CN111257978A

CN111257978A - Prism assembly and digital light processing prism equipment

Info

Publication number: CN111257978A
Application number: CN202010111588.3A
Authority: CN
Inventors: 饶钦和; 李衡; 岳德举; 白金刚
Original assignee: Guangdong Lianda Photoelectricity Co ltd
Current assignee: Guangdong Lianda Photoelectricity Co ltd
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2020-06-09

Abstract

The invention provides a prism assembly and digital light processing prism equipment, and belongs to the technical field of optics. The prism assembly comprises two or more prisms, at least one of the prisms comprising one or more surfaces for total internal reflection or partial spectral reflection of incident light, at least a portion of one of the surfaces for reflective purposes being covered by an element, the element being spaced from the surface with a gap between the surface and the element, the gap being sealed by a seal, the seal being provided on one of the prisms to prevent contaminants from entering the gap. The prism assembly can prevent pollutants from entering the surface of the prism and covering the gap between the elements on the surface of the prism, and well keeps the surface of the prism clean.

Description

Prism assembly and digital light processing prism equipment

Technical Field

The present invention relates to a prism assembly, and more particularly, to a prism assembly composed of two or more prisms, and a digital light processing prism apparatus.

Background

In the prior art, Cathode Ray Tube (CRT) projectors are used for most projection applications, but they have been largely replaced because they are large in size, difficult to calibrate, must be used in very dark environments, and are very prone to failure frequently. Digital projector systems have become increasingly popular in the past decade because they are capable of projecting high quality images for application scenes such as conference room presentations, home cinema systems and large stadium concerts. Liquid Crystal Displays (LCDs) are one technology used in digital projectors, but the visible pixelation problem and larger size compared to DLP are negative factors associated with LCD technology. DLP is a competitive technology that is prized for its compactness and ability to provide high levels of contrast and brightness.

However, the prisms used in DLP projectors are very sensitive to contaminants. Digital projectors are commonly used in high pressure environments, such as concerts, where dust, smoke, cracked oils and other contaminants are present in the atmosphere. Air gaps in prismatic constructions tend to accumulate these contaminants, which often results in the projection of visual artifacts, such as color speckles. Contaminants may block light or invalidate TIR conditions. Due to the high cost and difficulty of cleaning, it is impractical to remove contaminants from the prism. Therefore, there is a need for a means of protecting the prism and DMD chip in a DLP light engine from atmospheric contaminants.

In order to project an image without visual artifacts, all TIR conditions must be maintained and light must be allowed to pass through all necessary regions of the prism in the DLP light engine. Thus, there is also a need for a technical means to satisfy all TIR conditions and allow light to pass through all necessary areas in the prism and DMD chip in a DLP light engine.

Disclosure of Invention

The present invention provides a prism assembly aiming at the above problems existing in the prior art, and the technical problems to be solved by the present invention are: how to prevent contaminants from entering the prism surface and gaps between elements covering the prism surface.

The purpose of the invention can be realized by the following technical scheme:

a prism assembly comprising more than two prisms, wherein at least one prism comprises one or more surfaces for total internal or partial spectral reflection of incident light, at least a portion of one of the surfaces for reflective purposes being covered by an element, the element being spaced from the surface with a gap between the surface and the element, the gap being sealed by a seal arranged on one prism to prevent contaminants from entering the gap.

In one of the prism assemblies described above, the element comprises a plate or a light reflecting valve or another prism of the prism assembly.

In one of the prism assemblies described above, the sealing member comprises at least one sealant.

In one of the prism assemblies described above, the prism assembly is used for image construction, and the encapsulant is disposed only at locations of the prism that do not participate in reflecting incident light associated with the image construction.

In one of the prism assemblies described above, all portions of the surface that reflect incident light associated with the image construction are covered by the elements.

In one of the prism assemblies described above, the temperature that the encapsulant can withstand is above 80 ℃, and the encapsulant is resistant to ultraviolet light.

In one of the prism assemblies described above, the encapsulant comprises silicone or silicone rubber.

It is another object of the present invention to provide a digital light processing prism device that is capable of satisfying all TIR conditions and allowing light to pass through the prism in the DLP light engine and all necessary areas in the DMD chip.

The purpose of the invention can be realized by the following technical scheme:

a digital light processing prism apparatus, characterized in that the prism apparatus comprises a total internal reflection, TIR, prism assembly comprising two triangular prisms extending in a first direction, one of the surfaces of the TIR prisms being opposite to each other, and a color prism assembly comprising one quadrangular prism having one surface facing the surface of one color triangular prism, one triangular prism having a second surface facing the first surface of one color triangular prism, and two triangular prisms having a second surface partly facing the surface of one of the TIR prisms, all opposite surfaces having a gap therebetween, which gap is sealed by a seal arranged on the prism.

In one of the above-mentioned digital light processing prism apparatuses, each color prism is provided with a light reflection valve on one surface thereof with a gap between the light reflection valve and the corresponding surface, the gap being sealed by a sealing member provided on the light reflection valve and the prism.

In one of the digital light processing prism devices described above, the outwardly oriented surfaces of the TIR prisms and the outwardly oriented surfaces of the color prisms used for total internal reflection or partial spectral reflection of the image building portion of the incident light are covered with elements spaced from the surfaces with a gap between the surfaces and the elements, the gap being sealed by a seal disposed on one of the prisms to prevent contaminants from entering the gap.

Compared with the prior art, the invention has the following advantages:

1. the prism assembly can prevent pollutants from entering the surface of the prism and covering the gap between the elements on the surface of the prism, and well keeps the surface of the prism clean.

2. The TIR prism component can enable the whole optical engine structure to be more compact, reduce the volume of the illumination and projection system and improve the energy utilization rate of the system.

3. The TIR prism component thoroughly separates the light beams in the 'flat' and 'off' states from the light beams in the 'on' state, improves the projection contrast and avoids the flat bright spots generated by the 'flat' state.

4. The TIR prism component has good final imaging quality, good uniformity and no bright line or bright spot phenomenon.

Drawings

FIG. 1 is a functional block diagram of a generic DLP light engine system of the present invention;

FIG. 2A is a left side view of the DLP prism apparatus of the present invention;

FIG. 2B is a right side view of the DLP prism apparatus of the present invention;

FIG. 2C is a rear view of the DLP prism apparatus of the present invention;

FIG. 3 is a rear view of the DLP prism subassembly of the present invention;

FIG. 4A is a bottom right view of the DLP prism subassembly of the present invention;

FIG. 4B is a lower left perspective view of the DLP prism subassembly of the present invention;

FIG. 5A is a side view of the DLP prism subassembly of the present invention;

FIG. 5B is a top view of the DLP prism subassembly of the present invention;

FIG. 5C is an enlarged view of portion A of FIG. 5B;

FIG. 6 is a schematic structural diagram of another embodiment of a TIR prism assembly;

FIG. 7 shows the path of the illumination beam in the prism for the DMD in the "on", "flat" and "off" states.

In the figure, 100, a DLP light engine system; 120. a light gathering column; 130. an optical relay system; 140. a DLP prism device; 150. a projection lens; 160. a DLP prism subassembly; 135. a third sealant; 200. a blue prism; 205. a red prism; 210. a green prism; 215. a TIR prism assembly; 220. glass I; 225. a second glass; 227. glass III; 230. fourthly, glass; 235. a first sealant; 240. sealing tape; 245. a second sealant; 250a, a DMD orifice plate I; 250b, a DMD orifice plate II; 250c, a DMD orifice plate III; 255a, a DMD chip I; 255b, a DMD chip II; 255c, a DMD chip III; 280a, DMD hole one; 280b DMD Aperture two; 280c DMD Aperture III; 500. an on state light; 510. an off state light; 520. transmitted white light; 530. transmitted green light; 535. reflected green light; 540. a TIR prism face; 550. transmitted blue light; 555. reflected blue light; 560. transmitted red/green light; 562. transmitted red light; 564. reflected red light; 565. reflected red/green light; 570. reflected projected light; 580. a blue prism face; 585. a blue prism face; 590. a red prism face; 595. a red prism face; 600. an air gap; 610. a first prism; 620. a second prism; 630. and a third prism.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1, it is a functional block diagram of a general DLP light engine system 100. The general DLP light engine system 100 includes a lamp 110, a light-gathering pole 120, an optical relay system 130, a DLP prism device 140, and a projection lens 150. The lamp 110 is a standard lamp for digital projection systems, such as a mercury or xenon bulb lamp. The lamp 110 is irradiated onto the light-focusing column 120, and the light-focusing column 120 adjusts and controls the light so that the light is uniformly distributed. As an example embodiment, a set of 4-6 lenses is included in optical relay system 130, and optical relay system 130 emits light from light beam 120 onto DLP prism device 140. The DLP prism device 140 includes a blue prism 200, a red prism 205, a green prism 210, a DMD chip and a DMD aperture plate, wherein the DMD chip includes a first DMD chip 255a, a second DMD chip 255b and a third DMD chip 255c, the DMD aperture plate includes a first DMD aperture plate 250a, a second DMD aperture plate 250b and a third DMD aperture plate 250c, and the sealant includes a first sealant 235, a second sealant 245 and a third sealant 135.

The DLP prism device 140 separates, reflects, and recombines light through the projection lens 150 for projection. A typical projection lens 150 has a focal length of 30 to 60mm, an f/number of f/2.5, a physical diameter of 120mm, and a physical length of 250 mm.

As shown in fig. 2A, in the present embodiment, the DLP prism apparatus 140 includes a blue prism 200, a red prism 205, a green prism 210, a TIR prism assembly 215, a first glass 220, a second glass 225, a third glass 227, a first sealant 235, a sealing tape 240, a second sealant 245, a first DMD aperture plate 250a, and a first DMD chip 255 a.

As shown in fig. 2A, in the present embodiment, the blue prism 200 is a triangular glass prism having a blue dichroic coating for separating blue light, such as those manufactured by konica minolta, japan, and the like. The red prism 205 is a triangular glass prism having a red dichroic coating for separating red light, such as those manufactured by cunica media et al. The green prism 210 is a glass four-prism through which the remaining light as green light passes. The TIR prism assembly 215 comprises two smaller triangular prisms bonded together, which are not visible due to the obscuration by glass one 220. The blue prism 200, the red prism 205, the green prism 210, and the TIR prism assembly 215, which pass through the center of and are perpendicular to the DMD chip three 255c, have a size in the range of 70-125mm, as measured along the optical axis.

The glasses include glass one 220, glass two 225, glass three 227, and glass four 230. as an example, glass one 220 is a glass plate having dimensions of about 25 x 70 x 2mm and is adhered to the left side of TIR prism assembly 215 by a transparent adhesive such as Dymax OP-29. Glass one 220 is sealed to the blue prism 200 by sealant one 235.

The first sealant 235 is used to seal the air gap between the blue prism 200, the red prism 205 and the green prism 210 on the TIR prism assembly 215 and seal the air gap between the TIR prism assembly 215 and the blue prism 200. The first sealing agent 235 is a high temperature (up to 80 ℃) resistant, Ultraviolet (UV) resistant, flexible sealing agent with a width of 3-4mm and does not discharge gas.

As an example, the first sealant 235 is made of silicone or silicon rubber.

As an example, glass two 225 is a glass plate having dimensions of about 20X 67X 2 mm. Glass two 225 is adhered to the top of the TIR prism assembly 215 by a transparent adhesive (such as Dymax OP-29) and sealed to the blue prism 200 by sealant one 235. Glass three 227 is a glass plate having dimensions of about 23 x 74 x 2 mm. Glass three 227 is adhered to glass one 220 and glass two 225 by using a transparent adhesive (such as Dymax OP-29) and sealed to blue prism 200 by sealant one 235.

The sealing tape 240 is a flexible tape resistant to high temperature (up to 80 c), ultraviolet rays, and has a width of 3-4mm or less, and does not discharge gas. The sealing tape 240 is used to seal the air gap at the top of the DLP prism apparatus 140. As an example, the sealing tape 240 is made of silicone resin or silicone rubber. The sealing strip 240 is used to ensure that the TIR conditions are not violated and that light is not blocked at the top of the device, which may occur if a sealant is used.

The second encapsulant 245 is resistant to high temperatures (up to 80 ℃), ultraviolet light, and very soft (e.g., silicone rubber), which ensures that the position of the DMD chip one 255a is not disturbed.

As an example, the DMD aperture plate one 250a is a thin ferrous metal plate that is capable of absorbing stray light that would otherwise cause light to appear next to the screen. DMD chip one 255a is a micromirror array manufactured by texas instruments, usa. The DMD chip one 255a is attached to the DMD aperture plate one 250a and sealed to the blue prism 200 by the sealant two 245.

As shown in fig. 2B, the DLP prism device includes a glass four 230, a DMD aperture plate two 250B, and a DMD chip two 255B. Glass four 230 may be the same as glass one 220 in fig. 2A. The DMD aperture plate two 250b may be the same as the DMD aperture plate one 250a of fig. 2A. The DMD chip two 255b is a micromirror array, which may be the same as the DMD chip one 255a in fig. 2A.

As shown in fig. 2A and 2B, glass four 230 is adhered to the left side of TIR prism assembly 215 by a transparent adhesive such as Dymax OP-29 and sealed to blue prism 200 and red prism 205 by sealant one 235. The DMD chip 255b is attached to the DMD aperture plate two 250b and sealed to the red prism 205 by sealant two 245.

As shown in fig. 2C, the DLP prism apparatus includes a DMD aperture plate three 250C and a DMD chip three 255C. DMD aperture plate three 250c may be the same as DMD aperture plate one 250a in fig. 2A. DMD chip three 255c is a micromirror array and may be identical to DMD chip one 255a in fig. 2A. As shown in fig. 2A, 2B, and 2C, each DMD aperture plate 250 is attached to its respective DMD chip (i.e., DMD aperture plate one 250a is attached to DMD chip one 255a, DMD aperture plate two 250B is attached to DMD chip two 255B, DMD aperture plate three 250C is attached to DMD chip three 255C).

A second encapsulant 245 seals the gap between each DMD aperture plate and the corresponding prism and each interface between each DMD aperture plate and its corresponding DMD chip.

As shown in fig. 3, the DLP prism sub-assembly includes a plurality of DMD apertures, i.e., DMD aperture one 280a, DMD aperture two 280b, and DMD aperture three 280 c. The first DMD hole 280a, the second DMD hole 280b, and the third DMD hole 280c are openings in the first

DMD hole plate

250a, 250b, and 250c, respectively, and are slightly larger than the first DMD chip 255a, the second DMD chip 255b, and the third DMD chip 255 c. DLP prism subassembly 160 is a subassembly of DLP prism assembly 140 in which the DMD chips (i.e., DMD chip one 255a, DMD chip two 255b, and DMD chip three 255c) are removed so that DMD well one 280a, DMD well two 280b, and DMD well three 280c and encapsulant two 245 can be seen. Each DMD aperture 280 allows light to pass through to the corresponding DMD chip.

As shown in fig. 4A and 4B, DLP prism subassembly 170 is a subassembly of DLP prism assembly 140, with TIR prism assembly 215, DMD aperture plate one 250a, DMD aperture plate two 250B, and DMD aperture plate three 250c, and DMD chip one 255a, DMD chip two 255B, and DMD chip three 255c removed for viewing. In this embodiment, the width of the sealant one 235 applied to the front of the blue prism 200 should not exceed 1mm in order to satisfy the TIR condition and prevent the visual artifact from appearing on the projected image. The sealing tape 240 is used to seal the gaps between the blue prism 200, the red prism 205, and the green prism 210 on top of the DLP prism sub-assembly 170. The first sealant 235 is used to seal the gap between the front of the blue prism 200 and the red prism 205.

As shown in fig. 4B, a sealing tape 240 is used to seal the gaps between the blue prism 200, the red prism 205, and the green prism 210 on the bottom of the DLP prism sub-assembly 170.

As shown in fig. 1, 2A, 2B, 2C, 3, 4A, and 4B, the DLP prism apparatus 140 receives light from the relay optical system 130. Light enters through the TIR prism 215 and is reflected out through the DLP prism apparatus 140 where the dichroic coating separates the light into red, green, and blue components. After the light is split, each component of the light (i.e., red, green, and blue) passes through a DMD aperture (i.e., DMD aperture one 280a, which corresponds to blue prism 200, DMD aperture two 280b, which corresponds to red prism 205, and DMD aperture three 280c, which corresponds to green prism 210) and is reflected by a respective DMD chip attached to the prism (i.e., DMD chip one 255a, which corresponds to blue prism 200, DMD chip two 255b, which corresponds to red prism 205, and DMD chip three 255c, which corresponds to green prism 210). Then, each DMD chip 255 reflects its corresponding colored light (i.e., a first DMD chip 255a reflects blue light, a second DMD chip 255b reflects red light, and a third DMD chip 255c reflects green light). The "On state" light is recombined and reflected by the projection lens 150 onto the display screen, while the "off state" light is absorbed within the projector. The DMD aperture one 280a corresponds to the DMD chip one 255a, the DMD aperture two 280b corresponds to the DMD chip two 255b, and the DMD aperture three 280c corresponds to the DMD chip three 255c for modulation and reflection back to the projection lens. The first sealant 235, the first glass 220, the second glass 225, the third glass 227, the fourth glass 230, the sealing tape 240, and the second sealant 245 form a protective covering for the inner surfaces of the blue prism 200, the red prism 205, and the green prism 210, and the DMD chips one 255a, 255b, and 255c to be free from atmospheric contaminants without using a metal can housing, thereby enabling better heat dissipation.

As shown in fig. 5A, the light path of the green light is shown for viewing. In this figure, there is shown a blue prism 200, a red prism 205, a green prism 210, a DMD chip one 255a, a DMD chip two 255b, and a DMD chip three 255c, a TIR prism assembly 215, on state light 500, off state light 510, transmitted white light 520, transmitted green light 530, and TIR prism face 540. The On-state light 500 is light reflected from the DMD chip three 255c, which is projected through the projection lens 150. off-state light 510 is light reflected from the DMD chip three 255c, which is not projected and absorbed within the projector. The transmitted white light 520 is the white light that enters the DLP prism device 140 from the optical relay lens 130. The transmitted green light 530 is green light separated from the blue and red components by passing through the blue prism 200 and the red prism 205. The TIR prism face 540 is the front face of the TIR prism assembly 215.

In operation, transmitted white light 520 enters the TIR prism assembly 215 from the bottom and reflects off the TIR prism facets 540 and passes through the blue prism 200 and the red prism 205 before reaching the green prism 210. Blue and red light is filtered out of the transmitted white light 520 by using dichroic coatings on the blue prism 200 and the red prism 205. The transmitted green light 530 reaches the DMD chip three 255c where it is selectively reflected as either on-state light 500 or off-state light 510. The On-state light 500 passes through the green prism 210, the red prism 205, the blue prism 200, and the TIR prism assembly 215, and is then projected. The Off state light 510 is reflected upward within the projector and is not projected.

As shown in fig. 5B, it is the path of the off-state light. In this view, blue prism 200, red prism 205, green prism 210, TIR prism assembly 215, DMD chip one 255a, 255b, 255c, transmitted white light 520, transmitted blue light 550, reflected blue light 555, transmitted red/green light 560, transmitted red light 562, reflected red light 564, transmitted green light 530, reflected green light 535, reflected red/green light 565, reflected projected light 570, blue prism face 580, blue prism face 585, red prism face 590, red prism face 595, and TIR prism face 540 are shown.

As shown in fig. 5A, transmitted blue light 550 is blue light separated from transmitted white light 520. The reflected blue light 555 is the blue light reflected from the DMD chip one 255 a. The transmitted red/green light 560 is red and green light separated from the transmitted white light 520. The transmitted red light 562 is red light separated from the transmitted red/green light 560. The reflected red light 564 is red light reflected from the DMD chip two 255 b. The transmitted green light 530 is green light separated from the transmitted red/green light 560. The reflected green light 535 is the green light reflected from the DMD chip three 255 c. Reflected red/green light 565 is combined reflected red light 564 and reflected green light 535. Reflected projected light 570 is combined reflected blue light 555 and reflected red/green light 565. The blue prism face 580 is a face of the blue prism 200 for reflecting blue light by total internal reflection. Blue prism face 585 is one face of blue prism 200, which serves to separate blue light from transmitted white light 520 by the dichroic coating and to reflect the blue light. The red prism face 590 is one face of the red prism 205 that serves to separate red light from the transmitted red/green light 565 by the dichroic coating and to reflect the red light. The red prism face 595 is one face of the red prism 205, which is used to reflect red light by total internal reflection.

As shown in fig. 5A and 5B, the transmitted white light 520 enters the TIR prism assembly 215 and is reflected by the TIR prism facets 540. The transmitted white light 520 reaches blue prism face 585 where the transmitted blue light 550 is separated from the transmitted white light 520 by using a dichroic coating and reflected. Transmitted blue light 550 is then reflected from blue prism face 580 to DMD chip one 255 a. DMD chip one 255a reflects light and transmits on-state light 500 and reflected blue light 555, the reflected blue light 555 being reflected by blue prism 200 and blue prism face 580 to recombine with the other reflected components of light, reflected red/green light 565.

The transmitted red/green light 560 reaches the red prism face 590 where the transmitted red light 562 is separated from the transmitted red/green light 560 by using a dichroic coating and reflected. The transmitted red light 562 is then reflected from the red prism face 595 to the DMD chip two 255 b. DMD chip two 255b reflects light and transmits on-state light 500 and reflected red light 564, which reflected red light 564 reflects from red prism face 590 and recombines with reflected green light 535 into reflected red/green light 565.

The transmitted green light 530 reaches the DMD chip three 255c where it is reflected. The transmitted green light 530 then reaches the red prism face 590 where it is recombined with reflected red light 564 into reflected red/green light 565. Reflected red/green light 565 combines with reflected blue light 555 into reflected projected light 570 and exits DLP prism sub-assembly 160.

As shown in fig. 5C, where the light path is shown for viewing. Encapsulant three 135 is used to seal the vertical air gap at the intersection of blue prism 200, red prism 205, and green prism 210. The sealing tape 140 is used to seal air gaps between the blue prism 200 and the red prism 205 and between the red prism 205 and the green prism 210.

As shown in fig. 1, 2A, 2B, 2C, 3, 4A, 4B, 5A, 5B and 5C, a combination of glass one 220, 225, 227 and 230, encapsulant one 235, sealing tape 240 and encapsulant two 245 are used to protect the DMD chips one 255A, 255B and 255C in the DLP light engine system 100 from atmospheric contaminants while allowing sufficient heat dissipation. Thus, the TIR condition is satisfied for transmitted white light 520, on state light 500, off state light 510, transmitted blue light 550, reflected blue light 555, transmitted red/green light 560, transmitted red light 562, reflected red light 564, reflected projected light 570, TIR prism face 540, blue prism face 580, and red prism face 595.

As another example, as shown in fig. 6, the TIR prism assembly 215 includes a first prism 610, a second prism 620 and a third prism 630, wherein the LG plane of the second prism 620 is disposed parallel to the DMD device, and the LG plane is the incident plane of the DMD; in the second prism 620, a first prism 610 and a third prism 630 are respectively arranged on two LD surfaces and GH surfaces adjacent to the LG surface of the incident surface; the BC surface of the first prism 610 is opposite to the LD surface of the second prism 620, the FM surface of the third prism 630 is opposite to the GH surface of the second prism 620, certain air gaps 600 are arranged between the BC surface and the LD surface and between the FM surface and the GH surface at intervals, and the three prisms are glued together from the side by a glass clamping plate; the air gap 600 takes a value between 50 μm and 100 μm, the prism is easily attached together when the air gap is less than 50 μm, the total reflection condition cannot be met, and the relative displacement between the refracted light beam and the incident light beam is too large when the air gap 600 is too large.

As shown in fig. 7, the light beam enters through the first prism 610 and the second prism 620 at a certain angle, and then enters into the DMD through the first prism 610 and the second prism 620, and when the DMD is in the "on" state, the reflected light is totally reflected on the LD surface and exits from the EF surface through S3. When the DMD is in a flat state, the reflected light rays are emitted from the LD surface and the DH surface after being subjected to multiple total reflections on the LD surface and the GH surface. When the DMD is in an 'off' state, the reflected light rays are emitted from the LD and DH surfaces after multiple total reflections on the LD and GH surfaces. That is, when the DMD is in three different states, the "off" and "flat" light beams after passing through the TIR prism assembly 215 and the "on" light beams are emitted from different surfaces, so as to completely separate the light beams in the three different states, prevent the non-imaging light beams from entering the projection system and affecting the imaging quality, and realize the modulation of the "on", "flat" and "off" states of the DMD. Different infrared materials can be selected to meet the use requirements of different working wave bands. The invention solves the problem that the imaging quality is seriously influenced because the center of a projected image has an inevitable bright line because a light beam entering a projection system passes through the intersected edges of three prisms when passing through a TIR prism (see zl201310071235.5 for details).

The TIR prism assembly 215 of the present embodiment can make the whole optical engine structure more compact, reduce the volume of the illumination and projection system, and improve the energy utilization rate of the system, in addition, it completely separates the light beam in the "flat" and "off" states from the light beam in the "on" state, improves the projection contrast, avoids the flat bright spot generated in the "flat" state, and it can make the principal ray of the incident light beam after the incident light beam passes through the TIR prism in the DMD and then parallel to the optical axis of the projection system, and it has good imaging quality, good uniformity, and no bright line or bright spot. The problem that before entering the projection system, the on-state light beam in the patent must pass through the intersected edges of three prisms, so that a bright line seriously influencing the imaging quality appears in the center of an image is solved.

As an example, when the working wavelength band of the infrared scene projector is 3-5 μm, the materials selected by the prism are CaF2, ZnSe and GaAs, etc.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims

1. A prism assembly comprising more than two prisms, wherein at least one prism comprises one or more surfaces for total internal or partial spectral reflection of incident light, at least a portion of one of the surfaces for reflective purposes being covered by an element, the element being spaced from the surface with a gap between the surface and the element, the gap being sealed by a seal, the seal being provided on one prism to prevent contaminants from entering the gap.

2. The prism assembly of claim 1 wherein the component comprises a plate or a light reflecting valve or another prism of the prism assembly.

3. The prism assembly according to claim 1, wherein the sealing member comprises at least one sealant.

4. The prism assembly according to claim 3, wherein the sealant is capable of withstanding temperatures above 80 ℃ and the sealant is resistant to ultraviolet light.

5. The prism assembly of claim 3, wherein the encapsulant comprises silicone or silicone rubber.

6. A digital light processing prism apparatus, characterized in that the prism apparatus comprises a total internal reflection, TIR, prism assembly and a color prism assembly, the TIR prism assembly comprising two triangular prisms extending in a first direction, one of the surfaces of the TIR prism opposing each other, the color prism assembly comprising one quadrangular prism having one surface facing the surface of one color triangular prism, one triangular prism having a second surface facing the first surface of one color triangular prism, the other color prism having a second surface partly facing the surface of one of the TIR prisms, wherein all opposing surfaces have a gap between them, which gap is sealed by a seal arranged on the prism.

7. A digital light processing prism apparatus according to claim 6, wherein each color prism is provided with a light reflection valve on one surface thereof, the light reflection valve having a gap with the corresponding surface, the gap being sealed by a sealing member provided on the light reflection valve and the prism.

8. A digital light processing prism apparatus according to claim 6, characterized in that the outwardly oriented surfaces of the TIR prisms and the outwardly oriented surfaces of the color prisms for total internal reflection or partial spectral reflection of the image building portion of the incoming light are covered with elements spaced apart from the surfaces with a gap between the surfaces and the elements, said gap being sealed by a seal arranged on one of the prisms to prevent contaminants from entering the gap.