CN1258690C - Reflection type liquid crystal display light machine - Google Patents

Abstract

The utility model relates to a reflective liquid crystal display optical machine, which belongs to the field of optical instruments. The object of the present invention is to overcome the deficiencies of the prior art, and provide a liquid crystal display projector with simple structure, low production cost, low technical requirements, and favorable for mass production. The invention discloses a reflective liquid crystal display optical machine, which includes a light source assembly, a light splitting/combining system and a projection lens. The light splitting/combining system includes a polarizer, two broadband wave plates, a polarization beam splitter, a color separation Mirror, analyzer, and three reflective liquid crystals that can modulate red, green, and blue light respectively; the polarizing beam splitter is a prism composed of two triangular prisms, and the common glued surface of the two triangular prisms is coated with Wide-wavelength polarizing beam-splitting film; the dichroic mirror is a plane dichroic mirror coated with a two-color beam-splitting film. The light splitting/combining system of the present invention requires fewer optical devices, is convenient for debugging and positioning, has low optical machine cost, and is easier to enter into families.

Description

Reflective LCD Optical Machine

technical field

The invention belongs to the field of optical instruments, in particular to a projection instrument.

Background technique

Liquid crystal projection technology has been greatly developed and widely used in computer displays, projectors, and projection TVs. This technology has improved the quality of human life and brought enormous wealth to society.

A general liquid crystal projection system is composed of light source components, optical engine, projection lens and other components.

The light source component generally includes an illumination source (providing projector illumination), a collimator lens group (to turn the divergent light emitted by the illumination source into a parallel beam), an optical filter (to filter out infrared and ultraviolet light in the beam), and a polarizer (to convert The natural polarized light of the light source becomes linearly polarized light).

In the optical engine, the light beam of the light source is divided into three colors of red, green and blue, and the three-color light beams are respectively modulated by three reflective liquid crystals (for example, the current LCOS chip); onto the projection lens to form an image.

The publication number of the Chinese invention patent application "liquid crystal display projector" is CN1330280A, and the publication date is January 9, 2002. In this publication, a liquid crystal display projector containing a rhombic prism three-color combination/light splitting engine is disclosed. Its structure is shown in FIG. and LCD 5,6,7. The light beam emitted by the light source assembly 100 is split, modulated, and combined by the optical engine, and then passes through the projection lens 4 to be projected onto the screen. The disadvantages of this kind of liquid crystal display projector are: (1) the optical engine of this liquid crystal display projector has high requirements on the coating of the rhombic prism. There are difficulties in processing, especially in industrialized production; (2) the light splitting/combining system of the liquid crystal display projector needs a lens with a small focal length and a large back focus. This brings great difficulties to the design of the projection lens, and also increases the production cost of the lens; (3) due to the use of the polarizing beam splitter, there is a problem of low extinction ratio of light at large angles, which directly affects the contrast of the optical machine.

Contents of the invention

The object of the present invention is to overcome the deficiencies of the prior art and provide a liquid crystal display projector with high performance, simple structure, low production cost, low technical requirements and favorable for mass production.

The invention provides a reflective liquid crystal display optical machine, which includes a light source assembly, a light splitting/combining system and a projection lens, and is characterized in that the light splitting/combining system includes a polarizer, two broadband wave plates, a polarizing beam splitter, dichroic mirror, analyzer, and three reflective liquid crystals that can modulate red, green, and blue light respectively; the polarizing beam splitter is a grating with polarization splitting function, or a The prism composed of prisms is engraved with a grating with polarization splitting function on the common glued surface of two triangular prisms; the dichroic mirror is a plane dichroic mirror coated with a two-color splitting film;

The polarized light that enters the light splitting/combining system from the light source assembly enters the polarizing beam splitter through the polarizer and the first broadband wave plate, and a beam of light transmitted from the polarizing beam splitting mirror is incident on the first reflective liquid crystal, from which The other light beam reflected by the polarizing beam splitter is split by the dichroic mirror, and then respectively incident on the reflective liquid crystal; the reflected light beam modulated by the three reflective liquid crystals returns along the original optical path, passes through the polarizing beam splitter, the second The broadband waveplate and analyzer are projected into the projection lens.

The broadband wave plate of the present invention is a wave plate that only acts on a single primary color, or a wave plate that acts on light of two colors, or two wave plates that only act on a single primary color composed of overlays.

The two colors in the two-color light-splitting film coated with the dichroic mirror in the present invention are any two colors in the three primary colors of red, green and blue.

The polarizer in the present invention is a polarizer or a grating with a polarization splitting function.

The analyzer in the present invention is a polarizer or a grating with a polarization splitting function.

The light splitting/combining system of the present invention requires fewer optical devices, has high contrast, and is convenient for debugging and positioning. This feature of the present invention will reduce the cost of the projector and make it easier for the liquid crystal display projector to enter the family.

Description of drawings

FIG. 1 is a schematic structural diagram of a liquid crystal display projector disclosed in a prior invention patent application.

FIG. 2 is a schematic structural diagram of Embodiment 1 of the present invention.

Fig. 3 is a schematic structural diagram of Embodiment 2 of the present invention.

FIG. 4 is a schematic structural diagram of Embodiment 3 of the present invention.

Fig. 5 is a schematic structural diagram of Embodiment 4 of the present invention.

Detailed ways

The composition and working process of the present invention are illustrated below in conjunction with the accompanying drawings:

The light source assembly of the present invention includes an illumination light source, a collimating lens group, an optical filter, and a polarizer/analyzer.

In two embodiments of the present invention shown in Fig. 2, Fig. 3, polarization beam splitter 11 is a prism that is made up of two triangular prisms, is plated with wide-wavelength polarization beam splitter film on the public bonding surface of two triangular prisms Or engrave a grating with polarization splitting function, polarizer and analyzer adopt polarizer or grating with polarization splitting function.

According to whether it is S-polarized light or P-polarized light that enters the light splitting/combining system from the light source component, it is described in two cases:

(1) If S polarized light 8 emerges from the light source assembly, then A, B, and C (representing a combination of red, green, and blue tricolor light) in S polarized state are purified by polarizer 9 and then incident The first broadband wave plate 10 converts the S-polarized light of the A color light into P-polarized light, and the remaining two kinds of light are still S-polarized light. Then the three beams of light are incident on a polarizing beam splitter (PBS) 11 , the polarized light of color A is directly transmitted through the polarizing beam splitter 11 , and the polarized lights of colors B and C are reflected by the polarizing beam splitter. After the S polarized light of B and C two colors is reflected from the polarization beam splitter, it passes through a plane dichroic mirror 12 coated with a two-color beam splitting film at a certain angle with the surface of the polarization beam splitter, and one of the B and C color lights Reflection, another kind of transmission, realizes B and C splitting. In this way, the splitting of the three-color light of A, B, and C is finally realized, that is, the splitting of the three colors of red, green, and blue is realized. The three colors of light finally shine on the surfaces of the three reflective liquid crystals respectively. If the light reflected by the three liquid crystals 5, 6 and 7 is rotated 90° by the liquid crystal modulation polarization state, then the A light (polarization state is S) reflected by the liquid crystal is reflected by the polarization beam splitter; C light (polarization state is P) reaches the polarization beam splitter after being combined by the dichroic mirror, and is directly transmitted from the polarization beam splitter, thus realizing the combination of the three colors of light A, B, and C, that is, realizing red, green, and Combination of blue light. The combined light beam is projected by the projection lens, and the projected bright state at this time.

If the light reflected by the liquid crystal is modulated by the liquid crystal and the polarization state is not rotated, what is obtained through the projection lens is a dark state. Changing the modulation voltage on the liquid crystal can change the deflection angle of the light reflected from the liquid crystal, and different gray scales can be obtained by projecting through the projection lens. In order to further improve the performance, a second broadband wave plate 13 and an analyzer 14 are added in front of the projection lens. The function of the second broadband wave plate is to make the polarization states of the three colors of light A, B and C consistent, and the function of the analyzer is to purify the projected light again.

(2) If P polarized light 8 is emitted from the light source assembly, then A, B, and C (representing a combination of red, green, and blue tricolor light) of P polarized state are incident on the polarizer 9 after the tricolor light passes through the polarizer 9 The first broadband wave plate 10 converts the P polarized light of the two colors of light A and B into S polarized light, and the C light is still P polarized light. Then, the three beams of light are incident on the polarizing beam splitter 11, the polarized light of A and B colors is reflected by the polarizing beam splitter, and the polarized light of C color is directly transmitted through the polarizing beam splitter. Similarly, after the S-polarized light of two colors A and B comes out of the polarizing beam splitter, it is split by the dichroic mirror, one of which is reflected, and the other is transmitted to achieve A and B splitting. Finally, the splitting of the three colors of light A, B, and C is realized, that is, the splitting of the three colors of red, green, and blue is realized. The principle of synthesizing light is similar to the case (1).

According to the positional relationship between the dichroic mirror and the polarizing beam splitter and the type of the polarizing beam splitter, the present invention can also have two kinds of implementation structures as shown in Figure 4 and Figure 5, and in these two embodiments the polarizing beam splitter 11 is transparent A plane polarizing beam splitter coated with a polarizing beam splitting film on a flat substrate or a grating with a polarizing beam splitting function, and a polarizer and an analyzer adopt a polarizing plate or a grating with a polarizing beam splitting function. In the embodiment shown in FIG. 4 , the dichroic mirror and the polarizing beam splitter are arranged in parallel, and in the embodiment shown in FIG. 5 , the dichroic mirror and the polarizing beam splitter are arranged vertically. The working process of the optical machine is the same as that described in the foregoing embodiments.

Compared with ordinary polarizing beam splitters, polarizing beam splitters using planar gratings have many advantages: 1) The extinction ratio does not change with the angle of incident light; 2) Good heat dissipation, there is no problem of glass birefringence caused by thermal force . These advantages can greatly improve the contrast of the projection light machine.

The broadband wave plate in the present invention can adopt the ColorSelect wave plate provided by American ColorLink Company. The grating with the polarization splitting function can be a metal wire grid polarizer (WGP) produced by MOXTEK, USA.

Claims (7)

1. reflection type liquid crystal shows ray machine, comprise light source assembly, separation/combination photosystem and projection lens, it is characterized in that: described separation/combination photosystem comprises the polarizer (9), two wide wavestrip wave plates (10,13), polarization spectroscope (11), dichronic mirror (12), analyzer (14), and three reflection type liquid crystals (5,6,7) that can distinguish modulated red, green, blue three color light; Described polarization spectroscope (11) is a prism of being made up of two triangular prisms, engraves the grating with polarization spectro function on the public cemented surface of two triangular prisms; Described dichronic mirror (12) is a planar dichroic mirror that is coated with double-colored spectro-film;

The polarized light that goes out to inject the separation/combination system from described light source assembly enters polarization spectroscope (11) through the polarizer (9), the first wide wavestrip wave plate (10), incide on first reflection type liquid crystal (7) from one road light beam of polarization spectroscope (11) transmission,, after described dichronic mirror (12) beam split, incide respectively on the reflection type liquid crystal (5,6) from another road light beam of polarization spectroscope (11) reflection; Return along original optical path through the folded light beam after three reflection type liquid crystal modulation, go into described projection lens through described polarization spectroscope (11), the second wide wavestrip wave plate (13) and analyzer (14) projection.

2. reflection type liquid crystal according to claim 1 shows ray machine, it is characterized in that: described wide wavestrip wave plate is a wave plate that only single primary colours is worked, or the wave plate that the light of two kinds of colors is worked.

3. reflection type liquid crystal according to claim 1 shows ray machine, it is characterized in that: described wide wavestrip wave plate is that two wave plate stacks of only single primary colours being worked are formed.

4. reflection type liquid crystal according to claim 1 shows ray machine, it is characterized in that: double-colored in the double-colored spectro-film of described dichronic mirror (12) plating is any two kinds of colors in the red, green, blue three primary colours.

5. reflection type liquid crystal according to claim 1 shows ray machine, it is characterized in that: the described polarizer is polaroid or grating with polarization spectro function.

6. reflection type liquid crystal according to claim 1 shows ray machine, it is characterized in that: described analyzer is polaroid or grating with polarization spectro function.

7. reflection type liquid crystal shows ray machine, comprise light source assembly, separation/combination photosystem and projection lens, it is characterized in that: described separation/combination photosystem comprises the polarizer (9), two wide wavestrip wave plates (10,13), polarization spectroscope (11), dichronic mirror (12), analyzer (14), and three reflection type liquid crystals (5,6,7) that can distinguish modulated red, green, blue three color light; Described polarization spectroscope (11) is the grating that a slice has the polarization spectro function; Described dichronic mirror (12) is a planar dichroic mirror that is coated with double-colored spectro-film;

The polarized light that goes out to inject the separation/combination system from described light source assembly enters polarization spectroscope (11) through the polarizer (9), the first wide wavestrip wave plate (10), incide on first reflection type liquid crystal (7) from one road light beam of polarization spectroscope (11) transmission,, after described dichronic mirror (12) beam split, incide respectively on the reflection type liquid crystal (5,6) from another road light beam of polarization spectroscope (11) reflection; Return along original optical path through the folded light beam after three reflection type liquid crystal modulation, go into described projection lens through described polarization spectroscope (11), the second wide wavestrip wave plate (13) and analyzer (14) projection.

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