JP2010281869A - Light beam scanning optical system, optical scanning device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light beam scanning optical system, an optical scanning device and an image forming device, reducing the time of optical beam scanning control in regions other than an image writing region on a reflection surface of a rotary polygon mirror without the light beam scanning control's relying on a light beam or of increasing the ratio of occupation of the image writing region on the reflection surface of the rotary polygon mirror. <P>SOLUTION: The light beam scanning optical system which writes image information on a photoconductor 3 while detecting the writing start position of the image information by deflecting and scanning the light beam L1a from a light source 110 emitting the light beam L1a by a polygon mirror 120 and by detecting the light beam L1b from the polygon mirror 120 by a BD part 130, and the optical scanning device 1 and the image forming device D include a light source 140 for BD emitting a light beam L2a besides the light source 110. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light beam scanning optical system that can be applied to an image forming apparatus such as a digital copying machine or a laser printer. In particular, the light beam from a light source is deflected and scanned by a rotary polygon mirror to set the writing start position of image information. The present invention relates to a light beam scanning optical system, an optical scanning apparatus, and an image forming apparatus that write image information on a scanning target while being detected by a detection unit.

  This type of optical scanning device is conventionally mounted in an image forming apparatus such as a digital copying machine or a laser printer, and is widely used as an optical writing means in these image forming apparatuses.

  In an image forming apparatus equipped with this optical scanning device, for example, when an image is formed by an electrophotographic image forming process, the surface of an image carrier such as a photosensitive member acting as a scanned body is charged, and the charged area is set. Based on the image information, the optical scanning device deflects and scans the surface of the image carrier on the surface of the image carrier in the main scanning direction by a rotating polygon mirror (also called a polygon mirror) while modulating the light beam from the light source. A latent image is formed (written), and the electrostatic latent image is developed with a developer to form a toner image. The toner image is transferred to a transfer medium such as an intermediate transfer member or a recording material, and the transfer target is transferred. When the transfer body is an intermediate transfer body, it is further transferred and fixed on a recording material, and when the transfer body is a recording material, it is fixed as it is.

  In addition, in an image forming apparatus that requires high resolution and high printing speed of an image to be formed (printed), an optical scanning device can simultaneously write adjacent lines on the image carrier. A multi-beam type light source having a plurality of light emitting elements such as a semiconductor laser array may be used.

  In an optical scanning device, as light beam scanning control for controlling deflection scanning of a light beam, a light beam from a light source is normally incident on a reflecting surface of a rotating rotary polygon mirror and reflected by the reflecting surface to perform deflection scanning. The writing start position of the image information is detected by detecting the written light beam in a writing start position detection (Beam Detect: BD) unit.

  In addition, the output power of the light source varies depending on the individual light source, and the output power may change due to the heat generated by the light source itself. Therefore, as the light beam scanning control, the stabilization control for stabilizing the output power of the light source ( Auto Power Control (APC) may be performed.

  Therefore, on the reflecting surface that deflects and scans the light beam of the rotary polygon mirror, when performing BD area for detecting the writing start position of image information, image writing area for writing image information, and APC, Further, an APC area for performing APC is provided. The BD area and the APC area are provided in areas other than the image writing area so as not to affect the image.

  In order to increase the printing speed, it is possible to shorten the time of light beam scanning control in an area other than the image writing area including the BD area and the APC area, or to increase the ratio of the image writing area. It is desired.

  In particular, a light beam having a width wider than the width of one reflecting surface of the rotating polygon mirror in the rotation direction is incident on the reflecting surface of the rotating polygon mirror, and the reflecting surface is deflected as a substantial aperture (aperture) in the main scanning direction. In an optical scanning device that scans, so-called overfill type optical scanning device, since the ratio of the reflecting surface of the rotary polygon mirror to the image writing area is large, it is important to reduce the BD area and the APC area as much as possible. It has become.

  In this regard, in the conventional techniques described in Patent Document 1 and Patent Document 2, APC is performed in order with a plurality of light beams, or in the conventional technique described in Patent Document 3, a specific light source among a plurality of light sources is specified. BD is performed with one light source.

JP 2006-69205 A JP 2006-315278 A JP 2006-126714 A

  However, in any of the conventional techniques described above, since the light beam from the light source is used as the light beam for detecting the writing start position of the image information, the light beam scanning control depends on the light beam from the light source. Resulting in.

  That is, the light source not only emits light for writing image information, but also emits light for detecting the writing start position of the image information, so that the light source in the area other than the image writing area on the reflecting surface of the rotary polygon mirror. The light beam scanning control time becomes longer, or the ratio of the image writing area on the reflecting surface of the rotary polygon mirror becomes smaller.

  This is particularly noticeable in an overfill type optical scanning apparatus in which the ratio of the reflecting surface of the rotary polygon mirror to the image writing area is large.

  Therefore, the present invention shortens the time of the light beam scanning control in an area other than the image writing area on the reflecting surface of the rotary polygon mirror, or does not depend on the light beam from the light source. It is an object of the present invention to provide a light beam scanning optical system, an optical scanning device, and an image forming apparatus capable of increasing the ratio of the image writing area on the reflecting surface of the polygon mirror.

  In order to solve the above-described problems, the present invention provides a scanning target while detecting a writing start position of image information by a writing start position detecting unit by deflecting and scanning the light beam from a light source that emits a light beam by a rotary polygon mirror. A light beam scanning optical system for writing image information on a body, wherein a light source for writing start position detection for emitting a light beam is provided in addition to the light source. . The present invention also provides an optical scanning device comprising the light beam scanning optical system according to the present invention. The present invention also provides an image forming apparatus comprising the optical scanning device according to the present invention.

  In the present invention, the term “light source” simply refers to a light source for writing image information.

  In the present invention, stabilization control (APC) of the output power of the light source may be performed.

  In the light beam scanning optical system, the optical scanning apparatus, and the image forming apparatus according to the present invention, the detection of the writing start position of the image information is performed by rotating the light beam from the writing start position detecting light source provided in addition to the light source. The writing start position detector detects a light beam incident on the reflecting surface of the rotating polygon mirror and reflected and deflected by the reflecting surface.

  Thus, according to the present invention, since the write start position detecting light source is provided in addition to the light source, the light beam scanning control for controlling the deflection scanning of the light beam depends on the light beam from the light source. Never do. Therefore, the light emission for detecting the writing start position of the image information by the writing start position detecting light source is not limited to the light emission timing of the light source, that is, other than the image writing area on the reflecting surface of the rotary polygon mirror. It is not limited to the light emission timing in the area, but can be performed arbitrarily at any time. Thereby, the time of the light beam scanning control in the area other than the image writing area on the reflecting surface of the rotating polygon mirror is shortened, or the ratio of the image writing area in the reflecting surface of the rotating polygon mirror is increased. Can do.

  This is particularly effective in an overfill type optical scanning apparatus that occupies a large proportion of the image writing area on the reflecting surface of the rotary polygon mirror.

  In the present invention, the light beam from the write start position detecting light source and the light beam from the light source may be incident on different reflecting surfaces of the rotary polygon mirror. It is preferable that the light beam from the light source and the light beam from the light source enter the same reflecting surface of the rotary polygon mirror.

  In this specific matter, since the light beam from the write start position detection light source and the light beam from the light source are incident on the same reflecting surface of the rotating polygon mirror, the rotating polygon mirror has different reflecting surfaces. Compared to the case of incidence, it becomes possible to detect the writing start position of the image information with high accuracy.

  In the present invention, the light source may be provided with a plurality of light emitting elements. The light source for writing start position detection may be provided with at least one light emitting element. In this case, the light source can be, for example, a multi-beam light source having a plurality of light emitting elements such as a semiconductor laser array. By doing so, it is possible to simultaneously write adjacent lines on the image carrier. In addition, a single light emitting element may be provided in the writing start position detecting light source. In this case, it is possible to detect a writing start position of image information by the light beams from the plurality of light emitting elements of the light source using the light beam from the single light emitting element. In the light source for writing start position detection, a light emitting element may be provided corresponding to a plurality of light emitting elements of the light source.

  In the present invention, it is possible to exemplify an embodiment in which the light emitting element of the light source for detecting the writing start position is arranged close to the light emitting element of the light source.

  In this specific matter, since the light emitting element of the write start position detecting light source is disposed close to the light emitting element of the light source, the write start position detecting light source and the light source are integrated (for example, made into one chip). Thus, the apparatus configuration can be made compact.

  In the present invention, examples of the light beam from the light source include those having a wavelength in the wavelength region for writing. In this case, the light beam emitted from the write start position detection light source can be exemplified by a light beam having a wavelength in a write start position detection wavelength region different from the write wavelength region.

  As the wavelength region for writing, from the viewpoint of improving the resolution, for example, a region having a relatively short wavelength of blue wavelength to violet wavelength (specifically, about 400 nm to 500 nm) can be exemplified. The write start position detection wavelength region includes a wavelength region that is a predetermined wavelength away from the write wavelength region, such as an infrared wavelength to red wavelength (specifically, about 600 nm to 800 nm) region. Can do.

  In this specific matter, since the writing wavelength region and the writing start position detecting wavelength region are different, it is possible to easily distinguish the light beam from the light source and the light beam from the writing start position detecting light source. it can.

  For example, it comprises wavelength separation means for reflecting the light beam in the writing start position detecting wavelength region while passing the light beam in the writing wavelength region, and the wavelength separating means includes the light source and the writing start position. The aspect provided in the optical path of the light beam from the light source for a detection can be mentioned.

  In this specific matter, since the wavelength separation unit is provided on the optical path of the light beam from the light source and the write start position detection light source, the write start from the write start position detection light source is performed in the wavelength separation unit. Only the light beam in the wavelength region for position detection can be reflected, and the light beam in the wavelength region for writing from the light source can be transmitted. As a result, even if the light beam from the light source and the light beam from the write start position detection light source have substantially the same (very close) optical path, the light beam from the light source and the write start position detection light source The light beam can be easily separated.

  In the present invention, it is preferable that a light absorber that absorbs the light beam in the wavelength region for writing that has passed through the wavelength separation means is provided.

  In this specific matter, by absorbing the light beam in the wavelength region for writing that has passed through the wavelength separation unit by the light absorber, the light beam that has passed through the wavelength separation unit is, for example, irradiated on the scanned object. Irradiation to an extra area such as an area that does not need to be effectively prevented.

  The wavelength separation means may be any one as long as it passes the light beam in the writing wavelength region and reflects the light beam in the writing start position detecting wavelength region. A dichroic mirror can be illustrated.

  In the present invention, the light source for writing start position detection includes a first deflection scanning surface indicating a scanning locus of the light beam from the light source for writing start position detection by the deflection scanning with the rotary polygon mirror. A mode in which the beam is arranged so as to form an angle with respect to the second deflection scanning plane showing the scanning locus by the deflection scanning with the rotary polygon mirror can be exemplified.

  In this specific matter, since the first deflection scanning surface forms an angle with respect to the second deflection scanning surface, a light beam at the time of writing image information, for example, when performing the stabilization control, It is possible to sufficiently suppress the light beam during the stabilization control from entering the writing start position detecting unit, and thereby arranging the writing start position detecting light source and the writing start position detecting unit in the vicinity of the rotary polygon mirror. Is possible.

  As described above, according to the light beam scanning optical system, the optical scanning device, and the image forming apparatus according to the present invention, in addition to the light source, the light source for writing start position detection is provided, so that the light beam scanning is performed. The control does not depend on the light beam from the light source. Therefore, the light emission for detecting the writing start position of the image information by the writing start position detecting light source is not limited to the light emission timing of the light source. That is, the light emission timing is not limited to an area other than the image writing area on the reflecting surface of the rotary polygon mirror, and can be arbitrarily performed at any time. Thereby, the time of the light beam scanning control in the area other than the image writing area on the reflecting surface of the rotating polygon mirror is shortened, or the ratio of the image writing area in the reflecting surface of the rotating polygon mirror is increased. Can do.

1 is a perspective view schematically showing an optical scanning device including a light beam scanning optical system according to a first embodiment of the present invention. It is a schematic diagram which shows schematically a light source and a light source for writing start position detection. It is a figure which shows an example of each area | region in the reflective surface which carries out deflection scanning of the light beam of a polygon mirror. It is a perspective view which shows schematically the optical scanning device provided with the light beam scanning optical system which concerns on 2nd Embodiment of this invention. It is a perspective view which shows roughly the optical scanning device provided with the light beam scanning optical system which concerns on 3rd Embodiment of this invention. FIG. 6 is a schematic diagram schematically showing a light beam incident state and a light beam reflection state on a reflection surface of a polygon mirror in the optical scanning device shown in FIG. 5. FIG. 7A is a diagram illustrating a timing chart of image writing control and light beam scanning control in the Nth line and the N + 1th line, and FIG. 9A is a diagram illustrating an example of a timing chart in a conventional configuration, and FIG. These are figures which show an example of the timing chart in the structure of 1st Embodiment to 3rd Embodiment. FIG. 7A is a diagram illustrating a timing chart of image writing control and light beam scanning control in the Nth line and the N + 1th line, and FIG. 9A is a diagram illustrating an example of a timing chart in a conventional configuration, and FIG. These are figures which show the other example of the timing chart in the structure of 1st Embodiment to 3rd Embodiment. It is sectional drawing which shows schematically the image forming apparatus to which the optical scanning device of 1st Embodiment to 3rd Embodiment is applied.

  Embodiments according to the present invention will be described below with reference to the drawings. The following embodiments are examples embodying the present invention, and are not of a nature that limits the technical scope of the present invention.

(First embodiment)
FIG. 1 is a perspective view schematically showing an optical scanning device 1 (1a) including a light beam scanning optical system according to the first embodiment of the present invention. FIG. 1 also shows a photoconductor 3 that acts as a scanned body. The same applies to FIGS. 4 and 5 of the second and third embodiments described later.

  The optical scanning device 1 (1a) shown in FIG. 1 writes image information by deflecting and scanning a light source 110 that emits light beams L1a and L1b and the light beams L1a and L1b from the light source 110 onto the surface 3a of the photoreceptor 3. A rotating polygon mirror (hereinafter referred to as a polygon mirror) 120 and a writing start position detecting (hereinafter referred to as BD) unit 130 for detecting a writing start position of image information are provided.

  The optical scanning device 1 (1a) deflects and scans the light beam L1a from the light source 110 by the polygon mirror 120, and the light beam L1b from the polygon mirror 120 is detected by the BD unit 130 to thereby start writing image information. Image information is written on the surface 3a of the photoreceptor 3 while detecting the above.

  In addition to the light source 110, the optical scanning device 1 (1a) is provided with a BD light source 140 that emits light beams L2a and L2b.

  FIG. 2 is a schematic diagram schematically showing the light source 110 and the BD light source 140.

  As shown in FIG. 2, in the first embodiment, the light source 110 is a multi-beam type. Here, the light source 110 is provided with a semiconductor laser array including two semiconductor laser elements LD1 and LD2 such as a laser diode.

  Here, the BD light source 140 is provided with a single semiconductor laser element LD3 such as a laser diode.

  Further, the semiconductor laser element LD3 of the BD light source 140 is disposed in proximity to the two semiconductor laser elements LD1 and LD2 of the light source 110. In other words, the two semiconductor laser elements LD1, LD2 and the semiconductor laser element LD3 constitute a semiconductor laser array composed of three semiconductor laser elements LD1, LD2, LD3. That is, here, the BD light source 140 and the light source 110 are integrated, and the light source 110 and the BD light source 140 are integrated into one chip.

  As shown in FIG. 2, two light beams La1 and La1 are emitted from the light source 110, but are shown by a single line in FIG. The two light beams La1 and La1 are simply referred to as a light beam La1 and will be described below.

  As shown in FIG. 1, the polygon mirror 120 has a plurality of reflecting surfaces 121, and is rotated at a constant rotational speed in a predetermined rotational direction (in the direction of arrow F in the figure) around an axis by a motor driving unit (not shown). It is designed to be driven. The polygon mirror 120 is configured such that the light beam L1a from the light source 110 and the light beam L2a from the BD light source 140 are incident on one reflecting surface 121.

  That is, the light beam L2a from the BD light source 140 and the light beam L1a from the light source 110 are incident on the same reflecting surface 120 of the polygon mirror 120. However, the present invention is not limited to this, and the BD light source 140 and the light source 110 may be provided independently. Further, the light beam L2a from the BD light source 140 and the light beam L1a from the light source 110 may be incident on different reflecting surfaces 120 of the polygon mirror 120. Further, the light beam L2a and the light beam L1a may be incident on the same reflecting surface 120 at different incident angles in the main scanning direction.

  Here, the light beams L1a and L2a on the side incident on the reflecting surface 121 of the polygon mirror 120 are hereinafter referred to as incident beams L1a and L2a, and the light beam L1b on the side reflected on the reflecting surface 121 of the polygon mirror 120 is referred to. , L2b are hereinafter referred to as outgoing beams L1b, L2b.

  The BD unit 130 includes a semiconductor optical sensor (here, a photodiode) 131 and a BD reflection mirror 132 that reflects the outgoing beam L2b from the reflection surface 121 of the polygon mirror 120 and guides it to the semiconductor optical sensor 131.

  In the semiconductor optical sensor 131, the incident beam L2a from the BD light source 140 is incident on the reflecting surface 121 of the rotating polygon mirror 120, reflected from the reflecting surface 121, deflected and scanned, and further reflected by the BD reflecting mirror 132. The emitted beam L2b is incident. Thereby, the semiconductor optical sensor 131 can detect the timing at which the outgoing beam L2b is incident.

  The BD reflection mirror 132 is provided on the optical path of the outgoing beams L1b and L2b reflected from the light source 110 and the BD light source 140 through the polygon mirror 120.

  Various optical components are disposed in the incident beam optical path 150a from the light source 110 and the BD light source 140 to the polygon mirror 120 and in the outgoing beam optical path 160a from the polygon mirror 120 to the surface 3a of the photoreceptor 3. .

  Here, the optical component arranged in the incident beam optical path 150a is referred to as the incident optical system 150, and the optical component arranged in the outgoing beam optical path 160a is referred to as the outgoing optical system 160.

  The incident optical system 150 guides incident beams L1a and L2a emitted from the light source 110 and the BD light source 140 to the polygon mirror 120. The output optical system 160 guides the output beam L1b reflected from the light source 110 through the reflection surface 121 of the polygon mirror 120 to the surface 3a of the photosensitive member 3, and the reflection surface of the polygon mirror 120 from the light source 140 for BD. The outgoing beam L <b> 2 b reflected through 121 is guided to the BD unit 130.

  The incident optical system 150 includes a collimating lens 151, an aperture plate 152, a cylindrical lens 153, and a bending mirror 154.

  The collimating lens 151, the aperture plate 152, the cylindrical lens 153, and the bending mirror 154 are arranged in this order in the incident light beam path 150a from the light source for BD 140 and the light source 110 toward the polygon mirror 120.

  The collimating lens 151 is for converting incident beams L1a and L2a emitted from the light source 110 and the BD light source 140 into parallel beams. The opening plate 152 is configured by a plate-like member having a rectangular opening at a substantially central portion. The cylindrical lens 153 corrects the incident beams L1a and L2a from the aperture plate 152 so as to converge only in the sub-scanning direction. The bending mirror 154 guides the incident beams L 1 a and L 2 a from the cylindrical lens 153 toward the reflecting surface 121 of the polygon mirror 120.

  The exit optical system 160 includes fθ lenses 161 and 162 and a folding mirror 163.

  The fθ lenses 161 and 162 and the folding mirror 163 are arranged in this order in the outgoing beam optical path 160a from the polygon mirror 120 toward the photosensitive member 3, and the beam spot P formed on the surface 3a of the photosensitive member 3 is It has a predetermined size and acts to scan the surface 3a of the photoreceptor 3 at a constant speed.

  The fθ lens corrects the outgoing beam L1b, which is reflected by the reflecting surface 121 of the polygon mirror 120 and moves at an equal angular velocity, so as to move on the surface 3a of the photosensitive drum 3 at an equal velocity.

  The folding mirror 163 has both functions of a long cylindrical lens that corrects the surface tilt of the polygon mirror 120 and a reflection folding mirror. In this example, the folding mirror 163 is used as a cylindrical lens and a reflection folding mirror. However, instead of the folding mirror 163, a cylindrical lens and a reflection folding mirror may be provided independently.

  In the optical scanning device 1 (1a) having such a configuration, the incident optical system 150 uses the incident beams L1a and L2a from the light source 110 and the BD light source 140 in the height direction (rotation axis direction) of the reflecting surface 121 of the polygon mirror 120. ) Can irradiate the central area. On the other hand, the outgoing optical system 160 can guide the outgoing beam L1b that passes through the fθ lenses 161 and 162 from the light source 110 through the polygon mirror 120 and is reflected by the folding mirror 163 to the surface 3a of the photosensitive member 3, and BD. The outgoing beam L2b passing through the fθ lenses 161 and 162 through the polygon mirror 120 from the light source 140 for use can be guided to the BD unit 130.

  The outgoing beam L1b reflected from the light source 110 via the reflecting surface 121 of the polygon mirror 120 reaches the surface 3a of the photoreceptor 3 through different optical paths in the rotating direction F depending on the position of the reflecting surface 121 in the rotating direction F.

  Now, among the outgoing beams L1b reaching the surface 3a of the photoconductor 3, the width d used for image formation on the surface 3a of the photoconductor 3, that is, the outgoing beam L1b is set for each main scanning line of the surface 3a of the photoconductor 3. In the optical scanning device 1 (1a), the outgoing beam L1b is periodically generated for each main scanning line on the surface 3a of the photoreceptor 3 in the main scanning beam region L1c. On the other hand, different places are scanned at regular intervals in the moving direction of the surface 3a of the rotating photosensitive member 3 while scanning.

  FIG. 3 is a diagram illustrating an example of each region on the reflection surface 121 that deflects and scans the incident beams L1a and L2a of the polygon mirror 120. FIG.

  As shown in FIG. 3, the reflection surface 121 of the polygon mirror 120 is provided with an image writing area γ for writing image information and an area X other than the image writing area γ. In this example, in the region X other than the image writing region γ, a BD region α for detecting the writing start position of image information and stabilization control (hereinafter referred to as APC) for stabilizing the output power of the light source 110 are performed. An APC region β for performing is provided. In this example, the BD region α is provided in a region X other than the image writing region γ. For example, the incident surface L2a of the BD light source 140 and the incident beam L1a of the light source 110 are different reflection surfaces of the polygon mirror 120. If the configuration is such that the outgoing beam L2b of the BD light source 140 does not affect the image, such as a configuration in which the light is incident on 120, it can be arbitrarily provided.

(Second Embodiment)
FIG. 4 is a perspective view schematically showing an optical scanning device 1 (1b) including a light beam scanning optical system according to the second embodiment of the present invention.

  In FIG. 4, the same components as those of the optical scanning device 1 (1a) of the first embodiment shown in FIG.

  The optical scanning device 1 (1b) shown in FIG. 4 is provided with a BD portion 130a in place of the BD portion 130 of the optical scanning device 1 (1a) shown in FIG. ) And substantially the same configuration.

  The BD unit 130a includes a semiconductor optical sensor (here, a photodiode) 131 and wavelength separation means (here, a dichroic mirror 133).

  In the first embodiment described above, the incident beam L1a and the outgoing beam L1b of the light source 110 and the incident beam L2a and the outgoing beam L2b of the BD light source 140 are not particularly limited in wavelength, but in the second embodiment, The peak wavelengths of the incident beam L1a and the outgoing beam L1b of the light source 110 are different from the peak wavelengths of the incident beam L2a and the outgoing beam L2b of the BD light source 140.

  That is, from the viewpoint of improving the resolution, the two semiconductor laser elements LD1 and LD2 of the light source 110 are here an incident beam L1a having a peak wavelength in a writing wavelength region of a relatively short blue wavelength to violet wavelength, and The emitted beam L1b is emitted.

  Here, the semiconductor laser element LD3 of the BD light source 140 emits an incident beam L2a and an outgoing beam L2b having a peak wavelength in the wavelength region for detecting the write start position from the infrared wavelength to the red wavelength. .

  The dichroic mirror 133 passes the light beam in the writing wavelength region and reflects the light beam in the writing start position detecting wavelength region.

  The dichroic mirror 133 is provided on the optical path of the outgoing beams L1b and L2b reflected from the light source 110 and the BD light source 140 via the polygon mirror 120 (here, the optical path other than the main scanning beam region L1c). The dichroic mirror 133 reflects the outgoing beam L2b in the writing start position detection wavelength region from the reflecting surface 121 of the polygon mirror 120 and guides it to the semiconductor optical sensor 131, while writing wavelength region from the reflecting surface 121 of the polygon mirror 120. The outgoing beam L1b is transmitted.

  In the second embodiment, a light absorber 134 that further absorbs the outgoing beam L1b in the wavelength region for writing that has passed through the dichroic mirror 133 is provided. The light absorber 134 absorbs at least light having a wavelength in the wavelength region for writing, and examples thereof include a black light absorber.

(Third embodiment)
FIG. 5 is a perspective view schematically showing an optical scanning device 1 (1c) including a light beam scanning optical system according to the third embodiment of the present invention. 6 schematically shows the incident state of the incident beams L1a and L2a and the reflected state of the outgoing beams L1b and L2b on the reflecting surface 121 of the polygon mirror 120 in the optical scanning device 1 (1c) shown in FIG. FIG.

  5 and 6, the same components as those in the optical scanning device 1 (1a) according to the first embodiment shown in FIG.

  The optical scanning device 1 (1c) shown in FIG. 5 and FIG. 6 is provided with the light source 110 and the BD light source 140 of the optical scanning device 1 (1a) shown in FIG. The optical scanning device 1 (1a) shown in FIG. 1 has substantially the same configuration except that the BD unit 130b is provided.

  In the BD light source 140, the first deflection scanning surface Q1 indicating the scanning locus of the outgoing beam L2b by the deflection scanning of the reflection surface 121 of the polygon mirror 120 of the incident beam L2a from the BD light source 140 is incident from the light source 110. The beam L1a is arranged so as to form an angle θ (see FIG. 6) with respect to the second deflection scanning surface Q2 indicating the scanning locus of the outgoing beam L1b by the deflection scanning on the reflection surface 121 of the polygon mirror 120.

  The BD portion 130b is provided with a semiconductor photosensor (here, a photodiode) 131.

  In the semiconductor optical sensor 131, the incident beam L2a from the BD light source 140 is incident on the reflecting surface 121 of the rotating polygon mirror 120, and the outgoing beam L2b reflected and deflected from the reflecting surface 121 is incident. It has become. Thereby, the semiconductor optical sensor 131 can detect the timing at which the outgoing beam L2b is incident.

(From the first embodiment to the third embodiment)
In the optical scanning device 1 (1a to 1c) of the first to third embodiments, light for controlling image writing to write image information on the surface 3a of the photoreceptor 3 and deflection scanning of the emitted beams L1b and L2b. A control unit (not shown) that performs beam scanning control is provided. The control unit includes a processing device such as a CPU and a storage unit including a memory such as a ROM and a RAM, and the processing device loads a control program stored in advance in the ROM of the storage unit onto the RAM of the storage unit. By executing this, image writing control and light beam scanning control are performed.

  As the light beam scanning control, the control unit detects the writing start position of the image information by detecting the emitted beam L2b of the BD light source 140 provided in addition to the light source 110 by the BD unit 130. .

  The control unit performs APC as light beam scanning control. The APC uses two semiconductors based on detection results from a light amount sensor (for example, a semiconductor optical sensor such as a photodiode) that detects the light amounts of incident beams L1a and L1a from the two semiconductor laser elements LD1 and LD2 in the light source 110. The light amounts of the laser elements LD1 and LD2 are controlled.

  Therefore, on the reflecting surface 121 of the polygon mirror 120, as shown in FIG. 3, a BD area α, an APC area β, and an image writing area γ are provided.

  According to the optical scanning device 1 (1a to 1c) of the first to third embodiments described above, the BD light source 140 is provided in addition to the light source 110, thereby detecting the writing start position of image information. The light beam scanning control does not depend on the outgoing beam L1b of the light source 110. Therefore, BD light emission by the BD light source 140 is not limited to the light emission timing of the light source 110, that is, not limited to the light emission timing in the region X other than the image writing region γ on the reflection surface 121 of the polygon mirror 120. Can be done arbitrarily at any time. Thereby, the time of the light beam scanning control in the region X other than the image writing region γ on the reflecting surface 121 of the polygon mirror 120 is shortened, or the ratio of the image writing region γ on the reflecting surface 121 of the polygon mirror 120 is increased. can do. This will be further described with reference to the timing charts of FIGS.

<Explanation of timing chart>
FIG. 7 and FIG. 8 are timing charts of image writing control and light beam scanning control in the Nth line and the (N + 1) th line. N is an integer of 1 or more.

  FIG. 7A and FIG. 8A show an example of a timing chart in the conventional configuration. FIG. 7B shows an example of a timing chart in the configuration of the first embodiment to the third embodiment, and FIG. 8B is a timing in the configuration of the first embodiment to the third embodiment. The other example of the chart is shown.

  In the conventional configuration shown in FIGS. 7A and 8A, the timing of writing image information (image signal) on the surface 3a of the photoreceptor 3 is detected by the outgoing beam L1b of the light source 110. . For this purpose, the first semiconductor laser element LD1 of the light source 110 emits light for BD.

  Further, in order to adjust the light output of the two semiconductor laser elements LD1 and LD2 of the light source 110, light emission for APC is performed for each line for a predetermined time.

  Here, of the two semiconductor laser elements LD1 and LD2 of the light source 110, not only the emission beam L1b of the first semiconductor laser element LD1 used as the light beam for BD but also the second light that does not emit light for BD. When the APC outgoing beam L1b of the semiconductor laser element LD2 enters the semiconductor optical sensor 131 of the BD unit 130, the semiconductor optical sensor 131 of the BD unit 130 sensitizes the outgoing beam L1b of the first semiconductor laser element LD1. The writing timing of the image information on the surface 3a of the body 3 may be erroneously detected.

  For this reason, from the viewpoint of setting a distance so that the outgoing beam L1b of the second semiconductor laser element LD2 that does not emit light for BD does not enter the semiconductor optical sensor 131 of the BD section 130, the second semiconductor laser element LD2 A predetermined interval needs to be provided between the APC emission and the BD emission of the first semiconductor laser element LD1.

  In contrast, in the first to third embodiments, as described above, since the BD light source 140 is provided in addition to the light source 110, the light beam scanning control in the region X other than the image writing region γ is performed. Can be shortened, or the proportion of the image writing area γ can be increased. In particular, in the second embodiment and the third embodiment, since the outgoing beam L1b of the light source 110 does not enter the semiconductor optical sensor 131 of the BD unit 130, it is shown in FIGS. 7B and 8B. Thus, it is effective when the timing of APC and the timing of BD overlap.

  For example, the APC end timing in the configuration of the first to third embodiments shown in FIG. 7B can be made earlier by Y time than the APC end timing in the conventional configuration shown in FIG. Thereby, the time required for the light beam scanning control in the region X other than the image writing region γ on the reflecting surface 121 of the polygon mirror 120 can be shortened.

  That is, in the first to third embodiments shown in FIG. 7B, from the viewpoint of preventing the light emission for the APC of the light source 110 from entering the surface 3a of the photoreceptor 3 and disturbing the image. The shortening of the time required for the light beam scanning control in the region X other than the image writing region γ is used to increase the margin of the region X other than the image writing region γ.

  Further, the scanning time for one line in the configuration of the first to third embodiments shown in FIG. 8B is earlier than the scanning time of one line in the conventional configuration shown in FIG. 8A by Z time. Accordingly, the rotation speed of the polygon mirror 120 can be increased and / or the width of the reflection surface of the polygon mirror 120 in the rotation direction F can be reduced.

  That is, in the first to third embodiments shown in FIG. 8B, from the viewpoint of increasing the resolution and printing speed of an image to be formed (printed), an area other than the image writing area γ. The shortening of the time required for X light beam scanning control is used to shorten the scanning time of one line.

  Furthermore, in the first to third embodiments, the incident beam L2a from the light source for BD 140 and the incident beam L1a from the light source 110 are incident on the same reflecting surface 120 of the polygon mirror 120, so that the polygon Compared to the case where the light enters the different reflecting surface 120 of the mirror 120, the writing start position of the image information can be detected with higher accuracy.

  Further, in the first embodiment and the second embodiment, as shown in FIG. 2, the semiconductor laser element LD3 of the BD light source 140 is disposed close to the semiconductor laser elements LD1 and LD2 of the light source 110, so The light source 140 and the light source 110 can be integrated (in this case, a single chip), whereby the device configuration can be made compact.

  Furthermore, in the second embodiment, since the wavelength of the outgoing beam L1b of the light source 110 and the wavelength of the outgoing beam L2b of the BD light source 140 are different, the outgoing beam L1b of the light source 110 and the outgoing beam L2b of the BD light source 140 are Can be easily distinguished.

  Here, as shown in FIG. 4, the dichroic mirror 133 reflects only the emission beam L2b in the write start position detection wavelength region of the BD light source 140 and transmits the emission beam L1b in the write wavelength region of the light source 110. Thus, even if the incident beam L1a from the light source 110 and the incident beam L2a from the BD light source 140 have substantially the same (very close) optical paths, the emission beam L1b in the writing wavelength region of the light source 110 and the BD light source 140 It is possible to easily separate the outgoing beam L2b in the writing start position detection wavelength region.

  Further, by providing a light absorber 134 that absorbs the emission beam L1b in the writing wavelength region that has passed through the dichroic mirror 133, the emitted beam in the writing wavelength region that has passed through the dichroic mirror 133 by this light absorber 134. By absorbing L1b, it is possible to effectively prevent the outgoing beam L1b that has passed through the dichroic mirror 133 from irradiating an unnecessary region that does not require irradiation of the surface 3a of the photoreceptor 3.

  That is, since the wavelength of the outgoing beam L1b of the light source 110 and the outgoing beam L2b of the BD light source 140 are different, the outgoing beam L2b of the BD light source 140 is reflected by the dichroic mirror 133 and enters the BD unit 130, while the light source 110 The outgoing beam L1b is transmitted and can be prevented from hitting the surface 3a of the photoreceptor 3 by the light absorber 134.

  Further, in the third embodiment, as shown in FIGS. 5 and 6, the BD light source 140 is configured such that the first deflection scanning plane Q1 of the outgoing beam L2b of the BD light source 140 is the first of the outgoing beam L1b of the light source 110. By being arranged so as to make a predetermined angle θ with respect to the two deflection scanning plane Q2, for example, it is possible to sufficiently prevent the outgoing beam L1b at the time of APC from entering the BD unit 130, thereby, in the vicinity of the polygon mirror 120. It is possible to dispose the BD light source 140 and the BD unit 130 on each other.

  That is, by providing the first deflection scanning surface Q1 by the emitted light L2b of the BD light source 140 and the second deflection scanning surface Q2 by the emitted light L1b of the light source 110 at a predetermined angle θ, the emitted beam L2b of the BD 140 is photosensitive. It does not enter the surface 3a of the body 3. In addition, since interference can be avoided with respect to the incident optical system 150 and the outgoing optical system 160 which are optical components for writing image information, the BD light source 140 and the BD unit 130 are arranged close to the polygon mirror 120. be able to.

  In the first to third embodiments described above, the light source 110 is of the multi-beam type, and here, the two incident beams L1a and L1a from the two semiconductor laser elements LD1 and LD2 are used. Needless to say, even if three or more of these are provided, the same effects as described above can be obtained.

  Next, an image forming apparatus D equipped with the optical scanning device 1 (1a to 1c) of the first to third embodiments will be described. Hereinafter, the optical scanning device 1 (1a to 1c) will be described simply as the optical scanning device 1.

(Image forming device)
FIG. 9 is a cross-sectional view schematically showing an image forming apparatus D to which the optical scanning device 1 of the first to third embodiments is applied.

  The image forming apparatus D shown in FIG. 9 is a document reading device B that reads an image of a document, and records the image of the document read by the document reading device B or image information received from the outside in color or single color on plain paper or the like. The apparatus main body A which records and forms on a material is provided.

  In the document reading apparatus B, when the document is set on the document set tray 41, the pickup roller 44 is pressed against the surface of the document and rotated, the document is pulled out from the tray 41, and passes between the suction roller 45 and the separation pad 46. After being separated one by one, it is transported to the transport path 47.

  In the conveyance path 47, the leading edge of the document contacts the registration roller 49 and is aligned parallel to the registration roller 49, and then the document is conveyed by the registration roller 49 and passes between the document guide 51 and the reading glass 52. At this time, the light from the light source of the first scanning unit 53 is irradiated on the surface of the document through the reading glass 52, and the reflected light is incident on the first scanning unit 53 through the reading glass 52. Reflected by the mirrors of the first and second scanning units 53 and 54 and guided to the imaging lens 55, an image on the surface of the document is formed on a CCD (Charge Coupled Device) 56 by the imaging lens 55. The CCD 56 reads an image on the surface of the document and outputs image data indicating the image. Further, the document is transported by the transport roller 57 and discharged to the document discharge tray 59 via the discharge roller 58.

  The document reading device B can read a document placed on the document table glass 61. The registration roller 49, the document guide 51, the document discharge tray 59, and the like and the members above them are an integrated cover body, and an axis line along the sub-scanning direction on the back side of the document reading apparatus B It is pivotally supported so that it can be opened and closed. When the upper cover body is opened, the document table glass 61 is opened, and a document can be placed on the document table glass 61. The document placed on the document table glass 61 is held by the cover body when the cover body is closed. When a document reading instruction is issued, the surface of the document on the document table glass 61 is exposed by the first scanning unit 53 while the first and second scanning units 53 and 54 are moved in the sub-scanning direction. The reflected light from the document surface is guided to the imaging lens 55 by the first and second scanning units 53 and 54, and is imaged on the CCD 56 by the imaging lens 55, where the document image is read. At this time, the first and second scanning units 53 and 54 are moved while maintaining a predetermined speed relationship with each other, and reflection of the document surface → first and second scanning units 53 and 54 → imaging lens 55 → CCD 56 is performed. The positional relationship between the first and second scanning units 53 and 54 is always maintained so that the length of the optical path of the light does not change, and thereby the focus of the image on the original surface on the CCD 56 is always accurately maintained.

  The entire original image read in this way is sent and received as image data to the apparatus main body A of the image forming apparatus D, and the apparatus main body A records an image on a recording material.

  On the other hand, the apparatus main body A of the image forming apparatus D includes an optical scanning device 1, a developing device 2 (2a, 2b, 2c, 2d), a photosensitive drum 3 (3a, 3b, 3c, 3d) that functions as a scanned body, Intermediate transfer belt device including charger 5 (5a, 5b, 5c, 5d), cleaner device 4 (4a, 4b, 4c, 4d), and intermediate transfer roller 6 (6a, 6b, 6c, 6d) acting as a transfer portion. 8, a fixing device 12, a transport device 18, a paper feed tray 10 that functions as a paper feed unit, and a paper discharge tray 15 that functions as a paper discharge unit.

  The image data handled in the apparatus main body A of the image forming apparatus D is data corresponding to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, This corresponds to a monochrome image using (black). Accordingly, the developing device 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), the charger 5 (5a, 5b, 5c, 5d), and the cleaner device 4 (4a, 4b, 4c, 4d) and four intermediate transfer rollers 6 (6a, 6b, 6c, 6d) are provided so as to form four types of images corresponding to the respective colors. Is associated with black, b with cyan, c with magenta, and d with yellow to form four image stations. Hereinafter, the description will be made with the suffixes a to d omitted.

  The photoconductor drum 3 is disposed at substantially the center in the vertical direction of the apparatus main body A. The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential, and a charger type charger is used in addition to a contact type roller type or brush type charger. .

  Here, the optical scanning device 1 is a laser scanning unit (LSU) provided with the light beam scanning optical system shown in FIGS. 1, 4 and 5, and the surface of the charged photosensitive drum 3 is made according to image data. Exposure is performed to form an electrostatic latent image corresponding to the image data on the surface. Here, the image forming apparatus D shown in FIG. 9 is of a tandem type in which four photosensitive drums 3 are arranged in parallel in a predetermined direction. Accordingly, the light beam scanning optical systems shown in FIGS. 1, 4 and 5 are incorporated corresponding to the four photosensitive drums 3 so that electrostatic latent images can be formed on the four photosensitive drums 3, respectively. It is.

  The developing device 2 develops the electrostatic latent image formed on the photosensitive drum 3 with (K, C, M, Y) toner. The cleaner device 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  In addition to the intermediate transfer roller 6, the intermediate transfer belt device 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7 that acts as an intermediate transfer member, an intermediate transfer belt drive roller 21, a driven roller 22, and a tension roller. 23 and an intermediate transfer belt cleaning device 9.

  Roller members such as the intermediate transfer belt drive roller 21, the intermediate transfer roller 6, the driven roller 22, and the tension roller 23 stretch and support the intermediate transfer belt 7, and the intermediate transfer belt 7 is supported in a predetermined conveyance direction (arrow in the figure). Move around in the C direction).

  The intermediate transfer roller 6 is rotatably supported inside the intermediate transfer belt 7 and is pressed against the photosensitive drum 3 via the intermediate transfer belt 7, and transfers the toner image on the photosensitive drum 3 to the intermediate transfer belt 7. A transfer bias is applied.

  The intermediate transfer belt 7 is provided so as to be in contact with each photoconductive drum 3, and a color toner image (each color is transferred by sequentially superimposing and transferring the toner image on the surface of each photoconductive drum 3 onto the intermediate transfer belt 7. Toner image). Here, the transfer belt 7 is formed in an endless belt shape using a film having a thickness of about 100 μm to 150 μm.

  The transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by an intermediate transfer roller 6 that is in pressure contact with the inner side (back surface) of the intermediate transfer belt 7. A high voltage transfer bias (for example, a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. Here, the intermediate transfer roller 6 is a roller based on a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the recording material.

  The apparatus main body A of the image forming apparatus D further includes a secondary transfer apparatus 11 including a transfer roller 11a that functions as a transfer unit. The transfer roller 11a is in contact with the opposite side (outside) of the intermediate transfer belt 7 from the intermediate transfer belt drive roller 21.

  As described above, the toner images on the surfaces of the respective photosensitive drums 3 are stacked on the intermediate transfer belt 7 and become a color toner image indicated by the image data. The stacked toner images of the respective colors are transported together with the intermediate transfer belt 7 and transferred onto the recording material by the secondary transfer device 11.

  The intermediate transfer belt 7 and the transfer roller 11a of the secondary transfer device 11 are pressed against each other to form a nip region. Further, a voltage (for example, a polarity (+) opposite to the toner charging polarity (−)) is applied to the transfer roller 11a of the secondary transfer device 11 to transfer the toner image of each color on the intermediate transfer belt 7 onto the recording material. Is applied). Further, in order to constantly obtain the nip region, either the transfer roller 11a of the secondary transfer device 11 or the intermediate transfer belt drive roller 21 is made of a hard material (metal or the like), and the other is a soft material such as an elastic roller. (Elastic rubber roller, foaming resin roller, etc.).

  In addition, the toner image on the intermediate transfer belt 7 may not be completely transferred onto the recording material by the secondary transfer device 11, and the toner may remain on the intermediate transfer belt 7. Causes color mixing. Therefore, the residual toner is removed and collected by the intermediate transfer belt cleaning device 9. The intermediate transfer belt cleaning device 9 includes, for example, a cleaning blade that contacts the intermediate transfer belt 7 as a cleaning member, and residual toner can be removed and collected by the cleaning blade. The driven roller 22 supports the intermediate transfer belt 7 from the inner side (back side), and the cleaning blade is in contact with the intermediate transfer belt 7 so as to press it toward the driven roller 22 from the outer side.

  The paper feed tray 10 is a tray for storing recording materials, and is provided below the image forming unit of the apparatus main body A. The paper discharge tray 15 provided on the upper side of the image forming unit is a tray for placing printed recording materials face down.

  Further, the apparatus main body A is provided with a conveying device 18 for sending the recording material of the paper feed tray 10 to the paper discharge tray 15 via the secondary transfer device 11 and the fixing device 12. The transport device 18 has an S-shaped transport path S, and along this transport path S, a pickup roller 16, each transport roller 13, a pre-registration roller 19, a registration roller 14, a fixing device 12, and a paper discharge. A conveying member such as a roller 17 is arranged.

  The pickup roller 16 is a pull-in roller that is provided at the downstream end of the paper feed tray 10 in the recording material conveyance direction and supplies the recording material from the paper feed tray 10 to the conveyance path S one by one. Each conveyance roller 13 and the pre-registration roller 19 are small rollers for promoting and assisting the conveyance of the recording material. Each transport roller 13 is provided at a plurality of locations along the transport path S. The pre-registration roller 19 is provided in the immediate vicinity of the registration roller 14 upstream in the recording material conveyance direction, and conveys the recording material to the registration roller 14.

  The registration roller 14 temporarily stops the recording material conveyed by the pre-registration roller 19, aligns the leading end of the recording material, and is on the intermediate transfer belt 7 in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11. The recording material is conveyed with good timing in accordance with the rotation of the photosensitive drum 3 and the intermediate transfer belt 7 so that the color toner image is transferred onto the recording material.

  For example, the registration roller 14 performs recording so that the front end of the color toner image on the intermediate transfer belt 7 matches the front end of the image forming range on the recording material in the nip region between the intermediate transfer belt 7 and the secondary transfer device 11. Transport material.

  The fixing device 12 includes a heat roller 31 and a pressure roller 32. The heat roller 31 and the pressure roller 32 sandwich and transport the recording material.

  The heat roller 31 is temperature-controlled by the main control unit so as to reach a predetermined fixing temperature based on a detection output of a temperature detector (not shown). The toner image transferred onto the recording material is melted, mixed, and pressed to be thermally fixed to the recording material.

  The recording material after the fixing of the toner images of the respective colors is discharged onto the paper discharge tray 15 by the paper discharge roller 17.

  It is also possible to form a monochrome image using at least one of the four image forming stations and transfer the monochrome image to the intermediate transfer belt 7 of the intermediate transfer belt device 8. Similarly to the color image, this monochrome image is also transferred from the intermediate transfer belt 7 to the recording material and fixed on the recording material.

  In addition, when performing image formation on both sides as well as the front (front) surface of the recording material, the recording material is fixed by the fixing device 12 and then the recording material is discharged by the paper discharge roller 17 in the conveyance path S. In the middle of conveyance, the paper discharge roller 17 is stopped and then reversely rotated, the recording material is passed through the front / back reversing path Sr, the recording material is reversed, and then the recording material is guided to the registration roller 14 again. Similarly to the front surface of the recording material, an image is recorded and fixed on the back surface of the recording material, and the recording material is discharged to the paper discharge tray 15.

  The main control unit provided in the image forming apparatus D can instruct the control unit provided in the optical scanning device 1 of the first to third embodiments. Further, instead of the control unit of the optical scanning device 1 of the first to third embodiments, a part of the main control unit of the image forming apparatus D may constitute the control unit of the optical scanning device 1.

  According to the image forming apparatus D described above, since the optical scanning device 1 according to the first to third embodiments is provided, the same effects as those described above can be obtained.

  Here, the optical scanning device according to the present invention is mounted on a tandem type image forming apparatus, but may be mounted on an image forming apparatus including a single photoconductor.

DESCRIPTION OF SYMBOLS 1 Optical scanning apparatus 3 Photosensitive body (an example of to-be-scanned body)
110 Light source 120 Polygon mirror (Rotating polygon mirror)
121 Reflecting surface 130 BD section (writing start position detecting section)
133 Dichroic mirror 134 Light absorber 140 BD light source (light source for writing start position detection)
D Image forming apparatus L1a, L2a Incident beam (light beam)
L1b, L2b Output beam (light beam)
LD1 to LD3 Semiconductor laser element (an example of a light emitting element)
Q1 First deflection scanning plane Q2 Second deflection scanning plane θ Angle

Claims (12)

A light beam scanning optical system for writing image information on a scanned object while deflecting and scanning the light beam from a light source emitting a light beam by a rotary polygon mirror and detecting a writing start position of image information by a writing start position detector Because
In addition to the light source, a light source for detecting a writing start position for emitting a light beam is provided. The light beam scanning optical system according to claim 1.
The light beam scanning optical system, wherein the light beam from the light source for detecting the writing start position and the light beam from the light source are incident on the same reflecting surface of the rotary polygon mirror. The light beam scanning optical system according to claim 1 or 2,
The light source is provided with a plurality of light emitting elements, and the writing start position detecting light source is provided with at least one light emitting element. The light beam scanning optical system according to claim 3.
The light beam scanning optical system, wherein the light emitting element of the light source for detecting the writing start position is disposed in proximity to the light emitting element of the light source. The light beam scanning optical system according to any one of claims 1 to 4,
The light beam from the light source has a wavelength in the wavelength region for writing,
The light beam scanning optical system according to claim 1, wherein the light beam from the write start position detection light source has a wavelength in a write start position detection wavelength region different from the write wavelength region. The light beam scanning optical system according to claim 5,
A wavelength separation unit that reflects the light beam in the writing start position detection wavelength region while passing the light beam in the writing wavelength region;
The light beam scanning optical system, wherein the wavelength separation means is provided on an optical path of a light beam from the light source and the writing start position detecting light source. The light beam scanning optical system according to claim 6.
A light beam scanning optical system comprising a light absorber that absorbs the light beam in the wavelength region for writing that has passed through the wavelength separation means. The light beam scanning optical system according to claim 6 or 7,
The light beam scanning optical system, wherein the wavelength separation means is a dichroic mirror. The light beam scanning optical system according to claim 1,
The light source for writing start position detection has a first deflection scanning surface showing a scanning locus by a deflection scanning of the light beam from the light source for writing start position detection by the rotary polygon mirror, and the rotation of the light beam from the light source. A light beam scanning optical system, characterized in that the light beam scanning optical system is arranged so as to form an angle with respect to a second deflection scanning surface showing a scanning locus by deflection scanning with a polygon mirror.   An optical scanning apparatus comprising the light beam scanning optical system according to any one of claims 1 to 9. The optical scanning device according to claim 10.
An optical scanning device that performs stabilization control of output power of the light source.   An image forming apparatus comprising the optical scanning device according to claim 10.

Images