JP2001212073A - Fluorescent imaging instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of a filter acquiring an image signal of desired wavelength band from fluorescence, perform pinning reading and improve a S/N ratio when imaging. SOLUTION: An exciting light 13 is irradiated to an organism part 10 to be measuring from a GaN series semiconductor laser 114. Fluorescence L4 emitted from the organism part 10 transmits through an image fiber 103 and a dichroic filter 122 combining a blue band-pass filter and the whole wavelength band one, and then is received by a CCD image pickup device 125. Since each band-pass filter of the dichroic filter 122 corresponds to the upper and lower two pixels of the CCD image pickup device 125, the surface area occupied by the individual band-pass filters is enlarged, thus improving the performance of the dichroic filter 122. Further, since the fluorescence transmitted through the same band-pass filter is incident on the upper and lower two pixels of the CCD image pickup device 125, the pinning reading that is a reading of added data of plural pixel signals is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescence image pickup apparatus which divides fluorescence emitted from a part to be measured irradiated with excitation light into a desired wavelength band and images the fluorescence.

[0002]

2. Description of the Related Art Conventionally, when a living body is irradiated with excitation light in an excitation wavelength region of an in-vivo dye, the fluorescence spectrum of fluorescent light emitted from normal tissue is different from that of fluorescent light emitted from diseased tissue. It is known. FIG. 11 shows representative fluorescence spectra of fluorescence emitted from normal tissue irradiated with excitation light and fluorescence emitted from diseased tissue, measured by the inventors. It is presumed that such fluorescence is a superposition of fluorescence from various in vivo substances such as flappin, collagen, fibronectin, and porphyrin.

[0003] As described above, by utilizing the fact that the fluorescence spectra are different between the normal tissue and the diseased tissue, the fluorescence emitted from the part to be measured of the living body irradiated with the excitation light can be used for a plurality of desired wavelength bands. An apparatus has been proposed which acquires an image signal and displays a pseudo-color image reflecting the relative intensity of the image signal in each wavelength band on a monitor, thereby displaying the localization / infiltration range of the diseased tissue as a color change. . This type of device is often built into an endoscope inserted into a body cavity, a colpososcope, a surgical microscope, or the like, and is usually a part to be measured of a living body irradiated with excitation light. Is mounted with a fluorescence imaging device that divides the fluorescence emitted from the device into a desired wavelength band and captures an image.

In a conventional fluorescence imaging apparatus, for example, when selecting the entire measurement wavelength band and the blue wavelength band as desired wavelength bands, a band filter for transmitting light in the entire measurement wavelength band and a blue filter for the blue wavelength band are used. A large number of band filters that transmit light are alternately combined, and a mosaic filter in which each band filter corresponds one-to-one with a pixel of the image sensor is arranged on the front surface of the image sensor to capture a fluorescent image. Detecting signal strength.

[0005]

In recent years, image sensors have been developed, and image sensors having a high resolution have been widely used. In these image sensors, the number of pixels is significantly increased, and a clear image can be captured. However, as the number of pixels of the image sensor increases, the area of each pixel decreases. For this reason, when capturing a fluorescent image using an imaging device having a large number of pixels, it is necessary to reduce the area of each bandpass filter of the mosaic filter attached to the front surface of the imaging device. For this reason, there is a problem in that the manufacture of the mosaic filter becomes difficult, and the performance of each bandpass filter is deteriorated. In addition, there has been a problem that the accuracy of the alignment between each pixel and each bandpass filter becomes severe, and it becomes difficult to manufacture a fluorescent imaging device.

Further, the fluorescence emitted from the living tissue irradiated with the excitation light is weak, and in the above-described conventional example, the light intensity of the fluorescence transmitted through each band filter of the mosaic filter is reduced by each pixel. Detected every time. For this reason, the signal charges accumulated in each pixel are small and are easily affected by noise. In general, when the signal charge stored in each pixel is small and the S / N ratio is large,
The effect of noise can be reduced by binning reading. The binning readout is a method in which signal charges in a plurality of pixels are read out after being added. By reading out the signals after adding the signal charges, the time required for reading out is reduced, and noise mixed in with the readout of the signal charges is reduced. Can be suppressed.

[0007] Such binning readout is performed by a method of adding signal charges of a plurality of pixels arranged in a line, or by two methods.
A general method is to add and read signal charges of a group of pixels such as × 2 or 3 × 3 pixels and read them out. But,
When a mosaic filter corresponding to each pixel is attached one by one as in the above-described conventional fluorescence imaging device,
Since fluorescent light transmitted through different bandpass filters enters adjacent pixels, it is difficult to add signal charges for each wavelength band, and it is also difficult to perform binning readout.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a fluorescence imaging apparatus that captures fluorescence emitted from a part to be measured irradiated with excitation light, and improves the performance of filter means for acquiring an image signal in a desired wavelength band from the fluorescence. It is an object of the present invention to provide a fluorescence imaging device having improved and high reliability.

Another object of the present invention is to enable binning readout and reduce noise contamination. An object of the present invention is to provide a fluorescence imaging device capable of improving the S / N of a captured image.

[0010]

According to the present invention, there is provided a fluorescence imaging apparatus comprising: an excitation light irradiating means for irradiating an object to be measured with excitation light;
An imaging unit for imaging fluorescence emitted from the measurement target portion by irradiation of the excitation light, wherein the imaging unit includes an imaging element in which a large number of pixels are arranged two-dimensionally, Filter means in which a large number of at least two types of bandpass filters having a wavelength band are combined on a two-dimensional plane is provided on an imaging plane between the measured section and the image sensor, and each of the bandpass filters is It corresponds to a plurality of pixels arranged continuously in the image sensor.

[0011] The filter means may comprise a linear band-pass filter combined in a stripe pattern.

If the image pickup device is a charge transfer type image pickup device, it is preferable that the linear band-pass filter corresponds to a pixel column arranged along a charge transfer direction.

[0013] The filter means may be provided on a light receiving surface of the image sensor.

The image pickup apparatus includes a binning control means for adding and reading signal charges of a plurality of pixels of the image pickup element, and a band filter for transmitting the same wavelength band is provided as the binning control means. It is preferable to add the signal charges of the pixels.

The imaging device may be of any type as long as it captures an optical image, and may be of any type, such as a CCD imaging device or a MOS imaging device.

The filter means may be of any type as long as it transmits light in a desired wavelength band. Regardless of the method of forming the filter means, a color filter which is printed in advance or a transparent film is deposited on a surface. May be used.

Examples of the charge transfer type imaging device include a normal CCD imaging device, a back-illuminated CCD, an ICCD (Intensified CCD) capable of high-sensitivity imaging, and an ECD.
Any type of imaging device, such as a B-CCD (Electoron Bombardment CCD), that transfers and outputs electric charges may be used, and the type thereof is not limited.

[0018]

According to the fluorescence imaging apparatus of the present invention described above, at least two types of band filters having different wavelength bands are alternately combined on a two-dimensional plane. Placed on the image plane between
By making each bandpass filter correspond to a plurality of pixels of an image sensor arranged continuously, the area occupied by each bandpass filter can be increased. And the performance of each bandpass filter is improved. Further, the manufacturing cost of the filter means can be reduced. Further, the alignment accuracy between the image pickup device and the filter means is reduced, and the manufacturing cost of the fluorescent image pickup device can be reduced.

In the case where the filter means is constituted by a linear band-pass filter which is alternately combined in a stripe shape, it is not necessary to divide the band-pass filter in the line direction, and the filter means can be more easily manufactured. And the performance of each bandpass filter is further improved. Further, the manufacturing cost can be further reduced. Further, the alignment accuracy of the image pickup device and the filter means in the line direction is further reduced, and the manufacturing cost of the fluorescent image pickup device can be further reduced.

In the case where the image pickup device is a charge transfer type image pickup device, if the linear band-pass filter corresponds to a pixel row arranged along the charge transfer direction, it is easy to obtain a desired image. Signal processing can be performed, and the convenience of the fluorescence imaging device can be improved.

Further, by disposing the filter means on the light receiving surface of the image pickup means, there is no need to provide an image forming surface for disposing the filter means on the optical path where the fluorescent light enters the image pickup means. The image optical system can be simplified. Further, the distance between the filter means and the image pickup device is reduced, and the positioning of the filter means is facilitated.

The image pickup device further includes binning control means for adding and reading the signal charges of a plurality of pixels of the image pickup device, wherein the binning control means converts the signal charges of the pixels provided with a bandpass filter for transmitting the same wavelength band. In the case of adding, it is possible to perform binning readout while imaging the fluorescence emitted from the measurement target portion irradiated with the excitation light into a desired wavelength band, thereby shortening the readout time. Therefore, noise contamination can be reduced, and the S / N of a captured image can be improved.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, an endoscope apparatus according to a first specific embodiment to which the fluorescence imaging apparatus according to the present invention is applied will be described with reference to FIGS. FIG.
FIG. 1 is a schematic configuration diagram of an endoscope apparatus to which a fluorescence imaging device according to the present invention is applied. The endoscope apparatus irradiates an excitation light to a living body measurement target, and images fluorescence emitted from the measurement target. The fluorescence image is two-dimensionally acquired as a fluorescence image by a fiber, and the fluorescence image is transmitted through a two-color filter in which a blue band filter transmitting the blue wavelength band and a full wavelength band filter transmitting the entire measurement wavelength band are combined. An image is picked up by a CCD image sensor, the signal intensity in the blue wavelength band and the signal intensity in the entire measurement wavelength band are detected, and displayed on a monitor as a pseudo color image corresponding to a relative ratio of both signal intensities. Each band filter corresponds to an adjacent pixel of the CCD image sensor.

The endoscope apparatus according to the first embodiment of the present invention is an endoscope inserted into a site suspected of a lesion of a patient.
100, an illumination unit 110 including a light source that emits white light for capturing a normal image and excitation light for capturing a fluorescent image, and a fluorescence imaging unit that receives and captures fluorescence generated from a living body measurement unit due to the excitation light when displaying a fluorescent image. 120, a fluorescent image processing unit 130 for performing image processing for displaying a fluorescent image as a pseudo-color image according to a relative ratio of signal intensities in a predetermined wavelength band, and performing image processing for displaying a normal image as a color image A normal image processing unit 140, a superimposer 150 for imposing a color image of a normal image and a pseudo color image of a fluorescent image, a controller 160 connected to each part and controlling operation timing, and imposed by a superimposer 150. And a monitor 170 for displaying a normal image (a color image of a normal image) and a fluorescent image (a pseudo color image of a fluorescent image). That.

The endoscope 100 includes a light guide 101, a CCD cable 102, and an image fiber 103 which extend to the distal end. Light guide 101 and CCD
At the distal end of the cable 102, that is, at the distal end of the endoscope 100,
An illumination lens 104 and an objective lens 105 are provided. The image fiber 103 is a glass fiber, and has a condenser lens 106 at the tip. At the end of the CCD cable 102, a CCD image sensor 108 on which a mosaic filter 107 in which minute color filters are combined in a mosaic shape is connected, is connected.
A prism 109 is attached to 108.

The mosaic filter 107 is a complementary color filter composed of three color filters of yellow, magenta, and cyan, which are complementary colors of the three primary colors. Each color filter has a one-to-one correspondence with a pixel of the CCD image sensor 108. Is supported.

The light guide 101 is formed by bundling a white light light guide 101a which is a multi-component glass fiber and an excitation light light guide 101b which is a quartz glass fiber, and is integrated in a cable shape.
The excitation light guide 101b is connected to the illumination unit 110. One end of the CCD cable 102 is normally connected to the image processing unit 140, and one end of the image fiber 103 is connected to the fluorescence imaging unit 120.

The illumination unit 110 includes a white light source 111 for emitting white light L1 for normal image pickup, a white light source power supply 112 electrically connected to the white light source 111, and excitation light for fluorescent image pickup.
A GaN-based semiconductor laser 114 that emits L3 and an excitation light source power supply 115 that is electrically connected to the GaN-based semiconductor laser 114 are provided.

The fluorescent imaging unit 120 includes a lens 121 for forming a fluorescent image, a two-color filter 122 in which two kinds of bandpass filters are combined, a lens 124, and a CCD.
An image pickup device 125 and a CCD driver 126 as binning control means for driving the CCD image pickup device 125 are provided.

As shown in FIG. 2, the CCD image pickup device 125 is a frame transfer type CCD composed of an image pickup surface 21 in which n pixels and m pixels are arranged, a horizontal shift register 22 and an output circuit 23. An image sensor.

As shown in FIG. 3, the two-color filter 122 is a band-pass filter 123a for transmitting light in a blue wavelength band.
And a bandpass filter 123b that transmits light in all measurement wavelength bands.
Are alternately combined, the bandpass filter 123a transmits a wavelength band of 430 nm to 520 nm as shown in FIG. 4A, and the bandpass filter 123b has a wavelength band as shown in FIG. The wavelength band from 430 nm to 800 nm is transmitted. This two-color filter 12
Numeral 2 is arranged on the image plane formed by the lens 121, and each bandpass filter is created and positioned so as to correspond to two vertically arranged pixels of the CCD image sensor 125.

The fluorescent image processing unit 130 generates a pseudo color image signal from the fluorescent image picked up by the CCD image sensor 125, and digitizes the pseudo color image signal obtained by the signal processing circuit 131. A / D conversion circuit 13
2, a fluorescent image memory 133 for storing the digitized pseudo-color image signal, a D / A conversion circuit 134 for DA-converting the pseudo-color image signal output from the fluorescent image memory 133, and a pseudo-color image signal as a video signal. A fluorescent image encoder 135 for conversion is provided.

The normal image processing unit 140 includes a signal processing circuit 141 for creating a color image signal from the normal image picked up by the CCD image pickup device 108, and an A / A for digitizing the color image signal obtained by the signal processing circuit 141. D conversion circuit 142, a normal image memory for storing digitized color image signals
143, a D / A conversion circuit 144 for DA-converting the color image signal output from the normal image memory and a normal image encoder 145 for converting the color image signal to a video signal.

The superimposer 150 imposes the pseudo color image signal output from the fluorescent image encoder 135 and the color image signal output from the normal image encoder 145, and outputs them as display signals.

Hereinafter, the operation of the endoscope apparatus having the above configuration to which the fluorescence imaging apparatus according to the present invention is applied will be described. First, the operation of the present endoscope apparatus when displaying a normal image will be described.

During normal image display, the white light source power supply 112 is driven based on a signal from the controller 160, and the white light source 111 emits white light L1. The white light L1 is incident on the white light light guide 101a through the lens 113, is guided to the end of the endoscope, and is then emitted from the illumination lens 104 to the measured section 10. The reflected light L2 of the white light L1 is
The light is condensed by 5, reflected by the prism 109, transmitted through the mosaic filter 107, received by the CCD image pickup device 108, photoelectrically converted, and output as an electric signal.

In the signal processing circuit 141, the CCD image pickup device 10
8, correlated double sampling, clamping,
After processing such as blanking and amplification, Y / C separation for separating a luminance signal and a chrominance signal is performed, and then Y signal processing is performed to calculate a luminance signal Y1. Also, the CCD imaging device 10
8 The complementary color signal separated by the on-chip mosaic filter 107 is converted into a primary color signal (complementary color-primary color conversion). The primary color signals are converted into color difference signals R1-Y1 and B1-Y1 by NTSC color difference matrix conversion.
Is calculated.

The luminance signal Y1 and the color difference signals R1-Y, which are color image signals for each pixel, calculated by the signal processing circuit 141.
1 and B1-Y1 are input to the A / D conversion circuit 142, and after being digitized, the luminance signal Y1 is stored in the luminance signal storage area of the normal image memory 143, and the color difference signal R1
-Y1 and B1-Y1 are stored in the color difference signal storage area.

The color image signals (the luminance signal Y1, the color difference signals R1-Y1 and B1
-Y1) is a D / A conversion circuit 14 according to the display timing.
4 and converted into a predetermined video signal by a normal image encoder 145, input to a superimposer 150, and output to a monitor 170 as a video signal imposed with a pseudo color image signal of a fluorescent image described later. You.
Details of the operation of the monitor 170 will be described later.

Next, the operation when a fluorescent image is displayed will be described. Based on the signal from the controller 160,
The excitation light source power supply 115 is driven, and the GaN semiconductor laser
From 114, excitation light L3 having a wavelength of 410 nm is emitted. Excitation light L
3 is transmitted through the lens 116, is incident on the excitation light guide 101b, and is guided to the end of the endoscope.
The object 104 is irradiated from 104.

The fluorescent light L4 from the measured section 10 generated by the irradiation of the excitation light L3 is condensed by the condensing lens 106, is incident on the tip of the image fiber 103, passes through the image fiber 103, and passes through the fluorescent imaging unit. Incident at 120.

The fluorescent light L4 imaged on the two-color filter 122 by the lens 121 is transmitted through the two-color filter 122, is imaged on the CCD image pickup device 125 by the lens 124, and is received.

In the CCD image sensor 125, the fluorescent light L4 is photoelectrically converted in each pixel, accumulated as signal charges corresponding to the intensity of light, and read out by binning readout by driving the CCD driver 126 at predetermined time intervals. With reference to FIG. 5 which is a partially enlarged schematic view of the CCD image pickup device 125, the details of the operation of reading signal charges from the CCD image pickup device 125 will be described.

The fluorescent light transmitted through the bandpass filter 123a is incident on the pixel 24 disposed in the hatched portion of FIG. 5, and the fluorescent light transmitted through the bandpass filter 123b is incident on the pixel 25 disposed in the other portion. . In the CCD image sensor 125, the signal charges accumulated in each pixel are sequentially sent to the horizontal transfer CCD 26 of the horizontal shift register 22 sequentially after a certain time.

In the horizontal shift register 22, first, when the signal charge of the pixel of one horizontal line is input, it waits for the signal charge of the pixel of the next horizontal line to be input.
After being transferred to the horizontal shift register 22, the signal is transferred in the horizontal direction and output via an output circuit 23 provided at the left end. When all the signal charges of the horizontal transfer CCD 26 are output, the signal charges of the next line and the next line are transferred from the pixel. By repeating such operations,
The signal charges of the pixels on the lowermost line of the imaging surface 21 and the signal charges of the pixels on the line above the added signals are added, and are sequentially read from left to right.

For example, if the signal charges of one line and two lines are added and read, then the three lines and four
The signal charges of the lines are added, added, and read out, and sequentially moved to read out signals of all pixels and one screen.

The electric signals accumulated in the pixels of each CCD image sensor 125 are read out after the signal charges of the upper and lower two pixels are added by such binning readout. That is, the signal charges accumulated in the pixels on which the fluorescent light transmitted through the filters of the same upper and lower wavelength bands are incident are added and output to the signal processing circuit 131.

In the signal processing circuit 131, the CCD image pickup device 12
The signal strength B2 of the blue wavelength band transmitted through the blue filter 123a by performing process processing such as correlated double sampling, clamping, blanking, and amplification of the signal output from 5 and the signal intensity B2 of the entire measurement wavelength band transmitted through the full wavelength filter 124b. The signal intensity W2 is detected for each pixel pair, a color difference matrix operation is performed for each pixel pair by the NTSC method using each signal pair, and a pseudo color image signal (a pseudo luminance signal Y2, a pseudo color difference signal R
2-Y2 and B2-Y2) are calculated by a matrix operation.

The pseudo color image signals (pseudo luminance signal Y2, pseudo color difference signals R2-Y2 and B2-Y2) for each pixel calculated by the signal processing circuit 131 are input to the A / D conversion circuit 132 and digitized. After that, the pseudo luminance signal Y
2 is stored in the luminance signal storage area of the fluorescent image memory 133, and the pseudo color difference signals R2-Y2 and B2-Y2 are stored in the color difference signal storage area. The pseudo-color image signals (pseudo-luminance signal Y2, pseudo-color difference signals R2-Y2 and B2-Y2) stored in the fluorescent image memory 133 are DA-converted by the D / A conversion circuit 134 in accordance with the display timing, and the fluorescent image The video signal is converted into a predetermined video signal by an encoder 135, input to a superimposer 150, and is usually input to an image encoder 145.
The color image signal (luminance signal Y) of the normal image output from
1. Imposed with the color difference signals R1-Y1 and B1-Y1) and output to the monitor 170.

The monitor 170 converts the color image signal and the pseudo color image signal input as video signals and displays them as a normal image 30 and a fluorescent image 31. Note that the fluorescence image shows the signal intensity W2 of the entire measurement wavelength band.
Is displayed in a pseudo color in which the display color changes in accordance with the change in the relative ratio of the signal intensity B2 in the blue wavelength band, and the color is determined by the coefficient of the matrix operation formula in the image signal matrix circuit 137 described above.

It is desirable that the coefficient is set so that the difference between the display colors of the fluorescence emitted from the normal tissue and the fluorescence emitted from the diseased tissue becomes clear. For example, the fluorescence emitted from normal tissue becomes white,
By selecting a coefficient so that the fluorescence emitted from the diseased tissue becomes pink or another color and displaying it in a pseudo color, the observer can easily recognize the diseased tissue.

Accordingly, a large number of band filters 123a and 123b corresponding to the two pixels arranged vertically in the CCD image sensor 125 are alternately combined on a two-dimensional plane.
By arranging the color filter 122 on the image plane between the image fiber 103 and the CCD image pickup device 125 and picking up a fluorescent image, the area occupied by each band-pass filter becomes large. As a result, the performance of each band-pass filter is improved, and the manufacturing cost can be reduced.
Since the area of each band filter is large, a two-color filter
The alignment accuracy between 122 and CCD image sensor 125 becomes loose,
The assembly of the fluorescent imaging device is facilitated, and the manufacturing cost is reduced.

Further, by driving the CCD driver 126,
By performing the binning read, the signal charges of the upper and lower two pixels can be added and read, the read time can be reduced, and the S / N at the time of imaging can be improved.

Next, an endoscope apparatus according to a second specific embodiment to which the fluorescence imaging apparatus according to the present invention is applied will be described with reference to FIGS. FIG. 6 is a schematic configuration diagram of an endoscope apparatus to which the fluorescence imaging apparatus according to the present invention is applied, and white illumination light is decomposed into three-color sequential light through blue, red, and green rotating filters. Irradiate the part to be measured,
The reflected light is imaged by a CCD image sensor attached to the endoscope endoscope, three-color sequential signals are obtained, a color image signal is synthesized by a signal processing circuit, and displayed as a normal image color image on a monitor. In addition, the target part is irradiated with excitation light, and the fluorescent light emitted from the target part is received by a CCD image pickup device provided at the distal end of the endoscope which is also used for imaging a normal image, and a fluorescent image is obtained. To display. The above CCD
The image sensor has on-chip a stripe filter in which a line-shaped band filter that transmits the yellow wavelength band and a line-shaped band filter that transmits the entire measurement wavelength band are alternately combined. ,
It is performed in a time sharing manner.

An endoscope apparatus according to a second embodiment of the present invention is an endoscope inserted into a site suspected of a lesion of a patient.
200, an illumination unit 210 including a light source that emits three colors of sequential light L5 for capturing a normal image and excitation light L7 for capturing a fluorescent image,
A fluorescent image processing unit 220 for performing image processing for displaying a fluorescent image as a pseudo-color image, a normal image processing unit 230 for performing image processing for displaying a normal image as a color image, a CCD driver 24 for driving a CCD image sensor
It comprises a superimposer 150 for imposing 0, normal images and fluorescent images, a controller 250 for controlling the operation timing of each part, and a monitor 170 for displaying the display image imposed by the superimposer 150.

The endoscope 200 includes a light guide 201 and a CCD cable 202 extending to the distal end. An illumination lens 203 and an objective lens 204 are provided at the distal end of the light guide 201 and the CCD cable 202, that is, at the distal end of the endoscope 200. At the end of the CCD cable 202, a CCD image sensor 207 composed of a cooled back-side illuminated CCD on which a stripe filter 205 in which line-shaped band filters are alternately combined is connected, is connected to the CCD image sensor 207. , And a prism 208 are attached.

The light guide 201 is composed of a sequential light guide 201a, which is a multi-component glass fiber, and an excitation light guide 201b, which is a quartz glass fiber, which are integrated into a cable.
The excitation light guide 201b is connected to the illumination unit 210. The CCD cable 202 is composed of two output lines 202a and 202b and a drive line 202c. The output line 202a is connected to the fluorescent image processing unit 220, and the output line 202b is connected to the normal image processing unit 230.
The drive line 202c is connected to the CCD driver 240.

The CCD image pickup device 207 is an interline type CCD having an image pickup surface composed of n pixels vertically and m pixels horizontally.
FIG. 7 shows a partially enlarged schematic view of a CD image sensor. The CCD image sensor 207 includes an imaging surface 31, a horizontal shift register 32, and an output circuit 33. Each pixel 34 on the imaging surface 31 includes a photodiode 35 and a vertical transfer CCD 36.
And the horizontal shift register 32 is composed of m horizontal transfer CCDs 37. Under the control of the CCD driver 240, the signal charge stored in each pixel 34 is changed to an odd line (1 line, 3 lines, 5 lines,...) Or an even line (2 lines, 4 lines, 6 lines,...). The signal is read by an interlace operation for reading a signal.

As shown in FIG. 8, the stripe filter 205 includes a line-shaped yellow band-pass filter 206a for transmitting light in the yellow wavelength band and a line-shaped full-wavelength band filter 206b for transmitting light in all the measurement wavelength bands. Alternately combined, the yellow bandpass filter 206a is shown in FIG.
As shown in FIG. 9, the wavelength range from 520 nm to 800 nm is transmitted, and the full wavelength band filter 206b transmits the wavelength range from 430 nm to 800 nm as shown in FIG. The stripe filter 205 is such that each band filter is C
It is positioned in advance so as to correspond to the pixel row of the CD image sensor 207 in the horizontal charge transfer direction.

The illumination unit 210 includes a white light source 211 for emitting white light, a white light source power supply 212 electrically connected to the white light source 211, a rotary filter 213 for extracting three colors of light L5 sequentially from the white light, A filter driving unit 214 for driving the rotary filter 213; a GaN-based semiconductor laser 114 for emitting excitation light L7 for capturing a fluorescent image; and a power supply 115 for an excitation light source electrically connected to the GaN-based semiconductor laser 114. ing.

The fluorescent image processing unit 220 includes a signal processing circuit 221 for generating a color image signal of a normal image from the sequential signals of three colors picked up by the CCD image sensor 207, and a pseudo color image obtained by the signal processing circuit 221. Digitize signals
A / D conversion circuit 222, fluorescent image memory 223 for storing a digitized pseudo color image signal, D / A conversion circuit 224 for DA converting the pseudo color image signal output from the fluorescent image memory, and a pseudo color image signal And a fluorescent image encoder 225 for converting the image into a video signal.

The normal image processing unit 230 includes a signal processing circuit 231 for generating a color image signal from the normal image picked up by the CCD image pickup device 207, and an A / A for digitizing the color image signal obtained by the signal processing circuit 231. D conversion circuit 232, normal image memory 233 for storing digitized color image signals, D / A conversion circuit 234 for DA conversion of color image signals output from the normal image memory 233, and conversion of color image signals into signals A normal image encoder 235 is provided.

The irradiation of the light L5 and the imaging of the reflected light L6, that is, the imaging of a normal image, the irradiation of the excitation light L7 and the fluorescence
L8 imaging is performed in a time-sharing manner under the control of the controller 250. When capturing a fluorescent image, a CCD driver
Normal interlace drive is performed by 240
The output of the even-numbered line and the odd-numbered line of the image sensor 207 are alternately output via the output line 202a to the fluorescent image processing unit 220.
Is output to the signal processing circuit 221. When capturing a normal image, the image sensor 207 is driven by irregular interlace driving.
Only the outputs of the even lines are output to the signal processing circuit 231 of the normal image processing unit 230 via the output line 202b.

Hereinafter, the operation of the endoscope apparatus having the above configuration to which the fluorescence imaging apparatus according to the present invention is applied will be described. First, the operation of the present endoscope apparatus when displaying a normal image will be described.

When a normal image is picked up, the white light source power supply 212 is first driven based on a signal from the controller 250, and white light is emitted from the white light source 211. White light
A sequential light L5 that sequentially changes into three colors of blue, green, and red through a rotation filter 213 and a lens 215, which is rotationally controlled by a controller 250 via a filter driving unit 214.
After being sequentially incident on the light guide 201a and guided to the end of the endoscope, the illumination lens 104
Irradiated to The reflected light L6 of the sequential light L5 is
And is reflected by the prism 208 to be received by the photosensitive portion of the CCD image sensor 207.

In the CCD image pickup device 207, as shown in FIG. 10, the light transmitted through the yellow bandpass filter 206a is incident on the pixels on the odd lines on the image pickup surface 31, and the pixels on the even lines are irradiated on the entire wavelength band. Light transmitted through the filter 206b is incident.

In the CCD image pickup device 207, the incident light is photoelectrically converted in the photodiode 35 of each pixel 34 and stored as signal charges corresponding to the intensity of the light.
The data is read out by the drive of the CD driver 240. When capturing a normal image, the CCD is controlled by the controller 250.
The driver 240 uses an irregular interlacing
The signal is read from the image sensor 207.

First, the signal charges stored in the photodiodes 35 of the even-numbered line or the odd-numbered line are transferred to the adjacent vertical transfer CCD 36. Then vertical transfer CCD36
Transfer charge in the vertical direction in parallel. The vertically transferred signal charges are transferred to a horizontal transfer CCD of a horizontal shift register 32.
It is sequentially sent to 37.

The horizontal shift register 32 transfers a signal in the horizontal direction each time a signal charge of a pixel on one horizontal line enters, and outputs the signal via an output circuit 33 provided at the left end.
When all the signal charges of the horizontal transfer CCD 37 are output, the signal charges of the next line are transferred from the vertical transfer CCD 36. By repeating such an operation, signal charges are sequentially read from the lower left pixel of the imaging surface 21 to the right, and when a signal of one line is read, a signal charge of a line two lines above is next read. Are read out and sequentially moved to read out the signals of all the pixels on the odd or even line.

When the normal interlacing operation is performed, the reading of the signal charges stored in all the pixels of the odd-numbered lines of the CCD image pickup device 207 and the reading of the signal charges stored in all the pixels of the even-numbered lines are alternately performed. Is output to the subsequent circuit, but during normal image capturing, the CCD driver 240
, Only the signal charges accumulated in the pixels 34 of the even-numbered lines are stored in the signal processing circuit 231 of the normal image processing unit 230.
And the signal charges accumulated in the odd-numbered pixels 34 are discarded from the output circuit to the substrate or the ground.

In the signal processing circuit 231, the CCD image pickup device 20
Performs processing such as correlated double sampling, clamping, blanking, and amplification of the signal captured in step 7 from the blue component light image captured when the blue illumination light of the light L5 is sequentially irradiated. , A signal intensity B3 in the blue wavelength band is obtained for each pixel, and the signal intensity G in the green wavelength band is similarly calculated.
3 and the signal intensity R3 of the red wavelength band, and from each signal, a luminance signal Y3, which is a color image signal, and a color difference signal R3
-Y3 and B3-Y3 are calculated and output to the A / D conversion circuit 142. The operation after the A / D conversion circuit 142 is performed in the same manner as in the first embodiment.

Next, the operation when a fluorescent image is displayed will be described. Based on the signal from the controller 250,
The excitation light source power supply 115 is driven, and the GaN semiconductor laser
From 114, excitation light L7 having a wavelength of 410 nm is emitted. Excitation light L
7 is transmitted through the lens 116, enters the excitation light guide 201b, and is guided to the end of the endoscope.
The object to be measured 13 is irradiated from 203.

The fluorescent light L8 from the measured section 13 generated by the irradiation of the excitation light L7 is condensed by the condenser lens 204, reflected by the prism 208, transmitted through the stripe fill 205, and transmitted to the CCD image pickup device. The light is received at 207 and stored as signal charges corresponding to the intensity of the light. When capturing a fluorescent image, the CCD driver 24 is controlled by the controller 250.
0 performs interlace operation and binning read,
The signal is read from the CCD image pickup device 207.

First, the signal charges stored in the photodiodes 35 on the even-numbered lines or the odd-numbered lines are transferred to the adjacent vertical transfer CCD 36. Then vertical transfer CCD36
Transfer charge in the vertical direction in parallel. The vertically transferred signal charges are transferred to a horizontal transfer CCD of a horizontal shift register 32.
It is sequentially sent to 37.

In the horizontal shift register 32, when signal charges of pixels in one horizontal line are input, four signal charges are added, and
The added value is output to the signal processing circuit 221 of the fluorescence image processing unit 220 via the output circuit 33 provided at the left end. When all the signal charges of the horizontal transfer CCD 37 are output, the signal charges of the line on the upper stage are transferred to the vertical transfer CCD 37.
Transferred from 36. By repeating such an operation, the four pixel blocks 38 at the lower left of the imaging surface 34 shown in FIG.
From the right, the added signal charges are sequentially read four by four, and when the signal of one line is read, the signal charges of the next two lines are read and moved in order. Thus, the signals of all the pixels on the odd-numbered line or the even-numbered line are added four by four and read out.

In the signal processing circuit 221, the CCD image pickup device 20
7 performs the process signal processing of the signal output from the yellow bandpass filter 20 of the stripe filter 205.
The signal intensity Ye4 of the yellow band (green + red) is obtained from the signal charge output from the pixel 34 of the even line on which the light transmitted through 6a is incident, and the odd line on which the light transmitted through the full wavelength band filter 206b is incident. From the signal charges output from the pixel 34, the signal intensity W4 in the entire measurement wavelength band is obtained. Further, the signal strength B4 in the blue wavelength band is calculated from the following equation.

B4 = W4-Ye4 Further, a division value S is calculated from the following equation. S = B4 / W4 Further, this division value S is further divided into a reference value RE of a division value previously obtained from fluorescence obtained from normal tissues and diseased tissues. If the division value S is larger than RE, a pseudo-color image signal which is white indicating that the fluorescence is close to the fluorescence emitted from the normal tissue is set. A pseudo color image signal of red color indicating closeness to the obtained fluorescence is set and output to the A / D conversion circuit 132.
The operations after the A / D conversion circuit 132 are performed in the same manner as in the first embodiment. The pseudo color image signal of the fluorescent image is converted into a predetermined video signal by the fluorescent image encoder 135, and is input to the superimposer 150. Is imposed with the color image signal of the normal image output from the normal image encoder 145,
It is output to the monitor 170.

The monitor 170 converts the color image signal and the pseudo color image signal input as video signals and displays them as a normal image 14 and a fluorescent image 15.

As described above, by using the stripe filter 205 in which the line-shaped yellow bandpass filters 206a and the full-wavelength bandpass filters 206b are alternately combined, it is not necessary to divide the bandpass filters in the line direction. The manufacture of the means is easier, the performance of each bandpass filter is further improved and the manufacturing costs are reduced.

At the time of capturing a fluorescent image, a normal interlacing operation is performed to capture a fluorescent image based on the fluorescent light transmitted through the yellow band filter 206a and the full wavelength band filter 206b of the stripe filter 205. Interlaced operation and full wavelength band filter
Only the output of the even-numbered line where the light transmitted through 206b
Output to the signal processing circuit 231 and the yellow bandpass filter 206a
By discarding the output of the odd-numbered line on which the light transmitted through the pixel is discarded, it is possible to easily read out only the signal charges of the pixels of the even-numbered line and capture a normal image. For this reason,
By only slightly changing the control operation, it is possible to perform the imaging of the fluorescent image and the imaging of the normal image with one image sensor,
The convenience of the fluorescence imaging device can be improved.

Further, by using the stripe filter 205, the fluorescence L8 emitted from the measured part 13 of the living body irradiated with the excitation light is divided into two wavelength bands of a yellow wavelength band and a whole measurement wavelength band for imaging. And binning readout in which the signal charges of four consecutive pixels to which the light transmitted through the same bandpass filter is incident can be performed, so that the readout time of the signal charges can be shortened and the noise contamination can be reduced. Thus, the S / N of the captured image is improved.

The stripe filter 205 is a CCD image pickup device
207 is on-chip on the light receiving surface,
There is no need to provide an image plane for arranging the stripe filter 205 on the optical path incident on the CD image sensor 207, and the image forming optical system can be simplified. Also, the stripe filter 20
5 and the positioning accuracy of the CCD image sensor 207 in the stripe direction is loosened, so that the manufacture of the fluorescent image pickup device is further facilitated and the manufacturing cost is further reduced.

In the endoscope apparatus according to the second specific embodiment, only the horizontal binning read for adding the signal charges of the pixels in the horizontal direction is performed. The vertical binning reading to be added and the horizontal binning reading can be performed in combination. For example, first, the signal charges of the pixels in one line and the signal charges of the pixels in three lines in FIG. 10 are added by vertical binning reading, and then, the signal charges of four pixels are added and read in the horizontal direction by horizontal binning reading. Thus, the signal charges of the eight pixels in the pixel blocks 38 and 39 can be added and read. With this method, resolution is sacrificed, but an image with excellent contrast can be captured even when the amount of incident light is not sufficient.

Further, as a modified example of the endoscope apparatus according to the second specific embodiment, a fluorescence characteristic utilizing the difference between the fluorescence intensity of the fluorescence obtained from the normal tissue and the fluorescence intensity obtained from the diseased tissue is used. There is also an endoscope apparatus that determines a display color of a fluorescent image by a determination in which the determination method described above is combined with a determination method using the above-described division value S.

In this case, first, near-infrared light having a wavelength band of 650 nm or more is irradiated to reduce the influence of unevenness of the living body part and the difference in light absorption rate.
The signal intensity IR of the pixels on the odd-numbered lines of the CCD image pickup device 207 on which the light transmitted through 206b is incident is calculated, and the fluorescence yield T, which is the ratio to the signal intensity W4 when the excitation light is irradiated, is determined. Based on the fluorescence yield T and the division value S, it was determined whether the characteristic of the detected fluorescence was closer to the characteristic of the fluorescence obtained from the normal tissue or the fluorescence obtained from the diseased tissue, and the result of the determination was reflected. Display a color fluorescent image. Since the characteristic of the fluorescence is determined from the value in which the difference in the waveform of the fluorescence spectrum and the difference in the intensity of the fluorescence spectrum are taken into account, the reliability of the determination of the fluorescence characteristic is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an endoscope apparatus which is a first specific embodiment to which a fluorescence imaging apparatus according to the present invention is applied.

FIG. 2 is a schematic configuration diagram of a CCD imaging device used in the endoscope apparatus according to the first specific embodiment.

FIG. 3 is a schematic configuration diagram of a two-color filter used in the endoscope apparatus according to the first specific embodiment.

FIG. 4 is a diagram showing a transmission wavelength band of a band filter constituting the two-color filter.

FIG. 5 is a partially enlarged schematic diagram of the CCD image sensor.

FIG. 6 is a schematic configuration diagram of an endoscope apparatus which is a second specific embodiment to which the fluorescence imaging apparatus according to the present invention is applied.

FIG. 7 is a partially enlarged schematic view of a CCD image pickup device used in the endoscope apparatus according to the second specific embodiment.

FIG. 8 is a schematic configuration diagram of a stripe filter used in the endoscope apparatus according to the second specific embodiment.

FIG. 9 is a diagram showing a transmission wavelength band of a bandpass filter constituting the stripe filter.

FIG. 10 is a diagram for explaining the operation of the CCD image sensor.

FIG. 11 is a spectrum intensity distribution diagram of fluorescence emitted from normal tissue and diseased tissue.

[Explanation of symbols]

 10,13 Target part 11,14 Fluorescent image 12,15 Normal image 100,200 Endoscope 110,210 Illumination unit 114 GaN semiconductor laser 120 Fluorescent imaging unit 107 Mosaic filter 122 Two-color filter 125,207 CCD image sensor 126,240 CCD driver 130,220 Fluorescent image processing Unit 140,230 Normal image processing unit 150 Superimposer 160,250 Controller 170 Monitor 205 Stripe filter L1 White light L2, L6 Reflected light L3, L7 Excitation light L4, L8 Fluorescence L5 Sequential light

Claims (5)

[Claims] 1. A fluorescence imaging apparatus comprising: an excitation light irradiating unit that irradiates excitation light to a measurement target; and an imaging unit that captures fluorescence emitted from the measurement target by irradiation of the excitation light. The means includes an image sensor in which a number of pixels are arranged two-dimensionally, and a filter means in which a large number of at least two types of band filters having different transmission wavelength bands are combined on a two-dimensional plane, A fluorescence imaging apparatus provided on an imaging plane between the imaging elements, wherein each of the bandpass filters corresponds to a plurality of pixels arranged continuously in the imaging element. 2. The fluorescence imaging apparatus according to claim 1, wherein said filter means comprises a linear band-pass filter combined in a stripe shape. 3. The image pickup device according to claim 1, wherein the image pickup device is a charge transfer type image pickup device, and the line-shaped band-pass filter corresponds to a pixel column arranged along a charge transfer direction. 3. The fluorescence imaging device according to 2. 4. The apparatus according to claim 1, wherein said filter means is provided on a light receiving surface of said image sensor.
The fluorescence imaging device according to claim 1. 5. A binning control unit for adding and reading signal charges of a plurality of pixels of the image pickup device, wherein the binning control unit converts a signal charge of a pixel corresponding to a bandpass filter transmitting the same wavelength band. The fluorescence imaging apparatus according to any one of claims 1 to 4, wherein the addition is performed.