Optical positioning device using different combinations of interlaced photosensitive elements

• US 20050259097A1
• Filed: 05/05/2005
• Published: 11/24/2005
• Est. Priority Date: 05/21/2004
• Status: Abandoned Application

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Roxlo, Charles B., Carlisle, Clinton B., Trisnadi, Jahja I., Webb, Douglas A., Lehoty, David A.
• Application Number:
  US11/123,500
• Publication Number:
  US 20050259097A1
• Time in Patent Office: Days
• US Class Current: 345/207
• 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
• CPC Class Codes: G06F 3/0354 with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks

Abstract

One embodiment relates to an optical displacement sensor for sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of frames of the surface. The sensor includes at least a detector, first circuitry, and second circuitry. The detector includes a plurality of photosensitive elements organized in first and second arrays. The first circuitry is configured to combine signals from every Mth element of the first array to generate M group signals, and the second circuitry is configured to combine signals from every M′th element of the second array to generate M′ group signals. M and M′ are numbers which are different from each other. Other embodiments are also disclosed.

Claims

1. An optical displacement sensor for sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of frames of the surface, the sensor comprising:

a detector including a plurality of photosensitive elements organized in first and second arrays;

first circuitry configured to combine signals from every Mth element of the first array to generate M group signals; and

second circuitry configured to combine signals from every M′

th element of the second array to generate M′

group signals,

wherein M and M′

are numbers which are different from each other.

2. The optical displacement sensor according to claim 1, wherein the first and second arrays include at least one shared photosensitive element.

3. The optical displacement sensor of claim 2, further comprising:

a current mirror circuit configured to duplicate photocurrent from the shared photosensitive element.

4. The optical displacement sensor of claim 2, wherein the first and second arrays share substantially all of the photosensitive elements.

5. The optical displacement sensor of claim 4, further comprising:

current mirror circuitry configured to duplicate photocurrent from substantially all of the photosensitive elements.

6. The optical displacement sensor according to claim 1, wherein each said array comprises a linear comb array (LCA) arranged parallel to an axis.

7. The optical displacement sensor according to claim 6, further comprising:

circuitry configured to generate a first pair of line signals from the M group signals; and

circuitry configured to generate a second pair of line signals from the M′

group signals.

8. The optical displacement sensor according to claim 7, wherein the line signals are oscillatory in form as the data input device is moved in a direction not perpendicular to the axis.

9. The optical displacement sensor according to claim 8, further comprising:

circuitry configured to calculate from a line signal a component v of a velocity of movement of the data input device along the axis using equation;

v=f*p/τ

f is a frame rate, p is a detector pitch, and τ

is the time between a previous two zero-crossings going in a same direction.

10. The optical displacement sensor according to claim 7, wherein the line signal generation circuitry comprises weighting circuitry to weight the group signals.

11. The optical displacement sensor according to claim 10, wherein the M group signals are each weighted by one of M in-phase weighting factors and one of M quadrature weighting factors, and wherein the M′

group signals are each weighted by one of M′

in-phase weighting factors and one of M′

quadrature weighting factors.

12. The optical displacement sensor according to claim 11, where the in-phase weighting factors (S1) and the quadrature weighting factors (S2) are calculated using equations:

13. The optical displacement sensor according to claim 1, further comprising:

circuitry configured to compare a quality of a line signal which is generated from the M group signals with the quality of another line signal which is generated from the M′

group signals; and

circuitry configured to select a higher quality line signal based on the comparison.

14. The optical displacement sensor according to claim 1, further comprising:

circuitry configured to weight line signals based on a signal quality characteristic and to combine the weighted line signals.

15. A method of sensing movement of a data input device across a surface using an optical displacement sensor having a detector including a plurality of photosensitive elements organized in first and second arrays, the method comprising:

receiving on the plurality of photosensitive elements an intensity pattern produced by light reflected from a portion of the surface;

combining signals from every Mth element of the first array to generate M group signals; and

combining signals from every M′

th element of the second array to generate M′

group signals,

wherein M and M′

are numbers which are different from each other.

16. The method of claim 15, wherein the first and second arrays share photosensitive elements.

17. The method of claim 15, further comprising:

generating a first pair of oscillatory line signals from the M group signals; and

generating a second pair of oscillatory line signals from the M′

group signals.

18. The method of claim 17, further comprising:

comparing a quality of a line signal which is generated from the M group signals with the quality of another line signal which is generated from the M′

group signals; and

selecting a higher quality line signal based on the comparison.

19. The method of claim 17, further comprising:

weighting line signals based on a signal quality characteristic; and

combining the weighted line signals.

20. An optical positioning apparatus, the apparatus comprising:

a two-dimensional array of photosensitive elements organized as an M×

M′

pattern of elements which is repeated to form the array; and

circuitry configured to combine signals from every element in a same position within the pattern so as to generate M×

M′

group signals.