Collimator lens and optical scanning apparatus using the same

• US 6,396,640 B2
• Filed: 03/28/2001
• Issued: 05/28/2002
• Est. Priority Date: 03/30/2000
• Status: Expired due to Fees

• Current Assignee: Fujinon Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Otomo, Ryoko
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US09/818,598
• Publication Number:
  US 20010043409A1
• Time in Patent Office: 426 Days
• Field of Search: 359/641,205,763,764,772,774
• US Class Current: 359/641
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 9/34 having four components only

Abstract

A collimator lens comprises, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power. The second and third lenses are cemented together. One of the second and third lenses has a negative refracting power, whereas the other has a positive refracting power. The collimator lens further satisfies Bƒ/ƒ>0.6, where Bf is the back focus of the whole lens system, and f is the focal length of the whole lens system.

Claims

1. A collimator lens comprising, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power, said second and third lenses being cemented together, one of said second and third lenses having a negative refracting power, the other having a positive refracting power;

said collimator lens satisfying the following conditional expression (1);

2. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expression (2):

3. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expression (3):

4. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expression (4):

5. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expressions (2) and (3):

6. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expressions (2) and (4):

7. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expressions (3) and (4):

8. A collimator lens according to claim 1, wherein said first lens is a positive lens having a convex surface directed onto the parallel luminous flux side, said fifth lens is a positive meniscus lens having a concave surface directed onto the light source side, and said collimator lens satisfies the following conditional expressions (2) to (4):

9. An optical scanning apparatus using the collimator lens according to claim 1.

10. An optical scanning apparatus according to claim 9, wherein said optical scanning apparatus carries out multi-beam scanning.

11. An optical scanning apparatus according to claim 9, wherein said optical scanning apparatus is a laser printer or a copier.