CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    The present application is a continuation-in-part of pending U.S. application Ser. No. 09/284,443, filed on Apr. 14, 1999, which corresponds to PCT Application No. PCT/DE97/02218, filed Sep. 26, 1997, which claims the benefit of German Application No. 196 43 558.7, filed on Oct. 24, 1996. U.S. application Ser. No. 09/284,443, PCT Application No. PCT/DE97/02218, and German Application No. 196 43 558.7 are each incorporated by reference herein, in their entirety. 
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention relates to a microscope having a proximity sensor and a control circuit for automatically switching electrical microscope functions.  
           [0004]    2. Description of Related Art  
           [0005]    Modern microscopes are distinguished, inter alia, by the fact that the various microscope functions are designed in such a way that they can be controlled electrically and/or by electric motor. For example, known electrically operating switching and adjusting functions are autofocusing devices, motor-driven adjustments of the specimen stage, electrically switchable shutters, filters or phase-retarding rings etc. A microscope in which these functions are realized is described, for example, in DE 42 31 379 A1.  
           [0006]    In this microscope, the operating elements for the switching functions are grouped together in an ergonomic way on a control console and have to be manually selected by the observer. This has proved successful in practice. However, due to the large number of electrically controllable microscope functions, the area around the microscope, and consequently also the specimen to be observed, is exposed to heat. In particular when using lighting devices with very high lamp outputs, such as for example gas-discharge lamps, the specimen may be damaged by the heat to which it is exposed. Particularly sensitive specimens are, for example, living cells or else specimens in fluorescence microscopy, which may be destroyed by high luminous intensities.  
           [0007]    The observer is in these cases obliged to deactivate or switch the switchable function manually by means of the control console. It has been found in practice that, for many applications, this procedure is always inconvenient if, for example, the microscope function is not required for a short time.  
           [0008]    In the case of photographic cameras, it is known to arrange on or in the viewfinder a sensor which activates or deactivates the entire main circuit of the camera according to whether or not the photographer is looking into the viewfinder. In the case of cameras, this is only with the intention of saving the battery.  
           [0009]    In the case of microscopes it is also the case that the main circuit must not be interrupted, since this would necessitate complete re-setting of the microscope when the functions were activated once again. In addition, the lifetime of lamps is reduced considerably by frequent switching on and off.  
           [0010]    WO 96/13743 A1 discloses a microscope with a sensor and a control device, in which the microscope functions can be controlled contactlessly by the position of the observer&#39;s pupil. A device for detecting the position of the pupil is equipped with a switching element, which interrupts the measuring routine as soon as the device for detecting the position of the pupil cannot perceive a pupil.  
           [0011]    Furthermore, DE 44 46 185 A1 discloses a laser scanning microscope with a UV laser and with an optical fiber, in which the damage caused by UV light is reduced by providing between the laser and the optical fiber a scanning shutter, which exposes the optical fiber only during scanning.  
         BRIEF SUMMARY OF INVENTION  
         [0012]    It is therefore an object of the present invention to develop a known microscope with simplest possible means in such a way that, independently of the manual operation by a person, the electrical and/or electric-motor-driven microscope functions can also be performed fully automatically, and at the same time damage to sensitive specimens or impairment of the image quality is reduced.  
           [0013]    This object is achieved according to the invention by the features specified herein. According to an embodiment of the present invention, a microscope includes a viewing tube for the visual examination of a specimen and an illumination device for illuminating the specimen. The microscope comprises a control circuit housed in the microscope for activating electrical microscope functions and a proximity sensor connected to the control circuit and fitted on the microscope for responding to the absence of an observer viewing the specimen through the viewing tube. The control circuit includes an adjustable time-delay logic element located in the control circuit for delaying switches of the microscope functions such that the microscope functions are switched after the observer is absent for a predetermined time period. Further advantageous developments of the invention are also described.  
           [0014]    The arrangement of a proximity sensor on or in the eyepiece and its connection to the control circuit make it possible for microscope functions to be controlled fully automatically. These functions are initiated whenever the user looks into the eyepiece on the tube, or if said user does not look in. This fully automatic control has proved successful in particular in fluorescence microscopy for swiveling an occulting shutter in and out of the illuminating beam. This avoids a gradual bleaching of the specimen (fading effect) being caused by unnecessary illumination.  
           [0015]    The obscuring of the illuminating light by an occulting shutter or by regulating the lamp voltage is of course also advisable if living tissue or cells are to be observed and/or worked on using the microscope.  
           [0016]    The proximity sensor is advantageously also used in the case of microphotographic exposures. In this case, to avoid the incidence of extraneous light through the eyepiece, an occulting shutter is swiveled into the observing beam. Of course, it is also possible to activate a beam-splitting mirror by means of the proximity sensor and the control circuit, so that all of the light coming from the specimen can be used for the photographic exposure.  
           [0017]    Thus, according to an embodiment of the present invention, a microscope includes an observation beam path, an observation tube for an observation of a specimen, a control circuit for activating electrical microscope functions, and an illumination system for illuminating the specimen. The microscope further includes an eyepiece coupled to the observation tube for observing the specimen, a camera, a movable mirror positionable in the observation beam path, and a proximity sensor coupled to the observation tube and the control circuit. Upon the approach of an observer to the eyepiece, the proximity sensor emits a signal. A position of the movable mirror corresponds to the signal of the proximity sensor and the observation beam path propagates to one of the observation tube and the camera based on the position of the movable mirror.  
           [0018]    A commercially available proximity sensor, forming a separate structural unit, may be used on the tube of the microscope. The proximity sensor may in this case be designed as a light sensor, such as for example as a reflection barrier, a forked light barrier, a passive infrared detector or an ultrasonic detector. A contact-sensitive switch may also be used as the proximity sensor.  
           [0019]    According to another embodiment, a microscope includes an observation beam path, an observation tube for an observation of a specimen, a control circuit for activating electrical microscope functions, and an illumination system for illuminating the specimen. The microscope further includes an eyepiece coupled to the observation tube for observing the specimen, a camera coupled to a photo-tube, a movable mirror positionable in the observation beam path, and a proximity sensor coupled to the observation tube. Upon the approach of an observer to the eyepiece, the proximity sensor emits a signal. The control circuit is coupled to the movable mirror and changes a position of the movable mirror corresponding to the signal of the proximity sensor. The observation beam path propagates to one of the observation tube and the camera based on the position of the movable mirror. In addition, the microscope can include an actuator coupled to the moveable mirror and the control circuit to place the movable mirror in a first position which allows propagation of the observation beam path into the eyepiece and a second position which allows propagation of the observation beam path into the photo-tube. Preferably, the actuator is one of a motor and an electromagnet.  
           [0020]    Also, according to this embodiment, the microscope can include an adjustable time-delay logic element coupled to the control circuit, responsive to the presence and absence of the signal from the proximity sensor, for delaying switches of the microscope functions such that the microscope functions are switched after the observer is absent for a first continuously adjustable time period to protect the specimen and to prevent frequent switching of the illumination device when the observer is momentarily absent from an observing position. Further, the control circuit can provide a trigger for a first change of the position of the movable mirror upon the presence of a continuous signal from the proximity sensor for a second continuously adjustable time period of about 1 second to about 1 minute.  
           [0021]    Other advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0022]    The invention is explained in more detail on the basis of exemplary embodiments with the aid of schematic drawings, in which  
         [0023]    [0023]FIG. 1 shows a schematic diagram of the microscope according to an embodiment of the invention, and  
         [0024]    [0024]FIG. 2 shows an example carrier plate that includes three prisms to switch viewing in accordance with an alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    [0025]FIG. 1 shows a microscope  1  with a tube  2  and an eyepiece  3 . The microscope  1  has, furthermore, an objective turret  9  with an objective  10  and a microscope stage  11  for the specimen  12  to be observed by means of an observing beam  13 . The specimen  12  is illuminated by means of a light source  14 , arranged in the microscope  1 , the associated illuminating beam  15  and the deflecting mirror  19 . The light source  14  is electrically connected to a control device or circuit  7  by a line  21 .  
         [0026]    Arranged on the eyepiece  3  is a proximity sensor  4 , which emits IR rays  5  and receives again reflected IR rays  6 . Arranged in the microscope  1  is the control circuit  7 , which is connected to the proximity sensor  4  by an electrical line  8 .  
         [0027]    An optical element  20  is provided in the observing beam  13  for deflecting the light coming from the specimen  12  into the eyepiece  3 . Optical element  20  is preferably a reflecting element that is rotatable and/or laterally displaceable in the observing beam  13 . Optical element  20  can be, e.g., a prism, a switchable prism, a mirror, preferably highly reflective, or other reflective optical element, as discussed below. To avoid the incidence of extraneous light through the eyepiece  3 , also arranged in the observing beam  13  is an eyepiece shutter  16 , which is designed in such a way that it can be moved by a motor  17 . The motor  17  is connected to the control circuit  7  by the control line  18 .  
         [0028]    A switchable occulting shutter  22 , which is designed in such a way that it can be moved in the direction of the double-headed arrow by means of a motor  23 , is provided in the illuminating beam  15  for obscuring the illuminating light coming from the light source  14 . The motor  23  is connected to the control circuit  7  by an electrical line  24 .  
         [0029]    The proximity sensor  4  constantly emits IR rays  5 . These rays  5  are reflected from an observer (not included in the representation) when said observer looks into the eyepiece  3 . The reflected rays  6  are received again by the proximity sensor  4 , the sensitivity of the sensor input to the reflected IR rays being of a preselectable design. The reception of IR rays  6  causes a corresponding signal to be emitted by the proximity sensor  4  via the control line  8  and to be registered in the control circuit  7 . In this case, corresponding signals are emitted from the control circuit  7  via the two lines  18  and  24  to the two servo motors  17  and  23 . The eyepiece shutter  16  is then swiveled out of the observing beam  13  by means of the motor  17 .  
         [0030]    In analogy with this, the occulting shutter  22  is also brought out of the illuminating beam  15  by means of the motor  23 .  
         [0031]    If no IR rays  6  reflected from the observer are received by the proximity sensor  4 , a corresponding signal is triggered by means of the control circuit  7  and both the occulting shutter  22  and the eyepiece shutter  16  are brought back into the respective beam.  
         [0032]    If incandescent or halogen lamps are used in the microscope  1 , they can be supplied with current by means of the electrical line  21 , so that a dimming of the light source  14  is possible with the control circuit  7 . If no reflected IR rays  6  are received by the proximity sensor  4 , the light source  14  is dimmed. If IR rays are received, the lamp  14  can be operated again at the operating voltage or operating current.  
         [0033]    In the exemplary embodiment described, the “transmitted light” operating mode for the illuminating device is represented and described. It goes without saying that it is within the scope of the invention to use the proximity sensor in microscopes with a different type of illumination, such as for example reflected-light illumination or a combined reflected light/ transmitted light illumination.  
         [0034]    To avoid unnecessary frequent switching in the absence of the received IR signal, an adjustable time-delay logic  28  is provided in the control circuit. This achieves the effect that the switching pulses emitted to the two motors  17  and  23  are only emitted after an adjustable time period has expired. As mentioned above, the adjustable time period can be greater than a time that the observer momentarily is absent from the eyepiece (to prevent unnecessary switching on-and-off of the illumination source), and less than a time that corresponds to an amount of time where lengthy illumination of the sample may cause sample damage. For example, this time period can be from about 1-5 seconds to about 1 minute, depending on the sample being observed. If the particular sample is not as susceptible to damage via prolonged exposure, then the time period delaying the switching off of microscope functions can be set at a longer time. The adjustable time period can be preset by the user (before observation) using a time dial and/or a digital time interface  31  mounted on the microscope and coupled to the adjustable time delay logic element  28  and/or the control circuit  7 .  
         [0035]    It is of course within the scope of the invention for other microscope functions, such as for example an autofocusing device, a photographic device or electric consumers in general, to be switched by means of the proximity sensor and the control circuit.  
         [0036]    Accordingly, as mentioned above, an optical element  20 , such as a reflector (e.g., a mirror, prism, or switchable prism), can be utilized to alternate viewing between the eyepiece  3  and a camera  25 . For example, in the observation beam path  13  of the microscope  1 , a mirror  20  is disposed which is made so as to be moveable and/or displaceable by an actuator  27 , such as a conventional motor (e.g., a stepper motor) or an electromagnet. In the embodiment shown in FIG. 1, the mirror  20  can then deflect the light of the observation beam path coming from the specimen  12 , into the eyepiece  3  in one step position and, in another (step) position, the observation beam path propagates along the dotted line of FIG. 1 into the photo-tube  29 . The mirror  20  can be mounted on a base or carrier  32  that is laterally or rotatably displaceable to move the mirror  20  in or out of observation beam path  13 .  
         [0037]    Camera  25  can be a video camera or a conventional photographic camera that is mounted to the photo-tube  29 , or another type of camera. If a video camera is used, the camera  25  can be further coupled to a monitor  26  for observation of the camera image.  
         [0038]    Further, the signal emitted from proximity sensor  4  can be used as a basis for switching the position of the movable mirror  20 . For example, when an observer approaches the eyepiece  3 , the sensor  4  gives an “approach” signal to the control circuit  7 . The control circuit  7  is then activated and picks up a second continuously adjustable time period set through the adjustable time delay logic  28 . For example, this continuously adjustable time period can be selected via an interface on the microscope housing (similar to dial/interface  31 ) from about 1 second to about 1 minute. Preferably, this adjustable time period is set at about 3 seconds. In an example operation, when the sensor  4  continuously supplies the “approach” signal for at least 3 seconds, the movable mirror can be switched into the first position, thus allowing observation of the image through the eyepiece  3 . If the “approach” signal from the proximity sensor  4  is not continuous for the selected (e.g., 3 seconds) time period, the movable mirror is not switched. Thus, not until after 3 seconds and the continuous presence of the signal during this period of time does the motor become activated by the control circuit  7  and the mirror  20  is brought to the first position, allowing the observation beam path  13  to be deflected into the eyepiece  3 .  
         [0039]    In this example operation, if the observer is no longer looking into the eyepiece  3 , the sensor  4  stops giving a signal. In a manner similar to that already described, in the case of the “approach” signal, after 3 seconds of a continuous absence of the signal from sensor  4 , the mirror  20  is changed back to the second position, and the image can again be observed by the camera  25  and/or the monitor  26 . The time period corresponding to a continuous presence of the observer at the eyepiece (before triggering a change in position of the mirror to allow eyepiece viewing) and the time period corresponding to a continuous absence of the observer (for the purpose of switching the mirror position to provide camera observation) can be the same or a different amount of time.  
         [0040]    Alternatively, variations of the above device include: the photo-tube  29  being disposed in another region of the microscope, such that when the mirror  20  is in a first position, it deflects the observation beam path  13  into the eyepiece  3 , and when mirror  20  is in a second position (e.g., rotated to a different angle), it deflects observation beam path  13  into the photo-tube  29 . In another alternative embodiment, when the mirror  20  is in a first position, the observation beam path  13  is deflected to the photo-tube  29 , and when mirror  20  is in a second position, observation beam path  13  passes to the eyepiece  3  (here, the eyepiece  3  and the photo-tube  29  can be switched in position than as that shown in FIG. 1). In a further alternative embodiment, the mirror  20  is a prism that is displaceable in or out of observation beam path  13 . In yet another alternative embodiment, a prism  20  remains fixed in position, and an additional mirror (not shown) is positionally displaceable in the observation beam path  13  at a location along observation beam path  13  between prism  20  and turret  9 , such that in a first position, observation beam path  13  passes to the eyepiece  3 , and in a second position, the additional mirror deflects observation beam path  13  towards the photo-tube  29 . In yet another alternative embodiment, two or more prisms mounted on a carrier or base  32  can be utilized. The carrier  32  is coupled with the motor  27  to bring one of the prisms into a desired position (corresponding to the desired viewing position selected). For example, as illustrated in FIG. 2, a first prism  20 A (in a first position) can be used to deflect the observation beam  13  into the eyepiece, a second prism  20 B (in a second position, and oriented to deflect the beam at an angle out of the plane of the drawing) can be used to “deflect” the observation beam  13  to the video camera, and a third prism  20 C (in a third position) can be used to deflect the observation beam  13  to, e.g., a second camera, a second eyepiece, a photographic camera, or a photosensitive detector.  
         [0041]    The ability to delay the changeover from video/photographic observation to eyepiece observation is especially preferred when microscope  1  is configured as a fluorescence microscope. Such changing-over is preferred when very little light is available, as is the case with some types of fluorescent illumination because simultaneously splitting the light to an eyepiece and the camera may result in insufficient light propagating to the eyepiece and/or the camera. In addition, it is preferred that element  20  is a highly reflective mirror or prism, e.g., a metal-coated mirror (having about  85 % or greater reflectivity) because partially reflective mirrors do not provide enough image light for a more resolved image when very little light may be available. The ability to observe the sample with the eyepiece when desired is preferred because the eyepiece may provide the maximum resolution of the image, whereas photographic cameras or video cameras may not provide this maximum resolution.  
                                         List of Parts by Reference Number                                1.   microscope       2.   tube       3.   eyepiece       4.   proximity sensor       5.   emitted IR rays       6.   reflected IR rays       7.   control device       8.   electrical line 4-7       9.   objective turret       10.   objective       11.   microscope stage       12.   specimen       13.   observing beam       14.   light source       15.   illuminating beam       16.   eyepiece shutter       17.   motor       18.   control line 7-17       19.   deflecting mirror       20.   optical element, reflector       21.   electrical line 7-14       22.   occulting shutter       23.   motor       24.   electrical line 7-23       25.   camera       26.   television       27.   actuator (motor or electromagnet)       28.   adjustable time relay logic       29.   photo-tube       31.   time delay interface       32.   carrier
A microscope with a viewing tube for visual observation of a specimen by an observer, with a control circuit for controlling electrical and/or electro-motor-driven microscope functions, and an illuminating device for illuminating the specimen to be observed is described. The control circuit is connected to a proximity sensor installed on the microscope, which responds to the presence of the observer to the viewing tube. The control circuit includes an adjustable time-delay logic element located in the control circuit for delaying switches of the microscope functions such that the microscope functions are switched after the observer is absent for a predetermined time period.