Optical finger navigation device having an integrated ambient light sensor and electronic system comprising the same

• US 8,987,656 B2
• Filed: 10/09/2012
• Issued: 03/24/2015
• Est. Priority Date: 10/09/2012
• Status: Active Grant

• Current Assignee: Cloud Light Technology Limited
• Original Assignee: SAE Magnetics Limited (TDK Corporation)
• Inventors: Hung, Vincent Wai, Ng, Victor Pak Hong
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US13/648,257
• Publication Number:
  US 20140097327A1
• Time in Patent Office: 896 Days
• Field of Search: 250/221, 250/227.11, 250/227.14, 250/239, 250/216, 250/214.AL, 340555-557, 340602-604, 200/84.R
• US Class Current: 250/221
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

An optical finger navigation module includes a light source configured for emitting light in a first spectrum; a cover housing disposed above the light source, the cover housing including a window plate that is configured to transmit light in at least the first spectrum, and a light guiding structure that is configured to transmit light in at least a second spectrum; a first light sensor configured to sense light in the first spectrum originally emitted by the light source, reflected by an object, and then transmitted through the window plate; a second light sensor configured to sense light in the second spectrum transmitted through the light guiding structure or the window plate; and a substrate. The light source, the cover housing, the first light sensor and the second light sensor are coupled and mounted to the substrate.

Claims

1. An optical finger navigation device comprising:

a light source configured for emitting detecting light in a first spectrum;

a cover housing disposed above the light source, the cover housing comprising a window plate that is configured to transmit the detecting light in at least the first spectrum, and a light guiding structure that is configured to transmit ambient light in at least a second spectrum;

a detecting light sensor configured to sense the detecting light in the first spectrum originally emitted by the light source, reflected by a finger, and then transmitted through the window plate;

an ambient light sensor configured to sense the ambient light in the second spectrum transmitted through the light guiding structure or the window plate;

a data processing unit; and

a substrate;

wherein;

the light source, the cover housing, the detecting light sensor and the ambient light sensor are coupled and mounted to the substrate; and

wherein the data processing unit is electrically connected to the detecting light sensor, and configured to convert a subsequent change of a spatial intensity profile collected by the detecting light sensor into information regarding a motion of the finger.

2. The optical finger navigation device of claim 1, wherein the first spectrum is an infrared spectrum with a peak wavelength of about 850 nm.

3. The optical finger navigation device of claim 1, wherein the ambient light in the second spectrum is visible light with a wavelength of 400 nm to 700 nm.

4. The optical finger navigation device of claim 1 further comprising a first set of passive optical components being disposed between the light source and the window plate and configured to direct the light emitted by the light source to the finger.

5. The optical finger navigation device of claim 4 further comprising a second set of passive optical components being disposed between the window plate and the detecting light sensor and configured to focus light reflected by the finger to form an image onto the detecting light sensor, wherein the window plate is configured to selectively transmit the detecting light in the first spectrum and block the ambient light in the second spectrum.

6. The optical finger navigation device of claim 5, wherein the first and second sets of passive optical components comprise lenses and prisms.

7. The optical finger navigation device of claim 1, wherein the ambient light sensor is coated with a coating or covered by a spectral filter that transmits the ambient light in the second spectrum while blocking the detecting light in the first spectrum.

8. The optical finger navigation device of claim 1, wherein the light source is a vertical-cavity surface-emitting laser or a light-emitting diode.

9. The optical finger navigation device of claim 1, wherein the ambient light sensor comprises an analog-to-digital converter configured to convert the light induced analog signal into a digital signal.

10. The optical finger navigation device of claim 1, wherein the ambient light sensor is a photo-transistor configured to output an analog signal to the detecting light sensor, and the detecting light sensor is configured to convert the analog signal into a digital signal.

11. The optical finger navigation device of claim 1, wherein the light guiding structure encloses a periphery of the window plate.

12. The optical finger navigation device of claim 1, wherein the data processing unit is configured to buffer a reading of the ambient light sensor for a predetermined period of time, to determine whether the finger is being placed on the window plate, and when the finger is determined to be being placed on the window plate to use the buffered reading of the ambient light sensor in place of an actual reading of the ambient light sensor.

13. The optical finger navigation device of claim 1 further comprising a structure disposed between the light source and the detecting light sensor, wherein the structure defines an aperture and is made of a material that blocks light, and part of the light reflected by the finger passes through the aperture before being projected onto the detecting light sensor.

14. The optical finger navigation device of claim 1, wherein the windows plate is configured to transmit the detecting light in the first spectrum and the ambient light in the second spectrum, and the detecting light sensor and the ambient light sensor are two parts of an integrated sensor, covering a first sensing area and a second sensing area respectively.

15. The optical finger navigation device of claim 14 further comprising a first spectral filter disposed on top of the detecting light sensor and a second spectral filter disposed on top of the ambient light sensor, wherein the first spectral filter is configured to transmit the detecting light in the first spectrum and block the ambient light in the second spectrum, and the second spectral filter is configured to transmit the ambient light in the second spectrum and block the detecting light in the first spectrum.

16. The optical finger navigation device of claim 15, wherein the second spectral filter comprises a plurality of sections with mutually different spectral responses, each section covering a subdivision of the second sensing area.

17. The optical finger navigation device of claim 1 further comprising a second light source and an optical guide, wherein the second light source comprises a plurality of LEDs being configured to emit light in a visible spectrum, the optical guide is configured to couple light emitted by the second light source to the light guiding structure, and the light guiding structure comprises light diffusive materials or is coated with light diffusive paint on the outer surfaces thereof.

18. The optical finger navigation device of claim 17 further comprising a switching control unit, wherein the switching control unit is configured to control an operation timing sequences between the light source and the ambient light sensor in an alternating manner.

19. An electronic system comprising an optical finger navigation device configured for tracking a motion of a finger, the optical finger navigation device comprising:

a light source configured for emitting detecting light in a first spectrum;

a cover housing disposed above the light source, the cover housing comprising a window plate that is configured to transmit the detecting light in at least the first spectrum, and a light guiding structure that is configured to transmit ambient light in at least a second spectrum;

a detecting light sensor disposed below the window plate and configured to sense the detecting light in the first spectrum originally emitted by the light source, reflected by the finger, and then transmitted through the window plate;

an ambient light sensor disposed below the window plate and configured to sense the ambient light in the second spectrum transmitted through the light guiding structure or the window plate; and

a substrate;

wherein;

the light source, the cover housing, the detecting light sensor and the ambient light sensor are mounted to the substrate;

the first spectrum is an infrared spectrum with a peak wavelength of about 850 nm; and

the ambient light in the second spectrum is visible light with a wavelength of 400 nm to 700 nm.

20. An optical finger navigation device comprising:

a light source configured for emitting detecting light in a first spectrum;

a cover housing disposed above the light source, the cover housing comprising a window plate and a light guiding structure;

a detecting light sensor disposed below the window plate and configured to sense the detecting light in the first spectrum originally emitted by the light source, reflected by a finger, and then transmitted through the window plate;

an ambient light sensor disposed below the window plate and configured to sense the ambient light in a second spectrum transmitted through the light guiding structure or the window plate;

a substrate; and

a data processing unit;

wherein;

the light source, the cover housing, the detecting light sensor and the ambient light sensor are mounted to the substrate; and

the data processing unit is electrically connected to the detecting light sensor, and configured to convert a subsequent change of a spatial intensity profile collected by the detecting light sensor into information regarding a motion of the finger.