in the following , a preferred embodiment of a method for resetting a cmos imaging element in an endoscope according to the present invention will be described in detail by reference to the accompanying drawings . fig1 is an entire configuration diagram illustrating the schematic configuration of an endoscope system according to one embodiment of the present invention . as shown in fig1 , an endoscope system 10 according to the present embodiment includes an endoscope apparatus ( an electronic endoscope , referred to as endoscope below ) 12 , a processor apparatus 14 , and a light source apparatus 16 . the endoscope 12 includes a flexible insertion portion 20 to be inserted into a body cavity of a patient ( a subject ), an operation portion 22 provided continuously to a proximal end portion of the insertion portion 20 , and a universal cord 24 connected to the processor apparatus 14 and the light source apparatus 16 . a distal end portion 26 where a cmos imaging element ( an imaging chip ) 54 which takes an image of the inside of a body cavity ( see fig3 ) or the like is incorporated is provided continuously to the distal end of the insertion portion 20 . a bending portion 28 where a plurality of bending pieces are connected together is provided posterior to the distal end portion 26 . the bending portion 28 bends vertically and horizontally when an angle knob 30 provided on the operation portion 22 is operated to push and pull a wire inserted through the insertion portion 20 . the distal end portion 26 is thereby oriented in a desired direction in a body cavity . the proximal end of the universal cord 24 is connected to a connector 36 . the connector 36 is of composite type . the processor apparatus 14 is connected to the connector 36 , and the light source apparatus 16 is also connected thereto . the processor apparatus 14 feeds power to the electronic endoscope 12 through a cable 68 ( see fig3 ) inserted through the universal cord 24 to control the driving of the cmos imaging element 54 . the processor apparatus 14 also receives an imaging signal transmitted from the cmos imaging element 54 through the cable 68 and performs various signal processing on the received imaging signal to convert the signal into image data . the image data converted in the processor apparatus 14 is displayed as an endoscope image on a monitor 38 connected to the processor apparatus 14 through a cable . the processor apparatus 14 is also electrically connected to the light source apparatus 16 through the connector 36 to collectively control the operation of the endoscope system 10 . fig2 is a front view illustrating the distal end portion 26 of the electronic endoscope 12 . as shown in fig2 , an observation window 40 , illumination windows 42 , a forceps outlet 44 , and an air / water supply nozzle 46 are provided in a distal end surface 26 a of the distal end portion 26 . the observation window 40 is arranged in the center on one side of the distal end portion 26 . the illumination windows 42 are arranged at two positions symmetrical with respect to the observation window 40 to project illumination light from the light source apparatus 16 onto a region to be observed in a body cavity . the forceps outlet 44 is connected to a forceps channel 70 ( see fig3 ) provided in the insertion portion 20 to communicate with a forceps inlet 34 ( see fig1 ) provided in the operation portion 22 . various treatment instruments where an injection needle , a diathermy knife or the like is provided at the distal end are inserted into the forceps inlet 34 , and the distal ends of various treatment instruments are exposed from the forceps outlet 44 . the air / water supply nozzle 46 sprays cleaning water or air supplied from an air / water supply device incorporated in the light source apparatus 16 to the observation window 40 or into a body cavity according to the operation of an air / water supply button 32 ( see fig1 ) provided on the operation portion 22 . fig3 is a side sectional view illustrating the distal end portion 26 of the endoscope 12 . as shown in fig3 , a lens barrel 52 which holds an objective optical system 50 for receiving image light of an observed region in a body cavity is provided posterior to the observation window 40 . the lens barrel 52 is mounted such that the optical axis of the objective optical system 50 is parallel to the center axis of the insertion portion 20 . a prism 56 which guides the image light of the observed region from the objective optical system 50 toward the imaging chip 54 by bending the image light at a substantially right angle is connected to the rear end of the lens barrel 52 . the cmos imaging element 54 is a monolithic semiconductor ( a so - called cmos sensor chip ) where a cmos sensor 58 and peripheral circuits which drive the cmos sensor 58 and input and output a signal into and from the cmos sensor 58 are integrally formed , and is mounted on a support substrate 62 . an imaging surface 58 a of the cmos sensor 58 is arranged facing an emission surface of the prism 56 . a cover glass 64 having a rectangular plate shape is attached onto the imaging surface 58 a via a spacer 63 having a rectangular frame shape . the cmos sensor 58 , the spacer 63 , and the cover glass 64 are bonded together with an adhesive . the imaging surface 58 a is thereby protected from ingress of dust or the like . a plurality of input - output terminals 62 a are provided side by side in the width direction of the support substrate 62 which is extended toward the rear end of the insertion portion 20 in a rear end portion of the support substrate 62 . signal lines 66 are bonded to the input - output terminals 62 a to mediate an exchange of various signals between the input - output terminals 62 a and the processor apparatus 14 through the universal cord 24 . the input - output terminals 62 a are electrically connected to the peripheral circuits 60 inside the cmos imaging element 54 through a wire or a bonding pad ( not shown ) formed on the support substrate 62 . the signal lines 66 are inserted in a bundle into the flexible tubular cable 68 . the cable 68 is inserted through the inside of each of the insertion portion 20 , the operation portion 22 , and the universal cord 24 , and connected to the connector 36 . although not shown in the drawings , an illumination portion is provided posterior to the illumination window 42 . an emission end of a light guide which guides the illumination light from the light source apparatus 16 is arranged at the illumination portion . the light guide is inserted through the inside of each of the insertion portion 20 , the operation portion 22 , and the universal cord 24 , and its incident end is connected to the connector 36 in a similar manner to the cable 68 . fig4 is a block diagram illustrating the configuration of the endoscope 12 and the processor apparatus 14 in the above endoscope system 10 . as shown in fig4 , the cmos imaging element 54 where the cmos sensor 58 and the peripheral circuits are formed on the same chip is incorporated in the distal end portion 26 of the endoscope 12 ( the insertion portion 20 ). the peripheral circuits include an analog front end ( afe ) 100 , a format conversion circuit 102 , a register 106 , a timing generator ( tg ) 104 , and an interface circuit 108 . the cmos sensor 58 includes a photodiode formed for each of pixels arranged in a matrix , a voltage conversion circuit which converts signal charges accumulated in the photodiode into a voltage signal , a scanning circuit ( a vertical scanning circuit and a horizontal scanning circuit ) which specifies the address ( the position ) of a pixel whose voltage signal is to be read out from the voltage conversion circuit , and an output circuit which sequentially outputs the voltage signals of the pixels read out by the scanning circuit . the afe 100 includes a correlated double sampling circuit ( cds ), an automatic gain control circuit ( agc ), and an analog / digital converter ( a / d ). the cds performs correlated double sampling processing on an imaging signal including the pixel signals sequentially read out from the pixels of the cmos sensor 58 , and eliminates reset noise and amplifier noise generated in the cmos sensor 58 . the agc amplifies the imaging signal from which noise has been eliminated by the cds at a gain ( an amplification factor ) specified by the processor apparatus 14 . the a / d converts the imaging signal amplified by the agc into a digital signal having a predetermined number of bits and outputs the digital signal . the format conversion circuit 102 converts the imaging signal digitalized and output by the a / d ( the digital imaging signal ) into a signal of a predetermined format determined in relation to the processor apparatus 14 , and the signal is thereby transmitted to the processor apparatus 14 . the timing generator ( tg ) 104 generates a drive pulse for reading out the pixel signal from the cmos sensor 58 , and a synchronizing pulse for each section such as the afe 100 . the register 106 is a memory which stores a parameter that determines the processing content of each section in the cmos imaging element 54 , and each section is processed according to the parameter . the interface circuit 108 inputs a control signal ( a command ) which sets the processing content of each section of the cmos imaging element 54 , a basic clock or the like from outside the cmos imaging element 54 , and outputs information of the parameter or the like set in the register 106 to outside . when a command is input to the interface circuit 108 , a parameter is set in the register 106 according to the command . the basic clock is given to the tg 104 , and the pulse to be fed to each section is produced based thereon . although not always provided , a relay board 110 is mounted on the operation portion 22 of the endoscope 12 . the relay board 110 includes a cpu 112 when a switch for electrical processing or the like is provided on the operation portion 22 or when zoom control or focus control of the objective optical system 50 ( see fig3 ) which forms an image of an object is performed on the cmos sensor 58 . the cpu 112 detects the state of the switch , and the objective optical system 50 is controlled by the cpu 112 and an unillustrated drive circuit . the cpu 112 is connected to a cpu 200 of the processor apparatus 14 via an unillustrated interface circuit . information of the switch state relating to processing performed in the processor apparatus 14 is thereby transmitted to the cpu 200 , and the cpu 200 executes the processing based on the switch state . the processor apparatus 14 includes the cpu 200 , an image processing circuit 208 , and a display control circuit 210 . the cpu 200 collectively controls the operation of each section in the processor apparatus 14 , and also exchanges various signals with the endoscope 12 as described above . for example , the cpu 200 gives the control signal or the basic clock to the cmos imaging element 54 , and acquires the control information from the cmos imaging element 54 . the image processing circuit 208 is shown in a simplified manner as a single circuit which performs image processing in the processor apparatus 14 such as color separation , color interpolation , gain correction , white balance adjustment , gamma correction , edge enhancement processing , and brightness adjustment processing on the input imaging signal . image data obtained by giving the image processing on the imaging signal input into the image processing circuit 208 is input into the display control circuit 210 at the subsequent stage . the display control circuit 210 generates a video signal according to the display format of the monitor 38 from the image data input from the image processing circuit 208 , and outputs the video signal to the monitor 38 . the monitor 38 thereby displays an endoscope image taken by the cmos imaging element 54 . a power circuit 212 is a circuit which supplies power of a necessary voltage to each section of the processor apparatus 14 , and the cmos imaging element 54 and the relay board 110 of the endoscope 12 . the cpu 200 of the processor apparatus 14 may not be directly connected to the interface circuit 108 of the cmos imaging element 54 , but the cpu 112 of the relay board 110 in the endoscope 12 may be connected thereto . accordingly , the exchange of signals between the cpu 200 of the processor apparatus 14 and the cmos imaging element 54 may be performed via the cpu 112 , or the cpu 112 may control the cmos imaging element 54 . although reset control described below is entirely performed based on an instruction from the cpu 200 of the processor apparatus 14 , the control may be also partly or entirely performed by the cpu 112 ( a control circuit ) in the endoscope 12 , not the cpu 200 . a method for resetting the cmos imaging element 54 in the endoscope 12 of the endoscope system 10 having the aforementioned configuration will be described . fig5 is a block diagram illustrating a connection line between a configuration section relating to reset of the cmos imaging element 54 and the processor apparatus 14 . in fig5 , a video processing section ( a signal processing section ) 300 representing the configuration section relating to the signal processing such as the afe 100 and the format conversion circuit 102 in fig4 , the register 106 in fig4 , and a communication interface ( a communication if ) 302 of the interface circuit 108 in fig4 which performs serial communication with the cpu 200 are shown in the cmos imaging element 54 . a serial communication terminal 310 , a device reset terminal 312 , and a power terminal 314 are also provided as a chip terminal on the cmos imaging element 54 . a serial communication line 320 which connects the cpu 200 of the processor apparatus 14 and the serial communication terminal 310 , a device reset line 322 which connects the cpu 200 and the device reset terminal 312 , and a power supply line 324 which connects the power circuit 212 of the processor apparatus 14 and the power terminal 314 are also shown . the register 106 is the memory which stores the value that determines the control content of the cmos sensor 58 or the processing content of the video processing section 300 ( vh width , shutter speed or the like ) as described above . each section of the cmos imaging element 54 executes the processing according to the value in the register 106 by reference to the value in the register 106 . the communication if 302 is connected to the serial communication terminal 310 inside the cmos imaging element 54 . when receiving a control signal ( a command ) from the cpu 200 of the processor apparatus 14 through the serial communication line as described above , the communication if 302 decodes the control signal and sets a set value according to the content of the control signal in the register 106 . the processing instructed by the control signal is thereby executed in each section such as the video processing section 300 . fig6 is a flowchart illustrating the procedure of the resetting method when the cmos imaging element 54 having the configuration as shown in fig5 is out of control . for example , when the cpu 200 of the processor apparatus 14 transmits a control signal to give a predetermined control instruction to the cmos imaging element 54 through the serial communication line 320 as normal processing while the cmos imaging element 54 is taking an image , the cpu 200 waits until a response signal indicating that the control signal has been received is transmitted from the cmos imaging element 54 . in a case where the response signal is not transmitted after passage of a predetermined time period , the cpu 200 transmits the same control signal again and waits until the response signal is transmitted . the cpu 200 repeats the processing up to a predetermined number of times until the response signal is transmitted ( step s 10 ). the processing is referred to as an operation state determining process of the cmos imaging element 54 . the cpu 200 determines whether the cmos imaging element 54 is in a normal state or in an abnormal state ( out of control ) based on whether or not the response signal is finally obtained from the cmos imaging element 54 after performing the operation state determining process of the cmos imaging element 54 ( step s 12 ). when it is determined that the cmos imaging element 54 is in a normal state , the operation proceeds to normal processing ( a normal process ). meanwhile , when it is determined that the cmos imaging element 54 is out of control , the cpu 200 transmits a control signal to eliminate the control signals accumulated in the communication if 302 since there is a possibility that an incorrect control signal has been given to the communication if 302 due to noise on the serial communication line ( step s 14 ). the cpu 200 then executes the operation state determining process in a similar manner to steps s 10 and s 12 ( step s 16 ) to determine whether or not the cmos imaging element 54 is in a normal state ( step s 18 ). when it is determined that the cmos imaging element 54 is in a normal state in step s 18 , the operation proceeds to the normal process . when it is determined that the cmos imaging element 54 is out of control , the cpu 200 recognizes that there is a problem with the cmos imaging element 54 , and sequentially performs the following processes to reset the cmos imaging element 54 . first , the cpu 200 executes soft reset where the cmos imaging element 54 can be restored to a normal operation at high speed ( step s 20 ). the soft reset is executed by transmitting a control signal to execute the soft reset through the serial communication line 320 from the cpu 200 . when the communication if 302 receives the control signal , the data recorded in the register 106 is all initialized . the cpu 200 executes the operation state determining process in a similar manner to steps s 10 and s 12 ( step s 22 ) to determine whether or not the cmos imaging element 54 is in a normal state ( step s 24 ). when it is determined that the cmos imaging element 54 is in a normal state , the reset process is terminated , and the operation proceeds to the normal process . when it is determined that the cmos imaging element 54 is out of control in step s 24 , the cpu 200 subsequently executes device reset ( step s 26 ). the device reset is performed by transmitting a predetermined reset signal ( a pulse signal ) to the device reset terminal 312 provided as the chip terminal on the cmos imaging element 54 as shown in fig5 . the video processing section 300 is initialized by the device reset . the cpu 200 executes the operation state determining process in a similar manner to steps s 10 and s 12 ( step s 28 ) to determine whether or not the cmos imaging element 54 is in a normal state ( step s 30 ). when it is determined that the cmos imaging element 54 is in a normal state , the reset process is terminated , and the operation proceeds to the normal process . when it is determined that the cmos imaging element 54 is out of control again in step s 30 , the cpu 200 recognizes that there is a problem with the entire cmos imaging element 54 , and temporarily stops ( off ) power supply to the power terminal 314 of the cmos imaging element 54 from the power circuit 212 through the power supply line 324 , and restarts ( on ) the power supply after passage of a predetermined time period ( step s 32 ). when the power supply is temporarily stopped and restarted , the cmos imaging element 54 is reliably restored to a normal state unless the cmos imaging element 54 is broken . thus , the operation proceeds to the normal process . it is necessary to set the set value in the register 106 again after performing the reset process of any of the soft reset ( step s 20 ), the device reset ( step s 26 ), and the power supply stop and restart ( step s 32 ). the register 106 may be set again after the cmos imaging element 54 is determined to be in a normal state by each of the reset process and the operation proceeds to the normal process . alternatively , the register 106 may be set again along with the operation state determining process by the control signal transmitted from the cpu 200 to the cmos imaging element 54 when the operation state determining process is executed after the soft reset and the device reset . the aforementioned method of the operation state determining process is just an example , and the cmos imaging element 54 may be determined whether to be in a normal state or not by another method . for example , the imaging signal output from the cmos imaging element 54 is a digital signal , and can contain desired additional information . thus , the imaging signal may be allowed to contain information indicating the operation state of the cmos imaging element 54 as the additional information , the processor apparatus 14 may extract the additional information from the imaging signal obtained from the cmos imaging element 54 , and the cpu 200 may thereby determine whether or not the operation state of the cmos imaging element 54 is normal based on the additional information . alternatively , the cpu 200 may monitor a change in the endoscope image ( a moving image ) generated by the imaging signal obtained from the cmos imaging element 54 , to determine whether or not the cmos imaging element 54 is normal based on the change . for example , when there is no change in the endoscope image , the cmos imaging element 54 can be determined to be not in a normal state . also , in the aforementioned embodiment , there is a possibility that noise occurs on the device reset line 322 connected to the device reset terminal 312 of the cmos imaging element 54 , and the device reset is unintentionally executed . thus , the device reset may be selectively enabled and disabled based on the set value of a predetermined address in the register 106 ( a switch 330 of the register in fig5 corresponds thereto ), so that the device reset may be enabled in an initial state after the power is turned on , and may be switched to a disabled state by rewriting the set value in the register 106 by a control signal transmitted from the cpu 200 to the communication if 302 . the cpu 200 of the processor apparatus 14 may not be directly connected to the interface circuit 108 ( the communication if 302 ) of the cmos imaging element 54 , but the control circuit in the endoscope 12 such as the cpu 112 of the relay board 110 in the endoscope 12 may be connected thereto as described above . accordingly , the exchange of signals between the cpu 200 of the processor apparatus 14 and the cmos imaging element 54 may be performed via the control circuit in the endoscope 12 , or the control circuit in the endoscope 12 may control the cmos imaging element 54 . in this case , the above reset control may be partly or entirely performed by the control circuit in the endoscope 12 , not the cpu 200 . also , there is a case in which the start and stop of power supply to the cmos imaging element 54 is controlled by the control circuit in the endoscope 12 in any of the cases in which the cpu 200 of the processor apparatus 14 is directly connected to the interface circuit 108 of the cmos imaging element 54 and the control circuit in the endoscope is connected to the interface circuit 108 of the cmos imaging element 54 . in this case , the control circuit in the endoscope 12 performs the control on the start and stop of power supply to the cmos imaging element 54 in the procedure of the resetting method . moreover , the cpu 112 , the relay board 110 and the control circuit described above may be provided at the position of the connector 36 or the like of the universal cord 24 of the endoscope 12 , and the present invention is not limited to the case where the cpu 112 , the relay board 110 and the control circuit are provided at the operation portion 22 .