KR20170013161A - Optical scanning device and image forming apparatus including the same - Google Patents

Abstract

The present invention relates to an optical scanning device and an image forming apparatus including the same. The optical scanning device according to the present invention comprises: a deflection unit which has a deflection side and deflects a light flux to scan a non-scanning side in a main scanning direction; an incidence optical system disposed for the light flux to obliquely come into the deflection side in a sub scanning section; and a light receiving unit which is disposed to generate a signal by receiving the light flux deflected by the deflection side. The following condition, which is <=, is fulfilled wherein (deg) is an incidence angle of the light flux for the deflection side in the sub scanning section, and (deg) is an angle formed by a light flux came into a deflection side in the main scanning section and a light flux oriented towards the light receiving unit by being deflected by the deflection side.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical scanning apparatus and an image forming apparatus including the optical scanning apparatus.

The present invention relates to an image forming apparatus such as a laser beam printer (LBP), a digital copying machine, or a multifunction printer (multifunction printer); And an optical scanning apparatus included in the image forming apparatus.

As an optical scanning apparatus included in an image forming apparatus, an optical scanning apparatus for deflecting a light beam from a light source by a deflection unit and optically scanning the surface to be scanned in the main scanning direction is known. In this optical scanning apparatus, in order to optically scan the surface to be scanned with high precision, a synchronous detection unit for detecting a light beam deflected by the deflecting unit and determining a write-start position in the main scanning direction on the scan surface .

Japanese Patent Laid-Open Publication No. 2009-115943 discloses a configuration in which a light flux from a light source is separated by a beam splitting element, and the light flux is guided to the surface to be scanned and the synchronization detection unit, respectively. Further, Japanese Patent Application Laid-Open No. 2007-298997 discloses a configuration in which a light flux passing through an end of an imaging lens is reflected by using a mirror, and the light flux is guided to the synchronization detection unit.

However, in the structures of Japanese Patent Application Laid-Open No. 2009-115943 and Japanese Patent Application Laid-Open No. 2007-298997, a beam splitter and a mirror are required, so that the apparatus can be complicated, High-precision synchronous detection may no longer be performed. In addition, in the configurations of Japanese Patent Application Laid-Open No. 2009-115943 and Japanese Patent Application Laid-Open No. 2007-298997, since each member needs to be disposed so that the light beam directed toward the surface to be scanned is not blocked in the main- Is not sufficiently miniaturized.

The present invention provides an optical scanning apparatus and an image forming apparatus capable of achieving high-precision synchronous detection and size reduction by a simple configuration.

A deflection unit having a deflecting surface and arranged to optically scan the surface to be scanned in a main scanning direction while deflecting the light beam; An incident optical system arranged such that the light flux enters the deflecting surface in the sub-scan section; And a light receiving unit arranged to receive a light beam deflected by the deflecting surface and generate a signal. The following conditions are satisfied,

| β | ? |? |,

(Deg) is the angle of incidence of the light beam from the incident optical system on the deflecting surface in the sub-scan section, and? (Deg) is deflected by the light beam incident on the deflecting surface in the main-scan section and the deflecting surface And an angle formed by a light flux directed toward the light receiving unit.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a main part of an optical scanning apparatus according to a first embodiment of the present invention. Fig.
2 is a main scanning sectional view of the optical scanning device according to the first embodiment of the present invention.
Fig. 3 provides a schematic view of essential parts of an incident optical system and a light receiving unit according to Embodiment 1 of the present invention.
4 is a diagram showing the light emission timing of the light source according to the first embodiment of the present invention.
5 shows a main scanning sectional view of an optical scanning apparatus according to Embodiment 2 of the present invention.
6 is a sub-scan sectional view of the optical scanning device according to the second embodiment of the present invention.
Fig. 7 is a schematic view of a main portion of an incident optical system and a light receiving unit according to Embodiment 2 of the present invention. Fig.
8 is a main scanning sectional view of the optical scanning device according to the second embodiment of the present invention.
9 is a sub-scan sectional view of an incident optical system according to Embodiment 3 of the present invention.
Fig. 10 provides a diagram showing the light emission timings of the light source according to the third embodiment and the comparative example of the present invention.
Fig. 11 is a schematic view of essential parts of an incidence optical system and a synchronization detecting unit according to Embodiment 4 of the present invention.
12 is a main scanning sectional view of an optical scanning apparatus according to Embodiment 5 of the present invention.
13 is a sub-scan sectional view of an incident optical system according to Embodiment 5 of the present invention.
14 is a sub-scan sectional view of the image forming apparatus according to the embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Each of the drawings may be shown at different scales from the actual scale for ease of understanding. In the drawings, the same reference numerals are given to the same members, and redundant explanations are omitted. In the following description, the main scanning direction is a direction in which the deflection unit optically scans the surface to be scanned. In this case, the main scanning direction corresponds to the direction perpendicular to the rotation axis (or swing axis) of the deflection unit and the optical axis direction. The sub-scanning direction is a direction intersecting the main scanning direction. In this case, the sub-scan direction corresponds to a direction parallel to the rotation axis (or swing motion axis) of the deflection unit. The main-scan cross-section includes an optical axis and is parallel to the main-scan direction. In this case, the main-scan section is also perpendicular to the sub-scan direction. The sub-scan section is a section including an optical axis and parallel to the sub-scan direction. In this case, the sub-scan section is also a section perpendicular to the main scan direction.

Fig. 1 provides a schematic view of the main part of the optical scanning apparatus 100 according to the first embodiment of the present invention. 1 schematically shows a main scanning section of the optical scanning apparatus 100. As shown in FIG. 1 schematically shows a sub-scan section of a portion including an incident optical system L, a deflection unit 5, and a light-receiving unit 8 included in the optical scanning apparatus 100. As shown in Fig. FIG. 1 shows only the principal ray of the light beam, omitting the marine rays. 1, the optical path extends 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 the left drawing of Fig.

The optical scanning apparatus 100 according to the present embodiment deflects the light beam by the deflection unit 5 and optically scans the scan surface 7 in the main scanning direction B. [ As the deflection unit 5, there is shown a rotary polygonal mirror (polygon mirror) having a plurality of deflecting surfaces (reflecting surfaces) 51 that rotate around a rotation axis. Instead of this, It is possible to use a swinging mirror having one or two deflecting surfaces. The deflection unit 5 is rotated at a constant speed (constant angular velocity) in the direction indicated by the arrow A by a drive unit (not shown) composed of a motor or the like.

The incident optical system L according to the present embodiment has a configuration in which the light beam is incident on each of the deflecting surfaces 51 of the deflecting unit 5 in the sub-scan section as shown in the right- (I.e., oblique incidence with respect to each other). The incident optical system L according to the present embodiment includes only a light source, but if necessary, the incident optical system L may include an optical element for guiding the light flux from the light source to the deflecting surface 51 and an aperture stop . Alternatively, the incident optical system L may guide the light beam from the light source disposed outside the optical scanning apparatus 100. [

The light receiving unit 8 receives the light beam deflected by the deflecting surface 51 and generates a signal. Synchronous detection for determining the recording-start position in the main scanning direction on the scan surface 7 and control of the amount of light emitted from the light source can be performed based on the signal generated by the light receiving unit 8. [ The light receiving unit 8 according to the present embodiment is constituted by only a photoelectric conversion element and a light receiving element. If necessary, the light receiving unit 8 includes an optical element for guiding the light flux from the deflecting surface 51 to such a light receiving element, May include an aperture. In this embodiment, the light source and the light receiving element are mounted on the same substrate, thereby reducing the number of parts and suppressing the displacement between the relative positions of these members.

In the incident optical system L, a light beam emitted from a light source such as a semiconductor laser is incident on the deflecting surface 51 of the rotating deflecting unit 5. At any rotation angle, the light beam reflected by the deflecting surface 51 enters the light receiving unit 8, is photoelectrically converted, and generates a signal. As the deflection unit 5 further rotates, the light beam reflected by the deflecting surface 51 is incident on the scan surface 7 by the imaging optical system 6. Along with the rotation of the deflecting unit 5, the light flux from the incident optical system L is deflected by the deflecting surface 51 and the scanning surface 7 is scanned in the main scanning direction (Y direction). By using the signal generated in the light receiving unit 8, it is possible to determine the timing of starting the optical scanning on the scan surface 7, that is, the recording-start position, based on the signal. This synchronization detection is performed every time the scanning surface 7 is scanned once. In the case of repeating optical scanning in the main scanning direction while moving the scan surface 7 in the sub scanning direction, synchronization detection can be performed every time a plurality of scanning is performed.

In this case,? (Deg) is an incident angle to the deflecting surface 51 of the light flux from the incident optical system L in the sub-scan section, and? (Deg) And the light beam deflected by the deflecting surface 51 and directed toward the light receiving unit 8. [0050] Each angle is determined with respect to the principal ray of the light beam. At this time, the optical scanning apparatus 100 according to the present embodiment satisfies the following condition (1)

|? |? |? | ... (One)

In the optical scanning apparatus 100 according to the present embodiment, since the incident optical system L is a projection system, the incident optical system L and the light receiving unit 8 can be disposed apart from each other in the sub-scanning direction. Further, since the conditional expression (1) is satisfied, the incident optical system L and the light receiving unit 8 can be arranged close to each other in the main scanning section. Therefore, it is not necessary to dispose a member such as a beam splitter and a mirror described in JP-A-2009-115943 and JP-A-2007-298997 in each optical path. That is, in the main-scan section, the optical path between the incident optical system L and the deflecting surface and the optical path between the deflecting surface and the light receiving unit 8 are optical paths in which the principal ray of the light flux is not refracted or reflected. With this simple configuration, it is possible to achieve highly accurate synchronization detection and size reduction of the entire apparatus.

When the condition (1) is not satisfied, the space occupied by the incident optical system L and the light receiving unit 8 increases in the main-scan section, making it difficult to reduce the size of the entire apparatus. In order to achieve sufficient reduction of the size of the entire apparatus, it is preferable that at least one of the following conditional expressions (2) and (3) is satisfied:

1.5? |? |? 10 (2), and

0? |? |? 5.0 (3).

It is more preferable that the optical scanning apparatus 100 according to the present embodiment satisfies at least one of the following conditional expressions (4) and (5).

1.5? |? |? 5.0 (4), and

0? |? |? 3.0 (5).

Example  One

Hereinafter, the optical scanning device 200 according to the first embodiment of the present invention will be described in detail.

2 is a main scanning sectional view of the optical scanning device 200 according to the present embodiment. 3 provides a schematic view of the main parts of the light-receiving unit 8 and the incident optical system L included in the optical scanning device 200. As shown in Fig. The left side view of FIG. 3 schematically shows a sub-scan section. 3 schematically shows a front view of a module including a light source and a photoelectric conversion element. 3, the optical path is expanded 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. FIG. 3 shows only the principal ray of the light beam while omitting the marginal ray.

The incident optical system L according to the present embodiment includes a light source 1 for emitting a light flux, an aperture stop 2 for shaping a light flux by regulating the light flux from the light source 1, And a condensing lens (condensing optical element) 3 for converting the condensing state (convergence degree) of the light beam. In this embodiment, the light source 1 is a semiconductor laser, and the condenser lens 3 is an anamorphic lens having a different refractive power (power) in the main-scan section and the sub-scan section. The condenser lens 3 converts the divergent light flux emitted from the light source 1 and passed through the aperture stop 2 into a parallel light flux or a convergent light flux in the main-scan section and a convergent light flux in the sub-scan section. The condenser lens 3 can be composed of two optical elements including a collimator lens and a cylinder lens, in which case the two optical elements can be integrated.

The deflecting unit 5 according to the present embodiment is a rotating polygon mirror (polygon mirror) having a plurality of deflecting surfaces (reflecting surfaces) 51 and is constituted by a driving unit (not shown) (Constant angular velocity) in the direction indicated by the arrow. The deflecting unit 5 deflects the light beam guided by the incidence optical system L using the respective deflecting surfaces 51 and optically scans the scan surface 7 in the main scanning direction (the direction indicated by the arrow B). As the deflection unit 5, a swinging mirror that swings at a constant speed can be employed instead of the rotary polygon mirror.

In the optical path from the deflecting unit 5 to the scan surface 7, an imaging optical system 6 formed of an imaging lens (imaging optical element) having a light converging function and f? Characteristic is disposed. This imaging lens is an anamorphic lens formed of a plastic (resin) material or the like and has a positive power on the optical axis in the main scanning section and the sub scanning section. The imaging optical system 6 guides and condenses the light beam deflected by the deflecting unit 5 onto the scan surface 7 to form a spot image. The spot image moves at a constant speed on the scan surface 7 by the f? Characteristic. The imaging optical system 6 compensates the optical surface entanglement error of the deflecting surface 51 by making the deflecting surface 51 and the scan surface 7 conjugate with each other in the sub-scan section.

Table 1 shows respective numerical values such as the optical arrangement of the imaging optical system according to the present embodiment.

The shape (bus shape) in the main-scan section including the surface apexes of the respective lens surfaces (incident surface and exit surface) of the imaging lens according to this embodiment is an aspherical surface that can be represented as a function up to the twelfth order. Concretely, when the intersection point between each lens surface and the optical axis is the origin, the axis in the optical axis direction is the X axis, and the axis perpendicular to the optical axis in the main scanning direction is the Y axis, 6): &lt; RTI ID = 0.0 &gt;

... (6)

... (6)

In this equation, R is the radius of curvature (radius of curvature of the curvature of the curvature) in the main-scan section on the optical axis, and K, B4, B6, B8, B10 and B12 are aspheric coefficients in the main- The shape of each lens surface in the sub-scan section at each position in the main-scan direction (char- acteristic shape) is expressed by the following equations (7) and (8)

... (7)

... (7)

... (8)

... (8)

D ₂ , D ₄ , D ₆ , D ₈ , D ₁₀ , and D ₁₂ are the char- acteristic change coefficients, and r 'is the radius of curvature in the sub-scan section on the optical axis Is the radius of curvature of curvature at the position of height (Y), and M _{j - k} is the aspherical surface coefficient in the sub-scan section. For example, M _{j - 1} is the first term of Z and represents the slope of the lens surface in the sub-scan section (sine tilt). In this embodiment, the amounts of tilt in the main scanning direction are changed using the coefficients of 0, 2, 4, 6, 8, and 10th order.

Table 2 shows shape data of each lens surface of the imaging lens according to this embodiment. The suffix u indicates the same side (upper side) as the light source 1 with respect to each lens surface apex (i.e., optical axis) of the image-forming lens, And the light source 1 and the opposite side (lower side) with respect to the vertex. Coefficients without subscript u or l are coefficients common to the top and bottom.

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

The light receiving unit 8 functions as a synchronization detecting unit which receives the light beam deflected by the deflecting surface 51 and generates a synchronizing signal for determining the recording-start position in the main scanning direction on the scan surface 7. [ The light receiving unit 8 includes a synchronous detection lens (synchronous detecting optical element) 81 for guiding and condensing the light flux DL for synchronous detection deflected by the deflecting surface 51, And a synchronous detection sensor (photoelectric conversion element) 82 for receiving the light flux and outputting a synchronous signal.

The synchronous signal output from the sensor 82 is input to the control circuit (driver) 10 shown in Figs. 2 and 3. The control circuit 10 determines the recording-start position in the main scanning direction on the scan surface 7 based on this synchronization signal. Fig. 4 is a timing chart showing the emission timing of the light source 1 during one rotation of the deflection unit 5. Fig. LD denotes an ON / OFF state of the light source, CLK denotes a clock signal, and DT denotes an output signal of the sensor.

The control circuit 10 causes the light source 1 to start emitting light at time t1 and temporarily stops emitting light at time t2. During this period, when the light flux from the light source 1 is reflected by the deflecting surface 51 and enters the sensor 82, a synchronizing signal is generated at time td. The control circuit counts the clock pulse CLK from the time td and makes the light source 1 ready to emit light (time t3) when the count number reaches a predetermined value. The time required for optical scanning of the effective area of the scan surface 7 (time t3 to time t4) is predetermined. Therefore, during this period, the light source 1 is turned on or off according to the image data, and the scan surface 7 is exposed in a pattern corresponding to one line of image data.

Thus, the recording-start timing in the main scanning direction is determined based on the synchronization signal. Therefore, even if the scanning is repeated, the reproducibility of the recording-start position is maintained. In this embodiment, the synchronization detection is performed every time the scan surface 7 is optically scanned once, and the operation of determining the recording-start timing is repeated.

Table 3 shows the numerical values such as the optical arrangement of the incident optical system L and the like. Table 4 shows the respective numerical values such as the optical arrangement of the light receiving unit 8 and the like.

In Table 3, "the angle of incidence within the main-scan section" represents an angle formed by the principal ray incident on the deflecting surface 51 and the optical axis of the imaging optical system 6 emitted from the incident optical system L in the main-scan section . The incident angles? '' And? '' In the main scanning section and the sub scanning section in Table 4 are deflected by the deflecting surface 51 in each of the main scanning section and the sub scanning section, And an optical axis of the imaging optical system 6, respectively. In the present embodiment,? =? 'And? = -Α'.

3, the incident light flux LL led to the deflecting surface 51 of the deflecting unit 5 by the incidence optical system L is incident on the deflecting surface 51 in a main scanning direction Is deflected toward the incident optical system (L) when it has a deflection angle. In this case, since the incident optical system L inclines the incident light flux LL at an incident angle of 3 degrees with respect to the deflecting surface 51 in the sub-scan section, the incident optical flux L incident on the deflecting surface 51 LL are deflected downward without returning to the incident optical system L. [ In this embodiment, since the incident optical system L and the light receiving unit 8 are arranged in the sub-scan direction so as to have the same incident angle in the main-scan section, the light beam deflected by the deflecting surface 51 is detected as the synchronous detection light flux DL And enters the light receiving unit 8.

As described above, in the present embodiment, since the incident optical system L is a line-by-line system, the incident optical system L and the light receiving unit 8 can be arranged side by side in the sub-scan direction. In the present embodiment, since? = 3 占 and? = 0 占 the above-described conditional expressions (1) to (5) are satisfied. This makes it possible to reduce the space for disposing the light receiving unit 8 within the main scanning section and consequently to enlarge the scanning angle of view of the deflection unit 5 and to reduce the size of the scanning optical system 6 and the scan surface 7 Can be shortened.

Particularly, as in the present embodiment, by arranging the incident light flux LL in the main-scan section to be aligned with the synchronism detecting light flux DL, the entire apparatus can be reduced in size more sufficiently. The expression "Alignment" refers not only to the exact alignment between the incident light flux LL and the positive light fluxes DL of the synchronous detection light flux DL in the main-scan section, but also to "substantial alignment ", such as when both light fluxes overlap each other over the entire light path . However, it is preferable that the principal rays of both the incident light flux LL and the synchronous detection light flux DL are aligned with each other.

Further, by adopting the above-described configuration, the incident optical system L and the light receiving unit 8 can be disposed closer to the imaging optical system 6. This makes it possible to reduce the error between the effective light flux for optically scanning the effective area of the scan surface 7 and the light flux DL for synchronization detection, so that the synchronization detection can be performed with higher accuracy. Unlike the configuration described in Japanese Patent Application Laid-Open No. 2007-298997, it is not necessary to detect the light flux DL through the imaging optical system 6, so that the size of the imaging optical system 6 can be reduced.

In the present embodiment, the condenser lens 3 (first optical element) and the synchronous detection lens 81 (second optical element) are integrally formed (integrated) to reduce the number of parts. However, these lenses can be arranged separately from each other if necessary. In the present embodiment, the light source 1 and the sensor 82 are mounted on the same substrate, thereby reducing the number of parts and suppressing the displacement between the relative positions of these members. The optical path length from the light source 1 to the deflecting surface 51 is substantially equal to the length from the deflecting surface 51 to the synchronism detecting sensor 82. [

The optical path length from the light source 1 to the deflecting surface 51 is 47 mm so that the distance between the light source 1 and the synchronization detecting sensor 82 in the sub scanning direction is 47 mm x sin 3 °)) x 2 = 4.9 mm. 3, the light source 1 has a circular shape with a diameter of 4 mm, and the sensor 82 has a rectangular shape having a length in the main-scan direction of 3 mm and a length in the sub-scan direction of 4 mm. Interference does not occur between the light source 1 and the sensor 82 even when the incident optical system L and the light receiving unit 8 have the same incident angle in the main scanning section.

In the present embodiment, the optical path from the incident optical system L (light source 1) to the deflecting surface 51 or the optical path from the deflecting surface 51 to the light receiving unit 8 (sensor 82) The optical path is not provided with a member for refracting the principal ray of the light beam or a member for reflecting the main ray of the light beam. That is, since the beam splitter or mirror disclosed in Japanese Patent Application Laid-Open No. 2009-115943 and Japanese Patent Application Publication No. 2007-298997 are not disposed, the influence of the placement error of these members is no longer And space for arranging each member so as not to interfere with each other is no longer required.

According to the optical scanning apparatus 200 according to the present embodiment, highly accurate synchronization detection and size reduction can be provided by a simple configuration.

Example  2

Hereinafter, the optical scanning device 300 according to the second embodiment of the present invention will be described in detail. The optical scanning apparatus 300 according to the present embodiment differs from the optical scanning apparatus 200 according to the first embodiment in that the light flux emitted from the two light sources optically scans two different scan surfaces.

5 shows a main scanning section of the optical scanning device 300 according to the present embodiment. 5 schematically shows the incident optical systems L1 and L2 and the light receiving unit 8 in an enlarged manner. 6 schematically shows a sub-scan section of the optical scanning device 300. As shown in Fig. 5, the reflecting members M1 to M3 in the respective optical paths from the deflecting surface 51 to the scan surfaces 71 and 72 are omitted, and each optical path is expanded. 5, light beams other than the principal ray emitted from the light source 11 and a part of the member are omitted.

In this embodiment, the first incident optical system L1 and the second incident optical system L2 are arranged so that the light beams respectively corresponding to the first scan surface 71 and the second scan surface 72, which are different from each other, (51). The first incidence optical system L1 includes a light source 11, a collimator lens 31, a cylinder lens 41, and an aperture stop 21. The second incident optical system L2 includes a light source 12, a collimator lens 32, a cylinder lens 42 and an aperture diaphragm 22. In this embodiment, although the cylinder lenses 41 and 42 are integrated, they can be arranged separately if necessary. Further, the collimator lenses 31 and 32 can be integrated.

In this embodiment, the light sources 11 and 12 are semiconductor lasers. Each of the collimator lenses 31 and 32 has the same refractive power in the main scanning section and the sub scanning section. The collimator lenses 31 and 32 convert the diverging light flux emitted from the light sources 11 and 12 into a parallel light flux in the main scanning section and the sub scanning section. The cylinder lenses 41 and 42 convert the light flux emitted from the collimator lenses 31 and 32 into a convergent light flux in the sub-scan section, respectively. The aperture stops 21 and 22 regulate the light flux emitted from the cylinder lenses 41 and 42, respectively, and form a light flux.

The imaging optical system 6 according to the present embodiment is configured so that the imaging optical system 6 is arranged in the optical path from the deflecting surface 51 to the scan surfaces 71 and 72 to the first imaging lens 61 and the second imaging lens 62). In this embodiment, the first imaging lens 61 is integrated (shared) in each optical path. The imaging lenses 61 and 62 are anamorphic lenses formed of the same plastic material. The first imaging lens 61 has a positive power in the main-scan section on the optical axis and no power in the sub-scan section. Further, the second imaging lens 62 has a negative power in the main-scan section on the optical axis and a positive power in the sub-scan section.

Reflecting members M1 to M3 for bending the light beam and guiding the light beam to the corresponding scan surface are provided between the first imaging lens 61 and the scan surfaces 71 and 72, Dust-preventing glasses 91 and 92 are disposed. The number and arrangement of reflecting members in each optical path are not limited to those shown in Fig. Alternatively, if necessary, the first imaging lens 61 may be separated into two parts and disposed in each optical path, and the second imaging lens 62 may be integrated into each optical path.

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 deflecting surface 51 in the optical scanning apparatus 300 according to the present embodiment, Are simultaneously incident on the slopes (71, 72) at positions corresponding to each other. That is, the recording-start timing by the light flux emitted from the light source 11 and the light source 12 is the same. However, if necessary, the luminous flux may be incident at different incidence positions at the deflecting surface 51, or the write-start timing at each scan surface may be different.

Table 5 shows the numerical values 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 this embodiment. Each value shown in Table 5 is common to two optical paths. The shape of each lens surface of each of the imaging lenses 61 and 62 is expressed by the same definition formula as that of the first embodiment.

Next, the configurations of the incident optical systems L1 and L2 and the light receiving unit 8 according to the present embodiment will be described in detail. Fig. 7 is a schematic view of essential parts of the incident optical systems L1 and L2 and the light receiving unit 8. Fig. The left side view of Fig. 7 schematically shows a sub-scan section. 7 schematically shows a front view of a module including a light source and a photoelectric conversion element. Table 7 shows the numerical values such as the optical arrangement of the incident optical systems L1 and L2, and Table 8 shows the respective numerical values such as the optical arrangement of the light receiving unit 8, as in the first embodiment. 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.

The incident optical systems L1 and L2 according to the present embodiment respectively incident on the deflecting surface 51 in the sub-scan section at an incident angle of ± 2.2 degrees. As a result, the light beams emitted from the incident optical systems L1 and L2 are separated from each other, and the light beam optically scans the different scan surfaces 71 and 72, respectively. At this time, the same optical member can be employed in each optical path by the same configuration as in this embodiment, in which the absolute values of the incident angles in the sub-scan section of the incident optical systems L1 and L2 are the same. In addition, the incident optical systems L1 and L2 allow the light beam to be incident on the deflecting surface 51 at 78 degrees and 84 degrees in the main-scan section.

By arranging the incident optical systems L1 and L2 so as to have different incidence angles in the main scanning direction as described above, interference between the light source 11 and the light source 12 is avoided, Can be reduced. According to this configuration, it is possible to minimize the angle of incidence in the sub-scan section of the incident optical system L1 and L2. Even if deviation occurs in the eccentricity and inclination of each deflecting surface of the deflecting unit 5, The change in the pitch of the scanning lines can be prevented from occurring.

The light beam LL1 guided to the deflecting surface 51 of the deflection unit 5 by the incident optical system L1 is deflected by the light beam DL at a predetermined deflection angle as shown in the right- To be incident on the light receiving unit 8. At this time, since the incident optical system L1 is a quadrature system in the sub-scan section, the incident optical system L1 and the light receiving unit 8 can be arranged close to each other. Specifically, in the present embodiment, since? = 2.2 占 and? = 1.5 占, the above-described conditional expressions (1) to (5) are satisfied. Thus, the space for disposing the light-receiving unit 8 within the main-scan section can be reduced.

In this embodiment, the incidence angle in the main-scan section of the incidence optical system L1 is 78 占 and the incidence angle in the main-scan section of the light receiving unit 8 is 76.5 占. As shown in Fig. 5, the sensor 82 is disposed on the downstream side of the scanning (the downstream side in the rotating direction of the deflection unit 5) with respect to the light source 11. This makes it possible to perform synchronization detection at a position closer to the recording-start position in the main scanning direction on the surface to be scanned, as compared with the case where the sensor 82 is disposed on the upstream side of the light source 11, Can be reduced. Further, it is possible to prevent the light beam DL from being blocked by the deflecting surface 51.

In this embodiment, the optical path length from the light source 11 to the deflecting surface 51 is 166 mm. Therefore, the separation distance in the sub-scan direction between the centers of the light source 11 and the synchronization detecting sensor 82 is? (((166 mm x sin (2.2)) 2) ² + (166 mm x sin ² )) = 13.5 mm. Since the sizes of the light source 11 and the sensor 82 are the same as those of the first embodiment, no interference occurs between the light source 12 and the sensor 82, as shown in the right drawing of Fig.

The light source 12 and the sensor 82 can be arranged side by side in the sub scanning direction so that the incident optical system L2 and the light receiving unit 8 have the same incident angle in the main scanning section in the same manner as in the first embodiment. In the present embodiment, the cylinder lenses 41 and 42 and the synchronism detecting lens 81 are integrally formed to reduce the number of parts, but these members can be separately arranged if necessary.

The recording on each of the first scan surface 71 and the second scan surface 72 is performed on the basis of the synchronization signal generated when the light receiving unit 8 receives the light flux from the light source 11. In this embodiment, - Determines the start timing, but is not limited to this. For example, the recording-start timing at each surface to be scanned can be determined based on the synchronization signal generated when the light-receiving unit 8 receives the light flux from the light source 12. [ Alternatively, the write-start timing at the corresponding scan surface can be determined based on the respective synchronization signals generated when the light-receiving unit 8 receives the light beams from the light source 11 and the light source 12 .

In the optical scanning apparatus 300 according to the present embodiment, another set of the members other than the deflection unit 5 shown in the left drawing of Fig. 5 and the deflection unit 5 shown in Fig. 6 is disposed on the side opposite to the deflection unit 5 (Opposing arrangement). Thereby, a tandem-type optical scanning device can be configured in which one deflecting surface 51 optically scans two scanned surfaces and optically scans two scanned surfaces different in different deflecting surfaces. At this time, the recording-start timing of the four scan surfaces can be determined based on the synchronization signal generated when the light-receiving unit 8 receives the light flux from at least one of the four light sources.

Next, an optical scanning apparatus according to a second embodiment of the present invention will be described. 8 is a schematic diagram (main scanning sectional view) of an optical scanning apparatus 700 according to the present embodiment. 9 is a schematic view (sub-scan sectional view) of the main part of the incidence optical system L included in the optical scanning device 700. As shown in Fig. 9, the optical path is expanded so that the optical axis direction of the incident optical system L is aligned with the optical axis direction (X direction) of the imaging optical system 6 in Fig. 9 shows only the principal ray of the light flux while omitting the marginal ray.

The optical scanning device 700 according to the present embodiment includes a light source 1 and a light source 1 that deflects the light beam emitted from the light source 1 and optically scans the scan surface 7 in the main scanning direction A deflection unit 5 and an incidence optical system L for guiding the light flux from the light source 1 to the deflecting surface 51 of the deflection unit 5. [ The incident optical system L has a function of moving the light flux from the light source 1 from the outside of the to-be-scanned region (the region through which the scanning light beam optically scanning the scanning surface 7 passes) within the main scanning cross- (Not shown).

The incident optical system L according to the present embodiment allows the light beam from the light source 1 to be incident on the deflecting surface 51 (obliquely incident on the main-scan section) in the sub-scan section It is the input season. Thus, the light beam deflected by the deflecting surface 51 can be prevented from returning to the light source 1.

The light beam deflected by the deflecting surface 51 is directed to the light source 1 in the main scanning direction at the timing when the light beam from the incident optical system L enters the deflecting surface 51 in a direction perpendicular to the deflecting surface 51, The light source 1 can emit light even at the timing before and after the normal incidence (normal incidence). Since the light detecting unit (light receiving unit) 15 receives the light flux emitted from the light source 1 at that timing, the light amount control can be performed based on the detection signal output from the light detecting unit 15. [

As described above, according to the optical scanning apparatus 700, since the light source 1 emits light at the timing when the light flux reflected by the deflecting surface returns to the light source in the structure of the related art, The time required for the light amount control can be sufficiently secured, and the light amount control can be performed with high accuracy.

Example  3

Hereinafter, the optical scanning device 700 according to the third embodiment of the present invention will be described in detail. The optical scanning device 700 according to the present embodiment has the same configuration as the configuration according to the above-described embodiment.

The light source 1 according to the present embodiment is a semiconductor laser as an end surface emission type laser. The light source 1 emits the front luminous flux toward the deflecting unit 5 and simultaneously emits the rear luminous flux from the side of the substrate toward the side opposite to the deflecting unit 5. [ In the present embodiment, the front luminous flux is used as a scanning luminous flux (luminous flux for optically scanning the scan surface 7 to form an image), and the rear luminous flux is used as a detection luminous flux for controlling the amount of light.

The numerical values such as the optical arrangement of the incident optical system L according to the present embodiment are the same as those shown in Table 3 according to the first embodiment. The numerical values such as the optical arrangement of the imaging optical system 6 according to the present 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 the first embodiment.

The light amount control in the optical scanning device 700 according to the present embodiment will be described in detail below.

The optical scanning device 700 detects the light flux emitted from the light source 1 by detecting the light flux emitted from the light source 1 by the light detection unit 15 and feeding the obtained detection signal to the drive circuit of the light source 1 A method of automatically controlling the intensity of the light beam (automatic power control, APC) is adopted. Thus, the output (amount of light emission) of the light source 1 can be controlled so as to be always equal to the design value, so that image formation can be performed stably regardless of the temperature change.

As described above, in the present embodiment, the end surface emission type laser is used as the light source 1, and a photodetector (serving as the photodetector 15) serving as the photodetection unit 15 disposed in the laser package of the end surface emission type laser Element) detects the rear light flux emitted from this side of the laser substrate. Based on the detection signal output from the photodetection unit 15, the light quantity control unit (APC unit) 13 performs light quantity control. The light quantity control unit 13 may employ a processor such as a CPU or MPU.

9, the incident light flux (front light flux) LL emitted from the light source 1 and incident on the deflecting surface 51 is reflected by the deflecting surface 51 in a main scanning direction when the deflecting surface 51 is at a specific deflection angle , And is deflected toward the incidence optical system (L) side. In this case, since the incident optical system L projects the incident light beam LL at an incident angle of 3 degrees with respect to the deflecting surface 51 in the sub-scan section, the incident optical system L deflects the deflected light beam deflected by the deflecting surface 51 DL are deflected downward without returning to the incident optical system L, and are shielded by a shielding portion (not shown).

As described above, in the present embodiment, since the incident optical system L is a projection system, it is possible to avoid a shape in which the deflected light flux DL returns to the light source 1 and the accuracy of light amount control is lowered. The incident light flux LL and the deflected light flux DL (the optical axis of the incident optical system L and the deflecting surface of the deflecting surface 51) before and after the incident light flux LL enters the deflecting surface 51 in the main- The light source 1 can emit light even at the timing before and after the surface normals of the light source 51 overlap each other.

10 is a timing chart showing light emission timings of the light sources. 10 is a timing chart according to a comparative example. 10 is a timing chart according to the present embodiment. In the comparative example, it is assumed that the light amount control is performed in the optical scanning device of the prior art including an incidence optical system other than a projection optical system. As shown in Fig. 10, the light amount control needs to be performed before the light beam reaches the scanned area (effective scanning area) on the scan surface. This is because, when the light amount control is performed while the light flux is passing through the scanned area, the density of the formed image may become non-uniform as the light amount changes.

In the comparative example, as shown in the upper drawing of Fig. 10, at the timing when the light beam reflected by the deflecting surface returns to the light source (before and after the light beam is normally incident on the deflecting surface), the light emission of the light source is stopped There is a need. The time for detection and control of the amount of light can not be sufficiently secured and the time for detection and control of the amount of light before and after the timing is also divided and discontinuous. Therefore, it is difficult to control the light amount with high accuracy.

In contrast, as shown in the lower drawing of Fig. 10, the light source can emit light even at the timing at which the light beam is vertically incident on the deflecting surface. Therefore, detection and control of the amount of light can be continuously performed before and after the timing at which the light beam normally enters the deflecting surface for a sufficient time.

Example  4

Hereinafter, the optical scanning device 800 according to the fourth embodiment of the present invention will be described in detail. The optical scanning device 800 according to the present embodiment is different from the optical scanning device 800 according to the third embodiment in that the optical scanning device 800 includes the synchronization detection unit 8 ' And is different from the scanning device 700. Fig. 11 provides a schematic diagram showing the main parts of the incidence optical system L and the synchronization detecting unit 8 'included in the optical scanning apparatus 800. Fig. 11 is a sub-scan sectional view, and the sub-drawing of Fig. 11 is a front view. The optical scanning apparatus 800 has a configuration similar to that of the optical scanning apparatus 700 except for the synchronization detecting unit 8 '.

The synchronous detection unit 8 'includes a synchronous detection lens (synchronous detection optical element) 81 for guiding and condensing the deflected light beam DL deflected by the deflecting surface 51, (Synchronous detection light receiving element) 82 for receiving a light beam and generating a synchronizing signal. In the present embodiment, the synchronization control unit 14 determines the recording-start position in the main scan direction on the scan surface 7 based on the synchronization signal output from the synchronization detection sensor 82. [

11, in the present embodiment, in order to reduce the number of parts, the converging lens 3 (first optical element) and the synchronism detecting lens 81 (second optical element) are integrally (Integrated). However, if necessary, these lenses can be separated from each other. In this embodiment, the light source 1 and the synchronization detecting sensor 82 are mounted on the same substrate, thereby reducing the number of components and suppressing the deviation between the relative positions of these members. The respective numerical values such as the optical arrangement of the synchronization detecting unit 8 'according to this embodiment are the same as those shown in Table 4 according to the first embodiment.

The incident light flux LL emitted from the light source 1 and incident on the deflecting surface 51 is deflected downward of the incident optical system L at a predetermined deflection angle as shown in the upper diagram of Fig. 11, the incident optical system L and the synchronization detecting unit 8 'are arranged side by side in the sub-scanning direction so as to have the same incident angle in the sub-scan section, as shown in the sub-drawing of Fig. Therefore, the deflected light flux DL is incident on the synchronous detection unit 8 '.

As described above, according to the present embodiment, synchronous detection using the front luminous flux emitted from the light source 1 can be performed simultaneously with the light amount control using the rear luminous flux emitted from the light source 1. At this time, since the incident optical system L is a line-by-line system, light amount control and synchronization detection can be performed before and after the incident light beam LL enters the deflecting surface 51 in the main-scan section perpendicularly.

In addition, since the incident optical system L and the synchronization detecting unit 8 'are arranged side by side in the sub-scan direction, the space for disposing the synchronization detecting unit 8' within the main scanning section can be reduced. As a result, the scanning angle of view of the deflection unit 5 can be increased. The distance between the imaging optical system 6 and the scan surface 7 can be shortened and the size of the entire apparatus can be reduced. Further, since the incident optical system L and the synchronous detection unit 8 'can be disposed closer to the imaging optical system 6, the error between the scanning light beam and the deflected light beam DL And synchronization detection can be performed with high accuracy.

It is preferable that the light source 1 overlaps with the synchronization detecting sensor 82 within the main scanning section as in the present embodiment in order to sufficiently reduce the size of the entire apparatus. Namely, it is preferable that the incident light flux LL is the deflected light flux DL Overlapping. The expression "alignment" also includes not only a strict alignment between the incident light flux LL and the positive light flux DL in the main-scan section but also a "substantial alignment ", such as when both light fluxes overlap each other over the entire light path, . However, the configuration is not limited to this, and if necessary, the light source 1 and the synchronization detecting sensor 82 may be arranged so as to be offset from each other in the main scanning section.

Example  5

Hereinafter, the optical scanning device 900 according to the fifth embodiment of the present invention will be described in detail. The optical scanning apparatus 900 according to the present embodiment is configured such that the optical scanning apparatus 900 employs a surface emitting type laser as the light source 16 and controls the light amount by using the light flux separated by the optical separation element 9 Which is different from the optical scanning device 700 according to the third embodiment. 12 is a schematic diagram (main scanning sectional view) of the main part of the optical scanning device 900 according to the present embodiment. 13 is a schematic view (sub-scan sectional view) of a main portion of an incident optical system L included in the optical scanning device 900. As shown in Fig.

When the surface emitting type laser is used as the light source 16, unlike the end surface emitting type laser, the rear light beam is not emitted from the side of the substrate. It is necessary to separate and detect the light flux emitted from the surface emitting type laser toward the deflecting surface 51 in order to control the light amount. The half mirror serving as the optical splitter 9 is disposed in the optical path between the condenser lens 3 and the deflecting surface 51 so that the light flux from the light source 16 is directed to the deflecting surface 51 and the light flux (reflected light flux) directed toward the photodetection unit 15. The light flux (transmitted light flux) Thereby, since the light detecting unit 15 can always detect the light amount, it is possible to control the light amount with high accuracy.

The condensing lens 3 'for condensing the reflected light flux from the optical splitter 9 on the light receiving surface of the light detecting unit 15 is provided in this embodiment, The lens 3 'can be integrally formed. The optical separation element 9 is not limited to the half mirror but may be a wedge-shaped prism, for example, a beam splitter corresponding to a different intensity of a transmitted light flux and a reflected light flux, or a wedge- Prism) can be used. In this embodiment, similarly to 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.

The image forming apparatus

Fig. 14 is a schematic view (ZX cross-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 simultaneously records image information on the photosensitive surface (scanning surface) of four photosensitive drums (photosensitive members) by the optical scanning apparatus 500. [

The image forming apparatus 600 includes a printer control unit 530, an optical scanning apparatus 500, photosensitive drums 210, 220, 230 and 240 serving as image bearing members, developing units 310 and 320 , 330, and 340, a transport belt 510, and a fusing unit 540. The optical scanning apparatus 500 may include four optical scanning apparatuses according to the first embodiment, or may include two optical scanning apparatuses according to the second embodiment. At this time, the optical scanning device 500 is arranged so that the main scanning direction is aligned with the Y-axis direction in FIG. 14, and the sub-scanning direction is aligned with the rotational direction (circumferential direction) of the photosensitive drums 210 to 240.

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

The optical scanning device 500 provides optical scanning to the photosensitive surface of the photosensitive drums 210 to 240 in the main scanning direction (Y direction) by the light beams 410, 420, 430, and 440 modulated in accordance with the respective image data do. The photosensitive drums 210 to 240 are rotated in a clockwise direction by a motor (not shown). By this rotation, each photosensitive surface moves in the sub-scanning direction (circumferential direction) with respect to the light fluxes 410 to 440. Each photosensitive surface, which is electrically charged to a charging roller (not shown), is exposed to the light fluxes 410 to 440, respectively, whereby an electrostatic latent image is formed on the photosensitive surface.

The developing units 310 to 340 develop the electrostatic latent images of the respective colors formed on the photosensitive surfaces of the photosensitive drums 210 to 240 as toner images. A transfer unit (not shown) transfers the toner images of the respective colors to the transfer material conveyed by the conveyance belt 510 in an overlapping manner. The fixing unit 540 fixes the superposed image. By the above-described steps, one full-color image is formed.

The optical scanning apparatus 500 may include at least an incident optical system and a light receiving unit according to each embodiment, and may be a tandem type optical scanning apparatus that provides optical scanning for four scanned surfaces by one deflection unit. In addition, a color image reading apparatus including a line sensor such as a CCD sensor or a CMOS sensor is connected to the image forming apparatus 600 as an external apparatus 520, thereby constituting a color digital copying machine.

Variation example

Although the preferred embodiments and examples of the present invention have been described, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and alterations can be made within the scope of the present invention.

For example, in each of Embodiments 1 to 4 described above, a semiconductor laser having only one light emitting point is used as the 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 can be employed to perform image formation at high speed on the surface to be scanned. For example, a vertical cavity surface emitting laser (VCSEL) may be employed as the laser having a plurality of light emitting points. In the fifth embodiment, a VCSEL may be employed. Further, the number, materials and shape of the imaging optical elements forming the imaging optical system can be changed according to the configuration of the optical scanning apparatus.

In Embodiment 2, one deflecting surface provides optical scanning for two scanned surfaces, but is not limited thereto. Light from three or more incident optical systems can be deflected by one deflecting surface to provide optical scanning for three or more scanned surfaces. Alternatively, a plurality of deflecting surfaces may provide optical scanning for a plurality of scan surfaces. When a plurality of incident optical systems are provided, as in the first embodiment, optical elements arranged in each optical path and members such as an aperture stop can be integrated.

Further, in each optical path from the deflecting surface to the plurality of scan surfaces, the imaging lenses can be individually disposed, or the integral imaging lens can be shared by the optical path. In Embodiment 2, only one light receiving unit corresponding to one light source is provided, and the light emission timing of a plurality of light sources is controlled by using the synchronous signal. However, it is possible to provide a plurality of light receiving units corresponding to a plurality of light sources. When a light source having a plurality of light emission points is employed, the light emission timing of the other light emission points can be controlled based on the synchronization signal obtained by detecting only the light flux from one light emission point. Alternatively, the light flux from each light emitting point can be individually detected and controlled.

In each of Embodiments 1 and 2 described above, a control circuit for determining the write-start position in the main scan direction on the scan surface is mounted in the optical scanning device, but is not limited thereto. The control circuit is disposed in the image forming apparatus, but the control circuit can be mounted outside the optical scanning apparatus. In this case, the control circuit can be provided to the printer control unit included in the image forming apparatus.

When a multi-beam laser is employed, the light amount control can not be performed simultaneously for all of a plurality of light emission points. Therefore, it is necessary to sequentially detect a plurality of light beams and to control the light amount of each light emission point. In the case of applying the multi-beam laser to the above-described comparative example, it is not possible to sufficiently secure the time for detecting and controlling the amount of light in a single scan. Therefore, it is necessary to perform optical scanning several times until the light amount control of all the light emission points is finished. The total time of light amount control can be prolonged. In contrast, when a multi-beam laser is applied to any one of Examples 3 to 5, sufficient time for light amount control can be secured. Therefore, the total time of light amount control can be shortened.

In Examples 3 and 4, the amount of light is controlled by detecting the rear luminous flux emitted from the end surface-emitting type laser. However, if necessary, the amount of light can be controlled by detecting the front luminous flux. At this time, for example, in the third embodiment, the optical detection unit can be provided at the position of the synchronization detection sensor according to the fourth embodiment. In the fourth embodiment, at the position next to the synchronization detection sensor, It is possible to provide an optical detection unit on the same substrate. Alternatively, as in the fifth embodiment, the front luminous flux can be separated and detected by the optical isolator. In each of Embodiments 3 to 5, the photodetecting unit can be used as a synchronous detecting sensor, can perform synchronous detection based on a signal from the photodetecting unit, and can perform light quantity detection and synchronous detection simultaneously with one photodetecting unit .

In each of the third to fifth embodiments, the light emission timing control of the light source can be performed by a control unit provided in the light source or by a control unit provided externally. Further, the light amount control unit and the synchronization control unit may be disposed inside the optical scanning apparatus or inside the image forming apparatus. At this time, at least one of the light amount control, the synchronous control, and the light emission timing control of the light source can be performed by one control unit.

In each of Examples 3 to 5, the light flux from one light source provides optical scanning for one scan surface, but is not limited thereto. A light flux from a plurality of light sources can provide optical scanning for a plurality of scan surfaces. At this time, one deflecting surface can deflect a plurality of light beams at the same time, or a plurality of deflecting surfaces can deflect a plurality of light beams. At this time, in each optical path from the deflecting surface to the plurality of scan surfaces, the image forming lenses can be individually disposed, or the integrated optical lens can be shared by the optical path.

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

Claims (20)

An optical scanning device comprising:
A deflection unit having a deflecting surface and arranged to optically scan the surface to be scanned in a main scanning direction by deflecting the light beam;
An incident optical system disposed such that the light beam is incident on the deflecting surface in a sub-scan section; And
And a light receiving unit arranged to receive a light beam deflected by the deflecting surface to generate a signal,
The following conditions are satisfied,
|? |? |? |
(Deg) is an angle of incidence of the light beam from the incident optical system in the sub-scan section with respect to the deflecting surface, and? (Deg) is a light flux incident on the deflecting surface in the main- And is formed by a light beam deflected by said light source and directed toward said light receiving unit. The method according to claim 1, wherein the following conditions are satisfied:
1.5? |? |? 10, and
0? |? |? 5.0
Is satisfied. &Lt; / RTI &gt; The method according to claim 1, wherein the following conditions are satisfied:
1.5? |? |? 5.0, and
0? |? |? 3.0
Is satisfied. &Lt; / RTI &gt; 2. The optical scanning device according to claim 1, wherein a light beam incident on the deflecting surface is aligned with a light beam deflected by the deflecting surface in the main scanning direction and directed toward the light receiving unit. The optical scanning device according to claim 1, wherein the light receiving unit is disposed downstream of the incident optical system in the rotating direction of the deflecting unit. 2. The optical pickup apparatus according to claim 1, wherein, in the main-scan section, an optical path between the incident optical system and the deflecting surface and an optical path between the deflecting surface and the light receiving unit are optical paths in which a principal ray of the light flux is not refracted or reflected, Optical scanning device. The optical system according to claim 1, wherein the incident optical system includes a first optical element arranged to condense a light beam, and the light receiving unit includes a second optical element arranged to condense a light beam, Are integrated with each other. 2. The photoelectric conversion device according to claim 1, wherein the incident optical system includes a light source arranged to emit a light flux, and the light receiving unit includes a photoelectric conversion element arranged to receive a light flux, The optical scanning device comprising: The optical scanning device according to claim 1, wherein the incident optical system includes a plurality of incident optical systems, and the deflecting unit optically scans a plurality of scan surfaces by deflecting the light flux from the plurality of incident optical systems. 10. The optical scanning device according to claim 9, wherein each light flux from the plurality of incident optical systems has a different incident angle with respect to the deflecting surface in the main-scan section. 10. The optical scanning device according to claim 9, wherein each light flux from the plurality of incident optical systems has an incident angle having an absolute value equivalent to the deflecting surface in the sub-scan section. The optical scanning device according to claim 1, wherein the light receiving unit generates a signal for determining a write-start position in the main scanning direction on the surface to be scanned. The optical scanning device according to claim 1, further comprising a control circuit arranged to determine a recording-start position in the main scanning direction on the surface to be scanned based on the signal. The method according to claim 1,
Further comprising a light source,
The incidence optical system causes the light flux from the light source to be incident on the deflecting surface from the outside of the scanned region within the main-scan section,
Wherein the light source emits a light beam at a timing at which the light beam from the incident optical system enters the deflecting surface perpendicularly in the main-scan section. 15. The optical scanning device according to claim 14, wherein said light receiving unit receives light flux reflected by said deflecting surface at said timing to generate a signal. 16. The optical scanning device according to claim 15, further comprising a light amount control unit arranged to control an amount of light emission of the light source based on the signal. 16. The optical scanning device according to claim 15, further comprising a synchronization control unit arranged to determine a recording-start position in the main scanning direction on the surface to be scanned based on the signal. The optical scanning device according to claim 15, further comprising a light splitting element arranged to separate the light flux from the light source into a light flux directed toward the deflecting surface and a light flux directed toward the light receiving unit. An image forming apparatus comprising:
An optical scanning device according to any one of claims 1 to 18;
A developing unit arranged to develop, as a toner image, an electrostatic latent image formed on the surface to be scanned by the optical scanning device;
A transfer unit arranged to transfer the developed toner image onto a transfer material; And
And a fixing unit arranged to fix the transferred toner image to the transfer material. An optical scanning device comprising:
Light source;
A deflection unit having a deflecting surface and arranged to optically scan the surface to be scanned in a main scanning direction by deflecting a light flux from the light source; And
And an incidence optical system arranged to guide the light beam from the light source to the deflecting surface,
Wherein the deflection unit is formed by a single rotation polygonal mirror,
The incidence optical system causes the light beam to be incident on the deflecting surface from the outside of the scanned area in the main-scan section, causing the light beam to be incident on the deflecting surface in the sub-
Wherein the light source emits a light beam at a timing at which the light beam from the incident optical system enters the deflecting surface perpendicularly in the main-scan section.

Images