Mirrorless scanners with movable laser, optical and sensor components

Abstract: In bar code symbol scanning systems employing laser, optical and sensor components, a mirrorless scanner arrangement mounts one or more of these components on a drive for repetitive reciprocating movement either about an axis or in a plane to effect scanning.

Description: This invention generally relates to scanner systems for reading indicia of different light reflectivity such as bar code symbols and, more particularly, to so-called mirrorless scanner systems wherein system components, other than mirrors, are employed to effect sweeping or scanning of symbols to be read. Scanner systems and components of the type exemplified by US-A-4,251,798; US-A-4,360,798; US-A-4,369,361; US-A-4,387,297; US-A-4,593,186; US-A-4,496,831; US-A-4,409,470; US-A-4,460,120; US-A-4,607,156 AND US-A-4,673,803 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 or reading distance from a hand-held or stationary scanner. Typically, a light source such as a laser generates a light beam which is optically modified to form a beam spot of a certain size at the working distance and is directed by optical components along a light path toward a bar code symbol located in the vicinity of the working distance for reflection from the symbol. A photodetector having a field of view extending across and slightly past the symbol detects light of variable intensity reflected off the symbol and generates electrical signals indicative of the detected light. These electrical signals are decoded into data descriptive of the symbol. A scanning component is situated in the light path. The scanning component may either sweep the beam spot across the symbol and trace a scan line across and past the symbol, or scan the field of view of the photodetector, or do both. In any case, the scanner typically includes a moving mirror. For example, US-A-4,251,798 discloses a rotating polygon having a planar mirror at each side, each mirror tracing a scan line across the symbol. US-A-4,387,297 and US-A-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. No matter what the shape or orientation of the mirror, the known scanning components employed in laser scanning systems moved mirrors to perform the aforementioned sweeping and scanning actions. Moving other laser scanning system components was not thought to be practical. Thus, moving a gas laser tube was unthinkable, particularly in hand-held, compact system applications, due to the large size and the requisite large room necessary to accommodate a moving gas laser tube. Moving an optical lens was also not thought to be desirable, because optical alignment is critical in laser scanning systems. Hence, it was the mirror that was typically designated to effect the sweeping/scanning functions. However, in some laser scanning applications, mirror movements have not been found to be altogether desirable. In non-laser scanning systems of the type exemplified by US-A-4,578,571, a non-laser light emitting diode, an optical assembly, a photodetector, and electronic preamplifier/filter circuitry are all fixedly mounted on a common support that is connected to a cantilevered bimorph which is reciprocatingly driven to jointly move all the aforesaid components back and forth over a bar code symbol to be scanned. The large volume and heavy mass of all the commonly-mounted non-laser system components requires the expenditure of a great deal of power for the drive. This is not altogether practical in those cases, e.g. battery-powered operation, where power consumption is to be held to a minimum. Also, moving only one or more non-mirrored system components relative to another for conserving power was heretofore not considered desirable, because of the optical alignment problems described above. EP-A-0264956 discloses those features set out in the preamble of claim 1. According to the present invention a mirrorless scanner arrangement is characterised by the features set out in the characterising portion of claim 1. Advantageously, the drive means includes a motor having an elongated shaft, and operative for reciprocatingly turning the shaft about an axis which extends along the elongation of the shaft in alternate circumferential directions over arc lengths less than 360°, e.g. 10° to either side of a center position. Said at least one component is mounted on the shaft for joint turning movement therewith. The component mounted on the shaft may be the laser, e.g. a semiconductor laser diode, a focusing lens, an aperture stop, the combination of a focusing lens and aperture stop, or the entire combination of the diode, the lens and the aperture stop. Since the diode requires a power supply e.g. a 12-volt DC source, and since the electrical signal developed by the photodiode must be conveyed to signal processing circuitry, electrical coiled tensile wires are advantageously connected to the laser diode and the photodiode. The mirrorless scanner arrangement of this invention can be used to generate a single scan line over the symbol to be read, or can be used with other scanner components to generate a multi-line scan pattern over the symbol. In addition, the mirrorless scanner arrangement is very compact in size and light in weight, and can be mounted in modular manner in many different system configurations. For example, the arrangement can be mounted in hand-held housings having any convenient shape, e.g. a gun-shaped head having a barrel and a handle, or a box-like head, or a cylindrical-type head, or in desk-top housings, e.g. a workstation having scan-above, scan-down, or scan-sideways capabilities, or in stationary system installations, e.g. mounted at a production line or at a cash register. The compact size and lightweight characteristic renders the arrangement very versatile for multiple applications and uses. The power requirements for reciprocating the one or more components to be reciprocated is minimal. Advantageously, the arrangement is easily removable from the system in which it is installed. An arrangement requiring replacement is easily interchangeable with another. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, best will be understood from the following description of specific embodiments when read in connection with the accompanying drawings. FIG. 1A is a partly broken-away, partly sectioned side view of a hand-held light scanning system in which a mirrorless scanner arrangement (not in accordance with this invention) is housed; FIG. 1 is an end view of FIG. 1A; FIG. 2 is a front perspective view of the mirrorless scanner arrangement of FIG. 1A; [FIG. 3 has been deleted]; [FIG. 4 has been deleted]; FIG. 5 is a partly sectioned side view of a mirrorless scanner arrangement in accordance with a preferred embodiment of this invention; FIG. 6 is an enlarged view taken on line 6-6 of FIG. 5; FIG. 7 is a diagrammatic top plan view of the embodiment of FIG.5 depicting its operation at two end-limiting positions. [FIG. 8 has been deleted]; [FIG. 9 has been deleted] and; FIG. 10 is a side view of a gooseneck-type scanning system workstation for use with the preferred mirrorless scanner arrangements of this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, reference numeral 10 in FIGs. 1A and 1B generally identifies an arrangement in a scanner system of the type generally described in the above identified patents and patent applications, for reading symbols, particularly UPC bar code symbols. As used in this specification and the following claims, the term "symbol" is intended to be broadly construed and to cover not only symbol patterns composed of alternating bars and spaces, but also other patterns, as well as alpha-numeric characters and, in short, any indicia having portions of different light reflectivity. The arrangement 10 comprises a hand-held housing 12 having a base 14 which subdivides the interior of the housing into an upper half 16 and a lower half 18. A lightweight, high-speed, miniature scanning motor 20 similar to that described in U.S. Pat. No. 4,496,831 is mounted on base 14. The motor 20 has an output shaft 22 which is repetitively driven in alternate circumferential directions about an axis along which the shaft extends over arc lengths less than 360° in each direction. Structural, functional and operational aspects of the motor 20 and of control circuitry 24 for the motor are set forth in detail in U.S. Pat. No. 4,496,831 and, hence, for the sake of brevity, will not be repeated herein. One difference between the motor 20 of this invention and the motor of U.S. Pat. No. 4,496,831 is the superstructure that is mounted on the output shaft 22. Instead of a planar mirror as taught by said patent, the invention proposes, in FIG. 1A, mounting a generally U-shaped support 26 at the end of the shaft 22, and mounting a laser/optics subassembly 28 on the support 26. The subassembly 28 and the support 26 are jointly oscillated and turned with the shaft 22. The subassembly 28 includes an elongated hollow tube 30, a laser diode 32 fixedly mounted at one axial end region of the tube 30, a lens barrel 34 mounted at the opposite axial end region of the tube 30, and a focusing lens mounted within the barrel. The focusing lens is preferably a plano-convex lens, but may be spherical, convex or cylindrical as well. The barrel 34 has an end wall formed with an aperture stop wich is an opening extending through the end wall. The barrel 34 is mounted for longitudinal telescoping movement within and along the tube 30. The lens is situated adjacent the end wall of the barrel and is mounted for joint movement with the barrel. The position of the barrel and, in turn, of the lens relative to the diode is fixed typically by gluing or clamping, at the assembly site so that a known distance between the lens and the aperture stop, on the one hand, and between the lens, the aperture stop and the diode, on the other hand, is obtained. A coil spring is located within and extends along the barrel and tube, and has one coil end bearing against the diode, and another coil end bearing against a planar side of the lens. The spring urges the lens against the end wall having the aperture stop, thereby fixedly locating the lens relative to the aperture stop. The subassembly 28, per se, forms no part of this invention and, in fact, is described and claimed in pending U.S. Appl. Ser. No. 706,502 to which reference can be had for further structural, functional and operational aspects of the subassembly. It is sufficient for this invention to understand that the sub-assembly 28 includes a solid-state laser diode 32 operative for propagating and generating an incident laser beam, either in the invisible or visible light range, and the combination of a focusing lens and an aperture stop together operative for focusing the laser beam to have a beam cross-section or beam spot of a certain waist size within a range of working distances relative to the housing 12. The focused beam passes through the aperture stop and through a scan window 40 on the housing in the vicinity of a reference plane located exteriorly of the housing within the range of working distances along an outgoing optical path. During the alternate, repetitive oscillations of the shaft 22, the support 26 and the subassembly 28 likewise participate in this oscillatory movement, thereby causing the beam spot to be swept in an arc whose center of curvature is located at the diode across the symbol at the reference plane and to trace a curved scan line thereat. Hence, no longer is a mirror used to effect sweeping of a beam spot across a symbol, but, instead, other scanner components are moved and, in the embodiment of FIG. 1A, these other components comprise the laser diode 32 and the optical components which are jointly turned as a unitary structure about an axis parallel to the reference plane. A portion of the light reflected off the symbol passes along a return path through a second window 42 on the housing in the direction of arrow B to a photodetector 44 for detecting the variable intensity of the returning portion of the reflected laser light over a field of view; and for generating an electrical analog signal indicative of the detected variable light intensity. In the FIG. 1A embodiment, the photodetector 44 is stationarily mounted on the printed circuit board 46. Printed circuit boards 48 and 50 at either side of board 46 contain signal processing circuitry 52 and microprocessor control circuitry 53 for converting the analog electrical signal to a digital signal, and for processing the digital signal to data descriptive of the symbol being read. Details of the signal processing and microprocessor control circuitry can be had by reference to the above-identified patents and applications. A two-part multi-wire plug-in cable connector 54 has one part electrically connected to the signal processing and microprocessor control circuitry and another part electrically connected to a flexible multi-wire cable 54' connected to a display 55 and a keyboard 56. A rechargeable battery pack 58 supplies power to the laser diode and the electrical circuitry in the housing. By moving only the laser diode and the optical component relative to the stationary photodetector, power from the battery pack is conserved. Means for initiating reading may advantageously include a trigger 60 mounted on the housing 12. The trigger extends in part outwardly of the housing to be manually actuated by a user who is holding the housing 12 in his hand. The trigger is operatively connected through trigger switch 62 and actuates the laser diode 32, the motor 20, the photodetector 44, the signal processing circuitry 52 and the control circuitry 53 to initiate a reading of the symbol. The trigger is actuated once for each symbol to be read, each symbol in its respective turn. Once the control circuitry determines that the symbol has been successfully decoded, the control circuitry terminates the reading of the symbol and deactuates the previously actuated components in the housing and readies the system for the next symbol. FIG. 2 illustrates the various electrical, mechanical and optical components assembled as a modular unit prior to mounting in the upper half 16 of the housing 12 of FIGs. 1A, 1B.The electrical circuitry on the printed circuit boards 46, 48, 50, as well as on base 14, has been omitted from FIG. 2 for the sake of clarity. Turning now to the embodiment of FIGS. 5-7, like reference numerals again identify like parts. The oscillating motor 20, once again, has an output shaft 22 on which a support 80 is mounted. Rather than being U-shaped like support 26, support 80 is L-shaped and has an upright leg 82. A laser/optics subassembly 28 is mounted on leg 82. A photodetector 44 is stationarily mounted on printed circuit board 46. Coiled tensile wire group 68 interconnects the diode 32 and electrical circuitry on board 46. Collecting lens 72 is mounted on leg 82 in a coaxially surrounding relationship with subassembly 28. The lens 72 and the sub-assembly 28 turns as a unit in either direction of double-headed arrow 76, whereas photodetector 44 is stationary. As schematically shown in FIG. 7, an incident light beam emitted from subassembly 28 is directed in one end-limiting position along optical axis 84 to impinge on a symbol located at the reference plane 78, whereupon a portion of the reflected light, as represented by light rays 86, 88, is incident on collecting lens 72 and focused at one end 90 of an elongated slot-like inlet 92 of the photodetector 44, best shown in FIG. 6. At an opposite end-limited position, shown in phantom lines in FIG. 7, the collected portion of reflected light is focused at an opposite end 94 of the inlet 92. Between end-limiting portions, the collected, focused light travels lengthwise along the inlet 92. FIG 10 shows a desk-top workstation wherein a housing 121 generally having the same shape as the upper half of housing 12 in FIG. 1A is mounted above a base 123 situated on a generally horizontal support surface such as a tabletop 125. A gooseneck-type semi-rigid, bendable, conduit 127 interconnects the housing 121 with the base 123 and enables the housing to be manually bendably positioned in any desired orientation relative to the base and to be maintained in the desired orientation. The light beam emitted from the housing can thus be positioned at any desired angle relative to the symbol to be read. Advantageously, the base 123 is hollow and contains signal processing circuitry which is connected by electrical wires running through the conduit 127 to the mirror scanning arrangement contained in the housing 121. Instead of the base, the end of the conduit remote from the housing 121 could be attached to a cash register, analogous point-of-sale apparatus, or a fixed mount, e.g. on a production line.

Claims: A scanner arrangement comprising: (a) a light source component (32) for emitting a light beam; (b) an optical component (34) for optically modifying and directing the light beam along an optical path (74) toward an indicia; (c) a photodetector component (44) having a field of view and operative for detecting at least a portion of light of variable intensity reflected off the indicia, and for generating an electrical signal indicative of the detected light intensity, and (d) a collection component (72) for collecting and directing the reflected light portion to the photodetector component (44); the arrangement being characterised in that : (A) the photodetector component (44) is stationary; (B) mounting means are provided for mounting the light source component (32), the optical component (34) and the collection component (72) for repetitive, reciprocating movement relative to the stationary photodetector component (44), and (C) drive means (2) are provided for respectively, reciprocatingly moving the mounting means to scan the light beam and the field of view. An arrangement as claimed in claim 1, wherein the drive means includes a motor (20) having an elongated shaft (22), and operative for reciprocatingly turning the shaft about an axis which extends along the length of the shaft in alternate circumferential directions over arc lengths less than 360°: and wherein the light source and optical components are mounted on the shaft (22) for joint turning movement therewith about the axis. An arrangement as claimed in claim 2, wherein the light source component is a semiconductor laser diode (32); and wherein the optical component includes a focusing lens and an aperture stop. An arrangement as claimed in claim 2 or claim 3, wherein the mounting means includes a support (82) for holding the diode (32), the lens and the aperture stop at a spacing from a power supply, and tensile wires (68) spanning the spacing between the power supply and the diode (32). An arrangement as claimed in claim 3, wherein the photodetector component (44) has an elongated input; and wherein the collection component is a collection lens (72) mounted on the shaft (22), and operative for collecting and directing the reflected light portion to and along the input of the photodetector component (44). An arrangement as claimed in claim 4, wherein the tensile wires (68) are connected to joints which are positioned in the immediate vicinity of the axis of the shaft (22). An arrangement as claimed in claim 1, in which the light beam and the field of view is scanned in a plane which is perpendicular to the optical path (74). An arrangement as claimed in claim 7, arranged to generate a single scan line for each reciprocal movement; and further comprising means for generating a scan pattern comprised of multiple scan lines over the indicia. An arrangement as claimed in claim 1, wherein the mounting means, photodector collection and optical components and the drive means constitute a compact module mounted within a housing (12). An arrangement as claimed in claim 9, wherein the housing (12) is a hand-held head having manually actuatable trigger means (60) operative for initiating reading of the indicia. An arrangement as claimed in claim 9, wherein the housing is a desk-top workstation having an overhead head (121), a base (123) and a semi-rigid, bendable conduit (127) between the head and the base, the conduit being orientable to position the head in a desired orientation relative to the base. An arrangement as claimed in claim 9, wherein the compact module includes an electrical connector for detachably interconnecting the module to other components.

Inventors: BARKAN EDWARD, KRICHEVER MARK, METLITSKY BORIS, SHEPARD HOWARD, SWARTZ JEROME, BARKAN, EDWARD, KRICHEVER, MARK, METLITSKY, BORIS, SHEPARD, HOWARD, SWARTZ, JEROME
Applicants: SYMBOL TECHNOLOGIES INC, SYMBOL TECHNOLOGIES, INC.
Application year: 1989
Main classification: G06K7
IPC codes: G06K7