LCD direct projection light path structure

Abstract

The utility model relates to an LCD (Liquid Crystal Display) direct projection light path structure which comprises a light emitting unit, a rear Fresnel lens, an LCD screen, a front Fresnel lens and a projection lens which are sequentially arranged along the light propagation direction, the focal length of the rear Fresnel lens ranges from 40 mm to 80 mm, the size of the LCD screen ranges from 2.2 inches to 3.2 inches, and the focal length of the front Fresnel lens ranges from 50 mm to 90 mm. The distance between the light emitting surface of the LCD screen and the light incident surface of the projection lens is 40-70mm, and the focal length of the projection lens is less than 80mm. According to the LCD direct projection light path structure, a reasonable light path design is adopted, a reflective mirror is canceled, the utilization rate of light rays is improved by adopting a direct projection mode, and a projection image is formed through the 2.2-3.2 inch LCD screen, so that the image quality is improved. The rear Fresnel lens and the front Fresnel lens with proper focal lengths are matched at the same time, and the projection lens with short focal length is utilized, so that the light path can be shortened, the projection ratio is smaller than 1.2, the miniaturization of the LCD projector is realized, the edge light can be fully utilized, and the utilization rate of the light and the uniformity of illumination are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of LCD projectors, in particular to an LCD direct projection optical path structure. Background Art

[0002] A single-chip LCD projector forms an image by using a light source to emit light to an LCD panel, and then projecting the light transmitted through the LCD panel onto a screen through a projection lens.

[0003] With the increasing application of projectors in daily life, improving the illumination of single-chip LCD projectors has become a development trend. However, due to the unreasonable design and arrangement of various optical components and the presence of reflectors, single-chip LCD projectors have many problems such as low light utilization, large projection ratio, and small projection image. Utility Model Content

[0004] Based on this, the purpose of the utility model is to overcome the deficiencies of the prior art and provide an LCD direct projection light path structure.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] An LCD direct projection optical path structure comprises a light emitting unit, a rear Fresnel lens, an LCD screen, a front Fresnel lens and a projection lens which are sequentially arranged along the light propagation direction;

[0007] The focal length of the rear Fresnel lens is 40-80 mm, the size of the LCD screen is 2.2-3.2 inches, and the focal length of the front Fresnel lens is 50-90 mm; the distance between the light exit surface of the LCD screen and the light entrance surface of the projection lens is 40-70 mm, and the focal length of the projection lens is less than 80 mm.

[0008] As an implementation manner, a heat insulating sheet is provided between the rear Fresnel lens and the LCD screen.

[0009] As an embodiment, the heat insulation sheet has a length of 50-70 mm, a width of 25-45 mm, and a thickness of 0.9-1.2 mm.

[0010] As an embodiment, a brightness enhancement film is provided on the surface of the thermal insulation sheet.

[0011] As an implementation manner, a polarizing film is further provided on the surface of the heat insulation sheet.

[0012] As an embodiment, the light output unit includes a light source and a light funnel, the light source is arranged at the light entrance of the light funnel, the rear Fresnel lens is arranged at the light exit of the light funnel, and the size of the light entrance is smaller than the size of the light exit.

[0013] As an implementation manner, the length of the light entrance is 8-12 mm and the width is 5-8 mm, the length of the light exit is 41-60 mm and the width is 24-41 mm, and the distance between the light entrance and the light exit is 35-55 mm.

[0014] As an implementation manner, the light source is an LED, and its light power is 25-35W.

[0015] As an implementation manner, the length of the light-emitting surface of the LED is 8-10 mm, the width is 5-7 mm, and the light-emitting angle is 120°.

[0016] As an implementation manner, a reflective layer is provided on the inner surface of the light funnel.

[0017] The LCD direct projection optical path structure of the embodiment of the present application adopts a reasonable optical path design, eliminates the reflector, and adopts a direct projection method to improve the utilization rate of light. The projection image is formed through a 2.2-3.2 inch LCD screen. At the same time, a rear Fresnel lens and a front Fresnel lens with appropriate focal lengths are matched, and a short focal length projection lens is used. This can shorten the optical path, and at the same time, the projection ratio is less than 1.2, and the miniaturization of the LCD projector is realized. Such a setting can make full use of the edge light, thereby improving the utilization rate of light and the uniformity of illumination.

[0018] In order to better understand and implement the present invention, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the LCD direct projection optical path structure in the embodiment of the present application;

[0020] Figure 2 This is a schematic diagram of the structure of the light funnel in the embodiment of the present application;

[0021] Figure 3 This is a schematic diagram of the structure of the light funnel in the embodiment of the present application;

[0022] Figure 4 This is a schematic diagram of the structure of the LCD screen in the embodiment of the present application;

[0023] Figure 5 It is a schematic diagram of the structure of the thermal insulation sheet in the embodiment of the present application. DETAILED DESCRIPTION

[0024] To further illustrate each embodiment, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementation methods and advantages of the present invention.

[0025] In the description of the present invention, it needs to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "left", "right", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0026] See also Figures 1 to 5 The present embodiment provides an LCD direct projection optical path structure, which can be applied to an LCD projector. Specifically, the LCD direct projection optical path structure of the present embodiment includes: a light output unit 1, a rear Fresnel lens 2, an LCD screen 4, a front Fresnel lens 5 and a projection lens 6 which are sequentially arranged along the light propagation direction.

[0027] Among them, the light emitting unit 1 can emit white light, the focal length of the rear Fresnel lens 2 is 40-80 mm, the size of the LCD screen 4 is 2.2-3.2 inches, and the focal length of the front Fresnel lens 5 is 50-90 mm; the distance between the light emitting surface of the LCD screen 4 and the light incident surface of the projection lens 6 is 40-70 mm, and the focal length of the projection lens 6 is less than 80 mm.

[0028] It can be seen from the above technical solutions that the LCD direct projection optical path structure of this embodiment adopts a reasonable optical path design, eliminates the reflector, and adopts a direct projection method to improve the utilization rate of light. The projection image is formed through a 2.2-3.2 inch LCD screen 4. At the same time, a rear Fresnel lens 2 and a front Fresnel lens 5 with appropriate focal lengths are matched, and a short focal length projection lens 6 is used, thereby shortening the optical path. While achieving a projection ratio of less than 1.2, the miniaturization of the LCD projector is achieved. In addition, such a setting can make full use of the edge light, thereby improving the utilization rate of light and the uniformity of illumination.

[0029] Preferably, the light emitting unit 1 comprises a light source 11 and a light funnel 12, wherein the light source 11 can emit light, such as Figure 2 and 3As shown, the light funnel 12 has a light inlet 121 and a light outlet 122 which are opposite to each other along the optical axis, the size of the light inlet 121 is smaller than the size of the light outlet 122, the light inlet 121 of the light funnel 12 is rectangular, having a pair of short sides and a pair of long sides, similarly, the light outlet 122 of the light funnel 12 is also rectangular, having a pair of short sides and a pair of long sides, the short side of the light inlet 121 corresponds to the short side of the light outlet 122, and the long side of the light inlet 121 corresponds to the long side of the light outlet 122, so that the focusing cavity inside the light funnel 12 has a trapezoidal structure; the surface of the focusing cavity inside the light funnel 12 is provided with a reflective layer coated with silver or a reflective film, so as to reflect and focus the incident light, so that the light is emitted roughly evenly and in parallel.

[0030] The light source 11 is disposed at the light entrance 121 of the light funnel 12, and the rear Fresnel lens 2 is disposed at the light exit 122 of the light funnel 12. Figure 2 As shown, the length L1 of the light inlet 121 is 8-12 mm, and the width W1 is 5-8 mm; the length L2 of the light outlet 122 is 41-60 mm, and the width W2 is 24-41 mm; the distance D3 between the light inlet 121 and the light outlet 122 is 35-55 mm. The size of the light funnel 12 is reasonably designed, so that the light coming out of the light funnel 12 is uniform.

[0031] like Figure 4 As shown, the light source 11 is preferably an LED, wherein the LED in this embodiment is a COB packaged LED with a luminous power of 25-35W, a length L3 of the light-emitting surface of the LED of 8-10mm, a width W3 of 5-7mm, a luminous angle of 120°, and the light emitted is white light with sufficient brightness and a reasonable angle.

[0032] The rear Fresnel lens 2 may be, but is not limited to, made of a relatively low-cost plastic material, and its surface may have a plurality of concentric corrugated structures to form a collimating lens structure. The front Fresnel lens 5 may be, but is not limited to, made of a relatively low-cost plastic material, and its surface may have a plurality of concentric corrugated structures to form a focusing lens structure.

[0033] In order to reduce the luminous heat and reduce the risk of device damage, preferably, a heat insulation sheet 3 is provided between the rear Fresnel lens 2 and the LCD screen 4. Figure 5As shown, the heat insulation sheet 3 of this embodiment is made of glass, and the length L4 of the heat insulation sheet 3 is 50-70mm, the width W4 is 25-45mm, and the thickness is 0.9-1.2mm. Preferably, a brightness enhancement film is provided on the surface of the heat insulation sheet 3 to increase the brightness of light, and the surface of the brightness enhancement film is a 90° incremental prism structure. Furthermore, a polarizing film is also provided on the surface of the heat insulation sheet 3 to filter polarized light and block stray light.

[0034] In the LCD direct projection optical path structure of this embodiment, the light is emitted from the LED and incident on the light funnel 12 for multiple reflections to achieve a uniform light effect. The light is then collimated by the rear Fresnel mirror. The collimated near-parallel light illuminates the LCD screen 4, and then is further focused by the front Fresnel mirror to reduce the light beam. Finally, the light is projected onto the screen through the projection lens 7 to form an image.

[0035] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model manual self-centering vise. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model.

Claims

1. An LCD direct projection optical path structure, characterized in that: include: A light emitting unit, a rear Fresnel lens, an LCD screen, a front Fresnel lens and a projection lens are sequentially arranged along the light propagation direction; The focal length of the rear Fresnel lens is 40-80 mm, the size of the LCD screen is 2.2-3.2 inches, and the focal length of the front Fresnel lens is 50-90 mm; the distance between the light exit surface of the LCD screen and the light entrance surface of the projection lens is 40-70 mm, and the focal length of the projection lens is less than 80 mm.

2. The LCD direct projection optical path structure according to claim 1, characterized in that: A heat insulation sheet is arranged between the rear Fresnel lens and the LCD screen.

3. The LCD direct projection optical path structure according to claim 2, characterized in that: The heat insulation sheet has a length of 50-70 mm, a width of 25-45 mm, and a thickness of 0.9-1.2 mm.

4. The LCD direct projection optical path structure according to claim 2, characterized in that: A brightness enhancement film is arranged on the surface of the heat insulation sheet.

5. The LCD direct projection optical path structure according to claim 2, characterized in that: A polarizing film is also provided on the surface of the heat insulation sheet.

6. The LCD direct projection optical path structure according to any one of claims 1 to 5, characterized in that: The light output unit comprises a light source and a light funnel, the light source is arranged at the light entrance of the light funnel, the rear Fresnel lens is arranged at the light exit of the light funnel, and the size of the light entrance is smaller than that of the light exit.

7. The LCD direct projection optical path structure according to claim 6, characterized in that: The length of the light entrance is 8-12 mm, and the width is 5-8 mm. The length of the light exit is 41-60 mm, and the width is 24-41 mm. The distance between the light entrance and the light exit is 35-55 mm.

8. The LCD direct projection optical path structure according to claim 6, characterized in that: The light source is an LED, and its light power is 25-35W.

9. The LCD direct projection optical path structure according to claim 8, characterized in that: The length of the light-emitting surface of the LED is 8-10 mm, the width is 5-7 mm, and the light-emitting angle is 120°.

10. The LCD direct projection optical path structure according to claim 6, characterized in that: The inner surface of the light funnel is provided with a reflective layer.

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