Registers – Coded record sensors – Error checking
Reexamination Certificate
1994-05-26
2003-09-02
Shepperd, John (Department: 2514)
Registers
Coded record sensors
Error checking
C235S462490
Reexamination Certificate
active
06612491
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a bar code reading method and a bar code reader each used for terminal equipment such as point of sales (POS) terminal.
2) Description of the Related Art
FIG. 12
is a block diagram showing a configuration of the bar code reading device (bar code reader). Referring now to
FIG. 12
, numeral
31
represents a bar code printed on a surface of an article, the bar code being generally formed of plural black bars and white bars arranged alternately. A predetermined datum is represented based on the width of each black bar and the width of each white bar.
An optical system
32
irradiates a laser beam L
2
onto the bar code
31
and receives a reflected light R
1
, or a laser beam L
2
reflected on the bar code
31
. The optical system
32
also is constituted of a laser emitting unit
33
, a scanning mechanism
34
, and an optical converting unit
35
. The laser emitting unit
33
includes a semiconductor laser device for emitting the laser beam L
1
.
The scanning mechanism
34
is constituted of a polygon mirror that is rotatably driven with, for example, a motor. The scanning mechanism
34
also irradiates the laser beam L
2
to the plural black bars and white bars forming the bar code
31
, the beam L
2
formed by reflecting the laser beam L
1
from the laser emitting unit
33
, while it moves and scans the laser beam at a fixed rate and in the direction perpendicular to the black and white bars of the bar code
31
.
The scanning mechanism
34
irradiates the reflected light R
1
as the reflected light R
2
to the photoelectric converting unit
35
, the reflected light R
1
being the laser beam L
2
reflected by the bar code
31
and traveled with the laser beam L
2
scanned.
The photoelectric converting unit
35
is formed of a photoelectric converting element, for example, a photo diode. The photoelectric converting unit
35
also receives the reflected light R
2
(light input signal) via the scanning mechanism
34
to convert it into an electric signal (analog value) corresponding to the light amount thereof.
The A/D converter unit
36
digitizes the electric signal from the photoelectric converting unit
35
to convert it into a binary signal including a black level signal corresponding to each black portion and a white level signal corresponding to each white portion in the bar code
31
. The white level signal represents a high level signal and the black level signal represents a low level signal because the light amount of the reflected light R
2
reflected by each white bar is larger than that of the reflected light R
2
reflected by each black bar in the binary signal.
Numeral
37
represents a bar width counter for counting clock signals from the clock generator
38
. The bar width counter
37
also outputs as a clock signal count value the time widths of the black level signal portion and the white level signal portion of a binary signal from the A/D converter unit
36
, or each black bar width and each white bar width of an actual bar code
31
.
Furthermore, the memory
39
stores the bar width count value from the bar width counter
37
. The CPU
40
extracts and decodes predetermined data of the bar code
31
based on the bar width count value (a value corresponding to each black bar width or each white bar width) stored in the memory
39
.
In the above structure, the scanning mechanism
34
irradiates the laser beam L
1
emitted from the laser emitting unit
33
as the laser beam L
2
to the black bar and the white bar of the bar code
31
while it moves and scans the laser beam at a constant rate and in the direction perpendicular to the black bar and white bar of the bar code
31
.
The laser beam L
2
emitted from the scanning mechanism
34
is scatteringly reflected on a portion of the bar code
31
and is re-irradiated as the reflected light R
1
to the scanning mechanism
34
. The reflected light R
1
varies its reflection angle as the laser beam L
2
scans and moves. However the polygon mirror constituting the scanning mechanism
34
reflects the reflected light R
1
to input it as the reflected light R
2
to the photoelectric element in the photoelectric converting unit
35
arranged at a predetermined place.
The photoelectric converting unit
35
converts the reflected light R
2
to an electric signal corresponding to the amount thereof. The A/D converter unit
36
digitizes the electric signal into a binary signal including a black level signal corresponding to each black level portion and a white level signal corresponding to each white level portion of the bar code
31
.
The A/D converter unit
36
produces a digital signal as a binary signal. The bar width counter
37
counts clock signals from the clock generator
38
so that the time width (a value corresponding to the widths of each black bar and each white bar of an actual bar code
31
) of the black level signal portion and the white level signal portion of the binary signal from the A/D converter unit
36
is measured as a clock signal count value. The memory
39
stores temporarily the count value. The CPU
40
subjects the bar width count value stored in the memory
39
to a predetermined decoding process to extract and decode the determined data of the bar code
31
.
FIG. 13
is a diagram showing a bar code reader which converts an electrical signal (analog signal) corresponding to the amount of the light R
2
reflected from the photoelectric converting unit
35
into a binary signal to store in the memory
39
.
As shown in
FIG. 13
, the bar code reader is constituted of the bar code information detection unit
41
in the photoelectric converting unit
35
, the A/D converting unit
36
, the binary data converting unit
42
having the comprehensive function of the bar width counter
37
and the clock
38
, and the FIFO (first-in first-out) memory
43
acting as the memory
39
.
In such a structure, the bar code information detecting unit
41
first detects the bright and dark information on the bar width of the bar code
31
as an analog signal. Next the binary data converting unit
42
converts the analog signal into binary data to store sequentially in the FIFO memory
43
.
The binary data stored in the FIFO memory
43
includes a large amount of the so-called trash data, or data being not the bar width bright and dark information of the bar code
31
. For example, noises due to stains on the paper on which the bar code
31
is printed may be outputted as a bar width detection signal.
However, in the above bar code reading method and the bar code reader, there is a problem that if the bar code information read should include a large amount of trash data, it is difficult to find quickly normal bar code data and the decreased normal bar code storage efficiency degrades the reliability of the bar code reader.
SUMMARY OF THE INVENTION
The present invention is made to overcome the above described problems. An object of the present invention is to provide a bar code reading method which provides an improved bar code reading rate and an improved effective bar code storage efficiency by detecting trash data so as not to store them in a memory.
Another object of the present invention is to provide a bar code reader which provides an improved bar code reading rate and an improved effective bar code storage efficiency by detecting trash data so as not to store them in a memory.
In order to achieve the above object, according to the present invention, the bar code reading method is characterized by the steps of detecting bright and dark information of a bar width based on a bar code; converting the detected bright and dark information into binary information; storing plural pieces of the converted binary information; sequentially outputting the plural pieces of the binary information on a first-in, first-out basis; detecting binary information as error information when plural pieces of bar code bright and dark information do not come alternately in a binary information storing operation; and storing only the last dat
Iwaguchi Isao
Sato Shin'ichi
Fujitsu Limited
Shepperd John
Staas & Halsey , LLP
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