Enhanced resolution automatic data collection apparatus and method using an afocal optical element

• US 8,061,617 B2
• Filed: 07/27/2007
• Issued: 11/22/2011
• Est. Priority Date: 07/28/2006
• Status: Expired due to Fees

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Massieu, Jean-Louis, Gillet, Alain
• Primary Examiner(s): MAI, THIEN T
• Application Number:
  US11/829,398
• Publication Number:
  US 20080023552A1
• Time in Patent Office: 1,579 Days
• Field of Search: 235/462.01, 235/462.32, 235/462.46, 235/462.34, 235/472.01, 235/462.36, 359/492, 359/196, 359/212
• US Class Current: 235/462.36
• CPC Class Codes: G02B 26/0825 the reflecting element being a flexible sheet or membrane, e.g. for varying the focus flexible mirrors for cosmetic use A45D42/24
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: Y10T 29/49069 Data storage inductor or core

Abstract

An automatic data collection device, such as a scanner-type device, is provided with an afocal optical element, such as an afocal lens, that operates in conjunction with a scanning mirror to scan a target machine-readable symbol using a scanning beam. The scanning mirror deflects a light beam into the afocal lens. The afocal lens operates to change a resolution or width of the scanning beam for far-field scanning, for example, where resolution is increased by the afocal lens. The afocal lens can also operate to change the resolution or width of the scanning beam for near-field scanning, for example, where resolution is decreased by the afocal lens.

Claims

1. A method for reading machine-readable symbols using an automatic data collection device, the method comprising:

generating a light beam;

directing the light beam to a scanning mirror;

directing the light beam from the scanning mirror to an afocal optical element, the light beam being incident on the afocal optical element;

using the afocal optical element to change a characteristic associated with a scanning beam; and

exiting the light beam from the afocal optical element as the scanning beam having the changed characteristic and directing the scanning beam having the changed characteristic onto a target machine-readable symbol,

wherein using the afocal optical element to change the characteristic associated with the scanning beam includes using the afocal optical element to decrease a field of view and increase resolution for far-field scanning said target machine-readable symbol at a first time.

2. The method of claim 1, further comprising changing an amplitude of oscillation of the scanning mirror to correspondingly change a resolution associated with the scanning beam.

3. The method of claim 1 wherein directing the scanning beam to the target machine-readable symbol includes directing the scanning beam to a barcode symbol.

4. The method of claim 1 wherein using the afocal optical element to change the characteristic associated with the scanning beam includes using the afocal optical element to change a resolution associated with the scanning beam.

5. The method of claim 1 wherein using the afocal optical element to change the characteristic associated with the scanning beam includes using the afocal optical element to change a field of view associated with the scanning beam.

6. The method of claim 1 wherein directing the light beam from the scanning mirror to the afocal optical element includes directing the light beam to an afocal lens.

7. The method of claim 1, further comprising:

using the afocal optical element to increase a field of view for near-field scanning said target machine-readable symbol at a second time.

8. The method of claim 1, further comprising varying a magnification of the afocal optical element to reduce a field of view for large oscillation of the scanning mirror and to linearize a spot displacement of the scanning beam along a scanning plane.

9. The method of claim 1, further comprising:

receiving at least a portion of light of the scanning beam that is returned from the target machine-readable symbol;

evaluating the received light to provide feedback information indicative of the characteristic associated with the scanning beam; and

using the feedback information to adaptively determine a degree of variation of an optical property associated with the afocal optical element to adjust said characteristic associated with the scanning beam.

10. An automatic data collection device to read machine-readable symbols, the automatic data collection device comprising:

a light source to generate light;

a scanning mirror positioned to have the generated light incident thereon and to deflect the incident light; and

an afocal optical element positioned to receive the deflected light from the scanning mirror and to output a scanning beam derived from the received deflected light, the scanning mirror being movable to move the scanning beam across a target machine-readable symbol, wherein the afocal optical element is adapted to provide an increase in a field of view and a corresponding decreased resolution associated with the scanning beam for near-field scanning.

11. The device of claim 10 wherein the afocal optical element comprises an afocal lens.

12. The device of claim 10 wherein the scanning mirror comprises a microelectromechanical structure (MEMS) mirror.

13. The device of claim 10 wherein the MEMS mirror is formed on a die, and wherein the afocal optical element comprises an optical window that covers the die having said MEMS mirror formed thereon.

14. The device of claim 10, further comprising an actuator coupled to said scanning mirror to vary an amplitude of oscillation of the scanning mirror to correspondingly vary a resolution associated with the scanning beam output from the afocal optical element.

16. The device of claim 10 wherein the afocal optical element has a varying magnification.

17. The device of claim 10, further comprising a housing to house the light source and scanning mirror, wherein the afocal optical element is coupled to the housing.

18. The device of claim 17, further comprising a mounting element to couple the afocal optical element to an internal structure inside the housing, in a manner that the afocal optical element is positioned to receive the deflected incident light from the scanning mirror.

19. The device of claim 10, further comprising a deformable mirror coupled between the light source and the scanning mirror to additionally change a characteristic associated with the scanning beam.

20. The device of claim 10, further comprising:

a light detector to detect a portion of light from the scanning beam that is returned from the target machine-readable symbol; and

a processor coupled to the light detector to evaluate the returned light from the target machine-readable symbol and from the returned light from the target machine-readable symbol, to provide feedback information indicative of a characteristic associated with the scanning beam, the processor further being coupled to make an adjustment to an optical property associated with the afocal optical element based on the feedback information.

21. The device of claim 20 wherein the light detector is adapted to generate an analog signal representative of the returned light from the target machine-readable symbol, the device further comprising:

an analog-to-digital converter coupled to the light detector to change the analog signal to a digital signal; and

a machine-readable medium to store a control algorithm executable by the processor to process the digital signal to decode data encoded by the target machine-readable symbol, wherein the processor in cooperation with the control algorithm is coupled to evaluate the analog signal, the digital signal, or the decoded data to determine a degree of adjustment of the optical property associated with the afocal optical element to correspondingly adjust said characteristic associated with the scanning beam.

22. The device of claim 10 wherein the afocal optical element comprises a deformable lens.

15. An automatic data collection device to read machine-readable symbols, the automatic data collection device comprising:

a light source to generate light;

a scanning mirror positioned to have the generated light incident thereon and to deflect the incident light; and

an afocal optical element positioned to receive the deflected light from the scanning mirror and to output a scanning beam derived from the received deflected light, the scanning mirror being movable to move the scanning beam across a target machine-readable symbol, wherein the afocal optical element is adapted to provide a decrease in a field of view and a corresponding increased resolution associated with the scanning beam for far-field scanning.

23. An article of manufacture, comprising:

a machine-readable medium having instructions stored thereon that are executable by a processor of an automatic data collection device to read machine-readable symbols, by;

causing generation of a light beam that is directed to a scanning mirror positioned to direct the light beam to pass through an afocal optical element to enable said afocal optical element to change a resolution or a field of view associated with said light beam;

actuating the scanning mirror to scan the light beam, which has passed through said afocal optical element and which has said associated resolution or field of view changed by said afocal optical element, across a target machine-readable symbol;

changing a first oscillation amplitude of the scanning mirror at a first time to correspondingly increase the field of view for near-field scanning; and

changing a second oscillation amplitude of the scanning mirror at a second time to correspondingly decrease the field of view and increase the resolution for far-field scanning;

evaluating light received from the target machine-readable symbol to determine a property associated with the light beam; and

using the determined property and the afocal optical element to further change said resolution or field of view associated with the light beam scanned across the target machine-readable medium.

24. The article of manufacture of claim 23 wherein the instructions to use the determined property include instructions to change an amplitude of oscillation of the scanning mirror to correspondingly vary the resolution.

25. The article of manufacture of claim 23 wherein the instructions to evaluate the received light include instructions to evaluate an analog form of the received light, a digital form of the received light, or decoded data from the received light to determine an amount in which to change the resolution or field of view.