JP2008104614A - Endoscope with automatic dimming function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve quick light quantity regulation and acquisition of necessary still images etc. <P>SOLUTION: A first rotary shutter 15A with an opening 15P1 and a second rotary shutter 15B with an opening 15P2 are coaxially disposed to face each other and rotated at prescribed speed. The first rotary shutter 15A is rotated with the phase advanced in the direction of rotation relative to the second rotary shutter 15B, and by varying the speed of rotation of the first rotary shutter 15A, the exposure termination timing is varied while the exposure starting timing being fixed, so that the region of the overall opening MA is changed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an endoscope apparatus having an automatic light control function. In particular, the present invention relates to an endoscope apparatus that performs automatic light control processing using a rotary shutter.

In an electronic endoscope apparatus including one or a plurality of rotary shutters, the rotary shutter is rotated for automatic light control processing, autofluorescence observation, and the like (see Patent Documents 1 to 3). In Patent Document 1, the amount of light to the subject is adjusted by rotating two rotary shutters arranged coaxially so as to face each other and changing the opening angle of the opening.
JP 2005-312936 A JP 2005-143899 A JP 2002-119464 A

  In order to quickly adjust the amount of light even with a sudden change in brightness, it is necessary to acquire an observation image at the moment when the amount of light changes, that is, an image signal as soon as possible.

  On the other hand, when obtaining a still image by a freeze operation, it is necessary to obtain a still image immediately after the freeze operation as much as possible. The operator is performing endoscopy while viewing the observation image. When the operator determines to record the observation image, it is necessary to obtain a still image as close as possible to the determination, that is, the moment when the freeze operation button is operated. There is.

  An electronic endoscope apparatus according to the present invention includes a video scope having an image sensor, a signal processing unit that generates a video signal corresponding to a subject image based on an image signal read from the image sensor, and a light source that emits illumination light. The first and second rotary shutters, which have a light shielding part for shielding the illumination light and a transmission part for allowing the illumination light to pass, and are arranged coaxially so as to face each other, and the first and second rotary shutters And a driving means for rotating each of them. The shape of the rotary shutter is arbitrary, but a rotary shutter may be formed in which the area of the transmission part does not change (the size does not change during light control). For example, the transmission part is formed in a sector shape along the circumferential direction. Further, the driving means includes, for example, a stepping motor. When recording a still image, the electronic endoscope apparatus is provided with a freeze button that is operated to execute a freeze operation, and a still image signal generation unit that generates a still image according to an operation on the freeze button.

  In the present invention, the rotation phase of the first rotary shutter is relatively shifted with respect to the rotation phase of the second rotary shutter so that the brightness of the subject image is maintained at an appropriate brightness, so that the two transmission portions There is provided a light amount control means for adjusting the light amount of the illumination light by changing the bona fide region. For example, when the rotary shutter is driven by a stepping motor, the rotation speed may be changed by changing the number of pulses. The light quantity control means shifts the rotational phase of the first rotary shutter while periodically matching the timing at which the illumination light starts to pass through the two transmission parts. For example, the light quantity control means may change the rotation speed of the first rotary shutter while maintaining the state where the phase is advanced in the rotation direction with respect to the second rotary shutter 15B. In the present invention, unlike the electronic shutter function, the end timing is changed without changing the exposure (charge accumulation) start timing. Therefore, when the brightness of the subject image changes, an image signal corresponding as much as possible to the subject when the light amount changes is obtained, and the light amount is adjusted quickly. When a freeze button or the like is operated to record a still image, a still image is generated from illumination light that reaches the subject in a period closer to the time when the freeze button is operated.

  The automatic dimming device for endoscope of the present invention can be applied to an electronic endoscope device provided with a video scope, a light source device used for a fiber scope, or the like. The automatic light control device for an endoscope has a light-shielding part that shields illumination light from a light source and a transmission part that allows illumination light to pass through, respectively, and is arranged coaxially so as to face each other. The rotary shutter, the driving means for rotating the first and second rotary shutters, and the rotation phase of the second rotary shutter so as to maintain the brightness of the displayed subject image at an appropriate brightness. A light amount control unit that adjusts the amount of illumination light by shifting the rotational phase of the first rotary shutter and changing the entire transmission region where the two transmission units overlap, and the light amount control unit includes the two transmission units. The rotation phase of the first rotary shutter is shifted while the timing at which the illumination light starts to pass is made constant periodically.

  The automatic dimming method for an endoscope of the present invention includes a first light-shielding unit that shields illumination light from a light source and a transmission unit that transmits illumination light, and is arranged coaxially so as to face each other. The rotation phase of the first rotary shutter is shifted with respect to the rotation phase of the second rotary shutter so that the brightness of the displayed subject image is maintained at an appropriate brightness by rotating the second rotary shutter. The first rotary shutter is rotated while adjusting the light amount of the illumination light by changing the entire transmission region where the two transmission parts overlap, and periodically changing the timing at which the illumination light starts to pass through the two transmission parts. Shift phase.

  According to the present invention, it is possible to realize quick light amount adjustment, acquisition of a required still image, and the like.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of an electronic endoscope apparatus according to the first embodiment.

  The electronic endoscope apparatus includes a video scope 50 having a CCD 54 and a processor 10 that processes a pixel signal read from the CCD 54 and is integrally provided with a light source unit. The video scope 50 is detachably connected to the processor 10, and a monitor 52 that displays a subject image is connected to the processor 10.

  When a lamp lighting switch (not shown) is turned on, power is supplied from the lamp control unit 11 to the lamp 12 and the lamp 12 is lit. The light emitted from the lamp 12 enters the incident end 51 </ b> A of the light guide 51 that passes through the video scope 50 via the rotary shutter 15 and the condenser lens 16. The light guide 51 is an optical fiber bundle that transmits light emitted from the lamp 12 to the distal end side of the video scope 50. Light that has passed through the light guide 51 is emitted from the emission end 51B, and is a light distribution lens ( Light is irradiated to the observation site via a not shown).

  The light reflected at the observation site reaches the CCD 54 through an objective lens (not shown), and an image of the observation site is formed on the light receiving surface of the CCD 54. In this embodiment, a single-plate simultaneous type and color difference line sequential method is applied as a color imaging method, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) are provided on the light receiving surface of the CCD. Complementary color filters (not shown) in which the color elements are arranged in a checkered pattern are arranged so as to correspond to the respective pixels on the light receiving surface. In the CCD 54, the pixel signal of the subject image corresponding to the color passing through the complementary color filter is generated by photoelectric conversion. Here, an interline transfer type CCD is applied to the CCD 54.

  For example, the NTSC system is applied as a color television system, and when a moving image is displayed on the monitor 52, field reading is performed and according to a drive signal sent from the CCD driver 59 every 1/60 second time interval. In a state where adjacent pixels are added to each other, the odd-numbered field and even-numbered field image signals are sequentially read out and sent to the amplifier circuit 55. That is, the pixel signal (charge) is read out by the color difference line sequential method.

  In the amplification circuit 55, the pixel signal is subjected to amplification processing and the like, and the amplified pixel signal is sent to the initial signal processing circuit 57. The initial signal processing circuit 57 performs predetermined processing on the image signal and sends it to the processor-side signal processing circuit 28 of the processor 10.

  The processor-side signal processing circuit 28 performs various processes such as white balance adjustment and gamma correction on the image signal sent from the initial signal processing circuit 57 to generate an analog video signal. The analog video signal is output to the monitor 52, whereby the observation image is displayed on the monitor 52 as a moving image.

  On the other hand, when a still image is displayed on the monitor 52 by pressing the freeze button 53, frame reading is performed in which pixel signals for one frame are read by the same exposure. That is, the image signal for one frame accumulated in one exposure is divided into odd-numbered pixel signals and then even-numbered lines in the pixel array of the CCD 54, and sequentially read out as one-field pixel signals. The pixel signals of odd lines and even lines for one field are sent to the initial signal processing circuit 57 and the processor side signal processing circuit 28, respectively, and are output to the monitor 52 as video signals of odd fields and video signals of even fields.

  A system control circuit 22 including a CPU controls the operation of the processor 10 and outputs a control signal to each circuit such as the lamp control unit 11 and the processor side signal processing circuit 28. In a timing control circuit (not shown) on the processor side, a clock pulse signal for adjusting the processing timing of the signal is output to each circuit in the processor 10, and a synchronization signal accompanying the video signal is a processor side signal processing circuit. 28.

  The video scope 50 is provided with a scope controller 56 that controls the video scope 50 and controls an initial signal processing circuit 57 and a timing control circuit 58. The timing control circuit 58 outputs a drive signal to the CCD driver 59 based on the control signal sent from the scope controller 56 and controls the pixel signal reading process of the CCD 54. When the video scope 50 is connected to the processor 10, data is transmitted and received between the scope controller 56 and the system control circuit 22.

  The rotary shutter 15 is composed of first and second rotary shutters 15A and 15B, and rotates according to a drive signal sent from the drive unit 23 via a motor (not shown here). When a luminance signal is sent from the processor-side signal processing circuit 28 to the system control circuit 22, a difference between the luminance value and a reference luminance value representing appropriate brightness is detected, and the rotary shutter 15 is controlled so that no luminance difference occurs. Is done. A light shielding chopper 17 is provided between the rotary shutter 15 and the condenser lens 16, and operates based on a drive signal sent from the drive circuit 24 when the freeze operation is executed.

  FIG. 2 is a perspective view of the rotary shutter 15. FIG. 3 is a plan view of the rotary shutter 15 as viewed from the light guide side. 4 is a cross-sectional view of the rotary shutter 15 taken along line IV-IV in FIG.

  The first and second rotary shutters 15A and 15B are arranged coaxially so as to face each other, and are driven by the first motor 18A and the second motor 18B, respectively. The first rotary shutter 15A faces the lamp 12 and the second rotary shutter 15B faces the light guide 12 side.

  As shown in FIGS. 3 and 4, the first and second rotary shutters 15A and 15B are respectively formed with fan-shaped openings 15P1 and 15P2 along the circumferential direction, and the openings 15A and 15B are half-circumferential. Extends the length of the minute. The portions other than the openings 15A and 15B are configured as light shielding portions 15T1 and 15T2. The first and second rotary shutters 15A and 15B are positioned so as to pass the light beam LS of the light emitted from the lamp 12 through the openings 15P1 and 15P2.

  The first and second rotary shutters 15A and 15B are rotatable in the same direction (here, the counterclockwise direction when viewed from the paper surface), and rotate at the same speed except during light amount adjustment. Light from the lamp 12 reaches the light guide 12 when the openings 15P1 and 15P2 cross the light beam LS, and is blocked when the light shielding portions 15T1 and 15T2 cross the light beam LS. Therefore, light transmission and blocking are repeated by the rotation of the first and second rotary shutters 15A and 15B.

  The first and second rotary shutters 15B are both formed in a disk shape and are arranged at close distances. The shaft 18S2 of the second motor 18B is coaxially attached to the second rotary shutter 15B. On the other hand, a cylindrical protrusion 15AT having a hole 15AP through which the shaft 18S2 passes is integrally attached to the lamp-side surface of the first rotary shutter 15A. The first rotary shutter 15A including the protrusion 15AT is slidable with respect to the rotation of the second motor 18B, and the first rotary shutter 15A and the second rotary shutter 15B rotate independently of each other. .

  The shaft 18S1 of the first motor 18A is disposed in parallel with the shaft 18S2 of the second motor 18B, and the belt 19 is wound around the shaft 18S1 and the protrusion 15AT (see FIG. 4). The belt 19 rotates as the shaft 18S1 rotates, and as a result, the first rotary shutter 15A rotates according to the movement of the belt 19.

  FIG. 5 is a diagram illustrating a timing chart of signal processing. FIG. 6 is a diagram showing the rotational phase difference of the rotary shutter. FIG. 7 is a diagram showing the amount of illumination light.

  During the moving image mode, the rotary shutter 15 rotates at a predetermined speed, and a pixel signal is generated by the amount of light obtained during a period N during which light passes through the rotary shutter 15. That is, the rotation of the rotary shutter 15 has the same exposure amount adjustment function as the electronic shutter.

  Since the openings 15P1 and 15P2 have the same size and shape, when the first and second rotary shutters 15A and 15B are rotated at the same speed and phase matching, the openings 15P1 and 15P2 have the same timing and the same period. Only traverse the light flux LS. That is, the area of the entire opening of the rotary shutter 15 when the first rotary shutter 15A and the second rotary shutter 15B are overlapped coincides with the area of the opening 15P1 or the opening 15P2.

  FIG. 6 shows the first and second rotary shutters 15A and 15B in a state in which the first rotary shutter 15A has advanced by a predetermined phase in the rotation direction. A part of the light shielding portion 15T1 of the first rotary shutter 15A overlaps with the opening 15P2 of the second rotary shutter 15B, and the area MA of the entire opening is smaller than the areas of the openings 15PT1 and PT2.

  The period N during which the illumination light can pass through the rotary shutter 15 follows the size of the area of the overall opening MA, that is, the length along the circumferential direction. Therefore, by adjusting the rotational phase difference of the first rotary shutter 15A, the amount of light to the subject is changed, and brightness adjustment is executed.

  During the brightness adjustment, the phase of the first rotary shutter 15A always matches or advances with the phase of the second rotary shutter 15B. That is, the first rotary shutter is always in a state where the phase of the first rotary shutter 15A is advanced, except when the area of the overall opening MA is maximized (matches the phase of the second rotary shutter 15B). Rotate 15A. Then, based on the difference between the detected luminance value and the reference luminance value, the rotational speed of the first rotary shutter 15A is changed to change the phase difference.

  When suppressing the brightness of the subject image, the drive unit 23 increases the rotation speed of the first motor 18A attached to the first rotary shutter 15A based on the control signal from the system control circuit 22, and the second rotary The rotational phase of the first rotary shutter 15A is advanced in the rotational direction with respect to the shutter 15B. As a result, the rotational phase difference between the first rotary shutters 15A and 15B increases (the area of the overall opening MA becomes narrow), and the amount of light to the subject decreases. On the other hand, when increasing the brightness of the subject image, the rotational speed of the first motor 18A is decreased, and the rotational phase difference between the first rotary shutter 15A and 15B is decreased.

  When the scope button 53 is pressed, as shown in FIG. 5, execution of still image signal processing is started, and a pixel signal for a still image is based on an image signal for one frame obtained by one exposure in the EVEN field. Is obtained. That is, exposure for a still image is executed, and the accumulated charges of the odd lines are transferred in the next ODD field, and the accumulated charges of the even lines are transferred in the next EVEN field. At this time, the light-shielding chopper 17 operates to shield light. Note that the time from when the scope button 53 is pressed to when the still image signal processing is started is determined by the system environment setting.

  FIG. 7 shows a change in the amount of illumination light reaching the subject. The change in the amount of light at the start of the passage of the illumination light is represented by a line LM, and the change in the amount of light at the end is represented by a line LU. The second rotary shutter 15B rotates at a constant speed. On the other hand, the first rotary shutter 15A rotates while maintaining a state in which the phase is always advanced as compared with the second rotary shutter 15B, and the phase difference corresponding to the luminance difference is set so that the brightness of the subject image is constant. To change. Accordingly, the timing at which the illumination light starts to pass through the openings 15P1 and P2, that is, the exposure start timing is periodically constant and fixed and does not change (the line LM does not change). Due to the phase shift of the rotary shutter 15, only the end timing of illumination light passage (exposure end) changes (the line LU changes).

  As described above, according to the present embodiment, the first rotary shutter 15A provided with the opening 15P1 and the second rotary shutter 15B provided with the opening 15P2 are arranged coaxially so as to face each other at a predetermined speed. Rotate with. The second rotary shutter 15B rotates at a constant speed, while the first rotary shutter 15A rotates while always maintaining a state in which the phase has advanced in the rotation direction with respect to the second rotary shutter 15B. Then, by changing the rotation speed of the first rotary shutter 15A, the exposure start timing of the illumination light is periodically fixed and fixed, and the timing at the end of exposure changes. As a result, the area of the overall opening MA changes, and the amount of light is adjusted.

  Instead of adjusting the brightness of the subject image by changing the timing of starting charge accumulation as in a conventional electronic shutter, the brightness is adjusted by changing only the end timing while keeping the start timing constant. Therefore, when the subject image changes abruptly, an image signal based on the illumination light at the time of change is obtained statically, and quick light quantity adjustment is possible. Further, a still image is obtained based on illumination light as close as possible at the moment when the freeze button 53 is operated, and a necessary still image is recorded.

  The rotary shutter may have a shape other than the shape having a fan-shaped opening. Further, the phase of the second rotary shutter 15B may be shifted relative to the first rotary shutter B. The automatic light control mechanism of this embodiment may be applied to a light source device for a fiberscope.

It is a block diagram of the electronic endoscope apparatus which is 1st Embodiment. It is a perspective view of a rotary shutter. It is the top view which looked at the rotary shutter from the light guide side. It is sectional drawing of the rotary shutter along line IV-IV of FIG. It is the figure which showed the timing chart of signal processing. It is the figure which showed the rotation phase difference of a rotary shutter. It is the figure which showed the light quantity of illumination light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Processor 12 Lamp 15 Rotary shutter 15A 1st rotary shutter 15B 2nd rotary shutter 15P1 Opening part 15P2 Opening part 15T1 Light-shielding part 15T2 Light-shielding part 18A 1st motor 18B 2nd motor 23 Drive part 50 Videoscope 54 CCD
MA Overall aperture LS Luminous flux

Claims (7)

A video scope having an image sensor;
Signal processing means for generating a video signal corresponding to a subject image based on an image signal read from the image sensor;
A light source that emits illumination light to illuminate the subject;
First and second rotary shutters each having a light shielding part for shielding illumination light and a transmission part for allowing illumination light to pass, and arranged coaxially so as to face each other;
Driving means for rotating each of the first and second rotary shutters;
The rotational phase of the first rotary shutter is relatively shifted with respect to the rotational phase of the second rotary shutter so that the brightness of the subject image is maintained at an appropriate brightness, and the two transmission parts overlap. A light amount control means for adjusting the amount of illumination light by changing the entire transmission region,
The electronic endoscope apparatus, wherein the light quantity control means shifts the rotational phase of the first rotary shutter while periodically making the timing at which illumination light starts to pass through the two transmission parts. A freeze button operated to perform the freeze operation;
The electronic endoscope apparatus according to claim 1, further comprising a still image signal generation unit configured to generate a still image in accordance with an operation on the freeze button.   The electronic endoscope apparatus according to claim 1, wherein a region of each of the transmission parts does not vary.   The electronic endoscope apparatus according to claim 1, wherein the transmission portion is formed in a sector shape along a circumferential direction.   The light amount control means changes the rotation speed of the first rotary shutter while maintaining the state where the phase is advanced in the rotation direction with respect to the second rotary shutter 15B. Electronic endoscope device. First and second rotary shutters each having a light-shielding part that shields illumination light from the light source and a transmission part that allows illumination light to pass, and are arranged coaxially so as to face each other;
Driving means for rotating each of the first and second rotary shutters;
In order to maintain the brightness of the displayed subject image at an appropriate brightness, the rotational phase of the first rotary shutter is relatively shifted with respect to the rotational phase of the second rotary shutter, and two transmissions are performed. A light amount control means for adjusting the light amount of the illumination light by changing the entire transmission region where the portions overlap,
The automatic light control for an endoscope, wherein the light amount control means shifts a rotation phase of the first rotary shutter while periodically making a timing at which illumination light starts to pass through the two transmission parts. apparatus. Each of the first and second rotary shutters having a light shielding part that shields the illumination light from the light source and a transmission part that allows the illumination light to pass through and coaxially arranged so as to face each other,
In order to maintain the brightness of the displayed subject image at an appropriate brightness, the rotational phase of the first rotary shutter is relatively shifted with respect to the rotational phase of the second rotary shutter, and two transmissions are performed. Adjust the amount of illumination light by changing the overall transmission area where the parts overlap,
An automatic dimming method for an endoscope, wherein the rotational phase of the first rotary shutter is shifted while the timing at which illumination light starts to pass through the two transmission parts is periodically constant.

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