Patent Description:
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.

From <CIT> an enhanced vision system includes a first optic subsystem and a transparent photodetector subsystem disposed within a common housing is known. The first optic subsystem includes passive devices such as simple or compound lenses, active devices such as low-light enhancing image intensifiers, or a combination of passive and active devices. The transparent photodetector subsystem receives the visible image exiting the first optic subsystem and converts a portion of the electromagnetic energy in the visible image to a signal communicated to image analysis circuitry. On a real-time or near real-time basis, the image analysis circuitry detects and identifies structures, objects, and/or individuals in the visible image. The image analysis circuitry provides an output that includes information regarding the structure, objects, and individuals to the system user contemporaneous with the system user viewing the visible image.

From <CIT> a system for combining multi-spectral images of a scene is known. The system includes a first detector for transmitting a scene image in a first spectral band. A separate, second detector senses the scene in a second spectral band. The second detector has an image output that is representative of the scene. A transparent display mounted in the output viewing path of the first detector and displays a displayed image in the second spectral band. The image of the transparent display is aligned such that the image of the scene in the second spectral band combines with the image output in the first spectral band. The combined multi-spectral images are conveyed to an output for a user.

From <CIT> a display device is known. The display device includes a substrate having a plurality of transmissive regions aligned in a first direction and a second direction, a plurality of first wiring lines on the substrate extending in the first direction, a plurality of second wiring lines on the substrate extending in the second direction, and a plurality of light emitting sections disposed on the substrate. Each of the transmissive regions is surrounded by the first and second wiring lines. The light emitting sections include a first light emitting section and a second light emitting section. At least part of the first light emitting section is located in a region that is adjacent to the transmissive regions and overlap one of the first wiring lines. At least part of the second light emitting section is located in a region that is adjacent to the transmissive regions and overlap one of the second wiring lines.

The invention is defined in claim <NUM> and preferred embodiments are defined in the dependent claims.

Another embodiment not covered by the subject-matter of the claims, 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.

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 <FIG>, a non-limiting example of a NV system is illustrated. In particular, <FIG> illustrate a PVS <NUM> NV system <NUM>. In the example illustrated, the NV system <NUM> includes a housing <NUM>. As will be illustrated in more detail below in other figures, the housing <NUM> houses an image intensifier module <NUM>. The NV system <NUM> further includes an objective <NUM> which receives light reflected and/or generated in an environment. The objective <NUM> includes optics such as lenses, waveguides, and/or other optical components for receiving and transmitting light to the image intensifier module <NUM>. The NV system <NUM> further includes an eyepiece <NUM>. The eyepiece <NUM> includes optics for focusing images created by the NV system <NUM> into the eye of the user.

<FIG> illustrates the image intensifier module <NUM>, according to one example. The image intensifier module <NUM> includes an image intensifier <NUM> without an overlay display. The light from the image intensifier module <NUM> is captured by the eyepiece <NUM> and directed to the user.

The image intensifier module <NUM> receives the input light <NUM>, which has been transmitted through the objective <NUM> to the image intensifier module <NUM>. The input light <NUM> 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 <NUM> into the image intensifier <NUM>. The image intensifier <NUM> 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 <NUM>, a microchannel plate <NUM>, and a phosphor screen <NUM>. The photocathode <NUM> absorbs incident photons and outputs electrons in response. The electrons may pass through an optional ion barrier film <NUM>. Electrons from the photocathode <NUM> are transmitted to the microchannel plate <NUM>, which multiplies the number of electrons. The multiplied electrons then strike a phosphor screen <NUM>, which absorbs the energy from electrons generating photons in response. The phosphor screen <NUM> converts the radiant energy of the multiplied electrons to luminescent light via the phenomenon of luminescence. Accordingly, the phosphor screen <NUM> glows due to electrons from the microchannel plate <NUM> striking the phosphor screen <NUM>, creating an intensified image that represents the image of the input light <NUM>. A fiber-optic element <NUM> carries the intensified light <NUM> (with the intensified image) to the eyepiece <NUM>.

The analog NV system <NUM> is a direct-view imager. The analog NV system <NUM> generates an image directly from the input light <NUM> 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 <NUM>, the overlay display <NUM> generates a display image which is discussed below.

The overlay display <NUM> generates display light <NUM>, which is superimposed with the intensified light <NUM>. For example, the overlay display <NUM> 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>, which is discussed below, illustrates an example of an image in which an overlay display <NUM> superimposes text, symbols, and other information over an intensified image that includes trees and clouds. Additional details regarding certain embodiments of the NV system <NUM> and the overlay display <NUM> are provided in <CIT>, titled "Backside Etch Process for Transparent Silicon Oxide Technology".

<FIG> illustrates an example of an image in which an overlay display <NUM> superimposes text and other graphical symbols over an amplified image of a nightscape that includes trees and clouds. As discussed above, the overlay display <NUM> 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 <NUM> outputs display light <NUM> which can be sent to the eyepiece. Thus, an image such as that illustrated in <FIG> is presented to the user in the NV system <NUM>.

<FIG> and <FIG> illustrate top-down views of respective layouts for the overlay display <NUM>. In both <FIG> and <FIG>, the overlay display <NUM> is fabricated on a semiconductor chip <NUM>, and the overlay display <NUM> includes an active area <NUM> and data-handling circuitry, including, e.g., an image data pipeline <NUM>, an analog reference block <NUM>, a global configuration <NUM>, a display data pipeline <NUM>, a column driver <NUM>, and a line driver <NUM>. In <FIG>, the layout for the overlay display <NUM> has the data-handling circuitry within the active area <NUM>. In <FIG>, the data-handling circuitry is outside the active area <NUM>. Inside the active area <NUM>, transparent regions are arranged between pixels, and the transparent regions transmit the intensified light <NUM>, as discussed below with reference to <FIG> and <FIG>. In contrast, outside the active area <NUM>, the chip is opaque to the intensified light <NUM>.

An advantage of having some (or all) of the data-handling circuitry within the active area, as illustrated in <FIG>, is that the active area <NUM> occupies a larger percentage of the total area of the semiconductor chip <NUM>. Thus, the semiconductor chip <NUM> can be smaller because it does not require a large boundary region in which to fabricate additionally circuitry. Because the semiconductor chip <NUM> 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 <NUM>, the active area <NUM> may extend all the way to the border/periphery of the semiconductor chip <NUM>. For example, <FIG> illustrates the active area <NUM> extending to the border/periphery on three edges of the semiconductor chip <NUM>. The data-handling circuitry can be arranged within the active area <NUM> by fabricating the data-handling circuitry below or above the display control circuitry, for example.

Additionally, in certain embodiments not covered by the subject-matter of the claims, 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>. 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> illustrates a cross-section of a part of the overlay display <NUM>. In certain non-limiting embodiments, the overlay display <NUM> may include active silicon areas, which are illustrated as active silicon islands <NUM> (e.g., native silicon islands). The active silicon islands <NUM> 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 <NUM> that include insulators (e.g., oxides and dielectrics) and metal traces <NUM>. In certain embodiments not covered by the subject-matter of the claims, 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 <NUM>).

In the example illustrated in <FIG>, each of the active silicon islands represents a pixel of the overlay display <NUM>. Thus, by powering various emitters <NUM> in the emitter stack <NUM> using the transistors in the active silicon islands, a display image can be created by the overlay display <NUM> and output to a user. In certain embodiments not covered by the subject-matter of the claims, the emitters <NUM> can be organic light emitting diodes (OLEDs). A display image is generated by outputting the display light <NUM>. In <FIG>, the intensified light <NUM> enters the overlay display <NUM> from the bottom, passes through the oxide <NUM> and then through the other layers before exiting the overlay display <NUM> through the cover glass <NUM>. The display light <NUM> is generated in the emitter <NUM> and, like the intensified light <NUM>, the display light <NUM> exits through the cover glass <NUM>. After exiting through the cover glass, both the display light <NUM> and the intensified light <NUM> are transmitted to the eyepiece <NUM> of the NV system <NUM>, and then to the user.

Whereas the pixels (i.e., Si island <NUM>, metal traces <NUM>, and emitters <NUM> in the emitter stack <NUM>) substantially attenuate the intensified light <NUM>, transparent regions between the pixels are at least partially transparent to the intensified light <NUM>. Accordingly, the intensified light <NUM> is transmitted through the transparent regions between the pixels of the overlay display <NUM>. In contrast, the active Si islands <NUM> and the metal traces <NUM> substantially block the intensified light <NUM>.

<FIG> illustrates a cross-section of a part of the overlay display <NUM> in which a first set of fabrication layers are provided in which to implement the display control circuitry <NUM> (e.g., circuitry to drive the emitters <NUM> and generate display light <NUM>). A second set of fabrication layers are provided in which to implement the data-handling circuitry <NUM>. Thus, the display control circuitry <NUM> and the data-handling circuitry <NUM> are respectively fabricated in separate circuitry planes. The display control circuitry <NUM> is fabricated in a first (upper) circuitry plane, and the data-handling circuitry <NUM> is fabricated in a second (lower) circuitry plane.

<FIG> illustrates a top-down view of a portion of an overlay display <NUM> in which the opaque regions (e.g., regions including the active Si islands <NUM> and metal traces <NUM>) are configured with a transparent region <NUM> between the opaque regions. The active Si islands <NUM> and metal traces <NUM> 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 <NUM>. The active Si islands <NUM> and metal traces <NUM> substantially block the intensified light <NUM>, but the intensified light <NUM> may be transmitted through the transparent region <NUM> between the Si islands <NUM> and metal traces <NUM>. Metal traces called column lines <NUM> and row lines <NUM> 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 <NUM> in <FIG>) additionally opaque regions may be fabricated below the row and column lines without blocking the light transmitted through the transparent region <NUM>. For example, in the borderless display configuration, routing communication lines to the bond pads (see pad row <NUM> in <FIG> and <FIG>) may be fabricated below the inter-pixel top metal row lines <NUM> and column lines <NUM>.

Returning to <FIG> and <FIG>, the display light <NUM> is generated by emitters <NUM> (e.g., OLEDs) that are driven by the display control circuitry <NUM>. The intensified light <NUM> passes through the transparent regions between the Si islands <NUM> and metal traces <NUM>, and the Si islands <NUM> and metal traces <NUM> attenuate/block the intensified light <NUM>. In <FIG>, the intensified light <NUM> would be blocked by the display control circuitry <NUM> even if the data-handling circuitry <NUM> were not present. Accordingly, the addition of the data-handling circuitry <NUM> below the display control circuitry <NUM> does not decrease the transmission of the intensified light <NUM> through the overlay display <NUM> or otherwise degrade the intensified image represented thereby.

Alternatively or additionally, the data-handling circuitry <NUM> may be provided above the display control circuitry <NUM>, so long as the data-handling circuitry <NUM> does not block or otherwise obscure the display light <NUM>. In certain embodiments not covered by the subject-matter of the claims, the data-handling circuitry <NUM> may be provided in a same fabrication layer as the display control circuitry <NUM>. This configuration (in which the data-handling circuitry <NUM> is coplanar with the display control circuitry <NUM>) 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 <NUM> 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 <NUM>.

Returning to <FIG>. , the image data pipeline <NUM>, analog reference block <NUM>, global configuration <NUM>, display data pipeline <NUM>, column driver <NUM>, and line driver <NUM> are each illustrated as having one edge adjacent to an edge of the active area <NUM>. By having one edge adjacent to an edge of the active area <NUM>, 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 <NUM> may route signals off chip or to circuitry that is on chip but outside of the active area. The pad row <NUM> includes bond pads for routing electrical signals on/off the semiconductor chip <NUM>.

An advantage of the borderless configuration illustrated in <FIG> is that the semiconductor chip <NUM> 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 <NUM> in <FIG> is borderless on three edges because there are no units of circuitry on three edges of the active area <NUM>, making the display illustrated in <FIG> a borderless configuration.

In certain embodiments, the overlay display <NUM> 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> illustrates an example in which a non-borderless overlay display <NUM> is used to superimpose display light over the top half of the intensified light <NUM>. Because the column driver <NUM> is arranged in the middle of the cross-sectional area of the intensified light <NUM>, part of the intensified light <NUM> is obscured, which is disadvantageous. This obscuring of the intensified light <NUM> by the border corresponding to the column driver <NUM> may be cured either by using a borderless configuration for the overlay display <NUM>, as illustrated in <FIG>, or by using a prism/beam splitter <NUM>, as illustrated in <FIG>.

In <FIG>, the overlay display <NUM> is arranged outside of the optical path of the intensified light <NUM>. Then a prism/beam splitter <NUM> is used to combine the display light <NUM> with the intensified light <NUM>. Arranging the overlay display <NUM> outside of the optical path of the intensified light <NUM> has the drawback of increasing the overall size of the intensifier module <NUM>. Additionally, the beam splitter <NUM> increases the weight and size of the intensifier module <NUM>. These drawbacks are overcome by using a borderless overlay display <NUM>, as illustrated in <FIG>.

In <FIG>, a borderless overlay display <NUM> is used to superimpose display light over the top half of the intensified light <NUM>. Because the column driver <NUM> is within the active area <NUM>, the active area <NUM> extends all the way to the bottom edge of the overlay display <NUM>, in contrast to <FIG>. That is, the bottom edge of the overlay display <NUM> 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 <NUM> (e.g., there is no circuitry on the bottom edge of the overlay display <NUM>), the borderless overlay display <NUM> does not obscure the middle of the cross-sectional area of the intensified light <NUM>. 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 <NUM> due to an opaque border, as in the bordered configuration in <FIG>.

<FIG> illustrates an embodiment not covered by the subject-matter of the claims, of the overlay display <NUM> that includes photodetectors <NUM> arranged below the data-handling circuitry <NUM>. The photodetectors <NUM> detect an intensity of the intensified light <NUM>. The data-handling circuitry <NUM> can include a readout integrated circuit that processes and routes signals from the photodetectors <NUM>. For example, the readout integrated circuit may route signals from the semiconductor chip <NUM>, or the signals from the photodetectors <NUM> may be processed locally on the semiconductor chip <NUM> (e.g., to control an intensity of the display light <NUM>).

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.

Claim 1:
An optical device comprising:
a semiconductor chip (<NUM>) having a first surface that receives direct-view light and transmits the direct-view light through transparent regions (<NUM>); and
a plurality of electro-optical circuits formed on the semiconductor chip (<NUM>), the plurality of electro-optical circuits comprising light emitters (<NUM>) spanning an active area (<NUM>) that extends to one or more edges of the semiconductor chip (<NUM>), the light emitters (<NUM>) configured to output display light, and the transparent regions (<NUM>) being arranged between the respective light emitters (<NUM>), wherein a plurality of data-handling circuits (<NUM>) is formed on the semiconductor chip (<NUM>), the plurality of data-handling circuits (<NUM>) routing signals to and/or from the plurality of electro-optical circuits, wherein a plurality of display-control circuits (<NUM>) is formed in first fabrication layer of the semiconductor chip (<NUM>), the plurality of display-control circuits (<NUM>) being formed within the active area (<NUM>), and the first fabrication layer being below a plurality of emitters, when observed from a top-down view, characterized in that the plurality of data-handling circuits (<NUM>) is fabricated below plurality of electro-optical circuits, when observed from a top-down view.