Backup method for multiple source optical scanner

A backup method for a multiple source optical scanner which alerts an operator when one of the sources has failed. A controller monitors the operation of each source and flags the failed sources. In the case of a scanner having dual full-time channels, the controller removes power from the failed source and disregards the signal from the failed source. In the case of a scanner having non-simultaneously operating sources, the controller switches the remaining source of the scanner to full-time operation. If both sources have failed, power to the failed sources is turned off.

CROSS REFERENCE TO RELATED APPLICATION 
The present invention is related to commonly assigned and U.S. application 
entitled, "Multiple Source Optical Scanner", filed Sep. 14, 1992, invented 
by Tang, and having a Ser. No. 07/944,576. 
BACKGROUND OF THE INVENTION 
The present invention relates to multiple source optical scanners and more 
specifically to a backup method for a multiple source optical scanner. 
In the related Application cited above, a multiple source optical scanner 
is disclosed. A first embodiment of the optical scanner includes a 
plurality of scanning light sources of different wavelengths, collimating 
and focusing optics for producing a beam for each source, reflecting 
optics for aligning each beam in a predetermined direction, a collector 
for collecting light reflected from a bar code label to be scanned, filter 
optics for separating the different wavelengths of light, and processing 
circuitry having a plurality of processing channels for converting the 
reflected light of each wavelength into electrical signals based upon the 
intensities of the reflected light. The first embodiment may also include 
a mirrored spinner and a plurality of pattern mirrors. 
A second embodiment of the optical scanner includes a plurality of scanning 
light sources of the same wavelength, collimating and focusing optics for 
producing a beam for each source, reflecting optics for aligning each beam 
in a predetermined direction, a collector for collecting light reflected 
from a bar code label to be scanned, and processing circuitry having a 
single processing channel for converting the reflected light into 
electrical signals based upon the intensities of the reflected light. The 
scanner additionally includes modulation and control circuitry, which 
turns the sources off and on in sequence. The second embodiment may also 
include a mirrored spinner and a plurality of pattern mirrors. 
While the multiple source optical scanner works well, it is difficult for 
an operator to determine when one of the sources has failed. In such a 
state, the performance of the multiple source optical scanner is reduced. 
Therefore, it would be desirable to provide a backup method for a multiple 
source optical scanner which detects a malfunctioning source and alerts an 
operator. In the case of a scanner having multiple full-time channels, it 
would be desirable to remove power from the failed source, and to 
disregard the signal from the channel of the failed source. In the case of 
a scanner having non-simultaneously operating sources, it would be 
desirable to place the operating sources in a full-time mode of operation. 
SUMMARY OF THE INVENTION 
In accordance with the teachings of the present invention, a backup method 
for a multiple source optical scanner is provided. The method includes the 
steps of monitoring the operation of each source, alerting an operator 
when one of the sources has failed, and flagging the failed source. If the 
scanner employs multiple channels, then the method further includes the 
steps of removing power from the failed sources and disregarding the 
signal from the channels of the failed sources. If the scanner employs 
sources which alternate in operation, then the method further includes the 
step of switching the remaining operating sources to full-time operation. 
If both sources have failed, power is removed from the scanner. 
It is accordingly an object of the present invention to provide a backup 
method for a multiple source optical scanner. 
It is another object of the present invention to provide a backup method 
for a multiple source optical scanner having multiple channels, which 
includes the step of disregarding the signals from the channels of the 
failed sources. 
It is another object of the present invention to provide a backup method 
for a multiple source optical scanner which alerts an operator of the 
malfunctioning sources and which switches the operating sources to a 
full-time mode of operation, if they are not already operating full-time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, a first multiple source optical scanner 10 
includes first laser source 12, second laser source 14, first collimating 
and focusing optics 16, second collimating and focusing optics 18, 
reflector 20, collector 22, filter optics 26, and processing circuitry 28. 
Optical scanner 10 may also include spinner 30 and pattern mirrors 32. 
Laser sources 12 and 14 are preferably laser diodes. Although two are 
shown, any number of laser sources are envisioned. Some commercially 
available laser diodes envisioned for use in the present invention produce 
light at 635 nanometers (nm), 670 nm, and 780 nm. 
First and second beam collimating and focusing optics 16 and 18 produce 
laser beams 34 and 36 and each may include a focusing lens and an 
aperture, as known in the art. 
Reflector 20 orients beam 36 in a desired direction with respect to beam 
34. Preferably, reflector 20 substantially aligns beam 36 with beam 34 to 
produce two beams propagating in the same direction. Reflector 20 may 
include a flat mirror. 
Collector 22 collects light reflected from an item 38 having a bar code 
label 40 to be scanned. Collector 22 may include a collecting mirror with 
a central aperture for passing the outgoing beams 34 and 36. 
Filter optics 26 is located between collector 22 and processing circuitry 
28 and directs the reflected light of different wavelengths into separate 
channels corresponding to the wavelengths of laser sources 12 and 14. 
Processing circuitry 28 converts the reflected light into electrical 
signals based upon the intensity of the reflected light and may send the 
electrical signals to a host terminal, such as a point-of-service (POS) 
terminal 41. 
Where included, spinner 30 and pattern mirrors 32 reflect beams 34 and 36 
in a plurality of directions to form a scan pattern. 
Turning now to FIG. 2, a backup method for use with the scanner of FIG. 1 
is shown, beginning with START 42. 
In block 43, processing circuitry 28 continually monitors laser sources 12 
and 14 to determine if they are operating. 
If both of laser sources 12 and 14 are not operating, then processing 
circuitry 28 determines whether one of laser sources 12 and 14 is working 
in block 44. 
In block 46, if neither of sources 12 and 14 are operating, then processing 
circuitry 28 issues an error code and alerts the operator that both 
sources are malfunctioning. Processing circuitry 28 then instructs the 
operator to remove power from the scanner. 
In block 48, if one of sources 12 and 14 is operating, then processing 
circuitry 28 issues an error code identifying the malfunctioning source 
and alerts an operator that performance will be degraded. Processing 
circuitry 28 disregards the signal from the failed channel and removes 
power from the failed source. 
Referring now to FIG. 3, a second embodiment 60 of the optical scanner of 
the present invention is shown. Like scanner 10, scanner 60 includes first 
laser source 12, second laser source 14, first collimating and focusing 
optics 16, second collimating and focusing optics 18, reflector 20, 
collector 22, and processing circuitry 28. Preferably, laser sources 12 
and 14 emit light at the same wavelength. Optical scanner 60 may also 
include spinner 30 and pattern mirrors 32. 
Scanner 60 additionally includes modulation and control circuitry 62, which 
turns laser sources 12 and 14 off and on in alternating fashion. 
Referring now to FIG. 4, a backup method for use with the scanner of FIG. 3 
is shown, beginning with START 70. 
In block 72, processing circuitry 28 continually monitors laser sources 12 
and 14 to determine if they are operating. 
If both of laser sources 12 and 14 are not operating, then processing 
circuitry 28 determines whether one of laser sources 12 and 14 is working 
in block 74. 
In block 76, if neither of sources 12 and 14 are operating, then processing 
circuitry 28 issues an error code and alerts the operator that both 
sources are malfunctioning. Processing circuitry 28 then instructs the 
operator to shut the scanner off. 
In block 78, if one of sources 12 and 14 is operating, then processing 
circuitry 28 issues an error code identifying the malfunctioning source 
and alerts an operator that performance will be degraded. Processing 
circuitry 28 removes power from the failed source and switches the 
operating source into a full-time mode of operation. 
Although the present invention has been described with particular reference 
to certain preferred embodiments thereof, variations and modifications of 
the present invention can be effected within the spirit and scope of the 
following claims.