Abstract:
A videoscope includes a sensor end having an image detector and at least one sensor selected from the group consisting of an eddy current sensor, an ultrasonic sensor, or an array of such sensors, a handle; and an elongated arm that comprises a conduit that connects the sensor end to the handle. The conduit houses a link that transmits image information from the image detector through the conduit, and the conduit further houses at least first and second working channels that extend from the sensor end to the handle. Fluid injected at a handle end of the conduit passes through the first working channel, out the sensor end, and onto the surface under examination. The second working channel contains the eddy current or ultrasonic sensor and passes their signals through the conduit.

Description:
[0001]     The present application is a continuation-in-part of U.S. patent application Ser. No. 10/731,329, filed Dec. 9, 2003, entitled “Non-Medical Videoscope” (incorporated herein by reference), which claims the benefit of U.S. provisional application No. 60/496,438 (also incorporated herein by reference in its entirety). 
     
    
     FIELD OF THE INVENTION  
       [0002]     The field of the invention is videoscopes.  
       BACKGROUND OF THE INVENTION  
       [0003]     A videoscope has an image detecting element (a CCD, for example) at a distal end (the “sensor end”) of an elongated arm (rigid or flexible) wherein the arm is coupled to a handle and signals from the image detecting element are transmitted from the image detecting element and along the arm towards the handle by one or more electrical conductors. The signals are subsequently transmitted to a display, and an image generated from the signals is viewed by a videoscope operator. Videoscopes will typically also comprise one or more optical fibers extending along the arm between the handle and the sensor end. Such optical fibers are used to transmit light to the sensor end and to provide light for illuminating the field of view of the image detecting element.  
         [0004]     The principle of eddy current testing for cracks is that as a coil of wire is drawn across a crack, there is a differential current produced in the coil that is a measure of the crack size, as it interrupts the magnetic field produced by the coil. When an AC current flows in a coil in close proximity to a conducting surface the magnetic field of the coil will induce circulating (eddy) currents in that surface. The magnitude and phase of the eddy currents will affect the loading on the coil and thus its impedance. As an example, assume that there is a deep crack in the surface immediately underneath the coil. This will interrupt or reduce the eddy current flow, thus decreasing the loading on the coil and increasing its effective impedance. This is the basis of eddy current testing, by monitoring the voltage across the coil in such an arrangement changes in the material of interest may be detected.  
         [0005]     Geometry affects eddy current sensor performance, especially where the surface being investigated is not flat. Geometrical features such as curvature, edges, grooves etc. often exist on the surface of interest exist and will effect the eddy current response. Test techniques must recognize this, for example in testing an edge for cracks the probe will normally be moved along perpendicular to the edge so that small changes may be easily seen. Where the material thickness is less than the effective depth of penetration, this will also effect the eddy current response.  
         [0006]     Proximity between the eddy current sensor and the surface of interest is another factor that affects eddy current sensor performance. In particular, the occurrence of a “lift-off” signal as the probe is moved on and off the surface and the reduction in sensitivity that occurs as the coil to product spacing increases, both negatively affect the performance of the eddy current sensor.  
         [0007]     When attempting to use a conventional eddy current probe to examine tubine engine blades through a videoscope or borescope, both the geometry and proximity factors discussed above negatively impact performance of the eddy current sensor: The geometry negatively affects performance because the blade geometry is not flat. With respect to lift-off, it is difficult to maintain the probe in contact with the blade as it is swept across the surface, as well as maintaining it normal to the blade surface.  
         [0008]     What is needed is an improved videoscope having an eddy current sensor that may be used to inspect turbine blades. The improved device should be less susceptible than current systems to “lift off.” In addition, the performance degradation that occurs in existing systems upon inspection of a non-flat geometry should be minimized or eliminated in the improved device.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is directed to an improved videoscope based inspection tool that has at least two working channels extending along the arm wherein one channel (a “sensor/tool channel”) is adapted to permit a non-destructive testing (NDT) sensor or a tool to be positioned at the distal end, and a second channel (a “fluid delivery” channel) is adapted to guide a fluid (a gas or liquid) to the sensor end. Such an inspection tool permits the use of miniature NDT probes and remediation tools in remote and normally inaccessible areas such as the internal areas of an engine, metal structures within the walls of a building, remote sections of a pipe, and the like.  
         [0010]     Combining the working channels with an image detecting element allows an operator to view the position and/or operation of any tool passing through the sensor/tool channel as well as the placement of any fluid passing through the fluid delivery channel. In some instances any lens system used to focus a signal on the image detecting element could be directed toward where a tool passing through the working channel would be during its operation.  
         [0011]     In one embodiment, the videoscope includes a sensor end having an image detector and at least one sensor selected from the group consisting of an eddy current sensor, an ultrasonic sensor, or an array of such sensors; a handle; and an elongated arm that comprises a conduit that connects the sensor end to the handle. The conduit houses a link that transmits image information from the image detector through the conduit, and the conduit further houses at least first and second working channels that extend from the sensor end to the handle. Fluid injected at a handle end of the conduit passes through the first working channel, out the sensor end, and onto the surface or object under examination. The second working channel contains the eddy current or ultrasonic sensor and transmits their signals through the conduit.  
         [0012]     In another embodiment, the videoscope includes a sensor end having an image detector and an eddy current sensor that comprises a hemispherical surface and a pickup coil wrapped around the sensor. The hemispherical surface maintains contact with the surface of interest during examination of the surface of interest with the eddy current sensor. The videoscope also includes a handle, and an elongated arm having a conduit that connects the sensor end to the handle. The conduit houses a link that transmits image information from the image detector through the conduit, and at least one working channel that extends from the sensor end to the handle. The at least one working channel transmits signals from the eddy current sensor through the conduit during examination of the surface with the eddy current sensor.  
         [0013]     Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a perspective view of a videoscope, in accordance with one embodiment of the present invention;  
         [0015]      FIG. 2  is a diagram of the sensor end of a videoscope with a hemispherically-shaped eddy current sensor, in accordance with another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     As shown in  FIG. 1 , a videoscope  1  comprises a handle  100  and an arm  200  wherein arm  200  comprises a sensor end  300 . Sensor end  300  comprises an image detecting element  310 , optical fiber ends  320 , and the ends of working channels  330  and  340 . Fibers  220  extend along the length of arm  200 , as do working channels  230  and  240 , and conductors  210 . Conductors  210  transmit signals to and from element  310 . Arm  200  may also comprise one or more steering cables  250  required for distal end articulation. The portion of arm  200  that is coupled to handle  100  may be referred to as the handle end, and the sensor end  300  of the arm may be referred to as the distal end.  
         [0017]     As can be seen,  FIG. 1  depicts an improved videoscope based inspection tool  1  that has at least two working channels  330  and  340  extending along the arm wherein one channel (a “sensor/tool channel”) is adapted to permit a non-destructive testing (NDT) sensor or a tool to be positioned at the distal end, and a second channel (a “fluid delivery” channel) is adapted to guide a fluid (a gas or liquid) to the sensor end. Such an inspection tool permits the use of miniature NDT probes and remediation tools in remote and normally inaccessible areas such as the internal areas of an engine, metal structures within the walls of a building, remote sections of a pipe, and the like.  
         [0018]     It is contemplated that any tool or sensor having an appropriate size could be positioned near the sensor end using the sensor/tool channel. However, it is contemplated that eddy current sensor(s) (e.g., either a single eddy current sensor or an array of eddy current sensors), ultraviolet, and ultrasonic sensor(s) (e.g., either a single ultrasonic sensor or an array of ultrasonic sensors) may prove particularly advantageous, and can be manufactured to pass through the sensor/tool channel while maintaining an adequate signal-to-noise ratio.  
         [0019]     It is contemplated that transmitting a fluid to the sensor end through the fluid delivery channel would be particularly advantageous if the fluid was one of: water (or other coupler) to enhance the output of an ultrasound sensor positioned via the sensor/tool channel; or a dye penetrant (or air to speed the drying of the dye penetrant) to be used with a ultraviolet (UV) light source and detector to examine the dye penetrant after it has been applied to a surface. However, any fluid that serves a desired purpose at the sensor end of the tool could be transported to that end via the fluid delivery channel. Fluid from the fluid delivery channel may also be used to mark a suspicious area (e.g., an area where a crack may be present) for further examination. In one embodiment (not shown), a syringe located on or near handle  100  is used to inject fluid through the fluid delivery channel and onto the surface being analyzed.  
         [0020]     The actual materials used in the construction of videoscope  1  may vary between different types of videoscopes, as may the sizes and dimensions of its various components.  
         [0021]     Arm  200  may be rigid or flexible. If flexible, it is advantageous to provide it with a steering mechanism such as cables  250  in order to be able to change the position of the sensor end  300  from handle  100 . Less preferred embodiments may use a different type of steering mechanism.  
         [0022]     The working channels, optical fibers, and conductors are preferred to be positioned within arm  200  in order to protect them and to make insertion of arm  200  into small openings easier. However, in less preferred embodiments, one or more elements of videoscope  1  that extend from the handle to a position at or near sensor end  300  may be positioned on the outside of arm  200 , or may simply be adjacent to arm  200 .  
         [0023]     Image detecting element  310  is preferably a CCD (charge coupled device) detector, square or rectangular in shape, and sized to fit in an 11 or 12 mm envelope, or even a 6 to 8 mm envelope. However, element  310  may comprise and device or combination of devices suitable for detecting and transmitting images of surfaces and/or objects positioned near the sensor end of videoscope  1 . In less preferred embodiments, an image may be transmitted via an optical fiber, or element  310  may be something other than a CCD.  
         [0024]     It is contemplated that an inspection tool as described herein may comprise multiple image detecting elements. In such an instance, the use of multiple elements may be used to provide a larger field of view and/or different viewing angles. If multiple image detecting elements are used, one or more elements may be dedicated to viewing a particular portion of the tool, or to a surface being inspected and/or manipulated.  
       EXAMPLE #1  
       [0025]     It is contemplated that videoscopes having delivery channels as described herein may be used in conjunction with an ultrasound sensor being positioned through use of the videoscope. In such an instance, an ultrasound sensor could be passed through an arm of the videoscope, and the videoscope used first to identify a location where the sensor is to be positioned, then to transmit a fluid such as water to that location, and then to position the sensor. Ideally, fluid transmission, and positioning of the ultrasound sensor would all be done while using the videoscope to view the location where the sensor is being positioned.  
       EXAMPLE #2  
       [0026]     It is contemplated that videoscopes having delivery channels as described herein may also be used to mark a suspicious area for further examination. The use of a videoscope to do such marking allows objects or portions of objects that are not readily accessible to be marked, and allows them to be marked without having to stop viewing the area through the videoscope. As such, a method of using a videoscope comprising a fluid delivery channel may comprise one or more of the following steps: using a videoscope comprising a fluid delivery channel to examine an object or a portion of an object and to identify a portion of the object that is to be further examined, replaced, and/or repaired; while viewing the portion of the object to be marked through the videoscope, causing fluid to flow through an arm of the videoscope and onto or adjacent to the identified portion of the object; subsequently removing and/or disassembling the object and locating the identified portion of the object. If, for example, the object is an aircraft engine having internal assemblies that are only visible with disassembling the engine, through the use of access ports and a videoscope, one could use such a port and the videoscope to identify a potential problem within the engine, to mark that spot using fluid delivered via the videoscope, to remove the scope from the access port and thereby temporarily losing visibility to the marked portion, and then removing and/or partially disassembling the engine to regain visibility to the marked portion. In contrast, prior methods would typically require either removal and/or disassembly of the engine for inspection, and having to re-locate the area of concern after such removal and/or disassembly.  
         [0027]      FIG. 2  is a diagram of the sensor end of a videoscope  2  with a hemispherically-shaped eddy current sensor  410 , in accordance with another embodiment of the present invention. The videoscope shown in  FIG. 2  is substantially the same as the videoscope shown in  FIG. 1 , except the videoscope in  FIG. 2  includes an eddy current probe  410  which is comprised of a hemispherical surface  410   a  and windings (not shown) around the probe that function as a conventional pickup coil. Probe  410  is cantilevered from the end of its cable  420 , reaching out of the distal end  430  of videoscope  2 . The cable  420 , being flexible, is fed into the working channel of videoscope  2  and observed through a video monitor until the hemispherical surface  410   a  of probe  410  is in contact with the surface  440  being examined (e.g., an aircraft engine blade), and then some, to bend over cable  420 . Then, during examination of surface  440  with videoscope  2 , as the distal end  430  is moved to traverse the probe  410  across the surface  440 , the hemispherical surface  410   a  of probe  410  remains in contact with the surface  440  and cable  420  bends or unbends to accommodate changes in the contour of surface  440 . During this process, the hemispherical surface  410   a  of probe  410  remains in contact with surface  440 , and is normal to the surface.  
         [0028]     Thus, specific embodiments and applications of videoscopes having fluid delivery channels have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.