Abstract:
An optical observation apparatus includes: an optical system which produces an image of an object being observed and a video device ( 7 ) for recording the image and producing an image signal. The video device ( 7 ) includes a first memory ( 71 ) for temporarily storing the image signal, a second memory ( 73 ) in data communication ( 77 ) with the first memory ( 71 ), and a control device ( 75 ) in communication ( 76 A,  76 B) with both memories ( 71, 73 ) for controlling the storage procedure in the first memory and data transfer from the first to the second memory. The control device ( 75 ) controls the storage procedure and the data transfer so that overwriting of such data already stored for a given period of time in the first memory ( 71 ) is effected and that transfer of the content of the first memory ( 71 ) to the second memory ( 73 ) takes place as a reaction to a trigger signal.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention concerns an optical observation apparatus, in particular an operation microscope, with a video device. 
   2. Description of the Related Art 
   Optical observation apparatuses such as for example microscopes, telescopes or endoscopes are used for example to view objects which are small, far away or which involve difficulties in access. In such an apparatus the objects are frequently reproduced by means of an optical system which in the simplest case can be an objective lens, in the form of an intermediate image on an image plane, referred to as the intermediate image plane. That intermediate image can be viewed on a magnified scale by means of an eyepiece. 
   Often however there is a wish to subject the intermediate image to electronic analysis. In addition, it is frequently desirable for the intermediate image to be made accessible not only to a single viewer but a plurality of viewers at the same time. In order to permit simultaneous viewing of the intermediate image by a plurality of viewers, the intermediate image can be recorded by a camera in analog or digital form and the recorded image can be displayed on a monitor or a plurality of monitors. In addition in particular recording the intermediate image by means of a digital camera permits electronic analysis of the intermediate image. A microscope which is combined with a video camera and in which the intermediate image is recorded by the image sensor of a video camera is described for example in JP 910 28 99 A. 
   While working with an optical observation apparatus which is equipped with a video device, many users want to record images of the situations being observed, for documentation purposes. Frequently however a situation arises only over a short period of time and also can no longer be reconstructed after that period of time has elapsed. For example, it is usual for surgeons to record images for scientific purposes during an operation. In that case however it frequently happens that the surgeon carrying out the procedure is too busy, during the operation, to immediately cause a situation which arises to be recorded, so that the situation can only be incompletely recorded or often cannot even be recorded at all. Frequently the situation can also no longer be reconstructed in the desired manner, for image recording thereof at a later time. Complete documentation of such situations is therefore not possible with the optical observation apparatuses in accordance with the state of the art. 
   Therefore the object of the present invention is to provide an improved optical observation apparatus which in particular can be an operation microscope or an endoscope and which simplifies documentation of the observed situation for the user. 
   SUMMARY OF THE INVENTION 
   An optical observation apparatus according to the invention includes: an optical system which produces an image of the object being observed and a video device for recording the image and for producing an image signal representative of the image. It is distinguished in that the video device includes a first memory for temporary storing the image signal, a second memory which is in data communication with the first memory, and a control device which is in control communication with both memories for controlling the storage procedure in the first memory and a data transfer from the first to the second memory. The control device is adapted to control the storage procedure and the data transfer in such a way that overwriting of such data which are stored in the first memory and which are already stored for a given period of time in the first memory is effected and that transfer of the content of the first memory to the second memory takes place as a reaction to a trigger signal. Preferably the entire content of the first memory is transferred into the second memory, but it is also possible for only a part of the memory content to be transferred into the second memory, whereby the amount of data to be transferred can be reduced, in particular when dealing with a relatively large first memory. All storage media which are suitable for recording the image signal can be used as the first or second memory. In addition the memories do not need to be physically separate memories. They can also be embodied in the form of a common physical memory which is only logically divided into a first and a second memory, that is to say in a first and a second memory region. 
   The configuration of the optical observation apparatus of the invention makes it possible for the object which is being observed to be continuously recorded without assistance from the user, and put into intermediate storage in the first memory. Data which have already been stored in the first memory over a predetermined period of time, for example the oldest recordings in the first memory, are in that case respectively overwritten by fresh data, for example a new recording. If now for example during an operation a situation which the surgeon conducting the procedure would like to record occurs, he can still secure the recording of the situation during the entire period of time in which it is stored in the first memory, by causing transfer preferably of the entire content of the first memory into the second memory. If the images are in intermediate storage in the first memory for example for five minutes, then the first image recorded of the situation is erased again five minutes after it was recorded. Therefore the user of the optical observation apparatus still has five remaining minutes to trigger transfer into the second memory. In particular recording of a situation which occurs only briefly can still be secured in that way even if the situation is already past. 
   In order to guarantee transfer of the data from the first memory to the second memory as quickly as possible, it is advantageous if the data communication between the first and second memories is designed for transmission at a high data rate. It is also advantageous if the second memory has a memory capacity which is at least twice as high as that of the first memory so that it permits the storage of a plurality of transfers from the first memory. That can increase the period of time before the second memory is full so that the optical observation apparatus is ready for use in one piece over a longer period of time, that is to say it is ready for transfer of recordings which are in intermediate storage in the first memory, to the second memory. 
   The duration of the operational readiness of the optical observation apparatus can be further increased if, instead of being in the form of a fixedly installed memory, the second memory is in the form of a replaceable memory. As soon as the second memory is full it is replaced. After a relatively short period of time involved in changing the second memory, regular operation of the optical observation apparatus can be continued. However, no transfer of the content of the first memory to the second memory can take place during the operation of changing the second memory. In order to permit a transfer of data even during the period of the change, it is possible to provide as a further intermediate memory a third memory whose memory capacity corresponds at least to that of the first memory. If, during the memory change procedure, the recording of a situation is to be transferred from the first memory to the second memory, the control device causes intermediate storage to firstly take place in the third memory. As soon as a fresh second memory has been fitted the control device then causes the content of the third memory to be transferred to the second memory. 
   The optical system of the optical observation apparatus can be a stereoscopic optical system. The image produced by the optical system then comprises two stereoscopic partial images and the video device comprises two first and two second memories, a respective one for each stereoscopic partial image. In particular the optical system for each stereoscopic partial image can include its own observation channel, wherein a first memory and a second memory are associated with each observation channel. 
   The video device can include as the image source both a video camera which records images in a video frequency and also a still camera, in particular with a high resolution, which records individual images only with a frequency below 10 Hz. 
   In a particular configuration of the invention the optical observation apparatus is an operation microscope while in an alternative embodiment it is an endoscope. 
   Further features, properties and advantages of the present invention are described hereinafter with reference to the accompanying drawings, by means of detailed embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a first embodiment of the optical observation apparatus according to the invention. 
       FIG. 2  shows a first embodiment of the video device. 
       FIG. 3  shows a second embodiment of the video device. 
       FIG. 4  shows a second embodiment of the optical observation apparatus according to the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An operation microscope is diagrammatically shown in  FIG. 1 , as a first embodiment of the invention. The Figure represents a section taken along the optical axis OA of the operation microscope. The Figure shows an object  1  of which the image is to be produced, an optical system  2  with an achromatic objective lens  3  and further lenses  6  (not to be described in greater detail), as well as an intermediate image  5  of the object  1 , which is produced by the optical system  2  in an intermediate image plane  4 . 
   The operation microscope further includes a video device  7  with an active camera surface  11 . The active camera surface  11  can either be the surface of a camera objective lens which produces the intermediate image  5  on a sensor surface, for example a CCD chip, of the video device  7 , or the sensor surface itself. In the latter case, the intermediate image  5  is recorded directly with the sensor surface. 
   The video device  7  is shown in  FIG. 2  in the form of a simplified block circuit diagram. Elements which are not required to understand the invention have been omitted for the sake of simplicity. The video device  7  includes a first memory  71  and a second memory  73 . The two memories  71 ,  73  are connected together by way of a data line  77  with which data can be transferred, preferably at a high data rate, from the first memory  71  to the second memory  73 . The first memory  71  is further connected by way of a further data line  78  to the sensor surface  79  of the video device  7 . The image signal is transferred from the sensor surface  79  into the first memory by way of the data line  78 . The video device  7  further includes a control unit  75  which is connected by way of control lines  76 A,  76 B and  76 C to the sensor surface  79 , the first memory  71  and the second memory  73 . 
   The first memory  71  is a short-term memory in which an image recorded by the sensor surface  79  is stored for a given period of time which can be any, possibly adjustable, period of time, for example between  30  seconds and ten minutes, preferably between two and five minutes. In this case, the first memory  71  is of such a size that it can store all images which are recorded during that period of time. The second memory  73  in contrast is a long-term memory in which the stored images are not automatically overwritten by new images. Preferably the second memory  73  is of a replaceable nature so that, when it is full, that is to say when it no longer offers any storage space, a new second memory  73  can be fitted. The usual replaceable storage media such as for example floppy discs, tapes or Smart Media cards can be used as the replaceable second memory  73 . In addition the second memory  73  is further preferably of such a size that it can store a multiple of the content of the first memory  71 . 
   Control of the video device is effected in such a way that, during operation of the optical observation apparatus, the image data recorded by the sensor surface  79  are continuously transferred to the first memory  71  by way of the control line  78 . When that happens, in each case the oldest image data stored in the first memory  71  are overwritten by freshly recorded image data. Now, by way of a trigger button or other suitable trigger element (not shown), the user can cause the control unit  75  to output control signals by way of the control lines  76 B and  76 C, to the first and second memories  71 ,  73 , which cause the entire content of the first memory  71  to be transferred to the second memory  73 . 
   If the video device is of such a design that only a part of the content of the first memory  71  is transferred to the second memory  73 , the arrangement may include a device for setting or selecting that part of the memory content, which is transferred to the second memory  73  in response to actuation of the trigger button. If the duration of storage in the first memory  71  is sufficiently long, selection of the part of the memory content which is to be transferred can be effected subsequently, that is to say after recording of the image data and storage thereof in the first memory  71 , but before the erasure thereof from the first memory  71 , which is caused by the passage of time. If in contrast the image data are only stored in the first memory  71  over a relatively short period of time before they are erased again so that there is no time remaining for subsequent selection, selection is preferably effected automatically on the basis of a pre-setting implemented prior to the commencement of use of the optical observation apparatus. 
   After the end of use of the optical observation apparatus or after removal of the second memory  73  the images stored in the second memory  73  can be transferred for the purposes of archiving onto a further storage medium, for example a magnetic tape, a CD or a DVD. Prior to the next use of the second memory  73 , its memory content is then erased. By means of a suitable control routine, it is also possible for the content of the second memory  73  to be read out, in on-going operation of the optical observation apparatus, so that there is no need to effect a change in the second memory  73 . 
   The two memories permit subsequent storage of a situation in the form of an image or an image sequence. If for example a surgeon who is working with an apparatus according to the invention wishes to store an image or an image sequence, he triggers transfer of the content of the first memory into the second memory. He can also still trigger transfer after the situation has occurred and possibly even still after the situation is past. That is possible as the image or images of the situation are stored in the short-term memory at any event for the given period of time without activity in that respect on the part of the surgeon and is or are kept in readiness for transfer into the long-term memory. The surgeon therefore has time firstly to bring to a close his other and more important tasks, for example a step in the surgical operation procedure, before he triggers transfer into the long-term memory. 
   A particular configuration of the video device with a replaceable second memory is shown in the form of a block circuit diagram in  FIG. 3 . The illustrated embodiment differs from that shown in  FIG. 2  only insofar as there is a third memory  80 , in addition to the first memory  71  and the second memory  73 . The third memory  80  is connected by way of data lines  81  and  82  both to the first and also to the second memory and has a storage capacity which corresponds at least to the storage capacity of the first memory  71 . In addition it is connected by way of a control line  83  to the control unit  75 . In other respects the configuration shown in  FIG. 3  does not differ from that shown in  FIG. 2 . 
   In the usual recording mode of the optical observation apparatus the third memory  80  does not perform any function. Image data from the first memory  71  are written directly to the second memory  73  by way of the data line  77  as a reaction to a trigger signal. The situation is different if the trigger button is pressed while a change of the second memory  73  is taking place, that is to say if no second memory  73  is available for storing the data transferred from the first memory. In that case, by way of the control lines  76 B and  83 , the control device  75  sends the first memory  71  and the third memory  80  control signals which cause the content of the first memory  71  to be transferred to the third memory  80  by way of the data line  81 , instead of to the second memory  73 . As soon as a second memory  73  with adequate free storage capacity has been fitted into the video device  7  again, the control device  75  delivers control signals to the second memory  73  and the third memory  80 , and those control signals cause the image data transferred from the first memory  71  to the third memory  80  to be forwarded to the second memory  73 . 
     FIG. 4  diagrammatically shows a further embodiment of the optical observation apparatus according to the invention, in the form of a stereoscopic operation microscope in which a video device according to the invention is used. Two partial images which represent the object  1  being viewed, from different angles of view, are produced in a stereoscopic microscope. 
     FIG. 4 , like  FIG. 1 , represents a view in section taken along the optical axis of the operation microscope. The stereoscopic operation microscope includes two observation channels  20   a  and  20   b  which each include an optical system  2   a ,  2   b  with an achromatic objective lens  3   a ,  3   b  and further lenses  6   a ,  6   b  (not to be described in greater detail here). The image of the object  1  is produced in an intermediate image plane  4 , by the optical systems  2   a  and  2   b . A common achromatic objective lens  19  is connected upstream of the two observation channels  20   a ,  20   b.    
   For the purposes of recording the stereoscopic partial images, each observation channel  20   a ,  20   b  includes its own video device  7   a ,  7   b , control of the two video devices taking place synchronously. The video devices  7   a ,  7   b  used can be video devices as have been described with reference to  FIGS. 2 and 3 . Alternatively it is also possible to use a common video device for both observation channels  20   a ,  20   b . In addition, the stereoscopic operation microscope can also be designed in such a way that there is only one observation channel and the stereoscopic partial images are produced by that observation channel alternately in respect of time. It will be appreciated that, in that case, there only needs to be one video device.