JPH01217415A - Light source device for endoscope - Google Patents

Abstract

PURPOSE:To supply various illuminating beams including face sequential beams capable of forming a color image and to obtain various images having different observation wave length areas or the like in accordance with an observing portion, an observing purpose or the like by switching filters by a filter switching means. CONSTITUTION:The title device is provided with plural kinds of filters 51a-51c arranged so as to be optionally loaded/unloaded to/from the illuminating optical path of a light source 21 and including filters capable of separating beams projected from the light source 21 time sequentially at least into three wavelength areas capable of forming a color image and the filter switching means 43 capable of inserting one of the filters 51a-51c into the illuminating optical path. Thereby, plural kinds of illuminating beams including face sequential beams capable of forming a color image can be supplied by switching the filter by means of the filter switching means. Consequently, various illuminating beams can be supplied so that various images having different observation wavelength areas or the like can be obtained in accordance with an observing portion, an observing purpose or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light source device for an endoscope that can supply various types of illumination light so that various images with different observation wavelength ranges can be obtained.

[Problems to be solved by conventional techniques and inventions] In recent years,
Endoscopes are widely used to allow the observation of organs within a body cavity by inserting an elongated insertion section into a body cavity, and to perform various therapeutic procedures as necessary using a treatment instrument inserted into a treatment instrument channel. There is.

Furthermore, various electronic endoscopes using solid-state imaging devices such as charge-coupled devices (CODs) as imaging means have been proposed.

By the way, it is known that knowing the amount of hemoglobin in blood and the distribution of oxygen saturation is useful for early detection of lesions. As a method for determining hemoglobin concentration and oxygen saturation in blood, for example,
As shown in the above publication, there is a method of obtaining the hemoglobin from images in a plurality of specific wavelength regions related to hemoglobin in blood.

However, since the observation wavelength range is fixed in the camera shown in the conventional example, it is not possible to obtain an image in the visible region within the membrane, and it is not possible to obtain an image in the visible region within the film, and it is not possible to obtain the optimum observation according to the vA detection area, observation purpose, etc. I couldn't do it.

In addition, for example, Japanese Patent Application Laid-open No. 56-3033 focuses on the fact that there are cases where the change in color tone is large in regions other than the visible region, for example, in the infrared wavelength region, and at least one in the infrared wavelength region. The spectral light that it has is guided in time series to illuminate the object to be observed, and the reflected light from the object is imaged on a solid-state imaging device, which converts it into an electrical signal, and processes the electrical signal according to the wavelength range. However, a technique has been disclosed in which an image in a wavelength region is displayed using a specific color signal. According to this conventional example, invisible information obtained in the infrared wavelength region can be converted into visible information, and for example, it is possible to quickly identify affected areas and normal areas.
It becomes possible to do it easily.

However, even in this conventional example, since the observation wavelength range is fixed, for example, when using infrared light, it is not possible to obtain images in the visible range inside the shell, and comparisons between general images and special images Furthermore, there are problems in that it is difficult to detect vA and is not effective for vA objects having characteristics in other wavelength regions.

In the case of an endoscope device that captures images in a field-sequential manner, it is possible to obtain special images such as those described above by changing the wavelength range of the field-sequential illumination light. In the light source device, the rotating filter that separates the illumination light in time series is fixed in the illumination optical path, so the light source device had to be changed in order to switch the type of illumination light.

[Object of the Invention] The present invention has been made in view of the above circumstances, and provides a method for supplying various illumination lights so that various images with different observation wavelength ranges etc. can be obtained depending on the observation site, observation purpose, etc. It is an object of the present invention to provide a light source device for an endoscope that can perform the following functions.

[Means and effects for solving the problems] The light source device for an endoscope of the present invention is provided with a light source and an illumination optical path of the light source so as to be freely inserted and removed, and at least converts the light emitted from the light source into a color image. a plurality of types of filters including filters that can be separated in time series into three wavelength regions capable of forming a filter, and a filter switching means that can selectively insert one of the plurality of types of filters into an illumination optical path. By switching the filters using a filter switching means, a plurality of types of illumination light including field sequential light capable of forming a color image can be supplied.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 to 15 relate to one embodiment of the present invention;
The figure is a block diagram showing the configuration of the endoscopic device, FIG. 2 is a side view showing the entire endoscope device, FIG. 3 is a cross-sectional view of the filter cassette to show the rotary filter, and FIG. 3
A-A = line sectional view in the figure, Figure 5 is a perspective view of the filter cassette changer, Figure 6 is a plan view of the filter cassette changer, Figure 7 is a perspective view showing the back side of the filter cassette changer, Figure 8 is a sectional view taken along line B-B in Figure 6, and Figure 9 is a normal ? i! l! Explanatory diagrams showing the transmission characteristics of each filter of the rotary filter for inspection, Figures 10 and 1
Figure 1 is an explanatory diagram showing the transmission characteristics of each filter of the rotation filter for special images, Figures 12 and 13 are explanatory diagrams showing changes in blood absorbance due to changes in oxygen saturation of hemoglobin, and Figure 14 is an explanatory diagram showing the transmission characteristics of each filter of the rotation filter for special images. FIG. 15 is a sectional view of a filter cassette showing another example of a rotating filter for normal observation. FIG. 15 is a sectional view of a filter cassette showing a rotating filter in a modified example of this embodiment.

As shown in FIG. 2, the electronic endoscope 1 connected to the light source device of this embodiment has an elongated, for example, flexible insertion section 2, and a large-diameter insertion section 2 at the rear end of the insertion section 2. An operating section 3 is provided in series. A flexible cable 4 extends laterally from the rear end of the operating section 3, and a connector 5 is connected to the tip of the cable 4.
is provided. The electronic endoscope 1 is connected via the connector 5 to a video processor 6 having a built-in light source device and a signal processing circuit.

Furthermore, a monitor 7 is connected to the video processor 6.

On the distal end side of the insertion portion 2, a rigid distal end portion 9 and a bendable portion 10 adjacent to the distal end portion 9 and capable of bending toward the rear side are sequentially provided. Furthermore, by rotating a bending operation knob 11 provided on the operating section 3, the bending section 10 can be bent in the left-right direction or the up-down direction. Further, the operation section 3 is provided with an insertion port 12 that communicates with a treatment instrument channel provided in the insertion section 2.

As shown in FIG. 1, inside the insertion section 2 of the electronic endoscope 1,
A light guide 14 that transmits illumination light is inserted.

The distal end surface of this light guide 14 is located at the distal end 9 of the insertion section 2.
The distal end portion 9 can emit illumination light. Further, the incident end side of the light guide 14 is inserted into the universal cord 4 and connected to the connector 5. Further, the tip portion 9 is provided with an objective lens system 15, and a solid-state image sensor 16 is disposed at the imaging position of the objective lens system 15. This solid-state image sensor 16 has sensitivity in a wide wavelength range from the ultraviolet region to the infrared region, including the visible region.

Signal lines 26 and 27 are connected to the solid-state image sensor 16, and these signal lines 26 and 27 are inserted into the insertion section 2 and the universal cord 4 and connected to the connector 5.

On the other hand, a light source device 20 provided in the video processor 6
is equipped with a lamp 21 that emits broadband light ranging from ultraviolet light to infrared light. As this lamp 21, an internal xenon lamp, a strobe lamp, or the like can be used. The xenon lamp and strobe lamp emit large amounts of not only visible light but also ultraviolet light and infrared light. This lamp 21 is configured to be supplied with electric power by a power supply section 22. In front of the lamp 21, there are a plurality of filter cassettes 50 (the figure shows three filter cassettes).
is provided. This filter cassette 50 is selectively inserted into the illumination optical path by a filter cassette changer 70. Further, the filter cassette changer 70 is controlled by a control signal from the switching circuit 43. Also,
Each filter cassette 50 has a rotating filter 51,
When inserted into the illumination optical path, the rotating filter 51
is connected to a motor 23 and rotated by this motor 23. The rotation of this motor 23 is controlled and driven by a motor driver 25.

The configuration of the filter cassette 50 will be explained using FIGS. 3 and 4.

As shown in FIG. 3, the rotating filter 51 has three filters 51a, 51b, and 51c arranged along the circumferential direction. In the case of a rotating filter for normal observation, each of the filters 51a, 51b, and 51c is used for light in the red (R), green (G), and blue (B) wavelength regions, respectively, as shown in FIG. It is a filter that allows it to pass through. A plurality of holes 53 for detecting the rotational position of the rotary filter 51 are arranged along the circumferential direction on the inner peripheral side of each of the filters 51a, 51b, and 51c. Further, as shown in FIG. 4, the rotary filter 51 is housed in a housing 52 of a filter cassette 50, and
is a ball bearing 5 provided in the center of the housing 52.
It is rotatably supported by 5.55.

Windows 56 and 56 are provided in the front plate 52a and the back plate 52b of the housing 52 at positions facing each other and also facing each filter 51a, 51b, and 51C of the rotary filter 51, and windows 56 and 56 are provided at positions facing each other and also facing each filter 51a, 51b, and 51C of the rotary filter 51, and windows 56 and 56 are provided in the front plate 52a and the rear plate 52b of the housing 52. The emitted light passes through this window 56, 56 and each filter 51a, 51b, 5
It is designed to be able to pass through 1c. Further, windows 57, 57 are provided in the front plate 52a and the rear plate 52b at positions facing each other and also facing the rotational position detection hole 53 of the rotary filter 51. A light emitting element 61 is disposed outside one window 57, and the other window 57 is provided with a light emitting element 61.
A photosensor 62 is disposed on the outside of
is configured. That is, light emitted from the light emitting element 61 and passed through the hole 53 is received by the photosensor 62, and the output of this photosensor 62 is used by the timing generator 42. which generates the timing of the entire system. is now entered.

Further, the rotary shaft 54 of the rotary filter 51 protrudes rearward from the rear plate 52b side of the housing 52. On the other hand, a clutch 64 is provided at the end of the output shaft of the motor 23.
is provided, and the rotating shaft 54 of the rotating filter 51 and the output shaft of the motor 23 are connected via the clutch 64.

Also, is it possible to change the filter cassette at the bottom of the housing 52? At the end on the -70 side, there is a pawl 6 that protrudes downward.
5 is provided.

As the rotary filter 51, in addition to a rotary filter for normal observation in which filters having transmission characteristics as shown in FIG. 9 are arranged, for example, the following rotary filter for special images is prepared. .

One rotating filter includes three filters 51a.

51b and 51c are both 80 as shown in FIG.
A rotating filter that transmits a narrow band centered at 5 nm (hereinafter referred to as an 805 nm single wavelength rotating filter).
It is.

The other rotating filters are three filters 51a.

As shown in FIG. 11, two of 51b and 51c are rotary filters (hereinafter referred to as rotary filters), which are a filter that transmits a narrow band centered at 500 nm and a filter that transmits a narrow band centered at 650 nm. It is called a hemoglobin observation type rotating filter.)

Furthermore, other rotating filters include three filters 51a, 51
The wavelength range that b and 51c transmit is the wavelength where the absorbance of blood changes due to changes in the oxygen saturation of hemoglobin (hereinafter also referred to as S02), and the vicinity of that wavelength, and S0
This is a two-wavelength rotating filter (hereinafter referred to as a S02?IS1 quintillion type rotating filter) that has two wavelengths in which the absorbance of blood changes little due to changes in wavelength. Figure 13 shows 500~
It shows changes in blood absorbance (scattered reflection spectrum) due to changes in S02 around 650 nm.

The transmission wavelength range of each filter of the S02 observation type rotating filter in this band is, for example, 569 nm, 577 nm,
A pair of 585 nm and 585 nm is selected.

Furthermore, S02? The combination of transmission wavelength ranges of each filter of the ISl detection type rotating filter is not limited to that shown in FIG. 13. Figure 12 shows the spectral absorption characteristics of oxyhemoglobin and deoxyhemoglobin. As can be seen from this figure, the combination of the transmission wavelength range of each filter of the S02 observation type rotating filter, that is, the combination of the transmission wavelength range of each filter of the S02 observation type rotating filter, Several combinations of two wavelength ranges with substantially equal absorbance and a wavelength range with a large difference in absorbance between oxyhemoglobin and deoxyhemoglobin can be selected.

Still another rotating filter is as shown in FIG.
Although it is for normal observation, each R, G, and B filter 51a,
This is a rotary filter (hereinafter referred to as a frontage angle changing type rotary filter) in which the frontage angles of 51b and 51c are changed (FIG. 14 shows an example in which they are made smaller).

These various rotary filters 51 are housed in housings 52 of separate filter cassettes 50, respectively.

Next, the configuration of the filter cassette changer 70 will be explained using FIGS. 5 to 8.

As shown in FIG. 5, the filter cassette changer 7
0 includes a cassette unit 71 that can accommodate a plurality of (three shown in the figure) filter cassettes 50. This cassette unit 71 has an optical axis 24
For example, three cassette storage sections 72 are formed that open on the side of the illumination optical path shown by , and each of the cassette storage sections 72 stores the plurality of types of filter cassettes 50 described above. At the bottom of the cassette unit 71, there is an optical axis 24 of the illumination optical path.
A nut 73 is attached which is arranged parallel to the. A pipe screw 76 rotated by a cassette change motor 75 is screwed into the nut 73.

The motor 75 is fixed at a predetermined position so as not to move.

Then, the vibrator screw 76 is driven by the motor 75.
By rotating the cassette unit 71 together with the nut 73, as shown in FIG.
It is designed to be able to move back and forth in a direction parallel to the

As shown in FIG. 8, rails 77 are provided at the upper and lower parts of each cassette storage section 72 of the cassette unit 7-1.
．． 77 is provided, and the filter cassette 50 moves along this rail 77, 77 and is inserted into and removed from the illumination optical path. Further, the filter cassette 50
The pawl 65 projects downward from the rail 77 on the lower side, and the other end of a tension spring 78, one end of which is fixed to the inner part of the cassette storage section 72, is attached to the pawl 65. This spring 78 biases the filter cassette 50 in the direction of storing it in the cassette storage section 72.

Further, as shown in FIG. 7, the cassette unit 71
A long hole 80 that communicates with all the cassette storage sections 72 and is parallel to the optical axis 24 of the illumination optical path is formed in the lower part of the surface on the side opposite to the illumination optical path. This elongated hole 80 has the light IN+24
A bias crew 82 is inserted which is arranged perpendicularly thereto and rotated by a motor 81. As shown in FIG. 8, a nut 83 is screwed into the bias crevice 82 within the cassette unit 71. As shown in FIG.

The rotation of this nut 83 is restricted, and the nut 83 is moved by the rotation of the pipe screw 82 and comes into contact with the pawl 65 of the filter cassette 50. The motor 81 is fixed at a predetermined position so as not to move. Then, by rotating the pipe screw 82 with the motor 81, the nut 8
3, the filter cassette 50 can be moved and inserted into and removed from the illumination optical path. Note that when the filter cassette 50 is moved in the direction of retreating from the illumination optical path, by retracting the nut 83, the filter cassette 50 is retracted by the tensile force of the springs 78.

Next, the operation of the filter cassette changer 70 will be explained.

First, by rotating the motor 75, the cassette unit 71 is moved so that the desired filter cassette 50 is at a position where it can be moved by the nut 83.

Next, by rotating the motor 81, the nut 83 that contacts the pawl 83 of the desired filter cassette 50 is advanced toward the illumination optical path side, and the filter cassette 50 is pushed out. As a result, as shown in FIGS. 5 and 6, the window 52a
.

The filter cassette 50 is arranged at a position where the filter cassette 52b is interposed in the illumination optical path. In this state, the clutch 6 provided on the output shaft of the motor 23 for rotating the rotary filter
4 is connected to the rotating shaft 54 of the rotating filter 51. Incidentally, when connecting the clutch 64 and the rotating shaft 54, the motor 23 may be moved to the filter cassette 50 side, or the clutch 64 and the rotating shaft 54 may be connected using a magnet. You can also do it.

Next, when retracting the filter cassette 50 from the illumination optical path, by rotating the motor 81 and retracting the nut 83, the filter cassette 50 is retracted by the tensile force of the spring 78 and stored in the cassette storage section 72. be done.

As shown in FIG. 1, the light selected by the filter cassette changer 70 and transmitted through the rotary filter 51 of the filter cassette 50 interposed in the illumination optical path is condensed by a condensing lens 88, and is condensed by a light guide 14. The light enters the incident end of the light guide 14, is guided to the tip 9, and is emitted from the tip 9 to illuminate the observation site.

The returned light from the observation site due to the illumination light is imaged by the objective lens system 15 onto the solid-state image sensor 16 and photoelectrically converted. This solid-state image sensor 16 is connected to the video processor 6 via the signal line 26.
A drive pulse is applied from a driver circuit 31 within the memory, and reading and transfer are performed by this drive pulse. The video signal read out from the solid-state image sensor 16 is input to a preamplifier 32 provided within the video processor 6 or within the electronic endoscope 1 via the signal line 27.

The video signal amplified by the preamplifier 32 is input to the process circuit 33, where it is subjected to signal processing such as γ correction, why, and doparance, and then processed by the A/D converter 34.
It is now converted to a digital signal. This digital video signal is sent to three memories (1) 36a corresponding to each color, for example, red (R), green (G), and blue (B), by the select circuit 35. MeT: 1) (3) It is designed to be selectively stored in 36C. The memory (1) 36a, Me-EIJ (2
) 36b, 1. The memory (3) 36c is simultaneously read out, converted to an analog signal by the D/A converter 37, and outputted as R, G, and B color signals, and input to the encoder 38, from which the NTS
It is designed to be output as a C composite signal.

The R, G, and B color signals or the NTSC composite signal are input to the color monitor 7, and the observed region is displayed in color by the color monitor 7.

The timing generator 42 also controls the motor driver 25 . Driver circuit 31. Select circuit 35
The synchronization between each circuit is maintained.

In this embodiment, when the filter cassette change <p-70 is controlled by the switching circuit 43 and the filter cassette 50 containing the rotary filter 51 for normal observation is inserted in the illumination optical path, the light emitted from the lamp 21 is The light passes through a rotating filter 5 for normal observation in this filter cassette 50.
Filters 51a, 51b, 5 that transmit R, G, and B of 1
1c, and is divided into R, G, and B wavelength regions in time series. And this R, G, B light,
The light is transmitted to the tip 9 via the light guide 14 and irradiated onto the subject. The returned light from the object due to the R2G, B field sequential illumination light in the visible band is imaged by the objective lens system 15 onto the solid-state image sensor 16, and the image of the object is imaged by the solid-state image sensor 16. Therefore,
A normal visible image is displayed in color on the monitor 7.

On the other hand, the switching circuit 43 controls the filter cassette changer 70 to change the rotation filter 5 for special images.
When a filter cassette 50 containing a rotary filter 51 is inserted into the illumination optical path, the following images can be obtained depending on the type of rotary filter 51.

First, if you select an 805nm single wavelength rotating filter,
At all timings of R, G, and B, a narrow band of light centered at 805 nm passes through this rotating filter, and the 805 nm
An image of the subject in a narrow band centered on is obtained.

By the way, ICG (rndoc
Blood contaminated with yan i negreen) is 80
It has maximum absorption at 5 nm. Therefore, for example, the ICG is mixed into the blood by intravenous injection, and the 805 nm
By observing the image of the subject in a narrow band centered on , it becomes possible to observe the cancer in ①b and the running state of submucosal blood vessels.

Furthermore, when the hemoglobin amount observation type rotating filter is selected, an image of the subject in a narrow band centered at 500 nm and an image of the subject in a narrow band centered at 650 nm are obtained. As shown in FIG. 13, there is a large difference in the absorbance of blood near 500 nm and near 650 nm.

Therefore, from the difference in absorbance in these two wavelength ranges,
Changes in the amount of hemoglobin can be observed.

Furthermore, when the So 2 observation type rotating filter is selected, images in each wavelength range of 569 nm, 577 nm, and 585 nm are obtained. As shown in Figure 13, 569nm, 5
85 nm is a wavelength at which the absorbance of blood hardly changes due to a change in SO2, and 577 nm is a wavelength at which the absorbance of blood changes due to a change in SO2. Therefore, changes in SO2 can be observed using images in these three wavelength ranges.

Also, if you select a frontage angle variable rotary filter with a small opening angle, R, G.

Images with less blur can be obtained for each of B.

Note that the color shift between R, G, and 8 can be corrected.

In addition, when any filter cassette 50 is not interposed in the illumination optical path, an endoscope that can output white light and that allows naked eye observation such as a fiberscope or an endoscope that has a simultaneous imaging means can be used. Matching illumination can also be provided for mirrors.

As described above, according to the present embodiment, by switching the filter cassettes 50 interposed in the illumination optical path using the filter cassette changer 70, the combination of field-sequential illumination light can be selected from among a plurality of combinations. Can be done. Therefore, it is possible to supply various combinations of field-sequential illumination light having different wavelength ranges depending on the observation purpose of the observation region A5 and the like.

By using these various combinations of sequential illumination lights, various images such as a normal image, an image that does not show cancer or the running state of blood vessels, an image that shows changes in the amount of hemoglobin, and an image that shows changes in the oxygen saturation of hemoglobin are generated. It becomes possible to obtain an image with less blur for each of R, G, and B images.

In addition, each filter 51a, 51b, 5 of the rotary filter 51
When changing the frontage angle of 1c, the frontage angles of the R, G, and B filters may not be equal, but may be different, for example, as shown in FIG. 15, in order to maintain white balance. In the example shown in this figure, the aperture angle of the filter 51a that transmits R is smaller than that of the filter 51b that transmits G and the filter 51c that transmits B.

By the way, aluminum or the like is used for the frame 90 of the rotary filter 51, and each filter 51a.

Although glass or the like is used for 51b and 51c, the frame 90
When the specific gravity of each filter 51a, 51b, 51c is different, as shown in FIG.
, 51c have different frontage angles, the rotary filter 51 will become unbalanced. In this way, if the rotary filter 51 is driven with poor balance, it may not be stable and the feedback control may not work.

Therefore, in the modification shown in FIG. 15, the rotary filter 51
Balance is maintained by attaching a balancer 91 to a part of the frame 90. The position and weight of the balancer 91 are set according to the position of the center of gravity of the rotary filter 51 before the balancer 91 is attached.

In the example shown in FIG. 15, the specific gravity of the frame 90 is
Since the specific gravity is larger than that of 18251b and 51c, the center of gravity is shifted toward the R transmission filter 51a from the center of rotation, so the balancer 91 is attached to the opposite side of the filter 51a. By balancing the rotary filter 51 in this way, the rotation of the rotary filter 51 starts smoothly and becomes stable.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, the rotating filter 51 may include filters that transmit three different wavelength regions in the infrared band and ultraviolet band as the filters 51a, 51b, and 51c. It's okay. Such a rotating filter makes it possible to observe a subject image in the infrared band or ultraviolet band. Furthermore, instead of a rotating filter, a filter cassette containing a filter that always transmits a predetermined amount of light may be provided.

Further, the mechanism for exchanging filter cassettes is not limited to that shown in the embodiment, and the number of exchangeable filter cassettes is also arbitrary. Further, the rotary filter may be made replaceable without being built into the filter cassette.

In addition, in each filter cassette, along with a rotating filter,
A motor and a rotary encoder may also be provided.

Note that the present invention is not limited to an endoscope that receives reflected light from an object to be observed, but can also be applied to an endoscope that receives and observes light that has passed through an object to be observed.

Furthermore, the present invention is not limited to electronic endoscopes having a solid-state imaging probe at the distal end of the insertion section, but can also be applied to the eyepiece of an endoscope capable of visual observation such as a fiberscope, or to the eyepiece. It can also be applied to an endoscope device that is used by connecting a television camera in place of the above.

[Effects of the Invention] As explained above, according to the present invention, by switching the filters using the filter switching means, it is possible to supply various types of illumination light including field-sequential light that can form a color image. or! This has the effect of making it possible to obtain various images with different observation wavelength ranges depending on the purpose of the BJ dormitory.

[Brief explanation of the drawing]

Figures 1 to 15 relate to one embodiment of the present invention;
The figure is a block diagram showing the configuration of the endoscope 11 device, FIG. 2 is a side view showing the entire endoscope device, FIG. 5 is a perspective view of the filter cassette changer, FIG. 6 is a plan view of the filter cassette changer, FIG. 7 is a perspective view showing the rear side of the filter cassette changer, and FIG. is a sectional view taken along the line B-B' in Fig. 6, Fig. 9 is an explanatory diagram showing the transmission characteristics of each filter of the rotating filter for normal observation, and Figs. 10 and 11 are each of the rotating filters for special images. FIGS. 12 and 13 are explanatory diagrams showing the transmission characteristics of the filter.
FIG. 4 is a sectional view of a filter cassette showing another example of a rotating filter for normal observation, and FIG. 15 is a sectional view of a filter cassette showing a rotating filter in a modification of this embodiment. 1...Electronic endoscope 6...Video block length 20...Light source device 21...Lamp 50...
・Filter cassette 51...Rotary filter 70...Filter force set 1 to changer Fig. 3
Figure 4 Figure 7 Figure 7o Figure 8 bl b and 15 eljl Figure 9 Figure 10 Figure 11: Wavelength (nm) Figure 13 Wavelength (nm) Figure 14 Figure 15

Claims (1)

[Claims] A light source device for an endoscope capable of supplying illumination light suitable for an endoscope equipped with a field-sequential imaging means, which includes a light source and an illumination optical path of the light source that is removably inserted into the illumination optical path of the light source, and at least the light source. a plurality of types of filters including a filter that can chronologically separate light emitted from the light into three wavelength regions capable of forming a color image; and one of the plurality of types of filters is selectively placed in an illumination optical path. 1. A light source device for an endoscope, comprising an insertable filter switching means.