KR102657488B1 - Light modulator for mems display - Google Patents

Abstract

Electromechanical light modulators and backlights provide efficient, affordable, high-performance displays.

Description

Light modulator for MEMS display {LIGHT MODULATOR FOR MEMS DISPLAY}

Related US Patent Documents

U.S. Application No. 12/584,465, filed September 3, 2009, now U.S. Patent No. 7,995,261 B2; and U.S. Application No. 14/589,699, filed January 5, 2015. U.S. Application No. 14/589,634, filed Jan. 5, 2015 U.S. Application No. 14/589,434, filed Jan. 5, 2015 U.S. Application No. 14/589,551, filed Jan. 5, 2015 Related is U.S. Application No. 14/589,715, filed on May 5, which is hereby incorporated by reference.

The present invention relates generally to the field of displays. In particular, the invention relates to displays incorporating electromechanical picture elements.

Currently, liquid crystal displays occupy most of the flat panel display market.

It has been suggested that displays based on electromechanical light modulators are possible alternatives to LCDs. The present invention discloses an electromechanical light modulator and display that can compete with LCDs in terms of picture performance, light efficiency and cost.

What follows is a summary description of exemplary embodiments of the invention. This is provided as an introduction to assist those skilled in the art in understanding the detailed design discussion that follows to further disclose the invention and is in no way intended to limit the scope of the claims appended hereto.

This specification discloses several electromechanical light modulators. According to an exemplary embodiment of the invention, a modulator includes an optical shutter supported on a surface of a substrate by one or two electrostatic actuators and a plurality of supports attached to the shutter at first and second ends of the shutter. In operation, the actuator applies a force to the shutter. The shutter support limits movement of the shutter in the direction of the force and causes the shutter to move substantially laterally relative to the force. The shutter moves laterally between the first and second positions without physical contact with a stationary part or surface. Each electrostatic actuator includes two electrodes positioned substantially parallel and at a close distance from each other. In some embodiments, the shutter is conductive and serves as one of the actuator electrodes. In another design, the shutter includes a flange extending from an edge of the shutter at right angles, forming a fixed electrode and an electrostatic actuator. The fixed electrode can be positioned very close to the flange to form an efficient electrostatic actuator.

Because the shutter support is located between the shutter and the surface, the shutters within the display can be positioned very close to each other, allowing only space between them for movement of the shutter. In some modulators, the shutter is supported on the surface by a cantilever beam. The present invention discloses a cantilever beam and a method of manufacturing a shutter supported by a cantilever beam. The present invention includes a plurality of modulators each including a light absorption layer having a light transmission area, a backlight for reflecting light toward the light absorption layer, and a shutter positioned between the backlight and the light absorption layer, wherein the shutter is and a light-transmitting area and a light-reflecting surface facing the backlight to recycle light emitted from the backlight, wherein light coming from the backlight and striking the light-transmitting area of the shutter is generated when the shutter is in the first position. When the light is transmitted through the transmissive region of the light absorption layer, the light is transmitted through the light absorption layer when the shutter is in the second position, and is absorbed within the light absorption layer.

The present invention includes a substrate having a plurality of modulators each comprising a shutter having a light transmitting area, and a surface and a plurality of embedded light reflectors, the embedded light reflectors allowing light to travel from the surface of the substrate to the substrate. Another display is further disclosed, causing the light to exit and converge on the respective light transmitting area of the shutter.

The foregoing and other objects of the present invention are illustrated in the accompanying drawings and described in the detailed description that follows.

1A is a perspective view of a shutter assembly according to an exemplary embodiment of the present invention.
Figure 1B is a front view of the shutter assembly shown in Figure 1A.
FIG. 2A is a top view of an exemplary mold for manufacturing the shutter assembly shown in FIG. 1A.
FIG. 2B is a cross-sectional view taken along line segment 2B in FIG. 2A.
Figure 3A is a perspective view of a light modulator according to an exemplary embodiment of the present invention.
Figure 3b is a front view of the light modulator of Figure 3a.
Figure 3C is a front view of the light modulator of Figure 3A, showing the shutter positioned in a first position.
Figure 3D is a front view of the light modulator of Figure 3A, showing the shutter positioned in a second position.
Figure 4A is a perspective view of a light modulator according to an exemplary embodiment of the present invention.
Figure 4b is a front view of the light modulator of Figure 4a.
Figure 5A is a perspective view of a light modulator according to an exemplary embodiment of the present invention.
Figure 5b is a front view of the light modulator of Figure 5a.
Figure 6A is a perspective view of a light modulator according to an exemplary embodiment of the present invention.
Figure 6B is a side view of the light modulator of Figure 6A.
FIG. 6C is a perspective view showing a shutter support in the light modulator shown in FIG. 6A.
FIG. 6D is a top view of the light modulator shown in FIG. 6A.
Figure 6E is a top view of the light modulator of Figure 6A, showing the shutter positioned in a first position.
Figure 6F is a top view of the light modulator of Figure 6A, showing the shutter positioned in a second position.
Figure 7A is a top view of a light modulator according to an exemplary embodiment of the present invention.
Figure 7b is a side view of the light modulator of Figure 7a.
FIG. 7C is a top view showing a shutter support in the light modulator shown in FIG. 7A.
Figure 7D is a top view of the light modulator of Figure 7A, showing the shutter positioned in a first position.
Figure 8A is a perspective view of a shutter support according to an exemplary embodiment of the present invention.
FIG. 8B is a perspective view of a mold for manufacturing the shutter support shown in FIG. 8A.
FIG. 8C is a cross-sectional view taken along line CC in FIG. 8B illustrating the steps of manufacturing the shutter support shown in FIG. 8A.
FIG. 8D is a top view illustrating the steps of manufacturing the shutter support shown in FIG. 8A.
Figure 8E is a front view illustrating the steps of manufacturing the shutter support shown in Figure 8A.
Figure 8F is a front view illustrating the steps of manufacturing the shutter support shown in Figure 8A.
FIG. 8G is a top view illustrating the steps of manufacturing the shutter support shown in FIG. 8A.
Figure 8J is a side view illustrating the steps of manufacturing the shutter support shown in Figure 8A.
Figure 9A is a perspective view of a shutter according to an exemplary embodiment of the present invention.
FIG. 9B is a perspective view of a mold for manufacturing the shutter shown in FIG. 9A.
FIG. 9C is a cross-sectional view taken along line CC in FIG. 9B illustrating the steps of manufacturing the shutter shown in FIG. 9A.
FIG. 9D is a perspective view illustrating the steps of manufacturing the shutter shown in FIG. 9A.
Figure 9E is a cross-sectional view taken along line segment EE in Figure 9D, illustrating the steps of manufacturing the shutter shown in Figure 9A.
Figure 9f is a cross-sectional view taken along line segment FF in Figure 9d, illustrating the steps of manufacturing the shutter shown in Figure 9a.
Figure 10A is a perspective view of a display backlight according to an exemplary embodiment of the present invention.
Figure 10B is a side view of the display backlight of Figure 10A.
FIG. 10C is an enlarged view of the area indicated by 10C in FIG. 10B.
11A-11D are cross-sectional views illustrating steps for fabricating an optical layer with an embedded light reflector according to an exemplary embodiment of the present invention.
12A-12C are cross-sectional views illustrating steps for manufacturing a substrate with an embedded light reflector according to an exemplary embodiment of the present invention.
Figure 13A is a top view of a display cover assembly according to an exemplary embodiment of the present invention.
FIG. 13B is a cross-sectional view taken along line segment 13B in FIG. 13A.
FIG. 14A is a cross-sectional view of a display according to an exemplary embodiment of the present invention, illustrating a shutter positioned in a first position.
FIG. 14B is a cross-sectional view of the display shown in FIG. 14A illustrating the shutter positioned in a second position.
FIG. 15A is a cross-sectional view of a display according to an exemplary embodiment of the present invention, illustrating a shutter positioned in a first position.
FIG. 15B is a cross-sectional view of the display shown in FIG. 15A illustrating the shutter positioned in a second position.
Figure 16 is a front page view for reference.

FIG. 1A is a perspective view and FIG. 1B is a front view of a shutter assembly 100 according to an exemplary embodiment of the present invention. Shutter assembly 100 includes an optical shutter 101 supported on a surface 103 of a transparent substrate 102 by supports 104 and 105. Support 104 is attached to the first end 106 of shutter 101 and support 105 is attached to second end 107 of shutter 101 . Supports 104 and 105 are substantially straight and inclined relative to each other and to surface 103 and form an angle 113 with surface 103 of between 70 and 85 degrees. Supports 104 and 105 are attached to the surface 103 of substrate 102 through pad 109 with a distance 114 greater than the distance 115 between the attachment points of supports 104 and 105 on shutter 101. ) is attached to. Shutter assembly 100 may be configured to have supports 104 and 105 that are inclined relative to each other and attached to surface 103 at a distance 114 that is less than distance 115 . Supports 104 and 105 and pad 109 are made of thin conductive material and provide an electrical connection from surface 103 to shutter 101. Shutter 101 is also made of a thin conductive material or multilayer film that also includes a conductive layer. Shutter 101 includes a light transmitting area 108 and a light blocking or blocking area 110. The light blocking area 110 is larger (wider and longer) than the light transmitting area 108. The light transmitting area 108 transmits more than 90% of the light that strikes the light transmitting area 108, and the light blocking area 110 blocks at least 99% of the light.

The outer edge or all edges of the shutter 101 are beveled so that the shutter 101 does not bend. Shutter assembly 100 may be fabricated on a mold made of metal such as aluminum and silicon alloy. In one implementation, all surfaces of shutter 101 may have a light absorbing finish. In another implementation, the shutter 101 may have a first side 120 that reflects light and a second side 121 that absorbs light. The light reflecting surface 120 reflects more than 80% of the light, and the light absorbing surface 121 absorbs more than 80% of the light.

Depositing an aluminum layer on the surface of the mold will create a mirror-like first side 120 of the shutter 101, and a black oxide layer can be formed on the second side 121 by anodizing. The black oxide layer may be formed after etching the light transmissive area 108 such that the inner edge of the light transmissive area 108 is covered with the black oxide layer.

Chromium or niobium oxide may be deposited to form a light absorbing surface, or a black organic resin may be applied to the shutter 101.

Without limitation, portions of shutter assembly 100 may have the following dimensions: Shutter 101 may have a width 115 between 50 and 1000 micrometers and a thickness between 0.5 and 5 micrometers. The light transmissive area 108 may have a width 122 of 2 to 50 micrometers. Supports 104 and 105 may have a width of 2 to 20 micrometers and a thickness of 0.5 to 5 micrometers. The supports 104 and 105 may have a length 112 that is 1.5 to 3 times the width 122 of the light transmitting area 108.

2A and 2B show a mold 200 for manufacturing the shutter assembly 100. FIG. 2A is a top view of the mold 200 and FIG. 2B is a cross-sectional view taken along line segment 2B in FIG. 2A.

Mold 200 is constructed on surface 103 of substrate 102 using grayscale or multiple mask photolithography. A layer of sacrificial material 201 is deposited on surface 103. Grooves 203 and depressed areas 206 are formed in the surface 205 of the layer 201 . Shutter assembly 100 is constructed by depositing a thin layer of conductive film on the surface of mold 200 and selectively etching it. Supports 104 and 105 are formed on the side wall 204 of the groove 203. Side wall 204 has an angle of inclination 113 relative to surface 103 that is the same as supports 104 and 105. The recessed area 206 is provided to constitute a shutter 101 with beveled edges. The beveled edge helps prevent shutter 101 from bowing or bending. A combination of directional and conformal deposition of conductive material may be used to control the relative thicknesses of supports 104 and 105 and shutter 101.

3A-3D illustrate a light modulator 300 according to an exemplary embodiment of the present invention.

3A and 3B, the modulator 300 includes the shutter assembly 100 and the cover assembly 303 of FIG. 1A. Cover assembly 303 includes a transparent substrate 304 supported on a surface 103 of substrate 102 by spacers 306 and 307. Two electrodes 308 and 309 are formed on the inner surface 305 of the substrate 304.

The electrode 308 and the conductive shutter 101 form a first electrostatic actuator 311, and the electrode 309 and the conductive shutter 101 form a second electrostatic actuator 312. In operation, a voltage potential applied between the electrode 308 and the shutter 101 pulls the support 104 attached to the first end 106 of the shutter 101 to a substantially upright position relative to the surface 103. The voltage potential applied between the electrode 309 and the shutter 101 creates an electrostatic force (FIG. 3C) that pulls and moves the shutter 101 laterally (FIG. 3C) to the first position. Support 105 attached to end 107 is pulled to a nearly upright position relative to surface 103, creating an electrostatic force (FIG. 3D) that moves shutter 101 laterally (FIG. 3D) to a second position.

Stored mechanical force in supports 104 and 105 restores shutter 101 from the first or second position to a mechanical rest or neutral position as shown in FIG. 3B.

In the modulator 300, the first actuator 311 and the second actuator 312 each apply a force to the shutter 101 in substantially the same direction and move the shutter 101 laterally in opposite directions.

In Figure 3C, arrow 314 indicates the direction of the force applied to shutter 101 by first actuator 311, and arrow 315 indicates the direction of shutter 101 from the mechanical rest position to the first position. Direction Indicates the direction of movement. The shutter 101 moves laterally from the mechanical rest position to the first position at least five times more than in the direction of the force applied to the shutter 101 by the first actuator 311 .

In FIG. 3D, arrow 316 indicates the direction of the force applied to the shutter 101 by the second actuator 312, and arrow 317 indicates the direction of lateral movement of the shutter 101 into the second position. Displays .

Applying and increasing the voltage to the actuator 311 and decreasing the voltage applied to the actuator 312 will gradually move the shutter between the first and second positions, or applying a fixed voltage to the actuator 311. And applying a variable voltage to the actuator 312 will also gradually move the shutter between the first and second positions.

In a display, electrodes 308 and 309 may be shared by shutter assemblies that are formed wider and positioned in successive rows or columns.

4A and 4B illustrate a light modulator 400 according to an exemplary embodiment of the present invention. Modulator 400 includes a shutter assembly 401 and a cover assembly 418. Shutter assembly 401 includes a shutter 410 supported on a surface 403 of a transparent substrate 402 by supports 406 and 407. Support 407 is attached to the first end 408 of the shutter 410 and support 406 is attached to the second end 409 of the shutter 410. The shutter 410 is formed of an electrical insulator or dielectric material and includes a light transmitting area 411 and a light blocking area 412. The shutter 410 further includes a first electrode 405 and a second electrode 404. Support 407 provides an electrical connection from surface 403 to electrode 405, and support 406 provides an electrical connection from surface 403 to electrode 404.

Cover assembly 418 includes a transparent substrate 413 supported on surface 403 by spacers 416 and 417. The cover assembly 418 further includes a transparent conductive layer 415 formed of a material such as indium tin oxide on the inner surface 414 of the substrate 413.

In the modulator 400, the first electrode 405 and the conductive layer 415 form a first electrostatic actuator 418, and the second electrode 404 and the conductive layer 415 form a second electrostatic actuator 419. forms.

In operation, the first actuator pulls the support 407 to an approximately upright position relative to the surface 403, moves the shutter 410 laterally to the first position, and the second actuator moves the support 406 It is pulled into a substantially upright position relative to surface 403 and laterally moves shutter 410 to a second position. Stored mechanical force in supports 406 and 407 restores shutter 410 from the first or second position to a mechanical rest or neutral position as shown in FIG. 4B.

5A and 5B illustrate a light modulator 500 according to an exemplary embodiment of the present invention. Modulator 500 includes spacers 508 and 509 and a shutter assembly 503 formed on a surface 502 of a substrate 501 from polymer. Shutter assembly 503 includes a shutter 507 and shutter supports 505 and 506 formed of a conductive material and attached to spacers 508 and 509 by conductive pads 512 and 513.

Modulator 500 further includes two electrodes 510 and 511 formed on surface 502 of substrate 501. The electrode 510 and the conductive shutter 507 form a first electrostatic actuator 514, and the electrode 511 and the conductive shutter 507 form a second electrostatic actuator 515.

The shutter assembly 503 is constructed similarly to the shutter assembly 401, and the two electrodes 510 and 511 may be replaced with a transparent conductive layer.

6A-6F illustrate a light modulator 600 according to an exemplary embodiment of the present invention. 6A to 6C, the modulator 600 includes an optical shutter 601 made of a conductive material and including a light transmitting area 602 and a light blocking area 603.

Shutter 601 is positioned on surface 605 of substrate 604 by four cantilever beams 606 and 607 formed between shutter 601 and surface 605 and substantially within the boundaries of shutter 601. supported (Figure 6c). A first end of each cantilever beam 606 and 607 is attached to surface 605 by a post 609 and a conductive pad 610, and a second end is attached to the shutter 601 by a post 608. do. Cantilever beam 606 is attached to first end 618 of shutter 601 and cantilever beam 607 is attached to second end 617 of shutter 601 . Beams 606 and 607 are positioned substantially parallel to surface 605 and spaced from surface 605 by a first gap 619 . Beams 606 and 607 are also positioned substantially parallel to shutter 601 and spaced apart from shutter 601 by a second gap 620 . The cantilever beams 606 and 607 may be formed to be thin and long so that they can be bent or bent without the need for large forces. Beams 606 and 607 may also be formed to have sufficient height oriented perpendicular to surface 605 to support the load of shutter 601.

Shutter 601 further includes a first flange 613 extending from a first end or edge 618 of shutter 601 toward surface 605 within 5 degrees from a normal to surface 605 . Shutter 601 further includes a second flange 615 extending from second edge 617 toward surface 605 within 5 degrees of a normal to surface 605 .

Beams 606 and 607 are inclined relative to surface 629 of flange 613 and form an angle 628 of 70 to 89 degrees (FIG. 6D).

Modulator 600 further includes two electrodes 614 and 616 extending at near right angles from surface 605. Electrode 614 is attached to surface 605 by conductive pad 611, and electrode 616 is attached to surface 605 by conductive pad 612. Electrode 614 and flange 613 form a first electrostatic actuator 622 , and electrode 616 and flange 615 form a second electrostatic actuator 621 .

In operation, actuator 622 applies a first force 625 to shutter 601 and pulls beam 606 attached to first end 618 of shutter 601 ) toward a first position substantially laterally 626 relative to the first force 625 (FIG. 6E), the actuator 621 applies a second force 627 to the shutter 601, pulling the beam 607 attached to the second end 617 of the shutter 601 and moving the shutter 601 substantially laterally 628 relative to the second force 627 toward the second position. (Figure 6f). Shutter 601 moves laterally 626 at least five times more than in the direction of first force 625.

The stored mechanical force in beams 606 and 607 restores shutter 601 from the first or second position to a mechanical rest or neutral position as shown in FIG. 6D. Shutter 601 moves between a first position and a second position in a plane substantially parallel to surface 605 .

When the shutter 601 moves from the mechanical rest position (FIG. 6D) to the first position (FIG. 6E), the straight-line distance between the posts 608 and 609 attached to the ends of the beam 607 increases. For this reason, beam 607 is formed to be somewhat curved to compensate for the increased straight-line distance between posts 608 and 609.

7A-7D illustrate a light modulator 700 according to an exemplary embodiment of the present invention. The modulator 700 includes an optical shutter 701 comprised of a conductive material and including a light transmitting area 702 and a light blocking area 703. Shutter 701 further includes a first flange 708 attached to shutter 701 at a first end 706. Shutter 701 is supported on surface 704 of substrate 705 by four cantilever beams 712 and 714 (FIG. 7C).

A first end of each cantilever beam 712 and 714 is attached to surface 704 by post 716 and a conductive pad 717, and the second end is attached to shutter 701 by post 715. do. Cantilever beam 714 is attached to first end 706 of shutter 701 and cantilever beam 712 is attached to second end 707 of shutter 701 . Cantilever beams 712 and 714 are substantially straight. Cantilever beam 714 is inclined relative to flange 708 and forms an angle 730 of 70 to 89 degrees, and cantilever beam 712 forms an angle 731 of approximately 90 degrees with flange 708.

Modulator 700 further includes an electrode 709 extending perpendicularly from surface 704 and attached to surface 704 by a conductive pad 710 . Electrode 709 and flange 708 of shutter 701 form electrostatic actuator 711.

In operation, actuator 711 pulls beam 714 attached to first end 706 of shutter 701 in direction 720 and substantially rotates shutter 701 relative to direction 720. It is moved toward the first position in direction 721 (FIG. 7d). Stored mechanical forces in beams 712 and 714 restore shutter 701 from the first position to a mechanical rest or neutral position (FIG. 7A). Shutter 701 moves between positions in a plane substantially parallel to surface 704.

The modulator 700 has a second flange 722 attached to the shutter 701 at a second end 707 and a second flange 722 that extends perpendicularly from the surface 704 and is attached to the surface 704 by a conductive pad 724. It may further include a second electrostatic actuator 725 formed by two electrodes 723. In the modulator 700, the support 712 limits the movement of the shutter 701 and the second flange 722 closer to the second electrode 723, so that the second electrode 723 moves closer to the second flange 722. ) can be positioned at a short distance to form an efficient actuator.

In a display, a pixel addressing voltage may be applied to a second actuator 725 to selectively hold the shutter 701 in a mechanically neutral position.

8A-8F illustrate steps in fabricating a shutter support 800, similar to supports within modulators 600 and 700, according to an exemplary embodiment of the invention. 8A shows a shutter support 800 including a cantilever beam 803. A first end of the beam 803 is attached to a first post 804 that connects the beam 803 to the surface 801 of the substrate 802 via a pad 805, and a second end of the beam 803 is attached to the second post 806, which is later connected to the shutter. The first post 804 and the second post 806 each have three sides and a top.

Support 800 is formed on mold 807. The first manufacturing step is to form a mold 807 from a sacrificial material on the surface 801 of the substrate 802 (FIG. 8B). Mold 807 is formed in the shape of a rectangular prism and has four side walls 808, 809, 810 and 811 and a top 812. The sidewalls are oriented perpendicular to surface 801 within +/- 5 degrees relative to the normal. The next steps include depositing a conformal conductive material 814 on the surface 801 and the surface of the mold 807 by magnetron sputtering and forming a positive photoelectric layer on the conductive layer 814 by electrophoretic deposition or spraying. A conformal layer 815 of resist is applied (FIG. 8C).

The next step is to position the first photomask 816 on the mold 807 (FIG. 8D) with a divergence angle of less than 2 degrees and an inclination angle of 45 to 75 degrees from the direction of the sidewalls 808 and 809 with respect to the surface 801. The photoresist layer 815 is illuminated with a UV light source having 817 (FIGS. 8E and 8F). Mold 807 and first photomask 816 form a photoresist layer 815 that defines the geometry of cantilever beam 803, first post 804, second post 806, and pad 805. Blocks UV light from the upper region. The next step is to position the second photomask 818 on the mold 807 (Figure 8g) and illuminate the photoresist layer 815 from the direction of the sidewall 811 (Figure 8j). Then, the photoresist layer 815 applied to the lower part of the side wall 811 will be illuminated. The steps shown in FIGS. 8G and 8J can be omitted if the second post 806 is formed with only two side and top surfaces formed on the side walls 808 and 809 of the mold 807. .

After illumination from all three directions, the photoresist layer 815 is developed and the unprotected areas of the conductive layer 814 are removed by etching. The cantilever beam 803 formed on the mold 807 has a width equal to the thickness of the conductive layer 814.

If the conductive layer 814 is formed of a material such as aluminum that can reflect UV light, a light absorbing layer may be applied or formed on the conductive layer 814 prior to applying the photoresist layer 815. . This will reduce the reflection of UV light from horizontal and vertical surfaces. To reduce reflections from the surface of photoresist layer 815, the mold and mask can be immersed in a liquid having a similar refractive index as photoresist layer 815.

9A-9F illustrate steps for fabricating a shutter 900 and electrode 905, similar to modulators 600 and 700, according to an exemplary embodiment of the invention.

FIG. 9A shows a shutter 900 including a light transmitting area 901 and a flange 902 . Shutter 900 is connected to post 806 of support 800 described above. 9A further shows an electrode 905 attached to the surface 801 of the substrate 802 by a pad 904.

The first manufacturing step is to form a mold 910 containing two rectangular prisms 911 and 912 on the surface 801 of the substrate 802 using a sacrificial material. Prism 911 has four side walls 914, 915, 916, 917 and a top surface 918. Prism 912 has four side walls 920, 921, 923, 924 and a top surface 925. The sidewalls are oriented perpendicular to surface 801 within +/- 5 degrees from the normal. A via hole 926 is formed at the top 918 of the prism 911 to connect the shutter 900 to the post 806 of the support 800.

The next steps include depositing a conformal conductive material 930 on the surface 801 and the surface of the mold 910 and forming a conformal layer 931 of negative photoresist on the conductive layer 930. It is deposited (Figure 9c).

The subsequent steps are positioning the photomask 932 on the mold 910 (FIG. 9D) and illuminating the photoresist layer 931 with a UV light source having a beam of light collimated and oblique from the direction of the sidewalls 916 and 924. (Figures 9e and 9f).

The mask 932 is a photoresist layer 931 applied to the surfaces of the side walls 915, 916, 917, 920 and 923 and the area of the top surface 918 where the light transmitting area 901 of the shutter 900 is formed. ) blocks UV light illumination. The mold blocks a portion of the surface 801 between the side walls 914 and 921 and the lower portion of the surface of the side walls 914 and 921 where the flange 902 and the electrode 905 are formed.

After illumination from all three directions, the photoresist layer 931 is developed and the unprotected areas of the conductive layer 930 are etched.

The next step is to remove the sacrificial layer and release the shutter 900 and support 800.

Shutter 900 may be formed to include flanges, such as flange 902, on all four edges of shutter 900. These flanges can improve contrast by effectively blocking stray light from leaving the display.

10A, 10B, and 10C illustrate a display backlight 1000 according to an exemplary embodiment of the present invention. FIG. 10A is a perspective view of the backlight 1000, FIG. 10B is a side view of the backlight 1000, and FIG. 10C is an enlarged view of the area designated 10C in FIG. 10B.

The backlight 1000 includes a generally planar light guide 1001 made of acrylic or other transparent material with a refractive index n1 having a value between 1.45 and 1.6. Light guide 1001 includes a top surface 1002, a bottom surface 1003, opposing sides 1004 and 1005, and a light input end 1006.

The bottom surface 1003 is inclined relative to the top surface 1002 and forms an angle 1009 (FIG. 10B) with a value of approximately 0.1 to 2.0 degrees. The bottom surface 1003 approaches the top surface 1002 in a direction away from the optical input terminal 1006.

The backlight 1000 further includes a light absorption film 1010 positioned close to the bottom surface 1003 of the light guide 1001 and a plurality of light sources 1011 positioned close to the light input terminal 1006.

The backlight 1000 further includes a first optical layer 1015 comprised of a substantially transparent material with a refractive index n2 having a value of about 1.45 to 1.6. The first optical layer 1015 includes a light exit surface 1016, a light input surface 1017, and a plurality of embedded light reflectors 1018 located between the light input surface 1017 and the light exit surface 1016. Includes. Light reflector 1018 is formed from a thin light reflecting material such as aluminum or silver. Light reflector 1018 can have a substantially flat surface or a curved surface with a radius of curvature of about 20 to 80 microns. The light reflector 1018 is inclined relative to the top surface 1002 of the light guide 1001 and forms an angle 1026 with a value of approximately 20 to 40 degrees.

The backlight 1000 further includes a second optical layer 1020 formed between the light input surface 1017 of the first optical layer 1015 and the top surface 1002 of the light guide 1001. The second optical layer 1020 is composed of a fluoropolymer or other substantially transparent material with a refractive index n3 of a value of about 1.3 to 1.4.

In operation, light rays 1023 entering from the light input end 1006 of the light guide 1001 reflect from the top surface 1002 and the bottom surface 1003 and change their angle toward the normal to the top surface 1002. I order it. Light ray 1023 has an angle of incidence on the top surface 1002 that is less than the critical angle 1024 (FIG. 10C) defined by the refractive index n1 of the light guide 1001 and the refractive index n3 of the second optical layer 1020. Exits the light guide 1001. The light ray 1023 passing through the second optical layer 1020 enters the first optical layer 1015 from the light input surface 1017 and has an angle defined by the refractive index n2 of the first optical layer 1015. change it Almost all light rays 1023 entering the first optical layer 1015 are reflected internally from the light exit surface 1016. Light rays leave the first optical layer 1015 from the light exit surface 1016 by reflection from the embedded light reflector 1018. The light rays reflected from the curved light reflector 1018 leave the first optical layer 1015 from the light exit surface 1016 and converge at a predetermined distance 1025 from the light exit surface 1016.

The backlight 1000 may further include a transparent substrate such as a glass substrate and a dichroic filter layer interposed between the first optical layer 1015 and the second optical layer 1020.

The manufacturing steps of optical layer 1108 with embedded light reflector or light reflecting surface 1106 are shown in FIGS. 11A-11D. In step (A), a micro-prism 1101 is constructed from a transparent UV cured liquid polymer on a substrate 1103 using photolithography. In step (B), the substrate 1103 is tilted about an angle 1105 (FIG. 11B) and the extension 1104 of the micro-prism 1101 is formed from the same liquid polymer. Micro-prisms 1101 with extensions 1104 can also be molded. In step (C), a reflective mirror film is deposited on each side of the extension 1104 to form a light reflecting surface 1106. In step (D), grooves 1107 are filled with the same UV cured liquid polymer. FIG. 11D shows optical layer 1108 with embedded light reflecting surface 1106.

Optical layer 1108 may be coupled with shutter assembly 100 or 401 in modulators 300 and 400 disclosed above. Optical layer 1108 may be constructed on a substrate and positioned between shutter supports prior to constructing shutter assembly 100 or 401. For modulators 500, 600 or 700 with a shutter located at a proximate distance from the surface of the substrate, an embedded light reflector may be configured within the substrate.

12A, 12B, and 12C illustrate steps in fabricating a glass substrate 1200 with an embedded light reflector 1205 according to an exemplary embodiment of the present invention. The first step is to etch grooves 1203 in the glass substrate 1200. The next three steps are similar to steps B, C and D described above. The second step is to tilt the substrate 1200 and form extensions 1204 in each groove with UV cured liquid polymer. The third step is to deposit a reflective mirror film on the extension portion 1204 to form a light reflecting surface 1205. The fourth step is to fill the grooves with the same UV cured liquid polymer. FIG. 12C shows a glass substrate 1200 configured with an embedded light reflector 1205. The cured polymer preferably has a refractive index substantially the same as that of the glass substrate 1200. In backlight 1000, first optical layer 1015 can be replaced with glass substrate 1200 and modulator 500, 600, or 700 can be constructed on glass substrate 1200.

13A and 13B illustrate a display cover assembly 1400 according to an exemplary embodiment of the present invention. The cover assembly 1400 includes a transparent substrate 1401 having a first side 1402 and a second side 1403. The cover assembly 1400 further includes a light diffusion layer 1404 formed on the first surface 1402 and a light absorption layer 1405 formed on the light diffusion layer 1404. For thin substrates with a thickness of 200 micrometers or less, the diffusion layer 1404 may be formed on the second or outer surface 1403 and the light absorption layer 1405 may be formed on the inner surface 1402 of the substrate 1401. It can be. The light absorption layer 1405 includes a light transmission area 1407 and an opaque light absorption area 1406. The cover assembly 1400 includes electrodes, such as electrodes 308 and 309 of the modulator 300, formed on the opaque light absorbing region 1406 of the light absorbing layer 1405 having a light reflecting mirror surface or within the modulator 400. It may further include a transparent conductive layer such as the electrode 415.

The light absorption layer 1405 may be formed of a conductive material. Conductive light absorbing layer 1405 may serve as an EMI or electrostatic shield within a display or as an electrode for an actuator, such as the actuator within modulator 400.

The light absorption layer 1405 may absorb more than 80% of the light that strikes the opaque light absorption region 1406 and transmit less than 1% of the light.

Displays based on electromechanical light modulators can include a large number of modulators arranged in rows and columns. Each picture element or pixel within a display may include one or more modulators. For illustrative purposes the following figures illustrate a display with only one modulator.

14A and 14B show cross-sectional views of display 1500 according to an exemplary embodiment of the present invention. Display 1500 includes a cover assembly 1501, a modulator 1502, and a backlight 1503 that includes a back reflector 1504. The cover assembly 1501 includes a transparent substrate 1505, a light diffusion layer 1506 formed on the first side 1507 of the substrate 1505, and a light absorption layer 1508 formed on the light diffusion layer 1506. The light absorption layer 1508 includes a light transmission area 1509 and an opaque light absorption area 1510. The modulator 1502 includes a shutter 1511 having a light transmitting area 1514 and a light blocking area 1515. The surface of the shutter 1511 facing the backlight 1503 is a light reflecting surface, and the surface facing the light absorption layer 1508 is a light absorbing surface. The light transmitting area 1509 of the light absorption layer 1508 is larger than the light transmitting area 1514 of the shutter 1511 and is smaller than the light blocking area 1515 of the shutter 1511. In FIG. 14A, the shutter 1511 is in the first position or on position, and in FIG. 14B, the shutter 1511 is in the second position or off position. Light 1520 that strikes the light transmissive area 1514 of the shutter 1511 from the backlight 1503 passes through the light transmissive area 1509 of the light absorption layer 1508 when the shutter 1511 is in the first position. It is transmitted (FIG. 14A) and absorbed in the light absorbing layer 1508 (FIG. 14B) when the shutter is in the second position. Light that strikes the light blocking area 1515 of the shutter 1511 is reflected back to the backlight 1503 and recycled by being reflected from the back reflector 1504. Modulator 1502 may be any of the modulators disclosed above or a modulator that includes a shutter having a light reflecting surface facing the backlight 1503 to recycle the light emitted from the backlight 1503.

It is important to design the modulator so that the shutter supports do not take up much more space than the display surface required by the shutters, so that the shutters are positioned very close to each other, allowing movement of the shutters and just enough space for a few conductors to fit between them. .

The shutter assembly disclosed above satisfies these requirements. Compared to some prior art shutter assemblies where the shutter supports are positioned next to the shutter and occupy more than 50% of the display surface, in the shutter assembly disclosed above the shutter supports are positioned between the shutter and the surface on which the shutter is supported; positioned substantially within the boundaries of the shutter including movement of the shutter between the first and second positions.

This increases light efficiency by increasing the total light transmission area relative to the display surface and reduces the spacing between rows and columns of the display.

In display 1500, light absorbing layer 1508 may be formed of a conductive material and may replace electrode 415 in modulator 400 disclosed above.

The electrodes 308 and 309 of the modulator 300 may be formed on the light absorbing layer 1508 having a light reflecting surface facing the backlight 1503, and the shutter 101 may be formed on the surface 1522 of the substrate 1521. It can be supported on top. Shutter 601 of modulator 600 and shutter 701 of modulator 700 may also be supported on surface 1522 of substrate 1521 . The spacers 508 and 509 of the modulator 500 may be formed in the light absorption layer 1508 and the shutter 503 may be suspended from the spacers 508 and 509.

In display 1500, backlight 1503 emits surface light and may be an edge lit or direct lit backlight, as known from LCD displays.

15A and 15B show cross-sectional views of display 1700 according to an exemplary embodiment of the present invention. Display 1700 includes a cover assembly 1701, a modulator 1702, and a backlight 1703. The cover assembly 1701 includes a transparent substrate 1705, a light diffusion layer 1706 formed on the first surface 1707 of the substrate 1705, and a light absorption layer 1708 formed on the light diffusion layer 1706. The light absorption layer 1708 includes a light transmission area 1709 and a light absorption area 1710. The modulator 1702 includes a shutter 1711 having a light transmitting area 1714 and a light blocking area 1715. The surface of the shutter 1711 facing the backlight 1703 may be a light reflecting surface or a light absorbing surface, and the surface facing the light absorbing layer 1708 is a light absorbing surface. The light transmitting area 1709 of the light absorption layer 1708 is larger than the light transmitting area 1714 of the shutter 1711 and is smaller than the light blocking area 1715 of the shutter 1711. The modulator 1702 further includes a substrate 1716 having a light exit surface 1721 and an embedded light reflection surface 1717. The facets 1717 are curved and allow light 1720 from the backlight 1703 to leave the substrate 1716 and converge on the light transmitting area 1714 of the shutter 1711. Shutter 1711 is supported on surface 1721 of substrate 1716. Backlight 1703 includes a light guide 1719 and an optical layer 1718 positioned between light guide 1719 and substrate 1716. Backlight 1703 is similar to backlight 1000 in FIGS. 10A-10C. The backlight 1703 further includes a light absorbing layer 1704 positioned behind the light guide 1719 for absorbing stray light or light reflected from the shutter 1711.

In FIG. 15A the shutter 1711 is in the first position or on position, and in FIG. 15B the shutter 1711 is in the second position or off position. The light 1720 emitted from the substrate 1716 is transmitted by the light transmission area 1714 of the shutter 1711 and the light transmission area 1709 of the light absorption layer 1708 when the shutter 1711 is in the first position. (FIG. 15a), and when the shutter 1711 is in the second position, the light is blocked by the light blocking area 1715 of the shutter 1711 (FIG. 15b). Light reflected back from the light blocking area 1715 of the shutter 1711 is absorbed within the light absorption layer 1704.

In display 1700, curved reflector 1717 increases the viewing angle of the display and reduces the required travel distance of shutter 1711 between the ON and OFF positions when compared to a flat reflector.

The display described above consists of substrates, spacers to maintain precise distances between row and column conductors formed on one or both of the substrates, one or more thin film transistors for addressing the display pixels, and a storage capacitor, ground plane, or power circuit. It may further include a surface, a common interconnect for resetting the display pixels, a dichroic or color filter, and a reflective ring coating.

The displays described above may be named electromechanical, micromechanical, micro-electromechanical, or micro-electro-mechanical system (MEMS) displays. The display described above may be a black-and-white display, a color display, or a color sequential display.

Now that the invention has been described in detail in accordance with the requirements of patent law, those skilled in the art will find no difficulty in making modifications and changes in the individual parts or their relative assembly or manufacturing methods to satisfy particular requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention as set forth in the following claims.

Claims (15)

As an electromechanical display element,
first and second electrostatic actuators, and
a shutter having first and second ends,
The shutter is supported on the surface of the substrate by a plurality of supports attached to the first end and a plurality of supports attached to the second end,
The longitudinal direction of the support attached to the first end of the shutter is inclined with respect to the longitudinal direction of the support attached to the second end of the shutter, and the longitudinal direction of the support attached to the first and second ends of the shutter is inclined with respect to the longitudinal direction of the support attached to the first and second ends of the shutter. It is inclined with respect to the surface of the substrate,
A first electrostatic actuator applies a force to a first end of the shutter and pulls the support attached to the first end to an upright position relative to the surface of the substrate, moving the shutter to the first position. move it,
A second electrostatic actuator applies a force to the second end of the shutter and pulls the support attached to the second end to an upright position relative to the surface of the substrate and moves the shutter to the second position. Mechanical display element. According to claim 1,
wherein the first and second actuators each apply a force to the shutter in the same direction and move the shutter laterally in an opposite direction to the applied force. According to claim 1,
The electromechanical display element is,
further comprising first and second electrodes,
the first electrode and the shutter form the first electrostatic actuator,
wherein the second electrode and the shutter form the second electrostatic actuator. According to claim 1,
The electromechanical display element is,
It further includes a first electrode 405 and a second electrode 404 formed on the shutter,
The first electrode 405 forms the first electrostatic actuator with a conductive layer 415,
wherein the second electrode (404) forms the second electrostatic actuator with the conductive layer (415). According to claim 1,
The shutter includes first and second electrodes,
a support attached to the first end of the shutter provides a first electrical connection from the surface of the substrate to the first electrode,
and a support attached to the second end of the shutter provides a second electrical connection from the surface of the substrate to the second electrode. According to claim 1,
The support is straight,
A plurality of supports attached to the first end are parallel to each other,
An electromechanical display element, wherein the plurality of supports attached to the second end are parallel to each other. According to claim 1,
The electromechanical display device of claim 1, wherein the shutter includes a light absorbing surface. According to claim 1,
The electromechanical display device of claim 1, wherein the shutter includes a first side that absorbs light and a second side that reflects light. According to claim 1,
Each of the supports forms an angle of 70 to 85 degrees with the surface of the substrate. According to claim 1,
The electromechanical display device of claim 1, wherein the shutter includes a beveled edge. delete delete delete delete delete

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