US-12625360-B2 - Night vision device with integrated display

US12625360B2US 12625360 B2US12625360 B2US 12625360B2US-12625360-B2

Abstract

A night vision device includes a binocular body in which is mounted, along an optical axis, an objective lens, a light intensifier tube, a light guide, and an eyepiece lens. The light intensifier tube includes a photocathode, a microchannel wafer, a phosphor screen intended to deliver a night vision image and a light guide having an input side contiguous to the phosphor screen and an output side intended to form an image in the focal plane of the eyepiece lens. The light intensifier tube further includes a display in the form of a thin glass plate or of a thin film comprising light-emitting elements, the thin plate/the thin film being directly arranged on the output side of the light guide. A power supply and control module, housed within the tube body, at the periphery of the light guide, delivers the respective bias voltages of the different elements of the light intensifier tube and controls the luminescence of the light-emitting elements of the display.

Inventors

Pierre-Yves BONY
Nicolas LAURENT
Geoffroy Deltel
Arend HIDDEMA

Assignees

PHOTONIS FRANCE

Dates

Publication Date: 20260512
Application Date: 20221028
Priority Date: 20211029

Claims (15)

1 . A night vision device comprising a binocular body in which are mounted, along an optical axis, an objective lens, a light intensifier tube, and an eyepiece lens, the light intensifier tube comprising a photocathode receiving light having crossed the objective lens and converting the photons thus received into photoelectrons, a microchannel wafer multiplying the photoelectrons received from the photocathode by generating secondary electrons, a phosphor screen delivering a night vision image based on the secondary electrons impacting it, a light guide having an input side contiguous to the phosphor screen and an output side forming an image in the focal plane of the eyepiece lens, wherein the light intensifier tube further comprises a display in the form of a thin glass plate or of a thin film comprising light-emitting elements, the thin plate/the thin film being directly arranged on the output side of the light guide, a power supply and control module, located within the light intensifier tube, at the periphery of the light guide, delivering respective bias voltages of the photocathode, of the light intensifier, and of the phosphor screen and controlling the light-emitting elements of the display.
2 . The night vision device according to claim 1 , wherein the light guide is formed by a glass block or by a bundle of optical fibers bonded to one another.
3 . The night vision device according to claim 2 , wherein the light-emitting elements appear in the form of segments.
4 . The night vision device according to claim 3 , wherein the display is formed by bonding of a glass plate on at least a portion of the output side, phosphor segments being deposited on the thin plate and individually addressable by conductive tracks.
5 . The night vision device according to claim 1 , wherein the display is formed by deposition of a film on at least a portion of the output side, planar or planarized, the deposition being performed by an atomic layer deposition technique.
6 . The night vision device according to claim 5 , wherein the thin film comprises a first dielectric layer, a light-emitting film, and a second dielectric layer, the assembly formed by the first dielectric layer, the light-emitting film, and the second dielectric layer being sandwiched between a first array of electrodes arranged in the form of columns and a second array of transparent electrodes organized in rows, orthogonal to the first array.
7 . The night vision device according to claim 1 , wherein the power supply and control module appears in the form of two distinct units, a first unit having the function of delivering respective high bias voltages of the photocathode, of the microchannel wafer, and of the phosphor screen and a second unit having the function of controlling the display.
8 . The night vision device according to claim 7 , further comprising a communication module coupled to the second unit by means of a bus, said communication module having a wireless radio interface, and delivering information to be displayed to the second unit via said bus, said first unit transmitting to the second unit a signal for controlling the luminance of the light-emitting elements to be displayed.
9 . The night vision device according to claim 8 , further comprising a power supply module powering with a low voltage the first and second units, the first unit comprising a voltage multiplier for generating said high bias voltages based on said low voltage.
10 . The night vision device according to claim 9 , wherein the first unit measures an anode current of the phosphor screen and supplies this measurement to the second unit, the second unit controlling a voltage and/or a duty cycle of a signal for biasing the light-emitting elements, to limit a ratio of a luminance of the elements thus displayed to a luminance of the night vision image, to a level within a range of predetermined values.
11 . The night vision device according to claim 10 , wherein the second unit controls the voltage and/or the duty cycle of the signal for biasing the light-emitting elements so that the luminance of the elements varies in successive stages, a variation of the luminance of the light-emitting elements following in delayed fashion the variation of the luminance of the night vision image when the latter increases or decreases.
12 . The night vision device according to claim 10 , wherein the second unit controls the voltage and/or the duty cycle of the signal for biasing the light-emitting elements so that the luminance of the elements is proportional to the anode current filtered by means of a recursive low-pass filter.
13 . The night vision device according to claim 1 , wherein the power supply and control module is an integrated unit, delivering the respective bias voltages of the photocathode, of the microchannel wafer, and of the phosphor screen, and controlling the display.
14 . The night vision device according to claim 13 , wherein said integrated unit is adapted to controlling the voltage and/or the duty cycle of the signal for biasing the light-emitting elements so that the luminance thereof is proportional to the anode current filtered by means of a recursive low-pass filter.
15 . A replacement light intensifier tube intended to retrofit a night vision device, said night vision device comprising a binocular body in which are mounted, along an optical axis, an objective lens, a light intensifier tube, and an eyepiece lens, said replacement light intensifier tube replacing the light intensifier tube and comprising a photocathode, receiving light having crossed the objective lens and converting the photons thus received into photoelectrons, a microchannel wafer multiplying the photoelectrons received from the photocathode by generating secondary electrons, a phosphor screen delivering a night vision image based on the secondary electrons impacting it, a light guide having an input side contiguous to the phosphor screen and an output side forming an image in the focal plane of the eyepiece lens, a display in the form of a thin glass plate or of a thin film comprising light-emitting elements, the thin plate/the thin film being directly arranged on the output side of the light guide, said replacement light intensifier tube further comprising a power supply and control module housed within the tube body, at the periphery of the light guide, and delivering respective bias voltages of the photocathode, of the light intensifier tube, and of the phosphor screen controlling the light-emitting elements of the display.

Description

TECHNICAL FIELD The present invention generally concerns the field of night vision devices using a light intensifier tube (also called image intensifier). It applies in particular to night vision binoculars (NVB). BACKGROUND Night vision devices are generally used in in theatres of operations of low luminosity, or even darkness, in a hostile civilian or military environment. These night vision devices operate in the visible and near-infrared spectral range. FIG. 1 schematically shows a conventional night vision device. The latter is constructed from a binocular body 100, within which are mounted, along an optical axis, an objective lens, 110, a light intensifier tube, 190, and an eyepiece lens 140. Light intensifier tube 190 comprises a photocathode, 121, receiving the light having crossed the objective lens, and converting the photons thus received into photoelectrons, a microchannel wafer or MCP, 122, playing the role of an electron multiplier by generating secondary electrons from the photoelectrons, a phosphor screen, 123, coupled to an anode, converting the flux of secondary electrons into a light flux. An output light guide, 130, generally formed of a glass block or of a bundle of optical fibers contiguous to the phosphor screen, is intended to form an image in the focal plane of the eyepiece lens, 140. Finally, a power supply module 150 delivers the power supply voltages enabling to bias the different elements forming the light intensifier tube. This power supply module is coupled to a battery arranged outside of the concerned tube. The user's concentration capacity being generally entirely focused on the observation of the amplified images, it is difficult for them to disperse their attention on a plurality of terminals to take into account additional information (GPS data, itinerary guides, compass, alerts etc.) likely to guide them or to aid them in the mission. To address this situation, it has been disclosed in document U.S. Pat. No. 11,054,629 to integrate a microdisplay in a conventional night vision device. This microdisplay is arranged orthogonally to the optical axis of the tube, downstream of the light intensifier tube and upstream of the eyepiece lens. The image of the data display is projected onto a glass plate inclined by 45° (or a prism) on the optical axis of the tube. The projected image is combined with that received from the light intensifier tube and the user of the device then perceives the combination of the two images through the eyepiece lens. While this assembly effectively enables to combine the image of a data display and that of a light intensifier tube within a same device, it cannot be obtained by simple retrofitting of an existing night vision device. Further, the arrangement of the display at the outlet of the tube is not mechanically stable. Finally, the presence of the microdisplay within the device, arranged orthogonally to the tube axis, decreases by its bulk the surface area of the exit pupil and, accordingly, the size of the image seen through the eyepiece lens. Further, when the luminance at the outlet of the light intensifier tube is low, the user of the night vision device may be dazzled by the display on the data screen. It is thus necessary to balance the intensity of the display and that of the intensifier tube. An object of the present invention accordingly is to provide a night vision device which does not have the limitations of the state of the art, in particular which may be equipped with a display by simple retrofitting, with no modification of the focal distance of the eyepiece lens and of the objective lens, and with no alteration of its performance, particularly with no decrease in the size of the amplified images. A secondary object of the present invention is to provide such an integrated display night vision device which maintains a good contrast level between the night vision image and the image provided by the display. Finally, another object of the invention is to provide a replacement light intensifier tube enabling to retrofit a conventional night vision device by transforming it into an integrated display night vision device. SUMMARY OF THE DISCLOSURE The present invention is defined by a night vision device comprising a binocular body in which are mounted, along an optical axis, an objective lens, a light intensifier tube, and an eyepiece lens, the light intensifier tube comprising a photocathode intended to receive the light having crossed the objective lens and to convert the photons thus received into photoelectrons, a microchannel wafer intended to multiply the photoelectrons received from the photocathode by generating secondary electrons, a phosphor screen intended to deliver a night vision image based on the secondary electrons impacting it, a light guide having an input side contiguous to the phosphor screen and an output side intended to form an image in the focal plane of the eyepiece lens, the night vision device being origina