JP2008185995A - Mirror reinforcement method, mirror, optical scanner, image reading apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mirror reinforcement method by which an effective, assured and necessary reinforcement effect is inexpensively available with a small amount of materials, and to provide a mirror which is reinforced by the mirror reinforcement method. <P>SOLUTION: The mirror reinforcement method is used for reinforcing a mirror 1 having a slender reflection face 1a, by which a reinforcement member 2 is fixed on the side face of the mirror 1 with respect of the reflection face 1a, and the reinforcement member 2 satisfies the condition 0.8×Lm≤Lh, where Lm represents the length (mm) of the mirror in the longitudinal direction, Lh represents the length (mm) of the reinforcement member in the longitudinal direction, consequently there is no possibility that a sufficient reinforcement effect is unavailable in spite of the attachment of the reinforcement member, and an effective mirror reinforcement is available. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a method for reinforcing a mirror having a shape in which a reflecting surface is elongated, a mirror reinforced by the mirror reinforcing method, an optical scanning device or an image reading device using the mirror, and the optical scanning device or the image reading device. The present invention relates to an image forming apparatus.

In an image forming apparatus such as a copying machine using electrophotographic technology, an image reading apparatus that reads an original image, an image that is read by an image reading apparatus, or an image information for forming an output image transmitted from a personal computer or the like is used. A mirror is used in an optical scanning device that writes a latent image on an image carrier.
Mirrors used in these image forming apparatuses are used to change the direction of light rays by reflecting a linear light beam or a linearly scanned light beam. Accordingly, these mirrors generally have a very long and narrow shape, and in many cases, only the vicinity of both ends of the mirror can be held so as not to block light. Due to the shape of the mirror and the holding method, the mirror used in the image forming apparatus is very likely to vibrate.

  When the mirror of an image reading device or optical scanning device vibrates, the mirror generates a vibration that deforms in an arcuate shape with the holding parts at both ends as fulcrums. Therefore, the magnification of the mirror in the longitudinal direction and the bending of the light line in the short direction of the image information read in accordance with this or the image information written on the image plane cause a periodic shift. Periodic shifts in magnification in the longitudinal direction result in periodic fluctuations in the lines of the output image, and periodic shifts in bending in the short direction cause periodic image shading called banding. Both cause degradation of image quality.

  It has been well known that the thickness of the mirror should be increased in order to reduce the vibration of the mirror. Here, float glass is generally used as the material of the mirror. Float glass is used because it can be formed cheaply from its construction method and high flatness can be obtained. 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 direction parallel to the reflecting surface must be cut out.

  Here, in the case of the size of a mirror generally used in an image forming apparatus, if the plate thickness is 6 mm or less, the glass surface is scratched with a diamond cutter or the like and then lightly shocked. Then cut along the scratches. However, when the plate thickness exceeds 6 mm, it is difficult to fold along the scratch well, 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, and as a result, the processing cost becomes considerably high when using this method. Therefore, when the mirror is thickened, not only the material cost but also the processing method changes, and the processing cost becomes considerably high (much higher than the parts cost of the reinforcing member described later). Therefore, the mirror thickness should be 6 mm or less as much as possible. There are circumstances that you want to keep.

  In order to improve the vibration resistance of the mirror with respect to this problem, various techniques have been conventionally proposed. For example, Patent Document 1 describes that a mirror is reinforced by attaching a reinforcing member to the back surface of the reflecting surface of the mirror. However, in this method, since the mirror is aligned with the flatness of the reinforcing member, the flatness of the reinforcing member is also required to maintain the flatness of the mirror reflecting surface with high accuracy. Therefore, there is a problem that reinforcement at low cost is difficult.

  On the other hand, as a technique for solving this problem and the problem of vibration, an optical folding mirror described in Patent Document 2 has been proposed. In the prior art described in Patent Document 2, since the reinforcing member is attached to the side surface of the reflecting surface of the mirror, even if the flatness of the reinforcing member is not so high, the mirror follows the reinforcing member and is parallel to the reflecting surface. Therefore, the mirror can be reinforced without substantially affecting the flatness of the reflecting surface. Therefore, it is claimed that there is a merit that the vibration resistance of the mirror can be improved at a very low cost.

Japanese Utility Model Publication No. 1-142913 JP-A-10-282399 JP 2006-154116 A

  Such an elongated mirror used in an optical scanning device, an image reading device or the like is usually supported near both ends in the longitudinal direction. Specifically, the back surface of the reflecting surface is pressed with a spring and the reflecting surface is abutted against the support member. In addition, the position in the short direction of the reflective surface is also large, such as by using a spring to abut against the support member, or by using a restricting member that is arranged with a slight gap without using a spring. Do not slip. Accordingly, support members, springs, restricting members, and the like are disposed in the vicinity of both ends in the longitudinal direction of the mirror so that the layout is hindered when the mirror reinforcing member projects from the mirror. Each shape becomes complicated, and the reliability of holding the mirror is impaired.

  Furthermore, the present inventors performed a vibration simulation by the finite element method for the mirror reinforcing method of the form proposed in Patent Document 2. The results are shown in Table 1 below and FIG. From this result, it was newly found that the conventional technique described in Patent Document 2 has the following two problems.

(1) If something hard member is stuck on the mirror, it is not always reinforced. Even if an iron plate is attached, the resonance frequency may not increase.
For example, when a steel plate of length 254 mm × thickness 1 mm is attached to a mirror of length 254 mm × width 10 mm × thickness 5 mm, the primary resonance frequency of the mirror with respect to the width of the reinforcing member (iron plate) is shown in Table 1 and FIG. It was shown in 2. Here, the primary resonance frequency in the case of no reinforcing member is shown as a reinforcing plate width of 0 mm for convenience. 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 compared to a case where nothing is attached.

(2) Conventionally, it has been considered that the resonance frequency increases as the width of the reinforcing member increases. However, as shown in Table 1, the resonance frequency increases as the width of the reinforcing member increases. It doesn't mean that
As shown in Table 1 and FIG. 2, when the reinforcing plate width is 45 mm, the primary resonant frequency is lower by 74 Hz than when the reinforcing plate width is 20 mm, and the primary resonant frequency is lowered despite the increase in the width of the reinforcing member. ing.

In the past, it was vaguely thought that the mirror would be reinforced if a reinforcing member was attached, and that the reinforcing effect would be greater as the width of the reinforcing member was larger, but the shape and size of the reinforcing member that can be used practically From the results of (1) and (2) above, it is clear that these recognitions are wrong in the range, and the required effect is not obtained, or sometimes the effect is not obtained at all. It was.
In particular, when a support method that does not completely constrain the rotation direction is used, the rigidity is not so high against torsional deformation with the mirror longitudinal direction as the rotation axis. Here, if the width of the reinforcing member is increased, mass is added at a position far from the above-described rotation shaft, so that it is easily affected by the vibration mode in the torsional direction. As a result, even if the width of the reinforcing member is increased. On the contrary, the phenomenon that the vibration resistance is lowered is generated. Therefore, it is necessary to design in consideration of the vibration mode in the torsional direction.

  The present invention has been made in view of the above circumstances, and is intended to solve or reduce the problems of the prior art, particularly effectively and reliably with a smaller amount of material and a lower cost. An object of the present invention is to provide a mirror reinforcing method capable of obtaining a necessary reinforcing effect. An object of the present invention is to provide a mirror reinforced by the mirror reinforcing method, an optical scanning device or an image reading device using the mirror, and an image forming apparatus including the optical scanning device or the image reading device. To do.

In order to achieve the above object, the present invention adopts the following means.
A first means of the present invention is a method for reinforcing a mirror having a shape in which a reflecting surface is elongated, wherein a reinforcing member is fixed to a side surface of the mirror with respect to the reflecting surface, and the reinforcing member satisfies the following conditional expression: It is characterized by satisfying.
0.8 × Lm ≦ Lh
Lm: Length in the longitudinal direction of the mirror (mm)
Lh: Length in the longitudinal direction of the reinforcing member (mm)

According to a second means of the present invention, in the mirror reinforcing method of the first means, a length Lh in the longitudinal direction of the reinforcing member is shorter than a length Lm in the longitudinal direction of the mirror.
According to a third means of the present invention, in the mirror reinforcing method of the first means, a notch is provided in the vicinity of the end of the mirror of the reinforcing member.

A fourth means of the present invention is a method for reinforcing a mirror having a shape in which a reflecting surface is elongated, and a reinforcing member is fixed to a side surface of the mirror with respect to the reflecting surface, and the direction is substantially perpendicular to the reflecting surface of the mirror. The following conditional expression is satisfied.
Wh ≧ (−1.1 × ln (Th) +2.7) × (Lm / 250) ^ 1.3
× (Tm / 5) ^ 0.2 × (Wm / 10) ^ 0.5 + Tm
Wh: width of the reinforcing member (mm)
ln (Th): natural logarithm of Th Th: thickness of reinforcing member (mm)
Lm: Length in the longitudinal direction of the mirror (mm)
Tm: Thickness (mm) in a direction substantially perpendicular to the reflecting surface of the mirror
Wm: Mirror width (mm)

According to a fifth means of the present invention, in the mirror reinforcing method according to any one of the first to fourth means, the material of the base material of the mirror is a glass material, and the material of the reinforcing member is an iron-based sheet metal material. It is characterized by being.
The sixth means of the present invention is a mirror having a shape in which the reflecting surface is elongated and is reinforced by the mirror reinforcing method of any one of the first to fifth means.

According to a seventh means of the present invention, in an optical scanning device that deflects light from a light source with a deflector and scans on an image surface, a mirror disposed in an optical path from the deflector to the image surface includes It is characterized by using a mirror of the means.
According to an eighth means of the present invention, an image of a document is imaged on a photoelectric conversion element through a mirror and a lens, and in the image reading apparatus for reading image information of the document, the mirror of the sixth means is included in the mirror. It is characterized by using.
The ninth means of the present invention is an image forming apparatus, characterized in that it comprises an optical scanning device as the seventh means or an image reading device as the eighth means, and forms an image.

In the mirror reinforcing method of the first means of the present invention, there is no such a situation that a sufficient mirror reinforcing effect cannot be obtained even when the reinforcing member is attached, and efficient mirror reinforcement can be performed.
Further, in the mirror reinforcing method of the second means, in addition to the function and effect of the first means, a mirror having a simple configuration without using a support member having a complicated shape and without impairing the mirror reinforcing effect. Can be supported.
Furthermore, in the mirror reinforcing method of the third means, in addition to the function and effect of the first means, a mirror having a simple structure can be used without using a support member having a complicated shape and without impairing the mirror reinforcing effect. Support is possible.

In the mirror reinforcing method of the fourth means, a sufficient mirror reinforcing effect is not obtained even when the reinforcing member is attached, and it is efficient (minimum amount of material of the reinforcing member and extremely simple) (A sufficient mirror reinforcing effect can be obtained with a simple shape).
In addition, in the mirror reinforcing method of the fifth means, in addition to the operational effect of any one of the first to fourth means, it is possible to form a reflective surface having a highly accurate surface shape at low cost, and it is sufficient at low cost. A mirror reinforcing method capable of obtaining a reinforcing effect can be realized.
Further, since the mirror of the sixth means is reinforced by the mirror reinforcement method of any one of the first to fifth means, the function and effect of any one of the first to fifth means can be obtained and vibration can be obtained. It is possible to realize a mirror with reduced occurrence of the low cost.

In the optical scanning device of the seventh means, by using the mirror of the sixth means, it is possible to reduce the image deterioration of the written image due to the vibration of the mirror.
Further, according to the image reading apparatus of the eighth means, by using the mirror of the sixth means, it is possible to reduce image deterioration of the read image due to the vibration of the mirror.
Further, the image forming apparatus of the ninth means includes the optical scanning device of the seventh means or the image reading apparatus of the eighth means, and forms an image, so the image of the written image or the read image by the vibration of the mirror is formed. Deterioration can be reduced at low cost.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

<About vibration simulation>
First, the vibration simulation used in the present invention will be described. The simulation described in the above-mentioned “problem to be solved by the present invention” is 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 below.

FIG. 3 is an explanatory view of a mirror reinforcing method according to the present invention. FIG. 3 (a) is a perspective view of the mirror 1 reinforced by a plate-like reinforcing member (reinforcing plate) 2 used for vibration simulation. FIG. (B) is a view seen from the direction of arrow A in FIG. As shown in FIG. 3A, the boundary condition is that the mirror reflecting surface is supported at three points, the first restraint point 4-1 is restrained in the xyz direction, the second restraint point 4-2 is restrained in the yz direction, 3 constraint point 4-3 was defined as z-direction constraint. In this example, the mirror 1 is pressed and held by a spring (not shown), and the support point is not completely fixed, and the rotation direction is close to a so-called free support. The rotation direction of both points is not constrained.
Between the reinforcing member 2 and the mirror 1, as shown in FIG. In addition, in addition to adhesive fixation, even when pasting with double-sided tape, at least in the low frequency range where vibration is a problem in practice, the reinforcing member 2 and the mirror 1 do not move independently. It can be simulated as a completely fixed state. In addition, since it can be seen from known examples such as Patent Document 3 that a sufficiently large effect can be obtained if three or more portions are bonded in the longitudinal direction even if it is not the entire surface, the application of the present invention is limited to the entire surface fixing. is not.

<About the required reinforcement effect>
There are the following two effective means as countermeasures against vibration of the mirror 1.
[1] By increasing the rigidity of the mirror 1, even if it resonates, the amplitude is reduced to such an extent that the optical characteristics are not affected.
[2] The resonance frequency of the mirror 1 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 decreases accordingly even if resonance occurs. In the case of the mirror 1 as an object of the present invention, if the primary resonance frequency is 300 Hz or more, even if it resonates, the displacement is sufficiently small and hardly affects the optical characteristics.
Therefore, if the above measure [1] can be realized, the amplitude of the mirror is small regardless of the frequency of the excitation source, and the vibration of the mirror does not affect the optical characteristics. However, measures [1] cannot always be realized due to layout considerations such as the size of the device and cost issues. In such a case, as described in the measure [2] above, it is preferable to shift the resonance frequency of the mirror 1 from the frequency of the excitation source so that the mirror 1 does not resonate.

Here, an example of a vibration characteristic called a transfer function of the mirror 1 is shown in FIG. FIG. 4 shows the transfer function obtained by simulation when the mirror shape is 260 mm and 240 mm in length, width 10 × thickness 5 mm (without a reinforcing member). The vertical axis indicates the displacement of the central portion in the longitudinal direction of the mirror per 1 N of the exciting force.
From FIG. 4, it can be seen that the amplitude can be reduced to about 1/10 of the amplitude at the time of resonance if it deviates by about 20 to 30 Hz from the primary resonance frequency regardless of the shape of the mirror. In other words, if the mirror 1 vibrates greatly without a reinforcing member, the frequency of the excitation source overlaps with the primary resonance frequency of the mirror 1 and resonates. If the primary resonance frequency of the mirror 1 can be shifted by about 20 to 30 Hz by attaching the reinforcing member 2, the amplitude of the mirror 1 can be reduced to about 1/10. In other words, even if the reinforcing member 2 is pasted, 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.

  Hereinafter, more specific examples of the present invention will be described.

[Example 1]
FIG. 1 shows a first embodiment of the present invention. FIG. 1A is a perspective view of a mirror 1 reinforced by a plate-like reinforcing member (reinforcing plate) 2, and FIG. 1B is a view seen from the direction of arrow A in FIG. is there.
As shown in FIG. 1, the length of the mirror 1 in the longitudinal direction (x direction) is Lm, the thickness in the direction perpendicular to the reflecting surface 1a (z direction) is Tm, and the transverse direction (y direction) of the reflecting surface 1a. The length of the reinforcing member (reinforcing plate) 2 in the x direction is Lh, the thickness in the y direction is Th (not shown), and the width in the z direction is Wh. The unit of length is mm unless otherwise specified.
The reinforcing member (reinforcing plate) 2 is formed so that the reflecting surface side protruding amount and the back surface side protruding amount are equal in the z direction, and the midpoint of Lm and the midpoint of Lh coincide with each other in the x direction. Affixed to the side.

The results of the vibration simulation performed on the mirror 1 having such a configuration are shown in FIGS. Materials, restraint conditions, and the like other than the above configuration are the same as the simulation conditions described above (FIG. 3 and Table 2). In all of FIGS. 5 to 7, the thickness Th of the reinforcing member (reinforcing plate) 2 is 1 mm.
FIG. 5 shows a reinforcing effect when the widths Wh and Lh of the reinforcing member 2 are swung when the mirror shape Lm × Wm × Tm is 250 × 10 × 5 (mm). This is a result of simulating the increase in the primary resonance frequency due to pasting. 6 and 7 show the results when the mirror shape Lm × Wm × Tm is 300 × 10 × 5 (mm) and 250 × 15 × 5 (mm), respectively.

From the results of FIGS. 5 to 7, in any case where the shape of the mirror 1 is different, when Lh / Lm is decreased from 1.0, 0.8 to 0.9 is 1.0 and reinforcing. While the effect is hardly changed, the reinforcing effect starts to weaken suddenly at 0.7, and when it becomes 0.6, it decreases to about half of that at 1.0. From this result, when Lh / Lm is set to 0.8 or more, it is possible to realize a mirror reinforcing means that can obtain a substantially maximum reinforcing effect while using the short reinforcing member 2 that does not deteriorate the layout of the mirror support structure. I understand.
In particular, when a support method that does not completely constrain the rotation direction as in this example is used, the rigidity is not so high against torsional deformation with the mirror longitudinal direction as the rotation axis. Here, if the width of the reinforcing member is increased, mass is added at a position far from the above-described rotation shaft, so that it is easily affected by the vibration mode in the torsional direction. As a result, even if the width of the reinforcing member is increased. On the contrary, a phenomenon occurs in which the vibration resistance is lowered. In this example, a reinforcing member with a certain width is attached to the side of the mirror, and at the same time as the vibration in the deflection direction of the mirror, the length of the reinforcing member is made suitable to reduce the vibration in the torsional direction. is doing.

[Example 2]
8 (a) to 8 (c) show a second embodiment of the present invention. 8A is an exploded perspective view showing the mirror 1 reinforced by the plate-like reinforcing member (reinforcing plate) 2 and the supporting member, and FIG. 8B is from the direction of arrow A in FIG. 8A. The figure seen, the figure (c) is the figure seen from the arrow B direction in the figure (a).
In FIG. 8A, three hatched rectangular portions of the reflecting surface of the mirror 1 are supported by the first support member 5-1 and the second support member 5-2, and the mirror 1 The position and inclination of the reflecting surface 1a are determined. At this time, the mirror 1 is pressed against the back surface of the reflecting surface 1a by the presser spring 6 fastened to the first and second support members 5-1 and 5-2 by the screw 7, so that the first and second It is abutted against and held by the support members 5-1 and 5-2. As can be seen from FIGS. 8A and 8B, the first and second support members 5-1 and 5-2 have a U-shape, and the mirror 1 is 0.01. The position of the mirror 1 in the short direction (y direction) is regulated by fitting a gap of about 0.5 mm. In this embodiment, since the reflecting surface 1a of the mirror 1 is a flat surface, a slight positional shift in the short direction (y direction) of the mirror 1 does not affect the optical characteristics. For example, the reflecting surface 1a has a concave shape. In such a case, positional accuracy in the short direction is also required. Therefore, the gap may be reduced, or may be abutted against one side using a spring.

  In addition, in order to prevent complication of the drawing, the regulating member in the longitudinal direction of the mirror 1 is not illustrated, but in practice, the mirror 1 is not displaced greatly in the longitudinal direction of the mirror 1 either. The regulating member is arranged with a slight gap from the end face in the longitudinal direction.

Here, if both longitudinal ends of the reinforcing member 2 are made shorter by about 5 to 20 mm than the mirror 1 as shown in FIG. 8, the reinforcing member 2 does not interfere with the mirror support portion. A mirror holding structure similar to that in the case where the reinforcing member is not used), and therefore, a mirror reinforcing effect using the reinforcing member 2 can be obtained without impairing the layout. For example, when the length of the mirror 1 is 250 mm, even if both ends of the reinforcing member 2 are shortened by 20 mm and the length of the reinforcing member 2 is 210 mm, Lh / Lm = 0.84 and 0.8 or more. As shown in one embodiment (FIG. 5), a sufficient reinforcing effect can be obtained.
Further, the length of the reinforcing member 2 is the same as that of the mirror 1, and as shown in FIG. 9, even if notches having a length of 5 to 20 mm are provided at both ends in the longitudinal direction of the reinforcing member (reinforcing plate) 2, Similar to the example of FIG. 8 described above, the mirror holding structure can be reinforced without impairing the layout. According to such a configuration, the reinforcing member 2 can be positioned by aligning the end portions of the reinforcing member 2 in the longitudinal direction (x direction) and the short direction (z direction) with the end portion of the mirror 1. The work of attaching the reinforcing member 2 to the mirror 1 can be performed more easily.

[Example 3]
As a third embodiment of the present invention, a reinforcing member (which is generally used in an optical scanning device or an image reading device) in a range in which the length Lm of the mirror 1 is 200 to 350 mm and the thickness Tm is 3 to 10 mm. From the result of the vibration simulation at the time of attaching the reinforcing plate 2, the following conditional expression was obtained that can reliably obtain a reinforcing effect of around +30 Hz.
Wh ≧ (−1.1 × ln (Th) +2.7) × (Lm / 250) ^ 1.3
× (Tm / 5) ^ 0.2 × (Wm / 10) ^ 0.5 + Tm
Wh: width of the reinforcing member (mm)
ln (Th): natural logarithm of Th Th: thickness of reinforcing member (mm)
Lm: Length in the longitudinal direction of the mirror (mm)
Tm: Thickness (mm) in a direction substantially perpendicular to the reflecting surface of the mirror
Wm: Mirror width (mm)

  The lower limit values of the thickness and width of the necessary reinforcing member (reinforcing plate) 2 derived from the above conditional expressions with respect to the length Lm of the various mirrors 1 and the thickness Tm of the mirror 1, and by attaching the reinforcing plates The change in the primary resonance frequency is shown in Table 3 below. As shown here, by attaching the reinforcing plate 2 having the minimum shape derived by the above conditional expression, the reinforcing effect of about +30 Hz is surely obtained for any combination of the length and thickness of the mirror 1. It can be seen that

  The conditional expression does not include the length of the reinforcing plate 2. If the reinforcing plate is too short, the reinforcing effect expected in Table 3 cannot be obtained. Thus, if the length of the reinforcing plate 2 is 0.7 × Lm or more, a sufficient reinforcing effect can be obtained. Similarly, as described above, it is better if the length of the reinforcing plate is 0.8 × Lm or more.

The above simulation is performed for a configuration in which the reinforcing member (reinforcing plate) 2 protrudes evenly on both sides of the mirror 1 in the direction perpendicular to the reflecting surface 1a of the mirror 1, for example, as shown in FIG. However, at least the width of the reinforcing member when the reinforcing effect is about +30 Hz, the result does not change so much even with one-side protrusion as shown in FIG. 10B (see Table 4 below). The formula can also be applied when the protrusion amount differs between the mirror reflection surface side and the back surface side.
In addition, the shape of the reinforcing member 2 is not limited to a perfect rectangle. For example, a slight partial cutout for avoiding interference with a rib provided to reinforce the structure of the optical box in which the mirror is installed. There may be a shape.

In the above embodiment, the material of the mirror 1 is float glass in the simulation, but any material other than float glass can be used as long as E / ρ (E: Young's modulus, ρ: density) is not significantly different from float glass. The same effect can be obtained. In the simulation, the reinforcing member (reinforcing plate) 2 is an iron-based sheet metal material. However, if E / ρ is not significantly different from this iron-based sheet metal material, the same applies to materials other than the iron-based sheet metal material. An effect is obtained. Therefore, the operational effects in the above-described embodiments are not limited to the float glass and the iron-based sheet metal material.
However, if the mirror 1 is made of float glass, high surface accuracy can be obtained at a lower cost. If the reinforcing member 2 is an iron-based sheet metal material, the material cost and processing cost of the reinforcing member 2 are extremely low, and a high reinforcing effect can be obtained. Therefore, it is more desirable that the material of the mirror 1 is float glass and the material of the reinforcing member 2 is an iron-based sheet metal material.

The reinforcing member 2 in the present invention does not necessarily have a flat plate shape as shown in FIG. For example, the shape may be bent as shown in FIG. 11, and Wh in this case is the width in the direction perpendicular to the mirror reflecting surface 1a of the reinforcing member 2 (as shown in FIG. )).
In the above embodiments, the mirrors 1 are all flat mirrors, but the application of the present invention is not limited to this, and the same effect can be obtained by applying to curved mirrors such as cylindrical mirrors and fθ mirrors. it can.

[Example 4]
FIG. 12 shows an embodiment of an optical scanning device using a split housing to which the present invention is applied. FIG. 13 shows the arrangement of optical elements from the deflector to the image carrier (photosensitive member) in FIG.
In the optical scanning device shown in FIG. 12 and FIG. 13, the light beams emitted from the semiconductor lasers (LD) of the light source units 406a to 406d are deflected by the deflector 407 through the cylindrical lenses, respectively. The image is scanned on the image plane via 411d, 412a to 412d and a plurality of mirrors 413. The arrangement of the optical elements after the deflector 407 is as shown in FIG. Specifically, the deflector 407 includes two stages of polygon mirrors. The four light beams from the four light source units 406a to 406d in FIG. 12 are deflected by the two-stage polygon mirror mirrors of the deflector 407, respectively. The four photosensitive elements pass through the first scanning imaging elements 411a to 411d having the same two-layer configuration arranged on the left and right sides and through the second scanning imaging elements 412a to 412d arranged in the respective optical paths. Each of the bodies 414a to 414d is imaged and scanned.

  In the optical scanning apparatus of FIGS. 12 and 13 using such an optical system, all twelve mirrors 413 have the same length and are bridged and held by two sheet metal side plates 401 and 402 facing each other. Further, the four second scanning imaging elements 412a to 412d are held by sheet metal stays that are bridged to the side plates 401 and 402 facing each other. Here, the side plates 401 and 402 are connected by the side plates 403 and 404 to form one housing (second housing).

  On the other hand, as shown in FIG. 12, the four light source units 406a to 406d, the cylindrical lens, the deflector 407, and the first scanning imaging elements 411a to 411d are integrally formed with a housing 405 (first housing). Body). The housing 405 is fixed to the side plates 401 and 402 by being bridged. Lower openings that are not blocked by the four side plates and the bottom surface of the housing 405 are blocked by lower covers 408a and 408b 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 portion that is covered with glass that transmits light.

  Here, the periphery of the deflector 407 is surrounded by a rib formed integrally with the housing 405 and soundproof glass 409a and 409b disposed in a portion through which the light beam passes. Further, the periphery of the deflector 407 is sealed by closing the upper opening with the cover 410, thereby greatly reducing the wind noise generated by the rotation of the deflector 407 and the heat generated by the deflector 407 from leaking outside the apparatus. can do.

  In addition, when the sound is not a serious problem because the rotation of the deflector 407 is relatively slow or the outer shape of the polygon mirror is small, a gap is provided between the rib of the housing 405 and the cover 410, All of the heat generated by the deflector 407 may be diffused slightly in the optical box instead of being kept in the deflector housing.

  As in this embodiment, in an optical scanning device that holds a plurality of mirrors 413 by bridging between side plates, most or all of the mirrors have the same shape. If the mirror reinforcing method (mirror 1 reinforced with the reinforcing member 2) as shown in the first to third embodiments is applied, the shape of the reinforcing member can be unified in addition to the shape of the mirror, and thus the number of parts is reduced. In addition, the cost can be reduced. In addition, since the shape of the mirror and the reinforcing member attached to it can be unified, even if the reinforcing member is attached to the mirror and delivered to the assembly factory of the optical scanning device, the transportation cost including material handling can be reduced. Since the cost can be reduced, it is possible to increase the degree of freedom in designing the production process for the entire optical scanning device.

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

[Example 5]
FIG. 14 shows an embodiment of an image reading apparatus to which the present invention is applied.
In FIG. 14, a first traveling body 100 and a second traveling body 101 are disposed below the contact glass 11 on which the document 16 is placed. The 1st traveling body 100 has the illumination lamp 14 and the 1st mirror 12-1, and the illumination lamp 14 and the 1st mirror 12-1 can move integrally. The first mirror 12-1 reflects the reflected light from the document in the horizontal direction. The second traveling body 101 includes a second mirror 12-2 and a third mirror 12-3, and the second and third mirrors 12-2 and 12-3 are movable together. . The second and third mirrors 12-2 and 12-3 are obliquely arranged so that the reflecting surfaces are perpendicular to each other, and the reflected light from the first mirror 12-1 is folded back in the horizontal direction. The reflected light is imaged on the CCD 17 as a photoelectric conversion element by the lens 13. In this way, the image information of the document 16 is extracted from the CCD 17 as an electrical signal.

  The first traveling body 100 and the second traveling body 101 are both movable in the direction of the arrow shown in FIG. 14 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 17 constant, the first traveling body 100 moves at a speed V twice that of the second traveling body 101. 14 indicate the positions of the mirrors 12-1, 12-2, and 12-3 after the document 16 is scanned.

  If the mirror reinforcing method (mirror 1 reinforced by the reinforcing member 2) as shown in the first to third embodiments is applied to the mirrors 12-1, 12-2, 12-3 of such an image reading apparatus. Therefore, it is possible to realize an image reading apparatus that reduces the vibration of the mirror at low cost and does not cause fluctuations in the line of image data that is read as electronic information, which are not found in the original.

[Example 6]
FIG. 15 is a schematic cross-sectional configuration diagram showing an embodiment of an image forming apparatus on which the optical scanning device of Embodiment 4 or the image reading device of Embodiment 5 is mounted.
Four image formations having drum-shaped photoreceptors 601 (corresponding to 414a to 414d in FIG. 13) corresponding to each of four colors of black, cyan, magenta, and yellow are provided in the substantially central portion of the image forming apparatus. A station is provided, and a latent image is written on each photoconductor 601 by the optical scanning device 600 in accordance with image information of a document read by the image reading device 613 or image information sent from a personal computer or the like. It is.
Development is performed around the photoconductor 601 of each image forming station to make the electrostatic latent image recorded by the optical scanning device 600 adhere to the charging charger 602 that charges the photoconductor 601 to a high voltage and to visualize the image. A roller 603, a toner cartridge 604 that supplies toner to the developing roller 603, a cleaning case 605 that scrapes and stores toner remaining on the photosensitive member 601, and the like are disposed.

  The above-described image forming stations are arranged in parallel in the moving direction of the intermediate transfer belt 606, and yellow, magenta, cyan, and black toner images formed on the photoconductor 601 of each image forming station are transferred to a primary transfer unit (primary transfer unit) (not shown). A roller, a primary transfer charger, a primary transfer brush, and the like) are sequentially transferred onto the intermediate transfer belt 606 at appropriate timing, and are superimposed to form a color image. Each image forming station basically has the same configuration except that the toner color is different.

  On the other hand, a transfer material such as recording paper is supplied from a paper feed tray 607 by a paper feed roller 608 and is sent out by a registration roller pair 609 in accordance with the recording start timing in the sub-scanning direction. A color image is transferred from the intermediate transfer belt 606 by a secondary transfer roller, a secondary transfer charger, or the like. Then, the transferred transfer material is sent to the fixing device 610, and the image is fixed on the transfer material by the fixing roller and the pressure roller of the fixing device 610. The transfer material after fixing is discharged to a discharge tray 611 by a discharge roller 612.

  Although an example of the image forming apparatus to which the present invention is applied has been described above, the image forming apparatus to which the present invention is applied is not limited to the color image forming apparatus as shown in FIG. However, in the tandem type image forming apparatus using a plurality of photoconductors 601 as shown in FIG. 15, the optical scanning device 600 is used according to the number of photoconductors 601 as in the embodiments shown in FIGS. Since the number of mirrors increases, 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 for the optical characteristics of the image reading device and the optical scanning device is higher than that of the monochrome image forming device, the application of the present invention that can obtain a higher quality output image at a lower cost is effective. It is.

Note that the popularization layer of the image forming apparatus is an apparatus having a size corresponding to the A4 or A3 paper size. In the image forming apparatuses corresponding to A4 and A3, the length of the paper in the main scanning direction is 210 mm and 297 mm, respectively. Accordingly, the length of the mirror used in these image forming apparatuses is generally 350 mm or less even when an extra length necessary for holding both ends of the mirror is taken into consideration.
On the other hand, a mirror or the like used at a position close to the deflector of the optical scanning device has a short length required for scanning. Here, for example, in the case of a mirror having a length of 150 mm × width of 10 mm, the primary resonance frequency exceeds 322 Hz and 300 Hz without reinforcement even if the thickness is relatively thin as 3 mm, and the displacement at the time of mirror resonance is small even without reinforcement. Therefore, in a general optical scanning apparatus, it is rarely necessary to consider reinforcement for a mirror shorter than 150 mm.

  In addition, in the image forming apparatus of a type corresponding to a paper size larger than A3, the mirror length tends to be longer and countermeasures against vibration of the mirror are more essential, but compared with an image forming apparatus compatible with A4 or A3 size. Although the parts cost has never been cheaper due to the extremely small number of global production, the small cost reduction measures have little merit, and even if a thick mirror is used as a mirror vibration measure, it is not much There is no problem.

It is a figure which shows the 1st Example of this invention, Comprising: It is a figure which shows the structural example of the mirror reinforced with the reinforcement member. It is a figure which shows the effect of the conventional mirror reinforcement member. It is explanatory drawing of the mirror reinforcement method which concerns on this invention, Comprising: The figure (a) is a perspective view of the mirror reinforced with the plate-shaped reinforcement member (reinforcement board) used for vibration simulation, The figure (b) is the figure. It is the figure seen from the arrow A direction in the figure (a). It is a figure which shows the result of having calculated | required the transfer function (vibration characteristic) when a mirror shape is length 260mm and 240mm, width 10x thickness 5mm (without a reinforcement member) by simulation. It is a figure which shows an example of the result of having simulated the reinforcement effect of the mirror which applied the reinforcement method which concerns on this invention. It is a figure which shows another example of the result of having simulated the reinforcement effect of the mirror to which the reinforcement method which concerns on this invention is applied. It is a figure which shows another example of the result of having simulated the reinforcement effect of the mirror to which the reinforcement method which concerns on this invention is applied. It is a figure which shows the 2nd Example of this invention, Comprising: It is explanatory drawing of the support method of the mirror reinforced with the reinforcement member. It is a figure which shows another example of the 2nd Example of this invention, Comprising: It is a figure which shows the example which provided the notch part in the both ends of the longitudinal direction of a reinforcement member. It is a figure which shows the example of the one-sided protrusion which protrudes only to one side which the reinforcement member protrudes equally to both sides with respect to a mirror in the direction perpendicular | vertical to the reflective surface of a mirror. It is a figure which shows another example of a shape of the reinforcement member used for the reinforcement method of this invention. It is a disassembled perspective view which shows one Example of the optical scanning device using the division | segmentation type | mold housing to which this invention is applied. It is a schematic sectional drawing which shows arrangement | positioning of the optical element from the deflector of the optical scanning apparatus shown in FIG. 12 to an image carrier (photosensitive body). It is a schematic sectional drawing which shows one Example of the image reading apparatus to which this invention is applied. 1 is a schematic cross-sectional configuration diagram showing an embodiment of an image forming apparatus to which the present invention is applied.

Explanation of symbols

1,12-1,12-2,12-3,413: Mirror 1a: Reflecting surface 2: Reinforcing member (reinforcing plate)
3: Bonding part 4-1, 4-2, 4-3: Restriction point 5-1, 5-2: Support member 6: Pressing spring 7: Screw 11: Contact glass 13: Lens 14: Illumination lamp 16: Document 17 : CCD (photoelectric conversion element)
401-404: side plate 405: housing 406a-406d: light source unit 407: deflector 408a, 408b: lower cover 409a, 409b: soundproof glass 410: cover 411 (411a-411d): first scanning imaging elements 412a-412d : Second scanning imaging element 414a to 414d, 601: photoconductor (image carrier)
600: optical scanning device 602: charging charger 603: developing roller 604: toner cartridge 605: cleaning case 606: intermediate transfer belt 607: paper feed tray 608: paper feed roller 609: registration roller 610: fixing device 611: paper discharge tray 612 : Paper discharge roller

Claims (9)

A method for reinforcing a mirror having a shape in which a reflecting surface is elongated,
A mirror reinforcing method, wherein a reinforcing member is fixed to a side surface of the mirror with respect to the reflecting surface, and the reinforcing member satisfies the following conditional expression.
0.8 × Lm ≦ Lh
Lm: Length in the longitudinal direction of the mirror (mm)
Lh: Length in the longitudinal direction of the reinforcing member (mm) The mirror reinforcing method according to claim 1,
A mirror reinforcing method, wherein a length Lh in the longitudinal direction of the reinforcing member is shorter than a length Lm in the longitudinal direction of the mirror. The mirror reinforcing method according to claim 1,
A mirror reinforcing method, wherein a notch is provided near an end of the mirror of the reinforcing member. A method for reinforcing a mirror having a shape in which a reflecting surface is elongated,
A mirror reinforcing method comprising: fixing a reinforcing member on a side surface of the mirror with respect to the reflecting surface; and satisfying the following conditional expression in a direction substantially perpendicular to the reflecting surface of the mirror.
Wh ≧ (−1.1 × ln (Th) +2.7) × (Lm / 250) ^ 1.3
× (Tm / 5) ^ 0.2 × (Wm / 10) ^ 0.5 + Tm
Wh: width of the reinforcing member (mm)
ln (Th): natural logarithm of Th Th: thickness of reinforcing member (mm)
Lm: Length in the longitudinal direction of the mirror (mm)
Tm: Thickness (mm) in a direction substantially perpendicular to the reflecting surface of the mirror
Wm: Mirror width (mm) In the mirror reinforcement method according to any one of claims 1 to 4,
A mirror reinforcing method, wherein a material of the base material of the mirror is a glass material, and a material of the reinforcing member is an iron-based sheet metal material. A mirror having a shape in which the reflecting surface is elongated,
A mirror reinforced by the mirror reinforcing method according to any one of claims 1 to 5. In an optical scanning device that deflects light from a light source with a deflector and scans the image surface,
7. An optical scanning device using the mirror according to claim 6 as a mirror disposed in an optical path from the deflector to the image plane. In an image reading apparatus that forms an image of a document on a photoelectric conversion element through a mirror and a lens and reads image information of the document,
An image reading apparatus using the mirror according to claim 6 as the mirror.   An image forming apparatus comprising the optical scanning device according to claim 7 or the image reading device according to claim 8, and forming an image.

Images