Abstract:
An implementation of a system, device and method for projecting a visual indicator against a surface is provided. A display projection system in a handheld sensor device (e.g. a handheld wall scanner) projects a static or computer-controlled dynamic pattern of light onto a surface being scanned to indicate a specific feature, such as existence of solid structures of wood, metal or plastic, electric or magnetic fields, or a disturbance of a field. The projected light may be controlled by a computer via an aperture to allow flexibility in what is projected, such as icons, lines, graphics, characters and colors.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation and claims the benefit under 35 U.S.C. §120 of U.S. Pat. No. 8,581,724 by Barry Wingate as the first named inventor, entitled “Dynamic information projection for a wall sensor”, and filed Oct. 16, 2009, which is incorporated herein by reference in its entirety, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/105,856 by Anthony J. Rossetti as the first named inventor, entitled “Dynamic information projection for a wall sensor”, and filed Oct. 16, 2008, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates generally to handheld sensor devices, such as stud sensors, and more specifically to projection of visual indicators against a surface regarding a hidden object. 
     Background of the Invention 
     Portable sensors, including handheld detector units, are used to locate hidden objects are known. For example, U.S. Pat. Nos. 4,099,118, 4,464,622, and 6,259,241, which are incorporated herein by reference, disclose detector units (e.g., “stud sensors” and alternating current detectors) that identify a hidden object&#39;s position behind a surface. Some handheld detectors identify the hidden object by measuring a capacitance change in one or more sensor elements within the detector unit as the user moves the unit across the wall over the hidden object. Such hidden objects include wooden structural studs, pipes, and other metal and nonmetal objects such as wiring. Some handheld detectors contain sensor element and detecting circuitry to measure electromagnetic field changes to identify wires carrying alternating current. Some detectors identify objects that affect a local magnetic field, such as masses of metal or gas lines. 
       FIG. 1  illustrates a typical application in which a user holds a handheld sensor device  10  against wall or other surface  12 . The user moves device  10  transversely, as indicated by the arrows, to detect an object hidden from view behind the surface  12 . The object may be hidden framing or a stud  14  defining a first edge  18 , a centerline  20  and a second edge  22 . Circuits within device  10  display the sensed information on display  16 . 
     A handheld detector unit typically indicates a sensed feature (e.g., an edge  18  or a centerline  20 ) using a visual display, such as display  16 . A device&#39;s visual display may include one or more light-emitting diodes (LEDs) and/or liquid crystal display (LCD) in various configurations. For example, some devices include an arrow-shaped LED display. Another device sold under the name Intellisensor® made by Stanley in New Britain, Conn., uses a vertical line of LEDs for a display. In addition, U.S. Pat. No. 6,249,113, issued Jun. 19, 2001, and U.S. Pat. No. 5,917,314, issued Jun. 29, 1999, both incorporated herein by reference, disclose several LCD and LED display configurations. Typically, a visual display  16  of a handheld sensor device is designed to assist the device user in determining some characteristic of a sensed object, such as an edge or a centerline. Referring again to  FIG. 1 , for example, display  16  may indicate stud  14 &#39;s edge  18 , a centerline  20  located between edge  18  and edge  22 , both edges  18  and  22 , or other representations of stud  14 . 
     The display or displays  16  are typically mounted in the housing of the handheld sensor device. Thus, the display  16  is distance from the surface  12 . That is, the display  16  is displaced both laterally and in depth from the surface  12  behind which the detected object is located. Furthermore, users often operate handheld detectors at skewed angles and in unusual positions such as when searching for objects that are behind ceilings, floors, corners, etc. For example, in  FIG. 1 , if stud  14  is located behind a surface  12  that is close to a large visual obstruction, such as a water heater tank, the user will have difficulty seeing display  16 . Even if display  16  is visible, the skewed viewing angle requires the user to make a visual angular estimate of the hidden object&#39;s location behind the surface, based on the display&#39;s position in the detector unit housing. 
     Known in an unrelated art is projecting information from a computer against a surface. For example, U.S. Pat. No. 6,266,048, by Carau, Sr., issued on Jul. 24, 2001 and titled “Method and apparatus for a virtual display/keyboard for a PDA”, discloses a computer or PDA with a projected display onto a substantially flat, white surface to create a virtual computer screen display and a projected keyboard onto the substantially flat, white surface. Similarly in U.S. Pat. No. 7,215,327, by Liu et al. issued May 8, 2007 and titled “Device and method for generating a virtual keyboard/display”, a keyboard and display are projected. Such projection technologies may be advantageously used in handheld sensor devices. 
     Handheld sensor devices, such as stud sensors, wall scanners, AC voltage detectors and magnetic field disturbance sensors, display information to a user using one or more LEDs and/or LCD displays located on the body of the device. Some devices use light passed through an aperture or slit on the body of the device to project a line or lines onto the wall surface. Such a slit does not produce a distinct two-dimensional icon but rather a length of light that has no discernible or distinctive features along a dimension. See, for example, U.S. Pat. No. 6,259,241, by Krantz issued on Jul. 10, 2001 and titled “Projected display for portable sensor indicating the location of a detected hidden object behind a surface”, which discloses a handheld detector that projects a visible pattern onto the surface behind which a detected object is located. The projected pattern represents one or more predetermined characteristics of the detected object. A predetermined characteristic may include an edge, a position between two edges, a centerline between two edges, a characteristic of the object&#39;s mass, and/or an electromagnetic characteristic emitted or affected by the object. Also discloses is a narrow aperture defined in one end of the detector unit housing. When the detector unit&#39;s sensing circuit detects a hidden object, the sensing circuit signals an activating circuit that energizes a light source within the detector housing. A portion of the light from the light source passes through the aperture and thereby projects a line onto the surface beneath which the detected object is located. The line is projected in a single dimension. That is, there is no lateral distinctiveness to the projected line. Furthermore, the projected line may not have distinct side edges or the line may easily be misaligned due to the LED being butted against the aperture opening. 
       FIG. 1  illustrates a typical application in which a user holds a handheld sensor device against wall or other surface. The handheld sensor device is being used to scan the wall to determine the existence of hidden object beneath the surface. The handheld sensor device may project information various detected features. Such features may include whether the device is over an object (such as a stud), at an edge of the object, or at the center of the object, whether the object is metal, and whether the device is over electrically hot AC wires, etc. Additionally, the device may display a direction to the hidden object. Furthermore, different colors may be projected to help convey changing information to the user. Embodiments project this information using one or more static and/or dynamic apertures. 
     In general, a conventional handheld sensor device uses visual and audio feedback emanating from device to tell a user of the device that it has detected a stud or other hidden object. Typically, a handheld sensor device includes one or more LEDs and/or an LCD display to visually show the existence of a stud detected behind a wall or other surface. In some devices, a single line or a plurality of lines, and may be projected in one or more directions. Therefore, what is desired is a way to improve how information is presented to the user. 
     SUMMARY 
     Some embodiments of the present invention provide for a handheld sensor device to project a visual indicator against a surface, the device comprising: a sensor to sense an object behind the surface and to provide a data signal; a controller coupled the sensor to receive the data signal, the controller configured to activate a first icon based on the data signal and to provide a control signal, wherein the first icon comprises a distinct two-dimensional icon; and a light source coupled to controller to receive the control signal and to project the first icon against the surface, the light source comprising a light emitting source; and an aperture defined to project light from the light emitting source as the first icon. 
     Some embodiments of the present invention provide for a method to project a visual indicator against a surface using a handheld sensor device, the method comprising: sensing an object behind the surface; determining a first feature of the sensed object; and projecting, from a light emitting source and through an aperture shaped to project light as a first icon onto the surface, a first icon indicating the first feature, wherein the first icon comprises a distinct two-dimensional icon. 
     Some embodiments of the present invention provide for a handheld sensor device to project a visual indicator against a surface, the device comprising: means for sensing an object behind the surface; means for determining a first feature of the sensed object; and means for projecting, from a light emitting source and through an aperture shaped to project light as a first icon onto the surface, a first icon indicating the first feature. 
     Some embodiments of the present invention provide for a method for detecting an object behind a surface using a handheld sensor device, the method comprising: sensing a first feature of the object; selecting a first icon, from a plurality of icons, based on sensing the first feature, wherein the first icon comprises a distinct two-dimensional icon; projecting the first icon against the surface in response to being selected; sensing a second feature of the object; selecting a second icon, from the plurality of icons, based on sensing the second feature, wherein the second icon comprises a distinct two-dimensional icon; and projecting the second icon against the surface in response to selecting the second icon. 
     These and other aspects, features and advantages of the invention will be apparent from reference to the embodiments described hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will be described, by way of example only, with reference to the drawings. 
         FIG. 1  illustrates a typical application in which a user holds a handheld sensor device against wall or other surface. 
         FIGS. 2A and 2B  illustrate views of a handheld sensor in operation, in accordance with embodiments of the present invention. 
         FIGS. 3A, 3B and 3C  show perspective views of a housing and a projected arrow, in accordance with embodiments of the present invention. 
         FIGS. 4, 5, 6, 7A and 7B  shows a relationship between an LED, an aperture and a projected arrow, in accordance with embodiments of the present invention. 
         FIG. 8  shows method of projecting a visual indicator, in accordance with embodiments of the present invention. 
         FIGS. 9A, 9B, 9C, 9D and 9E  show various projected arrows, in accordance with embodiments of the present invention. 
         FIGS. 10A, 10B, 10C, 10D and 11  show top-down views of a handheld sensor device projecting display information, in accordance with embodiments of the present invention. 
         FIGS. 12A, 12B, 12C, 12D and 13  show various display information, in accordance with embodiments of the present invention. 
         FIG. 14  shows a dynamic light source, in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, reference is made to the accompanying drawings, which illustrate several embodiments of the present invention. It is understood that other embodiments may be utilized and mechanical, compositional, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present disclosure. The following detailed description is not to be taken in a limiting sense. Furthermore, some portions of the detailed description that follows are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits that can be performed in electronic circuitry or on computer memory. A procedure, computer executed step, logic block, process, etc., are here conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those utilizing physical manipulations of physical quantities. These quantities can take the form of electrical, magnetic, or radio signals capable of being stored, transferred, combined, compared, and otherwise manipulated in electronic circuitry or in a computer system. These signals may be referred to at times as bits, values, elements, symbols, characters, terms, numbers, or the like. Each step may be performed by hardware, software, firmware, or combinations thereof. 
     Embodiments of the present invention provide an improved optical light projection system able to project information through static or dynamic light patterns, such as icons, pixels, graphics and/or colors, to convey information to the user. Some embodiments include appropriate illuminators, apertures, and potentially lenses and computer-controlled apertures to create a dynamic information display projected onto the surface being scanned. 
     Typical, handheld sensor devices provide information to the user using display(s) mounted on the body of the device, and not on the surface being scanned. Embodiments of the present invention instead display user-interface information directly onto the surface being scanned so as to more intimately convey detected information to the user. Because projected light does not introduce any physical interference, a device that allows a user to super-impose marks (with pencil, tape, etc.) at precise locations on the wall as guided by the projected display improves the accuracy of such marks. These marks remain behind even after the unit is removed to aid the user in remembering where the hidden objects are located. 
     Some embodiments of the present invention project graphical information and characters on the working area of a surface when using a handheld sensor devices (e.g. stud sensor), or other portable tool. The handheld sensor device includes light source(s), aperture(s), and optional lenses to project this graphical information against the surface. 
     In accordance with some embodiments of the present invention, a static aperture is used to project an arrow icon or other fixed two-dimensional icon against a surface when a feature is detected by the device. The displayed icon is formed by LED light passing from a distance through a fixed-shaped aperture. Because the light is passed to the aperture from a distance (and not butted against the aperture), the projection is less susceptible to having indistinct side edges and misalignment. In accordance with other embodiments of the present invention, more complicated information may be projected and displayed via a dynamic aperture that changes during scanning to indicate the one or more detected features. The more complicated information may include one or more icons or other graphic as well as text. 
       FIGS. 2A and 2B  illustrate views of a handheld sensor device  10  in operation, in accordance with embodiments of the present invention. In  FIG. 2A , the handheld sensor device  10  is shown projecting a light stream  41  against a surface  30  resulting in a fixed two-dimensional icon  40  to reveal a feature of a hidden object, such as an edge  18  of a stud  14 . The device  10  includes a sensor  100 , a controller  110 , and a light source  120 . The sensor  100  senses the hidden object behind surface  30  and provides a data signal to the controller  110 . For example, the data signal may indicate the presence of an edge feature or a center feature of the hidden object. The sensor  100  may include one or more of a capacitive sensor, a stud sensor, an electrical field sensor, and a magnetic field sensor or the like. 
     Based on the data signal from the sensor  100 , the controller  110  activates a light source  120  to project a light stream  41 , which results a first icon  40  being displayed against the surface  30 . The light source  120  includes a light emitting source  121  and an aperture  50  (shown in figures described below) when combined operate to shape the projected light from the light emitting source  121  through the aperture  50  as an arrow or other two-dimensional icon against the surface  30 . 
     The light source  120  may be formed with one or more LEDs (examples below), a lamp, bulb, or the like. In some embodiments, the light source  120  may also project a second icon against the surface  30 . For example, the first icon created from a first static aperture may represent a center feature and the second icon created from a second static aperture may represent an edge feature of the hidden object. In some embodiments, the light source  120  projects a single color icon, while in other embodiments, the light source  120  may project a selected one of two or more different colored icons to represent a corresponding two or more different features. For example, one color may be used to indicate an edge feature while another color is used to indicate a center feature. Alternatively, a first color may indicate a shallow stud while a second color indicates a deep stud. Yet as another alternative, a red colored icon may be used to indicate an electrically hot AC circuit, a blue icon may be used to represent a non-electrical metal object, such as a pipe, and a green icon may be used to represent a stud. 
       FIG. 2B  shows a top-down view outlining a handheld sensor device  10  projecting fixed two-dimensional icon (arrow  40 ) onto a surface  30 . The device  10  is configured with a static aperture  50  that allows light to pass from the device  10 . The aperture  50  is formed such that passing light projects the arrow  40 . 
       FIGS. 3A, 3B and 3C  show perspective views of a housing and a projected arrow, in accordance with embodiments of the present invention. The housing of the handheld sensor device  10  includes a base housing  10 A ( FIG. 3B ) and top housing  10 B ( FIG. 3C ) and is shown combined into a single integrated housing ( FIG. 3A ). The base housing  10 A includes a notch  50 A, which appears as a wide-angled inverted ‘V’ positioned parallel to the surface  30 . The plane of the wide-angled inverted ‘V’ may be exactly parallel (0 degrees) or off-parallel (up to 30 degrees or more from parallel) to the surface  30 . The top housing  10 B also includes a notched  50 B, but appears as a narrow-angled inverted ‘V’ positioned perpendicular to the surface  30 . Again, the plane of the narrow-angled inverted ‘V’ may be exactly perpendicular (0 degrees) or off-perpendicular (up to 30 degrees or more from perpendicular) to the surface  30 . When positioned on top of one another, the two notches  50 A and  50 B define a static aperture  50 . Due to the inverted ‘V’ shapes from notches  50 A and  50 B positioned together, when the two housing sections  10 A and  10 B are combined the light passing from inside the device  10  through the defined aperture  50  results in an arrow  40  projected on the surface  30 . 
       FIGS. 4, 5, 6, 7A and 7B  shows a relationship between an LED, an aperture and a projected arrow, in accordance with embodiments of the present invention. In  FIG. 4 , the light source projects an arrow  40  in front of the device. The arrow  40  has a distinctive two-dimensional shape unlike a one-dimensional line of conventional devices. In conventional handheld sensor device, the LED butts up against the housing wall such that the greatest dimension of the aperture is greater than the distance between the LED and the housing wall. Embodiments of the present invention disclose a light emitting source (e.g., LED  121 ) distant from the aperture  50 . Distancing the LED  121  from the aperture enables the handheld sensor device  10  to define a distinct and fixed two-dimensional icon (e.g., arrow  40 ) against the surface  30 . 
     In  FIG. 5 , an LED  121  is used as the light emitting source. The LED  121  is positioned distant from the aperture  50 . The greatest perpendicular dimension of the aperture  50  defines a distance D 1 . For example, assume the height of the aperture  50  provides the largest lateral opening. The LED  121  is positioned internally within the device  10  at a distance D 2  from the aperture  50 , where D 2  is greater than D 1  (D 2 &gt;D 1 ). In some embodiments, the ratio of D 2  and D 1  are such that D 2 :D 1 =2:1. In other embodiments, the ratio D 2 :D 2  is approximately 3:1, 4:1, 5:1, or greater than 5:1. For example, the greatest dimension of the aperture (D 1 ) may be 2 mm and the distance (D 2 ) between the aperture and the LED may be 9 mm, such that the ratio D 2 :D 1  is 4.5:1.  FIG. 6  shows a view up into the aperture  50  from a perspective near the surface  30  and near the projected arrow  40 . From this perspective, the aperture  50  appears more as an arrow. 
     In  FIGS. 7A and 7B , the handheld sensor device  10  is shown with a base housing  10 A and a top housing  10 B. The base housing  10 A has a wide V-shaped notch  50 A oriented perpendicularly or nearly perpendicular to the surface  30 . The top housing  10 B defines a trapezoid notch  50 B with a narrow top edge parallel to both the surface and to an imaginary similar-length or wider bottom line and also defines two side edges parallel or nearly parallel to one another. The distance D 2  between the aperture  50  and the light emitting source  121  is approximately 2 to 5 (or 5 to 30 or more) times farther than the distance D 1  of the aperture. Here, the ratio D 2 :D 1  is shown to be approximately 20:1. Channeling the light from the light emitting source  121  to the aperture  50  allows for this ratio to be larger and more efficient. 
       FIG. 8  shows method of projecting a visual indicator, in accordance with embodiments of the present invention. The method, using a handheld sensor device  10 , begins at block  200  by sensing a stud  14  behind a surface  30 . At  210 , the device  10  determines a first feature of the sensed stud  14 . At  220 , the device  10  projects, through an aperture  50  shaped to project light as an arrow  40  or other distinct two-dimensional icon onto the surface  30 , a first icon indicating the first feature. At  230 , the device  10  determines a second feature of the sensed object exists behind the surface  30 . At  240 , the device projects, through an aperture  50 , a second icon indicating the second feature. The aperture of steps  220  and  240  may be different static apertures, the same static aperture, or a common dynamic aperture. For example, the stud  14  may be a stud and the first feature may be an edge  18  or  22  of the stud, and the second feature may be a centerline  20  of the stud  14 . The first and second projected icons may be identical, have different colors and/or different shapes or orientations. At  250 , the device detects absence of the feature and disables projection. 
       FIGS. 9A, 9B, 9C, 9D and 9E  show various projected arrows, in accordance with embodiments of the present invention. Each arrow comprises a distinct two-dimensional icon, is formed by passing light at a distance D 2  from an aperture  50 , and includes a distinctive head and may also include a tail or shaft.  FIG. 9A  shows a traditional arrowhead and shaft  40 A with a straight-lined head backing. In  FIG. 9B , the arrowhead  40 B similar to the arrow  40 A but is void of a shaft. In  FIG. 9C , the arrowhead and shaft  40 C includes an arrowhead with V-lined head backing. In  FIG. 9D , the arrowhead  40 D is double-headed. In  FIG. 9E , the arrowhead and shaft  40 E is elongated. Unlike a projected line, each arrow has characteristics in two dimensions and is used to distinctly point to a location on a surface  30 . 
     Several of the embodiments described above included a passive aperture  50  in which light passes through a preformed and fixed aperture  50  to form a distinct two-dimensional icon, such as an arrow, on the surface  30 . Similarly, a handheld sensor device  10  may include a plurality of passive apertures  50  each channeling light from a separate LED or other light source. Each aperture may be shaped and position to form a separate icon. For example, a first aperture  50  may be formed to present an arrow  40 A. To project the arrow from the first aperture  50 , a first LED may be illuminated. A second aperture  50  may be formed to present an arrow pointing to the left indicating an object is to the left of the device  10 . To project the left-pointing arrow from the second aperture  50 , a second LED may be illuminated channeling light just to the second aperture  50 . A third aperture  50  may be formed to present an arrow pointing to the right to indicate an object is to the right of the device  10 . Similarly, to project the right-pointing arrow from the third aperture  50 , a third LED may be illuminated channeling light just to the third aperture  50 . Separate channels may be formed with individual clear material, such as plastic tubes, or may be formed by physically dividing an open space with the device  10 . 
     In other embodiments, the aperture  50  is dynamic. That is, light passing through the aperture is actively regulated such that a variety of icons or other information may be projected onto the surface  30 . Light may be regulated through an LCD lens, through an active shutter, or the like. Examples of devices  10  using a dynamic aperture  50  are given below. 
       FIGS. 10A, 10B, 10C, 10D and 11  show top-down views of a handheld sensor device  10  projecting display information, in accordance with embodiments of the present invention. In  FIG. 10A , a handheld sensor device  10  includes a dynamic aperture  50 , which allows light to pass to form a display area  40  on the surface  30 . The device  10  projects one or more distinct two-dimensional icon within this display area  40 . Several of possible icons are described below by way of example. 
     In  FIG. 10B , a user operates a handheld sensor device  10  searching for a hidden stud  14 . The device  10  detects an edge  18  to the left of the sensor but it not yet over the edge  18 . Conventional devices provide an indication showing a hidden stud is close but does not indicate which direction the user should move the device. Using a device  10  with directivity sensing, the device  10  may determine a direction of the hidden object. The handheld sensor device  10  projects an arrow  40 F indicating to the user that the hidden object is to the left. Simultaneously, the device  10  may provide similar information on a display  16 . 
     In  FIG. 10C , the user has moved the device  10  over an edge  18  of the stud  14 . Once the device  10  has detected the edge  18 , it projects an icon to the surface  30 . For example as shown, the device  10  projects both the letter “EDGE” and an arrow  40 G. In some embodiments, the icon is projected at a fixed location relative to the device  10 . In other embodiments, the icon may appear stationary relative to the surface  30  but moves relative to the device  10  while the user moves the device  10  to the left and right over the edge. 
     In  FIG. 10D , the handheld sensor device  10  is nearly centered over the stud. The device  10  then projects a center icon “CNTR” with an arrow  40 H to indicate the device  10  is over a center feature of the stud  14 . Again, the device  10  may track the relative position of the feature and adjust its projected icon to appear stationary on the surface as the user moves the device about the centerline of the stud  14 . 
     In  FIG. 11 , the device  10  projects to the surface  30  the word “CENTER” along with a bar. The bar represents the hidden stud  14  and the word “CENTER” represents that the device  10  is centered over the stud  14 . Other projections are possible with a handheld sensor device  10  that has a dynamic aperture. 
       FIGS. 12A, 12B, 12C, 12D and 13  show various display information, in accordance with embodiments of the present invention.  FIG. 12A  shows a display area  40  that indicates the device  10  is near an edge of the stud  14 . In  FIG. 12B , the user has moved the device to the left such that it is centered over an edge as indicated by the word “EDGE”, by the left-pointing arrow and by the shadowed area to the left side of the display area  40 . In  FIG. 12C , the user has centered the device  10  directly above the centerline of the stud  14 . The projected display area  40  shows a shadowed area representing the hidden stud and also the word “CNTR” or “CENTER” to highlight to the user that the device  10  is centered over the stud  14 .  FIG. 12D  shows the device  10  moved to the left so that it is centered over another edge. The display  40  shows approximately a mirrored images to that shown in  FIG. 12B . 
     The shadowed area may be animated such that is appears relatively stationary against the surface  30  to simulate a view of the stud  14  looking through the surface  30 . The pixilated characters making up the words “CENTER”, “CNTR” or “EDGE” are examples of dynamic text that the handheld sensor device  10  projects depending on the circumstances and context of use for the device  10  at that instant in time. The content and specifics of the displayed information is determined by a computer, microprocessor or micro controller controlling the device  10 . The displayed information also depends on what the device  10  is sensing. Each icon described above (e.g., arrows shown in  FIGS. 12B and 12D ) convey information (e.g., directional information) with a single icon. Each icon may be static or dynamical and is turned on or off by the device  10 . 
     The projected information depends on what information the handheld sensor device  10  has measured and needs to display to the user. It may include characters, graphics, and icons in various colors to convey user-interface information to the user of the device  10 . Some embodiments display the projected information via an LCD aperture or other dynamic aperture within the device  10 . The LCD aperture may be a transmissive, negative type, in which the pixels that are transparent will be projected. All other pixels are non-transparent, thus block the light. The displayed icon may be colored by being projected: (1) from a colored LED, (2) through a colored lens (e.g., at or near the aperture), or (3) through a colored LCD. In some embodiments, graphics on the LCD object are pre-distorted (to compensate for tilt and projection angles), and passed through appropriate lenses, so that they appear not to be distorted and correct when projected to the surface. In other words, the image on the LCD object is distorted such that the projection on the surface  30  is not distorted. Control of the information being displayed is managed by the microcontroller or the like, which updates and changes the information dynamically and in real time depending on the current sensor measurements and operating mode. 
       FIG. 13  shows additional possible displayed information. Icon (A) shows a projection of an example initialization information. Icon (B) shows a projection of information telling a user that the device  10  is in a stud scan mode. Icon (C) shows a projection of information telling a user that the device  10  found a center of a stud  14  (similar to  FIGS. 10C, 11 and 12C ). Icon (D) shows a projection of information telling a user that the device  10  found an edge of a stud  14  (similar to  FIG. 10B ). Icon (E) shows a projection of information telling a user that the device  10  move back towards a stud  14  (similar to  FIG. 10A ). Icon (F) shows a projection of instructions to a user to begin scanning Icons (G 1 ) through (G 9 ) show a progression of projections as a device  10  passes over a stud  14  (shown with black pixels) from right to left. 
       FIG. 14  shows a dynamic light source  120 , in accordance with embodiments of the present invention. The light source  120 , also referred to as a display projection system, includes a light emitting source  121 , such as an LED, which projects light along a projection path  300 . A condensing lens  310  focuses this light into a dynamic aperture  50 , such an LCD panel. When the dynamic aperture  50  is solid black or opaque, light does not pass through. When projecting and image, the dynamic aperture  50  displays a negative of an image to project. That is, the dynamic aperture  50  is non-transparent for areas not representing the icon to be displayed. Light passing through the dynamic aperture  50  is filtered by this negative image. The light then passes a projection lens  320  and a prism  330 . From the prism  330 , the projected light  41  provides a visual indication against the surface  30  as icon  40 . 
     Other active projection systems may be used. For example, the LCD panel may contain color LCDs thereby allowing colored icons and text. The LCD panel may allow for partially translucent pixels thus allowing grayscale icons and text. 
     Therefore, it should be understood that the invention can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is not intended to be exhaustive or to limit the invention to the precise form disclosed. It should be understood that the invention can be practiced with modification and alteration.