JP2008070722A - Mirror reinforcement structure, optical scanner, image read-out device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively and firmly perform a necessary reinforcement of a mirror by using a smaller amount of materials at low cost. <P>SOLUTION: A rectangular reinforcement member 2 is used by projecting the reflection face side projected part 2a at the reflection face 1a side of the mirror 1 and a back face side projected part 2b at the back face side 1b by an equal amount, and the middle part 2c of the reinforcement member 2 is bonded to the side face 1c of the mirror 1. In this way, the generation of vibration of a low frequency mode to twist the reflection face of the mirror 1 is prevented by arranging the reinforcement member 2 with a mass balance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mirror reinforcing structure that reinforces an elongated mirror, and an optical scanning device, an image reading apparatus, and an image forming apparatus that use a mirror reinforced by the mirror reinforcing structure as a part of an optical component.

  In an image forming apparatus such as a copying machine using electrophotographic technology, a latent image is formed on an image carrier based on image information output from an optical system of an image reading apparatus that reads an original image or the image reading apparatus or a personal computer. A mirror in the optical system of the optical scanning device for writing is used.

  A mirror used in the image forming apparatus is used to reflect a linear light beam or a linearly scanned light beam and change the direction of the light beam. For this reason, in general, the mirror has a very long and thin shape, and in many cases, the mirror can be held only in the vicinity of both ends of the mirror so as not to block light. Due to the shape and holding structure of the mirror, the mirror used in the image forming apparatus is very likely to vibrate.

  When the mirror of the image reading device or the optical scanning device vibrates, the mirror generates a vibration that deforms into an arcuate shape with the holding parts at both ends as fulcrums. Are periodically deformed, and a periodic shift occurs in the magnification of the mirror in the longitudinal direction of the image information read in accordance with this or the image information written on the image plane, or the bending of the light line in the short direction. . A periodic shift in magnification in the longitudinal direction results in periodic fluctuations in the vertical lines of the output image, and a periodic shift in bending in the short direction causes a periodic image density called banding. Any of these causes degradation of image quality.

  As one means for reducing the vibration of the mirror as described above, it has been well known that the thickness of the mirror should be increased. Float glass is generally used as the mirror material. This is because the float glass can obtain high flatness cheaply from the construction method.

  The thickness in the direction perpendicular to the mirror reflecting surface is used as the thickness of the float glass plate, but the width and length in the parallel direction on the reflecting surface must be appropriately cut and cut out. Here, in the case of a mirror size generally used in an image forming apparatus, if the plate thickness is 6 mm or less, the glass surface is scratched along the line to be cut with a diamond cutter or the like, By lightly giving an impact, it can be cut out by folding along the wound.

  However, when the plate thickness exceeds 6 mm, it is difficult to fold along the flaw, so this method cannot be used, and it is necessary to cut by a method such as grinding. Since glass is a material with low toughness, the cutting speed is very slow in order to prevent cracking and chipping. As a result, if this method is used, the processing cost becomes considerably high. Therefore, when the mirror is thickened, not only the material cost for the thicker part but also the processing cost is considerably increased. Therefore, there is a circumstance that the thickness of the mirror should be kept to 6 mm or less as much as possible.

  In order to improve the vibration resistance of the mirror, various techniques have been proposed in the past. For example, Patent Document 1 describes a configuration in which a reinforcing member is attached to the back surface of the reflecting surface of the mirror to reinforce the mirror. However, in this method, since the mirror follows the flatness of the reinforcing member, the flatness of the reinforcing member is also required to keep the flatness of the mirror reflecting surface with high accuracy. Therefore, inexpensive reinforcement is difficult.

  As a technique for solving the above-described problems and vibration problems together, for example, a technique described in Patent Document 2 has been proposed. The structure described in Patent Document 2 is such that a reinforcing member is attached to the side surface adjacent to the reflecting surface of the mirror. In Patent Document 2, the mirror is reinforced even if the flatness of the reinforcing member is not so high. Since it deforms in a direction parallel to the reflecting surface following the member, the mirror can be reinforced with little effect on the flatness of the reflecting surface, which can increase the vibration resistance of the mirror at a very low cost. There is a description that there is a merit that it can be done.

However, when the inventors applied the technique described in Patent Document 2 to the optical scanning device of the image forming apparatus, a banding image was generated in the output image even though the reinforcing member was attached to the mirror. .
Japanese Utility Model Publication No. 1-142913 JP-A-10-282399 JP 2006-154116 A

  Therefore, the inventors tried vibration simulation by the finite element method for the mirror reinforcing structure of the form described in Patent Document 2. The results are shown in (Table 1) and FIG. From this result, it was newly found that this technique has the following problems (1) and (2).

  (1) If something hard member is stuck on the mirror, it is not always reinforced. For example, the resonance frequency may be lowered by attaching an iron plate.

  Primary resonance of a mirror when a 254 mm long × 1 mm thick reinforcing member (iron plate) is attached to a mirror of length 254 mm × width 10 mm × thickness 5 mm and the width of the reinforcing member (reinforcing plate width) is changed The results of measuring the frequency are shown in (Table 1) and FIG. Here, for the sake of convenience, the primary resonance frequency in the case of no reinforcing member is shown as a reinforcing plate width of 0 mm. As shown in (Table 1), when an iron plate having a width of 5 mm is attached to the mirror, the primary resonance frequency is reduced by about 3 Hz as compared to the case where nothing is attached.

（２）従来では、補強部材の幅を大きくするほど共振周波数が高くなると考えられていたが、実際には（表１）に示したように、補強部材の幅を大きくすればするほど共振周波数が高くなるというわけではない。

(2) Conventionally, it has been considered that the resonance frequency becomes higher as the width of the reinforcing member is increased. However, as shown in (Table 1), the resonance frequency is actually increased as the width of the reinforcing member is increased. Is not high.

  As shown in (Table 1) and FIG. 11, when the plate width of the reinforcing member is 45 mm, the primary resonance frequency is as low as 74 Hz, even though the width of the reinforcing member is increased. The primary resonance frequency has decreased.

  Thus, in the past, it was vaguely considered that the mirror was reinforced if the reinforcing member was attached, and the reinforcing effect was greater as the width of the reinforcing member was larger. However, the shape and size of the reinforcing member that can be used in practice From the results of the examinations (1) and (2) above, it is recognized that these recognitions are wrong, and the required effect is not obtained, or in some cases, the effect is not obtained at all. I understand.

  Patent Document 3 describes a technique in which an L-shaped member is attached to a mirror as a reinforcing member. However, in Patent Document 3, as shown in FIG. 12, one of the two L-shaped surfaces of the reinforcing member 100 is bonded to the back surface 101b of the mirror 101 on the side opposite to the reflecting surface 101a. In addition, the other L-shaped surface 100b is disposed so as to protrude toward the reflecting surface 101a of the mirror 101.

  Here, Patent Document 3 describes that the natural frequency increases as the amount of protrusion of the L-shaped reinforcing member 100 toward the reflecting surface 101a of the mirror 101 increases. When the inventors performed a vibration simulation for the above, when the protrusion amount is increased, a vibration mode in the rotation direction with the mirror longitudinal direction as an axis appears in the primary mode (in the direction of arrow A in FIG. 12). On the other hand, it became clear that it became weak and resonated at a low frequency.

  The present invention is intended to solve or reduce the above-mentioned conventional problems, and a mirror reinforcing structure capable of effectively and reliably reinforcing a mirror with a smaller amount of material and lower cost. An object is to provide an optical scanning device, an image reading device, and an image forming apparatus.

  In order to achieve the object, the invention according to claim 1 is a mirror reinforcing structure in which a mirror reinforcing member is fixed to a side surface adjacent to a reflecting surface in an elongated mirror, and the mirror in the mirror reinforcing member is provided. The amount of protrusion in the direction perpendicular to the reflecting surface is set so that the mirror reflecting surface side is equal to the mirror back surface side opposite to the mirror reflecting surface side. By arranging the reinforcing member in a balanced manner, it is possible to prevent the occurrence of low-frequency mode vibrations that cause the mirror reflecting surface to be twisted. Therefore, even if the width of the reinforcing member is increased, It can be suppressed that the reflection direction of the light is largely deviated by the vibration of.

  According to a second aspect of the present invention, in the mirror reinforcing structure according to the first aspect, the amount of protrusion of the mirror reinforcing member in the direction substantially perpendicular to the reflecting surface of the mirror toward the rear surface of the mirror is the length in the short direction of the mirror. This configuration is characterized by the following, and this configuration can prevent the resonance of the vibration mode in the rotational direction centering on the axis parallel to the longitudinal direction of the mirror from appearing at a low frequency, and thereby a large reinforcing member Therefore, it is possible to perform efficient mirror reinforcement without obtaining a sufficient mirror reinforcement effect even when using the above-mentioned.

  According to a third aspect of the present invention, in the mirror reinforcing structure according to the first or second aspect, the material of the mirror base material is a glass material, and the material of the mirror reinforcing member is an iron-based sheet metal material. According to the configuration, it is possible to form a highly accurate reflective surface at a low cost and to obtain a sufficient mirror reinforcing effect at a low cost.

  According to a fourth aspect of the present invention, in the optical scanning device that performs optical scanning on the image surface using an optical component, the mirror reinforcing structure according to any one of the first to third aspects is adopted as a part of the optical component. This configuration is characterized in that the optical characteristics of the optical system are stabilized and highly reliable optical scanning is possible.

  According to a fifth aspect of the present invention, in the image reading apparatus that optically reads image information from a reading target using an optical component, the mirror reinforcing structure according to any one of the first to third aspects is provided in a part of the optical component. Is used, and this configuration stabilizes the optical characteristics of the optical system and makes it possible to read image information with high reliability.

  According to a sixth aspect of the present invention, there is provided an optical scanning unit that optically scans an image surface using an optical component, an image reading unit that optically reads image information by optical scanning of the optical scanning unit, and the image reading unit An image forming apparatus comprising an image forming unit that forms an image upon receiving information from a scanning unit, and an optical scanning device according to claim 4 as the optical scanning unit, and claim 5 as the image reading unit. This configuration is characterized in that at least one of the image reading apparatuses is mounted. With this configuration, the optical characteristics of the optical system of each unit are stabilized, and highly reliable image formation is possible.

  According to the mirror reinforcing structure of the present invention, by arranging the reinforcing members in a balanced manner, it is possible to prevent the occurrence of vibrations in a low frequency mode such that the mirror reflecting surface is twisted. Even if the width is increased, it is possible to suppress the light reflection direction from deviating greatly due to vibration in the low frequency range. Therefore, it is not necessary to increase the width of the mirror as in the prior art, and a sufficient amount of mirror reinforcement can be obtained with a minimum amount of mirror reinforcement material and a simple shape. Therefore, the layout can be reduced at low cost. Highly efficient mirror reinforcement is realized.

  Further, by using the mirror employing the mirror reinforcing structure according to the present invention, the optical characteristics in the optical system are stabilized, and highly reliable optical scanning, image reading, image formation, and the like are possible.

  Embodiments of the present invention will be described below.

  First, the vibration simulation used for explaining the embodiment according to the present invention will be described. The simulation described in the column “Problems to be solved by the invention” was also performed under the same conditions as described below.

  A commercially available simulation software by the finite element method was used for the vibration simulation. Moreover, the hexahedral element was used for the mesh, and the maximum length of the element was about 2 to 3 mm.

  The material property values used are as shown in Table 2.

境界条件は、図１の斜視図に示すように、ミラー１の反射面１ａを３点ａ〜ｃで支持し、拘束点ａをｘｙｚ方向拘束、拘束点ｂをｙｚ方向拘束、拘束点ｃをｚ方向拘束とした。通常、ミラー１はバネで押圧されて保持され、支持点は完全な固着ではなく、回転方向は自由な、いわゆる自由支持に近い形態であることから、シミュレーションでも、支持箇所の３点部分とも回転方向は拘束していない。なお、ｘ方向はミラー１の矩形状をなす反射面の一辺の長手方向（ミラーの長さ方向）、ｙ方向はミラー１の反射面の一辺の短手方向（ミラーの幅方向）、ｚ方向はミラー１の反射面の垂直方向（ミラーの厚さ方向）を示す。

As shown in the perspective view of FIG. 1, the boundary condition is that the reflecting surface 1a of the mirror 1 is supported at three points a to c, the restraint point a is restrained in the xyz direction, the restraint point b is restrained in the yz direction, and the restraint point c is The z-direction constraint was used. Normally, the mirror 1 is pressed and held by a spring, and the support point is not completely fixed, and the rotation direction is free. It is a form close to so-called free support. The direction is not constrained. The x direction is the longitudinal direction of one side of the reflecting surface forming the rectangular shape of the mirror 1 (mirror length direction), the y direction is the short side direction of one side of the reflecting surface of the mirror 1 (mirror width direction), and the z direction. Indicates the vertical direction of the reflecting surface of the mirror 1 (the thickness direction of the mirror).

  Between the reinforcing member 2 and the mirror 1, as shown in the side view of FIG. In addition to adhesive fixing, even when the two-sided tape 3 is used for bonding, the reinforcing member 2 and the mirror 1 do not move independently at least in a low frequency region where vibration is a problem in practice. It can be simulated as a completely fixed state. Further, it can be seen from Patent Document 3 that a sufficiently large effect can be obtained if not less than the entire surface is bonded to three or more locations in the longitudinal direction. Therefore, the application of the present invention is not limited to the entire surface fixing.

Next, the standard of the required reinforcement effect is demonstrated. There are two countermeasures (b) and (b) below as effective means for countermeasures against mirror vibration.
(A) By increasing the rigidity of the mirror, the amplitude is reduced to the extent that the optical characteristics are not affected even if the mirror resonates.
(B) The resonance frequency of the mirror is shifted from the frequency of the excitation source so that the mirror does not resonate.

  In general, when the resonance frequency is increased by increasing the rigidity, the amplitude at the time of resonance is reduced even if resonance occurs. In the case of a mirror that is the subject of the present invention, if the primary resonance frequency is 300 Hz or more, even if it resonates, the displacement is sufficiently small, and optical properties are hardly affected.

  Therefore, if the measure (A) can be realized, the mirror amplitude is small regardless of the frequency of the excitation source, and the vibration of the mirror does not affect the optical characteristics. However, it is not always possible to implement the measure (b) because of layout considerations such as the size of the apparatus and cost problems. In such a case, it is preferable to shift the resonance frequency of the mirror from the frequency of the excitation source so that the mirror does not resonate as a countermeasure (b).

  Here, an example of the vibration characteristic (transfer function) of the mirror is shown in FIG. FIG. 3 shows the transfer function obtained by simulation when the mirror shape is 260 mm and 240 mm long, 10 mm wide × 5 mm thick (no reinforcing member). The vertical axis shows the displacement of the central portion in the longitudinal direction of the mirror per force (1N) to be excited. FIG. 3 shows that the amplitude can be reduced to about one-tenth of the amplitude at the time of resonance if it is shifted from the primary resonance frequency by about 20 Hz to 30 Hz regardless of the shape of the mirror.

  That is, if the mirror vibrates greatly without the reinforcing member, the frequency of the excitation source overlaps with the primary resonance frequency of the mirror and resonates. If the primary resonance frequency of the mirror can be shifted by about 20 Hz to 30 Hz by pasting, the amplitude of the mirror can be reduced to about 1/10. In other words, even if the reinforcing member is attached, if the primary resonance frequency does not change by 20 Hz or more, the reinforcing effect is extremely limited and is likely to be insufficient.

  FIG. 4 is a block diagram showing Embodiment 1 of the mirror reinforcing structure according to the present invention. In addition, in the following description, the same code | symbol is attached | subjected to the thing corresponding to the already demonstrated member.

  The configuration of the first embodiment is basically the same as that shown in FIG. 1, but in this example, a rectangular reinforcing member 2 is applied to the rectangular mirror 1 and the reflection on the reflecting surface 1 a side of the mirror 1 is reflected. The protrusion amount of the surface side protruding portion 2a and the back surface side protruding portion 2b on the back surface 1b side are made equal, and the intermediate portion 2c of the reinforcing member 2 is attached to the side surface 1c of the mirror 1. Regarding the reinforcing member 2, the x direction is the longitudinal direction of one side of the rectangular surface (the length direction of the reinforcing member), the y direction is the direction perpendicular to the surface (the thickness direction of the reinforcing member), z The direction indicates a short side direction (width direction of the reinforcing member) of one side of the surface.

  As described above, the fact that the longer the width of the reinforcing member 2 is, the higher the reinforcing effect is not obtained, which has not been known so far, is new from the vibration simulation results performed by the inventors. It was found out.

  That is, according to the simulation, when the width of the reinforcing member is short, the vibration mode in the direction of arrow B in FIG. 12 appears first, whereas when the protruding amount of the reinforcing member is too long, it becomes weak in the direction of arrow A in FIG. Thus, it was found that the vibration mode in this direction appears first.

  Therefore, as shown in FIG. 12, the reinforcing member 2 is arranged on the reflecting surface 1a side and the back surface 1b side of the mirror 1 as shown in FIG. When the protrusions are evenly projected, the reinforcing member 2 is arranged with a good balance with respect to the mirror 1, so that the vibration mode in the direction of arrow A in FIG. Thereby, the mirror 1 can be reinforced to a higher primary resonance frequency.

  FIG. 5 shows the result of the vibration simulation performed to verify the operational effects of the first embodiment. FIG. 5 is a plot of the primary resonance frequencies obtained by simulating the structural examples 1 to 4 shown in (Table 3) while changing the width of the reinforcing member. However, the configuration examples 1 and 2 are comparative examples of the configuration in which the reinforcing member 2 ′ protrudes only in the reflective surface 1 a side of the mirror 1 (z direction) as shown in FIG. Is due to.

図５に示すように、実施例１の構成を採用した構成例３では補強部材幅約２０ｍｍ、構成例４では補強部材幅約３０ｍｍにて、それぞれ一次共振周波数の最大値を示している。

As shown in FIG. 5, the configuration example 3 adopting the configuration of the first embodiment shows the maximum value of the primary resonance frequency at the reinforcing member width of about 20 mm, and the configuration example 4 at the reinforcing member width of about 30 mm.

  In this case, the amount of protrusion on the mirror reflecting surface side of the reinforcing member = the amount of protrusion on the mirror back surface side of the reinforcing member = (reinforcing member width−mirror thickness) / 2. When the width of 2 is 20 mm and 30 mm, the amount of protrusion on the reflecting surface 1 a side and the amount of protrusion on the back surface 1 b side of the mirror 1 in the reinforcing member 2 are both substantially equal to the width of the mirror 1.

  Therefore, if the protruding amount of the reinforcing member 2 is made equal to or less than the mirror width, an efficient mirror reinforcing effect corresponding to the width of the reinforcing member 2 can be obtained. On the other hand, it can be seen that if the protruding amount of the reinforcing member 2 is greater than or equal to the mirror width, the reverse effect is obtained.

  Further, in FIG. 5, when the results of the configuration examples 3 and 4 are compared with the results of the configuration examples 1 and 2 using the same shape mirror and the reinforcing member having the same length and thickness, On the other hand, by making the reinforcing member 2 protrude evenly on both sides of the mirror 1, the maximum value of the primary resonance frequency when the width of the reinforcing member is changed is extremely large, and vibration in the low frequency mode is generated. It can be prevented and found to be effective.

  In the simulation in the embodiment described above, the mirror material is float glass. However, as long as E / ρ (E: Young's modulus, ρ: density) is not significantly different from that of float glass, it can be used in materials other than float glass. A similar effect can be obtained. In the simulation, the reinforcing member is made of an iron-based sheet metal material. However, if E / ρ is not significantly different from the iron-based sheet metal material, the same effect can be obtained in materials other than the iron-based sheet metal material. Is obtained.

  Therefore, the effect in the said Example is not restricted to a float glass and an iron-type sheet metal material. However, if the mirror material is float glass, high surface accuracy can be obtained at a lower cost. If the reinforcing member is an iron-based sheet metal material, the material cost and processing cost of the reinforcing member are extremely low, and a high reinforcing effect can be obtained. Therefore, it is desirable that the material of the mirror is float glass and the material of the reinforcing member is an iron-based sheet metal material.

  In the above embodiment, all the mirrors are plane mirrors, but the application of the present invention is not limited to this, and the same effect can be obtained even when applied to a curved mirror such as a cylindrical mirror.

  FIG. 7 is a perspective view showing a configuration of an embodiment of an optical scanning device using a split housing in which a mirror having a mirror reinforcing structure according to the present invention can be used in an optical system, and FIG. 8 is a deflection in FIG. It is a block diagram which shows the example of arrangement | positioning of the optical element from a container to a photoreceptor.

  In the optical scanning device shown in FIG. 7, light beams emitted from the light source units 11a to 11d made of laser diodes or the like are deflected by a deflector 12 such as a polygon mirror through a cylindrical lens, respectively, and two scanning imaging elements and mirrors The image is scanned on the image plane via the. The arrangement of the optical elements in the optical path after the deflector 12 is as shown in FIG.

  As shown in FIG. 8, the deflector 12 includes polygon mirrors 12a and 12b in two upper and lower stages, and the four light beams L from the four light source units 11a to 11d in FIG. 12a and 12b are respectively deflected and passed through the first scanning imaging element 13 and the four second scanning imaging elements 14 in a two-tiered arrangement arranged on the left and right sides, respectively, to the four photoreceptors 15a to 15d. Form an image and scan.

  In the optical scanning device of FIG. 7 using the optical system having the structure shown in FIG. 8, all the 12 mirrors 16 have the same length, and are bridged between two opposing side plates 17 and 17 made of sheet metal. Held. Further, the four second scanning imaging elements 14 are respectively held by sheet metal stays that are bridged to the opposing side plates 17 and 17. The side plates 17 and 17 are connected by opposing side plates 18 and 18 to form an outer casing.

  Also, as shown in FIG. 7, the four light source units 11a to 11d, the cylindrical lens, the deflector 12, and the first scanning imaging element 13 are attached to a housing 19 that is integrally formed of resin. The housing 19 is bridged and fixed to the side plates 17 and 17 and the side plates 18 and 18. The lower openings that are not blocked by the four side plates 17 and 18 and the bottom surface of the housing 19 are blocked by the lower covers 20 and 20 so that dust does not enter the optical box. Although not shown, the upper opening is also closed by the upper cover. However, since the light beam is emitted upward in this optical scanning device, the upper cover is provided with an opening covered with glass that transmits light.

  Here, the periphery of the deflector 12 is surrounded by a rib formed integrally with the housing 19 and glasses 21 and 21 arranged in a portion through which the light beam passes. Further, the periphery of the deflector 12 is hermetically sealed by covering the upper opening with the cover 22, thereby reducing wind noise generated by the rotation of the deflector 12 and heat generated by the deflector 12 from leaking outside the apparatus. be able to.

  In the case where the generated sound does not matter so much because the rotation of the deflector 12 is relatively slow or the outer shape of the polygon mirrors 12a and 12b is small, the gap between the rib of the housing 19 and the cover 22 is not significant. A gap may be formed so that all the heat generated by the deflector 12 is not retained in the housing 19 but may be slightly diffused in the apparatus.

  As in the present embodiment, in the optical scanning device that holds each mirror 16 by bridging between the side plates 17 and 17, the shape of most or all of the mirrors is the same. If the structure as shown in the embodiment of the mirror reinforcing structure is applied, the shape of the reinforcing member can be unified in addition to the shape of the mirror, the number of parts is reduced, and the cost is also reduced. be able to. In addition, since the shape of the mirror and the reinforcing member attached to it can be unified, if the reinforcing member is attached to the mirror and delivered to the assembly factory of the optical scanning device, distribution was included. Since the transportation cost can be reduced, the degree of freedom in designing the production process in the entire optical scanning device can be increased.

  The configuration of the optical scanning device to which the present invention can be applied is not limited to the configuration in which the mirror is bridged and held between the side plates. For example, the optical scanning device is integrally formed in a box shape with resin or aluminum. The same effect can be obtained when applied to an optical scanning device using an optical box.

  FIG. 9 is a configuration diagram of an embodiment of an image reading apparatus using a mirror having a color reinforcing structure according to the present invention in an optical system.

  As shown in FIG. 9, a first traveling body 25 and a second traveling body 26 are arranged below the contact glass 24 on which the document D is placed. The first traveling body 25 includes an illumination lamp 27 and a first mirror 28a, and the illumination lamp 27 and the first mirror 28a can move integrally. The first mirror 28a reflects the reflected light from the document D in the horizontal direction. The second traveling body 26 includes a second mirror 28b and a third mirror 28c, and the second mirror 28b and the third mirror 28c are movable together.

  The second mirror 28b and the third mirror 28c are obliquely arranged so that the reflection surfaces are perpendicular to each other, and the reflected light from the first mirror 28a is folded back in the horizontal direction. The reflected light is imaged on the CCD 30 as a photoelectric conversion element by the lens 29. In this way, the image information of the original is taken out from the CCD 30 as an electrical signal.

  Both the first traveling body 25 and the second traveling body 26 are movable in the direction of the arrow shown in FIG. 9 using a traveling body motor (not shown) as a drive source. At this time, in order to keep the optical distance from the document being exposed to the CCD 30 constant, the first traveling body 25 moves at a speed V twice that of the second traveling body 26. 9 indicates the positions of the mirrors 28a to 28c after the original D is scanned.

  If the mirrors 28a to 28c of such an image reading apparatus are configured as shown in the embodiment of the mirror reinforcing structure, the vibration of the mirror can be reduced at low cost and the image data read as electronic information can be reduced. Therefore, it is possible to provide an image reading apparatus that does not cause line fluctuations that are not present in the original.

  FIG. 10 is a block diagram of an embodiment of the image forming apparatus on which the optical scanning device described in FIGS. 7 and 8 and the image reading apparatus in FIG. 9 are mounted according to the present invention.

  As shown in FIG. 10, the drum corresponding to each of the four colors of black, cyan, magenta, and yellow according to the image information of the document read by the image reading device 40 or the image information sent from a personal computer or the like. A latent image is written on the photoconductor 41 by the optical scanning device 42.

  Around each photosensitive member 41, a charging charger 43 that charges the photosensitive member 41 to a high voltage, a developing roller 44 that attaches a charged toner to an electrostatic latent image recorded by the optical scanning device 42, and develops the image, development A toner cartridge 45 for supplying toner to the roller 44 and a cleaning unit 46 for scraping and collecting the toner remaining on the photoreceptor 41 are disposed.

  Image forming stations configured around the respective photoconductors 41 are arranged in parallel in the moving direction of the transfer belt 47, and toner images of yellow, magenta, cyan, and black are sequentially transferred onto the transfer belt 47 in time, A color image is formed by superposition.

  Each image forming station has basically the same configuration except that the toner color is different.

  On the other hand, the recording paper P is supplied from the paper supply tray 48 by the paper supply roller 49, and is sent out by the registration roller pair 50 in accordance with the recording start timing in the sub-scanning direction, and the color image is transferred from the transfer belt 47, After the transfer, the image is fixed by the fixing unit 51 and discharged to the paper discharge tray 53 by the paper discharge roller 52.

  Further, the image forming apparatus to which the present invention is applied is not limited to the color image forming apparatus as described above, but in the tandem type image forming apparatus using a plurality of the photosensitive bodies 41 as shown in FIG. Since the number of mirrors used in the optical scanning device increases in accordance with the number of optical elements, a greater effect can be obtained by applying the present invention.

  In addition, in a tandem type image forming apparatus, if each color image formed on a plurality of photoconductors cannot be formed at the correct position, an image deterioration phenomenon called color misregistration occurs, resulting in poor color reproducibility. Since the required accuracy with respect to the optical characteristics of the image reading device and the optical scanning device is higher than that of the monochrome image forming device, the present invention can be applied to obtain a higher quality output image at a lower cost. Is effective.

  The present invention is applied to an image forming apparatus equipped with an optical scanning device and an image reading device such as a copying machine, a facsimile machine, and a printer, and is particularly effective as a mirror reinforcing structure for reinforcing an elongated mirror.

The perspective view which shows schematic structure of embodiment which concerns on this invention Side view of the mirror reinforcement structure of FIG. The figure which shows the difference in the vibration characteristic (transfer function) by the length of the mirror which concerns on this embodiment 1 is a configuration diagram showing a first embodiment of a mirror reinforcing structure according to the present invention. The figure which shows the result of having performed the vibration simulation in order to verify the effect of Example 1. The block diagram which shows the comparative example of the structure which made the reinforcement member project only the reflective surface of a mirror The perspective view which shows the structure of the Example of the optical scanning device using the split-type housing which can use the mirror which comprises the mirror reinforcement structure based on this invention for an optical system. FIG. 7 is a configuration diagram showing an example of arrangement of optical elements from the deflector to the photosensitive member in FIG. 1 is a configuration diagram of an embodiment of an image reading apparatus using a mirror having a color reinforcing structure according to the present invention in an optical system. 7 is a configuration diagram of an embodiment of an image forming apparatus equipped with the optical scanning device described in FIGS. 7 and 8 and the image reading device in FIG. The figure which shows the result of having measured the primary resonant frequency when sticking a reinforcement member (iron plate) to the conventional mirror and changing the width (reinforcement plate width) of the reinforcement member Configuration diagram showing a conventional mirror reinforcement structure

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mirror 1a Reflective surface 2 Reinforcing member 2a Reflective surface side protrusion 2b Back surface side protrusion L Light beam 16 Mirror 28a First mirror 28b Second mirror 28c Third mirror

Claims (6)

A mirror reinforcing structure in which a mirror reinforcing member is fixed to a side surface adjacent to a reflecting surface in an elongated mirror,
The amount of protrusion of the mirror reinforcing member in the direction perpendicular to the reflection surface of the mirror is set so that the mirror reflection surface side is equal to the mirror back surface side opposite to the mirror reflection surface side. Mirror reinforcement structure characterized by.   2. The mirror according to claim 1, wherein an amount of protrusion of the mirror reinforcing member in a direction substantially perpendicular to the reflection surface of the mirror toward the rear surface of the mirror is set to be equal to or less than a length in a short direction of the mirror. Reinforced structure.   The mirror reinforcing structure according to claim 1 or 2, wherein a material of the base material of the mirror is a glass material, and a material of the mirror reinforcing member is an iron-based sheet metal material. In an optical scanning device that performs optical scanning on an image surface using an optical component,
An optical scanning device using a mirror in which the mirror reinforcing structure according to claim 1 is employed as a part of the optical component. In an image reading apparatus that optically reads image information from a reading target using an optical component,
An image reading apparatus using a mirror in which the mirror reinforcing structure according to any one of claims 1 to 3 is used as a part of the optical component. An optical scanning unit that performs optical scanning on an image surface using an optical component, an image reading unit that optically reads image information by optical scanning of the optical scanning unit, and image formation that receives information from the image reading unit In an image forming apparatus comprising an image forming unit for performing
An image forming apparatus comprising at least one of the optical scanning device according to claim 4 as the optical scanning unit and the image reading device according to claim 5 as the image reading unit.

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