JP2005081812A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having an optical housing with an attachment means which is hardly influenced by vibration or heat. <P>SOLUTION: Attachment means 30a, 30b, 30c, 30d for attaching the optical housing to a body frame are provided to a bottom face 13d at both sides of the roughly rectangular-shaped optical housing 15 in the longitudinal direction. The attachment means 30a, 30b at both sides in one end of the optical housing 15 in the longitudinal direction are to be fixed ends and the attachment means 30c, 30d at both ends of the other end in the longitudinal direction are to be free ends. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser beam printer having an optical housing provided with attachment means for attachment to a main body frame, and an image forming apparatus such as a digital copying machine and a laser FAX.

  Image forming apparatuses such as laser beam printers, digital copying machines, and laser fax machines have a polygon mirror formed into a regular polygon that deflects and scans a light beam from a light source, and the light beam scanned by the polygon mirror is exposed to a photoconductor surface. An optical element (scanning lens) for forming an image above is provided, and a light detector is provided on the scanning start side outside the effective exposure region in order to determine the writing start position.

  Such a laser beam writing optical element is installed in an optical housing fixed to the main body frame. This optical housing includes (1) twisting of the housing by a fixing means for fixing the housing, (2) thermal deformation due to heat generated by the polygon motor, (3) thermal deformation due to heat from another unit in the image forming apparatus, (4 ) Problems such as jitter due to vibration of the image forming apparatus main body occur.

In particular, when a resin optical housing is used, there are many problems such as the strength of the optical housing and the positional deviation of dots due to thermal deformation.
In addition, in a conventional image forming apparatus such as a copying machine, the scanner portion can be opened and the optical housing can be attached to the main body frame. Inserted more.

  Therefore, there is a problem that when the optical housing is fixed, the optical housing is likely to be twisted. Further, in the tandem color machine, the twist of the optical housing causes the color misregistration because the positional relationship between the photoconductors of the respective colors and the optical elements in the optical housing is broken.

In order to solve these problems, the optical housing is supported and fixed with respect to the stay of the main body frame so as to be rotatable with respect to the longitudinal direction of the photosensitive drum. A technique that can be adjusted is disclosed (Patent Document 1).
JP-A-11-227249

However, the above technique functions only when the optical housing is adjusted in the horizontal direction with respect to the photoconductor through the main body frame, and cannot be adjusted in the vertical direction with respect to the photoconductor through the main body frame. is there.
Further, since all the attachment means are fixed to the main body frame, when the optical housing is thermally deformed, twisting and distortion occur, and the position setting of each optical element in the optical housing and the photosensitive member changes. There is.
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus provided with an optical housing provided with a mounting means that is not easily affected by vibration or heat.

  According to the first aspect of the present invention, mounting means for mounting the optical housing to the main body frame is provided on the bottom surfaces of both sides in the long side direction of the substantially rectangular optical housing, and the both sides of one end in the long side direction of the optical housing are provided. The attachment means is a fixed end, and the attachment means on both sides of the other end in the long side direction of the optical housing are free ends.

  According to the first aspect of the present invention, the attachment means for attaching the optical housing to the main body frame is provided on the bottom surfaces of both sides in the long side direction of the substantially rectangular optical housing, and the both sides of one end in the long side direction of the optical housing are provided. The mounting means is a fixed end, and the mounting means on both sides of the other end in the long side direction of the optical housing are free ends. Is solved.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, an adjusting portion for adjusting the optical housing in a horizontal direction is formed on attachment means on both sides of one end in the long side direction of the optical housing. Features.

  According to the second aspect of the present invention, since the adjusting portion for adjusting the optical housing in the horizontal direction is formed on the attachment means on both sides of one end in the long side direction of the optical housing, the optical housing can be easily adjusted in the horizontal direction. Become.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, an adjusting portion that adjusts the optical housing in the vertical direction is formed on attachment means on both sides of one end in the long side direction of the optical housing. Features.

  According to the third aspect of the present invention, since the adjusting portion for adjusting the optical housing in the vertical direction is formed on the attachment means on both sides of one end in the long side direction of the optical housing, the optical housing can be easily adjusted in the vertical direction. Become.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the contact portion of the adjusting portion with the main body frame is hemispherical.

  According to the invention of claim 4, since the contact portion of the adjustment portion with the main body frame is hemispherical, fine adjustment in the vertical direction can be easily performed.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the optical housing is fixed to the main body frame by attachment means on both sides of one end in the long side direction of the optical housing. A member is provided.

  According to the fifth aspect of the present invention, the fixing means for fixing the optical housing to the main body frame is provided on the attachment means on both sides of one end in the long side direction of the optical housing, so that the optical housing is securely fixed to the main body frame.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the optical housing is made of resin.

  According to the invention of claim 6, since the optical housing is made of resin, it is possible to provide an image forming apparatus at low cost.

  According to the first aspect of the present invention, the attachment means on the both sides at one end in the long side direction of the optical housing are fixed ends, and the attachment means on the both sides at the other end in the long side direction of the optical housing are free ends. Therefore, when the optical housing is thermally expanded, the distortion can be eliminated at the free end. Also, when the optical housing is thermally expanded, the distortion can be eliminated at the free end, and the characteristic value deterioration (beam spot diameter, scanning line tilt, scanning line rolling) caused by twisting of the optical housing is caused. It is possible to provide an image forming apparatus including an optical housing provided with an attachment unit that can reduce the influence on a certain image and is hardly affected by heat. Also, since the means for attaching the optical housing to the main body frame are provided on both sides of the optical housing in the long side direction, the influence on the image caused by vibration propagating from the main body frame is minimized, and means for attaching to the vibration is provided. An image forming apparatus including the optical housing can be provided.

  According to the second aspect of the present invention, since the adjustment portion for adjusting the optical housing in the horizontal direction is formed on the attachment means on both sides of one end in the long side direction of the optical housing, the optical housing can be easily moved in the horizontal direction. Can be adjusted. In addition, an adjustment unit is provided in the vertical direction with respect to the scanning direction of the writing laser beam, so that fine adjustment is possible when the optical housing is mounted, the inclination of the writing laser beam can be adjusted, and multi-color image formation is possible. Color shift can be reduced.

  According to the third aspect of the present invention, since the adjusting portion for adjusting the optical housing in the vertical direction is formed on the attachment means on both sides of one end in the long side direction of the optical housing, the optical housing can be easily moved in the vertical direction. Can be adjusted. In addition, an adjustment unit is provided in the vertical direction with respect to the scanning direction of the writing laser beam, so that fine adjustment is possible when the optical housing is mounted, the inclination of the writing laser beam can be adjusted, and multi-color image formation is possible. Color shift can be reduced.

  According to the fourth aspect of the present invention, since the contact portion of the adjustment portion with the main body frame is hemispherical, fine adjustment in the vertical and horizontal directions can be facilitated at the same time. Further, it is possible to prevent the mounting surface from being twisted when the optical housing is finely adjusted.

  According to the fifth aspect of the present invention, since the fixing means for fixing the optical housing to the main body frame is provided on the attachment means on both sides of one end in the long side direction of the optical housing, the optical housing is securely fixed to the main body frame. can do.

  According to the sixth aspect of the invention, since the optical housing is made of resin, it is possible to provide an image forming apparatus including a cheaper optical housing.

  FIG. 1 is a schematic sectional view of a digital color copying machine 20 as an example of the image forming apparatus of the present invention. The digital color copying machine (image forming apparatus) 20 includes a paper feeding unit 19, a conveying unit 21, a substantially rectangular optical housing 15 as an image forming unit, writing laser beams 16a to 16d, photoconductors (image carriers) 17a to 17d, The image forming apparatus includes a transfer belt 18, a fixing device 22, a paper discharge roller 23, a paper discharge tray 24, and the like. An arrow A indicates the moving direction of the transfer belt 18.

  Then, the paper fed from the paper feeding unit 19 is conveyed to the image forming unit by the conveying unit 21, and the optical housing 15, writing laser beams 16 a to 16 d, photoconductors (image carriers) 17 a to 17 d, and the transfer belt 18. The image is transferred by, for example. Thereafter, the image is fixed by the fixing device 22 and is discharged from the paper discharge roller 23 to the paper discharge tray 24.

  FIG. 2 is an enlarged cross-sectional view of a main part of the image forming unit. Reference numeral 1 (1a, 1b) is a two-stage polygon mirror that has a reflecting mirror on the side of a regular polygon, deflects and scans laser light by high-speed rotation, and 2a, 2b is a soundproof glass with the soundproofing effect of a polygon motor. Reference numerals 3a and 3b denote fθ lenses that change the equiangular motion of the beam scanning into a uniform linear motion by the polygon mirrors 1a and 1b, and 4a to 4d, 6a to 6d, and 7a to 7d mirrors for guiding laser light to the photosensitive member ( 1st to 3rd), 5a to 5d are long lenses for correcting the surface tilt of the polygon mirror, 8a to 8d are dust-proof glasses for preventing dust and the like from falling into the optical housing, 17a to 17d are photoreceptors, and 13a. Is a wall surface on which the optical element is arranged, 13b is an optical element arrangement surface, 11 is an upper lid for sealing the optical housing, 12 is a lower lid, and 10 is a polygon mirror lid. Reference numerals 30a and 30b denote attachment means (fixed ends), and reference numerals 30c and 30d denote attachment means (free ends). Reference numeral B denotes a stable optical housing 15 by suppressing the vertical direction when the optical housing 15 is inserted into the digital color copying machine 20. A spring s for causing the optical housing 15 to be positioned is a fulcrum for positioning the optical housing 15. Since the optical housing 15 is made of resin, an inexpensive image forming apparatus can be obtained.

  Then, as shown in FIGS. 3A and 3B, mounting means 30, a, 30b, and 30c for mounting the optical housing 15 to the main body frame on the bottom surfaces 13d on both sides in the long side direction of the optical housing 15 are provided. , 30d, both sides of one end in the long side direction of the optical housing 15, that is, the left mounting means 30a, 30b in the figure are fixed ends, and both sides on the other end in the long side direction of the optical housing 15, In the figure, the right attachment means 30c and 30d are free ends.

  In this example, the optical housing 15 is provided so as to protrude from both sides in the direction of insertion into the digital color copying machine 20. As will be described later, the attachment means 30a and 30b on the front side of the optical housing 15 in the insertion direction are fixed ends, and the attachment means 30c and 30d on the back side in the insertion direction are free ends. Accordingly, the simulation results shown in Tables 1 and 2 below can strengthen the vibration from the main body side.

In Tables 1 and 2, the resonance frequency was compared using the shape of the optical housing 15 of this example as it is as the model 1 and using a rectangular box-shaped model as the model 2 as shown in FIG. In Table 1, the case where the attachment means (fixed ends) 30a and 30b are attached to the lower left side in FIG. 3B and the attachment means (free ends) 30c and 30d are located on the upper right side in case 1 Case 2 is a case where the attachment means (fixed ends) 30a, 30b and the attachment means (free ends) 30c, 30d are both attached downward in FIG. And when the thickness of the model 1 and the model 2 was changed to 2.5-3.5 mm, the resonant frequency and the resonant frequency below 1 kHz were simulated about the modes 1-15, respectively.
As a result, it was found that the mode 1 of case 2 having a large resonance frequency and a small number of resonance frequencies having a frequency of 1 kHz or less is least susceptible to vibration.

In Table 2, simulations were performed for Cases A to D using Model 1 and Model 2 similar to Table 1. In case A, attachment means (fixed ends) 30a and 30b and attachment means (free ends) 30c and 30d are both attached to the upper part in FIG. 4, case B is attached to the middle part, and case C is attached to the lower part. In the case D, the attaching means (fixed ends) 30a and 30b and the attaching means (free ends) 30c and 30d are the same as the case 1 in Table 1.
And about the models 1 and 2, the resonance frequency which an attachment means receives about the modes 1-15 was simulated, respectively. As a result, it was found that the mode 1 of case C having a large resonance frequency is most resistant to vibration and is optimal.

  From these simulation results, the optimum mounting positions of the mounting means (fixed ends) 30a and 30b and the mounting means (free ends) 30c and 30d of the optical housing 15 are set to the bottom surfaces 13d on both sides in the long side direction.

  Incidentally, the optical housing 15 may be deformed due to the heat generated by a polygon motor (not shown) or the heat of another unit such as a fixing unit in the image forming apparatus. For this reason, if the optical housing 15 is completely fixed to the main body frame 31 of the image forming apparatus by the attaching means 30a to 30d, when the optical housing 15 is thermally deformed, the optical housing 15 is deformed in the direction of the arrow in FIG. End up.

  As a result, the set positions of the optical elements in the optical housing 15 and the photoconductors 17a to 17d may be shifted. As a result, color misregistration occurs. Therefore, as shown in FIG. 5B, by making the attachment means 30c, 30d free ends, the thermally expanded optical housing 15 is deformed so as to be expandable / shrinkable in the direction of arrows AB.

  At this time, the setting positions of the optical elements in the optical housing 15 and the photoconductors 17a to 17d are deviated. However, as shown in FIG. 5A, all the attaching means 30a to 30d of the optical housing 15 are fixed to the main body frame. Therefore, color shift can be reduced. Further, the attachment means 30c and 30d which are free ends at this time are not completely fixed to the main body frame 31 with screws or the like, but a pin is inserted into the fulcrum s and the spring B is used to move the upper and lower parts in FIG. It is regulated so that it is difficult to shift in the direction.

  By the way, as shown in FIG. 6A, for example, even if the optical housing 15 is positioned as designed with respect to the photoreceptor 17a, there is an error in the mounting position of the components of each optical element in the optical housing 15. In such a case, the writing laser beam 16a irradiated on the photoconductor 17a may deviate from the design value. At this time, by attaching the mounting means 30c and 30d of the optical housing 15 to the free ends, the optical housing 15 can be tilted to adjust the scanning line irradiation position on the photosensitive member 17a as shown in FIG. 6B. it can.

  Note that the right side surface 13a of the optical housing 15 may be provided with a protrusion, and a fulcrum s may be formed by forming a hole that fits into the protrusion in the body frame 31 (not shown) and fitting them together. Then, with the fulcrum s as the center, the optical housing 15 is tilted as shown in FIG. 6B or tilted in the opposite direction, and the position of the writing laser beam 16a irradiated on the photoconductor 17a is slightly reduced in the horizontal direction. Make adjustments.

  If the mounting surface of the fixed attachment means 30a, 30b on the main body frame 31 is flat, the optical housing is adjusted when the irradiation position of the writing laser beam 16a is adjusted as shown in FIG. 6B. 15 is distorted and attached to the main body frame. Even if the inclination of the scanning line can be adjusted by this adjustment, each optical element in the optical housing 15 deviates from the design value with respect to each of the photoconductors 17a to 17d. There is a risk of adversely affecting the optical characteristic value, for example, the diameter of the beam spot irradiated on the lens may deviate from the design value.

  Therefore, as shown in FIG. 7A, a hemispherical adjustment portion 32 that adjusts the optical housing 15 in the vertical direction at the contact portion of the mounting means 30a, 30b on the front side in the insertion direction of the optical housing 15 with the main body frame 31. Form. Thereby, when adjusting the vertical / horizontal tilt of the optical housing 15, the mounting distortion of the optical housing 15 can be reduced. For example, as shown in FIG. 7B, two screws (fixing members) 33a and 33b are attached to the optical housing 15 side, and the screw 32a, It fixes to the main body frame 31 by 32b. The adjustment amount of the adjustment unit 32 is adjusted by the feed amount of each screw 33a, 33b. These screws 33a and 33b are not limited to this, and pins or the like may be used.

  Then, by adjusting the feed amount of the screws 33a and 33b of the attaching means 30a and 30b, the optical housing 15 can be installed in an inclined state as shown in FIG. At the same time, since the adjusting portion 32 is hemispherical, the optical housing 15 can be attached to the main body frame 31 without being distorted.

  The tandem type color image forming apparatus provided with the optical systems of Bk, Y, M, and C in the optical housing 15 has been described. However, the present invention is not limited to this, and any form is possible. It can be applied to the image forming apparatus. If it is not a color image forming apparatus, there is no effect of reducing color misregistration, but the influence on the optical characteristics due to thermal deformation of the optical housing, distortion at the time of mounting, etc. can be reduced.

In this example, the optical housing 15 can be adjusted in both the vertical and horizontal directions using the hemispherical adjustment portion 32. However, the present invention is not limited to this, and the shape of the adjustment portion 32 is semi-spherical. On the cylinder, only the horizontal direction or only the vertical direction may be adjusted.
In this example, the insertion direction of the optical housing 15 is the long side direction of the rectangle. However, the present invention is not limited to this, and the optical housing 15 may be attached to the main body in any manner.

1 is a schematic cross-sectional view of an image forming apparatus of the present invention. FIG. 2 is a detailed sectional view of the optical housing of the present invention provided in FIG. 1. 2A is a schematic view as viewed from above, and FIG. 2B is a schematic view as viewed from the side. It is a schematic perspective view of the model 2 used for the simulation of Table 1,2. (A) is a schematic diagram illustrating a case where the optical housing is thermally expanded when the four corners of the optical housing are fixed to the main body frame, and (b) is a case where the two corners of the optical housing are free ends. It is the schematic explaining the case where an optical housing expands thermally. (A), (b) is a figure explaining a mode that the optical housing of FIG.5 (b) is attached to a main body frame, and is finely adjusted. 5A is a schematic cross-sectional view of a main part in which an adjustment portion is formed at two fixed ends of the optical housing of FIG. 5B, and FIGS. 5B and 5C are optical housings using the adjustment portion of FIG. It is a figure for demonstrating a mode that is attached to a main body frame.

Explanation of symbols

1, 1a, 1b Polygon mirror 2a, 2b Soundproof glass 3a, 3b fθ lens 4a, 4b, 4c, 4d, 6a, 6b, 6c, 6d, 7a, 7b, 7c, 7d Mirror 5a, 5b, 5c, 5d Long Lens 8a, 8b, 8c, 8d Dust-proof glass 10 Polygon mirror lid 11 Upper lid 12 Lower lid 13a Wall surface 13b Optical element placement surface 13d Bottom surface 15 Optical housing 16a, 16b, 16c, 16d Write laser beam 17a, 17b, 17c, 17d Photoconductor (image carrier)
18 Transfer belt 19 Paper feed unit 20 Digital color copier (image forming device)
DESCRIPTION OF SYMBOLS 21 Conveyance part 22 Fixing device 23 Paper discharge roller 24 Paper discharge tray 30a, 30b Attaching means (fixed end)
30c, 30d Mounting means (free end)
31 Body frame 32 Adjustment part 33a, 33b Screw (fixing member)
s fulcrum

Claims (6)

  Attachment means for attaching the optical housing to the main body frame is provided on the bottom surfaces of both sides in the long side direction of the substantially rectangular optical housing, and the attachment means on both sides at one end in the long side direction of the optical housing are fixed ends. In addition, the image forming apparatus is characterized in that the mounting means on both sides of the other end in the long side direction of the optical housing is a free end.   The image forming apparatus according to claim 1, wherein an adjustment unit that adjusts the optical housing in a horizontal direction is formed in attachment means on both sides of one end in the long side direction of the optical housing.   The image forming apparatus according to claim 1, wherein an adjustment portion that adjusts the optical housing in a vertical direction is formed in attachment means on both side portions at one end in the long side direction of the optical housing.   The image forming apparatus according to claim 2, wherein a contact portion of the adjustment unit with the main body frame is hemispherical.   5. The image forming apparatus according to claim 1, further comprising a fixing member for fixing the optical housing to the main body frame on attachment means on both sides of one end in the long side direction of the optical housing. The image forming apparatus according to claim 1, wherein the optical housing is made of resin.

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