Optical scanning device and image forming apparatus

Abstract

The invention discloses an optical scanning device and an image forming apparatus. There is provided a light scanning apparatus including: a deflection unit configured to deflect a light beam from a first light source to scan a first scanned surface in a main scanning direction; a first imaging optical system and a reflective element configured to guide the first light beam deflected by the deflection unit to the first scanned surface; an optical element configured to guide the first light beam emitted from the first light source to the deflection unit; and a holding member configured to hold the deflection unit, the first imaging optical system, the reflective element, and the optical element, in which the optical element and the reflective element are adjacent to the holding member.

Description

Technical Field

[0001] The present disclosure relates to a light scanning device, and more particularly, to a light scanning device suitable for an image forming device such as a laser beam printer, a digital copier, or a multifunction printer. Background Art

[0002] There has hitherto been known an optical scanning device including a plurality of holding units each of which holds one optical element among a plurality of optical elements.

[0003] In Japanese Patent Application Laid-Open No. 2016-133777, there is disclosed an optical scanning device in which a reflection mirror for bending an optical path of a light beam deflected by a deflection unit is held by a holding unit formed integrally with a housing.

[0004] On the other hand, a collimator lens for converting a light beam emitted from the light source into a parallel light beam is held by a light source unit for holding the light source. The light source unit is fixed to the housing by a fixing screw. Summary of the invention

[0005] According to an embodiment, a light scanning device is provided, which includes: a deflection unit, which is configured to deflect a light beam from a first light source to scan a first scanned surface in a main scanning direction; a first imaging optical system and a reflecting element, which are configured to guide the first light beam deflected by the deflection unit to the first scanned surface; an optical element, which is configured to guide the first light beam emitted from the first light source to the deflection unit; and a holding member, which is configured to hold the deflection unit, the first imaging optical system, the reflecting element, and the optical element, wherein the optical element and the reflecting element are adjacent to the holding member.

[0006] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A 1 is a development view in the main scanning section of the optical scanning device according to the first embodiment of the present invention.

[0008] Figure 1B is a partial sub-scanning cross-sectional view of the optical scanning device according to the first embodiment.

[0009] Figure 2 is a sub-scanning cross-sectional view of a first imaging optical element included in the light scanning device according to the first embodiment.

[0010] Figure 31 is a partial projection diagram in the main scanning section of the optical scanning device according to the first embodiment.

[0011] Figure 4A is a front view of a first incident optical element included in the light scanning device according to the first embodiment.

[0012] Figure 4B is a side view of a first incident optical element included in the light scanning device according to the first embodiment.

[0013] Figure 5A 1 is a diagram of the light scanning device according to the first embodiment, viewed from the optical axis direction, in the vicinity of the first incident optical element.

[0014] Figure 5B 1 is a view of the light scanning device according to the first embodiment viewed from the main scanning direction in the vicinity of the first incident optical element.

[0015] Figure 5C 1 is a diagram of the light scanning device according to the first embodiment viewed from the sub-scanning direction in the vicinity of the first incident optical element.

[0016] Fig. 6A : is a graph for illustrating the image height correlation of the LSF depth center position in the main scanning direction on each scanned surface in the light scanning device according to the first embodiment.

[0017] Figure 6B : is a graph for illustrating the image height correlation of the LSF depth center position in the sub scanning direction on each scanned surface in the light scanning device according to the first embodiment.

[0018] Figure 7 1 is a partial projection diagram in the main scanning section of the optical scanning device according to the first embodiment.

[0019] Fig. 8A 1 is a development view in the main scanning section of an optical scanning device according to a second embodiment of the present invention.

[0020] Figure 8B is a partial sub-scanning cross-sectional view of the optical scanning device according to the second embodiment.

[0021] Fig. 9 1 is a partial projection diagram in the main scanning section of the optical scanning device according to the second embodiment.

[0022] Fig. 10A : is a graph for illustrating the image height correlation of the LSF depth center position in the main scanning direction on each scanned surface in the light scanning device according to the second embodiment.

[0023] Fig. 10B: is a graph for illustrating the image height correlation of the LSF depth center position in the sub-scanning direction on each scanned surface in the light scanning device according to the second embodiment.

[0024] Fig.11A 1 is a development view in the main scanning section of an optical scanning device according to a third embodiment of the present invention.

[0025] Fig. 11B is a partial sub-scanning cross-sectional view of the optical scanning device according to the third embodiment.

[0026] Fig.12 1 is a partial projection diagram in the main scanning section of the optical scanning device according to the third embodiment.

[0027] Fig.13A : is a graph for illustrating the image height correlation of the LSF depth center position in the main scanning direction on each scanned surface in the light scanning device according to the third embodiment.

[0028] Fig. 13B : is a graph for illustrating the image height correlation of the LSF depth center position in the sub-scanning direction on each scanned surface in the light scanning device according to the third embodiment.

[0029] Fig.14 is a sub-scanning cross-sectional view of a main portion of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, the optical scanning device according to the present embodiment will be described in detail with reference to the accompanying drawings. In order to make the present disclosure more easily understood, some of the drawings to be referred to below may be drawn in a scale different from the actual scale.

[0031] In the following description, the main scanning direction refers to a direction perpendicular to the rotation axis of the deflection unit 50 and the optical axes of the first to fourth imaging optical systems (a direction in which light beams are deflected by the deflection unit 50 ).

[0032] The sub-scanning direction is a direction parallel to the rotation axis of the deflection unit 50. The main-scanning section is a section perpendicular to the sub-scanning direction. The sub-scanning section is a section perpendicular to the main-scanning direction.

[0033] Hereinafter, the optical axis directions of the first to fourth imaging optical systems, the main scanning direction, and the sub-scanning direction are defined as an X direction, a Y direction, and a Z direction, respectively.

[0034] The X direction may also be defined as a direction (first direction) parallel to a straight line passing through a first intersection between the first scanned surface 100a and the optical axis of the first imaging optical system and a second intersection between the second scanned surface 100b and the optical axis of the second imaging optical system.

[0035] [First embodiment]

[0036] Figure 1A and Figure 1B An expanded view in a main scanning section and a partial sub-scanning cross-sectional view of the optical scanning device 1 according to the first embodiment of the present invention are respectively shown.

[0037] exist Figure 1A , first reflecting elements (reflecting optical elements) 70a, 70b, 70c and 70d and second reflecting elements (reflecting optical elements) 90a and 90b are indicated by dotted lines.

[0038] The optical scanning device 1 according to the present embodiment includes a housing 2 (holding member) and first, second, third and fourth light sources 10a, 10b, 10c, and 10d as well as first and second incident optical elements 20a and 20b (refractive optical elements).

[0039] The optical scanning device 1 according to the present embodiment further includes first and second sub-scanning diaphragms 30 a and 30 b , first and second main-scanning diaphragms 40 a and 40 b , and a deflection unit 50 .

[0040] The optical scanning device 1 according to the present embodiment further includes first imaging optical elements 60a and 60b, first reflecting elements 70a to 70d, second imaging optical elements 80a, 80b, 80c and 80d, and second reflecting elements 90a and 90b.

[0041] The housing 2 is configured to hold and simultaneously accommodate the optical elements provided in the light scanning device 1 according to the present embodiment.

[0042] Each of the first to fourth light sources 10a to 10d is a light source such as a semiconductor laser having two light emitting points. That is, the light scanning device 1 according to the present embodiment is provided with eight light emitting points in total.

[0043] The first light source 10 a and the second light source 10 b are arranged in the same position in the main scanning section, and are arranged in positions different from each other in the sub scanning direction.

[0044] The third light source 10 c and the fourth light source 10 d are arranged in the same position in the main scanning section, and are arranged in positions different from each other in the sub scanning direction.

[0045] The first incident optical element 20a and the second incident optical element 20b are formed of anamorphic lenses having different magnitudes of refractive power in the main-scan section and the sub-scan section.

[0046] The first incident optical element 20a converts the convergence of the first light beam LA and the second light beam LB emitted from the first light source 10a and the second light source 10b, respectively, so that the first light beam LA and the second light beam LB become parallel light beams in the main scanning direction.

[0047] Similarly, the second incident optical element 20b converts the convergence of the third light beam LC and the fourth light beam LD emitted from the third light source 10c and the fourth light source 10d, respectively, so that the third light beam LC and the fourth light beam LD become parallel light beams in the main scanning direction.

[0048] It is assumed here that the parallel light beam includes not only a strictly parallel light beam, but also a substantially parallel light beam including a weakly divergent light beam and a weakly convergent light beam.

[0049] The first incident optical element 20 a converges the first light beam LA and the second light beam LB emitted from the first light source 10 a and the second light source 10 b , respectively, toward the deflection unit 50 in the sub-scanning direction.

[0050] Similarly, the second incident optical element 20 b converges the third light beam LC and the fourth light beam LD emitted from the third light source 10 c and the fourth light source 10 d , respectively, toward the deflection unit 50 in the sub-scanning direction.

[0051] The detailed configurations of the first incident optical element 20a and the second incident optical element 20b are described later.

[0052] The first sub-scanning aperture 30a includes a lower opening portion 30al (first opening portion) and an upper opening portion 30au (second opening portion) having a quadrilateral shape to adjust the beam widths of the first light beam LA and the second light beam LB having traveled through the first incident optical element 20a in the sub-scanning direction.

[0053] Similarly, the second sub-scanning aperture 30b includes two opening portions having a quadrangular shape to adjust the beam widths of the third light beam LC and the fourth light beam LD having traveled through the second incident optical element 20b in the sub-scanning direction.

[0054] The first main scanning aperture 40a includes a single opening portion having a quadrangular shape to adjust the beam widths of the first light beam LA and the second light beam LB having traveled through the first sub scanning aperture 30a in the main scanning direction.

[0055] Similarly, the second main scanning aperture 40b includes a single opening portion having a quadrangular shape to adjust the beam widths of the third light beam LC and the fourth light beam LD having traveled through the second sub scanning aperture 30b in the main scanning direction.

[0056] The deflection unit 50 is a polygon mirror (rotating polygon mirror) having four deflection surfaces, and is driven by a driving unit (not shown) such as a motor to Figure 1A The device rotates at a constant speed in the direction of the arrow R indicated in the figure.

[0057] The first imaging optical elements 60 a and 60 b and the second imaging optical elements 80 a to 80 d are fθ lenses (scanning lenses) having fθ characteristics.

[0058] The first imaging optical element 60a and the second imaging optical element 80a converge (guide) the first light beam LA deflected by the deflection unit 50 to a scanning area (image forming area) of the first scanned surface 100a, thereby forming a light spot image on the scanning area.

[0059] The first imaging optical element 60a and the second imaging optical element 80b converge (guide) the second light beam LB deflected by the deflection unit 50 to a scanning area of ​​the second scanned surface 100b, thereby forming a light spot image on the scanning area.

[0060] The first imaging optical element 60b and the second imaging optical element 80c converge (guide) the third light beam LC deflected by the deflection unit 50 to a scanning area of ​​the third scanned surface 100c, thereby forming a light spot image on the scanning area.

[0061] The first imaging optical element 60b and the second imaging optical element 80d converge (guide) the fourth light beam LD deflected by the deflection unit 50 to the scanning area of ​​the fourth scanned surface 100d, thereby forming a light spot image on the scanning area.

[0062] The first reflecting elements 70a to 70d and the second reflecting elements 90a and 90b are long mirrors having no refractive power that bend the optical paths of the first to fourth light beams LA to LD deflected by the deflection unit 50 in the sub-scan section.

[0063] The first incident optical element 20 a and the second incident optical element 20 b provided in the light scanning device 1 according to the present embodiment are molded lenses formed by injection molding of a plastic material (resin material).

[0064] Similarly, the first imaging optical elements 60 a and 60 b and the second imaging optical elements 80 a to 80 d are molded lenses formed by injection molding of a plastic material (resin material).

[0065] However, these elements are not limited thereto and may be molded lenses formed by injection molding of a glass material.

[0066] In the optical scanning device 1 according to the present embodiment, the use of a molded lens that is easily formed with an optical surface having an aspherical shape and is suitable for mass production can improve productivity and optical performance.

[0067] The first reflecting elements 70a to 70d and the second reflecting elements 90a and 90b provided in the optical scanning device 1 according to the present embodiment are long reflecting mirrors formed by forming a film as a reflecting surface on a common long glass sheet, but are not limited thereto.

[0068] That is, the first reflecting element and the second reflecting element may be long reflecting mirrors created by forming a film as a reflecting surface on a member formed by injection molding of a plastic material, or by performing mirror-like finishing on a metal member such as an aluminum member.

[0069] In the light scanning device 1 according to the present embodiment, the reflection surfaces they possess are formed to have a flat shape with no refractive power, but are not limited thereto and may be formed to have a spherical or other curved surface shape.

[0070] The first light beam LA and the second light beam LB emitted from the first light source 10a and the second light source 10b, respectively, are converted into parallel light beams in the main scanning section by the first incident optical element 20a, and are also converged in the sub-scanning section.

[0071] After traveling through the first incident optical element 20 a , the first light beam LA and the second light beam LB travel through the first sub-scanning diaphragm 30 a and the first main-scanning diaphragm 40 a , and are then guided to the first deflecting surface 50 a of the deflecting unit 50 .

[0072] Therefore, the beam widths of the first and second light beams LA and LB are adjusted in the main scanning direction and the sub scanning direction and converge in the sub scanning direction so that a long line image is formed in the main scanning direction near the first deflecting surface 50 a of the deflecting unit 50 .

[0073] The third light beam LC and the fourth light beam LD emitted from the third light source 10c and the fourth light source 10d, respectively, are converted into parallel light beams in the main scanning section by the second incident optical element 20b, and are also converged in the sub-scanning section.

[0074] After traveling through the second incident optical element 20 b , the third light beam LC and the fourth light beam LD travel through the second sub scanning aperture 30 b and the second main scanning aperture 40 b , and are then guided to the second deflecting surface 50 b of the deflecting unit 50 .

[0075] Therefore, the beam widths of the third and fourth light beams LC and LD are adjusted in the main scanning direction and the sub scanning direction and converge in the sub scanning direction so that a long line image is formed in the main scanning direction near the second deflecting surface 50 b of the deflecting unit 50 .

[0076] In the light scanning device 1 according to the present embodiment, the first light beam LA and the second light beam LB emitted respectively from the first light source 10a and the second light source 10b are incident on the first deflecting surface 50a of the deflecting unit 50 at different angles relative to the main scanning section in the sub-scan section.

[0077] Specifically, the first light beam LA and the second light beam LB are incident on the first deflecting surface 50 a of the deflecting unit 50 obliquely at angles of −2.70° and +2.70°, respectively, with respect to the main scanning section.

[0078] The third light beam LC and the fourth light beam LD emitted from the third light source 10c and the fourth light source 10d, respectively, are incident on the second deflecting surface 50b of the deflecting unit 50 obliquely at different angles from each other in the sub-scan section with respect to the main-scan section.

[0079] Specifically, the third light beam LC and the fourth light beam LD are incident on the second deflecting surface 50 b of the deflecting unit 50 at angles of −2.70° and +2.70°, respectively, with respect to the main scanning section.

[0080] Next, the first light beam LA and the second light beam LB deflected by the first deflecting surface 50a of the deflecting unit 50 are respectively converged on the first scanned surface 100a and the second scanned surface 100b by the first imaging optical element 60a and the second imaging optical elements 80a and 80b.

[0081] The third light beam LC and the fourth light beam LD deflected by the second deflecting surface 50b of the deflecting unit 50 are respectively converged on the third scanned surface 100c and the fourth scanned surface 100d by the first imaging optical element 60b and the second imaging optical elements 80c and 80d, respectively.

[0082] The rotation of the deflection unit 50 causes the first to fourth scanned surfaces 100a to 100d to be optically scanned at a uniform speed in the main scanning direction using the first to fourth light beams LA to LD, respectively, thereby allowing images to be recorded on the first to fourth scanned surfaces 100a to 100d.

[0083] In the optical scanning device 1 according to the present embodiment, in order to determine the writing start timing at which the optical scanning of the first to fourth scanned surfaces 100a to 100d is to be started, a synchronization detection optical system (not shown) is provided.

[0084] Specifically, a predetermined light beam deflected to a predetermined direction by the deflection unit 50 is guided to a sensor (not shown) for synchronization detection through a lens (not shown) for synchronization detection.

[0085] A synchronization detection signal (light beam detection (BD) signal) acquired by detecting a signal output from the sensor for synchronization detection is used to determine the light emission timing of each of the first to fourth light sources 10 a to 10 d .

[0086] In the optical scanning device 1 according to this embodiment, the first incident optical system is formed by the lower part 21al of the first incident optical element 20a in the sub-scanning direction (the first refractive optical part), the lower opening part 30al of the first sub-scanning aperture 30a and the opening part of the first main scanning aperture 40a.

[0087] The second incident optical system is formed by the upper portion 21au (second refractive optical portion) of the first incident optical element 20a in the sub scanning direction, the upper opening portion 30au of the first sub scanning diaphragm 30a, and the opening portion of the first main scanning diaphragm 40a.

[0088] The third incident optical system is formed by the lower side portion of the second incident optical element 20b in the sub-scanning direction, the lower side opening portion of the second sub-scanning aperture 30b, and the opening portion of the second main-scanning aperture 40b.

[0089] The fourth incident optical system is formed by the upper portion of the second incident optical element 20b in the sub-scanning direction, the upper opening portion of the second sub-scanning aperture 30b, and the opening portion of the second main-scanning aperture 40b.

[0090] In the optical scanning device 1 according to the present embodiment, the first imaging optical system is formed by the upper side portion of the first imaging optical element 60 a in the sub-scanning direction and the second imaging optical element 80 a .

[0091] The second imaging optical system is formed by the lower side portion of the first imaging optical element 60 a in the sub-scanning direction and the second imaging optical element 80 b .

[0092] The third imaging optical system is formed by the upper side portion of the first imaging optical element 60 b in the sub-scanning direction and the second imaging optical element 80 c .

[0093] The fourth imaging optical system is formed by the lower side portion of the first imaging optical element 60b in the sub-scanning direction and the second imaging optical element 80d.

[0094] Next, specification values ​​of the optical scanning device 1 according to the present embodiment, the refractive index and coordinates of each optical element, and the shape of the optical surface of each optical element are shown in Table 1, Table 2, and Table 3-1 and Table 3-2, respectively.

[0095] In Table 2, Table 3-1, and Table 3-2, only information on the first and second incident optical systems and the first and second imaging optical systems is shown.

[0096] That is, in Table 2, Table 3-1, and Table 3-2, information on the third and fourth incident optical systems and the third and fourth imaging optical systems is omitted.

[0097] Table 1

[0098]

[0099]

[0100] Table 2

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107] Table 3-1

[0108]

[0109]

[0110]

[0111] Table 3-2

[0112]

[0113]

[0114] The upper part 21au and the lower part 21a1 of the first incident optical element 20a and the upper part and the lower part of the second incident optical element 20b provided in the light scanning device 1 according to the present embodiment each have an incident surface having a diffraction surface of a diffraction grating formed therein.

[0115] The first incident optical element 20a and the second incident optical element 20b are formed by injection molding using a plastic material as described above.

[0116] Therefore, the optical scanning device 1 adopts a so-called temperature compensation optical system in which changes in the refractive power of the first incident optical element 20a and the second incident optical element 20b due to environmental changes are compensated by changes in the diffraction power of the diffraction surface that accompany changes in the wavelengths of the first light beams LA to the fourth light beams LD in the first light source 10a to the fourth light source 10d.

[0117] Specifically, the diffraction surface formed as the incident surface of each of the upper part 21au and the lower part 21a1 of the first incident optical element 20a and the upper part and the lower part of the second incident optical element 20b is defined by the phase function represented by the following expression (1).

[0118]

[0119] In Expression (1), φ represents a phase function, M represents a diffraction order, and λ represents a design wavelength, and since the optical scanning device 1 according to the present embodiment uses first-order diffracted light, M is 1 and λ is 790 nm.

[0120] The first imaging optical elements 60a and 60b and the second imaging optical elements 80a to 80d provided in the optical scanning device 1 according to the present embodiment have an incident surface and an exit surface, each of which has a shape (meridian shape) in the main scanning section of an aspherical shape represented by a tenth-order polynomial function.

[0121] Specifically, in each of the first imaging optical elements 60 a and 60 b and the second imaging optical elements 80 a to 80 d , an intersection point (surface vertex) between an optical surface and the optical axis is set as an origin.

[0122] On each optical surface, a direction parallel to the optical axis, an axis perpendicular to the optical axis in a main scanning section, and an axis perpendicular to the optical axis in a sub scanning section are set as an X axis, a Y axis, and a Z axis, respectively.

[0123] In this case, the aspherical shape in the main scanning section of each of the incident surface and the exit surface of the first imaging optical elements 60a and 60b and the second imaging optical elements 80a to 80d is expressed by the following expression (2).

[0124]

[0125] In Expression (2), R represents the radius of curvature (meridional radius of curvature) in the main scanning section, K represents the eccentricity, and B i represents the aspheric coefficient.

[0126] The shape (sagittal shape) in the sub-scan section of each of the incident surface and the exit surface of the first imaging optical elements 60a and 60b and the second imaging optical elements 80a to 80d is expressed by the following Expression (3).

[0127]

[0128] In Expression (3), S represents a shape (sagittal shape) in a cross section including a normal line of a meridian at a predetermined position in the main scanning direction and perpendicular to the main scanning cross section, and M ij represents the aspheric coefficient.

[0129] The curvature radius r' (sagittal curvature radius) in the sub-scan section at a position spaced Y from the optical axis in the main-scan direction is expressed by the following expression (4).

[0130]

[0131] In Expression (4), "r" represents the sagittal curvature radius on the optical axis, and Ei represents the sagittal variation coefficient.

[0132] In the light scanning device 1 according to the present embodiment, the shape of the optical surface of each optical element is defined by the functions expressed in the above expressions (1) to (4), but is not limited thereto and may be defined by other functions.

[0133] like Figure 1A and Figure 1B As illustrated in the figure, in the light scanning device 1 according to the present embodiment, the first light beam LA and the second light beam LB travel through the first imaging optical element 60a shared by the first light beam LA and the second light beam LB, and the third light beam LC and the fourth light beam LD travel through the first imaging optical element 60b shared by the third light beam LC and the fourth light beam LD.

[0134] Specifically, the first light beam LA and the second light beam LB travel through the upper side portion 61 a and the lower side portion 62 a of the first imaging optical element 60 a in the sub scanning direction, respectively.

[0135] The third light beam LC and the fourth light beam LD travel through an upper side portion and a lower side portion of the first imaging optical element 60b in the sub scanning direction, respectively.

[0136] Here, the upper part and the lower part in the sub scanning direction may also be respectively referred to as "opposite to the scanned surface side part" and "scanned surface side part" on the side opposite to the scanned surface in the sub scanning direction.

[0137] As shown in Table 3-1 and Table 3-2, the shape of the exit surface of the first imaging optical element 60a is defined to be different between the upper portion 61a through which the first light beam LA travels and the lower portion 62a through which the second light beam LB travels.

[0138] That is, although being a single optical element, the first imaging optical element 60a is formed to have a multi-stage configuration in which the shape of the exit surface is different between the upper portion 61a and the lower portion 62a in the sub scanning direction, and the first imaging optical element 60b also has a similar configuration.

[0139] Figure 2 A sub-scanning cross-sectional view of the first imaging optical element 60 a provided in the light scanning device 1 according to the present embodiment is shown.

[0140] like Figure 2 As illustrated in FIG. 1 , the first imaging optical element 60 a has an upper portion 61 a through which the first light beam LA travels and a lower portion 62 a through which the second light beam LB travels, on each side of a center line indicated by a dotted line in the sub scanning direction.

[0141] The upper portion 61 a and the lower portion 62 a of the first imaging optical element 60 a have exit surfaces formed to have the shapes shown in Table 3-1 and Table 3-2, respectively.

[0142] This enables the first imaging optical element 60a to efficiently condense both the first light beam LA and the second light beam LB emitted from the first light source 10a and the second light source 10b, respectively.

[0143] Figure 3 A partial projection diagram in the main scanning section of the optical scanning device 1 according to the present embodiment is shown.

[0144] Specifically, in Figure 3 4 and 5 , a second incident optical system, a second imaging optical system, a first reflecting element 70 b and a second reflecting element 90 a forming an optical path of the second light beam LB are illustrated in FIG.

[0145] In the optical scanning device 1 according to this embodiment, multiple reflective elements are used to fold the optical paths of the first light beam LA to the fourth light beam LD in the sub-scanning direction, thereby reducing the size of the housing 2 and shortening the distance between adjacent scanned surfaces (drum pitch).

[0146] Results, such as Figure 3As illustrated in FIG. 2 , when projected in the main scanning section, the ends of the first incident optical element 20 a and the second reflecting element 90 a in the longitudinal direction are arranged very close to each other.

[0147] In other words, the first incident optical element 20a and the second reflecting element 90a are arranged in the first region and the second region, respectively, in the X direction, and at least a portion of the first region and at least a portion of the second region overlap each other.

[0148] To explain further, when projected in the main scanning section, the first incident optical element 20a is arranged on an extension line in the direction (Y direction) in which the second reflecting element 90a extends.

[0149] Such an arrangement in which a plurality of optical elements are too close to each other is not preferable in terms of the outer shape of each optical element and the space to be formed for a holding portion for holding each optical element.

[0150] On the other hand, the first incident optical element 20a in the optical scanning device 1 according to the present embodiment is arranged in a manner advantageous from the perspective of the overall optical performance of the device, error sensitivity, etc., and Figure 3 The optical arrangement illustrated in is therefore optically preferred.

[0151] Next, the specific shapes of the first incident optical element 20 a and the second incident optical element 20 b provided in the light scanning device 1 according to the present embodiment are described.

[0152] Figure 4A and Figure 4B A front view and a side view of the first incident optical element 20a provided in the light scanning device 1 according to the present embodiment are respectively shown.

[0153] Figure 4B The two arrows illustrated in FIG. 1 indicate the traveling directions of the first light beam LA and the second light beam LB, respectively, and Figure 4B The dotted lines illustrated in Schematically indicate the shapes of the respective optical surfaces in the sub-scan section.

[0154] The first incident optical element 20a and the second incident optical element 20b have the same shape as each other, and therefore, only the shape of the first incident optical element 20a will be described below.

[0155] like Figure 4A and Figure 4B As illustrated in FIG. 1 , the first incident optical element 20a provided in the light scanning device 1 according to the present embodiment is a so-called double lens element formed of an upper portion 21au and a lower portion 21a1 arranged at positions different from each other in the sub-scanning direction.

[0156] That is, in the first incident optical element 20a, the upper portion 21au and the lower portion 21a1 are formed integrally with each other.

[0157] The lower portion 21a1 and the upper portion 21au may respectively converge the first light beam LA and the second light beam LB respectively emitted from the first light source 10a and the second light source 10b.

[0158] The first incident optical element 20a is also provided with a plurality of reference surfaces 221a, 222a, and 223a (a second protruding portion group) for positioning in the optical axis direction of the first incident optical element 20a.

[0159] Specifically, the plurality of reference surfaces 221a to 223a are formed as protruding portions protruding outward from the outer shape surface 22ae on the exit surface side of the ineffective region surrounding the upper portion 21au and the lower portion 21a1 through which the first and second light beams LA and LB do not travel.

[0160] As described later, the plurality of reference surfaces 221 a to 223 a abut against a holding portion (projecting portion) 2 p provided in the housing 2 , thereby determining the position of the first incident optical element 20 a in the optical axis direction.

[0161] As described above, the first incident optical element 20a is formed by injection molding of the plastic material injected from the gate portion 24a.

[0162] For this reason, Figure 4A As illustrated in FIG. 1 , the first incident optical element 20a is provided with a plurality of pressing surfaces 231a, 232a, 233a, 234a, 235a, and 236a which are pressed by a push rod when the first incident optical element 20a is released from a mold.

[0163] Specifically, similarly to the plurality of reference surfaces 221 a to 223 a , the plurality of pressing surfaces 231 a to 236 a (third protruding portion group) are formed as protruding portions protruding outward from the outer shape surface 22 ae.

[0164] On the other hand, the protrusion amount of each of the plurality of pressing surfaces 231 a to 236 a is smaller than the protrusion amount of each of the plurality of reference surfaces 221 a to 223 a .

[0165] That is, the plurality of pressing surfaces 231 a to 236 a do not contribute to the positioning of the first incident optical element 20 a in the optical axis direction.

[0166] In the first incident optical element 20a, some of the plurality of pressing surfaces 231a to 236a (specifically, the plurality of pressing surfaces 231a, 233a, 234a, 236a) are formed closer to the outside in the sub scanning direction than the plurality of reference surfaces 221a to 223a.

[0167] In the case where the plurality of pressing surfaces 231a, 233a, 234a, and 236a are formed closer to the outside in the sub-scanning direction than the plurality of reference surfaces 221a to 223a, shape changes that cause molding defects when releasing the first incident optical element 20a can be suppressed.

[0168] Next, the holding of the first incident optical element 20 a and the second reflecting element 90 a in the optical scanning device 1 according to the present embodiment will be described.

[0169] Figure 5A , Figure 5B and Figure 5C A view of the vicinity of the first incident optical element 20a (optical element) of the light scanning device 1 according to the present embodiment viewed from the optical axis direction, a view of the vicinity viewed from the main scanning direction, and a view of the vicinity viewed from the sub-scanning direction are respectively shown.

[0170] In the optical scanning device 1 according to the present embodiment, as Figure 5A , Figure 5B and Figure 5C As illustrated in FIG. 2 , a protruding portion 2 p that protrudes in the sub-scanning direction and is integrated with the first sub-scanning aperture 30 a is integrally formed in the housing 2 .

[0171] In other words, the housing 2 includes a box portion having an inner space in which optical elements are arranged and a cover portion covering the inner space, and the protrusion portion 2p protrudes in the sub-scanning direction from a predetermined position on the bottom surface of the box portion.

[0172] To explain further, the protrusion 2 p is formed of the same material as the rest of the housing 2 .

[0173] The direction in which the protruding portion 2p protrudes is not limited to the sub scanning direction, and the protruding portion 2p may protrude in a direction that is not parallel to the sub scanning direction, such as a direction including a component of the sub scanning direction.

[0174] A plurality of reference surfaces 221a to 223a formed on the outer shape surface 22ae on the exit surface side of the first incident optical element 20a abut against the protruding portion 2p in the main scanning direction (Y direction).

[0175] Specifically, on the surface (first surface) of the protrusion 2p that is perpendicular to the optical axis of the first incident optical system, two protrusions 2a and 2b extending in the sub-scanning direction are formed on both sides of the optical axis direction (X direction) of the first imaging optical system to the fourth imaging optical system relative to the upper opening portion 30au and the lower opening portion 30al of the first sub-scanning aperture 30a.

[0176] The plurality of reference surfaces 221 a to 223 a abut against the two protruding portions 2 a and 2 b (first protruding portion group).

[0177] In the optical scanning device 1 according to the present embodiment, as Figure 5C As illustrated in FIG. 2 , the two protruding portions 2 a and 2 b have different lengths from each other in the main scanning section.

[0178] like Figure 5A and Figure 5B As illustrated in FIG. 2 , biasing portions 2 c and 2 d formed integrally with the housing 2 bias the first incident optical element 20 a toward the protruding portions 2 a and 2 b of the protruding portion 2 p.

[0179] As described above, since the biasing portions 2c and 2d bias the first incident optical element 20a in the optical axis direction toward the protruding portions 2a and 2b of the protruding portion 2p, the position of the first incident optical element 20a in the optical axis direction is determined.

[0180] That is, in the light scanning device 1 according to the present embodiment, the first incident optical element 20a is held by the protruding portion 2p and the offset portions 2c and 2d.

[0181] like FIG. 5A to FIG. 5C As shown in the figure, the second reflecting element 90a (reflecting optical element) abuts against the protruding portion 2p also in the sub-scanning direction (Z direction).

[0182] Specifically, the second reflecting element 90a is disposed on a recessed portion formed on a surface (second surface) of the protruding portion 2p parallel to the optical axis of the first incident optical system, and is biased toward the recessed portion by a biasing member (not shown).

[0183] That is, in the optical scanning device 1 according to the present embodiment, the second reflecting element 90 a is held by the protruding portion 2 p and the biasing member.

[0184] The protruding portion 2p may be formed so that the second reflecting element 90a abuts against the protruding portion 2p in the main scanning direction (Y direction) as necessary.

[0185] In the optical scanning device 1 according to the present embodiment, by adopting the above-described configuration, although the first incident optical element 20a and the second reflecting element 90a are close to each other in the main scanning section, the first incident optical element 20a can be held.

[0186] That is, in the light scanning device 1 according to the present embodiment, the first incident optical element 20a can be supported to be fixed without providing a separate supporting member for supporting the first incident optical element 20a.

[0187] In the optical scanning device 1 according to the present embodiment, as FIG. 5A to FIG. 5CAs illustrated in FIG. 2 , both the first incident optical element 20 a and the second reflecting element 90 a can be held by using the common protruding portion 2 p.

[0188] Therefore, the shape of the housing 2 can be simplified compared to a case where a holding portion for holding the first incident optical element 20 a and a holding portion for holding the second reflecting element 90 a are formed to be spaced apart from each other.

[0189] In addition, in the optical scanning device 1 according to the present embodiment, as Figure 5A and Figure 5C As shown in FIG. 2 , a holding portion for holding the first incident optical element 20 a , a holding portion for holding the second reflecting element 90 a , and the first sub-scanning stop 30 a are integrally formed as a protruding portion 2 p .

[0190] Therefore, in the optical scanning device 1 according to the present embodiment, the shape of the housing 2 can be simplified.

[0191] Fig. 6A and Figure 6B Image height correlations of a line spread function (LSF) depth center position in the main scanning direction and an LSF depth center position in the sub scanning direction on each scanned surface in the light scanning device 1 according to the present embodiment are respectively shown.

[0192] Here, the LSF depth center position in the main scanning direction and the LSF depth center position in the sub-scanning direction refer to the center position of the area where the LSF width in the main scanning direction and the sub-scanning direction is equal to or less than the slice level when defocused in the optical axis direction near the predetermined scanned surface.

[0193] In the light scanning device 1 according to the present embodiment, the slice level is set to 120 μm for the entire image height in both the main scanning direction and the sub-scanning direction.

[0194] The LSF width in the main scanning direction and the LSF width in the sub-scanning direction refer to the width of a slice of the light quantity distribution when the light quantity distribution obtained by integrating the light spot distribution at each image height in the sub-scanning direction and the main scanning direction is sliced ​​at a position that is 13.5% of the maximum value.

[0195] like Fig. 6A and Figure 6B As shown in , for all image heights, both the LSF depth center position in the main scanning direction and the LSF depth center position in the sub-scanning direction fall within ±1 mm, and this indicates that excellent imaging performance is achieved in the light scanning device 1 according to the present embodiment.

[0196] Figure 7A partial projection diagram in the main scanning section for illustrating an inequality in the optical scanning device 1 according to the present embodiment is shown.

[0197] First, the distance in the X direction between the on-axis deflection point C0 on the first deflecting surface 50a of the deflecting unit 50 and the center of the outer shape surface 22ae of the first incident optical element 20a where the plurality of reference surfaces 221a to 223a are formed is represented by LX.

[0198] Here, the on-axis deflection point C0 refers to a deflection point on the first deflecting surface 50a of the principal rays of the first light beam LA and the second light beam LB deflected by the deflection unit 50 in order for the on-axis image height on the first scanned surface 100a and the second scanned surface 100b to be scanned with the first light beam LA and the second light beam LB.

[0199] The distance in the X direction between the on-axis deflection point C0 and the center of the reflecting surface of the second reflecting element 90a is represented by M X express.

[0200] In this case, in the optical scanning device 1 according to the present embodiment, it is preferable that the following inequality (5) is satisfied.

[0201] 0.500 <M X / L X <1.500 … (5)

[0202] When the ratio exceeds the upper limit value in inequality (5), the second reflecting element 90a is separated too far from the deflection unit 50 in the main scanning section, which makes it difficult to shorten the interval between adjacent scanned surfaces, that is, it is difficult to reduce the size of the optical scanning device 1 according to this embodiment, making this not preferred.

[0203] On the other hand, when the ratio falls below the lower limit value in inequality (5), the second reflecting element 90a is too close to the deflection unit 50 in the main scanning section. Therefore, the second reflecting element 90a may interfere with at least one optical element provided in the third imaging optical system and the fourth imaging optical system located on the opposite side relative to the deflection unit 50.

[0204] Then, when the second reflecting element 90 a and at least one optical element are separated from each other in the sub-scanning direction in order to suppress such interference, the light scanning device 1 according to the present embodiment is increased in size in the sub-scanning direction, making this not preferable.

[0205] In the optical scanning device 1 according to the present embodiment, it is more preferable that the following inequality (5a) is satisfied.

[0206] 0.700 <M X / L X<1.400…(5a)

[0207] The distance in the Y direction between the on-axis deflection point C0 and the center of the outer surface 22ae of the first incident optical element 20a on which the plurality of reference surfaces 221a to 223a are formed is represented by L Y express.

[0208] The distance in the Y direction between the on-axis deflection point C0 and the end of the second reflecting element 90a closest to the first incident optical element 20a is represented by M Y express.

[0209] In this case, in the optical scanning device 1 according to the present embodiment, it is preferable that the following inequality (6) is satisfied.

[0210] 0.9000 <M Y / L Y <0.9700 … (6)

[0211] When the ratio exceeds the upper limit value in the inequality (6), the first incident optical element 20a and the second reflecting element 90a are too close to each other and may cause interference therebetween, making this unpreferable.

[0212] On the other hand, when the ratio falls below the lower limit value in inequality (6), the first incident optical element 20a and the second reflecting element 90a are too far apart from each other. This causes an increase in the size of the optical scanning device 1 according to the present embodiment, making this unpreferable.

[0213] In addition, when the ratio falls below the lower limit value in inequality (6), it is necessary to provide a holding portion for holding the first incident optical element 20a and a holding portion for holding the second reflecting element 90a separately from each other, instead of the single protrusion 2p. This complicates the structure of the housing 2, making it undesirable.

[0214] In the optical scanning device 1 according to the present embodiment, it is more preferable that the following inequality (6a) is satisfied.

[0215] 0.9300 <M Y / L Y <0.9700…(6a)

[0216] The distance in the main scanning section (XY section) between the on-axis deflection point C0 and the center of the outer shape surface 22ae of the first incident optical element 20a where the plurality of reference surfaces 221a to 223a are formed is represented by Lt.

[0217] The distance between the on-axis deflection point C0 and the first light source 10a and the second light source 10b in the optical axis direction of the first incident optical system and the second incident optical system (the optical axis direction of the first incident optical element 20a) is represented by L i express.

[0218] In this case, in the optical scanning device 1 according to the present embodiment, it is preferable that the following inequality (7) is satisfied.

[0219] 0.70 <L t / L i <0.90 … (7)

[0220] When the ratio exceeds the upper limit value in the inequality (7), the first incident optical element 20a and the second reflecting element 90a are separated from each other too far. Therefore, it is necessary to provide a holding portion for holding the first incident optical element 20a and a holding portion for holding the second reflecting element 90a separately from each other, instead of the single protrusion 2p. This complicates the structure of the housing 2, making it unpreferable.

[0221] On the other hand, when the ratio drops below the lower limit value in inequality (7), the optical efficiency in the optical scanning device 1 according to the present embodiment decreases, specifically, the amount of light of the first light beam LA and the second light beam LB reaching the first scanned surface 100a and the second scanned surface 100b, respectively, decreases, making this not preferred.

[0222] In the optical scanning device 1 according to the present embodiment, it is more preferable that the following inequality (7a) is satisfied.

[0223] 0.75 <L t / L i <0.85…(7a)

[0224] In the optical scanning device 1 according to the present embodiment, as shown in Table 1 and Table 10 described later, inequalities (5), (5a), (6), (6a), (7), and (7a) are satisfied.

[0225] As described above, in the optical scanning device 1 according to the present embodiment, the first incident optical element 20 a and the second reflecting element 90 a are held by the protruding portion 2 p formed integrally with the housing 2 .

[0226] Therefore, when downsizing is to be achieved by arranging the first incident optical element 20a and the second reflecting element 90a close to each other, both the first incident optical element 20a and the second reflecting element 90a can be held in a simple configuration.

[0227] That is, in the optical scanning device 1 according to the present embodiment, the number of components can be reduced by holding the first incident optical element 20a and the second reflecting element 90a by the protrusion 2p formed integrally with the housing 2 instead of using separate holding members.

[0228] [Second embodiment]

[0229] Fig. 8A and Figure 8B The expanded views of the main scanning section of the optical scanning device 201 according to the second embodiment of the present invention are shown respectively (corresponding to Figure 1A ) and its local sub-scan cross-sectional view (corresponding to Figure 1B ).

[0230] Fig. 9 A partial projection diagram in the main scanning section of the optical scanning device 201 according to the second embodiment (corresponding to Figure 3 ).

[0231] The light scanning device 201 according to the present embodiment has the same configuration as that of the light scanning device 1 according to the first embodiment except for differences in various numerical values. Therefore, the same components are denoted by the same reference numerals, and descriptions thereof are omitted.

[0232] Specification values ​​of the light scanning device 201 according to the present embodiment, the refractive index and coordinates of each optical element, and the shape of the optical surface of each optical element are shown in Table 4, Table 5, and Table 6-1 and Table 6-2, respectively.

[0233] In Table 5, Table 6-1, and Table 6-2, only information on the first and second incident optical systems and the first and second imaging optical systems is shown.

[0234] That is, in Table 5, Table 6-1, and Table 6-2, information on the third and fourth incident optical systems and the third and fourth imaging optical systems is omitted.

[0235] Table 4

[0236]

[0237]

[0238] Table 5

[0239]

[0240]

[0241]

[0242]

[0243]

[0244]

[0245] Table 6-1

[0246]

[0247]

[0248]

[0249] Table 6-2

[0250]

[0251]

[0252] Fig. 10A and Fig. 10B The image height correlations of the LSF depth center position in the main scanning direction and the LSF depth center position in the sub-scanning direction on each scanned surface in the light scanning device 201 according to the present embodiment are respectively shown.

[0253] like Fig. 10A As shown in , the LSF depth center position in the main scanning direction falls within ±1 mm for the entire image height.

[0254] like Fig. 10B As shown in , for all image heights except some image heights, the LSF depth center position in the sub-scanning direction falls within ±1 mm.

[0255] The above shows that excellent imaging performance is achieved in the optical scanning device 201 according to the present embodiment.

[0256] As described above, in the light scanning device 201 according to the present embodiment, the first incident optical element 20 a and the second reflecting element 90 a are held by the protruding portion 2 p formed integrally with the housing 2 .

[0257] Therefore, when downsizing is to be achieved by arranging the first incident optical element 20a and the second reflecting element 90a close to each other, both the first incident optical element 20a and the second reflecting element 90a can be held in a simple configuration.

[0258] [Third embodiment]

[0259] Fig.11A and Fig. 11BThe expanded views of the main scanning section of the optical scanning device 301 according to the third embodiment of the present invention are shown respectively (corresponding to Figure 1A ) and its local sub-scan cross-sectional view (corresponding to Figure 1B ).

[0260] Fig.12 A partial projection diagram in the main scanning section of the optical scanning device 301 according to the third embodiment (corresponding to Figure 3 ).

[0261] The light scanning device 301 according to the present embodiment has the same configuration as that of the light scanning device 1 according to the first embodiment except for differences in various numerical values. Therefore, the same components are denoted by the same reference numerals, and descriptions thereof are omitted.

[0262] The specification values ​​of the light scanning device 301 according to the present embodiment, the refractive index and coordinates of each optical element, and the shape of the optical surface of each optical element are shown in Table 7, Table 8, and Table 9-1 and Table 9-2, respectively.

[0263] In Table 8, Table 9-1, and Table 9-2, only information on the first and second incident optical systems and the first and second imaging optical systems is shown.

[0264] That is, in Table 8, Table 9-1, and Table 9-2, information on the third and fourth incident optical systems and the third and fourth imaging optical systems is omitted.

[0265] Table 7

[0266]

[0267]

[0268] Table 8

[0269]

[0270]

[0271]

[0272]

[0273]

[0274] Table 9-1

[0275]

[0276]

[0277] Table 9-2

[0278]

[0279]

[0280]

[0281] Fig.13A and Fig. 13B The image height correlations of the LSF depth center position in the main scanning direction and the LSF depth center position in the sub-scanning direction on each scanned surface in the light scanning device 301 according to the present embodiment are respectively shown.

[0282] like Fig.13A As shown in , the LSF depth center position in the main scanning direction falls within ±1 mm for the entire image height.

[0283] like Fig. 13B As shown in , for all image heights except some image heights, the LSF depth center position in the sub-scanning direction falls within ±1 mm.

[0284] The above shows that excellent imaging performance is achieved in the optical scanning device 301 according to the present embodiment.

[0285] As described above, in the light scanning device 301 according to the present embodiment, the first incident optical element 20 a and the second reflecting element 90 a are held by the protruding portion 2 p formed integrally with the housing 2 .

[0286] Therefore, when downsizing is to be achieved by arranging the first incident optical element 20a and the second reflecting element 90a close to each other, both the first incident optical element 20a and the second reflecting element 90a can be held in a simple configuration.

[0287] Table 10 below shows the relationship between various values ​​and inequalities in each optical scanning device according to the first to third embodiments of the present invention.

[0288] Table 10

[0289]

[0290]

[0291] According to the present embodiment, it is possible to provide an optical scanning device that can achieve size reduction with a simple configuration.

[0292] [Image forming apparatus]

[0293] Fig.14A sub-scan cross-sectional view showing a main portion of an image forming device 99 including the optical scanning device 1 according to any one of the first to third embodiments.

[0294] The image forming apparatus 99 is a tandem type color image forming apparatus in which the optical scanning apparatus 1 according to any of the first to third embodiments records image information on surfaces (scanned surfaces) of four photosensitive drums each being an image bearing member.

[0295] The image forming apparatus 99 includes the optical scanning device 1 according to any of the first to third embodiments, and first, second, third, and fourth photosensitive drums 100 a , 100 b , 100 c , and 100 d serving as image bearing members.

[0296] The image forming device 99 further includes first, second, third, and fourth developing units 15 , 16 , 17 , and 18 , a conveyor belt 91 , a printer controller 93 , and a fixing unit 94 .

[0297] like Fig.14 As illustrated in FIG. 8 , color signals of red (R), green (G), and blue (B) output from an external device 92 (eg, a personal computer) are input to an image forming device 99 .

[0298] Then, the input color signal is converted into image data (dot data) of cyan (C), magenta (M), yellow (Y), and black (K) by the printer controller 93 in the image forming apparatus 99 .

[0299] Next, the image data generated by the conversion is input to the light scanning device 1 according to any one of the first to third embodiments.

[0300] A first light beam LA, a second light beam LB, a third light beam LC and a fourth light beam LD modulated based on image data are emitted from the light scanning device 1, and the photosensitive surfaces of the first to fourth photosensitive drums 100a to 100d are scanned in the main scanning direction by the first light beam LA, the second light beam LB, the third light beam LC and the fourth light beam LD.

[0301] A charging roller (not shown) that uniformly charges the photosensitive surfaces of the first to fourth photosensitive drums 100 a to 100 d is provided so as to abut against the photosensitive surfaces.

[0302] Then, the light scanning device 1 irradiates the photosensitive surfaces of the first to fourth photosensitive drums 100 a to 100 d charged by the charging roller with the first to fourth light beams LA to LD.

[0303] As described above, the first to fourth light beams LA to LD have been modulated based on the image data of the respective colors, and electrostatic latent images are formed on the photosensitive surfaces by irradiating the respective photosensitive surfaces of the first to fourth photosensitive drums 100a to 100d with the first to fourth light beams LA to LD.

[0304] The formed electrostatic latent image is developed into a toner image by first to fourth developing units 15 to 18 which are arranged to abut against the first to fourth photosensitive drums 100 a to 100 d , respectively.

[0305] Next, the developed toner image is transferred in a superimposed manner onto a sheet (transfer material) (not shown) being transported on the transport belt 91 by a transfer roller (transfer unit) (not shown) arranged opposite to the first to fourth photosensitive drums 100a to 100d. Thus, a full-color image is formed on the sheet.

[0306] The sheet to which the unfixed toner image has been transferred is further conveyed by the conveying belt 91 to a portion of the sheet provided downstream of the first photosensitive drum 100a to the fourth photosensitive drum 100d (at the bottom of the sheet). Fig.14 ) on the left side of the fixing unit 94.

[0307] The fixing unit 94 includes a fixing roller including a fixing heater (not shown) therein and a pressure roller arranged in pressure contact with the fixing roller.

[0308] By heating the sheet that has been conveyed by the conveying belt 91 under pressure applied from the pressure contact portion between the fixing roller and the pressure roller, the unfixed toner image on the sheet is fixed.

[0309] Discharge rollers (not shown) are further provided downstream of the fixing unit 94 , and discharge the sheet to which the toner image is fixed to the outside of the image forming device 99 .

[0310] In the image forming device 99, the light scanning device 1 records the image signal (image information) on the photosensitive surfaces of the first to fourth photosensitive drums 100a to 100d, each corresponding to one color of cyan (C), magenta (M), Y (yellow), and K (black). Therefore, a color image can be printed at a high speed.

[0311] As the external device 92 , for example, a color image reading device including a CCD sensor can be used.

[0312] In this case, the color image reading device and the image forming device 99 form a color digital copying machine.

[0313] While embodiments of the present invention have been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An optical scanning device, comprising: a deflection unit configured to deflect the light beam from the first light source to scan the first scanned surface in a main scanning direction; a first imaging optical system and a reflecting element, wherein the first imaging optical system and the reflecting element are configured to guide the first light beam deflected by the deflection unit to the first scanned surface; an optical element configured to guide the first light beam emitted from the first light source to the deflection unit; as well as a holding member configured to hold the deflection unit, the first imaging optical system, the reflecting element, and the optical element, Wherein, the optical element and the reflective element abut against the holding member.

2. The optical scanning device according to claim 1, wherein: When the optical element and the reflective element are projected in a main scanning section, the optical element is arranged on a line extending from the reflective element in the main scanning direction.

3. The optical scanning device according to claim 1, wherein: The holding member includes a first holding portion extending in the sub scanning direction, and the optical element and the reflecting element abut against the first holding portion.

4. The optical scanning device according to claim 3, wherein: The first holding portion is provided with a first opening portion configured to adjust the first light beam in the sub scanning direction.

5. The optical scanning device according to claim 3, wherein: The first holding portion includes a plurality of protruding portions that abut against a surface of the optical element on the deflecting unit side.

6. The optical scanning device according to claim 5, wherein: The retaining member includes a biasing portion configured to bias the optical element toward the plurality of protruding portions.

7. The optical scanning device according to claim 5, wherein: The lengths of the plurality of protruding portions in the main-scan section are different from each other.

8. The optical scanning device according to claim 5, wherein: The surface of the optical element on the deflection unit side includes a plurality of protruding portions abutting against the plurality of protruding portions.

9. The optical scanning device according to claim 1, wherein: The optical element is configured to convert a convergence degree of the first light beam in a main scanning section and to converge the first light beam in a sub scanning section.

10. The optical scanning device according to claim 1, further comprising a second imaging optical system configured to guide the second light beam deflected by the deflection unit to a second scanned surface, in, The deflection unit is configured to deflect the first light beam and the second light beam respectively by a first deflection surface to scan the first scanned surface and the second scanned surface in the main scanning direction, and The optical element includes a first optical portion configured to guide the first light beam to the first deflecting surface and a second optical portion configured to guide the second light beam to the first deflecting surface.

11. The optical scanning device according to claim 10, wherein: The holding member includes a first holding portion extending in the sub-scanning direction, the optical element and the reflecting element are adjacent to the first holding portion, and the first holding portion is provided with a first opening portion and a second opening portion, and the first opening portion and the second opening portion are configured to adjust the first light beam and the second light beam in the sub-scanning direction.

12. The optical scanning device according to claim 3, wherein: The optical element abuts against the first holding portion in the main scanning direction, and the reflecting element abuts against the first holding portion in the sub-scanning direction.

13. The optical scanning device according to claim 3, in, The holding member includes a housing in which the deflection unit, the first imaging optical system, the reflective element, and the optical element are arranged, and wherein the first holding portion protrudes from a bottom surface of the housing in the sub-scanning direction.

14. The optical scanning device according to claim 1, further comprising a second imaging optical system configured to guide the second light beam deflected by the deflection unit to a second scanned surface, in, The deflection unit is configured to deflect the first light beam and the second light beam respectively by a first deflection surface to scan the first scanned surface and the second scanned surface in the main scanning direction, and Among them, the following conditions are met: 0.500<M X / L X <1.500, Among them, L X represents a distance in a first direction between an on-axis deflection point of the first light beam on the first deflecting surface and the center of a surface of the optical element adjacent to the holding member, the first direction being parallel to a straight line passing through a first intersection point of the first scanned surface and the optical axis of the first imaging optical system and a second intersection point of the second scanned surface and the optical axis of the second imaging optical system, and M X represents the distance in the first direction between the on-axis deflection point and the center of the reflecting surface of the reflecting element.

15. The optical scanning device according to claim 1, wherein: The following conditions are met: 0.9000<M Y / L Y <0.9700, Where L Y represents the distance in the main scanning direction between the on-axis deflection point of the first light beam in the deflection unit and the center of the surface of the optical element abutting against the holding member, and M Y The distance in the main scanning direction between the on-axis deflection point and the end of the reflective element closest to the optical element is represented.

16. The optical scanning device according to claim 1, wherein: The following conditions are met: 0.70<L t / L i <0.90, Where L t represents the distance in the main scanning section between the on-axis deflection point of the first light beam in the deflection unit and the center of the surface of the optical element abutting the holding member, and L i represents the distance between the first light source and the on-axis deflection point in a direction parallel to the optical axis of the optical element.

17. The optical scanning device according to claim 1, wherein: The optical element has an incident surface which is a diffractive surface.

18. The optical scanning device according to claim 1, further comprising a second imaging optical system, a third imaging optical system, and a fourth imaging optical system, wherein the second imaging optical system, the third imaging optical system, and the fourth imaging optical system are configured to guide the second light beam, the third light beam, and the fourth light beam deflected by the deflection unit to a second scanned surface, a third scanned surface, and a fourth scanned surface, respectively. in, the deflection unit is configured to deflect the second light beam, the third light beam, and the fourth light beam, respectively, to scan the second scanned surface, the third scanned surface, and the fourth scanned surface in the main scanning direction, wherein the first light beam and the second light beam are incident on a first deflection surface of the deflection unit at different angles relative to the main scanning section in the sub-scan section, and The third light beam and the fourth light beam are incident on the second deflection surface of the deflection unit at different angles from each other in the sub-scan section with respect to the main-scan section.

19. An image forming apparatus comprising: The optical scanning device according to any one of claims 1 to 18; a developing unit configured to develop the electrostatic latent image formed on the first scanned surface by the light scanning device into a toner image; a transfer unit configured to transfer the developed toner image onto a transfer material; as well as A fixing unit is configured to fix the transferred toner image to the transfer material.

20. An image forming device, comprising: The optical scanning device according to any one of claims 1 to 18; as well as A printer controller is configured to convert a signal output from an external device into image data to input the image data to the light scanning device.

Images