WO2015072432A1 - Capsule endoscope and capsule endoscope system - Google Patents

Abstract

Provided are a capsule endoscope and capsule endoscope system capable of acquiring images with a high level of data for intended color components using white LED as the light source for illumination inside the subject. The capsule endoscope (10) is provided with: an illumination unit (12), which has a light-emitting element for generating light comprising a first wavelength component as a result of the flow of electric current and a fluorescent material for generating light comprising a second wavelength component that differs from the first wavelength component as a result of absorbing light containing the first wavelength component and which is capable of emitting illumination light comprising the first and second wavelength components; an image pickup unit (11) for imaging inside a subject illuminated by the illumination light generated by the illumination unit (12) to acquire image data; and a control unit (13) for switching the spectral characteristics of the illumination light generated by the illumination unit (12) by changing the size of the electric current flowing to the illumination unit (12) in synchrony with the image pickup actions of the image pickup unit (11).

Description

Capsule endoscope and capsule endoscope system

The present invention relates to a capsule endoscope that is introduced into a subject and acquires image information by imaging the inside of the subject, and an image in the subject using image information acquired by the capsule endoscope. The present invention relates to a capsule endoscope system that creates

In the field of endoscopes for imaging the inside of a subject, a spectral image of each color component is acquired by irradiating the subject with light of a plurality of types of wavelength components (that is, color lights of a plurality of colors). Technology is known. As an example, there is a narrow band filter built-in electronic endoscope system (hereinafter referred to as NBI) in which the wavelength band of illumination light is narrowed using a narrow band pass filter. In NBI, each color component is separated by a surface-sequential method in which red (R), green (G), and blue (B) light beams narrowed by a narrow-band bandpass filter are sequentially irradiated to an organ or the like in a subject. Take an image.

In recent years, a technique for acquiring a spectral image of each color component has been studied even in a capsule endoscope that is swallowed into a subject and performs imaging while moving in the digestive tract (see, for example, Patent Document 1). ).

JP 2007-319442 A

Incidentally, in the subject, a wavelength component of 415 nm, which is an absorption band of hemoglobin, and a color component in the vicinity thereof (that is, a blue component) are easily absorbed. On the other hand, in a capsule endoscope, a white LED is conventionally used as a light source. For this reason, in the image data based on the reflected light of the white light irradiated in the subject, the level of the blue component data is very low and dark compared to the red component data that has relatively little absorption in the subject. Only spectral images could be obtained. However, since the blue component data well reflects the fine structure of the surface tissue in the subject, it is desired to obtain an image with a high level of blue component data.

In order to increase the level of blue component data, it is also conceivable to narrow the band of white light and sequentially irradiate the light of each color component into the subject, as in the NBI described above. However, it is difficult to provide a narrow band filter or the like in a capsule endoscope that is swallowed by a subject due to size restrictions.

The present invention has been made in view of the above, and an object of the present invention is to provide a capsule endoscope and a capsule endoscope system that can acquire an image with a high data level of a desired color component. To do.

In order to solve the above-described problems and achieve the object, a capsule endoscope according to the present invention includes a light-emitting element that generates light including a first wavelength component when a current flows, and the first wavelength. A phosphor that generates light including a second wavelength component different from the first wavelength component by absorbing light including the component, and includes illumination light including the first and second wavelength components. Illuminating means capable of emitting light, imaging means for capturing an image of a subject illuminated by illumination light generated by the illuminating means, and acquiring image data; and the illuminating means in synchronization with an imaging operation of the imaging means Control means for controlling the switching of the spectral characteristics of the illumination light generated by the illumination means by changing the magnitude of the current passed through the illumination means.

In the capsule endoscope, the control unit switches a spectral characteristic of illumination light generated by the illumination unit during a single exposure period of still image capturing.

In the capsule endoscope, the control unit is different from the first spectral characteristic after emitting light having the first spectral characteristic for a predetermined period when the imaging operation by the imaging unit is started. The light having the second spectral characteristic is emitted for a predetermined period.

In the capsule endoscope, the first spectral characteristic and the second spectral characteristic are the first wavelength component and the second wavelength component included in the illumination light generated by the illumination unit. It is characterized by different intensity ratios.

In the capsule endoscope, a center wavelength of the first wavelength component is shorter than a center wavelength of the second wavelength component, and the first spectral characteristic has a first wavelength with respect to the second wavelength component. In the second spectral characteristic, the intensity ratio of the first wavelength component to the second wavelength component is smaller than the intensity ratio in the first spectral characteristic. It is characterized by.

In the capsule endoscope, a light emission period of the light having the first spectral characteristic is longer than a light emission period of the light having the second spectral characteristic.

In the capsule endoscope, the first wavelength component is any of 400 nm to 470 nm.

A capsule endoscope system according to the present invention includes the capsule endoscope and an image processing apparatus that processes image data acquired by the capsule endoscope.

In the capsule endoscope system, the imaging unit acquires image data of each color component of red, green, and blue, and the image processing device creates a spectral image of each color component based on the image data. It is characterized by that.

In addition, the capsule endoscope according to the present invention has a light emitting element that generates light including a first wavelength component when current flows, and the first endoscope that absorbs light including the first wavelength component. A phosphor that emits light including a second wavelength component different from the wavelength component of the light source, and capable of emitting illumination light including the first and second wavelength components; and the illumination unit generates By imaging the inside of the subject illuminated by the illuminated light and acquiring image data, and by changing the magnitude of the current flowing through the illumination means in synchronization with the imaging operation of the imaging means, Control means for performing control for switching the spectral characteristics of the illumination light generated by the illumination means, and the control means provides the imaging means with a plurality of types of illumination light having different spectral characteristics at a predetermined imaging interval. Take multiple shots under A series of imaging operations performed, respectively is characterized in that it is performed repeatedly at a predetermined cycle.

In the capsule endoscope, the plurality of types of illumination light are illumination light having different intensity ratios between the first wavelength component and the second wavelength component included in the illumination light generated by the illumination unit. It is characterized by being.

In the capsule endoscope, a center wavelength of the first wavelength component is shorter than a center wavelength of the second wavelength component, and the control unit is configured to control the imaging unit with respect to the second wavelength component. The first imaging under illumination light having a first spectral characteristic in which the intensity ratio of the first wavelength component is greater than 1, and the intensity ratio of the first wavelength component to the second wavelength component is A second imaging under illumination light having a second spectral characteristic smaller than the intensity ratio in the first spectral characteristic is performed at the imaging interval.

In the capsule endoscope, an exposure time in the first imaging is longer than an exposure time in the second imaging.

In the capsule endoscope, the first wavelength component is any of 400 nm to 470 nm.

A capsule endoscope system according to the present invention includes the capsule endoscope and an image processing apparatus that processes image data acquired by the capsule endoscope.

In the capsule endoscope system, the image processing device creates a plurality of images based on the image data respectively acquired by the plurality of times of imaging, and corresponding pixels of the plurality of images A composite image is created by adding values.

In the capsule endoscope system, the image processing device creates a plurality of images based on the image data respectively acquired by the plurality of times of imaging, and includes any one of the plurality of images. A composite image is created by replacing the pixel value of the pixel saturated in step 1 with the pixel value of the corresponding pixel in another image of the plurality of images.

In the capsule endoscope system, the imaging unit acquires image data of each color component of red, green, and blue, and the image processing device is based on the image data acquired by the plurality of imaging operations, A spectral image of each of the color components is created.

According to the present invention, since the spectral characteristics of the light illuminating the inside of the subject are switched in synchronization with the imaging operation, it is possible to acquire an image having a high data level of a desired color component.

FIG. 1 is a schematic diagram showing a schematic configuration of a capsule endoscope system according to Embodiment 1 of the present invention. FIG. 2 is a block diagram corresponding to the capsule endoscope system shown in FIG. FIG. 3 is a schematic diagram showing an example of the structure of a pseudo white type white LED. FIG. 4A is a graph schematically showing spectral characteristics of the blue LED shown in FIG. FIG. 4B is a graph schematically showing spectral characteristics of fluorescence generated by the phosphor shown in FIG. FIG. 5 is a chromaticity diagram. FIG. 6 is a graph schematically showing the spectral characteristics of white light emitted from the white LED (when the drive current is increased). FIG. 7 is a graph schematically showing the spectral characteristics of white light emitted from the white LED (when the drive current is weakened). FIG. 8 is a diagram for explaining a control operation by the control unit of the capsule endoscope shown in FIG. FIG. 9A is a schematic diagram illustrating a data level (when spectral characteristics are changed) of image data output by the imaging unit for each imaging period. FIG. 9B is a schematic diagram illustrating the data level (when the spectral characteristics are constant) of the image data output by the imaging unit for each imaging period. FIG. 10 is a diagram for explaining the control operation of the control unit in the second embodiment. FIG. 11A is a schematic diagram illustrating a data level (when the drive current is increased) of image data output each time the imaging unit performs imaging once. FIG. 11B is a schematic diagram illustrating a data level (when the drive current is weakened) of image data output each time the imaging unit performs imaging once. FIG. 12 is a diagram for explaining the control operation of the control unit in the first modification.

Hereinafter, embodiments of a capsule endoscope and a capsule endoscope system according to the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments. Moreover, in description of each drawing, the same code | symbol is attached | subjected and shown to the same part.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a schematic configuration of a capsule endoscope system according to Embodiment 1 of the present invention. As shown in FIG. 1, the capsule endoscope system 1 according to the first embodiment acquires image data by being introduced into a subject 2 and imaging the subject 2, and is superimposed on a radio signal. The capsule endoscope 10 to be transmitted, the reception device 20 for receiving the radio signal transmitted from the capsule endoscope 10 via the reception antenna unit 3 attached to the subject 2, and the capsule endoscope The image processing apparatus 30 includes image processing apparatus 30 that captures image data acquired by the endoscope 10 via the receiving apparatus 20 and creates an image in the subject 2 using the image data.

FIG. 2 is a block diagram showing the capsule endoscope system 1.
The capsule endoscope 10 is a device in which various components such as an image sensor are incorporated in a capsule-shaped housing that is sized to allow the subject 2 to swallow. The capsule endoscope 10 includes an imaging unit 11 that images the inside of the subject 2, An illumination unit 12 that illuminates the inside of the sample 2, a control unit 13, a memory 14, a transmission unit 15, an antenna 16, and a power supply unit 17 are provided.

For example, the imaging unit 11 generates an imaging signal representing the inside of the subject 2 from an optical image formed on the light receiving surface and outputs it, such as a CCD or CMOS, and is disposed on the light receiving surface side of the imaging device. And an optical system such as an objective lens. The imaging device is a color sensor that outputs image data (R data, G data, B data) corresponding to each color component (wavelength component) of red (R), green (G), and blue (B).

The illumination unit 12 includes a white LED (Light Emitting Diode) that emits white light. Here, the light emitting method of the white LED is a method using a blue LED and a complementary yellow fluorescent material (hereinafter referred to as a pseudo white method), a purple (or near-ultraviolet) LED, and three types of red, green, and blue. A method using a phosphor and a method combining three types of LEDs each emitting red, green, and blue are known. In the first embodiment, a pseudo white white LED is used among these methods.

FIG. 3 is a schematic diagram for explaining a mechanism of light emission of the pseudo white type white LED. As shown in FIG. 3, the white LED includes a substrate 121, a cavity 122 disposed on the substrate 121, a blue LED 123 mounted on the substrate 121, and a fluorescent light disposed within the cavity 122 and covering the blue LED 123. A body 124 and a transparent resin 125 that seals these parts are provided. The blue LED 123 includes, for example, a gallium nitride crystal, and generates blue light having a center wavelength λ ₁ (λ ₁ is, for example, about 400 nm to 470 nm) when a current flows (see FIG. 4A). On the other hand, the phosphor 124 is obtained by mixing, for example, a YAG (yttrium, aluminum, garnet) yellow fluorescent agent with a transparent resin material such as epoxy or silicon resin, and is excited by blue light emitted from the blue LED 123. Then, yellow light (fluorescence) having a center wavelength λ ₂ (λ ₂ > λ ₁ , λ ₂ is about 520 nm to 640 nm, for example) is generated (see FIG. 4B).

When a driving current is passed through such a white LED, part of the blue light generated from the blue LED 123 is transmitted through the phosphor 124 and the rest is absorbed by the phosphor 124. The phosphor 124 is excited by the absorbed blue light and generates yellow light. As a result, the blue light transmitted through the phosphor 124 and the yellow light generated by the phosphor 124 are mixed, and white light is emitted.

FIG. 5 is a chromaticity diagram for explaining the principle of color mixing. Each coordinate on the boundary line (edge) of the chromaticity diagram indicates a pure color component, and a numerical value written on the boundary line indicates a wavelength of each color component. Each coordinate inside the boundary line indicates a color mixture. In such a chromaticity diagram, white light is mixed by mixing color components (for example, wavelengths λ ₁ and λ ₂ ) shown at both ends of a straight line (for example, a straight line L) passing through a white region W near the center at a ratio in a predetermined range. Can be generated.

6 and 7 are graphs schematically showing the spectral characteristics of white light emitted by the white LED, and FIG. 6 shows a case where the drive current of the white LED is increased compared to FIG. . Here, of the blue light emitted from the blue LED 123, there is an upper limit to the amount of light that can be absorbed by the phosphor 124. For this reason, even if the intensity of the current is changed, the intensity of the yellow light generated by the phosphor 124 does not change much. On the other hand, when the driving current is increased, the intensity of blue light generated from the blue LED 123 and transmitted without being absorbed by the phosphor 124 is increased.

Therefore, by changing the drive current of the white LED (blue LED 123), the spectral characteristics of the white light emitted by the white LED can be changed. Specifically, by increasing the drive current, as shown in FIG. 6, white light having a spectral characteristic C1 in which the emission intensity of the blue component at the center wavelength λ ₁ is stronger than that of the yellow component at the center wavelength λ ₂ is emitted. The That is, the intensity ratio of the blue component to the yellow component is greater than 1. On the other hand, by reducing the drive current, as shown in FIG. 7, the intensity ratio of the blue component to the yellow component becomes smaller than that of the spectral characteristic C1, and the emission intensity of the blue component and the yellow component is approximately the same (intensity). White light having a spectral characteristic C2 having a ratio of about 1 is emitted.

The control of the spectral characteristics by adjusting the driving current as described above conceptually corresponds to changing the chromaticity of the light emitted by the white LED on the straight line L in the chromaticity diagram shown in FIG. Therefore, by appropriately setting a range (range corresponding to the spectral characteristics C1 and C2) in which the drive current passed through the white LED is changed, it is possible to emit white light having different color mixture ratios (intensity ratios) of the respective color components. Note that when the drive current is changed, the chromaticity of the white light emitted by the white LED does not always change linearly on the chromaticity diagram, and is slightly curved according to the characteristics of the white LED. There are things to do.

In the first embodiment, is not particularly limited emission wavelength lambda ₁ of the blue LED 123, in the case of imaging the in vivo, it is preferable to use an LED that emits blue light absorption wavelength 415nm or near the hemoglobin .

Referring to FIG. 2 again, the capsule endoscope 10 incorporates a circuit board (not shown) on which an imaging drive circuit for driving the imaging unit 11 and an illumination drive circuit for driving the illumination unit 12 are formed. Yes. The imaging unit 11 and the illumination unit 12 are fixed to the circuit board in a state where the visual field is directed outward from one end of the capsule endoscope 10.

The control unit 13 controls each unit in the capsule endoscope 10 to cause the imaging unit 11 to perform an imaging operation, and performs A / D conversion and a predetermined signal on the imaging signal output from the imaging unit 11. Processing is performed to obtain digital image data. More specifically, the control unit 13 performs control to switch the light emission state of the illumination unit 12 by changing the magnitude of the drive current of the illumination unit 12 within one drive period (imaging period) of the imaging unit 11. I do. Note that the light emission state switching control is executed, for example, by switching a resistance included in the illumination driving circuit with a switch circuit and changing the magnitude of the driving current.

The memory 14 stores an execution program and a control program for the control unit 13 to execute various operations. Further, the memory 14 may temporarily store image data or the like that has been subjected to signal processing in the control unit 13.

The transmission unit 15 and the antenna 16 superimpose the image data stored in the memory 14 together with related information on a radio signal and transmit the image data to the outside. The related information includes identification information (for example, a serial number) assigned to identify the individual capsule endoscope 10.

The power supply unit 17 includes a battery made of a button battery or the like, a power supply circuit that boosts power from the battery, and a power switch that switches an on / off state of the power supply unit 17. Electric power is supplied to each part in the mold endoscope 10. The power switch is, for example, a reed switch that can be turned on and off by an external magnetic force. Before the capsule endoscope 10 is used (before the subject 2 swallows), the capsule endoscope 10 is externally connected. It can be switched on by applying a magnetic force.

Such a capsule endoscope 10 is swallowed by the subject 2 and then moves in the digestive tract of the subject 2 by a peristaltic movement of an organ or the like, while a living body part (esophagus, stomach, small intestine, large intestine, etc.) Are sequentially imaged at a predetermined cycle (for example, a cycle of 0.5 seconds). Then, the image data and related information acquired by the imaging operation are sequentially wirelessly transmitted to the receiving device 20.

The receiving device 20 includes a receiving unit 21, a signal processing unit 22, a memory 23, a data transmission / reception unit 24, a display unit 25, an operation unit 26, a control unit 27 that controls these units, and each of these units. And a power supply unit 28 for supplying power to the power supply.

The receiving unit 21 receives the image data and related information wirelessly transmitted from the capsule endoscope 10 via the receiving antenna unit 3 having a plurality (eight in FIG. 1) of receiving antennas 3a to 3h. Each of the receiving antennas 3a to 3h is realized by using, for example, a loop antenna or a dipole antenna, and is disposed at a predetermined position on the external surface of the subject 2.

The signal processing unit 22 performs predetermined signal processing on the image data received by the receiving unit 21.
The memory 23 stores the image data subjected to signal processing in the signal processing unit 22 and related information.

The data transmission / reception unit 24 is an interface that can be connected to a communication line such as USB, wired LAN, or wireless LAN. The data transmission / reception unit 24 transmits the image data and related information stored in the memory 23 to the image processing device 30 when connected to the image processing device 30 in a communicable state.

The display unit 25 displays an in-vivo image or the like based on the image data received from the capsule endoscope 10.

The operation unit 26 is an input device used when the user inputs various setting information and instruction information to the receiving device 20.

Such a receiving device 20 is discharged while passing through the digestive tract while the capsule endoscope 10 is imaging (for example, after the capsule endoscope 10 is swallowed by the subject 2). Until the subject 2 is worn and carried. During this time, the receiving device 20 further adds related information such as reception intensity information and reception time information at the receiving antennas 3a to 3h to the image data received via the receiving antenna unit 3, and the image data and the related information. Is stored in the memory 23.

After the imaging by the capsule endoscope 10 is completed, the receiving device 20 is removed from the subject 2 and set in the cradle 20a connected to the image processing device 30. As a result, the receiving device 20 is connected to the image processing device 30 in a communicable state, and transfers (downloads) the image data and the related information stored in the memory 23 to the image processing device 30.

The image processing device 30 is configured using a workstation including a display device 30a such as a CRT display or a liquid crystal display. The image processing apparatus 30 includes an input unit 31, a data transmission / reception unit 32, a storage unit 33, an image processing unit 34, an output unit 35, and a control unit 36 that controls these units in an integrated manner.

The input unit 31 is realized by an input device such as a keyboard, a mouse, a touch panel, and various switches. The input unit 31 receives input of information and commands according to user operations.

The data transmission / reception unit 32 is an interface that can be connected to a communication line such as a USB or a wired LAN or a wireless LAN, and includes a USB port and a LAN port. In the first embodiment, the data transmission / reception unit 32 is connected to the reception device 20 via the cradle 20a connected to the USB port, and transmits / receives data to / from the reception device 20.

The storage unit 33 is realized by a semiconductor memory such as a flash memory, a RAM, or a ROM, a recording medium such as an HDD, an MO, a CD-R, or a DVD-R, and a drive device that drives the recording medium. The storage unit 33 is a program for operating the image processing apparatus 30 to execute various functions, various information used during the execution of the program, and image data and related information acquired via the receiving apparatus 20 Memorize etc.

The image processing unit 34 is realized by hardware such as a CPU, and reads a predetermined program stored in the storage unit 33, thereby creating a predetermined in-vivo image corresponding to the image data stored in the storage unit 33. The image processing is performed. More specifically, the image processing unit 34 performs predetermined image processing such as demosaicing, density conversion (gamma conversion, etc.), smoothing (noise removal, etc.), sharpening (edge enhancement, etc.) on the image data. An image (spectral image) for each color component using each of R data, G data, and B data, and a color image using all image data are created. The image processing unit 34 also executes processing for creating a composite image using the created spectral image and color image.

The output unit 35 outputs various images created by the image processing unit 34 and other information to an external device such as the display device 30a for display.

The control unit 36 is realized by hardware such as a CPU, and reads various programs stored in the storage unit 33 to thereby input a signal input via the input unit 31 or image data input from the data transmission / reception unit 32. Based on the above, instructions to each unit constituting the image processing apparatus 30 and data transfer are performed, and the overall operation of the image processing apparatus 30 is comprehensively controlled.

Next, the operation of the capsule endoscope system 1 will be described. FIG. 8 is a diagram for explaining a control operation by the control unit 13 of the capsule endoscope 10.

When the power supply unit 17 of the capsule endoscope 10 is switched to the on state, the control unit 13 causes the imaging unit 11 to perform an imaging operation at a preset imaging cycle (T ₁ + T ₂ ). Further, in synchronization with this imaging operation, the control unit 13 causes the illumination unit 12 to emit light with two different types of spectral characteristics by changing the drive current during the imaging period T ₁ . That is, by driving the illumination unit 12 with the drive current I ₁ after the start of the imaging period T ₁ , light having a spectral characteristic C 1 (see FIG. 6) having a strong blue component with respect to the yellow component (hereinafter also referred to as illumination light). Thus, the subject 2 is illuminated for a predetermined light emission period t ₁ (first light emission state).

Subsequently, the control unit 13 drives the illumination unit 12 with the drive current I ₂ (I ₂ <I ₁ ) after the light emission period t ₁ has elapsed, so that the spectral characteristics of the yellow component and the blue component having the same intensity are obtained. The inside of the subject 2 is illuminated with a light having C2 (see FIG. 7) (same as above) for a predetermined light emission period t ₂ (t ₁ + t ₂ = T ₁ ) (second light emission state).

Accordingly, during the light emission period t ₁ , each pixel of the image sensor included in the imaging unit 11 receives the reflected light from the subject 2 of the illumination light having the spectral characteristics C 1, and red (R) and green (G). , Image information (charge) of each color component of blue (B) is accumulated. Further, during the subsequent light emission period t ₂ , each pixel of the image sensor receives the reflected light from the subject 2 of the illumination light having the spectral characteristic C 2 and similarly accumulates the imaging information. The imaging unit 11 reads the stored imaging information for each imaging period T ₁ and outputs image data (R data, G data, B data) corresponding to each color component. The output image data is stored in the memory 14.

9A and 9B are schematic diagrams illustrating data levels of image data output by the imaging unit 11 for each imaging period T ₁ . Of these, FIG. 9A shows a case where the spectral characteristics obtained by changing the spectral characteristic C2 from the spectral characteristics C1 during the imaging period T _1. On the other hand, FIG. 9B shows, for comparison, a case where the spectral characteristics are kept constant in the imaging period T ₁ while maintaining the spectral characteristics C2.

As shown in FIG. 9B, when the spectral characteristic C2 is not changed during the imaging period T ₁ , the short wavelength side color component including the wavelength λ ₁ (hereinafter referred to as the short wavelength side component) and the wavelength λ ₂ are included. The subject 2 is illuminated with light having the same emission intensity as the color component on the long wavelength side (hereinafter referred to as the long wavelength side component). Here, as described above, the subject 2 tends to absorb the absorption wavelength of 415 nm of hemoglobin and the short wavelength side component in the vicinity thereof. For this reason, in the reflected light from the subject 2, the intensity of the short wavelength side component is greatly attenuated compared to the long wavelength side component. As a result, in the image data output from the imaging unit 11 every imaging period T _1, for R data corresponding to the long wavelength side component, the level of B data corresponding to the short wavelength side component is very low End up.

In contrast, as shown in FIG. 9A, when changing the spectral characteristic between the imaging period T _1, first, during the light emission period t _1, the emission intensity of the shorter wavelength side component is resistant to long-wavelength side component The subject 2 is illuminated with light. Therefore, even if the short wavelength side component is absorbed in the subject 2, the short wavelength side component remains sufficiently in the reflected light from the subject 2. Further, during the subsequent light emission period t _2, the subject 2 is illuminated with light having the same emission intensity of the short wavelength side component and the long wavelength side component. Therefore, in the reflected light, but rather than the light emission period t ₁ is short intensity of the long wavelength side component in the opposite becomes relatively stronger than the light emission period t _1. After all, in the entire imaging period T ₁ , the level of B data in the image data output from the imaging unit 11 can be improved as compared with the case of FIG. 9B.

Here, specific values of the drive currents I ₁ and I ₂ vary depending on the characteristics of the blue LED 123 and the phosphor 124 constituting the white LED and the level of B data to be improved in the image data. The drive current I ₁ is preferably about three times that of I ₂ . Specifically, when the driving current of a white LED normally used in a general capsule endoscope is 5 mA, the driving current I ₂ is set to about 5 mA, and the driving current I ₁ is set to about 15 mA.

Further, the specific distribution of the light emission periods t ₁ and t ₂ is not particularly limited as long as t ₁ > t ₂ , and the ratio of the drive currents I ₁ and I ₂ or the level of B data to be improved in the image data. It is good to set according to. For example, when the drive current ratio is I ₁ : I ₂ = 3: 1, the distribution of the light emission period is preferably about t ₁ : t ₂ = 3: 1. In this way, by increasing the time for strengthening the short wavelength side component that is easily attenuated, the data of each color component can be acquired at a data level ratio as shown in FIG. 9A, for example.

The image data acquired in this way is wirelessly transmitted from the transmission unit 15 and taken into the image processing device 30 via the reception device 20. The image processing unit 34 performs predetermined image processing on the captured image data, and creates a spectral image composed of each color component of red (R), green (G), and blue (B). Further, the image processing unit 34 creates a color in-vivo image composed of R, G, and B color components by adding (or weighted addition) the pixel values of corresponding pixels between these spectral images. Also good.

In the first embodiment, the color temperature of the light that irradiates the subject 2 changes as compared with the case where the drive current of the illumination unit 12 is constant. For this reason, image processing for reducing the influence of changes in color temperature, such as white balance processing, may be performed on the image data.

As described above, according to the first embodiment, since the spectral characteristics of the white LED are changed during one imaging period, the level of the B data corresponding to the wavelength component on the short wavelength side that is easily absorbed by the living body. It is possible to acquire image data that is improved compared to the prior art. Therefore, by using such image data, it is possible to create a bright (high luminance) spectral image composed of B data. Further, by synthesizing such a spectral image and a spectral image of other color components, it is possible to create a color image in which the fine structure of the surface tissue in the subject 2 appears.

In the first embodiment, two types of light having different light emission characteristics are sequentially generated during one imaging period. However, three or more types of light having different light emission characteristics may be sequentially generated. .

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
The configuration of the capsule endoscope and the capsule endoscope system according to the second embodiment is the same as that of the first embodiment, and the capsule endoscope 10 shown in FIG. The control operation of the control unit 13 is different from that of the first embodiment.

FIG. 10 is a diagram for explaining a control operation executed by the control unit 13 in the second embodiment. 11A and 11B are schematic diagrams illustrating data levels of image data output each time the imaging unit 11 performs imaging.

When the power supply unit 17 of the capsule endoscope 10 is switched to the on state, the control unit 13 performs a series of imaging operations of imaging the imaging unit 11 twice at an imaging interval T ₄ (T ₄ <T ₃ ). Is executed every period T ₃ . Although specific numerical values of the period T ₃ is not particularly limited, it may be set to the one frame in a general capsule endoscope time (e.g. 500 ms). The specific value of the imaging interval T ₄ is not particularly limited, but may be set to, for example, about 1/8 to 1/15 (for example, about 30 ms to 60 ms) of the period T ₃ .

Further, the control unit 13 synchronizes with the imaging operation described above, and performs a series of light emitting operations in which the illumination unit 12 sequentially generates light having two different types of spectral characteristics at the imaging interval T ₄ in a cycle T _3. To run. That is, in the first imaging within the period T ₃ , the control unit 13 drives the illumination unit 12 with the drive current I ₁ , so that light having the spectral characteristic C1 (see FIG. 6) is used for a predetermined light emission period t _3. The inside of the subject 2 is illuminated. Further, in the subsequent second imaging, the control unit 13 drives the illumination unit 12 with the drive current I ₂ (I ₂ <I ₁ ), so that predetermined light emission is performed with light having the spectral characteristic C2 (see FIG. 7). During the period t ₄ , the inside of the subject 2 is illuminated. In FIG. 10, t ₄ = t ₃ is set.

Thus, the imaging unit 11 receives the reflected light from the subject 2 with light having a shorter short wavelength side component than the long wavelength side component in the first imaging within the period T ₃ . Therefore, in the reflected light, despite the absorption in the subject 2, the absorption wavelength of hemoglobin and the intensity of the short wavelength side component in the vicinity thereof remain sufficiently. Therefore, in the image data output from the imaging unit 11, the data level of B data is relatively higher than that of R data, as shown in FIG. 11A.

In addition, in the second imaging within the period T ₃ , the imaging unit 11 receives reflected light from the subject 2 with light having the same intensity of the short wavelength side component and the long wavelength side component. In this reflected light, the intensity of the short wavelength side component is greatly attenuated by absorption in the subject 2. Therefore, in the image data output from the imaging unit 11, as shown in FIG. 11B, the data level of the B data is very low compared to the R data.

The image data acquired in this way is wirelessly transmitted from the transmission unit 15 and taken into the image processing device 30 via the reception device 20. The transmission unit 15 may transmit image data every time imaging is performed, or may transmit image data acquired by imaging twice in one cycle T ₃ collectively.

The image processing unit 34 performs predetermined image processing on the captured image data, an image based on the image data acquired by the first imaging (spectral characteristic C1) (hereinafter referred to as a blue white image), 2 An image based on the image data acquired by the second imaging (spectral characteristic C2) (hereinafter simply referred to as a white image) is created. At this time, white balance processing or the like may be performed in order to reduce the influence of the change in color temperature in the light irradiated on the subject 2.

Subsequently, the image processing unit 34 creates a histogram of pixel values (luminance values) of pixels in the image for each of the blue white image and the white image. At this time, it is preferable to normalize the luminance values of the blue white image and the white image in consideration of the first and second imaging conditions (light emission intensity, light emission time, etc. at each time). Then, the image processing unit 34 creates a composite image by replacing the pixel value of the pixel saturated in the white image with the pixel value of the corresponding pixel in the blue white image based on each histogram.

Here, since the imaging interval T ₄ is short between the blue-based white image and the white image acquired by two imagings in one cycle T _3, it is considered that almost the same region in the subject 2 is captured. be able to. In addition, a blue white image captured by light with a short wavelength side component is less saturated than a white image, so even a region saturated in a white image is saturated in a blue white image. It's likely not. Therefore, by executing the above-described image processing, it is possible to obtain a composite image that is appropriately expanded in gradation and free from blurring. Further, since the blue white image well reflects the fine structure of the surface tissue in the subject 2, there is an advantage that detailed information of the pixel area where the pixel value is replaced can be obtained.

It should be noted that the pixel area where the pixel value is replaced may be appropriately selected by the user visually observing the white image displayed on the display device 30a.

In addition, the image processing unit 34 uses the B data acquired under the light having the spectral characteristic C1 and the G data and the R data acquired under the light having the spectral characteristic C2, respectively. May be created. In this case, a spectral image of a sufficiently bright blue component can be obtained based on the G data. Alternatively, a composite image may be created by adding (or weighting addition) pixel values of corresponding pixels in the blue white image and the white image. In this case, it is possible to obtain a color image in which the level of B data is improved as compared with the conventional art.

In the second embodiment, the case where the imaging is performed twice per cycle T ₃ has been described. However, the number of times of imaging per cycle T ₃ may be three or more. In this case, the spectral characteristics (that is, the drive current of the illumination unit 12) may be changed to three or more types according to the number of times of imaging.

(Modification 1)
FIG. 12 is a diagram for explaining a control operation by the control unit 13 of the capsule endoscope 10 in the first modification. In Embodiment 2 described above, two types of light having different spectral characteristics are generated when imaging is performed twice within one period T _3. However, light generated when imaging is performed twice. The light emission amount (= light intensity × light emission time) may be changed with the same spectral characteristics. For example, as shown in FIG. 12, the driving current is made constant (for example, I ₂ ) between the first and second times, and the second light emission period t _{4 is set} to be longer than the first light emission period (ie, exposure time) t _3. shorten. As a result, the amount of light that illuminates the subject 2 (in other words, the amount of reflected light from the subject 2) changes between the two imaging operations. As a result, two images having different gradations can be obtained in one cycle T ₃ . By creating pixel value histograms for these images and replacing the pixel values of the saturated pixels in one image with the pixel values of the corresponding pixels in the other image, the gradation is expanded appropriately. A composite image can be obtained.

(Modification 2)
In the first modification, when the amount of light that illuminates the subject 2 is changed between two imaging operations within one period T ₃ , the light emission period may be constant and the light intensity may be changed. good. In this case, the drive current of the illumination unit 12 may be varied within a range where the spectral characteristics of the generated light do not change significantly.

The present invention described above is not limited to Embodiments 1 and 2 and Modifications 1 and 2. Various combinations can be made by appropriately combining a plurality of components disclosed in the embodiments and modifications. Can be formed. For example, some constituent elements may be excluded from all the constituent elements shown in each embodiment or modification, or may be formed by appropriately combining the constituent elements shown in different embodiments or modifications. May be.

DESCRIPTION OF SYMBOLS 1 Capsule-type endoscope system 2 Subject 3 Reception antenna unit 3a-3h Reception antenna 10 Capsule endoscope 11 Imaging part 12 Illumination part 13 Control part 14 Memory 15 Transmission part 16 Antenna 17 Power supply part 20 Reception apparatus 20a Cradle 21 Reception unit 22 Signal processing unit 23 Memory 24 Data transmission / reception unit 25 Display unit 26 Operation unit 27 Control unit 28 Power supply unit 30 Image processing device 30a Display device 31 Input unit 32 Data transmission / reception unit 33 Storage unit 34 Image processing unit 35 Output unit 36 Control Part 121 Substrate 122 Cavity 123 Blue LED
124 phosphor 125 transparent resin

Claims (18)

A light emitting element that generates light including a first wavelength component when current flows, and a second wavelength component that is different from the first wavelength component by absorbing light including the first wavelength component An illuminating unit that emits illumination light including the first and second wavelength components;
Imaging means for capturing an image of a subject illuminated by illumination light generated by the illumination means, and acquiring image data;
Control means for performing control for switching the spectral characteristics of the illumination light generated by the illumination means by changing the magnitude of a current passed through the illumination means in synchronization with the imaging operation of the imaging means;
A capsule endoscope comprising: The capsule endoscope according to claim 1, wherein the control unit switches a spectral characteristic of illumination light generated by the illumination unit during one exposure period of still image capturing. The control unit emits light having the first spectral characteristic for a predetermined period when the imaging operation by the imaging unit is started, and then has light having a second spectral characteristic different from the first spectral characteristic. The capsule endoscope according to claim 2, wherein the capsule endoscope emits light for a predetermined period. The first spectral characteristic and the second spectral characteristic are characterized in that an intensity ratio between the first wavelength component and the second wavelength component included in illumination light generated by the illumination unit is different. The capsule endoscope according to claim 3. The center wavelength of the first wavelength component is shorter than the center wavelength of the second wavelength component,
In the first spectral characteristic, an intensity ratio of the first wavelength component to the second wavelength component is greater than 1,
The capsule according to claim 4, wherein, in the second spectral characteristic, an intensity ratio of the first wavelength component to the second wavelength component is smaller than the intensity ratio in the first spectral characteristic. Type endoscope. The capsule endoscope according to claim 5, wherein a light emission period of the light having the first spectral characteristic is longer than a light emission period of the light having the second spectral characteristic. The capsule endoscope according to any one of claims 1 to 6, wherein the first wavelength component is any of 400 nm to 470 nm. A capsule endoscope according to any one of claims 1 to 7,
An image processing device for processing image data acquired by the capsule endoscope;
A capsule endoscope system comprising: The imaging means acquires image data of each color component of red, green, and blue,
9. The capsule endoscope system according to claim 8, wherein the image processing apparatus creates a spectral image of each color component based on the image data. A light emitting element that generates light including a first wavelength component when current flows, and a second wavelength component that is different from the first wavelength component by absorbing light including the first wavelength component An illuminating unit that emits illumination light including the first and second wavelength components;
Imaging means for capturing an image of a subject illuminated by illumination light generated by the illumination means, and acquiring image data;
Control means for performing control for switching the spectral characteristics of the illumination light generated by the illumination means by changing the magnitude of a current passed through the illumination means in synchronization with the imaging operation of the imaging means;
With
The control unit causes the imaging unit to repeatedly execute a series of imaging operations for performing imaging a plurality of times under a plurality of types of illumination light having different spectral characteristics at a predetermined imaging interval at a predetermined cycle. A capsule endoscope characterized by that. The plurality of types of illumination lights are illumination lights having different intensity ratios between the first wavelength component and the second wavelength component contained in illumination light generated by the illumination means. 10. The capsule endoscope according to 10. The center wavelength of the first wavelength component is shorter than the center wavelength of the second wavelength component,
The control unit is configured to perform first imaging under illumination light having a first spectral characteristic in which an intensity ratio of the first wavelength component to the second wavelength component is greater than 1 with respect to the imaging unit. A second imaging under illumination light having a second spectral characteristic in which the intensity ratio of the first wavelength component to the second wavelength component is smaller than the intensity ratio in the first spectral characteristic. The capsule endoscope according to claim 11, wherein the capsule endoscope is executed at the imaging interval. The capsule endoscope according to claim 12, wherein an exposure time in the first imaging is longer than an exposure time in the second imaging. The capsule endoscope according to any one of claims 10 to 13, wherein the first wavelength component is any of 400 nm to 470 nm. The capsule endoscope according to any one of claims 10 to 14,
An image processing device for processing image data acquired by the capsule endoscope;
A capsule endoscope system comprising: The image processing device creates a plurality of images based on the image data respectively acquired by the plurality of times of imaging, and adds a pixel value of a corresponding pixel between the plurality of images to generate a composite image. The capsule endoscope system according to claim 15, wherein the capsule endoscope system is created. The image processing device creates a plurality of images based on the image data respectively acquired by the plurality of times of imaging, and pixel values of pixels saturated in any one of the plurality of images The capsule endoscope system according to claim 15, wherein a composite image is created by substituting a pixel value of a corresponding pixel in another image of the plurality of images. The imaging means acquires image data of each color component of red, green, and blue,
16. The capsule endoscope system according to claim 15, wherein the image processing device creates a spectral image of each color component based on image data acquired by the plurality of times of imaging.

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