JP2007029746A - Endoscope apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endoscope apparatus, obtaining a suitable observation image according to an observation environment by changing the light emission timing even in the case of color imaging with area sequential illumination. <P>SOLUTION: Light emitting diodes 26a, 26b, 26c emitting light in red, green and blue are housed in the tip part of an endoscope 2 having a built-in CCD 18, and connected to an LED driver 28 in a pulse lighting device. The LED driver is connected to a timing generator 41 for controlling the operation timing with a driver 30 for driving the CCD 18, and the timing generator 41 is further connected to a drive change-over switch 29. The pulse lighting time of the LED 26a, 26b, 26c is changed through the LED driver 28 by the change-over operation of the drive change-over switch 29, and according to the change, the exposure time of the CCD 18 is controlled. Further, the signal processing for an output signal of the CCD 18 is controlled by the timing generator 41, and according to the working environment, the exposure time can be easily changed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an endoscope that performs color imaging under field sequential illumination using pulse lighting.

  In recent years, endoscopes have been widely used in the medical field and the industrial field. In addition to the optical type that transmits an optical image using an image guide, an electronic endoscope having a built-in image sensor has been adopted as this endoscope.

  FIG. 12 shows a conventional electronic endoscope apparatus 1. The electronic endoscope apparatus 1 has an electronic endoscope 2, and the electronic endoscope 2 has an elongated and flexible insertion portion 3, for example, and has a large diameter at the rear end of the insertion portion 3. An operation unit 4 is continuously provided. From the vicinity of the rear end of the operation unit 4, a base end of a flexible universal cable 5 is extended laterally, and a connector 6 is provided at the end of the cable 5.

  The electronic endoscope 2 is connected via the connector 6 to a video processor 9 in which a light source device 7 'and a signal processing circuit 8 shown in FIG. Further, a color monitor 10 is connected to the video processor 9. On the distal end side of the insertion portion 3, a rigid distal end portion 11 and a bending portion 12 that can be bent on the rear side adjacent to the distal end portion 11 are sequentially provided.

  Further, the bending portion 12 can be bent in the left-right direction or the up-down direction by rotating the bending operation knob 14 provided in the operation portion 4. The operation unit 4 is provided with an insertion port 15 communicating with a treatment instrument channel (not shown) provided in the insertion unit 3. FIG. 13 shows the configuration of the signal processing system.

  As shown in FIG. 13, a light guide 16 that transmits illumination light is inserted into the insertion portion 3 of the electronic endoscope 2. The distal end surface of the light guide 16 is disposed at the distal end portion 11 of the insertion portion 3 so that illumination light can be emitted from the distal end portion 11. Further, the incident end side of the light guide 16 is inserted into the universal cable 5 and connected to the connector 6.

  The distal end portion 11 is provided with an objective lens system 17, and a charge coupled device (abbreviated as CCD) 18 as a solid-state imaging device is disposed at the image forming position of the objective lens system 17. The solid-state imaging device 18 has sensitivity in a wide wavelength region from the ultraviolet region to the infrared region including the visible region. Signal lines 19 and 20 are connected to the CCD 18, and these signal lines 19 and 20 are inserted into the insertion portion 3 and the universal cable 5 and connected to the connector 6.

  On the other hand, the light source device 7 ′ provided in the video processor 9 includes a lamp 21 that emits broadband light from ultraviolet light to infrared light. As the lamp 21, a general xenon lamp or the like can be used. The xenon lamp emits a large amount of not only visible light but also ultraviolet light and infrared light.

  The lamp 21 is supplied with electric power by a power supply unit 22. A rotary filter 24 that is driven to rotate by a motor 23 is disposed in front of the lamp 21. In the rotary filter 24, filters that transmit light in each wavelength region of red (R), green (G), and blue (B) for normal observation are arranged along the circumferential direction. At this time, the rotary filter rotates at a period of 1 / 20S.

  The motor 23 is driven by a motor driver 25 with its rotation controlled. The light transmitted through the rotary filter 24 and separated in time series into light of each wavelength region of R, G, and B is further incident on the incident end of the light guide 16, and the tip end portion is passed through the light guide 16. 11 and is emitted from the tip 11 to illuminate an observation site or the like.

  The return light from the subject (subject) such as the observation site by the illumination light is imaged on the CCD 18 by the objective lens system 17 and subjected to photoelectric conversion. A CCD drive signal (simply abbreviated as a drive signal) from the driver 30 in the video processor 9 is applied to the CCD 18 via the signal line 19, and an image of the subject photoelectrically converted by the drive signal is applied to the CCD 18. Only the corresponding electrical signal (video signal) is read out.

  The electrical signal read from the CCD 18 is input to the preamplifier 31 provided in the video processor 9 or the electronic endoscope 2 via the signal line 20. The video signal amplified by the preamplifier 31 is input to the process circuit 32, subjected to signal processing such as γ correction and white balance, and is converted into a digital signal by the A / D converter 33.

  This digital video signal is converted by the select circuit 34 into, for example, three memories (1) 35a, a memory (2) 35b, and a memory (3) corresponding to each color of red (R), green (G), and blue (B). 35c is selectively stored. The R, G, B color signals stored in the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c are simultaneously read and input to the color correction circuit 36.

  In the color correction circuit 36, the R and B color signals are input to the coefficient units 36a and 36b, respectively. Coefficient units 36a and 36b convert the magnitude of the input signal to a predetermined magnitude. This conversion is performed using a preset value or a value set from the outside.

  The R, G, B color signals color-corrected by the color correction circuit 36 are converted into analog signals by the D / A converter 37, and output from the RGB output terminal 38 as R, G, B color signals. Are input to an encoder 39, converted into an NTSC composite signal by the encoder 39, and output from an NTSC composite signal output terminal 40.

  The R, G, B color signals or the NTSC composite signal is input to the color monitor 10, and the color monitor 10 displays the observation region in color.

  The video processor 9 is provided with a timing generator 41 for generating the timing of the entire system. The timing generator 41 synchronizes the circuits such as the motor driver 25, the driver 30, and the select circuit 34. Yes.

  However, in the conventional frame sequential method, in order to obtain an RGB image, RGB filters 24R, 24G, and 24B are pasted on the transmission window of the rotary filter 24 as shown in FIG. 14, and the rotary filter 24 is set to 1/20 second. Rotate at a constant frequency.

  FIG. 15 shows the conventional CCD exposure timing, CCD drive pulse, and light emission timing of the light source. Since this method is a surface sequential method, as shown in FIG. 15, the light emission timing of the light source is obtained by rotating the rotation filter in the order of RGB to obtain illumination light of each color.

The CCD exposure timing is 1/60 second for each color. When the exposure period ends, the CCD drive signal generates a vertical transfer pulse and transfers the accumulated charges to the horizontal transfer unit. The RGB video signals obtained in this way are synchronized in the signal processing process of the signal processing circuit 8, and one screen of RGB is obtained in 1/20 second.
JP-A-9-285443

  For this reason, the exposure time for each of the RGB CCDs 18 is determined. For example, when a dark subject is photographed, even if an attempt is made to increase the exposure time, the rotation filter 24 rotates at a constant frequency, so The exposure time has been decided. In addition, in an observation part such as the esophagus where the movement is fast, a color shift peculiar to the frame sequential method becomes conspicuous. To reduce it, a method of shortening the exposure time is conceivable. Since the lens rotates at a constant frequency, the color shift cannot be reduced.

  In the endoscopic observation image, on a screen where the near point part is bright and the far point part is dark, if the brightness is adjusted to a dark place at the far point, the near point is too bright, and When the brightness was adjusted to the point, it was considered that the far point was dark and the observation was impossible.

  Even in such an observation image, it is conceivable to obtain an optimal observation image by adjusting the exposure time. However, since the period of the rotary filter 24 is constant, appropriate exposure control cannot be performed. .

  The present invention has been made in view of the above-described points. Even when color imaging is performed under frame sequential illumination, an appropriate observation image can be obtained according to the observation environment by changing the light emission timing. An object is to provide an obtained endoscope.

  An endoscope according to one aspect of the present invention includes a plurality of light emitting units that sequentially emit illumination light, and an imaging unit that captures an image of a subject that is sequentially illuminated by the illumination light and generates an imaging signal. In the mirror, the plurality of light emitting means is characterized in that any one of the other light emitting means is turned on at a timing when lighting of any one of the plurality of light emitting means is completed.

  The endoscope of the present invention has an advantage that an appropriate observation image can be obtained according to the observation environment by changing the light emission timing even when color imaging is performed under frame sequential illumination.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
1 to 4 relate to a first embodiment of the present invention. FIG. 1 shows a configuration of a signal processing system and the like of the electronic endoscope apparatus of the first embodiment, and FIG. 2 shows a normal use state. 3 is a timing chart, FIG. 3 is a timing chart showing the operation when the short exposure time is set, and FIG. 4 is a timing chart showing the operation when the long exposure time is set.
The overall configuration of the electronic endoscope apparatus 1 according to the first embodiment of the present invention is the same as that shown in FIG.

  The electronic endoscope apparatus 1 has an electronic endoscope 2, and the electronic endoscope 2 has an elongated and flexible insertion portion 3, for example, and has a large diameter at the rear end of the insertion portion 3. An operation unit 4 is continuously provided. From the vicinity of the rear end of the operation unit 4, a base end of a flexible universal cable 5 is extended laterally, and a connector 6 is provided at the end of the cable 5.

  The electronic endoscope 2 is connected to a video processor 9 having a built-in pulse lighting device 7 and a signal processing circuit 8 via the connector 6 (as shown in FIG. 1).

  Further, a color monitor 10 is connected to the video processor 9. On the distal end side of the insertion portion 3, a rigid distal end portion 11 and a bending portion 12 that can be bent on the rear side adjacent to the distal end portion 11 are sequentially provided.

  Further, the bending portion 12 can be bent in the left-right direction or the up-down direction by rotating the bending operation knob 14 provided in the operation portion 4. The operation unit 4 is provided with an insertion port 15 communicating with a treatment instrument channel (not shown) provided in the insertion unit 3.

  As shown in FIG. 1, the internal configuration of the electronic endoscope apparatus 1 according to the first embodiment is the same as the conventional electronic endoscope apparatus 1 shown in FIG. Instead, three light emitting elements (abbreviated as LEDs) 26a, 26b, and 26c are provided in the distal end portion 11, and the signal lines 27a, 27b, and 27c connected to the LEDs 26a, 26b, and 26c are connected to the connector 6 in FIG. Connected to the contact.

  Further, the electronic endoscope apparatus 1 according to the first embodiment has a structure in which the light source device 7 'portion in the conventional electronic endoscope apparatus 1 of FIG. I have to.

  The timing generator 41 that controls the overall timing of the electronic endoscope apparatus 1 includes a drive signal to the CCD 18 and pulsed lighting timings of the LEDs 26a, 26b, and 26c (more specifically, the lighting timing itself and its timing). A drive changeover switch 29 for switching the lighting time (lighting time from lighting timing) is connected.

  The timing generator 41 is connected to a memory controller 43 that controls writing to and reading from the three memories (1) 35a, (2) 35b, and (3) 35c.

  Then, in the normal use state where the drive changeover switch 29 is not operated or in the standard selection setting state, as shown in FIG. 2 as in the case of R, G, B frame sequential illumination as in the conventional example of FIG. Light is emitted at a period of 1/60 seconds.

  From this state, the drive changeover switch 29 can be selected for a short lighting time (light emission time) and, conversely, a long lighting time, so that the pulse lighting time can be selected according to the status of the endoscopy. For example, the drive changeover switch 29 can select three contact points. Normally, the standard set contact point is turned on, and the other two contacts can be turned on from this state. Output to the timing generator.

  In response to this selection, an instruction signal of the lighting time is sent from the drive changeover switch 29 to the timing generator, and the timing generator controls the LED driver 28 to control the lighting of the LED 27 with the lighting time corresponding to the instruction signal. Send a signal (as a control signal).

This timing signal is also sent to the driver 30 and the memory controller 43. Even when the lighting time is changed, a drive signal is applied to the CCD 18 at the timing of the end of the changed lighting time, and an image pickup signal obtained by photoelectric conversion is obtained from the CCD 18. Control to output from. When the signal processing circuit 9 performs signal processing, the memory controller 43 performs signal processing and writes the memory 35 in a writing state at the timing when it is input to the memory 35. Is also controlled to be performed in synchronization with the lighting.
The configuration of the present embodiment will be described in detail as follows.

As shown in FIG. 1, LEDs 26a, 26b, and 26c that emit light in three wavelength ranges, specifically, red, green, and blue, are provided in the distal end portion 11 of the electronic endoscope 2, and the LED 26a. , 26b, 26c are inserted into the electronic endoscope 2 and connected to the LED driver 28 of the pulse lighting device 7 through the contacts of the connector 6 in FIG.
Then, the LEDs 26a, 26b, and 26c are pulse-lit by a pulsed drive signal from the LED driver 28, and illuminate the subject in a frame sequential manner.

  The distal end portion 11 is provided with an objective lens system 17, and a charge coupled device (abbreviated as CCD) 18 as a solid-state imaging device is disposed at the image forming position of the objective lens system 17. The CCD 18 has sensitivity in a wide wavelength range from the ultraviolet region to the infrared region including the visible region. Signal lines 19 and 20 are connected to the CCD 18, and these signal lines 19 and 20 are inserted into the insertion portion 3 and the universal cable 5 and connected to the connector 6.

  On the other hand, the pulse lighting device 7 provided in the video processor 9 has the LED driver 28 as described above, and the LEDs 26a, 26b, and 26c are pulse-lit by the LED drive signal from the LED driver, and the subject is sequentially surface-sequentially. Illuminate with. That is, the subject is illuminated with light in each wavelength region of red (R), green (G), and blue (B).

  The return light from the subject (subject) such as the observation site by the illumination light is imaged on the CCD 18 by the objective lens system 17 and subjected to photoelectric conversion. A CCD drive signal from a driver 30 in the video processor 9 is applied to the CCD 18 via the signal line 19, and an imaging signal (video) corresponding to an image of a subject photoelectrically converted by the CCD drive signal. Signal) is read out.

  The line-sequential imaging signal read from the CCD 18 is input to a preamplifier 31 provided in the video processor 9 or the electronic endoscope 2 via the signal line 20. The video signal amplified by the preamplifier 31 is input to the process circuit 32, subjected to signal processing such as γ correction and white balance, and is converted into a digital signal by the A / D converter 33.

  This digital video signal is converted by the select circuit 34 into, for example, three memories (1) 35a, a memory (2) 35b, and a memory (3) corresponding to each color of red (R), green (G), and blue (B). 35c is selectively stored. The R, G, B color signals stored in the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c are simultaneously read and input to the color correction circuit 36.

  In the color correction circuit 36, the R and B color signals are input to the coefficient units 36a and 36b, respectively. Coefficient units 36a and 36b convert the magnitude of the input signal to a predetermined magnitude. This conversion is performed using a preset value or a value set from the outside.

  The R, G, B color signals color-corrected by the color correction circuit 36 are converted into analog signals by the D / A converter 37, and output from the RGB output terminal 38 as R, G, B color signals. Are input to an encoder 39, converted into an NTSC composite signal by the encoder 39, and output from an NTSC composite signal output terminal 40.

  The R, G, B color signals or the NTSC composite signal is input to the color monitor 10, and the color monitor 10 displays the observation region in color.

  The video processor 9 is provided with a timing generator 41 for generating the timing of the entire system. The timing generator 41 synchronizes the circuits such as the LED driver 28, the driver 30, and the select circuit 34. Yes.

  Next, the operation of the first embodiment will be described with reference to FIG. 2, FIG. 3 and FIG. These figures show timing charts of CCD exposure timing, (one CCD transfer signal forming vertical transfer pulse), and LED lighting timing. Note that R, G, and B respectively indicate R, G, and B light emission by the LEDs 26a, 26b, and 26c at the LED lighting timing in FIG.

  In this embodiment, when the drive changeover switch 29 is not operated or when a standard setting state is selected, the CCD exposure timing, vertical transfer pulse, and LED lighting timing shown in FIG. 2 are obtained.

  That is, the LEDs 26a, 26b, and 26c are sequentially turned on at a period of 1/60 seconds, and the signal charge of the light receiving portion (photosensitive portion) of the CCD 18 exposed during the previous lighting period during the extinguishing period at 1/60 seconds is a vertical transfer portion. The data is output from the CCD 18 by performing a transfer with a vertical transfer pulse transferred in the horizontal direction and a horizontal transfer with a horizontal transfer pulse (not shown). Then, signal processing is performed on the signal processing circuit 8 side in the same manner as in the conventional example, thereby displaying on the color monitor 10.

  In this state of use, the illumination means is different, but the illumination on the subject, the imaging by the CCD 18 under the illumination, and the signal processing for the imaging signal are the same as in the conventional example.

  Next, for example, in an observation site such as an esophagus where the subject is sufficiently bright or moves very quickly, the drive changeover switch 29 is switched to the shorter light emission time or shorter exposure time side.

  In the present embodiment, when the drive changeover switch 29 is switched to a short light emission time, the LEDs 26a, 26b, and 26c are sequentially turned on at a cycle of 1/120 seconds as shown in FIG. The signal charge of the light receiving portion of the CCD 18 exposed during the lighting period is transferred by a vertical transfer pulse and transferred in the horizontal direction by a horizontal transfer pulse (not shown) and output from the CCD 18.

On the signal processing circuit 8 side, the signal input in this short cycle is subjected to γ correction by the process circuit 32 and converted into a digital signal by the A / D converter 33. Then, according to the signals of the respective color components captured by the select circuit 34 under, for example, red (R), green (G), and blue (B) illumination, three memories (1) 35a and memories (2) 35b , And sequentially stored in the memory (3) 35c.
For example, a signal imaged by the CCD 18 under red (R) emission by the LED 26a is temporarily stored in the memory (1) 35a.

  The R, G, B color signals stored in the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c are simultaneously read out at a period of 1/30 seconds, for example, and pass through the color correction circuit 36 and the like. Are displayed on the color monitor 10.

  In this case, lighting (illumination) is performed with a period of, for example, 1/120 seconds that is much shorter than usual, and CCD driving and signal processing are performed, so that an object such as an organ in a region close to the heart that moves quickly is imaged. Even in this case, the color misregistration between RGB can be reduced, and an image with good image quality suitable for observation can be obtained.

On the other hand, even when the subject is very dark and the amount of light of the LEDs 26a, 26b, and 26c is maximized, when the observation image is very dark, specifically, when observing a far point portion, the drive changeover switch 29 is made to emit a long light. Switch to the time side.

  In this case, as shown in FIG. 4, the LEDs 26a, 26b, and 26c are sequentially turned on at a period of 1/30 seconds, and the light receiving portion of the CCD 18 exposed during the previous lighting period during the extinguishing period at 1/30 seconds. These signal charges are transferred by a vertical transfer pulse and transferred in the horizontal direction by a horizontal transfer pulse (not shown) and output from the CCD 18.

  And according to the signal of each color component imaged under illumination of red (R), green (G), and blue (B), three memories (1) 35a, memory (2) 35b, and memory (3) 35c Are stored in sequence.

  The R, G, and B color signals stored in the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c are simultaneously read out at a period of 1/30 seconds, for example, and the color correction circuit 36 and the like. And displayed on the color monitor 10.

In this case, since the lighting (illumination) is performed in a long period of 1/30 seconds, the CCD is driven, and the signal processing is performed even in a normal case, the amount of illumination light can be increased even for a dark subject ( When it is described on the imaging side, the imaging period or the exposure period can be increased), and the S / N of the imaged signal can be increased.
Therefore, an observation image with good image quality can be displayed on the color monitor 10.

  As described above, according to the present embodiment, by operating the drive changeover switch 29 according to the state of the subject to be observed or the observation environment, not only in the case of light emission in the standard light emission time, CCD drive and signal processing, An observation image can be easily obtained by light emission in a shorter light emission time, CCD drive and signal processing, and light emission in a longer light emission time, CCD drive and signal processing.

  In the conventional example, the rotation filter 24 is rotated by the motor 23, and thus the rotation speed cannot be easily changed. However, in the present embodiment, the plurality of LEDs 26a, 26b, and 26c are sequentially turned on. By changing, an appropriate observation image can be easily obtained according to the observation environment.

  The drive changeover switch 29 is arbitrarily switched by the operator using a manual switch or the like (not shown). However, a detection circuit for detecting the luminance level and motion information of the video signal is provided, and automatically based on the detection result. You may make it switch.

  In the above description, the case of imaging with a longer lighting time and three imaging with a shorter lighting time from the standard state has been described. However, it is possible to easily change to four or more.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This embodiment includes dynamic range expansion means for combining images captured at two or more different exposure times with a composite function, and each of the two or more different exposure times can be varied to an arbitrary length. As described above, a timing control circuit for controlling the exposure timing of the CCD 18, the emission timing of the LED light source, and the timing of synchronizing the video signals obtained in line sequential order is provided.

FIG. 5 shows a signal processing system according to the second embodiment. In this signal processing system in FIG. 1, the output signal of the A / D converter 33 is input to the time axis conversion circuit 43, and the time axis is adjusted.
The output signal of the time axis conversion circuit 43 is input to a gradation calculation circuit (gradation processing circuit) 44, where gradation calculation or gradation conversion processing is performed. The output signals of the gradation calculation circuit 44 are input to the adder 45 and added, and then input to the 55 selector circuit 34.
The time axis conversion circuit 43 is connected to the timing generator 41 and receives a timing signal for synchronization.

  In the present embodiment, when the drive changeover switch 29 selects the standard state, it performs light emission, imaging, and signal processing in a normal light emission time as shown in FIG. 2, but an observation image with a further expanded dynamic range. The dynamic range expansion mode can be selected.

When the dynamic range expansion mode is selected, the LEDs 26a, 26b, and 26c are turned on for two types of lighting times, and signals are captured based on one lighting time and images are captured based on the other lighting time. The signal is adjusted by the time axis conversion circuit 43 to synchronize the signal, the gradation calculation circuit 44 performs gradation calculation (gradation conversion processing), and the adder 45 adds the dynamic range to expand the dynamic range. These signals are sequentially stored in the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c via the selector circuit 34.
The signals stored in the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c are simultaneously read and displayed on the color monitor 10.

  The other configuration is the same as that of the first embodiment. When the standard state of the drive changeover switch 29 is selected, the output signal of the A / D converter 33 passes through the time axis conversion circuit 43, the gradation calculation circuit 44 and the adder 45 and passes through the selector circuit 34. The data is input to the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c.

FIG. 6 is a timing chart showing an example of the operation of the second embodiment.
When the drive changeover switch 29 in FIG. 5 is selected in the standard state, it operates according to the timing chart as shown in FIG.
On the other hand, when the dynamic range expansion mode is selected by operating the drive changeover switch 29, the operation is performed at the CCD exposure timing, the vertical transfer pulse, and the LED lighting timing shown in FIG.

That is, the LEDs 26a, 26b, and 26c are lit with a period of 1/60 seconds for a long period of R lighting and a short period of R lighting, a long period of G lighting, a short period of G lighting, a long period of B lighting, and a short period of time. B lights up.
In synchronism with these lighting operations, a CCD drive signal is applied to the CCD 18 during each extinguishing time after the lighting time (only the vertical transfer pulse is shown in FIG. 6).

  For example, a signal output from the CCD 18 under long-time R lighting (long exposure) is temporarily stored in, for example, a frame memory of the time axis conversion circuit 43.

  The signal (short-time exposure) imaged under the next short-time R lighting is read out from the signal temporarily stored in the frame memory at the timing inputted to the time-axis conversion circuit 43, and the time axis is simultaneously The two signals are input to the gradation calculation circuit 44, where gradation calculation or gradation conversion processing is performed, and the adder 45 adds the signals to perform dynamic range expansion synthesis processing.

  By the addition in the gradation calculation circuit 44 and the adder 45, gradation calculation is performed so as to expand the optimum dynamic range based on a certain mixing function, or two lookup tables having different input / output characteristics. Is used to perform gradation conversion. A specific example of this gradation calculation is shown in FIG.

A straight line indicated by a symbol A in FIG. 7 indicates a CCD output (video output) with respect to an incident light amount under long exposure (imaging time with a period of 1/60 seconds).
When the subject is bright, it is saturated at symbol A 'in FIG.

  On the other hand, the straight line C in FIG. 7 shows a case where the same subject is imaged with short exposure (for example, about 1/120 second). In this case, saturation does not occur because the exposure time is short. These two images are subjected to gradation calculation by different operations and added and synthesized by an adder 45, or gradation conversion is performed through two look-up tables having different input / output characteristics. By adding them, it can be converted into a CCD output having a wide dynamic range as indicated by the symbol B.

  Such processing is performed on each RGB signal, converted into a signal with a wide dynamic range, and then input to the memory (1) 35a, the memory (2) 35b, and the memory (3) 35c via the select circuit 34. By synchronizing, a predetermined video signal is obtained. Then, it is displayed on the color monitor 10.

According to the present embodiment, each of the LEDs 26a, 26b, and 26c is lit for two types of lighting times, and a signal imaged under one lighting time and a signal imaged under the other lighting time. In addition, since a means for converting the gradation characteristics into a signal by expanding the dynamic range by combining the characteristics is provided, a dark image can be obtained even when a dark image portion and a bright image portion are mixed. The portion can be displayed more clearly, and the bright image portion can also be displayed without whiteout.
That is, since an image can be displayed with a wide dynamic range, it is possible to obtain an image with good image quality that is easy to diagnose when diagnosing from an observed image.

  In FIG. 5, gradation calculation or gradation characteristic conversion is performed after passing through the time axis conversion circuit 43, but time axis conversion processing is performed after gradation calculation or gradation characteristic conversion. Anyway.

  For example, after a tone characteristic is converted for a signal captured under a long exposure by a common tone calculation circuit, the signal is temporarily stored in the frame memory of the time axis conversion circuit 43 for a short exposure. After the conversion of different gradation characteristics to the originally captured signal, the signal temporarily stored in the frame memory is read at the timing input to the time axis conversion circuit 43 and input to the adder 45 for addition. Thus, a signal having a wide dynamic range may be used.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 8 is a timing chart for explaining the operation in the third embodiment.
When observing, if the near point of the subject is normal brightness and the far point is very dark, and the brightness difference between the near point and the far point is large, the CCD will be By extending the exposure time, even if the observation point at the far point becomes the optimum brightness for observation, the near point becomes very bright and the white spot becomes white.

  In other words, by increasing the exposure time, the dark part at the far point becomes bright enough to be observed, but on the other hand, the near point part stops and the image becomes very difficult to observe when viewed as a whole. End up.

  Therefore, the present embodiment aims to prevent the near point from being lost and becoming difficult to observe by using the same method as the dynamic range expansion mode as in the second embodiment.

  The third embodiment also uses a signal processing circuit 8 shown in FIG. 5 as in the second embodiment. By switching the drive changeover switch 29, the timing generator 41 is switched from the light emission and exposure time in the standard mode, and two or more different exposures each longer than the lighting times of the LEDs 26a, 26b, and 26c described in the second embodiment. An observation image with time is obtained.

  For example, R long-time lighting, R short-time lighting, G long-time lighting, G short-time lighting, B long-time lighting, and B short-time lighting are performed. It is set to be longer than the lighting time described in the form.

  Along with this, the CCD drive signal (shown in FIG. 8 shows one vertical transfer pulse) also switches the timing so that the transfer can be performed at the optimum timing for the exposure time described above, and the R driving is performed for a long time. Long time exposure (ie R long time exposure), Short time exposure under R short time lighting (ie R short time exposure), Long time exposure under G long time lighting (ie G long time) Exposure) and short exposure under G short lighting (that is, G short exposure).

  As a result, the far point focal point can be observed with the optimum brightness even in the observation state described above. The present embodiment has substantially the same effect as the second embodiment.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 9 shows a timing chart for explaining the operation in the fourth embodiment.
The observation image stops very brightly at the near point, the far point is normal brightness, but when the brightness is adjusted to the near point, the far point becomes dark, so the part you want to observe is near point, and It became a problem in use in the observation image which is a far point.

  Therefore, this time, it is an object to obtain an optimum observation image by performing dynamic range expansion so as to shorten the exposure time of each of two or more different exposure times. In the fourth embodiment, the signal processing circuit 8 shown in FIG. 5 is used as in the second embodiment. Then, by switching the drive changeover switch 29, the timing generator 41 is switched from the lighting and exposure time in the standard mode, and the LEDs 26a, 26b, and 26c are turned on as shown in FIG. 9, and the CCD driving and signal processing corresponding thereto are performed. I do.

  As shown in FIG. 9, two or more different lighting times, for example, R long lighting for 1/120 seconds, R short lighting for 1/240 seconds, G long lighting for 1/120 seconds, 1/240 seconds Each of the lighting times is shorter than the lighting time shown in the second embodiment, such as the G short-time lighting, the 1/120 second B long-time lighting, and the 1/240 second B short-time lighting ( In FIG. 9, for example, R long lighting for 1/120 seconds is simply abbreviated as R, and R short lighting for 1/240 seconds is simply abbreviated as R).

  Corresponding to this, CCD drive is performed, long exposure under R long lighting for 1/120 seconds, short exposure under R short lighting for 1/240 seconds, 1/120 seconds. Long exposure under G long lighting, short exposure under 1/240 second G short lighting, long exposure under 1/120 second B long lighting, A CCD drive signal is applied to and read out from the CCD 18 that has been exposed for a short time under B short-time lighting of 1/240 seconds (in FIG. 9, for example, long exposure of 1/120 seconds is simply referred to as L exposure). , 1/240 second short exposure is abbreviated as S exposure).

  Then, the signal processing circuit 8 shown in FIG. 5 performs signal processing to convert the signal into a signal having a wide dynamic range, and displays it on the color monitor 10 as an image that can be easily observed at both far and near points even in a moving situation.

  In the present embodiment, each lighting time of each color is made shorter than the lighting time shown in the second embodiment, so that the lighting time and the exposure time (imaging) in the dynamic range expansion of a fast-moving subject or the like. Since the time) is short, an image with little color misregistration can be obtained, so that an easily observable image can be obtained.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 10 shows a timing chart for explaining the operation in the fifth embodiment.
For example, in the dynamic range expansion mode shown in the second embodiment, for example, R long exposure, R short exposure, and the like are performed. When this R long exposure and R short exposure are combined by converting the time axis, Since images with time differences are synthesized, in the case of a subject in motion, image blurring occurs and the image becomes very difficult to see.

  In order to solve this, the exposure time interval of each of the R long exposure and the R short exposure is shown in the uppermost part of the timing chart of FIG. As shown in the CCD exposure timing in the embodiment, it is shortened.

  For example, by bringing the R short-time exposure closer to the R long-exposure side immediately before it, it is possible to minimize the occurrence of image blurring in the combined image when exposed by long-time exposure and short-time exposure. be able to. Others have the same configuration, operation, and effects as those of the second embodiment.

Next, a modification of the fifth embodiment will be described with reference to FIG. FIG. 11 is a timing chart for explaining the operation in this modification.
In the embodiments so far, when the LEDs 26a, 26b, and 26c are sequentially turned on, a light-off period is provided between the light-on periods. In the light-off period, a drive signal is applied to the CCD 18 and exposure is performed immediately before the light-off period. In this modification, the LED 26b is turned on when the LED 26a has been turned on, and the LED 26c is turned on when the LED 26b is turned off. It is made to turn on one by one in order to make it.

  Further, in this modified example, signals picked up at two different lighting times as in the second embodiment are obtained, and the dynamic range is obtained by the signal processing circuit 8 including the gradation conversion circuit 44 shown in FIG. I am trying to expand.

  For this reason, as shown in FIG. 11, for example, a transfer signal is applied to the CCD 18 at a long lighting timing longer than half of the R lighting time to transfer the signal charge of the photosensitive portion to the vertical transfer portion, and then the vertical transfer pulse. In addition, a long-time R exposure signal imaged (exposed) under long-time lighting is read until the R lighting time ends after the horizontal transfer pulse is applied.

  Further, a short-time R exposure signal imaged under a short R lighting time after being transferred by applying a transfer signal is transferred from the photosensitive portion to the vertical transfer portion by a transfer signal at the end of the R lighting time. (And at the same time, the next G lighting starts), the short-time R exposure signal transferred to this vertical transfer unit is applied to the subsequent vertical transfer pulse and horizontal transfer pulse to apply the CCD 18 during the next long G lighting period. Read from.

  The long-time R exposure signal and the short-time R exposure signal are subjected to processing for expanding the dynamic range by the gradation calculation circuit 44 and are temporarily stored in the memory (1) 35a.

  The same processing is performed also in the case of G lighting and B lighting, and is temporarily stored in the memory (2) 35b and the memory (3) 35c. Thereafter, the image is read out simultaneously, and a color image with an expanded dynamic range is displayed on the color monitor 10.

  According to this modification, the time difference between the long-time exposure and the short-time exposure can be further reduced, so that an image with good image quality with little color misregistration or the like can be obtained.

  In this modification, the CCD 18 is assumed to be an interline transfer type CCD having a photosensitive portion for photoelectric conversion and a vertical transfer portion to which a signal of the photosensitive portion is transferred. In addition to this, even if a frame transfer unit is provided, an extinguishing period shorter than the time required for transfer from the photosensitive unit to the frame transfer unit (storage unit) may be provided.

  As an effect of the above-described embodiment, in the conventional frame sequential method, since the RGB rotary filter is rotated at a constant frequency, the exposure time cannot be arbitrarily switched according to the observation image. According to the present invention, the exposure time can be arbitrarily set by changing the drive timing of the image sensor, the light emission timing of the light emitting means, and the synchronization timing, and by setting an appropriate exposure time according to the use environment. An optimum observation image can be obtained.

In addition, it is not limited to the lighting time mentioned above, You may make it light by the lighting time of a different value.
In the above description, the dynamic range is expanded by combining signals of two different imaging times under the illumination light of each color. However, the signals obtained at three or more imaging times are combined. For example, the dynamic range may be expanded. Note that embodiments and the like configured by partially combining the above-described embodiments and the like also belong to the present invention.

[Appendix]
1. In an endoscope apparatus that performs color imaging in a frame sequential method by imaging a subject that is sequentially illuminated with light in a plurality of wavelength ranges,
A light emitting means for sequentially emitting light in a plurality of wavelength regions by pulse lighting;
Imaging means for capturing a subject image illuminated by the pulse lighting of the light emitting means;
Driving means for outputting a signal imaged by the imaging means;
Video signal processing means for performing signal processing for generating a video signal with respect to an output signal of the imaging means;
A control unit that performs lighting control for pulse-lighting the light-emitting unit, and performs control of drive signal timing control for the imaging unit and signal processing of the video signal processing unit according to the time the pulse is lit.
An endoscope apparatus characterized by comprising:

2. In Supplementary Note 1, the light-emitting means has three light-emitting elements that emit light sequentially in the red, green, and blue wavelength regions by pulse lighting.
3. In Supplementary Note 1, the light emitting means sequentially emits light in the red, green, and blue wavelength regions by pulse lighting with a light extinction period interposed therebetween.
4). In Supplementary Note 1, the light emitting means sequentially emits light in the red, green, and blue wavelength regions by pulse lighting with almost no intervening period.

5. In Supplementary Note 3, the drive means outputs a drive signal for reading a signal imaged immediately before the extinguishing period during the extinguishing period.
6). In Supplementary Note 4, the driving means outputs a driving signal for reading a signal picked up when the pulse is lit immediately before the lighting period in the lighting period where the pulse is lit. 7). In Supplementary Note 1, the driving means outputs a driving signal for reading out signals imaged at a plurality of different imaging times when the issuing means performs pulse lighting in each wavelength region.
8). In Supplementary Note 7, the video signal processing means performs signal processing for expanding a dynamic range on the signals imaged at the plurality of different imaging times.

9. Light emitting means capable of pulse lighting;
Imaging means for capturing a subject image illuminated by the pulse lighting of the light emitting means;
Video signal processing means for processing an output signal of the imaging means;
And a control means for generating a lighting control signal for pulse-lighting the light-emitting means and outputting a drive signal for the imaging means and a control signal for the video signal processing means in response to the pulse lighting. Endoscopic device.

10. In a frame-sequential electronic endoscope device using a pulsed light source device, the CCD exposure timing, the light source emission timing, and the timing to synchronize the video signal obtained in line sequence can be synchronized at any timing. An electronic endoscope apparatus having a controllable timing control circuit.

11.2 In dynamic range expansion in which an image captured at two or more different exposure times is combined with a certain composite function, each of the two or more different exposure times can be varied to an arbitrary length. An electronic endoscope apparatus comprising: a timing control circuit for controlling the exposure timing of a CCD, the emission timing of a light source, and the timing of synchronizing video signals obtained in a line sequential manner.

The block diagram which shows the structure of the signal processing system etc. of the endoscope apparatus of the 1st Embodiment of this invention. The timing chart figure which shows the operation | movement in a normal use state. The timing chart figure which shows the operation | movement in the state set to short exposure time. The timing chart figure which shows the operation | movement in the state set to the long exposure time. The block diagram which shows the structure of the signal processing system etc. in the 2nd Embodiment of this invention. The timing chart figure which shows the operation | movement in 2nd Embodiment. Explanatory drawing of operation | movement of dynamic range expansion by a gradation arithmetic circuit. The timing chart figure which shows the operation | movement in the 3rd Embodiment of this invention. The timing chart figure which shows the operation | movement in the 4th Embodiment of this invention. The timing chart figure which shows the operation | movement in the 5th Embodiment of this invention. The timing chart figure which shows the operation | movement in the modification of 5th Embodiment. 1 is an overall configuration diagram of a conventional electronic endoscope apparatus. The block diagram which shows the internal structure of the video processor of FIG. The figure which shows the rotation filter in a prior art example. Operation | movement explanatory drawing of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope apparatus 2 ... Electronic endoscope 3 ... Insertion part 7 ... Pulse lighting device 8 ... Signal processing circuit 9 ... Video processor 17 ... Objective lens 18 ... CCD
26a, 26b, 26c ... LED
27a, 27b, 27c ... Signal line 28 ... LED driver 29 ... Drive changeover switch 30 ... Driver 34 ... Select circuit 35a, 35b, 35c ... Memory 36 ... Color correction circuit 41 ... Timing generator 42 ... Memory controller Agent Patent attorney Susumu Ito

Claims (10)

A plurality of light emitting means for sequentially emitting illumination light;
In an endoscope comprising: an imaging unit that images an object sequentially illuminated by the illumination light and generates an imaging signal;
The endoscope in which any one of the other light emitting means is turned on at the timing when the lighting of any one of the plurality of light emitting means is completed. A transfer signal for transferring the imaging signal generated by the imaging unit to the transfer unit of the imaging unit and a transfer pulse for reading the imaging signal transferred to the transfer unit from the imaging unit to the imaging unit With a driver to apply,
The driver applies the transfer signal to the imaging unit at a timing when any one of the plurality of light emitting units is turned off, and within a period in which any one of the other light emitting units is turned off. The endoscope according to claim 1, wherein the transfer pulse is applied to the imaging unit.   3. The driver according to claim 2, wherein the driver applies the transfer signal and the transfer pulse to the imaging unit within a period in which any one of the plurality of light emitting units is turned on. Endoscope.   A time from when any one of the plurality of light-emitting means starts lighting until a time when any one of the plurality of light-emitting means is turned on, and the period 4. The endoscope according to claim 3, wherein the time from when the transfer signal is applied to when lighting of any one of the plurality of light emitting unit farms ends is different.   The endoscope according to any one of claims 1 to 3, wherein the plurality of light emitting units respectively emit light having different wavelength ranges.   The endoscope according to claim 5, wherein the plurality of light emitting means are first, second, and third light emitting means that emit light in a wavelength region of red, blue, and green.   The endoscope according to any one of claims 1 to 6, wherein the light emitting means is provided at a distal end portion of the endoscope.   The endoscope according to claim 1, wherein the light emitting unit is an LED.   A timing generator for controlling the timing of lighting and lighting end of the plurality of light emitting means and the timing of driving the imaging means and applying a processing signal; and sending an instruction signal to the timing generator to turn on the light emitting means An endoscope according to any one of claims 2 to 8, further comprising a drive changeover switch that varies a timing at which lighting ends and a timing at which the imaging unit is driven and a processing signal is applied. .   At a standard timing when the drive changeover switch is not operated, the plurality of light emitting means emit light at a period of 1/60 seconds, and the drive changeover switch is set to a shorter emission time and a longer emission time as compared with the standard timing. The endoscope according to claim 9, wherein the timing generator is controllable so that switching can be selected.

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