An airborne head-up display with red-green dual color display

Abstract

The utility model discloses an airborne head-up display with red and green double-color display. Including green image source, red image source and optical path system, optical path system is by collimating lens I, polarizing beam splitter PBS, collimating lens II, reflector, collimating lens III and half -transparent half -mirror is constituteed, green image source and red image source are placed respectively at the both sides of polarizing beam splitter PBS, and the angle of two image sources display image plane is 90 DEG, and the 0 degree polarized light that green image source sent is penetrated polarizing beam splitter PBS after collimating lens I, and is observed to human eye finally on half -transparent half -mirror after collimating lens III after reflecting mirror reflection, and the 90 degree polarized light that red image source sent is deflected after collimating lens II after polarizing beam splitter PBS and is incident to reflector with the same angle, and is observed to human eye finally on half -transparent half -mirror after collimating lens II after reflecting mirror reflection. The utility model discloses increased red display function, is helpful to pilot for the understanding of information, has improved the flight safety of airplane in special environment.

Description

Technical Field

[0001] This utility model belongs to the field of airborne head-up display, specifically relating to an airborne head-up display with red and green dual-color display. Background Technology

[0002] The head-up display (HUD) uses a high-resolution digital image source and, through a specific optical path design, overlays flight safety and combat information onto the cockpit view, presenting it at infinity directly in front of the pilot. This allows the pilot to obtain critical combat information without looking down, thereby improving the fighter jet's combat performance. The principle of the HUD is as follows: Figure 1 As shown.

[0003] A head-up display (HUD) is a visual system, and the human eye is most sensitive to yellow-green light, while its sensitivity to red and violet light is weaker. Whether in photopic or scotopic vision, the spectral response is strongest in the green band. Therefore, the design of airborne HUDs must select green as the display color, with the center wavelength typically chosen to be 507 nm to 555 nm.

[0004] Currently, both domestically and internationally, mass-produced airborne head-up displays (HUDs) all use a single green digital image source. However, a single color is not conducive to pilots' understanding of information. Red light has a longer wavelength and is easier to see. Using a dual-color red-green display can distinguish warning information, helping pilots to detect warning information earlier or more easily.

[0005] During night flights, pilots experience visual fatigue from prolonged observation of green characters on the head-up display. Red light, with its longer wavelength, is less stimulating to the eyes and can help reduce pilot fatigue in low-light or nighttime environments, potentially enhancing operational capabilities. Furthermore, red light can reduce the separation of retinaldehyde from proteins, minimizing bleaching and thus accelerating dark adaptation, which contributes to improved flight safety in alternating light and dark environments.

[0006] Due to the limitations of light utilization in head-up display (HUD) systems, the image source brightness needs to exceed 45,000 nits to meet the design requirements of airborne HUDs. To achieve a dual-color (red-green) HUD display, a research institute designed an image source integrating both red and green backlights; the red backlight is activated during night flights, while the green backlight activates in bright environments. However, this design has several drawbacks. First, because it has two backlight systems, the red and green colors cannot be displayed simultaneously on the HUD. Second, the presence of the red backlight occupies half of the backlight system's luminous surface, preventing the green display from reaching the 45,000 nits brightness requirement. Third, the existence of two backlight systems inevitably increases the spacing between LEDs of the same color, requiring an increase in the backlight mixing space to ensure display quality, thus increasing the image source's size. Utility Model Content

[0007] The purpose of this invention is to provide an airborne head-up display with red and green dual-color display. Compared with the current head-up displays, it adds a red display function, which helps the pilot understand the information and improves the flight safety of the aircraft in special environments.

[0008] The technical solution to achieve the purpose of this utility model is: an airborne head-up display with red and green dual-color display, including a green image source, a red image source and an optical path system, wherein the optical path system is composed of a collimating lens I, a polarizing beam splitter PBS, a collimating lens II, a reflecting mirror, a collimating lens III and a semi-transparent and semi-reflective mirror;

[0009] The green and red image sources are placed on either side of the polarizing beam splitter PBS, with the image planes of the two sources at an angle of 90°. The 0° polarized light emitted from the green image source passes through the polarizing beam splitter PBS after collimating lens I, is reflected by the mirror, and then passes through collimating lens III before being observed by the human eye on the semi-transparent mirror. The 90° polarized light emitted from the red image source passes through collimating lens II, is deflected by the polarizing beam splitter PBS, and then enters the mirror at the same angle. After being reflected by the mirror, it passes through collimating lens III before being observed by the human eye on the semi-transparent mirror.

[0010] Furthermore, the light rays emitted from the same position of the green and red image sources overlap on the semi-transparent mirror after passing through the optical path system.

[0011] Furthermore, the green image source includes a liquid crystal display, an optical film, a backlight cavity, and an LED array.

[0012] Multiple green LEDs are arranged in a vertical and horizontal array at the bottom of the backlight cavity to form an LED array. The opening of the backlight cavity is provided with an optical film and an LCD screen in sequence.

[0013] Furthermore, the peak wavelength of the green LED is 525nm±3, and the half-width at half maximum (WHM) is no greater than 32nm; the package size of each LED is 3mm*3mm or 5mm*5mm, and the luminous flux is greater than 55lm@100mA.

[0014] The backlight design of the green light source is as follows: the spacing between adjacent LEDs is A1 and A2, A1 and A2 are no greater than 2mm, and the distance from the LED light-emitting surface to the lower surface of the optical film is P≤A / 1.2, where A is the larger value between A1 and A2;

[0015] The LCD screen is a 3.8-inch monochrome LCD screen with a resolution of 1280*1024, a transmittance of not less than 20%, and an effective display area of ​​74mm*57mm.

[0016] Furthermore, the backlight cavity of the green image source (1) is covered with a material with a diffuse reflectance greater than 99% as a reflective film, and a material with a diffuse reflectance greater than 99% is covered in the gap between the LED light sources as a reflective film; the upper polarization of the LCD screen adopts a polarizer with an absorption axis of 0°, and the lower polarization adopts a polarizer with an absorption axis of 90°.

[0017] Furthermore, the red image source includes a liquid crystal display, an optical film, a backlight cavity, and a light-emitting diode array.

[0018] Each red LED has a package size of 3mm*3mm or 5mm*5mm and a luminous flux greater than 30lm@100mA; the digital image source uses a 3.8-inch monochrome LCD screen with a resolution of 1280*1024, a transmittance of not less than 20%, and an effective display area of ​​74mm*57mm.

[0019] The backlight design of the red image source is the same as that of the green light source;

[0020] The sidewalls of the red image source backlight cavity are coated with a material with a diffuse reflectivity greater than 99% as a reflective film, and the gaps between the diodes are coated with a material with a diffuse reflectivity greater than 99% as a reflective film.

[0021] The upper polarizer of the LCD screen uses a polarizer with an absorption axis of 90°, and the lower polarizer uses a polarizer with an absorption axis of 0°.

[0022] Furthermore, the extinction ratio of the polarizing beam splitter (PBS) is not less than 1000:1.

[0023] The wavefront aberration of collimating lens I, collimating lens II and collimating lens III is no greater than λ / 10@632.8nm, the transmittance is no less than 99.5% and the stress birefringence is less than 5nm / cm;

[0024] Semi-transparent mirrors have a reflectivity of 15%-30% and a transmittance of 70%-85% in the visible light band.

[0025] Compared with the prior art, the significant advantages of this utility model are:

[0026] By utilizing the principle of polarized light reflection, digital image source light sources for red and green display colors are integrated into the same optical system, thus creating an airborne head-up display capable of displaying red and green dual colors.

[0027] The airborne head-up display designed and manufactured by this invention can realize red and green dual-color display, which can improve the pilot's ability to perceive information, effectively reduce the pilot's visual fatigue and dark adaptation speed in special environments, and improve flight safety and combat level. Attached Figure Description

[0028] Figure 1This is a schematic diagram of a head-up display (HUD) based on existing technology.

[0029] Figure 2 This is a schematic diagram of the digital image source structure of this utility model.

[0030] Figure 3 This is a diagram of an LED array.

[0031] Figure 4 This utility model relates to an airborne head-up display with red and green dual-color display.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-Green image source, 2-Collimating lens I, 3-Polarizing beam splitter PBS, 4-Red image source, 5-Collimating lens II, 6-Reflector, 7-Collimating lens III, 8-Semi-transparent and semi-reflective mirror, 9-LCD screen, 10-Optical film, 11-Backlight cavity, 12-LED array. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings.

[0035] By using two image sources with different display colors and controlling the polarization state of the light emitted from the image sources, an off-axis dual-optical-path system was designed to simultaneously project two different colored light beams into the pilot's eyes, thus realizing an airborne head-up display with simultaneous red and green color display.

[0036] 1. Green digital image source design:

[0037] 1.1 Material Selection:

[0038] Digital image sources contain core components such as backlight cavity, LED array, optical film, and LCD screen. Their relative positions are as follows: Figure 2 As shown. 9 is an LCD screen, 10 is an optical film, 11 is a backlight cavity, and 12 is an LED array.

[0039] Green LEDs with a peak wavelength of 525nm±3 and a half-width at half-maximum of 32nm are selected as the light source for the digital image source. The LED package size is 3mm*3mm or 5mm*5mm, and the luminous flux is greater than 55lm@100mA. The LCD screen of the digital image source is a 3.8-inch monochrome LCD screen with a resolution of 1280*1024 manufactured by Tianma, with a transmittance of not less than 20% and an effective display area of ​​74mm*57mm.

[0040] 1.2 Backlight Design: The opening of the backlight cavity is the same size as the effective display area of ​​the LCD screen, and the LEDs should be evenly soldered to the bottom of the backlight cavity. The spacing between LEDs, A1 and A2, should not exceed 2mm. The mixing space of the digital image source, i.e., the distance P from the LED light-emitting surface to the lower surface of the optical film, should be ≤ A / 1.2, where A is the larger value between A1 and A2.

[0041] 1.3 Pre-treatment of backlight cavity: Apply a material with a diffuse reflectance greater than 99%, such as DRP reflective film, to the side wall of the backlight cavity, and apply a material with a diffuse reflectance greater than 99%, such as DRP reflective film, to the gap between LED light sources.

[0042] 1.4 Digital image source surface design: The upper polarizer of the LCD screen adopts a polarizer with an absorption axis of 0°, and the lower polarizer adopts a polarizer with an absorption axis of 90°.

[0043] 2. Red digital image source design:

[0044] 2.1 A red light-emitting diode (LED) is selected as the light source for the digital image source. The package size of the light source is 3mm*3mm or 5mm*5mm, and the luminous flux is greater than 30lm@100mA. The display medium for the digital image source is a 3.8-inch monochrome LCD screen with a resolution of 1280*1024 manufactured by Tianma, with a transmittance of not less than 20% and an effective display area of ​​74mm*57mm.

[0045] 2.2 Backlight design: such as Figure 2 , 3 The backlight design shown is the same as that of the green image source, the only difference being the different color of the LED light emission.

[0046] 2.3 Pre-treatment of backlight cavity: Apply a material with a diffuse reflectance greater than 99%, such as DRP reflective film, to the side wall of the backlight cavity, and apply a material with a diffuse reflectance greater than 99%, such as DRP reflective film, to the gap between the diodes.

[0047] 2.4 Digital image source surface design: The upper polarizer of the LCD screen adopts a polarizer with an absorption axis of 90°, and the lower polarizer adopts a polarizer with an absorption axis of 0°.

[0048] 3. Optical Path Design: A polarizing beam splitter PBS3 with an extinction ratio of not less than 1000:1 is introduced into the optical path. The red and green image sources are placed on either side of the polarizing beam splitter PBS3, with the image planes of the two sources displaying an angle of 90°. Figure 4 As shown, the 0° polarized light emitted from the green image source 1 passes through the collimating lens I2, then through the polarizing beam splitter PBS3, and is reflected by the reflecting mirror 6 with a reflectivity of not less than 98%, finally being observed by the human eye on the semi-transparent mirror. Similarly, the 90° polarized light emitted from the red image source is deflected after passing through the PBS and enters the semi-transparent mirror 8 at the same angle, ultimately being observed by the human eye.

[0049] Collimating lens I (2), collimating lens II (5), and collimating lens III (7) have wavefront aberrations not greater than λ / 10@632.8nm, transmittance not less than 99.5%, and stress birefringence less than 5nm / cm. Semi-transparent mirror (8) has a reflectance between 15% and 30% and a transmittance between 70% and 85% in the visible light band.

[0050] 4. Assembly Requirements: The two image sources work together to display graphics or characters. The two colors of light must maintain the same incident and exit angles in the optical path; otherwise, light mixing may occur, leading to color shift. Therefore, during design and assembly, it is essential to ensure that the centers of the image surfaces of the two digital image sources are in the same position, meaning that the light emitted from the same position will overlap on the semi-transparent mirror 8 after passing through the optical path.

Claims

1. An airborne head-up display with red and green dual-color display, characterized in that, It includes a green image source (1), a red image source (4) and an optical path system, wherein the optical path system consists of a collimating lens I (2), a polarizing beam splitter PBS (3), a collimating lens II (5), a reflecting mirror (6), a collimating lens III (7) and a semi-transparent and semi-reflective mirror (8); The green image source (1) and the red image source (4) are placed on both sides of the polarizing beam splitter PBS (3). The image planes of the two image sources are 90° apart. The 0° polarized light emitted by the green image source (1) passes through the collimating lens I (2) and then through the polarizing beam splitter PBS (3). After being reflected by the mirror (6), it passes through the collimating lens III (7) and is finally observed by the human eye on the semi-transparent mirror (8). The 90° polarized light emitted by the red image source (4) is collimated by the collimating lens II (5) and then refracted by the polarizing beam splitter PBS (3) to enter the reflecting mirror (6) at the same angle. After being reflected by the reflecting mirror (6), it passes through the collimating lens III (7) and is finally observed by the human eye on the semi-transparent mirror (8).

2. The display according to claim 1, characterized in that, The light emitted from the green image source (1) and the red image source (4) at the same position coincides on the semi-transparent mirror (8) after passing through the optical path system.

3. The display according to claim 2, characterized in that, The green image source (1) includes a liquid crystal screen (9), an optical film (10), a backlight cavity (11), and an LED array (12). Multiple green LEDs are arranged in a vertical and horizontal array at the bottom of the backlight cavity (11) to form an LED array (12). The opening of the backlight cavity (11) is provided with an optical film (10) and a liquid crystal screen (9) in sequence.

4. The display according to claim 3, characterized in that, The peak wavelength of the green LED is 525nm±3, and the half-width at half maximum (WHM) is no greater than 32nm. The package size of each LED is 3mm*3mm or 5mm*5mm, and the luminous flux is greater than 55lm@100mA. The backlight design of the green light source is as follows: the interval between adjacent LEDs is A1 and A2, A1 and A2 are not greater than 2mm, and the distance from the LED light-emitting surface to the lower surface of the optical film (10) is P≤A / 1.2, where A is the larger value between A1 and A2; The LCD screen is a 3.8-inch monochrome LCD screen with a resolution of 1280*1024, a transmittance of not less than 20%, and an effective display area of ​​74mm*57mm.

5. The display according to claim 4, characterized in that, The backlight cavity of the green image source (1) is covered with a material with a diffuse reflectance greater than 99% as a reflective film, and a material with a diffuse reflectance greater than 99% is covered in the gap between the LED light sources as a reflective film; the upper polarization of the liquid crystal screen (9) adopts a polarizer with an absorption axis of 0°, and the lower polarization adopts a polarizer with an absorption axis of 90°.

6. The display according to claim 2, characterized in that, The red image source (4) includes a liquid crystal screen, an optical film, a backlight cavity, and a light-emitting diode array. Each red LED has a package size of 3mm*3mm or 5mm*5mm and a luminous flux greater than 30lm@100mA; the digital image source uses a 3.8-inch monochrome LCD screen with a resolution of 1280*1024, a transmittance of not less than 20%, and an effective display area of ​​74mm*57mm. The backlight design of the red image source (4) is the same as that of the green light source; The red image source (4) has a material with a diffuse reflectance greater than 99% attached to the side wall of the backlight cavity as a reflective film, and a material with a diffuse reflectance greater than 99% attached to the gap between the diodes as a reflective film. The upper polarizer of the LCD screen uses a polarizer with an absorption axis of 90°, and the lower polarizer uses a polarizer with an absorption axis of 0°.

7. The display according to claim 1, characterized in that, The extinction ratio of the polarizing beam splitter PBS (3) is not less than 1000:1, the wavefront aberration of collimating lens I (2), collimating lens II (5) and collimating lens III (7) is not greater than λ / 10@632.8nm, the transmittance is not less than 99.5%, and the stress birefringence is less than 5nm / cm; The semi-transparent and semi-reflective mirror (8) has a reflectivity of 15%-30% and a transmittance of 70%-85% in the visible light band.

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