Patent Publication Number: US-2023134188-A1

Title: Apparatus and method for a vision system having a borderless chip design

Description:
BACKGROUND 
     Night vision (NV) systems allow users to see in low-light environments without flooding the environment with visible light. Accordingly, NV systems can be used for covert vision in low-light environments. By enabling sight without illumination in the visible or other spectra, NV systems protect users from being detected. 
     Analog NV systems function by receiving low levels of light and intensifying the received light using an image intensifier. The image intensifier has a photocathode that emits electrons in response to incident photons. The emitted electrons are accelerated through a vacuum tube and directed towards a microchannel plate that amplifies the signal by multiplying the number of electrons. The multiplied electrons then strike a phosphor screen, and, via the phenomenon of luminescence, the phosphor screen emits photons in response to radiant energy (e.g., the electrons). The luminescent light from the phosphor screen is coupled through a series of optics to the user. For example, the luminescent light may be coupled through an inverting fiber optic to an eyepiece where the user can view the illuminated phosphor screen, thus allowing the user to see the objects. 
     Analog NV systems can include an overlay display that transmits a direct-view, intensified image through the overlay display and emits display light representing a display image from the overlay display to thereby generate a combined image with the display image superimposed over the direct-view, intensified image. The overlay display can be used to convey various information to the user, such as temperatures, distances, indicators marking objects, situational awareness messages, messages from other users, etc. 
     A challenge of adding an overlay display to analog NV systems is that the overlay display can increase the size, weight, and power of the analog NV systems. Accordingly, improved analog NV systems and overlay displays are desired to minimize the increase in size, weight, and/or power. 
     The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced. 
     BRIEF SUMMARY 
     One embodiment illustrated herein includes an optical device that includes a semiconductor chip having a first surface that receives direct-view light and transmits the direct-view light through transparent regions. The optical device further includes a plurality of electro-optical circuits formed on the semiconductor chip. The plurality of electro-optical circuits formed on the semiconductor chip, the plurality of electro-optical circuits comprising light emitters spanning an active area that extends to one or more edges of the semiconductor chip, the light emitters configured to output display light, and the transparent regions being arranged between the respective light emitters. 
     Another embodiment illustrated herein is a method of processing light in an intensifier module. The method includes receiving, at an intensifier, light from an environment and generating intensified light representing an intensified image of the environment. The method further includes transmitting the intensified light through a transparent overlay display. The method further includes emitting display light from the transparent overlay display, the display light superimposing a display image over the intensified image. The transparent overlay display includes a semiconductor chip having a first surface that receives intensified light and transmits the intensified light through the transparent regions of the optical device. The transparent overlay display further includes a plurality of electro-optical circuits formed on the semiconductor chip, the plurality of electro-optical circuits comprising light emitters spanning an active area that extends to one or more edges of the semiconductor chip, the light emitters configured to output the display light, and the transparent regions being arranged between the respective light emitters of the light emitters. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     Additional features and advantages will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the teachings herein. Features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the manner in which the above-recited and other advantages and features can be obtained, a more particular description of the subject matter briefly described above will be rendered by reference to specific embodiments which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments and are not therefore to be considered to be limiting in scope, embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG.  1 A  illustrates a perspective view of a night vision (NV) system, according to one embodiment; 
         FIG.  1 B  illustrates a side cutaway view of the NV system, according to one embodiment; 
         FIG.  2    illustrates a schematic diagram of an intensifier module of the NV system, according to one embodiment; 
         FIG.  3    illustrates an NV scene image with heads-up display functionality, according to one embodiment. 
         FIG.  4 A  illustrates a chip layout of an overlay display having a bordered configuration, according to one embodiment; 
         FIG.  4 B  illustrates a chip layout of an overlay display having a borderless configuration, according to one embodiment; 
         FIG.  5 A  illustrates a diagram of a portion of an overlay display having a single planar circuit configuration, according to one embodiment; 
         FIG.  5 B  illustrates a diagram of a portion of an overlay display having a two plane circuit configuration, according to one embodiment; 
         FIG.  6    illustrates a top-down view of a portion of an overlay display, according to one embodiment; 
         FIG.  7 A  illustrates a schematic diagram of an intensifier module having a partially overlapping overlay display with a bordered configuration, according to one embodiment; 
         FIG.  7 B  illustrates a schematic diagram of an intensifier module having a partially overlapping overlay display that is superimposed over the intensified light using a beam splitter, according to one embodiment; 
         FIG.  7 C  illustrates a schematic diagram of an intensifier module having a partially overlapping overlay display with a borderless configuration, according to one embodiment; and 
         FIG.  8    illustrates a diagram of a portion of an overlay display having photodetectors, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     As discussed above, the improved functionality of incorporating an overlay display into the intensifier module of an analog night vision (NV) system comes at the expense of increased size, weight and power. However, the embodiments disclosed herein have the advantage of minimizing this increase in the size, weight, and/or power due to the overlay display being integrated with the analog NV system. 
     Size, weight, and power are each important parameters in image intensifier systems. For example, greater weight can increase the torque that a head-mounted NV system applies the human neck, potentially causing lasting damage through prolonged use. Keeping NV systems small and compact while simultaneously providing overlay display functionality presents challenges given the size of conventional displays and beam combiners that required in order to span a large portion (or all) of the cross-sectional of an intensified image. One challenge is that, for conventional displays and beam combiners, the large size of the beam combiner or display can necessitate a larger housing to hold those components. 
     Accordingly, the embodiments disclosed herein provide overlay display configurations having reduced size relative to other configurations (e.g., configurations using beam splitters). For example, the size of the display chip can be decreased by using a borderless display configuration. The borderless display configuration may be realized by changing the location of the addressing and readout circuitry from the border of the chip to within the active area of the display. This change in location may be realized, e.g., by adding a semiconductor circuit layer below the opaque/non-transparent regions for pixels of the overlay display. Additionally, borderless display configuration may be realized by routing communication lines to the bond pads using metallization layers below the inter-pixel top metal row/column lines. A third technique reduces the display chip size by using data-handling circuitry integrated below the active area of the chip (e.g., the opaque regions corresponding to pixels). Alternatively or additionally, a circuit configuration can be used in which some (or all) of the data-handling circuitry are coplanar with the display control circuitry driving the pixels of the overlay display. This coplanar configuration may be realized by decreasing the pixel density to allow for additional area at the respective pixels (e.g., opaque regions) that can be used for readout circuitry and other data-handling circuitry. 
     As discussed below, the driving circuitry for the pixels of the overlay display attenuates or blocks the direct-view, intensified light. For example, the active silicon and metallization layer(s) that are used to fabricate transistors (e.g., CMOS transistors) and other circuit elements attenuate light in the direct-view, intensified light (also abbreviated as “intensified light”). Additionally, the metallization layer(s) used to fabricate interconnect lines also attenuate the intensified light. These regions in which the intensified light is attenuated or blocked are generally referred to as opaque regions. Fabricating additional circuit elements or metal lines above or below the opaque regions does not degrade the intensified image because the additional circuit elements or metal lines only attenuate those rays of the intensified light that would be attenuated by the opaque regions. Here, the phrase “above or below the opaque regions” means that, with respect to optical paths of rays of the intensified light, the additional circuit elements lie in the same optical path(s) as opaque regions. 
     Additionally, the active silicon can be arranged above or below the interconnect lines because both the active silicon and the interconnect lines represent opaque regions. That is, any type of opaque region may be arranged above or below any other type of opaque region because either type of opaque region obscures or attenuates those rays of the intensified light passing through the opaque region. 
     Referring now to  FIGS.  1 A and  1 B , a non-limiting example of a NV system is illustrated. In particular,  FIGS.  1 A and  1 B  illustrate a PVS-14 NV system  100 . In the example illustrated, the NV system  100  includes a housing  124 . As will be illustrated in more detail below in other figures, the housing  124  houses an image intensifier module  112 . The NV system  100  further includes an objective  102  which receives light reflected and/or generated in an environment. The objective  102  includes optics such as lenses, waveguides, and/or other optical components for receiving and transmitting light to the image intensifier module  112 . The NV system  100  further includes an eyepiece  122 . The eyepiece  122  includes optics for focusing images created by the NV system  100  into the eye of the user. 
       FIG.  2    illustrates the image intensifier module  112 , according to one example. The image intensifier module  112  includes an image intensifier  204  without an overlay display. The light from the image intensifier module  112  is captured by the eyepiece  122  and directed to the user. 
     The image intensifier module  112  receives the input light  202 , which has been transmitted through the objective  102  to the image intensifier module  112 . The input light  202  may be, for example, dim light from a nighttime environment that would be challenging to see with the naked eye. 
     The objective directs the input light  202  into the image intensifier  204 . The image intensifier  204  may include functionality for amplifying the received image so that the image that can be viewed by the user. In the illustrated embodiment, this amplification is accomplished using a photocathode  206 , a microchannel plate  210 , and a phosphor screen  212 . The photocathode  206  absorbs incident photons and outputs electrons in response. The electrons may pass through an optional ion barrier film  208 . Electrons from the photocathode  206  are transmitted to the microchannel plate  210 , which multiplies the number of electrons. The multiplied electrons then strike a phosphor screen  212 , which absorbs the energy from electrons generating photons in response. The phosphor screen  212  converts the radiant energy of the multiplied electrons to luminescent light via the phenomenon of luminescence. Accordingly, the phosphor screen  212  glows due to electrons from the microchannel plate  210  striking the phosphor screen  212 , creating an intensified image that represents the image of the input light  202 . A fiber-optic element  214  carries the intensified light  216  (with the intensified image) to the eyepiece  112 . 
     The analog NV system  100  is a direct-view imager. The analog NV system  100  generates an image directly from the input light  202  without an intervening step of the image being based on a detected/digitized image as performed in digital NV system. In contrast to the direct-view intensified image representing an intensified version of the input light  202 , the overlay display  218  generates a display image which is discussed below. 
     The overlay display  218  generates display light  220 , which is superimposed with the intensified light  216 . For example, the overlay display  218  may include functionality for displaying information to a user. Such information may include graphical content, including text, images, superimposed thermal image data and the like.  FIG.  3   , which is discussed below, illustrates an example of an image in which an overlay display  218  superimposes text, symbols, and other information over an intensified image that includes trees and clouds. Additional details regarding certain embodiments of the NV system  100  and the overlay display  218  are provided in U.S. patent application Ser. No. 16/868,306, filed on May 6, 2020, titled “Backside Etch Process for Transparent Silicon Oxide Technology”, which is incorporated herein by reference in its entirety. 
       FIG.  3    illustrates an example of an image in which an overlay display  218  superimposes text and other graphical symbols over an amplified image of a nightscape that includes trees and clouds. As discussed above, the overlay display  218  may include functionality for displaying information to a user. Such information may include graphical content, including text, images, superimposed thermal image data and the like. The overlay display  218  outputs display light  220  which can be sent to the eyepiece. Thus, an image such as that illustrated in  FIG.  3    is presented to the user in the NV system  100 . 
       FIGS.  4 A and  4 B  illustrate top-down views of respective layouts for the overlay display  218 . In both  FIGS.  4 A and  4 B , the overlay display  218  is fabricated on a semiconductor chip  300 , and the overlay display  218  includes an active area  370  and data-handling circuitry, including, e.g., an image data pipeline  322 , an analog reference block  324 , a global configuration  326 , a display data pipeline  328 , a column driver  354 , and a line driver  356 . In  FIG.  4 B , the layout for the overlay display  218  has the data-handling circuitry within the active area  370 . In  FIG.  4 A , the data-handling circuitry is outside the active area  370 . Inside the active area  370 , transparent regions are arranged between pixels, and the transparent regions transmit the intensified light  216 , as discussed below with reference to  FIGS.  5 A and  5 B . In contrast, outside the active area  370 , the chip is opaque to the intensified light  216 . 
     An advantage of having some (or all) of the data-handling circuitry within the active area, as illustrated in  FIG.  4 B , is that the active area  370  occupies a larger percentage of the total area of the semiconductor chip  300 . Thus, the semiconductor chip  300  can be smaller because it does not require a large boundary region in which to fabricate additionally circuitry. Because the semiconductor chip  300  is smaller, a smaller housing can be used for an intensifier module that includes a borderless display. 
     Additionally, on one or more edges of the semiconductor chip  300 , the active area  370  may extend all the way to the border/periphery of the semiconductor chip  300 . For example,  FIG.  4 B  illustrates the active area  370  extending to the border/periphery on three edges of the semiconductor chip  300 . The data-handling circuitry can be arranged within the active area  370  by fabricating the data-handling circuitry below or above the display control circuitry, for example. 
     Additionally, in certain embodiments, the display control circuitry does not consume all the available area in the given fabrication layers in which the display control circuitry is fabricated. For example, the fabrication layers can have opaque regions and transparent regions, as discussed below with reference to  FIG.  6   . The display control circuitry may occupy only part of the opaque region within a given fabrication layer and the remaining part of the opaque region within the given fabrication layer may be used to fabricate some (or all) of the data-handling circuitry. 
       FIG.  5 A  illustrates a cross-section of a part of the overlay display  218 . In certain non-limiting embodiments, the overlay display  218  may include active silicon areas, which are illustrated as active silicon islands  450  (e.g., native silicon islands). The active silicon islands  450  can be used to fabricate transistors, such as MOSFETs by doping the silicon (Si) with spatially varying concentrations of donor and acceptor atoms. Further, the MOSFETs may be fabricated using intermetal and dielectric layers  464  that include insulators (e.g., oxides and dielectrics) and metal traces  456 . In certain embodiments, the MOSFETs may provide (but are not limited to providing) logic functions and/or control functions (e.g., to control turning on/off the LEDs in the emitter stack  454 ). 
     In the example illustrated in  FIG.  5 A , each of the active silicon islands represents a pixel of the overlay display  218 . Thus, by powering various emitters  472  in the emitter stack  454  using the transistors in the active silicon islands, a display image can be created by the overlay display  218  and output to a user. In certain embodiments, the emitters  472  can be organic light emitting diodes (OLEDs). A display image is generated by outputting the display light  220 . In  FIG.  5 A , the intensified light  216  enters the overlay display  218  from the bottom, passes through the oxide  460  and then through the other layers before exiting the overlay display  218  through the cover glass  466 . The display light  220  is generated in the emitter  472  and, like the intensified light  216 , the display light  220  exits through the cover glass  466 . After exiting through the cover glass, both the display light  220  and the intensified light  216  are transmitted to the eyepiece  122  of the NV system  100 , and then to the user. 
     Whereas the pixels (i.e., Si island  450 , metal traces  456 , and emitters  472  in the emitter stack  454 ) substantially attenuate the intensified light  216 , transparent regions between the pixels are at least partially transparent to the intensified light  216 . Accordingly, the intensified light  216  is transmitted through the transparent regions between the pixels of the overlay display  218 . In contrast, the active Si islands  450  and the metal traces  456  substantially block the intensified light  216 . 
       FIG.  5 B  illustrates a cross-section of a part of the overlay display  218  in which a first set of fabrication layers are provided in which to implement the display control circuitry  544  (e.g., circuitry to drive the emitters  472  and generate display light  220 ). A second set of fabrication layers are provided in which to implement the data-handling circuitry  542 . Thus, the display control circuitry  544  and the data-handling circuitry  542  are respectively fabricated in separate circuitry planes. The display control circuitry  544  is fabricated in a first (upper) circuitry plane, and the data-handling circuitry  542  is fabricated in a second (lower) circuitry plane. 
       FIG.  6    illustrates a top-down view of a portion of an overlay display  218  in which the opaque regions (e.g., regions including the active Si islands  450  and metal traces  456 ) are configured with a transparent region  466  between the opaque regions. The active Si islands  450  and metal traces  456  may be configured to function as electronic components (such as MOSFETs) to provide logic functions and to provide control functions for the control of pixels in an overlay display  218 . The active Si islands  450  and metal traces  456  substantially block the intensified light  216 , but the intensified light  216  may be transmitted through the transparent region  466  between the Si islands  450  and metal traces  456 . Metal traces called column lines  458  and row lines  462  run between the pixels, conveying signals addressed to the respective pixels. These lines are also opaque regions. Accordingly, in a second circuitry plane (as illustrated by the data-handling circuitry  542  in  FIG.  5 B ) additionally opaque regions may be fabricated below the row and column lines without blocking the light transmitted through the transparent region  466 . For example, in the borderless display configuration, routing communication lines to the bond pads (see pad row  320  in  FIGS.  4 A and  4 B ) may be fabricated below the inter-pixel top metal row lines  462  and column lines  458 . 
     Returning to  FIGS.  5 A and  5 B , the display light  220  is generated by emitters  472  (e.g., OLEDs) that are driven by the display control circuitry  544 . The intensified light  216  passes through the transparent regions between the Si islands  450  and metal traces  456 , and the Si islands  450  and metal traces  456  attenuate/block the intensified light  216 . In  FIG.  5 B , the intensified light  216  would be blocked by the display control circuitry  544  even if the data-handling circuitry  542  were not present. Accordingly, the addition of the data-handling circuitry  542  below the display control circuitry  544  does not decrease the transmission of the intensified light  216  through the overlay display  218  or otherwise degrade the intensified image represented thereby. 
     Alternatively or additionally, the data-handling circuitry  542  may be provided above the display control circuitry  544 , so long as the data-handling circuitry  542  does not block or otherwise obscure the display light  220 . In certain embodiments, the data-handling circuitry  542  may be provided in a same fabrication layer as the display control circuitry  544 . This configuration (in which the data-handling circuitry  542  is coplanar with the display control circuitry  544 ) can be realized by increasing the area of the opaque region for each pixel. Increasing the area of the opaque regions may be a more viable option for overlay displays having lower pixel densities (e.g., lower resolution pixel arrays). 
     The data-handling circuitry  542  may include register circuits, digital to analog converters, analog to digital converter, direct memory access circuits, shift registers, logic circuits, and other circuitry for managing, communicating, and processing input and output pixel values for the overlay display  218 . 
     Returning to  FIG.  4 B , the image data pipeline  322 , analog reference block  324 , global configuration  326 , display data pipeline  328 , column driver  354 , and line driver  356  are each illustrated as having one edge adjacent to an edge of the active area  370 . By having one edge adjacent to an edge of the active area  370 , the respective units of circuitry are allowed to communicate/route signals from within the active area to outside of the active area and vice versa. For example, units of circuitry that have an edge adjacent to an edge of the active area  370  may route signals off chip or to circuitry that is on chip but outside of the active area. The pad row  320  includes bond pads for routing electrical signals on/off the semiconductor chip  300 . 
     An advantage of the borderless configuration illustrated in  FIG.  4 B  is that the semiconductor chip  300  may be used in a partial overlay display without requiring a beam splitter. Here, the word “borderless” means that the active area extends all the way to the border on at least one edge of the chip—not necessarily all four edges. Here, a “border” means the area of the chip between the active area of the display and the edge of the chip, in which area circuitry may be fabricated. For example, the semiconductor chip  300  in  FIG.  4 B  is borderless on three edges because there are no units of circuitry on three edges of the active area  370 , making the display illustrated in  FIG.  4 B  a borderless configuration. 
     In certain embodiments, the overlay display  218  may be configured to cover only part of the cross-sectional area of the intensified image (e.g., the top half of the intensified image).  FIG.  7 A  illustrates an example in which a non-borderless overlay display  218  is used to superimpose display light over the top half of the intensified light  216 . Because the column driver  354  is arranged in the middle of the cross-sectional area of the intensified light  216 , part of the intensified light  216  is obscured, which is disadvantageous. This obscuring of the intensified light  216  by the border corresponding to the column driver  354  may be cured either by using a borderless configuration for the overlay display  218 , as illustrated in  FIG.  7 C , or by using a prism/beam splitter  280 , as illustrated in  FIG.  7 B . 
     In  FIG.  7 B , the overlay display  218  is arranged outside of the optical path of the intensified light  216 . Then a prism/beam splitter  280  is used to combine the display light  220  with the intensified light  216 . Arranging the overlay display  218  outside of the optical path of the intensified light  216  has the drawback of increasing the overall size of the intensifier module  112 . Additionally, the beam splitter  280  increases the weight and size of the intensifier module  112 . These drawbacks are overcome by using a borderless overlay display  218 , as illustrated in  FIG.  7 C . 
     In  FIG.  7 C , a borderless overlay display  218  is used to superimpose display light over the top half of the intensified light  216 . Because the column driver  354  is within the active area  370 , the active area  370  extends all the way to the bottom edge of the overlay display  218 , in contrast to  FIG.  7 A . That is, the bottom edge of the overlay display  218  is a borderless edge that passes through an interior of the cross-sectional area of an optical path of the intensified image. Thus, there is no opaque border on the bottom of the overlay display  218  (e.g., there is no circuitry on the bottom edge of the overlay display  218 ), the borderless overlay display  218  does not obscure the middle of the cross-sectional area of the intensified light  216 . Accordingly, the borderless configuration allows for partial overlay displays without the additional size and weight incurred by using a beam splitter and without obscuring part of the intensified light  216  due to an opaque border, as in the bordered configuration in  FIG.  7 A . 
       FIG.  8    illustrates an embodiment of the overlay display  218  that includes photodetectors  428  arranged below the data-handling circuitry  542 . The photodetectors  428  detect an intensity of the intensified light  216 . The data-handling circuitry  542  can include a readout integrated circuit that processes and routes signals from the photodetectors  428 . For example, the readout integrated circuit may route signals from the semiconductor chip  300 , or the signals from the photodetectors  428  may be processed locally on the semiconductor chip  300  (e.g., to control an intensity of the display light  220 ). 
     In the examples above it should be noted that although not shown various alternatives can be implemented. For example, in any of the embodiments illustrated, a backside fill may be used or may be omitted. Alternatively, or additionally, while the active areas have been shown as being substantially square in nature, it should be appreciated that the active areas may be rectangular or other appropriate shapes. 
     The discussion above refers to a number of methods and method acts that may be performed. Although the method acts may be discussed in a certain order or illustrated in a flow chart as occurring in a particular order, no particular ordering is required unless specifically stated, or required because an act is dependent on another act being completed prior to the act being performed. 
     The present invention may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.