Abstract:
The invention relates to a knife holder ( 100 ) having a blade changing apparatus ( 102 ). The knife holder has a first blade receptacle ( 111 ) defining a cutting position, a securing device ( 130, 141, 142 ) for securing a blade ( 201 ) received in the first blade receptacle ( 111 ), a second blade receptacle ( 112 ) defining an output position, and an ejection device ( 141, 143, 144   a ) for ejecting a blade ( 201 ) received in the first blade receptacle ( 111 ) out of the first blade receptacle ( 111 ). The first and the second blade receptacles are arranged in the knife holder in such a way that a blade ejected from the first blade receptacle ( 111 ) can travel by gravity into the second blade receptacle ( 112 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of German patent application number 10 2012 213 824.2 filed Aug. 3, 2012, the entire disclosure of which is incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The present invention relates to a knife holder having a blade changing apparatus for a microtome. 
     BACKGROUND OF THE INVENTION 
     Microtomes are used, for example, to prepare thin sections of tissue that can then be investigated microscopically. Microtomes have for this purpose a knife holder having a very sharp blade. Disposable blades have become established in particular in the laboratory sector, a blade being disposed of after a number of sectioning operations and replaced with a new blade. One such knife holder is described in DE 10 2004 051 974 A1. Here the blades must be changed manually. As an improvement, DE 10 2007 006 826 B1 describes a knife holder in which blade changing is assisted by a driver. New blades are taken out of a blade supply container in which a blade stack made up of multiple blades is received in spring-loaded fashion, and are slid into a blade receptacle. A used blade present in the blade receptacle is thereby pushed backward out of the blade receptacle and disposed of into a blade disposal container. This design requires a relatively large amount of space. The sliding out of the used blade can also be impeded, for example, by jamming or oversliding. 
     It is desirable to have available a blade changing apparatus that is improved in particular in this regard. 
     SUMMARY AND ADVANTAGES OF THE INVENTION 
     The present invention proposes a knife holder for a microtome, wherein the knife holder has a blade changing apparatus. 
     In a knife holder according to the present invention, a used blade no longer needs to be pushed out of the blade receptacle of the cutting position (hereinafter the “first blade receptacle”) by a new blade. Instead, it can be delivered by means of gravity, e.g. can fall or slide or slip out, into a blade receptacle of a disposal position (hereinafter the “second blade receptacle”). A new blade can then be slid into the unoccupied blade receptacle of the cutting position so that no risk of jamming or oversliding exists. The particular configuration also makes it possible for the used blade to be disposed of to the side on which the new blades are also located, so that the width of the knife holder can be reduced. Instead of three blade lengths as in the existing art, only two blade lengths are now needed. 
     A securing means, e.g. a clamping mechanism, for securing a blade in the first blade receptacle, and an ejection means, e.g. a movable lug, for ejecting a blade received in the first blade receptacle out of the first blade receptacle, are usefully connected to the same actuation means, e.g. to a lever, in order to be actuated thereby. 
     In a preferred embodiment, the first blade receptacle and the second blade receptacle are arranged vertically spaced apart in the knife holder. This is a particularly simple construction for utilizing gravity, without which, for example, a relative motion of the receptacles with respect to one another would be necessary, for example by rotating or tilting the knife holder. 
     The knife holder is preferably equipped with an external mounting location for a blade supply container that contains unused or new blades, and with a first, in particular automatic or manually actuated driver in order to convey a new blade out of the externally mounted blade supply container into the first blade receptacle. The external mounting location results in a defined position and orientation for the blade supply container, so that the insertion of a new blade into the blade receptacle can occur in particularly simple fashion via the first driver. This considerably reduces a risk of injury, since the user no longer needs to touch the blade. 
     The knife holder is preferably also equipped with an external mounting location for a blade disposal container, separated from the blade supply container, into which used or old blades are discarded, and with a second, in particular automatic or manually actuated driver in order to convey a used blade out of the second blade receptacle into the externally mounted blade disposal container. The external mounting location results in a defined position and orientation for the blade disposal container, so that the discarding of a new blade into the blade disposal container can occur in particularly simple fashion via the second driver. This considerably reduces a risk of injury, since the user no longer needs to touch the blade. 
     In order to minimize the installation space, an external mounting location is usefully located horizontally directly next to the associated blade receptacle. 
     Further advantages and embodiments of the invention are evident from the description and from the appended drawings. 
     It is understood that the features recited above and those yet to be explained below are usable not only in the respective combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention. 
     The invention is schematically depicted in the drawings on the basis of an exemplifying embodiment, and will be described in detail below with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING VIEWS 
         FIGS. 1 a  through 1 d    show various steps of a blade changing operation, with reference to a knife block of a knife holder according to a preferred embodiment of the invention, 
         FIG. 2  is a perspective view of elements of the blade changing apparatus in addition to the knife block, 
         FIG. 3  is a perspective view of the substantially complete knife holder with the blade changing apparatus, 
         FIG. 4  is a cross-sectional view of the knife holder in the region of the blade changing apparatus, and 
         FIG. 5  is a cross-sectional view of the knife holder in the region of the knife block. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The Figures are described below together and continuously, identical elements being labeled with identical reference characters. 
       FIGS. 1 a  to 1 d    show various steps or states of a blade changing operation with reference to a schematic depiction of a few elements of a knife holder  100 . The sequence of  FIGS. 1 a  to 1 d    corresponds to the sequence in time.  FIG. 2  shows knife holder  100 , with elements of a blade changing apparatus  101 , in a state according to  FIG. 1   c.    
       FIG. 3  is a schematic, perspective view of knife holder  100  with further elements for better clarity, and  FIGS. 4 and 5  each show a cross-sectional view through knife holder  100 . 
     A knife block  110  of a knife holder  100  is depicted, comprising in its upper region two steps  111  and  112  that each form a blade receptacle. Step  111  forms a first blade receptacle for a cutting position, and step  112  forms a second blade receptacle for a disposal position. A blade that is located in first blade receptacle  111  is labeled  200 . 
     Depicted at the same height, next to blade receptacle  111 , is a blade stack  210  that is usually received in a blade supply container (not depicted in  FIG. 1 ). As indicated by arrow  1 , a new blade has been delivered into first blade receptacle  111  by being slid out of the blade supply container. In this state only one blade is present in first blade receptacle  111 . 
     For disposal of the blade, it is firstly ejected out of first blade receptacle  111  as indicated by an arrow  2  in  FIG. 1 b    so that it can fall by gravity into second blade receptacle  112 . In this state only one blade is present in second blade receptacle  112 . 
     The next step of the blade changing operation is depicted in  FIG. 1 c   . A (new) blade  201  to be utilized is located in the blade stack, and the (old) blade to be disposed of is located in blade receptacle  112  for the disposal position. As indicated by an arrow  3 , blade  201  is then delivered into blade receptacle  111  and, as indicated by arrow  4 , blade  200  is delivered into a disposal container that, according to a preferred embodiment of the invention, is arranged on the same side as the blade supply container. The two conveying operations can be carried out simultaneously but also successively. One or both conveying operations can each be carried by a driver that engages into engagement openings that are depicted in the Figure as holes in the blade. 
     The final state is depicted in  FIG. 1 d   : new blade  201  is located in first blade receptacle  111  and can be secured there, and old blade  200  has been conveyed out of second blade receptacle  112  and can fall, for example, into a blade disposal container. 
       FIG. 2  shows the state according to  FIG. 1 c   ; schematically depicted to the left next to knife block  110  is a driver mechanism  300  of blade changing apparatus  101 , which mechanism comprises a first driver  301  for new blade  201  as well as a second driver  302  for old blade  200 . 
     The first and the second driver are coupled to a driving mechanism, embodied as a toothed linkage  303 , on which a driver actuation element  304  acts. Proceeding from the position shown in  FIG. 2 , upon actuation of driver actuation element  304 , by means of the drivers new blade  201  is conveyed to the right into first receptacle  111 , and old blade  200  is conveyed to the left out of second receptacle  112 . 
     First driver  301  possesses a driver spring plate  305  that can be moved back and forth by a driver toothed rack  306  and is mounted on a driver guide  307 . Second driver  302  is embodied substantially as a driver toothed rack having a blade stop  302   a , e.g. a pin, at its right end in  FIG. 2 . 
       FIG. 2  depicts a solution in which first driver  301  and second driver  302  are actuated simultaneously via the driving mechanism. Be it noted, however, that actuation successively is also possible in the context of the invention. 
       FIG. 3  is a schematic perspective depiction of knife holder  100 ;  FIG. 4  is a cross-sectional view through the knife holder. 
     Located on knife block  110  is a clamping plate  130  that can be clamped against knife block  110  by way of a securing mechanism connected to an actuation element  140 , so that a blade present in blade receptacle  111  can be secured. In the depiction, for example, the lever is in a zero position. An upward actuation of lever  140  results in a rotation of a cam  141  in such a way that a clamping bolt  142  pushes upward against clamping plate  130  located thereabove (not depicted in  FIG. 5 ), so that a blade becomes clamped in place in first blade receptacle  111 . 
     A downward actuation of lever  140  results in a rotation of cam  141  in such a way that a first ejector bolt  143  of an ejection means pushes outward against a second ejector bolt  144  of the ejection means, so that a tip  144   a  of second ejector bolt  144  pushes against a blade in first blade receptacle  111  and ejects it over the step. The blade can consequently fall into second blade receptacle  112  located therebelow. 
     The knife holder is embodied so that during introduction of a new blade  201  from the blade stack or blade supply container into first receptacle  111  via the first driver, a finger protector  150  that prevents injury from the moving blade is also slid out. Finger protector  150  can then be slid back again via a handle  151  in order to expose the blade in the blade position. 
       FIG. 4  furthermore depicts a blade supply container  410  externally mounted at a first external mounting location, as well as a blade disposal container  420  externally mounted at a second external mounting location, these together forming a blade dispenser. A blade stack  411  made up of a plurality of blades  412 ,  201  is received in blade supply container  410 , the uppermost blade being labeled  201 . Blade stack  411  is supported in a support block  413  that is impinged upon with spring force by a spring means embodied as leaf spring  414 . The spring force presses the support block upward so that uppermost blade  201  of the blade stack comes to rest in a removal position next to a removal opening. 
     The next blade to be removed is in this case always the uppermost one of blade stack  411 . It can be slid out of the removal position and out of blade supply container  410  through the removal opening, to the side, i.e. to the right in  FIG. 3 , and removed. Each blade  412 ,  201  of blade stack  411  comprises one or more engagement openings  418  into which first driver  301  can engage in order to push the blade out of removal opening  416  of the blade supply container. In order to enable access to blade  201  in the removal position, an access opening embodied as a slot  417  is provided in the upper side of blade supply container  410 . 
     Blade disposal container  420  is embodied here as a container open on its upper side. Blade disposal container  420  is embodied to receive used blades  422 , which are likewise received as a stack  421  in blade disposal container  420 . Blades to be disposed of fall from above into blade disposal container  420 . 
     Blade dispenser  400  comprises a detachable and reconnectable connecting means that detachably connects blade supply container  410  and blade disposal container  420  to one another. The connecting means is embodied here as a slide closure in the manner of a dovetail guide, such that the connection can be released and created by sliding containers  410  and  420  with respect to one another. In the embodiment depicted, the dovetail guide comprises interengaging flanges  431  on the underside of the blade supply container and  432  on the upper side of the blade disposal container. As a consequence, the result of connecting the blade supply container and the blade disposal container is also that the upper side of blade disposal container  420  becomes closed off. One or both flanges  431  of the dovetail guide can preferably also be used to externally mount the respective container on the knife holder. In this case the knife holder comprises corresponding flanges of a dovetail guide. 
     Once blade disposal container  420  has been fastened on blade supply container  410  by means of the dovetail guide, the used blades are securely received and can easily be disposed of together with the empty blade supply container. 
     Blade supply container  410  comprises multiple alignment means that are embodied as grooves  452  and/or lugs and serve to enable exact orientation (and preferably secure fastening) of blade supply container  410  on knife holder  100 . The knife holder preferably also comprises corresponding guides that interact with the alignment means of the containers, for example likewise lugs and/or grooves. 
     Blade supply container  410  furthermore comprises a bar  460  having a beveled end  461 , which bar can serve as a guide for used blades. Beveled end  461  forms an inclined plane with respect to the blade supply container surface. 
     As is evident in the cross-sectional view in  FIG. 4 , the bodies or main extension planes A of blades  201 ,  412  of blade stack  411  are arranged with respect to stack direction B at an angle α not equal to 90°. The angle α between A and B is in this case approximately 70°. This enables a space-saving arrangement of blade supply container  410  on the knife holder. For this purpose, support block  413  is embodied in cross section with a corresponding angle α between its upper side, on which the blade stack is supported, and the vertical axis of the blade supply container. Support block  413  is impinged upon from below with spring force by leaf spring  414 . The oblique placement of the blades in the blade supply container allows the horizontal installation space required for the blade supply container on the knife holder to be made smaller, since with a blade that extends approximately vertically, the blade supply container need not protrude horizontally but instead, as depicted, extends obliquely downward.