Abstract:
A refractometer which provides a “sugar” or “diet” indication when immersed on a beverage. The device is electronic and lights either a “sugar” or “diet” signal to the user. A prove has a light source and a photodetector at one end and an angled face at the other end. Depending on the refractive index of the beverage, the light is either reflected back into the probe and into the photodetector and exits out of the angled face and does not reflect back to the photodetector.

Description:
[0001]    This is a nonprovisional application of provisional patent application Serial No. 60/197,898 filed Apr. 17, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention is a device to be used for determining whether a beverage is of the artificially sweetened “diet” variety or the sugar sweetened variety. This is useful for beverages, such as carbonated soft drinks, which are sold in both varieties, the two being almost identical in taste and appearance. Many people, such as diabetics or calorie-conscious dieters, could benefit from a simple, reliable means of differentiating between the two varieties.  
           [0003]    This invention uses the index of refraction of the beverage to determine whether the beverage contains sugar. As the concentration of sugar in a beverage is increased, the index of retraction of the beverage increases as well. Because artificial sweeteners are only used in minute quantities in diet soft drinks, the refractive index of diet drinks is essentially the same as that of pure water. A typical sugar sweetened soft drink, on the other hand, contains enough sugar to make its refractive index considerably higher than that of its artificially sweetened counterpart.  
           [0004]    The sugar sweetened versions of most soft drinks contain about 12% sugar by weight as they come from the bottle and may vary as low as 6% sugar after dilution by melted ice.  
           [0005]    The device consists of a probe which is dipped into the beverage to be tested, together with electronic circuitry which determines the type of beverage being tested. The device turns on an indicator light to display the result of the test. The invention has advantages over devices such as that described in U.S. Pat. No. #5,859,696, “Refractometer for distinguishing sugar-sweetened beverages from artificially-sweetened ones”, which require enough ambient light for the user to be able to see light passing through the liquid. This invention is easier to use because the user only needs to dip the probe in the beverage and press a button to perform a test. The test is also more discreet because the user does not need to raise the device to his eye. This invention has an advantage over chemical test strips which can only be used once and which have a limited shelf life. The device is only intended to indicate whether a beverage is of the diet or sugar-sweetened variety, rather than producing a high accuracy measurement of refractive index. Thus it can be simpler, more compact and more economical than devices which produce high accuracy measurements.  
           [0006]    This device could be useful to those people who wish to avoid sugar because of diabetes, dental problems or weight control concerns. People with phenylketonuria (PKU) must avoid aspartame, a common artificial sweetener. Some people experience nervous system problems when they drink beverages containing aspartame and may wish to avoid diet soft drinks. Many people are wary of any possible long term health effects of consuming artificial sweeteners and want to avoid them to reduce their possible risk of cancer or other illnesses. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a plan view of the device for distinguishing sugar sweetened beverages of the present invention.  
         [0008]    [0008]FIG. 2 is a front view of the device of FIG. 1 shown being held over a container of a beverage.  
         [0009]    [0009]FIG. 3 is a cut-away view showing the internal elements of the device of FIG. 1.  
         [0010]    [0010]FIG. 4 is a cross-sectional side view of the probe, light source, and photodetector of the device of FIG. 1.  
         [0011]    [0011]FIG. 5 is a cross-sectional view of the probe, light source, and photodetector of the device of FIG. 1.  
         [0012]    [0012]FIG. 6 is a circuit diagram of the device of FIG. 1. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    In the preferred embodiment, the device  10  has an enclosure  11 , shown in FIG. 1, which houses the electronics and a source of power, such as a battery  12  (shown in FIG. 3). The enclosure has a button  13  which the user presses to activate the device. The device has red  14  and green  15  indicator lights which display the results of the test being conducted. A probe  16  made display the results of the test being conducted. A probe  16  made from a transparent material such as glass or plastic projects from the enclosure.  
         [0014]    [0014]FIG. 2 shows the device  10  being held over a container  17  of a beverage. the probe  16  is dipped into the beverage shortly after the power switch  13  is depressed. If the drink contains ice, the drink should be stirred with a straw or spoon to thoroughly mix in any water that may have formed as the ice melted (otherwise a false indication of “diet” could result).  
         [0015]    The device should be held so the button can be pressed while the probe is dipped into the drink, and so the indicator lights can be seen. FIG. 2 shows a comfortable way of holding the device. Press the button so the “ON” light comes on. Firmly hold the button in and dip the probe quickly into the drink. It should be dipped in at least as far as to cover the tip of the probe. Watch the indicator lights as the probe goes into the drink. If the red “SUGAR” light comes on, the drink is of the “regular” type. If just the green “ON” light stays on, the drink is of the “diet” type. Carefully wipe the probe dry after using the device. Avoid smearing grease on the probe or scratching the shiny face at the end. If testing more than one drink, wipe excess beverage off the probe after testing each drink.  
         [0016]    If the probe is held in the drink for more than a couple of seconds, and the drink is highly carbonated, the red light may go out and the green light come back on. This is due to bubbles covering the probe and preventing the liquid from touching the sensing area on the probe. This is why it is important to dip the probe in quickly and watch to see if the lights change.  
         [0017]    The device should not be used to test for the presence of sugar in drinks that contain alcohol. Alcohol can produce the same indication as sugar, giving a false positive reading.  
         [0018]    [0018]FIG. 3 shows a cut-away view of the preferred embodiment of the invention. A light source  18  inside the enclosure  11  is positioned so as to project a beam of light  19  into the light-receiving end  20  of the probe  16 , as shown in FIG. 4. The light beam  19  travels parallel to the long axis  21  of the probe  16  and impinges on an inclined face  22  at the extreme end of the probe. Any light which is reflected from this face bounces to a mirrored surface  23  in the probe and is reflected back through the probe  16 . The reflected ray is indicated in FIG. 4 by reference character  24 . Ray  24  strikes a photodetector  25  inside the enclosure. The probe  16  has two holes  26  and  27  and a notch  28  positioned so as to prevent stray reflections and light from external sources from reaching the photodetector  25 .  
         [0019]    The light beam  19  striking the inclined face  22  at the end of the probe is reflected from, or transmitted through, the face  22  to an extent which depends on the refractive index of the medium in contact with the face. The angle of the face is chosen so that the beam  19  is totally reflected when the index of refraction is equal to that of pure water or a diet beverage. When the index of refraction is that of a sugar sweetened beverage, a large portion of the light beam  19  is transmitted through the face into the beverage as shown in FIG. 5. The transmitted ray is indicated by reference character  29 . As a result, the amount of light striking the photodetector drops. The lower intensity light ray  30  is an indication of a sugar-sweetened beverage.  
         [0020]    An electronic circuit, shown in FIG. 6, is used to determine whether the light intensity striking the photodetector corresponds to a sugar-sweetened or a diet beverage. Amplifier A 1  is used as a current-to-voltage converter to produce a voltage output from the current through photodetector Q 1 . R 1  is chosen to give a suitable voltage gain with the range of current available from Q 1 . Zener diode D 1  provides a stable reference voltage for the circuit.  
         [0021]    Amplifier A 2  is used as comparator to determine whether Al&#39;s output voltage is above or below the threshold voltage set by potentiometer R 4 . If the output voltage of A 1  is higher than the threshold voltage, corresponding to a high light level, the output of A 2  goes to its positive limit. This turns on green LED D 2  which indicates a diet beverage. R 2  and R 3  are chosen to provide hysteresis, giving a positive switching action to the comparator.  
         [0022]    A 3  is connected as an inverter. When the output of A 2  is high, the output of A 3  goes low, preventing red LED D 3  from turning on. When the output of A 2  is low, as when a sugar-sweetened beverage is detected, the output of A 3  goes high, turning on D 3  which indicates a sugar sweetened beverage.  
         [0023]    The user presses the power button  13  to activate the device and dips the probe  16  into the liquid to be tested. The device immediately lights an indicator to display the result of the test. In the preferred embodiment of the device, a red light  14  indicates the presence of sugar and a green light  15  indicates the absence of sugar.  
         [0024]    The electronic circuitry can include means for reducing the sensitivity of the device to ambient light, such as modulation or synchronous detection. The device may include a means to indicate low battery level. The device may include an audible alarm to alert the user when a beverage is found to contain sugar. The alarm may consist of a tone or other distinctive sound, or a voice saying, for example, “Sugar.” The probe may be made retractable for protection while the device is being carried. It could slide or pivot out of the enclosure for use.  
         [0025]    The present embodiments of this invention are thus to be considered in all respects as illustrative and not restrictive; the scope of the invention being indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.