US-12625371-B2 - Projector comprising a variable aperture assembly that can move laterally along an optical axis and rotate with respect to the optical axis

Abstract

A projector for use in a head-up or head-worn display is described. The projector comprises a display source, an output screen, and a variable aperture assembly. The variable aperture assembly is positioned on an optical axis between the display source and the output screen and is adjustable to change a geometry (e.g. size and/or shape) of an aperture that is aligned with the optical axis and thereby change the efficiency of the optical train of the projector. The geometry that is changed may be a physical geometry or an effective geometry.

Inventors

• Darren Neil Grimwood

Assignees

• BAE SYSTEMS PLC

Dates

Publication Date

20260512

Application Date

20220321

Priority Date

20210330

Claims (20)

1. 1 . A projector for use in a head-up or head-worn display, the projector comprising: a display source; an output screen; a variable aperture assembly positioned on an optical axis between the display source and the output screen and wherein the variable aperture assembly is adjustable to change a physical or an effective geometry of an aperture that is aligned with the optical axis; and an aperture actuator mechanism coupled to the variable aperture assembly, the aperture actuator mechanism configured to (i) change the effective geometry of the variable aperture assembly by moving the variable aperture assembly along the optical axis, and (ii) change the physical geometry of the variable aperture assembly by a lateral motion or a rotation of at least a portion of the variable aperture assembly with respect to the optical axis.
2. 2 . The projector according to claim 1 , wherein the physical geometry of the aperture comprises a size of the aperture.
3. 3 . The projector according to claim 1 , wherein the physical geometry of the aperture comprises a shape of the aperture.
4. 4 . The projector according to claim 1 , wherein the variable aperture assembly comprises a plate with a plurality of apertures of different geometries in the plate, and wherein the aperture that is aligned with the optical axis can be any one of the plurality of apertures.
5. 5 . The projector according to claim 4 , wherein the plate comprises two apertures of different sizes.
6. 6 . The projector according to claim 4 , wherein the plate comprises three apertures of different sizes.
7. 7 . The projector according to claim 1 , wherein: the variable aperture assembly comprises a plate with a plurality of apertures of different geometries in the plate; and the aperture actuator mechanism is operable to move the plate between two or more pre-set positions, wherein in each pre-set position a different one of the plurality of apertures is aligned with the optical axis.
8. 8 . The projector according to claim 7 , wherein the motion is a lateral motion.
9. 9 . The projector according to claim 7 , wherein the motion is a rotation.
10. 10 . The projector according to claim 1 , wherein the variable aperture assembly comprises a plate having an opening and a movable member, and wherein the aperture actuator mechanism is operable to move the movable member relative to the plate, wherein moving the movable member changes the effective geometry of the aperture that is aligned with the optical axis.
11. 11 . The projector according to claim 1 , wherein the variable aperture assembly comprises a plate with a variable geometry aperture in the plate.
12. 12 . The projector according to claim 11 , wherein the aperture actuator mechanism is operable to change the geometry of the variable geometry aperture.
13. 13 . The projector according to claim 1 , having a first mode of operation wherein the variable aperture assembly is adjusted to a first aperture size and a second mode of operation wherein the variable aperture assembly is adjusted to a second aperture size and wherein the first aperture size is smaller than the second aperture size.
14. 14 . The projector according to claim 13 , wherein the projector is operable to switch between the first mode and the second mode of operation in response to an input signal.
15. 15 . The projector according to claim 14 , wherein the input signal is received from a switch or button.
16. 16 . The projector according to claim 14 , wherein the input signal is received from an ambient light level sensing system.
17. 17 . The projector according to claim 16 , wherein the projector is operable to switch to the first mode of operation in response to an input signal indicating an ambient light level below a first pre-defined threshold.
18. 18 . The projector according to claim 16 , wherein the projector is operable to switch to the second mode of operation in response to an input signal indicating an ambient light level above a second pre-defined threshold.
19. 19 . A head-up display comprising the projector according to claim 1 .
20. 20 . A head-worn display comprising the projector according to claim 1 .

Description

TECHNICAL FIELD The present invention relates to an improved projector and in particular to an improved projector for use in a head-up display (HUD) or head-worn (or head-mounted) display. BACKGROUND A head-up display (HUD) is a transparent display device that presents data and or images to a user without requiring the user to look away from the scene they are viewing. For example, a HUD may be used by an aircraft pilot to receive images and data from various sources whilst viewing their normal field of view, either naturally or via an imaging device. A head-worn display (or head-mounted display, HMD) is a different type transparent display device that presents data and or images to a user without requiring the user to look away from the scene they are viewing. A head-worn display may, for example, be integrated in a helmet. The helmet may be worn by an aircraft pilot, for example, and used to receive images and data from various sources whilst viewing their normal field of view. The helmet may alternatively be worn in other situations, e.g. on a boat/ship, in a land-based vehicle, etc. In another example, the head-worn display may be in the form of glasses or other form-factor. Both HUDs and head-worn displays include a device that generates the image viewed by the user. In older designs, the image was generated using CRT technology; however, these devices are now being replaced with DLE (digital light engine) projectors which include an electro-optic light source (e.g. LEDs) and are much smaller and lighter. Such a projector may, for example, be a DLE (digital light engine) projector or may use other technologies, such as LCDs. The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known head-up or head-worn displays. SUMMARY 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. A projector for use in a head-up or head-worn display is described. The projector comprises a display source, an output screen, and a variable aperture assembly. The variable aperture assembly is positioned on an optical axis between the display source and the output screen and is adjustable to change a geometry (e.g. size and/or shape) of an aperture that is aligned with the optical axis and thereby change the efficiency of the optical train of the projector. The geometry that is changed may be a physical geometry or an effective geometry. A first aspect provides a projector for use in a head-up or head-worn display, the projector comprising: a display source; an output screen; and a variable aperture assembly positioned on an optical axis between the display source and the output screen and wherein the variable aperture assembly is adjustable to change a physical or an effective geometry of an aperture that is aligned with the optical axis. The projector may further comprise an aperture actuator mechanism coupled to the variable aperture assembly and operable to change the geometry of an aperture that is aligned with the optical axis. The variable aperture assembly may be adjustable to change the physical geometry of the aperture. The geometry of an aperture may comprise the size of an aperture. The geometry of an aperture may comprise the shape of an aperture. The variable aperture assembly may comprise a plate with a plurality of apertures of different geometries in the plate. The plate may comprise two apertures of different sizes. The plate may comprise three apertures of different sizes. The aperture actuator mechanism may be operable to move the plate between two or more pre-set positions, wherein in each pre-set position a different one of the plurality of apertures is aligned with the optical axis. The motion may be a lateral motion. The motion may be a rotation. The variable aperture assembly may comprise a plate having an opening and a second member and wherein the aperture actuator mechanism is operable to move the second member relative to the plate, wherein moving the second member changes the geometry of the aperture. The variable aperture assembly may comprise a plate with a variable geometry aperture in the plate. The aperture actuator mechanism may be operable to change the geometry of the variable geometry aperture. The aperture actuator mechanism may be operable to move the variable aperture assembly along the optical axis. The projector may have a first mode of operation wherein the variable aperture assembly is adjusted to a first aperture size and a second mode of operation wherein the variable aperture assembly is adjusted to a second aperture size and wherein the first aperture size is smaller than the second aperture size. The projector may be operable to sw