Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1999-03-22
2002-07-02
Le, Thien M. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462010
Reexamination Certificate
active
06412700
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to automatic code symbol reading (i.e. recognition) systems, and more particularly to an automatic code symbol reading system which permits fully automated operation while providing a high degree of simplicity and versatility in its use.
2. Brief Description of the Prior Art
Hitherto, a number of techniques have been proposed for reading bar code symbols using hand-held devices. Despite variety amongst prior art bar code symbol reading devices, the various techniques incorporated into prior art devices can be classified into two principally distinct classes, namely, manually operated or triggered bar code symbol reading, and automatic bar code symbol reading.
Representative of prior art manually operated bar code symbol reading devices are U.S. Pat. No. 4,387,297 to Swartz, et al., U.S. Pat. No. 4,575,625 to Knowles, and U.S. Pat. No. 4,845,349 to Cherry. While such prior art devices are capable of bar code symbol reading, they nevertheless suffer from several significant shortcomings and drawbacks. In particular, the user is required to manually pull a trigger or push a button each time symbol reading (i.e. scanning and) decoding is to be cyclically initiated and terminated. This requirement is most fatiguing on the user when large numbers of bar code symbols are to be read. Also, in certain symbol reading applications, such as warehouse inventory, pulling the trigger to initiate scanning of bar code symbols may be extremely difficult for the user due to the physical location of the objects bearing the bar code symbols.
An alternative to manually operated bar code symbol reading devices is automatic bar code symbol readers, which incorporate technique for automatically initiating and terminating scanning and decoding operations. Representative of prior art automatic bar code symbol devices are U.S. Pat. No. 4,639,606 to Boles, et al. and U.S. Pat. No. 4,933,538 to Heiman, et al. While capable of automatically initiating scanning of bar code symbols, such prior art devices and incorporated techniques nevertheless also suffer from significant shortcomings and drawbacks.
In particular, U.S. Pat. No. 4,639,606 to Boles, et al. discloses laser emission control circuitry for use in implementing a hand-held triggerless bar code scanner. The laser is operated in a pulsed “find paper” mode until a reflected signal is obtained, indicating the presence of an object (e.g., paper) in the search field. Thereupon, the circuitry is changed to a “search mode” in which the power of the laser is increased to above the safety limits for a period of time, and the return signal is monitored for signal transitions corresponding to the black bars of the code. On detection of the first black bar, the circuitry is changed to an “in-code” (i.e., decode) mode as long as successive symbols are received within a given period of time. If the decode mode terminates within a predetermined time interval (e.g., one second after the beginning of the search mode), then the search mode is re-entered, otherwise the decode mode will change to find paper mode.
While the triggerless bar code symbol reader proposed in U.S. Pat. No. 4,639,606 possesses three modes of operation, this prior art bar code symbol reader nevertheless suffers from several significant shortcomings and drawbacks. In particular, this prior art bar code symbol reader requires continuous use of a pulsed laser beam to determine the presence of an object within the scan field, which, in hand-held portable battery power devices, undesirably drains limited power reserves, especially in extended time duration bar code reading applications. Also, this prior art device, not knowing whether a bar code symbol is actually present in the scan field, requires commencement of decode processing upon detection of the first black bar. Undesirably, this typically necessitates initializing a programmable device, such as a microprocessor, for decoding scan data that may likely contain no bar code symbol at all. Consequently, this characteristic of such prior art bar code symbol reading devices results in decreased responsiveness and versatility.
U.S. Pat. No. 4,933,538 discloses a bar code symbol reading system which, in the “object sensor mode”, is triggerless and constantly emits a laser beam at a narrow angle and low power. When an indicia pattern indicative of a bar code symbol has been detected, the laser beam is widened and its power increased, for reading the entire symbol. While this prior art bar code reading system permits detection of bar code symbols within the scan filed in order that the power of the laser beam may be automatically increased to a higher level for collecting scan data for use in decoding operations, this system also suffers from several significant shortcomings and drawbacks. In particular, it requires continuous use of laser emission to determine the presence of both objects and bar code symbols within the scan field, which necessarily results in drain of limited power reserves in portable batter power applications. In addition, the extensive use of a laser beam to perform object and bar code symbol detection functions implicates necessity for laser emission control measures.
In general, prior art automatic bar code symbol reading devices of the type described above, suffer from other shortcomings and drawbacks. For example, unlike manually operated devices which use a trigger to activate trigger bar code symbol reading, pulled once for each bar code to be read, prior art automatic bar code symbol reading devices lack intelligence capabilities necessary to prevent undesired multiple reading of a bar code symbol, particularly when the scanning beam is permitted to dwell on a bar code symbol for extended period of time.
Further, prior art automatic bar code symbol reading devices lack system control capabilities which permit diverse modes of operation and automatic reading of a plurality of consecutively different bar code symbols, while preventing misreads and inadvertent multiple reads of the same bar code symbol.
Thus, there is a great need in the code symbol reading art for a fully automatic hand-holdable code symbol reading device which overcomes the above shortcomings and drawbacks of prior art devices and techniques.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a fully automatic hand-holdable bar code symbol reading device capable of automatically reading one or more bar code symbols in a consecutive manner without the above-described shortcomings and drawbacks of prior art devices.
Another object of the present invention is to provide such an automatic bar code symbol reading device which is capable of detecting an object bearing a bar code symbol in an object detection field using object sensing energy, and in response thereto, scanning a light beam across a scan field in order to detect the presence of a bar code symbol, and only thereafter proceed to read the detected bar code symbol.
A further object is to provide such an automatic bar code symbol reading device, in which the object detection field spatially encompasses at least a portion of the scan field along the operative scanning range of the device.
A further object of the present invention is to provide an automatic hand-holdable bar code symbol reading device which is capable of collecting and detecting reflected IR object sensing energy and laser return light using common collection optics and signal processing circuitry.
Another object of the present invention is to provide a hand-holdable bar code symbol reading device which is capable of distinguishing between a bar code symbol and a regular pattern of light and dark areas such as that formed by printed characters, and to only enable bar code symbol reading operations upon the detection of a bar code symbol in the scan field of the device.
An even further object of the present invention is to provide an automatic bar code symbol reading device which prevents
Blake Robert
Knowles Carl H.
Rockstein George B.
Wilz David M.
Le Thien M.
Metrologic Instruments Inc.
Morgan & Lewis & Bockius, LLP
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