Image generation device and head-up display

Abstract

The embodiment of the present application provides an image generating device and a head-up display. The image generating device comprises a projection lens and a projection surface located on the light exit side of the projection lens. The projection lens comprises a fixed lens group and a movable lens group. The movable lens group can move along the optical axis of the projection lens. The position of the projection surface is adjusted according to the projection distance range, so that the head-up display projects virtual images with different virtual image distances.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of display, and more particularly, to an image generating device and a head-up display. BACKGROUND

[0002] With the continuous progress of the automotive industry, to ensure the safety and comfort during driving has been significantly improved, the head-up display system (HUD) has been introduced into the automotive intelligent cockpit design. However, the HUD systems on the current market generally adopt a fixed virtual image distance setting, which limits the ability of the HUD to provide more optimized driving experience for users in different driving environments. In addition, the clarity of the projection face display picture in the traditional head-up display is not high, which affects the projection quality.

[0003] Therefore, there is a need to provide a new technical solution to solve the above technical problems. SUMMARY

[0004] The purpose of the present application is to provide a new technical solution of an image generating device and a head-up display.

[0005] The present application provides an image generating device. The image generating device is applied to a head-up display, a projection lens and a projection face located on the light emitting side of the projection lens.

[0006] The projection lens comprises a fixed lens group and a movable lens group, the movable lens group can move along the optical axis of the projection lens, and the position of the projection face is adjusted according to the projection distance range, so that the head-up display projects virtual images with different virtual image distances.

[0007] Optionally, the movable lens group is located on the light emitting side of the fixed lens group, or the movable lens group is located on the light incident side of the fixed lens group.

[0008] Optionally, the lens of the movable lens group farthest from the fixed lens group is an aspherical lens.

[0009] Optionally, the movable lens group is located on the light emitting side of the fixed lens group, the overall optical power of the movable lens group is negative, and the overall optical power of the fixed lens group is positive.

[0010] Optionally, the movable lens group is located on the light incident side of the fixed lens group, the overall optical power of the movable lens group is positive, and the overall optical power of the fixed lens group is negative.

[0011] Optionally, the projection distance range between the projection face and the projection lens satisfies: 120mm≤T≤140mm.

[0012] Optionally, the movable lens group is located on the light-outgoing side of the fixed lens group, and a distance T1 between the movable lens group and two lenses adjacent to each other in the fixed lens group satisfies 3.15 mm < T1 < 3.35 mm.

[0013] Optionally, the projection lens further comprises an equivalent prism, the movable lens group is located on the light-outgoing side of the equivalent prism, and a distance T2 between a lens in the movable lens group farthest from the fixed lens group and the equivalent prism satisfies 5.5 mm < T2 < 5.9 mm.

[0014] Optionally, the movable lens group is located on the light-incoming side of the fixed lens group, and a distance T3 between the movable lens group and two lenses adjacent to each other in the fixed lens group satisfies 0.01 mm < T3 < 0.2 mm.

[0015] Optionally, an aperture of the lens closest to the projection surface of the projection lens is D1, and an effective focal length of the projection lens is EFL, where D1 / EFL < 0.95.

[0016] Optionally, a total length of the projection lens is TTL, and an effective focal length of the projection lens is EFL, where TTL / EFL < 4.5.

[0017] Optionally, the projection lens further comprises an adjusting mechanism, a non-effective area of a lens in the movable lens group is arranged in the adjusting mechanism, and the adjusting mechanism drives the movable lens group to move along the optical axis of the projection lens.

[0018] Optionally, the adjusting mechanism comprises a main body part, a recessed groove is formed on a side of the main body part facing the movable lens group, and a sliding groove is arranged in the recessed groove;

[0019] The adjusting mechanism further comprises a sliding part, the non-effective area of the lens in the movable lens group is connected with the sliding part, the sliding part is at least partially located in the recessed groove, and the sliding part is embedded in the sliding groove to drive the movable lens group to move along the optical axis of the projection lens.

[0020] Optionally, the projection lens comprises, in sequence along the optical axis, a fifth lens, a fourth lens, a third lens, a second lens and a first lens, the first lens is arranged adjacent to the projection surface, and optical powers of the fifth lens, the fourth lens, the third lens, the second lens and the first lens are, in sequence, positive, positive, negative, positive and negative; the first lens is configured to be movable along the optical axis, or the fifth lens is configured to be movable along the optical axis.

[0021] Optionally, the projection distance range between the first lens and the projection surface satisfies 120 mm ≤ T ≤ 140 mm.

[0022] Optionally, the first lens is an aspherical lens, and the fifth lens is an aspherical lens.

[0023] Optionally, in the case that the first lens is configured to be movable along the optical axis, a distance T1 between the first lens and the second lens satisfies: 3.15mm < T1 < 3.35mm.

[0024] Optionally, in the case that the fifth lens is configured to be movable along the optical axis, a distance T3 between the fifth lens and the fourth lens satisfies: 0.01mm < T3 < 0.2mm.

[0025] Optionally, the projection lens further comprises an equivalent prism, the fifth lens is configured to be movable along the optical axis, and a distance T2 between the fifth lens and the equivalent prism satisfies: 5.5mm < T2 < 5.9mm.

[0026] Optionally, the projection lens satisfies: -1.1 < EFL / f1 < -0.95; 0.95 < EFL / f2 < 1.05; -1.25 < EFL / f3 < -1.15; 0.93 < EFL / f4 < 0.98; 0.65 < EFL / f5 < 0.75;

[0027] wherein EFL is an effective focal length of the projection lens, f1 is a focal length of the first lens, f2 is a focal length of the second lens, f3 is a focal length of the third lens, f4 is a focal length of the fourth lens, and f5 is a focal length of the fifth lens.

[0028] Optionally, the third lens and the fourth lens are cemented to form a cemented lens group.

[0029] In a second aspect, the embodiments of the present application further provide a head-up display. The head-up display comprises the image generating device according to the first aspect.

[0030] According to the embodiments of the present application, the projection lens in the image generating device comprises a movable lens group, the movable lens group is movable along the optical axis of the projection lens, and the projection surface adjusts its setting position within the projection distance range, which can ensure that the projection surface displays a picture with relatively high definition, and on the other hand, the image generating device is applied to the head-up display, and the head-up display can project a virtual picture with different virtual image distances.

[0031] Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present specification and, together with the description, serve to explain the principles of the present specification.

[0033] Figure 1 A light path schematic of a projection lens provided by an embodiment of the present application is shown. Figure 1 .

[0034] Figure 2 A structure of a projection lens provided by an embodiment of the present application is shown. Figure 1 .

[0035] Figures 3a to 3e A light path schematic of a projection lens provided by an embodiment of the present application is shown. Figure 2 MTF diagrams of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm.

[0036] Figures 4a to 4e A field curvature / distortion diagram of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm. Figure 2 MTF diagrams of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm.

[0037] Figure 5 A field curvature / distortion diagram of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm. Figure 2 A curve diagram of the change of the position of the first lens relative to the second lens of the projection lens shown when the projection distance changes every 2mm from 120mm to 140mm.

[0038] Figure 6 A light path schematic of a projection lens provided by an embodiment of the present application is shown. Figure 2 .

[0039] Figure 7 A structure of a projection lens provided by an embodiment of the present application is shown. Figure 2 .

[0040] Figures 8a to 8e A light path schematic of a projection lens provided by an embodiment of the present application is shown. Figure 7 MTF diagrams of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm.

[0041] Figures 9a to 9e A field curvature / distortion diagram of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm. Figure 7 MTF diagrams of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm.

[0042] Figure 10 A field curvature / distortion diagram of the projection lens shown when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm. Figure 7 A curve diagram of the change of the position of the fifth lens relative to the equivalent prism of the projection lens shown when the projection distance changes every 2mm from 120mm to 140mm.

[0043] Reference numerals:

[0044] 101, movable lens group; 102, fixed lens group;

[0045] 20, first lens; 21, second lens; 22, third lens; 23, fourth lens; 24, fifth lens;

[0046] 31, equivalent prism; 32, protective glass; 33, DMD; 34, diaphragm;

[0047] 4, adjusting mechanism; 41, main body; 42, sliding part;

[0048] 5, projection surface; DETAILED DESCRIPTION

[0049] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps set forth in the examples, as well as the numerical expressions and values, are not limitations on the scope of the present application unless otherwise specifically stated.

[0050] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application, its application, or uses.

[0051] Techniques and equipment known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification where appropriate.

[0052] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0053] It should be noted that like numerals and letters refer to like items throughout the drawings, and once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0054] The image generating device according to the embodiments of the present application is applied to a head-up display. The image generating device of the head-up display is used to generate image information and project it onto a projection surface 5 through a projection lens of the image generating device. In this process, a movable lens group 101 inside the projection lens can be moved flexibly along the optical axis direction. With the movement of the movable lens group 101, the position of the projection surface 5 in the image generating device is also adjusted accordingly. By adjusting the setting positions of the movable lens group 101 and the projection surface 5, effective projection can be achieved within a projection distance range. Due to the change of the position of the projection surface 5, the head-up display flexibly adjusts the distance of the virtual picture (virtual image distance) according to the actual projection distance between the projection surface 5 and the movable lens group 101.

[0055] In the embodiments of this application, reference is made to Figure 1 and Figure 2 as well as Figure 6 and Figure 7 The image generating device includes a projection lens and a projection surface 5 located on the light-emitting side of the projection lens. The projection lens includes a fixed lens group 102 and a movable lens group 101; the movable lens group 101 can move along the optical axis of the projection lens and adjust the position of the projection surface 5 according to the projection distance range, so that the head-up display projects virtual images with different virtual image distances.

[0056] In this embodiment, the image generating device mainly includes a projection lens and a projection surface 5. The projection lens is responsible for projecting image information, while the projection surface 5, located on its light-emitting side, is responsible for receiving and displaying the image information. In the head-up display, the projection surface 5 emits light carrying image information, which, after being reflected by a reflective component, forms a virtual image on the side of the vehicle's windshield away from the viewer's eyes. Exemplarily, the image generating device also includes a lighting system and a display chip. The type of image generating device may be, but is not limited to, a DLP-type image generating device or an LCOS-type image generating device.

[0057] The projection lens includes a fixed lens group 102 and a movable lens group 101, the movable lens group 101 being movable relative to the fixed lens group 102 along the optical axis. Figure 2 The direction indicated by the arrow or Figure 7 (Indicated by the arrow). For example, the movable lens group 101 can be the lens group closest to the projection surface 5, or the lens group furthest from the projection surface 5, or the lens group located in the middle of all the lenses of the projection lens (in this case, the movable lens group is located between two fixed lens groups). Regardless of the position of the movable lens group 101 within the projection lens, as long as the position of the projection surface 5 can be adjusted within the projection distance range, the movement of the movable lens group 101 can compensate for the display quality of the image displayed on the projection surface 5. That is, by moving the position of the movable lens group 101, the quality of the image displayed on the projection surface 5 can be improved, thereby improving the quality of the virtual image projected by the HUD.

[0058] Preferably, refer to Figure 2 and Figure 7 In the projection lens, in order to facilitate the movement of the movable lens group 101 and to better improve the quality of the image displayed on the projection surface 5 by moving the movable lens group 101, the movable lens group 101 can be the lens group closest to the projection surface 5, or the movable lens group 101 can be the lens group furthest from the projection surface 5.

[0059] During the movement of the movable lens group 101 along the optical axis of the projection lens, the projection lens realizes zooming, in order to ensure the clarity of the picture displayed on the projection surface 5, the position of the projection surface 5 is adjusted within the projection distance range, so that a picture with higher clarity can be displayed on the projection surface 5 during the focusing of the projection lens.

[0060] Since the position of the projection surface 5 changes due to the movement of the movable lens group 101, the distance between the projection surface 5 and the reflection assembly in the head-up display is indirectly adjusted, when the distance between the projection surface 5 and the reflection assembly in the head-up display is adjusted, the transmission path of the outgoing light of the projection surface 5 and the incident angle of the outgoing light are changed, so that the head-up display can project a virtual picture with different virtual image distances. For example, referring to Figure 1 and Figure 6 , the projection surface 5 moves from the A position to the B position, and the virtual image distance of the virtual picture projected by the head-up display gradually increases; or the projection surface 5 moves from the B position to the A position, and the virtual image distance of the virtual picture projected by the head-up display gradually decreases.

[0061] Specifically, during the movement of the movable lens group 101 along the optical axis of the projection lens, the projection surface 5 moves closer to or farther away from the projection lens, according to the imaging law, when the projection surface 5 moves closer to the projection lens, that is, the projection surface 5 moves farther away from the reflection assembly of the head-up display, the virtual image distance presented on the front windshield to the driver is farther (the virtual image distance is farther); when the projection surface 5 moves away from the projection lens, that is, the projection surface 5 moves closer to the reflection assembly of the head-up display, the virtual image distance presented on the front windshield to the driver is closer (the virtual image distance is shorter), so that the driver can adjust the distance of the virtual image presented on the front windshield according to his own driving habits and driving conditions.

[0062] For example, the movable lens group 101 can continuously move along the optical axis of the projection lens, and the position of the projection surface 5 (i.e. the projection surface) of the image generating device also continuously changes, so that the head-up display can project a continuous virtual picture, and the continuous virtual picture has different virtual image distances.

[0063] Therefore, in this embodiment, the projection lens in the image generating device includes the movable lens group 101, the movable lens group 101 can move along the optical axis of the projection lens, and the projection surface 5 adjusts its setting position within the projection distance range, which can ensure that the projection surface 5 displays a picture with higher clarity, and on the other hand, the image generating device is applied to the head-up display, and the head-up display can project a virtual picture with different virtual image distances.

[0064] In a specific embodiment, the setting position of the movable lens group 101 in the projection lens is limited, specifically, referring to Figure 1 and Figure 2The movable lens group 101 is located on the light-out side of the fixed lens group 102. Alternatively, referring to Figure 6 and Figure 7 The movable lens group 101 is located on the light-in side of the fixed lens group 102, i.e. the fixed lens group 102 is located on the light-out side of the movable lens group 101.

[0065] In one example, referring to Figure 1 and Figure 2 In the image generating device, the movable lens group 101 and the projection surface 5 are oppositely arranged, so that the arrangement of the projection surface 5 (the actual projection distance between the projection surface 5 and the projection lens) can be adjusted within a projection distance range by the flexible movement of the movable lens group 101, so that the projection surface 5 can display a picture with higher definition. The projection distance range is related to the type of the image generating device, the virtual image distance of the virtual picture to be projected by the head-up display, and other parameters. That is, in this embodiment, the movable lens group 101 is arranged behind the fixed lens group 102, i.e. the light first passes through the fixed lens group 102 and then passes through the movable lens group 101. This arrangement can be used to adjust the focusing or direction of the light so that the projection surface 5 displays a clear picture within the projection distance range.

[0066] In another example, referring to Figure 6 and Figure 7 In the image generating device, the movable lens group 101 is actually oppositely arranged with the equivalent prism 31 in the projection lens, i.e. the movable lens group 101 is arranged before the fixed lens group 102, i.e. the light first passes through the movable lens group 101 and then passes through the fixed lens group 102. This arrangement is used to pre-process the light by the movable lens group 101 before the light enters the fixed lens group, such as adjusting the angle or intensity of the light, so that the light emitted by the projection lens is projected to the projection surface 5, and the projection surface 5 displays a clear picture within the projection distance range.

[0067] In one embodiment, referring to Figure 1 and Figure 2 and Figure 6 and Figure 7 The lens of the movable lens group 101 farthest from the fixed lens group 102 is an aspherical lens.

[0068] Specifically, in the projection lens, the lens of the projection lens closest to the projection surface 5 is an aspherical lens, and the lens of the projection lens farthest from the projection surface 5 is an aspherical lens. By optimizing the shape of the curved surface, the aspherical lens can more effectively focus the light, reduce or eliminate aberrations, including spherical aberration, chromatic aberration, etc., thereby providing higher quality images.

[0069] In addition, in the case that the lens closest to the projection surface 5 in the projection lens is an aspherical lens, and the lens farthest from the projection surface 5 in the projection lens is an aspherical lens, the movable lens group 101 is arranged on the light-outgoing side or the light-entering side of the fixed lens group 102, that is, by adjusting the arrangement position of the movable lens group 101 containing the aspherical lens, the virtual image distance of the virtual image projected by the head-up display can be adjusted in coordination with the adjustment of the position of the projection surface 5, while ensuring that the projection surface 5 displays a high-definition image.

[0070] In one embodiment, referring to Figure 1 and Figure 2 , the movable lens group 101 is arranged on the light-outgoing side of the fixed lens group 102, the overall optical power of the movable lens group 101 is negative, and the overall optical power of the fixed lens group 102 is positive.

[0071] In this embodiment, the position of the projection surface 5 of the image generating device changes during the movement of the movable lens group 101 along the optical axis in the projection lens. By limiting the overall optical power of the movable lens group 101 and the overall optical power of the fixed lens group 102, the actual projection distance between the projection lens and the projection surface 5 can be ensured to be within the projection distance range, and the projection surface 5 can clearly project.

[0072] Specifically, the overall optical power of the movable lens group 101 is negative, and the movable lens group 101 has the characteristic of diverging light rays. In the projection lens, a lens group with negative optical power is usually used to adjust the focal length or correct aberrations.

[0073] Due to the negative optical power characteristic of the movable lens group 101, when the movable lens group 101 moves along the optical axis, the degree of divergence of the light rays passing through the movable lens group 101 changes, thereby affecting the focal length and clarity of the projected image.

[0074] The optical power of the fixed lens group 102 is positive, and the fixed lens group 102 as a whole has the characteristic of converging light rays. In the projection lens, a lens group with positive optical power is usually used to focus light rays to a specific position, such as the projection surface 5 (i.e., the projection surface).

[0075] In the projection lens, the combination of the movable lens group 101 and the fixed lens group 102 can achieve adjustment of the projection distance and clarity. When the movable lens group 101 moves along the optical axis, it changes the total focal length of the projection lens and the total length of the lens group inside the lens, thereby affecting the position and size of the projected image on the projection surface. By limiting the optical power of the movable lens group 101 and the fixed lens group 102 and their relative positions, it can be ensured that within the projection distance range, the projection lens can clearly project an image.

[0076] In another embodiment, referring to Figure 6 andFigure 7 The fixed lens group 102 is located on the light exit side of the movable lens group 101, the overall optical power of the movable lens group 101 is positive, and the overall optical power of the fixed lens group 102 is negative.

[0077] In this embodiment, the movable lens group 101 has positive optical power and converges light rays. In a projection lens, a movable lens group 101 with positive optical power is usually used for zoom, focus adjustment, or aberration correction. Since the movable lens group 101 is movable, it can adapt to different projection requirements by moving, such as changing the projection distance, and the projection surface 5 displays a clear picture within the projection distance range.

[0078] The fixed lens group 102 has negative optical power and diverges light rays. In a projection lens, a fixed lens group 102 with negative optical power is usually used to further correct aberrations, adjust light distribution, or achieve specific projection effects. Since the fixed lens group 102 is fixedly arranged, it provides stable optical performance, which helps to ensure the clarity and quality of the projected picture.

[0079] In one embodiment, the projection distance range between the projection surface 5 and the projection lens is 120mm≤T≤140mm.

[0080] Specifically, the range of the projection distance between the projection surface 5 and the projection lens is defined, that is, within this projection distance range, the movable lens group 101 of the projection lens moves along the optical axis, which can ensure the clarity requirement of the picture displayed by the projection surface 5.

[0081] Illustratively, based on the type of image generating device, the projection distance range between the projection surface 5 and the projection lens can be defined. Taking DLP as an example, according to the effective focal length of the projection lens, the picture size and the DLP chip size requirement, the projection distance range of DLP can be defined, and the projection distance range between the projection surface 5 and the projection lens is defined according to the projection distance range of DLP.

[0082] The projection distance range of 120mm-140mm meets the requirements of most image generating device products, and is applied to head-up displays, which can realize near distance virtual image display (e.g. about 4.5m) or even 20m or more distance virtual image display (far distance virtual image display).

[0083] Further, on the basis that the projection distance T between the projection surface 5 and the projection lens meets the above range, the movable lens group 101 is located on the light exit side of the fixed lens group 102, and the distance T1 between the movable lens group 101 and the two lenses arranged adjacent to each other in the fixed lens group 102 meets: 3.15mm<T1<3.35mm.

[0084] In this embodiment, the distance T1 between the active lens group 101 and the two lenses adjacent to each other in the fixed lens group 102 determines the imaging quality of the projection lens to a certain extent. During the movement of the active lens group 101 along the optical axis, the distance T1 between the active lens group 101 and the two lenses adjacent to each other in the fixed lens group 102 satisfies: 3.15mm < T1 < 3.35mm, which can ensure the clarity, contrast and color restoration of the projection picture to a certain extent.

[0085] In addition, the projection distance T between the projection lens and the projection surface 5 and the distance T1 between the active lens group 101 and the two lenses adjacent to each other in the fixed lens group 102 jointly affect the performance of the image generating device. The projection distance T mainly determines the size and clarity of the projection picture, while T1 more affects the imaging quality and stability inside the projection lens. Under the combination of the two, the clarity requirement of the picture displayed on the projection surface 5 can be ensured.

[0086] In another embodiment, referring to Figure 1 and Figure 2 , the projection lens further comprises an equivalent prism 31, and the active lens group 101 is located on the light exit side of the equivalent prism 31. On the basis that the projection distance T between the projection surface 5 and the projection lens satisfies the above range, the distance T2 between the lens farthest from the fixed lens group 102 in the active lens group 101 and the equivalent prism satisfies: 5.5mm < T2 < 5.9mm.

[0087] In this embodiment, during the movement of the active lens group 101 along the optical axis, the distance T2 between the lens farthest from the fixed lens group 102 in the active lens group 101 and the equivalent prism 31 satisfies: 5.5mm < T2 < 5.9mm, which can ensure the clarity, contrast and color restoration of the projection picture to a certain extent.

[0088] Under the consideration of the limiting conditions of T and T2, on the one hand, the projection surface 5 can display a picture with relatively high clarity, and on the other hand, the head-up display can project a virtual picture with different virtual image distances.

[0089] Please continue to refer to Figure 6 and Figure 7 , on the basis that the projection distance T between the projection surface 5 and the projection lens satisfies the above range, the distance T3 between the active lens group 101 and the two lenses adjacent to each other in the fixed lens group 102 satisfies: 0.01mm < T3 < 0.2mm.

[0090] In this embodiment, the distance T3 between the movable lens group 101 and the two lenses arranged adjacent to each other in the fixed lens group 102 has a direct impact on the optical performance of the projection lens during the movement of the movable lens group 101 along the optical axis. Too small T3 can cause the mutual influence between lenses to be enhanced, increasing the generation of aberration and stray light; while too large T3 can increase the overall length of the lens, which is not conducive to compact design. Therefore, on the basis of combining the projection distance T between the projection surface 5 and the projection lens, T3 is limited within this range, which on the one hand ensures that the projection surface 5 displays a picture with relatively high resolution, and on the other hand the head-up display can project a virtual picture with different virtual image distances.

[0091] In one embodiment, the lens aperture of the projection lens closest to the projection surface 5 is D1, and the effective focal length of the projection lens is EFL, where D1 / EFL < 0.95.

[0092] In this embodiment, D1 generally refers to the effective clear aperture of the lens of the projection lens closest to the projection surface 5. This parameter directly affects the light collection ability and imaging quality of the projection lens. The larger the aperture, the more light can generally be collected, but in some cases it can also increase the volume and weight of the projection lens.

[0093] The effective focal length (EFL) of the projection lens is the distance from the back focal point of the projection lens to the clear imaging point on the projection surface 5 (i.e. the projection surface).

[0094] Specifically, by controlling the ratio of D1 / EFL to be less than 0.95, a smaller aperture D1 relative to a longer effective focal length EFL can reduce the diameter of the front end of the lens, thereby saving space to achieve the purpose of reducing the volume of the head of the projection lens system.

[0095] In one embodiment, the total length of the projection lens is TTL, and the effective focal length of the projection lens is EFL, where TTL / EFL < 4.5.

[0096] In this embodiment, TTL refers to the total length of the lens, i.e. the distance from the front end of the projection lens to the imaging surface (such as a photosensitive element). It includes the space occupied by all lenses, barrels and other optical elements inside the lens.

[0097] By setting TTL / EFL < 4.5, the overall length of the projection lens can be controlled to a certain extent to achieve the purpose of compact design. In addition, while controlling the length, TTL / EFL < 4.5 also helps to optimize the performance of the projection lens. Through reasonable optical design and material selection, good imaging quality and color reproduction can be achieved in a smaller lens volume. In addition, a smaller TTL / EFL ratio can also reduce the aberration and distortion inside the lens, thereby improving the clarity and accuracy of the projected picture.

[0098] In one embodiment, referring to Figure 1 and Figure 2 , the projection lens further comprises an adjusting mechanism 4, a non-effective area of the lens in the movable lens group 101 is arranged in the adjusting mechanism 4, and the adjusting mechanism 4 drives the movable lens group 101 to move along the optical axis of the projection lens.

[0099] In this embodiment, the non-effective area of the lens in the movable lens group 101 is in a connection relationship with the adjusting mechanism 4, and the movable lens group 101 is moved along the optical axis by the adjusting mechanism 4.

[0100] The effective area of the lens refers to the part that can participate in imaging and contribute to the projection quality. The non-effective area refers to the part of the lens other than the effective area, which usually does not directly participate in imaging. Exemplarily, the non-effective area of the lens in the movable lens group 101 is connected with at least part of the adjusting mechanism 4, and the movable lens group 101 is moved along the optical axis without affecting the imaging of the projection lens.

[0101] Exemplarily, the adjusting mechanism 4 drives the movable lens group 101 as a whole to move along the optical axis (i.e. the central axis of the light passing through the lens) of the projection lens by means such as mechanical transmission, electromagnetic drive, etc. This movement can change the position of the projection surface 5 (projection surface) within the projection distance range, so as to adjust the incident angle of the light emitted by the projection surface 5 to the reflection assembly, and according to the different incident angles of the light emitted by the projection surface 5, the head-up display can project virtual pictures with different virtual image distances.

[0102] In one specific embodiment, referring to Figure 6 and Figure 7 , the adjusting mechanism 4 comprises a main body part 41, the main body part 41 is formed with a recessed groove towards the side of the movable lens group 101, and a sliding groove is formed in the recessed groove;

[0103] The adjusting mechanism 4 further comprises a sliding part 42, the non-effective area of the lens in the movable lens group 101 is connected with the sliding part 42, the sliding part 42 is at least partially located in the recessed groove, and the sliding part 42 is embedded in the sliding groove to drive the movable lens group 101 to move along the optical axis of the projection lens.

[0104] In this specific embodiment, when it is necessary to adjust the position of the movable lens group 101, the adjusting mechanism 4 drives the sliding part 42 to move in the sliding groove by means such as manual adjustment or electric drive. The movement of the sliding part 42 drives the movable lens group 101 connected therewith to move along the optical axis of the projection lens.

[0105] When the movable lens group 101 moves along the optical axis under the drive of the sliding part 42, the projection surface 5 adjusts its setting position according to the movement of the movable lens group 101, that is, the position of the projection surface in the image generating device changes. When the position of the projection surface in the image generating device changes, that is, the distance between the projection surface and the reflection assembly in the head-up display is adjusted, the projection surface adjusts the incident angle of the outgoing light rays to the reflection assembly, and according to the different incident angles of the outgoing light rays of the projection surface 5, the head-up display can project virtual pictures with different virtual image distances.

[0106] It should be noted that the structure of the adjusting mechanism includes but is not limited to the above structure, as long as the movable lens group 101 can move along the optical axis.

[0107] In a specific embodiment, the projection lens includes: a fifth lens 24, a fourth lens 23, a third lens 22, a second lens 21 and a first lens 20 arranged in sequence along the optical axis, the first lens 20 is arranged adjacent to the projection surface 5, the optical power of the fifth lens 24, the fourth lens 23, the third lens 22, the second lens 21 and the first lens 20 is: positive, positive, negative, positive, negative; In this embodiment, the total number of lenses of the lens is 5 pieces.

[0108] Referring to Figure 1 and Figure 2 , the first lens 20 is configured to be movable along the optical axis.

[0109] Referring to Figure 6 and Figure 7 , the fifth lens 24 is configured to be movable along the optical axis.

[0110] That is, for the same set of optical architecture, by moving the position of the first lens 20 (the lens closest to the projection surface 5) or by moving the position of the fifth lens 24 (the lens farthest from the projection surface 5), combined with the adjustment of the position of the projection surface 5 within the projection distance range, on the one hand, it ensures that the projection surface 5 displays a picture with relatively high resolution, and on the other hand, the head-up display can project virtual pictures with different virtual image distances.

[0111] It should be noted that the movable lens group 101 can include one movable lens defined above, or the movable lens group 101 further includes two movable lenses, or more movable lenses. And the fixed lens group 102 can include four fixed lenses defined above, or more or less lenses.

[0112] In addition, according to the type of the image generating device, the display size of the projection surface 5, and the requirement of the display quality of the projection surface 5, the projection lens can include different numbers of lenses. A smaller number of lenses can reduce the manufacturing cost and help reduce the volume and weight of the projection lens. However, the reduction of the number of lenses can sacrifice part of the imaging quality. Therefore, the total number of lenses can be limited in a proper range to ensure a certain imaging quality. For example, the number of lenses can be 4 to 7.

[0113] It should be noted that the number of lenses in the projection lens is not particularly limited in the embodiments of the present application, as long as the clear virtual image with different virtual image distances can be projected by moving the position of a certain lens and setting the position of the projection surface.

[0114] In a specific embodiment, referring to Figure 1 and Figure 2 , the movable lens group 101 includes a lens that can move along the optical axis, i.e., the first lens 20. The optical power of the first lens 20 is negative, and the lens has a diverging effect on light. In the projection lens, the lens with negative optical power is usually used to adjust the focal length to meet different projection requirements.

[0115] Specifically, the first lens 20 moves along the optical axis to realize the zoom, focus, or other optical adjustment functions of the projection lens. That is, when the first lens 20 moves along the optical axis, the projection surface 5 moves within the projection distance range to ensure the display quality of the projection surface 5. When the projection surface 5 moves within the projection distance range, the incident angle of the light rays emitted by the projection surface 5 to the reflection assembly of the head-up display changes, so that the head-up display can project virtual images with different virtual image distances on the side of the windshield away from the human eye.

[0116] The fixed lens group 102 includes four lenses, specifically the second lens 21, the third lens 22, the fourth lens 23, and the fifth lens 24. The transmission direction of the light rays is that the light rays emitted by the illumination system pass through the display chip, then pass through the fifth lens 24, the fourth lens 23, the third lens 22, the second lens 21, and the first lens 20 in sequence, and then project to the projection surface 5.

[0117] The optical power of the fifth lens 24 and the fourth lens 23 is positive, which helps to enhance the converging effect of the light rays and improve the clarity and contrast of the projection image. At the same time, the fourth lens 23 and the third lens 22 can be cemented together to correct the aberration generated by the fifth lens 24 to ensure the quality of the projection image.

[0118] The third lens 22 is located on the light exit side of the fourth lens 23, and the optical power of the third lens 22 is negative. The lens with negative optical power is used to further adjust the path and distribution of light rays to optimize the imaging quality and reduce aberration. Exemplarily, by reasonably designing the curvature and material of the third lens 22, the optimized control of the light rays can be achieved.

[0119] The second lens 21 is located on the light exit side of the third lens 22, and the optical power of the second lens 21 is positive. The lens with positive optical power has a further converging effect on the light rays, which helps to focus the light rays on the projection surface 5 to form a clear image.

[0120] Exemplarily, on the basis that the projection distance T between the projection surface 5 and the projection lens satisfies 120mm-140mm, the distance T1 between the first lens 20 and the second lens 21 satisfies: 3.15mm

[0121] In addition, the second lens 21 and the third lens 22 are further provided with a diaphragm 34.

[0122] In addition, the projection lens further includes an equivalent prism 31, a protective glass 32 and a DMD 33.

[0123] In one specific embodiment, referring to Figure 6 and Figure 7 The movable lens group 101 includes a lens that can move along the optical axis, i.e., the fifth lens 24. The movement of the fifth lens 24 is usually used for zoom or focus adjustment. By changing the position of the fifth lens 24, the focal length of the projection lens can be changed to adapt to different projection distances.

[0124] Exemplarily, on the basis that the projection distance T between the projection surface 5 and the projection lens satisfies 120mm-140mm, the distance T3 between the fifth lens 24 and the fourth lens 23 satisfies: 0.01mm

[0125] Or on the basis of the projection distance T between the projection surface 5 and the projection lens T satisfies 120mm~140mm, the distance T2 between the fifth lens 24 and the equivalent prism 31 satisfies: 5.5mm<T2<5.9mm. That is, by fine-tuning the setting position of the fifth lens 24, the position of the projection surface 5 changes within the projection distance range, and the head-up display can project pictures with different virtual image distances on the basis of clear projection.

[0126] In one specific embodiment, with reference to Figure 1 and Figure 2 and Figure 6 and Figure 7 , the first lens 20 is an aspherical lens, and the fifth lens 24 is an aspherical lens.

[0127] Specifically, the first lens 20 is an aspherical lens arranged opposite to the projection surface 5, which can reduce the aberration generated during zooming and focusing, and ensure that the projected picture remains clear and accurate at different focal lengths. The fifth lens 24 is an aspherical lens where light first enters, which can more effectively correct field curvature and ensure that the projected picture remains clear and flat within the entire field of view. By selecting an aspherical lens for these two key positions, the imaging quality of the lens can be significantly improved, and aberration can be reduced.

[0128] In the case where the first lens 20 is an aspherical lens and the fifth lens 24 is an aspherical lens, by moving the position of the first lens 20 or moving the setting position of the fifth lens 24, on the one hand, the projection surface 5 displays a picture with relatively high clarity, and on the other hand, the head-up display can project a virtual picture with different virtual image distances.

[0129] In one specific embodiment, the projection lens satisfies: -1.1<EFL / f1<-0.95; 0.95<EFL / f2<1.05; -1.25<EFL / f3<-1.15; 0.93<EFL / f4<0.98; 0.65<EFL / f5<0.75;

[0130] Wherein, EFL is the effective focal length of the projection lens, f1 is the focal length of the first lens 20, f2 is the focal length of the second lens 21, f3 is the focal length of the third lens 22, f4 is the focal length of the fourth lens 23, and f5 is the focal length of the fifth lens 24.

[0131] In this embodiment, the ratio of the focal length of each lens to the effective focal length of the projection lens is limited, which can make the light path of the projection lens smoother, improve the resolution of the projection lens, and ensure the performance stability of the projection lens.

[0132] In another embodiment, the first lens 20 has a refractive index and Abbe number satisfying the relationship: Nd1 < 1.65, Vd1 > 45; the second lens 21 has a refractive index and Abbe number satisfying the relationship: Nd2 < 1.75, Vd2 < 45; the third lens 22 has a refractive index and Abbe number satisfying the relationship: Nd3 < 1.75, Vd3 < 45; the fourth lens 23 has a refractive index and Abbe number satisfying the relationship: Nd4 > 1.65, Vd4 > 45; and the fifth lens 24 has a refractive index and Abbe number satisfying the relationship: Nd5 < 1.65, Vd5 > 45. The above combination of materials can reduce chromatic aberration of the projection lens.

[0133] In one embodiment, the third lens 22 and the fourth lens 23 are cemented to form a cemented lens group.

[0134] In this embodiment, the cemented lens group can effectively correct aberrations such as chromatic aberration and spherical aberration generated by a single lens through the combination of different materials.

[0135] The specific combination of focal length ratio and optical power (one negative and one positive) of the third lens 22 and the fourth lens 23 enables them to form more precise control of light rays after cementing, thereby optimizing the imaging quality.

[0136] In a specific embodiment, referring to Figure 1 and Figure 2 the projection lens of the image generating device comprises, in order along the direction of light exit, a DMD 33, a protective glass 32, an equivalent prism 31, a fifth lens 24, a fourth lens 23, a third lens 22, a diaphragm 34, a second lens 21, and a first lens 20, wherein the first lens 20 is movable along the optical axis. The setting position of the projection surface 5 can be adjusted within the range of the variable projection area. Table 1 is the optical parameters of the projection lens.

[0137] Table 1:

[0138]

[0139] The first lens 20 and the fifth lens 24 are aspherical lenses, wherein S1, S2 and S9, S10 are two aspherical surfaces of the first lens 20 and the fifth lens 24, and the surface type is described as follows:

[0140]

[0141] wherein Z(h) is the sag of the aspherical surface at a height of h along the optical axis, c = 1 / r, r represents the radius of curvature of the aspherical surface, k is the conic coefficient, and A, B, C, D, E, F, G, and H are high-order coefficients of the aspherical surface.

[0142] Table 2 provides aspherical surface parameters of the first lens 20 and the fifth lens 24 in the projection lens of the embodiment:

[0143] Table 2:

[0144] Figure 6 K A B C D E F G H S1 50.24 0 -6.9E-04 2.2E-05 -7.5E-07 1.0E-08 -1.0E-10 0 0 S2 -6.15 0 3.6E-03 -2.6E-04 1.6E-05 -5.8E-07 9.3E-09 0 0 S9 -5.10 0 3.1E-05 5.6E-07 -2.2E-08 -1.5E-11 0.0E+00 0 0 S10 -2.74 0 6.4E-06 7.0E-07 -2.2E-08 -2.3E-11 0.0E+00 0 0

[0145] In this specific embodiment, the projection lens in the image generating device can clearly project in the projection distance range of 120mm-140mm.

[0146] wherein Figure 7 Fig. 4 shows the MTF diagram of the projection lens of the image generating device provided by the embodiment of the present application when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm. The projection lens can achieve clear projection when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm respectively.

[0147] wherein Figure 1 Fig. 5 shows the field curvature / distortion diagram of the projection lens of the image generating device provided by the embodiment of the present application when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm. When the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm respectively, the image field curvature / distortion is small, and the picture has high quality.

[0148] wherein Figure 2 Fig. 6 shows the change curve diagram of the position of the first lens 20 relative to the second lens 21 when the projection distance of the projection lens of the image generating device provided by the embodiment of the present application changes every 2mm in the range of 120mm-140mm. When the position of the first lens 20 is slightly adjusted along the optical axis direction, the picture displayed on the projection surface 5 has high picture quality in the projection distance range.

[0149] In another specific embodiment, referring to Figure 6 and Figure 7 , the projection lens of the image generating device comprises in sequence along the outgoing direction of the light: the DMD 33, the protective glass 32, the equivalent prism 31, the fifth lens 24, the fourth lens 23, the third lens 22, the diaphragm 34, the second lens 21 and the first lens 20, wherein the fifth lens 24 is movable along the optical axis direction. The setting position of the projection surface 5 can be adjusted in the variable projection area range. Table 3 provides the optical parameters of the projection lens.

[0150] Table 3:

[0151]

[0152] The first lens 20 and the fifth lens 24 are aspherical lenses, wherein S1, S2 and S9, S10 are two aspherical surfaces of the first lens 20 and the fifth lens 24, and the surface type is described as follows:

[0153]

[0154] wherein Z(h) is the sag of the aspherical surface at a position with a height of h along the optical axis, c=1 / r, r represents the radius of curvature of the aspherical surface, k is the conic coefficient, and A, B, C, D, E, F, G, H are high-order coefficients of the aspherical surface.

[0155] Table 4 provides the aspherical surface parameters of the first lens 20 and the fifth lens 24 in the projection lens of the embodiment:

[0156] Table 4:

[0157] Figure 1 K A B C D E F G H S1 50.24 0 -6.9E-04 2.2E-05 -7.5E-07 1.0E-08 -1.0E-10 0 0 S2 -6.15 0 3.6E-03 -2.6E-04 1.6E-05 -5.8E-07 9.3E-09 0 0 S9 -5.10 0 3.1E-05 5.6E-07 -2.2E-08 -1.5E-11 0.0E+00 0 0 S10 -2.74 0 6.4E-06 7.0E-07 -2.2E-08 -2.3E-11 0.0E+00 0 0

[0158] In this specific embodiment, the projection lens in the image generating device can clearly project in the projection distance range of 120mm-140mm.

[0159] wherein Figure 2 Fig. 6 shows the MTF diagram of the projection lens of the image generating device provided by the embodiment of the present application when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm, and the projection lens can clearly project when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm respectively.

[0160] wherein Figure 6 Fig. 7 shows the field curvature / distortion diagram of the projection lens of the image generating device provided by the embodiment of the present application when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm, and the image field curvature / distortion is small when the projection distance is 120mm, 125mm, 130mm, 135mm and 140mm respectively, and the picture has high quality.

[0161] wherein Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure 6 Figure 7 Figure 1 Figure 2 Figure Fig. 8 shows the change curve diagram of the position of the fifth lens 24 relative to the equivalent prism 31 when the projection distance of the projection lens of the image generating device provided by the embodiment of the present application changes every 2mm in the range of 120mm-140mm, and the picture displayed on the projection surface 5 has high picture quality when the position of the fifth lens 24 is slightly adjusted along the optical axis.

[0162] The application further provides a head-up display. The head-up display comprises the image generating device as described above. The image generating device is applied to the head-up display. The head-up display can project virtual pictures with different virtual image distances in the case of realizing clear projection pictures.

[0163] The above embodiments mainly describe the differences between the embodiments. The different optimization features between the embodiments can be combined to form a better embodiment without contradiction. In order to make the description concise, the details are not described herein.

[0164] Although some specific embodiments of the application have been described in detail above, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the application. The scope of the application is defined by the appended claims.

Claims

1. An image generating apparatus, characterized in that, For use in head-up displays, the image generating device includes: a projection lens and a projection surface (5) located on the light-emitting side of the projection lens; The projection lens includes a fixed lens group (102) and a movable lens group (101). The movable lens group (101) can move along the optical axis of the projection lens and adjust the position of the projection surface (5) according to the projection distance range, so that the head-up display projects virtual images with different virtual image distances. The projection distance between the projection surface (5) and the projection lens is within the range of: 120mm≤T≤140mm; The movable lens group (101) is located on the light-emitting side of the fixed lens group (102), and the distance T1 between the two adjacent lenses in the movable lens group (101) and the fixed lens group (102) satisfies: 3.15mm. <T1<3.35mm; Alternatively, the projection lens may further include an equivalent prism (31), with the movable lens group (101) located on the light-emitting side of the equivalent prism (31), and the distance T2 between the lens furthest from the fixed lens group (102) in the movable lens group (101) and the equivalent prism satisfying: 5.5mm. <T2<5.9mm。 2. The image generating apparatus according to claim 1, characterized in that, The lens in the movable lens group (101) that is furthest from the fixed lens group (102) is an aspherical lens.

3. The image generating apparatus according to claim 1, characterized in that, The movable lens group (101) is located on the light-emitting side of the fixed lens group (102). The overall optical power of the movable lens group (101) is negative, and the overall optical power of the fixed lens group (102) is positive.

4. The image generating apparatus according to claim 1, characterized in that, The movable lens group (101) is located on the light-incident side of the fixed lens group (102). The overall optical power of the movable lens group (101) is positive, and the overall optical power of the fixed lens group (102) is negative.

5. The image generating apparatus according to claim 1, characterized in that, The movable lens group (101) is located on the light-incident side of the fixed lens group (102), and the distance T3 between the two adjacent lenses in the movable lens group (101) and the fixed lens group (102) satisfies: 0.01mm. <T3<0.2mm。 6. The image generating apparatus according to claim 1, characterized in that, The aperture of the projection lens closest to the projection surface (5) is D1, and the effective focal length of the projection lens is EFL, where D1 / EFL<0.

95.

7. The image generating apparatus according to claim 1, characterized in that, The total length of the projection lens is TTL, and the effective focal length of the projection lens is EFL, where TTL / EFL < 4.

5.

8. The image generating apparatus according to claim 1, characterized in that, The projection lens also includes an adjustment mechanism (4), and the non-effective area of ​​the lens in the movable lens group (101) is set in the adjustment mechanism (4). The adjustment mechanism (4) drives the movable lens group (101) to move along the optical axis of the projection lens.

9. The image generating apparatus according to claim 8, characterized in that, The adjustment mechanism (4) includes a main body (41), and a recessed groove is formed on the side of the main body (41) facing the movable lens group (101), and a sliding groove is provided in the recessed groove; The adjustment mechanism (4) further includes a sliding part (42), the non-effective area of ​​the lens in the movable lens group (101) is connected to the sliding part (42), the sliding part (42) is at least partially located in the recessed groove, and the sliding part (42) is embedded in the groove to drive the movable lens group (101) to move along the optical axis of the projection lens.

10. The image generating apparatus according to any one of claims 1-9, characterized in that, The projection lens includes a fifth lens (24), a fourth lens (23), a third lens (22), a second lens (21), and a first lens (20) arranged sequentially along the optical axis. The first lens (20) is arranged adjacent to the projection surface (5). The optical powers of the fifth lens (24), the fourth lens (23), the third lens (22), the second lens (21), and the first lens (20) are positive, positive, negative, positive, and negative, respectively. The first lens (20) is configured to be movable along the optical axis, or the fifth lens (24) is configured to be movable along the optical axis.

11. The image generating apparatus according to claim 10, characterized in that, The projection distance between the first lens (20) and the projection surface (5) is within the range of 120mm≤T≤140mm.

12. The image generating apparatus according to claim 10, characterized in that, The first lens (20) is an aspherical lens, and the fifth lens (24) is an aspherical lens.

13. The image generating apparatus according to claim 11, characterized in that, When the first lens (20) is configured to move along the optical axis, the distance T1 between the first lens (20) and the second lens (21) satisfies: 3.15 mm. <T1<3.35mm。 14. The image generating apparatus according to claim 11, characterized in that, When the fifth lens (24) is configured to move along the optical axis, the distance T3 between the fifth lens (24) and the fourth lens (23) satisfies: 0.01 mm. <T3<0.2mm。 15. The image generating apparatus according to claim 11, characterized in that, The projection lens also includes an equivalent prism (31), and when the fifth lens (24) is configured to move along the optical axis, the distance T2 between the fifth lens (24) and the equivalent prism (31) satisfies: 5.5 mm. <T2<5.9mm。 16. The image generating apparatus according to claim 10, characterized in that, The projection lens satisfies: -1.1 <EFL / f1<-0.95;0.95< EFL / f2<1.05;-1.25<EFL / f3<-1.15;0.93< EFL / f4<0.98;0.65< EFL / f5<0.75; Wherein, EFL is the effective focal length of the projection lens, f1 is the focal length of the first lens (20), f2 is the focal length of the second lens (21), f3 is the focal length of the third lens (22), f4 is the focal length of the fourth lens (23), and f5 is the focal length of the fifth lens (24).

17. The image generating apparatus according to claim 10, characterized in that, The third lens (22) and the fourth lens (23) are cemented together to form a cemented lens group.

18. A heads-up display, characterized in that, The head-up display includes an image generating device as claimed in any one of claims 1-17.

Images