JP6786258B2 - Optical scanning device and image forming device equipped with it - Google Patents

Description

The present invention relates to an image forming apparatus such as a laser beam printer (LBP), a digital copier, and a multifunction printer (multifunctional printer), and an optical scanning apparatus included therein.

As an optical scanning device included in an image forming apparatus, there is known an optical scanning device that scans a surface to be scanned in the main scanning direction by deflecting a light flux from a light source with a deflector. In such an optical scanning device, in order to light-scan the surface to be scanned with high accuracy, it is necessary to detect the luminous flux deflected by the deflector and determine the writing position in the main scanning direction on the surface to be scanned. A synchronization detector is required.

Patent Document 1 describes a configuration in which a light flux from a light source is separated by a light flux separating element and guided to a surface to be scanned and a synchronization detection unit, respectively. Further, Patent Document 2 describes a configuration in which a light beam passing through an end portion of an imaging lens is reflected by a mirror to be guided to a synchronization detection unit.

Japanese Unexamined Patent Publication No. 2009-15943 JP-A-2007-298997

However, in the configurations described in Patent Documents 1 and 2, a light flux separating element and a mirror are required, which not only complicates the apparatus but also makes it impossible to perform highly accurate synchronization detection due to each placement error. there is a possibility. Further, in the configurations described in Patent Documents 1 and 2, since it is necessary to arrange each member in the main scanning cross section so that the light flux toward the surface to be scanned is not kicked, the device has not been sufficiently made compact. ..

An object of the present invention is to provide an optical scanning apparatus and an image forming apparatus capable of realizing highly accurate synchronization detection and compactification with a simple configuration.

To achieve the above object, an optical scanning apparatus according to one aspect of the present invention, a deflector for scanning to deflect the light beam to the scanned surface in the main scanning direction, a first of said deflector in the sub-scanning section an incident optical system for obliquely incident light beam on the deflecting surface of, has fθ characteristics, and an imaging optical system for guiding the light beam deflected by said first deflecting surface to the surface to be scanned, the first deflection The imaging optical system includes a light receiving unit that receives a light beam deflected by the surface and generates a first signal, and the imaging optical system is arranged between the deflector and the scanned surface, and is used for sub-scanning. The angle of incidence of the light beam from the incident optical system in the cross section with respect to the first deflection surface is α (deg), and the light beam incident on the first deflection surface in the main scanning cross section and the first deflection surface are used . When the angle formed by the deflected light beam toward the light receiving portion is β (deg), the condition of | β | ≤ | α | is satisfied.

According to the present invention, it is possible to provide an optical scanning apparatus and an image forming apparatus capable of realizing highly accurate synchronization detection and compactification with a simple configuration.

It is a schematic diagram of the main part of the optical scanning apparatus which concerns on embodiment of this invention. It is a main scanning sectional view of the optical scanning apparatus which concerns on Example 1 of this invention. It is a schematic diagram of the main part of the incident optical system and the light receiving part which concerns on Example 1 of this invention. It is a figure which shows the light emission timing of the light source which concerns on Example 1 of this invention. It is a main scanning sectional view of the optical scanning apparatus which concerns on Example 2 of this invention. It is a sub-scanning sectional view of the optical scanning apparatus which concerns on Example 2 of this invention. It is a schematic diagram of the main part of the incident optical system and the light receiving part which concerns on Example 2 of this invention. It is a main scanning sectional view of the optical scanning apparatus which concerns on Example 3 of this invention. It is a sub-scanning sectional view of the incident optical system which concerns on Example 3 of this invention. It is a figure which shows the light emission timing of the light source which concerns on Example 3 and Comparative Example of this invention. It is a schematic diagram of the main part of the incident optical system and the synchronization detection part which concerns on Example 4 of this invention. It is a main scanning sectional view of the optical scanning apparatus which concerns on Example 5 of this invention. It is a sub-scanning sectional view of the incident optical system which concerns on Example 5 of this invention. It is a sub-scanning sectional view of the image forming apparatus which concerns on embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. For convenience, each drawing may be drawn at a scale different from the actual one. Further, in each drawing, the same member is given the same reference number, and duplicate description is omitted. In the following description, the main scanning direction is the direction in which the surface to be scanned is lightly scanned by the deflector, and here, in the direction perpendicular to the rotation axis (or swing axis) of the deflector and the optical axis direction. Equivalent to. The sub-scanning direction is a direction that intersects with the main scanning direction, and here corresponds to a direction parallel to the rotation axis (or swing axis) of the deflector. Further, the main scanning cross section is a cross section including the optical axis and parallel to the main scanning direction, and here, it is also a cross section perpendicular to the sub scanning direction. The sub-scanning cross section is a cross section including the optical axis and parallel to the sub-scanning direction, and here, it is also a cross-section perpendicular to the main scanning direction.

FIG. 1 is a schematic view of a main part of the optical scanning device 100 according to the present embodiment. FIG. 1A schematically shows a main scanning cross section of the optical scanning apparatus 100, and FIG. 1B is a portion including an incident optical system L, a deflector 5, and a light receiving portion 8 included in the optical scanning apparatus 100. The sub-scanning section of is schematically shown. In FIG. 1, only the main ray is shown by omitting the marginal ray of each luminous flux. Further, in FIG. 1B, the optical path is developed so that the optical axis direction of the incident optical system L coincides with the optical axis direction (X direction) of the imaging optical system 6 in FIG. 1A.

The optical scanning device 100 according to the present embodiment deflects a light beam by a deflector 5 to lightly scan the surface to be scanned 7 in the main scanning direction B. As the deflector 5, a rotating multi-sided mirror (polygon mirror) in which a plurality of deflection surfaces (reflection surfaces) 51 rotate around a rotation axis is shown, but instead of this, one or one or one around the swing axis is shown. It may be a swing mirror in which two deflection surfaces swing. The deflector 5 is rotated at a constant speed (equal angular velocity) in the direction of arrow A by a drive unit (not shown) composed of a motor or the like.

As shown in FIG. 1B, the incident optical system L according to the present embodiment obliquely incidents a luminous flux on the deflection surface 51 of the deflector 5 (incidents obliquely with respect to the main scanning cross section) in the sub-scanning cross section. It is an oblique incident system. The incident optical system L according to the present embodiment is composed of only a light source, but if necessary, the incident optical system L includes an optical element that guides a light flux from the light source to a deflection surface 51, an aperture diaphragm, and the like. May be adopted. Alternatively, the incident optical system L may be configured to guide a light flux from an external light source of the optical scanning device 100.

Further, the light receiving unit 8 receives the light flux deflected by the deflection surface 51 and generates a signal. Based on the signal generated by the light receiving unit 8, synchronization detection for determining the writing position in the main scanning direction on the surface to be scanned 7 and control of the amount of emitted light from the light source can be performed. The light receiving unit 8 according to the present embodiment is composed of only a light receiving element such as a photoelectric conversion element, but the light receiving unit 8 guides the light flux from the deflection surface 51 to such a light receiving element as needed. A configuration including an optical element, an aperture stop, and the like may be adopted. In this embodiment, the light source and the light receiving element are mounted on the same substrate, so that the number of parts is reduced and the relative positions of the light source and the light receiving elements are suppressed from being displaced.

In the incident optical system L, the light flux emitted from a light source such as a semiconductor laser is incident on the deflection surface of the rotating deflector 5. At a certain angle of rotation, the light flux reflected by the deflection surface 51 enters the light receiving unit 8 and is photoelectrically converted to generate a signal. As the rotation of the deflector 5 further progresses, the light flux reflected by the deflection surface 51 is incident on the surface to be scanned 7 by the imaging optical system 6. Then, as the deflector 5 rotates, the light flux from the incident optical system L is deflected by the deflection surface 51, and the surface to be scanned 7 is scanned in the main scanning direction (Y direction).

By using the signal generated by the light receiving unit 8, it is possible to determine the timing at which optical scanning is started on the surface to be scanned 7, that is, the writing position, based on the signal. Such synchronous detection is performed once for each scan of the surface to be scanned 7. Further, when the optical scanning in the main scanning direction is repeatedly performed while moving the surface to be scanned 7 in the sub-scanning direction, the synchronization detection may be performed once for every plurality of scannings.

Here, the incident angle of the light flux from the incident optical system L in the sub-scanning cross section with respect to the deflection surface 51 is α (deg), and the light flux incident on the deflection surface 51 in the main scanning cross section and the deflection surface 51 are deflected. Let β (deg) be the angle formed by the light flux toward the light receiving unit 8. However, each angle is determined based on the main ray of each luminous flux. At this time, the optical scanning apparatus 100 according to the present embodiment satisfies the following conditional expression (1).
｜ β ｜ ≦ ｜ α ｜ ・ ・ ・ (1)

In the optical scanning apparatus 100 according to the present embodiment, by using the incident optical system L as an oblique incident system, the incident optical system L and the light receiving unit 8 can be arranged so as to be separated from each other in the sub-scanning direction. Then, by satisfying the above conditional expression (1), the incident optical system L and the light receiving unit 8 can be arranged close to each other in the main scanning cross section. As a result, it is not necessary to arrange members such as a light flux separating element and a mirror as described in Patent Documents 1 and 2 in each optical path. That is, in the main scanning cross section, the optical path between the incident optical system L and the deflection surface and between the deflection surface and the light receiving portion 8 is an optical path in which the main ray of the luminous flux is neither refracted nor reflected. It is possible to realize highly accurate synchronization detection and compactness of the entire device with such a configuration.

If the conditional expression (1) is not satisfied, the space occupied by the incident optical system L and the light receiving unit 8 in the main scanning cross section becomes large, and it becomes difficult to make the entire device compact. It is desirable to satisfy at least one of the following conditional expressions (2) and (3) in order to realize a more sufficient compactification of the entire device.
1.5 ≤ | α | ≤ 10 ... (2)
0 ≦ ｜ β ｜ ≦ 5.0 ・ ・ ・ (3)

Further, the optical scanning apparatus 100 according to the present embodiment more preferably satisfies at least one of the following conditional expressions (4) and (5).
1.5 ≦ ｜ α ｜ ≦ 5.0 ・ ・ ・ (4)
0 ≤ | β | ≤ 3.0 ... (5)

[Example 1]
Hereinafter, the optical scanning apparatus 200 according to the first embodiment of the present invention will be described in detail.

FIG. 2 is a main scanning cross-sectional view of the optical scanning apparatus 200 according to the present embodiment. FIG. 3 is a schematic view of a main part of the incident optical system L and the light receiving unit 8 included in the optical scanning device 200, FIG. 3 (a) schematically shows a sub-scanning cross section, and FIG. 3 (b) shows a light source and photoelectric light. The front surface of the module having the conversion element is schematically shown. In FIG. 3, the optical path is developed so that the optical axis direction of the incident optical system L coincides with the optical axis direction (X direction) of the imaging optical system 6 in FIG. 2, and only the main ray is omitted by omitting the marginal ray. Is shown.

The incident optical system L according to the present embodiment includes a light source 1 that emits a light flux, an aperture throttle 2 that regulates the light flux from the light source 1 to form its shape, and a condensing state (convergence) of the light flux from the aperture throttle 2. It includes a condensing lens (condensing optical element) 3 for converting a degree). In this embodiment, the light source 1 is a semiconductor laser, and the condenser lens 3 is an anamorphic lens having different refractive powers in the main scanning cross section and in the sub scanning cross section. The condenser lens 3 converts the divergent luminous flux emitted from the light source 1 and passing through the aperture diaphragm 2 into a parallel luminous flux or a convergent luminous flux in the main scanning cross section, and is converted into a convergent luminous flux in the sub-scanning cross section. The condenser lens 3 may be composed of two optical elements, a collimator lens and a cylinder lens, and at that time, the two optical elements may be integrated.

The deflector 5 according to the present embodiment is a rotary multifaceted mirror (polygon mirror) having a plurality of deflection surfaces (reflection surfaces) 51, and has a constant speed in the direction of arrow A by a drive unit (not shown) composed of a motor or the like. It is rotated at (uniform velocity). The deflector 5 deflects the light flux guided by the incident optical system L on each deflection surface 51, and light-scans the surface to be scanned 7 in the main scanning direction (direction of arrow B). As the deflector 5, a swing mirror or the like that swings at a constant speed may be used instead of the rotary multifaceted mirror.

In the optical path from the deflector 5 to the surface to be scanned 7, an imaging optical system 6 composed of an imaging lens (imaging optical element) having a condensing function and fθ characteristics is arranged. This imaging lens is an anamorphic lens made of a plastic (resin) material or the like, and has a positive power on the optical axis in the main scanning cross section and the sub scanning cross section. The imaging optical system 6 guides and concentrates the light flux deflected by the deflector 5 on the surface to be scanned 7 to form a spot image. Then, the spot image moves on the scanned surface 7 at a constant velocity due to the fθ characteristic. The imaging optical system 6 compensates for the deflection of the deflection surface 51 by making the deflection surface 51 and the surface to be scanned 7 have a conjugate relationship in the sub-scanning cross section.

Table 1 shows each numerical value such as the optical arrangement of the imaging optical system according to this embodiment.

The shape (generatrix shape) of each lens surface (incident surface and exit surface) of the imaging lens 6 according to the present embodiment in the main scanning cross section including the surface apex can be expressed as a function up to the 12th order. It has a spherical shape. Specifically, when the intersection of each lens surface and the optical axis is the origin, the axis in the optical axis direction is the X axis, and the axis orthogonal to the optical axis in the main scanning surface is the Y axis, the lens surface of each lens surface. The bus shape is expressed by the following equation.

However, R is the radius of curvature (generatrix radius of curvature) in the main scanning cross section on the optical axis, and K, B ₄ , B ₆ , B ₈ , B ₁₀ , and B ₁₂ are the aspherical coefficients in the main scanning cross section. Is. Further, the shape (child line shape) of each lens surface in the sub-scanning cross section at each position in the main scanning direction is expressed by the following equation.

1 / r'= 1 / r + D ₂ Y ² + D ₄ Y ⁴ + D ₆ Y ⁶ + D ₈ Y ⁸ + D ₁₀ Y ¹⁰ + D ₁₂ Y ¹²
However, r is the radius of curvature (radius of curvature of the child line) in the sub-scanned cross section on the optical axis, and D ₂ , D ₄ , D ₆ , D ₈ , D ₁₀ , and D ₁₂ are the coefficient of variation of the child line. Further, D ₂ , D ₄ , D ₆ , D ₈ , D ₁₀ , and D ₁₂ are the radius of curvature of the child line at the position of the image height Y, and Mj_k is the aspherical coefficient in the sub-scanning section. For example, Mj_1 is a linear term of Z and indicates the inclination of the lens surface (child line tilt) in the sub-scanning cross section. In this embodiment, the child line tilt amount is changed in the main scanning direction by using coefficients of the 0th, 2nd, 4th, 6th, 8th, and 10th orders.

Table 2 shows the shape data of each lens surface of the imaging lens according to this embodiment. For each coefficient in Table 2, the subscript u indicates the same side (Upper side) as the light source 1 with respect to each lens surface apex (that is, the optical axis) of the imaging lens, and the subscript l indicates the imaging lens. The side opposite to the light source 1 (Lower side) is shown for each lens surface apex. The coefficients without the subscripts u and l are common coefficients on the Upper side and the Lower side.

Next, the configurations of the incident optical system L and the light receiving unit 8 according to this embodiment will be described in detail.

The light receiving unit 8 according to the present embodiment is a synchronization detection unit that receives the light flux deflected by the deflection surface 51 and generates a synchronization signal for determining the writing position in the main scanning direction on the scanned surface 7. Function. The light receiving unit 8 receives light from the synchronous detection lens (optical element for synchronous detection) 81 that guides and concentrates the light flux DL for synchronous detection deflected by the deflection surface 51, and the light flux from the synchronous detection lens 81. It has a synchronization detection sensor (photoelectric conversion element) 82 that outputs a synchronization signal.

The synchronization signal output from the sensor 82 is input to the control circuit (driver) 10 shown in FIGS. 2 and 3, and the control circuit 10 is the writing position in the main scanning direction on the scanned surface 7 based on the synchronization signal. To determine. FIG. 4 is a timing chart showing the light emission timing of the light source 1 while the deflector 5 makes one rotation. LD indicates the on / off state of the light source, CLK indicates the clock signal, and DT indicates the output signal of the sensor.

By the control circuit 10, the light source 1 starts emitting light at time t1 and temporarily stops emitting light at time t2. During this period, when the luminous flux from the light source 1 is reflected by the deflection surface 51 and enters the sensor 82, a synchronization signal is generated at time td. The control circuit counts the clock pulse CLK from the time td, and when the count reaches a predetermined value, the light source 1 is made capable of emitting light (time t3). Since the time (time t3 to time t4) required for optical scanning of the effective region of the scanned surface 7 is predetermined, the light source 1 is turned on or off according to the image data during that time, and the scanned surface 7 is lined up. The exposure will be performed in a pattern corresponding to the minute image data.

In this way, since the writing timing in the main scanning direction is determined based on the synchronization signal, the reproducibility of the writing position is maintained even if the scanning is repeated. In this embodiment, the operation of performing synchronous detection and determining the writing timing is repeated every time the scanned surface 7 is light-scanned once.

Table 3 shows each numerical value such as the optical arrangement of the incident optical system L, and Table 4 shows each numerical value such as the optical arrangement of the light receiving unit 8.

The “incident angle γ in the main scanning cross section” in Table 3 indicates the angle formed by the main ray emitted from the incident optical system L and incident on the deflection surface 51 in the main scanning cross section and the optical axis of the imaging optical system 6. ing. Further, the “incident angle γ ′ in the main scanning cross section” and the “incident angle α ′ in the sub scanning cross section” in Table 4 are deflected by the deflection surfaces 51 in the main scanning cross section and in the sub scanning cross section, respectively. The angle formed by the main light beam toward the light receiving unit 8 and the optical axis of the imaging optical system 6 is shown. In this embodiment, γ = γ'and α = −α'.

As shown in FIG. 3A, the incident luminous flux LL guided to the deflection surface 51 of the deflector 5 by the incident optical system L is when the deflection surface 51 has a specific deflection angle in the main scanning cross section. , It is deflected toward the incident optical system L side. Here, since the incident optical system L obliquely incidents the incident light flux LL with respect to the deflection surface 51 at an incident angle of 3 ° in the sub-scanning cross section, the incident light flux LL incident on the deflection surface 51 is the incident optics. It is deflected downward without returning to the system L. Then, in this embodiment, since the incident optical system L and the light receiving unit 8 are arranged side by side in the sub-scanning direction so that the incident angles in the main scanning cross section are the same, they are deflected by the deflection surface 51. The luminous flux is incident on the light receiving unit 8 as a synchronous detection luminous flux DL.

As described above, in this embodiment, the incident optical system L is an oblique incident system, so that the incident optical system L and the light receiving unit 8 can be arranged side by side in the sub-scanning direction. Here, in this embodiment, since α = 3 ° and β = 0 °, the above-mentioned conditional expressions (1) to (5) are satisfied. As a result, the space for arranging the light receiving portion 8 can be reduced in the main scanning cross section, and as a result, the scanning angle of view of the deflector 5 can be widened, so that the imaging optical system 6 and the subject can be covered. It becomes possible to shorten the distance from the scanning surface 7.

In particular, by configuring the incident luminous flux LL and the synchronous detection luminous flux DL to match in the main scanning cross section as in the present embodiment, it is possible to realize a more sufficient compactification of the entire apparatus. The term "match" here means not only when the main rays of the incident light flux LL and the synchronous detection light flux DL are exactly the same in the main scanning cross section, but also when both light fluxes overlap over the entire optical path. It also includes cases such as cases where there is a "substantial match". However, it is more preferable that the main rays of both the incident luminous flux LL and the synchronous detection luminous flux DL are the same.

Further, by adopting the above configuration, the incident optical system L and the light receiving unit 8 can be arranged at a position closer to the imaging optical system 6. As a result, the error between the effective luminous flux that lightly scans the effective region of the scanned surface 7 and the luminous flux DL for synchronization detection can be reduced, so that synchronization detection can be performed with higher accuracy. At this time, unlike the configuration described in Patent Document 2, it is not necessary to detect the luminous flux DL via the imaging optical system 6, so that the imaging optical system 6 can be made compact.

In this embodiment, the condenser lens 3 (first optical element) and the synchronization detection lens 81 (second optical element) are integrally molded (integrated) in order to reduce the number of parts. However, if necessary, they may be arranged separately. Further, in this embodiment, by mounting the light source 1 and the sensor 82 on the same substrate, the number of parts is reduced and the relative position deviation of each is suppressed. When this configuration is adopted, the optical path length from the light source 1 to the deflection surface 51 and the optical path length from the deflection surface 51 to the synchronization detection sensor 82 are substantially the same.

In this embodiment, since the optical path length from the light source 1 to the deflection surface 51 is 47 mm, the distance between the centers of the light source 1 and the synchronization detection sensor 82 in the sub-scanning direction is (47 mm × sin (3 °)) ×. 2 = 4.9 mm. Then, in FIG. 3B, the light source 1 has a circular shape with a diameter of 4 mm, and the sensor 82 has a rectangular shape with a length of 3 mm in the main scanning direction and a length of 4 mm in the sub-scanning direction. Therefore, even if the incident optical system L and the light receiving unit 8 have the same incident angle in the main scanning cross section, the light source 1 and the sensor 82 do not interfere with each other.

Here, in the present embodiment, in the main scanning cross section, the optical path from the incident optical system L (light source 1) to the deflection surface 51 and the optical path from the deflection surface 51 to the light receiving portion 8 (sensor 82) are the main light beams. The member that refracts the light beam and the member that reflects the light beam are not arranged. That is, since the members such as the luminous flux separation element and the mirror as described in Patent Documents 1 and 2 are not arranged, they are not affected by the arrangement error of these members and do not interfere with each member. Space for arranging them is not required.

As described above, according to the optical scanning apparatus 200 according to the present embodiment, highly accurate synchronization detection and compactification can be realized with a simple configuration.

[Example 2]
Hereinafter, the optical scanning apparatus 300 according to the second embodiment of the present invention will be described in detail. Unlike the optical scanning device 200 according to the first embodiment, the optical scanning device 300 according to the present embodiment has a configuration in which light rays emitted from two light sources lightly scan two different surfaces to be scanned. There is.

FIG. 5A schematically shows the main scanning cross section of the optical scanning apparatus 300 according to the present embodiment, and FIG. 5B schematically shows the incident optical systems L1 and L2 and the light receiving unit 8 in an enlarged manner. Further, FIG. 6 schematically shows a sub-scanning cross section of the optical scanning apparatus 300. In FIG. 5A, the reflection members M1 to M3 in each optical path from the deflection surface 51 to the scanned surfaces 71 and 72 are omitted, and each optical path is shown in an expanded manner. Further, in FIG. 5B, light rays other than the main light rays emitted from the light source 12 and some members are omitted.

In this embodiment, the first incident optical system L1 and the second incident optical system L2 deflect the light fluxes corresponding to the first scanned surface 71 and the second scanned surface 72, which are different from each other, with the same deflection. The light is guided to the surface 51. The first incident optical system L1 includes a light source 11, a collimator lens 31, a cylinder lens 41, and an aperture aperture 21, and the second incident optical system L2 includes a light source 12, a collimator lens 32, a cylinder lens 42, and an aperture aperture 21. 22 is included. In this embodiment, the cylinder lenses 41 and 42 are integrated, but they may be separated from each other if necessary. Further, the collimator lenses 31 and 32 may be integrated.

In this embodiment, each of the light sources 11 and 12 is a semiconductor laser. Each of the collimator lenses 31 and 32 has the same refractive force in the main scanning cross section and in the sub scanning cross section, and the divergent light emission emitted from the light sources 11 and 12 can be seen in the main scanning cross section and the sub scanning cross section, respectively. It is converted to a parallel light beam inside. Each of the cylinder lenses 41 and 42 converts the light flux emitted from the collimator lenses 31 and 32 into a convergent light flux in the sub-scanning cross section. Further, each of the aperture diaphragms 21 and 22 is shaped by regulating the light flux emitted from the cylinder lenses 41 and 42, respectively.

Unlike the first embodiment, the imaging optical system 6 according to the present embodiment has a first imaging lens 61 and a second imaging lens 62 in each optical path from the deflection surface 51 to the scanned surfaces 71 and 72. It has two imaging lenses. In this embodiment, the first imaging lens 61 is integrated (shared) in each optical path. Each of the imaging lenses 61 and 62 is an anamorphic lens made of the same plastic material. The first imaging lens 61 has a positive power in the main scanning cross section and no power in the sub scanning cross section on the optical axis. Further, the second imaging lens 62 has a negative power in the main scanning cross section and a positive power in the sub scanning cross section on the optical axis.

Between the first imaging lens 61 and the scanned surfaces 71 and 72, the reflecting members M1 to M3 that bend the luminous flux to guide the light to each scanned surface, and the intrusion of dust into the inside of the optical scanning device 300. Dustproof glasses 91 and 92 are arranged to prevent the above. The number and arrangement of reflective members in each optical path are not limited to those shown in FIG. Further, if necessary, the first imaging lens 61 may be separated and arranged in each optical path, or the second imaging lens 62 may be integrated in each optical path.

In the optical scanning apparatus 300 according to the present embodiment, the light fluxes from the first incident optical system L1 and the second incident optical system L2 are reflected at the same position on the same deflection surface 51, and are reflected on the scanned surfaces 71 and 72. They are simultaneously incident at positions corresponding to each other in each main scanning direction. That is, the writing timings of the light flux emitted from each of the light source 11 and the light source 12 are equal to each other. However, if necessary, the incident position of each light flux on the deflection surface 51 and the writing timing on each scanned surface may be different from each other.

Similar to the first embodiment, Table 5 shows each numerical value such as the optical arrangement of the imaging optical system according to the present embodiment, and Table 6 shows the lens surface shape of the imaging lens according to the present embodiment. The values shown in Table 5 are common to the two optical paths. Further, the shape of each lens surface of the imaging lenses 61 and 62 is represented by the same definition formula as that shown in the first embodiment.

Next, the configurations of the incident optical systems L1 and L2 and the light receiving unit 8 according to this embodiment will be described in detail. 7A and 7B are schematic views of the main parts of the incident optical systems L1 and L2 and the light receiving unit 8, FIG. 7A is a schematic cross section of the sub-scanning, and FIG. Is shown. Similar to the first embodiment, Table 7 shows each numerical value such as the optical arrangement of the incident optical systems L1 and L2, and Table 8 shows each numerical value such as the optical arrangement of the light receiving unit 8. The values shown in Table 7 are common to the incident optical systems L1 and L2 except for the incident angle in each cross section.

In the incident optical systems L1 and L2 according to the present embodiment, the luminous flux is obliquely incident on the deflection surface 51 at an incident angle of ± 2.2 ° in the sub-scanning cross section. As a result, the light flux emitted from each of the incident optical systems L1 and L2 can be separated from each other and guided, and the different scanned surfaces 71 and 72 can be light-scanned. At this time, as in the present embodiment, the same optical member can be adopted in each optical path by configuring the incident optical systems L1 and L2 so that the absolute values of the incident angles in the sub-scanning cross sections are equal to each other. It will be possible. Further, in the main scanning cross section, the incident optical systems L1 and L2 obliquely incident the luminous flux at the incident angles of 78 ° and 84 ° with respect to the deflection surface 51, respectively.

By arranging the incident optical systems L1 and L2 so that the incident angles in the main scanning cross section are different from each other in this way, as shown in FIG. 7, while avoiding interference between the light source 11 and the light source 12, each of them The interval in the sub-scanning direction can be reduced. Further, according to this configuration, the incident angle in the sub-scanning cross section of the incident optical systems L1 and L2 can be made as small as possible, so that even if the eccentricity or tilt of each deflection surface in the deflector 5 varies, it is covered. It is possible to suppress the occurrence of pitch unevenness of scanning lines on the scanning surface.

Then, as shown in FIGS. 5 (b) and 7 (a), the incident light flux LL1 guided to the deflection surface 51 of the deflector 5 by the incident optical system L1 serves as a light flux DL at a certain deflection angle, and is a light receiving unit 8 Incident in. At this time, since the incident optical system L1 is an oblique incident system in the sub-scanning cross section, the incident optical system L1 and the light receiving unit 8 can be arranged close to each other. Specifically, in this embodiment, since α1 = 2.2 ° and β = 1.5 °, the above-mentioned conditional expressions (1) to (5) are satisfied. As a result, the space for arranging the light receiving portion 8 can be reduced in the main scanning cross section.

Further, in this embodiment, the incident angle in the main scanning cross section of the incident optical system L1 is 78 °, and the incident angle in the main scanning cross section of the light receiving unit 8 is 76.5 °. As shown in FIG. 5, the sensor 82. Is arranged on the scanning downstream side (downstream side in the rotation direction of the deflector 5) with respect to the light source 11. As a result, compared with the case where the sensor 82 is arranged on the upstream side of the light source 11, synchronous detection can be performed at a position closer to the writing position in the main scanning direction on the scanned surface, so that the detection error can be reduced. Can be done. Further, it is possible to prevent the luminous flux DL from being kicked by the deflection surface 51.

Here, in this embodiment, the optical path length from the light source 11 to the deflection surface 51 is 166 mm. Therefore, the separation distance between the centers of the light source 11 and the synchronization detection sensor 82 in the sub-scanning direction is √ (((166 mm × sin (2.2 °)) × 2) ^ 2 + (166 mm × sin (1.5 °)). ^ 2))) = 13.5 mm. Since the sizes of the light source 11 and the sensor 82 are the same as those in the first embodiment, interference between the light source 12 and the sensor 82 does not occur as shown in FIG. 7B.

If necessary, the light source 12 and the sensor 82 are arranged side by side in the sub-scanning direction so that the incident angles in the main scanning cross section of the incident optical system L2 and the light receiving unit 8 are the same as in the first embodiment. You may. In this embodiment, the cylinder lenses 41 and 42 and the synchronization detection lens 81 are integrally molded in order to reduce the number of parts, but each may be separately arranged if necessary.

In this embodiment, the writing timing on each of the first scanned surface 71 and the second scanned surface 72 is determined based on the synchronization signal generated by receiving the light flux from the light source 11 by the light receiving unit 8. However, it is not limited to this. For example, the writing timing on each surface to be scanned may be determined based on the synchronization signal generated by receiving the light flux from the light source 12 by the light receiving unit 8. Alternatively, the writing timing on the corresponding surface to be scanned may be determined based on each of the synchronization signals generated by receiving the light flux from each of the light source 11 and the light source 12 by the light receiving unit 8.

Further, in the optical scanning apparatus 300 according to the present embodiment, another set of members other than the deflector 5 shown in FIGS. 5A and 6 is arranged (opposed) on the opposite side to the deflector 5. You may. As a result, a tandem type optical scanning device capable of lightly scanning two scanned surfaces by one deflection surface 51 and at the same time lightly scanning the other two scanned surfaces by another deflection surface. Can be configured. At this time, the writing timing on each of the four scanned surfaces can be determined based on the synchronization signal generated by receiving the light flux from at least one of the four light sources by the light receiving unit 8.

[Example 3]
Hereinafter, the optical scanning apparatus 700 according to the third embodiment of the present invention will be described in detail. FIG. 8 is a schematic view (main scanning sectional view) of a main part of the optical scanning apparatus 700 according to the present embodiment. Further, FIG. 9 is a schematic view (sub-scanning sectional view) of a main part of the incident optical system L included in the optical scanning apparatus 700. In FIG. 9, the optical path is developed so that the optical axis direction of the incident optical system L coincides with the optical axis direction (X direction) of the imaging optical system 6 in FIG. 8, and only the main ray is omitted, omitting the marginal ray. Is shown.

The configuration of the optical scanning apparatus 700 according to this embodiment is the same as the configuration according to the first embodiment described above. That is, each numerical value such as the optical arrangement of the incident optical system L according to the present embodiment is the same as that shown in Table 3 according to the first embodiment. Further, each numerical value such as the optical arrangement of the imaging optical system 6 according to this embodiment and the shape data of each lens surface of the imaging lens are the same as those shown in Tables 1 and 2 according to Example 1. .. However, in FIG. 8, the light receiving unit 8 is omitted for convenience.

In the main scanning cross section (inside the XY cross section), the incident optical system L according to the present embodiment is outside the region to be scanned (the region through which the scanning light flux for light scanning the surface to be scanned 7 passes) for the light flux from the light source 1. Is incident on the deflection surface 51. Further, the incident optical system L is an obliquely incident system in which the light flux from the light source 1 is obliquely incident on the deflection surface 51 (incident diagonally with respect to the main scanning cross section) in the sub-scanning cross section (inside the ZX cross section). As a result, it is possible to prevent the light flux deflected by the deflection surface 51 from returning to the light source 1.

Therefore, the timing at which the luminous flux deflected by the deflection surface 51 faces the light source 1 in the main scanning cross section, that is, the luminous flux from the incident optical system L in the main scanning cross section is vertically incident on the deflection surface 51 (direct incident). It is possible to make the light source 1 emit light at the timing before and after the operation. Then, by receiving the light beam emitted from the light source 1 at that timing by the light detection unit (light receiving unit) 15, the light amount control can be performed based on the detection signal output from the light detection unit 15.

As described above, according to the optical scanning apparatus 700, in the conventional configuration, the light source 1 is made to emit light even at the timing when the light flux reflected by the deflection surface returns to the light source, so that the time for detecting and controlling the amount of light is sufficient. It is possible to secure the light intensity and control the amount of light with high accuracy.

The light source 1 according to the present embodiment is a semiconductor laser as an end face emitting laser, and at the same time as emitting a front luminous flux toward the deflector 5, the rear side of the substrate is directed toward the side opposite to the deflector 5. It emits a luminous flux. In this embodiment, the front luminous flux is used as the scanning luminous flux (the luminous flux for light-scanning the scanned surface 7 to form an image), and the rear luminous flux is used as the detection luminous flux for controlling the amount of light.

Next, the light amount control in the optical scanning apparatus 700 according to this embodiment will be described in detail.

In the optical scanning device 700, the light flux emitted from the light source 1 is detected by the photodetector 15, and the obtained detection signal is fed back to the drive circuit of the light source 1 to automatically control the intensity of the luminous flux emitted from the light source 1. The method (auto power control: APC) is adopted. As a result, the output (amount of emitted light) of the light source 1 can be controlled so as to be always equal to the design value, so that stable image formation can be performed regardless of the temperature change.

As described above, in this embodiment, an end face emitting laser is used as the light source 1, and the photodetector (light flux detecting element) as the photodetector 15 arranged in the laser package emits light from the back side of the laser substrate. It has a configuration that detects the rear luminous flux. Then, the light amount control unit (APC unit) 13 controls the light amount based on the detection signal output from the light detection unit 15. As the light amount control unit 13, a processor such as a CPU or MPU can be adopted.

As shown in FIG. 9, the incident luminous flux (front luminous flux) LL emitted from the light source 1 and incident on the deflection surface 51 is an incident optical system when the deflection surface 51 has a specific deflection angle in the main scanning cross section. It is deflected toward the L side. Here, since the incident optical system L obliquely incidents the incident luminous flux LL with respect to the deflection surface 51 at an incident angle of 3 ° in the sub-scanning cross section, the deflection luminous flux DL deflected by the deflection surface 51 is incident. Instead of returning to the optical system L, it is deflected downward and is shielded by a light-shielding portion (not shown).

As described above, in this embodiment, by using the incident optical system L as the oblique incident system, it is possible to prevent the deflected luminous flux DL from returning to the light source 1 and reducing the accuracy of the light amount control. Therefore, the timing before and after the incident light flux LL vertically incident on the deflection surface 51 in the main scanning cross section, that is, the incident light flux LL and the deflection light flux DL (the optical axis of the incident optical system L and the surface normals of the deflection surface 51) are mutually exclusive. The light source 1 can be made to emit light even at the timing before and after the overlap.

FIG. 10 is a time chart showing the light emission timing of the light source, the upper figure of FIG. 10 shows the time chart according to the comparative example, and the lower figure of FIG. 10 shows the time chart according to the present embodiment. In the comparative example, it is assumed that the light intensity is controlled by a conventional optical scanning apparatus in which the incident optical system is not the oblique incident system. As shown in FIG. 10, the light intensity control needs to be performed before the light flux reaches the scanned region (effective scanning region) on the scanned surface. This is because if the light amount is controlled while the luminous flux passes through the area to be scanned, the density of the formed image becomes non-uniform due to the change in the light amount.

In the comparative example, as shown in the upper figure of FIG. 10, the light source stops emitting light at the timing when the light flux reflected by the deflection surface returns to the light source (the timing before and after the light flux is vertically incident on the deflection surface). There is a need to. Therefore, it is not possible to secure a sufficient time for detecting and controlling the amount of light, and the time for detecting and controlling the amount of light is divided before and after that timing, resulting in discontinuity. Therefore, highly accurate light amount control Becomes difficult.

On the other hand, in this embodiment, as shown in the lower figure of FIG. 10, the light source can be made to emit light at the timing before and after the light flux is vertically incident on the deflection surface. Therefore, it is possible to continuously detect and control the amount of light for a sufficiently sufficient time from before the timing at which the luminous flux is vertically incident on the deflection surface to after that timing.

[Example 4]
Hereinafter, the optical scanning apparatus 800 according to the fourth embodiment of the present invention will be described in detail. Unlike the optical scanning device 700 according to the third embodiment, the optical scanning device 800 according to the present embodiment includes a synchronization detection unit 8 and has a configuration capable of simultaneously performing light amount control and synchronization detection. FIG. 11 is a schematic view of a main part of the incident optical system L and the synchronization detection unit 8 included in the optical scanning apparatus 800. The upper view of FIG. 11 shows a sub-scanning sectional view, and the lower view of FIG. 11 shows a front view. There is. The configuration of the optical scanning device 800 is the same as the configuration of the optical scanning device 700 except for the synchronization detection unit 8.

The synchronization detection unit 8 according to the present embodiment receives light from the synchronization detection lens (synchronization detection optical element) 81 that guides and concentrates the deflection light flux DL deflected by the deflection surface 51, and the light flux from the synchronization detection lens 81. It has a synchronization detection sensor (synchronization detection light receiving element) 82 that generates a synchronization signal. In this embodiment, the synchronization control unit 14 determines the writing position in the main scanning direction on the scanned surface 7 based on the synchronization signal output from the synchronization detection sensor 82.

As shown in the upper part of FIG. 11, in this embodiment, the condenser lens 3 (first optical element) and the synchronization detection lens 81 (second optical element) are integrally integrated in order to reduce the number of parts. Although they are molded (integrated), they may be arranged separately if necessary. Further, in this embodiment, by mounting the light source 1 and the synchronization detection sensor 82 on the same substrate, the number of parts is reduced and the deviation of the relative positions of the respective parts is suppressed. The numerical values such as the optical arrangement of the synchronization detection unit 8 according to the present embodiment are the same as those shown in Table 4 according to the first embodiment.

As shown in the upper part of FIG. 11, the incident luminous flux LL emitted from the light source 1 and incident on the deflection surface 51 is deflected downward of the incident optical system L at a certain deflection angle. Then, as shown in the lower figure of FIG. 11, in this embodiment, the incident optical system L and the synchronous detection unit 8 are arranged side by side in the sub-scanning direction so that the incident angles in the sub-scanning cross section are the same as each other. Therefore, the deflected luminous flux DL is incident on the synchronization detection unit 8.

As described above, according to the present embodiment, it is possible to perform synchronous detection using the front luminous flux emitted from the light source 1 at the same time as controlling the amount of light using the rear luminous flux emitted from the light source 1. At this time, since the incident optical system L is an oblique incident system, it is possible to perform light quantity control and synchronous detection at the timing before and after the incident luminous flux LL is vertically incident on the deflection surface 51 in the main scanning cross section. ..

Further, by arranging the incident optical system L and the synchronization detection unit 8 side by side in the sub-scanning direction, the space for arranging the synchronization detection unit 8 can be reduced in the main scanning cross section. As a result, since the scanning angle of view of the deflector 5 can be widened, the distance between the imaging optical system 6 and the surface to be scanned 7 can be shortened, and the entire device can be miniaturized. .. Further, by adopting the above configuration, the incident optical system L and the synchronization detection unit 8 can be arranged at a position closer to the imaging optical system 6, so that the error between the scanning luminous flux and the deflecting luminous flux DL can be reduced. It is possible to perform synchronization detection with high accuracy.

Here, in order to sufficiently reduce the size of the entire device, as in this embodiment, the light source 1 and the synchronization detection sensor 82 overlap each other in the main scanning cross section, that is, the incident luminous flux LL and the deflected luminous flux DL are arranged. It is preferable to configure them to match. The term "match" here means not only when the main rays of the incident luminous flux LL and the deflected luminous flux DL are exactly the same in the main scanning cross section, but also when both luminous fluxes overlap over the entire optical path. It also includes cases where there is a "substantial match", such as when there is. However, the present invention is not limited to this configuration, and the light source 1 and the synchronization detection sensor 82 may be staggered in the main scanning cross section as needed.

[Example 5]
Hereinafter, the optical scanning apparatus 900 according to the fifth embodiment of the present invention will be described in detail. Unlike the optical scanning apparatus 700 according to the third embodiment, the optical scanning apparatus 900 according to the present embodiment employs a surface emitting laser as the light source 16 and controls the amount of light using the light flux separated by the optical separating element 9. ing. FIG. 12 is a schematic view (main scanning cross-sectional view) of a main part of the optical scanning device 900 according to the present embodiment, and FIG. 13 is a schematic view (sub-scanning cross section) of a main part of the incident optical system L included in the optical scanning device 900. Figure).

When a surface emitting laser is used as the light source 1, the rear luminous flux is not emitted from the back side of the substrate unlike the end surface emitting laser. Therefore, in order to control the amount of light, the surface emitting laser is moved to the deflection surface 51. It is necessary to separate and detect the luminous flux emitted toward it. Therefore, in this embodiment, a half mirror as an optical separation element 9 is arranged in the optical path between the condenser lens 3 and the deflection surface 51, and the luminous flux from the light source 1 is directed toward the deflection surface 51 (transmitted luminous flux). ) And the luminous flux toward the light detection unit 15 (reflected luminous flux). As a result, the light amount can always be detected by the light detection unit 15, so that highly accurate light amount control can be performed.

In this embodiment, the condenser lens 10 for condensing the reflected light beam from the light separation element 9 on the light receiving surface of the light detection unit 15 is provided, but if necessary, the condensing lens 3 and the condensing lens 3 are collected. The optical lens 10 may be integrally formed. Further, the optical separation element 9 is not limited to a half mirror, and if necessary, a beam splitter in which the intensities of the transmitted luminous flux and the reflected luminous flux are different from each other, and a wedge-shaped prism in which the incident surface and the emitted surface are non-parallel ( A wedge prism) or the like may be used. Further, also in this embodiment, as in the fourth embodiment, by providing the synchronization detection sensor on the substrate on which the light source 1 and the light detection unit 15 are mounted, the light amount control and the synchronization detection can be performed at the same time. It may be.

[Image forming device]
FIG. 8 is a schematic view (ZX sectional view) of a main part of the image forming apparatus 600 according to the embodiment of the present invention. The image forming apparatus 600 is a tandem type color image forming apparatus that records image information on the photosensitive surfaces (scanned surfaces) of four photosensitive drums (photoreceptors) in parallel by the optical scanning apparatus 500.

The image forming apparatus 600 is fixed to the printer controller 530, the optical scanning apparatus 500, the photosensitive drums 210, 220, 230, 240 as image carriers, the developing devices 310, 320, 330, 340, and the transport belt 510. It is equipped with a container 540. As the optical scanning device 500, a configuration including four optical scanning devices according to the first embodiment or a configuration including two optical scanning devices according to the second embodiment can be adopted. At this time, the optical scanning device 500 is arranged so that the main scanning direction coincides with the Y-axis direction in FIG. 8 and the sub-scanning direction coincides with the respective rotation directions (circumferential directions) of the photosensitive drums 210 to 240.

As shown in FIG. 8, each color signal of R (red), G (green), and B (blue) is output from the external device 520 such as a personal computer. Each color signal is converted into Y (yellow), M (magenta), C (cyan), and K (black) image data (dot data) by the printer controller 530 and input to the optical scanning device 500. The printer controller 530 not only converts the signals described above, but also controls each part of the image forming apparatus 600 such as a motor described later.

The optical scanning device 500 lightly scans the photosensitive surface of the photosensitive drums 210 to 240 in the main scanning direction (Y direction) by each of the luminous fluxes 410, 420, 430, and 440 modulated according to each image data. Each of the photosensitive drums 210 to 240 is rotated clockwise by a motor (not shown), and each photosensitive surface moves in the sub-scanning direction (circumferential direction) with respect to the luminous flux 410 to 440 with this rotation. Each of the luminous fluxes 410 to 440 exposes each photosensitive surface charged by a charging roller (not shown), so that an electrostatic latent image is formed on each photosensitive surface.

After that, the electrostatic latent image of each color formed on each photosensitive surface of the photosensitive drums 210 to 240 is developed as a toner image of each color by each of the developers 310 to 340. Then, the toner images of each color are multiple-transferred to the transfer material conveyed by the transfer belt 510 by a transfer device (not shown), and then fixed by the fixer 540. By the above steps, one full-color image is formed.

The optical scanning apparatus 500 may be configured to include at least the incident optical system and the light receiving unit according to each embodiment. For example, a tandem type optical scanning device that optically scans four scanned surfaces with one deflector. The device may be adopted. Further, a color digital copying machine may be configured by connecting a color image reading device including a line sensor such as a CCD sensor or a CMOS sensor to the image forming device 600 as an external device 520.

[Modification example]
Although the preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications and modifications can be made within the scope of the gist thereof.

For example, in Examples 1 to 4 described above, a semiconductor laser having only one light emitting point is adopted as a light source, but the present invention is not limited to this. If necessary, a monolithic multi-beam laser having a plurality of light emitting points may be adopted to adopt a configuration capable of forming an image on the surface to be scanned at high speed. As a laser having a plurality of light emitting points, a vertical resonator type surface emitting laser (VCSEL) or the like can be adopted. In addition, VCSEL may be adopted in Example 5. Further, the number, materials, and shapes of the imaging optical elements constituting the imaging optical system may be changed according to the configuration of the optical scanning apparatus.

In the second embodiment, two planes to be scanned are light-scanned by one deflection plane, but the present invention is not limited to this, and light from three or more incident optical systems is deflected by one deflection plane to three. The surface to be scanned may be configured to lightly scan. Alternatively, a configuration may be adopted in which a plurality of scanned surfaces are lightly scanned by a plurality of deflection surfaces. When a configuration including a plurality of incident optical systems is adopted, members such as an optical element and an aperture diaphragm in each optical path may be integrated as in the first embodiment.

Further, the imaging lenses may be individually arranged in each optical path from the deflection surface to the plurality of scanned surfaces, or the imaging lenses may be integrated and shared by the optical paths. Further, in the second embodiment, only one light receiving unit corresponding to one light source is provided, and the emission timing of the plurality of light sources is controlled by using the synchronization signal, but the plurality of light sources corresponding to each of the plurality of light sources is controlled. The light receiving portion of the above may be provided. Further, when a light source having a plurality of light emitting points is adopted, the light emitting timing of the other light emitting points may be controlled based on the synchronization signal obtained by detecting only the luminous flux from one light emitting point. The luminous flux from each light emitting point may be individually detected and controlled.

In the above-described first and second embodiments, the configuration in which the control circuit for determining the writing position in the main scanning direction on the surface to be scanned is mounted in the optical scanning device has been described, but the present invention is not limited to this. The control circuit may be mounted inside the image forming apparatus but outside the optical scanning apparatus. In this case, a control circuit may be provided in the printer controller included in the image forming apparatus.

When a multi-beam laser is adopted, it is not possible to control all the light quantities of a plurality of light emitting points at the same time. Therefore, it is necessary to sequentially detect each of the plurality of luminous fluxes and control the light quantity of each light emitting point. Therefore, when the multi-beam laser is applied to the above-mentioned comparative example, it is not possible to secure a sufficient time for detecting and controlling the amount of light in one scan, so how many times it takes to finish controlling the amount of light at all the light emitting points. It is also necessary to perform optical scanning, which increases the total time for controlling the amount of light. On the other hand, when the multi-beam laser is applied to Examples 3 to 5, it is possible to secure a sufficient time for controlling the amount of light within one scan, so that the total time for controlling the amount of light can be shortened.

Further, in Examples 3 and 4, the rear luminous flux emitted from the end face emitting laser is detected to control the light amount, but if necessary, the front luminous flux is detected and the light amount is controlled. May be good. At that time, for example, in the third embodiment, the optical detection unit may be provided at the position where the synchronization detection sensor according to the fourth embodiment is arranged, or in the fourth embodiment, the same as the synchronization detection sensor so as to be adjacent to the same. A photodetector may be provided on the substrate. Alternatively, as in the fifth embodiment, the front luminous flux may be separated and detected by an optical separation element. Further, in Examples 3 to 5, the photodetector may be used as a synchronization detection sensor to perform synchronization detection based on a signal from the photodetector, or light amount detection and synchronization detection may be simultaneously performed by one photodetector. You may.

In Examples 3 to 5, the light emission timing control of the light source may be performed by a control unit provided inside the light source, or may be performed by a control unit provided outside. Further, the light amount control unit and the synchronous control unit may be arranged inside the optical scanning device or may be arranged inside the image forming device. At this time, one control unit may be configured to perform at least one of light quantity control, synchronization control, and light emission timing control of the light source.

In Examples 3 to 5, one surface to be scanned is lightly scanned by a light flux from one light source, but the present invention is not limited to this, and a plurality of surfaces to be scanned are lightly scanned by light fluxes from a plurality of light sources. The configuration may be adopted. At this time, a configuration in which a plurality of light fluxes are deflected simultaneously by one deflection surface may be adopted, or a configuration in which a plurality of light fluxes are deflected by a plurality of deflection surfaces may be adopted. At this time, the imaging lenses may be individually arranged in each optical path from the deflection surface to the plurality of scanned surfaces, or the imaging lenses may be integrated and shared by the optical paths. ..

5 Deflection device 7 Scanned surface 51 Deflection surface L Incident optical system 8 Light receiving unit 100 Optical scanning device

Claims (28)

A deflector that deflects the luminous flux and scans the surface to be scanned in the main scanning direction,
An incident optical system that obliquely incidents a luminous flux on the first deflection surface of the deflector in the sub-scanning cross section,
An imaging optical system having an fθ characteristic and guiding a luminous flux deflected by the first deflection surface to the scanned surface.
A light receiving unit that receives a light flux deflected by the first deflection surface and generates a first signal is provided.
The imaging optical system is arranged between the deflector and the scanned surface.
The angle of incidence of the luminous flux from the incident optical system in the sub-scanning section with respect to the first deflection surface is α (deg), and the luminous flux incident on the first deflection surface in the main scanning cross section and the first deflection surface. When the angle formed by the luminous flux directed to the light receiving portion is β (deg).
｜ β ｜ ≦ ｜ α ｜
An optical scanning device characterized by satisfying the above conditions. 1.5 ≤ | α | ≤ 10
0 ≦ ｜ β ｜ ≦ 5.0
The optical scanning apparatus according to claim 1, wherein at least one of the above conditions is satisfied. 1.5 ≤ | α | ≤ 5.0
0 ≤ | β | ≤ 3.0
The optical scanning apparatus according to claim 1, wherein at least one of the above conditions is satisfied. Any one of claims 1 to 3, wherein the luminous flux incident on the first deflection surface and the luminous flux deflected by the first deflection surface and directed toward the light receiving portion coincide with each other in the main scanning cross section. The optical scanning apparatus according to paragraph 1. The optical scanning apparatus according to any one of claims 1 to 3, wherein the light receiving unit is arranged on the downstream side of the incident optical system in the rotation direction of the deflector. In the main scanning cross section, the optical path between the incident optical system and the first deflection surface and between the first deflection surface and the light receiving portion is an optical path in which the main ray of the luminous flux is neither refracted nor reflected. The optical scanning apparatus according to any one of claims 1 to 5, wherein the optical scanning apparatus is provided. The incident optical system includes a first optical element that collects a light beam, the light receiving unit includes a second optical element that collects a light beam, and the first and second optical elements are integrally formed with each other. The optical scanning apparatus according to any one of claims 1 to 6, wherein the optical scanning apparatus is characterized. Any of claims 1 to 7, wherein the light receiving unit includes a photoelectric conversion element that emits a light beam, and the light source and the photoelectric conversion element are mounted on the same substrate. The optical scanning apparatus according to item 1. The optical scanning apparatus according to any one of claims 1 to 8, wherein the incident optical system and the imaging optical system do not include a common optical element integrally formed with each other. The optical scanning apparatus according to any one of claims 1 to 9, wherein the incident optical system includes an optical element arranged apart from the imaging optical system. The optical scanning apparatus according to claim 10, wherein the optical element is arranged between the deflector and the imaging optical system in the optical axis direction of the imaging optical system. Any one of claims 1 to 11, wherein a plurality of incident optical systems are provided, and the first deflecting surface deflects light fluxes from the plurality of incident optical systems to scan a plurality of scanned surfaces. The optical scanning apparatus according to the section. The optical scanning apparatus according to claim 12, wherein the incident angles of the light fluxes from the plurality of incident optical systems with respect to the first deflection surface are different from each other in the main scanning cross section. The optical scanning apparatus according to claim 12 or 13, wherein the absolute values of the incident angles of the light fluxes from the plurality of incident optical systems with respect to the first deflection plane are equal to each other in the sub-scanning cross section. The plurality of incident optical systems include a common optical element integrally formed, and the common optical element guides a light flux deflected by the first deflection surface to the light receiving portion. Item 2. The optical scanning apparatus according to any one of Items 12 to 14. The optical scanning apparatus according to any one of claims 1 to 15, wherein the first signal is a signal for determining a writing position in the main scanning direction on the surface to be scanned. The optical scanning apparatus according to any one of claims 1 to 16, further comprising a control circuit for determining a writing position in a main scanning direction on the surface to be scanned based on the first signal. The incident optical system includes a light source that emits a luminous flux, and the luminous flux is incident on the first deflection surface from the outside of the area to be scanned in the main scanning cross section, and the light source is said in the main scanning cross section. The optical scanning apparatus according to any one of claims 1 to 17, wherein the light flux is emitted at a timing when the light flux from the incident optical system is perpendicularly incident on the first deflection surface . The optical scanning apparatus according to claim 18, further comprising a photodetector that receives a light flux emitted from the light source at the timing and generates a second signal. The optical scanning apparatus according to claim 19, wherein the photodetector continuously receives a light beam from before the timing to after the timing. The optical scanning apparatus according to claim 19 or 20, further comprising a light amount control unit that controls the amount of emitted light of the light source based on the second signal. The optical scanning device according to claim 21, wherein the light amount control unit does not control the amount of emitted light emitted from the light source while the light flux emitted from the light source passes through the area to be scanned. The optical scanning apparatus according to any one of claims 19 to 22, wherein the photodetector receives a light flux emitted from the light source to a side opposite to the first deflection surface at the timing. .. The optical scanning apparatus according to any one of claims 19 to 22, wherein the photodetector receives a light flux reflected by the first deflection surface at the timing. The invention according to any one of claims 19 to 24, which comprises an optical separation element that separates a light flux from the light source into a light flux toward the first deflection surface and a light flux toward the light detection unit. Optical scanning device. The method according to any one of claims 19 to 25, wherein the light receiving unit receives a light flux reflected by the first deflection surface at the timing to generate the first signal. Optical scanning device. The optical scanning device according to any one of claims 1 to 26, a developer that develops an electrostatic latent image formed on the surface to be scanned by the optical scanning device as a toner image, and the developed toner. An image forming apparatus including a transfer device for transferring an image to a transfer material and a fixing device for fixing the transferred toner image to the transfer material. The optical scanning apparatus according to any one of claims 1 to 26, and a printer controller that converts a color signal output from an external device into image data and inputs the color signal to the optical scanning apparatus. Image forming device.

Images