JPS61176911A - Diaphragm device of light source device for endoscope - Google Patents

Abstract

PURPOSE:To improve the responding speed of an endoscope without changing the light distribution characteristic and spectral characteristic of lighting lights, by providing a liquid crystal board divided by numerous electrodes on a concave mirror which changes the lights of a light source to parallel lights. CONSTITUTION:Lights of the light source 12 of a lighting device 11 are changed to parallel lights by means of a concave mirror 13 and an object is irradiated by the parallel lights passed through a light guide 10. A liquid crystal board 16 equipped with transparent electrodes 16a and 16c which are closely concentrically arranged is glued to the surface of the concave mirror 13. A light adjusting signal from an image pickup element 4 is inputted in the liquid crystal board 16 through the objective lens 3 of an endoscope inserting section and a voltage corresponding to the signal is selectively applied across the electrode 16a. Thus a nonreflecting section 16b is formed. Therefore, the optimum lighting intensity to the object is automatically adjusted and the whole mirror 13 is uniformly changed. Accordingly, the lighting light quantity can be adjusted with excellent responsiveness without changing the light distribution characteristic and spectral characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an aperture device for an endoscope light source device suitable for varying the amount of light irradiated onto a subject.

[Technical Background of the Invention and Problems Therewith] In recent years, technology has been realized for endoscopes as well, in which a solid-state image sensor is used to image a subject on a display device such as a cathode ray tube.

Electronic endoscopes using solid-state imaging devices are easier to record images than those that form optical images on image kite fibers, and will continue to grow as highly integrated technology advances. It has the advantage that it can be made smaller.

However, when using the above-mentioned solid-state image sensor, if the amount of light incident on the photodetector on the imaging surface is too large, excessive charge leaks to the surrounding area, causing blurring and pluming on the playback screen. There is a problem that not only cannot the image be faithfully reproduced, but also that imaging is impossible until the normal state is restored.

A conventional example of a diaphragm device for controlling the intensity of illumination light on the light source device side so as to prevent the blooming phenomenon described above is shown in FIG. 3.

That is, light from a light source 30 such as a discharge lamp is passed through a concave mirror 31.
In the optical system, a convex lens 32 reflects the collimated light into parallel light, and irradiates the incident end of the light guide fiber 10 serving as an illumination light transmitting means on the optical path between the convex lens 32 and the light guide fiber 10. As shown in FIG. 4, a diaphragm 33 in the shape of a fan-shaped notch is provided at the center of the disk and a part of the disk, and by moving this diaphragm 33 (downward in FIG. 4), The amount of light incident on the light guide fiber 10 is varied by blocking a part of the light beam according to the amount of movement, and the amount of illumination light emitted from the other end of the light guide fiber 10 is adjusted.

However, in this conventional example, when the luminous flux is narrowed down by the aperture 33, this luminous flux is blocked from the periphery.
Since the light distribution angle distribution of the illumination light emitted from the tip surface of the light guide fiber 10 toward the subject changes, the light distribution characteristics change, and the illumination intensity of each part within the field of view changes unevenly. This will result in Furthermore, in this shape,
This has the drawback that the response speed of the aperture operation is slow, making it unsuitable for automatic light control.

Further, the maximum incident angle at which light can be transmitted normally depends on the wavelength of the light guide 10. In other words, the numerical aperture differs depending on the wavelength. For this reason, when the focused light is irradiated onto the incident end of the light guide 10 as in the conventional example, if the light beam in the middle is narrowed down by the diaphragm 33, the light is blocked from the periphery side where the wavelength dependence is large. However, there is a drawback that the spectral characteristics of the illumination light irradiated from the output end side of the light guide 10 to the subject side also change (depending on the aperture amount).

Further, even if the aperture 33 is disposed in the parallel light portion, there is a drawback that the light distribution characteristics change.

On the other hand, it is possible to prevent the blooming phenomenon by controlling the voltage applied to the light source 30, but the change in voltage also changes the emission spectrum distribution of the light source 30, which complicates image processing.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and is directed to the light distribution characteristics of illumination light emitted to the subject side.

It is an object of the present invention to provide a diaphragm device for an endoscope light source device that does not change spectral characteristics and has a good response speed.

[Summary of the Invention] The aperture device according to the present invention includes a concave mirror that converts a light beam from a light source into parallel light, and a convex lens that focuses the parallel light onto a light guide provided inside the insertion section of an endoscope. In the light source device for endoscopy, a liquid crystal plate composed of liquid crystal and a large number of segmented electrodes is provided on the concave mirror, and when a voltage is applied to each electrode, The liquid crystal forms a non-reflective surface on the concave mirror to adjust the amount of reflection of the concave mirror.

[Embodiments of the invention] The present invention will be specifically described below with reference to the drawings.

1 and 2 relate to one embodiment of the present invention, FIG. 1 is a schematic diagram of the entire endoscope device, and FIG. FIG. 3 is a front view showing a liquid crystal body in different states.

In these figures, numeral 1 is an endoscope device, and 2 is an elongated insertion section connected to this endoscope device 1. An objective lens 3 for imaging is disposed on the distal end side of the insertion section 2, and the imaging surface of a solid-state imaging device 4 such as a COD (1! cargo coupling device) is located at the imaging position of the objective lens 3. It is arranged. On this imaging surface, light receiving elements each having a photoelectric conversion function are regularly arranged. Immediately in front of this imaging surface, a mosaic-arranged three primary color film 4A is attached that transmits only light of each wavelength of the three primary colors.

By the clock signal applied to the solid-state Il image element 4,
The signals that have passed through the transmission filter of the three primary color film 4A are sequentially output. - This signal is amplified by a preamplifier (preamplifier) 5 with a low noise figure, and sent via a signal cable 6 to a video processing section 7. Each color signal R, G, B is separated and taken in by the sample and hold circuit inside, and after each is amplified, a synchronization signal is superimposed,
The image is input to a color monitor 8, and an Ii image plane is formed so that it can be displayed as a color image.

A light distribution lens 9 is disposed in the insertion section 2 so as to be adjacent to the objective lens 3, and a flexible fiber bundle is arranged so that its output end faces the inner surface of the light distribution lens 9. The configured light guide 10 is inserted.

The rear end of the light guide 10 on the proximal side is removably attached to the light source device 11 via the connector IOA.The light source device 11 is provided with a concave mirror 13.
Light 8!1 from a discharge lamp or the like is placed at the focal point of this concave mirror 13.
2 are arranged. This concave l! Reference numeral 13 reflects the diverging light from the light source 12 into parallel light, and a condenser lens 14 is provided in the direction of reflection of this concave mirror 13. The parallel light is condensed onto the rear end of the ride guide 10 by the condenser lens 14. Further, a light shielding plate 15 is interposed between the mold 11112 and the condenser lens 14. This light shielding plate 15 is provided to prevent the diverging light from the light source 12 from directly entering the light guide.

Further, a liquid crystal plate 16 is attached to the surface of the concave mirror 13. This liquid crystal plate 16 includes a transparent electrode 16c attached to the entire surface of the concave mirror 13, another transparent electrode 16a provided opposite to this transparent electrode 16c, and both electrodes 168.16.
Furthermore, as shown in FIG. 2, a large number of transparent electrodes 16a are divided into concentric circles.

This liquid crystal plate 16 is controlled based on a dimming signal input to a decoder 27.

The dimming signal input to this decoder 27 is each color signal R, G output from the video processing section 7.

It is generated by roughly integrating the luminance signal formed by adding B in an adder 25 in an integrating circuit 26.

The adder 25 maintains color balance and outputs a dimming signal, and the integrating circuit 26 corresponds to the light receiving period of the signal output from each light receiving element. The integration time constant is set to be approximately one frame or more, and the number of high-level digital voltages corresponding to the output level of this integrated signal is applied to each transparent electrode 1 of the liquid crystal plate 16.
6a is selectively applied.

For example, if the number of high level electrodes is 3, the transparent electrode 16
5th and 10th from the outside as shown in Figure 2(a).
A voltage is applied to every multiple of 5, such as the 1511th and 1511th, and as the number of high-level lines increases, a voltage is applied to the transparent electrode 16a every multiple of 4 from the outside as shown in FIG. 2(b). be done. The liquid crystal 16 (j) corresponding to the transparent electrode 16a to which a voltage is applied has its transmission characteristics changed to form a non-reflective portion 16b.The density of the non-reflective portion 16b formed on the concave surface 113 is uniform throughout. It is increased or decreased depending on the level of the dimming signal.

According to the embodiment configured in this way, when the insertion section 2 is brought close to an object such as an affected area to observe the object in detail, or moved away from it to grasp the overall characteristics, the illumination is adjusted according to the distance. The amount of light incident from the subject changes, and therefore the optimal illumination intensity changes. Signals corresponding to each pixel output from the solid-state image sensor 4 in this state are taken into the video processing section 7 and displayed in color on the color monitor 8. Each color signal R9G, B separated along with this
is added by the adder 25 and further integrated by the integrating circuit 26, and is formed on the concave surface #i13 according to the level of the dimming signal that reflects the amount of incident light that is reflected by the subject and incident during one frame period. The density of the non-reflective portions 16b is varied. For example, if the amount of incident light is too large, the level of the dimming signal will increase and the density of the non-reflective portions 16b will increase, and if the level of the dimming signal becomes small, the density will become coarse.

The amount of reflected light of the light beam incident on this non-reflection portion 16b is significantly attenuated. Therefore, when the light beam emitted from the light source 12 is reflected by the concave mirror 13, it is made into parallel light, and at the same time, the illumination intensity is automatically adjusted to a level suitable for imaging.

As a result, the operator is freed from the hassle of having to adjust the light each time depending on the object distance or the reflection intensity of the object, and can concentrate on diagnosis or treatment using the treatment instrument. This allows accurate diagnosis and appropriate treatment.

Furthermore, according to this embodiment, the amount of light reflected from the concave surface [13] can be varied by applying a voltage to a predetermined transparent electrode 16a, resulting in good responsiveness. Furthermore, since the density of the non-reflective portions 16b changes uniformly over the entire concave mirror 13, the light distribution characteristics and spectral characteristics in each state do not change.
It is possible to realize an illumination means for color imaging with good color reproducibility even in any aperture state. Therefore, even in the case of an imaging means using the solid-state imaging device 4, color imaging and color display without color shift can be performed.

The aperture device described above is used for a light source device for capturing color images using a white light source, but the aperture device of the present invention can also be applied to a light source device forming a color plane sequential type illumination means.

Further, the transparent electrodes 16a may be divided into a matrix, radially from the center, or randomly arranged.

Further, the liquid crystal plate may be constructed by assembling a plurality of liquid crystal cells.

[Effects of the Invention] As described above, according to the present invention, a liquid crystal plate composed of a liquid crystal and a large number of segmented electrodes is disposed on a concave mirror that converts a light beam from a light source into parallel light. Since the reflection device from the concave mirror is controlled by selectively applying a voltage to each electrode, the illumination light can be adjusted without changing the light distribution characteristics and spectral characteristics.

Furthermore, since the amount of light is controlled by liquid crystal, the structure is simpler and the response is better than conventional mechanical means.

[Brief explanation of the drawing]

1 and 2 relate to one embodiment of the present invention, FIG. 1 is a schematic diagram of the entire endoscope device, and FIG. FIG. 3 is a schematic diagram of a conventional aperture device, and FIG. 4 is a front view of the aperture. 2...Light source 10...Light guide 11...
・Light source device 12...Light source 13...Concave mirror
14... Convex lens 16... Liquid crystal plate 16a...
・Electrode 16d...liquid crystal

Claims (1)

[Claims] A light source device for an endoscope includes a concave mirror that converts a light beam from a light source into parallel light, and a convex lens that focuses the parallel light on a light guide provided in an insertion section of an endoscope. A diaphragm device for a light source device for an endoscope, characterized in that the diaphragm device is provided with a liquid crystal plate composed of a liquid crystal and a large number of segmented electrodes.