Automatic hand-supportable laser bar code symbol scanner and method of reading bar code symbols using the same

Claims

What is claimed is:

1. An automatic bar code symbol system having a selectable mode of operation in which a bar code symbol can be selectively read one or more times, said system comprising:

a hand-supportable housing having a light transmission aperture through which visible light can exit from and enter into said hand-supportable housing;

laser beam producing means, disposed in said hand-supportable housing, for producing a visible laser beam within said hand-supportable housing;

laser beam scanning means, disposed in said hand-supportable housing, for repeatedly scanning said visible laser beam across a scan field defined external to said hand-supportable housing and across a bar code symbol on an object located in at least a portion of said scan field;

laser light detecting means, disposed in said hand-supportable housing, for detecting the intensity of visible laser light reflected off said bar code symbol and passing through said light transmission aperture as said visible laser light reflected off said bar code symbol and passing through said light transmission aperture as said visible laser beam is repeatedly scanned across said bar code symbol present in said scan field, and for automatically producing scan data indicative of said detected intensity;

scan data processing means for processing produced scan data in order to detect and decode said bar code symbol when said bar code symbol is present in said scan field and automatically produce symbol character data in a form representative of said decoded bar code symbol and suitable for transmission to a symbol character data storage means,

said scan data processing means also including means for automatically processing produced scan data in order to determine that said decoded bar code symbol has become absent from said scan field, prior to said scan data processing means automatically processing produced scan data so as to detect and decode said decoded bar code symbol once again when said decoded bar code symbol is once again present in said scan field, and thereafter produce once again symbol character data in a form representative of said decoded bar code symbol and suitable for transmission to said symbol character data storage means;

control means for automatically controlling the operation of said laser beam producing means and said scan data processing means so that said bar code symbol is detected and decoded as said visible laser beam is repeatedly scanned across said bar code symbol present in said scan field, and after said scan data processing means detects the absence of said decoded bar code symbol from said scan field, said scan data in order to detect and decode said decoded bar code symbol once again when said decoded bar code symbol is once again present in said scan field, and thereafter automatically produces once again said symbol character representative of said decoded bar code symbol.

2. The system of claim 1, wherein said laser beam producing means comprises a laser diode.

3. The system of claim 1, wherein said bar code symbol has first and second envelope borders, and wherein said scan data processing means detects the presence of said bar code symbol in said scan field by processing produced scan data so as to detect the first and second envelope borders of said bar code symbol.

4. The system of claim 1, wherein said hand-supportable housing comprises a head portion and a handle portion, and wherein said laser beam producing means, said laser beam scanning means, and said laser detecting means are disposed in said head portion.

5. The system of claim 1, wherein said scan data processing means and said control means are disposed within said hand-supportable housing.

6. The system of claim 5, which further comprises a data output port for transmitting said symbol character data to said symbol character data storage means disposed external to said hand-supportable housing.

7. The system of claim 6, which further comprises a flexible connector cable physically associated with said data output port, for transmitting said bar code symbol data to said symbol character data storage means.

8. A method of selectively reading a bar code symbol one or more times using an automatic hand-supportable unit, comprising the sequence of steps:

(a) manually supporting said automatic hand-supportable unit adjacent an object bearing a bar code symbol so that said object is located within at least a portion of a scan field defined external to said automatic hand-supportable unit, and said automatic hand-supportable unit is disposed in a substantially non-contacting relationship with said object;

(b) producing a visible laser beam from a laser beam producing source disposed in said automatic hand-supportable unit, in repeatedly scanning said visible laser beam through a light transmission aperture in said automatic hand-supportable unit and across said bar code symbol while said bar code symbol is present in said scan field;

(c) automatically detecting at said automatic hand-supportable unit, the intensity of visible laser light reflected off said bar code symbol, and automatically producing scan data indicative of said detected intensity of visible laser light reflected off said bar code symbol;

(d) automatically processing scan data produced in step (c) in order to detect and decode said bar code symbol present in said scan field, and upon detecting and decoding said bar code symbol, automatically producing symbol character data in a form representative of said decoded bar code symbol and suitable for transmission to a symbol character data storage means operatively associated with said hand-supportable unit;

(e) moving said automatic hand-supportable unit relative to said object so as to cause said decoded bar code symbol to be absent from said scan field;

(f) producing said visible laser beam from said laser beam producing source, and repeatedly scanning said visible laser beam through said light transmission aperture and across said object while said bar code symbol is absent from said scan field;

(g) automatically detecting at said automatic hand-supportable unit, the intensity of visible laser light reflected off said object, and automatically producing scan data indicative of said detected intensity of visible laser light reflected off said object;

(h) automatically processing scan data produced in step (g) in order to detect the absence of said bar code symbol from said scan field;

(i) moving said automatic hand-supportable unit relative to said object so as to cause said decoded bar code symbol to be present once again in said scan field;

(j) projecting said visible laser beam from said laser beam producing source, and repeatedly scanning said visible laser beam through said light transmission aperture and across said bar code symbol present once again in said scan field;

(k) automatically detecting at said automatic hand-supportable unit, the intensity of visible laser light reflected off said decoded bar code symbol, and automatically producing scan data indicative of said detected intensity of visible laser light of the decoded bar code symbol;

(1) automatically processing scan data produced in step (k) in order to detect and decode once again said decoded bar code symbol, and upon detecting and decoding said decoded bar code symbol, automatically producing once again symbol character data in a form representative of said decoded bar code symbol and suitable for transmission to said symbol character data storage means.

9. The method of claim 8, where in steps (d), (h) and (l), said scan data is processed by a scan data processor disposed in said automatic hand-supportable unit.

10. The method of claim 8, where in steps (b), (f) and (j), said visible laser beam is produced by a laser diode disposed in said automatic hand-supportable unit.

11. The method of claim 8, wherein said bar code symbol has first and second envelope borders, and where in steps (d) and (h) the presence of said bar code symbol in said scan field is detected by processing produced scan data so as to detect the first and second envelope borders of said bar code symbol.

12. The method of claim 8, wherein said automatic hand-supportable unit comprises a housing having a head portion and a handle portion.

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 device having a control system which permits multiple modes of fully automated operation while conserving power and providing versatility in its method of 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 successful 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 scanning and decoding is to be cyclically initiated and terminated. The 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 operating a bar code symbol reading devices is use of automatic bar code symbol readers, which incorporate techniques 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" (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 powering and 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 further consumption of power.

U.S. Pat. No. 4,933,538 discloses a bar code symbol scanning system, which in the "object sensor mode" the scanner is triggerless and the constantly on laser beam normally emits at a narrow angle and low power. When an indicia pattern indicative of a bar code symbol has been detected, the laser beam will widen, the power of the beam will increase, and the beam will read the entire symbol. While this prior art scanning technique permits detection of bar code symbols within the scan field 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 prior art system nevertheless suffers from several significant shortcomings and drawbacks as well. In particular, this prior art system 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 battery 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 also suffer from other shortcomings and drawbacks. For example, unlike manually operated devices which rely on the user to activate a trigger, once for each bar code to be read, prior art triggerless (i.e., automatic) bar code symbol reading devices lack intelligence capabilities necessary to prevent undesired multiple reading of bar code symbols, particularly when the scanning beam is permitted to dwell on a bar code symbol for extended periods of time.

Further, prior art automatic bar code symbol reading devices have lacked control capabilities which permits diverse modes of programmable system-control operation, while preventing misreads and inadvertent multiple reads and ensuring conservation of power.

Thus, there is a great need in the code symbol reading art for a fully automatic code symbol reading device which overcomes the above shortcomings and drawbacks of prior art devices and techniques.

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 bar code symbols in accordance with user-selectable system-control operations.

A further object of the present invention is to provide such an automatic bar code symbol reading device incorporating a control system having a plurality of control centers, each of which can be assigned predetermined control functions that enable operation of particular device components in accordance with a user-selected system-control operation.

A further object of the present invention is to provide such an automatic bar