# US 6,293,468 B1 · Pulsed barcode scanner

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- Number: US 6,293,468 B1
- Document ID: US6293468B1
- Status: Granted
- Kind: B1
- Application number: 09/184,799
- Filed: 1998-11-02
- Granted: 2001-09-25
- Earliest claimed: 1998-11-02
- Assignees: NCR Corporation
- Inventors: Edward G. Rantze; Joseph M. Lindacher
- Web page: https://patentgrep.com/patent/US6293468B1

## CPC

- G06K 7/10851: {Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device (basic electronic circuitry H03)}
- G06K 7/10584: {Source control}
- G06K 7/10613: {by rotation, e.g. polygon}
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS

## Abstract

A barcode is scanned by a scanner having a laser emitting a pulsed laser beam which reflects off the barcode and is detected by a light detector. A receiver operatively joined to the light detector is tuned to the frequency of the pulsed laser beam for increasing signal gain.

## Claims

### Claim 1

A scanner for scanning a barcode comprising:
a pulse-mode laser for emitting across said barcode a laser beam pulsed at a pulse frequency;
a light detector for detecting said laser beam reflected off said barcode at a data rate different than said pulse frequency; and
a receiver operatively joined to said light detector and tuned to said pulse frequency for resolving said reflected laser beam at said pulse frequency to decode said barcode.

### Claim 2 (depends on 1)

A scanner according to claim 1 wherein said receiver includes a narrow bandwidth for detecting substantially only said pulse frequency, with a correspondingly high gain.

### Claim 3 (depends on 2)

A scanner according to claim 2 wherein said pulse frequency is substantially constant.

### Claim 4 (depends on 3)

A scanner according to claim 3 wherein said pulse frequency is greater than said data rate.

### Claim 5 (depends on 3)

A scanner according to claim 3 wherein said light detector has a frequency response for detecting said reflected laser beam at said pulse frequency.

### Claim 6 (depends on 3)

A scanner according to claim 3 further comprising a digital signal processor operatively joined to said receiver for decoding said reflected beam.

### Claim 7 (depends on 3)

A scanner according to claim 3 further comprising means for sweeping said pulsed laser beam across said barcode, and said light detector is coupled to said sweeping means.

### Claim 8 (depends on 7)

A scanner according to claim 7 wherein said sweeping means comprise:
a rotary spinner having a plurality of reflective facets optically aligned with said laser;
a plurality of pattern mirrors optically aligned with said spinner for sweeping said laser beam across said barcode; and
said pattern mirrors being narrow in height to substantially match sweeping path of said laser beam from said spinner; and
wherein said light detector is optically aligned with said spinner for detecting said reflected laser beam, and has a field of view correspondingly narrow with said pattern mirrors.

### Claim 9 (depends on 8)

A scanner according to claim 8 wherein said light detector comprises a compound curvature collector for condensing said reflected laser beam onto an adjoining photodetector.

### Claim 10 (depends on 3)

A scanner according to claim 3 further comprising means for sweeping said pulsed laser beam across said barcode, and said light detector is decoupled from said sweeping means.

### Claim 11 (depends on 10)

A scanner according to claim 10 wherein said light detector has a large field of view for detecting said reflected laser beam from said barcode.

### Claim 12

A method of scanning a barcode comprising:
sweeping across said barcode a laser beam pulsed at a pulse frequency;
detecting said laser beam reflected off said barcode at a data rate different than said pulse frequency by tuning to said pulse frequency; and
decoding said barcode by resolving said detected pulsed laser beam at said pulse frequency.

### Claim 13 (depends on 12)

A method according to claim 12 further comprising detecting substantially only said pulse frequency within a narrow bandwidth, and with a correspondingly high gain.

### Claim 14 (depends on 13)

A method according to claim 13 wherein said pulse frequency is substantially constant.

### Claim 15 (depends on 14)

A method according to claim 14 wherein said pulse frequency is greater than said data rate.

### Claim 16 (depends on 15)

A method according to claim 15 wherein said pulsed laser beam is modulated in power by reflection from said barcode, and said reflected laser beam is resolved in amplitude modulation for decoding said barcode.