RU2518863C1 - Optical system for projection type on-board display - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: optical system has a concave spherical beam-splitting mirror with curvature radius R, a flat beam-splitting mirror mounted with inclination to the optical axis, a spherical diffusing screen, a projection lens, a liquid crystal display and a condenser. The projection lens consists of two components and an aperture diaphragm (AD). The first component is a single negative meniscus whose convex side faces a diffusion screen with curvature radius R/2. The second component is made of a negative glued lens and a double-lens positive element comprising a biconcave and a biconvex lens. The AD is placed between the first and second components in the front focus of the second component into which the positive glued lens is directed, said positive glued lens being placed between the AD and the negative glued lens, and a positive meniscus lens, whose concave side faces the spherical diffusion screen. Optical power values of the lenses satisfy conditions given in the claim.

EFFECT: high flight safety by preventing loss of information from the display when the head of the pilot moves both along and perpendicular to the optical axis.

1 dwg, 1 app

Description

The present invention relates to optical instrumentation and can be used in the aviation industry, in particular for aviation optical sights, display devices in front of the windshield of the cockpit, etc.

On-board display devices are an optical system that provides overlay on the real picture of the external space of various symbolic information perceived by the pilot due to the positive brightness contrast. The overlay effect is ensured by the use of optical beam splitters in the indicator, partially transmitting light rays from external space and reflecting light rays coming from a collimated imaginary image of the information picture. The image source for the information picture is high-brightness screens, the displays of which are aligned with the front focal surface of the optical system of the projection-based on-board indicator (OSBI).

The main requirements for OSPB are:

- A large output field of view of at least 30 ° horizontally and 20 ° vertically, which determines the informative capabilities of the indicator;

- Significant removal of the entrance pupil - the plane of the pilot’s eye from the reflecting beam splitter (combiner) at a distance of more than 300 mm;

- Significant dimensions of the entrance pupil of at least 160 mm horizontally and 100 mm vertically, providing the ability to observe information when the pilot's head moves within Δx = 80 mm horizontally and Δy = ± 50 mm vertically;

- Minimal distortion distortion of the image of objects;

- The need to use as a display for the formation of the image of symbolic or other information - liquid crystal panels ZhSK displays;

- The constructive ability to withdraw the combiner from the path of rays to ensure the observation of objects only in the space of objects.

There are a number of OSPBI [1-2] installed in front of the windshield of the cockpit.

In known optical systems [1-2], flat surfaces are used as a reflecting beam splitting mirror (combiner), and OSPBI is collimator lenses with luminous screens installed in their focal planes.

The disadvantages of such optical systems are that they do not provide the required large angular fields of view due to the limited size of the lens. Indeed, the angular field 2ω is related to the diameter (D) of the lens by the ratio:

D = 2S tg (ω) xD _int.sp ,

where S is the distance from the pilot’s eyes to the lens, D _int.sp is the diameter of the entrance pupil.

Since the value of S = 300 mm, then already at 2ω = 30 ° there should be a lens diameter D≥160-270 mm.

The optical system of the projection on-board indicator [3] is made in the form of a concave spherical beam splitting mirror, a flat beam splitting mirror mounted obliquely to the optical axis, a projection lens and a display containing a cathode ray tube (CRT).

The disadvantage of this OSPBI is the inability to use an LCD display to form an information image.

The disadvantage of OSPBI [4], containing a beam-splitting concave spherical mirror and a flat beam-splitting mirror mounted obliquely to the optical axis, a diffuse-scattering screen, a projection lens and a ZhSK display, is a small angular field of view.

The disadvantage of OSPBI [5], containing a beam-splitting concave spherical mirror and a flat beam-splitting mirror mounted obliquely to the optical axis, a diffuse-scattering screen, a projection lens and a display, is a small angular field of view and the size of the incoming pupil.

The disadvantage of OSPBI [6], which contains a beam-splitting concave spherical mirror and a flat mirror mounted obliquely to the optical axis, a projection lens, and an ZhSK display, is the small size of the entrance pupil.

The closest technical solution to the proposed invention is OSPB [7].

The optical system of the projection on-board indicator contains a concave spherical beam splitting mirror with a radius of curvature R, a flat beam splitting mirror mounted obliquely to the optical axis, a spherical diffuse-scattering screen, a projection lens, a liquid crystal display, and a condenser.

The projection lens consists of two components and an aperture diaphragm (AD), the first component is made in the form of a single meniscus with negative optical power φ _I , convex to a spherical diffuse-scattering screen with a radius of curvature R / 2, the second component is made of a glued lens with negative optical power φ _{II, 1} and a two-lens element with positive optical power φ _{II, 2} , containing biconcave and biconvex lenses glued together.

The disadvantages of OSPBI are the possibility of its use only for small distances from the pilot’s eyes to the beam splitting mirror, i.e. for values of S <50 mm; the inability to move the pilot’s head during the observation of symbolic information due to the strictly fixed position of the OSPB relative to the pilot’s head.

The main objective of the invention is to ensure flight safety by eliminating the loss of information from the display when the pilot’s head moves along the optical axis and perpendicular to it due to the large size of the OSBI entrance pupil and the distance from it to the combiner.

To solve this problem, an optical system for a projection on-board indicator is proposed, which, like the prototype, contains a concave spherical beam splitter with a radius of curvature R, a flat beam splitter mounted obliquely to the optical axis, a spherical diffuse-scattering screen, and a projection lens consisting of two components and aperture diaphragm (AD), the first of the components is made in the form of a single meniscus with negative optical power φ _I , convex to a spherical diff narrowly scattering screen with a radius of curvature R / 2, the second component is made of a glued lens with negative optical power φ _{II, 1} and a two-lens element with positive optical power φ _{II, 2} , containing a biconcave and biconvex lens, as well as a liquid crystal display and a condenser.

Unlike the prototype, in the proposed optical system of the projection on-board indicator, an aperture diaphragm (AD) is installed between the first and second components in the front focus of the second component, a glued lens with a positive optical power φ _{II, 3} installed between the aperture diaphragm (AD) is introduced into the second component and cemented lenses with negative refractive power φ _{II, 1} and a meniscus lens with a positive refractive power φ _{II, 4} facing concavity to the spherical diffuse-diffusing screen installed behind COMBINE constant lens with negative refractive power φ _{II, 1,} with a biconcave and biconvex lens element with a positive two-lens optical power φ _{II, 2} are arranged with an air gap, the optical power of the lenses satisfy a condition:

0.2 <| φ _I / φ _equiv | <0.3

0.4 <| φ _{II, 1} / φ _equiv | <0.5

0.1 <φ _{II, 2} / φ _equiv <0.25

0.9 <φ _{II, 3} / φ _equiv <1.1

0.45 <φ _{II, 4} / φ _equiv <0.6

where φ _eq is the equivalent optical power of the lens as a whole.

The essence of the proposed optical system for the projection on-board indicator is as follows.

Installing an aperture diaphragm (AD) between the first and second components in the front focus of the second component provides a telecentric path of the main rays in the space of the liquid crystal display.

Polarized radiation from the source after the parallel-beam condenser illuminates the liquid crystal display and, after reflection from its surface, fills the aperture diaphragm (AD) of the projection lens, creating the greatest and most uniform brightness of the liquid crystal display.

The introduction into the second component between the aperture diaphragm (AD) and the negative lens optical lens φ _{II, 1 of the} positive optical lens bonded lens _{II, 3} , and behind the negative optical lens φ _{II, 1 of the} meniscus lens with positive optical power φ _{II, 4} , facing concavity to a spherical diffuse scattering screen, allowed to increase the aperture of the lens in the space of the liquid crystal display and thereby increase the illumination of the image on the spherical diffuse scattering screen, outside a layer of positive aberrations, coma, astigmatism, increase chromatism and negative position chromatism, which made it possible to compensate for the aberrations introduced by the other lenses of the projection lens.

The installation of a biconcave and biconvex lens of a two-lens element with a positive optical power φ _{II, 2} with an air gap made it possible to eliminate the chromaticity of position and magnification, as well as astigmatism.

The implementation of lenses with optical powers that satisfy the condition:

0.2 <| φ _I / φ _equiv | <0.3

0.4 <| φ _{II, 1} / φ _equiv | <0.5

0.1 <φ _{II, 2} / φ _equiv <0.25

0.9 <φ _{II, 3} / φ _equiv <1.1

0.45 <φ _{II, 4} / φ _equiv <0.6

where φ _eq is the equivalent optical power of the lens as a whole, it was possible to obtain the specified surface curvature of the spherical diffuse-scattering screen equal to the focal length (f) of the concave spherical beam splitter mirror, f = R / 2, where R is the radius of curvature of the concave spherical beam splitter and compensate for the distortion of the projection lens on a spherical diffuse-scattering screen.

The essence of the invention is illustrated in the drawing, which shows a diagram of the optical system of the projection on-board indicator, and the Appendix, which shows the design parameters and optical characteristics of a particular sample.

The proposed optical system for the projection on-board indicator consists of a concave spherical beam splitting mirror 1 with a beam splitting reflecting surface 2 of radius R, a flat beam splitting mirror 3 with a beam splitting reflecting surface 4, a spherical diffuse-scattering screen 5 with a radius R / 2, and a projection lens consisting of the first component made in the form of a single meniscus 6 with negative optical power φ _I , convex to a spherical diffuse-scattering screen 5, an aperture diaphragm (AD) 7 and a second component comprising a glued lens 8 with negative optical power φ _{II, 1} , a two-lens element 9 with positive optical power φ _{II, 2} , made in the form of a biconcave and biconvex lenses mounted with an air gap, a glued lens 10 with a positive optical power φ _{II, 3} , a meniscus lens 11 with a positive optical power φ _{II, 4} , facing concavity to a spherical diffuse-scattering screen 5.

The liquid crystal display 12 is illuminated by a source 13 using a capacitor 14 and a polarizing prism 15.

The pupil of the eye 16 can move horizontally by ± Δx and vertically (in the plane of the drawing) by ± Δy in the plane of the entrance pupil 17, observing the object 18 and simultaneously displaying symbol information from the liquid crystal display 12 on a spherical diffuse-scattering screen 5.

The optical system of the projection on-board indicator is as follows.

In the reverse course of the rays, parallel beams of light from each pilot’s eye with a diameter equal to the diameter of the entrance pupil of the eye (2-4 mm), after reflection from a concave spherical mirror 1 and a flat beam-splitting mirror 3, focuses on the spherical surface of the diffuse-scattering screen 5 located in focus concave spherical mirror 1.

The projection lens 6-11 mates the surface of the liquid crystal display 12 with the surface of the diffuse-scattering screen 5. Thus, the optical system of the projection on-board indicator is a monocular wide-angle magnifier, in the focus of which a diffuse-scattering screen 5 is mounted on which information from the liquid crystal display 12 is projected The pilot simultaneously observes the surface of the diffusely scattering screen 5 against the background of the external object 18.

To illuminate the liquid crystal display 12, a lighting system is used consisting of a radiation source (LED) 13 located at the focus of the condenser 14. A parallel radiation beam after the capacitor 14 is reflected from the polarizing surface of the prism 15, which reflects the P-polarization and transmits S-polarization. The P radiation reflected from the liquid crystal display 12 is rotated 90 ° and focused in the plane of the aperture diaphragm (AD) 7, filling its diameter. The projection lens 6-11 operates with a magnification of 5.7 ^x for the attached example in the direction of the diffuse-scattering screen 5.

, например, при R=360 мм α≥24°, или апертура sinα≥0,4.The largest apertures at which polarization with prism 15 is provided do not exceed 0.13-0.15. With an increase of 5.7 ^{x the} aperture in the image space on the diffuse-scattering screen 5 is 0.02-, 025. In order to be able to observe the information when the pilot’s head is shifted by Δx = ± 80 mm, Δy = ± 50 mm, it is required that the diffusion-scattering screen 5 has an aperture (α) of at least

for example, at R = 360 mm α≥24 °, or the aperture sinα≥0.4.

To ensure the aperture sinα≥0.4-0-0, a diffuse-scattering screen 5 is used, which converts the 0.025 aperture incident on it after radiation passes through it to 0.4-0.5.

As an example, the optical system of the projection on-board indicator is shown with the following parameters given in the Appendix.

INFORMATION SOURCES

1. Russian Federation, patent for invention No. 2358304, IPC: G02B 27/08, G02B 27/01, publ. 06/10/2009

2. Russian Federation, patent for invention No. 2358303, IPC: G02B 27/08, G02B 27/01, publ. 06/10/2009

3. United States, patent for the invention No. 5907416, IPC: G02B 27/01, G09B 9/30, publ. 05/25/1999

4. France, patent for invention No. 2858068, IPC: G02B 27/01, publ. January 28, 2005

5. United States, patent for the invention No. 7391574, IPC: G02B 27/14, publ. September 20, 2007

6. United States, patent for the invention No. 8089568, IPC: G02B 27/01, G02F 1/1335, publ. 01/03/2012

7. United States, patent for the invention No. 5483307, IPC: G02B 26/08, G02B 27/01, G02B 27/02, G02B 27/00, publ. 01/09/1996, the prototype.

Claims (1)

The optical system of the projection on-board indicator, containing a concave spherical beam splitter mirror with a radius of curvature R, a flat beam splitter mirror mounted obliquely to the optical axis, a spherical diffuse-scattering screen, a projection lens consisting of two components and an aperture diaphragm (AD), the first component is made in the form of a single meniscus with negative optical power φ _I , convex to a spherical diffuse-scattering screen with a radius of curvature R / 2, the second component in made of a glued lens with negative optical power φ _{II, 1} and a two-lens element with positive optical power φ _{II, 2} , containing a biconcave and biconvex lens, as well as a liquid crystal display and a condenser, characterized in that the aperture diaphragm (AD) is installed between the first and the second component in the front focus of the second component, a glued lens with a positive optical power φ _{II, 3} , inserted between the aperture diaphragm (AD) and a glued lens with a negative optical system, is introduced into the second component loya φ _{II, 1} , and a meniscus lens with positive optical power φ _{II, 4} , facing concavity to a spherical diffuse-scattering screen, mounted behind a glued lens with negative optical power φ _{II, 1} , with a biconcave and biconvex lens of a two-lens element with positive optical forces φ _{II, 2 are} installed with an air gap, while the optical forces of the lenses satisfy the condition:
0.2 <| φ _I / φ _equiv | <0.3
0.4 <| φ _{II, 1} / φ _equiv | <0.5
0.1 <φ _{II, 2} / φ _equiv <0.25
0.9 <φ _{II, 3} / φ _equiv <1.1
0.45 <φ _{II, 4} / φ _equiv <0.6
where φ _eq is the equivalent optical power of the lens as a whole.

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