Abstract:
A scan module for use in a bar code reader including a base, a light source, a focusing lens, a scan mirror mounted for oscillatory motion relative to the base so as to create a scanner laser beam, and a magnifying lens for magnifying the angle of reflection of a light beam from the light source off the scan mirror.

Description:
This is a continuation of U.S. patent application Ser. No. 10/059,552, filed Jan. 29, 2002, now U.S. Pat. No. 6,648,227, which is a continuation of U.S. patent application Ser. No. 09/692,318, filed Oct. 20, 2000, abandoned, which is a division of U.S. patent application Ser. No. 09/152,264, filed Sep. 14, 1998, now U.S. Pat. No. 6,186,399, which is a division of U.S. patent application Ser. No. 08/438,163, filed Jun. 7, 1995, now U.S. Pat. No. 5,966,230, which is a division of U.S. patent application Ser. No. 08/141,342, filed Oct. 25, 1993, abandoned. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to scanners. More specifically, the present invention relates to integrated barcode scanners mounted on common substrates. 
   Barcodes store information about an associated object and are read by scanners, which are now handheld. As barcode scanners have become smaller, the number of uses have increased. Today, barcode scanners are used to price store items, control warehouse inventory, and even route overnight packages. 
   In reading a barcode, a barcode scanner scans a laser beam across the barcode and detects the reflected light from the barcode. Typically, barcode scanners,including handheld scanners, have been constructed using discrete components. These discrete components, such as laser diodes and rotatable scanning mirrors, are separately manufactured and carefully aligned in the scanner to obtain the proper scanning function. 
   However, the use of discrete components limits further miniaturization of the barcode scanner, thus restricting additional uses for the barcode scanner. Further, improper alignment of the discrete components can render the scanner inoperative. Thus, the discrete components must be carefully aligned during assembly, making the scanner complex and costly to construct. 
   Accordingly, it is desirable to provide an improved barcode scanner with increased flexibility. 
   It is also desirable to provide a miniaturized barcode scanner. 
   It is also desirable to provide a barcode scanner that is simpler to construct. 
   It is also desirable to decrease the cost of constructing a barcode scanner. 
   Additional desires of the invention will be set forth in the description which follow, and in part will be apparent from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the amended claims. 
   SUMMARY OF THE INVENTION 
   To achieve the foregoing desires, a barcode scanner mounted on a common substrate is disclosed. More, particularly and in accordance with the purposes of the invention as embodied and broadly described herein the present invention provides a light scanning system formed on a common substrate comprising a light scanner, integrated on the substrate, for scanning light across a target and a sensor, integrated on the substrate, for detecting light reflected from the target. 
   The barcode scanner may include a light scanner comprising a micro-machined mirror which may be rotated or bent to scan an incident light beam. The barcode scanner may also scan a light beam without using a micro-machined mirror by rotating a light source. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the objects, advantages, and principles of the invention. 
     In the drawings, 
       FIG. 1  is a side view of a scanner according to a first embodiment of the present invention; 
       FIG. 2  is a plan view of a scanner according to the first embodiment of the present invention; 
       FIG. 3  is a side view of a scan module used in the scanner shown in  FIG. 1 ; 
       FIG. 4  is a side view of a scanner according to a second embodiment of the present invention; 
       FIG. 5  is a side view of a scanner according to a third embodiment of the present invention; 
       FIG. 6  is a plan view of a scanner according to the third embodiment of the present invention; 
       FIGS. 7A and 7B  show a side view of scanners according to a fourth embodiment of the present invention; 
       FIG. 8  is a perspective view of another scan module according to the present invention; 
       FIG. 9  is perspective view of a scanner according to a fifth embodiment of the present invention; 
       FIGS. 10A-10B  area top and side view respectively, of a retro-collective micro-machined mirror according to the present invention; 
       FIG. 11  is a side view of a scan module according to the present invention using deformable mirrors; 
       FIGS. 12A-12C  are a perspective, side, and top view, respectively, of a scanner according to a sixth embodiment of the present invention; and 
       FIG. 13  shows a scanner system incorporating the scanner according to the present invention. 
   

   DETAILED DESCRIPTION 
   The present invention is directed to a light scanning system formed on a common substrate. The light scanning system may include a light source for producing a light beam, a deflector for deflecting the focused light beam in a desired pattern, a lens, a detector for monitoring the light beam from the light source, a sensor for detecting a reflection of the deflected light beam, and electronic circuits. 
   Reference will now be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. 
   A first embodiment of the scanner of the present invention is shown in FIG.  1  and is designated generally by reference numeral  100 . Scanner  100  includes a laser diode  112 , spherical lens  114 , scan module  118 , and detectors  120  and  128 . Laser diode  112  and detector  128  are mounted on a laser submount  126  which serves as a supporting stand. Spherical microlens  114  is supported by lens holder  116 . Laser submount  126 , lens holder  116 , scan module  118 , and detector  120  are mounted on a substrate  122 . 
   The surface of substrate  122  includes a flat portion  121  adjacent to a sloped portion  123 . Laser submount  126  and lens holder  116  are mounted on flat portion  121 . Scan module is mounted on sloped portion  123 . In a preferred embodiment, substrate  122  is made of a semiconductor material such as silicon, and the sloped portion  123  is inclined at about a 45° angle. 
   Laser diode  112  is aligned with an optical axis of lens  114  and emits a visible laser beam according to a laser diode driver, not shown in the drawings. In a preferred embodiment, laser diode  112  can be any commercially available laser diode which is capable of producing a laser beam suitable for bar code scanning, such as the laser diode chip from a Sony SLD 1101 VS. 
   Detector  128  is mounted on laser submount  126  behind laser diode  112  for monitoring the output of laser diode  112 . Detector  128  creates a signal representative of the amount of light output from the back of laser diode  112 , which is proportional to the intensity of the laser beam output from the front of laser diode  112 . That signal can be transmitted to a laser diode driver to control the output of laser diode  112 . 
     FIG. 1  shows lens  114  secured in an upright position by a separate lens holder  116 . It is understood that lens  114  and lens holder  116  could also be a single integrated device. Although  FIG. 1  shows lens holder  116  mounted on the flat portion of substrate  122 , it could also be attached to laser submount  126 . Also, although lens  114  is shown as a spherical microlens in the preferred embodiment, lens  114  could also comprise any other lens for focusing a laser beam, such as a ball microlens, a grated rod index lens (GRIN), a micro-FRESNEL lens, or a cylindrical microlens. 
   The desired focus of the laser beam can be achieved by adjusting the distance between lens  114  and laser diode  112 . Although lens holder  116  may be adjustable to move lens  114  closer to or farther from laser diode  112 , it is preferred that lens  114  be fixed in a pre-aligned position. 
   Scan module  118  is mounted on the sloped portion  123  to permit scan module  118  to intercept and deflect a laser beam from laser diode  112 . During operation of scanner  100 , scan module  118  scans the laser beam in one dimension across a target. 
   Scan module  118  preferably comprises a micro-machined mirror, which is fabricated using existing VLSI technology. K. E. Peterson, “Silicon as a Mechanical Material,” Proc. of IEEE, Vol. 70, No. 5, 420-457 (May 1982), U. Breng et al., “Electrostatic Micromechanic Actuators,” 2 J. Micromech. Microeng. 226-261 (1992), and Larry J. Hornbeck, “Deformable-Mirror Spatial Light Modulators,” 1150 Proceedings of SPIE (1989) describe acceptable techniques for fabricating micro-machined mirrors. 
   Detector  120 , which is preferably mounted on the flat portion  121  of substrate  122 , detects a reflection of a laser beam as the beam is scanned across a target. The laser beam scattters as it is scanned across the target, thus allowing detector  120  to receive and detect light reflected from the target. Detector  120  then creates a signal representing the detected reflection. For example, where a laser beam has been scanned across a barcode having light and dark regions, the light regions of a barcode will reflect light, while the dark regions will not. As the laser beam is scanned across the barcode, detector  120  detects the dispersed light, which represents the light regions of the barcode, and creates a corresponding signal, thus permitting the barcode to be “read.” In a preferred embodiment, detector  120  is a monolithically integrated photodetector. 
     FIG. 2  shows a top view of scanner  100 . Laser diode  112 , lens  114 , and scan module  118  are arranged in alignment with each other to permit scan module  118  to deflect a focused laser beam. Detector  120  can be located on either side of lens holder  116 . 
   Wire bond pads  130  permit detector  120  to interface with an external device, for example, a signal processor. Wire bond pads  132  and  134  permit laser diode  112  and detector  128 , respectively, to interface with an external device, such as a laser diode driver for controlling the output of laser diode  112 . Wire bond pads  142  allow micro-machined mirror to be actuated by an external device such as a feedback circuit (not shown). 
   Scan module  118  of the present invention may be implemented using various structures such as torsional or cantilever as described in detail below. Further, scan module  118  can be actuated by various techniques also described in detail below such as electrostatic actuation and heat actuation. Under heat actuation, for example, hinges are made of shape memory alloy or are bimetallic. 
   Under a torsional structure, scan module  118  includes scanning mirror  136 , torsional hinges  138 , and frame  140 . Hinges  138  are supported by frame  140 , which is mounted on the sloped portion  123  of substrate  122 . Scanning mirror  136  is suspended by hinges  138  and rotates about an axis formed by hinges  138  along the surface of the sloped portion of substrate  122 . Scanning mirror  136  can be rotated up to 90°. As described above, wire bond pads  142  permit scan module  118  to interface with an external device, such as a scan module driver for controlling scan module  118 . 
     FIG. 3  shows various elements for controlling scan module  118 . Electrostatic actuation is one way that scan module  118  can rotate mirror  136  to scan an incident laser beam. Accordingly, in the preferred embodiment, scan module  118  includes upper electrodes  144  mounted on a glass cover  148  on either side of the rotation axis above mirror  136 , and substrate electrodes  146  mounted on substrate  122  on either side of the rotation axis below mirror  136 . Upper electrodes  144  need to be transparent to allow light to enter and exit scan module  118 , For example, upper electrodes  144  can be formed by depositing on glass cover  148  a semi-transparent-metallic coating having a low reflectivity. 
   During operation of scan module  118 , upper electrodes  144  and substrate electrodes  146  are energized to create an electrostatic force to rotate mirror  136 . The electrostatic force creates a voltage between one of the substrate electrodes  146  and mirror  136 , which in turn creates charges of opposite polarity between substrate electrode  146  and mirror  136 . The resulting attractive force pulls the closer side of mirror  136  downward, thus rotating mirror  136  along the rotation axis. 
   At the same time, a voltage is applied between mirror  136  and a corresponding upper electrode  144  to aid the substrate electrode  146  in rotating mirror  136 . The resulting attractive force pulls the other side of mirror  136  upward, continuing to rotate mirror  136  in coordination with the substrate electrode  146 . 
   Mirror  136  can be rotated in the opposite direction by applying voltages to the other substrate electrode  146  and upper electrode  144 . An incident light beam can be scanned by scan module  118  by alternately applying voltages to the appropriate substrate electrodes  146  and upper electrodes  144 . This approach provides a simple method of actuating scan module  118  using very low power consumption. 
   Although  FIG. 3  shows both upper electrodes  144  and substrates electrodes  146 , mirror  136  could also be rotated using only one set of electrodes, i.e. either upper electrodes  144  or substrate electrodes  146 . In such a configuration, substrate electrodes  146  could rotate mirror  136  without using upper electrodes  144  by alternately applying voltages between the substrate electrodes  146  and mirror  138 . Upper electrodes  144  could work alone in the same manner. Either situation would require a greater attractive force to rotate mirror  136 . 
   While hinges  138  can be made of any suitable material hinges  138  are preferably made of a shape memory alloy, such as titanium-nickel, because of the unique shape-restoring features of such alloys. Shape memory alloys return to their original shape when heated above a transition temperature. After hinges  138  are twisted by the rotation of mirror  136 , they can be subjected to a short electric pulse prior to each scan to heat them and return mirror  136  to its original position. In a preferred embodiment, a 10-20 mW pulse can be applied for 10 milliseconds or less to restore mirror  136  to its original position. 
   Additional embodiments of the invention will now be described where like or similar parts are identified throughout the drawings by the same reference characters. 
     FIG. 4  shows a second embodiment of a scanner of the, present invention. Scanner  102  includes laser diode  112  mounted on laser submount  126  in alignment with an optical axis of lens  144  for emitting a laser beam, and detector  128  mounted on laser submount  126  for monitoring the output of laser diode  112 . Lens  144 , supported by lens holder  116 , focuses the laser beam emitted from laser diode  112 . Laser submount  126  and lens holder  116  are mounted on a flat portion  121  of substrate  122 . Scan module  118 , mounted on a sloped portion  123  of substrate  122 , deflects the focused light beam across a target, and detector  120  detects a reflection of the scanned laser beam. 
   In addition, scanner  102  further includes lens  146 , supported by lens holder  142 , for magnifying the deflection of the beam from scan module  118  before the beam is scanned across a target. A wider deflection of the beam allows a smaller mechanical deflection angle of a micromirror in modules  118 , and increases the flexibility in focusing the beam. As shown in  FIG. 4 , lens  144  is a positive lens and lens  146  is a negative lens, though it is understood that lens  144  and lens  146  can be of any type. 
     FIG. 5  shows a third embodiment of the invention as scanner  104  comprising laser diode  112  mounted on laser submount  126 , which is in turn mounted on flat portion  121  of substrate  122 . Detector  128  is also mounted on laser submount  126  behind laser diode  112  for monitoring the output of laser diode  112 . Scan module  118 , mounted on the sloped portion  123  of substrate  122 , receives an unfocused laser beam from laser diode  112  and deflects that beam through lens  148 , which is supported by lens holder  150 . Lens  148  focuses the deflected beam before it reaches a target, such as a barcode. The configuration of scanner  104  provides a simple and compact structure due to the absence of a lens between laser diode  112  and scan module  118 . 
     FIG. 6  shows a top view of scanner  104  without lens  148 . Laser diode  112  is aligned with scan module  118 . Wire bond pads  132  and  134  allow external devices to interface with laser diode  112  and detector  128 , respectively. Wire bond pads  142  allow external devices to interface with the micro-machined mirror. Although  FIG. 6  shows no detector for detecting the reflected light, such a detector may easily be mounted near scan module  118  or at some other desirable location. 
   A fourth embodiment of the present invention bends the light beam onto a scan module and is shown in  FIGS. 7A and 7B . As shown in  FIGS. 7A and 7B , respectively, scanners  106 , and  107  comprise laser diode  112 , lens  114 , scan module  118 . Lens  114  used in scanners  106  and  107  can be of any type and is mounted on substrate  222 , which is completely flat. Laser diode  112  is mounted on laser submount  126 . 
   As shown in  FIG. 7A , laser diode  112  of scanner  106  is aligned above an optical axis of lens  114  by an amount x. By aligning laser diode  112  in this way, the laser beam emitted from laser diode  112  is bent downward an angle θ. The bent laser beam strikes scan module  118 , which is mounted on flat substrate  222 . Scan module  118  scans the laser beam across a target in the manner described in the other embodiments. 
   As shown in  FIG. 7B , scanner  107  also includes a prism  115  positioned adjacent to lens  114 . A laser beam emitted from laser diode  112  passes through lens  114  and is bent downward by prism  115  onto scan module  118 . Again, scan module  118  scans the laser beam across a target in the manner described in the other embodiments. 
   Bending the laser beam emitted from laser diode  112  eliminates the need for a sloped substrate. This provides a distinct advantage because a flat substrate is easier to manufacture than a sloped substrate. 
     FIG. 8  shows another scan module according to the present invention designated by numeral  119 . Mirror  136 , suspended by hinges  138 , rotates along an axis of rotation perpendicular to an incident laser beam. Hinges  138  are supported by frame  140 . Mirror  136  is tilted at an angle with respect to the surface of substrate  222  to intercept and deflect an incident light beam perpendicular to the surface of substrate  222 . Mirror  136  is rotated back and forth, for example, using electrostatic actuation as described above, causing an incident laser beam to be scanned across a target such as a barcode. 
     FIG. 9  shows a fifth embodiment of a scanner of the present invention. Scanner  108  implements scan module  119  shown in FIG.  8 . In scanner  108 , laser diode  112 , mounted on flat substrate  139 , emits a laser beam parallel to the surface of substrate  139  onto mirror  136 . Detector  128  monitors the output of laser diode  112 . Hinges  138 , also mounted on flat substrate  139 , allow mirror  136  to rotate and deflect the beam in a desired pattern. A groove  137  is etched in substrate  139  in front of laser diode  112  to hold a lens (not shown) to focus the laser beam emitted from laser diode  112 . 
   Scanner  108  of  FIG. 9  is more planar than scanner  100  of  FIG. 1  since the components, including scan module  119 , can be mounted on a single, low-profile, flat substrate  139 . Not only is the flat substrate  139  of scanner  108  easer to manufacture than the sloped substrate  123  of scanner  100 , the low profile of scanner  108  requires less space than scanner  100 , thus allowing it to be used in more applications. 
     FIGS. 10A and 10B  show a top and side view, respectively, of a retro-collective micro-machined mirror  135 . Retro-collective micro-machined mirror  135  can be implemented in place, of scan module  118  or  119  in any of the embodiments of the present invention. Mirror  136  is mounted in the center of detector  120 , which is suspended by hinges  138 . Mirror  136  and detector  120  are rotated along hinges  138  by electrostatic actuation as described above, causing a laser beam incident to mirror  136  to scan a target. Detector  120  detects a reflection of the scanned beam from the target. 
   Retro-collective micro-machined mirror  135  minimizes the amount of space required in a scanner by eliminating the need for a separate detector and scan mirror. Further, detector  120  in the retro-collective micro-machined mirror  135  detects reflected light more effectively than a stationary detector because detector  120  is always rotated to face the scanned target, thus allowing detector  120  to receive more dispersed light reflected from the target. This also reduces noise (i.e. light not reflected from the target) detected by detector  120 . 
     FIG. 11  shows a scan module  164  with a cantilever structure that uses deformable mirrors rather than a rotating mirror. Scan module  164  includes mirror element  150 , support  152 , silicon electrodes  154 , oxide film  156 , silicon substrate  158 , and voltage source  160 . 
   Mirror element  150  is made of a reflective material, such as aluminum, and is electrically grounded and secured at one end to support  152 . Support  152  is mounted on electrode  154 , which is coated with oxide film  156  for electrical insulation. Electrode  154  is mounted on substrate  158  and is connected to voltage source  160 . Electrode  154  is separated from mirror element  150  by air gap  162 . 
   When voltage source  160  applies a voltage to an electrode  154 , it creates an electrostatic field within air gap  162 , causing an electrostatic attraction between electrode  154  and corresponding mirror element  150 . The electrostatic attraction forces mirror element  150  to bend downward and deflect an incident light beam. Proper control of the electrostatic would scan an incident light beam. 
   The present invention can also be implemented without using mirrors.  FIGS. 12A-12C  show a perspective, side, and top view, respectively, of a sixth embodiment of the present invention. Scanner  170  includes focusing module  178  rotatably mounted on scan module  180 . Focusing module  178  comprises laser diode  172 , lens  174 , and aperture  176 , and is suspended by hinges  182  the same way mirror  136  is suspended by hinges  138  in scan module  118  (see FIG.  3 ), and focusing module  178  can be rotated back and forth along hinges  182  the same way mirror  136  is rotated along hinges  138  by scan module  118 . 
   A laser beam emitted from laser diode  172  passes through lens  174  and aperture  176  to focus the beam. Rotating focusing module  178  thus scans an incident laser beam across a target, such as a barcode, without using a mirror. 
     FIG. 13  shows a scanner system  200  incorporating scanner  202 , which represents the various embodiments of the present invention. External devices  204  are connected to scanner  202  by lines  206 . Scanner system  200  may be, for example, a stationary barcode scanner or a handheld barcode scanner. 
   The scanners of the present invention can be manufactured using either monolithic integration or hybrid integration. Monolithic integration fabricates the opto-mechanical system entirely on a single semiconductor chip. On the other hand, a hybrid integrated circuit combines one or more individually-fabricated subsystems on a common substrate. Hybrid integration generally involves less complicated processes than monolithic integration and permits the combination of more accurate devices. 
   Many of the components of the present invention including the laser diode, detectors, lenses, and scan module could be fabricated using VLSI technology. If monolithic integration is used, all of these components are fabricated onto a single chip in a single series of process steps. If hybrid integration is used, each component is individually fabricated and mounted onto a common substrate. 
   However, it is not necessary that all of the components be VLSI. For example, the lens for focusing the light beam could be constructed using other known,techniques and then appropriately mounted onto the scanner. 
   It will be apparent to those skilled in the art that various modifications and variations can be made in the scanner of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.