JP4965895B2 - Optical scanning device - Google Patents

Description

  The present invention relates to an optical scanning device used for a laser beam printer, a digital copying machine, or the like.

  2. Description of the Related Art Conventionally, in an optical scanning device used in a laser beam printer, a digital copying machine, and the like, a light beam that has been optically modulated in accordance with an image signal and emitted from a light source is periodically deflected and scanned by an optical deflector to form an imaging optical system. The beam is focused on the image forming surface on the photosensitive drum by the system. Here, examples of the optical deflector include a rotating polygon mirror. The imaging optical system has fθ characteristics.

  The spot on the imaging surface forms an electrostatic latent image in accordance with main scanning by the deflector and sub-scanning by the rotation of the photosensitive drum, and image recording is performed.

  FIG. 14 shows an optical scanning apparatus 100 according to a conventional example. A divergent light beam emitted from a light source 101 is made into a substantially parallel light beam by a collimator lens 102, the light amount of the light beam is adjusted by a diaphragm 103, and a refractive power only in the sub-scanning direction. Is incident on a cylindrical lens 104 having

  The parallel light beam incident on the cylindrical lens 104 is emitted in the state of a substantially parallel light beam as it is in the main scanning section, and converges only in the sub-scanning section, and is formed as a line image on the reflecting surface 105a of the rotary polygon mirror 105. Image.

  The light beam deflected and scanned by the rotation of the rotary polygon mirror 105 forms an image on the imaging surface of the photosensitive drum 120 through the fθ lens 106 which is an imaging optical element having fθ characteristics. The point image (spot) imaged on the imaging surface is scanned on the photosensitive drum 120 in the direction of arrow B shown in FIG. 14 by rotating the rotary polygon mirror 105 in the direction of arrow A shown in FIG. Image recording is performed on the photosensitive drum 120, which is a recording medium, with such main scanning and sub-scanning due to the photosensitive drum 120 rotating around its rotation axis.

  Also, if the optical components such as the fθ lens 106 (106a, 106b) and the reflecting surface 105a of the rotary polygon mirror 105 are contaminated, the image is affected by a decrease in the amount of light, etc. 15 is sealed by a lid 150 and a sealing member 151 shown in FIG.

  FIG. 15A is a top view of the optical scanning device shown in FIG. 14, and FIG. 15B is a cross-sectional view.

  In particular, the higher the outer peripheral speed of the rotary polygon mirror 105, the more conspicuous the dirt on the reflecting surface 105a of the rotary polygon mirror 105 appears. Therefore, the degree of sealing needs to be increased. In order to increase the sealing degree, for example, as shown in Patent Document 1, a dustproof glass (not shown) may be provided on the housing 152 between the fθ lens 106 and the photosensitive drum 120.

Further, since the cost of the dustproof glass is high, there is a sealing means that can be performed at a low cost as shown in Patent Document 2. In FIG. 14, the collimator lens 102, the cylindrical lens 104, the rotary polygon mirror 105, and the fθ lens 106 are disposed in a housing 152 and cover the housing 152 with a lid 150. The gap between the upper portion of the fθ lens 106b and the lid is appropriately compressed between the fθ lens 106b and the lid 150 by using an elastic member such as an elastic flexible urethane foam (density 20 kg / m ^{3 to} 60 kg / m ³ ) as a sealing member 151. Then closed. When further sealing is required, as shown in Patent Document 3, not only the upper part of the fθ lens 106 but also the lower part and the side part of the fθ lens 106 are closed with, for example, elastic flexible urethane foam.

  FIG. 16 illustrates a color image forming apparatus that uses a plurality of optical scanning devices similar to the above to record image information for each color on a plurality of photosensitive drums to form a color image.

  This apparatus includes four optical scanning devices 100, four photosensitive drums 121, 122, 123, and 124, developing devices 131, 132, 133, and 134, and a conveyor belt 141, respectively.

  The four optical scanning devices 100 correspond to C (cyan), M (magenta), Y (yellow), and Bk (black) colors. Each optical scanning device 100 records image signals on the photosensitive drums 121, 122, 123, and 124, develops them by the developing devices 131, 132, 133, and 134, and transfers them to a sheet material on the conveyance belt 141. Thus, a color image is printed at high speed.

  In such a color image forming apparatus, since a plurality of scanning lines are superimposed to form an image, it is particularly important to reduce scanning line deviation (registration deviation) between colors.

  As a method of reducing the scanning line deviation, for example, there is a method of moving the fθ lens and adjusting the scanning line to a constant value as disclosed in Patent Document 4. As an example of adjusting the fθ lens, FIG. 17A shows a top view of the optical scanning device, and FIG. 17B shows a front view of the optical scanning device.

As the adjustment of the scanning line, for example, the inclination in the sub-scanning direction is adjusted in the urging directions A and B for the fθ lens 106b, and the half magnification in the main scanning direction is adjusted in the urging direction C for the fθ lens 106b. After the adjustment, the fθ lens 106b is fixed to the housing 152 with, for example, an ultraviolet curable adhesive. By adjusting the scanning line to a constant value by energizing the fθ lens 106b, the scanning line deviation between the respective colors after the scanning lines are superimposed is reduced.
JP-A-5-60992 JP 2003-177344 A Japanese Patent Laid-Open No. 10-232360 JP 2003-255245 A JP 2000-193902 A

  However, in the case of the prior art as described above, the following problems have occurred.

  The optical scanning device for adjusting the fθ lens 106b described with reference to FIG. 17 as shown in Patent Document 4 is an optical scanning device that closes the opening of the housing 152 with the fθ lens 106b as in Patent Document 5. The degree of sealing inside is raised. However, in an optical scanning device that has a gap of 0.3 to 0.5 mm between the fθ lens 106b and a housing 152 that is, for example, a resin molded product, the rotary polygon mirror 105 is provided in an optical scanning device that requires a high degree of sealing. It becomes dirty and causes image deterioration.

Further, when the optical scanning device is hermetically sealed using a flexible urethane foam as shown in Patent Documents 2 and 3, there are the following problems. That is, there are a plurality of soft urethane foams, the assemblability is not good, and a reaction force of the soft urethane foam is generated when the lid 150 is assembled, and the scanning line is changed by moving the fθ lens. The fluctuation of the scanning line due to the movement of the fθ lens causes a scanning line shift between the colors after the scanning lines are overlaid in the color image forming apparatus, resulting in image degradation.

An object of the present invention is to provide an optical scanning device having good dustproof performance without using dustproof glass.

In order to achieve the above object, the present invention provides:
Deflection scanning means for deflecting and scanning the light beam emitted from the light source, the light beam scanningly deflected by the deflection scanning means is transmitted, an imaging means for focusing the light beam on the surface of the image bearing member, before Symbol deflection scanning transmitting the optical box, and a lid member mounted on the optical box, the imaging means is in a position facing the imaging means of said lid member for accommodating the hand Dan及 beauty said imaging means In the optical scanning device in which the opening through which the luminous flux passes is formed ,
The elastic member has a shape along the entire circumference of the opening of the lid member, and has a sheet-like elastic member fixed to one of the imaging means and the lid member and in contact with the other. In the state where the lid member is mounted on the optical box, the portion fixed to the one of the elastic members and the portion contacting the other are separated with respect to the direction perpendicular to the optical axis direction of the imaging means. and it has the deflection elastic member, and wherein the busy Guko the gap between the lid member and the imaging means in the entire circumference of the imaging means.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the optical scanning device which has favorable dustproof performance , without using dustproof glass.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  A first embodiment to which the present invention can be applied will be described in detail with reference to FIGS.

  FIG. 2 is a schematic sectional view of an image forming apparatus provided with an optical scanning device to which the present invention can be applied. In the figure, reference numerals 1Y, 1M, 1C, and 1Bk denote image carriers arranged at equal pitches, and in this embodiment, are constituted by photosensitive drums. The image forming operation by the image forming apparatus will be described below with reference to FIG.

  In this embodiment, light beams (laser beams) LY, LM, LC, and LBk that are respectively light-modulated based on image information are emitted from the light source, and are respectively on the corresponding photosensitive drums 1Y, 1M, 1C, and 1Bk. Irradiation forms an electrostatic latent image.

  The latent images are formed on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1Bk that are uniformly charged by the primary chargers 2Y, 2M, 2C, and 2Bk, respectively. The toner images of yellow, magenta, cyan, and black are visualized by the developing devices 4Y, 4M, 4C, and 4Bk, respectively, and superimposed on the transfer belt 8 by the transfer rollers 5Y, 5M, 5C, and 5Bk, and electrostatically formed. Transcribed.

  Thereafter, residual toner remaining on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1Bk is removed by the cleaners 6Y, 6M, 6C, and 6Bk, and the primary chargers 2Y, 2Y, 2Y, and 2B are formed again to form the next color image. It is uniformly charged by 2M, 2C, 2Bk.

  The transfer material P is stacked on a feeding tray 41, and is fed one by one by a feeding roller 42 in order, and is sent out onto a conveying belt 7.

  While being transported on the transport belt 7, the color toner image formed on the surface of the transfer belt 8 is transferred onto the transfer material P to form a color image.

  The color image formed on the transfer material P is heat-fixed by the fixing device 45, and is then conveyed by the discharge roller 46 and outputted outside the apparatus.

  FIG. 3 is a perspective view for explaining the configuration of an optical scanning apparatus to which the present invention can be applied.

  Beams (light beams) emitted from the light source devices 50a, 50b, 50c, and 50d as light sources are incident on different surfaces of the rotary polygon mirrors 12 and 18 constituting the deflection scanning means, and are scanned in different directions.

  The beams scanned by the rotary polygon mirrors 12 and 18 form scanning light on four photosensitive drums as shown below. That is, the beams scanned by the rotary polygon mirrors 12 and 18 first pass through the first scanning lenses 13a, 13b, 13c, and 13d. The direction can be changed by folding mirrors 14a, 14b, 14c, and 14d arranged at the same pitch as the photosensitive drum pitch and at an angle of about 45 ° with respect to the incident light beam. Thereafter, the light passes through the second scanning lenses 15a, 15b, 15c and 15d as image forming means, and forms an image of the scanning light on the four photosensitive drums. Here, the first scanning lenses 13a, 13b, 13c, and 13d, the folding mirrors 14a, 14b, 14c, and 14d, and the second scanning lenses 15a, 15b, 15c, and 15d constitute an optical member group.

  The second scanning lenses 15a, 15b, 15c, and 15d are moved in, for example, the sub-scanning directions A and B shown in FIG. 3 in order to reduce the scanning line shift (registration shift) between the colors. The scanning line in the scanning direction is adjusted. Further, the scanning line in the main scanning direction is adjusted by moving in the main scanning direction C.

  The second scanning lenses 15a, 15b, 15c, and 15d are fixed to the optical box 21 with an adhesive or the like after adjustment. In this embodiment, the second scanning lenses 15a, 15b, 15c, and 15d are fixed at two locations of the fixing portions 27 provided at both ends. Here, the fixing part 27 fulfills the following functions during lens adjustment. That is, the second scanning lens 15a, 15b, 15c, 15d functions as a holding portion (adjustment auxiliary portion) that holds the second scanning lenses 15a, 15b, 15c, and 15d so as to be swingable in the sub-scanning directions A and B and the main scanning direction C. In addition, it functions as a positioning portion in the direction substantially perpendicular to the sub-scanning directions A and B and the main scanning direction C.

  The optical scanning device includes deflectors 19 and 20 as deflection scanning means each having polygon mirrors 12 and 18 on the same plane of one optical box 21. Further, the optical scanning device uses all of the optical scanning systems (optical scanning means) such as the other folding mirrors 14a, 14b, 14c, 14d and the scanning lenses 13a, 13b, 13c, 13d, 15a, 15b, 15c, 15d as resin. It is provided in the optical box 21 molded by the above method.

Then, the lid 22 as a lid member is attached to the second scanning lenses 15a, 15b, 15c, 15
The optical scanning device is hermetically sealed by being attached to the optical box 21 from a direction substantially parallel to the direction of emission of the light that has passed through d, and fixed by a fixing means such as a screw or snap fit (not shown). In this embodiment, the lid 22 is formed of resin.

  FIG. 4 is a diagram showing the lid 22 and the elastic member 24, and FIG. 5 is a diagram showing the lid 22 to which the elastic member 24 is attached and the second scanning lens 15.

  As shown in FIG. 4, the elastic member 24 such as urethane foam is an integral (integrated) member provided with an opening 25 through which a light beam passes.

  As shown in FIG. 5, the lid 22 is provided with an opening 29 and a guide 23. The opening 29 is for the light beam that has passed through the second scanning lens 15 to pass therethrough. The guide 23 is provided around the opening 29 so as to protrude in the direction facing the second scanning lens 15, and the shape of the portion facing the second scanning lens 15 is the second scanning lens. Similar to the outer shape of the lens 15. The elastic member 24 is attached along the guide 23 by a supporting means such as a double-sided tape.

  FIG. 1 is a diagram illustrating a state in which the lid 22 is attached to the optical box 21.

  As shown in FIG. 1, the elastic member 24 is interposed between the optical box 21 and the lid 22 with the lid 22 attached to the optical box 21. Between the scanning lens 15 and the guide 23 provided in the direction facing the second scanning lens 15.

  The elastic member 24 is in contact with the entire circumference of the second scanning lens 15a, 15b, 15c, 15d in the optical axis direction La. Here, the fact that the elastic member 24 is in contact with the entire circumference of the second scanning lens 15 in the optical axis direction La means that the elastic member 24 is elastically deformed in the second scanning lens 15 with which the elastic member 24 is in contact. That is, the direction of the reaction force F generated by the above coincides with the optical axis. Therefore, the direction of the reaction force F generated in the second scanning lens 15 by the contact of the elastic member 24 is a direction substantially orthogonal to the sub-scanning directions A and B and the main scanning direction C shown in FIG. .

  Thereby, a high sealing degree can be realized by eliminating the gap between the second scanning lens 15 and the lid 22, and entry of dust and the like can be prevented. Further, the reaction force F generated by the contact of the elastic member 24 is generated in a direction substantially orthogonal to the direction in which the position of the second scanning lens 15 is adjusted, whereby the reaction force applied to the second scanning lens 15 is increased. The force can be reduced and deformation of the second scanning lens 15 can be suppressed. That is, fluctuations in the scanning line after adjustment due to reaction force can be suppressed.

  Therefore, it is possible to prevent image degradation. Furthermore, since the elastic member 24 is provided integrally, the assemblability, that is, the workability during assembly can be improved.

  In the present embodiment, the case where the elastic member 24 is in contact with the entire circumference of the second scanning lens 15 has been described, but the present invention is not limited to this. FIG. 13 is a diagram for explaining a modification of the elastic member 24. As shown in FIG. 13, the elastic member 24 provided integrally is only required to be in contact with the longitudinal direction (main scanning direction) of the second scanning lens 15. If the elastic member 24 is in contact with at least the longitudinal direction of the second scanning lens 15, the effect of sufficiently preventing the entry of dust or the like can be obtained.

In the present embodiment, the elastic member 24 is attached along the guide 23 provided on the lid 22, but is not limited thereto, and is attached to the optical box 21 or the second scanning lens 15. It may be a thing.

  Further, the guide 23 is provided so that the shape of the portion facing the second scanning lens 15 is similar to the outer shape of the second scanning lens 15. In this embodiment, as shown in the figure, the second scanning lens 15 is provided so as to cover the outer shape when viewed from the optical axis direction La. Here, the shape similar to the outer shape refers to a shape in which the elastic member 24 attached to the guide 23 comes into contact with the second scanning lens 15 in the optical axis direction to obtain the above-described effect. To do.

  In this embodiment, an example in which a plurality of photosensitive drums are irradiated with one optical scanning device is shown, but the present invention is not limited to this.

  6 and 7 show a second embodiment to which the present invention can be applied. In addition, the same code | symbol is attached | subjected about the component similar to Example 1, and the description is abbreviate | omitted.

  The lid 22 is provided with a guide 23 similar to the outer shape of the second scanning lens 15a, 15b, 15c, 15d, and a sheet member 28 such as PET is fixed with a double-sided tape or the like along the guide 23 as an elastic member. .

  FIG. 7 shows a state where the lid 22 is attached to the optical box 21.

  The sheet member 28 contacts the entire circumference of the second scanning lens 15a, 15b, 15c, 15d in the optical axis direction La.

  In this embodiment, since an inexpensive material can be used as the elastic member, it is possible to achieve a high degree of sealing while realizing a reduction in cost.

  FIG. 8 shows a third embodiment to which the present invention can be applied. FIG. 8 is a perspective view of the lid 22. In addition, the same code | symbol is attached | subjected about the component similar to Example 1, and the description is abbreviate | omitted.

  The lid 22 is provided with a guide 23 similar to the outer shape of the second scanning lens 15a, 15b, 15c, 15d, and a rib 26 for restricting the movement (movable range) of the elastic member 24 inside the guide 23. Yes. The rib 26 may be positioned in the direction orthogonal to the optical axis by being assembled with the opening 25 provided in the elastic member 24.

  FIG. 9 shows a state where the lid 22 is assembled.

  The rib 26 is disposed close to the outer shape of the scanning lenses 15a, 15b, 15c, and 15d with the optical axis La interposed therebetween.

  Thereby, in addition to the effects described in the first embodiment, the following effects can be obtained. That is, by providing the ribs 26, the elastic member 24 may be blocked by mistake when the elastic member 24 is attached to the lid 22, or when the elastic member 24 is twisted when the lid 22 is assembled to the optical box 21. It is possible to prevent problems that occur during work.

FIG. 10 shows a fourth embodiment to which the present invention can be applied. FIG. 10 shows the guide 2 provided on the lid 22.
FIG. In addition, the same code | symbol is attached | subjected about the component similar to Example 1, and the description is abbreviate | omitted.

  The lid 22 has a guide 23 similar to the outer shape of the second scanning lens 15a, 15b, 15c, 15d, but in the main scanning direction from the guide width 32 of the H portion (lens end) to the G portion (approximately the center of the lens). Part) is provided such that the guide width 31 thereof becomes longer. For example, when the scanning lenses 15a, 15b, 15c, and 15d are fixed to the optical box 21 at both ends, the vicinity of the G portion, which is a substantially central portion of the scanning lenses 15a, 15b, 15c, and 15d, is easily distorted by an external force. Here, the guide widths 31 and 32 are intervals between two guides 23 provided on both sides of the opening 29 in the sub-scanning direction.

  FIG. 11 shows a cross section of the G portion and FIG. 12 shows a cross section of the H portion when the lid 22 is assembled to the optical box 21.

  The distance between the second scanning lens 15a, 15b, 15c, 15d and the guide 23 is a distance 35 in the G portion, a distance 36 in the H portion, and an elastic member in the G portion where the distance is longer than in the H portion. 24 reaction force can be reduced.

  Thereby, in addition to the effects described in the first embodiment, the following effects can be obtained. That is, the reaction force generated from the elastic member 24 is locally reduced in the scanning lenses 15a, 15b, 15c, and 15d, so that deformation of the scanning lenses 15a, 15b, 15c, and 15d can be reduced. It is possible to reduce the scanning line deviation between the respective colors in the scanning direction.

  In the present embodiment, the case where the rib 26 described in the third embodiment is provided has been described. However, the present invention can be suitably applied to the case where the rib 26 is not provided as in the first embodiment. .

1 is a diagram illustrating an optical scanning device according to Embodiment 1. FIG. 1 is a diagram illustrating an optical scanning device according to Embodiment 1. FIG. 1 is a diagram illustrating an optical scanning device according to Embodiment 1. FIG. 1 is a diagram illustrating an optical scanning device according to Embodiment 1. FIG. 1 is a diagram illustrating an optical scanning device according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating an optical scanning device according to a second embodiment. FIG. 6 is a diagram illustrating an optical scanning device according to a second embodiment. FIG. 9 is a diagram illustrating an optical scanning device according to a third embodiment. FIG. 9 is a diagram illustrating an optical scanning device according to a third embodiment. FIG. 10 is a diagram illustrating an optical scanning device according to a fourth embodiment. FIG. 10 is a diagram illustrating an optical scanning device according to a fourth embodiment. FIG. 10 is a diagram illustrating an optical scanning device according to a fourth embodiment. FIG. 10 is a diagram illustrating a modification of the elastic member in the optical scanning device according to the first embodiment. It is a figure explaining the optical scanning device of a prior art example. It is a figure explaining the optical scanning device of a prior art example. It is a figure explaining the subject of the optical scanning apparatus of a prior art example. It is a figure explaining the subject of the optical scanning apparatus of a prior art example.

Explanation of symbols

1Y, 1M, 1C, 1Bk Photosensitive drums 15a, 15b, 15c, 15d Second scanning lens 19, 20 Deflector 21 Optical box 22 Lid 23 Guide 24 Elastic member 29 Opening 50a, 50b, 50c, 50d Light source device

Claims (6)

Deflection scanning means for deflecting and scanning the light beam emitted from the light source, the light beam scanningly deflected by the deflection scanning means is transmitted, an imaging means for focusing the light beam on the surface of the image bearing member, before Symbol deflection scanning transmitting the optical box, and a lid member mounted on the optical box, the imaging means is in a position facing the imaging means of said lid member for accommodating the hand Dan及 beauty said imaging means In the optical scanning device in which the opening through which the luminous flux passes is formed ,
The elastic member has a shape along the entire circumference of the opening of the lid member, and has a sheet-like elastic member fixed to one of the imaging means and the lid member and in contact with the other. In the state where the lid member is mounted on the optical box, the portion fixed to the one of the elastic members and the portion contacting the other are separated with respect to the direction perpendicular to the optical axis direction of the imaging means. and has the elastic member bends, the optical scanning device comprising a busy Guko the gap between the lid member and the imaging means in the entire circumference of the imaging means. Wherein the lid member, the guide portion which is disposed around the imaging means in a mounted state to the optical box is formed along the periphery the opening,
The elastic member is in contact or fixed to the guide portion, the optical scanning apparatus according to claim 1, characterized in that close the gap between the imaging means and the guide portion. The guide portion in a state where the lid member to the optical box is attached, the optical scanning apparatus according to claim 2, characterized in that is provided to protrude I suited in the optical box. The guide portion in a state where the lid member is attached to the optical box, an optical scanning apparatus according to claim 2, characterized in that is provided to protrude I suited outside the optical box. In a state where the lid member is mounted on the optical box, the guide portions are opposed to each other with the image forming means in the short direction of the image forming means, and the interval between the guide portions in the short direction is the optical scanning apparatus according to claim 2 or 3, characterized in and go is wide toward the longitudinal center than the longitudinal end portion of the imaging means. 6. The elastic member according to claim 1, wherein the elastic member is fixed to the lid member.
The optical scanning device according to any one of the preceding claims.

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