WO2018212479A1

WO2018212479A1 - Imaging device

Info

Publication number: WO2018212479A1
Application number: PCT/KR2018/004829
Authority: WO
Inventors: 류재열; 빅토르비치 무라베브니콜라이; 예브게니에비치 피스쿠노브드미트리; 바체슬라보비치 포포브미하일; 니콜라이비치 안드레이푸틸린; 알렉산드로비치 만코안드레이; 빅토르비치 모로조브알렉산더
Original assignee: 삼성전자 주식회사
Priority date: 2017-05-15
Filing date: 2018-04-26
Publication date: 2018-11-22

Abstract

An imaging device is provided. The imaging device comprises: a display for emitting light which represents a predetermined image; a first polarization plate which is arranged in front of the display and polarizes the light in a first linear polarizing state; a first retarder which is arranged in front of the first polarization plate and changes the first linear polarizing state of the light to a first circular polarizing state; a first optical element which includes a cholesteric liquid crystal layer and transmits the light, which is incident after passing through the first retarder, in the first circular polarizing state; a second retarder which is arranged in front of the first optical element and changes the first circular polarizing state of the light to a second linear polarizing state; and a second optical element which includes a second polarization plate and changes the second linear polarizing state of the light to a second circular polarizing state by reflecting the light to the first optical element, which is incident in the second linear polarizing state, through the second retarder.

Description

Imaging device

TECHNICAL FIELD The present disclosure relates to the field of image technology, and more particularly, to an image device capable of generating high quality images.

High resolution imaging devices are increasingly used for various purposes, especially for VR applications. The development and enhancement of VR devices has opened up new possibilities for users in various fields. For example, a user wearing a VR helmet or VR glasses can quickly and easily immerse themselves in the desired VR environment, for example, to simulate different situations while actually sitting at home. The use of such a VR environment in the video game industry is well known, but it can be applied very well to all other industries.

In particular, VR devices are generally used as follows.

-In the army for battlefield, combat situations or medical training

-In the education industry for e-learning purposes

-In the medical field for virtual reality diagnosis and virtual robot surgery

-In the business community for virtual travel, educational purposes

-In the field of communications for video conferencing and telemedicine

Preferred or essential for the applications listed above is that the VR device is mounted on the head so that the wearer's hand can move freely and easily, to hold the required object, eg a gun, in a battlefield or combat situation. The mobility of the wearer is also affected by the weight and size of the VR device itself. Various attempts have been made to solve this problem, but some of them have been to replace the conventional optical mirrors with liquid crystal films, thin film polarizers, etc., and to reduce the number of optical elements to thin the optical elements included in the VR devices. The smaller the number of elements, the smaller the optical path in the overall system, which must be done with care, as this can lead to degradation of image quality.

US Pat. No. 5853240 discloses a small, lightweight liquid crystal projector combined with a head mounted device (HMD) for projecting an image from a HMD or a 3D image onto a common screen. The HMD has an optical device in the casing for enlarging an image of the liquid crystal panel illuminated by the backlight. The optical device includes a half mirror coated refractive element and a cholesteric liquid crystal element that acts as a translucent mirror that selects circular-polarized-light. This prior art solution still uses a translucent mirror (ie half-mirror), which does not significantly reduce the overall size and weight of the overall system.

U. S. Patent No. 6094242 discloses an optical HMD device comprising a refractor comprising a half mirror coated refractive element and a translucent mirror that selects one-polarized light, arranged in order from the side on which light is incident. The translucent mirror is composed of a quarter wave plate (phase difference plate), a half mirror and a polarizing plate or cholesteric liquid crystal arranged in order from the incidence side. Thin-film high-magnification optics employs a semi-transparent mirror that reflects incident light first in a clockwise circularly polarized manner and selects circularly polarized light that transmits anti-clockwise circularly polarized light without reflection in 1.5 round trips. It is obtained by using. However, this prior art solution cannot be used for light beams of both linear and circularly polarized light, thus reducing possible applications.

US Pat. No. 6,866,194 includes a cholesteric liquid crystal for displaying a planar image, a fiber plate for converting the displayed planar image into a spherical image, and an eyepiece optical system having first and second spherical translucent reflecting surfaces and projecting the spherical image. A display device is disclosed. However, this prior art solution does not offer the possibility of using light beams of linear and circularly polarized light simultaneously. Also, the resulting image is always spherical.

Therefore, there is a need for an imaging device capable of producing high quality images with low weight and small volume, and capable of operating simultaneously on light beams of two different polarization states. It is further desirable that such an image device is head mounted and applied to a VR application.

Embodiments of the present invention provide an imaging device having a low weight and a small volume.

An imaging apparatus according to an embodiment of the present invention, a display for emitting light representing a predetermined image; A first polarizer disposed in front of the display and polarizing the light in a first linearly polarized state; A first retarder disposed in front of the first polarizing plate and configured to change the first linearly polarized state of the light to a first circularly polarized state: the first circularly polarized light incident after passing through the first retarder A first optical element for transmitting light in a state; A second retarder, disposed in front of the first optical element, for changing the first circularly polarized state of the light to a second linearly polarized state; And a second optical element for reflecting the light incident in the second linear polarization state to the first optical element through the second retarder to change the second linear polarization state of the light to a second circular polarization state; Wherein the first optical element is configured to reflect the light in the second circularly polarized state back to the second optical element through the second retarder, thereby converting the second circularly polarized state into the first linearly polarized state. To.

The second optical element may transmit the light in the first linearly polarized state to the eyes of a user.

The first optical element may include a cholesteric liquid crystal layer, and light in a first circularly polarized state may pass through the first optical element, or may be formed by the alignment of liquid crystal molecules of the cholesteric liquid crystal layer. The light in the two circularly polarized state may be changed to the first linearly polarized state.

The first optical element may include at least one of a lens and an optical film, and the cholesteric liquid crystal layer may be disposed on the surface of the lens or the optical film or may be embedded in the lens or the optical film. have.

The lens or optical film may also be formed of an optically transparent material selected from one of optical glass, optical crystals and polymers.

The second optical element may include a second polarizing plate.

In addition, the second polarizing plate may be a wire grid polarizing plate.

The wire grid polarizer may be formed of a parallel metal wire layer formed on the surface of the second optical element.

In addition, at least one of the first delayer and the second delayer may be a λ / 4 delayer.

The first retarder may include a switchable λ / 4 retarder composed of a liquid crystal layer sandwiched between two electrical contact layers, and the image device may operate in different modes, a first mode and a second mode. have.

Further, in the first mode, the transparent display is turned on and emits the light, and the liquid crystal molecules of the liquid crystal layer in the switchable [lambda] / 4 retarder emit the first circularly polarized light in the first circular state. Oriented to change to a polarization state, and in the second mode, the transparent display is turned off, and the liquid crystal molecules in the switchable [lambda] / 4 retarder allow the user's eye without reflection of ambient light passing through the transparent display. Can be oriented to be delivered to.

The imaging device may switch to the first mode in response to a predetermined voltage applied between the electrical contact layers, and to switch to the second mode when no voltage is applied between the electrical contact layers. Can be.

In addition, the image device may switch to the first mode and the second mode at a switching frequency of 120 Hz or more.

The display may include at least one of a liquid crystal display (LCD), a display based on a light emitting diode (LED), a display based on an organic LED (OLED), and a display based on a laser diode.

In addition, the first polarizer may be a thin film polarizer.

The imaging device may be integrated into at least one of a virtual device, an augmented reality device, and an optical system.

On the other hand, an image device according to another embodiment includes a display for emitting light representing a predetermined image; A first polarizer disposed in front of the display and polarizing the light in a first linearly polarized state; And a first optical element transmitting the light incident in the first linearly polarized state. A retarder disposed in front of said first optical element, said retarder for changing said light in said first linearly polarized state to a first circularly polarized state: and said first light in said first circularly polarized state through said retarder; A second optical element reflecting an optical element to change the first circularly polarized state of the light to a second linearly polarized state, wherein the first optical element comprises light of the second linearly polarized state through the retarder; The second linear polarization state of the light is changed to a second circular polarization state by reflecting back to the second optical element.

The second optical element may transmit light of the second circularly polarized state to the eyes of a user.

In addition, the first optical element may include a wire grid polarizer.

The second optical element may include a cholesteric liquid crystal layer, and the light of the first circularly polarized state may be changed to a second linearly polarized state by the alignment of liquid crystal molecules of the cholesteric liquid crystal layer. have.

1 is a diagram illustrating an image device, according to an exemplary embodiment.

FIG. 2 is a diagram illustrating an optical device and another optical device included in the image device of FIG. 1.

3 and 4 illustrate a switching element for the image device of FIG. 1.

5 is a diagram illustrating an image device, according to another exemplary embodiment.

Various embodiments of the present disclosure are described in more detail with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function set forth in the description below. On the contrary, these examples are provided to provide a detailed and complete description of the disclosure. In accordance with the description of the present disclosure, it will be apparent that the scope of the present disclosure includes any embodiments of the present disclosure disclosed herein, whether the embodiments are implemented independently or in conjunction with any other. For example, the apparatus disclosed herein may be implemented in practice by using any number of embodiments provided herein. In addition, it should be understood that any embodiment of the present disclosure may be implemented using one or more elements set forth in the appended claims.

The word "exemplary" is used herein to mean "used as an example or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or to be construed as having an advantage over other embodiments.

In the present specification, the term "cholesteric liquid crystal" is used in a general sense and refers to a liquid crystal having a helical structure and chiral. Cholesteric liquid crystals are also known as chiral nematic liquid crystals. These crystals are organized into layers without alignment in the layer. Due to the periodic structure (ie helical molecular orientation), cholesteric liquid crystals selectively reflect light components at a given wavelength. What is essential to the present disclosure is that cholesteric liquid crystals can be used that transmit the light beam of the first circularly polarized light to the maximum and reflect the light beam of the second circularly polarized light to the maximum.

As used herein, the term “polarizing plate” is used in a general sense and refers to an optical filter capable of passing a light beam in one polarization state and blocking a light beam in another polarization state. Polarizers are generally classified into linear polarizers and circular polarizers. The wire grid polarizer described herein is one of the simplest linear polarizers and may consist of several fine parallel metallic wires arranged in a particular plane. In this configuration of the wire grid polarizer, light is transmitted to be linearly polarized.

As used herein, the term “retarder” (or “wavelength plate”) is used in its general sense and refers to an optical device capable of altering the polarization state of the light passing through the retarder. One type of retarder used in denotes a λ / 4 retarder, wherein the λ / 4 retarder is configured to convert linearly polarized light into circularly polarized light and vice versa.

1 is a diagram illustrating an image device 100 according to an embodiment of the present disclosure. As shown in FIG. 1, the imaging apparatus 100 includes a display 102, a first polarizer 104, a first retarder 106, a first optical element 108, a second retarder 110, and And a second optical element 112. The apparatus 100 is described in more detail below.

The display 102 emits light representing a given image. Display 102 may be used in commercial electronic devices such as, for example, liquid crystal displays (LCDs), displays based on light emitting diodes (LEDs), displays based on organic LEDs (OLEDs), displays based on laser diodes, and the like. It may be any one of the available displays. As will be apparent to those skilled in the art, the selection of each display type depends on the particular application.

The first polarizer 104 is disposed in front of the display 102 and polarizes the light from the display 102 to a first linear polarization state, ie p-polarized (short p-state). The first linear polarization state is schematically illustrated in FIG. 1 with both arrows inclined to the left. In a preferred embodiment, the first polarizer 104 may be a thin film polarizer to reduce the volume of the overall image device 100. The type of thin film polarizer is well known in the art and thus will not be described herein.

The first retarder 106 is disposed in front of the first polarizer 104 and changes the p-state of light to the first circularly polarized state. The first circularly polarized state is a right circularly polarized (RHCP) state (ie, clockwise polarized state) and is schematically illustrated in FIG. 1. In a preferred embodiment, the first delay 106 is a λ / 4 delay, which is well known in the art.

The optical element 108 is disposed in front of the first retarder 106 and the cholesteric liquid crystal layer 114 is embedded therein. The liquid crystal molecules of the cholesteric liquid crystal layer 114 are oriented such that the RHCP-state light incident on the cholesteric liquid crystal layer 114 is transmitted after passing through the first retarder 106. In some other embodiments, the cholesteric liquid crystal layer 114 may be deposited on one surface of the first optical element 108, as shown in FIG. 2. Another embodiment of the first optical element 108 is shown in FIG. 2 as a lens or film design. In particular, each of the first optical element 108 and the second optical element 112 is a convex lens, a concave lens, a concave-convex lens, a convex-concave lens, a two-sided convex lens, a two-sided concave lens, a planar-, depending on the application. Convex lenses, planar-concave lenses, spherical lenses or aspherical lenses. In addition, the above-mentioned lens or film may be made of an optically transparent material including optical glass, optical crystals and polymers.

The second retarder 110 is disposed in front of the first optical element 108 and changes the RHCP-state of light to a second linearly polarized state, ie s-polarized (short s-state). The second linear polarization state is schematically illustrated in FIG. 1 with both arrows inclined to the right. In a preferred embodiment, the second delayer 112 may be a λ / 4 delay similar to the first delayer 106.

The second optical element 112 may be disposed in front of the second retarder 110, and the wire grid polarizer 116 may be disposed on the second optical element 112 (in another embodiment, the wire grid polarizer ( 116 may be impregnated into the second optical element 112 similarly to the cholesteric liquid crystal layer 114). The wire grid polarizer 116 reflects the light incident in the s-state to the first optical element 108 (that is, the cholesteric liquid crystal layer 114) through the second retarder 110, thereby s- Change the state to the second circularly polarized state. The second circularly polarized state is schematically shown at 1 as the left circularly polarized light (LHCP) state (ie, counterclockwise polarization state). The liquid crystal molecules of the cholesteric liquid crystal layer 114 described above are such that the light in the LHCP state is reflected back to the second optical element 112 through the second retarder 110 to change the LHCP state to the p-state. Can be oriented. The wire grid polarizer 116 allows p-state light to be delivered to the user's eyes.

Although the alignment state of the light passing through the imaging device 100 has been described above, it is apparent to those skilled in the art that the present invention is not limited to that shown in FIG. In another embodiment, for example, the LHCP-state may occur after light passes through the first retarder 106 and the RHCP-state may occur after light passes through the second retarder 110. That is, the first and

second delayers

106 and 110 may be used interchangeably. The same is true for the p-state and the s-state. For example, the first polarizer 104 can polarize light from the display 102 to the s-state (instead of the p-state). On the other hand, the second retarder 110 may change the circularly polarized light (ie, the RHCP- or LHCP-state) of the light incident thereon to the p-state (instead of the s-state as shown in FIG. 1). .

Techniques for forming the cholesteric liquid crystal layer 114 and the wire grid polarizer 116 are well known in the art. For example, as a process of forming a cholesteric liquid crystal layer, a process of filling a liquid crystal in a precursor exposed on one or both sides by using a vacuum method or a capillary effect may be used, and nanoimprint lithography to form a wire grid polarizer Process of laser interference lithography or soft lithography may be used.

3 and 4 show another embodiment. In Figures 3 and 4 the display 102 is implemented as a transparent display (not shown) and the first retarder 106 is between two electrical contact layers 304 (deposited on the substrate 306 in turn). It can be implemented as a switchable λ / 4 retarder 310 composed of a liquid crystal layer 302 sandwiched therein. With this configuration, the device 100 can operate in a first mode and a second mode. In the first mode, the transparent display is turned on to emit light, and the liquid crystal molecules in the switchable λ / 4 retarder 310 change the linearly polarized state (ie, p-state or s-state) to the circularly polarized state ( Ie, LHCP- or RHCP- state. In the second mode, the transparent display is turned off and the liquid crystal molecules in the switchable [lambda] / 4 retarder 310 are oriented to deliver ambient light passing through the transparent display to the user's eye without reflection. The electrical contact layer 304 may be made of ITO. In addition, the device 100 switches to the second mode when there is no voltage applied between the electrical contact layer 304 (FIG. 3), and the predetermined voltage Vq applied between the electrical contact layer 304 (FIG. 4). And in response to switching to the first mode. The apparatus 100 may be configured to switch to the first mode and the second mode at a switching frequency of 120 Hz or more. This switching arrangement makes it possible to alternately view an ambient scene and the image displayed on the display 102 at the switching frequency described above.

5 shows an image device 400 of yet another embodiment. The device 400 of FIG. 5 has a different number and arrangement of components compared to the device 100 of FIG. 1. In particular, the device 400 includes a display 402, a first polarizer 404, a first optical element 406, a retarder 408, and a second optical element 410. Display 402 emits light representing a given image. The first polarizer 404 is disposed in front of the display 402 and polarizes the light in a first linear polarization state (ie, p-state). The first optical element 406 includes a second polarizer 412 formed on the first optical element 406. The second polarizer 412 may be a wire grid polarizer configured to transmit incident light in a p-state. The retarder 408 is disposed in front of the first optical element 406 and changes the p-state of light to the first circularly polarized state (ie, the RHCP-state). The second optical element 410 includes a cholesteric liquid crystal layer 414 embedded therein (if necessary, the cholesteric liquid crystal layer 414 is one of the surfaces of the second optical element 410). May be deposited). The liquid crystal molecules of the cholesteric liquid crystal layer are oriented so that the light of the RHCP state incident on the cholesteric liquid crystal layer 414 is reflected toward the first optical element 406 through the retarder 408, and thus the light of RHCP Change the state to a second linearly polarized state (ie s-state). The wire grid polarizer 412 also reflects the s-state of light back through the retarder 408 to the second optical element 410 to reflect the s-state of the light to the second circularly polarized state (ie, the LHCP-state). To. The orientation of the molecules of the cholesteric liquid crystal causes the LHCP-state light to be delivered to the user's eye.

The present disclosure may be applied when a user needs to be immersed in virtual reality in order to perform various tasks such as 3D modeling, games, navigation, and design. It can also be applied to a variety of different head-mounted devices, such as glasses or helmets, which are currently widely used in the gaming device and education industry. The present disclosure can also be used in various optical systems such as projectors, collimators, telescopes, binoculars, range finders, 3D scanners and the like.

Further aspects of the present disclosure will become apparent upon consideration of the drawings and the foregoing description of embodiments of the present disclosure. Those skilled in the art will appreciate that other embodiments of the present disclosure are possible and that details of the disclosure may be modified in various respects without departing from the spirit of the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive. Unless otherwise indicated, elements mentioned in the singular form in the appended claims do not exclude the presence of a plurality of such elements.

Claims

A display for emitting light representing a given image;

A first polarizer disposed in front of the display and polarizing the light in a first linearly polarized state;

A first retarder disposed in front of the first polarizing plate and changing the first linearly polarized state of the light to a first circularly polarized state:

A first optical element transmitting the light of the first circularly polarized state incident after passing through the first retarder;

A second retarder, disposed in front of the first optical element, for changing the first circularly polarized state of the light to a second linearly polarized state; And

A second optical element for reflecting the light incident in the second linear polarization state to the first optical element through the second retarder, thereby changing the second linear polarization state of the light to a second circular polarization state; Including,

The first optical element,

And the light of the second circularly polarized state is reflected back to the second optical element through the second retarder, thereby changing the second circularly polarized state to the first linearly polarized state.
The method of claim 1,

The second optical element,

And an image device for transmitting the light of the first linearly polarized state to an eye of a user.
The method of claim 1,

The first optical element,

Including a cholesteric liquid crystal layer,

An image in which light in a first circularly polarized state is transmitted through the first optical element or the light in the second circularly polarized state is changed to the first linearly polarized state due to the alignment of liquid crystal molecules in the cholesteric liquid crystal layer. Device.
The method of claim 3, wherein

The first optical element comprises at least one of a lens and an optical film,

And the cholesteric liquid crystal layer is disposed on the surface of the lens or optical film or is embedded in the lens or optical film.
The method of claim 4, wherein

The lens or optical film,

An imaging device formed from an optically transparent material selected from one of optical glass, optical crystals and polymers.
The method of claim 1,

The second optical element,

An imaging device comprising a second polarizer.
The method of claim 6,

The second polarizing plate,

Imaging device that is a wire grid polarizer.
The method of claim 7, wherein

And the wire grid polarizer is formed of a parallel metal wire layer formed on a surface of the second optical element.
The method of claim 1,

At least one of the first delayer and the second delayer,

An imaging device that is a λ / 4 delay.
The method of claim 1,

The first retarder comprises a switchable λ / 4 retarder consisting of a liquid crystal layer sandwiched between two electrical contact layers,

The imaging device operates in a first mode and a second mode that are different modes.
The method of claim 10,

In the first mode,

The transparent display is turned on and emits the light, and the liquid crystal molecules of the liquid crystal layer in the switchable [lambda] / 4 retarder are oriented to change the light of the first linearly polarized state into a first circularly polarized state. ,

In the second mode,

The transparent display is turned off and the liquid crystal molecules in the switchable [lambda] / 4 retarder are oriented such that ambient light passing through the transparent display is transmitted to the eye of the user without reflection.
The method of claim 10,

The image device,

And switch to the first mode in response to a predetermined voltage applied between the electrical contact layers and to switch to the second mode when no voltage is applied between the electrical contact layers.
The method of claim 10,

The image device,

And an imaging device that switches to the first mode and the second mode at a switching frequency of 120 Hz or more.
The method of claim 1,

The display,

An imaging device comprising at least one of a liquid crystal display (LCD), a display based on a light emitting diode (LED), a display based on an organic LED (OLED), and a display based on a laser diode.
The method of claim 1,

The first polarizing plate is

An imaging device that is a thin film polarizer.