member 51 include modified-polyphenyleneether (m-PPE) (for example, Xyron SZ800 manufactured by Asahi Kasei Chemicals Corporation).
In addition, the heating element 53 is not conducted at the time of power-up of the image forming apparatus 100. When the conduction of electric current to the heating element 53 is turned on simultaneously with the power-up, the output power of the heating element 53 is low and requires three to four hours until the surface temperature of the photosensitive drum 14 is raised by 6° C. Therefore, when image formation is performed immediately after the power-up under the condition that the relative humidity inside the image forming apparatus 100 is 60% or higher, image deletion may occur. To prevent such occurrence of image deletion, it is preferable to perform drum refresh immediately after the power-up.
The following is an example of a specific method for the drum refresh. First, toner is ejected toward the photosensitive drum 14 from the developing roller 16a included in the developing unit 16. Then, the photosensitive drum 14 and the slide-and-friction roller 45 rotate for a predetermined period of time. Consequently, the surface of the photosensitive drum 14 (the surface of the surface protective layer) is polished by the toner present between the photosensitive drum 14 and the slide-and-friction roller 45.
With this structure, the photosensitive drum 14 is heated by convection of air warmed by the heating element 53 and also directly by radiant heat from the resistor chips 53b. Thus, the photosensitive drum 14 is more efficiently heated as compared to the disposition of the heating element 53 shown in
For cooling the heating members disposed inside the image forming apparatus 100, the image forming apparatus 100 according to the second embodiment is provided with an intake fan (not shown) for drawing ambient air into the image forming apparatus 100. The intake fan is disposed on one of the opposing side surfaces (the side surface further back in
In view of the above, the resistor chips 53b according to the second embodiment are disposed as shown in
That is to say, the 11Ω resistor chips 53b disposed in the one edge portions of the substrate 53a each generate more heat than that generated by the individual 10Ω resistor chips 53b disposed in the central portion and the other edge portion of the substrate 53a. This arrangement achieves to more effectively heat the one edge portion of the photosensitive drum 14 (the end portion further back in
Similarly to the heating element 53 shown in
The image forming apparatus 100 according to the third embodiment includes a retaining member (not shown) for retaining the heating element 53 within a concave portion 51a of a conveyance-path resin member 51. The retaining member is attached to a region R2 located at the central portion of the substrate 53a. Therefore, none of the resistor chips 53b can be mounted in the region R2 of the substrate 53a. As a result, the temperature of the photosensitive drum 14 tends to be lower at the central portion corresponding to the region R2 than at the edge portions of the photosensitive drum 14, which may increase a risk of image deletion at the central portion of the photosensitive drum 14.
In view of the above, the resistor chips 53b according to the third embodiment are disposed as shown in
That is, the resistance values of the resistor chips 53b are gradually higher from the edge portions of the substrate 53a toward the central portion of the substrate 53a. Consequently, the amount of heat generation by the resistor chips 53b increases from the edge portions of the substrate 53a to the central portion of the substrate 53a. This achieves to more effectively heat the region of the photosensitive drum 14 corresponding to the region R2 where none of the resistor chips 53b can be disposed. Consequently, the temperature rise variations across the photosensitive drum 14 in the longitudinal direction of the photosensitive drum 14 can be eliminated to reduce occurrence of image deletion.
As shown in
As shown in
In the fourth embodiment, the sheet P is charged by the transfer bias applied to the transfer roller 18 and thus electrically attracted to the conveyance metal plate 70 that is disposed on the upper surface of the conveyance-path resin member 51. This ensures that the sheet P is attracted toward the upper surface of the conveyance-path resin member 51 and thus smoothly conveyed along the conveyance-path resin member 51. Each rib 71 is disposed on the top surface of the conveyance-path resin member 51 and protrudes beyond the surface of the conveyance metal plate 70. This arrangement keeps the sheet P out of direct contact with the conveyance metal plate 70 and eliminates the risk of bias current flowing into the conveyance metal plate 70.
In addition, the conveyance metal plate 70 is formed from a material having a higher thermal conductivity than that of the conveyance-path resin member 51, and the substrate 53a of the heating element 53 is secured to the conveyance metal plate 70. Examples of the usable materials include: an electrolytic zinc-coated steel sheet (SECC) manufactured by Sumitomo Metal Industries, Ltd. and having a thermal conductivity of 50.0 W/(m·k) for the conveyance metal plate 70; Xyron SZ800 manufactured by Asahi Kasei Chemicals Corporation and having a thermal conductivity from 0.16 W/(m·k) to 0.20 W/(m·k)) for the conveyance-path resin member 51; and CCL-EL190T manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC. and having a thermal conductivity of 0.45 W/(m·k) for the substrate 53a.
Use of such materials enables the conveyance metal plate 70 to function as a heat-dissipating plate (heat sink), so that the conveyance metal plate 70 efficiently dissipates heat conducted from the resistor chips 53b to the substrate 53a. Thus, deterioration and damage of the substrate 53a by heat can be reduced.
As shown in
In view of the above, the resistor chips 53b according to the fourth embodiment are disposed as shown in
Alternatively, a fewer number of resistor chips 53b may be disposed in the regions corresponding to the ribs 71. In this way, the temperature rise variations across the photosensitive drum 14 in the longitudinal direction of the photosensitive drum 14 may likewise be eliminated by varying the spacing intervals of the resistor chips 53b.
The present disclosure is not limited to the first to fourth embodiments described above, and various modifications are possible within a scope not departing from the gist of the present disclosure. For example, according to the first to fourth embodiments, either the resistance values or the spacing intervals of the resistor chips 53b are varied along the longitudinal direction of the substrate 53a. Alternatively, both the resistance values and the spacing intervals of the resistor chips 53b can be varied along the longitudinal direction of the substrate 53a.
In addition, alternatively to the charging unit 15 of a contact charging type that includes the charging roller 41 as shown in
In addition, the image forming apparatus according to the present disclosure is not limited to a monochrome printer as shown in
In the image forming apparatus 100 according to the first to fourth embodiments described above, the heating element 53 for heating the photosensitive drum 14 includes the substrate 53a and the plurality of resistor chips 53b mounted on the substrate 53a. The substrate 53a extends correspondingly to the entire region of the photosensitive drum 14 in the longitudinal direction of the photosensitive drum 14. To ensure that the photosensitive drum 14 is heated by the heating element 53 to have a uniform surface temperature distribution, the resistor chips 53b are disposed so that at least either the resistance values or the spacing intervals of the resistor chips 53b varies along the longitudinal direction of the substrate 53a. With this arrangement, the temperature rise variations across the photosensitive drum 14 in the longitudinal direction of the photosensitive drum 14 can be efficiently eliminated to reduce occurrence of image deletion. This is achieved even when an air flow is present around the photosensitive drum 14 or a region of the substrate 53a is used for retaining the substrate 53a and thus not available for mounting a resistor chip.
The following specifically describes advantageous effects of the present disclosure by way of examples.
As Example 1, an image forming apparatus 100 was prepared which was provided with intake fans one on each side surface of the image forming apparatus 100 (one at the front and the other at the rear) facing the respective edge portions of a photosensitive drum 14. The image forming apparatus 100 of Example 1 includes the heating element 53 shown in
Tests 1 and 2 were conducted under the same testing conditions. In particular, the respective image forming apparatuses 100 were installed in a room with a temperature of 25° C. The target temperature for raising the surface temperature of the photosensitive drum was set to 31° C. The direct voltage of 24 V was applied to the heating element 53. The surface temperature of the photosensitive drum 14 was measured at locations A-E in the respective regions determined by equally dividing the photosensitive drum 14 in the direction from the front to the rear of the image forming apparatus 100 (in
In
In addition, the value of the electric current flowing through the heating element 53 of the image forming apparatus 100 was 0.0909 A in Example 1 and 0.0857 A in that of Comparative Example 1. It follows that the power consumption W of the heating element 53 of Example 1 is calculated to be W=I2R=(0.0909)2×{(10×22)+(11×4)}=(0.0909)2×264 2.181 W. On the other hand, the power consumption W of the heating element 53 of Comparative Example 1 is calculated to be W=I2R=(0.0857)2×(10×28) 2.056 W. It means that there was no substantial difference in the power consumption between the image forming apparatus 100 of Example 1 and the image forming apparatus 100 of Comparative Example 1.
As Example 2, an image forming apparatus 100 was prepared which was provided with an intake fan on one side surface (one at the rear) facing one edge portion of a photosensitive drum 14. The image forming apparatus 100 of Example 2 includes the heating element 53 shown in
In
In addition, the value of the electric current flowing through the heating element 53 of the image forming apparatus 100 was 0.0882 A in Example 2. It follows that the power consumption W of the heating element 53 of Example 2 is calculated to be W=I2R=(0.0882)2×{(10×25)+(11×2)}=(0.0882)2×272≈2.116 W. On the other hand, the power consumption W of the heating element 53 of Comparative Example 2 was 2.056 W, which is the same as Comparative Example 1. It means that there was no substantial difference in the power consumption between the image forming apparatus 100 of Example 2 and the image forming apparatus 100 of Comparative Example 2.
As Example 3, an image forming apparatus 100 was prepared which includes a retaining member for retaining the heating element 53. The retaining member was attached to the region R2 in the central portion of the substrate 53a. The image forming apparatus 100 of Example 3 includes the heating element 53 shown in
In
In addition, the value of the electric current flowing through the heating element 53 of the image forming apparatus 100 was 0.0857 A in Example 3. In addition, the value of the electric current flowing through the heating element 53 of the image forming apparatus 100 was 0.0909 A in Comparative Example 3. It follows that the power consumption W of the heating element 53 of Example 3 is calculated to be W=I2R=(0.0857)2×{(11×12)+(12×8)+(13×4)}=(0.0857)2×280≈2.056 W. On the other hand, the power consumption W of the heating element 53 of Comparative Example 3 is calculated to be W=I2R=(0.0909)2×(11×24)≈2.181 W. It means that there was no substantial difference in the power consumption between the image forming apparatus 100 of Example 3 and the image forming apparatus 100 of Comparative Example 3.
Each test described above confirms the effect achieved by adjusting the resistance values of the resistor chip 53b to ensure a uniform temperature distribution of the photosensitive drum 14 across the longitudinal direction of the photosensitive drum 14. That is, the temperature variations of the photosensitive drum 14 across the longitudinal direction of the photosensitive drum 14 were eliminated and thus occurrence of image deletion was effectively reduced. Although not disclosed herein, it is confirmed that the uniform temperature distribution of the photosensitive drum 14 across the longitudinal direction of the photosensitive drum 14 can also be achieved by changing the spacing intervals of the resistor chips 53b mounted on the substrate 53a.
Number | Date | Country | Kind |
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2013-027993 | Feb 2013 | JP | national |