JPH0413111A - Filter for video superposing device - Google Patents

Abstract

PURPOSE:To make a contrast to a visual image higher and to enhance the efficiency without lowering the brightness of a displayed video by making 1st and 2nd refracting means opposite to each other by interposing a refractive layer between them, and arranging before the displayed video is superposed in a collimated beam of light. CONSTITUTION:A filter 4 is formed by making the 1st and 2nd refracting means 11 and 12 having the same refractive index opposite to each other and by inter posing the refractive layer 14 whose refractive index is different from that of the refracting means 11 and 12 on the front side of the opposite faces gammaand beta, or on a prescribed position, and also it is arranged before the displayed video is superposed in the collimated beam of light. Then, a luminous flux arriving at a dark area in a visual field is removed by performing the angular separation of the group of the luminous flux which makes a prescribed angle with an optical axis in the part of the collimated beam of light in an optical system before the video is superposed. Thus, the contrast to the observed image can be made higher without lowering the brightness of the displayed video, so that the efficiency can be enhanced.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a 1m image that provides a density difference when displaying video information in a superimposed manner. Relating to device filters.

In recent years, video superimposition devices have been put into practical use in head-up displays, microscopes, and the like. Such a video superimposing device superimposes and displays other video information on scenery, video, etc. within the field of view, and can recognize more information at the same time without requiring large movements. Therefore, in order to accurately recognize more information, it is required that the displayed image has good contrast. Therefore, it is necessary to provide a density difference only to the background without reducing the brightness of the displayed image.

[Conventional technology]

FIG. 7 shows a configuration diagram of a microscope to which a conventional image superimposing device is applied. The microscope R50 in FIG. 7 is the observation object 51.
The real image of the objective lens 52. Through the imaging lens 53, the position [
56, and the observer 55 recognizes the erect virtual image through the eyepiece 54. On the other hand, between the objective lens 52 and the imaging lens 53, a plate (hereinafter referred to as "image combiner J") 57 is provided with reflectance and transmittance set appropriately.
An information image from a display tube 58 is incident on an image combiner 57 such as a half mirror via a collimator lens 59. That is, the image combiner 57 transmits the image of the observation object 51 depending on the ratio, reflects the information image of the display tube 58, and superimposes the two images.

Generally, microscopes are used for observing the fine structure of objects, performing precision work, etc., and include monocular types and binocular types including stereoscopic microscopes capable of stereoscopic viewing.

Applying the above-mentioned image superimposition to such a microscope expands the functions of the microscope, since it is possible to display working conditions and image information superimposed within the field of view of the microscope.
It is possible to eliminate the need to take one's eyes away from the field of view of the microscope and refer to an external display, etc., and also to reduce eye fatigue.

Here, the image combiner 57 in FIG. 7 is located in the parallel light portion of the microscope optical system. This is because by inserting the flat plate or cube-shaped image combiner 57, the generated multiple reflected light does not cause ghosts, and also because it can be easily installed in an existing microscope. For example, a beam splitter for photography is placed in the parallel light section, and by replacing it, images can be easily superimposed.

Generally, in order to make the display within the field of view easier to see, it is necessary to create a high contrast between the display and the observed image. However, depending on the brightness, color, and pattern of the observed image, the display may become extremely difficult to see.Although contrast can be increased by increasing the brightness of the display, if the display is too bright, it may become dazzling and difficult to see. There are cases where the image becomes difficult to see. Therefore, if you can make the background of only one displayed part darker than the surrounding area, you can increase the contrast of the display while keeping the overall brightness constant.Display Regarding the location,
It depends on the object of observation and the nature of the work, but for boat fishing it is the peripheral part of the field of view other than the central part.

Therefore, as a method of darkening the background of the display portion, there is a method using a filter having a density distribution, and a conceptual diagram thereof is shown in FIG. FIG. 8 (A> shows a filter 60, in which a dark region 62 is provided in a predetermined section of a transparent flat plate 61. This filter 60
It is placed at the real image position 56 of the microscope 50 in FIG. FIG. 8(B) shows the microscopic field of view in this case, and corresponds to the density distribution of the filter 60 in the area 63°64.
A concentration difference is formed between the two. With this, II! This is to make only the background of the displayed portion (video information portion) darker than the surrounding area.

[Problem to be solved by the invention]

However, the filter 60 is placed at the real image position of the microscope optical system, and the real image position is located near the eyepiece lens 54. Therefore, there is a problem in that the brightness of the superimposed display image itself is also reduced by the filter 6o, and the efficiency is deteriorated.

The present invention was made in view of the above problems, and an object of the present invention is to provide a filter for an image superimposing device that improves efficiency by increasing the contrast with the observed image without reducing the brightness of the displayed image. do.

[Means to solve the problem]

The above problem is solved by a filter for an image superimposing device that converts the luminous flux of a visual field image into parallel light, superimposes a display image on the visual field image of the parallel light, and creates a density difference in the superimposed image within the visual field.
The filter is formed by arranging first and second refracting means having similar refractive indexes facing each other, interposing a refractive layer having a different refractive index from the refractive index on the entire surface of the opposing surface or at a predetermined location, and This problem is solved by arranging the display images in parallel light before being superimposed.

It will be done. With this filter, the light flux that reaches the area to be darkened in the field of view is angularly separated into a group of light fluxes that form a predetermined angle with the optical axis in the parallel light section of the optical system before image superimposition. Remove by. That is, angular separation is performed by totally reflecting a part of the luminous flux of the visual field image on the observed object at the boundary between refractive layers having different refractive indexes, and the light from the display device is not transmitted through the filter. Thereby, a part of the visual field image can be made dark, and the display at a predetermined position within the displayed image can be superimposed on the dark area within the visual field image. In this case, the brightness of the displayed image does not decrease. Therefore, it is possible to increase the contrast with the visual field 1 (observed image) and improve efficiency without reducing the brightness of the displayed image.

[Effect]

As described above, in the filter of the present invention, the first and second refraction means face each other with a refraction layer interposed therebetween, and in parallel light,
[Embodiment] FIG. 1 shows a configuration diagram of an embodiment in which the filter of the present invention is applied to a microscope. In FIG. 1, in a microscope 1, a light beam from an observation object 2 is converted into parallel light by an objective lens 3, and enters an image combiner 5 via a filter 4. On the other hand, the displayed image on the display tube 6 is made into parallel light by the collimator lens 7 and enters the image combiner 5. The image combiner 5 is viewed from the filter 4! The image and the display image from the collimator lens 7 are superimposed, and the image forming lens 8. The superimposed image is recognized by the observer 10 through the eyepiece lens 9.

Next, FIG. 2 shows a block diagram of the filter. The filter 4 in FIG. 2 includes first and second refracting means 11 having the same refractive index.
,12. For example, it is formed by making the hypotenuses of two right-angled prisms of an optical glass (BK7) jaw face each other and providing an air layer 14 around them with a spacer 13. The air layer 14 is a refractive layer whose refractive index is different from that of the first and second refractive means, and the interval t
is set to several microns to several tens of microns. In this case, the surfaces through which light passes are δ, γ, β, and α in the figure, and antireflection means 151, such as a light absorbing material, is coated on the other sides.

Here, FIG. 3 shows a diagram for explaining the principle of the filter of the present invention. The filter 4 of the present invention in FIG.
It utilizes the phenomenon of total internal reflection that occurs at the interface of media with different refractive indexes. Now, a homogeneous medium (air layer with refractive index no)
Inside, a prismatic transparent body (first
and second refracting means 11.12> are arranged close to each other, and the planes α and δ, β and γ are parallel to each other, and the interval between β and γ is on the order of several micrometers to several 1−μ−. shall be. Figure 3 (A)
Of the light rays that are incident from below (the first refracting means 11) through the boundary surface δ, those that reach the surface γ at an angle larger than the critical angle θC are totally reflected.

On the other hand, what is reached at an angle θ smaller than θC is the medium n0
It is further refracted at the surface β, enters the prismatic transparent body that is the second refracting means 12, and then exits into the medium no from the upper surface α. If the surfaces α and δ are parallel, the light ray exiting from the surface α is in the same direction as the light ray entering the surface δ. This makes it possible to angularly separate the light rays (luminous flux) at the critical angle, and the traveling direction of the light rays that are not totally reflected does not change.

On the other hand, FIG. 3(B) shows the influence of the wavelength dispersion of the refractive index on the angular separation of light rays. - In general optical glasses, the refractive index for short wavelength light is greater than the refractive index for long wavelength light. Here, as shown in the table for three types of refractive index and critical angle with respect to air of BK7, which is one of the most common optical glasses, the critical angle differs by 0.41 degree between red light and blue light. Visible wavelength range from 400 to 700
rv, it will be a little less than 0.6 degrees far. If the angle of incidence θ on the interface γ is smaller than the critical angle for the blue wavelength, all light in the visible range reaches the surface β without being totally reflected (ignoring specular reflection at the interface). When the incident angle θ' on the boundary surface γ is within the wavelength dispersion range of the critical angle, a part of the wavelength band is removed by total reflection, and a tint appears in the traveling light wave. For example, in Figure 3 (A), if no-1 (air) and n is the refractive index of BK7, the angle in the air is about 15 times the angle in the glass, so a little less than 0.6 degrees is 0. .9
slightly enlarged. There is a maximum of 0.9 degrees between the part where all wavelengths in the visible range are removed due to total internal reflection and the image is missing in the field of view, and the part where all wavelengths in the visible range reach and the color of the observed object itself can be seen. There is a spectral range. The width of the spectral region within the field of view is actually observed, but it is narrow, so there is no problem with darkening part of the background.

Therefore, the field of view of the microscope 1 shown in FIG. 1 is shown in FIG. 4. In FIG. 4, a circle 16 represents the field of view of the microscope, and is an area where an observation image (field image) can be seen. The upper shaded area 17 is a portion where light from the observation object is removed by the filter 4, and the image is black and missing. An image is displayed on this portion via an image combiner 5. At the boundary between the observed image and the area where the video is missing, there is the spectral area 1 mentioned earlier.
8 exists, but the width is not a practical problem.

Further, although the spectral region 18 is colored, the observed image is visible, so it has the effect of blurring the boundary between the observed image and the display area. In this case, since the filter 4 is placed in parallel light and before being superimposed by the image combiner 5, the area 17 can be changed by slightly rotating the filter 4 and changing the incident angle. Yes (Figure 1).

The microscope M1 shown in FIG. 1 may be any of a ψ-eye microscope, a binocular microscope, and a stereomicroscope.

In the case of a stereomicroscope, there are two systems of optical axes, but the configuration shown in the figure may be such that the two systems are provided in a direction perpendicular to the plane of the paper (however, the objective lens may be shared). In this case, the filter 4 shown in FIG. 2 may also be long in the direction perpendicular to the plane of the paper to cover the two optical systems, or it may be set separately for the two systems.

Next, FIG. 5 shows a configuration diagram of another embodiment of the filter according to the present invention. The filter 4 in FIG. 5 has a part of the refractive layer 14 in FIG.
9.

As a result, instead of completely removing part of the observed image within the field of view, the brightness is lowered as if passing through an ND filter (neutral density filter that does not exhibit spectral selective absorption), making the background visible. In the parallel light section of the microscope optical system, an angular filter is applied to a portion of the light beams traveling in various directions. Although the area becomes darker, the observed image also appears thinner.This embodiment is advantageous in understanding the entire observed image because there is no complete loss of the image.

Next, FIG. 6 shows a diagram for explaining shift correction of the optical axis caused by the filter. The first and second refracting means 11 and 12 in FIG.
), as shown in FIG. 6, the angle of incidence with respect to the surface δ is not 0 degrees due to the relationship of angles that give the critical angle. Therefore, the optical axis of the light beam transmitted through the filter 4 moves in parallel.

In order to minimize the loss of light*i without modifying the existing microscope, the thickness of the image combiner 5 can be used to return the optical axis to its original position. Alternatively, the apex angles of the two prisms constituting the filter 4 may be optimized so that the angle of incidence of the optical axis with respect to the surface δ is 0 degrees. In this case, it is preferable that the image combiner 5 is cube-shaped with prisms pasted together.

As in the above embodiment, within the microscope AT field of view, the field of view 1
Even when 1 (observation image) is bright, an easy-to-see display image can be superimposed. In addition, by changing the angle of the filter, it is possible to change the area to be darkened, so that the back 1j (field image) of the displayed image is completely blacked out or visible even when it is dark, as necessary. It is also possible to eliminate dark areas.

In addition, although the above example shows the case where it is applied to a microscope,
The invention is not limited to this, and can be applied to optical systems such as telescopes in which an image superimposing device is used.

〔Effect of the invention〕

As described above, according to the present invention, the first
By arranging the second refracting means in parallel light and before the displayed image is superimposed, the contrast with the visual field image is increased without reducing the brightness of the displayed image, increasing efficiency. can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the filter of the present invention applied to a microscope, Fig. 2 is a block diagram of the filter of the present invention, and Fig. 3 is a diagram for explaining the principle of the filter of the present invention. , FIG. 4 is a diagram showing the field of view in FIG. 1, FIG. 5 is a configuration diagram of another embodiment of the filter in the present invention, and FIG. 6 is a diagram for explaining shift correction of the optical axis caused by the filter. , FIG. 7 is a block diagram of a microscope to which a conventional image superimposing device is applied, and FIG. 8 is a conceptual diagram in which a density difference is provided by a conventional filter. In the figure, 1 is a microscope, 2 is an observation object, 3 is an objective lens, 4 is a filter, 5 is an image combiner, 6 is a display tube, 7 is a collimator lens, 8 is an imaging lens, 9 is an eyepiece lens, and 10 is an observation lens. 11 is a first refraction means, 12 is a second refraction means, and 14 is a refraction layer (air layer). A configuration diagram of an embodiment of the filter of the present invention applied to a microscope w8.Configuration diagram of the filter of the present invention.FIG.

Claims (1)

[Scope of Claims] A filter for an image superimposing device that converts a luminous flux of a visual field image into parallel light, superimposes a display image on the visual field image of the parallel light, and creates a density difference in the superimposed image within the visual field, comprising: The filter (4) includes first and second refracting means (11, 12) having similar refractive indices.
facing each other, and a refractive layer (1
4) A filter for an image superimposing device, characterized in that the filter is formed with a filter interposed therebetween, and is disposed in the parallel light before the displayed image is superimposed.