Lens module and projection device

Abstract

The present application provides a lens module. The lens module is arranged in a light beam transmission path to expand the light beam. The lens module includes a first lens assembly and a second lens assembly. The first lens assembly is arranged in the light beam transmission path and has a first equivalent focal length. The second lens assembly is arranged in the light beam transmission path from the first lens assembly and has a second equivalent focal length. The second equivalent focal length is greater than or equal to the first equivalent focal length. The present application also provides a projection device including the above lens module. The lens module and the projection device provided by the present application can provide a projection image with uniform color distribution.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical module and an optical device, and more particularly to a lens module and a projection device using the same. BACKGROUND

[0002] The principle of imaging of a projection device is to convert the illumination light beams generated by an illumination system into image light beams by a light valve, and then project the image light beams onto a screen through a projection lens to form an image picture. In order to form the illumination light beams, the illumination system can include a plurality of light beams of different wavelengths, which can be incident to a focusing lens along the same or different optical axes, so that the illumination light beams are condensed into a light integrating column and reflected multiple times in the light integrating column to achieve the effect of uniform light. The illumination light beams passing through the light integrating column can be projected to the light valve.

[0003] With the evolution of technology, in addition to the increasingly clear imaging quality, consumers also hope that the projector is light, thin, small and portable. Therefore, the miniaturization of the projector has become an important issue. However, in the miniaturized projector, the illumination light beams emitted by the light source can have a small illumination light beam diameter, so that the incident angle of the illumination light beams when focused to the light integrating column is too small, resulting in insufficient number of reflections of the illumination light beams in the light integrating column, thereby causing the problem of non-uniform light mixing.

[0004] The background section of this document is included in advance to provide information related to the present application. The information in this section can include some known technologies that can not constitute prior art in the field of the application. The content of this section does not mean that the content or problems to be solved by one or more embodiments of the present application are known or recognized by those skilled in the art before the present application is filed. SUMMARY

[0005] The present application provides a lens module, which can make the incident angle range of the light beams incident to the light integrating column larger, so that the light mixing of the light beams in the light integrating column is more uniform.

[0006] The present application provides a projection device, which can provide a projection picture with uniform color distribution.

[0007] Other objects and advantages of the present application can be further understood from the technical features disclosed by the present application.

[0008] To achieve one or some or all of the above-mentioned objects, an embodiment of the present application provides a lens module. The lens module is arranged in a light beam transmission path to expand the light beam. The lens module includes a first lens assembly and a second lens assembly. The first lens assembly is arranged in the light beam transmission path and has a first equivalent focal length. The second lens assembly is arranged in the light beam transmission path from the first lens assembly and has a second equivalent focal length. The second equivalent focal length is greater than or equal to the first equivalent focal length.

[0009] To achieve one or some or all of the above-mentioned objects, an embodiment of the present application provides a projection device. The projection device includes an illumination system, a light valve, and a projection lens. The illumination system is configured to provide an illumination light beam. The illumination system includes a light source module, the above-mentioned lens module, and a light homogenizing element. The light source module is configured to emit the illumination light beam. The lens module is arranged in the light beam transmission path and is configured to expand the illumination light beam. The light homogenizing element is arranged in the light beam transmission path from the lens module. The light valve is arranged in the light beam transmission path to modulate the illumination light beam into an image light beam. The projection lens is arranged in the image light beam transmission path.

[0010] Based on the above, in the projection device of the embodiment of the present application, the light source module can be configured to expand the light beam. Therefore, the light beam passing through the lens module can have a larger beam diameter, so that the incident angle of the light beam when focused on the light homogenizing element becomes larger, which can increase the number of reflections of the light beam in the light homogenizing element, thereby improving the uniformity of the light beam mixing. In this way, the projection device of the embodiment of the present application can provide a projection screen with uniform color distribution.

[0011] In order to make the above features and advantages of the present application more apparent, the following embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a schematic diagram of a projection device according to an embodiment of the present application.

[0013] Figure 2A is Figure 1 is a front view schematic diagram of a light source module in

[0014] Figure 2B is Figure 1 is a front view schematic diagram of another light source module in

[0015] Figure 3 is a schematic diagram of a projection device according to another embodiment of the present application.

[0016] Figure 4 is a schematic diagram of a projection device according to another embodiment of the present application.

[0017] Figure 5A and Figure 5B The light path of the light beam when the light beam is incident to the light homogenizing element at different incident angles is illustrated. DETAILED DESCRIPTION

[0018] The foregoing and other technical features, aspects and effects of the present application will become more apparent from the following detailed description of preferred embodiments, given by way of example only, with reference to the accompanying drawings. Directional terms used in the following embodiments, such as upper, lower, left, right, front or rear, are only used with reference to the accompanying drawings. Therefore, the directional terms are used for explanation and not for limiting the present application.

[0019] Figure 1 FIG. 1 is a schematic diagram of a projection device according to an embodiment of the present application. Figure 2A FIG. 2 is a schematic diagram of a light source module according to an embodiment of the present application. Figure 1 FIG. 3 is a front view of the light source module of FIG. 2. Figure 2B FIG. 4 is a front view of another light source module according to an embodiment of the present application. Please refer to FIG. 1 first. Figure 1 FIG. 5 is a schematic diagram of a projection device according to another embodiment of the present application. Figure 1 The projection device 200 of the present embodiment is used to project an image light beam IMB onto a screen or a wall (not shown). The projection device 200 includes a light source module 100, a light valve 210 and a projection lens 220. The light source module 100 is used to provide an illumination light beam IB. The light valve 210 is disposed in the transmission path of the illumination light beam IB to modulate the illumination light beam IB into the image light beam IMB. The projection lens 220 is disposed in the transmission path of the image light beam IMB and is used to project the image light beam IMB onto the screen or the wall (not shown) to form an image picture. Since the light valve 210 converts the illumination light beam IB into the image light beam IMB in time sequence and transmits the image light beam IMB to the projection lens 220 after the illumination light beam IB of different colors is sequentially generated and irradiated on the light valve 210, the image picture projected out of the projection device 200 by the image light beam IMB converted by the light valve 210 can become a color picture.

[0020] In the present embodiment, the light valve 210 is, for example, a digital micro-mirror device (DMD) or a liquid-crystal-on-silicon panel (LCOS panel). However, in other embodiments, the light valve 210 can also be a transparent liquid crystal panel or other spatial light modulator. Furthermore, the present embodiment does not limit the number of light valves 210. In the present embodiment, the projection lens 220 is, for example, a combination including one or more optical lenses having refractive power, such as a double-concave lens, a double-convex lens, a concave-convex lens, a convex-concave lens, a plano-convex lens, a plano-concave lens, or other non-planar lens or various combinations thereof. The present application does not limit the type and kind of the projection lens 220.

[0021] In the present embodiment, as shown in FIG. 1, the illumination system 100 includes a light source module 110, a lens module 120, and a light homogenizing element 130. The light source module 110 is configured to emit an illumination beam IB. The lens module 120 is disposed on the transmission path of the illumination beam IB and is configured to expand the illumination beam IB. The light homogenizing element 130 is disposed on the transmission path of the illumination beam IB from the lens module 120 and is configured to homogenize the illumination beam IB. Figure 1

[0022] In some embodiments, the light source module 110 generally refers to a light source capable of emitting a light beam of a specific wavelength. For example, the light source module 110 can include a laser diode (LD), a light emitting diode (LED), or an array or group of one of the above, without being limited thereto.

[0023] In the embodiment shown in FIG. 1, the light source module 110 includes at least one first light source 112 and at least one second light source 114. The at least one first light source 112 is configured to emit at least one first light beam L1, and the at least one second light source 114 is configured to emit at least one second light beam L2. Thus, Figure 2A Figure 2A ​​The illumination beam IB of the embodiments may include at least one first beam L1 and at least one second beam L2. Furthermore, in some embodiments, the dominant wavelengths of the at least one first beam L1 and the at least one second beam L2 may differ by, for example, by more than 50 nanometers (nm), where the dominant wavelength is defined as the wavelength corresponding to the point of maximum light intensity. For example, the light source module 110 may be a red and blue laser diode bank. The first beam L1 is, for example, a blue laser beam, and the second beam L2 is, for example, a red laser beam. That is, the dominant wavelength of the first beam L1 falls within the wavelength range of blue light, for example, 465 nm. The dominant wavelength of the second beam L2 falls within the wavelength range of red light, for example, 638 nm, but the invention is not limited thereto.

[0024] Figure 2A Taking multiple first light sources 112 and multiple second light sources 114 as an example, the multiple first light sources 112 and multiple second light sources 114 can be arranged symmetrically, for example, from top to bottom, the order is second light source 114, first light source 112 and second light source 114. The multiple first light sources 112 and multiple second light sources 114 can also be arranged asymmetrically, for example, from top to bottom, the order is second light source 114, first light source 112, second light source 114 and second light source 114, but the present invention is not limited to this.

[0025] exist Figure 2B In the embodiment shown, the light source module 110a may be similar to Figure 2A The light source module 110a contains only the first light source 112 and does not contain the second light source 114. Therefore, Figure 2B The illumination beam IB in the embodiment includes a first beam L1 but excludes a second beam L2.

[0026] In this embodiment, as Figure 1As shown, the lens module 120 can include a first lens assembly 122 and a second lens assembly 124. The first lens assembly 122 is disposed in the transmission path of the first beam LI and the second beam L2 of the illumination beam IB, and the first lens assembly 122 has a first effective focal length. The second lens assembly 124 is disposed in the transmission path of the first beam LI and the second beam L2 of the illumination beam IB from the first lens assembly 122, and the second lens assembly 124 has a second effective focal length, wherein the second effective focal length is greater than or equal to the first effective focal length. In some embodiments, the lens module 120 can further include a diffusion element 126 disposed between the first lens assembly 122 and the second lens assembly 124. In such a configuration, the diffusion element 126 is disposed in the transmission path of the first beam LI and the second beam L2 of the illumination beam IB from the first lens assembly 122. Thus, the first beam LI and the second beam L2 of the illumination beam IB from the light source module 110 sequentially pass through the first lens assembly 122, the diffusion element 126, and the second lens assembly 124. However, the present application is not limited thereto, and in other embodiments, the beams can also pass through at least one or more of the first lens assembly 122, the diffusion element 126, and the second lens assembly 124 in other orders.

[0027] In the present embodiment, the illumination beam IB includes the first beam LI and the second beam L2. However, the present application is not limited thereto, and in other embodiments, the illumination beam IB can also include a conversion beam CB (described in detail below).

[0028] In detail, the lens assembly (e.g., the first lens assembly 122 or the second lens assembly 124) of the present embodiment can be a single lens, or can include two or more lenses. For example, the lens assembly can be a convex lens, a combination of two or more convex lenses, or a combination of a convex lens and a concave lens. The lens assembly in the drawings of the present application is only schematically shown as a single lens. In the present embodiment, although the lens assembly (e.g., the first lens assembly or the second lens assembly) includes the term "assembly", it can be composed of one or two or more lenses. For example, the first lens assembly can include only one lens, or can include two or more convex lenses, or one convex lens and one concave lens, or one lens with a very large curvature. In some embodiments, the lens assembly (e.g., the first lens assembly or the second lens assembly) can cause a collimated beam to pass through and be re-converged, or cause a diverging beam emitted from a focal point to pass through and be called a collimated beam.

[0029] In addition, the diffusion element 126 of the present embodiment is, for example, a diffusion sheet or a light-transmitting substrate provided with diffusion particles or diffusion structures.

[0030] In this embodiment, the focal point of the first lens assembly 122 and the focal point of the second lens assembly 124 are located at the same position, and the diffusion element 126 is disposed on the focal point of the first lens assembly 122 and on the focal point of the second lens assembly 124. In this configuration, the distance dl between the first lens assembly 122 and the diffusion element 126 is substantially equal to the first effective focal length of the first lens assembly 122, the distance d2 between the diffusion element 126 and the second lens assembly 124 is substantially equal to the second effective focal length of the second lens assembly 124, and the distance d3 between the first lens assembly 122 and the second lens assembly 124 is substantially equal to the sum of the first effective focal length of the first lens assembly 122 and the second effective focal length of the second lens assembly 124. In other words, the illumination beam IB travels a first optical path length (corresponding to the distance dl) between the first lens assembly 122 and the diffusion element 126, which is substantially equal to the first effective focal length of the first lens assembly 122. The illumination beam IB travels a second optical path length (corresponding to the distance d2) between the diffusion element 126 and the second lens assembly 124, which is substantially equal to the second effective focal length of the second lens assembly 124. The illumination beam IB travels a third optical path length (corresponding to the distance d3) between the first lens assembly 122 and the second lens assembly 124, which is substantially equal to the sum of the first effective focal length of the first lens assembly 122 and the second effective focal length of the second lens assembly 124. In this or other embodiments, the optical path length refers to the distance that the beam travels along the optical axis direction, and the distance between two elements refers to the relative distance along the optical axis direction. The optical axis direction refers to the direction of the principal optical axis of the beam.

[0031] For example, the first effective focal length and the second effective focal length can be 50 mm and 100 mm, 20 mm and 40 mm, or 15 mm and 30 mm, respectively, although the application is not limited thereto.

[0032] In this embodiment, the diffuser element 126 can be disposed at or near the focal point of both the first lens assembly 122 and the second lens assembly 124. For example, the distance between the diffuser element 126 and the focal point of the first lens assembly 122 (or the focal point of the second lens assembly 124) can be less than or equal to 5 mm. Since the diffuser element 126 is disposed at or near the focal point of either the first lens assembly 122 or the second lens assembly 124, the first beam L1 and the second beam L2 are substantially concentrated along the optical axis when passing through the diffuser element 126. In other embodiments, the diffuser element 126 may not be disposed at or near the focal point of either the first lens assembly 122 or the second lens assembly 124. In this case, the beam will not be concentrated along the optical axis when passing through the diffuser element 126; however, beams incident on the diffuser element 126 in a direction different from the optical axis of the diffuser element 126 can also be diffused. In this configuration, the spot size of the beam can be changed during subsequent focusing (e.g., the spot size increases). In a preferred embodiment, when the diffuser element 126 is disposed at or near the focal point of the first lens assembly 122 or the second lens assembly 124, the first beam L1 and the second beam L2 are substantially concentrated on the optical axis when passing through the diffuser element 126, so as to avoid unintended changes in the subsequent spot size (e.g., spot enlargement).

[0033] In some embodiments, such as Figure 1 As shown, the illumination beam IB (e.g., the first beam L1 and the second beam L2) is collimated before passing through the first lens assembly 122, the diffuser element 126, and the second lens assembly 124, and has a first width w1. Next, the first lens assembly 122 is used to focus the illumination beam IB. Since the focal point of the first lens assembly 122 and the focal point of the second lens assembly 124 can be approximately located at the same position, the second lens assembly 124 can be used to collimate the illumination beam IB focused by the first lens assembly 122, so that the illumination beam IB becomes a collimated beam with a second width w2 after passing through the first lens assembly 122, the diffuser element 126, and the second lens assembly 124. Since the second equivalent focal length of the second lens assembly 124 is greater than or equal to the first equivalent focal length of the first lens assembly 122, and the diffusion element 126 can expand the angle of the first beam L1 and the second beam L2, the second width w2 is greater than the first width w1, so that the combination of the first lens assembly 122, the second lens assembly 124, and / or the diffusion element 126 has the effect of beam expansion.

[0034] In some embodiments, the lens module 120 further comprises a third lens assembly 128 and a reflective element RE. The third lens assembly 128 is disposed in the transmission path of the illumination beam IB from the second lens assembly 124, and the third lens assembly 128 is configured to focus the illumination beam IB. The third effective focal length of the third lens assembly 128 is, for example, in the range of 20mm to 40mm, but the present application is not limited thereto, and the third effective focal length of the third lens assembly 128 can be greater than, equal to, or less than the first effective focal length of the first lens assembly 122 and / or the second effective focal length of the second lens assembly 124. In some embodiments, the third lens assembly can be used to converge, so as to match the size of the light entry end of the subsequent homogenizing element. In some embodiments, the reflective element RE can be disposed in the transmission path of the illumination beam IB from the second lens assembly 124 and the third lens assembly 128, wherein the reflective element RE is configured to change the propagation direction of the illumination beam IB and transmit the illumination beam IB to the homogenizing element 130.

[0035] In some embodiments, the illumination beam IB travels a fourth optical path length (equivalent to the distance between the third lens assembly 128 and the reflective element RE plus the distance between the reflective element RE and the homogenizing element 130) between the third lens assembly 128 and the homogenizing element 130, and the fourth optical path length is substantially equal to the third effective focal length of the third lens assembly 128.

[0036] In some embodiments, the reflective element RE is disposed in the optical path between the third lens assembly 128 and the homogenizing element 130. However, in some embodiments, the reflective element RE can also be disposed in the optical path between the second lens assembly 124 and the third lens assembly 128. Alternatively, in other embodiments, the lens module 120 can not include the reflective element RE, and the third lens assembly 128 can directly focus the illumination beam IB to the light entry end of the homogenizing element 130 (in which case the homogenizing element 130 is rotated by 90 degrees).

[0037] For illustrative purposes, in the present embodiment, the optical path of the illumination beam IB is illustrated as follows: Figure 5A and Figure 5B to illustrate the optical path of the illumination beam IB when the illumination beam IB is incident on the homogenizing element at different incident angles. In the present embodiment, the homogenizing element 130 is, for example, an integration rod. As shown in Figure 5A when the illumination beam IB has a small incident angle A1 when incident on the homogenizing element 130, the illumination beam IB is reflected a small number of times within the homogenizing element 130, and thus the uniformity of the mixed light of the illumination beam IB is poor. As shown in Figure 5B when the illumination beam IB has a large incident angle A2 when incident on the homogenizing element 130, the illumination beam IB is reflected a large number of times within the homogenizing element 130, and thus the uniformity of the mixed light of the illumination beam IB is good.

[0038] Therefore, the lens module 120 of the embodiment of the present application can be used to expand the illumination beam IB. Thus, the illumination beam IB passing through the first lens assembly 122, the diffusion element 126 and the second lens assembly 124 of the lens module 120 can have a larger beam diameter (i.e. width w2), so that the incident angle of the illumination beam IB when focused to the light homogenizing element 130 becomes larger, which can increase the number of reflections of the illumination beam IB in the light homogenizing element, and thus improve the uniformity of the beam mixing. In this way, the projection device 200 of the embodiment of the present application can provide a projection screen with uniform color distribution.

[0039] It should be noted that in other embodiments, the lens module 120 can also not have the diffusion element 126. In this case, the second effective focal length of the second lens assembly 124 is greater than the first effective focal length of the first lens assembly 122, so that the combination of the first lens assembly 122 and the second lens assembly 124 can also have the effect of beam expansion.

[0040] In some embodiments, referring again to Figure 1 , the illumination system can further include an excitation light source 140 and a wavelength conversion element 150. The excitation light source 140 is used to emit an excitation beam EB. The wavelength conversion element 150 is arranged on the transmission path of the excitation beam EB, and the wavelength conversion element 150 is used to convert the excitation beam EB into a converted beam CB. In the present embodiment, the excitation light source 140 can be similar to the light source module 110. For example, the excitation light source 140 can be a blue laser diode bank, and the excitation beam EB is a blue laser beam, for example, with a main wavelength falling within the wavelength range of blue light. The main wavelength of the excitation beam EB can be different from the main wavelength of the first beam L1 or the second beam L2. For example, the main wavelength of the excitation beam EB can be 455 nanometers. However, in other embodiments, the main wavelength of the excitation beam EB can also be the same as the main wavelength of the first beam L1 or the second beam L2.

[0041] In some embodiments, the wavelength conversion element 150 is, for example, a phosphor wheel. The wavelength conversion element 150 can include a wavelength conversion region (not shown) which can be provided with a wavelength conversion substance. The wavelength conversion substance can convert a short-wavelength light beam passing to the wavelength conversion region into a long-wavelength light beam. For example, the wavelength conversion substance is, for example, a yellow phosphor which can convert the excitation light beam EB into a yellow light beam. When the excitation light beam EB is irradiated to the wavelength conversion region, the wavelength conversion substance can be excited to emit a converted light beam CB which is, for example, a yellow light beam. However, in different embodiments, the number or configuration of the wavelength conversion regions of the wavelength conversion element 150 can vary depending on different types of illumination system 100, and the present application does not limit the configuration of the wavelength conversion element 150 and the type thereof.

[0042] In some embodiments, the illumination system can further include a combining element 160. The combining element 160 is configured in the transmission path of the first light beam Ll, the second light beam L2, the excitation light beam EB and the converted light beam CB. The first light beam Ll and the second light beam L2 are incident to the combining element 160 along a first direction (for example, the up-down direction of the figure) Figure 1 , and the excitation light beam EB and the converted light beam CB are incident to the combining element 160 along a second direction (for example, the left-right direction of the figure) Figure 1 , wherein the first direction is perpendicular to the second direction, but the present application is not limited thereto.

[0043] In particular, the combining element 160 can be a dichroic unit, for example, a dichroic mirror (DM) or a dichroic prism, which can provide different optical effects for light beams of different colors. For example, the combining element 160 can allow blue and red light beams to pass through, and reflect yellow and green light beams. In this embodiment, the combining element 160 can be designed to transmit the first light beam Ll, the second light beam L2 and the excitation light beam EB, and reflect the converted light beam CB. Therefore, the combining element 160 can transmit the excitation light beam EB from the excitation light source 140 to the wavelength conversion element 150, and combine the converted light beam CB from the wavelength conversion element 150 with the first light beam Ll and the second light beam L2 from the light source module 110, and then transmit to the homogenizing element 130.

[0044] In summary, the illumination light beam IB of the present embodiment can include the first light beam Ll, the second light beam L2, the converted light beam CB and / or the excitation light beam EB, wherein the light source module 110 provides the first light beam Ll and the second light beam L2, and the excitation light source 140 provides the excitation light beam EB to excite the converted light beam CB. Finally, the illumination light beam IB is modulated by the light valve 210 into the image light beam IMB, and the image light beam IMB is projected by the projection lens 220 to the projection device 200.

[0045] The following embodiments omit the same or similar technical contents as the foregoing embodiments, and as to the same or similar elements, their names can refer to the descriptions of the foregoing embodiments, which will not be repeated hereinafter.

[0046] Figure 3 is a schematic diagram of a projection device according to another embodiment of the present application. Please refer to Figure 3 The projection device 200a of the present embodiment is similar to the projection device 200 of the embodiment of Figure 1 The main difference between the projection device 200a of the present embodiment and the projection device 200 of the embodiment of The first reflective element RE1 of the present embodiment is configured on the light path between the first lens assembly 122 and the diffusion element 126, and the second reflective element RE2 of the present embodiment is configured on the light path between the third lens assembly 128 and the homogenization element 130. However, in other embodiments, the second reflective element RE2 can also be configured on the light path between the second lens assembly 124 and the third lens assembly 128. Alternatively, in some other embodiments, the lens module 120a can not include the second reflective element RE2, and the third lens assembly 128 can directly focus the illumination light beam IB to the light-in end of the homogenization element 130 (in this case, the homogenization element 130 is rotated by 90 degrees).

[0047] Figure 3 In the embodiment shown in

[0048] In some embodiments, the illumination beam IB travels a first optical path length between the first lens assembly 122 and the diffusion element 126 (equivalent to the distance between the first lens assembly 122 and the first reflective element RE1 plus the distance between the first reflective element RE1 and the diffusion element 126), which is substantially equal to the first effective focal length of the first lens assembly 122. The illumination beam IB travels a second optical path length between the diffusion element 126 and the second lens assembly 124, which is substantially equal to the second effective focal length of the second lens assembly 124. Similarly, the illumination beam IB travels a third optical path length between the first lens assembly 122 and the second lens assembly 124 (equivalent to the distance between the first lens assembly 122 and the first reflective element RE1 plus the distance between the first reflective element RE1 and the second lens assembly 124), which is substantially equal to the sum of the first effective focal length of the first lens assembly 122 and the second effective focal length of the second lens assembly 124.

[0049] In other embodiments, the lens module 120a can also not have the diffusion element 126. In this case, the second effective focal length of the second lens assembly 124 is greater than the first effective focal length of the first lens assembly 122, such that the first lens assembly 122 and the second lens assembly 124 can also have a beam expanding effect.

[0050] Furthermore, in the case where the lens module 120a can also not have the diffusion element 126 and the second effective focal length of the second lens assembly 124 is greater than the first effective focal length of the first lens assembly 122, the distance between the first lens assembly 122 and the first reflective element RE1 can be substantially equal to the first effective focal length. Alternatively, the distance between the first reflective element RE1 and the second lens assembly 124 can be substantially equal to the second effective focal length, although the present application is not limited in this regard.

[0051] In Figure 3 In the illustrated embodiment, since the first reflective element RE1 is disposed on the optical path before the second lens assembly 124 (i.e., on the path of the beam before the beam is expanded), and the second reflective element RE2 is disposed on the optical path after the second lens assembly 124 (i.e., on the path of the beam after the beam is expanded), the size of the first spot formed by the illumination beam IB on the first reflective element RE1 is smaller than the size of the second spot formed by the illumination beam IB on the second reflective element RE2. However, the present application is not limited in this regard, and in other embodiments, such as in the case where the first reflective element RE1 is very close to the first lens assembly 122 and / or the second reflective element RE2 is very close to the homogenizing element 130, the size of the first spot formed by the illumination beam IB on the first reflective element RE1 can also be smaller than or equal to the size of the second spot formed by the illumination beam IB on the second reflective element RE2.

[0052] Figure 4 is a schematic view of a projection device according to another embodiment of the present application. Please refer to Figure 4 , the projection device 200b of the present embodiment is similar to the projection device 200a of the embodiment Figure 3 , the main difference is that the first reflective element RE1 of the lens module 120b of the illumination system 100b of the present embodiment is disposed between the diffusion element 126 and the second lens assembly 124, that is, the first reflective element RE1 is disposed on the light path between the diffusion element 126 and the second lens assembly 124.

[0053] In the present embodiment, the illumination light beam IB travels a first light path length between the first lens assembly 122 and the diffusion element 126, which is substantially equal to the first effective focal length of the first lens assembly 122. The illumination light beam IB travels a second light path length (which is equal to the distance between the diffusion element 126 and the first reflective element RE1 plus the distance between the first reflective element RE1 and the second lens assembly 124) between the diffusion element 126 and the second lens assembly 124, which is substantially equal to the second effective focal length of the second lens assembly 124. The illumination light beam IB travels a third light path length (which is equal to the distance between the first lens assembly 122 and the first reflective element RE1 plus the distance between the first reflective element RE1 and the second lens assembly 124) between the first lens assembly 122 and the second lens assembly 124, which is substantially equal to the sum of the first effective focal length of the first lens assembly 122 and the second effective focal length of the second lens assembly 124.

[0054] In summary, in the projection device of the embodiments of the present application, since the second effective focal length of the second lens assembly is greater than or equal to the first effective focal length of the first lens assembly, and the diffusion element can also expand the angle of the light beam passing through, the lens module can be used to expand the light beam. Therefore, the light beam passing through the lens module can have a larger beam diameter, so that the incident angle of the light beam when focused to the light uniformization element is larger, which can increase the number of reflections of the light beam in the light uniformization element, thereby improving the uniformity of the light mixing of the light beam. In this way, the projection device of the embodiments of the present application can provide a projection image with uniform color distribution.

[0055] While the application has been described by way of example with reference to specific embodiments, all modifications and alterations shall be made obvious to those with ordinary skill in the art having the benefit of the teachings of the present application. It is the intention, therefore, to limit the application only as indicated by the scope of the claims appended hereto. In addition, any incorporation by reference of documents above is limited such that no unclaimed subject matter is made accessible to the public by incorporation by reference. Moreover, no embodiment or claim herein contains all of the features which are deemed necessary by law for inventive activity. These and other modifications can be made to the application in light of the foregoing description.

[0056] BRIEF DESCRIPTION OF DRAWINGS

[0057] 100, 100a, 100b: illumination system

[0058] 110, 110a: light source module

[0059] 112: first light source

[0060] 114: second light source

[0061] 120, 120a, 120b: lens module

[0062] 122: first lens assembly

[0063] 124: second lens assembly

[0064] 126: diffusion element

[0065] 128: third lens assembly

[0066] 130: homogenizing element

[0067] 140: excitation light source

[0068] 150: wavelength conversion element

[0069] 160: combining element

[0070] 200: projection device

[0071] 210: light valve

[0072] 220, 200a, 200b: projection lens

[0073] A1, A2: angle of incidence

[0074] CB: converted beam

[0075] d1, d2, d3: distance

[0076] L: light beam

[0077] L1: first light beam

[0078] L2: second light beam

[0079] IB: illumination beam

[0080] IMB: image beam

[0081] RE: reflecting element

[0082] RE1: first reflecting element

[0083] RE2: second reflecting element

[0084] w1: first width

[0085] w2: second width

Claims

1. A projection device, characterized in that, The projection device includes an illumination system, a light valve, and a projection lens, wherein: The lighting system is used to provide an illumination beam, and includes a light source module, a lens module, an excitation light source, a wavelength conversion element, a light combining element, and a light homogenizing element, wherein: The light source module includes at least one first light source for emitting at least one first beam of light; The lens module is disposed on the transmission path of the at least one first beam and is used to expand the at least one first beam. The lens module includes a first lens assembly, a diffusion element, and a second lens assembly, wherein: The first lens assembly is disposed on the transmission path of the at least one first beam, and the first lens assembly has a first equivalent focal length; The second lens assembly is disposed on the transmission path of the at least one first beam from the first lens assembly, and the second lens assembly has a second equivalent focal length, wherein the second equivalent focal length is greater than or equal to the first equivalent focal length; and The diffusion element is a light-transmitting substrate configured with diffusion particles or a diffusion structure, wherein the focal point of the first lens assembly and the focal point of the second lens assembly are located at the same position, and the diffusion element is disposed on the focal point of the first lens assembly and the focal point of the second lens assembly; Wherein, the at least one first beam travels a first optical path length between the first lens assembly and the diffusion element, and the first optical path length is equal to the first equivalent focal length; The excitation light source is used to emit an excitation beam; The wavelength conversion element is disposed on the transmission path of the excitation beam, and the wavelength conversion element is used to convert the excitation beam into a converted beam; The beam combining element is disposed on the transmission path of the at least one first beam passing through the lens module, and on the transmission path of the excitation beam and the conversion beam. The at least one first beam is incident on the beam combining element along a first direction, and the conversion beam is incident on the beam combining element along a second direction, wherein the first direction is perpendicular to the second direction, and the conversion beam does not pass through the first lens assembly, the diffusion element, and the second lens assembly; and The homogenizing element is disposed on the transmission path of the at least one first beam from the combining element and the converted beam and is used to output the illumination beam, the illumination beam including the at least one first beam and the converted beam; The light valve is positioned along the transmission path of the illumination beam to modulate the illumination beam into an image beam; and The projection lens is positioned on the transmission path of the image beam.

2. The projection device according to claim 1, characterized in that, The at least one first beam has a first width before passing through the lens module, and the at least one first beam has a second width after passing through the lens module, wherein the second width is greater than the first width.

3. The projection device according to claim 1, characterized in that, The diffusion element is disposed on the transmission path of the at least one first beam from the first lens assembly, and the at least one first beam passes sequentially through the first lens assembly, the diffusion element, and the second lens assembly.

4. The projection device according to claim 3, characterized in that, The at least one first beam travels a second optical path length between the diffuser and the second lens assembly, the second optical path length being equal to the second equivalent focal length.

5. The projection device according to claim 1, characterized in that, The at least one first beam travels a third optical path length between the first lens assembly and the second lens assembly, the third optical path length being equal to the sum of the first equivalent focal length and the second equivalent focal length.

6. The projection device according to claim 1, characterized in that, The first lens assembly is used to focus the at least one first beam, and the second lens assembly is used to collimate the at least one first beam.

7. The projection device according to claim 3, characterized in that, The lens module further includes a first reflective element disposed between the first lens assembly and the diffuser element or between the diffuser element and the second lens assembly, wherein the first reflective element is used to change the propagation direction of the at least one first beam.

8. The projection device according to claim 7, characterized in that, The lens module further includes a second reflective element disposed on the transmission path of the at least one first beam from the second lens assembly, wherein the second reflective element is used to change the propagation direction of the at least one first beam, and wherein the size of the first spot formed by the at least one first beam on the first reflective element is smaller than the size of the second spot formed by the at least one first beam on the second reflective element.

9. The projection device according to claim 1, characterized in that, The lens module further includes a third lens assembly disposed on the transmission path of the at least one first beam from the second lens assembly, and the third lens assembly is used to focus the at least one first beam.

10. The projection device according to claim 1, characterized in that, The light source module further includes at least one second light source, which is used to emit at least one second light beam. The illumination beam also includes the at least one second light beam, wherein the dominant wavelength of the at least one first light beam differs from the dominant wavelength of the at least one second light beam by more than 50 nanometers.

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