JPH0336326Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a field-sequential color type endoscope device equipped with a solid-state image sensor within a rigid distal end portion.

BACKGROUND OF THE INVENTION In recent years, various endoscopes using solid-state imaging devices such as charge-coupled devices as imaging means have been proposed.

An endoscope using the solid-state imaging device described above can prevent image quality from deteriorating due to fiber breakage in an endoscope using an image guide formed of an optical fiber bundle (fiber bundle).
It has the advantage of making it easier to record images, etc., and is expected to become more compact and have improved resolution as integration technology progresses, so it is expected to be widely used in the future.

These endoscopes are equipped with a color-encoding filter in front of the solid-state image sensor to capture a color image of an object illuminated with white light. ), or a field-sequential method in which colored light such as cyan (C _y ), magenta (M _g ), and yellow (Y _e ) is sequentially irradiated onto an object to capture color images is currently known.

Incidentally, as the solid-state image sensor, a charge-coupled device (hereinafter referred to as CCD), which has two functions of photoelectric conversion and scanning, is widely used. this
CCDs are broadly classified into frame transfer type, line transfer type, and vertical interline type.

The above-mentioned frame transfer type CCD first performs photoelectric conversion and signal accumulation in the photosensitive section during a certain field period, and then transfers these charges in parallel to the storage section during a short vertical blanking period. The electric charges in the light-shielded storage section are transferred by a horizontal register in a standard scanning method during a horizontal blanking period in an amount equivalent to one scanning line, and signals are sequentially read out.

The above-mentioned line transfer type CCD is provided with a vertical output register, and reads the signal by switching the transfer signal for each row.

In addition, the vertical interline transfer method CCD mentioned above is
The photosensitive section and the transfer section are arranged as a pair in a line in the vertical direction.

Of the above, frame transfer type and line transfer type CCDs have a structure in which charge is transferred through a photosensitive part, so when the charge is transferred for signal readout, the incident light may be received and the difference may occur. There was a drawback that a smear phenomenon occurred in which signal charges corresponding to pixels were superimposed.

Purpose In view of the above points, the present invention has been developed to reduce the loss of light amount and prevent the occurrence of smear phenomenon for optical transmission bodies of different diameters in an endoscope that uses a line transfer type solid-state image sensor. The objective is to provide an endoscopic device with

Overview This purpose is to illuminate the object to be observed and the line transfer type solid-state image sensor, which is installed in the rigid tip of the endoscope insertion section and which receives an optical image of the object to be observed and converts it into an electrical signal. between the light source and the input end surface of the light transmission body; A light-blocking region that is disposed in the light source and blocks light in the wavelength range used for observation out of the light from the light source and three or more types of transmitting regions having different spectral transmittance characteristics for light in the wavelength range are arranged in the same circle. By rotating rotating filters provided alternately on the circumference, the three or more colored lights sequentially illuminate the object to be observed with a shading period, thereby being accumulated in the solid-state image sensor. In an endoscope apparatus, the charge is read out during the light-shielding period, converted into an electrical signal, and a color display of the object to be observed is performed based on the electrical signal,
A diaphragm provided at both ends of the transmission area and closer to the light source than the optical transmission body maintains a constant light shielding area passage time for optical transmission bodies of different diameters when the rotary filter is rotating. This problem is solved by an endoscope device characterized in that it is formed into a shape.

Further, according to the present invention, in the endoscope device, the boundary in the rotational direction of the transmitting region of the rotary filter has a center on the same circumference and has a maximum diameter of the light transmitting body having different diameters. It protrudes outward on the circumference beyond the enclosing circular arc, and the shape of the aperture is formed to correspond to the boundary.

Embodiments The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is a block diagram of the configuration of an endoscope apparatus according to the present invention, and FIG. 2 is a timing chart illustrating its operation. Here, the three or more types of colored lights may be four colored lights of red, green, blue, and yellow, or complementary colored lights such as cyan, yellow, and magenta. In the following explanation, the case of three-color light of red, green, and blue will be explained.

In FIG. 1, reference numeral 1 indicates the distal end component of the endoscope insertion section, and the objective lens 2 is attached to the distal end.
and an illumination lens 3 are arranged in parallel, and a line transfer type solid-state image sensor 4 is installed behind the objective lens 2. The received optical image is converted into a video signal V by a drive circuit 5, and this video signal is V is sent to the next stage circuit via a preamplifier 6. A light guide 7 made of an optical fiber bundle or the like is disposed behind the illumination lens 3, and illumination light is irradiated onto the rear end surface with a rotary filter 8 interposed therebetween. Illumination light is irradiated from a light source lamp 9 through a lens 10 onto a rotary filter 8, and this illumination light passes through R, G, and B filters that are arranged alternately at an appropriate shading period on the filter 8, and then passes through the light guide. It is incident on the end face of 7. A read pulse detection section 11 and a start pulse detection section 12 are fixedly installed around the outside of the rotary filter 8, and the rotary filter 8 is configured to rotate at a predetermined speed about a rotation shaft. The rotating shaft is connected to a motor 14 via a transmission system 13, and a rotation detecting section 1 provided on the motor 14
The motor drive section 16 is controlled by the signal from the motor 5, so that the rotational speed of the motor 14 is kept constant. On the other hand, the video signal V from the preamplifier 6 is further amplified through the amplifier 17 and then input to the multiplexer section 18. The multiplexer section 18 consists of three switches SW1, SW2, and SW3 corresponding to the input R, G, and B signals, and these switches receive gate signals SG ₁ ,
Each frame memory 20 for R, G, and B is sequentially switched at a predetermined frame period in SG ₂ and SG ₃ .
21 and 22, and from these frame memories, the R, G, and B signals are sent to the color TV monitor 23.
It is now displayed in color. In the above, the read pulse detection unit 11 detects the end positions of the R, G, and B filters arranged in the rotating direction of the rotary filter 8, and uses the detection pulse (read pulse) P _r and the oscillator 24 to The read gate signal G _r is created using the signal. This readout gate signal G _r is a signal for reading out the video signal accumulated in the solid-state image sensor 4 during a period corresponding to the period in which the R, G, and B lights are not irradiated, and is input to the AND circuit 26 together with the signal from the oscillator 24. The read clock signal CK _r is generated by the driver circuit 5.
is driven to change the accumulated charge of the solid-state image sensor 4 to R, G,
The readout gate signal _Gr is converted into a video signal V for each B, while the readout gate signal Gr is used together with the detection pulse (start pulse) _Ps from the start pulse detection section 12 (which detects one rotation of the rotary filter 8) to generate a gate signal for the multiplexer. The gate signals SG ₁ , SG 2 , and SG 3 are inputted to the section 19 and the gate signals SG 1 , SG ₂ , and SG ₃ for each of the switches are generated, and the multiplexer section 18 is switched to input the video signals for R, G, and B to each frame memory 20 , 21 , and 22 . is configured to do so.

In such a configuration, as shown in FIG. 2, one start pulse _Ps is output every time the rotary filter 8 rotates once and is sent to the multiplexer gate signal generator 19, and every time the rotary filter 8 rotates once, a start pulse Ps is outputted and sent to the multiplexer gate signal generator 19. R,G,
Three read pulses P _r corresponding to the B filters are output and sent to the read gate signal generator 25 . The read gate signal generator 25 uses the signal from the oscillator 24 to generate a read gate signal G _r having the same period as the read pulse P _r and having a width corresponding to the period in which the R, G, and B lights are not irradiated. Based on the period of this read gate signal G _r , the read clock signal CK _r
and switch gate signals SG ₁ , SG ₂ , and SG ₃ are created to obtain R, G, and B signals necessary for color display. In the readout gate signal G _r shown in the figure, the shaded areas are the R, G, and B video signal readout periods, and the low level period before each shaded area is the period in which the solid-state image sensor 4 is irradiated with R, G, and B light. This is the period during which R, G, and B signal charges are accumulated.
Therefore, the R, G, B frame memories 20, 2
Gate signals for switches 1 and 22 SG ₁ , SG ₂ ,
_SG3 is designed to be a gate signal corresponding to the R, G, and B video signal readout periods, respectively.

FIG. 3 is a diagram showing details of the light guide 7, rotary filter 8, light source lamp 9, and lens 10 in FIG. After that, the light beam is turned into a parallel light beam again by the lens group 10b, and is then condensed by the lens group 10c via the rotating filter 8 onto the incident end surface of the light guide 7, and enters the light guide 7. Note that the rotating filter 8 is connected to the rotating shaft 27.
At the same time, two apertures 28 are arranged on both sides of the rotary filter 8, that is, between the lens groups 10b and 10c.

Here, the rotary filter 8 is formed as shown in FIG. 4, for example. That is, the rotary filter 8 is provided on the same circumference of the endoscope 1 so as to shield the solid-state image sensor 4 from light while the solid-state image sensor 4 of the endoscope 1 reads image information (charge of each pixel) during rotation. It is provided with three light-shielding regions 8b (angle b), and further provided with transmitting regions 8b, 8c, and 8d (hereinafter referred to as openings) that transmit blue, green, and red color light, respectively, on the same circumference. There is. This opening 8b,
The shapes of 8c and 8d may have linear boundaries in the circumferential direction, as shown by solid lines in FIG. 4, or their outer and inner edges may be shaded areas, as shown by dotted lines in FIG. Even if the rotary filter 8 has an arc shape (for example, radius D/2) that extends within the rotary filter 8a,
Since the light beam attempting to pass through the openings 8b, 8c, and 8d has a circular shape with a diameter D as shown by the chain line 29, it does not affect the readout of the solid-state image sensor 4.
increases the amount of light that passes through. In this case, the shape of the diaphragm 28 may be a circle having approximately the same diameter as the light beam that is about to pass through the rotary filter 8, or the diaphragm 28 may be omitted.

By the way, if the diameter of the light beam trying to pass through the rotary filter 8 is D', which is larger than D, the fourth
If the light-shielding region 8a is formed during the readout period of the solid-state image sensor 4 as in the case shown in the figure, the central angle of the opening 8c' becomes smaller from e to e' as shown in FIG. The amount of light transmitted through 8b', 8c', and 8d' is also reduced compared to the case shown in FIG.
In addition, the opening indicated by the dotted line in FIG.
An aperture with a border indicated by a dotted line in the figure is shown for comparison. To this end, according to another feature of the invention, the rotary filter is constructed as shown in FIG. That is, in FIG. 6, the rotary filter 30 has openings 30a, 30b, 30
The circumferential boundary of c is each opening 8b', 8b' in FIG.
It is formed into a shape cut by a straight line corresponding to the radius touching the arcuate boundary of radius D of each opening 8b, 8c, 8d in Fig. 4 from the arcuate boundary of radius D' in the circumferential direction of 8c', 8d'. The aperture 28a of the diaphragm 28 has a shape that extends from a circle with a diameter D' as shown in FIG. ) is formed in a shape cut by a straight line corresponding to the radius tangent to ). In this way, it is possible to increase the diameter of the light beam passing through the rotary filter from D to D' without changing the central angles b and e of the light shielding area and the aperture, thereby increasing the amount of light incident on the solid-state image sensor 4.
Incidentally, the light beam attempting to pass through the notch shown by the chain line in FIG. 7 is blocked by the diaphragm 28, but since most of this light beam enters the periphery of the light guide 7, a thin light guide is used. In the case of a thick light guide, the part within the diameter D will be incident on the entire surface of the incident end face of the light guide, so no loss will occur, and in the case of a thick light guide, the peripheral part outside the diameter D excluding the notch will also be included in the luminous flux. , the amount of light passing through the rotating filter increases.

FIG. 8 shows another embodiment of the rotary filter, in which the rotary filter 31 has a sixth
Openings 30a, 30b of the rotary filter 30 in the figure,
30c has a shape in which an arcuate portion of diameter D' at the boundary in the circumferential direction is replaced by an inscribed straight line portion. As shown in FIG. 9, the diaphragm 28 used in conjunction with the rotary filter 31 has an aperture 28a' that forms an arcuate portion of diameter D' of the diaphragm aperture 28a in FIG. It is formed by replacing it with an inscribed straight line part. The rotary filter 31 and the diaphragm formed in this manner provide the same effect as in the embodiments of FIGS. 6 and 7.

FIG. 10 shows yet another embodiment of the rotary filter, in which the rotary filter 32 has a circular arc shape with a circumferential boundary of the openings 32a, 32b, and 32c having a diameter D and a central angle e. a straight line part in the radial direction forming a central angle h (h>e) that is continuous with this arc-shaped part, and further a diameter that is continuous with this straight part and is concentric with the arc-shaped part having the diameter D.
It is formed from the arc-shaped portion of D′. On the other hand, the aperture 28' of the diaphragm 28 is similarly formed as shown in FIG. Therefore, according to this configuration, the opening 3 of the portion shown by the dotted line (corresponding to the opening shown by the dotted line in FIG. 4)
The portions extending outward from 2a, 32b, and 32c are smaller than in the case of FIG. 6, thus increasing the amount of light passing when using a small diameter light guide.

FIG. 12 shows another embodiment of a rotary filter, in which the rotary filter 33 has an opening 33
The boundaries in the circumferential direction of a, 33b, and 33c are made of liquid crystal or the like, and the light-shielding range thereof can be changed by appropriate control thereof. In the drawing, the entire liquid crystal is controlled to be in a light-blocking state as indicated by hatching, corresponding to the light guide with the largest diameter. Thus, for light guides of various diameters, a rotating filter with an opening shown in dotted lines in FIG. 4 is used, in which case no diaphragm is required.

Note that if the radius of the circle passing through the center of the opening of each rotary filter is small, the angle b will become large in order to obtain a predetermined light-shielding period, and therefore, e will become small.
r must substantially satisfy the condition r>1.8D'...(1). If r exceeds this lower limit, the loss of the amount of light will increase, causing practical difficulties.

Each opening of the rotary filter can also be formed by colored glass or by an interference filter.
Further, the infrared cut filter 34 (FIG. 3) may be an interference filter or an infrared absorption filter, or may be an infrared absorption glass coated with an infrared cut coating.

Furthermore, although each of the above embodiments has been described using a light guide, it is needless to say that the light guide is not limited to this, and other light transmitting bodies such as a tube with a plated inner surface may be used.

Effects of the Invention As described above, according to the present invention, a predetermined light-shielding period is maintained for image reading of a solid-state image sensor for various optical transmission bodies from small diameters to large diameters, and the aperture of the rotating filter is maintained. In this way, the present endoscope device can be applied to various endoscopes having light transmitting bodies of various diameters, and the loss of light amount is small and smear phenomenon does not occur. Effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the endoscope device according to the present invention, Fig. 2 is a timing chart showing the operation of the device in Fig. 1, and Fig. 3 is a partially enlarged view showing the main parts of the device in Fig. 1. Figure, Figure 4, Figure 5, Figure 6,
8, 10 and 12 are front views showing embodiments of the rotary filter, FIGS. 7, 9 and 1.
FIG. 1 is a front view showing an embodiment of the aperture of the diaphragm. DESCRIPTION OF SYMBOLS 1... Tip component of endoscope insertion part, 2... Objective lens, 3... Illumination lens, 4... Solid-state image sensor, 5... Drive circuit, 6... Preamplifier, 7
...Light guide, 8, 30, 31, 32, 33
... Rotating filter, 9 ... Light source lamp, 10 ...
Lens, 11...Read pulse detection section, 12...Start pulse detection section, 13...Transmission system, 14...
Motor, 15...Rotation detection unit, 16...Motor drive unit, 17...Amplifier, 18...Multiplexer unit, 19...Gate signal generation unit, 20, 21, 2
2... Frame memory, 23... Color TV monitor, 24... Oscillator, 25... Read gate signal generator, 26... AND circuit, 27... Rotating shaft, 2
8... Aperture, 29... Luminous flux.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A line transfer type solid-state imaging device that is disposed in the rigid distal end of the endoscope insertion section and that receives an optical image of an object to be observed and converts it into an electrical signal; An endoscope comprising: a light transmitting body that receives light from a light source at an incident end face to illuminate an observation object and guides the light to an output end face disposed on the rigid distal end; a light-shielding region disposed between the incident end face and the light in the wavelength range used for observation among the light from the light source; and three or more types of light transmitting elements having different spectral transmittance characteristics for the light in the wavelength range. By rotating a rotary filter having regions alternately on the same circumference, the three or more colored lights sequentially illuminate the object to be observed with a shading period, and thereby the solid-state imaging In the endoscope apparatus, the charge accumulated in the element is read out during the light-shielding period and converted into an electric signal, and the object to be observed is displayed in color based on the electric signal, the endoscope apparatus comprising the following steps: A diaphragm provided closer to the light source than the light transmitting body is formed in a shape such that a constant light shielding area passage time is maintained for light transmitting bodies of different diameters when the rotary filter is rotating. An endoscope device characterized by: (2) The boundary in the rotational direction of the transmission region of the rotary filter is located on the circumference beyond an arc having a center on the same circumference and including the largest diameter of the light transmission bodies having different diameters. The endoscope device according to claim (1) of the registered utility model, wherein the endoscope device protrudes outward, and the shape of the diaphragm is formed corresponding to the boundary.