Abstract:
A hand-held automatic refractometer comprises a completely fluid-sealed housing enclosing a wireless transmitter for transmitting digital measurement data to a remote computer having a corresponding receiver connected thereto. The refractometer housing protects the internal components, including the transmitter, from damage caused by test fluids and cleaning fluids.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to refractometers for measuring refractive index of a substance, and more particularly to an automatic refractometer that includes a completely fluid-sealed housing for easy cleaning without sacrificing the capability to download measurement data to a computer. 
     Refractometers are widely used for quality control in industry for measuring sugar concentrations (Brix scale) of fruits, fruit juices, soft drinks and other food products; measuring concentrations of water soluble cutting fluids and other lubricants; testing the freeze point of propylene glycol and ethylene glycol antifreeze solutions; measuring the boiling point and percent water content of brake fluids; testing salinity of sea water; and for other refractive-index based measurements. Because refractometers come into contact with the above-mentioned fluids both during testing and as a natural consequence of being stored in industrial environments, they require frequent cleaning. It is therefore desirable to protect internal optics and electronics (in the case of automatic refractometers) from exposure to harmful test fluids and cleaning fluids. 
     While many automatic refractometers on the market today are substantially fluid-sealed, they suffer the drawback that a connection port for connecting a data cable to the instrument for downloading digital measurement data to a computer is exposed to test samples, environmental fluids, and cleaning fluids. Therefore, neatness during use and care during cleaning are required to prevent damage to the connection port. In non-automatic refractometers and refractometers without data downloading capability, completely fluid-sealed housings are known. 
     BRIEF SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to improve an automatic refractometer of a type that provides digital measurement data by enclosing the refractometer components in a completely fluid-sealed housing, without destroying the refractometer&#39;s capability to download measurement data to a computer. 
     To meet this object, a refractometer of the present invention is provided with a completely fluid-sealed housing, and a wireless transmitter is among the components enclosed within the housing. Digital measurement data are thereby transmitted as optical pulse signals through a communication window in the housing to a corresponding receiver connected to a computer. In a preferred embodiment, infra-red signal transmission is in accordance with IrDA (Infrared Data Association) hardware standards. 
     The housing includes an upper housing portion having a sample well opening and a display panel recess, a display/button panel fitted to reside in the display panel recess, a sample well received in the sample well opening, a lower housing portion including a window recess and a battery opening, the aforementioned communication window fitted to reside in the window recess, and a battery cover threadably attached to the lower housing portion to cover the battery opening. Fluid sealing O-rings are provided at connections between the upper and lower housing portions, between the sample well and the upper housing portion, and between the battery cover and the lower housing portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
     FIG. 1 is a perspective view of an automatic refractometer formed in accordance with a preferred embodiment of the present invention; 
     FIG. 2 is a cross-sectional view of the automatic refractometer shown in FIG. 1; 
     FIG. 3 is a bottom plan view of the automatic refractometer shown in FIG. 1; and 
     FIG. 4 is a schematic diagram showing wireless data communication of the automatic refractometer of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 through 3, an automatic hand-held refractometer formed in accordance with a preferred embodiment of the present invention is shown and broadly designated by the reference numeral  10 . Refractometer  10  is of a type that provides digital measurement data. In the presently preferred embodiment, refractometer  10  uses optical means in combination with a photosensitive detector, analog-to-digital conversion electronics for digitizing output from the detector, and microprocessing electronics for evaluating the digitized information to provide digital measurement data, as taught in commonly owned U.S. patent application Ser. No. 09/842,463, which is hereby incorporated by reference in the present specification. 
     Refractometer  10  includes a multiple-piece assembled housing that generally comprises an upper housing portion  12 , a lower housing portion  14 , a sample well  16  mounted in upper housing portion  12 , a display/button panel  18  mounted in upper housing portion  12 , a communication window  20  mounted in lower housing portion  14 , and a battery cover  22  threadably attached to lower housing portion  14 . 
     Upper housing portion  12  and lower housing portion  14  are preferably molded plastic pieces sized for closing fit with each other about their opposing peripheries and held together by a plurality of fasteners  24 . In accordance with the present invention, a sealing O-ring  26  is situated about the entire joined periphery and confined between upper housing portion  12  and lower housing portion  14  to provide a fluid-tight seal therebetween. 
     Upper housing portion  12  includes a display panel recess  28  sized to receive display/button panel  18  in a close-fitting manner, and a circular sample well opening  30  sized to receive an upper cylindrical portion of sample well  16 . Display/button panel  18  is a fluid-tight panel cemented in display panel recess  28  to provide a fluid-sealed cover over LCD display  32  and control buttons  34 . Sample well  16  includes a circumferential flange  36 , and a sealing O-ring  38  is situated and confined between flange  36  and upper housing portion  12  for fluid sealing about the sample well. Sample well  16  includes a frustoconical inner wall  40  tapering to meet an external surface  42  of a sample prism  44  for receiving a test sample. 
     The underside of lower housing portion  14  includes a window recess  46  in which a correspondingly sized communication window  48  is cemented in a sealing manner. Communication window  48  is formed of plastic that transmits infrared radiation, and completely covers a communication portal  50  through the underside of lower housing portion  14 . Lower housing portion  14  further includes a battery opening  52  through which batteries can be inserted into and removed from refractometer  10 , and battery cover  22  is threadably attached to the lower housing portion to cover battery opening  52 . A sealing O-ring  54  is provided between battery cover  22  and lower housing portion  14  to maintain a fluid-tight seal when the battery cover is in place. 
     Despite the completely fluid-sealed design of refractometer  10 , it nevertheless is capable of transmitting its digital measurement data to an external computer. In particular, the means for downloading the data to an external computer is fully enclosed by the completely fluid-sealed housing. In accordance with the present invention, the means for downloading the data to an external computer comprises a signal transmitter for converting the digitized data into optical pulses for wireless transmission to a corresponding receiver installed in a computer. Making reference now to FIGS. 2 and 4, presently preferred data transmission means comprises a standard IrDA transceiver  59  that includes an infrared LED  60  for transmission and an infrared photodiode  61  for reception connected to a main circuit board  62  of the refractometer and arranged to closely face communication portal  50  and communication window  20 . Transmitter  60  generates infrared pulse signals transmitted through communication portal  50  and communication window  20  to a corresponding IrDA transceiver  64  installed in external computer  66 . Of course other wireless communication interfaces may be used, including those which operate via radio frequencies, for example a “Bluetooth” interface. 
     As will be appreciated from the foregoing description, refractometer  10  is completely fluid-sealed for easy cleaning. This convenience does not prevent data communication with an external computer, as was the case with refractometers of the prior art, by virtue of the enclosure of wireless data transmission means within the refractometer housing.