CN114252943B

CN114252943B - Prism unit and projection device using the same

Info

Publication number: CN114252943B
Application number: CN202210096570.XA
Authority: CN
Inventors: 朱县雄; 范春荣; 柏先林
Original assignee: Shenzhen Kejinming Electronic Co Ltd
Current assignee: Shenzhen Kejinming Electronic Co Ltd
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2022-06-21
Anticipated expiration: 2042-01-26
Also published as: CN114252943A

Abstract

The invention relates to the technical field of projection, and discloses a prism unit and a projection device using the same, which are used for solving the problem of insufficient color gamut. The prism unit comprises at least six prisms, a first side surface and a second side surface of the first prism are respectively attached and fixed to first side surfaces of the second prism and the fourth prism, a first side surface and a second side surface of the third prism are respectively attached and fixed to second side surfaces of the second prism and the fourth prism, a first side surface of the fifth prism is attached and fixed to a third side surface of the third prism, and a first side surface of the sixth prism is attached and fixed to a second side surface of the fifth prism; the third side surface of the first prism is used as a first color light incident surface, the third side surface of the second prism is used as a second color light incident surface, the third side surface of the fourth prism is used as a third color light incident surface, the second side surface of the sixth prism is used as a compensation light incident surface, the third side surface of the sixth prism is used as a light combination and emergence surface, and the sixth prism is a total internal reflection prism.

Description

Prism unit and projection device using the same

Technical Field

The invention belongs to the technical field of projection, and particularly relates to a prism unit and a projection device using the same.

Background

A projector is a device that can project an image or video onto a curtain, and the mainstream projectors are classified into three types: DLP projector, single LCD projector, 3LCD projector. Among them, the 3LCD projector has good color performance, and is certainly used by the wide range of users.

However, the inventor has found that, in the conventional 3LCD projector, the prism unit generally includes two prisms, wherein the first surface of the first prism 12A is attached to one surface of the second prism 12B and serves as a light incident surface, the second surface of the first prism 12A serves as a light emergent surface, the laser beam emitted from the light source is homogenized and emitted to the light combining prism unit, the light combining prism unit totally reflects the incident beam to the LCD panel, and the modulated beam is emitted from the LCD panel to the lens for imaging. Due to the temperature and light fastness of the LCD panel, the wavelength band width directly incident on the 3-color system has a problem of insufficient color gamut.

Disclosure of Invention

The invention relates to the technical field of projection, in particular to a prism unit and a projection device using the same, which are used for solving the technical problem that the existing prism unit can cause insufficient color gamut.

A prism unit comprises a first prism, a second prism, a third prism, a fourth prism, a fifth prism and a sixth prism, wherein a first side surface and a second side surface of the first prism are respectively attached and fixed to the first side surfaces of the second prism and the fourth prism, a first side surface and a second side surface of the third prism are respectively attached and fixed to the second side surfaces of the second prism and the fourth prism, a first side surface of the fifth prism is attached and fixed to the third side surface of the third prism, and a first side surface of the sixth prism is attached and fixed to the second side surface of the fifth prism;

the third side of the first prism is used as a first color light incident surface, the third side of the second prism is used as a second color light incident surface, the third side of the fourth prism is used as a third color light incident surface, the second side of the sixth prism is used as a compensation light incident surface, the third side of the sixth prism is used as a light combination emergent surface, and the sixth prism is a total internal reflection prism.

In one embodiment, the top surfaces of all the first prism, the second prism, the third prism, the fourth prism, the fifth prism and the sixth prism are on the same plane.

In one embodiment, at least one of the first, second, third, fourth, fifth and sixth prisms has a top surface that is not coplanar with the top surfaces of the other prisms.

In one embodiment, the first prism, the second prism, the third prism and the fourth prism have top surfaces on a first plane, the fifth prism and the sixth prism have top surfaces on a second plane, and the first plane and the second plane are different planes.

In one embodiment, the first plane and the second plane form an angle greater than 90 degrees.

In an embodiment, first prism, second prism, third prism, fourth prism and sixth prism are right angle prism, the contained angle of the first side of fifth prism and third side is greater than 90 degrees, the first side and the second side of first prism are two adjacent perpendicular sides, the first side and the second side of second prism are two adjacent perpendicular sides, the first side and the second side of third prism are two adjacent perpendicular sides, the first side and the second side of fourth prism are two adjacent perpendicular sides, the first side and the second side of sixth prism are two adjacent perpendicular sides.

In an embodiment, when the first color light is incident on the third side surface of the first prism, the first color light sequentially transmits through the first prism and the second prism to enter the third prism, and/or sequentially transmits through the first prism and the fourth prism to enter the third prism, and the first color light transmits through the third prism and the fifth prism and then exits from the third side surface of the sixth prism;

when the second color light enters the third side face of the second prism, part of the second color light is reflected to the third prism by the second prism, is transmitted through the third prism and the fifth prism and is transmitted out of the third side face of the sixth prism; another part of the second color light passes through the second side surface of the second prism to reach the third prism, is reflected by the third prism, is guided to the fifth prism, is transmitted through the fifth prism and is transmitted out of the third side surface of the sixth prism;

when the third color light enters the third side surface of the fourth prism, part of the third color light is reflected to the third prism by the fourth prism, is transmitted through the third prism and the fifth prism and is transmitted out of the third side surface of the sixth prism; another part of the third color light passes through the second side surface of the fourth prism to reach the third prism, is reflected by the third prism, is guided to the fifth prism, is transmitted through the fifth prism and is transmitted out of the third side surface of the sixth prism;

when the compensating light enters the second side face of the sixth prism, the compensating light is transmitted into the third side face of the sixth prism, and the compensating light is reflected to the first side face of the sixth prism by the third side face of the sixth prism, then reflected to the third side face of the sixth prism by the first side face of the sixth prism and transmitted out.

In one embodiment, each of the light beams transmitted from the sixth prism is parallel light.

In an embodiment, the prism unit is a prism unit as described in any of the previous embodiments.

In one embodiment, the projection device further comprises a first light source, a first fly-eye lens, a second fly-eye lens, a first condenser lens, a first beam splitter, a first reflector, a first LCD panel, a second beam splitter, a second LCD panel, a relay lens, a second reflector, a second condenser lens, a third reflector, a third LCD panel, a second light source, a light-equalizing system, and a fourth LCD panel;

white light emitted by the first light source is subjected to light equalization treatment by the first fly-eye lens and the second fly-eye lens in sequence and then enters the first condenser lens for condensation, a condensed light beam enters the first spectroscope, and after the first spectroscope reflects second color light in the condensed light beam, the reflected second color light is guided to the first reflector by the first reflector, and is reflected again by the first reflector and guided to the second LCD panel; the other wavelengths of light in the condensed light beam are transmitted by the first spectroscope and reach the second spectroscope, the first color light in the second spectroscope is reflected to the first LCD panel by the second spectroscope, the third color light reaching the second spectroscope is transmitted by the second spectroscope, sequentially reaches the relay lens and the second reflector, is reflected to the second spectroscope by the second reflector, and passes through the third reflector to reach the third LCD panel; the target light beam emitted by the first light source passes through the light-equalizing system and then irradiates the fourth LCD panel;

the first LCD panel modulates the first color light and outputs the modulated first color light to irradiate the third side surface of the first prism; the second LCD panel modulates the second color light and outputs the modulated second color light to be incident to a third side face of the second prism, the third LCD panel modulates the third color light and outputs the modulated third color light to be incident to a third side face of the fourth prism, and the fourth LCD panel modulates the target light beam output by the light equalizing system to compensation light and emits the modulated compensation light to a second side face of the sixth prism.

In the prism unit of the present invention, a fifth prism is bonded and fixed to a third side surface of the third prism, the third prism is bonded and fixed to a sixth prism, and the first to fourth prisms are bonded and fixed to surround each other, so that the third side surfaces of the first, second, and third prisms may form a color light incident surface, a second side surface of the sixth prism may serve as a compensation light incident surface to form a four-path light path, and the sixth prism is a total internal reflection prism, and the four-path light combined light may be emitted from the third side surface of the sixth prism for use in projection by being guided by the fifth prism and the sixth prism. Therefore, the prism unit provided by the invention can be used for combining four paths of light, can be used for compensating the whole color gamut of projection, and can also be used for improving the brightness.

Drawings

FIG. 1 is a schematic diagram of a prism unit according to an embodiment of the present invention;

FIG. 2 is a schematic top view of a prism unit according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of light transmission of a prism unit according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a projection apparatus using a prism unit according to an embodiment of the present invention.

The reference numbers in the drawings of the specification are as follows:

0-a first light source, 1-a first fly-eye lens, 2-a second fly-eye lens, 3-a first condenser lens, 4-a first beam splitter, 5-a second beam splitter, 6-a relay lens, 7-a second mirror, 8-a second condenser lens, 9-a third mirror, 10-a first mirror, 11A-a first LCD panel, 11B-a second LCD panel, 11C-a third LCD panel, 11D-a fourth LCD panel, 12-a prism unit, 12A-a first prism, 12B-a second prism, 12C-a third prism, 12D-a fourth prism, 12E-a fifth prism, 12F-a sixth prism.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1-4, embodiments of the invention provide a prism unit 12 and a projection apparatus using the prism unit, which are described in detail below.

Referring to fig. 1-2, fig. 1 is a schematic diagram illustrating an overall structure of a prism unit 12 according to an embodiment of the present invention, and fig. 1 is a top plan view illustrating a prism unit 12 according to an embodiment of the present invention, where the prism unit 12 may be a profiled columnar structure, the prism unit 12 includes at least six prism units, and the at least six prism units are fixed to form the prism unit 12. For convenience of description, the six prism units are referred to as a first prism 12A, a second prism 12B, a third prism 12C, a fourth prism 12D, a fifth prism 12E, and a sixth prism 12F in this order. In one embodiment, the prisms refer to triangular prisms each including five faces, i.e., a top face, a bottom face, and three side faces, wherein the three side faces of each prism are referred to as a first side face, a second side face, and a third side face in the present invention. The plane corresponding to the plane of the top view shown in fig. 2 is the top surface of the prism.

In this embodiment, the first side surface and the second side surface of the first prism 12A are respectively bonded and fixed to the first side surfaces of the second prism 12B and the fourth prism 12D, the first side surface and the second side surface of the third prism 12C are respectively bonded and fixed to the second side surfaces of the second prism 12B and the fourth prism 12D, the first side surface of the fifth prism 12E is bonded and fixed to the third side surface of the third prism 12C, and the first side surface of the sixth prism 12F is bonded and fixed to the second side surface of the fifth prism 12E. In some embodiments, the prisms may be fixed by gluing. The third side surface of the first prism 12A is used as a first color light incident surface, the third side surface of the second prism 12B is used as a second color light incident surface, the third side surface of the fourth prism 12D is used as a third color light incident surface, the second side surface of the sixth prism 12F is used as a compensation light incident surface, the third side surface of the sixth prism 12F is used as a combined light emitting surface, and the sixth prism is a total internal reflection prism. Illustratively, the first color light is green light, the second color light is blue light, and the third color light is red light, and the compensation light is compensation light required by the projection apparatus in projection imaging, and the compensation light may be modulated light, for example, in some embodiments, the compensation light is light emitted after being modulated by an LCD panel. It should be noted that, in this embodiment and the following embodiments, for convenience of description, the description will be given by taking this as an example, and the description is not particularly limited. When the projection device uses the prism unit, the whole position of the prism or the incidence of colored light can be adjusted according to the position relation with other devices, and the projection device is not limited specifically.

In this embodiment, the differences from the conventional prism unit include: in the prism unit of the present invention, a fifth prism 12E is bonded and fixed to a third side surface of a third prism 12C, the third prism 12E is bonded and fixed to a sixth prism 12F, and the first to fourth prisms are bonded and fixed to surround each other, so that the third side surfaces of the first, second, and third prisms may form a color light incident surface, a second side surface of the sixth prism 12F may serve as a compensation light incident surface to form a four-path light path, and the four-path light incident surface may be guided by the fifth prism 12E and the sixth prism 12F, and the sixth prism may be a total internal reflection prism, and may emit the four-path light combined from the third side surface of the sixth prism 12 for projection. Therefore, the prism unit provided by the invention can be used for combining four paths of light, can be used for compensating the whole color gamut of projection, and can also be used for improving the brightness.

In one embodiment, the top surfaces of all of the first, second, third, fourth, fifth and

sixth prisms

12A, 12B, 12C, 12D, 12E and 12F are all in the same plane, while in other embodiments, at least one of the top surfaces of the first, second, third, fourth, fifth and

sixth prisms

12A, 12B, 12C, 12D, 12E and 12F is not in the same plane as the other prisms. For example, as shown in fig. 2, the top surfaces of the first prism 12A, the second prism 12B, the third prism 12C, and the fourth prism 12D are all on a first plane, the top surfaces of the fifth prism 12E and the sixth prism 12F are all on a second plane, and the first plane and the second plane are different planes. It can be seen that the prism unit 12 of the present invention can have various alternatives or embodiments, and the top surfaces of all prisms are on the same plane, so that the prism unit 12 is flush with the whole, which facilitates the subsequent internal structure design and mold opening of the projector. The gate prisms of all prisms are not planar, so that the light beams can be adjusted conveniently, for example, as shown in fig. 2, the second plane where the fifth prism 12E and the sixth prism 12F are located is "tilted" upward relative to the first plane, and the bottom surfaces of all prisms are on the same plane, so that the light beams transmitted from the fifth prism 12E can be incident from the light emitting surface of the sixth prism 12F, and the light conversion rate is improved. In one embodiment, as shown in fig. 2, the second plane, in some embodiments, the first plane and the second plane form an angle greater than 90 degrees, so as to avoid the prism unit 12 from occupying too much space under the condition of ensuring the optical path of the light beam as reasonable as possible.

In one embodiment, the first prism 12A, the second prism 12B, the third prism 12C, the fourth prism 12D, and the sixth prism 12F are right-angle prisms, so-called right-angle prisms, which refer to prisms in which two adjacent side surfaces of the prisms are perpendicular to each other, in this embodiment, the first side surface and the second side surface of the first prism 12A are two adjacent vertical side surfaces, the first side surface and the second side surface of the second prism 12B are two adjacent vertical side surfaces, the first side surface and the second side surface of the third prism 12C are two adjacent vertical side surfaces, the first side surface and the second side surface of the fourth prism 12D are two adjacent vertical side surfaces, and the first side surface and the second side surface of the sixth prism 12F are two adjacent vertical side surfaces. The vertical surfaces of the first prism 12A, the second prism 12B, the third prism 12C, and the fourth prism 12D are bonded and fixed, so that, when viewed from the top, the bonding lines form a cross shape to form a cross-shaped color separation prism, that is, the color separation prism formed by the first prism 12A, the second prism 12B, the third prism 12C, and the fourth prism 12D has a hexahedron shape formed by bonding the prisms of the four prisms. In one embodiment, the four straight prisms of the first prism 12A, the second prism 12B, the third prism 12C, and the fourth prism 12D are identical straight prisms, and the whole of the first prism 12A, the second prism 12B, the third prism 12C, and the fourth prism 12D after bonding appears as a cube.

In addition, in an embodiment, an included angle between the first side surface and the third side surface of the fifth prism 12E is greater than 90 degrees, the top surfaces of the fifth prism 12E and the sixth prism 12F are located on the same plane and have the same height, and the second side surface of the fifth prism 12E is attached to the first side surface of the sixth prism 12F and is partially exposed, so that the reflecting surface of the sixth prism 12F is large enough, and after the supplement light enters from the second side surface of the sixth prism 12F, the sixth prism 12F can emit the supplement light from the third side surface of the sixth prism after performing total internal reflection twice on the supplement light, and the light entering the sixth prism cannot be refracted to a place outside the prism, and the supplement light can be fully utilized.

It should be noted that, in an embodiment, referring to fig. 3 in combination with fig. 2, an arrow trend line in fig. 3 is a light beam trend line, when a first color light (green light) of a first LCD panel 11A (also called a light valve) enters a third side of the first prism 12A, the first color light (green light) sequentially transmits through the first prism 12A and the second prism 12B to enter the third prism 12C, and/or sequentially transmits through the first prism 12A and the fourth prism 12D to enter the third prism 12C, and the first color light (green light) transmits through the third prism 12C and the fifth prism 12E and then exits from the third side of the sixth prism 12F.

When the second color light (blue light) emitted from the second LCD panel 11B enters the third side surface of the second prism 12B, a part of the second color light (blue light) is reflected by the second prism 12B to the third prism 12C, transmitted through the third prism 12C and the fifth prism 12E, and transmitted out of the third side surface of the sixth prism 12F; another part of the second color light (blue light) passes through the second side surface of the second prism 12B to reach the third prism 12C, is reflected by the third prism 12C, is guided to the fifth prism 12E, is transmitted through the fifth prism 12E, and is transmitted out of the third side surface of the sixth prism 12F;

when the third color light (red light) emitted from the third LCD panel 11C enters the third side of the fourth prism 12D, part of the third color light (red light) is reflected by the fourth prism 12D to the third prism 12C, transmitted through the third prism 12C and the fifth prism 12E, and transmitted through the third side of the sixth prism 12F; another part of the third color light (green light) reaches the third prism 12C through the second side surface of the fourth prism 12D, is reflected by the third prism 12C, is guided to the fifth prism 12E, is transmitted through the fifth prism 12E, and is transmitted out of the third side surface of the sixth prism 12F;

when the compensation light emitted from the fourth LCD panel 11D enters the second side surface of the sixth prism 12F, the compensation light is transmitted into the third side surface of the sixth prism 12F, and the compensation light is reflected to the first side surface of the sixth prism 12F by the third side surface of the sixth prism 12F, and is reflected to the third side surface of the sixth prism 12F by the first side surface of the sixth prism 12F and is transmitted.

It should be noted that, in order to enable the dichroic prism to form the required refraction or reflection path, a dichroic film may be used inside the dichroic prism, and then the light of the corresponding light paths is combined and emitted from the sixth prism 12F.

In this embodiment, after the light beams emitted from the first LCD panel 11A, the second LCD panel 11B, the third LCD panel 11C, and the fourth LCD panel 11D pass through the prism unit provided in the embodiment of the present invention, four light beams are finally formed through the above processing of the prism unit and emitted from the prism unit, so that the light beams after color synthesis project to the projection lens to form a projection, and since the fourth LCD panel is added to emit compensation light to the prism unit for light combination, the color gamut coverage and brightness of the final projection can be increased, and the present invention has higher practicability.

In an embodiment, each light beam transmitted from the sixth prism 12F is a parallel light, and the incident angle of each light beam entering the prism can be adjusted to make each light beam transmitted from the sixth prism 12F be a parallel light and projected to the curtain after passing through the projection lens, so that the scattering of light can be reduced, and the projection is more uniform.

In an embodiment, there is provided a prism unit using the prism unit 12 of any one of the above embodiments.

In an embodiment, the projection apparatus further includes a first light source 0, a first fly-eye lens 1, a second fly-eye lens 2, a first condenser lens 3, a first beam splitter 4, a first reflector 10, a first LCD panel 11A, a second beam splitter 5, a second LCD panel 11B, a relay lens 6, a second reflector 7, a second beam splitter 8, a third reflector 9, a third LCD panel 11C, a second light source (not shown), a light-equalizing system (not shown), and a fourth LCD panel 11D. In the projection apparatus using the prism unit 12, white light emitted by the first light source 0 sequentially passes through the first fly-eye lens 1 and the second fly-eye lens 2 for light equalizing treatment to obtain uniform light beams, and then the uniform light beams are incident on the first condenser lens 3 for light condensing to obtain condensed light beams, the light equalizing treatment can make the light beams uniform, and the obtained condensed light beams are incident on the first beam splitter 4, wherein the first beam splitter 4 is configured to reflect second color light (blue light) and transmit light with other wavelengths, and after the first beam splitter 4 reflects the second color light (blue light) in the condensed light beams, the second color light (blue light) is reflected by the first reflector 4 and guided to the first reflector 10, and is reflected by the first reflector 10 and guided to the second LCD panel 11B again; light (including red and green light) of other wavelengths in the condensed light beam is directly transmitted through the first beam splitter 4 and reaches the second beam splitter 5, the first color light (green light) of the light beam is reflected by the second beam splitter 5 to the first LCD panel 11A, the third color light (red light) reaching the second beam splitter 5 is transmitted through the second beam splitter 5 and sequentially reaches the relay lens 6 and the second reflector 7, and is reflected by the second reflector 7 to the second condenser 8, and the third color light (red light) coming out of the second condenser 8 passes through the third reflector 9 to reach the third LCD panel 11C; an object beam emitted by the first light source (not shown in the figure) passes through the light-equalizing system and then irradiates the fourth LCD panel 11D;

the first LCD panel 11A modulates the first color light (green light) and outputs the modulated first color light (green light) to irradiate into the third side of the first prism 12A unit; the second LCD panel 11B modulates the second color light (green light) and outputs the modulated second color light (green light) to enter the third side surface of the second prism 12B unit, the third LCD panel 11C modulates the third color light (red light) and outputs the modulated third color light (red light) to enter the third side surface of the fourth prism 12D, and the fourth LCD panel 12D modulates the target light beam output by the light equalizing system to compensation light and emits the modulated compensation light to the second side surface of the sixth prism 12F. In this way, the modulated light beams entering the prism unit 12 are combined and projected from the projection lens of the projection apparatus to form a projection, that is, the projection lens projects the combined affected light, and in this embodiment, the compensation light may be a component including yellow light and modulated based on the video signal, and the luminance and the color gamut coverage of the projection may be efficiently modulated. It should be noted that, in the projection apparatus, the four LCD panels are an optical modulation apparatus, and each color light and compensation light may be adjusted according to the image requirement to be projected, so that the prism unit provided in the embodiment of the present invention is used to combine light, on one hand, the modulated compensation light of the second light source and the fourth LCD panel is used to supplement light, and if the compensation yellow light component is modulated based on the image to overlap with the green light, the brightness and the color gamut coverage of projection imaging are increased, and in addition, a light equalizing system is further added in the second light source and the second LCD panel, so that the compensation light does not affect the uniformity of projection imaging while the brightness and the color gamut are improved, so that the brightness or the color gamut of projection imaging is more uniform, and the projection quality is improved.

It should be noted that, in some embodiments, due to the limitations of the LCD panel itself, taking the third LCD panel 11C of the red light incident panel as an example, since the light beam reaching the third LCD panel 11C is elliptically polarized light, when the red light reflected from the third reflector 9 enters the third LCD panel 11C, in the third LCD panel, the polarizing plate of the red light incident surface may polarize the elliptically polarized red light into linearly polarized light, so that the linearly polarized light passes through, thereby functioning to pass only the polarized light in the fixed direction modulated in the LCD panel 11C, and reducing the unnecessary light component. For still other LCD panels, the above operation can be referred to as well, and the detailed description is not repeated here.

In some embodiments, a chromatic aberration adjusting mirror may be further disposed between the third LCD panel 11C and the prism unit 12, so that the magnification of the modulated red light entering the prism unit 12 is increased, and the magnification of each modulated light forms a light beam required for projection, thereby improving the projection quality. In some embodiments, the chromatic aberration adjustment mirror may be attached to the third side of the fourth prism 12C in the prism unit 12 in an elastic pressing manner, so as to reduce influence on modulated light caused by other bonding manners.

In some embodiments, the projection apparatus further includes a fifth LCD panel, and the fifth LCD panel modulates the synthesized light of the prism unit 12 and outputs the modulated light to the projection lens for projection.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A prism unit is characterized by comprising a first prism, a second prism, a third prism, a fourth prism, a fifth prism and a sixth prism, wherein a first side surface and a second side surface of the first prism are respectively fixedly attached to the first side surfaces of the second prism and the fourth prism, a first side surface and a second side surface of the third prism are respectively fixedly attached to the second side surfaces of the second prism and the fourth prism, a first side surface of the fifth prism is fixedly attached to the third side surface of the third prism, and a first side surface of the sixth prism is fixedly attached to the second side surface of the fifth prism;

the third side surface of the first prism is used as a first color light incident surface, the third side surface of the second prism is used as a second color light incident surface, the third side surface of the fourth prism is used as a third color light incident surface, the second side surface of the sixth prism is used as a compensation light incident surface, the third side surface of the sixth prism is used as a light combination emitting surface, the sixth prism is a total internal reflection prism, and four paths of light combination are emitted from the third side surface of the sixth prism to be used in projection;

first prism, second prism, third prism, fourth prism and sixth prism are right angle prism, the first side and the second side of first prism are two adjacent perpendicular sides, the first side and the second side of second prism are two adjacent perpendicular sides, the first side and the second side of third prism are two adjacent perpendicular sides, the first side and the second side of fourth prism are two adjacent perpendicular sides, the first side and the second side of sixth prism are two adjacent perpendicular sides.

2. The prism unit according to claim 1, wherein top surfaces of all of the first, second, third, fourth, fifth, and sixth prisms are on the same plane.

3. The prism unit of claim 1, wherein the top surface of at least one of the first, second, third, fourth, fifth, and sixth prisms is not coplanar with the top surfaces of the other prisms.

4. A prism unit according to claim 3, wherein the top surfaces of the first, second, third and fourth prisms are all in a first plane, the top surfaces of the fifth and sixth prisms are all in a second plane, and the first and second planes are different planes.

5. A prism unit according to claim 4, wherein the first plane is angled more than 90 degrees from the second plane.

6. A prism unit according to any one of claims 1 to 5, wherein the first side surface and the third side surface of the fifth prism include an angle of more than 90 degrees.

7. The prism unit according to any one of claims 1 to 5, wherein when a first color light is incident on the third side surface of the first prism, the first color light is transmitted through the first prism and the second prism in sequence into the third prism, and/or is transmitted through the first prism and the fourth prism in sequence into the third prism, and the first color light is transmitted through the third prism and the fifth prism and then is emitted from the third side surface of the sixth prism;

8. The prism unit according to claim 7, wherein each of the light beams transmitted from the sixth prism is parallel light.

9. A projection apparatus using a prism unit, wherein the prism unit is the prism unit according to any one of claims 1 to 8.

10. The projection device of claim 9, further comprising a first light source, a first fly-eye lens, a second fly-eye lens, a first condenser lens, a first beam splitter, a first reflector, a first LCD panel, a second beam splitter, a second LCD panel, a relay lens, a second reflector, a second condenser lens, a third reflector, a third LCD panel, a second light source, a light equalizing system, and a fourth LCD panel;