Bar code symbol reading system employing electronically-controlled raster-type laser scanner for reading bar code symbols during hands-on and hands-free modes of operation

A system for producing a raster-type scanning pattern for scanning 2-D bar code symbols, said system comprising:

• a housing;
• a light source disposed in said housing, for producing a light beam having cross-sectional characteristics suitable for scanning a 2-D bar code symbol;
• a first light beam scanning mechanism, disposed in said housing and responsive to a first electrical control voltage signal, for scanning said light beam along a first reference direction;
• said first light beam scanning mechanism further including
• a first scanning element of unitary construction having a first base portion, a first light beam deflecting portion, and a first flexible photo-etched gap region disposed therebetween,
• said first base portion being anchored with respect to a first optical bench so as to permit said first light beam deflecting portion to pivot about a first fixed pivot point defined between said first base portion and said first flexible photo-etched gap region,
• said first light beam deflecting portion having a first front surface and a first rear surface and being flexibly connected to said first base portion by said first photo-etched gap region,
• said first light beam deflecting portion having a first natural resonant frequency of oscillation about said first fixed pivot point determined in part by the physical dimensions of said first flexible photo-etched gap region,
• a first permanent magnet mounted on said first light beam deflecting portion,
• a first light beam deflecting element mounted on said first light beam deflecting portion, for deflecting said light beam falling incident upon said first light beam deflecting element,
• a first magnetic-field producing coil having a first pair of input terminals, and disposed adjacent said first permanent magnet, for producing a first magnetic force field of reversible polarity in the vicinity of said first permanent magnet in response to a first electrical current signal flowing through said first magnetic-field producing coil, at an amplitude which varies at a first controlled frequency,
• a first electrical circuit operably connected to said first pair of input terminals, and producing said first electrical control voltage signal which causes said first electrical current signal to flow through said first magnetic-field producing coil and produce in the vicinity of said first permanent magnet, said first magnetic force field having a polarity which varies in accordance with the amplitude and frequency of said first electrical current signal flowing through said first magnetic-field producing coil, and
• said first magnetic force field interacting with said first permanent magnetic and forcing said first light beam deflecting portion to oscillate about said first fixed pivot point at a first forced frequency of oscillation that is substantially equal to said first controlled frequency of said first electrical current signal and substantially different in frequency from said first natural resonant frequency of oscillation of said first light beam deflecting portion, and when said light beam is incident upon said first light beam deflecting element, said light beam being periodically deflected as said first light beam deflecting portion oscillates about said first fixed pivot point at said first forced frequency of oscillation;
• a second light beam scanning mechanism, disposed in said housing and responsive to a second electrical control voltage signal, for scanning said light beam along a second reference direction orthogonal to said first reference direction, so as to produce a raster-type scanning pattern for scanning said 2-D bar code symbol;
• wherein said second light beam scanning mechanism further includes
• a second scanning element of unitary construction having a second base portion, a second light beam deflecting portion, and a second flexible photo-etched gap region disposed therebetween,
• said second base portion being anchored with respect to a second optical bench so as to permit said second light beam deflecting portion to pivot about a second fixed pivot point defined between said second base portion and said second flexible photo-etched gap region,
• said second light beam deflecting portion having a second front surface and a second rear surface and being flexibly connected to said second base portion by said second photo-etched gap region,
• said second light beam deflecting portion having a second natural resonant frequency of oscillation about said second fixed pivot point determined in part by the physical dimensions of said second flexible photo-etched gap region,
• a second permanent magnet mounted on said second light beam deflecting portion,
• a second light beam deflecting element mounted on said second light beam deflecting portion, for deflecting said light beam falling incident upon said second light beam deflecting element,
• a second magnetic-field producing coil having a second pair of input terminals, and disposed adjacent said second permanent magnet, for producing a second magnetic force field of reversible polarity in the vicinity of said second permanent magnet in response to a second electrical current signal flowing through said second magnetic-field producing coil, at an amplitude which varies at a second controlled frequency;
• a second electrical circuit operably connected to said second pair of input terminals, and producing said second electrical control voltage signal which causes said second electrical current signal to flow through said second magnetic-field producing coil and produce in the vicinity of said second permanent magnet, said second magnetic force field having a polarity which varies in accordance with the amplitude and frequency of said second electrical current signal flowing through said second magnetic-field producing coil, and
• said second magnetic force field interacting with said second permanent magnetic and forcing said second light beam deflecting portion to oscillate about said second fixed pivot point at a second forced frequency of oscillation that is substantially equal to said second controlled frequency of said second electrical current signal and substantially different in frequency from said second natural resonant frequency of oscillation of said second light beam deflecting portion, and when said light beam is incident upon said second light beam deflecting element, said light beam being periodically deflected as said second light beam deflecting portion oscillates about said second fixed pivot point at said second forced frequency of oscillation;
• a light collector disposed in said housing, for collecting light reflected off a 2-D bar code symbol scanned by said raster-type scanning pattern;
• a light detector disposed in said housing, for detecting said collected light and producing scan data indicative of the intensity of said detected light;
• and
• a scanning mechanism controller, disposed in said housing, for electrically controlling the operation of said first and second light beam scanning mechanisms so as to produce said raster-type scanning pattern for scanning said 2-D bar code symbol.