Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
2000-08-17
2003-11-04
St. Cyr, Daniel (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462360
Reexamination Certificate
active
06641043
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to optical scanning and reading equipment and, in particular, to systems for scanning a light beam across a target such as a bar code symbol.
II. Description of the Related Art
In a light beam scanner, a small spot of light is swept rapidly across a target such as a bar code symbol. After reflection from the target, a photoelectric converter such as a photo diode detects the reflected light and converts it to electronic signals representing features of the target. A bar code scanner is an important commercial application for beam scanners and is referred to herein as a typical example of a specific application for the present invention.
Various mechanisms exist in the prior art for sweeping (or scanning) a light beam across a target. One such prior art mechanism is shown in FIG.
9
. In the mechanism of
FIG. 9
, a coil
145
wound on bobbin
146
is attached to a steel mounting frame
148
. Steel rivets with heads
147
a
and
147
b
act as poles for coil
145
. A scan element
149
a
has a fixed end
149
b
mounted to mount
149
which in turn is fastened to a scanner chassis. The scan element
149
a
is a laminated structure made from flexible copper clad printed circuit stock. The laminated structure at the fixed end has copper layer
133
laminated to flexible plastic film
135
(e.g. polyamide film) also laminated to copper layer
136
which is in turn affixed to mounting bracket
149
. The flexible end
149
c
of the scan element includes copper layer
131
laminated to film layer
135
which in turn is laminated to copper layer
138
. Flexible film layer
135
holds the fixed end
149
b
and the flexible end
149
c
of the scan element together.
The scan element shown in
FIG. 9
includes an open area
137
that is formed by etching away a portion of copper between layer sections
138
and
136
. The area immediately above area
137
is also been formed by etching the copper away between copper layer sections
133
and
131
and back filling this area with an elastomer fill
132
. Mirror
134
is attached to copper layer
131
and magnet
140
is attached to copper layer
138
. Magnet
140
causes mirror
134
to dither in the direction of double arrow
139
when acted upon by current introduced into coil
145
. In the scan mechanism of
FIG. 9
, film layer
135
is a permanent part of the structure and is substantially thick (i.e., on the order of 0.030″) imparting stiffness to the flexural characteristics of the device. Since film layer
135
acts as a stiffening layer, this structure must be made relatively large and heavy in order to achieve slow scan rates on the order of 20 Hz. Furthermore, the stiffening effect of plastic layer
135
reduces the Q of the system and acts as a damper so that many oscillations cannot be maintained by the introduction of only a single current pulse in coil
145
. As described more fully below, one object of the present invention is to overcome this problem by providing a scan system wherein sufficient oscillations can be maintained by introduction of only a single current pulse in the drive coil or by application of some other momentary distortion force to the system.
Due to the relatively high rigidity of film layer
135
, coil
145
must be large with an iron core having pole faces to sufficiently act upon magnet
140
. Furthermore, mass manufacture of the device of
FIG. 9
requires a significant number of steps and components. As described more fully below, it is a further object of the present invention to provide a scan system which does not require such a large coil and which can be mass manufactured more easily and cost efficiently than the mechanism of FIG.
9
.
U.S. Pat. No. 4,593,186 entitled “Portable Laser Scanning System and Scanning Methods” discloses a portable laser scanning system for reading bar code symbols. The system includes means for generating and directing a laser beam, scanning means for scanning the laser beam across a symbol, sensor means for detecting light reflected from the symbol and generating a signal, signal processing means for processing the signal, decoding means for decoding the signal, manually actuatable trigger means for initiating each reading of the symbol, power supply means, and means for determining a successful decoding of each symbol and for non-manually terminating the reading of each symbol after a successful decode. Alternatively, the system includes means for determining that a symbol has not been successfully decoded and for non-manually terminating the reading of the symbol if the symbol has not been successfully decoded after a predetermined amount of time. Thus, in the system of the '186 patent, the deactuation of the scan system depends, at least in part, on a determination as to whether a symbol has been successfully decoded. In the present invention the determination as to whether the symbol has been successfully decoded or not is not necessary in order to properly and efficiently deactuate a scanning system. It is thus an object of the present invention to provide an improved and simpler sequence for actuating and deactuating the elements in a scan system which functions independently of any determination that the symbol has been successfully or unsuccessfully decoded. In doing so the benefits are significant, among these are: less battery energy needed, easier to use, fewer components needed, lower assembly costs, less space required to mount the scanner and quicker scan sequences.
The scan systems disclosed in the '186 patent also include motors that must be supplied power continuously during the entire scan sequence. To conserve power the motors are shut down in response to, for example, determinations that the symbol has or has not been successfully decoded. As will be explained more fully below, it is a further object of the present invention, to provide an actuation sequence that is more efficient than that described in the '186 patent, and which does not require continuous power to the scan element during the entire scan sequence.
SUMMARY OF THE INVENTION
The present invention is directed to a flexible scan element for scanning a light beam. The scan element includes a first leaf that is rigidly affixed to a substrate, a second leaf having a mirror affixed thereto, and a flexible hinge that couples the first leaf to the second leaf. The second leaf is moveable and pivots about an axis of the flexible hinge. The first leaf is coupled to the second leaf by the flexible hinge which is formed solely from an elastomer material. The first and second leaves are preferably formed from flat rigid metal, and optionally include bonding flanges that couple the leaves to the elastomeric material. The mirror is affixed on one side of the second leaf and a magnet is optionally affixed on the opposite side of the second leaf. The scan element optionally includes tabs for mounting the device to a flat substrate or circuit board, and, in one embodiment has a resonant frequency in the range of 20 Hz-100 Hz.
In accordance with a further aspect, the present invention is directed to a flexible scan element that includes a first leaf that is rigidly affixed to a substrate, a second leaf having a mirror affixed thereto, and a flexible hinge that couples a first end of the first leaf to a first end of the second leaf. The second leaf is moveable and pivots about an axis of the flexible hinge. In accordance with this further aspect, a gap separates the first end of the first rigid leaf from the first end of the second rigid leaf, and the gap has a minimum width that ranges from 3-20 mils. In a particularly preferred embodiment, the gap has a width of about 7 mils.
In accordance with a still further aspect, the present invention is directed to a flexible scan element that includes a first leaf that is rigidly affixed to a substrate, a second leaf having a mirror affixed thereto, and a flexible hinge that couples a first end of the first leaf to a first end of the second leaf. The second
Cyr Daniel St.
Kirschstein et al.
Symbol Technologies Inc.
LandOfFree
Articulated scan elements with elastomeric hinges, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Articulated scan elements with elastomeric hinges, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Articulated scan elements with elastomeric hinges, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3120822