EP-4741886-A1 - PRISM STRUCTURE, OPTICAL SYSTEM, OPTICAL DISPLAY APPARATUS, AND TERMINAL DEVICE

EP4741886A1EP 4741886 A1EP4741886 A1EP 4741886A1EP-4741886-A1

Abstract

A prism structure (620), an optical system (320), an optical display apparatus (300), and a terminal device are disclosed, to enhance contrast of imaging of a projection lens (340 or 640). The optical system (320) includes the prism structure (620). The prism structure (620) includes a first layer (Q1), a second layer (Q2), and a third layer (Q3) that are sequentially stacked. A fourth side surface (L 24 ) of the second layer (Q2) is blackened. The first layer (Q1) is configured to guide an illumination light beam into the second layer (Q2) or guide out a non-projection light beam. The second layer (Q2) is configured to: guide the illumination light beam into a display chip (630), reflect a projection light beam reflected from the display chip (630) to the third layer (Q3), and guide a non-projection light beam reflected from the display chip (630) to a third side surface or guide a non-projection light beam reflected from the display chip (630) to the first layer (Q1). The third layer (Q3) is configured to guide the projection light beam into the projection lens (340 or 640). The non-projection light beam is guided to a blackened prism surface for absorption or is guided out from the prism structure (340), so that the non-projection light beam in the optical system (320) can be effectively suppressed, a probability that the non-projection light beam enters the projection lens (340 or 640) to participate in imaging is reduced, and projection contrast is enhanced.

Inventors

TONG, Kainian
ZHAO, DONGFENG
Chen, Xiangyu

Assignees

Shenzhen Yinwang Intelligent Technologies Co., Ltd.

Dates

Publication Date: 20260513
Application Date: 20240729

Claims (20)

A prism structure, comprising: a first triangular prism, a quadrangular prism, and a second triangular prism, wherein the first triangular prism comprises three quadrangular side surfaces and two triangular main surfaces, the quadrangular prism comprises four quadrangular side surfaces and two quadrangular main surfaces, and the second triangular prism comprises three quadrangular side surfaces and two triangular main surfaces; a second side surface of the first triangular prism is attached to a first side surface of the quadrangular prism, a second side surface of the quadrangular prism is attached to a first side surface of the second triangular prism, and a fourth side surface of the quadrangular prism is blackened; and the first side surface of the quadrangular prism and the second side surface of the quadrangular prism are two opposite surfaces, and the fourth side surface of the quadrangular prism is a surface that is connected to the first side surface of the quadrangular prism and the second side surface of the quadrangular prism and that is opposite to a third side surface of the second triangular prism.
An optical system, comprising a prism structure, wherein a display chip is placed in a first direction of the prism structure, a projection lens is placed in a second direction of the prism structure, the prism structure comprises a first layer, a second layer, and a third layer that are sequentially stacked in the second direction, and a fourth side surface that is of the second layer and that is in an opposite direction of the first direction is blackened; the first layer is configured to guide an illumination light beam into the second layer or guide out a non-projection light beam; the second layer is configured to: guide the illumination light beam into the display chip, reflect a projection light beam reflected from the display chip to the third layer, and guide a non-projection light beam reflected from the display chip to the fourth side surface, or guide out a non-projection light beam reflected from the display chip to the first layer; and the third layer is configured to guide the projection light beam into the projection lens.
The optical system according to claim 2, wherein the third layer is further configured to reflect the non-projection light beam reflected from the display chip to the fourth side surface.
The optical system according to claim 2 or 3, wherein the projection light beam comprises a light beam reflected from the display chip at a first deflection angle; and the non-projection light beam comprises a light beam reflected from the display chip at a second deflection angle and a light beam reflected from the display chip at a third deflection angle, wherein different deflection angles correspond to different states of the display chip.
The optical system according to any one of claims 2 to 4, wherein the prism structure is the prism structure according to claim 1, the first layer is the first triangular prism, the second layer is the quadrangular prism, the third layer is the second triangular prism, the display chip is placed on an outer side of a third side surface of the quadrangular prism, and the projection lens is placed on an outer side of a second side surface of the second triangular prism.
The optical system according to claim 5, wherein an included angle between the first side surface of the quadrangular prism and the third side surface of the quadrangular prism is 45°.
The optical system according to claim 5 or 6, wherein the second side surface of the second triangular prism is perpendicular to the third side surface of the second triangular prism.
The optical system according to any one of claims 5 to 7, wherein the third side surface of the quadrangular prism and the third side surface of the second triangular prism are located on a same plane, and the display chip is located below the plane.
The optical system according to any one of claims 5 to 8, wherein the fourth side surface of the quadrangular prism is parallel to the third side surface of the quadrangular prism, and an area of the fourth side surface of the quadrangular prism is less than an area of the third side surface of the quadrangular prism.
The optical system according to any one of claims 5 to 9, wherein a part of the non-projection light beam reflected from the display chip undergoes one or more reflections within the quadrangular prism, a part of the non-projection light beam is guided to the fourth side surface of the quadrangular prism, and a part of the non-projection light beam is guided out of the prism structure after being reflected to the first triangular prism.
The optical system according to claim 10, wherein another part of the non-projection light beam reflected from the display chip is refracted to the fourth side surface of the quadrangular prism through the third side surface of the quadrangular prism.
The optical system according to claim 10 or 11, wherein still another part of the non-projection light beam reflected from the display chip is reflected to the fourth side surface of the quadrangular prism through the second side surface of the second triangular prism.
The optical system according to any one of claims 5 to 12, wherein the projection light beam reflected from the display chip is reflected to the second side surface of the quadrangular prism through the first side surface of the quadrangular prism, is refracted to the second side surface of the second triangular prism from the second side surface of the quadrangular prism, and is guided out to the projection lens from the second side surface of the second triangular prism.
The optical system according to claim 13, wherein the non-projection light beam reflected from the display chip is reflected to the second side surface of the quadrangular prism through the first side surface of the quadrangular prism, and is reflected to the fourth side surface of the quadrangular prism from the second side surface of the quadrangular prism.
The optical system according to claim 14, wherein an incident angle of the projection light beam on the second side surface of the quadrangular prism is less than an incident angle of the non-projection light beam on the second side surface of the quadrangular prism.
The optical system according to claim 13 or 14, wherein a tilt angle of the second side surface of the quadrangular prism and a refractive index of a material of the quadrangular prism are selected such that the projection light beam is transmitted on the second side surface of the quadrangular prism and the non-projection light beam is reflected from the second side surface of the quadrangular prism.
The optical system according to any one of claims 13 to 16, wherein an incident angle, on the second side surface of the quadrangular prism, of a projection light ray having a maximum incident angle in the projection light beam is less than a critical angle for total reflection corresponding to the second side surface of the quadrangular prism, and an incident angle, on the second side surface of the quadrangular prism, of a projection light ray having a minimum incident angle in the non-projection light beam is greater than or equal to the critical angle for total reflection corresponding to the second side surface of the quadrangular prism.
The optical system according to any one of claims 5 to 17, wherein the refractive index of the material of the quadrangular prism is the same as a refractive index of a material of the second triangular prism.
The optical system according to any one of claims 5 to 18, wherein a non-effective optical path part of one or more outer surfaces of the prism structure other than the fourth side surface of the quadrangular prism is blackened.
The optical system according to any one of claims 5 to 19, wherein the second triangular prism is fastened to or integrated with a lens element that is closest to the second triangular prism and that is in the projection lens.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 202310984749.3, filed with the China National Intellectual Property Administration on August 4, 2023, and entitled "PRISM STRUCTURE, OPTICAL SYSTEM, OPTICAL DISPLAY APPARATUS, AND TERMINAL DEVICE", which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to the field of optical technologies, and in particular, to a prism structure, an optical system, an optical display apparatus, and a terminal device. BACKGROUND In recent years, with development of projection display technologies, people have increasingly high requirements for projection display effect. Among many projection display technologies, a digital light processing (digital light processing, DLP) technology is increasingly popular in the market due to its high brightness and high contrast, and gradually becomes a mainstream technical solution in the field of projection display. To implement a compact structure, a total internal reflection (total internal reflection, TIR) prism or a reverse total internal reflection (reverse total internal reflection, RTIR) prism is typically used in a DLP display apparatus to couple illumination light. However, in existing prism solutions, non-projection light beams generated by the DLP display apparatus also enter a projection lens and participate in projection. After undergoing one or more reflections or refractions in the projection lens, these non-projection light beams form stray light on a final image plane, affecting contrast of final imaging. In conclusion, how to enhance the contrast of imaging of the projection lens is a technical problem that urgently needs to be resolved currently. SUMMARY This application provides a prism structure, an optical system, an optical display apparatus, and a terminal device, to enhance contrast of imaging of a projection lens. According to a first aspect, this application provides a prism structure, including a first triangular prism, a quadrangular prism, and a second triangular prism. The first triangular prism includes three quadrangular side surfaces and two triangular main surfaces. The quadrangular prism includes four quadrangular side surfaces and two quadrangular main surfaces. The second triangular prism includes three quadrangular side surfaces and two triangular main surfaces. A second side surface of the first triangular prism is attached to a first side surface of the quadrangular prism, a second side surface of the quadrangular prism is attached to a first side surface of the second triangular prism, and a fourth side surface of the quadrangular prism is blackened. The first side surface of the quadrangular prism and the second side surface of the quadrangular prism are two opposite surfaces, and the fourth side surface of the quadrangular prism is a surface that is connected to the first side surface of the quadrangular prism and the second side surface of the quadrangular prism and that is opposite to a third side surface of the second triangular prism. In the foregoing solution, the fourth side surface of the quadrangular prism is blackened. In this way, the non-projection light beam can be guided to the blackened fourth side surface for absorption, so that the non-projection light beam in the prism structure can be effectively suppressed, and a relatively pure projection light beam enters the projection lens for imaging, to enhance projection contrast of the projection lens. In addition, in the prism structure, non-projection light can be suppressed by simply blackening a prism surface. Therefore, no additional display chip needs to be added, no additional angle-selective film layer needs to be coated, and no angle and position constraint of the prism structure needs to be carefully designed for guiding out the non-projection light beam. This further reduces a volume, costs, and weight of the prism structure. According to a second aspect, this application provides an optical system, including a prism structure. A display chip is placed in a first direction of the prism structure, a projection lens is placed in a second direction of the prism structure, the prism structure includes a first layer, a second layer, and a third layer that are sequentially stacked in the second direction, and a fourth side surface that is of the second layer and that is in an opposite direction of the first direction is blackened. When the optical system works, the first layer is configured to guide an illumination light beam into the second layer or guide out a non-projection light beam. The second layer is configured to: guide the illumination light beam into the display chip, reflect a projection light beam reflected from the display chip to the third layer, and guide a non-projection light beam reflected from the display chip to a fourth side surface or guide out a non-projection light beam reflected from the display chip to th