Optical scanning apparatus and image forming apparatus

Abstract

To provide an optical scanner and an image formation device having high vibration suppression effect with a simple configuration.SOLUTION: An optical scanner 20 is attached to an image formation device 10 as a unit. The optical scanner 20 is fixed on one end side of a beam emitting direction (longitudinal direction X) of the optical scanner 20 relative to the image formation device 10, and is positioned by one-point locking by a locking part 25 on the other end side of the beam emitting direction. A weight member 28 is provided on the other end side of the optical scanner 20.SELECTED DRAWING: Figure 7A

Description

Technical Field

[0001] The present disclosure relates to an optical scanning device and an image forming apparatus including the same.

Background Art

[0002] In an image forming apparatus such as a multifunction peripheral (hereinafter referred to as a machine), an optical scanning device is used for writing a latent image on an image carrier (photoconductor drum). The optical scanning device has been miniaturized and lightened, and is likely to receive vibrations caused by the drive system in the machine, and banding (image unevenness) generated thereby has become an issue. Conventionally, countermeasures against banding (vibration suppression measures) have been taken by increasing the weight of the optical scanning device (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, with the increase in the speed of machines, the vibrations of the drive unit tend to increase, while the miniaturization and lightening of the optical scanning device have further advanced. In addition, the optical scanning device attached to the machine needs to adjust the inclination of the emitted light beam, and one end of the optical scanning device is only supported (locked) by one boss. The end of the optical scanning device on the side supported by one boss is likely to vibrate in a seesaw shape around this boss and is likely to receive vibrations from the drive unit. Therefore, sufficient suppression of banding may not be achieved only by increasing the weight of the optical scanning device.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide an optical scanning device and an image forming apparatus having a simple configuration and a high vibration suppression effect.

Means for Solving the Problems

[0006] To solve the above problems, the optical scanning apparatus according to the first aspect of the present disclosure is an optical scanning apparatus attached to an image forming apparatus, which is fixed to the image forming apparatus at one end in the direction of light emission of the optical scanning apparatus and positioned at the other end in the direction of light emission by a positioning unit, and is characterized in that a weight member is provided at the other end.

[0007] According to the above configuration, by providing a weight member on the positioning side where vibrations are likely to occur in the optical scanning device, a high vibration suppression effect can be obtained even while using a lightweight weight member. In other words, banding countermeasures can be implemented with a minimum number of parts.

[0008] Furthermore, in the above-mentioned optical scanning device, the weight member can be configured to have approximately the same length as the optical scanning device along the main scanning direction of the optical scanning device.

[0009] Furthermore, in the above-mentioned optical scanning apparatus, the image forming apparatus has a drive unit that drives the image forming unit, and within the image forming apparatus, the drive unit is positioned on one side of the optical scanning apparatus in the main scanning direction, and the weight member can be positioned on the opposite side of the drive unit in the main scanning direction.

[0010] Furthermore, in the above-mentioned optical scanning device, the weight member can be configured to be provided on the light beam emission side from which the light beam is emitted.

[0011] Furthermore, in the above-mentioned optical scanning device, the weight member can be a rectangular parallelepiped-shaped member that is fixed to the housing of the optical scanning device with double-sided tape.

[0012] Furthermore, in the above-described optical scanning device, the weight member can be configured such that, when viewed from the rotation axis direction of the rotating polyhedron mirror, it does not overlap with the rotating polyhedron mirror in the direction of light emission.

[0013] Furthermore, in the above-described optical scanning device, the positioning unit is provided in the center of the main scanning direction of the optical scanning device, and the weight member can be configured to overlap with the positioning unit in the main scanning direction when viewed from the rotation axis direction of the rotating polyhedron mirror.

[0014] Furthermore, in the above-mentioned optical scanning device, the weight member can be configured such that both ends in the main scanning direction of the optical scanning device are bent upward.

[0015] Furthermore, in the above-described optical scanning device, the positioning unit is provided in the center of the main scanning direction of the optical scanning device, and the weight member can be configured to be positioned so as not to overlap with the positioning unit in the main scanning direction when viewed from the rotation axis direction of the rotating polyhedron mirror.

[0016] Furthermore, in order to solve the above-mentioned problems, the image forming apparatus according to the second aspect of this disclosure is characterized by comprising the optical scanning apparatus described above. [Effects of the Invention]

[0017] The optical scanning apparatus and image forming apparatus disclosed herein offer the advantage of efficiently suppressing vibrations transmitted from the drive unit within the machine to the optical scanning apparatus by optimizing the weight distribution of the optical scanning apparatus, thereby enabling banding countermeasures with a minimum number of parts. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic cross-sectional view showing an example configuration of an image forming apparatus to which the optical scanning apparatus of the present disclosure is applied. [Figure 2] This is a schematic plan view showing the internal structure of the optical scanning device. [Figure 3] This diagram shows an optical scanning device and its surroundings, and is a schematic perspective view taken from the right side of the optical scanning device. [Figure 4] This diagram shows the optical scanning device and its surroundings, and is a schematic perspective view taken from the left side of the optical scanning device. [Figure 5]It is a plan view showing an arrangement outline near an optical scanning device in a machine. [Figure 6] It is a schematic front view showing the direction of vibration generated in the optical scanning device. [Figure 7A] It is a schematic plan view showing an arrangement example of a weight member in the optical scanning device of Embodiment 1. [Figure 7B] It is a schematic plan view showing an arrangement example of a weight member in the optical scanning device of Embodiment 1. [Figure 8] It is a graph showing the result of vibration analysis of the vibration generated in the optical scanning device during the operation of the image forming apparatus. [Figure 9A] It is a schematic front view showing an example of the shape of a weight member in the optical scanning device of Embodiment 2. [Figure 9B] It is a schematic front view showing an example of the shape of a weight member in the optical scanning device of Embodiment 2. [Figure 9C] It is a schematic front view showing an example of the shape of a weight member in the optical scanning device of Embodiment 2. [Figure 10] It is a schematic plan view showing an arrangement example of a weight member in the optical scanning device of Embodiment 2. [Figure 11] It is a schematic plan view showing an arrangement example of a weight member in the optical scanning device of Embodiment 3. [Figure 12] It is a graph showing the result of vibration analysis of the vibration generated in the optical scanning device during the operation of the image forming apparatus. [Figure 13A] It is a schematic plan view showing an arrangement example of a weight member in the optical scanning device of Embodiment 3. [Figure 13B] It is a schematic plan view showing an arrangement example of a weight member in the optical scanning device of Embodiment 3.

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, the same reference numerals are given to the same components among the embodiments described below, and redundant descriptions of these components are omitted.

[0020] 〔Embodiment 1〕 -Overall configuration of the image forming apparatus- First, the overall configuration of the image forming apparatus 10 in Embodiment 1 will be described. Figure 1 is a schematic cross-sectional view showing an example of the configuration of the image forming apparatus 10 to which the optical scanning apparatus 20 of this disclosure is applied.

[0021] The image forming apparatus 10 is a multifunction device that has a scanner function, a copying function, a printer function, and a facsimile function, and forms an image on paper from an image of a document read by an image reading device 110 located on top, or from an image received from an external source.

[0022] The image forming apparatus 10 includes, as an image forming unit, a photoreceptor drum (image carrier) 11, a charger 12, a light scanning device 20, a developing device 13, a transfer roller 14, a drum cleaning device 15, and a fixing device 16.

[0023] The charger 12 uniformly charges the surface of the photoreceptor drum 11 to a predetermined potential. The light scanning device 20 emits light to scan the photoreceptor drum 11, which is the object to be scanned, and exposes the surface of the photoreceptor drum 11 to form an electrostatic latent image. The developing device 13 develops the electrostatic latent image on the surface of the photoreceptor drum 11 to form a toner image on the surface of the photoreceptor drum 11. The light scanning device 20 will be described in detail later.

[0024] The transfer roller 14 forms a nip area between itself and the photoreceptor drum 11, and transports the paper that has been transported through the paper transport path by gripping it in the nip area. As the paper passes through this nip area, the toner image on the surface of the photoreceptor drum 11 is transferred to it. The paper with the transferred toner image is then transported through the paper transport path to the fuser unit 16. The fuser unit 16 clamps the paper with the transferred toner image between two rollers (a fuser roller and a pressure roller), heats and pressurizes it, and fixes the toner image to the paper. The drum cleaning device 15 removes and recovers any residual toner from the surface of the photoreceptor drum 11 after the transfer.

[0025] The paper feed cassette 17 is a cassette for storing paper used for image formation. Paper is pulled out from the paper feed cassette 17, transported through the paper transport path, and delivered to the loading tray 18 via the transfer roller 14 and the fixing device 16. The image forming apparatus 10 may also have an inversion transport path and be configured to perform image formation not only on the front surface but also on the back surface of the paper. Furthermore, the image forming apparatus 10 may be provided with a manual feed tray 19 into which paper can be loaded by opening it from the side.

[0026] In this embodiment, the toner image is directly transferred from the photoconductor drum 11 to the paper P. However, the invention is not limited to this configuration, and a belt transfer method may be used in which the toner image is transferred from the photoconductor drum to an intermediate transfer belt, and then from the intermediate transfer belt to the paper P.

[0027] Figure 2 is a schematic plan view showing the internal structure of the optical scanning device 20. Figure 3 is a diagram showing the optical scanning device 20 and its surroundings, and is a schematic perspective view taken from the right side of the optical scanning device 20. Figure 4 is a diagram showing the optical scanning device 20 and its surroundings, and is a schematic perspective view taken from the left side of the optical scanning device 20. Here, for the sake of explanation, the direction of arrow X in the figures is the left-right direction, the direction of arrow Y is the front-back direction, and the direction of arrow Z is the up-down direction. However, these directions are used for the sake of explanation and do not limit the content of this disclosure. In this embodiment, the front-back direction Y coincides with the main scanning direction of the optical scanning device 20, and the up-down direction Z coincides with the sub-scanning direction of the optical scanning device 20. The left-right direction X is a direction orthogonal to both the main scanning direction and the sub-scanning direction, and coincides with the light ray emission direction of the optical scanning device 20.

[0028] As shown in Figure 2, the optical scanning device 20 has a housing 21 that is roughly rectangular when viewed from above, and various optical components are housed inside the housing 21. The optical scanning device 20 has the right side of the housing 21 as the light emission surface, and scans light emitted from the emission window 21a provided on the right side.

[0029] The optical scanning device 20 includes, as optical components, a light source 221 (laser diode element), a collimator lens 222, an aperture member 223, a cylindrical lens 224, a light source reflective mirror 225, a light deflection unit 23, an fθ lens 226, a beam detection reflective mirror 227, a beam detection lens 228 (focusing lens), and a beam detection unit 229 (Beam Detect sensor (BD sensor)). The illustrated optical scanning device 20 has a reduced number of lenses used, resulting in further miniaturization and weight reduction.

[0030] The light source 221 emits a light beam (laser beam). The collimator lens 222 directs the light beam from the light source 221 into approximately parallel light and irradiates the aperture member 223. The aperture member 223 focuses the incident light beam and irradiates the cylindrical lens 224. The cylindrical lens 224 focuses the incident light beam and irradiates the light source reflective mirror 225. The light source reflective mirror 225 reflects the light beam and focuses it onto the rotating polyhedron mirror 231 of the light deflection unit 23.

[0031] In the optical deflection unit 23, the rotating polyhedron mirror 231 is rotated to deflect and scan the incident light beam in the front-to-back direction Y. The light beam deflected and scanned in the optical deflection unit 23 is guided to the fθ lens 226, which has an elongated shape in the front-to-back direction Y, and the beam detection reflective mirror 227.

[0032] The light beam incident on the fθ lens 226 is emitted to the outside of the optical scanning device 20 through the exit window 21a. The light beam incident on the beam detection reflection mirror 227 is reflected and incident on the beam detection lens 228. The beam detection lens 228 focuses the light beam onto the beam detection unit 229. The beam detection unit 229 is provided on a detection substrate 24 attached to the optical scanning device 20 and outputs a beam detection signal indicating the timing before the start of the main scan.

[0033] Furthermore, the detection board 24 may be connected to a light source 221, and a circuit for driving the light source 221 may be provided. Also, the housing 21 of the optical scanning device 20 may be provided with an opening through which the light beam directed toward the beam detection unit 229 passes. In addition, the optical components housed in the optical scanning device 20 are not limited to those described above and may be changed or added as appropriate depending on the application. The light source 221 may be mounted on a substrate or the like, and the emission part of the light source 221 may be inserted into a hole provided on one side of the optical scanning device 20. In addition, although the optical scanning device 20 is sealed to prevent the intrusion of dust, a part of the components (for example, the rotation axis of the rotating polyhedron mirror 231) may be exposed while the gaps are sealed.

[0034] As shown in Figures 3 and 4, the optical scanning device 20 described above is attached to the support 30 inside the image forming apparatus 10. The optical scanning device 20 has a boss-shaped locking portion (positioning portion) 25 protruding from the right side of the housing 21 and a support shaft 26 protruding from the left side.

[0035] The locking portion 25 is locked into a locking hole in the first rib 31, which is erected on the upper surface of the support 30, and positions the right end of the optical scanning device 20. However, since the locking portion 25 is only inserted into the locking hole of the first rib 31, the right end of the optical scanning device 20 is rotatable around the locking portion 25.

[0036] The support shaft 26 is attached to the support body 30 via a shaft support member 40 and a positioning member 41. The locking portion 25 and the support shaft 26 are located approximately in the center of the optical scanning device 20 in the front-rear direction Y. In this specification, "approximately in the center" is a concept that includes not only the exact center in a given direction, but also a predetermined range from the center (for example, an area shifted approximately 10% from the center of the total width in a given direction). A control board 29 may be mounted on the upper surface of the optical scanning device 20.

[0037] The optical scanning device 20 has adjustment holes 271 and 272 at both ends in the front-rear direction Y on its left side. The adjustment holes 271 and 272 allow for positioning and fixing (fastening) by fastening with screws (fastening members) to the screw holes of the second ribs 321 and 322 erected on the upper surface of the support 30.

[0038] In the image forming apparatus 10, if there is a misalignment of light from the optical scanning device 20 relative to the photoreceptor drum 11, the optical scanning may be disrupted and the image quality may deteriorate. For this reason, it is necessary to adjust the orientation of the optical scanning device 20 to reduce the misalignment of light from the optical scanning device 20. The optical scanning device 20 has an oscillation axis δ (see Figure 2) passing through the locking part 25 and the support shaft 26, and the orientation of the optical scanning device 20 is determined by the direction of the oscillation axis δ and the inclination around the oscillation axis δ with respect to its positional relationship with the surface of the photoreceptor drum 11, which is the surface to be scanned.

[0039] In the optical scanning device 20 attached to the support 30, the position of the locking portion 25 is positioned by the first rib 31, and the direction of the oscillation axis δ is determined by the position of the support shaft 26. The position of the support shaft 26 can be adjusted using the shaft support member 40 and the positioning member 41. The method for adjusting the position of the support shaft 26 is described in the applicant's prior application (Japanese Patent Application No. 2022-45699: not published at the time of this application), and since it is not an important feature in this disclosure, a detailed explanation is omitted here.

[0040] The tilt of the optical scanning device 20 around the oscillation axis δ can be adjusted by positioning the adjustment holes 271 and 272 relative to the second ribs 321 and 322. The method for adjusting the tilt around the oscillation axis δ is also described in the aforementioned prior application and is not a feature important to this disclosure; therefore, a detailed explanation is omitted here.

[0041] After posture adjustment, the optical scanning device 20 is fixed to the second ribs 321 and 322 near both ends in the front-rear direction Y on the left side in the left-right direction X (unit fixed side: opposite to the light emission side). Therefore, vibration of the optical scanning device 20 is less likely to occur on the left side in the left-right direction X. Furthermore, within the optical scanning device 20, the relatively heavy light deflection unit 23, which includes the drive motor for the rotating polyhedron mirror 231, is positioned to the left of the center in the left-right direction X to ensure distance from the light emission surface (at least the drive motor for the rotating polyhedron mirror 231 is positioned to the left of the center). This also makes vibration of the optical scanning device 20 less likely to occur on the left side in the left-right direction X.

[0042] On the other hand, on the right side (light emission side) in the left-right direction X, the optical scanning device 20 is only locked at one point by the locking part 25. Furthermore, within the optical scanning device 20, no heavy components are placed on the right side, which is the light emission side. Therefore, without measures to suppress vibration (banding countermeasures), the optical scanning device 20 is prone to vibration (seesaw-like vibration around the locking part 25) on the right side in the left-right direction X. In particular, with optical scanning devices 20 that have been further miniaturized and lightened, it is difficult to sufficiently suppress this vibration with conventional banding countermeasures.

[0043] In the optical scanning device 20 according to this embodiment 1, a weight member 28 is placed on the upper surface of the housing 21 as a measure against banding. The method of fixing the weight member 28 to the housing 21 is not particularly limited, and methods such as attachment with double-sided tape or screw fastening can be used. In the optical scanning device 20, a high banding suppression effect is obtained with a simple configuration by devising the shape and placement of the weight member 28. As a result, banding can be effectively suppressed even in high-speed machines where vibrations of the drive unit become large, and in optical scanning devices 20 that have been further miniaturized and lightened.

[0044] Figure 5 is a plan view showing the general layout around the optical scanning device 20 within the machine. Note that the front and rear sides shown in Figure 5 correspond to the front and rear sides of the image forming apparatus 10. Within the machine, the drive system is typically located at the rear of the optical scanning device 20. This drive system includes a drive unit that drives the image forming section within the machine (such as the photoreceptor drum 11 and the developing rollers in the developing apparatus 13). Furthermore, in the arrangement of the optical scanning device 20 within the machine, the oscillation axis δ is perpendicular to the front-to-back direction of the machine, making it easy for vibrations transmitted from the drive system to the optical scanning device 20 to cause seesaw-like vibrations around the oscillation axis δ (see Figure 6). As mentioned above, these vibrations are particularly likely to occur on the light-emitting side of the optical scanning device 20.

[0045] Figures 7A and 7B are schematic diagrams showing an example of the arrangement of the weight member 28 in the optical scanning device 20 of this embodiment 1. As shown in Figures 7A and 7B, the weight member 28 has an elongated shape with the front-to-back direction Y of the optical scanning device 20 as its longitudinal direction, and is positioned to the right (light emission side) of the center (center line L1 shown in the figure) of the center in the left-to-right direction X of the optical scanning device 20. Thus, the weight member 28 positioned to the right in the left-to-right direction X is positioned so as not to overlap with the rotating polyhedron mirror 231 positioned to the left when viewed from the rotation axis direction (up-down direction Z) of the rotating polyhedron mirror 231. That is, the weight member 28 is positioned so as not to overlap with the rotating polyhedron mirror 231 in the left-to-right direction X when viewed from the up-to-down direction Z. Also, the weight member 28 is positioned so as to overlap with the locking part 25 in the front-to-back direction Y when viewed from the up-to-down direction Z. Note that the majority of the weight of the optical scanning device 20 is obtained from the housing 21 and its internal components. Therefore, the aforementioned center line L1 may be set not as the overall dimension of the optical scanning device 20 (including the locking portion 25 and the support shaft 26), but as the center line relative to the dimensions of the housing 21.

[0046] Such an elongated weight member 28 is relatively lightweight, yet it can effectively increase the moment of inertia of the optical scanning device 20 (more specifically, the moment of inertia about an axis perpendicular to the longitudinal direction of the weight member 28). By arranging the weight member 28 so that its longitudinal direction coincides with the front-to-back direction Y, vibrations around the oscillation axis δ can be effectively suppressed. Furthermore, by positioning the weight member 28 off-center towards the light emission side from the center in the left-to-right direction X, vibrations on the light emission side can be effectively suppressed. The closer the weight member 28 is positioned to the end on the light emission side, the greater its effect in suppressing vibrations on the light emission side. In other words, the configuration in Figure 7A has a higher vibration suppression effect than the configuration in Figure 7B. Also, the larger the longitudinal dimension of the weight member 28, the greater the moment of inertia of the optical scanning device 20. Therefore, it is preferable that the weight member 28 has approximately the same length as the optical scanning device 20 along the front-to-back direction Y of the optical scanning device 20. In this context, "approximately the same length" means that the longitudinal dimension of the weight member 28 is 97% or more of the front-to-back dimension of the optical scanning device 20, or that the difference between the longitudinal dimension of the weight member 28 and the front-to-back dimension of the optical scanning device 20 is within 5 mm. For example, in the optical scanning device 20 of this example, the front-to-back dimension Y of the optical scanning device 20 is 167 mm, and the front-to-back dimension Y of the weight member 28 is 162 mm, so the longitudinal dimension of the weight member 28 and the front-to-back dimension of the optical scanning device 20 are considered to be approximately the same length.

[0047] Figure 8 is a graph showing the results of a vibration analysis of vibrations generated in the optical scanning device 20 during the operation of the image forming apparatus 10. The vertical axis of Figure 8 shows the peak value of the power spectrum (waveform) obtained by the vibration analysis, and a smaller value indicates smaller vibration. On the horizontal axis, [Default] shows the case where no weight member 28 is used and no banding countermeasures are taken for the optical scanning device 20. [Overall Increase] shows the case where no weight member 28 is used, but the weight of the top plate of the housing 21 of the optical scanning device 20 is increased (for example, by increasing the number of top plates), thereby increasing the weight of the entire optical scanning device 20 in a plan view (conventional banding countermeasure). And [Light Ray Emission Side] shows the case where the weight member 28 is placed on the light ray emission side of the optical scanning device 20, as shown in Figure 7 (banding countermeasure of this disclosure).

[0048] As is clear from Figure 8, in the optical scanning device 20 with the elongated weight member 28 placed on the [light emission side], a higher vibration suppression effect is obtained than with conventional banding countermeasures ([overall increase]). In this analysis, while the weight of the optical scanning device 20 without the weight member 28 is approximately 550g, a sufficient vibration suppression effect was obtained by using a weight member 28 weighing 180-200g.

[0049] [Embodiment 2] The weight member 28 has an elongated shape with the front-to-back direction Y as its longitudinal direction. In this case, the weight member 28 may be a roughly rectangular parallelepiped shape such that each cross section in the longitudinal direction is the same, or it may be a shape in which the cross section in the longitudinal direction differs depending on the position in the front-to-back direction Y. When the weight member 28 has a shape in which the cross section in the longitudinal direction differs depending on the position in the front-to-back direction Y, it is preferable that it be heavier near the ends than in the center in the front-to-back direction Y.

[0050] As a specific example, as shown in Figure 9A, the weight of the weight member 28 can be increased near the ends by making the thickness of the ends greater than that of the central part. Alternatively, as shown in Figures 9B and 9C, the weight member 28 can be made from sheet metal, and its ends can be bent upward (and further inward in Figure 9C) to increase the weight of the weight member 28 near the ends. The weight member 28 in Figures 9B and 9C can be made with a weight member 28 that is heavier at the ends by a simple method such as bending sheet metal. Furthermore, the weight member 28 in Figure 9C can increase the weight at the ends while keeping the height of the weight member 28 lower compared to the weight member 28 in Figure 9B.

[0051] In this way, the weight member 28, which is heavier at the ends than in the longitudinal center, can effectively increase the moment of inertia of the optical scanning device 20 while keeping the weight of the weight member 28 down. As a result, an effective vibration suppression effect can be obtained for the optical scanning device 20 while suppressing the cost (especially material costs) of the weight member 28.

[0052] Alternatively, as shown in Figure 10, two weight members 28 may be used, and these two weight members 28 may be positioned near both ends in the front-rear direction Y relative to the optical scanning device 20. Even with the configuration in Figure 10, the moment of inertia of the optical scanning device 20 can be effectively increased while keeping the weight of the weight members 28 down, and an effective vibration suppression effect can be obtained while suppressing the cost of the weight members 28.

[0053] Furthermore, when the two weight members 28 are positioned near both ends in the front-to-back direction Y relative to the optical scanning device 20, the longitudinal direction of these weight members 28 does not necessarily have to be the front-to-back direction Y of the optical scanning device 20. In this case, for example, the left-to-right direction X can be the longitudinal direction of the weight members 28.

[0054] [Embodiment 3] The weight member 28 is positioned biased toward the light emission side in the left-right direction X of the optical scanning device 20, but it may also be biased toward the front-rear direction Y. In this case, as shown in Figure 11, it is preferable that the weight member 28 is positioned on the front side (away from the drive system inside the machine: see Figure 5) of the center (center line L2 shown) in the front-rear direction Y of the optical scanning device 20. In this case, as shown in Figure 11, it is preferable that the entire weight member 28 is positioned on the front side of the center line L2. In other words, it is preferable that the weight member 28 is positioned so that it does not overlap with the locking portion 25 in the front-rear direction Y when viewed from the up-down direction Z. However, this disclosure is not limited thereto, and a part of the weight member 28 may be on the rear side of the center line L2, and at least the center of gravity of the weight member 28 should be on the front side of the center line L2.

[0055] Figure 12 is a graph showing the results of a vibration analysis of vibrations generated in the optical scanning device 20 during the operation of the image forming apparatus 10. The values ​​for [Default] and [Overall Increase] on the horizontal axis of Figure 12 are the same as in Figure 8. Furthermore, the values ​​for [R Position Centroid], [C Position Centroid], and [F Position Centroid] on the horizontal axis of Figure 12 represent the cases where the center of gravity of the weight member 28 is positioned at the rear, center, and front, respectively, in the front-to-back direction Y. In the vibration analysis of Figure 12, the length and weight of the weight member 28 in the front-to-back direction Y are approximately 1 / 3 of those in the vibration analysis of Figure 8. Additionally, in the [R Position Centroid] and [F Position Centroid], the weight member 28 is positioned as close as possible to the end of the optical scanning device 20 in the front-to-back direction Y. Furthermore, in the left-to-right direction X, the weight member 28 is positioned as close as possible to the end of the optical scanning device 20 on the light-emitting side.

[0056] In the results shown in Figure 12, comparing the results for [Overall Increase] and [Center of C], it can be seen that the power spectrum remains almost unchanged, indicating that the vibration suppression effect has not improved compared to the conventional method. This is thought to be because, in the case of [Center of C], the length of the weight member 28 itself is short and it is positioned near the center of vibration of the optical scanning device 20, so the weight member 28 cannot effectively increase the moment of inertia of the optical scanning device 20.

[0057] Furthermore, comparing the results for [C position centroid], [R position centroid], and [F position centroid], it can be seen that the power spectrum is significantly smaller for [R position centroid] and [F position centroid] compared to [C position centroid], indicating an improved vibration suppression effect. This is thought to be because even if the length of the weight member 28 itself is shortened, by positioning it far from the center of vibration of the optical scanning device 20, the weight member 28 can effectively increase the moment of inertia of the optical scanning device 20.

[0058] Furthermore, comparing the results for [R position centroid] and [F position centroid], it can be seen that the power spectrum is significantly smaller at [F position centroid] compared to [R position centroid], indicating a further improvement in vibration suppression effect. The vibration transmitted from the vibration system to the optical scanning device 20, that is, the rotational moment transmitted from the vibration system to the optical scanning device 20, becomes larger the further away from the vibration system. For this reason, when the weight member 28 is positioned off-center in the front-rear direction Y, it is thought that placing the weight member 28 on the side away from the drive system in the machine will increase the effect of suppressing the rotational moment transmitted from the vibration system.

[0059] Figures 13A and 13B show modified examples of the optical scanning device 20 of this embodiment 3. As shown in Figures 13A and 13B, the length of the weight member 28 in the front-rear direction Y is not particularly limited and can be made significantly shorter. Even if the length of the weight member 28 in the front-rear direction Y is shortened, the moment of inertia of the optical scanning device 20 can be increased and the vibration suppression effect improved by increasing the weight of the weight member 28, for example by increasing its thickness (length in the vertical direction Z).

[0060] Furthermore, in this third embodiment as well, the weight member 28 only needs to be positioned on the light emission side of the center line L1 of the optical scanning device 20. However, in this case as well, the closer the weight member 28 is positioned to the end on the light emission side, the greater the effect of suppressing vibration on the light emission side, as in the first embodiment (that is, the configuration in Figure 13A has a higher vibration suppression effect than the configuration in Figure 13B).

[0061] Furthermore, when the weight member 28 is positioned off-center in the front-to-back direction Y relative to the optical scanning device 20, the weight member 28 does not necessarily have to have the front-to-back direction Y of the optical scanning device 20 as its longitudinal direction. In this case, for example, the left-to-right direction X can be the longitudinal direction of the weight member 28.

[0062] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of this disclosure is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims. [Explanation of Symbols]

[0063] 10 Image forming apparatus 20 Optical scanning device 21 cabinets 21a Ejection window 23 Light deflection section 231 Rotating polyhedron 25 Locking part (positioning part) 26 Spindle 271,272 adjustment hole 28 Weight member 30 Support 31. First Rib 321,322 Second Rib 40 Axle support member 41 Positioning member δ oscillation axis

Claims

1. An optical scanning device attached to an image forming apparatus, Light source and The light source is equipped with a rotating polyface mirror that deflects the light beam emitted from the light source to form scanning light, The direction in which the scanning light emitted from the optical scanning device is perpendicular to the rotation axis direction of the rotating polyhedron mirror, With respect to the image forming apparatus, it is fixed at one end in the direction of light emission and positioned at the other end in the direction of light emission by a positioning unit. The positioning portion has a locking portion that locks the other end at a single point, and is rotatable around the locking portion. An optical scanning device characterized in that a weight member is provided on the other end.

2. An optical scanning apparatus according to claim 1, The aforementioned weight member is characterized in that it has substantially the same length as the optical scanning device along the main scanning direction of the optical scanning device.

3. An optical scanning apparatus according to claim 1, The image forming apparatus has a drive unit that drives the image forming unit, Within the image forming apparatus, the drive unit is positioned on one side of the main scanning direction relative to the optical scanning device. The optical scanning apparatus is characterized in that the weight member is arranged on the opposite side from the drive unit in the main scanning direction.

4. An optical scanning apparatus according to any one of claims 1 to 3, The optical scanning device is characterized in that the weight member is provided on the light beam emission side from which light beams are emitted.

5. An optical scanning apparatus according to any one of claims 1 to 3, The aforementioned weight member is a rectangular parallelepiped-shaped member, and is fixed to the housing of the optical scanning device with double-sided tape, characterized in that it is an optical scanning device.

6. An optical scanning apparatus according to any one of claims 1 to 3, The optical scanning device is characterized in that the weight member is positioned so as to not overlap with the rotating polyhedron mirror in the direction of light emission when viewed from the rotation axis direction of the rotating polyhedron mirror.

7. An optical scanning apparatus according to any one of claims 1 to 3, The positioning unit is provided in the center of the main scanning direction of the optical scanning device, The optical scanning device is characterized in that the weight member is arranged to overlap with the positioning unit in the main scanning direction when viewed from the rotation axis direction of the rotating polyhedron mirror.

8. An optical scanning apparatus according to any one of claims 1 to 3, The aforementioned weight member is characterized in that both ends in the main scanning direction of the optical scanning device are bent upward.

9. The optical scanning apparatus according to claim 3, The positioning unit is provided in the center of the main scanning direction of the optical scanning device, The optical scanning device is characterized in that the weight member is positioned so as to not overlap with the positioning unit in the main scanning direction when viewed from the axis of rotation of the rotating polyhedron mirror.

10. An image forming apparatus characterized by comprising an optical scanning device according to any one of claims 1 to 3.

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