Patent Publication Number: US-2007123751-A1

Title: Endoscope with brightness adjustment function

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an endoscope that observes an observed portion, such as body cavity. In particular, it relates to illuminating-light irradiated from a light source such, as a lamp.  
      2. Description of the Related Art  
      In an endoscope with a brightness adjustment function, a light-amount adjustment mechanism or an electronic shutter function adjusts a brightness of an object image that is displayed on a display. In an electronic endoscope with a video-scope, a luminance of the object image is detected on the basis of image-pixel signals, which are read from a CCD provided in the video-scope. Then, an opening-degree of a stop or an electronic shutter speed is adjusted such that the displayed object image is maintained at a proper brightness. Also, in an electronic endoscope with a self-monitoring or self-diaqnosis function, a system for monitoring a status of the endoscope operation is installed in the electronic endoscope. When electric power is supplied to the endoscope by operating a power button, the system detects whether a trouble, resulting in erroneous operation, occurs in an electronic circuit. If any trouble or aberrant state is detected, warning information is displayed on the monitor.  
     SUMMARY OF THE INVENTION  
      An object of the present invention is to provide an endoscope that is capable of detecting and reporting unusual or aberrant state of the endoscope while the endoscope is used.  
      An electronic endoscope according to the present invention has a video-scope with an image sensor, a light source that radiates illuminating-light on an object, and a brightness adjuster that maintains a brightness of an object image at a proper brightness by adjusting an amount of illuminating-light. Further, the electronic endoscope has a brightness state detector and a reporting processor. The brightness state detector detects whether the amount of illuminating-light is aberrant, while the brightness is adjusted by the brightness adjuster. The reporting processor informs or reports an aberrant state of the illuminating light when the aberrant state id detected.  
      According to another aspect of the present invention, an apparatus for diagnosing an electronic endoscope has a brightness state detector that detects whether an amount of illuminating-light is aberrant, while an brightness adjuster maintains a brightness of an object image at a proper brightness on the basis of an amount of illuminating-light; and a reporting processor that reports an aberrant state of the illuminating light.  
      According to another aspect of the present invention, a method for diagnosing an electronic endoscope includes i) detecting whether an amount of illuminating-light is aberrant while maintaining a brightness of an object image at a proper brightness by adjusting the illuminating-light; and ii) reporting an aberrant state of the illuminating light. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be better understood from the description of the preferred embodiments of the invention set forth below together with the accompanying drawings, in which:  
       FIG. 1  is a block diagram of an electronic endoscope according to a first embodiment;  
       FIG. 2  is a flowchart of a main process performed by the system control circuit;  
       FIG. 3  is a view showing a subroutine of Step S 102  in  FIG. 2 ;  
       FIG. 4  is a view showing a subroutine of step s 103  in  FIG. 2 ;  
       FIG. 5  is a flowchart of an auto-brightness adjustment process and a self-diagnosis process;  
       FIG. 6  is a flowchart of a usage state detection process;  
       FIG. 7  is a block diagram of an electronic endoscope according to a second embodiment;  
       FIG. 8  is a flowchart of a main routine according to the second embodiment;  
       FIG. 9  is a flowchart of an auto-brightness adjustment process and a self-diagnosis process according to the second embodiment;  
       FIG. 10  is a block diagram of an electronic endoscope according to a third embodiment;  
       FIG. 11  is a view showing a main routine according to the third embodiment;  
       FIG. 12  is a view showing a flowchart of an auto-brightness adjustment process and a self-diagnosis process according to the third embodiment;  
       FIG. 13  is a flowchart of a usage state detection process according to the third embodiment;  
       FIG. 14  is a flowchart of an auto brightness adjustment process and a self-diagnosis process according to a fourth embodiment;  
       FIG. 15  is a view showing a main routine according to the fourth embodiment;  
       FIG. 16  is a view showing a subroutine of Step S 1302  shown in  FIG. 15 ;  
       FIG. 17  is a view showing a subroutine of Step S 1303  shown in  FIG. 15 ;  
       FIG. 18  is a block diagram of an electronic endoscope according to a fifth embodiment;  
       FIG. 19  is a view showing a main routine according to the fifth embodiment; and  
       FIG. 20  is a view showing a subroutine of Step S 1504  shown in  FIG. 19 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Hereinafter, the preferred embodiments of the present invention are described with reference to the attached drawings.  
       FIG. 1  is a block diagram of an electronic endoscope according to a first embodiment,  
      The electronic endoscope has a video-scope  10  with a CCD  14 , and a video-processor  30 . The video-scope  10  is removably connected to the video-processor  30 ; and a keyboard  60  and a monitor  70  are connected to the video-processor  30 . When the video-scope  10  is connected to the video-processor  30 , electric power is supplied from the video-processor  30  to the video-scope  10 , which allows the video-scope  10  to operate.  
      When a lamp switch button (not shown) is turned ON, a lamp  32  radiates illuminating light. The illuminating light emitted from the lamp  32  enters the incident surface  11 A of a light-guide  11  via a stop  31  and a collecting lens (not shown). The light-guide  11  is constructed of a fiber-optic bundle for directing the illuminating light to a tip end of the video-scope  10 . The light exits from the distal end portion  11 B of the light-guide  11 , and illuminates an observed object via a diffusion lens (not shown).  
      Light, reflected off the object, reaches the CCD  14  via an objective lens  13 , so that an object image is formed on the photo-sensitive area of the CCD  14 . A color filter (not shown), checkered by four color elements of Yellow (Y), Magenta (M), Cyan (C), and Green (G), is arranged on the photo-receiving area such that the four color elements are opposite to pixels arranged in the photo-sensitive area. Based on the light passing through each color element, analog image-pixel signals are generated by the photoelectric transformation effect.  
      The generated image-pixel signals are read from the CCD  14  to an image signal processing circuit  12  via an AGC (Auto Gain Control) circuit  16 , at regular time intervals in accordance with clock pulse signals output from a CCD driver  12 A in the video signal processing circuit  12 . The NTSC (or PAL) standard is herein applied as the TV standard; therefore, the image-pixel signals corresponding to one field image are read from the CCD  14  at a 1/60 (or 1/50) second intervals.  
      In the image signal processing circuit  12 , various processes, such as a gamma correction process, a white balance process, and so on, are carried out on the image-pixel signals, so that luminance and color difference signals are generated. The generated luminance and color difference signals are output to the video-processor  30 . In a latter signal processing circuit  42 , video signals are generated from the luminance and color difference signals, and are output to the monitor  70  so that an observed image is displayed on the monitor  70 .  
      The video-scope  10  has a scope controller  20  including a CPU  21 , a RAM  23 , and a ROM  27 ; and controls an operation of the video-scope  10  by outputting control signals to circuits in the video-scope  10 . In the ROM  27 , a program associated with a process of the video-scope  10  is stored. On the other hand, in an EEPROM  18 , data associated with characteristics of the video-scope  10  is stored.  
      The video-processor  30  has a system control circuit  40 , which includes a CPU  47 , a ROM  48 , and a RAM  49 ; and controls the operation of the video-processor  30 . A program for controlling the video-processor  30  is stored in the ROM  48 , whereas a data associated with the lamp  32  is stored in an EEPROM  43 . The system control circuit  40  outputs character codes to a CRTC (CRT Controller)  45 , and the CRTC  45  outputs character signals in accordance with the character codes so that character information is displayed on the monitor  70 . The system control circuit  40  and the scope-controller  20  transmit data to each other.  
      The stop  31  opens and closes to adjust an amount of the illuminating light, and is driven by a stop driver  35 . To carry out an auto brightness adjustment process, the system control circuit  40  controls the stop  31  on the basis of luminance signals, which are fed from the latter signal processing circuit  42 , so as to maintain the brightness of the displayed observed image at a proper brightness. Concretely, based on a difference between the detected luminance level and a reference luminance level (or the ratio of the detected luminance level to the reference luminance level), the system control circuit  40  adjusts an opening-degree of the stop  31  by outputting control signals to the stop driver  35 .  
      A first gyro-sensor  22  and a second gyro-sensor  24 , provided in the video-scope  10 , detect whether the video-scope  10  is used by an operator; namely, whether the operator user or manipulates the video-scope  10  for endoscope work, such as for an operation, or for treatment. The first and second gyro-sensors  22  and  24  detect, respectively, two angular velocities with respect to two directions perpendicular to each other, when the video-scope  10  is used.  
       FIG. 2  is a flowchart of a main process performed by the system control circuit  40 .  
      In Step S 101 , the initial setting process is performed so that variables are set to initial values. In Step S 102 , a process associated with a connection of the video-scope  10  is performed, and in step S 103 , a process associated with data communication to the video-scope  10  is performed. In Step S 104 , a process associated with an operation of the keyboard  60  is performed, and in Step S 105 , a process associated with an operation on a panel switch  50  is performed. Then, in Step S 106 , other processes are performed.  
       FIG. 3  is a view showing a subroutine or Step S 102  in  FIG. 2 .  
      In Step S 201 , it is determined whether the video-scope  10  is newly connected to the video-processor  30 . Herein, various video-scopes, corresponding to a lower digestive organ such as the colon, an upper digestive organ such as the stomach, the lungs, or so on, are prepared; and one video-scope is selectively connected to the video-processor  30 .  
      When it is determined in Step S 201  that the video-scope  10  is newly connected to the video-processor  30 , the process goes to Step S 202 . In Step S 202 , data associated with the video-scope  10 , such as a registration number, is read from the EEPROM  18 . Then, in Step S 203 , a scope-connection variable “vs” is set to 1. The scope-connection variable “vs” indicates a connection status of the video-scope. The scope-connection variable “vs” is set to 1 when the video-scope  10  is connected to the video-processor  30 , whereas the scope-connection variable “vs” is set to 0 when the video-scope  10  is not connected to the video-processor  30 . Also, in Step S 203 , reference ratio or proportions “CAL” and “CAS” associated with large and small opening-degrees, respectively, are set in accordance with the connected video-scope  10 , as described later.  
      On the other hand, when it is determined in Step S 201  that the video-scope  10  is not newly connected to the video-processor  30 , the process goes to Step S 204 . In Step S 204 , it is determined whether the video-scope  10  is detached from the video-processor  30 . When it is determined that the video-scope  10  is not detached from the video-processor  30 , the process is terminated. On the other hand, when it is determined that the video-scope  10  is detached from the video-processor  30 , the process goes to Step S 205 . In Step S 205 , the scope-connection variable “vs” is set to 0,  
       FIG. 4  is a view showing a subroutine of Step S 103  in  FIG. 2 .  
      In Step S 301 , it is determined whether data has been transmitted from the video-scope  10 . When it is determined that the data has not been transmitted from the video-scope  10 , the process is terminated. On the other hand, when it is determined that the data has been transmitted from the video-scope  10 , the process goes to step S 302 . At step S 302 , it is determined whether the transmitted data is data for determining whether the video-scope  10  is used.  
      When it is determined that the transmitted data is not data for determining whether the video-scope  10  is used, the process goes to Step S 304 . At Step S 304 , a process corresponding to the data is performed. On the other hand, when it is determined that the transmitted data is data for determining whether the video-scope  10  is used, the process goes to Step S 303 . In Step S 303 , the value of a usage state variable “us”, described later, is set to the value of the transmitted data.  
       FIG. 5  is a flowchart of an auto-brightness adjustment process and a self-diagnosis process performed by the system control circuit  40 . This process is carried out by interrupting in the main routine shown in  FIG. 2 , at 1/60 second intervals.  
      In Step S 401 , the auto brightness adjustment process is performed. Namely based on a luminance difference between a detected luminance level and a reference luminance level indicating a proper brightness of the object, the stop  31  is opened and closed such that the luminance difference does not occur. The stop  31  closes if the detected luminance level is higher than the reference luminance level, while the stop  31  opens if the detected luminance level is smaller than the reference luminance level.  
      In Step S 402 , a first recording timer variable “vc 1 ” is incremented by 1. The first recording timer variable “vc 1 ” is a variable that measures an interval for storing an opening-degree of the stop  31  in the RAM  49  at one-second intervals periodically. The first recording timer variable “vcl” is initially set to 0 at Step S 101  shown in  FIG. 2 . In Step S 403 , it is determined whether the first recording timer variable “vcl” is equal to or more than 60; namely, whether one second has passed.  
      When it is determined that the first recording timer variable “vc 1 ” is shorter than 60, in Step S 403 , the process is terminated. On the other hand, when it is determined that the first recording timer variable “vc 1 ” is equal to or greater than 60, the process goes to Step S 404 . In Step  3404 , the first recording timer variable “vc 1 ” is set to 0.  
      In Step S 405 , it is determined whether the usage state variable “us” is 1. The usage state variable “us” indicates the used or unused status of the video-scope  10 . Herein, it is determined whether the video-scope  10  is substantially used; namely, whether the video-scope  10  is operated for endoscope work, a treatment, an operation, etc. The usage state variable “us” is set to 1 when the video-scope  10  is substantially used, whereas the usage state variable “us” is set to 0 when the video-scope  10  is not substantially used.  
      When it is determined that the video-scope  10  is not substantially used, the process skips to Step S 408 . On the other hand, when it is determined that the video-scope  10  is substantially used, the process goes to Step S 406 . In Step S 406 , the opening-degree of the stop  31 , which is presently set by the system control circuit  40 , is temporarily stored in the RAM  49  as data. Concretely speaking, the frequency distribution data of the opening-degree is stored in the RAM  49 .  
      The opening-degree is herein represented by an integer in the range from 0 to 240. The amount of illuminating light increases as the value of the opening-degree increases. The opening-degree is represented by 0 when the stop  31  is fully closed, and the opening-degree is represented by 240 when the stop  31  is fully opened. The range from 0 to 240 of the opening-degree is divided into seven grades or stages; a section from 0 to 39, a section from 40 to 79, a section from 80 to 119, a section from 120 to 159, a section from 160 to 199, a section from 200 to 219, and a section from 220 to 240. The detected opening-degree is assigned to a corresponding grade such that the value of the corresponding frequency is incremented. By successively incrementing the value of the corresponding frequency, the frequency distribution data is generated. After Step S 406  is carried out, the process goes to Step S 407 ,  
      In step S 407 , a second recording timer variable “vc 2 ” is incremented by 1. The second recording timer variable “vc 2 ” is a variable that measures an interval for carrying out an aberrant status detection process, described later, at six-minute intervals. The second recording timer variable “vc 2 ” is initially set to 0 at Step S 102  shown in  FIG. 2 .  
      In Step S 408 , it is determined whether the second recording timer variable “vc 2 ” is equal to or greater than 360; namely, whether six minutes has passed from the previous aberrant status detection process. When it is determined that the second recording timer variable “vc 2 ” is smaller than 360, the process is terminated. on the other hand, when it is determined that the second recording timer variable “vc 2 ” is equal to or greater than 360, the process goes to Step S 409 , where the second recording timer variable “vc 2 ” is set to 0.  
      In Step S 410 , based on the frequency distribution data of the opening-degree, which has been stored in the RAM  49 , a first ratio “al” and a second ratio “as” are calculated. Note that, the frequency distribution data is obtained during the six minutes over which the video-scope  10  is substantially used. The first ratio “al” represents a ratio of the number of incidences of relatively large opening-degree to the total detected number of incidences of opening-degrees; namely, the ratio of the detected number of times of the relatively large opening-degree to the total detected number of times during the six minutes (=360). Herein, the first ratio “al” indicates the proportion of the seventh grade; the section from 220 to 240. On the other hand, the second ratio “as” represents a ratio of the number of incidences of relatively small opening-degree to the total detected number of incidences of opening-degrees. Herein, the second ratio “as” indicates the proportion of the first grade; namely, the section from 0 to 39. In Step S 411 , the frequency distribution data stored in the RAM  49  is reset to 0.  
      In Step S 412 , it is determined whether the first ratio “al” exceeds the reference ratio or the large opening-degree “CAL” determined at Step S 203  in  FIG. 3 . Namely, it is determined whether the situation in which the opening-degree of the stop  31  is extremely large continues while the auto-brightness adjustment process is perforated. For example, the amount of illuminating light or the brightness decreases due to dirt on the tip surface of the video-scope  10 , or a decrease in light irradiated from the lamp  32 . The decrease of illuminating-light results in a state in which a relatively large opening-degree continues. The value of the reference ratio “CAL” is determined in accordance with the type of the video-scope  10 . For example, in the case of the video-scope for the bronchi, the reference ratio “CAL” is set to 90 percent; in the case of the video-scope for the stomach, the reference ratio “CAL” is set to 95 percent; in the case of the video-scope for the colon, the reference ratio “CAL” is set to 85 percent.  
      When it is determined at Step S 412  that the first ratio “al” exceeds the reference ratio “CAL”, the process goes to Step S 413 . In Step S 413 , character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation of the electronic endoscope to the operator. Thus, the operator can recognize whether the operation or motion of the video-scope  10  or the video-processor is unusual or aberrant with respect to the amount of illuminating-light. On the other hand, when it is determined that the first ratio “al” does not exceed the reference ratio “CAL”, the process goes to Step S 414 .  
      In Step S 414 , it is determined whether the second ratio of the small opening degree “as” exceeds the reference ratio of the small opening-degree “CAS” determined at Step  203  in  FIG. 2 . For example, when the amount of light radiated from the lamp  32  becomes unexpectedly large due to an accident of the lamp  32 , a situation where the value of the opening-degree is extremely small continues during the auto brightness adjustment process, since the stop  31  closes to restrict the extremely large amount of illuminating-light. Herein, in the case of the video-scope for the bronchi, the reference ratio “CAS” is set to 25 percent; in the case of the video-scope for the stomach, the reference ratio “CAS” is set to 25 percent; in the case of the video-scope for the colon, the reference ratio “CAS” is set to 35 percent.  
      When it is determined that the second ratio of the small opening-degree “as” does not exceed the reference ratio “CAS”, the process is terminated. On the other hand, when it is determined that the second ratio “as” exceeds the reference ratio “CAS”, the process goes to Step S 415 , where the character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation,  
       FIG. 6  is a flowchart of the usage state detection process performed by the scope controller  20 . This process is carried out by interrupting a main routine (herein, not explained), which is performed by the scope controller  20 , at 1/60 second intervals.  
      In Step S 501 , angular velocity data is input from the first gyro-sensor  22  to the scope-controller  20 . The value of the angular velocity is herein represented by an integer in the range from 0 to 255. When the angular velocity is in the range from 121 to 135, it is determined by the first gyro-sensor  22  that the video-scope  10  is not moved. In Step S 502 , it is determined whether the angular velocity is greater than 120 and smaller than 136.  
      When it is determined that the angular velocity is greater than 120 and smaller than 136, the process goes to Step S 503 . In Step S 503 , a timer variable “vc 31 ” is incremented by 1. The timer variable “vc 31 ” is a variable for measuring the time, in 1/60 second intervals, that the first gyro-sensor  22  does not detect motion of the video-scope  10 . In Step S 504 , it is determined whether the timer variable “vc 31 ” exceeds 1800; namely, whether the time that the video-scope  10  is stationary continues for more than 30 seconds.  
      When it is determined at Step S 504  that the timer variable “vc 31 ” does not exceed 1800, the process skips to Step S 507 . On the other hand, when it is determined in Step S 504  that the timer variable “vc 31 ” exceeds 1800, the process goes to Step s 505 . In Step S 505 , a motion variable “ul” set to 0, and the timer variable “vc 31 ” is set to 0. The motion variable “u 1 ” is a variable that represents the motion of the video-scope  10  detected by the first gyro-sensor  22 . The motion variable “u 1 ” is set to 0 when the video-scope  10  is stationary, whereas the motion variable “ul” is set to 1 when the video-scope  10  is in motion.  
      On the other hand, when it is determined at Step S 502  that the angular velocity is equal to or smaller than 120, or is equal to or greater than 136, the process goes to Step S 506 . In Step S 506 , the motion variable “u 1 ” is set to 1, and the timer variable “vc 31 ” is set to 0.  
      In Step S 507 , angular velocity data is input from the second gyro-sensor  24 . In Steps S 508  to S 512 , it is determined by the second gyro-sensor  24  whether the video-scope  10  is in motion. If a situation in which the video-scope  10  is not in motion continues for 30 seconds, a motion variable “u 2 ”, which represents the motion of the video-scope  10  detected by the second gyro-sensor  24 , is set to 0. On the other hand, the motion variable “u 2 ” is set to 1 if the video-scope  10  is in motion.  
      In Step S 513 , it is determined whether both of the motion variables “u 1 ” and “u 2 ” are 0; namely, whether the video-scope  10  is not in motion or is fixed (for example, whether the video-scope  10  is held by a scope-holder). When it is determined that both of the motion variables “ul” and “u 2 ” are 0, the process goes to Step S 514 . In Step S 514 , the usage state variable “us”, as described above, is set to 0. On the other hand, when it is determined that the motion variable “u 1 ” or the motion variable “u 2 ” is not 0, the process goes to Step S 515 , where the usage state variable “us” is set to 1. The usage state variable “us” is periodically transmitted to the video-processor  30  where the value of the “usage state variable” defined in the video-processor  30  is set to the value of usage state variable “us” in the video-scope  10  (see Step S 303  in  FIG. 4 ).  
      In this way, in the first embodiment, as shown in  FIG. 5 , the auto-brightness adjustment process is carried out by controlling the stop  31  at 1/60 second intervals, and the data of the opening-degree of the stop  31 , which varies with the brightness, is stored in the RAM  49  at one-second intervals to generate the distribution data of detected opening-degrees (S 406 ). Then, the first ratio “al”, indicating the ratio of the number of incidences of relatively large opening-degree to the total detected number of incidences of opening-degrees, and the second ratio “as”, indicating the ratio of the number of incidences of relatively small opening-degree to the total detected number of incidences of opening-degree, are calculated, respectively, and are compared to the reference ratio of the large opening-degree “CAL” and to the reference ratio of the small opening-degree “CAS”, respectively (S 411 , S 412  and S 414 ). When the first ratio “al” is higher than the reference ratio “CAL”, or the second ratio “as” is higher than the reference ratio “CAS”, it is determined that the illuminating-light irradiated on the observed portion is aberrant, and character information for warning that the illuminating-light is aberrant is displayed on the monitor  70  (S 413  and S 415 ).  
      The values of first ratio “al” and the second ratio “as” may be optionally set. For example, a ratio of the number of incidences of relative large opening-degree, which is higher than 75 percent of the full opening-degree, to the total detected number of incidences of opening-degrees, may be set as the first ratio “al”. On the other hand, a ratio of the number of incidences of relative small opening-degree, which is lower than 25 percent of the full opening-degree, to the total detected number of incidences of opening-degrees, may be set as the second ratio “as”. Also, the values of the reference ratios “CAL” and “CAS”, respectively, may be optionally set in accordance with the connected video-scope. For example, the values of the reference ratios “CAL” and “CAS” may be set to ¾ and ¼. The information that the illuminating light is aberrant may be reported aurally, such as, by a buzzer sound.  
      With reference to FIGS.  7  to  9 , a second embodiment is explained. The second embodiment is different from the first embodiment in that the auto brightness adjustment process is performed by adjusting the amount of light emitted from a light source directly. Other constructions are substantially the same as those of the first embodiment.  
       FIG. 7  is a block diagram of an electronic endoscope according to the second embodiment.  
      A video-scope  10 ′ has an LED  25  and an LED driver  26 . A scope-controller  20 ′ controls the video-scope  10 ′. In a ROM  27 , a program for controlling the video-scope  10 ′ is stored. A stop and a lamp are not provided in a video-processor  30 ′, unlike in the first embodiment.  
      The LED  25 , provided in the tip portion of the video-scope  10 ′, emits light in accordance with an electric current from the LED driver  26 . The scope-controller  20 ′ controls the amount or electric current for the LED  25  on the basis of luminance signals fed from the image signal processing circuit  12 , so that the brightness of the object image is maintained at a proper brightness.  
       FIG. 8  is a flowchart of the main routine performed by the scope-controller  20 ′. In the second embodiment, the scope-controller  20 ′ (not the video-processor) detects any unusual or aberrant state of the illuminating light, unlike in the first embodiment.  
      In Step S 601 , an initial setting process is performed. In step S 602 , a process of communication with the video-processor  30 ′ is performed. In Step S 603 , a process of communication with the image signal processing circuit  12  is performed. In Step S 604 , a switch process associated with switches provided on the video-scope  10 ′ is performed. In Step S 605 , other processes are performed. Steps S 602  to S 605  is repeatedly performed until the video-scope  10 ′ is detached from the video-processor  30 ′, or the main electric power is turned OFF.  
       FIG. 9  is a flowchart of an auto-brightness; adjustment process and a self-diagnosis process according to the second embodiment.  
      In step S 701 , the auto brightness adjustment process is performed. Namely, based on the difference (or ratio) between the detected luminance level of the object image and the reference luminance level, the amount of electric current supplied from the LED driver  26  to the LED  25  is adjusted such that the brightness of the object image is maintained at a proper brightness. The process from Steps S 702  to S 705  is the same as that from steps S 402  to S 405  shown in  FIG. 5 .  
      In Step S 706 , data of the amount of electric current, which is presently set by the scope controller  20 ′, is stored in the RAM  23 . Herein, the value of the electric current is an integer in the range from 1 to 240. Similarly to in the first embodiment, the data of the amount of electric current is stored as frequency distribution data, which is divided into seven grades; a section from 1 to 39, a section from 40 to 79, a section from 80 to 119, a section from 120 to 159, a section from 160 to 199, a section from 200 to 219, and a section from 220 to 240.  
      The process from Steps S 707  to S 709  is the same as that from Steps S 407  to S 409  shown in  FIG. 5 . In Step S 710 , based on the frequency distribution data of the amount of electric current, which has been stored in the RAM  23 , a third ratio “c 1 ” and a fourth ratio “cs” are calculated. Note that the frequency distribution data is obtained during the six minutes that the video-scope  10  is substantially used. The third ratio “cl” represents a ratio of the number of incidences of a relatively high amount of electric current to the total detected number of incidences of electric current; namely, the ratio of detected number of times of relatively high amount of electric current to the total detected number of times of electric current during the six minutes (=360). Herein, the third ratio “cl” indicates the proportion of the seventh grade, the section from 220 to 240. On the other hand, the fourth ratio “cs” represents a ratio of the number of incidences of relatively low amount of electric current to the total detected number of incidences of electric current. Herein, the fourth ratio “cs” indicates the proportion of the first grade, the section from 1 to 39. In Step S 711 , the frequency distribution data stored in the RAM  23  is reset to 0.  
      In Step S 712 , it is determined whether the third ratio “cl” exceeds a reference ratio “CCL” corresponding to a large electric current. Namely, it is determined whether the situation in which the amount of electric current is extremely large continues while the auto-brightness adjustment process is performed. The value of the reference ratio “CCL” is determined in accordance with the type of the video-scope  10 . For example, in the case of the video-scope for the bronchi, the reference ratio “CCL” is set to 90 percent; in the case of the video-scope for the stomach, the reference ratio “CCL” is set to 95 percent; in the case of the video-scope for the colon, the reference ratio “CCL” is set to 85 percent.  
      When it is determined in Step S 712  that the third ratio “cl” exceeds the reference ratio “CCL”, the process goes to Step S 713 . In step S 713 , the character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation of the electronic endoscope to the operator. On the other hand, when it is determined that the third ratio “cl” does not exceed the reference ratio “CCL”, the process goes to Step S 714 .  
      In Step S 714 , it is determined whether the fourth ratio “cs” exceeds a reference ratio “CCS” corresponding to the small electric current. Herein in the case of the video-scope for the bronchi, the reference ratio “CCS” is set to 25 percent; in the case of the video-scope for the stomach, the reference ratio “CCS” is set to 25 percent; in the case of the video-scope for the colon, the reference ratio “CCS” is set to 35 percent. When it is determined that the fourth ratio “Cs” does not exceed the reference ratio “CCS”, the process terminated. On the other hand, when it is determined that the fourth ratio “cs” exceeds the reference ratio “CCS”, the process goes to Step S 715 , where the character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation to the operator.  
      In this way, in the second embodiment, the auto brightness adjustment process is carried out by adjusting the amount or electric current fed from the LED driver  25  to the LED  26 , and the self-diagnosis process is carried out on the basis of the amount of electric current. Then, as shown in  FIG. 9 , the third ratio “cl”, indicating a ratio of the number of incidences of a large value of electric current to the total detected number of incidences of electric current, and the fourth ratio “cs”, indicating a ratio of the number of incidences of a small value of electric current to the total detected number of incidences of electric current, are calculated, respectively, and are compared to the reference ratio “CCL” and to the reference ratio “CCS”, respectively (S 710 , S 712  and S 714 ), When the third ratio “cl” is greater than the reference ratio “CCL”, or the fourth ratio “cs” is greater than the reference ratio “ccs”, it is determined that the illuminating-light irradiated on the observed portion is in aberrant state, and character information for warning that the illuminating-light is aberrant is displayed on the monitor  70  (S 713  and S 715 ).  
      The third ratio “cl” and the fourth ratio “cs” may be optionally set. For example, a ratio of the number of incidences of relatively high value of electric current, which is higher than 75 percent of the maximum value of electric current to the total detected number of incidences of electric current, may be set as the third ratio “cl”. On the other hand, a ratio of the number of incidences of a relatively low value of electric current, which is smaller than 25 percent of the maximum value of electric current, to the total detected number of incidences of electric current may be set as the second ratio “cs”. Also, the values of the reference ratios “CCL” and “CCS”, respectively, may be optionally set in accordance with the connected video-scope. For example, the values of the reference ratios “CCL” and “CCS” may be set to ¾ and ¼, respectively.  
      The LED  25  may be installed in the video-processor. In this case, the video-processor may adjust the amount of electric current. The auto-brightness adjustment process and the self-diagnosis process may be carried out in a light source unit used for a fiber-scope. Another light source may be used instead of an LED, and may adjust the amount of electric current associated with the amount of illuminating-light.  
      With reference to FIGS.  10  to  13 , a third embodiment is explained. The third embodiment is different from the first and embodiments in that the auto brightness adjustment process is performed by an electronic shutter function. Other constructions are substantially the same as those of the first embodiment and the second embodiment.  
       FIG. 10  is a block diagram of an electronic endoscope according to the third embodiment.  
      A scope-controller  20 ″ in a video-scope  10 ″ carries out the auto brightness adjustment process on the basis of luminance signals detected by an image signal processing circuit  12 ″. The scope-controller  20 ″ outputs control signals to the image signal processing circuit  12 ″, to set a charge-accumulation period, or an electronic shutter speed. The CCD  14  is driven by driving signals fed from the CCD driver  12 ″A such that image-pixel signals are read from the CCD  14  in accordance with the determined charge-accumulation period. Thus, the proper brightness off the object image is maintained.  
       FIG. 11  is a view showing a main routine performed by the scope-controller  20 ″. The process from Steps S 801  to S 805  is the same as that from Steps S 601  to S 605  shown in  FIG. 8 .  
       FIG. 12  is a view showing a flowchart of an auto-brightness adjustment process and a self-diagnosis process according to the third embodiment. This process is carried out by interrupting the main routine shown in  FIG. 11  at 1/60 second intervals,  
      In Step S 901 , based on the difference between the detected luminance level of the object image and the reference luminance level, the electronic shutter speed or the charge-accumulation period is adjusted such that the proper brightness of the object imago is maintained. The process from Steps S 902  to s 905  is the same as that from Steps S 702  to S 705  shown in  FIG. 9 .  
      In Step S 906 , data on the electronic shutter speed, which is presently set by the scope controller  20 ″, is stored in the RAM  23 . Herein, the value of the electronic shutter speed is a value in the range from 1/60 to 1/10000. The data of the electronic shutter speed is stored as frequency distribution data, which is divided into eight grades; a section from 1/60 to less than 1/80, a section from 1/80 to less than 1/120, a section from 1/120 to less than 1/250, a section from 1/250 to less than 1/500, a section from 1/500 to less than 1000, a section from 1/1000 to less than 1/2000, a section from 1/2000 to less than 1/4000, and a section from 1/4000 to 1/40000. The process from Steps S 907  to S 909  is the same as that from Steps S 707  to S 709  in  FIG. 9 .  
      In Step S 910 , based on the frequency distribution data for the electronic shutter speed, which has been stored in the RAM  23 , a fifth ratio “tl” is calculated. Note that, the frequency distribution data is obtained over the six minutes that the video-scope  10  is substantially used. The fifth ratio “tl” represents a ratio of the number of incidences of relatively low speed, indicated by high value of electronic shutter speed, to the total detected number of incidences of electronic shutter speeds. Herein, the fifth ratio “tl” indicates the proportion of the first grade, the section from 1/60 to less than 1/80.  
      In Step S 911 , it is determined whether the fifth ratio “tl” exceeds a reference ratio “CS” corresponding to the low speed. Namely, it is determined whether the situation where the electronic shutter speed is extremely high continues while the auto-brightness adjustment process is performed. For example, in the case of the video-scope for the bronchi, the reference ratio “CS” is set to 90 percent.  
      When it is determined that the third ratio “tl” does not exceed the reference ratio “CS”, the process skips to Step S 913 . On the other hand, when it is determined at Step S 910  that the fifth ratio “tl” exceeds the reference ratio “CS”, the process goes to Step S 912 . In Step S 912 , the character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation of the electronic endoscope to the operator. In Step S 913 ′, the frequency distribution data stored in the RAM  23  is reset to  
       FIG. 13  is a flowchart of a usage state detection process according to the third embodiment. The process from Steps S 1101  to S 1115  is the same as that from Steps S 501  to S 515  shown in  FIG. 6 .  
      In this way, in the third embodiment, the auto-brightness adjustment process is carried out, and the self-diagnosis process is carried out on the basis of the electronic shutter speed. Then, the fifth ratio “tl”, indicating a ratio of the number of incidences of low electronic shutter speed to the total detected number of incidences of electronic shutter speed is calculated, and is compared to the reference ratio “CS” (S 910  and S 911 ). When the fifth ratio “tl” is higher than the reference ratio “CS”, it is determined that the illuminating-light irradiated on the observed portion is in aberrant state, and character information for warning that the illuminating-light is aberrant is displayed on the monitor  70  (S 912 ).  
      With reference to FIGS.  14  to  17 , a fourth embodiment is explained. The fourth embodiment is different from the first, second, and third embodiments in that the video-processor detects an amount of illuminating light on the basis of electronic shutter speed data. Other constructions are substantially the same as those of the first, second, and third embodiments.  
       FIG. 14  is a flowchart or an auto brightness adjustment process and a self-diagnosis process according to the fourth embodiment. This process is carried out by the scope-controller  20 ″ and interrupts the main routine, carried out by the scope-controller  20 ″, at 1/60 second intervals.  
      The process from Steps S 1201  to S 1209  is the same as that from Steps S 901  to S 909  shown in  FIG. 12 . Namely, the data of electronic shutter speed is stored in the RAM  23  at one-second intervals. In Step S 1210 , data of a series of detected electronic shutter speed is transmitted to the system control circuit  40 ″ at six minute intervals. In Step S 1211 , the data stored in the RAM  23  is reset to 0.  
       FIG. 15  is a view showing a main routine performed by the system control circuit  40 ″. The process from Steps S 1301  to S 1306  is the same as that from Steps S 101  to S 106  shown in  FIG. 2 .  
       FIG. 16  is a view showing a subroutine of Step S 1302  shown in  FIG. 15 . The process from Steps S 1401  to S 1405  is the same as that from Steps S 201  to S 205  shown in  FIG. 3 . Note that, in Step S 1403 , reference ratios “CSL” and “CSH”, described later, are set.  
       FIG. 17  is a view showing a subroutine of Step S 1303  shown in  FIG. 15 .  
      In Step S 1501 , it is determined whether data has been transmitted from the video-scope  10 ″. When it is determined that the data has not been transmitted from the video-scope  10 ″, the process is terminated. On the other hand, when it is determined that the data has been transmitted from the video-scope  10 ″, the process goes to Step S 1502 . In Step S 1502 , it is determined whether the transmitted data is data on the electronic shutter speed.  
      When it is determined that the transmitted data is not data of the electronic shutter speed, the process goes to Step S 1508 . In Step S 1508 , a process corresponding to the data is performed. On the other hand, when it is determined that the transmitted data is data of the electronic shutter speed, the process goes to Step S 1503 . In Step S 1503 , based on the frequency distribution data of the electronic shutter speeds, which has been stored in the RAM  23 , a sixth ratio “sl” and a seventh ratio “sh” are calculated. The sixth ratio “s 1 ” represents a ratio of the number of incidences of relatively low shutter speed (high value of the electronic shutter speed) to the total detected number of incidences of electronic shutter speeds. On the other hand, the seventh ratio “sh” represents a ratio of the number of incidences of relatively high speed (low value of electronic shutter speed) to the total detected number of incidences of electronic shutter speeds. Herein, the sixth ratio “sl” indicates the proportion of the first grade, the section from 1/60 to less than 1/80, whereas the seventh ratio “sh” indicates the proportion of the seventh grade, the section from 1/2000 to 1/40000.  
      In Step S 1504 , it is determined whether the sixth ratio “sl” exceeds the reference ratio “CSL” determined at Step S 1403  in  FIG. 16 . Namely, it is determined whether the situation in which the electronic shutter speed is extremely low continues while the auto-brightness adjustment process is performed. For example, in the case of the video-scope for the colon, the reference ratio “CSL” is set to 85 percent. When it is determined that the sixth ratio “sl” exceeds the reference ratio “CSL”, the process goes to Step S 1506 . In Step S 1506 , the character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation of the electronic endoscope to the operator.  
      On the other hand, when it is determined that the sixth ratio “sl” does not exceed the reference ratio “CSL”, the process goes to step S 1505 , In Step S 1505 , it is determined whether the seventh ratio “sh” exceeds the reference ratio “CSH” determined at Step S 1403  in  FIG. 16 . Namely, it is determined whether the situation in which the electronic shutter speed is extremely high continues while the auto-brightness adjustment process is performed. For example, in the case of the video-scope for the colon, the reference ratio “CSH” is set to 5 percent. When it is determined that the seventh ratio “sh” does not exceed the reference ratio “CSH” the process is terminated. On the other hand, when it is determined that the seventh ratio “sh” exceeds the reference ratio “CSH” the process goes to Step S 1507 , where the character signals are output from the CRTC  45  so as to display character information that reports an aberrant situation.  
      In this way, in the fourth embodiment, the auto brightness adjustment process is carried out by adjusting the electronic shutter speed, and the self-diagnosis process is carried out in the video-processor. Then, the sixth ratio “sl” corresponding to the low shutter speed and the seventh ratio “sh” corresponding to the high shutter speed are calculated, respectively, and are compared to the reference ratio “CSL” and the reference ratio “CSH”, respectively (S 1503 , S 1504  and Sl 505 ). When the sixth ratio “sl” is higher than the reference ratio “CSL”, or the seventh ratio “sh” is higher than the reference ratio “CSH”, it is determined that the illuminating-light irradiated on the observed portion is in an aberrant state, and character information for warning that the illuminating-light is aberrant is displayed on the monitor  70  (S 1506  and S 1507 ).  
      The sixth ratio “sl” and the seventh ratio “sh” may be set, optionally. For example, a ratio of the number of incidences of relatively low shutter speed, which is lower than 10 percent to the maximum shutter speed, to the total detected number of incidences of electronic shutter speeds, may be set as the sixth ratio “sl”. On the other hand, a ratio of the number of incidences of relatively high shutter speed, which is higher than 80 percent to the maximum shutter speed, to the total detected number of incidences of electronic shutter speeds, may be set as the seventh ratio “sh”. Note that, the maximum shutter speed is represented by logarithm function when setting the sixth and seventh ratios. Further, the values of the reference ratios “CSL” and “CSH”, respectively, may be set in accordance with the connected video-scope. For example, the values of the reference ratios “CSL” and “CSH” may be set to ¾ and ¼, respectively.  
      With reference to FIGS.  18  to  20 , a fifth embodiment is explained. The fifth embodiment is different from the first embodiment in that an aberrant state of the electronic endoscope is transmitted to an outside apparatus, such as, a computer via network communication; and a maximum amount of illuminating light is detected. Other constructions are substantially the same as those of the first embodiment.  
       FIG. 18  is a block diagram of an electronic endoscope according to the fifth embodiment.  
      A system control circuit  40 A provided in a video-processor  30 A is connected to outside equipment, such as a computer, by a network cable. The data is transmitted between the video-processor  30 A and the outside equipment via an interface circuit (I/F)  52 . Herein, the video-processor  30 A sends the data via e-mail messages.  
       FIG. 19  is a view showing a main routine performed by the system control circuit  40 A.  
      In Step S 1501 , the initial setting process is performed. Further, the system control circuit  40 A detects whether any system error occurs when starting the electronic endoscope. In Step S 1502 , a process associated with the video-processor  30  is performed. In Step S 1503 , a process associated with the video-scope  10  is performed. In Step S 1504 , a process of self-diagnosis is performed.  
       FIG. 20  is a view showing a subroutine of Step S 1504  shown in  FIG. 19 .  
      In Step S 1601 , it is determined whether 0.5 seconds have elapsed since the previous diagnosis process. Herein, the amount of illuminating light is detected at 0.5 second intervals by detecting the opening-degree of the stop  31 . When it is determined that 0.5 seconds have not elapsed since the previous diagnosis process, the process is terminated. On the other hand, when it is determined that 0.5 second has passed from the previous diagnosis process; the process goes to Step S 1602 .  
      In Step S 1602 , it is determined whether the stop  31  fully opens; namely, whether the amount of illuminating light is a maximum amount. When it is determined that the stop  31  fully opens, the process goes to Step S 1603 . In Step S 1603 , a timer variable “cr 1 ” is incremented by 1. The timer variable “crl” is a variable for measuring an interval that the maximum illuminating light is maintained. On the other hand, when it is determined that the stop  31  does not fully open, the process goes to Step S 1604 . In Step S 1604 , the timer variable “cr 1 ”0 is set to 0. Note that the timer variable is initially set to 0 at Step S 1501  shown in  FIG. 19 .  
      In Step S 1605 , it is determined whether the timer variable “crl” equals a constant “CN 1 ”. Namely, the status of maximum illuminating light continues for a given interval. Herein, the constant “CN 1 ” is set to 120. Thus, in Step S 1605 , it is determined whether the status of maximum illuminating light continues for 60 seconds. In this embodiment, if the maximum amount of illuminating light continues for 60 seconds, it is determined that the auto-brightness adjustment process is in an aberrant state. When it is determined that the timer variable “cr 1 ” does not equal the constant “CN 1 ”, the process is terminated. On the other hand, when it is determined that the timer variable “cr 1 ” equals the constant “CN 1 ”, the process goes to Step S 1606 .  
      In Step S 1606 , it is determined whether a reporting restriction variable “cr 2 ” is lower than 2. The reporting restriction variable “cr 2 ” is a variable for restricting the number of times that the aberrant state is reported outside. Herein, the information is transmitted outside twice. When it is determined that the reporting restriction variable “cr 2 ” is not smaller than 2, the process is terminated. On the other hand, when it is determined that the reporting restriction variable “cr 2 ” is smaller than 2, the process goes to Step S 1607 . Note that, the reporting restriction variable “cr 2 ” is set to 0 at the initial setting process.  
      In Step S 1607 , data that reports an aberrant state of the electronic endoscope is transmitted from the video-processor  30  to an outside computer system provided in a repair center. At this time, data associated with the electronic endoscope, such as the endoscope name and a registration number, is simultaneously transmitted. Also, to report the aberrant state to the operator, character signals are output to the CRTC  45  so as to display character information that warns against use of the electronic endoscope. In Step S 208 , the reporting restriction variable “cr 2 ” is incremented by 1.  
      In this way, in the fifth embodiment, the auto-brightness adjustment process is carried out by adjusting the opening-degree of the stop, and the self-diagnosis process is carried out on the basis of the opening-degree. If a situation in which the opening-degree is at the maximum continues for 60 seconds, it is determined that the illuminating-light is in an aberrant state, and data that reports the aberrant state is transmitted to the outside equipment via the network (S 1607 ).  
      The interval over which the maximum opening-degree continues may be optionally set to another interval, instead of to 60 seconds. Also, when a situation in which the amount of illuminating light in the range of 70 percent to 100 percent of the maximum amount of illuminating-light continues for a given interval, it may be determined that the illuminating-light is in an aberrant state.  
      Finally, it will be understood by those skilled in the arts that the foregoing description is of preferred embodiments of the device, and that various changes and modifications may be made to the present invention without departing from the spirit and scope thereof.  
      The present disclosure relates to subject matter contained in Japanese Patent Applications No. 2005-34346l (filed on Nov. 29, 2005), No. 2005-343531 (filed on Nov. 29, 2005), No. 2005-343660 (filed on Nov. 29, 2005), and No. 2005-343704 (filed on Nov. 29, 2005), which are expressly incorporated herein, by reference, in their entireties.