JP2002023085A - Optical scanning device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts, to facilitate the mounting of parts, to set an optical spot in a desired shape and to reduce the fluctuation of a spot diameter between image heights in an optical scanning device which optically scans a plurality of faces to be scanned by using a common optical deflector. SOLUTION: In the optical scanning device where the optical deflector 5 deflects luminous flux from at least one light source whose light intensity can be modulated, scanning/image-forming optical systems 6A, 7A, 6B and 7B converge deflected luminous flux toward the faces to be scanned 9A and 9B and the optical spot is formed on the face to be scanned so as to perform optical scanning, a plurality of faces to be scanned 9A and 9B, which are optically scanned, are arranged in parallel across the common optical deflector 5, the optical deflector 5 deflects luminous flux by the rotation of a deflection reflection face. The rotary axis of the deflection reflection face is parallel to the deflection reflection face. The two faces to be scanned 9A and 9B, which sandwich the reflection 5, are optically scanned by luminous flux from one light source 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical scanning device and an image forming apparatus.

[0002]

2. Description of the Related Art To realize high-speed image formation, "a plurality of scanning surfaces are arranged with a common optical deflector interposed therebetween, and light beams incident from both sides of the optical deflector are simultaneously deflected by the optical deflector. An optical scanning device that optically scans each surface to be scanned at the same time has been proposed (Japanese Patent Application Laid-Open No. H11-125784). If, for example, four scanned surfaces are simultaneously scanned by such optical scanning, exposure of image components of four colors of yellow, magenta, cyan, and black constituting a color image can be simultaneously realized. However, the invention described in the above publication requires a number of light sources equal to the number of scanned surfaces to be optically scanned, an optical system necessary for light beam processing such as a driving circuit for light source modulation, a coupling lens, a cylinder lens, and the like. This requires the same number of light sources as the number of light sources, which not only leads to a significant increase in cost, but also makes it difficult to mount the device while avoiding interference between components. In addition, since a "polygonal polygon mirror having six or more surfaces" is used as the optical deflector, there is a problem that the optical characteristics are greatly deteriorated due to the effect of sag. In order to solve the above problem, a pyramidal mirror having a single deflecting reflection surface inclined at 45 degrees with respect to the rotation axis is used, a light beam is incident from the rotation axis direction, and a plurality of scan surfaces are scanned with a single light source. An optical scanning device capable of optical scanning has been proposed (JP-A-11-249042).
No.).

In the case of this method, there are the following problems. That is, the shape of the light spot formed on the surface to be scanned is not necessarily circular, and an elliptical shape that is long in the main scanning direction or the sub-scanning direction is often used. The shape setting of the light spot is performed by the aperture shape of the aperture for performing so-called beam shaping. For example, to form an elliptical light spot that is long in the main scanning direction, a “rectangular or elliptical shape that is long in the main scanning direction” is often used as the aperture shape of the aperture. When the light beam is deflected by using a pyramidal mirror as described above, the action in the longitudinal direction of the aperture opening shape becomes
Since the light beam gradually rotates with the deflection of the light beam, the shape of the light spot formed on the surface to be scanned also rotates with the image height.
For this reason, the spot diameter of the light spot changes continuously with the image height in both the main scanning direction and the sub-scanning direction. Therefore, in the optical scanning device described in the above-mentioned Japanese Patent Application Laid-Open No. H11-249042, the shape of the light spot is changed by using an “aperture having a circular opening shape” as used in the embodiment of the publication. It is common to make a circle,
It is difficult to independently set the spot diameter in the main scanning direction / sub-scanning direction.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in an optical scanning device that optically scans a plurality of surfaces to be scanned by using a common optical deflector, it is possible to reduce the number of parts and reduce the cost. It is another object of the present invention to facilitate mounting of components, set a light spot having a desired shape, and reduce a spot diameter variation between image heights.

[0005]

According to a first aspect of the present invention, there is provided an optical scanning apparatus, comprising: "a light beam from at least one light source capable of light intensity modulation is deflected by an optical deflector, and the deflected light beam is received by a scanning image forming optical system. An optical scanning device that performs light scanning by condensing light toward a scanning surface and forming an optical spot on the surface to be scanned ”has the following features. That is, the plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with the common optical deflector interposed therebetween. The optical deflector deflects a light beam by rotating the deflecting / reflecting surface. The axis of rotation of the deflecting / reflecting surface is parallel to the deflecting / reflecting surface, and the light beam from one light source “2 It is configured to optically scan one “scanned surface”. The term “parallel” in this specification is not mathematically strictly parallel, but means parallel within an allowable mechanical error. As the "light source capable of light intensity modulation", various gas lasers, solid-state lasers, and LEDs can be used. The most common and preferable one is a "semiconductor laser". Since at least one “light source” is used, one or more light sources can be used. In this case, a “semiconductor laser array” having two or more light emitting units can be used as a light source. When two or more light sources are used, at least one of them is used for “optically scanning two surfaces to be scanned”. Another light source can be used for optical scanning of another scanned surface, or the two scanned surfaces may be optically scanned by a so-called multi-beam scanning method. The “scanned surface” is actually a photosensitive surface of a “photosensitive medium” such as a photoconductive photoconductor. "A plurality of scanned surfaces are arranged in parallel with each other across a common optical deflector" means that there is at least one scanned surface on each side of the optical deflector, and the scanning lines of the plurality of scanned surfaces are provided. (Lines optically scanned by the light spot) are substantially parallel. The same applies to the following description.

In the optical scanning device according to the first aspect of the present invention, "a light beam emitted from one light source and traveling toward the optical deflector in order to scan two scanned surfaces" is transmitted from the direction of the rotation axis of the optical deflector. It can be seen that "parallel to two scanned surfaces" (claim 2). An optical scanning device according to a third aspect of the present invention is arranged such that "a light beam from at least two light sources capable of light intensity modulation is deflected by an optical deflector, and each deflected light beam is condensed toward a different scanning surface by a scanning image forming optical system. The optical scanning device performs optical scanning by forming an optical spot on each surface to be scanned, and has the following features. That is, the plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with the common optical deflector interposed therebetween. The optical deflector deflects a light beam by rotating the deflecting / reflecting surface. The rotation axis of the deflecting / reflecting surface is parallel to the deflecting / reflecting surface, and each light beam from the two light sources is "light deflected". By optically scanning the “two scanned surfaces sandwiching the container”, four scanned surfaces are optically scanned by two light sources. In the optical scanning device according to the third aspect, "two light sources for optically scanning the four scanned surfaces" can be "arranged on the same side with respect to the optical deflector" (claim 4). , "Disposed on the opposite side to the optical deflector" (claim 5). Claim 4 or 5
In the optical scanning device described above, “each light beam from the two light sources for optically scanning the four scanned surfaces” is deflected in a direction “parallel to the scanned surface” when viewed from the direction of the rotation axis of the optical deflector. It can be configured to be incident on the vessel. In the optical scanning device according to the fourth, fifth or sixth aspect, each light beam traveling from two light sources for optically scanning the four scanned surfaces to the optical deflector is "spatially separated in the sub-scanning direction". (Claim 7).

In the optical scanning device according to any one of the first to seventh aspects of the present invention, the optical deflector includes “a deflecting reflection surface having one
As the surface, the one in which the rotation axis (of the deflecting / reflecting surface) and the deflecting / reflecting surface coincide with each other "can be used so that" the light flux from the light source side is incident toward the rotating axis "(claim 8). The expression "the rotation axis coincides with the deflecting reflection surface" means that "the rotation axis is located within the deflecting reflection surface" within an allowable error range. Other examples of the optical deflector include a rotating two-sided mirror and a mirror having three or more deflecting and reflecting surfaces.
A rotating polygon mirror of about four "can also be used. The optical scanning device according to claim 9, wherein "a light beam from at least one light source capable of light intensity modulation is deflected by an optical deflector, and the deflected light beam is converged toward a surface to be scanned by a scanning image forming optical system; An optical scanning device that performs optical scanning by forming an optical spot on a surface to be scanned ”has the following features. That is, the plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with the common optical deflector interposed therebetween. The light deflector is of a type that deflects a light beam by rotating a deflecting and reflecting surface, and has two deflecting and reflecting surfaces parallel to the rotation axis. It is configured to optically scan the two sandwiched surfaces to be scanned. In the optical scanning device according to the ninth aspect, "a light beam emitted from one light source and traveling toward the optical deflector in order to scan two scanned surfaces" is viewed from the direction of the rotation axis of the optical deflector. The two scanning surfaces can be parallel to each other (claim 10). An optical scanning device according to claim 11, wherein "a light beam from at least two light sources capable of light intensity modulation is deflected by an optical deflector, and each deflected light beam is condensed by a scanning image forming optical system toward a different scanning surface. The optical scanning device performs optical scanning by forming an optical spot on each surface to be scanned, and has the following features. That is, a plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with a common optical deflector interposed therebetween. The light deflector is of a type that deflects a light beam by rotating a deflecting and reflecting surface, and has two deflecting and reflecting surfaces parallel to the rotation axis. By optically scanning the “two interposed scanning surfaces”, four scanning surfaces are optically scanned by two light sources.

In the optical scanning device according to the eleventh aspect, "two light sources for optically scanning the four scanning surfaces" are arranged on the same side with respect to the optical deflector.
In addition, it is also possible to arrange it on the opposite side to the optical deflector (claim 13). In the optical scanning device according to the twelfth or thirteenth aspect, "each light beam from two light sources toward the optical deflector" can be spatially separated in the sub-scanning direction (claim 14). Further, in the optical scanning device according to the thirteenth aspect, "each light beam traveling from the two light sources toward the optical deflector is spatially separated in the sub-scanning direction, and the scanning image forming optical systems corresponding to the opposed light beams are mutually connected. Shift in the main scanning direction "(claim 15). Claim 11
In the optical scanning device according to any one of (1) to (15), "the light beams from the two light sources for optically scanning the four scanning surfaces are viewed from the direction of the rotation axis of the optical deflector. Incident parallel to the optical deflector ”(claim 16). The optical scanning device according to any one of claims 9 to 16, wherein "the scanning image forming optical system corresponding to the light beam from each light source is incident on the optical deflector with respect to the rotation center of the optical deflector. To be shifted to the side to perform "(claim 17). In the optical scanning device according to any one of claims 9 to 17, “a light beam from each light source can be incident toward the rotation center of the optical deflector” (claim 1).
8).

An image forming apparatus according to the present invention forms a latent image on each photosensitive surface by performing optical scanning on a photosensitive surface of a plurality of photosensitive media by an optical scanning device, and visualizes each latent image to obtain an image. An optical scanning device for optically scanning the photosensitive surfaces of a plurality of photosensitive media, wherein the optical scanning device according to any one of claims 1 to 18 is used.
9). Using a "photoconductive photoreceptor" as each photosensitive medium, an electrostatic latent image formed by uniform charging of each photosensitive surface and optical scanning by an optical scanning device is visualized as a toner image. (Claim 20). In this case, the toner image obtained on each photosensitive surface is transferred and fixed on a common “sheet-shaped recording medium (transfer paper or OHP sheet (plastic sheet for overhead projector))”.
If the electrostatic line images formed on the respective photosensitive surfaces are visualized with toners of different colors, a two-color image, a multi-color image or a color image can be formed. In the image forming apparatus according to the nineteenth aspect, a silver halide film may be used as each photosensitive medium. In this case, the latent image formed on each photosensitive medium can be visualized by a normal silver halide photographic development technique. Such an image forming apparatus can be realized, for example, as a color plate making apparatus. For example, using the optical scanning device according to the third aspect, it is possible to simultaneously perform optical scanning on four photosensitive media to simultaneously make "red plate, blue plate, green plate, and black plate". The image forming apparatus according to the twentieth aspect can be implemented as a color copying apparatus, a color printer, a color plotter, a color facsimile, or a copying apparatus, a printer, a plotter, a facsimile, or the like for forming a two-color or multicolor image.

[0010]

Embodiments of the present invention will be described below. In FIG. 1, reference numeral 1 denotes a semiconductor laser as a “light source”,
Reference numeral 2 denotes a coupling lens, reference numeral 3 denotes an aperture for beam shaping, reference numeral 4 denotes a cylindrical lens, and reference numeral 5
Is a rotating single-sided mirror as an "optical deflector", reference numerals 6A and 6B are first scanning lenses, reference numerals 7A and 7B are second scanning lenses, reference numerals 8A and 8B are dust-proof glasses, and reference numerals 9A and 9B are scanning surfaces. Shown respectively. The divergent luminous flux emitted from the semiconductor laser 1 is converted by the coupling lens 2 into a “luminous flux form suitable for the subsequent optical system”. The converted light beam can be a “weak convergent light beam”, a “weak divergent light beam”, or a “parallel light beam”. Hereinafter, for the sake of specificity, it is assumed that the light beam from the semiconductor laser 1 is converted into a “parallel light beam” by the coupling lens 2. The light beam emitted from the coupling lens 2 passes through the opening of the beam shaping aperture 3 in order to obtain a stable spot diameter, and is beam-shaped. The opening shape of the aperture 3 is, for example, “rectangle or ellipse”,
The diameters in the main scanning direction and the sub scanning direction are set according to the spot shape required for the light spot on the surface to be scanned. Therefore, the opening diameter may be different between the main scanning direction and the sub-scanning direction. The beam-shaped light beam is then condensed by the cylindrical lens 4 in the sub-scanning direction (a direction perpendicular to the drawing) and formed as a “line image long in the main scanning direction” at the position of the deflecting reflection surface of the rotary single-sided mirror 5. Image. The rotary single-sided mirror 5 as an “optical deflector” has a single deflecting and reflecting surface, and its rotation axis coincides with the deflecting and reflecting surface. As shown in FIG. 1, the light beam incident on the rotary single-sided mirror 5 from the light source side is incident “in parallel with the surfaces 9A and 9B to be scanned” toward the rotation axis of the rotary polygonal mirror 5. The incident light beam is incident on the rotary single-sided mirror 5 in a plane perpendicular to the rotation axis of the rotary single-sided mirror 5 (a plane parallel to the drawing).

The light beam reflected by the deflecting / reflecting surface of the rotary single-sided mirror 5 is deflected at a constant angular velocity in the above-mentioned "plane orthogonal to the rotation axis of the rotary single-sided mirror" together with the rotation of the rotary single-sided mirror 5. .
When the deflecting / reflecting surface of the rotary single-sided mirror 5 faces the "right side in the figure", the deflecting light beam passes through the first scanning lens 6A and the second scanning lens 7A sequentially, and the (deflecting housing for housing the optical scanning device) A light spot is formed on the surface 9A to be scanned by the action of the first scanning lens 6A and the second scanning lens 7A. First scanning lens 6
A and the second scanning lens 7A constitute a “scanning image forming optical system” for a deflected light beam that optically scans the surface 9A to be scanned, and what is called f
θ lens. Therefore, optical scanning of the scanned surface 9A is performed at a constant speed. When the deflecting reflection surface of the rotary single-sided mirror 5 faces “left side in the drawing”, the deflecting light beam is
B and the second scanning lens 7B are sequentially transmitted, and are emitted from the dust-proof glass 8B provided in the housing, and a light spot is formed on the surface 9B to be scanned by the action of the first scanning lens 6B and the second scanning lens 7B. Form. Accordingly, the first scanning lens 6B and the second scanning lens 7B constitute a “scanning optical system” for a deflected light beam that optically scans the surface 9B to be scanned.
is a θ lens, and optical scanning of the scanned surface 9B is performed at a constant speed.

[0012]

EXAMPLE A specific example relating to the embodiment of FIG. 1 will be described. Example 1 As the semiconductor laser 1 as a light source, an emission wavelength: 780
The emitted divergent light beam is converted into a parallel light beam by the coupling lens 2. As the cylindrical lens 4, the focal length in the sub-scanning direction: 70.6
is provided at a position of 70.6 mm from the rotation axis position of the rotary single-sided mirror 5 toward the light source. Therefore, the light beam from the light source side forms an image as a long line image in the main scanning direction on the rotation axis position of the rotary single-sided mirror 5 (coinciding with the deflecting reflection surface),
Along with the rotation of the rotary single-sided mirror 5 at a constant speed, it is deflected at a constant angular velocity in a plane perpendicular to the rotation axis. The lens data after the rotary single-sided mirror (optical deflector) is shown. The first scanning lenses 6A and 6B and the second scanning lenses 7A and 7B have the same configuration, and each of the first scanning lenses 6A and 6B pass through the rotation axis of the rotary single-sided mirror 5 and pass through the scanning surface 9A,
9B are arranged mirror-symmetrically with respect to the plane parallel to 9B. Therefore, the following data is common to the left and right optical systems of the rotary single-sided mirror 5. Counting from the deflecting / reflecting surface of the rotary polygon mirror 5 toward the surface to be scanned, the surface numbers are 1 (incident side surface of the first scanning lens) to 5 (surface to be scanned). The paraxial radius of curvature of these surfaces in the main scanning direction in the main scanning direction is “Rm”, and the paraxial radius of curvature in the sub-scanning direction at the optical axis position is “Rs (0)”. The surface spacing is represented by “X”, and the refractive index of the material of each lens is represented by “N”. The unit of the dimension having the length dimension is “mm”. Surface number Rm Rs (0) XN Remarks Deflective reflective surface 1.7 ∞ 51.7 Rotating single-sided mirror 1 ** -312.6 -312.6 31.4 1.52395 First scanning lens 2 ** -83.0 -83.0 78.0 3 * -500 -47.7 3.5 1.52395 Second scanning lens 4 -1000 -23.38 143.7 5---Surface to be scanned.

In FIG. 1, dust-proof glass 8A is disposed between the second scanning lens 7A and the surface 9A to be scanned and between the second scanning lens 7B and the surface 9B to be scanned.
8B are both “central wall thickness: 1.9 mm, refractive index: 1.51”
116 parallel flat glass ". The surfaces (surface numbers 1 and 2) marked with “**” are “coaxial aspherical surfaces” and have a well-known formula: X = (Y ＾ 2) / R {1 + √ {1- (1 + K) · ( Y / R) {2} + A ・ Y ＾ 4 + B ・ Y ＾ 6 + C ・ Y ＾ 8 + D ・ Y ＾ 10 (1), paraxial radius of curvature: R (= Rm = Rs (0)), coefficient: K , A, B, C, and D to specify the shape. Surface of surface number: 1 K = 2.667, A = 1.79E-07, B = −
1.08E-12, C = -3.18E-14, D =
3.74E-18 Surface number: 2 Surface K = 0.02, A = 2.50E-07, B = 9.
61E-12, C = 4.54E-15, D = -3.0
3E-18 In Expression (1), “＾” represents “power”, for example, “Y ＾ 6” represents “Y ⁶ ”. In the above description of the coefficient, for example, “2.50E-07” is changed to “2.50 × 10
^-7 ". The same applies to the following description. "*"
The surface indicated by the symbol (surface number 3) has a non-arc shape in the main scanning direction and a shape in which the radius of curvature in the sub-scanning direction changes continuously in the main scanning direction. The non-circular shape in the main scanning direction can be calculated by a known formula: X = (Y ＾ 2) / Rm {1 + {{1- (1 + K) * (Y / Rm) ｍ2} + A YＡ4 + B ・ Y ＾ 6 + C ＋ Y ＾ 8 + D · Y ＾ 10 (2) where paraxial radius of curvature: Rm, coefficients: K, A, B,
The shape is specified by giving C and D.

The radius of curvature in the sub-scanning direction is represented by a coordinate radius in the main scanning direction with the optical axis position as the origin: Y, and a radius of curvature using Y as a variable, and a polynomial: Rs (Y) = Rs (0 ) + Σb _j · Y ＾ j (j = 1, 2, 3,...) (3), and the curvature radius in the sub-scanning direction at the optical axis position shown above: Rs (0) and the coefficient: b _j Give and identify. Surface number: 3 Non-arc shape in main scanning direction K = -71.73, A = 4.33E-08, B =-
5.97E-13, C = -1.28E-16, D =
5.73E-21 “Change in the main scanning direction” of the radius of curvature in the sub-scanning direction b2 = 1.63E-03, b4 = −2.32E-0
7, b6 = 1.60E-11, b8 = −5.61E−
16, b10 = 2.18E-20, b12 = -1.2
5E-24 Coefficient: b _j All other coefficients are “0”. “Aberration Diagrams on Scanned Surfaces 9A and 9B” Regarding Example 1
Is shown in FIG. Both the curvature of field and the constant velocity characteristics are well corrected. By appropriately setting the shape of the aperture in the aperture 3, the spot diameter of the light spot on the surfaces 9A and 9B to be scanned can be set as the central image height: 51 μm in the main scanning direction, 68 μm in the sub-scanning direction.
m Peripheral image height (± 150 mm) Main scanning direction: 51 μm, sub-scanning direction: 64 μm, “spot with small deviation due to image height and stable small diameter” can be realized. The spot diameter is defined by “1 / e ＾ 2 of the maximum intensity”.

In the embodiment described with reference to FIG. 1 and the optical scanning device of the first embodiment, the light beam from at least one light source 1 capable of light intensity modulation is deflected by the light deflector 5, and the deflected light beam To the scanning imaging optical systems 6A, 7A, 6B, 7B
In the optical scanning device that performs light scanning by condensing light toward the scanned surfaces 9A and 9B and forming a light spot on the scanned surface, a plurality of scanned surfaces 9A and 9B to be optically scanned are shared. The light deflector 5 is arranged in parallel with each other with the light deflector 5 interposed therebetween. The light deflector 5 deflects the light beam by rotating the deflecting / reflecting surface, and the rotation axis of the deflecting / reflecting surface is parallel to the deflecting / reflecting surface. And a light beam from one light source 1 causes an optical deflector 5
Are configured to optically scan the two scanned surfaces 9A and 9B sandwiching the two surfaces (claim 1).
In order to scan A and 9B, a light beam emitted from one light source 1 and traveling toward the optical deflector 5 is scanned by two light beams when viewed from the direction of the rotation axis of the optical deflector 5 (a direction orthogonal to the drawing). Face 9
A, 9B are parallel (claim 2). The light deflector 5 has one deflecting / reflecting surface, the rotation axis and the deflecting / reflection surface coincide, and the light beam from the light source 1 is incident toward the rotation axis of the light deflector 5 (claim 8). The optical deflector (rotating single-sided mirror 5)
Since the deflecting reflection surface and its rotation axis are parallel to each other, the shape of the light spot on the surfaces to be scanned 9A and 9B does not change depending on the image height, and the primary and secondary surfaces are set according to the setting of the aperture shape of the aperture. A desired spot diameter can be obtained in both the scanning direction. In addition, the deflecting surface of the light deflector 5 and the rotation axis coincide with each other, and the light beam traveling from the light source 1 to the light deflector 5 is
When viewed from the direction of the rotation axis, the light is incident toward the rotation axis of the optical deflector in parallel to the two scanning surfaces 9A and 9B, so that the optical system of the optical system on both the left and right sides of the rotary single-sided mirror 5 in FIG. The characteristics can be made the same, and the images formed on each of the scanned surfaces 9A and 9B are transferred to the same sheet-shaped recording medium and are superimposed upon each other. ) Can be effectively reduced or prevented. Further, since the scannable range does not shift between the scanned surfaces 9A and 9B, a "wide effective writing width" can be realized.

FIG. 2 shows another embodiment. As in FIG. 1, reference numeral 1 denotes a semiconductor laser as a "light source", reference numeral 2 denotes a coupling lens, reference numeral 3 denotes an aperture, reference numeral 4 denotes a cylindrical lens, and reference numeral 5 denotes a rotating single-sided mirror as an optical deflector. Reference numeral 1 'denotes a semiconductor laser as a "light source", reference numeral 2' denotes a coupling lens, reference numeral 3 'denotes an aperture, and reference numeral 4' denotes a cylindrical lens. The divergent light beam emitted from the semiconductor laser 1 is converted into a parallel light beam by the coupling lens 2,
The beam is shaped by the aperture 3 and is incident on the rotary single-sided mirror 5 through the cylindrical lens 4, and is imaged as a long line image in the main scanning direction at the position of the deflecting and reflecting surface of the rotary single-sided mirror 5 by the action of the cylindrical lens 4. Is done. The light beam from the semiconductor laser 1 is incident parallel to the surfaces to be scanned 9A and 9B toward the rotation axis position of the rotary single-sided mirror 5. A light beam emitted from the semiconductor laser 1 and deflected by the rotary single-sided mirror 5 passes through a scanning imaging optical system constituted by a first scanning lens 6A and a second scanning lens 7A and a dustproof glass 8A. A light spot is formed on the scanned surface 9A,
The scanned surface 9A is scanned. On the other hand, a light beam emitted from the semiconductor laser 1 and deflected by the rotary single-sided mirror 5 passes through a scanning imaging optical system constituted by a first scanning lens 6B and a second scanning lens 7B and a dustproof glass 8B. Thus, a light spot is formed on the scanned surface 9B, and the scanned surface 9B is scanned. Therefore, in FIG. 2, the “system portion for optically scanning the scanned surfaces 9A and 9B with the light beam from the semiconductor laser 1” is completely the same as the embodiment of FIG. Optical system.

In the embodiment shown in FIG. 2, another system similar to the above-described system is provided.
That is, in the direction orthogonal to the drawing, the first scanning lens 6
A, 6B so that the first scanning lenses 6A ′, 6A overlap each other.
B 'is provided, the second scanning lenses 7A', 7B 'are provided so as to overlap the second scanning lenses 7A, 7B, and the dustproof glass 8 is provided so as to overlap the dustproof glasses 8A, 8B.
A ′, 8B ′ are provided, and the scanned surfaces 9A ′, 9B ′ are provided so as to overlap the scanned surfaces 9A, 9B. An actual optical arrangement in a portion from the rotary single-sided mirror 5 to each surface to be scanned is as shown in FIG. 8, for example. In FIG. 8, reference numerals m1 to m4 and m1 'to m4' indicate "a plane mirror for bending the optical path". Returning to FIG. 2, the divergent light beam emitted from the semiconductor laser 1 'is converted into a parallel light beam by a coupling lens 2', beam-shaped by an aperture 3 ', and rotated through a cylindrical lens 4'. 5 and is formed as a linear image long in the main scanning direction at the position of the deflecting reflection surface of the rotary single-sided mirror 5 by the action of the cylindrical lens 4 '. The light beam from the semiconductor laser 1 ′ is incident parallel to the scanning surfaces 9 A and 9 B toward the rotation axis position of the rotary single-sided mirror 5. On the other hand, a light beam emitted from the semiconductor laser 1 'and deflected by the rotary single-sided mirror 5 has a scanning image forming optical system constituted by a first scanning lens 6A' and a second scanning lens 7A 'and a dustproof glass 8A'. Then, a light spot is formed on the scanned surface 9A 'through the above-mentioned steps, and the scanned surface 9A' is scanned. On the other hand, a light beam emitted from the semiconductor laser 1 'and deflected by the rotary single-sided mirror 5 has a scanning image forming optical system constituted by a first scanning lens 6B' and a second scanning lens 7B 'and a dustproof glass. A light spot is formed on the scanned surface 9B 'through the scanning surface 8B', and the scanned surface 9B 'is scanned.

In FIG. 2, the optical system provided on the optical path from the semiconductor laser 1 ′ to the rotary single-sided mirror 5 is “an optical system provided on the optical path from the semiconductor laser 1 to the rotary single-sided mirror 5”.
And the first scanning lens 6A '
The scanning image forming optical system composed of the first scanning lens 6A and the second scanning lens 7A ′ has the same configuration as the “scanning image forming optical system composed of the first scanning lens 6A and the second scanning lens 7A”. The scanning image forming optical system constituted by the lens 6B ′ and the second scanning lens 7B ′ is “a first scanning lens 6B and a second scanning lens
B has the same configuration as the “scanning image forming optical system composed of B”. The dustproof glasses 8A, 8A ', 8B, 8B' have the same configuration. The optical system provided in the optical path from the semiconductor laser 1 'to the rotary single-sided mirror 5 is, like the optical system provided in the optical path from the semiconductor laser 1 to the rotary single-sided mirror 5, in a plane parallel to the drawing of FIG. Form an optical path. However, the optical path of the optical system provided in the optical path from the semiconductor laser 1 'to the rotary single-sided mirror 5 and the optical path of the optical system provided in the optical path from the semiconductor laser 1 to the rotary single-sided mirror 5 are in the sub-scanning direction ( FIG.
In the direction perpendicular to the drawing). That is, FIG.
The optical scanning device according to the embodiment described above uses a light deflector 5 for converting light beams from at least two light sources 1 and 1 ′ capable of light intensity modulation.
, And converge each deflected light beam toward different scanning surfaces 9A, 9A ', 9B, 9B' by the scanning image forming optical system, and form a light spot on each scanning surface to perform optical scanning. In the optical scanning device, a plurality of scanned surfaces 9A, 9A ', 9B, 9B' to be optically scanned are arranged in parallel with each other with a common optical deflector 5 interposed therebetween. In which the light beam is deflected by the rotation of the light source, the rotation axis of the deflecting / reflecting surface is parallel to the deflecting / reflecting surface, and the light beams from the two light sources 1 and 1 ′ sandwich the light deflector 5 respectively. By optically scanning the two surfaces to be scanned, four light sources 9A, 9A ', 9B, 9 by the two light sources 1, 1'.
B 'is configured to be optically scanned (claim 3).

The four scanning surfaces 9A, 9A ', 9
The two light sources 1 and 1 'for optically scanning B and 9B' are on opposite sides of the optical deflector 5 (claim 5).
Each light beam from 1 ′ is incident on the light deflector 5 parallel to the scanned surfaces 9A, 9A ′, 9B, 9B ′ when viewed from the direction of the rotation axis of the light deflector 5 (claim 6). Two light sources 1,
Each light beam traveling from 1 'to the light deflector 5 is spatially separated in the sub-scanning direction. The optical deflector 5 has one deflecting / reflecting surface, and the rotation axis coincides with the deflecting / reflecting surface (claim 8). In short, the embodiment shown in FIG. 2 is based on “rotating the same optical system as that of the embodiment shown in FIG. 1 by 180 degrees around the rotation axis of the rotary single-sided mirror 5,
Are arranged at a predetermined distance from each other in the sub-scanning direction. " Of course, a specific optical arrangement is, for example, as shown in FIG. Since these two sets of optical systems are exactly the same, they can be embodied by using two sets shown in the first embodiment. As a modification of the embodiment shown in FIG. 2, an optical system arranged in the optical path from the semiconductor laser 1 'to the rotary single-sided mirror 5, that is, the semiconductor laser 1', the coupling lens 2 ', and the aperture 3' The cylindrical lens 4 ′ may be arranged on the same side as the “optical system arranged on the optical path from the semiconductor laser 1 to the rotary single-sided mirror 5” and so as to overlap in the sub-scanning direction. That is, two light sources 1, 1 'for optically scanning the four scanned surfaces 9A, 9A', 9B, 9B 'may be arranged "on the same side as the optical deflector 5". 4). In this case, the two sets of optical systems overlap in the sub-scanning direction, as shown in FIG. 1 (each optical element overlaps in a direction orthogonal to the drawing). As in the embodiment of FIG. 1, the deflecting / reflecting surface of the rotary single-sided mirror 5 coincides with the rotation axis, and the light flux from each of the light sources 1 and 1 ′ is viewed from the direction of the rotation axis of the optical deflector 5. Scanning plane 9
A, 9A ', 9B, and 9B' are incident toward the rotation axis in parallel, so that the optical characteristics of the left and right optical systems of the rotary single-sided mirror 5 in FIG. 9
Effectively reduce image displacement (appearing as so-called "color misregistration" in color image formation) when images formed on A ', 9B, 9B' are transferred onto the same sheet-shaped recording medium and superimposed. Can be prevented. Also, the scanned surface 9
A, 9A ', 9B, 9B' does not deviate in the scannable range, so that a "wide effective writing width" can be realized. Although the embodiment shown in FIGS. 1 and 2 uses the cylindrical lens 4 (and 4 ′), the rotating single-sided mirror 5 used as an optical deflector does not suffer from “plane tilt”. It is not necessary to add the surface tilt correction function, the cylindrical lens 4 (and 4 ′) may be omitted, and a corresponding scanning image forming optical system (coaxially symmetric optical system) may be provided.

FIG. 3 shows another embodiment of the present invention. In order to avoid complication, the same symbols as those in FIG. In this embodiment, the "optical deflector" is a type that deflects a light beam by rotating the deflecting and reflecting surface, and has two deflecting and reflecting surfaces parallel to the rotation axis. . The differences from the optical scanning device of the embodiment of FIG. 1 are as follows.
That is, the “optical deflector” in the embodiment of FIG.
The plane mirror 50. The rotary two-sided mirror 50 is “a mirror having both surfaces of a parallel plate as deflection reflection surfaces”, and the center of the parallel plate in the thickness direction coincides with the rotation axis. Therefore, the two deflecting and reflecting surfaces are shifted with respect to the rotation axis, and a so-called "sag" occurs in the optical deflector. Therefore, the “scanning optical system configured by the first scanning lens 6A and the second scanning lens 7A” and the “scanning optical system configured by the first scanning lens 6B and the second scanning lens 7B” are both used. It is shifted in the main scanning direction (vertical direction in the figure) with respect to the rotation axis of the rotating two-sided mirror so that the sag is equal for each scanning image forming optical system. Other parts are the same as in the embodiment of FIG.

[0021]

Embodiment 2 Semiconductor laser 1, coupling lens 2,
The aperture 3 and the cylindrical lens 4 are the same as those in the first embodiment. The light beam incident on the rotating two-sided mirror 50 from the light source side is parallel to the scanned surfaces 9A and 9B, and
The light is incident toward the rotation axis of the rotating two-sided mirror 50. In FIG. 3, since the optical arrangement on both the left and right sides of the rotary two-sided mirror 50 is symmetrical with respect to the rotary two-sided mirror 50, the optical characteristics are left-right symmetric. Since the rotation axis of the rotary two-sided mirror 50 and the deflecting reflection surface are spatially separated by 1.5 mm, in order to reduce the effect of sag, each scanning and image forming optical system is moved with respect to the rotation axis by " The side where the light beam enters (upper in FIG. 3) "
In the main scanning direction. Data on the optical path from the rotating two-sided mirror 50 to the surface to be scanned is shown according to the first embodiment. Surface number Rm Rs (0) XN Remarks Deflective reflective surface 1.7 ∞ 51.7 Rotating two-sided mirror 1 ** -312.6 -312.6 31.4 1.52395 First scan lens 2 ** -83.0 -83.0 78.0 3 * -500.0 -47.7 3.5 1.52395 2-scan lens 4 -1000 -23.38 143.7 5---Scanned surface Since the first scan lens and the second scan lens are the same as those in the first embodiment, the upper radius of curvature is "paraxial value".
Only shown. The dustproof glasses 8A and 8B arranged between the surface number: 4 and the surface number: 5 are parallel flat glass having a center thickness of 1.9 mm and a refractive index of 1.51116. Considering the amount of deviation between the rotation axis of the rotary two-sided mirror 50 and the deflecting reflection surface: 1.5 mm, the interval from the cylindrical lens 4 to the rotation axis of the deflecting reflection surface is 1.5 mm to 70.6 mm in the first embodiment. 72.1 mm. Scanned surface 9
FIG. 6 shows aberration diagrams on A and 9B. Both the curvature of field and the constant velocity characteristics are well corrected.

The optical scanning device according to the embodiment and the embodiment 2 shown in FIG. 3 deflects a light beam from at least one light source 1 capable of light intensity modulation by an optical deflector 50, and scans the deflected light beam into a scanning image. The optical systems 6A, 7A, 6B, and 7B converge light toward the surfaces to be scanned 9A and 9B, form optical spots on the surfaces to be scanned 9A and 9B, and perform optical scanning in an optical scanning device. A plurality of surfaces to be scanned 9A and 9B are arranged in parallel with each other with a common optical deflector 50 interposed therebetween, and the optical deflector 50 deflects a light beam by rotating a deflecting reflection surface, The light deflector 50 has two deflecting / reflecting surfaces parallel to the rotation axis, and receives a light beam from one light source 1.
Are configured to optically scan the two scanning surfaces 9A and 9B sandwiching the scanning surface (claim 9).
In order to scan A and 9B, a light beam emitted from one light source 1 and traveling to the optical deflector 50 is parallel to the two scanned surfaces 9A and 9B when viewed from the direction of the rotation axis of the optical deflector 50. (Claim 10). Further, the light beam from the light source 1 enters the rotation center of the optical deflector 50 (claim 18). The embodiment of FIG. 3 is different from the embodiment of FIG.
The number of deflecting and reflecting surfaces is doubled, and "double the high-speed writing" is possible. A light beam traveling from the light source 1 to the light deflector 50 is viewed from the direction of the rotation axis of the light deflector 50 so that the two scanning surfaces 9
A and 9B are directed toward the rotation axis in parallel to FIG.
, The optical characteristics on both the left and right sides of the rotary single-sided mirror 50 can be made the same, and the images formed on each of the scanned surfaces 9A and 9B are transferred to the same sheet-shaped recording medium and superimposed on each other. So-called "color shift" in image formation and color image formation
) Can be effectively reduced or prevented. Further, since the scannable range does not shift between the scanned surfaces 9A and 9B, a "wide effective writing width" can be realized.

FIG. 4 shows another embodiment of the present invention. In order to avoid complication, the same reference numerals as those in FIG. 4 is different from the embodiment shown in FIG. 2 in the following points.
That is, the “optical deflector” in the embodiment of FIG.
This is a plane mirror 50 (the same as that shown in the embodiment and the second embodiment in FIG. 3). "The first scanning lens 6A,
Scanning imaging optical system constituted by second scanning lens 7A "
And the “scanning optical system constituted by the first scanning lens 6B and the second scanning lens 7B” in the main scanning direction (vertical direction in the drawing) with respect to the rotation axis of the rotating dihedral mirror. To the side so that the sag is equal for each of the scanning image forming optical systems.

Further, two sets of scanning image forming optical systems ("first scanning lens 6A ',
"Scanning imaging optical system constituted by second scanning lens 7A '", "first scanning lens 6B', second scanning lens 7B '"
Is formed in the main scanning direction (vertical direction in the figure) with respect to the rotation axis of the rotating two-sided mirror.
It is shifted to the semiconductor laser 1 'side so that sag is equal for each scanning image forming optical system. Therefore, as shown in FIG. 4, the first scanning lenses 6A and 6A ', 6B and 6B', the second scanning lenses 7A and 7A ', and 7B and 7B' are slightly shifted from each other in the main scanning direction. The other points are the same as the embodiment of FIG. First scanning lens 6A and 6A ', 6B and 6B', second scanning lens 7
A and 7A 'and 7B and 7B' are identical to each other, and can be realized by using the one shown in the first embodiment. The two sets of optical systems for making the light beam incident on the rotary two-sided mirror 50 are also identical to each other. Since it is the same as that shown in the first embodiment, it can be realized by using the one shown in the first embodiment. Since the aberration diagrams on the scanned surfaces 9A and 9B are the same as those in the second embodiment, they are as shown in FIG. The aberration diagrams on the scanned surfaces 9A ′ and 9B ′ are as shown in FIG. 7 (the aberration diagram of FIG. 6 is inverted upside down). On each surface to be scanned, both the curvature of field and the constant velocity characteristics are well corrected. In the embodiment of FIG. 4, the four scanned surfaces 9A, 9B, 9A ', 9B' are provided.
In the scanning image forming optical system corresponding to each light beam, it is necessary to make the “angle of view on the side where the light beam enters the optical deflector 50” wider than the angle of view on the opposite side.

The optical scanning device according to the embodiment shown in FIG.
Light beams from at least two light sources 1, 1 'capable of light intensity modulation are deflected by an optical deflector 50, and each deflected light beam is scanned by a scanning imaging optical system, and the surfaces to be scanned 9A, 9B, 9A',
In an optical scanning device that performs light scanning by forming a light spot on each scanned surface by condensing light toward 9B ′, a plurality of scanned surfaces 9A, 9B, 9A ′, 9B ′ to be optically scanned are formed. Are arranged in parallel with each other with a common optical deflector 50 interposed therebetween. The optical deflector 50 is of a type that deflects a light beam by rotation of a deflecting / reflecting surface. Surface, and each light flux from the two light sources 1, 1 ′ is respectively
By optically scanning the two scanned surfaces sandwiching the optical deflector 50, the two light sources 1, 1 'provide four scanned surfaces 9A,
9B, 9A ', and 9B' are configured to be optically scanned (claim 11), and include four scanned surfaces 9A, 9B.
B, 9A ', 9B' two light sources 1 for optical scanning,
1 ′ is on the opposite side to the optical deflector 50 (claim 1).
3) Each light beam from the two light sources directed to the light deflector 50 is spatially separated in the sub-scanning direction (claim 14). Each light beam directed from the two light sources 1, 1 'to the light deflector 50 is The scanning imaging optical systems spatially separated in the sub-scanning direction and corresponding to the opposing light flux are shifted from each other in the main scanning direction. In addition, four scanning surfaces 9A, 9B,
Two light sources 1 and 1 'for optically scanning 9A' and 9B '
Are incident on the light deflector 50 in parallel with the scanning surfaces 9A, 9B, 9A ', 9B' when viewed from the direction of the rotation axis of the light deflector 50 (claim 16). further,
The scanning image forming optical system corresponding to the light beam from each of the light sources 1 and 1 'is shifted to the side where each light beam enters the light deflector 50 with respect to the rotation center of the light deflector 50. The light flux from each of the light sources 1 and 1 'enters the rotation center of the optical deflector 50 (claim 18).

As a modification of the embodiment shown in FIG. 4, an optical system arranged in the optical path from the semiconductor laser 1 'to the rotary two-sided mirror 50, that is, the semiconductor laser 1', the coupling lens 2 ', The aperture 3 ′ and the cylindrical lens 4 ′ may be arranged on the same side as the “optical system arranged on the optical path from the semiconductor laser 1 to the rotary single-sided mirror 5” and in the sub-scanning direction. . That is, two light sources 1, 1 'for optically scanning the four scanned surfaces 9A, 9A', 9B, 9B 'may be arranged "on the same side as the optical deflector 5". 12). In this case, the two sets of optical systems overlap in the sub-scanning direction, as shown in FIG. 3 (each optical element overlaps in a direction orthogonal to the drawing). In this case as well as in the embodiment of FIG.
The specific arrangement of each optical element in the sub-scanning direction is as shown in FIG. 8, for example. By using the rotating two-sided mirror 50, twice as fast writing can be performed as in the case of the embodiment of FIG. A light beam traveling from the light sources 1 and 1 'to the optical deflector 50 is viewed from the direction of the rotation axis of the optical deflector 50, and the two scanned surfaces 9A, 9A', 9B and 9
Since the light is incident toward the rotation axis in parallel to B ′, the optical characteristics on both the left and right sides of the rotary single-sided mirror 50 in FIG. 4 can be made the same, and the images formed on each surface to be scanned can be converted into the same sheet-shaped recording medium. This can effectively reduce or prevent an image shift (appearing as a so-called “color shift” in color image formation) when transferring and superimposing images.

In each of the embodiments described above, one light beam scans one surface to be scanned. However, a "multi-beam system" in which one light beam scans one surface to be scanned is adopted. Higher speed may be realized. Finally, an embodiment of the image forming apparatus will be described with reference to FIG. This image forming apparatus is a “color laser printer”. The color laser printer 100 includes photosensitive media 111R, 111G, 11
1B and 111K have a “photoconductive photoconductor formed in a cylindrical shape”. The photosensitive medium 111R (111G,
111B, 111K), charging rollers 112R (112G, 112B, 112K) as charging means,
A developing device 113R (113G, 113B, 113K) is provided. Photosensitive media 111R, 112G, 112
B, 112K, a common transfer belt 1
A corona charger 1 for transfer is provided on a portion of the inner circumference of the transfer belt 114 corresponding to each photosensitive medium.
14R, 114G, 114B and 114K are arranged. Photosensitive media 111R, 112G, 112B, 112K
Above the optical scanning device 117 is provided. The optical scanning device 117 may be configured by, for example, tandemly arranging two sets of the embodiment shown in FIG. 1 or the embodiment shown in FIG. 2 and 4 (for example,
8 (configured as a portion indicated by reference numeral 117 in FIG. 8). In FIG. 9, reference numeral 116 denotes a fixing device, and reference numeral P denotes a transfer sheet as a recording medium.

When an image is formed, photosensitive media 111R to 111K, which are photoconductive photosensitive members, are rotated clockwise at a constant speed, and the surfaces thereof are charged rollers 112R to 112K.
It is uniformly charged by K. The optical scanning device 117 writes a red component latent image corresponding to a red component image on the photosensitive medium 111R, and writes green, blue, and black corresponding to green, blue, and black component images on the photosensitive media 111G, 111B, and 111K, respectively. Write the component latent image. Each color component latent image written and formed is a so-called "negative latent image", and the image portion is exposed. In the case where the optical scanning device having the configuration as shown in FIG. 8 is used, the red component image and the black component image are written using the same light source, and the green component image and the blue component image Are written by the same light source. These color component latent images are respectively processed by the developing devices 113R to 113K into red. Green / blue /
Each of the photosensitive media 111R to 1R is reversely developed with black toner.
The toner images of the respective colors are formed on 13K. The transfer paper P is sequentially conveyed by a transfer belt 114 to a transfer position for each photosensitive medium, and the transfer corona charger 1 is transferred.
14R, 114G, 114B, and 114K, a red toner image and a photosensitive medium 111G are sequentially output from the photosensitive medium 111R.
, A blue toner image is transferred from the photosensitive medium 111B, and a black toner image is transferred from the photosensitive medium 111R. A “color image” is formed as a composite image of the toner images of each color transferred in this manner. As an optical scanning device,
By using a combination as shown in FIG. 1 or FIG. 3 or a combination as shown in FIG. 2 or FIG. 4, it is possible to effectively prevent the size deviation between the toner images of the respective colors. The transfer paper P on which the color image is formed in this manner is transferred to the fixing device 11.
At 6, the color image is fixed and discharged out of the apparatus. Each of the photosensitive media 111R to after the toner image is transferred
The surface of 111K is cleaned by a cleaning device (not shown) to remove residual toner, paper dust, and the like.

The above-described OHP sheet or the like can be used in place of the transfer paper P, and the transfer of the toner image can be performed via an “intermediate transfer medium” such as an intermediate transfer belt. Therefore, the image forming apparatus according to the embodiment shown in FIG. 9 performs optical scanning by the optical scanning device 117 on the photosensitive surfaces of the plurality of photosensitive media 111R to 111K to form a latent image for each photosensitive surface, and forms each latent image. 19. An image forming apparatus for visualizing and obtaining an image, wherein the optical scanning apparatus performs optical scanning of photosensitive surfaces of a plurality of photosensitive media 111R to 111K.
Wherein the photosensitive mediums 111R to 111K are photoconductive photoconductors, and a uniform charging of each photosensitive surface and an optical scanning device are provided. The electrostatic latent image formed by the light scanning is visualized as a toner image (claim 20).

[0030]

As described above, according to the present invention, a novel optical scanning device and a new image forming apparatus can be realized.
In the optical scanning device according to the present invention, since one light source is shared to perform optical scanning of two scanned surfaces, the number of components such as a drive circuit for modulating the light source, a coupling lens, a cylinder lens, and the like can be reduced, and a large number of components can be achieved. Cost reduction can be realized. Further, since the interference between the components is reduced, the mounting of the components is facilitated. In addition, since optical components from the light source to the optical deflector are common to different scanned surfaces, no wavelength difference occurs, and color shift due to chromatic aberration of magnification is eliminated. Coupling action,
Since the characteristics such as the optical axis deviation are the same, the difference in the optical characteristics on different scanned surfaces is small, and the color deviation can be reduced. Since the reflecting surface and the rotation axis are parallel, by setting the aperture diameter of the aperture independently in the main scanning direction and the sub-scanning direction, a desired spot diameter in the main and sub-scanning directions can be set, and the image of the spot diameter can be set. A light spot with a small height deviation can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating one embodiment of an optical scanning device.

FIG. 2 is a diagram for explaining another embodiment of the optical scanning device.

FIG. 3 is a diagram for explaining another embodiment of the optical scanning device.

FIG. 4 is a diagram for explaining still another embodiment of the optical scanning device.

FIG. 5 is a diagram illustrating optical characteristics on a scanned surface in the first embodiment.

FIG. 6 is a diagram illustrating optical characteristics on a surface to be scanned in a second embodiment.

FIG. 7 is a diagram showing optical characteristics on scanning surfaces 9A ′ and 9B ′ in a specific example related to the embodiment shown in FIG. 4;

FIG. 8 is a diagram showing an example of a specific optical arrangement after the optical deflector in the embodiment shown in FIGS. 2 and 4;

FIG. 9 is a diagram for explaining an embodiment of the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser (light source) 2 Coupling lens 3 Aperture 4 Cylindrical lens 5 Rotating single-sided mirror (optical deflector) 6A, 6B 1st scanning lens 7A, 7B 2nd scanning lens 9A, 9B Scanning surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C362 AA11 BA50 BA51 BA53 BA54 DA09 2H045 AA00 BA22 BA23 BA34 CA68 CB24 2H087 KA19 LA22 PA02 PA17 PB02 QA03 QA07 QA12 QA22 QA37 QA41 RA05 RA07 RA13 5C072 AA19 BA01 BA02 HA20

Claims (20)

[Claims] 1. A light beam from at least one light source capable of light intensity modulation is deflected by an optical deflector, and the deflected light beam is condensed toward a surface to be scanned by a scanning image forming optical system. In an optical scanning apparatus that performs optical scanning by forming an optical spot, a plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with a common optical deflector interposed therebetween, A method of deflecting a light beam by rotation of a surface, wherein the rotation axis of the deflecting / reflecting surface is parallel to the deflecting / reflecting surface, and two light beams from one light source sandwich the light deflector. An optical scanning device configured to optically scan a surface. 2. The optical scanning device according to claim 1, wherein in order to scan two surfaces to be scanned, a light beam emitted from one light source and traveling toward the optical deflector is directed from the direction of the rotation axis of the optical deflector. An optical scanning device, which is parallel to the two surfaces to be scanned. 3. A light beam from at least two light sources capable of light intensity modulation is deflected by an optical deflector, and each deflected light beam is condensed by a scanning imaging optical system toward a different surface to be scanned. In an optical scanning device that performs optical scanning by forming an optical spot on a surface, a plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with a common optical deflector interposed therebetween, and the optical deflector includes: A method of deflecting a light beam by rotation of a deflecting reflection surface, wherein a rotation axis of the deflecting reflection surface is parallel to a deflecting reflection surface, and light beams from two light sources respectively sandwich the light deflector. An optical scanning apparatus, wherein four scanning surfaces are optically scanned by two light sources by optically scanning two scanning surfaces. 4. The optical scanning device according to claim 3, wherein the two light sources for optically scanning the four surfaces to be scanned are on the same side with respect to the optical deflector. 5. The optical scanning device according to claim 3, wherein two light sources for optically scanning the four scanning surfaces are on opposite sides of the optical deflector. . 6. The optical scanning device according to claim 4, wherein each of the light beams from the two light sources for optically scanning the four surfaces to be scanned is viewed from the direction of the rotation axis of the optical deflector. An optical scanning device, wherein the light enters the optical deflector in parallel with a scanning surface. 7. The optical scanning device according to claim 4, wherein each light beam traveling from two light sources for optically scanning the four scanning surfaces to the optical deflector spatially in the sub-scanning direction. An optical scanning device, which is separated. 8. The optical scanning device according to claim 1, wherein the optical deflector has only one deflecting / reflecting surface, and a rotation axis coincides with the deflecting / reflecting surface. A light beam from a light source is incident toward the rotation axis. 9. A light beam from at least one light source capable of modulating light intensity is deflected by an optical deflector, and the deflected light beam is condensed toward a surface to be scanned by a scanning image forming optical system. In an optical scanning apparatus that performs optical scanning by forming an optical spot, a plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with a common optical deflector interposed therebetween, A method of deflecting a light beam by rotation of a surface, comprising two deflecting / reflecting surfaces parallel to the rotation axis, and two scanning surfaces sandwiching the light deflector by a light beam from one light source. An optical scanning device configured to optically scan the light. 10. The optical scanning device according to claim 9, wherein the light beam emitted from one light source and traveling toward the optical deflector is viewed from the direction of the rotation axis of the optical deflector in order to scan two surfaces to be scanned. And an optical scanning device parallel to the two surfaces to be scanned. 11. A light beam from at least two light sources capable of light intensity modulation is deflected by an optical deflector, and each deflected light beam is condensed by a scanning image forming optical system toward a different surface to be scanned. In an optical scanning device that performs optical scanning by forming an optical spot on a surface, a plurality of scanned surfaces to be optically scanned are arranged in parallel with each other with a common optical deflector interposed therebetween, and the optical deflector includes: This is a method of deflecting a light beam by rotation of a deflecting reflection surface, and has two deflecting reflection surfaces parallel to a rotation axis, and each light beam from two light sources sandwiches the light deflector. An optical scanning device, wherein four scanning surfaces are optically scanned by two light sources by optically scanning one scanning surface. 12. The optical scanning device according to claim 11, wherein the two light sources for optically scanning the four surfaces to be scanned are on the same side with respect to the optical deflector. 13. The optical scanning device according to claim 11, wherein two light sources for optically scanning the four scanning surfaces are on opposite sides with respect to the optical deflector. . 14. The optical scanning device according to claim 12, wherein each light beam traveling from two light sources for optically scanning the four scanning surfaces to the optical deflector is spatially separated in the sub-scanning direction. An optical scanning device, comprising: 15. The optical scanning device according to claim 13, wherein each light beam traveling from two light sources for optically scanning the four scanning surfaces to the light deflector is spatially separated in the sub-scanning direction, and An optical scanning device, wherein scanning optical systems corresponding to opposed light sources are shifted from each other in the main scanning direction. 16. The optical scanning device according to claim 11, wherein each light beam from two light sources for optically scanning the four scanning surfaces is directed in the direction of the rotation axis of the optical deflector. An optical scanning device, wherein the light is incident toward the optical deflector in parallel with the surface to be scanned. 17. The optical scanning device according to claim 9, wherein the scanning image forming optical system corresponding to the light beam from each light source is arranged such that each light beam is positioned with respect to the rotation center of the optical deflector. An optical scanning device, which is shifted to a side where light enters a light deflector. 18. The optical scanning device according to claim 9, wherein a light beam from each light source is incident toward a rotation center of the optical deflector. 19. An image forming apparatus for forming a latent image on each photosensitive surface by performing optical scanning on a photosensitive surface of a plurality of photosensitive media by an optical scanning device and visualizing each latent image to obtain an image. An image forming apparatus, comprising: the optical scanning device according to any one of claims 1 to 18 as an optical scanning device for optically scanning a photosensitive surface of a plurality of photosensitive media. 20. An image forming apparatus according to claim 19, wherein each photosensitive medium is a photoconductive photosensitive member, and an electrostatic latent image formed by uniform charging of each photosensitive surface and optical scanning by an optical scanning device. Is visualized as a toner image.