JP2020065286A - Imaging device - Google Patents

Abstract

To lengthen irradiation time of illumination light of a specific reference color and obtain a suitable color image.SOLUTION: The imaging device include: a control unit for controlling an illumination unit capable of irradiating illumination light of a plurality of colors including one specific color and another nonspecific color; and a processing unit for generating an image by photographing by an imaging unit during a unit imaging period. The control unit controls an illumination unit so that irradiation time of the nonspecific color and a part of irradiation time of illumination light of the specific color of 1 overlap.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image pickup apparatus, an endoscope apparatus, and a control method for an image pickup apparatus, which independently pick up a plurality of color images in a time division manner and obtain a color image from the picked-up plural color images.

  Conventionally, as this type of endoscope imaging apparatus (endoscope apparatus), an endoscope main body (endoscope) having an insertion portion to be inserted into a body cavity, and a proximal side of the endoscope main body, A light source device that supplies illumination light, an imaging unit that is connected to the side of the endoscope main body and has a function of imaging, a signal processing circuit that performs signal processing for the imaging unit, and an image output from the signal processing circuit A device including a color TV monitor that displays a signal is known (see Patent Document 1). In this endoscope image pickup device, red, green, and blue illumination lights are sequentially emitted from the light source device, and the image pickup unit sequentially takes in the color images of the respective reference colors into the frame memory in synchronization with this irradiation. Then, a color image is generated from the captured color image of each reference color and displayed on the color TV monitor.

JP-A-8-36138

By the way, in an endoscope image pickup apparatus adopting such a color image pickup method (so-called time-sequential color image pickup method), as shown in FIG. 3, the illumination unit is synchronized with the image pickup unit, and during the blanking period of the image pickup unit, Illumination light of each standard color is emitted. That is, each color image is exposed in each blanking period, and each color image is scanned (read out) in the most recent scanning period.
However, in such a configuration, the blanking period becomes the irradiation time of the illumination light of each reference color, and therefore the irradiation time becomes extremely short. Therefore, there has been a problem that a light source with a high response speed (for example, an LED light source or the like) has to be used as a light source of all the reference colors. That is, the usable light source is extremely limited. Further, since the irradiation time is extremely short, there is also a problem that a specific reference color (hereinafter referred to as a specific reference color) instantaneously requires a very high emission intensity (luminance). For example, in a configuration using a HARP (High-gain Avalanche Roughing Amorphous Photoconductor) film in the imaging unit, the red light-receiving sensitivity becomes extremely low as shown in FIG. Therefore, in the irradiation of the red illumination light, a high light emission amount is required to supplement the light receiving sensitivity, but since this is covered by an extremely short irradiation period, a very high light emission intensity is instantaneously required. I will end up. When the illumination light is emitted instantaneously with a very high emission intensity from the light source, the light source may be damaged, or even if it is not reached to that extent, deterioration due to heat generation may occur. In particular, when an LED light source is used as a light source having a high response speed, damage is likely to occur due to the property that the heat radiation performance of the LED light source is lower than that of other light sources.
On the other hand, as shown in FIG. 5, in order to lengthen the irradiation time of the illumination light of the specific reference color (red in the example), the irradiation time of the illumination light of the specific reference color is set outside the blanking period (within the scanning period). It is also possible to extend to. However, in such a configuration, since the exposure time varies depending on the scanning line, unnecessary gradation occurs in the color image. Consequently, depending on the scanning row, the exposure (charge accumulation) accompanying the present illumination may be performed even after the reading, and may be carried over to the next scanning period. As a result, a color image in which the color components of the two reference colors are mixed is obtained. Moreover, even if an unnecessary color component is removed, the removal process is extremely complicated because the mixing ratio differs depending on the scanning line. As a result, there is a problem in that the color components of the respective reference colors cannot be accurately obtained and a suitable color image cannot be obtained.

  An object of the present invention is to provide an image pickup apparatus, an endoscope apparatus, and a control method of the image pickup apparatus, which can prolong the irradiation time of illumination light of a specific reference color and can obtain a suitable color image. There is.

An image pickup apparatus of the present invention includes a control unit that controls an illumination unit that can illuminate a subject with n (n ≧ 3) colors of illumination light that includes one specific reference color and a plurality of non-specific reference colors, and a unit imaging period. And a processing unit that generates a color image of a subject based on n color images corresponding to n colors captured by the imaging unit in time division, the control unit controls each non-specific reference color in a unit imaging period. The illumination unit is controlled so that the illumination time of the illumination light overlaps with the illumination time of the illumination light of the specific reference color of 1.
Another imaging apparatus according to the present invention includes a control unit for controlling an illumination unit capable of irradiating a subject with n (n ≧ 3) colors of illumination light including one specific reference color and a plurality of non-specific reference colors, and a unit. And a processing unit that generates a color image of a subject based on n color images corresponding to n colors captured by the imaging unit in a time-division manner during the imaging period, and the control unit illuminates a specific reference color during the unit imaging period. It is characterized in that the illumination unit is controlled so as to continuously irradiate the light and to irradiate the illumination light of each of the plurality of non-specific reference colors during the (n-1) blanking periods within the unit imaging period.

  In this case, it is preferable that the imaging unit includes a photoelectric conversion film that receives reflected light from the subject and an electron source unit that reads out the optical image accumulated on the photoelectric conversion film.

  In this case, it is preferable that the illumination light of the specific reference color has lower light receiving sensitivity in the image capturing unit than the plurality of non-specific reference colors.

An image capturing apparatus control method according to the present invention includes an illumination unit capable of irradiating a subject with n (n ≧ 3) colors of illumination light including one specific reference color and a plurality of non-specific reference colors, and capturing in a unit imaging period. A method for controlling an imaging apparatus, comprising: a processing unit that generates a color image of a subject based on n color images corresponding to n colors captured in a time division manner; The illumination unit is controlled so that the irradiation time of the illumination light of the reference color overlaps the irradiation time of the illumination light of the specific reference color of 1.
Another control method of an image pickup apparatus according to the present invention is an illumination unit capable of irradiating a subject with n (n ≧ 3) colors of illumination light including one specific reference color and a plurality of non-specific reference colors, and a unit imaging period. A method of controlling an image pickup apparatus, comprising: a processing unit that generates a color image of a subject based on n color images corresponding to n colors captured by the image pickup unit in a time-division manner. The illumination unit is controlled so as to continuously emit the illumination light of the color and also emit the illumination light of the plurality of non-specific reference colors during the (n-1) blanking periods in the unit imaging period. To do.

According to these configurations, the color image of only the color component of the specific reference color is captured in one scanning period, and the color component of the specific reference color and each non-specific reference color are captured in the (n-1) scanning period. A color image in which color components of colors are mixed is captured. Then, although the irradiation of the specific reference color is extended to the outside of the blanking period, the irradiation is continuously performed over the entire imaging period, so that there is no difference in the exposure time depending on the scanning line (see FIG. 6). . Further, since the color component of the specific reference color is common to all the color images, it is possible to easily remove the color component of the specific reference color from other color images by using the captured color image of the specific reference color. it can. As a result, it is possible to accurately obtain the color image (color component) of each reference color. Therefore, it is possible to obtain a suitable color image while prolonging the irradiation time of the illumination light of the specific reference color.
Therefore, the usable light source is not extremely limited, and damage to the light source can be prevented. Further, since the light emission intensity of the light source can be reduced, the life of the image pickup unit can be extended, and the maximum supply current value of the drive circuit can be reduced, which simplifies the entire device and consumes less power. It also contributes to electricity conversion. Furthermore, since the peak luminance value to the subject (for example, internal organs) can be significantly reduced, it is possible to suppress the light damage to the subject, and it is possible to use it in applications where there is concern about light damage.

  In the above-mentioned imaging device, it is preferable that the illumination light of the specific reference color emits light in a wavelength range based on the spectral sensitivity characteristic of the human retina.

  With this configuration, it is possible to obtain a color image that matches the human retina with the specific reference color.

  In this case, the illumination unit preferably has a first light source that emits illumination light of a specific reference color, and the first light source is preferably a white light source covered with a color filter.

  According to this configuration, the first light source can be made less expensive and the heat dissipation can be improved as compared with the case where the LED light source is used. In addition, the wavelength range of the illumination light can be widened. As the white light source, a phosphor light source that excites the phosphor to emit light, an incandescent light source, or the like is assumed.

  An endoscope apparatus of the present invention is characterized by including the above-mentioned image pickup apparatus and a lens barrel portion provided in the image pickup apparatus and having a lens optical system built therein.

  According to this configuration, a compact and highly accurate endoscope device can be provided by using an imaging device that can obtain a highly accurate color image with a long life and a simple configuration.

It is a schematic diagram showing the composition of the endoscope system concerning this embodiment. 6 is a time chart showing an image pickup operation by the endoscope system. It is explanatory drawing which showed the conventional color imaging system. It is a figure which showed the spectral sensitivity characteristic at the time of using a HARP film. It is explanatory drawing which showed the color imaging system of a modification. It is explanatory drawing which showed the color imaging system of this invention.

  Hereinafter, an image pickup apparatus, an endoscope apparatus, and a control method of the image pickup apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the present embodiment, an endoscope system (endoscope device) to which an image pickup device is applied is illustrated. This endoscope system is for performing color imaging of a subject such as an organ that becomes a lesion by a time-sequential imaging method. In particular, the present endoscope system realizes high-precision color imaging using a HARP film by controlling illumination and performing image processing (signal processing).

  As shown in FIG. 1, the endoscope system SY includes an endoscope main body 11 that captures an image of a subject A, and a signal processing unit (image processing unit) that processes a result of capturing the subject A by the endoscope main body 11. 12 and a monitor 13 for displaying the image-processed image pickup result in color.

  The endoscope main body 11 includes a lens barrel portion 21 that is inserted into the body, an image capturing portion 22 that is connected to the base end of the lens barrel portion 21, and that captures an image of the subject A through the lens barrel portion 21, and a lens barrel portion. An illumination unit 23 that illuminates the subject A with illumination light via 21 and illuminates the illumination light, and an illumination control unit 24 that controls the illumination unit 23. The image pickup device in the claims is configured by each unit (the signal processing unit 12, the monitor 13, the image pickup unit 22, the illumination unit 23, and the illumination control unit 24) except the lens barrel unit 21.

  The lens barrel portion 21 has a cylindrical body 31 made of a hard cylindrical member, and a lens optical system 32 built in the cylindrical body 31. The lens optical system 32 guides the illumination light from the illumination unit 23 to the subject A and guides the reflection from the subject A to the image pickup unit 22 so that the optical image of the subject A is displayed on the image pickup surface of the image sensor 51 of the image pickup unit 22. Form an image.

  The illumination unit 23 includes a red light source (first light source) 41 that emits red (R: specific reference color) illumination light, a green light source 42 that emits green (G: non-specific reference color) illumination light, and a blue light source. A blue light source 43 that emits (B: non-specific reference color) illumination light and an illumination optical system 44 that guides the illumination light from each of the light sources 41, 42, and 43 to the lens barrel portion 21 are provided. The illumination optical system 44 may have a configuration in which the illumination light of each of the light sources 41, 42, and 43 is guided coaxially by two half mirrors, or a three-pronged optical fiber of each of the light sources 41, 42, and 43. The configuration may be such that the illumination light is guided coaxially.

  The red light source 41 is composed of a white phosphor light source (fluorescent lamp) covered with a color filter. Further, as the red light source 41, one in which the red illumination light has a wavelength range based on the spectral sensitivity characteristic of the human retina is used. Specifically, the red light source 41 irradiates red with light in a wavelength range in which yellow and orange are mixed. On the other hand, the green light source 42 and the blue light source 43 are LED light sources which are light emitting diodes. Although details will be described later, during the image pickup operation, the red light source 41 continuously emits red illumination light, and the green light source 42 and the blue light source 43 pulse-emit green and blue illumination light to illuminate the subject A. .

  The image capturing section 22 includes a single image sensor 51 that captures an image of the subject A via the lens barrel section 21, and a sensor control section 52 that controls the image sensor 51.

  The image sensor 51 uses a HEED-HARP image pickup plate (monochrome image pickup plate) including a HARP film (photoelectric conversion film) 56 and a cold cathode array (electron source part) 57 of a HEED (High-Efficiency Electron Emission Device) type. . The HARP film 56 receives the reflected light from the subject A on the imaging surface and accumulates the light image as an electric charge (exposure). The cold cathode array 57 is composed of a plurality of cold cathode electron sources arranged in a matrix, and reads the optical image (image) accumulated on the HARP film 56 and outputs it to the signal processing unit 12 as an imaging signal. In the image sensor 51 using the HARP film 56 of this type, the red illumination light has extremely low light receiving sensitivity as compared with other reference colors (green and blue). In addition, it can be said that the red illumination light is more important in imaging than other reference colors for the purpose of imaging the inside of the body.

  Then, the sensor control unit 52 controls the image sensor 51, and cooperates with the illumination control unit 24 in the unit imaging period to capture three color images corresponding to the number of reference colors (three colors). The captured three color images are sequentially output to the signal processing unit 12.

  The signal processing unit 12 processes the image pickup signal (color image) from the image pickup unit 22 and outputs a component color video signal (color image). The signal processing unit 12 has a memory 61, and the memory 61 has a first memory area, a second memory area, and a third memory area for individually storing three color images. That is, the signal processing unit 12 generates a color image based on the three color images stored in each memory area.

  Here, with reference to the time chart of FIG. 2, the imaging operation by the endoscope system SY will be described. Here, each scanning period in the unit imaging period in the imaging unit 22 is referred to as a first scanning period, a second scanning period, and a third scanning period in order, and each blanking period in the unit imaging period in the imaging unit 22 is referred to as , A first blanking period, a second blanking period, and a third blanking period, respectively. The first blanking period is a blanking period immediately before the first scanning period, the second blanking period is a blanking period immediately before the second scanning period, and the third blanking period is a third blanking period. It is a blanking period immediately before the 3 scanning period.

  As shown in FIG. 2, the illumination control unit 24 controls the illumination unit 23 to continuously emit red illumination light in the unit imaging period (continuous emission), and in the second blanking period, to emit green light. Illumination light is emitted (pulse emission), and blue illumination light is emitted (pulse emission) in the third blanking period. That is, in the second blanking period, red and green illumination lights are simultaneously emitted, and in the third blanking period, red and blue illumination lights are simultaneously emitted.

  On the other hand, the image capturing unit 22 captures a red color image composed of only the red color component during the reading in the first scanning period. Further, in the reading in the second scanning period, a mixed color color image in which the red color component and the green color component are mixed is captured. Furthermore, in the reading in the third scanning period, a color image of a mixed color in which the red color component and the blue color component are mixed is captured. The captured color image is output by the image capturing unit 22 to the signal processing unit 12 as an image capturing signal each time the image is captured.

  Then, the signal processing unit 12 stores the three color images output from the imaging unit 22 in the respective memory areas of the memory 61, and the color image is generated on a frame-by-frame basis based on the three color images. To generate. Specifically, first, three color images are read from each memory area. Next, the red color image is used to remove the red color component from the mixed color image by matrix calculation, and the green color image composed only of the green color component and the blue color composed of only the blue color component. And the color image of. When the color image of each reference color is obtained, the color image of each reference color is combined to generate a color image. For example, the color image output in the section t8 to t11 is generated based on the three color images captured in the first scanning period t2 to t4, the second scanning period t5 to t7, and the third scanning period t8 to t10. To be done. The color image generated here is output to the monitor 13 as a component color video signal and sequentially displayed.

  According to the above configuration, although the irradiation of red color is extended to the outside of the blanking period, the irradiation is continued throughout the entire imaging period, so there is no difference in exposure time depending on the scanning line. (See Figure 6). Further, since the red color component is common to all color images, the red color component can be easily removed from other color images by using the captured red color image. As a result, it is possible to accurately obtain the color image (color component) of each reference color. Therefore, it is possible to obtain a suitable color image while prolonging the irradiation time of the red illumination light. Therefore, the usable red light source 41 is not extremely limited, and the red light source 41 can be prevented from being damaged. Further, since the emission intensity of the red light source 41 can be reduced, the life of the image pickup unit 22 can be extended, and the maximum supply current value of the drive circuit can be reduced, so that the entire system can be simplified. It also contributes to low power consumption. Furthermore, since the peak luminance value to the subject A can be significantly reduced, the light damage to the subject A can be suppressed, and it can be used for the application in which the light damage is concerned.

  Also, as the red illumination light, the light in the wavelength range based on the spectral sensitivity characteristics of the human retina is emitted, specifically, by irradiating the light in the wavelength range in which yellow and orange are mixed as auxiliary colors, It is possible to obtain a color image matching the retina of. In particular, in this type of endoscope system SY that images the inside of the body, red is highly important. Therefore, by adjusting the wavelength range of the red illumination light to the spectral sensitivity characteristic of the human retina, it is possible to obtain a highly accurate color image as the endoscope system SY.

  Further, by using the HARP-HEED image pickup plate as the image pickup unit 22, it is possible to provide the endoscope system SY that can obtain a highly accurate image.

  Furthermore, by using a white light source covered with a color filter as the red light source 41, the red light source 41 can be made cheaper and the heat dissipation can be improved as compared with the case where an LED light source is used. be able to. In addition, the wavelength range of the illumination light can be widened.

  Although the HEED type cold cathode array 57 is used in the image sensor 51 in the present embodiment, the SPINDT type cold cathode array 57 may be used.

  Further, in the present embodiment, the cold cathode array 57 was used to read out the optical image on the HARP film 56. However, an electron gun and a deflection mechanism (so-called deflection electron gun) are used as the electron source section, and an electron gun is used. Alternatively, the optical image on the HARP film 56 may be read out by the deflecting mechanism.

  Further, although the HARP-HEED image pickup plate is used as the image sensor 51 in the present embodiment, a CCD image sensor or a CMOS image sensor may be used as the image sensor 51. In these cases, the blue illumination light has a lower light receiving sensitivity than the other reference colors, and thus blue is set as the specific reference color. That is, in the imaging operation, blue illumination light is continuously emitted during the unit imaging period, and red and green illumination lights are emitted during the two blanking periods within the unit imaging period.

  Furthermore, in the present embodiment, the reference color having low light receiving sensitivity is used as the specific reference color, but the reference color having high importance in the use of the image pickup device or the reference color for which a light source having low responsiveness is desired to be specified is specified. It may be used as a reference color.

  Further, in the present embodiment, the configuration is such that the subject A is illuminated and imaged with the three reference colors (RGB) of the three primary colors of light. However, the subject A is illuminated with four or more reference colors, It may be configured to perform imaging.

  Furthermore, in the present embodiment, a white phosphor light source covered with a color filter is used as the light source (red light source 41) of the specific reference color, but an incandescent light source covered with a color filter may be used. As a result, an LED light source may be used as the light source.

  In the present embodiment, the illumination light of the specific reference color (red) is continuously emitted. However, if the illumination light is continuously emitted in the unit imaging period, the specific reference color (red) is used. The illumination light may be pulsed.

  Further, in the present embodiment, the illumination light is introduced into the lens barrel portion 21 from the side to illuminate the subject A. However, the light sources 41, 42, 43 are arranged around the image sensor 51, and the coaxial illumination is performed. Alternatively, the subject A may be illuminated with.

  Although the present invention is applied to the endoscope system SY of the rigid endoscope using the rigid barrel portion 21 in the present embodiment, the endoscope system SY of the flexible endoscope using the flexible barrel portion 21 is used. The present invention may be applied to.

  Further, although the present invention is applied to the endoscope system SY in the present embodiment, the present invention may be applied to an imaging device other than the endoscope. For example, the present invention may be applied to night-time and deep-sea imaging devices and microscope imaging devices.

  12: signal processing unit, 21: lens barrel unit, 22: imaging unit, 23: illumination unit, 24: illumination control unit, 32: lens optical system, 56: HARP film, 57: cold cathode array, A: subject, SY : Endoscope system

Claims (1)

A control unit that controls an illumination unit that can emit illumination light of a plurality of colors including one specific color and another non-specific color;
A processing unit that generates an image by capturing an image in the unit capturing period,
The said control part is an imaging device which controls the said illumination part so that the irradiation time of the illumination light of the said non-specific color may overlap with a part of irradiation time of the illumination light of the said 1 specific color in the said unit imaging period.

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