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EP-3906437-B1 - DIRECT VIEW DISPLAY WITH TRANSPARENT VARIABLE OPTICAL POWER ELEMENTS

EP3906437B1EP 3906437 B1EP3906437 B1EP 3906437B1EP-3906437-B1

Inventors

  • AMIR, ORNIT
  • LANDESBERG, YOLANDA
  • ARLIEVSKY, ARON
  • NESHER, Ofer

Dates

Publication Date
20260513
Application Date
20191231

Claims (8)

  1. A see-through display system, STDS, configured to show synthetic images to a viewer while still allowing the viewer to see through the STDS, comprising: a variable optical power element, VOPE (30), located on a head mounted device; a transparent active image source (40) located on a head-up display, HUD, physically detached from the head mounted device, wherein the transparent active image source (40) lies on a common optical axis (50) with said VOPE (30) going from a scene (20) to an eye position of the viewer (10); wherein said VOPE (30) is positioned closer to the eye position than said transparent active image source (40); a time division multiplexer, TDM (60), configured to control said VOPE (30) and said transparent active image source (40), wherein said TDM (60) is configured in a certain time period (T1) to cause said transparent active image source (40) to be in a transparent state and said VOPE (30) to exhibit no optical power, wherein said TDM is configured in another time period (T2) to cause said transparent active image source (40) to generate a respective synthetic image (22) along the optical axis (50) going from a scene (20) to an eye position of the viewer (10) and said VOPE (30) to apply non-zero optical power, for projecting the respective synthetic image (22) onto the eye position at a desirable distance therefrom, wherein said TDM (60) is configured to control said VOPE (30) with different optical powers (OP-A, OP-B, OP-C, OP-D) to present the respective synthetic image (22) at different distances corresponding to different locations (22A, 22B, 22C, 22D) along the optical axis (50) over time, and wherein said TDM (60) alternates between said certain time period (T1) and said another time period (T2); and an illumination condition controller configured to selectively adjust the duty cycle (210, 220, 230) of the TDM (60) responsive to illumination conditions such that a ratio between the certain time period (T1) and the another time period (T2) is varied to blend between the luminance of the scene (20) versus the luminance of the respective synthetic images (22) presented to the viewer (10).
  2. The see-through display system according to claim 1, further comprising an enhanced vision system, EVS, wherein said scene comprises a scene generated by said EVS.
  3. The see-through display system according to claim 1, further comprising night vision goggles, NVG, wherein said scene comprises a scene generated by said NVG.
  4. The see-through display system according to claim 1, further configured to present to each eye of said viewer said image from the image source from a different angle.
  5. The see-through display system according to claim 1, wherein said VOPE (30) is configured to have two or more focal planes so as to present at least two objects from said image source in a different depth to said viewer.
  6. The see-through display system according to claim 1, wherein said TDM (60) is further operable in at least two frequencies and wherein said image source is further configured to provide a different image for each of said frequencies to enable two or more viewers presented with different images.
  7. The see-through display system according to claim 1, wherein said TDM (60) exhibits a plurality of time period slots to generate at the transparent active image source a different image in each of said time period slots.
  8. A method for controlling a see-through display, STDS, configured to show synthetic images to a viewer while still allowing the viewer to see through the STDS, the STDS including: a variable optical power element, VOPE (30), located on a head mounted device, and a transparent active image source (40) located on a head-up display, HUD, physically detached from the head mounted device, wherein the transparent active image source (40) lies on a common optical axis (50) with said VOPE (30) going from a scene (20) to an eye position of a viewer (10), wherein said VOPE (30) is positioned closer to the eye position than said transparent active image source (40), the method comprising: controlling, using a time division multiplexer, TDM (60), said VOPE (30) and said transparent active image source (40), causing, using said TDM (60), in a certain time period (T1), the transparent active image source (40) to be in a transparent state and said VOPE (30) to exhibit no optical power, and causing, using said TDM (60), in another time period (T2), the said transparent active image source (40) to generate a respective synthetic image (22) along the optical axis (50) going from a scene (20) to an eye position of the viewer (10) and causing said VOPE (30) to apply non-zero optical power, for projecting the respective synthetic image (22) onto the eye position at a desirable distance therefrom, wherein said VOPE (30) is controlled, using said TDM (60), with different optical powers (OP-A, OP-B, OP-C, OP-D) to present the respective synthetic image (22) at different distances corresponding to different locations (22A, 22B, 22C, 22D) along the optical axis (50) over time, wherein said TDM (60) alternates between said certain time period (T1) and said another time period (T2), and wherein the method further comprises using an illumination controller to selectively adjust the duty cycle (210, 220, 230) of the TDM (60) responsive to illumination conditions such that a ratio between the certain time period (T1) and the another time period (T2) is varied to blend between the luminance of the scene (20) versus the luminance of the respective synthetic images (22) presented to the viewer (10).

Description

FIELD OF THE INVENTION The present invention relates generally to the field of see-through and direct view display systems. BACKGROUND OF THE INVENTION Prior to setting forth the background of the invention, it may be helpful to set forth definitions of certain terms that will be used hereinafter. A "see-through display" or a "see-through display system" (STDS) as used herein is defined as an electronic display that allows the user (e.g. viewer) to see what is shown on the screen (e.g. glass screen) while still being able to see through it. These screens may be used for augmented reality (AR), a way of enhancing the view of the world with digital images (e.g. synthetic images) overlaid onto real ones, and other applications such as shopping displays and more sophisticated computer screens. An "active image source" as used herein is any device that actively produces an image on a transparent screen, possibly responsive to some incoming data stream. The "active image source" can be, for example, a transparent organic light emitting diode (OLED) or a transparent liquid crystal display (LCD) or a projector combined with a transparent fluorescent or phosphorus screen. A "direct view display system" or a "direct view display" as used herein is defined as an electronic display in which the synthetic image is generated (possibly by an active image source) along the optical axis going from the scene to the eye of the viewer. This type of display called "direct" since the image is produced and viewed directly from the source of the image and it is not being reflected or folded from an image source located outside the optical axis running from the scene to the viewer. A "variable optical power element" or "VOPE" as used herein is a material that changes its optical power (e.g. focal length) in response to a stimulus signal such as electricity. The VOPE can be made of, by way of example, an electricity reactive lens and may be implemented in many ways and is not limited herein to one implementation. The main challenge with see-through displays is making sure that both the outside scene and the synthetic image are viewed in optimal conditions for the viewer in terms of the focal plane in which the outside scene and the synthetic image are presented. While the outside scene is in infinity, the synthetic image is located on a focal plan positioned between a few centimeters (in a case of a near eye display) and tens of centimeters (in a case of a head up display). EP 2447757, WO 2014/197109, US 2015/378074, US 2016/147067, and US 2018/146183 represent relevant documents in the field. SUMMARY OF THE INVENTION The invention is defined in the claims. BRIEF DESCRIPTION OF THE DRAWINGS The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which: Figure 1A shows a block diagram and a respective timing diagram illustrating a non-limiting exemplary architecture of a see-through display system (STDS) in a head up display (HUD) configuration and its functionality;Figure 1B shows a block diagram and a respective timing diagram illustrating a non-limiting exemplary architecture of a see-through display system (STDS) in a head mounted display (HMD) configuration and its functionality;Figure 2 shows a block diagram illustrating a non-limiting exemplary architecture of an STDS in either HMD or HUD configuration with respective timingFigure 3 shows a block diagram illustrating a non-limiting exemplary architecture of an STDS in either HMD or HUD configuration with a respective timing diagram;Figure 4 shows a block diagram illustrating a non-limiting exemplary architecture of an STDS in either HMD or HUD configuration with a respective timing diagram;Figure 5 shows a block diagram illustrating a non-limiting exemplary architecture of an STDS in either HMD or HUD configuration with a respective timing diagram;Figure 6 shows a block diagram illustrating a non-limiting exemplary architecture of an STDS in either HMD or HUD configuration with a respective timing diagram;Figure 7 shows a block diagram illustrating a non-limiting exemplary architecture of an STDS in either HMD or HUD configuration with a respective timing; andFigure 8 is a high-level flowchart illustrating non-limiting exemplary method. It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. DETAILED DESCRIPTION O