CN110677632A

CN110677632A - DLP projector capable of improving color uniformity of projected image

Info

Publication number: CN110677632A
Application number: CN201910969705.7A
Authority: CN
Inventors: 饶钦和; 李衡; 岳德举; 白金刚
Original assignee: Guangdong Union University Optoelectronics Co Ltd
Current assignee: Guangdong Union University Optoelectronics Co Ltd
Priority date: 2019-10-12
Filing date: 2019-10-12
Publication date: 2020-01-10

Abstract

The invention relates to a DLP projector for improving the color uniformity of a projected image, which comprises: an illumination system serving as a light source; the dichroic mirror group is used for separating light emitted by the light source into first color light, second color light and third color light; three DLP light modulation devices for receiving images to be presented by the first to third color lights and modulating the first to third color lights into first to third signal lights; the light combiner is used for mixing the first signal light, the second signal light, the third signal light and the fourth signal light to obtain projection light; and a projection lens for projecting the projection light onto an external screen; the sizes of the images to be presented by the first to third color lights on the respective received DLP light modulation devices differ by no more than 3%, and the optical paths of the first to third color lights from the dichroic mirror to the respective DLP light modulation devices are on the same plane. The technical scheme of the invention can improve the uniformity of the color.

Description

DLP projector capable of improving color uniformity of projected image

Technical Field

The invention relates to the technical field of projection, in particular to a DLP projector capable of improving the color uniformity of a projected image.

Background

A projector, also called a projector, is a device that can project images or video onto a screen. With the advancement and breakthrough of technology, the mainstream projectors in the market have been occupied by conventional CRT three-gun type projectors, and gradually by DLP (digital light Processor) projectors. Compared with the traditional CRT projector, the DLP projector has the advantages of bright color, rich levels, high saturation and the like, is widely popular with consumers, and is widely applied to scenes such as life entertainment, academic lectures, business exhibition and the like.

In some application scenarios, such as the status and information of the transportation industry, the large screen of the game image is facing upward, and the need for correct color display is high. With the increase of projection screens and the sensitivity of human eyes to chromatic aberration, the improvement and optimized design of the optical path of the DLP projector are required, and the existing DLP projector does also provide requirements for the improvement of color uniformity.

Disclosure of Invention

In view of the above, there is a need to provide a DLP projector with an improved optical path system, which can improve the color uniformity of the projected image and reduce the color shift compared to the conventional technology.

One aspect provides a DLP projector for improving color uniformity of a projected image, comprising:

an illumination system serving as a light source;

the dichroic mirror group is used for separating light emitted by the light source into first color light, second color light and third color light;

three DLP light modulation devices for receiving images to be presented by the first to third color lights and modulating the first to third color lights into first to third signal lights;

the light combiner is used for mixing the first signal light, the second signal light, the third signal light and the fourth signal light to obtain projection light; and

a projection lens for projecting the projection light onto an external screen;

the sizes of the images to be presented by the first to third color lights on the respective received DLP light modulation devices differ by no more than 3%, and the optical paths of the first to third color lights from the dichroic mirror to the respective DLP light modulation devices are on the same plane.

The images to be presented by the first through third color lights are the same size on each corresponding received DLP light modulating device and are oriented the same on the external screen.

The light source of the illumination system is a white light source or a multi-wavelength light source.

The first to third color lights are red, green and blue light respectively.

The DLP projector has a lens or a reflecting mirror on a light path between the illumination system and the dichroic mirror or between the dichroic mirror and the DLP light modulation device.

The transmittance of each dichroic mirror is 50%, but the wavelengths of light that each dichroic mirror can transmit are different.

The DLP projector further includes a color filter.

A second aspect provides a DLP projection system comprising a DLP projector and a screen; the DLP projector is the DLP projector.

The DLP projector may have an optical axis of a projection lens connected to the center of the screen.

The DLP projector provided by the embodiment of the invention comprises a lighting system, a dichroic mirror, a DLP light modulator, a light combiner and a projection lens, wherein the first to third color lights obtained by splitting by the dichroic mirror have the image size difference on the DLP light modulation devices respectively corresponding to no more than 3%, and light paths from the dichroic mirror to the DLP light modulation devices are on the same plane, so that compared with the traditional technology, the uniformity of the color of a displayed image is provided.

Drawings

FIG. 1 is a schematic structural diagram of a DLP projection system for improving color uniformity of a projected image according to an embodiment of the present invention;

fig. 2 is a schematic optical path diagram of a DLP projector for improving color uniformity of a projected image according to an embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention belong to the protection scope of the present invention.

Referring to fig. 1, a DLP projection system for improving the color uniformity of a projected image is provided in an embodiment of the present invention. The DLP projection system includes a DLP projector 1 and a screen 2. The application scene of the DLP projection system can be a large-scale game competition display platform or other commercial or entertainment industry information display platforms, the screen is large, the requirement on color display is high, the requirement on color uniformity is also met, and color shift cannot be contained. The existing DLP projector has stronger distortion sense when the viewer watches the image color along with the enlargement of the screen. There is thus a need for an improved optical path for DLP projectors therein.

Specifically, referring to the embodiment of fig. 1, the DLP projector includes:

an illumination system serving as a light source;

a projection lens for projecting the projection light onto an external screen;

the sizes of the images to be presented by the first to third color lights on the corresponding received DLP light modulation devices are different by no more than 3%, and the light paths of the first to third color lights from the dichroic mirror to the DLP light modulation devices are on the same plane.

The working principle of the DLP projector according to the embodiment of the present invention will be described in detail with reference to the schematic optical path diagram shown in fig. 2.

The optical path of fig. 2 is a schematic optical path of the example of fig. 1 of the present invention, and only includes the optical devices necessary for explaining the present invention. In the optical path, other portions that can realize light integration, light guide, optical communication are not within the limitation of the present embodiment.

In the embodiment of fig. 2, the illumination system 52 in the DLP projector may be a single light source, or may have multiple light sources, and may be a single light source or a combination of light sources that produce white light, or a multi-wavelength light source that approximates white light. Illumination system 52 may also include an elliptical or parabolic reflector that emits multiple wavelengths of light toward a set of dichroic mirrors.

The set of dichroic mirrors in the embodiment of fig. 2 are two dichroic mirrors, each having a 50% transmission, each dichroic mirror transmitting (or reflecting) a different range of light wavelengths. The white light or multi-wavelength light emitted from the illumination system 52 is split into light rays in 3 wavelength ranges or three colors, i.e., first, second, and third color lights, by passing through the dichroic mirror twice. Preferably, the first, second and third color lights may correspond to three primary colors, respectively.

The first through third colors of light are intended to represent substantially each color component of the overall image (e.g., R, G, B). The image of each color light is fed to a DLP light modulation device, which modulates it. The DLP light modulation device includes a plurality of DMD cells (each digital micromirror may correspond to a pixel), each pixel being independently addressable and drivable to convert first through third color lights into first through third signal lights. In the optical path diagram of fig. 2, 3 DLP light modulating devices are schematically depicted at 56a, 56b and 56 c. As mentioned above, the optical path of the embodiment of the present invention may further include other integration devices, and only the components related to the present invention are described herein. In order to improve the color uniformity of the image, the size of the image to be rendered by each color light may be adjusted so that the size difference between them is not more than 3%, preferably not more than 0.5%. In some existing DLP projectors, the DLP light modulation device is configured to be three-dimensional, which also affects the uniformity of light color, and the light paths from the dichroic mirror to the DLP light modulation device of the respective color lights are arranged in the same plane, so that color shift can be effectively reduced, that is, the

light path portions

76a, 76b, and 76c in fig. 2 are in the same plane.

In fig. 2, 70 is a light combiner for combining the images representing the color components into a complete image, and 72 is a projection lens for magnifying the image onto an external screen. The optical axis of the projection lens may be at the center of the screen.

Further, referring to FIG. 2, to direct the sub-beams onto the light modulation device, additional optical components are used, which may be lenses and/or mirrors (e.g., 54). The lenses are typically made of optical glass with standard anti-reflective coatings on both sides. The lens may also be made of other materials, such as quartz, but optical glass is preferred because it is cheaper. The mirrors are typically made of float glass and have a standard reflective coating on one side. Color filters (e.g., 78) may also be added in this embodiment at times, for example, to further separate colors.

In summary, the DLP projector according to the embodiments of the present invention includes an illumination system, a dichroic mirror, a DLP light modulator, a light combiner, and a projection lens, wherein the first to third color lights split by the dichroic mirror have an image size difference on the respective DLP light modulation devices of not more than 3%, and light paths from the dichroic mirror to the DLP light modulation devices are on the same plane, so as to provide uniformity of display image colors compared with the conventional technology.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A DLP projector for improving the color uniformity of projected images, comprising:

an illumination system serving as a light source;

a projection lens for projecting the projection light onto an external screen;

2. The DLP projector as claimed in claim 1 wherein the images to be presented by said first through third color lights are the same size on each corresponding receiving DLP light modulating device and are oriented the same on the external screen.

3. The DLP projector as claimed in claim 2, wherein the light source of the illumination system is a white light source or a multi-wavelength light source.

4. The DLP projector as claimed in claim 3, wherein the first to third color lights are red, green and blue lights.

5. The DLP projector as claimed in claim 3 or 4, wherein the DLP projector has a lens or a mirror on the light path between the illumination system and the dichroic mirror or between the dichroic mirror and the DLP light modulation device.

6. The DLP projector as claimed in claim 1 wherein each dichroic mirror has a 50% transmission but each dichroic mirror transmits a different wavelength of light.

7. The DLP projector as claimed in claim 2, wherein said DLP projector further comprises a color filter.

8. A DLP projection system, comprising a DLP projector and a screen; the DLP projector as claimed in claim 1, wherein the DLP projector is capable of improving the color uniformity of the projected image.

9. The DLP projection system according to claim 8, wherein the optical axis of a projection lens in said DLP projector is connectable to the center of said screen.