Abstract:
An IR camera for recording and presenting a thermal image of an object comprises optical receiving means for focusing infra-red radiation received from the object onto a focal plane array and processing means for receiving and processing the data from the focal plane array to form a thermal image, presentation means for presenting the thermal image and storage means for storing the thermal image. According to the invention the IR camera further comprises receiving means for receiving from at least one humidity sensor arranged to provide humidity information, information about the humidity in at least one measuring point on the object, and forwarding said humidity information to the processing means, said processing means being arranged to include said humidity information in the thermal image. In this way the camera can directly identify any points on the object where there is risk for damp.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a thermal IR camera having functions for detecting humidity.  
       BACKGROUND  
       [0002]     IR cameras may be used for detecting increased humidity, for example, in part of a building. Calculations based on the temperature in different parts of an IR image canbe used to point out areas in the building having an increased risk of damages caused by damp. However, measurements based only on temperature are not always reliable.  
         [0003]     Other means for humidity detection are known, for example, conductivity sensors. Such sensors are typically moved across an object where humidity is to be detected and react when the humidity in a measurement point exceeds a predetermined threshold value. These measurements are very reliable but are time consuming and cannot be stored for later display in a suitable way.  
         [0004]     The aim of the present invention is to provide an apparatus for humidity detection that is improved compared to the prior art.  
       SUMMARY OF THE INVENTION  
       [0005]     The object is achieved according to the invention by a IR camera for recording and presenting a thermal image of an object, said camera comprising optical receiving means for focusing infra-red radiation received from the object onto a focal plane array and processing means for receiving and processing the data from the focal plane array to form a thermal image, presentation means for presenting the thermal image and storage means for storing the thermal image, said IR camera further comprising receiving means for receiving from at least one humidity sensor arranged to provide humidity information, information about the humidity in at least one measuring point on the object, and forwarding said humidity information to a calculating means, said calculating means being arranged to include said humidity information in the thermal image.  
         [0006]     In this way any areas of the object in which there is a risk of damage due to humidity can be identified directly in the thermal image presented by the camera.  
         [0007]     In a preferred embodiment the IR camera itself comprises at least one humidity sensor for providing said humidity information. The humidity sensor may be a pin-type moisture meter utilizing the principle of electrical resistance. This type of humidity sensor uses wood or other hygroscopic material as an element in a circuit by driving two pins or electrodes into it. Alternatively, the humidity sensor may be a pinless moisture meter using radio frequency signals to penetrate the material being tested. Of course any type of humidity sensor fit to be included in an IR camera can be used.  
         [0008]     If the IR camera does not comprise a humidity sensor, the receiving means are arranged to receive said humidity information from an external humidity sensor.  
         [0009]     The IR camera may also comprise a laser pointer for pointing out, for a first point of interest in the thermal image, a corresponding point on the object.  
         [0010]     In this case, the IR camera may further comprise calculation means for calculating a first position in said thermal image for said first point of interest and based on the first position calculate at least one further position for at least one further point of interest in the image, said points of interest corresponding to points on the object in which measurements in which the humidity is measured. Said presentation means is then preferably arranged to present the measured humidity information in said points of interest in the thermal image.  
         [0011]     The presentation means may be arranged to present the humidity information from said at least one measuring point on the object in the thermal image by including in the image a position marker indicating the position of the measuring point and a number indicating the value of the humidity information in said measuring point.  
         [0012]     Preferably the IR camera also comprises image processing means arranged to assign a range of colours to the humidity information, wherein said presenting means is arranged to present the humidity information as a humidity image using range of colours. The range of colours used for the humidity information is preferably different from the range of colours used for the thermal image, in which case the humidity information can be superimposed on the thermal image.  
         [0013]     The humidity image can also be superimposed on a visual image of the object taken with a photographic camera and provided to the calculating means or a digitized version of a drawing provided to the calculating means. This will facilitate the identification of the different parts of the object in the humidity image.  
         [0014]     The presentation means may also be arranged to present information about the time of the recording and/or the location of the recording in the image.  
         [0015]     In a preferred embodiment the IR camera also comprises calculating means for performing calculations that diagnose the building&#39;s structural condition.  
         [0016]     In this case means may be provided for receiving ambient humidity information about a relative humidity in the air near the IR camera, said calculating means being arranged to take said ambient humidity information into account when performing said calculations.  
         [0017]     Preferably the IR camera comprises means for measuring said ambient humidity in the air near the IR camera and providing it to the receiving means.  
         [0018]     Preferably the IR camera comprises means for receiving information about a temperature in the air near the IR camera, said calculating means being arranged to take said temperature into account when performing said calculations.  
         [0019]     The means for measuring said temperature in the air near the IR camera is preferably arranged to provide it to the receiving means. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The present invention will be described in more detail in the following, with reference to the appended drawings, in which:  
         [0021]      FIG. 1  shows a first preferred embodiment of an IR camera according to the invention.  
         [0022]      FIG. 2  shows a second preferred embodiment of an IR camera according to the invention.  
         [0023]      FIG. 3  shows an IR camera cooperating with a computer according to the invention. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0024]      FIG. 1  illustrates a first preferred embodiment of an inventive IR camera  1 . As is common in IR cameras, the inventive IR camera comprises a lens  5  for focusing incoming IR radiation onto a focal plane array  7 . A processing means  9  receives the data from the focal plane array  7  and processes it to obtain a thermal image.  
         [0025]     In this embodiment a humidity sensor  10 , such as a conductivity sensor, is provided within the camera housing. The camera also comprises one or more input terminals  11  for receiving information from one or more external sensors. These external sensors  11  can be arranged to measure the ambient temperature and/or the air humidity near the camera  1 . The humidity information from the humidity sensor  10  is received in a receiving means  15  and forwarded to a calculating means  17 . Depending on the format of the humidity information received from the humidity sensor the receiving means  15  may also perform calculations on the humidity information to facilitate its inclusion in the image. The calculating means  17  also receives the thermal image from the processing means  9  and is arranged to superimpose the humidity information onto the thermal image. The thermal image having the humidity information superimposed on it may be stored in a storage unit  18  and/or displayed in a display unit  19 . Of course, the thermal image without the humidity information may also be stored and displayed.  
         [0026]     Different ways of superimposing the humidity information on the image will be discussed below.  
         [0027]     The camera may also comprise a laser pointer  21  arranged to emit a beam of light towards the object. Preferably, the laser pointer  21  is arranged to emit the beam of light so that it will mark the point on the object corresponding to the centre of the thermal image recorded by the camera. The laser pointer  21  communicates with the processor  9  and can be used to determine the point in the image to which a certain measurement on the object relates.  
         [0028]      FIG. 2  shows a second embodiment. For elements that are the same as in  FIG. 1 , the same reference numerals are used. In this case, the camera does not comprise an internal humidity sensor. Instead, the camera comprises input means  13  for receiving humidity information from at least one humidity sensor that is used to measure the humidity on the surface of the object. As in  FIG. 1 , the humidity information is provided to a receiving means  15  and from there to a calculating means  17 .  
         [0029]      FIG. 2  also shows a further sensor  23  included in the camera for measuring the ambient temperature and/or the air humidity near the camera. The data from the further sensor  23  is provided to the receiving means  15 , which optionally performs calculations on the data and on the humidity information received from the humidity sensors.  
         [0030]     As in  FIG. 1 , the image data received through the lens  5  and the focal plane array  7  are processed in the processing means  9 . The resulting thermal image is received in the calculating means  17  which also receives the information from the various sensors  10 ,  23  and input terminals  11 ,  13 , from the receiving means  15  and superimposes them on the thermal image. The thermal image having the humidity information superimposed on it may be stored in a storage unit  18  and/or displayed in a display unit  19 . Of course, the thermal image without the humidity information may also be stored and displayed.  
         [0031]     If the camera comprises a laser pointer  21  the laser pointer can be used when matching a measurement to the correct position in the image. The simplest way of implementing this would be to arrange the camera in such a way that the laser beam points at the measurement point while the measurement result is being communicated to the camera. In this way, the point in the image to which a measurement result relates can be determined. For example, it may be known that the point where the laser beam hits the object coincides with the centre of the image.  
         [0032]     A more complex procedure would be to define several points by their position relative to the point indicated by the laser beam. In this way, for example, a matrix of points having a predefined distance between them could be defined on the object and a corresponding matrix in the image. The laser beam could be used to point out one of these points, preferably the centre or a corner of the matrix. Then measurements could be performed in each point of the matrix in a predetermined order.  
         [0033]     An alternative way of determining the point in the image that corresponds to a particular measurement would be to use a sensor probe comprising a position sensing device that would communicate its position to the camera for each measurement performed on the object and communicated to the camera.  
         [0034]     The point in the image corresponding to a particular measurement could also be identified by using a sensor probe having properties that will allow it to be identified in the thermal image. For example, a number of heat sources, typically three heat sources may be arranged in a predetermined pattern so as to be identifiable in the thermal image. In this case, the processing means  9  can identity the position of the measuring point at the same time as data from the measuring point is received. The position identified in this way can be used to include the measuring data in the correct point of the image.  
         [0035]     The humidity information can be superimposed on the thermal image in several different ways. One way would be, for each measuring point on the object, to mark the corresponding point in the image, for example, by a cross, and state the humidity in that point as a number adjacent the cross. The corresponding points can be identified in one of the ways discussed above.  
         [0036]     Alternatively, the humidity range can be assigned a colour range in the same way as is generally done for the temperature range when generating a thermal image. In this case, different colour ranges should be used for humidity and temperature. For example, the thermal image may be presented in shades of grey while the different colours are used to mark humidity. In this way, different levels of humidity can be colour coded, using red for levels indicating an increased risk of damage. The skilled person is aware of several ways of assigning such colour ranges.  
         [0037]     In the same ways as discussed above for thermal images, the humidity information can be superimposed on a visible image or a drawing of the object in digital form.  
         [0038]     As is common in the art, information about date and time, and of the location where the images were recorded, can be included in the image or stored in association with the image. Other types of data, such as sound recordings can also be stored in association with the image.  
         [0039]     The calculating unit may also be arranged to perform calculations to diagnose the building&#39;s structural conditions. The ambient temperature and/or air humidity information received from input terminal  11  or internal sensor  23  can be used by the calculating unit when performing these calculations.  
         [0040]     As the skilled person will understand, the division into functional units in the cameras shown in  FIGS. 1 and 2  is intended for illustration only. The functional units can be combined so that, for example, the functions of the processing means  9  and the calculating means  17  are performed in one unit, or that all calculations are performed in the calculating means  17 , which could then receive humidity information and other information directly from the humidity sensors  10  or input means  11 ,  13 . Further, elements from the two embodiments can be combined so that, for example a laser pointer  21  as shown in  FIG. 1  is included in the embodiment of  FIG. 2 , or a temperature and/or air humidity sensor  23  is included in the embodiment of  FIG. 1 . Of course, the laser pointer  21  can be omitted in  FIG. 1 , and the internal sensors  23  can be omitted in  FIG. 2 .  
         [0041]     In the embodiment shown in  FIG. 3 , again an IR camera  31  is used to record the thermal image of an object  8 . A simplified diagram of the IR camera is shown, comprising a lens  35  for focusing incoming IR radiation onto a focal plane array  37 . A processing means  39  receives the data from the focal plane array  37  and processes it to obtain thermal image data. The thermal image data are then transferred to a computer  41 , such as a personal computer. The computer  41  is also arranged to receive the same types of humidity information and temperature information as above. The information received, as well as the processed images are stored in a memory means  43 . A calculating means  45  in the computer  41  is arranged to perform the humidity calculations performed in the previous embodiments by the calculating means  17  in the camera. In this embodiment the IR camera may be the IR camera as shown in  FIG. 1  or  2 , further arranged to communicate with the computer, or an IR camera that does not itself have the functions for receiving and processing humidity information. How to transfer data from an IR camera to a computer is well known in the art. The computer preferably comprises a display  47  in which the image can be displayed.  
         [0042]     The humidity information may also be superimposed on a visual image of the same object. Including the humidity information in a photograph of the object will make it easier to identify the different parts of the object. This function can be included in each of the embodiments above. The IR camera may also comprise a visible light camera that may provide the images, or digital photographs taken with a separate camera may be entered into the memory unit  18  of the camera or the memory unit of the computer, as the case may be.