LED lighting projector

Abstract

The present invention relates to a projector for generating a frame of an image. The projector may be used in an augmented reality or virtual reality device. The projector comprises an array of elements arranged in a plane, wherein each element comprises at least three LEDs having different colors, and a collector structure array, wherein each collector structure is configured to receive light from a single LED at any time and reduce the angle at which the LED emits light. The projector further comprises a projector unit configured to receive light from the collector structure array and collimate the light to form a frame. The frame is full color and is formed by combining a plurality of subframes, wherein the subframes are formed through spatial displacement of the element array relative to the collector structure array such that each collector structure receives light from a different LED during each subframe, and / or the subframes are formed through displacement of light emitted from each LED such that the light from each LED illuminates multiple pixels of the frame.

Description

Technology Field

[0001] The present invention relates to a projector. Specifically, it relates to a projector used in a waveguide system. Background Technology

[0002] Projectors for small devices, such as pico projectors, and wearable devices, such as virtual reality (VR) and augmented reality (AR) headsets, need to be lightweight and comfortable for users who need to hold or wear the device for a long time at a time.

[0003] A typical projection system includes a light source for generating light, an optical device for forming this light into a light path, a homogenizer for making this light path homogenized, and a relay for relaying the homogenized light path to a display to be illuminated.

[0004] Ideally, rather than relying on modulation displays to generate images that require separate lighting, it is preferable to use LED arrays that act as light sources to produce light, as LEDs can generate images. With the advent of Micro LEDs, the use of Micro LEDs will make increasingly smaller projectors possible.

[0005] Self-emissive panels, which theoretically generate light and create images, must provide improvements in the size of the reflective panel because they do not require a separate element to provide light. This also leads to improvements in image efficiency, brightness, and contrast.

[0006] However, since LEDs are Lambertian emitters, they emit light over a wide angular range. This can cause problems with system efficiency, as a significant portion of the emitted light may be lost. Optics can be used to help collect the maximum amount of emitted light. However, this increases the size of the system. Additionally, since each LED produces only a single color, multiple LEDs of different colors are required to create a single image pixel. This limits the resolution achievable in a system of a specific size.

[0007] According to one aspect of the present invention, a projector for generating a frame of an image is provided, the projector comprises: an array of elements arranged in a plane, wherein each element comprises at least three LEDs having different colors; a collector structure array, wherein each collector structure is configured to receive light from a single LED at any time and reduce the angle at which the LED emits light; and a projector unit configured to receive light from the collector structure array and collimate the light to form a frame, wherein the frame is full color and is formed by combining a plurality of subframes, and the subframes are formed through spatial displacement of the element array relative to the collector structure array such that each collector structure receives light from different LEDs during each subframe, and / or the subframes are formed through displacement of light emitted from each LED such that the light from each LED illuminates multiple pixels of the frame.

[0008] Since LEDs are Lambertian emitters, they emit light over a wide angular range. The collector structure enables the collection of light emitted from the LED, thereby reducing the angle of light emission. This improves the efficiency of the projector because the light emitted from the LED can be efficiently collected into a light path toward the display without loss.

[0009] In this way, the LED arrays can be arranged in a small area, and at the same time, a single collector structure can provide a full-color display without compromising image resolution, even though it can only illuminate with a single LED at a time. The movement of the element and collector array relative to each other, and / or the displacement of light from each LED, are each performed faster than the frame rate, so that a full-color image can be obtained without loss of resolution.

[0010] The displacement of light can be spatial or angular displacement. For example, spatial displacement may occur before the light is collimated. Angular displacement may occur after the light is collimated.

[0011] Preferably, each of at least three LEDs has an associated collector structure. In some arrangements, each collector structure may be associated with a single LED. In other arrangements, each collector structure may be associated with a single element, so that for each element, at least three LEDs are associated with the same collector structure. Since light from only a single LED can be collected by a single collector at a time, relative movement between the collector and the LED may be required.

[0012] Preferably, the projector unit includes an optical element that is adjustable to induce a displacement of light emitted from each LED, so that the light from each LED illuminates multiple pixels of the frame.

[0013] In this way, the resolution of the generated frame is maintained through an optical element that causes a displacement of light to be incident on multiple pixels for each frame, despite having different LEDs of different colors. The optical element can move at a speed capable of projecting light from each LED to multiple individual pixels on the display over a period equal to or less than the period during which the full-color frame is displayed.

[0014] The optical element is preferably a ray angle shifter capable of adjusting the angular position of the light. For example, the optical element may be an adjustable mirror. The mirror may be configured to switch between multiple positions or directions to provide displacement of the light. Alternatively, any type of electromechanical device capable of changing the direction of the light may be used.

[0015] Alternatively, the displacement may be an apparent optical motion. This may be provided by an oscillating wedge. The oscillating wedge may be made of glass. Alternatively, the optical element may be an angle-shifting shifting plate. For example, a nutating plate may be placed behind the collector array in front of the projector unit. The nutation of the plate may provide light displacement through tilting in different directions.

[0016] The displacement of light can occur through yaw rotation (vertical axis) and / or pitch rotation (transverse axis) of the optical element. Therefore, light can experience yaw and / or pitch rotation. That is, this can be in the x direction and / or the y direction. This may vary depending on the arrangement of LEDs in a plane. If LEDs of different colors are arranged horizontally in a plane, displacement may occur due to yaw rotation. Alternatively, if LEDs of different colors are arranged vertically in a plane, displacement may occur due to pitch rotation. Or, it may be a combination of pitch and yaw.

[0017] In other arrays, light from each LED can illuminate multiple pixels of the frame on its behalf (or additionally) through the movement of the collector array and element array relative to the projector unit.

[0018] The projector unit may further include a projector lens and an adjustable optical element. The projector lens converts light from a spatial position to an angular position to form a frame of an image. Alternatively, in an array where there is no displacement of light emitted from each LED, the projector unit may include only a projector lens.

[0019] The element array may be configured to be movable to provide spatial movement of the element array relative to the collector structure array. In this way, the collector structure may be static relative to other optical devices of the projector. Since the collector is static, there may be no need to move the light further to form a frame. The element array may include a mechanism to provide movement. The movement may occur along a plane.

[0020] Alternatively, the collector structure array may be configured to be movable to provide spatial movement of the element array relative to the collector structure array. In this way, the elements may be static relative to other optical devices of the projector and display where the user views the light. Due to the movement of the collector array, light from each LED can be collected during each frame. The element array may include a mechanism to provide movement. Movement may occur along a plane.

[0021] In some arrays, during the first subframe, the collector structure can receive light from the first LED among at least three LEDs, during the second subframe, the collector structure can receive light from the second LED among at least three LEDs, and during the third subframe, the collector structure can receive light from the third LED among at least three LEDs.

[0022] Preferably, each collector receives light from each LED of the device for the same amount of time. In this way, each subframe can have the same intensity.

[0023] In some arrays, if the device has n LEDs, there may be n subframes. Thus, the collector structure and / or the device may be movable between n different positions, that is, between at least a number of individual positions equal to the number of LEDs in the device.

[0024] In other arrangements, the collector structure array and the element array may both include a mechanism to enable movement in order to achieve the relative movement described above.

[0025] In some arrangements, the elements are arranged along a first axis extending in a first direction in a plane and along a second axis extending in a second direction in a plane, the first axis and the second axis are orthogonal to each other, each element includes LEDs of different colors arranged along at least the first direction, and the element array or collector array is configured to be movable along the first direction with respect to the collector.

[0026] In this way, the resolution of the projector can be increased along an axis where some LEDs on that axis are different colors. For example, this could be on the x-axis or the y-axis. This can be used to restore the resolution of that axis to be equal to the number of LEDs on that axis, despite the fact that LEDs of different colors may exist on that axis.

[0027] Each element may include LEDs of different colors arranged along a first direction and a second direction, and the element array or collector array is configured to be movable along the first and second directions. Therefore, even though there are LEDs of different colors on each axis, the resolution can be increased on both axes.

[0028] The displacement of light may be in the direction described above for the movement of the element and collector depending on the arrangement of the LEDs.

[0029] In some arrays, each subframe can be a single color. In this way, during each subframe, each collector is illuminated with an LED of the same color. Through this sequential color method, the combination of each subframe can provide a full-color image.

[0030] In other arrangements, each subframe may contain a different color. For example, different collectors may collect light from LEDs of different colors in each subframe, or each collector may collect light from LEDs of all different colors across a combination of subframes to form a full-color image frame. Since each collector may be associated with a single LED, each subframe may contain a distinct color. In this way, there may be no movement between LEDs (and elements) with respect to the collector structure. In such an arrangement, the displacement of light from each LED prevents loss of resolution. Advantageously, this requires fewer moving parts. This can provide the advantage that this projector is a quieter device.

[0031] In some arrays, each LED is configured to illuminate a single pixel in each subframe, and the displacement of light can cause the single pixel being illuminated to be different in each subframe. In this way, during the first subframe, each LED of each element illuminates a single pixel, and in the subsequent subframe, a different pixel that was illuminated in the previous subframe is illuminated by an LED of a different color. This provides a full-color frame. For example, the first pixel may be illuminated by an LED having a first color during the first subframe and by an LED having a second color during the second subframe.

[0032] In some arrays, each subframe formed can be shifted in the plane by one pixel. For example, during the first subframe, each LED can illuminate a pixel, and in the subsequent subframe, the LED can illuminate an adjacent pixel of the previous frame. This can be a pixel in an adjacent column or an adjacent row. In this way, each subsequent subframe can be shifted by a pixel (or up / down) compared to the previous subframe.

[0033] Preferably, the collector structure array is a microlens array and / or a tapered well structure. Microlenses can be used to reduce the angle of light emitted from the LEDs. Additionally, their small size makes them usable in systems such as pico projectors.

[0034] Alternatively, or additionally, the collector structure array in the microlens may be a tapered well structure array. The walls of the tapered well structure act as conduits for light emitted from the LED. Preferably, the tapered well structure has a first end configured to receive a light beam from the LED and a second end for emitting the light beam. The first end is preferably smaller than the second end so that the light can be expanded in two dimensions and the beam angle can be reduced by the tapered well structure. Preferably, the walls of the tapered well structure are glass that reflects light along the walls. Alternatively, the collector may be a tapered light pipe that acts as a conduit for light to pass through. The light pipe can also reduce the beam angle and expand the light in two dimensions. Thus, what is understood is preserved together with the collector.

[0035] At least three LEDs may include a red LED, a blue LED, and a green LED. In this way, each frame can be full color. Alternatively, the LEDs may be red, yellow, and blue. If there are four LEDs in the device, the additional LED may be white.

[0036] Alternatively, the device may include multiple LEDs of the same color. For example, the device may include red, green, blue, and red LEDs. In this arrangement, the collector may be arranged to sequentially collect light from each of the four LEDs of the device over a period equal to or shorter than the duration during which each individual frame is displayed. In this way, each LED can contribute to a subframe. Since the efficiency of red LEDs is low, using one or more red LEDs may improve image efficiency in some cases. In other arrangements, any color combination may be used.

[0037] Preferably, each element includes three or four LEDs. In an array with three LEDs, they can be arranged in a row. In this way, the element array can be arranged so that each column contains LEDs of the same color. Alternatively, the three LEDs can be arranged in rows. In this way, the element array can be arranged so that each column contains LEDs of the same color. Alternatively, the LEDs of each element can be arranged diagonally.

[0038] In an array where each element contains 4 LEDs, the LEDs can be arranged in a 2x2 configuration in a plane. Each element may contain 4 LEDs arranged in a 2x2 matrix. That is, each element may have 2 columns and 2 rows of LEDs. In other arrays, the LEDs can be arranged in a 3x1 configuration or a 1x3 configuration as described above. Alternatively, they can be arranged in a 4x1 configuration.

[0039] Preferably, in a first subframe, a first LED among at least three LEDs illuminates a first pixel, in a second subframe, a second LED among at least three LEDs illuminates a first pixel, and in a third subframe, a third LED among at least three LEDs illuminates a first pixel. In this way, each pixel of an image frame is formed by light from each different colored LED to form a full-color image.

[0040] Preferably, the LED is a micro LED. By using micro LEDs combined with a micro-lens array or a tapered well structure array, the size of the collecting optics can be reduced. The efficiency of the device is also improved compared to other types of light sources or conventional LEDs. As mentioned above, LEDs are Lambertian emitters, meaning they generally emit light over a wide angle, such as 2π steradians. When combined with a micro-lens or micro-well structure array, micro LEDs are not Lambertian emitters and emit over a much smaller angle range, thereby reducing light loss.

[0041] In some arrays, the number of subframes is equal to the number of LEDs in the device. For example, if there are 3 LEDs, there may be 3 subframes. Therefore, for a device containing RGB LEDs, the number of subframes may be 3.

[0042] In another aspect of the present invention, an augmented reality or virtual reality device comprising a projector of the above-described aspect is provided.

[0043] According to another embodiment, a projector display system is provided comprising a display for displaying an image; and a projector according to the above embodiment.

[0044] The display can be a waveguide. For example, it can be a waveguide for an augmented reality or virtual reality device.

[0045] According to another aspect, a method for generating a frame of an image using a projector is provided, the method comprising: a step of emitting light from an array of elements arranged in a plane, wherein each element comprises at least three LEDs having different colors; a step of receiving the light emitted from the array of elements in a collector structure array, wherein each collector structure receives light from a single LED at any time to reduce the angle at which the LED emits light; a step of emitting light from the collector structure array with reduced angle; and a step of receiving light from the collector structure array and collimating the light in a projector unit to form a frame; wherein the frame is full color and is formed by combining a plurality of subframes, and the subframes are formed through spatial displacement of the array of elements relative to the collector structure array such that each collector structure receives light from a different LED during each subframe, and / or the subframes are formed through displacement of light emitted from each LED such that light from each LED illuminates multiple pixels of the frame. Brief explanation of the drawing

[0046] Figures 1a and 1b are a front view and a side view of a green LED panel, respectively. FIGS. 2a and FIGS. 2b are, respectively, a front view and a side view of a green LED panel and a corresponding collector. Figures 3a and 3b are front and side schematic diagrams of LED panels of red, green, and blue LEDs and corresponding collectors, respectively. FIG. 4 is a schematic diagram of a downward view of a projector according to an embodiment of the present invention, illustrating the projection of an image onto a waveguide so that a user can view it. FIGS. 5a to 5c are front views showing different positions of the collector relative to the LED panel of the LED panel and collector array of the projector shown in FIG. 4. FIG. 5d is a front view of a full-color image frame generated from light from each of the positions shown in FIG. 5a to 5c. FIG. 6 is a schematic diagram of a downward viewpoint of a projector according to another embodiment of the present invention, illustrating the projection of an image onto a waveguide so that a user can view it. Figure 7 is a front view of the LED panel and collector array of the projector shown in Figure 6. FIG. 8a is a schematic diagram illustrating how full-color image pixels are formed from three different subframes for a projector as shown in FIG. 6. FIG. 8b is a front view of a full-color image frame generated from light from three different subframes shown in FIG. 8a. FIG. 9 is a schematic diagram of three subframes generated using the projector shown in FIG. 6 to generate the full-color image frame shown in FIG. 8b. FIG. 10 is a schematic diagram of a downward view of a projector according to another embodiment of the present invention, illustrating the projection of an image onto a waveguide so that a user can view it. FIG. 11a is a schematic diagram of an LED panel of a projector as shown in FIG. 10. FIG. 11b is a schematic diagram of a collector array of a projector as shown in FIG. 10. FIGS. 12a and FIGS. 12b illustrate schematic diagrams of an LED and a collector showing different positions of the collector for the LED for a projector as shown in FIG. 10. FIGS. 13a through 13d show schematic diagrams of the movement of a collector for an LED array for a projector as illustrated in FIG. 10. FIG. 14 is a schematic diagram of a light beam angle shifter that converts light from a first position into a green subframe with increased resolution for a projector as shown in FIG. 10. FIG. 15 shows a schematic diagram of a series of subframes formed by each position of the collector for the LED array as illustrated in FIG. 13a to 13d and a generated full-color image frame. And FIGS. 16a to 16e show schematic diagrams of exemplary movement of light so that the resolution of the image generated by each of the positions shown in FIGS. 13a to 13d can be increased. Specific details for implementing the invention

[0047] The difficulties in using an LED as an image source for a projector are illustrated and explained with reference to FIGS. 1a to 3b.

[0048] FIG. 1a shows one side of a green LED array (2) arranged in a plane. FIG. 1b is a side view of three green LEDs (2a) of the array (2) along with light (3) emitted from the LEDs. To indicate the colors of the LEDs shown in the drawings, a key is included at the top of FIG. 1a and the other drawings. As can be seen in FIG. 1b, since the LEDs are Lambertian emitters, light is emitted from each LED (2a) over a wide angular range. This is problematic for use in projection displays because the light from each LED is scattered over a wide area instead of forming the light rays necessary to project and form an image.

[0049] FIG. 2a is a front view of a green LED array (2) showing a potential solution to the problem of Lambertian emission. An array of collectors (6) is arranged on the green LED array (2). FIG. 2b is a side view of this array. As can be seen in FIG. 2b, the collectors (6) reduce the angle at which light is emitted from the LEDs (2). However, as can be seen in FIG. 1b and FIG. 2b, the size of the LEDs (2a) becomes smaller when using the collectors (6) to ensure that all light from each LED (2) is collected by the associated collectors.

[0050] The arrays shown in FIGS. 2a and 2b produce only single-color images because all LEDs emit green light. FIGS. 3a and 3b illustrate an array of LEDs (2) and a collector (6) capable of producing full-color images. In this array, the LED panel (2) includes green LEDs (2a), red LEDs (2b), and blue LEDs (2c). However, the number of LEDs of the same color for the same area is reduced to one-third, producing an image with one-third the number of full-color pixels in each area compared to a single-color panel as in FIG. 2a. For example, if the LED array shown in FIG. 2a forms an image of 1920 pixels in the horizontal direction (i.e., 1920 LEDs in this area), the number of pixels in FIG. 3a is reduced to 640. This reduces the achievable resolution size when a full-color image is required.

[0051] This illustrates the problem of using LEDs as a projector image source for full-color images while maintaining display resolution without significantly increasing the system size.

[0052] The objective of the present invention is to overcome these problems and provide a projector capable of generating full-color images without compromising the size of the system or the resolution achieved.

[0053] FIG. 4 is a schematic diagram of a downward view of a projector (1) according to one embodiment of the present invention. The projector (1) is shown projecting an image onto a waveguide (101). The image is viewed by a user (201).

[0054] The projector (1) includes an LED panel (2). A collector array (6) is located next to the LED panel (2). Between the collector array (6) and the waveguide (101), there is a projector unit including a projector lens (8).

[0055] The LED panel (2) generates light that serves as both an image source and a light source. Light from the LED is collected by the collector (6) to reduce the angle at which light is emitted from the LED in order to solve the aforementioned Lambertian emission problem. The light from the collector (6) is received by the projector lens (8). The projector lens (8) collimates the light to convert the position (spatial) image into an angle image. Each pixel of the image generated by the LED panel (2) has a spatial position. After the projector lens (8), where the position image is converted into an angle image, each pixel is indicated by an angle (azimuth and elevation).

[0056] The image is projected onto the input grid of the waveguide (101). Light is projected onto the output grid, which is seen as an image to the eyes of the user (201), below the waveguide (101) exiting the waveguide (101).

[0057] FIG. 5a is a front view of the LED panel (2) and collector array (6) of the projector (1) illustrated in FIG. 4. As illustrated, the LED panel (2) includes a green LED (2a), a red LED (2b), and a blue LED (2c). The LEDs can be considered to be arranged in elements (10), each element (10) including a red LED (2b), a green LED (2a), and a blue LED (2c). As illustrated, the LEDs (2) of each element (10) are arranged diagonally. However, in other embodiments, they may be arranged equally in a horizontal or vertical arrangement. The LED (2) array can be effectively considered as the same arrangement of green LEDs (2a) as illustrated in FIG. 2a, with additional red (2b) and blue (2c) LEDs located in the unused space between each green LED (2a). This allows for more efficient use of space because the three colors of LEDs can be placed within the same area, as shown in the layout of Fig. 2a.

[0058] Each collector structure (6) can collect light only from the LED located directly below it. The LED panel (2) is movable relative to the collector (6) as indicated by the arrows (20a, 20b) in FIG. 4. In this way, each LED (2) of the element (10) can be sequentially positioned below the associated collector (6) so that light from each LED (2) is collected by the collector (6). This is illustrated in more detail in FIG. 5a through 5c.

[0059] In FIG. 5a, the green LED (2a) is positioned below the collector (6) so that the collector (6) collects light only from the green LED (2a) to form a green subframe image.

[0060] In FIG. 5b, the LED panel (2) is moved so that the blue LED (2c) is positioned below the collector (6), and in this position, light from only the blue LED (2c) is collected to form a blue subframe image.

[0061] In FIG. 5c, the LED panel (2) is moved so that only the red LED (2b) is positioned below the collector (6), so that light from only the red LED (2b) is collected to form a red subframe image.

[0062] The movement of the LED panel between each position shown in FIGS. 5a to 5c can occur at the frame rate or faster. Thus, each position 5a to 5c serves to generate a monochrome subframe. As shown in FIG. 5d, each subframe is combined to generate a full-color frame. The number of pixels in the full-color frame is equal to the number of collectors (6). Therefore, there is no loss of resolution when generating a full-color image.

[0063] FIG. 6 is a schematic plan view of a projector (1) according to another exemplary embodiment of the present invention. The projector (1) is shown to project an image onto a waveguide (101) that is sequentially viewed by a user (201).

[0064] The projector (1) illustrated in FIG. 6 includes an LED panel (2), a collector array (6), and a projector lens (8) similar to the projector illustrated in FIG. 4. Additionally, the projector (1) includes a beam angle shifter (12) arranged between the projector lens (8) and a waveguide. In the projector (1) illustrated in FIG. 6, the LED panel (2) cannot move relative to the collector array (6), unlike in the embodiment illustrated in FIG. 4.

[0065] FIG. 7 is a front view of the LED panel (2) and collector array (6) of the projector (1) shown in FIG. 6. The LED panel (2) includes a green LED (2a), a red LED (2b), and a blue LED (2c). The LEDs are arranged alternately so that two LEDs of the same color are not arranged next to each other in the x and y directions. As can be seen in FIG. 7, the green LED (2a), red LED (2b), and blue LED (2c) in each row can be considered as elements (10). However, the classification of these elements can be done in the same way by looking at the columns rather than the rows.

[0066] In the projector (1) of the embodiment shown in FIGS. 6 and 7, each LED has a corresponding collector (6), and each collector (6) always collects light from the same LED (2).

[0067] The light angle shifter (12) can cause the light emitted from each LED to be shifted after passing through the collector (6) and the projector lens (8). As shown in FIG. 8a, the light from each color LED is shifted so that each pixel of the image formed by the projector is illuminated by the light from each color LED. In each subframe, a different color LED illuminates each pixel. This provides a full-color image as shown in FIG. 8b, having a pixel density equal to the number of collectors (and the number of LEDs). Thus, instead of the 640x640 resolution achieved without displacement, the resolution is increased to 1920x1920.

[0068] FIG. 9 is a schematic diagram of an exemplary method of combining pixels of different colors using the projector of FIG. 6. A subframe (15a) is formed of a plurality of pixels (22) each illuminated by different colored LEDs.

[0069] A subframe (15b) is formed by the angle shifting of light from each LED, so that a light angle shifter moves the light from each LED horizontally by a pixel. This can be achieved through yaw rotation. The LEDs are arranged on the panel in the order of green, red, and blue, shifting the subframe by 1 pixel so that the pixel previously illuminated by the first color is then illuminated by another second color LED. In the final third subframe (15c), the light is further angled so that the image is moved horizontally by an additional pixel, so that the final color of the three colors illuminates each pixel. This creates a whole white image frame as shown in FIG. 8b, having a number of pixels equal to the number of collectors (and LEDs).

[0070] As shown in Fig. 9, since two rows of pixels on both sides are not illuminated by the three colors of the LED, the resolution of the image does not exactly match the resolution of the number of LEDs. However, when forming an image of 1920 pixels, these four redundant rows of pixels have a negligible effect.

[0071] The angular movement between each subframe (15a, 15b, 15c) can occur at three times the frame rate so that each subframe (15a, 15b, 15c) is formed during one-third of the time each frame is displayed.

[0072] As each subframe (15a, 15b, 15c) is shifted by 1 pixel relative to each other, each LED emits light for the pixel being illuminated. For example, looking at the first green LED (2a) in frame (15a), it may emit light representing the first top-left pixel of the original image to be projected. In frame (15b), the green LED (2a) may emit light representing one pixel in the top-left of the original image to be projected, and in subframe (15c), the green LED (2a) may emit light representing two pixels in the top-left of the original image to be projected. This causes each pixel of the final image to represent a single pixel of the original image to be projected.

[0073] In the projector illustrated in FIG. 6, the beam angle shifter (12) is a mirror configured to move its position. Light from the collector is reflected from the mirror by different amounts depending on the direction of the mirror, causing a displacement of the light.

[0074] When the mirror is in the first position, the mirror does not cause the movement of light so that each collector (and its associated LED) forms pixels of the image as shown in the subframe (15a). When the mirror moves in the second direction, the subframe (15b) is formed, and finally, when the mirror moves toward the third position, the third subframe (15c) is formed. Reflection of light from the mirror along that direction causes an angular displacement of the light.

[0075] FIG. 10 is a schematic plan view of a projector (1) according to another exemplary embodiment of the present invention. The projector (1) is shown to project an image onto a waveguide (101) that is sequentially viewed by a user (201).

[0076] The projector (1) illustrated in FIG. 10 includes an LED panel (2), a collector array (6), a projector lens (8), and a beam angle shifter (12), similar to the projector illustrated in FIG. 6. In the projector (1) illustrated in FIG. 10, unlike the projector (1) illustrated in FIG. 6, the collector array (6) is movable and the LED panel (2) is static.

[0077] FIG. 11a is a front view of the LED array (2) of the projection display (1) illustrated in FIG. 10. As illustrated, the LED array contains LEDs of different colors. In the example illustrated in FIG. 3a, the LEDs are red, green, and blue. The LEDs are arranged in elements (10), and each element consists of a 2x2 square array of LEDs as illustrated in the dotted rectangle (10). Each element (10) includes two red LEDs (2b, 2d), one green LED (2a), and one blue LED (2c). The elements (10) are repeated across the LED array. The LEDs in this direction are densely packed so that there is no space between adjacent LEDs. With such a densely packed LED array, a collector cannot be placed across all the LEDs at once.

[0078] FIG. 11b is a front view of an array of collectors (6). In this embodiment, additional details of the collectors (6) are shown to indicate that the collectors have a tapered well structure.

[0079] FIGS. 12a and 12b illustrate a slice along the first row of LEDs as shown in FIG. 2a so that only the red (2d) and green (2a) LEDs are visible. The structure of the tapered well structure (6) is illustrated. For the embodiments illustrated in FIGS. 4 and 6, although these details are not illustrated, the collector (6) of these embodiments may also be a tapered well structure.

[0080] As illustrated in FIGS. 12a and 12b, each tapered well structure (6) includes a conduit (17) located between an inlet (14) at an end proximal to the LED and an outlet (16) at an end distal to the LED. Each tapered well structure includes four walls (18a, 18b, 18c, 18d) forming the structure of the tapered well structure (6). The walls of the tapered well structure are tapered so that the cross-sectional area of ​​the outlet (16) is larger than the cross-sectional area of ​​the inlet (14). This reduces the emission angle while increasing the area through which light is transmitted, and allows light to be collected from the LED array. The walls (18a to 18d) of the tapered well structure are formed of glass and serve to receive light within the conduit (17) of the tapered well structure (6).

[0081] As described above, in the embodiment illustrated in FIG. 10, the collector (tapered well structure) is movable relative to the LED array. This is illustrated in FIG. 12a, FIG. 12b and FIG. 13a through 13d. As in other embodiments, each collector may collect light from only a single LED at any given time. The reason for this is illustrated in FIG. 12a and FIG. 12b. In FIG. 12a, the tapered well structure (6) is positioned to collect light from the green LED (2a). In this configuration, the inlet (14) of the tapered well structure (6) is positioned over the green LED (2a), so that the green light is collected by the tapered well structure (6). By reflecting the green light from the wall (18) of the tapered well structure (6), the green light is contained within the tapered well structure. The angle of light emitted from the LED decreases, while the area of ​​light emission increases due to the tapering characteristic of the well structure. In this arrangement, the walls of the tapered well structure are positioned over the red LED (2d) and other red and blue LEDs (2b, 2c) not shown in this drawing so that light is not collected from these LEDs. FIG. 12b shows a different orientation of the tapered well structure (6) relative to the LEDs, and the tapered well structure (6) is positioned to collect light from the red LED (2d). In this configuration, the inlet (14) of the tapered well structure (6) collects light from the red LED (2d), while light from the other LEDs (2a, 2b, 2c) is blocked by the walls (18) of the tapered well structure.

[0082] FIGS. 13a through 13d are front views of different positions of the tapered well structure (6) for the LED array (2). In FIG. 13a, the collector is positioned over the green LED (2a), so that each collector is illuminated by the light from the green LED (2a) of the associated element (10). This is as shown in FIG. 12a. In FIG. 13b, the collector array moves along the plane in the +x direction so that they are positioned over the red LED (12b), so that the red LED (12b) of each element (10) illuminates the collector. In FIG. 13c, the collector array moves along the plane in the -y direction so that they are positioned over the blue LED (12c), so that the blue LED (12c) of each element (10) illuminates the collector. In FIG. 13d, the collector array moves along the plane in the -x direction so that they are positioned over the red LED (12d), so that the red LED (12d) of each element (10) illuminates the collector. This process is then repeated for the next image frame.

[0083] If the pitch of the LEDs (distance between the centers of two adjacent LEDs) is 3 μm in both the x and y directions, the pitch between the collectors can be 6 μm. Accordingly, the movement of the collectors can be 3 μm in both the x and y directions to achieve the movement as shown in FIGS. 13a to 13d.

[0084] The movement between each position shown in FIGS. 13a through 13d is faster than the frame rate. In fact, the movement speed is four times the frame rate to ensure that the collector is at each position shown in FIGS. 13a through 13d for each frame.

[0085] As illustrated in FIG. 14, when the collector is positioned in the location shown in FIG. 13a to collect light from the green LED, the light angle shifter increases the resolution of the resulting green subframe formed by causing an angular displacement of the light from the collector. Therefore, instead of forming an image of 540 pixels in each direction as in the case where, for example, there is no light angle shifter, the resolution of the image is increased to 1080 pixels, which is equal to the number of LEDs in the LED array (2). This is illustrated as a green subframe (30a).

[0086] Four subframes are generated as shown in FIG. 15 by using a ray angle shifter to induce an angular shift for each of the positions shown in FIG. 13a through 13d. Subframe (30a) is a green subframe as shown in FIG. 14. Subframe (30b) is a red subframe formed when the collector (6) is at the position shown in FIG. 13b. Subframe (30c) is a blue subframe formed when the collector (6) is at the position shown in FIG. 13c. Subframe (30d) is a red subframe formed when the collector is at the position shown in FIG. 13d. Each of these subframes is combined together to form a full-color frame (32). Since each of the subframes (30a through 30d) and the full-color frame (32) is 1080x1080 pixels, there is no loss of resolution.

[0087] Further details regarding how the angle shifter enables an increase in resolution may soon be explained in connection with FIGS. 16a through 16e. FIG. 16a illustrates three pixels formed by light emitted from three collectors (6). For example, these could be the first of the three collectors in the top row, in the position emitting the green light shown in FIGS. 13a and FIGS. 14. The three pixels are labeled 33a, 33b, and 33c. As mentioned above, due to the fact that the LED array is 2x2 and only one of the 2x2 LEDs is collected, the resolution of this subframe, in both horizontal and vertical dimensions, is 540 pixels, not the required 1080 pixels.

[0088] The LED can be controlled by a signal processor (not shown) that provides a signal to control the LED to form an image. In the array shown in FIG. 16a, the image to be initially projected is reduced to 540x540 pixels, with each projected pixel representing the average value of four pixels of the original image. For example, pixel (33a) is the average of four pixels of the original image, pixel (33b) is the average of four pixels of the original image, and pixel (33c) is the average of four pixels of the original image.

[0089] The light angle shifter (12) causes the projected light to shift by 1 / 2 pixel as shown in FIG. 16b, so that the light is projected to form three pixels (33a, 33b, 33c) that are angle-shifted by 1 / 2 pixel relative to the pixel in FIG. 16a. The dashed line indicates the position of the light in the previous projection. When projecting from the position in FIG. 16b, the LED is controlled by a signal processor to project a second reduced image of 540x540 pixels based on the original image shifted by 1 pixel. In this way, the pixel (33a) in FIG. 16b is the average of four pixels of the original image, but starts at 1 pixel, that is, starts in the second column of pixels of the original image. The other pixels (33b and 33c) are also shifted correspondingly.

[0090] A light angle shifter causes a shift of light by 1 / 2 pixel as shown in FIG. 16c, so that light is projected to form three pixels (33a, 33b, 33c) that are angle-shifted downward by 1 / 2 pixel relative to the pixel in FIG. 16b. When projecting from the position in FIG. 16b, the LED is controlled by a signal processor to project a third reduced image of 540x540 pixels based on the original image shifted by 1 pixel and 1 pixel downward. In this way, the pixel (33a) in FIG. 16c is the average of four pixels of the original image, but starts at 1 pixel and 1 pixel downward, that is, starts at the second column and second row of the pixels of the original image. The other pixels (33b and 33c) are also shifted correspondingly.

[0091] As shown in FIG. 16d, the beam angle shifter causes a shift of light by 1 / 2 pixel, so that light is projected to form three pixels (33a, 33b, 33c) that are angle-shifted relative to the pixel in FIG. 16c. When projecting at the position in FIG. 16c, the LED is controlled by a signal processor to project a fourth reduced image of 540x540 pixels based on the original image shifted down by 1 pixel. In this way, the pixel (33a) in FIG. 16d is the average of the four pixels of the original image, but starts 1 pixel lower, that is, starts at the second row of pixels of the original image. The other pixels (33b and 33c) are also shifted correspondingly.

[0092] FIG. 16e is a part of the image generated from these movements as shown in FIG. 16a through 16d. As can be seen from this combination of different positional movements, the number of pixels (35a, 35b) in the image increases significantly. By performing each of these movements for each of the positions shown in FIG. 13a through 13d, each frame (30a, 30b, 30c, and 30d) is formed to have a resolution of 1080 on both axes, forming a full-color 1080 frame (32). Performing this operation for each image frame increases the resolution from 540x540 to 1080x1080, allowing a full-color image to be formed with this increased resolution.

[0093] As described above, the movement of pixels as illustrated in FIGS. 16a through 16d is performed by a beam angle shifter that causes an angular movement of the pixels. In other embodiments, the effect described in FIGS. 16a through 16d can be achieved through spatial movement of light instead of angle. Instead of including a beam angle shifter, the effect can be produced by using the movement of the LED (2) and collector (6) arrays, which is added to the relative movement of the collector to the LEDs as illustrated in FIGS. 10 and FIGS. 13a through 13d. For example, the LED (2) array and the collector (6) array can be mounted with a mechanism that allows all movement relative to the projector lens (8) in a plane along the x and y directions. The movement is equivalent to moving 1 / 2 pixel in the +x direction (i.e., 1 / 2 of the collimator size), 1 / 2 pixel down in the -y direction, 1 / 2 pixel across the -x direction, and finally back up to the original position (1 / 2 pixel in the +y direction) as shown in FIGS. 16a through 16d. In this way, pixels as shown in FIGS. 16a through 16d are formed. With these movements performed when the collector is at each of the positions shown in FIGS. 13a through 13d, the full-color frame (32) shown in FIG. 15 can be formed.

[0094] The LEDs shown in all the embodiments described above may be micro LEDs. This is particularly preferred in pico projector designs due to the small size of micro LEDs. Each typical micro LED is 0.04 mm 2 It can have an area of ​​less than that. However, in other arrangements, the LEDs can be standard-sized LEDs depending on the projector use.

[0095] In the above description, the term "frame" is used to refer to an image, that is, a frame of an image formed by a projector. A frame may consist of a set of subframes that are displayed rapidly and continuously so that the frame appears as a static image to the viewer. The frame may be updated at a time, generally known as the frame rate. For example, the projector may operate the frame display at a frame rate of 60 Hz. Thus, in the above embodiment with three subframes, it may be displayed at 180 Hz. In the embodiment illustrated in FIG. 4, the movement of the LED may be 180 Hz. In the embodiment illustrated in FIG. 6, the movement between each subframe (15, 15b, 15c) of FIG. 9 may be 180 Hz. In the embodiment illustrated in FIG. 10, the movement of the collector between each position may be 240 Hz (since there are four positions). The movement of light between the positions illustrated in FIG. 16a through 16d may be 960 Hz. The above is based on a frame rate of 60Hz, and other frame rates may be used.

[0096] Since the embodiments of the present invention have been described in detail, it will be apparent that modifications and variations are possible without departing from the scope of the embodiments of the present invention as defined in the appended claims.

[0097] In the above description regarding FIG. 9, the subframe is shown as being formed by shifting one pixel in the horizontal direction. Alternatively, the shift may be in the vertical direction, which produces a similar result. The shift may vary depending on the size and orientation of the elements and their respective LEDs.

[0098] The resolutions described above are not limited and are merely examples. For instance, in the case where it is described that the resolution has increased from 640x640 to 1920x1920, it can be understood that the original frame may have any resolution and the associated increase may be made.

[0099] The collector of the above-described embodiment is described as having a tapered well structure. Alternatively, the collector array may be a microlens array. Microlenses can provide the same effect as a tapered well structure by reducing the angle at which light is collected and emitted from the LED. Thus, the Lambertian emission problem can be solved. In other configurations, the projector of the above embodiment may include both a microlens array and a tapered well structure array.

[0100] The colors of the LEDs shown in the above embodiments are RGB. However, the present invention is not limited thereto, and any combination of LED colors may be used. For example, the LEDs may be red, blue, and yellow. Or, the 2x2 array in FIG. 11a may be green, red, blue, and white LEDs.

[0101] Additionally, each element does not place any limitations on the color and number of LEDs displayed. For example, the embodiment illustrated in FIG. 10 may be equally valid for elements other than 2x2. For example, the element may be a 3x1 array of LEDs such as RGB. In such an array, the collector only needs to move in one direction in the plane, for example, only in the x-direction. Additionally, the position ranges shown in FIG. 16a and 16b will be adjusted so that full resolution can be achieved.

[0102] In the illustrated embodiments, the displacement of light may be achieved using an angle shifter, such as a movable mirror, as described in relation to FIG. 6 and FIG. 10, or it may be a spatial displacement of light, such as through the movement of the collector and LED array, as described in relation to FIG. 10, without a beam angle shifter. However, as another alternative, the displacement may be provided by an angle-shifting moving plate. For example, a nutating plate may be placed behind the collector array in front of the projector unit. The nutation of the plate, through tilting in different directions, may provide movement of light instead of the beam angle shifter or the movement of the LED and collector beams after the projector lens. Alternatively, an oscillating glass wedge may be used to provide apparent optical movement. Light may enter the glass wedge and be refracted to cause the light to undergo optical movement. Through the movement of this wedge, the light may be moved in the manner described for the above embodiments to provide the same desired effect. Any mechanism that induces the movement of light in different arrays can be used.

[0103] In the embodiment illustrated in FIG. 4, the LED panel can move while the collector is in a static state. In other arrangements, the collector may be movable and the LED panel may be in a static state. However, this may require a ray angle shifter or a similar mechanism to allow the subframes formed by the moving collector to overlap each other to form an image.

[0104] The arrangement illustrated and described in connection with FIGS. 16a through 16d is one example. Movement may be made in any way. Also, the sampling of the displayed images is not limited to the described manner.

[0105] In the above embodiment, the projector is illustrated as projecting an image onto a waveguide. However, the projector can be used to project light onto any type of device and any type of display and is not necessarily limited to a waveguide.

Claims

Claim 1 A projector for generating an image frame comprises: an element array arranged in a plane, wherein each element comprises at least three LEDs having different colors; a collector structure array, wherein each collector structure is configured to receive light from a single LED at any time and reduce the angle at which the LED emits light; and a projector unit configured to receive the light from the collector structure array and collimate the light to form a frame, wherein the frame is full color and is formed by combining a plurality of subframes, each subframe is a single color, and the plurality of subframes are formed through spatial movement of the element array relative to the collector structure array, wherein each collector structure receives light from a different LED during each subframe, and one of the element arrays is configured to be movable to provide spatial movement of the element array relative to the collector structure array, or the collector structure array is configured to be movable to provide spatial movement of the element array relative to the collector structure array. Claim 2 A projector according to claim 1, wherein the projector unit comprises an optical element configured to induce a displacement of light emitted from each LED so that the light from each LED illuminates a plurality of pixels of the frame. Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 A projector according to either claim 1 or claim 2, wherein the collector structure array is a micro-lens array or a tapered well structure array. Claim 9 A projector according to either claim 1 or 2, wherein the at least three LEDs include a red LED, a blue LED, and a green LED. Claim 10 A projector according to either claim 1 or claim 2, wherein each element includes four LEDs, said LEDs are arranged in a 2x2 configuration in the plane. Claim 11 A projector according to either claim 1 or 2, wherein in a first subframe, a first LED among at least three LEDs illuminates a first pixel, in a second subframe, a second LED among at least three LEDs illuminates the first pixel, and in a third subframe, a third LED among at least three LEDs illuminates the first pixel. Claim 12 A projector, wherein, in either one of paragraphs 1 and 2, the LED is a micro LED. Claim 13 A wearable device comprising a projector according to either claim 1 or claim 2. Claim 14 A projector display system comprising: a display for displaying an image; and said projector according to any one of claims 1 and 2. Claim 15 A method for generating an image frame using a projector comprises: a step of emitting light from an array of elements arranged in a plane, wherein each element comprises at least three LEDs having different colors; a step of receiving the light emitted from the array of elements in a collector structure array, wherein each collector structure receives light from a single LED at any given time to reduce the angle at which the LED emits light; a step of emitting the light from the collector structure array with the reduced angle; and a step of receiving the light from the collector structure array and collimating the light at a projector unit to form a frame; wherein the frame is full color and is formed by combining a plurality of subframes, each subframe is a single color, and the plurality of subframes are formed through spatial displacement of the array of elements relative to the collector structure array, wherein each collector structure receives light from a different LED during each subframe, and one of the arrays of elements is moved to provide spatial displacement of the array of elements relative to the collector structure array, or the collector structure array is the element relative to the collector structure array A generation method that is moved to provide spatial movement of an array.

Images