Abstract:
Disclosed is a device for modifying the distance between a microscope table and a microscope objective. The vertical adjusting mechanism of the microscope table encompasses a eccentric member which is rotatable about a shaft. At least one actuating button is mounted on the shaft. The eccentric member is embodied such that the microscope table can be subjected to a fine or rough vertical adjustment using of the eccentric member and a monolithic actuating button.

Description:
CROSS REFERENCE TO PRIOR APPLICATION 
   This is a U.S. national phase application under 35 U.S.C. §371 of International Patent Application No. PCT/EP2006/050062, filed Jan. 6, 2006, and claims benefit of German Patent Application No. 10 2005 005 619.9, filed Feb. 8, 2005. The International Application was published in German on Aug. 17, 2006 as WO 2006/084775 A1 under PCT Article 21(2). 
   The present invention relates to a device for varying the distance between a microscope objective and a microscope stage. In particular, the present invention relates to a device for varying the distance between a microscope objective and a microscope stage, the device including an eccentric means which is rotatable about a shaft and is in operative connection with the microscope stage or with the objective. Also provided is at least one control knob connected to the shaft. 
   BACKGROUND 
   U.S. Pat. No. 3,997,239 describes a microscope composed of shell-like parts. The microscope stage is mounted to an arm and can be moved by an eccentric cam in the direction of the optical axis of the microscope. No artificial illumination is provided for the samples located on the microscope stage. Neither is there any provision for a fine adjustment of the microscope stage. 
   Similarly, U.S. Pat. No. 4,361,377 describes a portable compact microscope which has a plurality of adjusting elements provided on the housing. The sample to be examined is introduced through a slot in the housing. Illumination is provided by at least one conventional incandescent lamp which is connectable to a battery for power supply. No provision is made for an adjustable microscope stage. 
   German Patent Applications DE 102 46 277 A1 and DE 102 46 275 A1 describe a microscope whose stand consists of a minimum number of shell parts. In addition, the stand of the microscope is provided with an adjusting knob for focusing. Moreover, the microscope is narrow relative to the height of the stand, and the number of control elements is reduced to a minimum. The microscope has only a few corners and edges, which considerably reduces the risk of damage. However, the microscope is not equipped with any stage adjustment mechanism which would allow fine or coarse adjustment of the microscope stage. 
   The Leitz HM microscope already describes a coarse and fine focus adjustment including a one-piece control knob. Coarse and fine focus adjustment is accomplished by a plurality of mechanical transmission elements. This design does not provide a cost-effective solution. 
   SUMMARY 
   It is an object of the present invention to provide a device for varying the distance between a microscope objective and a microscope stage of an inexpensive microscope, which device is easy to manufacture and has a minimum number of moving parts. 
   In an embodiment, the present invention provides a distance adjustment device for a microscope stage. The distance adjustment device includes a first eccentric member, a second eccentric member and a control knob. The first eccentric member is rotatable about a shaft and bears against the microscope stage. The first eccentric member is configured, when rotated, to adjust a relative distance between the microscope stage and an objective of the microscope. The second eccentric member is disposed on the shaft so as to be freely rotatable relative to the first eccentric member within a predetermined range of rotation so as to provide a fine adjustment of the microscope stage. The second eccentric member is configured, when outside the predetermined range of rotation, to rotate the first eccentric member therewith upon a rotation of the second eccentric member. The control knob is configured to rotate the first and second eccentric members by acting on the second eccentric member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The subject matter of the present invention is schematically illustrated in the drawings and will be described below with reference to the Figures, in which: 
       FIG. 1  is a perspective view of the microscope containing the height adjustment device according to the present invention; 
       FIG. 2  is a perspective inside view of a housing shell in which the individual components of the microscope are mounted; 
       FIG. 3  is a cross-sectional view of the microscope stage, illustrating the interior thereof; 
       FIG. 4  is a perspective view of the height adjustment device for the microscope stage; 
       FIG. 5   a  is a schematic view illustrating the operating principle of the height adjustment device for a microscope stage; 
       FIG. 5   b  is a schematic view illustrating the position of the first and second eccentric members which produces a height adjustment; and 
       FIG. 5   c  is a schematic view illustrating the position of the first and second eccentric members which produces a fine adjustment. 
   

   DETAILED DESCRIPTION 
   The present invention has the advantage that the device for varying the distance between a microscope objective and a microscope stage includes an eccentric means which is rotatable about a shaft. The eccentric means is in operative connection with the microscope stage or with the microscope objective and has at least one control knob connected to the shaft. The eccentric means is designed in such a way that fine and coarse distance adjustment of the microscope stage can be made using the eccentric member device and a one-piece control knob. 
   The eccentric means is composed of a first eccentric member and a second eccentric member. The coarse distance adjustment can be made using the first eccentric member, while the fine distance adjustment can be made using the second eccentric member. Only the first eccentric member is in operative connection with the microscope stage. The first eccentric member is formed with an eccentric hole, in which the second eccentric member is rotatably mounted. The second eccentric member has a pin formed thereon which cooperates with two stops provided on the first eccentric member. 
   The first eccentric member has a greater eccentricity than the second eccentric member. The ratio of the eccentricity of the first eccentric member to the eccentricity of the second eccentric member is between 10 and 25. Engagement of the pin of the second eccentric member against one of the stops of the first eccentric member results in a coarse distance adjustment of the microscope stage. Movement of the pin of the second eccentric member between the stops of the first eccentric member results in a fine distance adjustment of the microscope stage. 
   The microscope stage includes a sample support part, a guide part, and a base. The first eccentric member is disposed such that its periphery presses against the base of the microscope stage. 
   The first eccentric member and the second eccentric member are rotatably supported on a common shaft. The shaft itself is mounted in a mounting block. A thrust member connected to the mounting block acts on a side surface of the first eccentric member. The thrust member prevents the first eccentric member from rotating when a fine adjustment is made through rotation of the second eccentric member. A force F is provided which continuously presses an inner peripheral surface of the first eccentric member against an outer peripheral surface of the second eccentric member. The guide part of the microscope stage slides in the recess defined by one housing shell. 
   When the eccentric means cooperates with the microscope stage, then this is referred to as a coarse and fine vertical adjustment of the microscope stage relative to the objective in the working position. When the eccentric means cooperates with the microscope objective, then this is referred to as a coarse and fine distance adjustment of the microscope objective relative to the microscope stage. 
     FIG. 1  shows microscope  2  in a perspective view. Microscope  2  includes a stand  4  on which are provided an eyepiece tube  6 , at least one objective  8  and a microscope stage  10  which is adjustable in height. In the embodiment shown in  FIG. 1 , microscope  2  is provided with a turret  9  which can carry several objectives. Using turret  9 , a particular objective  8  desired by the user can be moved into an optical axis  11  defined by microscope  2 . An eyepiece  7  is mounted in eyepiece tube  6 . Furthermore, an control knob  25  is provided at least on one side of stand  4 , said control knob  25  allowing microscope stage  10  to be adjusted in height relative to objective  8  in the direction of optical axis  11 . Moreover, a potentiometer wheel  13  projects through an opening  14  provided in one side of stand  4 . Potentiometer wheel  13  allows the user to control the brightness of a light source provided in the stand. Stand  4  of microscope  2  is composed of a first housing shell  15 , a second housing shell  16 , and a base member  17 . 
     FIG. 2  is a perspective inside view of the first housing shell  15  of stand  4  of microscope  2 . Microscope turret  9  is rotatably mounted on the second housing shell  16 . Using said microscope turret, one of a plurality of objectives  8  can be moved at a time into an optical axis  11  defined by the microscope. A prism holder  20  is provided above the objective turret  9 . Prism holder  20  carries a prism  21  which folds optical axis  11  into eyepiece  7  in a suitable manner. First housing shell  15  also carries microscope stage  10 . Microscope stage  10  is guided in a guide sleeve  22 , so that it can be moved in a direction along optical axis  11 . A locking pin  23  ensures that the movement of microscope stage  10  along optical axis  11  is limited, and at the same time provides linear guidance in a suitable manner. A mounting block  24  is provided below the guide sleeve  22  for microscope stage  10 . The mounting block carries at least one control knob  25  which is mounted on a shaft extending through mounting block  24 . Also mounted on shaft  26  is an eccentric means  50  which allows the microscope stage to be adjusted in height, i.e., in the direction of optical axis  11 . In addition, a limit switch  27  is provided in the lower region of eccentric means  50 , said limit switch interrupting power to a light source (see  FIG. 3 ) when microscope stage  10  is lowered. Moreover, first housing shell  15  has provided therein a potentiometer  32  which allows adjustment of the brightness of the light source. The potentiometer  32  is operated from outside the first housing shell  15  using the corresponding potentiometer wheel  13 . Holding members  34  for a battery holder  35  are formed on the inside of first housing shell  15 . As already mentioned, battery  35  is used to supply power to the light source provided in the microscope. 
   Microscope stage  10  is shown in detail in  FIG. 3 . Microscope stage  10  forms a unit and is composed of a sample support part  38  and a cylindrical guide part  40 . Cylindrical guide part  40  is closed at one end by a base  42  and at the other end by sample support part  38 . Guide part  40  has mounted therein a holder for an illumination module  39 . Illumination module  39  may include the electronics and light source. It has turned out to be particularly suitable to use an LED as the light source. Sample support part  38 , cylindrical guide part  40 , and base  42  form one unit. This ensures simple and inexpensive final assembly of the entire microscope  2 . A transparent element  38   a  is provided in sample support part  38 . Transparent element  38   a  allows passage of the light generated by illumination module  39 . In addition, transparent element  38   a  (diffusing screen) also provides protection against external influences. Illumination module  39  serves to generate white light. The white light is emitted by at least one light-emitting diode  39   a  mounted on illumination module  39 . The diffusing panel ensures a homogeneous distribution of the light. Illumination module  39  rests against lower circumferential step  40   b  of guide part  40 . Guide part  40  is further formed with a circumferential step  40   a  which is located at the end opposite base  42  and used for connecting sample support part  38  to guide part  40 . A spring  43  is disposed on the base of guide part  40  to provide a restoring force for microscope stage  10 . It is obvious that such a spring must be provided on the microscope objective or on the microscope turret when the change in distance between the microscope stage and the microscope objective is accomplished only by movement of the microscope objective or of the microscope turret along the optical axis. Also provided on base  42  of guide part  40  is a sliding plate  44  which reduces friction between eccentric means  50  and base  42 . 
     FIG. 4  is a perspective view illustrating the height adjustment device for microscope stage  10 . The height adjustment device includes a mounting module  24  which is mounted in housing shell  15 . Mounting module  24  supports a shaft  26  which carries a control knob  25  on each of the two sides of mounting module  24 . Shaft  26  can be rotated by means of control knob  25 . Mounting module  24  is U-shaped and carries an eccentric means  50  within the open portion of the U. Eccentric means  50  is formed with an outer surface  51  which is in operative connection or contact with base  42  of microscope stage  10 . Eccentric means  50  includes a first eccentric member  50   1  and second eccentric member  50   2 . First eccentric member  50   1  and second eccentric member  50   2  are both mounted on shaft  26 . First eccentric member  50   1  has formed thereon a first stop  52  and a second stop  53 . First stop  52  and second stop  53  cooperate with a pin  54  formed on the second eccentric member  50   2 . Also provided on mounting module  24  is an adjustable thrust member  56  which presses against first eccentric member  50   1 . The purpose of thrust member  56  is to limit the rotary movement of first eccentric member  50   1  in both directions. Because of this, rotation of second eccentric member  50   2  generates only a lifting force on first eccentric member  50   1 , thus effecting the fine vertical adjustment of microscope stage  10 . The coarse adjustment of microscope stage  10  can be done using first eccentric member  50   1 , while the fine adjustment of microscope stage  10  can be accomplished by rotating second eccentric member  50   2 . When pin  54  of second eccentric member  50   2  abuts against one of stops  52  or  53  of first eccentric member  50   1  and control knobs  25  are rotated, then the coarse distance adjustment of microscope stage  10  is effected. When pin  54  of second eccentric member  50   2  can move freely between stops  52  and  53  of first eccentric member  50   1 , then the fine vertical adjustment of microscope stage  10  is performed. 
     FIG. 5   a  shows eccentric means  50  in operative connection with base  42  of microscope stage  10 . In  FIG. 5   a , the microscope stage is shown in a lowered position. First eccentric member  50   1  has a peripheral surface  51  which is always in contact with base  42  of the microscope stage, irrespectively of the position of the microscope stage. The first eccentric member  50   1  is formed with a hole  55 , in which second eccentric member  50   2  is mounted. Second eccentric member  50   2  is formed with a pin  54  which is movable between a first stop  52  and a second stop  53 . First stop  52  and second stop  53  are formed on a side surface  60  of first eccentric member  50   1 . A force F biases the microscope stage with respect to eccentric means  50  in such a manner that eccentric means  50  always bears with its peripheral surface  51  against base  42  of the microscope stage. 
     FIG. 5   b  illustrates the situation after a maximum vertical adjustment  70  has been made by rotating eccentric means  50 . The maximum vertical adjustment  70  is accomplished by means of the coarse distance adjustment. At the beginning of the coarse distance adjustment, pin  54  of second eccentric member  50   2  rests against one of stops  52  or  53  of first eccentric member  50   1 . Further rotation causes first eccentric member  50   1  to rotate about shaft  26 . The maximum coarse distance adjustment provided by first eccentric member  50   1  is determined by the degree of eccentricity of first eccentric member  50   1 . 
     FIG. 5   c  shows a maximum vertical adjustment  72  provided by the fine vertical adjustment. The fine vertical adjustment is effected by the movement of pin  54  of second eccentric member  50   2  between stops  52  and  53 . When pin  54  moves between stops  52  and  53 , thrust member  56  (see  FIG. 4 ) prevents rotation of first eccentric member  50   1 . Thus, since force F continuously presses first eccentric member  50   1  lightly against second eccentric member  50   2 , the relative small height adjustment  72  is produced, it being possible for said small height adjustment to be accomplished without any play. 
   In the following, specific dimensions of the height adjustment device will be disclosed. However, it will be obvious to those skilled in the art that this is only a specific example, and that any modifications thereof are within the ordinary skill of one in the art. When the eccentricity of first eccentric member  50   1  is selected to be 1.8 mm, the maximum adjustment sensitivity obtained is approximately 0.033 mm/degree, given a manufacturing tolerance of, for example, +/−0.1 mm. This allows trouble-free focusing with an objective having a magnification of many times, such as with a 4× and 10× objective. After rotating first eccentric member  50   1  by 180°, a maximum vertical travel of 3.6 mm+/−0.2 mm is possible. If first eccentric member  50   1  has a useful working range, or range of rotation, from 0 to 143°, the resulting vertical adjustment  70  is at least 3 mm. It should be considered that when focusing with a 40× magnification objective, the user may very quickly move out of the depth-of-field range by an estimated 5° when using first eccentric member  50   1 . (i.e., the coarse distance adjustment). It is then desired that the difference in vertical travel resulting in the case of the 5° be able to be traveled back using second eccentric member  50   2  to allow for comfortable focusing. In order to accomplish this comfortable focusing, pin  54  of second eccentric member  50   2  is moved between stops  52  and  53 . This is indicated by arrow A in  FIG. 5   c . Thus, in the worst case, one must be able to travel about 0.165 mm using second eccentric member  50   2 . This is achieved when the eccentricity is about 0.140 mm and the working range is defined to be from 46° to 136°. Then, the maximum adjustment sensitivity provided by second eccentric member  50   2  is about 2.3 m/degree. Vertical adjustment  70  provided by first eccentric member  50   1  and vertical adjustment  72  provided by second eccentric member  50   2  add up to a total vertical travel of about 3.2 mm. 
   The present invention is not limited to the exemplary embodiment described herein.