CN106338821A - Micro display eyepiece and head-mounted equipment - Google Patents

Abstract

The invention discloses a micro-display eyepiece and a head-mounted device. The micro-display eyepiece includes two positive lenses, a first positive lens and a second positive lens are arranged in sequence against the light incident direction, the second surface and the third surface are diffractive surfaces with positive refractive power, and the diffractive surface and the refractive surface Compensate the power of each other, so that the light-emitting screen of the micro-display eyepiece can achieve a field angle of 80° in the case of 1 inch; since the diffractive surface has positive dispersion in the state of positive power, it can effectively compensate for the chromatic aberration of the system, and The diffraction surface does not produce field curvature, which can further improve the imaging quality of the peripheral field of view; at the same time, the lens made of easy-to-process plastic material is used to reduce the volume. The micro-display eyepiece and the head-mounted device provided by the technical solution can meet the market demands of light weight, miniaturization, low cost and large field of view.

Description

A micro-display eyepiece and a head-mounted device

The patent application of the present invention is a divisional application of the Chinese invention patent application with the filing date of November 28, 2014, the application number of 201410713899.1, and the title of "a micro-display eyepiece and head-mounted device".

technical field

The invention relates to the field of optical technology, in particular to a micro-display eyepiece and a head-mounted device.

Background technique

Micro-display (i.e. tiny screen) head-mounted devices are popular in the market due to their advantages of small screen size, low cost and light weight.

The image height and viewing angle in the micro-display system satisfy the relationship h=fgtan(θ), where h is the half height of the screen, f is the focal length of the optical system, and θ is the half viewing angle. If the micro-display system provides a larger viewing angle, that is, under the requirement that h in the formula takes a small value and θ needs to take a large value, the value of the focal length f will be very small. In the case of a certain aperture of the optical system, the smaller the focal length f of the system, the stronger the diopter. This requires multiple groups of lenses to share the focal power to avoid huge aberrations caused by excessive diopters. However, the optical system using multiple sets of lenses is contrary to the requirements of light weight and miniaturization; and in the traditional optical system, the combination of positive and negative lenses is required to correct chromatic aberration, and the introduction of negative lenses will increase the burden of the optical power of the positive lens, affecting Imaging quality, so the traditional design is difficult to provide a larger field of view, unable to bring enough immersion to the user, and difficult to meet the requirements of a large field of view micro-display head-mounted system.

Contents of the invention

The invention provides a micro-display eyepiece and a head-mounted device to solve the problem that the existing eyepiece cannot realize a large field of view under the requirements of light weight and miniaturization.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

In one aspect, the present invention provides a microdisplay eyepiece, comprising a first positive lens and a second positive lens, the first positive lens and the second positive lens are sequentially arranged against the direction of light incidence, and the first positive lens Both the second positive lens and the second positive lens are made of plastic;

The first positive lens has a first surface facing the image side and a second surface facing the object side;

The second positive lens has a third surface facing the image side and a fourth surface facing the object side;

Wherein the second surface and the third surface are diffractive surfaces with positive refractive power, and the first surface and the fourth surface are aspheric surfaces.

In another aspect, the present invention provides a head-mounted device, which adopts the micro-display eyepiece provided by the above technical solution.

The micro-display eyepiece and the head-mounted device provided by this technical solution adopt a double positive lens structure, and a diffractive surface with positive refractive power is provided on at least one surface of the two positive lenses, and the refractive power is mutually compensated by the diffractive surface and the refractive surface. Make the light-emitting screen of the micro-display eyepiece achieve a field angle of 80° in the case of 1 inch; because the diffractive surface has positive dispersion in the state of positive power, it can effectively compensate the chromatic aberration of the system, and almost no field will be generated Curved, so the imaging quality of the peripheral field of view of the microdisplay eyepiece is significantly improved; by setting two diffractive surfaces to share the optical power required by the system, and setting them on the second surface and the third surface respectively, so that the two diffractive surfaces are located The middle position of the optical system is convenient to protect the surface shape of the diffraction surface during the production process; at the same time, the lens in this embodiment can be made of easy-to-process plastic material to further reduce the volume of the system, so that the micro-display eyepiece and the head-mounted device can Meet the market demands of light weight, miniaturization, large field of view, and low cost.

Description of drawings

Fig. 1 is the structural representation of the microdisplay eyepiece that the embodiment of the present invention provides;

Fig. 2 is a schematic diagram of field curvature and distortion aberration curves of the microdisplay eyepiece provided by the embodiment of the present invention;

Fig. 3 is the spot diagram of the microdisplay eyepiece provided by the embodiment of the present invention;

Fig. 4 is a spot diagram of a micro-display eyepiece with uncorrected chromatic aberration of magnification;

5 is a schematic diagram of an optical transfer function curve of a microdisplay eyepiece provided by an embodiment of the present invention;

Fig. 6 is a schematic diagram of magnification chromatic aberration of the microdisplay eyepiece provided by the embodiment of the present invention;

Fig. 7 is a schematic diagram of magnification chromatic aberration of a micro-display eyepiece without chromatic aberration correction.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

FIG. 1 is a schematic structural diagram of a microdisplay eyepiece provided by an embodiment of the present invention. This system is a refraction-diffraction hybrid optical system.

The micro-display eyepiece includes a first positive lens 1 and a second positive lens 2, and the first positive lens 1 and the second positive lens 2 are sequentially arranged against the light incident direction, wherein the diaphragm 3 of the micro-display eyepiece is the pupil of the human eye, The distance from the first surface 11 of the first positive lens 1 is 10mm, wherein:

The first positive lens 1 has a first surface 11 facing the image side and a second surface 12 facing the object side;

The second positive lens 2 has a third surface 21 facing the image side and a fourth surface 22 facing the object side;

And at least one of the first surface 11 , the second surface 12 , the third surface 21 , and the fourth surface 22 is configured as a diffractive surface with positive refractive power.

In a preferred embodiment, the first surface 11 of the first positive lens 1 is convex to the image side, the central position of the second surface 12 is convex to the object side, and the second surface 12 is a diffractive surface;

The third surface 21 of the second positive lens 2 is convex toward the image side, the central position of the fourth surface 22 is convex toward the object side, and the third surface 21 is a diffraction surface.

In this preferred embodiment, two diffractive surfaces are provided to share the optical power required by the system, and they are respectively arranged on the second surface and the third surface, so that the two diffractive surfaces are located in the middle of the optical system, which is convenient for protection during the production process. The shape of the diffractive surface.

Further preferably, the diffraction surfaces of the second surface 12 and the third surface 21 are designed to be the same in shape. Two diffractive surfaces with the same surface type can reduce mold processing costs and save costs.

Further preferably, the first surface 11 and the fourth surface 22 are designed as aspheric surfaces, so as to reduce the processing complexity of the system.

Further preferably, the upper and lower end faces of the first positive lens 1 and the second positive lens 2 are designed as planes, so as to facilitate the adjustment of the adjustment errors of the lenses.

In another embodiment, the first positive lens 1 is made of plastic material, and its refractive index range is 1.45<n ₁ <1.70, and the dispersion range is 50<v ₁ <75; the second positive lens 2 is made of plastic material, and its refractive index The range is 1.45<n ₁ <1.70, the dispersion range is 50<v ₁ <75, and the shape of the lens made of plastic is easy to process, making the system lighter.

Fig. 2 is the field curvature of the microdisplay eyepiece provided by the embodiment of the present invention and the schematic diagram of distortion aberration curve, two positive lenses in the present embodiment are respectively the plastic material of PMMA type, its refractive index n ₁ =1.531160, dispersion is v ₁ ＝56.04; the left picture is a schematic diagram of the field curvature curve of the microdisplay eyepiece, the t line in the figure is the meridional field curvature, the s line is the sagittal field curvature, and the difference between the meridional field curvature and the sagittal field curvature is the astigmatism of the system , field curvature and astigmatism affect the aberration of the system's off-axis field of view light, and if the difference is too large, it will seriously affect the imaging quality of the system's off-axis light. It can be seen from the left picture that the field curvature and astigmatism of this system are corrected to a very small range; the right picture is a schematic diagram of the distortion and aberration curve of the micro-display eyepiece. The distortion will not affect the definition of the system, but will only cause the system image distortion, but the distortion can be resolved by post-image processing. It can be seen from the figure on the right that the distortion of this system is within a reasonable range. It will not affect the field curvature and distortion of the micro-display eyepiece, and significantly improve the imaging quality of the peripheral field of view.

The micro-display eyepiece in this embodiment has corrected the chromatic aberration of magnification, so that good image quality can be obtained. As shown in FIG. 3 , it is the spot diagram of the micro-display eyepiece provided by the embodiment of the present invention. The diffuse spots formed by the convergence of light rays in each field of view at the image plane characterize the characteristics of various phase differences obtained by the system. The smaller the RMS RADIUS (root mean square radius) in the spot diagram, the better the imaging quality of the system. In Figure 3, the three gray-scale colors represent the light of the three wavelength bands, and the wider the diffuse spots of the three gray-scale colors prove the greater the chromatic aberration of the system; , the phenomenon of dispersion is obvious in the figure. Comparing Figure 3 and Figure 4, it can be seen that the chromatic aberration of the micro-display eyepiece provided by the embodiment of the present invention has been well corrected.

Figure 5 is a schematic diagram of the magnification chromatic aberration of the micro-display eyepiece provided by the embodiment of the present invention. The horizontal axis in the figure represents the chromatic aberration, and the vertical axis represents the viewing angle. Fig. 6 is a kind of schematic diagram of magnification chromatic aberration of the micro-display eyepiece of uncorrected chromatic aberration, contrast Fig. 5 and Fig. 6, can find out that the chromatic aberration value of (system provided by the present invention) characterizes in Fig. 5 is far smaller than Fig. 6 (uncorrected Chromatic aberration system), the chromatic aberration values of the micro-display eyepiece provided by the embodiment of the present invention have been well corrected by summarizing Fig. 2-Fig. 6.

Fig. 7 is the schematic diagram of the optical transfer function curve of the micro-display eyepiece provided by the embodiment of the present invention, in which the horizontal axis represents the radius size position from the center of the imaging plane to the edge, zero on the left is the center of the lens, and the far right is the edge of the image field radius, The unit of size is millimeters, and the vertical axis represents the percentage of the imaging quality reaching the real state. From 0 to 1, the optical transfer function MTF can comprehensively reflect the imaging quality of the system. The smoother the curve shape, the higher the relative horizontal axis height (that is, the closer to 1), the better the imaging quality of the system; the MTF obtained by the micro-display eyepiece of the present embodiment at 0°～40° field of view is provided in Fig. 7 (with the micro-display eyepiece of the present embodiment at 0°～-40° The MTF curves of the field of view are symmetrical to each other) are ideal, and it can be seen that the aberrations of this system are well corrected.

The micro-display eyepiece provided by the above-mentioned technical solution includes two positive lenses, and a first positive lens and a second positive lens are arranged in sequence against the light incident direction; a double positive lens structure is adopted, and at least one surface of the two positive lenses is provided with The diffractive surface with positive refractive power compensates the refractive power through the diffractive surface and the refractive surface, so that the light-emitting screen of the micro-display eyepiece can achieve a field angle of 80° in the case of 1 inch; because the diffractive surface has a Positive dispersion can effectively compensate the chromatic aberration of the system and hardly produce any field curvature, so the imaging quality of the peripheral field of view of the system is significantly improved; at the same time, the lens in this embodiment is made of easy-to-process plastic material, which further reduces the The size of the system enables the micro-display eyepiece to meet the market demand for light weight, miniaturization, and large field of view.

Another embodiment of the present invention provides a head-mounted device using the micro-display eyepiece provided by the above technical solution.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (8)

1. A kind of micro display eyepiece, it is characterized in that, comprise the first positive lens and the second positive lens, described first positive lens and the second positive lens are arranged successively against the direction of light incident, described first positive lens and The second positive lens is made of plastic; The first positive lens has a first surface facing the image side and a second surface facing the object side; The second positive lens has a third surface facing the image side and a fourth surface facing the object side; Wherein, the second surface and the third surface are diffractive surfaces with positive refractive power, and the first surface and the fourth surface are aspheric surfaces. 2. microdisplay eyepiece according to claim 1, is characterized in that, The first surface of the first positive lens is convex to the image side, and the central position of the second surface is convex to the object side; The third surface of the second positive lens is convex toward the image side, and the central position of the fourth surface is convex toward the object side. 3 . The microdisplay eyepiece according to claim 1 , wherein the diffractive surface of the second surface and the diffractive surface of the third surface have the same surface type. 4 . 4. The micro-display eyepiece according to claim 2, wherein the upper and lower end faces of the first positive lens and the second positive lens are planes. 5. microdisplay eyepiece according to claim 1, is characterized in that, The refractive index range of the first positive lens is 1.45<n ₁ <1.70, and the dispersion range is 50<v ₁ <75; The second positive lens has a refractive index range of 1.45<n ₂ <1.75, and a dispersion range of 25<v ₂ <40. 6. The micro-display eyepiece according to any one of claims 1-5, characterized in that the size of the light-emitting screen of the micro-display eyepiece is less than 1 inch. 7. The micro-display eyepiece according to claim 6, wherein the diaphragm of the micro-display eyepiece is the pupil of a human eye, and the distance from the first surface is 10mm. 8. A head-mounted device, characterized in that the head-mounted device comprises the micro-display eyepiece according to any one of claims 1-7.