Lcos display device having significantly improved contrast ratio

Abstract

Disclosed is an LCoS display device having a significantly improved contrast ratio. Provided, according to one aspect of an embodiment of the present invention, is an LCoS display device comprising: a light source emitting light to be outputted to the outside of the device; a polarizing beam splitter reflecting light of a first polarization direction and transmitting light of a second polarization direction; a polarizer disposed on an optical path between the light source and the polarizing beam splitter and adjusting a polarization direction of light incident thereon to the first polarization direction; a transmittance adjustment unit disposed on the optical path between the polarizer and the polarizing beam splitter, and adjusting the transmittance for each region within a frame; an LCoS adjusting a polarization state of light incident thereon for each pixel according to an image or a video to be outputted; and a driving circuit controlling operations of the light source, the transmittance adjustment unit, and the LCoS.

Description

LCOS display device with significantly improved contrast ratio

[0001] The present embodiment relates to an LCoS display device with significantly improved contrast ratio.

[0002]

[0003] This patent is the result of research conducted with the support of the Korea Institute of Industrial Technology Planning and Evaluation with funding from the government of the Republic of Korea (Ministry of Trade, Industry and Energy) (Detailed Project Number: 20026453, Project Name: Development of Materials and Components Technology, Project Name: Development of 10000 PPI LCoS Panel Technology Supporting 480 Frame Rate for Ultra-small XR Glasses).

[0004] The content described in this section merely provides background information for the present embodiment and does not constitute prior art.

[0005] LCoS (Liquid Crystal on Silicon) is an ultra-small display device used in augmented reality devices. It shares both structural similarities and differences with conventional LCDs. The similarity lies in the fact that it contains liquid crystals between two substrates, with an alignment layer on the surface of the substrates to align the liquid crystals. Furthermore, both devices include a pixel electrode that applies an electric field to control the liquid crystal alignment for each pixel, and a driving circuit that includes multiple TFT elements connected to the pixel electrode.

[0006] LCoS differs from conventional LCDs in the following ways: Because its backplane uses a silicon wafer, it can only be used as a reflective display, not a transmissive one. LCoS displays have very small pixels. Furthermore, a significant portion of LCoS's TFT circuitry, wiring, and display driving circuitry are embedded within or beneath the silicon wafer. LCoS displays are also very small, typically less than 1 inch diagonal.

[0007] Although LCoS is highly regarded for its various image quality characteristics, it has a relatively significantly lower contrast ratio compared to other display elements. The contrast ratio refers to the ratio of the luminance when the display element is in the (darkest) state (dark state or black state) to the luminance when it is in the (brightest) state (bright state or white state). LCoS includes an element that selectively reflects polarized light, thereby controlling the amount of light output with a specific polarization state. For example, assuming that the element reflects linearly polarized S waves and transmits linearly polarized P waves, if the S waves are output (reflected) according to the arrangement of liquid crystals in LCoS, the S waves are reflected from the element and not output to the outside. Conversely, if the P waves are output (reflected), the P waves pass through the element and are output to the outside. However, since the liquid crystals in LCoS have residual birefringence, some of the polarization component of the P waves remains in a situation where the S waves are reflected. Accordingly, the residual P-wave component passes through the element and leaks out unintentionally. This structurally hinders conventional LCoS from achieving a superior contrast ratio.

[0008] One embodiment of the present invention aims to provide an LCoS panel and a method for manufacturing the same that can maintain the quality of an image or video to be output while aligning liquid crystals at a preset angle in advance.

[0009] One embodiment of the present invention aims to provide an LCoS panel and a method for manufacturing the same, which structurally significantly reduces the possibility of occurrence of a short circuit.

[0010] In addition, one embodiment of the present invention aims to provide an LCoS display device with a significantly improved contrast ratio structurally.

[0011] According to one aspect of the present embodiment, an LCoS display device is provided, comprising: a light source for irradiating light to be output to the outside of the device; a polarizing beam splitter for reflecting light of a first polarization direction while transmitting light of a second polarization direction; a polarizer arranged between the light source and the polarizing beam splitter on an optical path to adjust the polarization direction of light incident thereon to the first polarization direction; a transmittance control unit arranged between the polarizer and the polarizing beam splitter on an optical path to adjust the transmittance of each area within a frame; an LCoS panel for adjusting the polarization state of light incident thereon for each pixel according to an image or video to be output; and a driving circuit for controlling the operation of the light source, the transmittance control unit, and the LCoS panel.

[0012] According to one aspect of the present embodiment, the polarizing beam splitter is characterized by having a reflective surface facing the light source and the LCoS panel.

[0013] According to one aspect of the present embodiment, the polarizing beam splitter is characterized in that it reflects light of a first polarization direction that is irradiated from the light source and passes through the polarizer, and reflects or transmits the light reflected after being incident on the LCoS panel to the outside according to the state of polarization.

[0014] According to one aspect of the present embodiment, the transmittance control unit is characterized by being an LCD.

[0015] According to one aspect of the present embodiment, the transmittance control unit is characterized in that it is divided into m*n regions.

[0016] According to one aspect of the present embodiment, m and n are characterized in that they are less than 10.

[0017] According to one aspect of the present embodiment, the transmittance at the boundary of each region within the transmittance control unit is characterized by changing in a gradient manner.

[0018] According to one aspect of the present embodiment, the LCoS panel is characterized in that, for each pixel, the proportion of light in the first polarization direction is adjusted so that a portion that should be relatively bright within an image or video to be output has a relatively high proportion of light incident on the panel.

[0019] According to one aspect of the present embodiment, the LCoS panel is characterized in that, for each pixel, the proportion of light in the second polarization direction is adjusted so that a portion that should be relatively dark within an image or video to be output has a relatively high proportion of light incident on the panel.

[0020] According to one aspect of the present embodiment, the driving circuit is characterized in that it controls the ratio of the polarization state of light to be reflected from the LCoS panel for each pixel of the LCoS panel, and adjusts the transmittance of each area of ​​the transmittance control unit in conjunction therewith.

[0021] As described above, according to one aspect of the present embodiment, there is an advantage in that the quality of an image or video to be output can be maintained while aligning the liquid crystal at a preset angle in advance.

[0022] According to one aspect of this embodiment, there is an advantage in that the possibility of occurrence of a short circuit is structurally significantly reduced.

[0023] In addition, according to one aspect of the present embodiment, there is an advantage in that it can have a significantly superior contrast ratio compared to conventional LCoS structurally.

[0024] FIG. 1 is a diagram illustrating the configuration of an LCoS display device according to one embodiment of the present invention.

[0025] FIG. 2 is a diagram illustrating signals transmitted when an LCoS display device according to one embodiment of the present invention operates.

[0026] FIG. 3 is a drawing illustrating the configuration of a transmittance control unit according to one embodiment of the present invention.

[0027] FIG. 4 is a diagram illustrating a gamma curve for controlling a transmittance control unit and a light source of an LCoS display device according to one embodiment of the present invention.

[0028] FIGS. 5 and 6 are diagrams illustrating examples of images output from an LCoS display device according to one embodiment of the present invention.

[0029] FIG. 7 is a plan view of an LCoS panel according to one embodiment of the present invention.

[0030] FIG. 8 is a cross-sectional view of an LCoS panel according to one embodiment of the present invention.

[0031] Figures 9 to 18 are drawings illustrating a process for manufacturing an LCoS panel according to one embodiment of the present invention.

[0032] FIG. 19 is a flowchart illustrating a method for manufacturing an LCoS panel according to one embodiment of the present invention.

[0033] FIG. 20 is a flowchart illustrating a method for aligning liquid crystals in an LCoS panel at a preset angle according to one embodiment of the present invention.

[0034] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0035] Terms such as first, second, A, and B may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0036] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0037] The terminology used in this application is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. It should be understood that terms such as "comprise" or "have" in this application do not preclude the presence or possibility of addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification.

[0038] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0039] Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0040] In addition, each configuration, process, procedure or method included in each embodiment of the present invention may be shared within a scope that is not technically inconsistent with each other.

[0041] FIG. 1 is a diagram illustrating the configuration of an LCoS display device according to one embodiment of the present invention.

[0042] Referring to FIG. 1, an LCoS display device (100) according to one embodiment of the present invention includes a driving circuit (110), a light source (120), a polarizer (130, 135), a transmittance control unit (140), a polarizing beam splitter (150), and an LCoS panel (160).

[0043] The LCoS display device (100) includes an LCoS panel (160) to output an image or video, and includes a transmittance control unit (140) to solve the problem of low contrast ratio, which is a problem of the LCoS display device.

[0044] The driving circuit (110) controls the operations of the light source (120), the transmittance control unit (140), and the LCoS panel (160), which will be described later. The driving circuit (110) controls each component (120, 140, 160) as illustrated in FIG. 2.

[0045] FIG. 2 is a diagram illustrating signals transmitted when an LCoS display device according to one embodiment of the present invention operates.

[0046] Referring to Fig. 2(a), the driving circuit (110) controls each light source (120) to emit light sequentially.

[0047] At this time, referring to FIGS. 2(b) and (c), the driving circuit (110) sequentially receives image or video data to be output from the outside by sub-frame. After receiving data corresponding to one sub-frame, the driving circuit (110) controls the operation of the LCoS panel (160). The driving circuit (110) transmits the brightness (gray level) of the signal to be output through the LCoS panel (160) for each pixel, but rather than driving (outputting light) each line individually, the driving circuit transmits the brightness of the signal to all lines and then drives each frame. That is, rather than driving each line like an LCD, the driving circuit (110) transmits the brightness of the signal to all lines of the LCoS panel (160) and then drives so that one entire frame is output. The signal output and displayed to the pixel is maintained until the next frame signal is output.

[0048] Referring to Fig. 2(d), the driving circuit (110) controls the operation of the transmittance control unit (140). The driving circuit (110) controls the transmittance control unit (140) so that all areas operate appropriately in unison, rather than sequentially controlling each pixel or line as in controlling each light source (120).

[0049] In this way, the driving circuit (110) controls the light source (120) and the LCoS panel (160) to control the image or video to be output, and individually controls the transmittance of each area within the transmittance control unit (140) for each frame. Based on this, the driving circuit (110) improves the contrast ratio of the image or video to be output. This will be described later with reference to FIGS. 4 to 6.

[0050] Referring again to FIG. 1, the light source (120) irradiates light to be output to the outside of the device (100) through a polarizer (130, 135), a transmittance control unit (140), a polarizing beam splitter (150), and an LCoS panel (160).

[0051] Polarizers (130, 135) are placed at both ends of the transmittance control unit (140) to adjust the polarization direction of light incident on them.

[0052] The polarizer (130) is placed between the light source (120) and the transmittance control unit (140) on the optical path, and transmits only the light of the second polarization direction perpendicular to the first polarization direction reflected from the polarizing beam splitter (150) among the light incident on it.

[0053] The polarizer (135) is placed between the transmittance control unit (140) and the polarizing beam splitter (150) on the optical path, and transmits only the light of the first polarization direction reflected from the polarizing beam splitter (150) among the light incident on it.

[0054] The transmittance control unit (140) adjusts the transmittance for each region within the frame by adjusting the polarization direction of the light incident on it. The transmittance control unit (140) adjusts the transmittance for each region within the frame in this way to adjust the brightness. The transmittance control unit (140) is implemented as illustrated in FIG. 3.

[0055] FIG. 3 is a drawing illustrating the configuration of a transmittance control unit according to one embodiment of the present invention.

[0056] Referring to FIG. 3, the transmittance control unit (140) is implemented as a configuration for controlling the transmittance, and can be implemented as, for example, an LCD. When implemented as an LCD, the transmittance control unit (140) can divide a plurality of regions (310) and control the transmittance for each region. The transmittance control unit (140) can control the polarization direction of light incident on it to control the amount of light passing through the polarizer (135). The transmittance control unit (140) adjusts the polarization direction according to the control of the driving circuit (110), thereby controlling the transmittance for each region according to the video or image to be output. The transmittance control unit (140) does not control the transmittance for each region line by line, but individually controls each region, and, like the LCoS panel (160), controls all regions collectively for each frame.

[0057] The transmittance control unit (140) can be divided into m*n regions (310), and each (m, n) may preferably be smaller than 10. According to the control of the driving circuit (110), the transmittance at the boundary of each region changes in a gradient manner, thereby preventing the brightness of an image or video to be output from being noticeably different from region to region.

[0058] Referring back to FIG. 1, the polarizing beam splitter (150) reflects light in the first polarization direction, but transmits light in the second polarization direction. The polarizing beam splitter (150) has a reflective surface facing the light source (120) and the LCoS panel (160), so that the light in the first polarization direction that is irradiated from the light source (120) and ultimately passes through the polarizer (135) is reflected to the LCoS panel (160), and the light reflected after entering the LCoS panel (160) is reflected or transmitted depending on the polarization state.

[0059] The LCoS panel (160) is controlled by the driving circuit (110) and adjusts the polarization state of the light incident on each pixel according to the image or video to be output. The LCoS panel (160) adjusts the light incident on each pixel so that a portion of the image or video to be output that should be relatively bright has a relatively high proportion of light in the first polarization direction, and a portion of the image or video to be output that should be relatively dark has a relatively high proportion of light in the second polarization direction. Accordingly, the light reflected after being input to the LCoS panel (160) is output as light in the first polarization direction with an appropriate proportion for each pixel. The light in the first polarization direction is output to the outside (viewer) by transmitting through the polarizing beam splitter (150), and the light in the second polarization direction is reflected from the polarizing beam splitter (150) and is not output. The LCoS panel (160) can adjust the gamma of an image or video to be output by adjusting the proportion of light in the first polarization direction for each pixel according to the control of the driving circuit (110).

[0060] At this time, the device (100) includes a transmittance control unit (140) and can improve the contrast ratio as illustrated in FIGS. 5 and 6 by controlling it as illustrated in FIG. 4.

[0061] FIG. 4 is a drawing showing a gamma curve for controlling a transmittance control unit and a light source of an LCoS display device according to an embodiment of the present invention, and FIGS. 5 and 6 are drawings showing examples of images output from an LCoS display device according to an embodiment of the present invention.

[0062] In order to output an image or video to be output, the driving circuit (110) controls the ratio of the polarization state of light to be reflected from the LCoS panel (160) for each pixel of the LCoS panel (160). Meanwhile, the driving circuit (110) adjusts the transmittance for each area of ​​the transmittance control unit (140) in conjunction therewith.

[0063] Referring to Fig. 4a, when the transmittance is 100%, the pixel value (Gray Level) can be the largest 256, and at this time, the brightest light is output. At this time, for example, in order to output light with a pixel value of 192 from the pixel, the pixel value itself can be reduced to 192 and output. However, in this case, in order to output light with a low pixel value, the pixel value itself is reduced by the corresponding value and output. At this time, the problem of unintentionally including light in the second polarization direction cannot be prevented, and thus the problem of a low contrast ratio has occurred.

[0064] Accordingly, the driving circuit (110) can control each configuration as follows. The pixel value of 192 in the corresponding pixel corresponds to the pixel value when the transmittance is 50% based on the maximum transmittance (100%). Accordingly, the driving circuit (110) can control the transmittance control unit (140) to reduce the transmittance to 50% instead of reducing and outputting the pixel value itself in the corresponding pixel, and can control the light source (120) and the LCoS panel (160) to output light in the first polarization direction with the maximum pixel value. Accordingly, the device (100) can output light having a specific pixel value while preventing the problem of unintentionally including light in the second polarization direction.

[0065] The driving circuit (110) can adjust the transmittance for each area of ​​the transmittance control unit (140) and output as shown in FIGS. 5 and 6.

[0066] As shown in Figure 5a, if the final output image is the Earth, the central Earth should have a constant pixel value, while areas other than the Earth should have very dark pixel values. However, as previously mentioned, conventional LCoS has a significantly low contrast ratio due to unintentionally residual polarization components.

[0067] On the other hand, the transmittance control unit (140) divides into a plurality of regions (310) as illustrated in FIG. 5b, and the driving circuit (110) can control the transmittance of each region of the transmittance control unit (140). The driving circuit (110) adjusts the region (within the transmittance control unit (140)) corresponding to the part where the Earth should be placed to have an appropriate transmittance, while adjusting the region (within the transmittance control unit (140)) corresponding to a part other than the Earth to have the lowest transmittance. Since the region within the transmittance control unit (140) has the lowest transmittance, even if light is output with the brightest pixel value from the light source (120) as illustrated in FIG. 4b, the effect of outputting the same light as that with the lowest pixel value can be achieved.

[0068] Accordingly, as illustrated in FIG. 5c, an image or video output through the device (100) can be output to be considerably dark in areas that should be dark, thereby having an excellent contrast ratio.

[0069] This is also the case in Fig. 6. Regardless of which image or video is output, the driving circuit (110) can secure an excellent contrast ratio by adjusting the transmittance of each area within the transmittance control unit (140) to correspond to the pixel value of the image or video to be output.

[0070] FIG. 7 is a plan view of an LCoS panel according to an embodiment of the present invention, and FIG. 8 is a cross-sectional view of an LCoS panel according to an embodiment of the present invention.

[0071] Referring to FIGS. 7 and 8, an LCoS panel (160) according to one embodiment of the present invention includes a lower substrate (710), an alignment film (715, 724), an upper substrate (720), a transparent electrode (728), a liquid crystal (730), a seal line (740), and a sealant (750).

[0072] The lower substrate (710) supports other components within the LCoS panel (160). The lower substrate (710) may be implemented as a silicon substrate and may be implemented in a wafer form. Accordingly, the lower substrate (710) can receive power from an external source to generate an electric field, and reflect incident light, thereby allowing the LCoS panel (160) to operate as a reflective display.

[0073] The lower substrate (710) may be connected to an external driving circuit (not shown) or may include a driving circuit (not shown) internally. The lower substrate (710) may control whether an electric field is generated in the transparent electrode (not shown) and the intensity of the electric field to be generated, depending on the control of the driving circuit (not shown). The lower substrate (710) may be equipped with a TFT circuit and wiring, etc. to control the operation of the LCoS panel (160), on a surface of the lower substrate (710) that is internal or far from the upper substrate (720).

[0074] The alignment film (715) is disposed on one surface of the lower substrate (710) facing the upper substrate (720). In particular, the alignment film (715) is disposed (on the aforementioned surface of the lower substrate (710)) within a space formed by the lower substrate (710), the upper substrate (720), and the seal line (740), into which the liquid crystal (730) is to be injected. The alignment film (715) is disposed at the aforementioned position and is formed so as not to extend beyond the seal line (740). When an electric field is formed by a driving circuit (not shown), even if the arrangement direction of the liquid crystal (730) changes in a direction different from the initial arrangement direction due to the electric field, the alignment film (715) maintains the liquid crystal (730) adjacent to the alignment film in the initial arrangement direction. The alignment film (715) is implemented as a main chain and a plurality of side chains protruding outward from the main chain. The alignment film (715) can be implemented with polyimide or polyimide acid. Accordingly, the side chain can control the alignment of the liquid crystal (730) depending on the protruding direction.

[0075] The upper substrate (720) is mounted on the lower substrate (710) and, together with the lower substrate (710) and the seal line (740), forms a space into which liquid crystal (730) is injected. The upper substrate (720) is made of glass, thereby allowing light incident from the outside to pass through.

[0076] The transparent electrode (728) is formed on one side of the upper substrate (720) facing the lower substrate (710), and similarly generates an electric field. The transparent electrode (728) is arranged, receives power from the outside, generates an electric field, and aligns the liquid crystal (730). Similarly to the lower substrate (710), the upper substrate (720) has a seal line (740) printed or drawn so that it is biased toward one end, and the liquid crystal (730) is injected into the space formed by the seal line (740). Accordingly, a sufficient space is formed on the other end of the corresponding surface of the upper substrate (720) to apply power from the outside to the transparent electrode (728). The transparent electrode (728) formed on the other end of the upper substrate (720) receives power from the outside and generates an electric field.

[0077] The transparent electrode (728) can structurally minimize short circuits by being patterned into a structure described later with reference to FIG. 10. The transparent electrode (728) can structurally prevent the occurrence of short circuits that frequently occur between the substrate and the transparent electrode or between each unit cell arranged on the transparent electrode through patterning.

[0078] The alignment film (724) is disposed on the transparent electrode (728) of the upper substrate (720). In particular, similar to the alignment film (715), the alignment film (724) is also disposed (on the aforementioned surface of the lower substrate (710)) within the space formed by the lower substrate (710), the upper substrate (720), and the seal line (740) into which the liquid crystal (730) is to be injected, and performs the same operation. The alignment film (724) is also implemented as a main chain and a side chain, and can control the alignment of the liquid crystal (730).

[0079] The upper substrate (720) may be implemented with a material having a thermal expansion coefficient within a preset error range, similar to the lower substrate (710), which may be implemented with a silicon wafer. For example, when the lower substrate (710) is implemented with a silicon wafer, the upper substrate (720) may be implemented with borosilicate glass, etc., whose thermal expansion coefficient is within a preset error range. As described below, the seal line (740) is implemented with a polymer sealant having thermosetting characteristics. Accordingly, it is essential that each substrate (710, 720) be exposed to at least a temperature at which the seal line (740) must be cured. At this time, if the thermal expansion coefficients of the two are different, a problem may arise in which the two warp to different degrees during the aforementioned heat process. If the two materials bend to different degrees due to differences in their coefficients of thermal expansion (by a margin of error), this complicates the manufacturing process of LCoS and reduces the reliability of accommodating (sealing) the liquid crystal (730). To prevent this problem, the upper substrate (720) is made of the aforementioned material, thereby preventing the aforementioned problem.

[0080] Meanwhile, an anti-reflection coating (not shown) may be applied to the surface opposite to the surface on which the alignment film (724) and transparent electrode (728) of the upper substrate (720) are formed. As the anti-reflection coating (not shown) is applied to the corresponding surface of the upper substrate (720), light incident from the outside or reflected after being incident can be prevented from being reflected on the surface of the upper substrate (720).

[0081] The liquid crystal (730) changes its orientation when an electric field is applied from the outside. By changing its orientation, the liquid crystal (730) controls the amount of light that passes through it. The liquid crystal (730) goes through a process described below with reference to FIGS. 16 to 18 and has a state in which it is oriented at a preset angle. Here, the preset angle may be 80 to 88°, and more preferably 84 to 86°. In this way, since the liquid crystal (730) has a state in which it is oriented at a preset angle in advance, when an electric field is applied from the outside, all the liquid crystals (730) can be oriented in a uniform direction and can be oriented at a desired angle more quickly. In addition, since the liquid crystal (730) goes through a process described below with reference to FIGS. 16 to 18 and has a state in which it is oriented at a preset angle in advance, it is possible to resolve the problem of including (unwanted) patterns due to rubbing in the final output video or image, as in the prior art.

[0082] When the liquid crystal (730) is injected, a photoreactive liquid crystal (735, RM: Reactive Mesogen, described later with reference to FIG. 16) is injected together with the liquid crystal (730) in a preset amount. The photoreactive liquid crystal (735) may be included in an amount of about 0.1 to 3% relative to the amount of the liquid crystal (730) injected. The photoreactive liquid crystal (735) is polymerized when irradiated with light from the outside, particularly, light in the ultraviolet wavelength range. When the photoreactive liquid crystal (735) is polymerized when irradiated with light from the outside, the angle of the liquid crystal (730) can be physically fixed. As described above, the orientation of the liquid crystal (730) changes only when an electric field is applied from the outside. At this time, the photoreactive liquid crystal (735) is polymerized, and the angle of the liquid crystal (730) can be physically / structurally fixed. Accordingly, the liquid crystal (730) can maintain a state of being aligned at a pre-set angle even if the electric field is stopped from outside.

[0083] The seal line (740) is printed or drawn between each substrate (710, 720) to form a space (744) for accommodating the liquid crystal (730) together with each substrate (710, 720). The seal line (740) may be implemented with a polymer sealant having thermosetting characteristics and may be printed or drawn between each substrate (710, 720). The seal line (740) may also be implemented with a polymer sealant having photocurable characteristics, but photocurable polymer sealants have relatively weak adhesive strength and may be unstable in accommodating the liquid crystal (730). Therefore, the seal line (740) is implemented with a polymer sealant having thermosetting characteristics.

[0084] The seal line (740) has a preset shape, for example, a square shape, and forms a receiving space inside. The seal line (740) includes an injection port (748) at one portion, so that liquid crystal (730) can be injected into the receiving space (744) from the outside.

[0085] The sealing material (750) seals the injection port (748) of the seal line (740) to prevent the liquid crystal (730) from being discharged from the receiving space (744). The sealing material (750) is partially injected into the receiving space (744) formed by the seal line (740), particularly, the injection port (748), and is cured, thereby sealing the injection port (748). The sealing material (750) seals the injection port (748) of the seal line (740) and prevents the liquid crystal (730) from being discharged to the outside from the receiving space (744).

[0086] LCoS (160) can have the above-described configuration and characteristics by being manufactured according to the process described below.

[0087] Figures 9 to 18 are drawings illustrating a process for manufacturing an LCoS panel according to one embodiment of the present invention.

[0088] Referring to FIG. 9, a first cut is performed at each interval between LCoS unit cells (920) to be formed on a silicon substrate (710). As described above, the silicon substrate (710) may be implemented in a wafer form. The first cut is performed at each interval between LCoS unit cells (920) on the silicon substrate (710), particularly on the surface facing the glass substrate (420) to be mounted according to the process described below.

[0089] The first cutting into the silicon substrate (710) is performed only to the following extent. The width of the first cutting is performed to be 50㎛ or less, and the depth can be performed only to 10 to 60% of the thickness of the silicon substrate (710).

[0090] If the width of the first cut is longer than the aforementioned length, the probability of scratch defects occurring on the back surface of the silicon substrate (710) (the side opposite to the side where the first cut was performed) during the rubbing process of the alignment film (715) described later increases significantly. Therefore, the width of the first cut is limited to 50 μm or less.

[0091] In addition, the depth of the first cutting is only 10 to 60%. In particular, when cutting the silicon substrate (710) by the process (scribing process) illustrated in FIG. 14 as described below, the depth of the first cutting can only be 10 to 30% of the thickness of the silicon substrate (710). If the silicon substrate (710) is first cut below the aforementioned level, there is a possibility that the silicon substrate (710) may not be cut smoothly when cut at unit cell intervals through the process illustrated in FIG. 14. Conversely, if the silicon substrate (710) is first cut above the aforementioned level, a situation in which the silicon substrate (710) is separated before the cutting process may occur.

[0092] Referring to Fig. 10a, an alignment film (715) is coated on one side of a first cut silicon substrate (710).

[0093] Referring to FIG. 10b, a transparent electrode (728) is deposited on one surface of the upper substrate (720).

[0094] Referring to FIG. 10c, patterning is performed on the deposited transparent electrode (728). The transparent electrode (728) is patterned so that the unit cells adjacent to each other in the vertical direction are separated and the upper substrate (720) is exposed, and the transparent electrode (728) is patterned so that the transparent electrode (728) remains in some areas in the form of a bridge (1010) and is connected between the unit cells adjacent to each other in the left and right directions. Accordingly, the transparent electrode (728) is patterned, and each unit cell and the unit cells adjacent to each other in the left and right directions remain in the form of a bridge, but the adjacent unit cells in the vertical direction are separated. The transparent electrode (728) is patterned in this manner, and a short circuit that may occur between the substrate and the transparent electrode or between each unit cell arranged on the transparent electrode can be minimized.

[0095] Referring to FIG. 10d, an alignment film (724) is coated on the patterned transparent electrode (728). The alignment film (724) may be coated on the upper substrate (720) at intervals between LCoS unit cells (920) to be formed.

[0096] Referring to FIGS. 11A and 11B, rubbing is performed on each alignment film (715, 724) coated on the silicon substrate (710) and the upper substrate (720). The rubbing may be performed such that each alignment film (715, 724), particularly, side chains within the alignment film, are inclined in one direction. As this rubbing is performed on each alignment film (715, 724), the liquid crystal may be oriented in a pre-set direction (e.g., in the direction of φ = 45 degrees and θ = 84 to 86 degrees based on the spherical coordinate system).

[0097] In addition, the depth of the rubbing performed on each alignment film (715, 724) may be 0.08 to 0.15 mm. Conventionally, rubbing has been performed on the alignment film to a depth of 0.2 mm or more. As a result, a problem has occurred in which (unwanted) patterns due to the rubbing are included in the image or video output from the LCoS. On the other hand, since the rubbing is performed on each alignment film (715, 724) to a depth of 0.08 to 0.15 mm, patterns due to the rubbing may not be included in the image output from the LCoS panel (160).

[0098] The depth of the love can be calculated as follows:

[0099]

[0100] Here, l represents the depth of rubbing, R represents the radius of the rubbing roll for performing the rubbing, and W represents the width of the rubbing marks created on the alignment film by rotating the rubbing roll while fixing the substrate. As the rubbing on each alignment film (715, 724) progresses to the depth described above according to the formula described above, a pattern caused by the rubbing may not be included in the image output from the LCoS panel (160).

[0101] Rubbing proceeds in the same direction while each alignment film (715, 724) is positioned facing the same direction within each substrate (710, 720). Accordingly, when the two substrates (710, 720) are bonded according to the process described below, each alignment film (715, 724) is rubbed in opposite directions, and the liquid crystals are uniformly aligned in a pre-set direction.

[0102] Referring to FIGS. 12a and 12b, a seal line (740) is printed or drawn at each LCoS unit cell interval on one surface (coated with an alignment film) of a glass substrate (720) to form an accommodation space within the LCoS unit cell. The seal line (740) is printed or drawn on a transparent electrode (728), and is printed or drawn at each LCoS unit cell interval in an area where the alignment film (724) is not coated. However, the present invention is not limited thereto, and the seal line (740) may also be printed or drawn on a silicon substrate (710).

[0103] Referring to Fig. 13, a silicon substrate (710) is bonded onto a seal line (740). At this time, the silicon substrate (710) is bonded so that the alignment film (715) faces the glass substrate (720) or the seal line (740). After the silicon substrate (710) is bonded, the seal line (740) is heat-cured.

[0104] Referring to FIG. 14, cutting is performed at intervals between LCoS unit cells on the silicon substrate (710) and the upper substrate (720), respectively. The upper substrate (720) is scribed at intervals between LCoS unit cells. Meanwhile, the silicon substrate (710) is scribed at intervals between LCoS unit cells on the opposite side of the first cut surface. Since the silicon substrate (710) is in a state of being first cut, cutting can be performed in a relatively straight shape, and the possibility of damage to the upper substrate (720) occurring during the cutting (scribing) process is also significantly reduced. If the silicon substrate is completely scribed without first cutting, there is a high possibility of damage to the upper substrate (720) occurring during the scribing process. However, since the silicon substrate (710) is first cut, the above-mentioned problem can be prevented.

[0105] Referring to FIGS. 15a and 15b, a liquid crystal (730) is injected into the injection port (748) of each cut LCoS unit cell. As described above, a preset amount of a photoreactive liquid crystal (735) is injected together with the liquid crystal (730). After the liquid crystal (730) is injected, the injection port (748) is sealed by a sealant (750).

[0106] Referring to Fig. 16, when the alignment film (715, 724) is present, the liquid crystal (730) and the photo-reactive liquid crystal (735) are naturally aligned in the vertical direction. Thereafter, voltage is applied to the transparent electrode (728) and the silicon substrate (710) to adjust the alignment direction of the liquid crystal (730) and the photo-reactive liquid crystal (735). When voltage is applied to both components (710, 728), an electric field is generated.

[0107] At this time, an AC voltage can be applied to both components (710, 728). If a DC voltage is applied to both components (710, 728), an imbalance in the ion concentration in the liquid crystal may occur, causing afterimages or uneven brightness. Conventionally, a DC voltage has been used to orient the liquid crystal due to its structural characteristics, but since the silicon substrate (710) and the transparent electrode (728) can be used to generate an electric field, an AC voltage is applied to generate an electric field.

[0108] Referring to FIGS. 17 and 18, a voltage is applied to the two components (710, 728), an electric field is generated, and accordingly, the angles of the liquid crystal and the photoreactive liquid crystal (735) (e.g., the direction of the other of φ and θ based on the spherical coordinate system) are adjusted. Through the above-described process, since rubbing has occurred on each alignment film (715, 724), the liquid crystal (730) and the photoreactive liquid crystal (735) are both aligned in the same direction. The liquid crystal (730) and the photoreactive liquid crystal (735) are aligned at a certain angle according to the distance or gap with the alignment film (715, 724) by the applied electric field.

[0109] While the liquid crystal (730) and the photo-reactive liquid crystal (735) are aligned by an electric field, light in the ultraviolet wavelength range is irradiated from the outside. The light in the ultraviolet wavelength range is irradiated, and the photo-reactive liquid crystal (735) is polymerized (1010). Here, the irradiated light (in the ultraviolet wavelength range) can be irradiated in a preset pattern. The preset pattern may be a pattern in which light with an intensity of several to several tens of J is repeatedly irradiated at preset intervals. Since the light in the ultraviolet wavelength range is repeatedly irradiated at regular intervals, additional time can be provided for the photo-reactive liquid crystal (735) to be polymerized and for the liquid crystal (730) to be oriented at a preset angle. Additionally, the irradiation with light in the ultraviolet wavelength range can continue even after the provision of the electric field (voltage application) is stopped. The light in the ultraviolet wavelength range can be continuously irradiated at a relatively lower intensity than when provided in the aforementioned process.

[0110] The photo-reactive liquid crystal (735) is polymerized, and structurally / physically maintains the liquid crystals (730) at a preset angle. After the photo-reactive liquid crystal (730) is polymerized (1010), the supply of the electric field is stopped. When the supply of the electric field is stopped, the liquid crystals (730) return to their original position (vertical direction). At this time, since the photo-reactive liquid crystal (730) is in a polymerized state (1010), the liquid crystals (730) can all be aligned at a preset angle by the photo-reactive liquid crystal (735). Through this process, the liquid crystal (730) can have a state in which it is aligned at a preset angle in a preset direction in advance. That is, the LCoS panel (160) can include the liquid crystal (730) in the above-described state without the need to form a micropattern on the electrode as in a conventional LCD. In addition, the LCoS panel (160) can prevent a pattern caused by rubbing from being included in the final output image or video, unlike conventional LCoS.

[0111] Meanwhile, although FIGS. 15 to 18 illustrate that the encapsulation of the injection port (748) and the polymerization of the photo-reactive liquid crystal are performed as separate processes, this is not necessarily limited. The processes of FIGS. 15 to 18 may be performed sequentially, but both processes may be performed simultaneously. The encapsulation of the encapsulant may also be performed by irradiation with light in the ultraviolet wavelength range, and the ultraviolet wavelength range light may be irradiated to the entire LCoS panel, and the encapsulation and polymerization may be performed simultaneously (in parallel). When both processes are performed simultaneously in this way, the following advantages may be obtained. If the encapsulation of the injection port (748) is performed first and the polymerization of the photo-reactive liquid crystal is performed later, the liquid crystal near the injection port (748) may be relatively excessively irradiated with light in the ultraviolet wavelength range during both processes. The liquid crystal may be relatively excessively irradiated with light in the ultraviolet wavelength range, and there is also a possibility that the liquid crystal may pretilt in an unintended direction (or angle). Accordingly, the bagging of the injection port (748) illustrated in FIG. 15 and the polymerization of the photo-reactive liquid crystal illustrated in FIGS. 16 to 18 can be performed simultaneously (once) while light in the ultraviolet wavelength band is irradiated across the entire LCoS panel, thereby preventing pretilt of the liquid crystal and simplifying the manufacturing process.

[0112] FIG. 19 is a flowchart illustrating a method for manufacturing an LCoS panel according to one embodiment of the present invention. The method for manufacturing an LCoS panel (160) illustrated in FIG. 19 can be performed by an LCoS panel manufacturing apparatus.

[0113] First cutting is performed at each interval between unit cells in the silicon substrate (710) (S1910).

[0114] An alignment film (715), a transparent electrode (728), and an alignment film (724) are printed on one surface of a silicon substrate (710) and an upper substrate (720) (S1920). At this time, the transparent electrode (728) is first deposited on the upper substrate (720), and the transparent electrode (728) is patterned so that the upper substrate (720) is exposed by separating the unit cells adjacent to each other in the vertical direction. Meanwhile, the transparent electrode (728) is patterned so that the transparent electrode (728) remains in some areas in the form of a bridge and is connected between the unit cells adjacent to each other in the left and right direction. Thereafter, the alignment film (724) is printed on the patterned transparent electrode (728).

[0115] Rubbing is performed at a preset depth on each alignment film of the silicon substrate (710) and the upper substrate (720) (S1930). Rubbing is performed in the same direction while each alignment film (715, 724) is positioned facing the same direction surface within each substrate (710, 720).

[0116] A seal line (740) is printed on the upper substrate (210) (S1940).

[0117] The silicon substrate (710) and the upper substrate (720) are bonded (S7350).

[0118] The silicon substrate (710) and the upper substrate (720) are cut at each LCoS unit cell interval (S1960).

[0119] Liquid crystal (730) is injected between the silicon substrate (710) and the upper substrate (720) (S1970).

[0120] The injection port (748) is sealed using a sealant (750) (S1980).

[0121] Voltage is applied to the transparent electrode (728) and the silicon substrate (710), and light is irradiated to the liquid crystal (730) (S1990). However, as mentioned above, the S1980 and S1990 processes can be performed simultaneously.

[0122] FIG. 20 is a flowchart illustrating a method for aligning liquid crystals in an LCoS panel at a preset angle according to one embodiment of the present invention.

[0123] An alternating voltage is applied to the transparent electrode (728) and the silicon substrate (710) (S2010).

[0124] Light in the ultraviolet wavelength range is irradiated to the liquid crystal (730) in a preset pattern (S2020). Accordingly, the photoreactive liquid crystal (735) is polymerized.

[0125] The application of the AC voltage is stopped (S2030). Since the photoreactive liquid crystal (735) is in a polymerized state, when the application of the AC voltage is stopped, the liquid crystal (730) is freed from the state of being aligned by the electric field and returns to its original state. However, since the photoreactive liquid crystal (735) is in a polymerized state according to the process described above, the liquid crystals (730) are aligned at a preset angle.

[0126] Although FIGS. 19 and 20 describe each process as being executed sequentially, this is merely an illustrative description of the technical idea of ​​one embodiment of the present invention. In other words, a person skilled in the art to which one embodiment of the present invention pertains may modify and apply various modifications and variations, such as changing the order described in each drawing and executing it without departing from the essential characteristics of one embodiment of the present invention, or executing one or more of each process in parallel. Therefore, FIGS. 19 and 20 are not limited to a chronological order.

[0127] Meanwhile, the processes illustrated in FIGS. 19 and 20 can be implemented as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all types of recording devices that store data that can be read by a computer system. That is, a computer-readable recording medium includes storage media such as magnetic storage media (e.g., ROM, floppy disks, hard disks, etc.) and optical reading media (e.g., CD-ROMs, DVDs, etc.). In addition, a computer-readable recording medium can be distributed across network-connected computer systems, so that the computer-readable codes can be stored and executed in a distributed manner.

[0128] The above description is merely an example of the technical idea of ​​the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of ​​the present embodiment, but rather to explain it, and the scope of the technical idea of ​​the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present embodiment.

[0129]

[0130] CROSS-REFERENCE TO RELATED APPLICATION

[0131] This patent application claims priority under 35 USC § 119(a) to Korean Patent Application No. 10-2024-0106021, filed in Korea on August 8, 2024, the entire contents of which are incorporated by reference herein. Furthermore, this patent application claims priority in countries other than the United States for the same reasons, the entire contents of which are incorporated by reference herein.

Claims

1. In the LCoS display device, A light source that emits light to be output outside the device; A polarizing beam splitter that reflects light of a first polarization direction and transmits light of a second polarization direction; A polarizer arranged between the light source and the polarizing beam splitter on the optical path, the polarization direction of light incident thereon being adjusted to a first polarization direction; A transmittance control unit arranged between the polarizer and the polarizing beam splitter on the optical path to control the transmittance of each area within the frame; An LCoS panel that adjusts the polarization state of light incident on each pixel according to the image or video to be output; and A driving circuit that controls the operation of the light source, the transmittance control unit, and the LCoS panel. An LCoS display device characterized by including a .

2. In paragraph 1, The above polarizing beam splitter, An LCoS display device characterized by having a reflective surface facing the light source and the LCoS panel.

3. In paragraph 2, The above polarizing beam splitter, An LCoS display device characterized in that light of a first polarization direction irradiated from the light source and passing through the polarizer is reflected, and the light reflected after entering the LCoS panel is reflected or transmitted to the outside according to the state of polarization.

4. In paragraph 1, The above transmittance control unit is, An LCoS display device characterized by being an LCD.

5. In paragraph 1, The above transmittance control unit is, An LCoS display device characterized by being divided into m*n areas.

6. In paragraph 5, The above m and n are, An LCoS display device characterized by having a pixel size less than 10.

7. In paragraph 1, The transmittance at the boundary of each area within the above transmittance control section is An LCoS display device characterized by gradient changes.

8. In paragraph 1, The above LCoS panel, An LCoS display device characterized in that, for each pixel, a portion that should be relatively bright within an image or video to be output is adjusted so that the proportion of light in the first polarization direction is relatively high.

9. In paragraph 1, The above LCoS panel, An LCoS display device characterized in that, for each pixel, a portion that should be relatively dark within an image or video to be output is adjusted so that the proportion of light in the second polarization direction is relatively high.

10. In paragraph 1, The above driving circuit, An LCoS display device characterized in that the ratio of the polarization state of light to be reflected from the LCoS panel is controlled for each pixel of the LCoS panel, and the transmittance of each area of ​​the transmittance control unit is adjusted in conjunction therewith.

Images