Optical scanner having a plurality of scanning systems

An optical scanner for optically scanning a bar code includes a housing having a window formed on a selected surface thereof, a first scanning system, housed in the housing, for emitting a first scanning beam from the housing through the window and a second scanning system, housed in the housing, for emitting a second scanning beam from the housing through the window. The first scanning beam moves in a first scanning pattern and the second scanning beam moves in a second scanning pattern which is different from the first scanning pattern. Additionally, the second scanning pattern may be used for scanning a bar code having a selected special form.

BACKGROUND OF THE INVENTION 
(1) Field of the invention 
The present invention generally relates to an optical scanner, and more 
particularly to an optical scanner applicable to a bar code reader. 
(2) Description of the related art 
To increase the efficiency of merchandise management and checking, POS 
(Point of Sales) systems have been introduced in department stores and 
supermarkets. The POS system is provided with a bar code reader for 
optically reading bar codes attached onto commodities so that information 
regarding the commodities is efficiently input to the POS system. 
Recently, various commodities have had bar codes attached thereto, and bar 
codes having various forms have been used in accordance with the shapes of 
the commodities. Thus, it is required that the bar code reader be able to 
read bar codes having various forms. 
In addition, use of the bar code readers has become popular in small-scale 
supermarkets, small-scale department stores and specialty stores in all of 
which service counters provided with bar code readers are small. Thus, it 
is required that the bar code readers used therein be miniaturized. 
FIG. 1 and FIG. 2 show a stationary type of conventional bar code reader. 
Referring to FIG. 1, a window 2 is formed on a top surface of a housing 1 
of a bar code reader. A laser beam is emitted through the window 2 to form 
a scanning pattern 3 formed of scanning lines extending in various 
directions. When a commodity is brought into a space over the window 2, a 
surface of the commodity is scanned by the laser beam having the scanning 
pattern 3. A reflected beam from the surface of the commodity returns into 
the housing 1 of the bar code reader through the window 2. 
A scanning unit as shown in FIG. 2 is mounted in the housing 1. Referring 
to FIG. 2, the scanning unit has a laser diode 4, a beam forming lens 5, a 
polygonal mirror 6, and a reflecting mirror 7 having three surfaces. A 
laser beam 4a emitted from the laser diode 4 travels to the polygonal 
mirror 6 via the beam forming lens 5 and is reflected by surfaces of the 
polygonal mirror 6. A reflected laser beam 4b from the polygonal mirror 6 
travels to the three surfaces of the reflecting mirror 7 and scans them. 
The laser beam 4b reflected by the three surfaces of the reflecting mirror 
7 is emitted from the housing 1 through the window 2, and three scanning 
lines extending in directions corresponding to the three surfaces of the 
reflecting mirror 7 are formed in a space over the window 2. That is, the 
scanning pattern 3 is formed in the space over the window 2. A laser beam 
reflected by a surface of a commodity onto which a bar code is attached 
returns into the housing 1 through the window 2. The laser beam 4c 
entering the housing 1 travels to a photodetector 8 via the reflecting 
mirror 7 and the polygonal mirror 6. The photodetector 8 outputs signals 
corresponding to the pattern of the bar code attached onto the surface of 
the commodity. 
In the above stationary type of bar code reader, it is desired that the 
commodity be positionable within a wide range of positions, and that the 
bar code on the commodity be precisely readable in any of these positions. 
Thus, the scanning pattern 3 is formed of many scanning lines extending in 
various directions. According to this structure of the scanning pattern, 
no matter where the commodity is positioned in the space over the window 
2, at least one of the scanning lines can certainly cross all bars of the 
bar code attached onto the surface of the commodity. However, to increase 
the number of scanning lines, the laser beam reflected by the polygonal 
mirror 6 must be divided into many beams corresponding to the scanning 
lines by the reflecting mirror 7 having many surfaces. As a result, each 
of the scanning lines is shortened. If the bar code reader is 
miniaturized, a range within which the laser beam can be swung by the 
polygonal mirror 6 becomes narrow. In this case, each of the scanning line 
is further shortened. When each of the scanning lines is shortened, it is 
difficult to read a bar code having a long sideways form in which the 
respective distances between the bars are large. 
In addition, in the stationary type of bar code reader, it is also desired 
that the space in which the bar code can be precisely read be large. Thus, 
as shown in FIG. 3A, a focal point (f) of the laser beam 4b emitted 
through the window 2 is positioned over the window 2. To precisely read 
the bar code, the spot of the laser beam must be smaller than the 
respective distances between the bars of the bar code. That is, the focal 
point (f) is positioned over the window 2 such that the spot of the laser 
beam 4b on the surface of the window 2 is smaller than the respective 
distances between the bars of the bar code having a normal form. As a 
result, a space having a readable depth S.sub.H1 as shown in FIG. 3A is 
set, as the space in which the bar code can be read, over the window 2. If 
the focal point (f) of the laser beam 4b is positioned on the surface of 
the window 2 as shown in FIG. 3B, a readable depth S.sub.H2 is less than 
the readable depth S.sub.H1 shown in FIG. 3A. Thus, as described above, 
the focal point (f) of the laser beam 4b is positioned over the window 2. 
In a case where a bar code in which respective distances between bars are 
small is to be read by the laser beam, the bar code must be scanned by the 
beam spot close to the focal point (f) of the laser beam. However, in this 
case, as the focal point (f) of the laser beam is positioned so as to be 
separated from the surface of the window 2 as shown in FIG. 3A, it is 
difficult to bring the bar code to a position at which the beam spot close 
to the focal position (f) of the laser beam can scan the bar code. In 
addition, when missreading of the bar code occurs, the operator tends to 
bring the bar code close to the surface of the window 2. However, the 
closer the bar code is brought to the surface of the window 2, the larger 
the spot of the laser beam becomes, as shown in FIG. 3A. Thus, when the 
bar code is brought close to the surface of the window 2, missreading of 
the bar code occurs frequently. 
SUMMARY OF THE INVENTION 
Accordingly, a general object of the present invention is to be provide a 
novel and useful optical scanner in which the disadvantages of the 
aforementioned prior art are eliminated. 
A more specific object of the present invention is to provide an optical 
scanner in which both a bar code having a normal form and a bar code 
having a special form can be precisely scanned. 
The above objects of the present invention are achieved by an optical 
scanner for optically scanning a bar code, the optical scanner comprising: 
a housing having a window formed on a predetermined surface thereof; a 
first scanning system, housed in the housing, for emitting a first 
scanning beam from the housing through the window, the first scanning beam 
moving in a first scanning pattern; and a second scanning system, housed 
in the housing, for emitting a second scanning beam from the housing 
through the window, the second scanning beam moving in a second scanning 
pattern different from the first scanning pattern, the second scanning 
pattern being suitable for scanning a bar code having a predetermined 
special form. 
According to the present invention as described above, a bar code having a 
normal form can be precisely scanned by the first scanning beam moving in 
the first scanning pattern, and a bar code having a special form can be 
precisely scanned by the second scanning beam moving in the second 
scanning pattern. 
Since a bar code having a long sideways form can be precisely scanned by 
the second scanning beam, it is preferable that a scanning line included 
in the second scanning pattern be longer than a scanning line included in 
the first scanning pattern. 
Further, since a bar code has a form in which respective distances between 
bars can be precisely scanned by the second scanning beam, it is 
preferable that a focal point of the second scanning beam be positioned on 
or close to a surface of said window. 
Additional objects, features and advantages of the present invention will 
become apparent from the following detailed description when read in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A description will now be given, with reference to FIG. 4, of the principle 
of an embodiment of the present invention. 
Referring to FIG. 4, a light source 17, a lens system 19, a scanning 
mechanism 16, a first mirror 14, a second mirror 15 and a photo detector 
18 are provided in a housing 100 of a bar code reader. A light beam 
emitted from the light source 17 travels to the scanning mechanism 16 
through the lens system 19. The light beam is divided into a first 
scanning beam 12 and a second scanning beam 13 by the scanning mechanism 
16. The scanning mechanism 16 swings the first scanning beam 12 and the 
second beam 13 in predetermined ranges, respectively. The first scanning 
beam 12 travels to the first mirror 14 and is reflected thereby. The first 
scanning beam 12 reflected by the first mirror 14 is emitted to the 
outside of the housing 100 through the transparent surface 11 of the 
housing 100. The first scanning beam 12 swung by the scanning mechanism 16 
forms a first scanning pattern 10 in a first space over the transparent 
surface 11 of the housing 100. The second scanning beam 13 travels to the 
second mirror 15 and is reflected thereby. The second scanning beam 12 
reflected by the second mirror 15 is emitted to the outside of the housing 
100 through a transparent surface 11 of the housing 100. The second 
scanning beam 12 swung by the scanning mechanism 16 forms a second 
scanning pattern 20 in a second space over the transparent surface 11 of 
the housing 100. 
The first scanning pattern 10 is formed, for example, so as to have many 
scanning lines extending in various directions. As a result, in a case 
where a bar code is scanned by the first scanning beam 12 having the first 
scanning pattern 10, it is acceptable for the bar code to be arranged in 
various directions in the first space. In addition, the focal point of the 
first scanning beam 12 is, for example, positioned over the transparent 
surface 11 of the housing 100 such that the readable depth in the first 
space is large. 
The second scanning pattern 20 is formed, for example, so that each 
scanning line thereof is long. As a result, the bar code having a long 
sideways form can be precisely scanned by the second scanning beam 13. In 
addition, the focal point of the second scanning means 13 is positioned 
close to the transparent surface 11 of the housing 100. As a result, in a 
case where the bar code has a form in which the distances between bars are 
small, the bar code can be precisely read by the second scanning beam 13 
due to the bar code being brought close to the transparent surface 11 of 
the housing 100. 
A description will now be given of a first embodiment of the present 
invention. 
FIG. 5 shows a structure of the bar code reader according to the first 
embodiment of the present invention. Referring to FIG. 5, the laser diode 
4, the beam forming lens 5, the polygonal mirror 6, the first reflecting 
mirror 7, a second reflecting mirror 24, a condenser lens 25 and a photo 
detector 8 are mounted in a housing 21 of the bar code scanner. The 
housing 21 has a top surface on which a window 22 is formed as shown in 
FIG. 6. A laser beam emitted by the laser diode 4 travels to the polygonal 
mirror 6 through the beam forming lens 5. The polygonal mirror 6 is 
rotated by a motor (not shown) at a constant speed and has first surfaces 
6a and second surfaces 6b as shown in FIG. 7B. The first reflecting mirror 
7 is positioned in the upward side of the second reflecting mirror 24 as 
shown in FIG. 7B. The first surfaces 6a of the polygonal mirror 6 are 
inclined such that the laser beam reflected by each of the first surfaces 
6a travels to the first reflecting mirror 7. The second surfaces 6b of the 
polygonal mirror 6 are inclined such that the laser beam reflected by each 
of the second surfaces 6b travels to the second reflecting mirror 24. The 
surface of the first reflecting mirror 7 is divided into three segments. 
The inclination of the first reflecting mirror 7 and the inclination of 
the second reflecting mirror 24 are adjusted such that the laser beam 
reflected by the first reflecting mirror 7 and the laser beam reflected by 
the second reflecting mirror 24 do not interfere with each other. 
The laser beam reflected by each of the first surfaces 6a of the polygonal 
mirror 6 is swung by the rotation of the polygonal mirror 6 and scans the 
three segments of the first reflecting mirror 7. The laser beam is 
reflected by the respective segments of the first reflecting mirror 7 in 
different directions. As a result, the laser beam reflected by the first 
reflecting mirror 7 is emitted through the window 22 and forms the first 
scanning pattern 3 having three scanning lines corresponding to the three 
segments of the first reflecting mirror 7. The laser beam reflected by the 
first reflecting mirror 7 is referred to as a multi-direction scanning 
beam 26. The multi-direction scanning beam 26 is used for scanning bar 
codes each of which has a normal form. 
The laser beam reflected by each of the second surfaces 6b of the polygonal 
mirror 6 is swung by the rotation of the polygonal mirror 6 and scans the 
surface of the second reflecting mirror 24. The laser beam reflected by 
the second reflecting mirror 24 travels in a direction corresponding to 
the inclination of the second reflecting mirror 24 and is emitted through 
the window 22. As a result, the laser beam forms the second scanning 
pattern 9 having a single scanning line. A scanning line on the surface of 
the second reflecting mirror 24 is not divided into a plurality of 
segments. Thus, the scanning line of the second scanning pattern 9 is 
longer than each of the scanning lines of the first scanning pattern 3. 
The laser beam reflected by the second reflecting mirror 24 is used for 
scanning bar codes, each of which has a special form. This laser beam is 
referred to as a special scanning beam 27. An area, on the window 22, 
through which the special scanning beam 27 is emitted, is surrounded by a 
line as shown in FIG. 6. This area is referred to as a special code 
reading area 23. Due to special code reading area 23, an operator can 
easily recognize an area through which the special scanning beam 27 is 
emitted. 
The length of an optical path in which the multi-direction scanning beam 26 
travels, is adjusted such that the focal point (f) of the multi-direction 
scanning beam 26 is positioned over the window 22 as shown in FIG. 3A. The 
length of an optical path in which the special scanning beam 27 travels, 
is adjusted such that the focal point (f) of the special scanning beam 27 
is positioned on or close to the surface of the window 22 as shown in FIG. 
3B. 
When the multi-direction scanning beam 26 scans a bar code on the surface 
of a commodity and is reflected by the surface, the reflected beam returns 
into the housing 21 through the window 22. The reflected beam then travels 
to the photodetector 8 via the first reflecting mirror 7, each of the 
first surfaces 6a of the polygonal mirror 6 and the condenser lens 25, as 
shown in FIGS. 7A and 7B. The special scanning beam 27 reflected by the 
surface of a commodity on which a bar code is formed returns into the 
housing 21 through the special code reading area 23 (shown in FIG. 6) and 
travels to the photodetector 8 via the second reflecting mirror 24, each 
of the second surfaces 6b of the polygonal mirror 6 and the condenser lens 
25, as shown in FIG. 7B. 
The operator brings a commodity into a space in which the first scanning 
pattern 3 is formed. A bar code formed on the surface of the commodity is 
scanned by the multi-direction scanning beam 26 forming the first scanning 
pattern 3. At least one of the scanning lines of the first scanning 
pattern 3 crosses all the bars of the bar code. At this time the 
photodetector 8 outputs a signal modulated in accordance with the pattern 
of the bar code. If the bar code has the long sideways form, each of the 
scanning lines of the first scanning pattern 3 can not cross all the bars 
of the bar code. Thus, a missreading occurs. In this case, the operator 
brings the commodity provided with the bar code having the long sideways 
form close to the special code read area 23 on the window 22. The special 
scanning beam 27 then scans the bar code such that the scanning line of 
the second scanning pattern crosses all the bars of the bar code. As a 
result, the bar code having the long sideways form can be precisely read. 
If the bar code has a form in which the respective distances between bars 
are small, the beam spot of the multi-direction beam 26 projecting onto 
the surface having the bar code is larger than the distance between the 
bars of the bar code. Thus, the bar code, cannot be precisely read and a 
missreading occurs. In this case, the operator brings the bar code formed 
on the surface of the commodity to or in contact with the surface of the 
special code read area 23 of the window 22. As the focal point (f) of the 
special scanning beam 27 is positioned on or close to the surface of the 
window 22, the spot of the special scanning beam 27 projected onto the 
surface of the commodity on which the bar code is formed is very small. 
Thus, the bar code can be scanned by the very small spot. As a result, the 
bar code having the form in which respective distances between bars are 
small, can be optically read in a precise manner. 
A processing circuit for processing signals output from the photodetector 8 
is formed as shown in FIG. 8. Referring to FIG. 8, the processing circuit 
has an amplifier 131, a detecting circuit 132, a decoder 133, a CPU 
(Central Processing Unit) 134 and an interface unit 35. The photodetector 
8 outputs a signal corresponding to a laser beam supplied through the 
condenser lens 25, as shown in FIG. 9 (2). The signal output from 
photodetector 8 is supplied to the detecting circuit 132 via the amplifier 
131. The detecting circuit 132 converts the signal from the photodetector 
8 into bi-level signals such as a BEG signal and a WEG signal, as shown in 
FIG. 9 (3) and (4). The bi-level signals (BEG and WEG) are supplied to the 
decoder 133. The decoder 133 generates decode data Do, D1, D2, D3, D4, D5, 
D6, . . . based on the bi-level signals (BEG and WEG), as shown in FIG. 9 
(5). The decode data is supplied to the CPU 134. The CPU 134 generates 
code data corresponding to the bar code based on the decode data. The code 
data is then supplied to a host system via the interface unit 135. 
A description will now be given, with reference to FIGS. 10, 11, 12A, 12B, 
13, 14A, 14B, and 15, of a second embodiment of the present invention. 
Referring to FIGS. 10, 12A, 12B, 14A and 14B, the laser diode 4, the beam 
forming lens 5, the first reflecting mirror 7, the photodetector 8, the 
condense lens 25, a polygonal mirror 32, a shading plate 33, and mirrors 
34 and 35 are provided in a housing 31 of the bar code scanner. As shown 
in FIG. 11, a first window 36 and a second window 37 are formed on a top 
surface of the housing 31. The polygonal mirror 36 is formed like a hand 
dram so as to have upper surfaces 32a facing obliquely downward and lower 
surfaces 32b facing obliquely upward. The upper surfaces 32a include first 
upper surfaces 32a1 and second upper surfaces 32a2, and the lower surfaces 
32b include first lower surfaces 32b1 and second lower surfaces 32b2. 
A laser beam emitted by the laser diode 4 travels to the polygonal mirror 
32 via the beam forming lens 5 and the mirrors 34 and 35 as shown in FIG. 
12A. The laser beam projected onto each of the first lower surfaces 32b1 
of the polygonal mirror 32 is reflected thereby and travels to each of the 
corresponding first upper surfaces 32a1. The laser beam reflected by each 
of the first upper surfaces 32a1 of the polygonal mirror 32 travels to the 
first reflecting mirror 7 as shown in FIG. 12B. That is, the respective 
angles of the first upper surfaces 32a1 and those of the first lower 
surfaces 32b1 with respect to the axis of the polygonal mirror 32 are 
adjusted such that the laser beam reflected by them travels to the first 
reflecting mirror 7. The laser beam projected onto each of the second 
lower surfaces 32b2 is reflected thereby and travels to each of the 
corresponding second upper surfaces 32a2 as shown in FIG. 14B. The laser 
beam reflected by each of the second upper surfaces 32a2 travels to the 
second reflecting mirror 24. That is, the respective angles of the second 
upper surfaces 32a2 and each of the second lower surfaces 32b2 with 
respect to the axis of the polygonal mirror 32 are adjusted such that the 
laser beam reflected by them travels to the second reflecting mirror 24. 
The laser beam reflected by the first reflecting mirror 7 is emitted to the 
outside of the housing 31 through the first window 36. The surface of the 
first reflecting mirror 7 is divided into three segments so that three 
scanning lines are formed in the space over the first window 36. In 
addition, the angles of the respective first upper surfaces 32a1 with 
respect to the axis of the polygonal mirror 32 slightly differ from each 
other, and the angles of the first lower surfaces 32b1 with respect to the 
axis of the polygonal mirror 32 slightly differ from each other. Thus, 
while the polygonal mirror 32 is being rotated, the laser beam 26 
reflected by the respective first upper surfaces 32a1 scans the first 
reflecting mirror 7 on different lines. As a result, the first scanning 
pattern 3a is formed as a set of a plurality of line patterns as shown in 
FIG. 13, each line pattern being formed of three scanning lines 
corresponding to the (three) segments of the surface of the first 
reflecting mirror 7. The number of patterns in the set is equal to the 
number of first upper surfaces 32a1 (first lower surfaces 32b1) of the 
polygonal mirror 32. 
The laser beam reflected by the second reflecting mirror 24 is emitted to 
the outside of the housing 31 through the second window 37 as shown in 
FIG. 15. Angles of the respective second upper surfaces 32a2 with respect 
to the axis of the polygonal mirror 32 differ slightly from each other, 
and angles of the second lower surfaces 32b2 with respect to the axis of 
the polygonal mirror 32 differ slightly from each other. Thus, while the 
polygonal mirror 32 is being rotated, the laser beam 27 reflected by the 
respective second upper surfaces 32a2 scans the second reflecting mirror 
24 on different lines. As a result, the second scanning pattern 9a is 
formed as a set of a plurality of line patterns as shown in FIG. 15, each 
line pattern being formed of a single scanning line corresponding to the 
surface of the first reflecting mirror 7. The number of patterns in the 
set is equal to the number of second upper surfaces 32a2 (second lower 
surfaces 32b2) of the polygonal mirror 32. Each of the scanning lines 
forming each second scanning pattern 9a is longer than each of the 
scanning lines forming each first scanning pattern 3a. 
The length of the optical path from the laser diode 4 to the first 
reflecting mirror 7 is adjusted such that the focal point of the laser 
beam forming the first scanning pattern 9a is positioned at in the space 
over the first window 36. The length of the optical path from the laser 
diode 4 to the second reflecting mirror 24 is adjusted such that the focal 
point of the laser beam forming the second scanning pattern 9a is 
positioned on or close to the surface of the second window 37. 
The laser beam reflected by the surface of a commodity brought into the 
space over the first window 36 returns into the housing through the first 
window 36, and then travels to the photodetector 8 via the first 
reflecting mirror 7, each of the first upper surfaces 32a1 of the 
polygonal mirror 32, each of the first lower surface 32b1 of the polygonal 
mirror 32 and the condense lens 25, as shown in FIGS. 12A and 12b. In 
addition, the laser beam reflected by the surface of the commodity brought 
into the space over the second window 37 returns into the housing through 
the second window 37, and travels to the photodetector 8 via the second 
reflecting mirror 24, each of the second upper surfaces 32a2 of the 
polygonal mirror 32, each of the second lower surfaces 32b2 and the 
condenser lens 25, as shown in FIGS. 14A and 14B. 
In the bar code reader according to the second embodiment, the operator 
generally brings a commodity into the space over the first window 36 so 
that a bar code formed on the commodity is scanned by the first scanning 
pattern 9a. On the other hand, if a bar code has a special form, such as a 
long sideways form and a form in which respective distances between bars 
are small, and thus a missreading occurs, a commodity on which the bar 
code having the special form is attached is brought close to or in contact 
with the surface of the second window 37. 
According to the second embodiment, even if a bar code to be scanned has a 
special form, the bar code can be scanned precisely by use of the second 
scanning pattern 9a in the same manner as in the first embodiment. 
In the above first and second embodiments, the surfaces of the second 
reflecting mirror 24 may be divided into segments. However, the number of 
segments of the second reflecting mirror 24 must be less than the number 
of segments of the first reflecting mirror so that each of the scanning 
lines of the second scanning pattern 9 (9a) is longer than each of the 
scanning line of the first scanning pattern 3 (3a). 
The present invention is not limited to the aforementioned embodiments, and 
variations and modifications may be made without departing from the scope 
of the claimed invention.