BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an observed image forming apparatus, and more particularly, to a structure of an electronic endoscope apparatus or a complex observation apparatus provided with a plurality of connector receivers for connecting a plurality of observation devices by way of connectors, wherein a cap is mounted to the connector receiver to which the observation device is not connected. 
         [0003]    2. Description of the Related Art 
         [0004]    The electronic endoscope apparatus can display an image of an object to be observed on a monitor, by taking an image of the object to be observed by a CCD (Charge Coupled Device) which is a solid body photographing element mounted on a scope (an electronic endoscope) for example, by supplying an image taking signal from this CCD to a processor unit, and by performing a determined process on the signal in an image processing circuit in this processor unit. The electronic endoscope apparatus of this type is so constructed that a plurality of scopes having different types of the CCD and different image taking systems can be connected to the processor unit. There is also a complex observation apparatus which is so constructed that as well as the aforesaid scopes, ultrasonic probes for taking ultrasonic images can be connected thereto. With this complex observation apparatus, it is possible to display and observe both an electronic endoscope image and an ultrasonic image. 
         [0005]    In  FIGS. 5A and 5B , there is shown a structure of the related-art electronic endoscope. As shown in  FIG. 5A , in an electronic endoscope  1 A of type A, for example, an optical connector  3  and an electric connector  4   a  in a square shape are connected to a processor unit  2 . With this optical connector  3 , a light guide for supplying light of a light source into the electronic endoscope  1 A, as an illumination light is connected to the processor unit  2 . The electric connector  4   a  is provided for the purpose of connecting a signal line for mainly transmitting an image signal and so on which has been obtained by the CCD or the like mounted on the electronic endoscope  1 A, to the processor unit  2 . 
         [0006]    Moreover, as shown in  FIG. 5B , in an electronic endoscope  1 B of type B, for example, the optical connector  3  and an electric connector  5   a  in a round shape are connected to the processor unit  2 . On the other hand, the processor unit  2  is provided with a connector receiver  4   b  in a square shape which is fit for the electric connector  4   a  in a square shape of the electronic endoscope  1 A of type A, and a connector receiver  5   b  in a round shape which is fit for the electric connector  5   a  in a round shape of the electronic endoscope  1 B of type B. In other words, in the related-art case, the two connector receivers  4   b,    5   b  are provided corresponding to two types of the electronic endoscopes  1 A and  1 B. Because shapes of the electric connectors  4   a,    5   a  are different in type A and in type B, image processing or so which is suitable to respective types of the electronic endoscopes  1 A,  1 B can be performed, while avoiding erroneous connection of the connectors. 
         [0007]    By the way, in the related-art electronic endoscope apparatus, in case where the connector is connected to one of the connector receivers  4   b,    5   b,  and the other connector receiver is exposed, as shown in  FIGS. 5A and 5B , water content may intrude into the connector receiver  4   b,    5   b  during use of the apparatus, and electrical safety may be deteriorated. At the same time, a trouble may occur in circuit operation inside the processor unit  2 , in some cases. Moreover, such possibility that a user of the like may get in touch with electrodes such as pins inside the connector receivers  4   b,    5   b  cannot be denied. 
         [0008]    Under the circumstances, caps  4   c,    5   c  adapted to be mounted and dismounted to and from the connector receivers  4   b,    5   b  have been provided in the related art, as shown in  FIGS. 5A and 5B . Specifically, the caps  4   c,    5   c  are attached to a side face of the processor unit  2  by means of a coupling cord  6 , so that the caps  4   c,    5   c  can be mounted to the connector receivers  4   b,    5   b  to which the connectors are not connected. 
         [0009]    However, in this manner of simply mounting the caps  4   c,    5   c  to the connector receivers  4   b,    5   b,  there is such a problem that the caps  4   c,    5   c  may be forgotten to be mounted, or the caps  4   c,    5   c  may be detached due to incomplete mounting. In such cases, electrical safety with respect to an internal circuit cannot be secured, and such anxiety that the user may get in touch with the electrode such as the pin in the connector receivers  4   b,    5   b  cannot be excluded. 
       SUMMARY OF THE INVENTION 
       [0010]    The invention has been made in view of the above described problems, and it is an object of the invention to provide an electronic endoscope apparatus in which electrical safety of an internal circuit can be secured, and such possibility that a user may get in touch with an electrode in a connector receiver can be eliminated, even in case where a cap is forgotten to be mounted to the connector receiver or incompletely mounted. 
         [0011]    In order to attain the above described object, according to a first aspect of the invention, there is provided an observed image forming apparatus comprising: an apparatus body including a plurality of connector receivers to which electric connectors of a plurality of observation devices for obtaining an image of an object to be observed can be connected; a cap that is to be mounted to one of said plurality of connector receivers to which any of said plurality of electric connectors is not connected; and a cap insertion and extraction detecting circuit that detects whether or not the cap is mounted to the one of the connector receivers in the apparatus body, wherein, when mounting of the cap has been detected by the cap insertion and extraction detecting circuit, one of the observation devices an electric connector of which is connected to the other one of the connector receivers in the apparatus body is controlled to be driven. 
         [0012]    According to second aspect of the invention, there is provided the observed image forming apparatus, wherein the cap insertion and extraction detecting circuit comprises: an insertion detecting circuit that detects insertion of the cap; and a pin connection detecting circuit that detects pin connection between the cap and the one of the connector receivers, and wherein the mounting of the cap is judged when the insertion of the cap has been detected by the insertion detecting circuit, and the pin connection has been detected by the pin connection detecting circuit. 
         [0013]    According to the first aspect of the invention, only when the mounting of the cap has been detected by the cap insertion and extraction detecting circuit, power is supplied to the observation device such as the scope (electronic endoscope) and the ultrasonic probe, for example, and the obtained image is displayed on a monitor or the like. In short, unless the cap is mounted, the image will not be displayed. 
         [0014]    According to the second aspect of the invention, only when the insertion of the cap has been detected by the insertion detecting circuit such as a photo-interrupter, and the pin connection between the cap (the cap provided with a short-circuited electrode) and the connector receiver has been detected by the pin connection detecting circuit, the observation device is driven. In this manner, the mounting of the cap can be confirmed through double detection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIGS. 1A and 1B  show a structure related to insertion and extraction of a cap to and from a connector receiver of an electronic endoscope apparatus which is an observed image forming apparatus in an embodiment according to the invention, in which  FIG. 1A  is a view showing a state before the cap is mounted, and  FIG. 1B  is a view showing a state after the cap has been mounted; 
           [0016]      FIG. 2  is a block diagram showing an overall structure of the electronic endoscope apparatus in the embodiment; 
           [0017]      FIG. 3  is a view showing another example of a structure of an insertion detecting circuit in the embodiment; 
           [0018]      FIG. 4  is a flow chart showing operation related to mounting/non-mounting of the cap in the electronic endoscope in the embodiment; and 
           [0019]      FIGS. 5A and 5B  show structures of the related-art electronic endoscopes, in which  FIG. 5A  is a perspective view in case where a scope of type A is used, and  FIG. 5B  is a perspective view in case where a scope of type B is used. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIGS. 1A ,  1 B and  2  show a structure of an electronic endoscope apparatus which is an observed image forming apparatus in an embodiment according to the invention.  FIGS. 1A and 1B  show a structure related to insertion and extraction of a cap into and from a connector receiver of a processor unit, and  FIG. 2  shows an overall structure of the electronic endoscope apparatus. In the beginning, as shown in  FIG. 2 , in the electronic endoscope apparatus, a connector  14   a  of a scope  10 A of type A (an observation device-an electronic endoscope) is connected to a connector receiver  14   b  of a processor unit (an apparatus body)  12 , and this processor unit  12  is provided with a connector receiver  15   b  for connecting another scope of type B. The scope  10 A contains therein a CCD  17  which is a solid body photographing element, a CDS (correlation double sampling)/AGC (auto gain control) circuit  18  for inputting an image taking signal which has been obtained by this CCD  17 , and so on. 
         [0021]    On the other hand, the processor unit  12  contains therein a CCD driving pulse circuit  20  for driving the CCD  17 , a scope power supplying circuit  21  for supplying necessary power to the scope  10 A, an A/D converter  22  for inputting an output of the CDS/AGC circuit  18 , an image processing circuit  23  which performs a determined image processing of the output signal of this A/D converter  22 , and a CPU (or a microcomputer)  24  which totally controls these circuits and also controls insertion and extraction of the cap. 
         [0022]    In this embodiment, there is provided a cap (in a round shape, for example)  15   c  which is mounted and connected to the aforesaid connector receiver  15   h  (as for the other connector receiver  14   b,  a cap in a square shape for example is provided), and at the same time, a cap insertion and extraction detecting circuit  26  is connected to the connector receivers  14   b,    15   b.    
         [0023]    A structure related to the cap  15   c,  the connector receiver  15   h  and the cap insertion and extraction detecting circuit  26  is shown in  FIGS. 1A and 1B . A photo-interrupter (an insertion detecting circuit)  28  for detecting an inserted state of the cap  15   c  is provided on a side face of the connector receiver  15   b.  This photo-interrupter  28  has a light emitting part (such as a light emitting diode) and a light receiving part (a photo-transistor), and can detect the inserted state of the cap  15   c  with respect to the connector receiver  15   b,  by reflecting a light emitted from the light emitting part from the side face of the cap  15   c,  and by detecting the reflected light in the light receiving part. 
         [0024]    A plurality of pins (electrodes)  30  are arranged in the connector receiver  15   b,  while two pin receivers (electrodes)  31  are provided in the cap  15   c  (arrangement of these pins and pin receivers may be reversed or some other structures maybe employed). These pin receivers  31  make short circuits inside. Moreover, the connector receiver  15   b  is provided with a pin connection detecting circuit  33  for detecting connection between the pins  30  and the pin receivers  31 , and an AND circuit  34  is provided on an after stage of the pin connection detecting circuit  33  and the aforesaid photo-interrupter  28 . 
         [0025]    Specifically, in the cap insertion and extraction detecting circuit  26  in this embodiment, when the cap  15   c  is mounted to the connector receiver  15   b,  as shown in  FIG. 1B  from the state as shown in  FIG. 1A , the insertion of the cap  15   c  itself is detected by the photo-interrupter  28 , and the connection between the pins  30  and the pin receivers  31  is also detected by the pin connection detecting circuit  33 . At this moment only, a signal (High signal) for judging that the cap  15   c  has been mounted (mounting of the cap) is issued. 
         [0026]    This embodiment has the above described structure, and the electronic endoscope apparatus in this embodiment is so constructed that a plurality of the scopes  10 A or the like can be connected to the processor unit  12 , as described referring to  FIGS. 5A and 5B . For example, in case where the connector  14   a  of the scope  10 A is connected to the connector receiver  14   b  of the processor unit  12 , as shown in  FIG. 2 , the cap  15   c  is mounted to the other connector receiver  15   b.  On this occasion, operation as shown in  FIG. 4  is performed in this embodiment. 
         [0027]    In  FIG. 4 , when the mounting of the cap  15   c  has been performed as described above, it is judged in step  101  whether or not the cap insertion and extraction detecting circuit  26  has detected the insertion of the cap  15   c.  Then, as described referring to  FIG. 1B , when the insertion of the cap  15   c  has been detected by the photo-interrupter  28 , and the connection between the pins ( 30 ,  31 ) has been detected by the pin connection detecting circuit  33 , it is judged that the cap  15   c  has been mounted (YES). Then, in step  102 , the CPU  24  energizes the CCD driving pulse circuit  20  and the scope power supplying circuit  21 , whereby supply of CCD driving pulse and supply of scope power to the CCD  17  of the scope  10 A is started (step  103 ). Then, in step  104 , the CPU  24  requests to display an image observed by the scope, and a determined signal processing is performed on an image signal which has been inputted from the scope  10 A, in the image processing circuit  23 , and the observed image is displayed on a monitor (step  105 ). 
         [0028]    On the other hand, in case where the cap  15   c  is not yet mounted, has been detached or has been extracted, as shown in  FIG. 1A , the insertion of the cap  15   c  is not detected by the photo-interrupter  28  (non-insertion is detected), the connection of the pins is not detected by the pin connection detecting circuit  33  (non-connection is detected) or both are not detected in the aforesaid step  101 , and it is judged that the cap  15   c  is not mounted (NO). In this case, the CPU  24  stops the CCD driving pulse circuit  20  and the scope power supplying circuit  21  in step  106 , and therefore, supply of the CCD driving pulse to the CCD  17  and supply of the scope power is stopped ( 107 ). Then, in step  108 , the CPU  24  requests a message that the cap  15   c  should not be extracted, and the massage to the effect that the cap  15   c  should not be extracted is displayed on the monitor or the like (step  109 ). 
         [0029]    In the above described cap insertion and extraction detecting circuit  26 , only when the insertion of the cap  15   c  itself has been detected by the photo-interrupter  28  and the connection of the pin receivers  31  of the cap  15   c  to the pins  30  of the connector receiver  15   b  has been detected by the pin connection detecting circuit  33 , the scope  10 A is driven to operate. Therefore, through this double detection, forgetting to mount the cap  15   c  and incompletely mounting can be reliably prevented. 
         [0030]      FIG. 3  shows another example of the structure of the insertion detecting circuit in the cap insertion and extraction detecting circuit  26 . In the insertion detecting circuit in this example, there are provided an operating rod  36  which is supported so as to reciprocally move to the right and left in the drawing, a micro switch  37  arranged at a back end side of this operating rod  36 , and a switch on/off detecting circuit  38  for detecting of/off of the micro switch  37 . 
         [0031]    With the insertion detecting circuit in this structure, when the operating rod  36  is pushed by the insertion of the cap  15   c,  the micro switch  37  is turned on, whereby the insertion of the cap  15   c  is detected. Therefore, in the cap insertion and extraction detecting circuit  26 , only when turning on of the micro switch  37  has been detected by this switch on/off detecting circuit  38 , and the connection of the pins has been detected by the pin connection detecting circuit  33 , an output of the AND circuit  34  becomes high. As the results, it is judged that the cap  15   c  has been mounted. 
         [0032]    Although in the above described embodiment, it is so adapted that operation of the scope  10 A starts, when the mounting of the cap  15   c  has been detected by the cap insertion and extraction detecting circuit  26 , it is also possible to start operation of the processor unit  12  including the scope  10 A, that is, operation of the electronic endoscope apparatus. 
         [0033]    Moreover, although the invention is applied to the electronic endoscope apparatus in the embodiment, it is also possible to apply the invention to a complex observation apparatus in which a scope is connected to an ultrasonic probe, for example. 
         [0034]    According to the observed image forming apparatus of the invention, there is obtained such advantage that electrical safety of the internal circuit can be secured, even in case where the cap is forgotten to be mounted, or incompletely mounted, and such possibility that a user may get in touch with the electrode inside the connector receiver can be eliminated. 
         [0035]    Moreover, according to the second aspect of the invention, forgetting to mount the cap and incomplete mounting of the cap can be reliably prevented through the double detection. 
         [0036]    The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.
An observed image forming apparatus comprises: an apparatus body including a plurality of connector receivers to which electric connectors of a plurality of observation devices for obtaining an image of an object to be observed can be connected; a cap that is to be mounted to one of said plurality of connector receivers to which any of said plurality of electric connectors is not connected; and a cap insertion and extraction detecting circuit that detects whether or not the cap is mounted to the one of the connector receivers in the apparatus body, wherein, when mounting of the cap has been detected by the cap insertion and extraction detecting circuit, one of the observation devices an electric connector of which is connected to the other one of the connector receivers in the apparatus body is controlled to be driven.