Projection device

The invention provides a projection device including a first display, a second display, a third display, a light-combining module, a first angle selector, a second angle selector, a third angle selector, and a projection lens. The first display, the second display, and the third display are respectively adapted to provide a first image beam, a second image beam, and a third image beam. The projection lens is configured on one side of a light-outgoing surface of the light-combining module, and is adapted to project the first image beam, the second image beam, and the third image beam out of the projection device. The first image beam, the second image beam, and the third image beam respectively pass through the first angle selector, the second angle selector, and the third angle selector, and are then transmitted to the projection lens by the light-combining module.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. 202011515371.5, filed on Dec. 21, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The invention relates to an optical device, particularly to a projection device.

Description of Related Art

The light source device required by a three-color-combined light projector that uses a light valve system of a digital light processor (DLP) or Liquid Crystal on Silicon (LCoS) has a complex optical system, which results in its huge volume. The advantage of using a three-chip micro-LED display panel with a light-combining system is that the size of the projection device may be reduced.

However, the greatest problem of using the three-chip micro-LED display panel with the light-combining system is the large light-emitting angle of the micro-LED. The method of reducing this angle is to add a reflective cover and to use a micro-LED array (that is, a micro-optical array), but the light-emitting half-angle can only be reduced by 20 degrees (under the condition of a pixel size of less than 5 μm). Moreover, as the light-emitting angle to be reduced is restricted, due to the large light-emitting half-angle and the total reflection inside the light-combining system (light greater than the effective light angle is only totally reflected inside the light-combining module), ineffective light is therefore introduced into the projection lens, leaving stray light appearing on the projected image, which affects the contrast of the projected image.

SUMMARY

The invention provides a projection device capable of effectively reducing stray light from transmitting out of the projection device through a light-combining module, and increasing the contrast of the projected image.

An embodiment of the present invention provides a projection device, which includes a first display, a second display, a third display, a light-combining module, a first angle selector, a second angle selector, a third angle selector, and a projection lens. The first display, the second display, and the third display are respectively adapted to provide a first image beam, a second image beam, and a third image beam. The light-combining module has a first light-incident surface, a second light-incident surface, a third light-incident surface, and a light-outgoing surface. The first angle selector is configured between the first display and the light-combining module. The second angle selector is configured between the second display and the light-combining module. The third angle selector is configured between the third display and the light-combining module. The projection lens is configured on one side of the light-outgoing surface of the light-combining module, and is adapted to project the first image beam, the second image beam, and the third image beam out of the projection device. The first image beam, the second image beam, and the third image beam respectively pass through the first angle selector, the second angle selector, and the third angle selector, and are then transmitted to the projection lens by the light-combining module.

Based on the above, in an embodiment of the present invention, since the projection device is provided with the first angle selector, the second angle selector, and the third angle selector, stray light of the projection device may be reduced effectively, so that the projected image has higher contrast.

DESCRIPTION OF THE EMBODIMENTS

FIG.1is a schematic diagram of a projection device according to an embodiment of the present invention. InFIG.1, an embodiment of the present invention provides a projection device10, including a first display110, a second display120, a third display130, a light-combining module200, a first angle selector310, a second angle selector320, a third angle selector330, and a projection lens400.

In this embodiment, the first display110, the second display120, and the third display130may be a liquid crystal display panel, a LED display panel, a mini LED display panel, or a micro-LED display panel, but the present invention is not limited thereto.

In this embodiment, the light-combining module200is, for example, a light-combining prism (X-Cube) formed by bonding four prisms, and the refractive index of the bonding agent is preferably the same as that of the prisms, but the manufacturing method described above is not limited to the manufacturing method of the light-combining module200. In the above configuration, every two adjacent prism surfaces may be provided with an optical film (for example, provide the film by coating), so that the beam with a specific wavelength in the image beam that is transmitted to the prism surface is reflected, whereas the image beams in the rest of the wavelength ranges pass through the prism surface.

In this embodiment, the first angle selector310, the second angle selector320, and the third angle selector330may be optical films formed by stacking high and low refractive indexes.

In this embodiment, the projection lens400includes, for example, a combination of one or more optical lenses with diopter. Optical lenses include various combinations of non-planar lenses, such as biconcave lenses, biconvex lenses, meniscus lenses, convex-concave lenses, plano-convex lenses, and plano-concave lenses. The present invention does not limit the form and type of the projection lens400.

Specifically, the first display110, the second display120, and the third display130of this embodiment are adapted to provide a first image beam R, a second image beam G, and a third image beam B, respectively. The first image beam R is, for example, a red light image beam; the second image beam G is, for example, a green light image beam; and the third image beam B is, for example, a blue light image beam. However, the invention is not limited thereto.

In this embodiment, the light-combining module200has a first light-incident surface210, a second light-incident surface220, a third light-incident surface230, and a light-outgoing surface240. The first light-incident surface210is opposite to the third light-incident surface230, the second light-incident surface220is opposite to the light-outgoing surface240, and the second light-incident surface220is connected between the first light-incident surface210and the third light-incident surface230. The first angle selector310is disposed between the first display110and the light-combining module200. The second angle selector320is disposed between the second display120and the light-combining module200. The third angle selector330is disposed between the third display130and the light-combining module200. The first angle selector310, the second angle selector320, and the third angle selector330are respectively disposed on one side of the first light-incident surface210, the second light-incident surface220, and the third light-incident surface230of the light-combining module200.

In this embodiment, the first image beam R, the second image beam G, and the third image beam B respectively pass through the first angle selector310, the second angle selector320, and the third angle selector330, and then are transmitted to the projection lens400as light combined by the light-combining module200. The projection lens400is disposed on one side of the light-outgoing surface240of the light-combining module200and is adapted to project the first image beam R, the second image beam G, and the third image beam B out of the projection device10. The first image beam R is reflected to the projection lens400by the optical film of the light-combining module200that has the function of reflecting the red-light waveband, the second image beam G passes through the light-combining module200and transmits to the projection lens400, and the third image beam B is reflected to the projection lens400by the optical film of the light-combining module200that has the function of reflecting the blue-light waveband. The two optical films above are configured in X-type.

In this embodiment, the first angle selector310is a filter (band pass filter), such as a red-light wavelength filter. For example, when light is incident perpendicularly to the first angle selector310, the light of a wavelength falling within the range of 610 to 650 nm is transmitted to pass through it whereas the light of the rest of the wavelengths is reflected. Moreover, the first angle selector310transmits light whose incident angle is less than 30 degrees (<30°) to pass through it and reflects light whose incident angle is 30 degrees or more (≥30°).

In this embodiment, the second angle selector320is a filter, such as a green-light wavelength filter. For example, when light is incident perpendicularly to the second angle selector320, the light of a wavelength falling within the range of 510 to 550 nm is transmitted to pass through it and the light of the rest of the wavelengths is reflected. Moreover, the second angle selector320transmits light whose incident angle is less than 30 degrees (<30°) to pass through it and reflects light whose incident angle is 30 degrees or more (≥30°).

In this embodiment, the third angle selector330is a filter, such as a blue-light wavelength filter. For example, when light is incident perpendicularly to the third angle selector330, the light of a wavelength falling within the range of 400 to 465 nm is transmitted to pass through it and the light of the rest of the wavelengths is reflected, or, for example, the light whose wavelength is less than or equal to 465 nm is transmitted to pass through it and the light of the rest of the wavelengths is reflected. Moreover, the third angle selector330transmits light whose incident angle is less than 30 degrees (<30°) to pass through it and reflects light whose incident angle is 30 degrees or more (≥30°).

In this embodiment, the projection device10further includes a first anti-reflection layer510, a second anti-reflection layer520, and a third anti-reflection layer530. The first anti-reflection layer510, the second anti-reflection layer520, and the third anti-reflection layer530are respectively disposed on the first light-incident surface210, the second light-incident surface220, and the third light-incident surface230.

In this embodiment, the projection device10further includes a fourth anti-reflection layer540, and the fourth anti-reflection layer540is disposed on the light-outgoing surface240. Since the projection device10is provided with the first anti-reflection layer510, the second anti-reflection layer520, the third anti-reflection layer530, and the fourth anti-reflection layer540, the light-outgoing efficiency of the projection device10of the embodiment of the present invention is improved effectively.

FIG.2is a schematic diagram of stray light in a projected image of a projection device provided with a third angle selector according to an embodiment of the present invention. InFIG.2, the left image shows the stray light formed at the light-outgoing surface of the light-combining module200, and the right image shows the stray light formed by the light emerging from the projection lens400. InFIG.2, in the effective projected image, the stray light is reduced by 66%, and the stray light outside the effective projected image is only about 55%.

Based on the above, in an embodiment of the present invention, since the projection device10is provided with: the first angle selector310located between the first display110and the light-combining module200, the second angle selector320located between the second display120and the light-combining module200, and the third angle selector330located between the third display130and the light-combining module200, thus large-angle image light that is more likely to have total internal reflection in the light-combining module200is reflected by the first angle selector310, the second angle selector320, and the third angle selector330and does not enter the light-combining module200. As the incident angle of the image beam incident to the light-combining module200is restricted effectively, the stray light of the projection device10is reduced, thereby improving the contrast of the projected image.

FIG.3is a schematic diagram of a projection device according to another embodiment of the present invention. InFIG.3, the projection device10′ ofFIG.3is similar to the projection device10ofFIG.1, and their main differences are that: in the projection device10′ ofFIG.3, a first angle selector310, a second angle selector320, and a third angle selector330are respectively (and directly) configured on a first light-incident surface210, a second light-incident surface220, and a third light-incident surface230, and therefore, the overall volume of the projection device10′ is reduced. A light-outgoing surface240of a light-combining module200of the projection device10′ has a fourth anti-reflection layer540, so that the light-outgoing efficiency of the projection device10′ of the embodiment of the present invention is improved effectively.

In summary, in an embodiment of the present invention, since the projection device is provided with a first angle selector located between the first display and the light-combining module, a second angle selector located between the second display and the light-combining module, and a third angle selector located between the third display and the light-combining module, the stray light of the projection device is reduced effectively, and the contrast of the projected image is higher.