1. Field of the Invention
The present invention relates generally to laser scanning systems, and more particularly to countertop bar code scanners that are equipped with adjustable mounting mechanisms and adapted to operate in an automatic “hands-free” mode of operation.
2. Description of Background Art
Optical scanners of various types have been developed for scanning and decoding bar code symbols. These scanners adapt readily to some operational environments, but present shortcomings when used in other situations. For example, consider system applications involving point-of-sale (POS) terminals in retail stores and supermarkets, inventory and document tracking, and diverse data control applications. Retail point-of-sale counters are prime sales areas Display designs and product offerings may change on a regular basis. Inventory and document tracking involves scanning a number of items or documents of widely varying shapes and sizes. Diverse data control applications may involve managing data flow on a factory assembly line where a variety of components and processes must be tracked. These applications demand a bar code scanner that presents some degree of mechanical flexibility for use in any of a wide range of operational environments.
Many existing bar code scanner designs are inadequately equipped to deal with the mechanical strains and stresses of day-to-day use. In many point-of-sale and factory environments, scanners are dropped, banged, and bumped. Delicate optical components may be damaged or misaligned, causing the performance of the scanner to degrade over time. Unfortunately, virtually all existing scanners are fabricated of high-impact polystyrene plastic, which provides only limited protection against mechanical shocks and bumps.
In addition to lacking mechanical ruggedness, bar code scanners suffer from other deficiencies. Existing scanners generally fall into one of two general categories: hand-held or stationary. The first category includes manually-actuated trigger-operated scanners, as well as automatically actuated hand-held scanners which do not utilize a triggering mechanism. The user positions the hand-held laser scanner at a specified distance from the object bearing the bar code. In the case of an automatically actuated scanner, the presence of the object is automatically detected, the presence of a bar code symbol on the object is detected, and thereafter the bar code symbols automatically read. In the case of trigger-operated scanners, the user positions the scanner at the specified distance from an object bearing a bar code symbol, manually activates the scanner to initiate reading and then moves the scanner over other objects bearing symbols to be read. Prior art trigger-operated bar code readers are disclosed in U.S. Pat. Nos. 4,387,297 to Swartz; U.S. Pat. No. 4,575,625 to Knowles; U.S. Pat. No. 4,845,349 to Cherry; U.S. Pat. No. 4,825,057 to Swartz, et al.; U.S. Pat. No. 4,903,848 to Knowles; U.S. Pat. No. 5,107,100 to Shepard, et al.; U.S. Pat. No. 5,080,456 to Katz, et al.; and U.S. Pat. No. 5,047,617 to Shepard, et al. Automatic laser-based bar code symbol reading systems are disclosed in U.S. Pat. No. 4,639,606 to Boles, et al., and U.S. Pat. No. 4,933,538 to Heiman, et al.
Several hand-held scanners have been developed to provide “omnidirectional” scanning, so as to permit reading of a bar code irrespective of its specific orientation within the scanning pattern. Examples of such systems include the NCR 7890 presentation scanner from the NCR Corporation and the LS9100 omnidirectional laser scanner from Symbol Technologies, Inc. Although these systems provide both hands-free as well as hands-on modes of operation, each of these systems suffers from a number of shortcomings. In particular, the spatial extent of the scan pattern produced from these scanners frequently results in the inadvertent scanning of code symbols on products placed near the scanner during its hands-free mode of operation. On the the other hand, in the hands-on mode of operation, it is virtually impossible to use these scanners to read bar code symbol menus provided in diverse application environments. In each of these scanner designs, the scanner is tethered to its base unit by a power/signal cord, and the user is required to handle the scanner housing in an awkward manner in the hands-on mode of operation, resulting in strain and fatigue and thus a decrease in productivity. In addition, the control structure provided in each of these hand-held projection scanners operates the scanner components in a manner which involves inefficient consumption of electrical power, and prevents diverse modes of automatic code symbol reading which would be desired in many portable scanning environments.
Hand-held scanners are not convenient to use in assembly-line applications where the user processes bar coded objects over an extended period of time, or where the user requires the use of both hands in order to manipulate objects. In other applications, hand-held scanners are difficult to manipulate while simultaneously moving objects or performing other tasks at a point-of-sale terminal. Stationary scanners, on the other hand, provide a degree of flexibility in many applications by allowing the user to manipulate bar coded objects with both hands. However, by their nature, stationary laser scanners render scanning large, heavy objects a difficult task, as such objects must be manually moved into or through the laser scan field.
One type of stationary scanner is frequently mounted within a checkout counter of a supermarket or other retail point-of-sale environment. Such “in-counter” or “presentation” scanners could also be employed in conjunction with conveyors at a factory assembly line. These scanning systems include a scanning window or aperture at the top of the scanner housing through which a scanning pattern is projected. The scanning pattern is typically provided in the form of a plurality of multi-directional scanning lines. When an item bearing a bar code is brought into the field of the scan pattern so that at least one of the scanning lines completely traverses the bar code, light is reflected from the bar code and received back through the window.
Stationary in-counter and presentation scanners use a variety of optical configurations to develop omnidirectional scanning patterns. These omnidirectional patterns are intended to ensure that at least one scanning line will cross a bar code symbol to be read, irrespective of the bar code's orientation within the scanning pattern. Examples of omnidirectional scanning patterns include comb patterns, orthogonal patterns, interlaced patterns, star-like patterns, lissajous patterns, and the like. While such scanners may be suitable for certain applications, the physical configuration of the optical components necessary to produce such complex omnidirectional patterns has resulted in scanner housings which are quite large and bulky. Moreover, the window of a counter-top or presentation scanner generally faces in a single, fixed direction. To change the direction of the scanning window and, thus, the orientation of the scanning pattern, it is necessary to relocate the entire housing. In many applications, this is inconvenient, especially when there is limited counter space.
One example of a stationary scanner, disclosed in U.S. Pat. No. 4,713,532, produces a scanning pattern having three groups of intersecting lines. These line groups form a large “sweet spot” which permits substantially omnidirectional reading of bar codes. The '532 scanner has a compact housing with a relatively small footprint, and is mountable on or in a counter. Depending upon the orientation of the window, the scanning pattern may be projected horizontally, vertically, or at an angle. An example of a scanner constructed in accordance with the '532 patent is the MS260 scanner, available from Metrologic Instruments of Blackwood, N.J. However, once the scanner was mounted in a given orientation, it was fixed and could not be easily moved.
Another example of a stationary scanner is disclosed in U.S. Pat. No. 5,216,231. This scanner is mountable on an adjustable base positioned above a counter. The base is constructed to permit the scanner housing to be adjusted in any of a variety of directions so that the scanning pattern will be projected at a desired orientation with respect to the counter. However, the base must be permanently secured to the countertop, which prevents the scanner from being lifted by hand to scan large or bulky items which do not fit on the countertop.
An attempt to combine the advantages of a hand-held scanner and a stationary scanner, U.S. Pat. No. 5,767,501 describes a hand-held scanner mounted in the head of a hand-supportable housing. The housing can also be supported in a separate base for hands-free presentation or countertop scanning. The base unit is mountable to a counter, and is equipped with a pivoting receptacle. The pivoting receptacle permits the scanning window and, hence, the scanning pattern, to be adjustable about a horizontal axis. Unfortunately, the user must return the hand-supportable housing to the base unit after each scan, requiring a realignment of the handle and handle receiving portions. This realignment process becomes tedious and annoying with repeated use. Moreover, the base unit is large and cumbersome for use in many point-of-sale environments.
Another attempt to combine the advantages of a hand-held scanner and a stationary scanner, U.S. Pat. No. 4,766,297 discloses a bar code scanning system which can be used in either a hands-on or hands-free mode of operation. The scanning system includes a portable hand-held laser scanning device for generating electrical signals corresponding to a scanned bar code symbol. In the hands-on mode of operation, a trigger is manually actuated each time the scanner operator wishes to read a bar code symbol on an object. The system also includes a fixture having a head portion for receiving and supporting the hand-held scanner, and a base portion above which the head portion is supported at a predetermined distance. In the hands-free mode of operation, the scanner is supported by the fixture head portion above the fixture base portion in order to allow objects bearing bar code symbols to pass between the head and base portions. In order to detect the presence of an object between the head and base portions, the fixture also includes an object sensor operably coupled to the scanner. When the object sensor senses an object between the head portion and the base portion, the sensor automatically causes the scanner, while supported in the fixture, to read the bar code symbol on the detected object.
Whereas bar code symbol scanning systems of the type disclosed in U.S. Pat. No. 4,776,297 permit reading of printed bar code information using either a portable (hands-on), or stationary (hands-free) mode of operation, such systems suffers from several significant drawbacks. For example, assume that it is desired to scan a large, heavy object such as an 80-lb. bag of concrete. The scanner operator could use the scanner in the hands-on mode of operation, but they would need to manually actuate a trigger each time the bar code symbol is to be read. If the scanner operator needs to move the bag into position, this is a two-handed job in itself, and the task of manipulating a trigger on the scanner during this positioning process is cumbersome and tedious at best. On the other hand, in the hands-free mode of operation, the heavy bag must be passed between the head and base portions of the fixture. If the bag will not fit between the head and the base portions, then one must resort to triggered operation.
Another scanning configuration is disclosed in U.S. Pat. No. 5,479,002. A scan head is adjustably mounted in a ball-and-socket joint on a scan module or housing. The scan head is movable about three mutually orthogonal axes, so as to allow the operator to steer the light beam emitted from the head. However, the '002 patent does not disclose or suggest any technique for combining the scan head and lower housing into a single package that is conveniently hand-held, but that can also be used as a free-standing scanner. Moreover, the design of the '002 housing is directed to a single-line scanning pattern and would not lend itself to production of an omnidirectional scanning pattern.
Additional attempts to produce omnidirectional scanners having adjustable housings or bases include the Model LS9100 Scanner, available from Symbol Technologies, and the Duet Scanner, available from PSC. Unfortunately, both of these scanners require the user to remove the hand-held scanner from a stand for hand-supported scanning.
Thus, there is a great need in the bar code symbol reading art for a bar code symbol reading system which overcomes the above described shortcomings and drawbacks of prior art devices and techniques, while providing greater versatility in its use. A need remains for a scanner configuration that is adjustable about one or more axes with respect to the base, but that does not entail the inconvenience of a separate scanner and stand. This configuration would permit omnidirectional bar code scanning from a hands-free standing position on a countertop or work surface, as well as from a hand-supported position for scanning large, heavy, or bulky items without requiring the scanner operator to repeatedly remove and/or replace the scanner in its stand.