CN101915992B - Free-form surface goggles-based see-through helmet mounted display device - Google Patents

Abstract

The invention discloses a penetrating helmet display device based on free-form surface goggles. There is a free-form goggle directly in front of the helmet body, and a micro-display imaging device and a relay lens group are respectively installed in front of the helmet body and on both sides of the upper part of the free-form goggle, and the inclination angle of the two relay lens groups is 42 degrees arrangement, the relay lens group includes a first relay lens, a second relay lens, a third relay lens, a fourth relay lens, a fifth relay lens, and a sixth relay lens, and the first relay lens and The second relay lens, the third relay lens, the fourth relay lens, the fifth relay lens, and the sixth relay lens are placed in sequence. The invention adopts the tire-shaped free-form surface to participate in the imaging, can realize a large off-axis angle of 33 degrees, can better correct aberrations, significantly improve the imaging quality, and has a simple structure; it is suitable for arrangement on the human head and conforms to the ergonomics Features: It adopts short focal length and large field of view design, with 12-15mm exit pupil and 40-50 degree field of view.

Description

A penetrating helmet-mounted display device based on free-form surface goggles

technical field

The invention relates to a penetrating helmet display device based on free-form surface goggles.

Background technique

After more than 30 years of development, especially in recent years, the technology of the helmet-mounted display has made great progress. The helmet-mounted display was first used in virtual reality. The feeling of being in a virtual environment. Head-mounted displays are widely used in virtual reality, visual training, medicine, aviation, entertainment and other occasions, and have a huge application market. HMD can be divided into immersion type and penetrating type according to its application. The immersion type is to block the external signal of the helmet and only display the internal signal generated by the helmet. The penetrating type is just the opposite. It superimposes the internal signal and the external scene of the helmet. The helmet-mounted display can realize the superposition of internal virtual signals and external real-world information. Users can see various information generated internally and external scenes at the same time. Therefore, it has greater applications in virtual reality, such as helmets. The display can be easily installed on headgear such as flight helmets, combat helmets, heat-insulating helmets, fire masks, chemical masks, safety helmets, etc., to realize the application of special occasions such as flight, fire fighting, and lifesaving.

The helmet display generally consists of the following parts: image information display source, image imaging optical system, positioning sensing system, circuit control and connection system, helmet and counterweight device. Among them, the design of the helmet display optical system is one of the core technologies of the whole system design, which is directly related to the overall performance of the helmet display. For this reason, the research and development of a head-mounted display optical system with good optical performance, reasonable structure and strong practicability is one of the important links affecting the performance of the head-mounted display.

The helmet display system can be divided into small field of view, medium field of view and large field of view according to the size of the field of view. The large field of view display can broaden the observation range and increase the display information capacity. At the same time, it can form depth perception through the enhancement of real objects and virtual objects. The large field of view helmet display can meet the needs of virtual reality immersion and interactivity. In order to achieve a large field of view display, there are two main forms of helmet display according to the structure classification: eyepiece structure and projection structure. The structure of the eyepiece belongs to the NonPupil form, that is, the image generating device has no conjugate image, and the exit pupil of the eye is used as the exit pupil of the helmet system. The projection structure belongs to the Pupilforming form, that is, the pupil plane in the optical system is conjugate to the eye exit pupil. Although the eyepiece structure has the advantages of simple structure and color display, it also has the disadvantage of difficult aberration correction under the condition of large field of view. The projection form has the characteristics of high imaging definition, but at the same time, it also has the disadvantage of being limited by the type and position of the folding screen.

Using the helmet goggles as the collimation combination element of the penetrating helmet display optical system has become a trend in the design of the helmet display optical system, especially in the wide field of view system. Therefore, the helmet goggles can be used as the design structure of the collimation combination glass element of the helmet display optical system to realize the direct projection of the image and complete the improvement of the optical system structure. Especially in recent years, with the continuous development of optical technology and processing technology, the application of reflective aspheric off-axis systems in helmet systems has been gradually applied. Compared with holographic optical components, aspheric surfaces have High efficiency, less stray light, good imaging quality, etc., the aspheric surface can better correct aberrations, so as to meet the requirements of reducing the number of optical components and reducing weight. At the same time, the role of helmet goggles is not only for protection, More importantly, it has become a part of the helmet display optical system, and its optical characteristics are very prominent.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a penetrating helmet display device based on free-form surface goggles.

The penetrating helmet display device based on free-form goggles includes a micro-display imaging device, free-form goggles, a helmet body, and a relay lens group. Free-form goggles are arranged directly in front of the helmet body. There are micro-display imaging devices and relay lens groups on the front and on both sides of the upper part of the free-form surface goggles. The two relay lens groups are arranged at an inclination angle of 42 degrees. The relay lens group includes the first relay lens and the second relay lens. , the third relay lens, the fourth relay lens, the fifth relay lens, the sixth relay lens, the first relay lens and the second relay lens, the third relay lens, the fourth relay lens, the sixth relay lens The fifth relay lens and the sixth relay lens are placed in sequence.

The free-form surface goggles adopt a tire-shaped free-form surface in an off-axis working mode, and have an off-axis angle of 33 degrees. The focal length of the reflection surface of the free-form surface goggles is positive, and the focal length distribution meets the following conditions: 1.5<F8/F< 1.8, F8 is the focal length of the free-form surface goggles, and F is the focal length of the relay lens group;

The first relay lens is a biconvex lens, the second relay lens is a meniscus lens, the third relay lens is a meniscus lens, the fourth relay lens is a biconvex lens, and the fifth relay lens is a meniscus lens , The sixth relay lens is a meniscus lens, and the focal length of the sixth relay lens satisfies: 5.0<F7/F<5.5; wherein, F7 is the focal length of the sixth relay lens, F is the focal length of the relay lens group, and the sixth The focal length of the four relay lenses is positive, and the focal length satisfies: 1.6<F5/F<2.0, where F5 is the focal length of the fourth relay lens, and F is the focal length of the relay lens group.

The micro-display imaging device is placed at an inclination of 4-6 degrees.

The combined focal length of the relay lens group and the free-form surface goggles is 25-30 mm.

The optical structure composed of the micro-display imaging device, the free-form surface goggles and the relay lens group has an exit pupil of 12-15 mm and a viewing angle of 40-50 degrees, and its relative aperture is 2.0-2.2.

Compared with the prior art, the present invention has the beneficial effects as follows: 1) adopt tire tread-shaped free-form surface to participate in imaging; it can ensure imaging with short focal length, large relative aperture and large field of view, can better correct aberrations, and has a simple structure: 2) With a large off-axis angle of 33 degrees, it is suitable for arrangement on the head of the human body, which is in line with the ergonomics performance characteristics; 3) The inclined and eccentric structure of the relay lens is used to significantly improve the imaging quality. 4) Adopt short focal length and large field of view design, focal length 25-30mm, with 15mm exit pupil and 40-degree field of view, 5) Large relative aperture design, relative aperture is 2.0-2.2, which improves the illuminance on the image plane;

Description of drawings

Fig. 1 is a schematic structural diagram of a large off-axis angle helmet display device based on free-form surface goggles;

Fig. 2 is the side structure schematic diagram of the present invention;

Fig. 3 is the layout diagram of the optical system of the present invention;

Fig. 4 is the modulation transfer function of the helmet display optical structure of the present invention;

Fig. 5 is a spot diagram of the present invention in each field of view;

Fig. 6 is the pupil plane aberration diagram of the present invention in each field of view;

In the figure, the microdisplay imaging device S1, first relay lens S2, second relay lens S3, third relay lens S4, fourth relay lens S5, fifth relay lens S6, sixth relay lens S7 , free-form surface goggles S8, human eyes S9, helmet body S10, relay lens group S21.

Detailed ways

As shown in Figure 1, the penetrating helmet display device based on free-form surface goggles includes micro-display imaging device S1, free-form surface goggles S8, helmet body S10, relay lens group S21, and the front of helmet body S10 is set There are free-form goggles S8, the front of the helmet body S10, and the upper sides of the free-form goggles S8 are respectively equipped with a micro-display imaging device S1 and a relay lens group S21, and the two relay lens groups S21 are arranged at an inclination angle of 42 degrees , the relay lens group S21 includes a first relay lens S2, a second relay lens S3, a third relay lens S4, a fourth relay lens S5, a fifth relay lens S6, a sixth relay lens S7, and A relay lens S2 is placed in sequence with the second relay lens S3, the third relay lens S4, the fourth relay lens S5, the fifth relay lens S6, and the sixth relay lens S7.

The free-form surface goggles S8 adopts a tire-shaped free-form surface that works off-axis, and has an off-axis angle of 33 degrees. The focal length of the reflection surface of the free-form surface goggles S8 is positive, and the focal length allocation meets the following conditions: 1.5<F8/ F<1.8, F8 is the focal length of the free-form surface goggles S8, and F is the focal length of the relay lens group S21;

The first relay lens S2 is a biconvex lens, the second relay lens S3 is a meniscus lens, the third relay lens S4 is a meniscus lens, the fourth relay lens S5 is a biconvex lens, and the fifth relay lens S6 is a meniscus lens, and the sixth relay lens S7 is a meniscus lens. The focal length of the sixth relay lens S7 satisfies: 5.0<F7/F<5.5; wherein, F7 is the focal length of the sixth relay lens S7, and F is The focal length of the relay lens group S21, the focal length of the fourth relay lens S5 is positive, and the focal length satisfies: 1.6<F5/F<2.0, where F5 is the focal length of the fourth relay lens S5, and F is the focal length of the relay lens group S21. focal length.

The micro-display imaging device S1 is placed at an inclination of 4-6 degrees.

The combined focal length of the relay lens group S21 and the free-form surface goggles S8 is 25-30 mm.

The optical structure composed of the micro-display imaging device S1, the free-form surface goggles S8, and the relay lens group S21 has an exit pupil of 12-15 mm and a viewing angle of 40-50 degrees, and its relative aperture is 2.0-2.2.

Fig. 2 is a schematic diagram of the side structure of the present invention. The helmet body can be a motorcycle helmet, a firefighting helmet or a flight helmet. Efficacy characteristics, the binocular helmet constructed in this way can be used in firefighting, aviation and virtual reality and other occasions.

Fig. 3 is a schematic diagram of the optical structure composed of micro-display imaging device S1, free-form surface goggles S8, and relay lens group S21, which sequentially has micro-display imaging device S1, relay lens S2, relay lens S3, relay lens S4, Relay lens S5, relay lens S6, relay lens S7, and free-form surface goggles S8; the optics adopt a catadioptric structure, and the virtual image generated by the micro-display imaging device S1 passes through relay lens S2, relay lens S3, relay Lens S4, relay lens S5, relay lens S6, and relay lens S7 are transmitted and reflected by the goggles into the human eye S9. The goggles S8 adopt tire-shaped free-form surface reflectors, and work off-axis, providing The large off-axis angle of 33 degrees is convenient for arrangement on the head. Relay lens S2, relay lens S3, relay lens S4, relay lens S5, relay lens S6, and relay lens S7 adopt biconvex-curved lenses respectively Moon-meniscus-biconvex-meniscus-meniscus structure, wherein the relay lens S3, the relay lens S4 and the relay lens S6 bend toward the direction of the micro-display device, and the relay lens S7 faces away from the direction of the micro-display device, The relay lenses are all made of even-order symmetrical aspheric lenses, and they work off-axis with eccentric inclination to correct part of the off-axis aberration caused by the large off-axis angle of the goggles. At the same time, the relay lenses are all made of optical plastics to reduce the weight of the lens , easy to install on the head. The goggles respectively adopt tire-shaped polynomial free-form reflective surfaces, which have more degrees of freedom, can minimize aberrations, and thus improve clarity.

The structure form of the polynomial free-form surface of the tread shape can be described by the following polynomials, as expressed in formulas (1) and (2):

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; )</span>{{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Ax</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Bx</span>}}^{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Cx</span>}}^{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Dx</span>}}^{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In formula (1), Z _x is the Sag quantity in the x direction, x is the x-axis coordinate, k _x : the cone coefficient in the x direction, c _x : the curvature of the basic spherical surface in the x direction, A, B, C, D are polynomial coefficients, Equation (1) shows that the variation of the free-form surface in the x direction is an even-degree polynomial of x;

The surface shape of the tire-shaped free-form surface in the x direction is expanded along the surface shape in the y direction, and the surface shape in the y direction satisfies the following formula:

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HSA00000203285300041.png,HSA00000203285300061.png"\; state="\{\{state\}\}">y</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; )</span>{{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HSA00000203285300041.png,HSA00000203285300061.png"\; state="\{\{state\}\}">y</figure-callout></span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, Z _y is the Sag quantity in the y direction, y is the coordinate of the y axis, ky _y : the conic coefficient in the y direction, cy _y : the curvature of the basic spherical surface in the y direction.

From equations (1) and (2), it can be seen that compared with the traditional even-order aspheric surface with rotational symmetry, the tire-shaped free-form surface is an asymmetric form, and the surface shapes in the x and y directions are completely different, so it has more Design freedom, at the same time, in the goggle helmet system, due to the tilt of the goggles, the asymmetry of the x-z plane and y-z plane will be formed, and the spherical aberration caused by this asymmetrical system can be better corrected by using the free-form surface of the tire tread , coma, distortion and other aberrations to obtain better imaging quality.

In Fig. 3, the surface reflection of the inner wall of S8 with tire tread shape is used, and the inner wall surface is coated with a semi-transparent and semi-reflective optical film, so that the image from the display chip and the relay optical system can be reflected by the inner wall surface in the direction of D1, while the outside world The information in the D2 direction can also penetrate the goggles and be superimposed on the human eye. For the information from the micro-display chip and the relay optical system, the goggles mainly play the role of a concave mirror with a positive focal length, which is mainly used to reduce the aperture of the relay optical system, reduce the size and weight of the optical system, and generate large The off-axis angle can be easily installed on the head. The concave mirror is concave to the human eye and placed at an angle of 33 degrees. In this way, the off-axis light with a large field of view is reflected and converged by the goggles S8. Compared with the rear reflector The field of view becomes smaller, so as to achieve the purpose of expanding the field of view. The focal length of the goggles S8 meets the following conditions:

1.5＜F8/F＜1.8            (3)

Among them, F8 is the focal length of the reflective surface S8 of the goggles, and F is the overall focal length of the system.

Equation (3) is the focal length allocation condition of the reflective surface S8, and Equation (3) is also a condition that must be satisfied for structural aberration balance. When F8/F<1.5, it is difficult to correct the overall structure in a large relative aperture and large field of view The aberrations caused by angular conditions, when F8/F>1.8, will increase the aperture of the subsequent optical system, so that the size and weight of the entire system cannot meet the ergonomics. At the same time, the reflective surface S8 also acts as a fine adjustment function, through the movement of the reflective surface S8, to ensure that the position of the image plane remains unchanged during the imaging process.

The relay lens S6 and the relay lens S7 are mainly used to correct the remaining off-axis coma aberration caused by the reflective surface S8. The relay lens S7 is an aspheric convex lens, which is in the shape of a meniscus and bends towards the direction of the goggles. The focal length distribution is positive. The focal length allocation of the relay lens S7 satisfies:

5.0＜F7/F＜5.5            (4)

Among them, F7 is the focal length of the rear relay lens S7, and F is the overall focal length of the system.

Equation (4) is the focal length allocation condition of the relay lens S7, and Equation (4) is the condition that must be satisfied for structural aberration balance. When F7/F<5.0, it is difficult to correct the overall structure caused by zooming under the condition of large relative aperture. The coma aberration caused, when F7/F>5.5, will shorten the back working distance of the system, causing the back intercept of the system to be insufficient to meet the conditions.

Relay lens S5 is an aspheric biconvex lens, which is mainly used to correct off-axis astigmatism and coma aberration. The focal length allocation is positive, and the focal length allocation of relay lens S5 satisfies:

1.6＜F5/F＜2.0          (5)

Relay lens S4 and relay lens S3 are both aspherical lenses, which use high and low refractive index and different dispersion glasses, and adopt a certain inclination angle, which is mainly used to correct residual spherical aberration and chromatic aberration;

The relay lens S2 is a biconvex lens, which is mainly used to correct distortion; the focal length distribution of the relay lens S2 satisfies:

1.3＜F2/F＜1.5           (6)

The overall optical system uses the micro-display surface to be placed at an inclination of 4 degrees, and the asymmetrical aberration is corrected by eccentric inclination. The relative aperture of the overall system is 2.0-2.2, the focal length is 25-30mm, the exit pupil is 12-15mm and the viewing angle is 40-50 degrees , which can ensure that the light emitted by the display device enters the human eye as much as possible, thereby ensuring the viewing brightness and brightness uniformity.

Table 1 shows the detailed parameters of the penetrating helmet display optical system:

Table 1: Structure detailed parameters

The position in Table 1 is based on the center of the eye box as the coordinate origin, and the direction horizontally facing the goggles is the X direction.

The following are the coefficients of the free-form surface of the tire surface:

C _x = -1/76.76

_Cy = -100

k _x =k _y =0

A=-2.91e-008

B=1.55e-010

C=-1.46e-013

D=5.465e-017

The definitions of the above parameters are shown in formula (1) and formula (2);

Fig. 4 is the modulation transfer function of the helmet display optical system of the present invention; it can reach more than 35% of 35 line pairs on the image plane, and the meridional and sagittal separation is small, and the modulation transfer function of the center is high, so the design tolerance is large, and it is easy to ensure processing . Fig. 5 is the spot diagram of the present invention in each field of view, and the numbers on the left are respectively the size of the field of view and the position on the image plane in the figure; Fig. 6 is the pupil plane aberration diagram of the present invention in each field of view, in each figure The picture on the left shows the pupil plane aberration of the sub-object plane, and the picture on the right shows the pupil plane aberration of the sagittal plane.

Claims (2)

1. penetration helmet mounted display device based on the free form surface safety goggles; It is characterized in that comprising micro-display imager spare (S1), free form surface safety goggles (S8), helmet helmet body (S10), relay lens group (S21); The dead ahead of helmet helmet body (S10) is provided with free form surface safety goggles (S8); The dead ahead of helmet helmet body (S10), free form surface safety goggles (S8) both sides, top are provided with micro-display imager spare (S1) and relay lens group (S21) respectively; Two relay lens group (S21) angle of inclination, 42 degree are arranged; Relay lens group (S21) comprises first relay lens (S2), second relay lens (S3), the 3rd relay lens (S4), the 4th relay lens (S5), the 5th relay lens (S6), the 6th relay lens (S7), and first relay lens (S2) is placed from micro-display imager spare (S1) beginning with second relay lens (S3), the 3rd relay lens (S4), the 4th relay lens (S5), the 5th relay lens (S6), the 6th relay lens (S7) in order; Described free form surface safety goggles (S8) adopts the tire tread shape free form surface from the axle working method; Off-axis angle with 33 degree; The reflecting surface focal length of free form surface safety goggles (S8) is for just; The focal length distribution meets the following conditions: 1.5＜F8/F＜1.8, and F8 is the focal length of free form surface safety goggles (S8), F is the focal length of relay lens group (S21); Described first relay lens (S2) is a biconvex lens; Second relay lens (S3) is that meniscus lens, the 3rd relay lens (S4) are meniscus lens for biconvex lens, the 5th relay lens (S6) for meniscus lens, the 6th relay lens (S7) for meniscus lens, the 4th relay lens (S5), and the focal length of the 6th relay lens (S7) satisfies: 5.0＜F7/F＜5.5; Wherein, F7 is the focal length of the 6th relay lens (S7), and F is the focal length of relay lens group (S21); The 4th relay lens (S5) focal length is for just, and focal length satisfies: 1.6＜F5/F＜2.0, wherein; F5 is the focal length of the 4th relay lens (S5), and F is the focal length of relay lens group (S21); Described relay lens group (S21) and free form surface safety goggles (S8) synthesize focal length 25～30mm; The optical texture that described micro-display imager spare (S1), free form surface safety goggles (S8), relay lens group (S21) are formed has the field angle of 12～15mm emergent pupil and 40～50 degree, and its relative aperture is 2.0～2.2.

2. a kind of penetration helmet mounted display device based on the free form surface safety goggles according to claim 1 is characterized in that described micro-display imager spare (S1) inclination 4～6 degree placements.

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