Optical scanning apparatus and image forming apparatus having the same

Abstract

To provide an optical scanning device that can achieve high speed while suppressing cost increases. [Solution] The optical scanning device according to the present invention comprises a deflector that deflects first and second luminous beams from first and second light sources to scan a common scan surface in the main scanning direction, a first optical element that guides the first and second luminous beams from first and second light sources to the deflector, and an optical system that guides the first and second luminous beams deflected by the deflector to the scan surface, wherein at least a portion of the first luminous beam enters the first optical element from the first optical surface and exits from the second optical surface, and at least a portion of the second luminous beam is reflected by the second optical surface in the first optical element, and the incidence angles of the main rays of the first and second luminous beams in the main scanning cross-section when they enter the first optical element are θ i1 (°) and θ i2 When we consider (°), 120 < θ i1 +θ i2 <150 It is characterized by satisfying the following conditions.

Claims

1. A deflector that deflects the first and second luminous beams from the first and second light sources to scan a common scanning surface in the main scanning direction, A first optical element that guides the first and second luminous beams from the first and second light sources to the deflector, The system includes an optical system that guides the first and second light beams, which have been deflected by the deflector, to the surface to be scanned, At least a portion of the first luminous beam enters the first optical element from the first optical surface and then exits from the second optical surface. At least a portion of the second luminous beam is reflected by the second optical surface in the first optical element. The incident angles of the principal rays of the first and second light beams in the main scanning cross-section when incident on the first optical element are θ, respectively. ｉ１ (°) and θ ｉ２ When we consider (°), 120<θ ｉ１ +θ ｉ２ <150 An optical scanning device characterized by satisfying the following conditions.

2. 0.95<θ ｉ１ / i ｉ２ <1.05 The optical scanning apparatus according to claim 1, characterized in that it satisfies the following conditions.

3. while having S-polarized light and P-polarized light, the reflectance of the second optical surface with respect to a light beam incident at an angle θ ｉ２ is respectively R Ｓ＿θｉ２ and R Ｐ＿θｉ２ when it is set like this 0.70<(R Ｓ＿θｉ２ +(1-R Ｐ＿θｉ２ )) / 2<0.91 The optical scanning apparatus according to claim 1, characterized in that it satisfies the following conditions.

4. While possessing S-polarization, at an angle θ ｉ２ (°), (θ ｉ２ -7) and (θ ｉ２ The reflectance of the second optical surface with respect to the light beam incident at +7) is R Ｓ＿θｉ２ , R Ｓ＿（θｉ２－７） and R Ｓ＿（θｉ２＋７） In that case, 1.97<(R Ｓ＿（θｉ２－７） +R Ｓ＿（θｉ２＋７） ) / R Ｓ＿θｉ２ <2.05 The optical scanning apparatus according to claim 1, characterized in that it satisfies the following conditions.

5. While possessing P-polarization, at an angle θ ｉ２ (°), (θ ｉ２ -7) and (θ ｉ２ The reflectance of the second optical surface with respect to the light beam incident at +7) is R Ｐ＿θｉ２ , R Ｐ＿（θｉ２－７） and R Ｐ＿（θｉ２＋７） In that case, 2.32<(R Ｐ＿（θｉ２－７） +R Ｐ＿（θｉ２＋７） ) / R Ｐ＿θｉ２ <3.03 The optical scanning apparatus according to claim 1, characterized in that it satisfies the following conditions.

6. The optical scanning apparatus according to claim 1, further comprising second and third optical elements that guide the first and second light beams from the first and second light sources to the first optical element.

7. The optical scanning apparatus according to claim 6, characterized in that the second and third optical elements are optical elements formed integrally with each other.

8. The optical scanning apparatus according to claim 6, characterized in that the second and third optical elements focus the first and second light beams in the sub-scanning cross-section.

9. The optical scanning apparatus according to claim 6, characterized in that the second and third optical elements convert the degree of convergence of the first and second light beams in the main scanning cross-section.

10. The optical scanning apparatus according to claim 6, characterized in that at least one of the second and third optical elements has an optical surface that converts the polarization state of an incident light beam.

11. The optical scanning apparatus according to claim 10, characterized in that the optical surface has a microstructure that converts the polarization state.

12. The optical scanning apparatus according to claim 1, characterized in that it comprises the first and second light sources provided on a common substrate.

13. The optical scanning apparatus according to claim 1, characterized in that the polarizations of the first and second light beams immediately before they enter the first optical element are different from each other.

14. The optical scanning apparatus according to claim 13, characterized in that the second optical surface is provided with a polarizing film that transmits the first light beam while reflecting the second light beam.

15. When N is the number of layers in the multilayer film forming the polarizing characteristic film, 4 ≤ N ≤ 6 The optical scanning apparatus according to claim 14, characterized in that it satisfies the following conditions.

16. The optical scanning apparatus according to claim 1, characterized in that the second light source is positioned on the side of the first light source where the surface to be scanned is located, in a first direction parallel to the optical axis of the optical system when projected onto the main scanning cross-section.

17. The first light source is positioned on the side of the scanned surface relative to the second light source in a first direction parallel to the optical axis of the optical system when projected onto the main scanning cross-section, The optical scanning apparatus according to claim 1, further comprising a light-shielding member disposed between the first optical element and the optical system in the first direction when projected onto the main scanning cross-section, which shields the second light beam that enters the first optical element from the second optical surface and then exits from the first optical surface.

18. The first light source is positioned on the side of the scanned surface relative to the second light source in a first direction parallel to the optical axis of the optical system when projected onto the main scanning cross-section, In the main scanning cross-section, the angle between the direction of propagation of the principal ray of the second light beam immediately before it enters the second optical surface and the optical axis, and the angle between the direction of propagation of the principal ray of the off-axis light beam immediately after it is deflected by the deflector and the optical axis, are defined as β and θ, respectively. ｍａｘ－ In that case, 1.05<β / θ ｍａｘ－ <1.40 The optical scanning apparatus according to claim 1, characterized in that it satisfies the following conditions.

19. The optical scanning apparatus according to claim 1, characterized in that the first and second optical surfaces are parallel to each other.

20. The optical scanning apparatus according to claim 1, characterized in that the direction of propagation of the principal rays of the first and second light beams immediately before they enter the deflector is parallel to the principal scanning cross-section.

21. A deflector that deflects the first and second luminous beams from the first and second light sources to scan a common scanning surface in the main scanning direction, A first optical element that guides the first and second luminous beams from the first and second light sources to the deflector, The system includes an optical system that guides the first and second light beams, which have been deflected by the deflector, to the surface to be scanned, At least a portion of the first luminous beam enters the first optical element from the first optical surface and then exits from the second optical surface. An optical scanning device characterized in that at least a portion of the second light beam is reflected by the second optical surface in the first optical element.

22. An image forming apparatus comprising: an optical scanning apparatus according to any one of claims 1 to 21; and a developer for developing an electrostatic latent image formed on the surface to be scanned by the optical scanning apparatus as a toner image.

23. An image forming apparatus comprising an optical scanning device according to any one of claims 1 to 21, and a controller that converts a signal output from an external device into image data and inputs it to the optical scanning device.

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