Apparatus for diagonal progressive scanning video and method of improving aiming visibility, reducing tilt dependence and improving read range

• US 20060076417A1
• Filed: 08/30/2005
• Published: 04/13/2006
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Massieu, Jean-Louis
• Granted Patent: US 7,407,105 B2
• Time in Patent Office: Days
• US Class Current: 235/462.100
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 2207/1016 Motor control or optical moving unit control
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03

Abstract

A method to improving aiming visibility, reducing tilt dependence and improving read range of a scanner with a very thin lighting path embedding the lighting path 3D volume of view. Physical pixel height is enlarged to aid optical imaging plane alignment. A selective filter centered on the lighting wavelength is placed in the image path. The height of the pixel is artificially reduced to m*w, where m is the lens magnification and w is the light thickness. A laser scanner utilizing a 2D resonant electrostatic micro-mirror to enable projection or acquisition of a discrete image. Diagonal progressive scanning is used to maximize the frequency values so shock resistance of the mirror is increased.

Claims

1. A 2D optical scanner, comprising:

2D gimbals resonant mirror, said 2D gimbals resonant mirror having x- and y-torsional suspension hinges and electrostatic driving electrodes in the plane of the resting position;

two driving clocks, the first driving clock having a first frequency f₁ and the second driving clock having a second frequency, where f1 and f₂ where f₁=f₂*k, where k is a rational number close to 1, n is a natural number and k=161/n;

a variable dc voltage added to the driving clocks such to tune the effective stiffness of the x- and y-torsional suspension hinges in closed-looped control with the detection of X and Y minimum oscillation amplitudes;

a laser beam wherein the beam is projected toward the mirror and deflected in an x-direction and a y-direction by the mirror; and

at least one photocell to receive the deflected light.

2. The 2D scanner of claim 1, wherein the driving clocks frequencies f₁ and f₂ are generated by two digital counters dividing a common clock whose the frequency f_cc is equal to a common multiple of f₁ and f₂.

3. The 2D scanner of claim 2 wherein a scanning field is quantized in discrete elements with a pixel clock having a frequency f_pc equal to or a multiple of the frequency f_cc of the common clock.

4. The 2D scanner of claim 1 wherein the deflected beam has a pin cushion distribution.

5. The 2D scanner of claim 1 wherein the deflected beam traces a stack of n lines in the x-direction and then n lines in the y-direction.

7. The 2D scanner of claim 1, wherein the driving clocks frequencies f₁ and f₂ are generated by two digital counters dividing a common clock whose the frequency f_cc is equal to a common multiple of f₁ and f₂.

8. The 2D scanner of claim 2 wherein a scanning field is quantized in discrete elements with a pixel clock having a frequency f_pc equal to or a multiple of the frequency f_cc of the common clock.

9. The 2D scanner of claim 1 wherein the deflected beam has a pin cushion distribution.

10. The 2D scanner of claim 1 wherein the deflected beam traces a stack of n lines in the x-direction and then n lines in the y-direction.

6. A 2D optical scanner, comprising:

2D gimbals resonant mirror, said 2D gimbals resonant mirror having x- and y-torsional suspension hinges and electrostatic driving electrodes in the plane of the resting position;

two driving clocks, the first driving clock having a first frequency f₁ and the second driving clock having a second frequency, where f1 and f₂ where f₁=f₂*k, where k is a rational number less than 1;

a variable dc voltage added to the driving clocks such to tune the effective stiffness of the x- and y-torsional suspension hinges in closed-looped control with the detection of x and y minimum oscillation amplitudes;

a laser beam wherein the beam is projected toward the mirror and deflected in an x-direction and a y-direction by the mirror; and

at least one photocell to receive the deflected light.

11. A method scanning a bar code comprising the steps of:

illuminating a bar code with an illumination source having a lighting wavelength and a thin, bright lighting path,

embedding said lighting path in 3D volume of view of the bar code,

passing backscattered light from the bar code through a filter centered on the lighting wavelength,

sensing the light backscattered from the barcode by an array of pixels having a pixel height and pixel width,

artificially reducing pixel height to m*w where m is the magnification of a lens in the scanner and w is the thickness of the lighting path;

and decoding the bar code.

12. The method of claim 11 wherein the bar code is read using a scanner comprising an illumination source,

the lens, said lens positioned such that light emitted by the illumination source passes through the lens into a thin, bright beam;

a photosensor comprising the array of pixels, and

the filter, said filter located in front of the sensor, between the lens and the sensor or on the lens.

13. The method of claim 11 wherein said barcode is located at a far field from the scanner.

14. The method of claim 11 wherein the pixel height is increase without increasing the number of pixels in the array.

15. The method of claim 11 further comprising the step of reducing the tilt dependence of the scanner.

16. The method of claim 11 wherein resolution of the image is only dependent on the thickness of the lighting path.

17. The method of claim 12 wherein said barcode is located at a far field from the scanner.

18. The method of claim 12 wherein the pixel height is increase without increasing the number of pixels in the array.

19. The method of claim 14 wherein said barcode is located at a far field from the scanner.

20. The method of claim 14 further comprising the step of reducing the tilt dependence of the scanner.