Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1998-10-19
2001-05-15
Le, Thien M. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S472010, C235S462400, C235S462430
Reexamination Certificate
active
06230976
ABSTRACT:
BACKGROUND
The field of the present invention relates to optical systems for data reading and particularly to a scanning system having improved resistance to shock and vibration.
Typically, a data reading device such as a bar code scanner illuminates a bar code and senses light reflected from the code to detect the bars and spaces of the code symbols and thereby derive the encoded data. In a common system, the scanner includes a housing and a scan module comprising a light source, one or more scanning mechanisms, a detector, and optics and signal processing circuitry.
A variety of scan modules and their scanning mechanisms are known as described in, for example, U.S. Pat. Nos. 5,475,206 and 5,629,510 or U.S. application Ser. No. 08/934,487, each of these disclosures hereby incorporated by reference. Such scanning mechanisms typically comprise rotating polygon mirror assemblies and dithering or oscillating mirror assemblies. Dithering assemblies typically comprise a cantilevered mirror and a drive means or dithering motor for moving the mirror.
FIG. 1
illustrates a dithering assembly
100
comprising a mirror/magnet assembly
110
, drive coil
106
, feedback coil
108
, bending member or flexure
112
, and mounting member
114
. The mounting member
114
is mounted to a suitable chassis (not shown). The mirror/magnet assembly comprises mirror
102
, mirror bracket
103
, drive magnet
104
, and feedback magnet
105
. The bracket
103
holds mirror
102
and is pivotally supported on the mounting member
114
via flexure
112
. Bending of flexure
112
results in rotation of the mirror/magnet assembly
110
about an axis substantially parallel to mirror
102
, perpendicular to the plane of FIG.
1
.
Due to the cantilevered ditherer configuration and the sensitive components used to construct the scanner, current scanners are relatively sensitive to shock and are often damaged before they would have worn out for other reasons. Handheld scanners are particularly subjected to shock and have been equipped with shock protection such as by mounting the scan module to the interior of the housing body via shock mounts as described in U.S. Pat. No. 5,475,206.
Other shock protection includes a pin-in-hole arrangement that typically comprises a moving pin associated with the cantilevered mirror, and a stationary hole associated with the support structure (e.g., the chassis). Since during dithering (rotating) operation, there is no lateral motion of the pin within the hole, the required clearance inside the stationary hole need only be sufficient to accommodate process and temperature variations.
While the pin-in-hole arrangement may protect the flexure from yielding during overflexure or buckling, its assembly is often difficult. Assembly can be made easier by increasing the diameter of the hole. However, a larger hole diameter affords less protection against higher shock levels when compared to the level of protection afforded by a smaller hole diameter. Furthermore, once the pin is properly positioned inside the hole, should the level of shock protection need to be changed, the hole diameter itself must be changed.
In an attempt to overcome some of the problems inherent with the pin-in-hole arrangement, dithering assemblies have been equipped with shock mounts. Mounting the flexure to the mounting member via shock mounts, as described in, for example, U.S. Application entitled “FLEXIBLE DITHER MOUNT WITH ROTATION,” Svetal et al., filed Sep. 3, 1998 with Express Mail Label No. EM351172541US, hereby incorporated by reference, advantageously permits the diameter of the stationary hole to be larger than the diameter would be without the shock mounts. However, this design may increase manufacturing costs as well as the overall size of the scanning mechanism. Having recognized these conditions, an improved scanning system resistant to shock and vibration is desired.
SUMMARY OF THE INVENTION
To these ends, the present invention is directed to a scan module and scanning mechanism including a dithering assembly that is compact, easy to assemble, and configured to protect the more delicate scanning components, such as flexures, from damage due to external mechanical shock. In a preferred construction, the dithering assembly includes a dither mount and a mirror mount, each mount having an arm adapted to matingly engage one another. In particular, the dither mount arm may include a socket configured to receive a boss of the mirror mount arm.
REFERENCES:
patent: 4175832 (1979-11-01), Umeki et al.
patent: 4660941 (1987-04-01), Hattori et al.
patent: 4691212 (1987-09-01), Solcz et al.
patent: 4708420 (1987-11-01), Liddiard
patent: 5170277 (1992-12-01), Bard et al.
patent: 5293265 (1994-03-01), Aleshin et al.
patent: 5475206 (1995-12-01), Reddersen et al.
patent: 5600120 (1997-02-01), Peng
patent: 5663550 (1997-09-01), Peng
patent: 5668655 (1997-09-01), Schwiezer et al.
patent: 5693929 (1997-12-01), Dvorkis et al.
Jensen James J.
Orlick Charles A.
Ruff David N.
Sautter Christopher F.
Felten Daniel S
Le Thien M.
Lyon & Lyon LLP
PSC Scanning Inc.
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