Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
2000-05-09
2002-12-10
Le, Thien M. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462010
Reexamination Certificate
active
06491225
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to a bar code reader having an electronic stylus.
Optical readers, such as bar code readers, are now quite common. Typically, a bar code comprises a series of encoded symbols, and each symbol consists of a series of light and dark regions, typically in the form of rectangles. The widths of the dark regions, the bars, and/or the widths of the light spaces between the bars indicate the encoded information.
A bar code reader illuminates the code and senses light reflected from the code to detect the widths and spacings of the code symbols and derive the encoded data. Bar code reading type data input systems improve the efficiency and accuracy of data input for a wide variety of applications. The ease of data input in such systems facilitates more frequent and detailed data input, for example, to provide efficient inventories, tracking of work in progress, etc. To achieve these advantages, however, users or employees must be willing to consistently use the bar code readers. The readers therefore must be easy and convenient to operate.
A variety of scanning devices is known. One particularly advantageous type of reader is an optical scanner which scans a beam of light, such as a laser beam, across the symbols. Laser scanner systems and components of the type exemplified by U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,760,248—which are owned by the assignee of the instant invention and are incorporated by reference herein—have generally been designed to read indicia having parts of different light reflectivity, e.g., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working range or reading distance from a hand-held or stationary scanner.
FIG. 1
illustrates an example of a prior art bar code reader unit
10
implemented as a gun shaped device, having a pistol-grip type of handle
53
. A lightweight plastic housing
55
contains the laser light source
46
, the detector
58
, the optics and signal processing circuitry and the CPU
40
, as well as a power source or battery
62
. A light-transmissive window
56
in the front end of the housing
55
allows the outgoing light beam
51
to exit and the incoming reflected light
52
to enter. The user aims the reader
10
at a bar code symbol
70
from a position in which the reader
10
is spaced from the symbol, i.e., not touching the symbol or moving across the symbol.
As further depicted in
FIG. 1
, the reader
10
may include a suitable lens
57
(or multiple lens system) to focus the scanned beam into a scanning spot at an appropriate reference plane. A light source
46
, such as a semiconductor laser diode, introduces a light beam into the axis of the lens
57
, and the beam passes through a partially-silvered mirror
47
and other lenses or beam-shaping structures as needed. The beam is reflected from an oscillating mirror
59
which is coupled to a scanning motor
60
energized when the trigger
54
is pulled. The oscillation of the mirror
59
causes the reflected beam
51
to scan back and forth in a desired pattern.
A variety of mirror and motor configurations can be used to move the beam in a desired scanning pattern. For example, U.S. Pat. No. 4,251,798 discloses a rotating polygon having a planar mirror at each side, each mirror tracing a scan line across the symbol. U.S. Pat. No. 4,387,297 and U.S. Pat. No. 4,409,470 both employ a planar mirror which is repetitively and reciprocally driven in alternate circumferential directions about a drive shaft on which the mirror is mounted. U.S. Pat. No. 4,816,660 discloses a multi-mirror construction composed of a generally concave mirror portion and a generally planar mirror portion. The multi-mirror construction is repetitively reciprocally driven in alternate circumferential directions about a drive shaft on which the multi-mirror construction is mounted.
The light
52
reflected back by the symbol
70
passes back through the window
56
for application to the detector
58
. In the exemplary reader
10
shown in
FIG. 1
, the reflected light reflects off of mirror
59
and partially-silvered mirror
47
and impacts on the light sensitive detector
58
. The detector
58
produces an analog signal proportional to the intensity of the reflected light
52
.
A digitizer circuit mounted on board
61
processes the analog signal from detector
58
to produce a pulse signal where the widths and spacings between the pulses correspond to the widths of the bars and the spacings between the bars. The digitizer serves as an edge detector or wave shaper circuit, and the threshold value set by the digitizer determines what points of the analog signal represent bar edges. The pulse signal from the digitizer is applied to a decoder, typically a programmed microprocessor
40
which will have associated program memory and random access data memory. The microprocessor decoder
40
first determines the pulse widths and spacings of the signal from the digitizer. The decoder then analyzes the widths and spacings to find and decode a legitimate bar code message. This includes analysis to recognize legitimate characters and sequences, as defined by the appropriate code standard. This may also include an initial recognition of the particular standard the scanned symbol conforms to. This recognition of the standard is typically referred to as autodiscrimination.
To scan a symbol
70
, a user aims the bar code reader unit
10
and operates movable trigger switch
54
to activate the light beam
51
, the scanning motor
60
and the detector circuitry. If the scanning beam is visible, the operator can see the scan pattern on the surface on which the symbol appears and adjust aiming of the reader
10
accordingly. If the light produced by the source
46
is marginally visible, an aiming light may be included in the optical system. The aiming light, if needed, produces a visible light spot which may be fixed, or scanned just like the laser beam; the user employs this visible light to aim the reader unit at the symbol before pulling the trigger.
The reader
10
may also function as a portable computer terminal. If so, the bar code reader
10
would include a keyboard
48
and a display
49
, such as described in the previously noted U.S. Pat. No. 4,409,470.
In optical scanners of the type discussed above, the laser diode, the lens, the mirror and the means to oscillate the mirror all add size and weight to the handheld scanner. The photodetector and the associated processing circuitry also add size and weight. In applications involving protracted use, a large heavy handheld unit can produce fatigue. When use of the scanner produces fatigue or is in some other way inconvenient, the user is reluctant to operate the scanner. Any reluctance to consistently use the scanner defeats the data gathering purposes for which bar code systems are intended. Also, a need exists for small scanner units to fit into small compact devices, such as notebooks.
Thus, an ongoing objective of bar code reader development is to miniaturize the bar code reader as much as possible, and a need still exists to further reduce the size and weight of the scan unit and to provide a particularly convenient scanner system. The mass of the moving components should be as low as possible to minimize the power required to produce the scanning movement and to facilitate operation at high scanning speeds.
It is also desirable to modularize scanning components, so that a particular module can be used in a variety of different scanners. A need exists, however, to develop a particularly small, lightweight module which contains all necessary scanner components.
Smaller size scanning components tend to operate at higher scanning frequencies. In typical bar code scanning applications, however, the scanning frequency of the moving spot should be relatively low, typically 20 Hz or less. If the frequency increases, the speed of the spot as it passes over the indicia increases. The signals produced by the detector also increases in frequency, and conseq
Dvorkis Paul
Mulla Altaf
Swartz Jerome
Kirschstein et al.
Le Thien M.
Symbol Technologies Inc.
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