WO1999056234A1

WO1999056234A1 - Scanner having movable laser, detector arrangement and two flexures

Info

Publication number: WO1999056234A1
Application number: PCT/US1999/009219
Authority: WO
Inventors: Randall K. Hems; Brian M. Mcmaster; Jay M. Eastman
Original assignee: Psc Inc.
Priority date: 1998-04-29
Filing date: 1999-04-29
Publication date: 1999-11-04
Also published as: EP1073985A1

Abstract

A scanning apparatus comprises a base section (12) having a signal processing unit disposed thereon, and a rotor section (10) attached to the base section and movable relative to the base section. A detector (16) is coupled to the rotor section. A pair of flexures (32, 34) attach the rotor section to the base section and support the rotor section for movement relative to the base section. The pair of flexures each provide a single conductor for signals representative of scanned information to be sent from said the detector to the signal processing unit (33) of the base section.

Description

_SCANNER HAVING MOVABLE LASER, DETECTOR ARRANGEMENT AND TWO FLEXURES

BACKGROUND OF THE I FJNTION

1. Field of the Invention

The present invention relates to a novel optical scanning and bar code reading apparatus . More specifically, the present invention relates to an improved optical scanning and bar code reading apparatus including an improved conductive flexure arrangement, a simplified layout of optical elements, and an improved arrangement of electrical pathways between the rotor and stationary base assemblies of the scanning and bar code reading apparatus .

2. Related Art

Flexure based scanners appearing in the past, such as those disclosed in commonly owned U.S. Patent No. 5,015,831 issued on May 14, 1991, and U.S. Patent No. 5,115,120 issued on May 19, 1992, both incorporated herein by reference, illustrate scan engines using flexural mounts for an oscillating rotor. Such mounts have facilitated miniaturization of scan engines by enabling a laser diode and associated photodetector to be mounted on a rotor, which can be reciprocally - 2 - oscillated relative to a stator to scan a light beam across a bar code.

Other scanning assemblies, including those disclosed in commonly owned U.S. Patent No. 5,629,510, issued on May 13, 1997, and U.S. Patent Serial No. 08/720,296, filed on September 27, 1996, both incorporated herein by reference, include a rotor, a stationary base, and four flexures between the rotor and the base. The flexures permit oscillation of, and provide support to, the rotor with respect to the base. The rotor carries a light source, such as a laser diode, and a coil. The stationary base in turn carries a magnetic source and a light detector.

Although this type of scanning assembly has enjoyed success, the flexure arrangement somewhat overconstrains the movement of the rotor relative to the stationary base. The four flexures attach the rotor to the base at four attachment points, creating a relatively complex, four point suspension. This difficulty is one which may reduce the effectiveness of known bar code scanning assemblies. Other noteworthy problems may also exist; however, the problem presented above should be sufficient to demonstrate that scanning assemblies appearing in the past will admit to worthwhile improvement.

SUMMARY AND OBJECTS OF THE INVENTION

Accordingly, it is therefore a general object of the invention to provide a flexure based scanner which will obviate or minimize difficulties of the type previously described.

It is a specific object of the invention to provide a conductive flexure based scanner which includes a simplified flexure mechanism that eliminates an overconstrained condition present in scanning assemblies appearing in the past. The flexure - 3 - mechanism simplifies the known four point suspension to a two point suspension.

It is a further object of the invention to provide a flexure based scanner which maintains optical alignment of the light source and the light detector, eliminating fabrication errors and costs associated with alignment of moving optical components.

It is another object of the invention to provide a flexure based scanner which is light-weight and durable, has relatively few parts, and is easy to maintain.

It is still another object of the invention to provide a flexure based scanner which enables light-to- frequency conversion of a collected light signal. It is yet another object of the invention to provide a flexure based scanner which provides electrical power and signal paths for both a moving light source and a moving light detector, using only two conductive paths to the stationary base. A preferred embodiment of the invention which is intended to accomplish at least some of the foregoing objects includes a light source and light detector assembly mounted to a rotor, a sense circuit and a signal processing unit and a control unit mounted to a stationary base, and a pair of conductive flexures between the rotor and stationary base that support and suspend the rotor for movement relative to the stationary base. The pair of conductive flexures each provide a single conductive pathway for operation of the light source and the light detector assembly. The flexures supply power to the light source and provide a pathway for transmission of signals that are representative of the output of the light detector assembly and, hence, contain information about the scanned data. The rotor also includes a magnet source, and the stationary base includes an electro-magnetic coil, which is responsive to the magnet source to _ 4 _ oscillate the rotor relative to the stationary base. Oscillation of the rotor scans a laser beam across ^" scannable data, including object or symbol data to be scanned, for example a bar code. Based on information transmitted from circuitry on the rotor through the conductive flexures, the sense circuit and demodulator generate information representative of the scanned bar code .

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent from the following detailed description of an apparatus/method according to the invention taken in conjunction with the accompanying drawings, in which;

Figure 1 is a system block diagram of the flexure based scanner in accordance with the invention;

Figure 2 is a graph of time versus the output of a light-to- frequency converter and shows the correlation of the output frequency of the light-to- frequency converter relative to a bar code being scanned;

Figure 3 is a graph of time versus current through a first flexure of the flexure based scanner and shows the correlation of current through the first flexure relative to the bar code depicted in Figure 2 ; Figure 4 is a front perspective view of an embodiment of a scanning apparatus in accordance with the invention;

Figure 5 is a side view of another embodiment of the scanning apparatus in accordance with the invention; - 5 -

Figure 6A is a top view of the embodiment shown in Figure 5 ;

Figure 6B is a top view of the embodiment shown in Figure 5, illustrating scanning motion of the rotor section in accordance with the invention;

Figure 7 is a top view of yet another embodiment of the scanning apparatus in accordance with the invention;

Figure 8 is a top perspective view of the embodiment of Figure 7;

Figure 9 is a front view of the embodiment of Figure 7 ;

Figure 10 is a side view in cross section of the embodiment of Figure 9 as taken along section line A-A; and

Figure 11 is a rear view of the embodiment of Figure 7 as taken along section line B-B.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like numerals indicate like parts, and initially to Figure 1, there will be seen a block diagram of a flexure based scanning apparatus in accordance with the invention. The flexure based scanning apparatus includes a rotor, represented by box 10, and a stationary base, represented by box 12. The term "rotor, " as used in this application, denotes an element that moves in relation to a stationary base. It will be understood that use of the term "rotor" does not require that the rotor undergo pure rotational movement. Rather, use of the term "rotor" contemplates other types of movement. The rotor 10 moves in a scanning direction to scan the light source and the light detector assembly across scannable material, such as a bar code, as will be described in more detail below. - 6 -

The rotor 10 preferably includes a light source 14, a light detector assembly 16, and a magnet source 18. The rotor also preferably includes a switching transistor 36 and a resistor 38, which is electrically connected to a first terminal (here, a collector) of the transistor 36. Although the transistor 36 is disclosed in Figure 1 as a bipolar transistor, it is not limited thereto. The transistor 36 may be implemented by other transistor types, such as FETs and light transistors. In addition, electrical component 36 need not be a transistor at all, but rather can be a magnetic switch, a light switch, or other suitable switch.

The light source 14 preferably comprises a laser assembly with integrated electronics. The laser assembly 14 provides a continuous wave output. Drive electronics (not shown) preferably are integrated into the laser assembly via a relatively small, application- specific, integrated circuit. Power adjustment could be done by laser trimming of a resistive element during manufacture of the laser assembly. Alternatively, the drive electronics could be incorporated on the rotor, but not as part of the laser assembly itself.

The light detector assembly 16 includes a light- to-frequency converter (also denoted 16 in some subsequent description) and a photodetector which can detect light reflected from a bar code. Light-to- frequency converters suitable for use in the present invention are commercially available and typically have a wide dynamic range, accommodating a large range of collected light levels. Suitable light-to-frequency converters include those sold and marketed by Texas Instruments, such as part number TSL235.

The stationary base 12 includes a main printed circuit board 20 and an electromagnetic element or coil 22. The coil 22 may be mounted directly to the printed circuit board 20, or it may be connected to the - 7 - stationary base by two wires or leads. An input/output element 24 leads to a terminal so that the scanning assembly can be used with, or separately from, a remote unit to provide, as one example, a portable data collection and transaction terminal system for collecting and entering optical data. The output from the printed circuit board may be non-decoded bar code data or ASCII (decoded) data.

The main printed circuit board 20 includes an input voltage 26 (+V_IN) and a sense resistor 28 in parallel with a sense circuit 29 and demodulator 30. Input voltage 26 preferably comprises a connection to an external voltage source. The main printed circuit board 20 also includes a drive circuit 31 for the coil 22. That drive circuit is controlled by control unit 33.

The main printed circuit board 20 further includes a signal processing unit 33 to decode bar code information for output to the terminal via interface circuits 35. In an alternative embodiment, the demodulator 30 may electrically communicate directly with the input/output element 24 and may provide output in the form of undecoded bar code information via the input/output element 24 to the terminal. The signal processing unit, and any control units, may be simple analog components, or they may be incorporated into a microcontroller capable of digital control and processing.

The flexure based scanning apparatus includes a pair of flexures 32 and 34 which electrically connect the rotor 10 and the stationary base 12 and which support and suspend the rotor 10 and its components for movement relative to the stationary base 12. The rotor 10 generally translates side-to-side in a scanning direction relative to the stationary base 12 during scanning . - 8 -

Movement of the rotor occurs due to the interplay between the magnet source 18 and the coil 22. The magnet source 18 and coil 22 electro-mechanically oscillate the rotor side-to-side relative to the stationary base to scan a laser beam across an object or symbol to be scanned, such as a bar code.

Besides mechanically supporting the rotor 10, the first and second flexures 32 and 34 also carry electrical signals between the rotor 10 and the base 12. As stated above, the present invention provides electrical power and signal paths for both the light source and the light detector assembly using only two conductive paths to the stationary base. Put another way, each flexure 32 and 34 preferably comprises a single conductor between the rotor 10 and the base 12.

On the stationary base side, the first flexure 32 is electrically connected to the sense resistor 28 and the sense circuit 29. On the rotor side, the first flexure 32 is connected to the switching transistor 36, one terminal of the laser assembly 14, and one terminal of the light-to-frequency converter 16. On the rotor side, the second flexure 34 is connected to the load resistor 38, another terminal of the laser assembly 14, and another terminal of the light-to- frequency converter 16. And, on the stationary base side, the second flexure 34 is connected to a common return. The electrical pathways in the rotor and stationary base can be formed on platable, molded plastic parts which become structural elements of the rotor and stationary base bodies, or pathways could be formed using conventional printed circuit board materials and fabrication methods, or extensions of the flexure itself could be attached directly to the printed circuit boards. The first flexure 32 maintains a voltage +V_CC (substantially equal to +V_IN minus the voltage drop across the sense resistor 28) . The second flexure 34 - 9 - is connected as a common return. Current leaving the stationary base 12 through the first flexure (I_P1 in Figure 1) substantially equals the current leaving the rotor through the second flexure 34 (I_F2) . The electrical system of the subject flexure based scanner, using transistor 36, switches current through a load resistor 38 ON and OFF in response to the output of the light-to-frequency converter 16, as will be described below. Switching the current through the resistive load ON and OFF, based on the output of the light-to-frequency converter 16, modulates the current through the first flexure 32. The sense circuit 29 can sense that current (I_F1 = I_F2) by measuring the voltage across resistor 28. The resultant voltage waveform can then be demodulated by demodulator 30 to recreate the bar code information.

As shown in Figure 1, current I_F1 from the first flexure 32 branches to a second terminal (here, an emitter) of the transistor 36 ( I_h0AD) and to both the light source 14 and the light-to-frequency converter 16

(Ii_ASHR + C_ONVERTER) • The output (V_ouτ) of the light -to- frequency converter 16 is applied to the control terminal (here, a base) of the transistor 36.

Figure 2 is a graph of time (x-axis) versus the output (V_ouτ) of a light-to-frequency converter (y- axis) . A bar code being scanned is positioned above the graph to show the correlation of the output frequency (V_ouτ) relative to the bar code being scanned.

Light emitted by the laser assembly 14 is reflected back by the bar code and collected by the photodetector of the light detector assembly 16, where the intensity of the collected light is converted to a frequency by the light-to-frequency converter. When the emitted light passes over a dark bar of the bar code, relatively little light is reflected back to the photodetector, and the output frequency (V_ouτ) of the light-to-frequency converter 16 is relatively low. - 10 -

However, when the emitted light passes over white space between the bars of the bar code, more light is reflected back to the photodetector, and the output frequency (V_ouτ) of the light -to- frequency converter 16 increases.

The output frequency (V_ouτ) , which is fed into the base of the switching transistor 36, switches the transistor ON and OFF. The switching transistor turns OFF when V_oϋτ is HIGH and turns ON when V_ouτ is LOW. The switching transistor rapidly turns ON and OFF when V_ouτ has a high frequency (i.e., during scanning of white space of a bar code) and turns ON and OFF more slowly when V_ouτ has a low frequency (i.e., during scanning of a dark bar of a bar code) . Put another way, the transistor turns ON and OFF at a rate based on the amplitude of the output signal from the photodetector (which is converted to a frequency by the light-to- frequency detector) .

When the transistor is OFF, I_L0AD (the current through resistor 38) is nearly 0, and I_F1 equals I^_SER + ϊ-_CONVERTER- When the transistor is ON, I_L0AD has a value, and I_F1 equals I_L0AD ⁺ •'-LASER ⁺ -LCONVERTE_R •

Figure 3 is a graph of time (x-axis) versus I_F1 (y- axis) . As shown, the frequency of I_F1 follows the frequency of V_ouτ and varies between I^_ER + I_CONVERTER ^and Ϊ _OAD + Ϊ_LASER + C_{ON ERTER} depending on V_ouτ (i.e., depending on whether the switching transistor is ON or OFF) .

I_F1, the current through the first flexure 32, approximately equals the current through the sense resistor 28 of the stationary base 12; the sense circuit 29 and demodulator 30 draw a relatively small amount of current. As explained above, I_F1 indicates the value and frequency of the output voltage (V_ouτ) of the light-to-frequency converter 16. Thus, the voltage across the sense resistor 28 (and the sense circuit 29) directly relates to the output voltage (V_ouτ) of the light-to-frequency converter 16. That voltage may be - 11 - demodulated by the demodulator 30 using analog circuits or using microcode in a micro-controller. In this manner, the sense circuit 29 and demodulator 30 can recreate the detected bar code information. As compared to certain prior flexure based scanners, where the light detector is mounted on the stationary base, in the present invention, an additional signal -- the output signal of the light detector -- is transmitted from the rotor to the stationary base. In addition, in these prior flexure based scanners, where the laser assembly is carried by the rotor and the light detector is mounted to the stationary base, proper alignment of the laser assembly and the light detector over the entire range of motion has proved difficult, especially when the rotor translates side-to-side relative to the stationary base. By mounting the light detector on the rotor, the present invention improves alignment of the laser assembly and the light detector. The laser assembly and the light detector remain in the same relative position throughout the scanning motion, resulting in more uniform light collection.

Prior flexure based scanners also included four flexures, rather than two flexures as in the present invention. Trajectory of the rotor relative to the stationary base is easier to control with fewer flexures. Moreover, for a given overall height dimension, using fewer flexures allows the use of wider, and thus stronger, flexures. Figure 4 shows an embodiment of the scanning apparatus for scanning an optical beam over scannable data in accordance with the invention. A rotor 10a has a light source 14a and a light detector assembly 16a mounted thereto. The light source 14a preferably comprises a laser diode assembly, and the light detector assembly 16a preferably comprises a photodetector and a light-to-frequency converter. By - 12 - mounting the light detector assembly 16a on the rotor 10a, the scanning apparatus maintains the alignment of the light source 14a and the light detector assembly 16a throughout the scanning motion, resulting in more uniform light collection.

The rotor 10a itself may be formed as a printed circuit board that contains an electrical circuit for transmission of power signals to the light source 14a and for transmission of electrical signals representative of scanned data from the light detector assembly 16a. The base 12a may also be comprised of a printed circuit board. An electromagnetic assembly is mounted to the base and is responsive to a magnet source mounted to the rotor 10a to move the rotor 10a relative to the base 12a. The electromagnetic assembly and the magnet source are not shown in Figure 4 for convenience of illustration. Examples of these elements may be found in Figures 5, 6, 10, and 11.

A first flexure element 32a and a separate, second flexure element 34a support the rotor 10a relative to the base 12a. In this embodiment, the flexures 32a and 34a are mounted between the front surface 40 of the base 12a and the rear surface 42 of the rotor 10a, one above the other, by brackets 44. The flexures 32a and 34a can be glued, soldered, or otherwise attached to the brackets 44. The brackets 44 are preferably plastic.

It will be understood that the two flexures 32a and 34a may be mounted at different locations on the front surface 40 of the base 12a and the rear surface 42 of the rotor 10a, as long as the flexures support the rotor for movement in a scanning direction. In addition, in an alternative embodiment, the base 12a may be rotated 90 degrees about its vertical axis V-V or horizontal axis H-H, and the flexures 32a and 34a may be attached to a side edge 46 or top (bottom) edge 48, respectively, of the base 12a. - 13 -

The first and second flexures 32a and 34a are conductive and, in the preferred embodiment, each provides a single electrical conductor between the rotor 10a and the base 12a such that only two conductors (or conductive pathways) exist between the rotor 10a and the base 12a for operation of the light source 14a and the light detector assembly 16a. The printed circuit boards that comprise the rotor 10a and the base 12a preferably are configured in the manner described in Figure 1.

In the embodiment of Figure 4, light reflected from a scanned bar code is detected by the photodetector of the light detector assembly 16a. Figures 5, 6A, and 6B show another embodiment with a different light detector assembly 16b. The light detector assembly 16b includes a collection mirror 50 in addition to a light detector assembly 54, which includes a photodetector and a light-to-frequency converter. The collection mirror 50 is curved or shaped to capture light reflected from the scanned bar code. The light source 14b transmits light L to a scannable bar code, and light reflected by the bar code RF is collected by the collection mirror 50 and focused by the collection mirror 50 onto the photodetector of the light detection assembly 54. As with Figure 4, rotor 10b and base 12b may comprise printed circuit boards, and these printed circuit boards are configured in the manner described in Figure 1.

Figure 5 also shows an electromagnetic assembly in the form of coil 22b mounted to the base 12b and a magnet source 18b mounted to the rotor 10b. The interaction of the electromagnetic coil 22b and the magnet source 18b operates to oscillate the rotor relative to the stationary base. As shown in Figure 6B, the rotor 10b moves relative to the base 12b in a scanning direction (shown in at one extreme of a - 14 - scanning arc) to sweep the light source over scannable material .

The Figures 5, 6A, and 6B show one possible configuration for mounting the electromagnetic coil 22b and the magnet source 18b on the scanning assembly; the electromagnetic coil 22b and the magnet source 18b may be positioned elsewhere on the base 12b and rotor 10b, respectively, provided that they interact to enact rotor movement . Figures 7-11 show yet another embodiment of a scanning apparatus in accordance with the present invention. In this embodiment, first flexure 32c and second flexure 34c support rotor 10c on stationary base 12c. The flexures extend from either side of a front surface 60 of the base 12c and angle inward to a rear surface 62 of a first curved portion 64 of a light collector. As will be described in more detail below, the light collector includes the first curved portion 64 and a second portion 66. The second portion 66 in turn generally comprises a top extension 72, a bottom extension 74, and a front extension 76 extending therebetween. The first curved portion 64 and the second portion 66 preferably comprises mirrors with reflective surfaces. The base 12c comprises a printed circuit board and includes, on a rear surface 68, an input/output connector 24c for connection to a remote terminal. The printed circuit board of the base 12c preferably is configured in the manner described in connection with Figure 1. The rotor 10c also includes an electric circuit on a printed circuit board 70; the preferred configuration of the electric circuit of the rotor 10c is described in Figure 1.

As seen best in Figures 10 and 11, an electromagnetic assembly in the form of an electromagnetic coil 22c may be mounted to the base 12c, and a magnet source 18c may be mounted to the - 15 - rotor 10c. The interaction of the electromagnetic coil 22c and the magnet source 18c operates to oscillate the rotor relative to the stationary base in a scanning direction. Depending on the polarity of the coil 22c, the magnet source 18c slides over the coil in one or another direction (into and out of the paper in Figure 10) to move the rotor 10c relative to the base 12c.

A light source 14c, shown as a laser diode, is also mounted to the rotor 10c. The laser diode 14c transmits light L to a scannable bar code. Light RL reflected from the scanned bar code is transmitted to a light collecting surface 63 of the first curved portion 64 of the light collector and then reflected to a light collecting, convex rear face 78 of the front extension 76 of the second portion 66, as shown in Figure 10. The light RL then passes to a photodetector of the light detector assembly 16c. Like in the previous embodiments, the light detector assembly 16c comprises a photodetector and light-to-frequency converter. The light-to-frequency converter is electrically connected to the electronic circuit on the rotor's printed circuit board 70. The printed circuit board 70 communicates with the flexures 32c and 34c, for example, via extensions 67 of the flexure itself that attach directly to the printed circuit board 70, as shown in Figure 7. These extensions 67 may extend through brackets 88 and 90. The output of the light- to-frequency converter is electrically communicated through flexures 32c and 34c to the printed circuit board of the base 12c in the same manner described in connection with Figures 1-3. Figures 10 and 11 also show an optional filter element 80 through which the reflected light passes before reaching the light detector assembly 16c. The second portion 66 of the light collector of this embodiment preferably is mounted to the printed circuit board 70 via elements 84, as shown in Figure - 16 -

10. The first curved portion 64 of the light collector has an opening 86, shown in Figure 8, through which the light source 14c may electrically communicate with the printed circuit board 70. The flexures 32c and 34c are mounted to brackets 88 and 90, respectively, that in turn are mounted to the rear face 62 of the first curved portion 64 of the light collector. The flexures 32c and 34c mechanically support the rotor 10c relative to the base 12c and allow the rotor 10c to move in a scanning direction. The flexures 32c and 34c each provide a single conductor between the rotor 10c and the base 12c to effect operation of the light source 14c and transmission of electrical signals from the light-to- frequency converter to the base circuitry.

The embodiment of Figures 7-11 provides a high performance scanner in a small volume. The use of the light detection assembly 16c allows for a large light collection aperture combined with excellent optical noise rejection. The embodiment of Figures 7-11 also integrates the light source 14c and the light detector assembly 16c in one structure, i.e., the rotor 10c, thus eliminating optical alignment problems that are inherent in combined dynamic/static optical systems. The location and shape of the first curved portion 64 of the light collector allows a larger portion of the light detector assembly 16c to actively collect light reflected from a scanned bar code, thus increasing available bar code read ranges . In the present invention, the two flexures are preferably formed of the same material and dimensioned to have the same thickness. The flexures, however, may differ in cross-sectional geometry from each other in some circumstances . These two independent flexures provide all of the mechanical support for the rotor in the present scanning apparatus . - 17 -

In each of the above embodiments, the scanning apparatus includes two separate flexure elements that operate to support the rotor relative to the stationary base and that serve as conductors (one conductor per flexure element) for transfer of information between the rotor and the base. It may also be possible to have a two-flexure apparatus where one flexure provides both conductors and the other flexure does not transmit information between the rotor and the base. In such an embodiment, the two separate flexures operate to support the rotor relative to the base and therefore are structurally configured to provide any necessary mechanical balance to the scanning apparatus. In this embodiment, as in the previously described embodiments, the scanning apparatus requires only two conductors (or conductive pathways) for its operation.

In describing the invention, reference has been made to a preferred embodiment and illustrative advantages of the invention. Those skilled in the art, however, and familiar with the instant disclosure of the present invention, will recognize additions, deletions, modifications, substitutions, and other changes which will fall within the purview of the present invention.

Claims

- 18 -What Is Claimed Is:

1. A scanning apparatus comprising: a base section having a signal processing unit disposed thereon; a rotor section attached to said base section and movable relative to said base section; a light source electrically communicating with said rotor section; a detector electrically communicating with said rotor section; a single pair of flexures attaching said rotor section to said base section and supporting said rotor section relative to said base section, said single pair of flexures transmitting signals representative of scanned information to be sent from said detector to said signal processing unit of said base section.

2. A scanning apparatus as claimed in claim 1, wherein each of said single pair of flexures provides a single conductor.

3. A scanning apparatus as claimed in claim 1, wherein one of said single pair of flexures is connected to common ground.

4. A scanning apparatus comprising: a base section; a single pair of flexures that have a first conductive pathway and a second conductive pathway respectively disposed thereon; a rotor section flexibly attached to said base section by said pair of flexures for allowing said rotor section to move relative to said base section, said first conductive pathway providing a first electrical signal from said base section to said rotor section, and said second conductive pathway providing - 19 - a second conductive pathway from said rotor section to said base section, said rotor section including a photodetector and a switch coupled to said photodetector, said photodetector providing an output signal based on an amount of light received by said photodetector, and said switch switching on and off at a rate based on a parameter of the output signal to vary the electrical signal through one of said pair of flexures.

5. A scanning apparatus as claimed in claim 4, wherein said parameter comprises an amplitude of the output signal of said photodetector.

6. A scanning apparatus as claimed in claim 4, wherein said switch comprises a switching transistor.

7. A scanning apparatus for scanning an optical beam over scannable data, comprising: a rotor section having mounted thereto a light source, a light detector assembly, and an electrical circuit for transmission of power signals to said light source and for receipt of electrical signals representative of scanned data from said light detector assembly; a base section having mounted thereto a signal processing unit and a control unit; a sense circuit for generating an output representative of the scanned data, said sense circuit electrically communicating with said base section and said rotor section; and a first flexure element and a second flexure element for movably supporting said rotor section relative to said base section, said first flexure element and said second flexure element each being conductive and each providing a single conductor between said rotor section and said base section such - 20 - that only two conductors exist between said rotor section and said base section for operation of said light source and said light detector.

8. A scanning apparatus as claimed in claim 7, wherein said sense circuit is mounted to said base section.

9. A scanning apparatus as claimed in claim 7, wherein said first flexure element and said second flexure element are composed of insulative material and said two conductors are plated to said insulative material .

10. A scanning apparatus as claimed in claim 9, wherein said insulative material is plastic.

11. A scanning apparatus as claimed in claim 7, wherein said first flexure element and said second flexure element comprise flexible printed circuit boards .

12. A scanning apparatus as claimed in claim 7, wherein current travelling through said first flexure element substantially equals current travelling through said second flexure element.

13. A scanning apparatus as claimed in claim 7, wherein said light detector assembly comprises a photodetector connected to a light-to-frequency converter, and an output of said light-to-frequency converter is representative of the scanned data.

14. A scanning apparatus as claimed in claim 13, wherein said electrical circuit of said rotor section comprises a switching transistor and a load resistor electrically connected to a first terminal of said - 21 - switching transistor, and wherein said light-to- frequency converter is electrically connected to a control terminal of said switching transistor for receipt of said electrical signals from said light-to- frequency converter.

15. A scanning apparatus as claimed in claim 14, wherein said first flexure element is electrically connected to said sense circuit and also is electrically connected to a terminal of said light source, to a terminal of said light-to-frequency converter, and to said a second terminal of said switching transistor.

16. A scanning apparatus as claimed in claim 14, wherein said second flexure is electrically connected to a common return and also is connected to an other terminal of said light source, to an other terminal of said light-to-frequency converter, and to said load resistor.

17. A scanning apparatus as claimed in claim 7, further comprising a demodulator mounted to said base section, said base section being electrically connected to said sense circuit for receipt of said output of said sense circuit and to said signal processing unit.

18. A scanning apparatus as claimed in claim 17, further comprising an input/output element electrically communicating with said demodulator to transmit the scanned data in undecoded form to a remote terminal unit .

19. A scanning apparatus as claimed in claim 17, further comprising a resistor mounted in parallel to said sense circuit such that said sense circuit is adapted to measure voltage across said resistor, - 22 - wherein the measured voltage is indicative of the scanned data .

20. A scanning apparatus as claimed in claim 7, further comprises a magnet source mounted to said rotor section, and an electromagnetic element electrically connected to said control unit of said base section, said magnet source being responsive to said electromagnetic element to move said rotor section relative to said base section.

21. A scanning apparatus as claimed in claim 20, further comprising a drive circuit for driving said electromagnetic element, said drive circuit electrically communicating with said control unit.

22. A scanning apparatus as claimed in claim 20, wherein said electromagnetic element comprises an electromagnetic coil.

23. A scanning apparatus as claimed in claim 21, wherein said electromagnetic coil is mounted directly to said base section.

24. A scanning apparatus as claimed in claim 21, wherein said electromagnetic coil is electrically connected to said base section.

25. A scanning apparatus as claimed in claim 7, further comprising an input/output element electrically communicating with said signal processing unit to transmit the scanned data in decoded form to a remote terminal unit .

26. A scanning apparatus as claimed in claim 25, further comprising an interface circuit electrically - 23 - connected to said signal processing unit and said input/output element.

27. A scanning apparatus as claimed in claim 7, wherein said light source comprises a laser assembly.

28. A scanning apparatus as claimed in claim 7, wherein said signal processing unit, said control unit, and said sense circuit are mounted to a printed circuit board on said base section.

29. A method of transmitting information representative of scanned data from a rotor section of a scanning apparatus to a base section of the scanning apparatus , comprising : providing a first flexure element and a second flexure element; affixing the first flexure element and the second flexure element between the rotor section and the base section, said first flexure element and said second flexure element each providing a single conductor between said rotor section and said base section; transmitting the information representative of scanned data from the rotor section to the base section via said single conductor provided by one of said first flexure element and said second flexure element.