Straight tube projector optical system

Abstract

This utility model discloses an optical system for a cylindrical projector, including objective lens one, objective lens two, a front Fresnel lens, an LCD display screen, a rear Fresnel lens, a reflector, and an LED light source, all installed inside the housing. Objective lens one, objective lens two, the front Fresnel lens, the LCD display screen, the rear Fresnel lens, the reflector, and the LED light source are sequentially distributed at intervals along a straight optical axis L. Objective lens one, objective lens two, and the front Fresnel lens together constitute a projection objective lens system. Light emitted from the LED light source is collected by the reflector and reflected to the rear Fresnel lens. The rear Fresnel lens refracts the light and projects it evenly onto the back of the LCD display screen. The image displayed on the front of the LCD display screen is magnified by the projection objective lens system and forms a magnified real image on the projection surface for viewing. It simplifies the structure, reduces manufacturing difficulty, simplifies installation, and lowers manufacturing costs.

Description

Technical Field

[0001] This utility model relates to an optical system for a cylindrical projector. Background Technology

[0002] Currently, the optical systems for short-projection-distance cylindrical projectors on the market are... Figure 1 As shown, its projection distance (i.e., the distance between the projection surface and the nearest objective lens) is approximately 61mm, and the projection area is approximately 295mm×295mm. It includes objective lens one, objective lens two, objective lens three, LCD display screen, lens four, lens five, and a large-diameter single-lamp LED light source. Objective lens one, objective lens two, objective lens three, LCD display screen, lens four, lens five, and large-diameter single-lamp LED light source are distributed sequentially along the straight optical axis S at intervals. Objective lens one, objective lens two, and objective lens three together constitute the projection objective lens system. Objective lens one, objective lens two, and objective lens three are ordinary concave and convex lenses.

[0003] The existing cylindrical projector optical system has the following technical problems: 1) It uses a large number of lenses, including five concave and convex lenses: objective lens one, objective lens two, objective lens three, lens four, and lens five. The structure is complex, difficult to process, has high installation requirements, and high manufacturing costs, which cannot satisfy customers. Summary of the Invention

[0004] The purpose of this invention is to provide a cylindrical projector optical system that solves the technical problems of existing projector optical systems, which use a large number of lenses, have complex structures, are difficult to process, have high installation requirements, and have high manufacturing costs, thus failing to satisfy customers.

[0005] The technical solution of this utility model is implemented as follows:

[0006] An optical system for a cylindrical projector is characterized by comprising objective lens one, objective lens two, a front Fresnel lens, an LCD display screen, a rear Fresnel lens, a reflector, and an LED light source, all mounted inside a housing. Objective lens one, objective lens two, the front Fresnel lens, the LCD display screen, the rear Fresnel lens, the reflector, and the LED light source are sequentially spaced along a linear optical axis L. Objective lens one, objective lens two, and the front Fresnel lens together constitute a projection objective lens system. Light emitted from the LED light source is collected by the reflector and reflected to the rear Fresnel lens. The rear Fresnel lens refracts the light and projects it uniformly onto the back of the LCD display screen. The image displayed on the front of the LCD display screen is magnified by the projection objective lens system and forms a magnified real image on the projection surface for viewing.

[0007] Preferably, the LED light source is an array of LEDs.

[0008] Preferably, the array of LEDs is arranged in a five-row, six-column configuration.

[0009] Preferably, the cross-section of the reflector cup is square.

[0010] Preferably, both the front and rear Fresnel lenses are constructed with a flat surface on one side and a Fresnel surface with concentric circles of varying sizes engraved on the other side. Both the Fresnel surfaces of the front and rear Fresnel lenses face the LCD display screen.

[0011] Preferably, the materials of objective lens one and objective lens two are optical plastic materials with a refractive index in the range of 1.4n-1.6n and a dispersion coefficient in the range of 30μ-60μ.

[0012] Preferably, objective lens one and objective lens two are ordinary concave and convex lenses of the same shape and are mounted symmetrically.

[0013] Preferably, objective lens one and objective lens two are installed inside an objective lens tube. A protruding post is provided on the outer side of the objective lens tube, and a spiral groove is provided on the housing. The protruding post moves along the spiral groove, thereby causing the objective lens tube to move back and forth along the linear optical axis L to achieve focusing.

[0014] Preferably, the distance between the projection surface and the first objective lens is 61±2mm, and the projection area is 295±2mm in length and 295±2mm in width.

[0015] Compared with the prior art, this utility model has the following advantages:

[0016] Effect 1: The optical system of this projector includes objective lens one, objective lens two, a front Fresnel lens, an LCD display screen, a rear Fresnel lens, a reflector, and an LED light source, all installed inside the housing. Light emitted from the LED light source is collected by the reflector and reflected onto the rear Fresnel lens. The rear Fresnel lens refracts the light and projects it evenly onto the back of the LCD display screen. The image displayed on the front of the LCD display screen is magnified by the projection lens system, forming a magnified real image on the projection surface for viewing. This invention significantly reduces the number of concave and convex lenses, simplifies the structure, reduces processing difficulty, simplifies installation, and lowers manufacturing costs, thus meeting customer requirements.

[0017] Other advantages of this invention will be described in more detail in the Embodiments section. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a traditional cylindrical projector optical system.

[0019] Figure 2 This is a cross-sectional view of the structure of this utility model;

[0020] Figure 3 for Figure 2 A magnified view of a portion of the image;

[0021] Figure 4 This is an exploded view of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0023] Example 1:

[0024] like Figures 2 to 4 As shown, this embodiment provides an optical system for a cylindrical projector, characterized in that it includes an objective lens 1, an objective lens 2, a front Fresnel lens 3, an LCD display screen 4, a rear Fresnel lens 5, a reflector cup 6, and an LED light source 7, all installed inside a housing 10. The objective lens 1, objective lens 2, front Fresnel lens 3, LCD display screen 4, rear Fresnel lens 5, reflector cup 6, and LED light source 7 are sequentially spaced along a linear optical axis L. The objective lens 1, objective lens 2, and front Fresnel lens 3 together constitute a projection objective lens system 100. Light emitted from the LED light source 7 is collected by the reflector cup 6 and reflected to the rear Fresnel lens 5. The rear Fresnel lens 5 refracts the light and projects it evenly onto the back of the LCD display screen 4. The image displayed on the front of the LCD display screen 4 is magnified by the projection objective lens system 100 and forms a magnified real image on the projection surface for viewing. This invention significantly reduces the number of concave and convex lenses, simplifies the structure, reduces processing difficulty, simplifies installation, and lowers manufacturing costs, thus meeting customer requirements.

[0025] Preferably, the LED light source 7 uses an array of LEDs, resulting in more uniform light projection.

[0026] Preferably, the array LEDs are arranged in a five-row, six-column configuration. This results in a more rational layout of the LED beads.

[0027] Preferably, the reflector cup 6 has a square cross-section, which is simple in structure.

[0028] Preferably, both the front Fresnel lens 3 and the rear Fresnel lens 5 are constructed with a flat surface on one side and a Fresnel surface with concentric circles of increasing size engraved on the other side. The Fresnel surfaces of both the front Fresnel lens 3 and the rear Fresnel lens 5 face the LCD display screen 4. The layout is reasonable and the structure is simple.

[0029] Preferably, objective lens 1 and objective lens 2 are made of optical plastic with a refractive index in the range of 1.4n-1.6n and a dispersion coefficient in the range of 30μ-60μ. Material selection is easy.

[0030] Preferably, objective lens 1 and objective lens 2 are ordinary concave and convex lenses of the same shape and are symmetrically installed, which reduces the number of molds required and further reduces costs.

[0031] Preferably, objective lens 1 and objective lens 2 are mounted inside an objective lens barrel 8. A protruding post 81 is provided on the outer surface of the objective lens barrel 8, and a spiral groove 11 is provided on the housing 10. Moving the protruding post 81 along the spiral groove 11 causes the objective lens barrel 8 to move back and forth along the linear optical axis L, thus achieving focusing. The structure is simple and easy to manufacture. Objective lens 1 and objective lens 2 are separated by a spacer 9.

[0032] Preferably, the distance between the projection surface and the objective lens 1 is 61±2mm, and the projection area is 295±2mm in length and 295±2mm in width. This is suitable for short-distance projection environments.

[0033] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited thereto. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model are equivalent substitutions and are included within the protection scope of the present utility model.

Claims

1. An optical system for a cylindrical projector, characterized in that: It includes objective lens one (1), objective lens two (2), front Fresnel lens (3), LCD display screen (4), rear Fresnel lens (5), reflector cup (6) and LED light source (7) installed inside the housing (10). Objective lens one (1), objective lens two (2), front Fresnel lens (3), LCD display screen (4), rear Fresnel lens (5), reflector cup (6) and LED light source (7) are distributed sequentially along the straight optical axis L. Objective lens one (1), objective lens two (2) and front Fresnel lens (3) together constitute the projection objective lens system (100). The light emitted by the LED light source (7) is collected by the reflector cup (6) and reflected to the rear Fresnel lens (5). The rear Fresnel lens (5) refracts the light and projects it evenly to the back of the LCD display screen (4). The image displayed in front of the LCD display screen (4) is magnified by the projection objective lens system (100) and forms a magnified real image on the projection surface for viewing.

2. The optical system for a cylindrical projector according to claim 1, characterized in that: The LED light source (7) adopts an array of LEDs.

3. The optical system for a cylindrical projector according to claim 2, characterized in that: The array-type LEDs are arranged in a five-row, six-column configuration.

4. The optical system for a cylindrical projector according to claim 1, 2, or 3, characterized in that: The cross-section of the reflector cup (6) is square.

5. The optical system for a cylindrical projector according to claim 4, characterized in that: Both the front Fresnel lens (3) and the rear Fresnel lens (5) are constructed with a flat surface on one side and a Fresnel surface with concentric circles engraved on the other side. The Fresnel surfaces of the front Fresnel lens (3) and the rear Fresnel lens (5) face the LCD display screen (4).

6. The optical system for a cylindrical projector according to claim 5, characterized in that: Objective lens 1 (1) and objective lens 2 (2) are made of optical plastic material with a refractive index in the range of 1.4n-1.6n and a dispersion coefficient in the range of 30μ-60μ.

7. The optical system for a cylindrical projector according to claim 6, characterized in that: Objective lens 1 (1) and objective lens 2 (2) are ordinary concave and convex lenses of the same shape and are mounted symmetrically.

8. The optical system for a cylindrical projector according to claim 7, characterized in that: Objective lens 1 (1) and objective lens 2 (2) are installed inside an objective lens tube (8). A protruding post (81) is provided on the outer side of the objective lens tube (8), and a spiral groove (11) is provided on the housing (10). The protruding post (81) moves along the spiral groove (11), thereby causing the objective lens tube (8) to move back and forth along the linear optical axis L to achieve focusing.

9. The optical system for a cylindrical projector according to claim 8, characterized in that: The distance between the projection surface and objective lens (1) is 61±2mm, and the projection area is 295±2mm in length and 295±2mm in width.

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