Abstract:
An infrared thermometer includes a thermal conductor and a thermal adjuster to conduct suitable thermal flux into the sensor unit. A thermal conductive bushing is also mounted under the bottom of the sensor unit and touching the thermal conductor. The thermal fluxes conducting to the upper portion and the lower portion of the sensor unit are thus balanced suitably and quickly to remove the thermal noise and help the thermometer maintaining precise measurements from infrared radiation of the target.

Description:
[0001]     This is a continuation-in-part application of application Ser. No. 11/025,046, filed on Dec. 30, 2004, and which claimed priority from Taiwanese Application No. 093134141, filed Nov. 9, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention generally relates to an infrared thermometer, and in particular relates to an infrared thermometer, such as an ear thermometer, that can easily become ready for measurement and save time of thermal balance.  
       BACKGROUND OF THE INVENTION  
       [0003]     Every summer, the severe acute respiratory syndrome (SARS) seems ready to make trouble. In the SARS crisis, more and more families use ear thermometers. Infrared thermometers become the front line tools of the airport quarantine personnel to prevent intrusion of the epidemic.  
         [0004]     As shown in  FIG. 1 , an ear thermometer mainly includes an infrared sensor  10  to detect temperature based on infrared radiation inside the ear canal. Besides the infrared sensor  10 , there is a waveguide  22  and a heatsink  21 . As shown in  FIG. 2 , the infrared sensor  10  is composed of a base  11 , pins  12 , a cover  13 , a filter  14  and a sensing portion  15 . The base  11  carries the sensing portion  15 . The pins  12  pass through the base  11  and output the electrical voltage transduced from the infrared radiation (corresponding to the target temperature) and signals corresponding to the temperature of the base  11  of the sensor. The cover  13  covers the base  11  and the sensing portion  15  and leaves a window for mounting the filter  14 . The filter  14  provides a suitable filtration of a certain range of infrared rays passing to the sensing portion  15  for detecting the temperature of the target (such as the eardrum in the ear canal that represents the body temperature).  
         [0005]     The sensing portion  15  is mainly a “thermopile” to detect the target temperature by transducing thermal radiation into an electrical output. In order to ensure reception of the thermal radiation of the target only, the filter  14  on the cover  13  is used to define a suitable viewing angle in which the heat (infrared radiation) from the target is transferred to the sensing portion  15 .  
         [0006]     The cover  13  is usually made of a thermal conductive material, such as metal, so that the heat conducted to the cover  13  of the sensing portion  15  is easy to be transferred to other portions, and prevents inaccurate measurement caused by interference of partial thermal unbalance. However, the cover  13  is made of thin metal so that partial thermal unbalance actually exists between the cover  13  and the base  11  and influences the thermopile output.  
         [0007]     Therefore, in application, the ear thermometer  20  includes a waveguide  22  and a heatsink  21 . The waveguide  22  leaves the infrared sensor  10  away from thermal contact with the heat target (ear canal) but transfers the infrared radiation. The heatsink  21  absorbs and balances the heat conducted to an exterior of the infrared sensor  10  so as to prevent partial thermal unbalance and increase the measurement accuracy. However, the waveguide  22  complicates the construction and increases the cost of the ear thermometer  20 .  
         [0008]     U.S. Pat. No. 6,076,962 discloses an infrared probe consisting of a sensor unit disposed on a sensor base and surrounded by an isolation unit to eliminate the conventional waveguide tube. The isolation unit is applied to limit the heat transmission caused by the temperature difference between the probe and the sensor unit. The isolation unit is made of thermal conductive material that can transmit the heat quickly so as to reduce the temperature measurement error. However, the isolation unit causes the sensor unit to be isolated from the ambient temperature. Therefore, the infrared probe has to stay in the environment for a period of time till the probe and the sensor unit get balanced in order to achieve accurate measurements. A long balancing time is required when the ambient temperature changes largely. It causes inconvenience to the users.  
       SUMMARY OF THE INVENTION  
       [0009]     The object of the invention is to provide an infrared thermometer without using a waveguide and can save time of thermal balance to get ready for measurement easily.  
         [0010]     An infrared thermometer according to the invention includes a shell, a thermal conductor, a sensor unit and a thermal conductive bushing. The thermal conductor and the sensor unit are located in the shell. The thermal conductor conducts suitable thermal flux into the sensor unit. The thermal conductive bushing is mounted under the bottom of the sensor unit and touching the thermal conductor. The thermal fluxes conducting to the upper portion and the lower portion of the sensor unit are thus balanced suitably and quickly to remove the thermal noise of conduction and help the thermometer maintaining precise measurements from infrared radiation of the target.  
         [0011]     The invention can further include a thermal conducting adjuster mounted between the thermal conductor and the sensor unit to allow suitable thermal flux conducted into the sensor unit and to maintain the accuracy of measurement. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention will become more fully understood from the detailed description given hereinbelow. However, this description is for purposes of illustration only, and thus is not limitative of the invention, wherein:  
         [0013]      FIG. 1  is a constructional view of a conventional ear thermometer;  
         [0014]      FIG. 2  is a constructional view of a conventional infrared sensor unit;  
         [0015]      FIG. 3  is a compositional view of an infrared thermometer of the invention;  
         [0016]      FIG. 4  is a sectional view of an infrared thermometer of the invention;  
         [0017]      FIGS. 5A  to  5 C are sectional views of other embodiments of the invention;  
         [0018]      FIG. 6A  is a partial sectional view of a shell in the invention showing a cutoff portion;  
         [0019]      FIG. 6B  is a partial sectional view of a shell in the invention showing a thermal retardant ring;  
         [0020]      FIGS. 7A, 7B  are embodiments of thermal conductive bushing in the invention; and  
         [0021]      FIGS. 8A, 8B  are embodiments of thermal conducting adjuster in the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     As shown in  FIG. 3 , an infrared thermometer according to the invention includes a shell  30 , a thermal conductor  40 , a sensor unit  60  and a thermal conductive bushing  70 . The shape of the shell depends on the final product. For example, the shell of an ear thermometer is a probe having a smaller front end for fitting into one&#39;s ear canal (not shown in the drawing). Of course, the shell  30  can have other shapes. The shell  30  is mainly a hollow tube having an inner space and a measuring window  31  at its front end. The thermal conductor  40  is also a tube having an inner space and an opening  41  corresponding to the measuring window  31 . The thermal conductor  40  is made of thermal conductive material, located in the shell  30  and holds the sensor unit  60  for conducting suitable thermal flux into the sensor unit  60  and equalizing the temperature surrounding the sensor unit  60 .  
         [0023]     The sensor unit  60  is located inside the thermal conductor  40 . The sensor unit  60  consists of a cover  61 , a base  62  and output pins  63 . The cover  61  has a filter window  611  (the same as that illustrated in  FIG. 2  and described above). Exterior infrared radiation passes through the measuring window  31 , the opening  41  and the filter window  611  to the sensing portion inside the sensor unit  60  for temperature measurement. In order to prevent the conductive thermal flux of the thermal conductor  40  from directly passing into the cover  61  of the sensor unit  60 , the portion of the thermal conductor  40  surrounding the sensor unit  60  does not fully contact with the cover  61 .  
         [0024]     In prior arts of infrared thermometers, the sensor unit is isolated behind the waveguide or covered by the heatsink or the isolation unit as described above. The conventional infrared thermometers require a period of time to balance the temperature of the sensor unit with the ambient temperature for an accurate measurement. Because the temperature measurement is based on the temperature difference between the sensing portion (the infrared radiation passing through the filter window  611 ) and the base  62 , the temperature at the upper portion of the sensor unit  60  has to be balanced with the temperature of the base  62  so as to get accurate measurements. Especially when moving the thermometer to a place where the ambient temperature changes a lot, a longer waiting time is required for the temperature of the sensor to get balanced with the ambient temperature.  
         [0025]     On the contrary, the infrared thermometer of the invention uses a thermal conductor  40  to hold the sensor unit  60  and conducts suitable thermal flux into the sensor unit  60  from the upper portion of the sensor unit  60 . Further, a thermal conductive bushing  70  is mounted under the bottom of the sensor unit  60  and touching the base  62  and the thermal conductor  40  (the thermal conductor  40  extends longer over the sensor unit  60  so as to contact the rim of the thermal conductive bushing  70 ). The shape of the thermal conductive bushing  70  can be as shown in  FIG. 7A , with some cutoffs being formed on the rim for partial contact only. Or, the thermal conductive bushing  70  can be a full circle as  FIG. 7B  for full rim contact with the thermal conductor  40 .  
         [0026]     The thermal conductive bushing  70  can be made of either a non-metal material (such as silicone rubber) or metal, for a suitable thermal conductivity.  
         [0027]     During measurement, a part of thermal flux is also conducted from the thermal conductor  40  via the thermal conductive bushing  70  to the bottom of the sensor unit  60  so as to balance with the thermal flux conducted from the thermal conductor  40  to the upper portion of the sensor unit  60 , and to maintain or fast achieve the ready-for-measurement conditions. According to different balance requirements, the shape (contact area), volume or length (as shown in  FIGS. 5A  to  5 C) of the thermal conductor  40  and the thermal conductive bushing  70  are suitably arranged. When suitably adjusting the thermal conductions of the thermal conductive bushing  70  and the thermal conductor  40  to the sensor unit  60 , it can even achieve a condition that the sensor unit  60  is dynamically balanced, at each measurement and maintains precise measurements from infrared radiation of the target without the need of waiting for a balance time of thermal conduction.  
         [0028]     As shown in  FIGS. 5A  to  5 C, there can further be a thermal conducting adjuster  50  mounted between the thermal conductor  40  and the sensor unit  60  to allow suitable thermal flux conducted into the sensor unit  60  and to maintain accurate measurements. The thermal conducting adjuster  50  is made of non-metal material (such as silicone rubber) or metal for a suitable thermal conductivity. The shape of the thermal conducting adjuster  50  can be a cup (as shown in  FIGS. 5A  to  5 C), a plate (as shown in  FIG. 8A ) or a ring (as shown in  FIG. 8B ).  
         [0029]     On the other hand, inside the front end of the shell  30 , there can be a concave or cutoff portion  32  to decrease the contact area of the shell  30  with the thermal conductor  40  and to achieve a better thermal conduction adjusting result. The reduction of thermal conduction can also be achieved by a thermal retardant ring  80  (as shown in  FIG. 6B ) located between the shell  30  and the thermal conductor  40 .  
         [0030]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.