JP5145651B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

  The present invention is an optical scanning method in which a light beam from a light source is deflected by an optical deflector and condensed as a light spot on a photoconductive photoconductor by a scanning imaging optical system attached to an optical housing to scan the photoconductor. The present invention relates to an apparatus and an image forming apparatus using the optical scanning device.

  2. Description of the Related Art In recent years, image forming apparatuses such as laser printers and digital copying machines using the above-described optical scanning apparatus are well known. In this type of image forming apparatus, a polygonal mirror 100 having a regular hexagonal plan shape as shown in FIG. The polygon mirror 100 is rotated in the counterclockwise direction indicated by the arrow. At this time, turbulence is generated due to the negative pressure phenomenon of air. Due to this turbulent flow, dust, fine particles, etc. in the air in the optical scanning device are struck against the surface of the polygon mirror 100 at the A portion on the rear side of each corner with respect to the rotation direction of the polygon mirror 100. There was a problem that the part A was contaminated due to this phenomenon. If the surface of the polygon mirror 100 is contaminated, the reflectance of the polygon mirror 100 may be reduced, and contamination of the polygon mirror 100 may deteriorate the image quality.

Japanese Patent No. 3652238 JP-A-11-218710

  Therefore, in Patent Document 1, it is difficult to eliminate or reduce the contamination of the polygon mirror described above with a simple configuration. Therefore, in the A portion of each reflecting surface that easily contaminates synchronous detection in order to control the exposure timing in the main scanning direction. In other words, it is disclosed to use a portion B that is relatively free from dirt.

Further, Patent Document 2 discloses that contamination is prevented by neutralizing a polygon mirror so that the contamination is difficult to adhere.
However, in Patent Document 1, it is inevitable that the polygon mirror becomes dirty due to use over time. If the image quality deteriorates due to this, the polygon mirror needs to be cleaned or replaced. In addition, Patent Document 2 is not an active measure to remove the cause of dirt, but it is difficult to get dirt, so that it can sufficiently cope with the increase in the amount of dirt particles and dirt caused by turbulent flow. It was not possible to prevent the adhesion of dirt over time.

  In view of the above-described conventional circumstances, an object of the present invention is to provide an optical scanning device and an image forming apparatus that can significantly reduce contamination of a polygon mirror due to turbulent flow.

In order to achieve the above object, according to the present invention, a light beam from a light source is deflected by an optical deflector, and is condensed as a light spot on a photoconductive photoreceptor by a scanning imaging optical system attached to an optical housing. An optical scanning device that scans a photosensitive member includes an electrostatic adsorption filter that collects fine particles and the like, a sheet having air permeability, and a frame, and the electrostatic adsorption filter is sandwiched between the sheets and the static adsorption filter is disposed. A collection member having a structure integrated with the frame body in a state of preventing scattering of members constituting the electroadsorption filter is provided, and the collection member is placed at a position where an air flow generated by the rotation of the optical deflector directly hits. There is proposed an optical scanning device characterized in that an upper surface of the optical deflector and the wall surface of the optical housing are arranged with a space between the wall surface via a leg portion .

Furthermore, the present invention is effective when the electrostatic adsorption filter is a highly charged electrostatic adsorption filter in which a fibrous member is formed in a short chain shape .

Furthermore, the present invention is effective when the collection member is locally fastened around the anti-scattering sheet covering the highly charged electrostatic adsorption filter.
Furthermore, the present invention is effective when the collecting member is fastened all around the scattering prevention sheet covering the highly charged electrostatic adsorption filter.

In order to achieve the above object, according to the present invention, a light beam from a light source is deflected by an optical deflector and collected as a light spot on a photoconductive photosensitive member by a scanning imaging optical system attached to an optical housing. In an optical scanning device that scans a photoconductor by light, an electrostatic adsorption filter that collects fine particles and the like, a sheet having air permeability, and a frame are provided, and the electrostatic adsorption filter is sandwiched between the sheets. A collecting member having a structure integrated with the frame body in a state of preventing scattering of members constituting the electrostatic adsorption filter is provided, and the collecting member directly receives an air flow generated by rotation of the optical deflector. The upper surface of the optical deflector, which is the position, is disposed on the wall surface of the optical housing with a space between the wall surface and a gap via a leg portion, and the sheet is charged more than the electrostatic adsorption filter. It proposes an optical scanning device which is a Sai electrostatic adsorption filter.
In addition, this invention is effective in the said sheet | seat being a mesh member provided with the porosity.

  Furthermore, the present invention is effective when a reinforcing net is provided on one surface of the scattering prevention sheet.

In order to achieve the above object, the present invention proposes an image forming apparatus comprising the optical scanning device according to any one of claims 1 to 7 .

  According to the present invention, it is possible to reliably prevent dirt from adhering to the polygon mirror by collecting dust and fine particles that cause contamination of the polygon mirror, and to prevent dirt by using a highly charged electrostatic adsorption filter. Even if the effect is enhanced, adverse effects caused by using a highly charged electrostatic adsorption filter can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory view showing the internal configuration of a light beam printer as an image forming apparatus according to the present invention.

  The digital copying machine shown in FIG. 1 includes an image reading device 1, a printer unit 2 having a laser beam scanning device, and an automatic document feeder 3. The automatic document feeder 3 conveys the set documents one by one, sets them on the contact glass 4, and discharges the documents on the contact glass 4 after the completion of copying.

  FIG. 2 shows a document reading apparatus 1, which includes a first carriage A equipped with a light source including an illumination lamp 5 and a reflecting mirror 6 and a first mirror 7, a second mirror 8 and a third mirror 9. And a second carriage B equipped with When reading a document, the first carriage A moves forward at a constant speed, and the second carriage B follows the first carriage A at a speed ½ that of the first carriage A. The original is optically scanned, the original on the contact glass 4 is illuminated by the illumination lamp 5 and the reflecting mirror 6, and the reflected light image passes through the first mirror 7, the second mirror 8, the third mirror 9, and the color filter 10. The image is formed on the CCD sensor 12 by the lens 11. The CCD sensor 12 photoelectrically converts the reflected light image of the imaged document, outputs an analog image signal, and reads the document. Then, after the image reading is completed, the first carriage A and the second carriage B return to the home position. It is to be noted that a color original can be read by using a three-line CCD provided with R (red), G (green), and B (blue) filters as the CCD sensor. Reference numeral 14 denotes a fan for cooling the inside of the document reading apparatus 1.

  The analog image signal from the CCD sensor 12 is converted into a digital image signal by an analog / digital converter, and various image processing (binarization, multi-value conversion, gradation processing, scaling processing, Editing process).

  In the printer unit 2, the photosensitive drum 15 as an image carrier is rotationally driven by the driving unit during the copying operation and is uniformly charged by the charging device 16, and then image processing is performed on the image processing plate 13. A digital image signal is sent to a semiconductor drive plate (not shown), and image exposure using the digital signal is performed by a laser beam scanning device 17 which is an optical scanning device, thereby forming an electrostatic latent image. Then, the electrostatic latent image on the photosensitive drum 15 is developed by the developing device 18.

  The transfer paper is fed from the selected one of the paper feeding devices 23 to 25 to the registration roller 26 and sent out in time with the image on the photosensitive drum 15 by the registration roller 26, and is transferred onto the photosensitive drum by the transfer device 20. The formed visible image is transferred onto the transfer paper. Then, the transfer paper is separated from the photosensitive drum 15 by the separation device 21, conveyed by the conveyance device 27, fixed by the fixing device 28, and then discharged as a copy onto the tray 29. Further, the photosensitive drum 15 is cleaned by the cleaning device 22 after the transfer paper is separated, and the residual toner is removed.

  As shown in FIG. 3, the laser beam scanning device 17 is provided with a semiconductor laser unit 30, a cylindrical lens 31, a polygon mirror 32, an fθ lens 34, a reflecting mirror 35, a dust-proof glass 36, and the like in an optical housing 40. A cover 41 is attached to the upper portion thereof to form a substantially sealed structure.

  In the laser beam scanning device 17, a laser beam emitted from a semiconductor laser in the semiconductor laser unit 30 is converted into a parallel light beam by a collimating lens in the semiconductor laser unit 30 and passes through an aperture provided in the semiconductor laser unit 30. Thus, the light beam is shaped into a fixed shape. This light beam is compressed in the sub-scanning direction by the cylindrical lens 31 and enters the polygon mirror 32. The polygon mirror 32 has an accurate polygon shape, and is driven to rotate at a constant speed in a constant direction by a polygon motor 33. The rotation speed of the polygon mirror 32 is determined by the rotation speed of the photosensitive drum 15, the writing density of the laser beam scanning device 17, and the number of surfaces of the polygon mirror 32. The laser beam incident on the polygon mirror 32 from the cylindrical lens 31 is deflected by the reflection surface of the polygon mirror and enters the fθ lens 34. The fθ lens 34 converts the scanning light having a constant angular velocity from the polygon mirror 32 so that it is scanned at a constant velocity by the photosensitive drum 15, and the laser beam from the fθ lens 34 passes through the reflecting mirror 35 and the dust-proof glass 36. The image is formed on the photosensitive drum 15. The fθ lens 34 also has a surface tilt correction function. Further, the laser beam that has passed through the fθ lens 34 is reflected by the synchronization detection mirror 37 outside the image area and is guided to the synchronization detection sensor 38. A synchronization signal serving as a reference for cueing in the main scanning direction is obtained from the detection output of the synchronization detection sensor 38.

  The laser beam scanning device 17 includes a large number of optical components whose optical performance is remarkably deteriorated due to adhesion of fine particles in the air. In particular, the polygon mirror 32 that rotates at high speed easily adheres to the fine particles contained in the air in the optical unit, and has a tendency to adhere depending on the rotation direction. As described above, the reflectance may be changed in the scanning direction to cause uneven density on the image.

  This problem can be alleviated by providing an electrostatic adsorption filter in the vicinity of the polygon mirror 32 so as to collect dust and fine particles that cause contamination. The electrostatic adsorption filter is formed of a fibrous member, and the fibrous member is shortened to be highly charged, so that the dust collection performance can be enhanced. However, if a high electrostatic attraction filter is used to collect dust efficiently, the possibility that the fibrous member constituting the filter will fall off due to airflow, gravity, vibration, or the like increases. If the fibrous member falls off, scatters, and adheres to a lens or the like, it causes a serious deterioration in the image in the optical scanning device.

Therefore, the present invention takes the following measures.
FIG. 4 shows a collecting member 50 according to an embodiment of the present invention. The collecting member 50 integrates a plurality of sheet-like members including a highly charged electrostatic adsorption filter 51 that collects fine particles and the like. It has the structure. Specifically, a highly charged electrostatic adsorption filter 51 is sandwiched between two air permeable anti-scattering sheets 52 and 53, whereby the anti-scattering sheets 52 and 53 are highly charged electrostatic adsorption filter 51. The fibrous member is prevented from being scattered by air current, gravity, vibration or the like.

Next, different embodiments of the collecting member 50 applied to the present invention will be described with reference to FIGS.
The collection member 50 shown in FIG. 5 has a configuration in which a plurality of sheets and a frame 60 are integrated by molding. That is, the collecting member 50 is configured to be integrally formed with the frame body 60 in a state where the highly charged electrostatic adsorption filter 51 is sandwiched between the scattering prevention sheets 52 and 53. Therefore, scattering of the fibrous member of the electrostatic adsorption filter 51 in the collection member 50 is prevented by the scattering prevention sheets 52 and 53.

  Since the collection member 50 configured as described above can be mounted in the optical housing 40 via the frame body 60, the collection member 50 can be easily attached and detached, and the frame body is attached to the seat group. It is cheaper than the one to be installed.

  6 (a) and 6 (b), a collecting member 50 shown in FIGS. 6 (a) and 6 (b) is formed by sandwiching a highly charged electrostatic adsorption filter 51 between two air-permeable sheets 52 and 53, and overlapping several locations on the outer periphery thereof. Fastened and integrated. Reference numeral 54 indicates the fastening portion. Moreover, as a fastening method, methods such as heat welding by applying heat and caulking for fastening by applying physical pressure can be considered. Further, a method using another member such as a stapler, eyelet, rivet, clip, etc. can be considered. It is possible to properly use what suits your needs.

  The collecting member 50 shown in FIGS. 7A and 7B is also formed by sandwiching a highly charged electrostatic adsorption filter 51 between two air-permeable sheets 52 and 53 and overlapping them. Although the fastening method of the collection member 50 shown can be used, it differs from the collection member of FIG. 6 in that the entire outer periphery is fastened. That is, the entire circumference of the collecting member is the fastening portion 54.

  As the sheets 52 and 53, any sheet can be used as long as it is air-permeable and can prevent the fibrous member of the inner highly charged electrostatic adsorption filter 51 from scattering. As a material for the materials 52 and 53, a mesh-like member having excellent air permeability is preferably used. In addition, an electrostatic adsorption filter can be selected as the sheets 52 and 53. In this case, a sheet having a lower charging performance than the inner highly charged electrostatic adsorption filter 51 is selected. Usually, an electrostatic adsorption filter with high charging performance often has short chains in the manufacturing process, and tends to drop off, drop, or scatter due to external force. On the other hand, an electrostatic adsorption filter of a type with a small amount of charge has a sufficient function as an anti-scattering sheet because the fibers are not short-chained and are not easily scattered. Moreover, although it is inferior to the highly charged electrostatic adsorption filter 51, it also has a function of adsorbing and capturing fine particles in the air.

Next, the installation place in the optical housing 40 of the collection member 50 is demonstrated.
The electrostatic adsorption filter is usually used in combination with a fan, a duct, and the like, and further collects fine particles by dust and dirt contained in the gas passing through the filter and a charged charge. In this embodiment, no fan or duct is used, and the amount of air passing through the collecting member due to the air flow caused by the rotation of the polygon mirror 32 is not large. Since 51 is used, it is possible to collect the fine particles in the optical housing 40 without using a fan or a duct. Therefore, if the collection member 50 is in the optical housing 40, the particle capturing effect can be expected almost anywhere.

  In order to prevent the polygon mirror 32 from being contaminated more efficiently, the collecting member 50 is installed in the vicinity of the polygon mirror 32. In particular, as shown in FIG. 8, when the collecting member 50 is installed facing the mirror surface of the polygon mirror 32, the air flow generated by the rotation of the polygon mirror 32 directly hits the collecting member 50. Can be collected.

Further, as shown in FIG. 9, even when the collecting member 50 is disposed above the polygon mirror 32, a good collecting effect can be obtained, and the polygon mirror 32 can be prevented from becoming dirty.
Incidentally, the embodiment shown in FIG. 10 is an example in which a net-like member 55 for reinforcing itself is provided on the sheets 52 and 53 which are electrostatic adsorption filters and are scattering prevention sheets. The net-like member 55 is formed integrally with the sheets 52 and 53, and has a function of reinforcing the sheets and suppressing dropping, dropping, and scattering with respect to the external force of the members constituting the sheets. Therefore, the sheets 52 and 53 have a function of making it difficult for the fibrous member or the like constituting the sheet from the surface on which the net-like member 55 is provided to drop off, fall, or scatter. This improves the handleability of the filter and increases the choice of materials that can be used as the anti-scattering sheet, thereby improving the design margin.

  Furthermore, since the net-like member 55 of the sheets 52 and 53 shown in FIG. 10 is provided on one surface of the sheet, a member that forms a collecting member on the surface provided with the net-like member 55 by gravity, airflow, vibration, or the like. A great effect can be obtained by using the side that is easily scattered, that is, the lower surface of the sheet 53 in this example.

1 is a schematic view of an image forming apparatus to which the present invention is applied. It is an enlarged explanatory view showing an image reading device of the image forming apparatus. It is a perspective view which shows the laser beam scanning apparatus of an image forming apparatus. It is front explanatory drawing which shows the structure of the collection member of this invention. It is a plane explanatory view showing one embodiment of the collection member of the present invention. (A), (b) is sectional explanatory drawing and plane explanatory drawing which show other embodiment of the collection member of this invention. (A), (b) is sectional explanatory drawing and plane explanatory drawing which show other embodiment of the collection member of this invention. It is plane explanatory drawing which shows the example of arrangement | positioning of the collection member of this invention. It is sectional explanatory drawing which shows another example of arrangement | positioning of the collection member of this invention. It is plane explanatory drawing which shows other embodiment of the collection member of this invention. It is explanatory drawing explaining the problem of an optical scanning device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 Photoconductor 17 Laser beam scanning apparatus 32 Polygon mirror 40 Optical housing 50 Collection member 51 Highly charged electrostatic adsorption filters 52 and 53 Scatter prevention sheet 55 Net-like member

Claims (8)

In an optical scanning device that deflects a light beam from a light source by an optical deflector and focuses the photoconductive photoreceptor as a light spot by a scanning imaging optical system attached to an optical housing to scan the photoreceptor.
An electrostatic adsorption filter that collects fine particles and the like, a sheet having air permeability, and a frame are provided, and the electrostatic adsorption filter is sandwiched between the sheets to prevent scattering of members constituting the electrostatic adsorption filter In a state to provide a collecting member having a structure integrated with the frame,
The trapping member is at a position where the airflow generated by the rotation of the optical deflector directly hits, and the upper surface of the optical deflector and the wall surface of the optical housing are provided with a gap between the wall surface and a leg portion. An optical scanning device characterized by being arranged .   2. The optical scanning device according to claim 1, wherein the electrostatic adsorption filter is a highly charged electrostatic adsorption filter in which a fibrous member is formed in a short chain shape.   3. The optical scanning device according to claim 1, wherein the collecting member is locally fastened around the sheet covering the highly charged electrostatic adsorption filter.   4. The optical scanning device according to claim 1, wherein the collecting member is fastened all around the sheet covering the highly charged electrostatic adsorption filter. . In an optical scanning device that deflects a light beam from a light source by an optical deflector and focuses the photoconductive photoreceptor as a light spot by a scanning imaging optical system attached to an optical housing to scan the photoreceptor.
An electrostatic adsorption filter that collects fine particles and the like, a sheet having air permeability, and a frame are provided, and the electrostatic adsorption filter is sandwiched between the sheets to prevent scattering of members constituting the electrostatic adsorption filter In a state to provide a collecting member having a structure integrated with the frame,
The trapping member is at a position where the airflow generated by the rotation of the optical deflector directly hits, and the upper surface of the optical deflector and the wall surface of the optical housing are provided with a gap between the wall surface and a leg portion. As well as
The optical scanning device according to claim 1, wherein the sheet is an electrostatic adsorption filter having a charge amount smaller than that of the electrostatic adsorption filter .   6. The optical scanning device according to claim 1, wherein the sheet is a mesh member provided with a porous material.   7. The optical scanning device according to claim 1, wherein a reinforcing net is provided on one surface of the sheet.   An image forming apparatus comprising the optical scanning device according to claim 1.

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