OPTICAL FILTER FOR IMAGE AND BARCODE SCANNING

• US 20120325912A1
• Filed: 12/01/2011
• Published: 12/27/2012
• Est. Priority Date: 06/27/2011
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wang, Ynjiun Paul, Ding, Yiwu, Feng, Chen
• Granted Patent: US 8,640,960 B2
• Time in Patent Office: Days
• US Class Current: 235/462.06
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

Methods for using an optical indicia reading terminal including a housing, a multiple pixel image sensor disposed within the housing, an imaging lens assembly configured to focus an image of decodable indicia on the image sensor, an optical bandpass filter disposed in an optical path of light incident on the image sensor, an analog-to-digital (A/D) converter configured to convert an analog signal read out of the image sensor into a digital signal representative of the analog signal, and processor configured to output a decoded message data corresponding to the decodable indicia by processing the digital signal.

Claims

1. A method for decoding indicia that includes a displayed decodable indicia displayed on a display having a wavelength emission spectrum the method comprising:

providing an optical indicia reading terminal comprising a housing, a multiple pixel image sensor disposed within said housing, an imaging lens assembly configured to focus an image of a decodable indicia on said multiple pixel image sensor, an optical bandpass filter disposed in an optical path of light incident on said multiple pixel image sensor, said optical bandpass filter configured to pass light of one or more selected ranges of wavelengths and to attenuate light of wavelengths outside of said one or more selected ranges, wherein a transmission profile of the optical band pass filter is matched to said wavelength emission spectrum of said display, an analog-to-digital converter configured to convert an analog signal read out of said multiple pixel image sensor into a digital signal representative of said analog signal, said analog signal representative of the light incident on said multiple pixel image sensor; and

a processor configured to output a decoded message data corresponding to said decodable indicia by processing said digital signal; and

using said optical indicia reading terminal to decode said decodable indicia displayed on said display having said wavelength emission spectrum.

4. The method of claim 1, wherein said wavelength emission spectrum includes narrow band emissions in the red, green and blue wavelength bands, and wherein the transmission profile of the optical band pass filter is matched to the wavelength emission spectrum by being adapted to transmit light in first, second and third narrow wavelength bands within the red, green and blue wavelength ranges in a manner such that a center wavelength of emission is aligned to a center wavelength of transmission of at least one of said narrow band emissions in the red, green, and blue wavelength bands.

5. The method of claim 1, wherein said wavelength emission spectrum includes narrow band emissions in the red, green and blue wavelength bands, and wherein the transmission profile of the optical band pass filter is matched to the wavelength emission spectrum by being adapted to transmit the full width half maximum wavelength ranges of at least one of said narrow band emissions in the red, green, and blue wavelength bands.

6. The method of claim 1, wherein said wavelength emission spectrum includes narrow band emissions in the red, green and blue wavelength bands, and wherein the transmission profile of the optical band pass filter is matched to the wavelength emission spectrum by providing the optical bandpass filter to include a single passband spanning the visible light spectrum.

7. The method of claim 1, wherein said transmission profile is based, at least in part, on actual spectrum data for one or more displays.

8. The method of claim 1, wherein said transmission profile is based, at least in part, on manufacturing data for one or more displays.

11. The method of claim 1, wherein the providing includes the providing the terminal so that the optical band pass filter has a variable emission profile.

12. The method of claim 11, wherein the providing includes providing the terminal so that the variable emission profile is variable responsively to a manually input control.

13. The method of claim 11, wherein the providing includes providing the terminal so that the variable emission profile is variable responsively to an automatically input control.

14. The method of claim 1, wherein the providing includes providing the terminal to include a light source for directing light towards a target and a first configuration available among one or more alternative configurations that can be activated responsively to an operator input control, wherein when the first configuration is active, the light source is maintained off during exposure of a frame occurring responsively to a trigger signal activation, wherein when at least one of the one or more alternative configurations is active, the light source is maintained on during exposure of a frame occurring responsively to a trigger signal activation, the method including inputting the manually input control to activate the first configuration.

15. The method of claim 1, wherein the providing includes providing the terminal to include a light source for directing light towards a target and a first configuration available among one or more alternative configurations that can be activated responsively to an operator input control, wherein when the first configuration is active, (a) the light source is maintained off during exposure of a frame occurring responsively to a trigger signal activation and (b) the transmission profile is controlled to match the wavelength transmission spectrum of the display, wherein when at least one of the one or more alternative configurations is active) the light source is maintained on during exposure of a frame occurring responsively to a trigger signal activation.

2. The method of 1, wherein said wavelength emission spectrum includes narrow band emissions in the red, green and blue wavelength bands, and wherein the transmission profile of the optical band pass filter is matched to the wavelength emission spectrum by being adapted to transmit light in first, second and third narrow wavelength bands within the red, green and blue wavelength ranges and being further adapted to attenuate light at wavelengths between the first and second narrow wavelengths bands, and between the second and third narrow wavelength bands.

3. The method of 1, wherein said wavelength emission spectrum includes narrow band emissions in the red, green and blue wavelength bands, and wherein the transmission profile of the optical band pass filter is matched to the wavelength emission spectrum by being adapted to transmit light in one or more of said first, second, and third narrow wavelength bands within the red, green and blue wavelength ranges and by being further adapted to attenuate light at wavelengths outside of the one or more first, second, and third narrow wavelength bands.

9. The method of 1, wherein said multiple pixel image sensor comprises a micro-lens;

and wherein said optical bandpass filter is disposed at a surface of said micro-lens.

10. The method of 1, wherein said housing is provided by a hand held housing.

16. A decodable indicia reading terminal comprising:

a housing including a housing window;

a multiple pixel image sensor disposed within said housing;

an imaging lens assembly configured to focus an image of a decodable indicia on said multiple pixel image sensor;

an optical bandpass filter having a variable transmission profile disposed in an optical path of light incident on said multiple pixel image sensor, said optical bandpass filter configured to pass light of one or more selected ranges of wavelengths and to attenuate light of wavelengths outside of said one or more selected ranges;

an analog-to-digital (A/D) converter configured to convert an analog signal read out of said multiple pixel image sensor into a digital signal representative of said analog signal, said analog signal representative of light incident on said multiple pixel image sensor; and

a processor configured to output a decoded message data corresponding to said decodable indicia by processing said digital signal.

17. The decodable indicia reading terminal of claim 16, wherein the transmission profile of the optical bandpass filter is variable in response to a manually input control input into the terminal.

18. The decodable indicia reading terminal of claim 16, wherein the transmission profile of the optical bandpass filter is variable between a first transmission profile in which the optical bandpass filter passes light in the red band(s) and attenuates light outside of the red band(s) and a second transmission profile in which the optical bandpass filter passes light in the blue and green bands and attenuates light outside of the blue and green bands.

19. The decodable indicia reading terminal of claim 16, wherein the transmission profile of the optical bandpass filter is variable between a first transmission profile in which the optical bandpass filter passes light in the red band(s) and attenuates light outside of the red band(s) and a second transmission profile in which the optical bandpass filter passes light in the blue band(s) and attenuates light outside of the blue band(s).

20. The decodable indicia reading terminal of claim 16, wherein the transmission profile of the optical bandpass filter is variable between a first transmission profile in which the optical bandpass filter passes light in the red and blue bands and attenuates light outside of the red and blue bands and a second transmission profile in which the optical bandpass filter passes light in the red and green bands and attenuates light outside of the red and green bands.

21. The decodable indicia reading terminal of claim 16, wherein the transmission profile of the optical bandpass filter is variable between a first transmission profile in which the optical bandpass filter passes light in the blue and green bands and attenuates light outside of the blue and green bands and a second transmission profile in which the optical bandpass filter passes light in the blue and red bands and attenuates light outside of the blue and red bands.

22. A method of making an optical indicia reading terminal, the method comprising:

determining the wavelength emission spectrum of a display capable of displaying a decodable indicia;

disposing in an optical reading assembly a multiple pixel image sensor, an imaging lens assembly configured to focus an image of said decodable indicia on said multiple pixel image sensor, an optical bandpass filter disposed in an optical path of light incident on said multiple pixel image sensor, said optical bandpass filter configured to pass light of one or more selected ranges of wavelengths and to attenuate light of wavelengths outside of said one or more selected ranges, an analog-to-digital converter configured to convert an analog signal read out of said multiple pixel image sensor into a digital signal representative of said analog signal, said analog signal representative of the light incident on said multiple pixel image sensor, and a processor configured to output a decoded message data corresponding to said decodable indicia by processing said digital signal; and

incorporating the optical reading assembly into a housing;

wherein one of said selected ranges of wavelengths corresponds to said wavelength emission spectrum of said display.