JP2012081001A - Endoscope apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a distal part of a scope and an observation region from being affected by heat when adjusting brightness with a rotary shutter.SOLUTION: The brightness of an object image is adjusted by controlling rotation of the rotary shutter. Usually, the amount of light is adjusted by shielding the light intermittently while rotating the shutter with a cycle of one frame period. When the amount of light is estimated to reach a limit that affects the distal part of the scope and the observation region by heat, the rotation speed of the rotary shutter is slowed down to make the cycle longer, and thus to set the shielding period longer than the one frame period.

Description

  The present invention relates to an electronic endoscope apparatus that images a subject such as an inner wall of an organ with a scope and displays an observation image on a monitor, and particularly relates to brightness adjustment processing of the observation image.

  In the endoscope apparatus, a brightness adjustment process is performed in which the illumination light quantity to the subject is increased or decreased using a diaphragm to maintain the brightness of the subject image at an appropriate brightness. In an endoscope apparatus using a rotary shutter, a rotary shutter composed of a light shielding portion and an opening is rotated at a period of one frame period to adjust an irradiation period (see Patent Document 1).

JP 2007-195850 A

  In the case of dimming processing using a rotary shutter, light shielding and illumination are alternately switched within one frame period. Therefore, when a relatively large amount of irradiation light is required depending on the optical characteristics of the scope or the observation situation, the subject is intermittently illuminated with a large amount of irradiation light for a long period of time.

  On the other hand, there are heat sources such as an image sensor and a ride guide tip at the scope tip, and the scope tip tends to generate heat. In order to prevent noise and component failures accompanying it, the irradiation light quantity must be sufficiently suppressed.

  An endoscope apparatus according to the present invention is an endoscope apparatus that performs brightness adjustment processing using a rotary shutter, and includes a light source that illuminates a subject and one frame period or one field period (one frame / field period). ), A rotary shutter that rotates on the optical path of the light source and intermittently reduces or blocks light, and a control unit that controls the rotation of the rotary shutter.

  The rotary shutter can be configured by various mechanisms, and the phase may be controlled by one rotary shutter, or the two rotary shutters are rotated in pairs, and the relative position (phase) of one rotary shutter is set. The amount of light may be increased or decreased by adjustment. Further, it may be configured to completely shield light for a certain period, or may be configured to reduce the overall light amount.

  In the present invention, when the amount of light applied to the subject exceeds the limit light amount, the control unit adjusts the rotation of the rotary shutter so as to perform intermittent light amount reduction or light shielding at time intervals exceeding one frame period. This prolongs the light shielding or light quantity reduction period, and prevents illumination with a very large quantity of irradiated light from continuing for several frame periods.

  Various determination methods can be applied to the limit light amount. The limit light amount varies depending on the structure of the endoscope apparatus and the observation situation. When the intensity of the lamp is high, the amount of irradiation light inevitably increases. Further, as a scope characteristic, when the attenuation rate of the light guide (optical fiber bundle) provided inside is large, the brightness adjustment processing is performed so as to lengthen the irradiation time, and thus the amount of irradiation light increases.

  Regarding the observation situation, when the scope tip is close to the observation site, or when the exposure time is shortened by the electronic shutter function, the amount of irradiation light increases. Furthermore, the amount of irradiation light also increases when a spectroscopic image is generated by irradiating light of a specific narrow band wavelength for blood vessel and lesion enhancement.

  Brightness adjustment processing is performed based on the limit light amount suitable for the device and the observation situation by presetting various limit light amounts based on the characteristics of the device and the observation state and storing them in a memory or the like. Is possible. When illumination is continued for a certain period with a constant light amount, it becomes easy to estimate the limit light amount. For example, it is better to estimate that the limit light amount is exceeded when irradiation is performed for the limit number of frames continuously in the limit irradiation time in one frame period.

  As for the control of the rotary shutter when the limit light amount is reached, it is possible to periodically rotate at a constant speed by reducing the rotation speed. For example, the control means may change the rotation speed of the rotary shutter so that the rotation cycle of the rotary shutter becomes longer than one frame period. In particular, by reducing the rotational speed of the rotary shutter during the light quantity reduction or light shielding period, the light shielding or light quantity reduction period can first be lengthened.

  In the case where the limit light quantity is reached and the light shielding period and the light quantity reduction period exceed one frame period, the observation image is disturbed if the image signal of that frame period is directly used for the video. Therefore, it is preferable to reduce the frame rate so that the image signal for that period is not used. Alternatively, interpolation processing or the like may be performed based on the image signals of the previous and subsequent frames.

  The brightness adjustment apparatus for an endoscope according to the present invention includes a luminance detection unit that detects luminance indicating the brightness of a subject image, and rotates on the optical path of the light source in accordance with one frame / field period, thereby intermittently reducing the amount of light. Or, a rotary shutter that shields light is controlled to rotate based on the detected luminance, and a control unit that maintains the brightness of the subject image at an appropriate brightness is provided. When exceeding, the rotation of the rotary shutter is adjusted so as to perform intermittent light quantity reduction or light shielding at time intervals exceeding one frame period.

  The program of the present invention rotates the endoscope apparatus on the optical path of the light source in accordance with a luminance detection means for detecting the luminance indicating the brightness of the subject image and one frame / field period, and reduces the light amount intermittently. When the rotary shutter that shields light is controlled to rotate based on the detected luminance and functions as a control means for maintaining the brightness of the subject image at an appropriate brightness, when the amount of light applied to the subject exceeds the limit light amount, one frame It functions as a control means for adjusting the rotation of the rotary shutter so as to perform intermittent light quantity reduction or light shielding at time intervals exceeding the period.

  As described above, according to the present invention, when the brightness is adjusted using the rotary shutter, it is possible to prevent the influence of heat on the scope tip and the observation site.

It is a block diagram of the electronic endoscope apparatus which is this embodiment. It is a schematic plan view of a rotary shutter. It is a flowchart of the brightness adjustment process performed in an aperture control unit. FIG. 4 is a subroutine of FIG. 3 showing a control amount determination process of the rotary shutter. It is a timing chart which shows the rotation state of a rotary shutter.

  Hereinafter, the electronic endoscope apparatus according to the present embodiment will be described with reference to the drawings.

  FIG. 1 is a block diagram of an electronic endoscope apparatus according to this embodiment. FIG. 2 is a schematic plan view of the rotary shutter.

  The electronic endoscope apparatus includes a video scope 10 whose insertion portion is inserted into the body, and a processor 30, and the video scope 10 is detachably connected to the processor 30. A monitor (not shown) is connected to the processor 30.

  The processor 30 includes a light source device 32 such as a xenon lamp. Illumination light emitted from the light source device 32 is incident on the light guide 12 provided in the video scope 10 via the condenser lens 31. The light is irradiated from the distal end portion 10T of the scope toward the subject (observation target).

  The illumination light reflected by the subject passes through the objective lens 13 provided at the scope distal end portion 10T, whereby a subject image is formed on the light receiving surface of the image sensor 14 such as a CCD. In the image sensor 14, an image signal for one frame is read from the image sensor 14 at a predetermined frame time interval (for example, 1/30 second interval). The image sensor 14 is provided with a complementary color filter in which color elements composed of Cy, Ye, G, Mg or R, G, B are arranged in a mosaic pattern.

  The read image signal is digitized by the AD conversion circuit 15 and then sent to the image processing circuit 16. The image processing circuit 16 performs signal processing such as white balance processing and gamma correction processing on the image signal. As a result, R, G, and B image signals are generated and sent to the image processing circuit 33 of the processor 30.

  In the image processing circuit 33, contour enhancement processing, superimpose processing, and the like are performed on the image signal. By outputting the video signal to the monitor, the observation image is displayed on the monitor as a real-time moving image. Images and the like are temporarily stored in the SDRAM 47 and the EEPROM 48.

  The processor control unit 40 outputs a control signal to the image processing circuit 33 and the like, and controls the operation of the entire processor 30. When the scope 10 is connected, the processor control unit 40 communicates with the scope control unit 17 provided in the scope 10 and acquires data related to the scope characteristics (resolution, scope type).

  The brightness of the subject image displayed on the monitor is adjusted by a pair of rotary shutters 42 and 43. As shown in FIG. 2, the rotary shutter 42 is a shutter in which a semicircular hole is formed in a disk-like plate, and includes a light shielding part 42A and a transmission part 42B. Similarly, the rotary shutter 43 includes a light shielding portion 43A and a transmission portion 43B, and is disposed coaxially with the rotary shutter 42 so as to face each other.

  The rotary shutters 42 and 43 are rotated by a motor 46 with one frame period as a cycle. In the optical path L of the light emitted from the light source device 32, the light shielding unit 42A and the transmission unit 42B alternately pass by the rotation of the rotary shutters 42 and 43, thereby adjusting the amount of light irradiated to the subject.

  The rotary shutter 43 can rotate while shifting the phase (rotation position) relative to the rotary shutter 42. While the rotary shutters 42 and 43 rotate at a constant speed, the amount of illumination light passing through both the transmissive portion 42B and the transmissive portion 43B is changed by increasing or decreasing the phase of the rotary shutter 43.

  A diaphragm control unit 44 composed of a DSP (Digital Signal Processor) or the like outputs a drive signal to the motor 46 and controls the rotation of the rotary shutters 42 and 43. When the brightness (average luminance value, etc.) of the subject image is calculated from the luminance signal for one frame read from the image processing circuit 33, the aperture control unit 40 increases or decreases the light amount based on the comparison with the reference luminance value. Do. Specifically, the brightness is adjusted by changing the phase of the rotary shutter 43 to increase or decrease the light shielding time within one frame period.

  Further, when the amount of light applied to the subject exceeds the limit amount, the rotational speed of the rotary shutter 42 is decreased and light shielding is intermittently performed at a period exceeding one frame period. Data relating to the limit light amount is stored in a memory (not shown) provided in the processor control unit 40 and is stored in association with the connected scope.

  Hereinafter, the brightness adjustment process will be described with reference to FIGS.

  FIG. 3 is a flowchart of brightness adjustment processing executed in the aperture control unit. The brightness adjustment process is interrupted at a time interval of one frame period. FIG. 4 is a subroutine of FIG. 3 showing the control amount determination processing of the rotary shutter. FIG. 5 is a timing chart showing the rotation state of the rotary shutter.

  In step S101, it is determined whether or not brightness adjustment processing at the time of the limit light amount is being performed. When the light amount is limited, light is intermittently shielded over several frame periods as will be described later. Therefore, the luminance detection is not performed and the process proceeds to step S103.

  On the other hand, when it is not at the limit light amount, the luminance is detected every frame period. In step S102, the luminance value of the subject image is calculated based on the sequentially generated image signals for one frame. Here, an average luminance value is obtained (S103). Then, the control amount of the rotary shutters 42 and 43 is calculated based on the luminance value (S104). While the image is continuously displayed, the light amount adjustment is repeated (S105).

  With reference to FIG. 4, the setting of the control amounts of the rotary shutters 42 and 43 in step S103 will be described in detail. First, the amount of light currently irradiated to the subject within one frame period is detected (S201). This is detected based on the relative position of the rotary shutter 43.

  In step S202, it is determined whether or not the limit light amount is exceeded when the brightness adjustment by the detected light amount continues for several frame periods. The limit light amount represents the amount of light that may affect the observation site due to the illumination light on the subject. Here, the product of the limit irradiation time (irradiation light amount) per frame and the number of frames that continue the limit irradiation light amount (here, 10 frames) is determined as the limit light amount.

  That is, when the irradiation is performed with a predetermined amount or more of light for a period of one frame and when the intermittent irradiation is continuously performed with the amount of light, the total amount of light is determined as the limit light amount. The limit light amount differs depending on the type of the scope, and the limit light amount is set according to the type of the connected scope.

  If the distance to the observation site is constant without moving the scope tip, it may be considered that substantially the same amount of irradiation light is maintained. Therefore, in step S202, on the premise that intermittent irradiation is performed for a certain period of time with the same irradiation light amount, a product of the detected irradiation light amount and a preset number of frames is calculated and compared with the limit light amount. . The limit irradiation time (limit irradiation light amount) of one frame period and the period (number of continuous frames) of continuous irradiation with the light amount are stored in advance in the memory according to the type of scope.

  When the limit irradiation light amount in one frame period is not reached or the limit light amount is not exceeded, normal brightness adjustment processing is performed. That is, the phase of the rotary shutter 43 is adjusted based on the difference between the reference luminance value corresponding to the appropriate brightness and the detected luminance value. At this time, the cycle of the rotary shutters 42 and 43 follows one frame period.

  On the other hand, when it is estimated that the light amount exceeds the limit light amount, the aperture control unit 44 similarly reduces the rotation speed of the rotary shutters 42 and 43 and changes the rotation period to a period exceeding one frame period (S204). Specifically, the rotational speed is reduced at the light shielding timing so that the light shielding period is longer than the light transmission period.

  FIG. 5 is a timing chart showing the rotation cycle of the rotary shutter 42. Here, the rotational speeds of the rotary shutters 42 and 43 are reduced at the same time after entering the light shielding period so as to make one rotation in a four frame period. As a result, the light shielding state continues for three frame periods. The dimming process is continued in the cycle after the speed change.

  In the image processing circuit 33, when the limit light amount is exceeded, the frame rate is reduced and the image signal obtained in the light shielding period is not used and not output. Thereby, an observation image based on the image signal in the light transmission period is displayed.

  When the brightness adjustment process is performed at a lower rotational speed due to the limit light amount, the light amount irradiated in the irradiation period of several frame periods is detected in step S201. Then, a period in which the brightness adjustment process is repeated with the light amount is determined, and it is determined whether or not the total light amount exceeds the limit light amount. When it is determined that the limit light amount is not reached, the normal light amount control is resumed.

  As described above, according to the present embodiment, the brightness adjustment processing of the subject image is performed by the rotation control of the rotary shutters 42 and 43. Normally, light quantity adjustment is performed by intermittently blocking light while rotating with a period of one frame period. Then, when it is estimated that the limit light amount that affects the distal end of the scope and the observation site is reached, the rotation speed of the rotary shutters 42 and 43 is decreased to increase the period, and the light shielding period so as to exceed one frame period. Is determined.

  Since the light shielding period becomes longer, it is possible to prevent a state in which the amount of light is large from being continuously maintained, and to suppress the influence of heat on the scope tip and the observation site. Further, since the rotational speed of the rotary shutter is decreased at the timing when it enters the light shielding period, the light shielding period immediately exceeds one frame period, and effective brightness adjustment processing can be performed.

  The reduction in the rotational speed of the rotary shutter is not limited to a four-frame cycle as shown in FIG. Further, instead of changing the speed (changing the cycle), the light shielding period and the light transmission period may be changed while continuously changing the speed. Further, the structure of the rotary shutter may be constituted by a single rotary shutter, and the light amount may be adjusted by the exposure time by the electronic shutter and the phase control of the rotary shutter.

  The setting of the limit light quantity can be determined not only according to the scope type (fiber scope, large diameter scope, small diameter scope), but also when using a high-speed electronic shutter or according to the characteristics of image signal processing such as spectral signal processing. is there. Also, the number of continuous frames can be set according to their characteristics (10 frames, 60 frames, 3000 frames).

  When the rotary shutter speed is lowered, an observation image may be generated by performing an interpolation process on the image signal obtained in the low light quantity state based on the image signal obtained with the high light quantity before and after the image signal. Alternatively, other purposes such as pixel defect, thermal noise noise, and FPN determination may be used.

10 Videoscope 42, 43 Rotary shutter 44 Aperture control unit

Claims (7)

A light source that illuminates the subject;
A rotary shutter that rotates on the optical path of the light source in accordance with one frame / field period and intermittently reduces or blocks the light amount;
Control means for rotationally controlling the rotary shutter so as to maintain the brightness of the subject image at an appropriate brightness,
The control means adjusts the rotation of the rotary shutter so as to perform intermittent light quantity reduction or light shielding at time intervals exceeding one frame period when the light quantity applied to the subject exceeds the limit light quantity. Endoscopic device.   The endoscope apparatus according to claim 1, wherein the control unit changes a rotation speed of the rotary shutter so that a rotation cycle of the rotary shutter becomes longer than one frame period.   The endoscope apparatus according to claim 1, wherein the control unit reduces the rotation speed of the rotary shutter in the middle of a light amount reduction or light shielding period.   The endoscope apparatus according to claim 1, wherein the control unit estimates that the light amount exceeds a limit light amount when irradiation is performed for a limit number of frames or more continuously in a limit irradiation time in one frame period. Further comprising image processing means for generating an image signal based on a pixel signal read out at an interval of 1 frame / field from an image sensor provided at the distal end of the scope;
The image processing means does not use or interpolates an image signal obtained during a light amount reduction or light shielding period while adjusting the rotation of the rotary shutter. The endoscope apparatus described. Luminance detection means for detecting luminance indicating the brightness of the subject image;
The rotary shutter, which rotates on the light path of the light source in accordance with one frame / field period and intermittently reduces or blocks light, is controlled to rotate based on the detected brightness, and the brightness of the subject image is adjusted to an appropriate brightness. Control means to maintain,
Endoscope brightness that adjusts the rotation of the rotary shutter so that the control means performs intermittent light quantity reduction or light shielding at time intervals exceeding one frame period when the illumination light quantity on the subject exceeds the limit light quantity. Adjustment device. Endoscope device
Luminance detection means for detecting luminance indicating the brightness of the subject image;
The rotary shutter, which rotates on the light path of the light source in accordance with one frame / field period and intermittently reduces or blocks light, is controlled to rotate based on the detected brightness, and the brightness of the subject image is adjusted to an appropriate brightness. Function as a control means to maintain,
When the amount of light applied to the subject exceeds the limit light amount, it functions as a control means for adjusting the rotation of the rotary shutter so as to perform intermittent light amount reduction or light shielding at time intervals exceeding one frame period. program.

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