Abstract:
A heat sink assembly for a microscope including a baffle plate located proximate an air inlet of a microscope and a heat sink located proximate the baffle plate. The baffle plate is arranged to enable the passage of air through the air inlet while occluding the emanation of light from the microscope through the air inlet. The baffle plate and heat sink are arranged to induce airflow through the baffle plate, across the heat sink, and out an air outlet for the microscope.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The instant application is a Continuation-In-Part of U.S. patent application Ser. No. 10/244,354 filed Sep. 16, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to microscopy, more specifically to an apparatus for the dissipation of heat away from the illumination source of a microscope, and, even more particularly, to a heat sink assembly for a microscope.  
         BACKGROUND  
         [0003]    As is well known, a microscope is an optical instrument used to view, examine, and study very small objects. Many different types of microscopes have been developed since 1673, when Anton van Leeuwenhoek first magnified an object using a polished glass bead. These types include, but are not limited to: compound, stereo, confocal, inverted, and laser microscopes.  
           [0004]    Microscopes have long used sources of light, both visible and non-visible, for the illumination of objects prior to their magnification. In early microscopes, plano and concave mirrors were used to guide light from external illumination sources, for example, the sun or candles, into the optical system. In modern microscopy, an object can be illuminated under many different lighting conditions. Some examples of lighting conditions include brightfield, darkfield, Köhler, oblique, and phase contrast illumination. The type of lighting condition used to illuminate an object is dependant upon the type of sample being observed, and the desired resultant image. For example, transparent sample images have poor contrast if illuminated with a brightfield source.  
           [0005]    An inherent problem in the operation of modern microscope illumination systems is the necessity to dissipate, in a safe and harmless manner, the heat energy generated by the illumination systems. Agencies such as Underwriters Laboratory (UL) have determined maximum permissible surface temperatures for laboratory instruments. However, many light sources commonly used in microscopes create temperatures well above the permissible temperatures. For example, tungsten halogen bulbs can reach temperatures of 250° C. under normal operating conditions. If the heat generated by a light source is allowed to transfer directly through the microscope base, the temperature of the base surface may exceed the abovementioned maximum temperature.  
           [0006]    Modern illumination systems require modem electronic circuits to regulate and control the delivery of light. The electronic components forming the illumination system control circuit are sensitive to heat. As a result, heating the control circuits with energy from the illumination source can adversely impact component life expectancy and illumination quality and consistency.  
           [0007]    The emission of light from a microscope into the ambient surroundings also is undesirable. Photomicrography demands the suppression of ambient light to obtain a quality photomicrograph. Due to the requirement of air exchange for heat dissipation, an area on the microscope near the illumination source is typically vented. Unfortunately, in addition to air exchange, venting also may allow light to escape. The escaping light can enter the optical system and degrade image quality. Under some special circumstances, even laboratory overhead lighting must be suppressed prior to image capture. Therefore, it can be seen that any ambient light, even light which emanates from the base of the microscope, is undesirable during the image capture process.  
           [0008]    Thus, given the aforementioned reasons, it can be seen there has been a longfelt need for a heat removal arrangement for a microscope illumination source capable of dissipating heat in a safe and effective manner and occluding air inlets to prevent illumination light egress.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    The present invention broadly includes a heat sink assembly for a microscope having a baffle located proximate an air inlet of a microscope and a heat sink located proximate the baffle. The heat sink is operatively arranged to transfer heat from an illumination source for the microscope to air entering the microscope past the baffle.  
           [0010]    A general object of the invention is to provide a means to transfer heat away from a microscope illumination source in a safe and effective manner.  
           [0011]    Another object of the invention is to occlude light from a microscope illumination source from escaping through an air inlet of the microscope.  
           [0012]    These and other objects, features, and advantages of the present invention will become readily apparent to those having ordinary skill in the art upon reading the detailed description of the invention in view of the drawings and appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    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:  
         [0014]    [0014]FIG. 1 is a perspective view of a microscope;  
         [0015]    [0015]FIG. 2 is a perspective view of the rear of the microscope;  
         [0016]    [0016]FIG. 3 is a perspective view of the microscope with the base plate shown separately;  
         [0017]    [0017]FIG. 4 is a magnified view of the encircled region shown in FIG. 3;  
         [0018]    [0018]FIG. 5 is an exploded view of FIG. 4;  
         [0019]    [0019]FIG. 6 is a cross-sectional view of the microscope, taken generally along line  6 - 6  of FIG. 1;  
         [0020]    [0020]FIG. 7 a  is a magnified view of the encircled region shown in FIG. 6;  
         [0021]    [0021]FIG. 7 b  is a cross-sectional view of the baffle plate, taken generally along line  7   b - 7   b  of FIG. 5;  
         [0022]    [0022]FIG. 8 is a perspective view of the top-right side of the heat sink;  
         [0023]    [0023]FIG. 9 is a perspective view of the bottom-left side of the heat sink;  
         [0024]    [0024]FIG. 10 is a perspective view of the top-left side of the heat sink; and,  
         [0025]    [0025]FIG. 11 is a perspective view of the bottom side of the heat sink.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    It should be appreciated at the outset that while the present invention relates to a “Heat Sink Assembly for a Microscope”, the Assignees of the present Application for Patent have developed certain other improvements to microscopes described in United States Patent Applications entitled “Interchangeable Microscope Stage Drive Assembly”, “Releasable/Interchangeable Fine Focus Knob for a Microscope”, “Ergonomically Arranged Object Adjustment Controls”, “Shielded-Ergonomic Microscope Stages”, “Lamp Assembly for a Microscope” and “Means for Transporting a Microscope”, which applications are filed concurrently herewith by the Assignees of the present Application for Patent, which Applications are incorporated herewith by reference in their entireties.  
         [0027]    [0027]FIG. 1 is a perspective view of a microscope  10 . Additionally, it should be appreciated that like drawing numbers on different drawing views identify identical structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is understood that the invention as claimed is not limited to the disclosed embodiments. In the description below, the terms “up,” “down,” “forward,” “backward,” “left”, “right”, and their derivatives, should be interpreted from the perspective of one viewing the microscope shown in FIG. 1. A conventional compound microscope  10  is shown in perspective view in FIG. 1. Although the invention is suitable for use with a variety of light microscopes, it is useful to review the basic microscope structure and function to appreciate the present invention.  
         [0028]    Microscope  10  broadly comprises microscope stand  12  to which all the component pieces of the microscope are mounted. In the embodiment shown, the viewing body  19  is binocular (eyepieces not shown). Viewing body  19  is not particularly germane to the invention, which is suitable for use with a microscope configured with any type of viewing body, for example, monocular, binocular, trinocular, or video. Objective lenses  23  are mounted to rotatable turret  15 . Microscope  10  further comprises interchangeable microscope stage system  11 , fixedly secured to stand  12 . Interchangeable microscope stage system  11  comprises slide mount  16 , stage  14 , and drive mechanism  27 . Slide mount  16  is incorporated into stage system  11  and enables movement of slide  17 , which holds a specimen to be viewed. Coarse and fine focus knobs  13  are rotatably mounted to stand  12 . Rotating knobs  13  move stage  14  up and down, further moving slide  17  within the optical path of the microscope, allowing for focus at the specimen. By operating switch  32 , the illumination source (not shown) of lamp assembly  21  is powered on and off. Integral to microscope stand  12  is air outlet  34 . Air is permitted to pass through outlet  34  via the plurality of slots  22 . Microscope stand illuminator housing  20  is operatively arranged to contain an illumination system (not shown).  
         [0029]    [0029]FIG. 2 is a perspective view of the rear of the microscope  10 . Power inlet  26  is electrically connected to switch  32  and is configured to receive power from a wall socket (not shown). Air outlet  55  comprising the plurality of slots  54  is arranged to permit the egress of air from the volume contained within microscope stand  12 .  
         [0030]    [0030]FIG. 3 is a perspective view of microscope  10  with base plate assembly  24  shown separately. Fixedly secured in the back area of base plate  35  is power inlet  26  and printed circuit board  25 . Fixedly secured in the front area of base plate  35  is switch  32  and lamp assembly  21 . The electrical wires connecting power inlet  26  to switch  32  are not shown.  
         [0031]    [0031]FIG. 4 is a magnified view of the encircled region shown in FIG. 3.  
         [0032]    [0032]FIG. 5 is an exploded view diagram of FIG. 4. The following should be considered in light of FIGS. 4 and 5. FIG. 5 shows a present invention heat sink assembly  29 . Heat sink assembly  29  includes heat sink  28  and baffle plate  33 . Heat sink  28  dissipates heat energy generated by the illumination source (not shown) of lamp assembly  21 . Base plate  35  includes air inlet  40 , which has a plurality of slots  38 . Baffle plate  33  comprises a plurality of slots  58 . Slots  58  are each partially covered by a respective baffle  57 . Air inlet  40  and slots  38  in base plate  35  and slots  58  and baffles  57  enable the flow of air into microscope stand  12 , around heat sink  28 , and out of microscope  10  through outlets  34  and  55  (see FIGS. 1 and 2).  
         [0033]    Heat sink  28  has integrally mounted fins  30 . Fins  30  include consecutive air gaps  87  and, between air gaps  87 , fm surfaces  86 . The increase in surface area for heat sink  28  due to fin surfaces  86  is largely responsible for the increased heat transfer efficiency of heat sink  28 . Additionally, some heat is dissipated from heat sink  28  via airflow through slots  31 .  
         [0034]    Heat sink  28  also can function as an illumination source housing. In the embodiments shown, an illumination source is included. However, the features required to mount electrical sockets for a source and to position a source are shown. Aperture  84  permits the disposition of a source within heat sink  28 . Holes  82  and  88  are operatively arranged to permit the accurate placement of a lamp assembly socket (not shown). Holes  83  and  89  are operatively arranged to fixedly secure the lamp assembly socket to heat sink  28 .  
         [0035]    [0035]FIG. 6 is a cross-sectional view of microscope  10 , taken generally along line  6 - 6  of FIG. 1.  
         [0036]    [0036]FIG. 7 a  is a magnified view of the encircled region shown in FIG. 6. The following should be viewed in light of FIGS. 5, 6, and  7   a . Baffles  57  serve the dual purposes of deflecting and directing air stream  51  and blocking light from an illumination source in microscope  10 . Thus, air stream  51  is deflected by baffles  57  and moves by and across heat sink  28 . Then, heat from sink  28  is transferred to air stream  51  for subsequent removal via outlets  34  and  55 . By deflecting air stream  51 , baffles  57  create a more turbulent and less laminar airflow by and over heat sink  28 . In general, turbulent airflows are more efficient than laminar airflows for heat transfer. Concurrently, the shape of baffles  57 , which is further described below, in combination with a the relative positions of slots  58  and  38 , blocks light emanating from bulb  50  and prevents this light from exiting through slots  38 . That is, slots  38  and  58  and baffles  57  are aligned such that baffles  57  block the direct path through the slots for light emanating directly from bulb  50  or reflecting from surfaces of lamp assembly  21  or baffles  57 . In the embodiments shown, the relative positions between slots  58  and  38  include a lateral displacement between slots  58  and  38 .  
         [0037]    Slots  38  are oriented in a left-to-right direction within base plate  35 . However, it should be understood that the orientation of slots  38  is not critical to the present invention. In the embodiments shown, baffle plate  33  is oriented so that slots  58  are parallel to slots  38 , that is, from left-to-right. However, in some embodiments (not shown), slots  58  are not parallel to slots  38 . For example, in some embodiments, slots  58  are orthogonal to slots  38 .  
         [0038]    Bulb  50  is releasably secured and collector lens  18  is fixedly secured within heat sink  28 . Collector lens  18  gathers light rays  53  and subsequently transmits rays  53  along the optical path (not shown) of microscope  10 . Bulb  50  imparts heat energy to heat sink  28 . Due to the direct and intimate contact of fins  30  with heat sink  28 , heat from bulb  50  is efficiently conducted to fins  30 . Then, air surrounding fins  30  is heated and subsequently rises within volume  52  of microscope stand  12 . In this embodiment, as the air rises, it is permitted to escape through slots  54  and slots  22 . The exiting air causes a negative pressure within volume  52 . The negative pressure re-equilibrates with atmospheric pressure by drawing air in through air inlet  40 . As noted above, air stream  51 , entering via inlet  40 , is disrupted by baffle plate  33 , thereby creating a more turbulent airflow past heat sink  28 . Thus, air stream  51  is drawn by and over heat sink  28  and fins  30  and convective heat transfer occurs between heat sink  28 , fins  30 , and air stream  51 . Then, the heated air rises and exits through slots  22  or  54 , effectively dissipating heat from heat sink  28 .  
         [0039]    As noted supra, maximum allowable surface temperatures for microscope  10  components, such as base plate  24  or illuminator housing  20  have been established. Since heat energy has the propensity to dissipate along the path of least resistance, more heat energy dissipates via heat sink  28  than transmits through base plate  24  or illuminator housing  20 . Thus, the present invention helps maintain compliance with the abovementioned maximum surface temperatures. It is also desirable to minimize heat transfer to printed circuit board  25 . The electronic components attached to board  25  and comprising the driving circuit for the illumination system (not shown) are thermally sensitive. As the temperatures of the components change, the lamp driving voltage generated by the circuit varies. This variance in driving voltage causes the illumination system to fluctuate, causing image degradation during capture. Therefore, transmitting heat energy through heat sink  28 , rather than through base plate  24 , maintains consistent illumination levels, and subsequently, improves the quality of captured images. Thus, heat sink  28  and baffle plate  33  safely and efficiently dissipate heat energy from microscope  10 .  
         [0040]    In some embodiments, an insulating layer is placed between baffle plate  33  and mounting plate  35  to thermally separate baffle plate  33  from base plate  35 . For example, in FIGS. 5 and 7 a , insulating layer  94  is shown between baffle plate  33  and mounting plate  35 . In the embodiment shown in FIG. 5, layer  94  consists of three separate pieces. However, it should be understood that the number and size of the pieces making up layer  94  can be varied within the spirit and scope of the invention as claimed. Layer  94  can be formed from any suitable insulating material known in the art. For example, in some embodiments, layer  94  is formed from cork.  
         [0041]    Air outlet  34  comprises consecutively located slots  22 , separated by air outlet material  62 . Air stream  51 , after passing by and over fins  30 , is permitted to exit through air vent  34  or outlet  55  (not shown). It should be understood that the configuration of outlet  34  is not particularly germane to the present invention.  
         [0042]    [0042]FIG. 7 b  is a cross-sectional view of baffle plate  33 , taken generally along line  7   b - 7   b  of FIG. 5. Each baffle  57  forms an opening  96 , defined by an upper edge  98  and the surface of baffle plate  33 . In the embodiments shown, slots  58  have a curved, or arcuate, cross-section. This cross-section can be a smooth curve, as shown in FIG. 7 b , or a segmented curve (not shown). Although a particular cross-sectional shape is shown in FIG. 7 b , it should be readily apparent to those having ordinary skill in the art that other cross-sectional shapes are possible, and that such shapes are within the spirit and scope of the invention as claimed. For example, essentially linear cross-sectional shapes, or combinations of linear and curved shapes also are included in the spirit and scope of the invention as claimed.  
         [0043]    In FIG. 7 b , slots  57  are arranged such that openings  96  face in one of two opposite directions. That is, the two left-most openings  96  face left and the three right-most openings  96  face right on the sheet for FIG. 7 b . It should be understood that this is only one possible arrangement for the openings. For example, the openings could be arranged to all face one direction (not shown). Also, the openings facing in different directions can be configured differently than as shown in FIG. 7 b . For example, openings  96  can be arranged in alternating patterns, for example, orienting every other opening in one direction, and orienting the remaining openings in an opposite direction. It is understood that other groupings and patterns of openings also are included in the spirit and scope of the invention as claimed.  
         [0044]    Baffles  57  disrupt air stream  51  as described above. In FIGS. 7 a  and  7   b , the pattern of openings  94  introduces air into the volume contained within microscope stand  12  in two different directions. That is, using sheet  6 / 8  as a frame of reference, air is directed to the left-hand side of the volume by the two left-most openings  92  and to the right-hand side of the volume by the three right-most openings  92 . Diverting the entering air in these two opposite directions helps ensure a more uniform and widely distributed flow of air by and over heat sink  28 .  
         [0045]    [0045]FIGS. 8 through 11 are perspective views of the top-right side, the bottom-left side, the top-left side, and the bottom side, respectively, of heat sink  28 . Collector lens  18  (not shown) is fixedly secured to surface  81 . Slotted openings  31  are operatively arranged to permit the flow of air around collector lens  18 , thus facilitating heat transfer. Holes  82  and  88  are operatively arranged to guide the placement of a lamp assembly socket (not shown). Holes  83  and  89  are operatively arranged to permit the rigid affixing of the lamp assembly socket. Aperture  84  is oriented to permit the installation of bulb  50  (not shown) via the releasable attachment of lamp socket  21  (not shown). Outer wall  90  and inner wall  91  are concentrically arranged with air gap  93  forming a thermal insulating layer between the walls. In the region of holes  83  and  89 , inner wall  91  and outer wall  90  are separated by air gap  92 . Air gap  92  is operatively arranged to prevent the transmission of heat from inner wall  91  to outer wall  90 , and subsequently from the lamp assembly socket (not shown) mounted to holes  83  and  89 .  
         [0046]    Fins  30   a  and  30   b  are integral to outer wall  90 . The remaining fins  30  are integral to inner wall  91 . It should be understood, however, that other configurations of fins  30  with walls  90  and  91  are possible, and that such configurations are within the spirit and scope of the present invention as claimed.  
         [0047]    Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, which modifications are intended to be within the spirit and scope of the invention as claimed. It also is understood that the foregoing description is illustrative of the present invention and should not be considered as limiting. Therefore, other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.