Optical navigation system having a filter-window to seal an enclosure thereof

• US 20070138377A1
• Filed: 12/16/2005
• Published: 06/21/2007
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Zarem, Harold
• Granted Patent: US 8,471,191 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface

Abstract

An optical navigation system is provided to sense relative movement between the system and a surface. Generally, the system includes: (i) an illuminator having a light source to illuminate a portion of the surface; (ii) a detector to receive light reflected from the portion of the surface; and (iii) an enclosure enclosing the illuminator and the detector, the enclosure having a window covering the detector and through which light reflected from the portion of the surface is transmitted to the detector, the window being substantially transparent to at least one wavelength of light emitted by the light source. In certain embodiments, the window is a filter-window that is substantially non-transparent to light from other sources, such as ambient light, having shorter or longer wavelengths. Other embodiments are also described.

Claims

1. An optical navigation system for sensing relative movement between the system and a surface, the system comprising:

an illuminator having a light source to illuminate a portion of the surface;

a detector to receive light reflected from the portion of the surface; and

an enclosure enclosing the illuminator and the detector, the enclosure having a window covering the detector and through which light reflected from the portion of the surface is transmitted to the detector, the window being substantially transparent to at least one wavelength of light emitted by the light source.

2. An optical navigation system according to claim 1, wherein the window is substantially non-transparent to ambient light.

3. An optical navigation system according to claim 1, wherein the light source is a narrow band light source emitting a narrow range of wavelengths, and wherein the window is substantially transparent to the wavelength of the light source.

4. An optical navigation system according to claim 1, wherein the light source is a coherent light source having a single wavelength.

5. An optical navigation system according to claim 4, wherein the window is a filter-window and is substantially non-transparent to light having wavelengths shorter and longer than the wavelength of the light source.

6. An optical navigation system according to claim 4, wherein the window is a filter-window and is substantially transparent to Infra-red (IR) light, but is substantially non-transparent to light having shorter wavelengths.

7. An optical navigation system according to claim 4, wherein the filter-window comprises at least two filtering layers including a first filter-window to block light having wavelengths shorter than the wavelength of the light source, and a second filter-window to block light having wavelengths longer than the wavelength of the light source.

8. An optical navigation system according to claim 1, wherein the window also covers the light source so that light emitted from the light source is transmitted out of the enclosure through the window.

9. An optical navigation system according to claim 1, further comprising a separate, second window covering the light source so that light emitted from the light source is transmitted out of the enclosure through the second window.

10. A method of sensing movement of an optical navigation system relative to a, the method comprising steps of:

illuminating a portion of the surface using an illuminator having a light source enclosed within an enclosure;

transmitting light reflected from the portion of the surface to a detector enclosed within the enclosure through a window in the enclosure covering the detector, the window being substantially transparent to at least one wavelength of light emitted by the light source; and

detecting a pattern of light reflected from the illuminated portion of the surface using the detector.

11. A method according to claim 10, wherein the light source is a coherent light source having a single wavelength.

12. A method according to claim 11, wherein the window is a filter-window substantially non-transparent to light having wavelengths shorter and longer than the wavelength of the light source, and wherein the method further comprises the step of attenuating light having wavelengths shorter and longer than the wavelength of the light source.

13. A method according to claim 10, wherein the window also covers the light source, and wherein the step of illuminating a portion of the surface comprises the step of transmitting light emitted from the light source out of the enclosure through the window.

14. A finger navigation device for sensing movement of a finger across a surface of the device, the finger navigation device comprising:

an enclosure having a window that includes the surface across which the finger is moved;

an illuminator enclosed within the enclosure and having a light source to illuminate at least a portion of the finger through the window when the portion of the finger is positioned in contact with or proximal to the surface of the window;

a detector to receive light reflected from the portion of the finger through the window; and

wherein the window is substantially transparent to wavelengths of emitted from the light source and reflected from the finger.

15. A finger navigation device according to claim 14, wherein the window is a filter-window substantially non-transparent to ambient light which may fall thereon in operation thereof.

16. A finger navigation device according to claim 14, wherein the light source is a coherent light source having a single wavelength, and wherein the window is a filter-window substantially non-transparent to light having wavelengths other than a wavelength of the light source.

17. A finger navigation device according to claim 14, wherein the window is a filter-window comprising a layer of plastic, glassine or crystalline material that is substantially transparent to at least one wavelength of light emitted by the light source and is adapted to block at least at least one wavelength of light.

18. An optical navigation system for sensing relative movement between the system and a surface, the system comprising:

an illuminator having a light source to illuminate a portion of the surface;

a detector to receive light reflected from the portion of the surface; and

an enclosure enclosing the illuminator and the detector, the enclosure having a window covering the illuminator and through which light emitted from the light source is transmitted out of the enclosure to illuminate the portion of the surface, the window being substantially transparent to at least one wavelength of light emitted by the light source.

19. An optical navigation system according to claim 18, wherein the light source is a coherent light source having a single wavelength, and the window is a filter-window and is substantially non-transparent to light having wavelengths shorter and longer than the at least one wavelength of light emitted by the light source.

20. An optical navigation system according to claim 18, wherein the window also covers the detector so that light reflected from the portion of the surface is transmitted to the detector through the window.

21. An optical navigation system according to claim 18, further comprising a separate, second window covering the detector through which light reflected from the portion of the surface is transmitted to the detector.