JP2002354346A - Imaging method and device using solid-state imaging element with electric charge intensifying shift register - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the S/N ratio of image signals, read out from a solid-state image pickup element with an electric charge intensifying shift register, with respect to an imaging method and a device by using the solid-state imaging element with the electric charge intensifying shift register. SOLUTION: A part of living body texture 1 is irradiated with pulse-like excitation light and the image of the fluorescence produced by the living body texture 1, irradiated with the pulse-like excitation light, is received by the solid-state imaging element 20, with the electric charge intensifying shift register and fluorescent image signals representing the fluorescent image are obtained by photoelectric transfer. The fluorescent image signals are read out, at a frame rate which is higher than 60 frames/sec and lower than 1500 frames/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup method and apparatus using a solid-state image pickup device, and more particularly, to a charge multiplication type solid-state image pickup device utilizing an impact ionization phenomenon capable of detecting weak light. The present invention relates to an imaging method and apparatus used.

[0002]

2. Description of the Related Art In general, noise components that lower the S / N of an image signal output from a solid-state imaging device such as a CCD are mainly dark noise and read noise, and dark noise increases in proportion to the read time. The read noise decreases according to the read time (reciprocal of the frame rate).

As shown in FIG. 2, noise generated when an image signal is read from a conventional ordinary solid-state image sensor at a frame rate of 60 frames / sec, which is a normal moving image frame rate, is higher than a read noise R than a dark noise D. Is dominant, and the read noise R decreases as the frame rate decreases (the readout time increases).

In particular, when a weak image is obtained as an image signal as in the case of observing a living tissue in a body cavity as a moving image with an endoscope, the read noise greatly degrades the image quality. Is reduced (the readout time is lengthened) and the frame rate (1/3) such as 30 frames / sec or 20 frames / sec is reduced.
The reading time is set to 0 second or 1/20 second), and reading is performed slowly to reduce read noise and increase the S / N of the acquired image signal. Note that an image signal acquired with a frame rate smaller than 60 frames / sec cannot be reproduced as a moving image in which an image changes smoothly even if it is visualized.

By the way, a charge multiplying type solid-state image pickup device (hereinafter, referred to as a solid-state image pickup device with a charge multiplying shift register) which amplifies electric charges by utilizing an impact ionization phenomenon has been developed. It is known that the use of a register-equipped solid-state imaging device can amplify photoelectrically converted charges without increasing read noise.
Also, studies are being made to utilize this solid-state imaging device with a charge multiplication shift register for capturing moving images of a living tissue in a body cavity to reduce read noise and significantly improve the S / N of an acquired image signal. ing.

The solid-state image pickup device with a charge multiplication shift register is an image pickup device having a shift register with a charge multiplication function between a horizontal readout shift register of a CCD and an output amplifier. This is to amplify the photoelectrically converted charge by the impact ionization effect caused by the above. The principle that a shift register with a charge multiplication function multiplies charge is based on the impact ionization phenomenon (charge shift) in which secondary electrons are generated when charges are transferred to a deep potential formed with sufficient strength. When it collides with silicon, the element that makes up the resistor,
Electron-hole generation).
The transfer of the charges transferred from the horizontal read shift register is performed by multi-stage shift registers each having a deep potential, whereby the generation of the secondary electrons is repeated, and the charges are amplified without amplifying the read noise. This solid-state imaging device with a charge multiplying shift register is described in detail in US Pat. No. 5,337,340.

[0007]

However, the solid-state imaging device with the charge multiplying shift register has the same performance as that of the conventional solid-state imaging device with respect to generation of dark noise, and suppresses generation of read noise. As a result, dark noise becomes dominant with respect to noise generated at a frame rate in the vicinity of 60 frames / sec. In particular, dark noise is formed by several photons as in the case of imaging fluorescence generated from living tissue in a body cavity. In an apparatus that is required to capture an extremely weak image, there remains a problem that the generation of the dark noise must be further suppressed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to improve the S / N of an image signal read from a solid-state imaging device with a charge multiplying shift register. It is an object of the present invention to provide an imaging method and an apparatus using the same.

[0009]

In order to solve the above-mentioned problems, the present inventor has studied various image signal reading methods using a solid-state image pickup device with a charge multiplying shift register. Attention is paid to the fact that dark noise is more dominant than read noise in reading image signals at a rate, and a solid-state image sensor with a charge multiplying shift register is used at a frame rate higher than 60 frames / sec, which has not been conventionally performed. By reading out the image signal from the image sensor, it was found that noise mixed into the image signal can be suppressed to a smaller level, and the present invention has been made based on this finding.

An image pickup method using a solid-state image pickup device with a charge multiplying shift register according to the present invention irradiates a subject with pulsed light, and multiplies an image by light generated from the subject or light reflected by the subject. The solid-state imaging device with a shift register receives light, performs photoelectric conversion to obtain an image signal representing the image, and reads out the image signal at a frame rate greater than 60 frames / sec and less than 1500 frames / sec. It is.

An image pickup apparatus using a solid-state image pickup device with a charge multiplying shift register according to the present invention comprises: an irradiating means for irradiating a subject with pulsed light; A solid-state imaging device with a charge multiplication shift register for receiving an image formed by light reflected by a subject and performing photoelectric conversion to obtain an image signal representing the image; reading means for reading out the image signal at a frame rate greater than sec and less than 1500 frames / sec.

That is, since the solid-state image pickup device with the charge multiplication shift register does not amplify the read noise when multiplying the image signal, as shown in FIG. 60 frames / se
The noise generated when reading at a frame rate near c is dominated by dark noise D, and the magnitude of the dark noise D decreases as the frame rate increases (reading time decreases). Therefore, in order to reduce noise at a frame rate near 60 frames / sec, it is only necessary to increase the frame rate (shorten the reading time) and reduce the dark noise component.

If the frame rate at the time of reading an image signal from the solid-state image pickup device with the charge multiplying shift register is too high (the reading time is too short), the read noise R becomes dominant again as shown in FIG. Therefore, the sum of the read noise R and the dark noise D is calculated as 60 frames / sec.
The range of the frame rate that can be suppressed to be smaller than the sum S of the read noise and the dark noise generated when reading the image signal from the solid-state imaging device with the charge multiplication shift register at the frame rate of c is more than 60 frames / sec and 1500. The range is smaller than frame / sec.

The calculating means for calculating the image signal read from the reading means is a charge multiplying shift register based on the value of the image signal representing the image read from the reading means without irradiating pulsed light. A subtraction image signal may be obtained by subtracting the value of the image signal received by the attached solid-state imaging device and photoelectrically converted and read from the reading unit,
Further, the arithmetic unit averages a plurality of the subtraction image signals obtained based on a plurality of image signals representing images sequentially read from the reading unit to obtain an average subtraction image signal. be able to.

A calculating means for calculating an image signal read from the reading means, for obtaining an averaged image signal by averaging a plurality of image signals representing an image continuously read from the reading means; It can be.

The image pickup apparatus using the solid-state image pickup device with the charge multiplying shift register can be applied to an endoscope.

The pulsed light emitted from the irradiating means may be two or more types of light having different spectral distributions from each other.

[0018] The readout means may be provided with a charge-multiplier shift register-equipped solid-state image sensor having a speed of more than 60 frames / sec.
It is preferable that the image signal is read at a frame rate of 00 frames / sec or less.

[0019]

According to the imaging method and apparatus using the solid-state imaging device with the charge multiplying shift register of the present invention, the image signal obtained by the solid-state imaging device with the charge multiplying shift register is set to be larger than 60 frames / sec. Since reading is performed at a frame rate smaller than 1500 frames / sec, the S / N is higher than that of an image signal which has been conventionally read at a frame rate of 60 frames / sec.
Can be obtained.

Because, as described above, 60 frames /
Regarding reading of an image signal from the solid-state imaging device with the charge multiplication shift register at a frame rate near sec, dark noise is the dominant noise, and decreases as the frame rate increases (as the reading time decreases). This is because the amount of dark noise exceeds the amount of increase in read noise, and the sum of dark noise and read noise can be reduced by increasing the frame rate. On the other hand, at a frame rate near 1500 frames / sec, contrary to the above, the amount of dark noise that decreases as the frame rate increases is smaller than the increase amount of the read noise, and as the frame rate increases ( The sum of the dark noise and the read noise increases (as the read time decreases). And the frame rate is 1500
When the speed is equal to or more than the frame / sec, the sum of the dark noise and the read noise becomes larger than the sum of the dark noise and the read noise generated when the image signal is read at a frame rate of 60 frames / sec. Therefore,
More than 60 frames / sec and 1500 frames / s
When the image signal is read at a frame rate of 60 frames / sec by reading the image signal within the range of the frame rate smaller than ec, the S / N of the image signal read from the solid-state imaging device with the charge multiplying shift register is reduced. Can be improved as compared with

Furthermore, if the image signal is read at a frame rate of more than 60 frames / sec and not more than 300 frames / sec, the image read at the frame rate of 60 frames / sec conventionally can be performed while suppressing the apparatus cost. An image signal having a higher S / N than a signal can be obtained.

That is, when the frame rate is increased, the reading time is shortened, and the speed of processing the image signal must be increased. However, generally, when the signal processing speed is increased, the device cost of the signal processing circuit increases. Considering this, at a frame rate of more than 60 frames / sec and 300 frames / sec or less, it is possible to reduce the apparatus cost to a practical level, and to increase the S / N ratio as compared with the related art. Therefore, it is possible to obtain a sufficient effect of acquiring an image signal having.

The calculating means for calculating the image signal read from the reading means is provided with a pulse-like signal based on the value of the image signal representing the image received and irradiated with the pulse-like light read from the reading means. If the subtraction image signal is obtained by subtracting the value of the image signal read from the reading unit without irradiating the light, the signal component which becomes the noise received without irradiating the pulsed light can be used. It can be excluded from the image signal, and the S / N of the image signal can be further improved. Further, if the arithmetic means is configured to obtain an average subtracted image signal by averaging the plurality of subtracted image signals representing the image continuously read from the reading means, the value of the image signal representing the image is obtained. Are averaged, and the S / N of the image signal can be further improved.

The arithmetic means for calculating the image signal read from the reading means obtains an averaged image signal by averaging a plurality of image signals representing an image continuously read from the reading means. In this case, the value of the image signal representing the image is averaged, and the S / N of the image signal can be further improved.

Further, the imaging apparatus according to the present invention using the solid-state imaging device with the charge multiplying shift register is suitable for an endoscope which targets weak light. Observation can be made more accurately.

Further, when the pulsed light emitted from the irradiating means is two or more types of light having different spectral distributions from each other, it is possible to obtain a normal tissue property and an abnormal tissue property (lesion) of a living body. Can be emphasized and observed, and the diagnosis of the living body can be easily and accurately performed.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of an embodiment in which an imaging apparatus that performs an imaging method using a solid-state imaging device with a charge multiplication shift register according to the present invention is applied to a fluorescence endoscope apparatus, and FIG. FIG. 3 is a diagram showing a relationship between a read time when an image signal is read from a general image sensor and noise mixed in the read image signal. FIG. 3 shows a case where an image signal is read from a solid-state image sensor with a charge multiplying shift register. Showing the relationship between the read time of the image and the noise mixed in the read image signal, FIG. 4 to FIG.
5 is a timing chart showing a read time when reading an image signal.

A fluorescent endoscope apparatus 100 according to an embodiment of the present invention includes an irradiating unit 10 for irradiating a pulsed light to a living tissue 1 as a subject, and a irradiating unit 10 for irradiating the pulsed light. A solid-state imaging device 20 with a charge-multiplying shift register, which receives an image of generated light or light reflected by the living tissue 1 and photoelectrically converts the image to obtain an image signal representing the image, and a solid-state imaging with a charge-multiplying shift register A reading unit 30 that reads out an image signal from the element 20 at a frame rate greater than 60 frames / sec and less than 1500 frames / sec. Note that the frame rate is a value represented by 1 / (image exposure time + exposed image reading time).

The fluorescence endoscope apparatus 100 further includes an A / D converter 40 for converting the image signal read from the reading means 30 into a digital value and outputting the digital value, and an A / D converter read from the reading means 30. Calculating means 50 for calculating an image signal converted into a digital value by the converter 40; a display 70 for converting the image signal output from the calculating means 50 into a video signal for display; Registered solid-state imaging device 20, reading means 30, A / D converter 4
0, a controller 60 for controlling the operation of the arithmetic means 50 and the timing of each operation.

The irradiating means 10 includes a gallium nitride-based pulse-driven semiconductor laser (GaN-LD) for emitting a pulsed excitation light having a wavelength of about 410 nm and a pulse-driven laser for emitting a pulsed near-infrared light. A light source device 11 is provided, and a light guide 12 for propagating excitation light emitted from the light source device 11 to the end G of the endoscope.

The reading means 30 includes a floating diffusion amplifier for converting an analog signal (charge), which is an image signal output from the solid-state imaging device 20 with a charge multiplying shift register, into a voltage, and an output of the floating diffusion amplifier. An A / D conversion gain adjustment amplifier 32 for amplifying a voltage is provided.

Next, the operation of the above embodiment will be described.

<First Embodiment> First, a fluorescent image due to fluorescence generated from a subject irradiated with pulsed excitation light is received by a solid-state image pickup device with a charge multiplying shift register and photoelectrically converted to convert the fluorescent image. A case will be described in which a fluorescent image image signal is acquired and the fluorescent image image signal acquired by the solid-state imaging device with the charge multiplying shift register is read at a frame rate greater than 60 frames / sec and less than 1500 frames / sec. In the first embodiment, the calculation of the image signal is not performed.

The pulsed excitation light emitted from the light source device 11 is applied to the living tissue 1 through the light guide 12. Fluorescence generated from the living tissue 1 irradiated with the pulse-like excitation light is imaged as a fluorescent image on a light receiving surface 21 of a solid-state imaging device with a charge multiplying shift register (hereinafter, referred to as DZS 20) through an imaging lens 71. Is done. Note that an excitation light cut filter 72 is provided between the imaging lens 71 and the light receiving surface 21 to block the excitation light entering the light receiving surface 21 together with the fluorescent image. The DZS 20 receives the fluorescent image formed on the light receiving surface 21 and performs photoelectric conversion to obtain a fluorescent image signal representing the fluorescent image. The fluorescence image signal acquired by the DZS 20 is
Greater than 0 frames / sec and 1500 frames / sec
It is read at a frame rate smaller than c. The fluorescence image signal read from the reading means 30 is supplied to the A / D converter 4.
The signal is A / D converted by 0, output as a digital fluorescence image signal consisting of a digital value, and stored in the arithmetic means 50.

The digital fluorescence image signal stored in the calculating means 50 is output to the display 70 as it is without being calculated in the calculating means 50, converted into a video signal and displayed.

Here, DZ is determined according to the frame rate.
The operation of improving the S / N of the image signal read from S20 will be described.

As shown in FIG. 2, the read noise R is more dominant than the dark noise D when the image signal is read out from the conventional ordinary solid-state imaging device at a frame rate near 60 frames / sec. Yes, the read noise R decreases as the frame rate decreases (the readout time increases). Therefore, in order to reduce noise at a frame rate near 60 frames / sec, it is only necessary to reduce the frame rate (extend the readout time) and reduce the read noise component. That is, the frame rate is reduced from 60 frames / sec to 30 frames / sec and further to 20 frames / sec (the readout time is reduced from 1/60 sec to 1/30 sec and 1/20 sec.
2), the sum of the read noise R and the dark noise D decreases along the curve W in FIG. 2, and the S / N of the image signal read from the image sensor can be increased.

On the other hand, in the solid-state image pickup device with the charge multiplication shift register, as shown in FIG. 3, as is apparent from the above-described noise characteristics, noise generated when reading at a frame rate near 60 frames / sec. Since the dark noise D becomes dominant and the dark noise D decreases as the frame rate increases (readout time decreases), the frame rate must be increased to reduce noise at a frame rate near 60 frames / sec. In this case, the dark noise component may be reduced by reducing the read time.

If the frame rate is too high, the read noise R increases. Therefore, the sum of the read noise R and the dark noise D is suppressed by setting the frame rate to be greater than 60 frames / sec and less than 1500 frames / sec. be able to. Note that the sum of the read noise R and the dark noise D is indicated by a curve W in FIG. Further, the range of the frame rate indicated by P in the figure is 300 frames / sec, which is larger than 60 frames / sec.
Within a frame rate range of less than or equal to sec, the apparatus cost can be suppressed to a practical level, and a sufficient effect of acquiring an image signal having a higher S / N than that of the related art can be obtained. .

<Second Embodiment> Next, from the value of the fluorescence image signal representing the fluorescence image read out by the same method as in the first embodiment, the pulse-like excitation light is not irradiated. A case will be described in which the value of the non-irradiation image signal received, photoelectrically converted, and read by the solid-state imaging device with the charge multiplication shift register is subtracted to obtain a subtraction image signal.

The fluorescent image signal representing the fluorescent image read out by the same method as that of the first embodiment is A / D converted by the A / D converter 40 and converted into a digital fluorescent image signal by the arithmetic means 50. It is memorized.

Subsequently, an image of the living tissue 1 which does not emit the excitation light from the light source device 11 and is not irradiated with the excitation light is DZ.
In S20, the light is received, photoelectrically converted, and obtained as a non-irradiated image signal. The non-irradiated image signal is read from the DZS 20 by the reading means 30 at the same frame rate as described above, A / D converted by the A / D converter 40, and stored in the arithmetic means 50 as a digital non-irradiated image signal. The digital non-irradiated image signal is a noise component (for example, an image signal obtained by the influence of room illumination light, dark noise, or fluorescent light other than fluorescent light generated by irradiation with excitation light such as lead noise). (A component of an image signal mixed as noise).

Note that the image signal reading time at this time is:
The reading time is set as shown in the timing chart of FIG. 4 to read out the fluorescence image received by the DZS 20 as a fluorescence image signal, and the reading time of the living tissue 1 not irradiated with the excitation light formed on the DZS 20 is set. The readout time for reading out the image as a non-irradiated image signal is set to 1/120 second, that is, the image signal is read out from the DZS 20 at 120 frames / sec larger than 60 frames / sec. Can be increased.

The arithmetic means 50 subtracts the digital non-irradiation image signal from the digital fluorescence image signal acquired and stored as described above, and creates and outputs a subtraction image signal representing a fluorescence image having a higher S / N. I do. The subtracted image signal output from the calculating means 50 is converted into a video signal,
It is displayed on the display 70 at a frame rate of sec.

The digital non-irradiated image signal does not necessarily have to be acquired every time a fluorescent image is acquired. If the amount of noise mixed in the image signal is constant, the value of the noise mixed in the image signal is reduced. This value may be measured in advance and this value may be used as a digital non-irradiated image signal.

<Third Embodiment> Next, a plurality of subtractions created by a method similar to that of the second embodiment described above based on a plurality of fluorescent image signal signals representing a fluorescent image read continuously. A case where an image signal is added and averaged to obtain an average subtracted image signal will be described.

The first subtraction image signal created based on the fluorescence image signal and the non-irradiation image signal read out in the same manner as in the second embodiment is stored in the arithmetic means 50.

Subsequently, the second subtraction image signal created in the same manner as described above is stored in the arithmetic means 50.

The first subtraction image signal and the second subtraction image signal are added and averaged by the arithmetic means 50, and an average subtraction image signal representing a fluorescent image having a higher S / N is created and output.

Here, the reading time of the image signal obtained when the average subtracted image signal is created will be described.

As shown in FIG. 5, the reading time for reading the fluorescence image signal and the non-irradiation image signal from the DZS 20 is both set to 1/240 second (frame rate of 240 frames / sec). Based on the fluorescence image signal and the non-irradiated image signal, a subtraction image signal is created by the arithmetic unit 50 every 1/120 second (each frame rate of 120 frames / sec). The two generated subtracted image signals are further averaged and output as an average subtracted image signal from the calculating means 50 every 1/60 second (each frame rate of 60 frames / sec).

The output average subtracted image signal is converted into a video signal and displayed on the display 70 at a frame rate of 60 frames / sec.

<Fourth Embodiment> Next, a fluorescence image signal representing a plurality of fluorescence images read continuously by the same method as in the first embodiment is added and averaged to obtain an averaged image signal. The case of acquiring is described.

The fluorescent image signal representing the fluorescent image read out by the same method as in the first embodiment is A / D converted by the A / D converter 40 and is calculated as a first digital fluorescent image signal. It is stored in the means 50.

Subsequently, the fluorescent image signal representing the fluorescent image read out in the same manner as described above is converted into an A / D signal by the A / D converter 40.
/ D converted and stored in the arithmetic means 50 as a second digital fluorescent image signal.

The first digital fluorescent image signal and the second digital fluorescent image signal are added and averaged by the arithmetic means 50, and an averaged image signal representing a fluorescent image with a higher S / N is created and output. .

Here, the reading time of an image signal obtained when the above-mentioned averaged image signal is created will be described.

As shown in FIG. 6, the reading time for reading out the fluorescent image received by the DZS 20 as a fluorescent image signal from the DZS 20 is 1/120 seconds (120 frames / s).
ec frame rate). That is,
120 frames / sec larger than 60 frames / sec
Since the fluorescence image signal is read from the DZS 20 at c, the occurrence of dark noise can be suppressed, and the S / N of the read fluorescence image signal can be increased. D
The first digital fluorescent image signal and the second digital fluorescent image signal read from the ZS 20 and A / D converted are further averaged to obtain a 1/6 averaged image signal.
It is output from the calculating means 50 every 0 seconds (each frame rate of 60 frames / sec).

The averaged image signal output from the arithmetic means 50 is converted into a video signal and displayed on the display 70 at a frame rate of 60 frames / sec.

<Fifth Embodiment> Next, a case where the pulsed light emitted from the irradiating means is two or more types of light having different spectral distributions from each other will be described.

The living tissue 1 is irradiated with pulsed excitation light and near-infrared light having different spectral distributions emitted from the light source device 11 through the light guide 12 at different timings.

The fluorescent image generated by the fluorescent light generated from the living tissue 1 irradiated with the pulsed excitation light is received by the DZS 20, photoelectrically converted and obtained as a fluorescent image signal representing the fluorescent image. Read A
A / D converted by the / D converter 40 and stored in the arithmetic means 50 as a digital fluorescent image signal.

On the other hand, the near-infrared light image reflected by the living tissue 1 after being irradiated with the pulsed near-infrared light is also stored in the arithmetic means 50 as a digital near-infrared light image signal in the same manner as described above. .

The calculating means 50 calculates a ratio between the digital fluorescence image signal and the digital near-infrared light image signal to create and output a normalized fluorescence intensity image signal.

Here, the reading time of the image signal acquired when the above-mentioned normalized fluorescence intensity image signal is created will be described.

As shown in FIG. 7, the reading time for reading out the fluorescence image received by the DZS 20 as a fluorescence image signal from the DZS 20 and the near-infrared light image received by the DZS 20 to the near-infrared light image signal The readout times are set to 1/120 seconds (a frame rate of 60 frames / sec). That is, since the image signal is read from the DZS 20 at a frame rate of 120 frames / sec, which is a frame rate larger than 60 frames / sec, the generation of dark noise can be suppressed and the S / N of the obtained image signal can be increased. The standardized fluorescence intensity image signal output from the calculating means 50 is converted into a video signal and displayed on the display 70 at a frame rate of 60 frames / sec.

A flash xenon lamp which emits pulsed white light to the irradiation means, and a spectroscope which splits the light emitted from the flash xenon lamp into red light, blue light and green light in a plane-sequential manner. The light source may further be provided, and a color image may be displayed on the display 70 by the same method as described above.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a fluorescent endoscope apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between read time and noise of a general image sensor.

FIG. 3 is a diagram illustrating a relationship between a read time and noise of a solid-state imaging device with a charge multiplication shift register.

FIG. 4 is a timing chart when creating a subtraction image signal.

FIG. 5 is a timing chart for generating an average subtraction image signal.

FIG. 6 is a timing chart when an averaging image signal is created.

FIG. 7 is a timing chart when creating a normalized fluorescence intensity image signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Living tissue 10 Irradiation means 20 Solid-state image sensor with charge multiplication shift register 30 Reading means 40 A / D converter 50 Operation means 60 Controller 70 Display 100 Fluorescence endoscope device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 23/24 G02B 23/24 B 23/26 23/26 D H01L 21/339 H04N 7/18 M 29 / 762 H01L 29/76 301E H04N 7/18 F term (reference) 2H040 BA00 CA06 CA23 GA02 GA05 GA11 4C061 CC06 HH51 LL02 MM01 MM03 NN01 QQ03 QQ04 QQ10 SS05 SS11 SS21 4M118 AA02 AA05 AB01 AB10 BA10 BA30 DD04X03 EX03 5 5C054 CB03 CC07 HA12

Claims (8)

[Claims] 1. An object is irradiated with pulsed light, and an image formed by light emitted from the object or light reflected by the object is received by a solid-state image pickup device with a charge multiplying shift register, and is photoelectrically converted. An image signal representing an image is obtained, and the image signal is set to a value greater than 60 frames / sec.
An imaging method using a solid-state imaging device with a charge multiplication shift register, wherein reading is performed at a frame rate smaller than 500 frames / sec. 2. An irradiating means for irradiating a subject with pulsed light, and receiving an image of light generated from the subject irradiated with the pulsed light or light reflected by the subject, and performing photoelectric conversion. A solid-state imaging device with a charge multiplying shift register for obtaining an image signal representing the image, and 60 frames / s from the solid-state imaging device with the charge multiplying shift register.
reading means for reading the image signal at a frame rate larger than ec and smaller than 1500 frames / sec. 3. An arithmetic unit for calculating an image signal read from the reading unit, wherein the calculating unit calculates the pulse signal from the value of the image signal representing the image read from the reading unit. Subtracting the value of the image signal that is received by the solid-state imaging device with the charge multiplication shift register without being irradiated with light, photoelectrically converted, and read from the reading unit to obtain a subtracted image signal. An imaging apparatus using the solid-state imaging device with a charge multiplying shift register according to claim 2. 4. An average subtracted image signal obtained by averaging a plurality of subtracted image signals obtained based on a plurality of image signals representing the image successively read from the reading unit, wherein the calculating means averages the subtracted image signals. 4. An imaging apparatus using a solid-state imaging device with a charge multiplying shift register according to claim 3, wherein: 5. An arithmetic unit for calculating an image signal read from the reading unit, the arithmetic unit adding a plurality of the image signals representing the image continuously read from the reading unit. 3. An image pickup apparatus using a solid-state image pickup device with a charge multiplying shift register according to claim 2, wherein an averaged image signal is obtained by averaging. 6. An imaging apparatus using a solid-state imaging device with a charge multiplication shift register according to claim 2, wherein the imaging apparatus is applied to an endoscope. 7. The solid-state image pickup device with a charge multiplying shift register according to claim 6, wherein said pulsed light emitted from said irradiating means is two or more types of light having different spectral distributions from each other. An imaging device using the device. 8. The method according to claim 1, wherein the readout means is configured to output a signal from the solid-state imaging device with the charge multiplication shift register which is greater than 60 frames / sec.
8. The imaging device using a solid-state imaging device with a charge multiplication shift register according to claim 2, wherein the image signal is read at a frame rate of 00 frames / sec or less.