Monolithic CD/DVD read/write head

• US 6,496,465 B1
• Filed: 06/07/1999
• Issued: 12/17/2002
• Est. Priority Date: 06/09/1998
• Status: Expired due to Fees

• Current Assignee: Broome, Barry G., Richard, Jenkin A.
• Original Assignee: Broome, Barry G., Richard, Jenkin A.
• Inventors: Broome, Barry G., Richard, Jenkin A.
• Primary Examiner(s): Young, W. R.
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US09/327,411
• Time in Patent Office: 1,289 Days
• Field of Search: 369/44.12, 369/44.14, 369/44.37, 369/44.38, 369/44.23, 369/44.24, 369/112.17, 369/112.2, 369/121, 369/122, 369/112.19, 369/94, 369/112.21, 369/112.23, 369/118, 369/112.01, 369/112.26, 369/112.08, 359/434, 359/819, 600/160
• US Class Current: 369/112.08
• CPC Class Codes: G11B 2007/0006 adapted for scanning different types of carrier, e.g. CD & DVD
• CPC Class Codes: G11B 7/1275 Two or more lasers having different wavelengths
• CPC Class Codes: G11B 7/1353 Diffractive elements, e.g. holograms or gratings diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44
• CPC Class Codes: G11B 7/1359 Single prisms
• CPC Class Codes: G11B 7/1365 Separate or integrated refractive elements, e.g. wave plates
• CPC Class Codes: G11B 7/1374 Objective lenses optical objectives per se G02B9/00
• CPC Class Codes: G11B 7/22 Apparatus or processes for the manufacture of optical heads, e.g. assembly

Abstract

A read head optical system capable of reading either CD or DVD disks is provided. A monolithic molded hollow plastic block includes three lenses integrally molded into its exterior surfaces. A 780 nm laser diode is aligned with the first lens for reading CD disks, a 655 nm laser is aligned with the second lens for reading DVD disks and a detector for providing signal, focus and tracking data is aligned with the third molded lens. The hollow plastic block has an interior cavity adapted to support optical elements to receive and transmit the output of the laser diodes to the disks and to the detector. The three lenses are formed in the hollow plastic block in various embodiments.

Claims

1. A read head optical system capable of reading either CD or DVD disks, comprising:

a monolithic molded, hollow plastic block, said hollow plastic block having first, second and third lens surfaces integrally molded into the exterior surface of said hollow plastic block, said hollow plastic block also having first and second exterior entry surfaces, said first and second entry surfaces being perpendicular to each other, and wherein said first lens surface is molded on said first exterior entry surface and said second and third lens surfaces are formed on said second exterior entry surface, whereby the output beams of said first and second lasers enter said hollow plastic block perpendicularly to each other,

a first laser diode aligned with said first molded lens, said first laser having a wavelength selected for reading CD disks,

a second laser diode aligned with said second molded lens, said second laser having a wavelength selected for reading DVD disks,

detector means aligned with said third molded lens for providing signal, focus and tracking data for said optical read head, and

cavity means for supporting optical elements wherein said cavity means is formed in said hollow plastic block, said cavity means being molded to capture and align one or more optically coated glass plates to receive and transmit the output of said first and second lasers to said disks and to said detector means.

2. The apparatus of claim 1 further comprising:

beamsplitter mounting means formed in said cavity means to align beamsplitters with said lens surfaces,

first and second dichroic plate glass beamsplitters carried in said cavity means, and

an integrally molded diffraction grating formed in said cavity means between said dichroic plate beamsplitters.

3. The apparatus of claim 2 wherein a totally internal reflection prism surface is integrally formed in said hollow plastic block to reflect the output beam of said first laser into said cavity means.

4. The apparatus of claim 1 wherein said hollow plastic block carries a diffractive combiner means for carrying said first and second lens surfaces and for diffractively combining the output beams of said first and second lasers.

5. The apparatus of claim 2 wherein said diffractive combiner means has a double faceted molded extension in which said first and second lens surfaces are formed.

6. The apparatus of claim 2 wherein said first laser has a wavelength of approximately 780 nm, said second laser has a wavelength of approximately 655 nm, and further comprising:

diffraction means for diffracting said 780 nm laser in the +1 order and for said 655 nm laser in the −

1 order.

7. The apparatus of claim 6 wherein said diffraction means comprises a glass plate substrate with a linear surface grating.

8. The apparatus of claim 1 wherein said first laser has a wavelength of approximately 780 nm, said second laser has a wavelength of approximately 655 nm, and further comprising:

a diffractive plano surface means molded into said cavity means to maximize the diffraction efficiency for said 780 nm laser in the +1 order and for said 655 nm laser in the +2 order.