Wall scanner

Embodiments of the invention relate to a wall scanner that includes a housing, a plurality of sensors, a display, and a control section. The housing includes a handle portion and a body portion. The handle portion is adapted to receive a removable and rechargeable battery pack such as a high-voltage lithium-ion (“Li-Ion”) battery pack. The body portion of the housing encloses the plurality of sensing devices, such as, for example, capacitive plate sensors for sensing the presence of a stud behind a surface, a D-coil sensor for identifying the presence of metal behind the surface, and a non-contact voltage sensor for detecting the presence of live wires carrying AC currents. The display is configured to display, among other things, the location of an object behind the surface in real-time, the depth of an object behind the surface, and whether an object behind the surface is ferrous or non-ferrous. The control section includes a plurality of actuation devices for controlling the functions and operations of the wall scanner, such as the scanning mode.

BACKGROUND

Embodiments of the invention relate to wall sensors. Wall sensors include the capability of detecting, for example, wooden or metal studs hidden behind a surface. In some instances, wall sensors include one or more plate sensors or high frequency transmitters for determining whether an object is hidden behind a surface. Wall sensors also include an indicating device or multiple indicating devices for alerting a user to the presence of an object that is hidden behind a surface. Indicating devices can include visual indicators such as light emitting diodes (“LEDs”), audible indicators such as a small speaker, or a combination thereof.

SUMMARY

Embodiments of the invention include a wall sensor or wall scanner that is capable of providing a plurality of wall scanning technologies and a high-resolution display in a single hand-held device. Embodiments also include a wall scanner that is ergonomically designed to provide a comfortable and easy-to-grip handle portion, a control section accessible with a single hand while that hand grips the handle portion, and a display that is not obstructed by a user's hand during normal operation of the wall scanner.

In one embodiment, the invention provides a wall scanner that includes a housing, a plurality of sensors, a display, a control section, and a plurality of wheels. The housing includes a handle portion and a body portion. The handle portion is adapted to receive a high-voltage removable and rechargeable battery pack, such as a lithium-ion (“Li-Ion”) battery pack (e.g., a 12V Li-Ion battery pack). The body portion of the housing encloses the plurality of sensors, such as, for example, capacitive plate sensors for sensing the presence of a stud behind a surface, a D-coil sensor for identifying the presence of metal behind the surface, and a non-contact voltage sensor for detecting the presence of live wires carrying AC currents behind the surface. The display is, for example, a negative LCD (“NLCD”), and is configured to display a plurality of status indications related to the operation of the wall scanner. For example, the display can display, among other things, the operational mode of the wall scanner, the location of an object behind the surface in real-time, the depth of an object behind the surface, and whether an object behind the surface is ferrous or non-ferrous. The control section includes a plurality of actuation devices for controlling the functions and operations of the wall scanner, such as the scanning mode. The plurality of wheels allow the wall scanner to roll along the surface in a linear manner.

In one embodiment, the invention provides a wall scanner for sensing objects behind a surface. The wall scanner includes a housing having a body portion and a handle portion, a first sensor, a second sensor, and a non-contact voltage sensor. The handle portion forms a first axis and includes a first recess. The first recess is operable to receive a removable battery pack along the first axis. The first sensor is of a first sensor type and senses a first object of a first object type behind the surface. The second sensor is of a second sensor type and senses a second object of a second object type behind the surface. The first sensor type is different than the second sensor type, and the first object type is different than the second object type. The non-contact voltage sensor is operable to detect a medium carrying an alternating current behind the surface, and the display is configured to display a plurality of indications to a user. The indications include at least an indication of a depth of the second object behind the surface and a graphical representation of the location of the first object behind the surface.

In another embodiment, the invention provides a method for operating a wall scanner that includes a handle portion. The method includes inserting a removable battery pack into a receiving chamber of the handle portion, sensing a first object of a first object type behind a surface using a first sensor of a first sensor type, and sensing a second object of a second object type behind the surface using a second sensor of a second sensor type. The first sensor type is different than the second sensor type, and the first object type is different than the second object type. The method also includes detecting, using a non-contact voltage sensor, a medium carrying an alternating current behind the surface, and displaying, on a display, a plurality of indications to a user. The indications include at least an indication of a depth of the second object behind the surface and a graphical representation of the location of the first object behind the surface.

DETAILED DESCRIPTION

Various embodiments herein describe a wall scanner that is capable of detecting a plurality of objects hidden behind a plurality of different surfaces. The wall scanner includes a housing, a plurality of sensors, a display, a control section, and a plurality of wheels. The housing includes a handle portion and a body portion. The handle portion includes a recess that is adapted to receive a high-voltage removable and rechargeable battery pack.

As a result of receiving operational power from the high-voltage removable and rechargeable battery pack, the wall scanner is capable of including a variety of additional features or functions that demand increased power. For example, the wall scanner can include a high-intensity LED flashlight, a backlighted control section or actuators, a high-resolution LCD, a color LCD, and/or an additional or remote display. Conventionally powered wall scanners (e.g., wall scanners powered by alkaline batteries) are unable to provide the required voltage and current to power these additional features, or the operational runtime (i.e., the amount of time for which the batteries can power the wall scanner before the batteries need to be replaced or recharged) of the alkaline batteries is shortened. In contrast, the high-voltage removable and rechargeable battery pack of a wall scanner according to embodiments of the invention is capable of powering both the additional features of the wall scanner and the described sensing and display features, while maintaining an operational runtime that is comparable to or longer than a conventional wall scanner that does not include additional features.

FIGS. 1-4illustrate the wall scanner5and housing10according to an embodiment of the invention. A handle portion15of the wall scanner housing10includes a battery pack recess20(seeFIG. 5) adapted to receive a high-voltage removable and rechargeable battery pack25. The battery pack recess20includes a plurality of terminals (shown as145inFIG. 7) for electrically connecting the battery pack25to the wall scanner5. Additionally, the handle portion15includes a plurality of recessed gripping portions35that provide additional grip to a user.

The handle portion15and the battery pack25define a first axis41of the wall scanner5. The handle portion15is coupled to and extends from the body portion40of the wall scanner5such that a recess45is formed between the body portion40and the handle portion15. The extension of the handle portion15from the body portion40allows the wall scanner5to receive the battery pack25. In some embodiments, the recess45between the handle portion15and the body portion40is closed by first and second connecting portions50and55. In other embodiments, the recess45is open and includes a single connecting portion. The recess45defines a space for accommodating the fingers of a user while the user is holding the wall scanner5.

The handle portion15extends approximately half the length of the housing10and is approximately parallel to the body portion40and a display60. In one embodiment, the first axis41is parallel to a second axis43which extends through a center of the body portion40. In other embodiments, the first axis41is not parallel to the second axis43, and the first axis41intersects the second axis43at a point a distance, d, away from the wall scanner5. The display60is positioned on the body portion40such that the display60is not blocked by the user's hand when the wall scanner5is being gripped. The control section65is provided on the first connecting portion50between the body portion40and the handle portion15of the wall scanner5. The control section65is positioned at an oblique angle with respect to the body portion40of the housing such that the buttons or switches (described below) within the control section65can be activated by the user using the same hand with which the user is gripping the wall scanner5. In some embodiments, the wall scanner5also includes one or more LEDs for providing an indication to the user of the status of the wall scanner5, the battery pack25, or both. The wheels70are rotatably coupled to the housing10to facilitate movement of the wall scanner5along a surface. In the illustrated embodiment, the wheels70are idle wheels, but may alternatively be driven wheels that are powered by the battery pack25.

FIG. 5illustrates an exploded view of the wall scanner5shown inFIGS. 1-4. The wall scanner5includes a base housing assembly100, right and left housing assemblies105and110, a panel assembly115, and the battery pack25. An exploded view of the base housing assembly100is shown inFIG. 6. The base housing assembly100includes a main printed circuit board assembly (“PCB”)120, a sensor board125which includes plate sensors for sensing studs, a D-coil sensor130for sensing metal, a base135, and the wheels70. An exploded view of the right housing assembly105is shown inFIG. 7. The left housing assembly110is similar to the right housing assembly105and is not described in detail. The right housing assembly105includes contact plate terminals145, a battery contact PCB150, a right half of the housing155, an indicator lens160, and an LED165. An exploded view of the panel assembly115is shown inFIG. 8. The panel assembly115includes a keypad170, a key holder175, a rubber key180, a light guide185, a key PCB190, a key panel195, an LCD lens200, and an LCD assembly205.

FIGS. 9, 10, and 11illustrate the battery pack25for use with the wall scanner5. In the illustrated embodiment, the battery pack25includes battery cells having a lithium-based chemistry such that the battery pack25is over 65% lighter and 50% smaller than an equivalent nickel-cadmium (“NiCd”) battery pack. The lithium-ion battery pack25also provides a longer operational run-time for the wall scanner5, and a longer life (e.g., number of recharge cycles) than other non-lithium based battery packs.

The illustrated battery pack25includes a casing300, an outer housing305coupled to the casing300, and a plurality of battery cells310(shown inFIG. 10) positioned within the casing300. The casing300is shaped and sized to fit within the recess20in the wall scanner5to connect the battery pack25to the wall scanner5. The casing300includes an end cap315to substantially enclose the battery cells310within the casing300. The illustrated end cap315includes two power terminals320configured to mate with corresponding power terminals145of the wall scanner5. In other embodiments, the end cap315may include terminals that extend from the battery pack25and are configured to be received in receptacles supported by the wall scanner5. The end cap315also includes sense or communication terminals325(shown inFIG. 11) that are configured to mate with corresponding terminals of the wall scanner5. The terminals325couple to a battery circuit (not shown). The battery circuit can be configured to monitor various aspects of the battery pack25, such as pack temperature, pack and/or cell state of charge, etc. and can also be configured to send and/or receive information and/or commands to and/or from the wall scanner. In one embodiment, the battery circuit operates as illustrated and described in U.S. Pat. No. 7,157,882 entitled “METHOD AND SYSTEM FOR BATTERY PROTECTION EMPLOYING A SELECTIVELY-ACTUATED SWITCH,” issued Jan. 2, 2007, the entire contents of which are hereby incorporated by reference. In another embodiment, the battery circuit operates as illustrated and described in U.S. Patent Publication No. 2006/0091858 entitled “METHOD AND SYSTEM FOR BATTERY PROTECTION,” filed May 24, 2005, the entire contents of which are also hereby incorporated by reference.

The casing300and power terminals320substantially enclose and cover the terminals145of the wall scanner5when the pack25is positioned in the recess20. That is, the battery pack25functions as a cover for the recess20and terminals145of the wall scanner5. Once the battery pack25is disconnected from the wall scanner5and the casing is removed from the recess20, the battery terminals145on the wall scanner are generally exposed to the surrounding environment.

The outer housing305is coupled to an end of the casing substantially opposite the end cap315and surrounds a portion of the casing300. In the illustrated construction, when the casing300is inserted into or positioned within the corresponding recess20in the wall scanner5, the outer housing305generally aligns with an outer surface of the wall scanner5. In this construction, the outer housing305is designed to substantially follow the contours of the wall scanner5to match the general shape of the housing10. In such embodiments, the outer housing305generally increases (e.g., extends) the length of the handle portion15of the wall scanner5.

In the illustrated embodiment, two actuators330(only one of which is shown) and two tabs335are formed in the outer housing305of the battery pack25. The actuators300and the tabs335define a coupling mechanism for releasably securing the battery pack25to the wall scanner5. Each tab335engages a corresponding recess formed in the wall scanner5to secure the battery pack25in place. The tabs335are normally biased away from the casing300(i.e., away from each other) due to the resiliency of the material forming the outer housing305. Actuating (e.g., depressing) the actuators330moves the tabs335toward the casing300(i.e., toward each other) and out of engagement with the recesses such that the battery pack25may be pulled out of the recess20and away from the wall scanner5. Such an arrangement allows a user to quickly remove the battery pack25from the wall scanner5for recharging or replacement without the use of tools. In other embodiments, the battery pack25may include other suitable coupling mechanisms to releasably secure the battery pack25to the wall scanner5, as discussed below.

As shown inFIG. 10, the battery pack25includes three battery cells310positioned within the casing300and electrically coupled to the terminals320. The battery cells310provide operational power (e.g., DC power) to the wall scanner5. In the illustrated embodiment, the battery cells310are arranged in series, and each battery cell310has a nominal voltage of approximately four-volts (“4.0V”), such that the battery pack25has a nominal voltage of approximately twelve-volts (“12V”). The cells310also have a capacity rating of approximately 1.4 Ah. In other embodiments, the battery pack25may include more or fewer battery cells310, and the cells310can be arranged in series, parallel, or a serial and parallel combination. For example, the pack25can include a total of six battery cells310in a parallel arrangement of two sets of three series-connected cells. The series-parallel combination of battery cells310creates a battery pack25having a nominal voltage of approximately 12V and a capacity rating of approximately 2.8 Ah. In other embodiments, the battery cells310may have different nominal voltages, such as, for example, 3.6V, 3.8V, 4.2V, etc., and/or may have different capacity ratings, such as, for example, 1.2 Ah, 1.3 Ah, 2.0 Ah, 2.4 Ah, 2.6 Ah, 3.0 Ah, etc. In other embodiments, the battery pack25can have a different nominal voltage, such as, for example, 10.8V, 14.4V, etc. In the illustrated embodiment, the battery cells310are lithium-ion battery cells having a chemistry of, for example, lithium-cobalt (“Li—Co”), lithium-manganese (“Li—Mn”), or Li—Mn spinel. In other embodiments, the battery cells310may have other suitable lithium or lithium-based chemistries.

FIG. 12is a block diagram of a wall scanner5according to an embodiment of the invention. The wall scanner5includes a main system module400, the stud sensor125, the D-coil sensor130, and the display60. The main system module400includes, among other things, a wall scanner controller420, a signal conditioning module425, a peak detection module430, and an analog-to-digital conversion module435. The display60is, for example, a 128×64 dot matrix liquid crystal display (“LCD”) or negative LCD (“NLCD”). The wall scanner controller420includes, for example, a PCB such as PCB120shown inFIG. 6. The PCB120is populated with a plurality of electrical and electronic components which provide operational control and protection to the wall scanner5. In some embodiments, the PCB120includes a control or processing unit such as a microprocessor, a microcontroller, or the like. In some embodiments, the controller420includes, for example, the processing unit, a memory, and a bus. The bus connects various components of the controller420including the memory to the processing unit. The memory includes, in many instances, read only memory (“ROM”) and random access memory (“RAM”). The controller420also includes an input/output system that includes routines for transferring information between components within the controller420. Software included in the implementation of the wall scanner5is stored in the ROM or RAM of the controller420. The software includes, for example, firmware applications and other executable instructions. In other embodiments, the controller420can include additional, fewer, or different components.

The PCB120also includes, for example, a plurality of additional passive and active components such as resistors, capacitors, inductors, integrated circuits, and amplifiers. These components are arranged and connected to provide a plurality of electrical functions to the PCB120including, among other things, filtering, signal conditioning, and voltage regulation. For descriptive purposes, the PCB120and the electrical components populated on the PCB120are collectively referred to herein as “the controller”420. The controller420receives signals from the sensors within the wall scanner, conditions and processes the signals, and transmits processed and conditioned signals to the display60. The display60receives the processed and conditioned signals and displays an indication of a sensed characteristic of an object hidden behind a surface. The signal conditioning module425provides signals to and receives signals from the stud sensor125, as described below; the peak detection module430receives signals from and sends signals to the D-coil sensor130, as described below; and the analog-to-digital conversion module435provides the conversion necessary for the controller420to interpret analog signals from the D-coil sensor130.

In some embodiments, a battery pack controller (not shown) can provide information to the wall scanner controller420related to a battery pack temperature or voltage level. The wall scanner controller420and the battery pack controller also include low voltage monitors and state-of-charge monitors. The monitors are used by the wall scanner controller420or the battery pack controller to determine whether the battery pack25is experiencing a low voltage condition which may prevent proper operation of the wall scanner5, or if the battery pack25is in a state-of-charge that makes the battery pack25susceptible to being damaged. If such a low voltage condition or state-of-charge exists, the wall scanner5is shut down or the battery pack25is otherwise prevented from further discharging current to prevent the battery pack25from becoming further depleted.

The wall scanner5is operable to detect the presence of a stud, such as a wood stud or metal joists within residential, commercial, and industrial structures using the stud sensor125. The wooden studs or metal joists can be detected when hidden behind surfaces composed of, for example, plaster, non-metallic wall materials, wooden panels, wall board, and the like. The stud sensor125includes a sensor circuit with a pair of sensors. Each sensor includes a coplanar primary plate440A with a single side coplanar plate440B arranged between the primary plates. The presence and location of the stud is then determined in a manner similar to that described in U.S. Patent Application Publication No. 2008/0238403, titled “STUD SENSOR,” the entire contents of which are hereby incorporated by reference.

The wall scanner5is also configured to operate in a metal scanning mode. The metal scanning mode is operable to detect both ferrous (i.e., iron based) and non-ferrous (e.g., copper) metals within residential, commercial, and industrial structures. While in the metal scanning mode, the wall scanner5can detect metal (e.g., rebar, metal conduit, copper piping, etc.) behind surfaces composed of wall board, tile, plaster, brick, or the like. The wall scanner5can also detect metal within walls composed of concrete, masonry, wood, brick, or the like. In some embodiments, the wall scanner5is operable to sense metal to a depth of, for example, six inches.

The D-coil sensor130illustrated inFIG. 6uses an inductively coupled sensor that includes overlapping D-shaped transmitter and receiver coils445A and445B. When the D-coil sensor130detects a metallic object, the sensor130outputs a signal to the controller420indicating the location of the object. The wall scanner5detects the presence of metal in a manner similar to that described in U.S. Patent Application Publication No. 2008/0272761, titled “DEVICE AND METHOD OF DETECTING FERRITE AND NON-FERRITE OBJECTS,” the entire contents of which are hereby incorporated by reference.

The wall scanner5is also configured to detect the presence of “live” (i.e., energized) electrical wiring behind a surface. In some embodiments, the wall scanner5includes an AC detection circuit such as that described in U.S. Pat. No. 6,894,508, titled “APPARATUS AND METHOD FOR LOCATING OBJECTS BEHIND A WALL LINING,” the entire contents of which are hereby incorporated by reference. In other embodiments, the wall scanner5includes a detachable non-contact voltage detector (not shown), such as that described in co-pending U.S. patent application Ser. No. 12/421,187, filed on Apr. 9, 2009 and titled “SLIDABLY ATTACHABLE NON-CONTACT VOLTAGE DETECTOR,” the entire contents of which are hereby incorporated by reference, which is slidably attachable to the housing10of the wall scanner5. The wall scanner5includes the LED165for indicating the detection of an AC voltage. The LED165can be located at a first end of the wall scanner5, such as the end opposite the battery pack25(as shown inFIG. 7), on the display60, or both. The wall scanner5is operable to sense the presence of AC voltages regardless of the operational mode of the wall scanner5(e.g., metal sensing mode or stud sensing mode), and the wall scanner5does not need to be calibrated to detect the presence of AC voltages.

FIG. 13illustrates the control section65of the wall scanner5. The control section65is positioned between the display60and the handle portion15along the first axis41. The control section65includes buttons, switches, or other actuation devices for controlling the function and operation of the wall scanner5. In some embodiments, the control section65includes a metal sensing mode button500, a stud sensing mode button505, a menu button510, a power button515, and a calibration button520. In other embodiments, the control section65includes additional buttons or switches for controlling additional or different features or functions of the wall scanner5. One or more of the buttons included in the control section65may have multiple functions such as selecting an operational mode and enabling a user to scroll through menu options on the display60. In the illustrated embodiment of the control section65, the buttons are arranged in a circular manner. In other embodiments, the buttons in the control section65can be arranged in a variety of different configurations, such as a grid or an array. In various embodiments of the control section65, the buttons are configured such that a user can access and select each button using a single hand (e.g., the same hand the user is using to grip the handle portion of the wall scanner).

The display60is symmetrically aligned along the first axis41defined by the handle portion15and the battery pack25. The display60is configured to display a plurality of status indications related to the operation of the wall scanner5. For example, the display60can display, among other things, the operational mode of the wall scanner5, the location of an object hidden behind the surface in real-time, the depth of an object hidden behind the surface, whether an object hidden behind the surface is ferrous or non-ferrous, battery pack power level, and an indication of whether sound (i.e., audible indication) is turned on or off.FIGS. 14-16illustrate embodiments of wall scanner status indications that the display60is configured to display.

The controller420receives signals from the sensors, processes or conditions the signals, and transmits the conditioned signals to the display60, as described above. The display60receives the conditioned signals and displays an image, a value (e.g., a distance, coordinates, etc.), an alert relating to the detected object, test results, measurement values, properties of the wall scanner, etc. The display60includes lighted symbols, such as white alphanumeric symbols, on a black background. The display60improves the visibility of the display in low or poor lighting conditions, such as outdoor, dark, or dirty conditions. Additionally or alternatively, the wall scanner5can include a remote display (not shown) that can be attachable to or detachable from the wall scanner5to provide the user with a remote display of the detection and/or position of a stud, or the operation of the wall scanner5. The wall scanner5can include a transmitter and a receiver for communicating with the remote display. In some embodiments, the remote display is configured to display the same information as the display60.

The user can access a menu (screen600) on the display60by activating buttons in the control section65. From the menu, a list of options relating to various settings of the wall scanner5is displayed on the display60. The user is able to select between English and metric units for displaying the depth or location of an object (screen605). The user can also select whether sound is activated (screen610). When sound is activated, the wall scanner5produces, for example, a beep or a series of beeps to indicate the presence or depth of an object hidden behind a surface. In other embodiments, the menu is operable to control additional functions such as display screen brightness, turning a backlight on and off, controlling the operation of a remote display, and adjusting wall scanner sensitivities. As such, the wall scanner5is a menu-driven device.

The display60also provides instructions to the user for calibrating the wall scanner5after power-up. When the wall scanner5is operating in the stud sensing mode, the user is prompted to place the wall scanner5on the surface to be scanned and activate the calibration button520(screen615). The display60then indicates to the user that the wall scanner5is being calibrated (screen620). The user can, if desired, manually change the sensitivity (e.g., scan depth) of the wall scanner5. For example, in one embodiment, a default depth setting of 0.5 inches is set for the wall scanner5when in the stud sensing mode. To change the scanning depth, the user activates the calibration button520while the wall scanner5is calibrating. Activating the calibration button520a second time changes the scanning depth from 0.5 inches to 1.0 inches. Activating the calibration button520a third time changes the scanning depth from 1.0 inches to 1.5 inches. If the calibration button is activated a fourth time, the scanning depth cycles back to 0.5 in. In other embodiments, the wall scanner5is configured with different scanning depths and sensitivities. If an error occurs during calibration, the user is prompted with an error message, such as that shown in screen625.

After calibration, the display60indicates when the wall scanner5is scanning for a stud (screen630). The display60is configured to display the location of a detected stud in real-time as the wall scanner5is passing over the stud. For example, when the wall scanner5is moving from left to right across a surface and a stud is detected, the stud is identified by a partially illuminated portion of the display60(e.g., the stud is represented by a combination of illuminated pixels and non-illuminated pixels). The illuminated pixels form a plurality of lines such as horizontal lines, vertical lines, diagonal lines, or any combination thereof which are separated by non-illuminated pixels or lines. The display60also includes a visual and/or linguistic identification of the edge of the stud (e.g., an arrow and/or the word “edge” displayed on the wall scanner display), as shown in screen635. The display60can also display both edges of a stud if the width of the stud is not greater than the width of the display60. In such an instance, each edge is identified by an arrow and/or a linguistic identification, and the stud is represented by a combination of illuminated and non-illuminated portions (screen640). The wall scanner5includes similar visual representations of a stud's location in real-time when the wall scanner is moving from the right to the left (screen645).

When the wall scanner5is operating in the metal sensing mode, the user is prompted to hold the wall scanner5off of the surface to be scanned in order for the wall scanner5to be properly calibrated (screen650). Similar to the stud sensing mode, the wall scanner5provides an indication on the display that the wall scanner5is being calibrated (screen655). If an error occurs during calibration, the user is prompted with an error message, such as that shown in screen660. After calibration, the display60indicates when the wall scanner5is scanning for metal (screen665). If the wall scanner5detects the presence of metal, the user is prompted visually or audibly that metal has been detected (screen670). The display60then provides the user with an indication of whether the detected metal is ferrous or non-ferrous, a numerical indication of the depth of the detected object, and a visual indication of the depth of the object (screen675). In some embodiments of the invention, the display60can also provide a symbol to indicate the nearest distance to a detected metal object (screen680).

A process700for the general operation of the wall scanner5is illustrated inFIG. 17. After the wall scanner5is powered up (step705), the default sensing mode for the wall scanner5is the metal sensing mode. To use the wall scanner in the metal sensing mode, the user activates the calibration button520from the control section65(step710). If the wall scanner5calibrates successfully (step715), the wall scanner5is ready to detect metal objects hidden behind a surface (step720). If the wall scanner5does not calibrate correctly, a calibration error is displayed (step725), and the wall scanner5waits for a user to change sensing modes or activate the calibration button520again (step730). In some embodiments, if a user selects the stud sensing mode (step735), the wall scanner5calibrates automatically. In other embodiments, the user must activate the calibration button520. If the calibration is successful (step740), the wall scanner5is ready to detect studs hidden behind a surface (step745). If the calibration is not successful, a calibration error is displayed (step725), and the wall scanner5waits for the user to change sensing modes or activate the calibration button520again (step730). Following steps720and745, the wall scanner5also waits for the user to change sensing modes or recalibrate the wall scanner5(step730). Alternatively, the user can activate the menu button510from the control section65(step750) to set up wall scanner tools (step755) such as selecting display units and turning sound on and off. To exit the tools setup, the user activates the menu button510a second time (step760).

Thus, the invention provides, among other things, a wall scanner that includes a stud sensor, a metal sensor, an AC voltage sensor, a liquid crystal display, and an easy-to-grip handle portion that allows a user to manipulate and control the wall scanner using a single hand. The handle portion is operable to receive a high-voltage removable and rechargeable battery pack, such as a battery pack having a lithium-based chemistry. Various features and advantages of the invention are set forth in the following claims.