Modular handheld or fixed scanner

A bar code scanning system which can be operated in two scanning categories: hendheld and fixed. The system incorporates a second scanning element having a fixedly mounted mirror and a dithering mirror disposed in relation to a hand-held scanner which is removably positioned in a holder means.

BACKGROUND OF THE INVENTION 
1. Field Of The Invention 
The field of the present invention relates generally to bar code scanning 
devices. More particularly, the field of the present invention relates to 
a modular, handheld or fixed scanner for reading an optical bar code by 
means of a scanning laser beam. 
2. The Prior Art 
Conventional point of sale (POS) bar code label readers in use today are of 
two general categories, fixed and handheld. Fixed scanners are typically 
mounted in a counter top and are typically used in supermarkets where 
there is a well established flow of goods along a predetermined item path 
from one location to another. An example of such a conventional fixed 
scanner is described in U.S. Pat. No. 4,939,355 and in references cited 
therein. The scan lines produced by such a scanner are directed generally 
to the package along its path. In addition, the scan lines are directed at 
many angles to facilitate reading the bar code label at any orientation. 
This category has the advantage of freeing the checker's hands to move the 
item past the scanner. 
In the second category, the scanner is held in the hand of the checker or 
sales person. In this case, there may be no fixed flow of goods, but 
rather the labeled items may be located in different directions from the 
checker or sales person. For example, in many POS locations, a large 
counter is used and the goods may come from either end of the counter. In 
such applications, a handheld scanner is most useful because the scanner 
can be directed to the label wherever it appears. Such scanners are 
described in U.S. Pat. Nos. 4,760,248 and 4,825,057, for example. This 
type of scanner generally produces a single line scan pattern which is 
repeated several times a second. This scan line is generally horizontal 
but can be rotated and pointed by the operator to scan across all the bars 
of the bar code label. 
In some POS applications, a fixed scanner is required because the flow of 
goods along an item path is well defined. At other times, a handheld 
scanner is required because the labeled items may be coming from different 
directions. There is therefore a need for a scanner which can perform the 
functions of a fixed scanner and also the functions of a handheld scanner. 
Such a scanner which could be rapidly and conveniently converted from 
functioning as a fixed scanner to functioning as a handheld scanner would 
be very useful in POS applications which have widely different needs and 
differing item paths. 
It would also be extremely advantageous from a cost and efficiency 
perspective, if a single bar code scanner could be designed as a modular 
component of a scanning system. Such a scanning device, in a first module, 
would be employed for unrestricted, multidirectional handheld scanning of 
various items. The scanner could then be changed to a second configuration 
for accurate scanning from a fixed location with respect to a well defined 
item path. Ideally, the scanner should be freely and quickly 
interchangeable between modules without any down time for modification and 
without any adverse impact o scanning performance. 
SUMMARY OF THE INVENTION 
In order to achieve the foregoing and other objectives, a modular bar code 
scanning system is described. According to one aspect of the invention, 
the present scanner can be used for both scanning categories, that is for 
all fixed scanning of items along a well defined item path, as well as for 
handheld applications. 
In a first module, the present device comprises a handheld scanner which 
functions in a normal fashion. It is held by a sales person to freely scan 
items at a point of sale which are not confined to an item path. Such a 
scanner produces a focused beam typically forming a scan line which is 
optimum for its us as a handheld scanner. This device also includes a 
means for scanning the beam and means for collecting reflected light from 
a bar code label including means for decoding bar code information. 
In accordance with an aspect of this invention, when the handheld scanner 
is inserted into a second module, a fixed scanner is created. The second 
module includes a mechanical mounting arrangement which allows the 
handheld scanner to be easily and conveniently inserted to form a fixed 
scanner for accurately resolving the bar code labels of items moving on an 
item path. The second module may also include optics for reforming the 
scanning beam for optimally resolving, from a fixed position, a bar code 
label of items in the item path. Pattern mirrors and a motor driven mirror 
scan the laser beam in different directions to form a substantially 
omnidirectional pattern. Insertion of the handheld scanner into the second 
module can also activate a scanning means such as a motor a driven 
polygonal mirror or a piezoelectrically driven tilted mirror or a solenoid 
activated mirror for scanning from a fixed location, and, or deactivate 
the scanning motor within the handheld scanner. A low power telescope in 
the second module can make the beam smaller or larger as needed to produce 
a beam waist at a desired location. Similarly, a single negative or 
positive lens or mirror can be used to reposition the spot to an optimum 
location for resolving a bar code label. The reflected light from the 
label can be collected by optics within the second module and the 
information contained therein can then be decoded in accordance with well 
known techniques. Alternatively, the collection means and decoding means 
of the handheld scanner can. also be employed in the second module 
An object of the present invention is to reduce the cost and size of POS 
stations which require both a handheld scanning capability and a fixed 
scanning capability. In the preferred embodiment, the incremental cost of 
providing a fixed scanner includes the cost of the housing, connection 
hardware, mirrors and the mirror or scanning element. This represents a 
significant savings over the cost of a separate fixed scanner and a 
handheld scanner. The counter area of a POS location is used to display 
items for sale and is therefore considered very costly in terms of space. 
The reduced size of the combined fixed and handheld scanner of the present 
invention therefore makes valuable space available for sale purposes. 
Another advantage of the smaller size of the combined fixed and handheld 
scanner of the present invention is an increase of spatial freedom which 
improves the ergonomics of the POS station. 
The performance of the scanner according to the present invention in the 
fixed application can be enhanced by careful design of the individual 
components. For example, the spot size at the scan plane may be obtained 
by using a weak telescope to magnify the entire scan beam. The light from 
the label is scattered in a specular and diffuse reflection will be 
collected more efficiently through the telescope. Preferably, the pattern 
mirrors are coated for high reflectivity to avoid loss of optical power. 
The scanning of the beam can be done by combining the scanning of the 
handheld scanner with additional scanning by a mirror downstream of the 
handheld scanner. Alternatively, all the scanning can be accomplished by a 
rotating polygonal mirror. In the latter case, the scanning mechanism in 
the handheld scanner is deactivated when polygon scanning is activated.

DETAILED DESCRIPTION 
Referring now to FIG. 1, a generic handheld scanner 1 has a built-in 
scanning and light collection subsystem. The handheld scanner 1 includes a 
source of laser light and produces a focused beam which scans a locus of 
points forming scan line 2 for resolving a bar code label. Detected light 
returning from a bar code label being scanned is collected by optical 
collection means within the scanner and is electronically processed by 
circuits within the handheld scanner unit 1 in accordance with well known 
techniques. The processed signal containing the item information decoded 
by the processing circuitry is sent via a cable 6 to the next instrument 
for further processing or data handling. A switch 8 selectively activates 
the handheld scanner when it is in the hand of the user The handheld 
scanner 1 is used for scanning oversize items or items which are not 
confined to an item path, and comprises a first module of the present 
modular scanning system. 
Referring now to FIG. 2, a conventional POS station is shown with a scanner 
built into the counter top 10. The scanning beam 11 passes through the 
window 12 making a scan pattern 14 on a package 16 being scanned. The flow 
of goods is generally from right to left in FIG. 2. 
Referring now to FIG. 3, a preferred embodiment of the present invention 
comprises a modular scanning system wherein a handheld scanner 20 is 
mounted in a holder means 21. The holder means 21 includes means for 
positively capturing the handheld scanner unit 20 and for establishing a 
mechanical relationship between the handheld scanner unit 20 and holder 
means 21 The fastening of the handheld scanner 20 into the holder means 21 
also can automatically activate a switch (such as switch 8 as shown in 
FIG. 1) which turns on the handheld scanning unit 20 and activates the 
scanning laser beam 11 as shown. In this configuration, the handheld 
scanner functions in a second module as a fixed scanner producing a beam 
which is scanned in an omnidirectional pattern to provide an optimal 
scanning region for resolving bar code labels of items on a defined item 
path. 
According to one aspect of the present modular scanning system, in the 
second or fixed mode, separate scanning means are provided for scanning 
the beam from the handheld scanner in a locus of positions which define an 
ideal scanning plane for resolving the bar code labels of items moving 
along a predetermined item path. 
A mirror 24 is mounted on a cantilever beam 34 which is fastened through 
base member 22 to a wall or housing beneath counter top 10. The counter 
top 10 preferably defines an item path. The mirror 24 reflects the laser 
beam 11 and scans the line pattern produced by the handheld scanner 20 to 
sweep a volume in space. This is the scan volume in which the label will 
be read. When the handheld unit 20 is inserted in its holding means 21, 
the scanning beams 11 are directed to a set of fixed pattern mirrors 26 
located in the same housing beneath window 12. The pattern mirrors 26 
convert a single broad scan line into three or more lines, two of which 
can be nearly vertical. Advantageously, this scan pattern enables the 
scanning unit 20 in accordance with the present invention to read bar code 
labels of items moving on an item path, from a fixed position without the 
need for orientation of the items. 
FIG. 4 shows the scanning and optics of a preferred embodiment of a modular 
handheld scanner employed in a second module, that is, as a fixed scanner 
in accordance with the present invention. A large negative lens 32 is 
disposed for focusing the laser beam 33 projected from the scanner unit 
20. The large negative lens 32 combines with a positive lens 34 to allow 
the imaging of the spot to the desired location above the window 12 The 
mirror 26 directs the scanning beam 33 through the positive lens 34 and 
through window 12 to form an appropriate scan line. Preferably, the 
embodiment is able to produce at least one scan line at substantially 
right angles to other scan lines. The scan lines thus project upwardly 
through the mirror 12 to scan a locus of lines which define an idealized 
scanning region for resolving a bar code label. The mirror 26 provides a 
beam directing means for directing the beam 33 through the positive lens 
34. The positive lens 34 provides a means for forming a beam waist at a 
desired location wherein the beam 33 is sufficiently focused to resolve 
the bar code lines. 
Those skilled in the art will understand that the optical power delivered 
by the lenses 32 and 34 can be incorporated in the mirror surfaces such as 
mirrors 24 and 26. This greatly reduces the cost and complexity of the 
design. Other optical modifications using additional lenses and mirrors 
also may be incorporated in the design. 
In accordance with another aspect of the modular scanning system, a 
resonant scanning means is provided for efficiently scanning the beam from 
the handheld unit to produce a locus of scan lines defining an enlarged 
scan volume for scanning items moving along a predetermined item path. 
A first end of cantilever beam 35 is rigidly attached to the mirror 24. A 
second end of cantilever beam 35 attaches to a base 37 which is firmly 
held in a part of the housing. A coil 36 is disposed in proximity to the 
base 37 of cantilever beam 35. Leads, not shown, are provided for applying 
an alternating current to the coil 36 in accordance with well known 
techniques. The coil 36 is attracted and repelled by a permanent magnet 38 
depending on the direction of current flowing through the coil 36. One 
skilled in the mature art of magnetics will be able to devise other 
efficient means of exciting the mechanical system. 
In accordance with one aspect of the invention, the mirror 24 and 
cantilever beam 35 are a resonant mechanical system. That is, a small 
amount of alternating current at the resonant frequency of the system 
applied through the coil 36 is adequate to produce the required 
deflections of the cantilever beam. The deflections of resonant cantilever 
beam 35 are chosen so a to direct the laser beam 33 into a locus of lines 
defining an ideal scanning region. The mirror 24 cooperates with the 
pattern mirrors 26 to convert the beam 33 into three or more scan lines, 
two of which can be nearly vertical. As set forth above, this scan pattern 
enables bar code labels to be read without the need for orientation of the 
item. 
Since the mirror 24 and cantilever beam 35 are a resonant mechanical 
system, only a small amount of current at the resonant frequency of this 
system is required to produce the required deflections and thus the 
scanning of beam 33. 
The apparatus according to the present invention provides a modular 
scanning system which employs a single handheld laser unit for both 
handheld and fixed scanning applications. In a first module, a handheld 
scanner is provided for scanning items from any direction at a point of 
sale. In a second configuration, the same handheld scanner unit is simply 
and efficiently converted to a fixed scanner. The second module 
supplements and reconfigures the scanner line of the first module for 
efficient scanning with a fixed flow of goods. The modular scanner in a 
fixed application includes means for scanning the beam in a locus of lines 
which define an ideal scanning region for resolving the bar code labels of 
items moving on a predetermined item path. The present scanner in the 
fixed mode also includes improved optical means for focusing the beam 
waist at an optimal location for resolving bar code labels of items as 
they move along the item path. 
Accordingly, the present modular scanning system provides the advantages of 
both a handheld and fixed scanner at a cost only slightly greater than the 
cost of the handheld scanner. The present device is very efficient and 
inexpensive to manufacture due to the small number of parts required. The 
present modular system enables a handheld scanner to also function as a 
fixed scanner for scanning a predetermined flow of goods along an item 
path without any loss of resolution or scanning efficiency. Also, the 
present invention enables the same scanner unit to be instantly removed 
from its fixed position and to function as a handheld scanner to 
facilitate the reading of a bar code label of items positioned in any 
orientation at a point of sale location or to scan oversize items which 
can not move along a predetermined item path. The modular handheld or 
fixed scanner in accordance with present invention has extreme flexibility 
in comparison with conventional bar code scanners and is adaptable to a 
wide variety of applications. 
While the invention has been described in connection with what is presently 
considered to be the most practical and preferred embodiments, it is to be 
understood that the invention is not limited to the disclosed embodiment, 
but on the contrary, is intended to cover various modifications and 
equivalent arrangements included within the spirit and scope of the 
appended claims. For example, multiple resonant cantilever beams and 
mirror systems could be employed for scanning the laser beam of the 
modular scanning unit into multiple scanning planes, some being at right 
angles to others, in order to read any bar code label moved through the 
scanning region above the window. However, in such a structure the device 
still provides a modular scanner for application in either a hand held or 
fixed mode. Therefore, persons of ordinary skill in this field are to 
understand that all such equivalent structures are to be included within 
the scope of the following claims.