KR20020057981A - Scanning beam image display - Google Patents

Abstract

The display device includes first and second IR or other light sources 80 that generate respective first and second invisible wavelengths. This light is modulated according to the desired image. This modulated light 82 is applied to the wavelength selective phosphor 96 which converts each component of the light into its own visible wavelength. In one embodiment, the image source is a scanning light beam display 70 that scans an IR light beam onto a screen carrying a phosphor.

Description

Scanning beam image display

Low-brightness projections are widely used in many applications such as night vision goggles ("NVGs"). NVGs allow personnel such as soldiers and police to see objects at night, in low-light environments.

Typical night vision glasses use an image intensifier tube (ITT) that produces a visible image in response to ambient light. In order to generate a visible image, an image reinforcing tube converts surrounding visible or invisible radiation into visible light of a wavelength that a user can easily recognize.

The prior art NVG 30 shown in FIG. 1 includes an input lens 32 that couples light from an external environment 34 to the IIT 36. IIT 36 is a G2 or G3 series IIT available from Edmonds Scientific. As shown in FIG. 2, the IIT 36 includes a photocathode 38 which emits electrons in response to light having an input wavelength λ _in . When these electrons enter the microchannel plate 40, the plate accelerates or increases the electrons to output higher energy electrons. Upon exiting the microchannel plate 40, these higher energy electrons impinge on the screen 42 covered with a cathode light emitting layer 44, such as a green phosphor. Cathode light emitting layer 44 responds to the electrons by emitting visible light in the area where they hit the screen 42. The light exiting the cathode emissive layer 44 thus forms the output of the IIT 36.

As shown in FIG. 1, visible light from the cathode light emitting layer 44 goes to an eye coupling optic 46 comprising an input lens 48, a beam splitter 50, and respective eyepieces 52. The lens 48 sends this visible light to the beam splitter 50, and the beam splitter 50 sends a portion of this visible light to each eyepiece 52. Each of the eyepieces 52 converts into light that each of the user's eyes 54 sees.

As you know, conventional photocathodes are often very sensitive in the IR range or near the IR range. This high sensitivity allows the photocathode to generate electrons at a very low luminance level so that the IIT 36 can generate output light at very low light conditions. For example, some NVGs can produce visible images in an environment of light sources that are darker than starlight.

Often, users are trained to operate appropriately and efficiently in low perspective environments using perspective NVG. For example, lens 48, IIT 36, and eyepiece 52 may cause significant distortion in the projected image. In addition, screen 42 typically outputs monochromatic light with limited resolution and contrast. Furthermore, NVG's limited field depth and narrow field of view give the user a sense of "tunnel vision." Due to the overall optical effects of distortion, monochromaticity, contrast limitations, field depth limitations and field of view limitations, users often need to practice manipulating NVGs before attempting important activities.

In addition to optical influences, users often take time to get used to the physical presence of NVG. For example, the NVG forms a mass off the center of mass of the user's head. The added mass exerts a force on the user that can affect the user's physical movement and balance. The combination of optical and physical effects significantly degrades the user's functionality, so some form of NVG training is often required before the user can intervene in difficult or dangerous activities.

One training method disclosed in US Pat. No. 5,420,414 replaces IIT with a fiber rod that sends light to a user in an external environment. This fiber rod is intended to limit the user's depth perception while allowing the user to see the external environment through a modified NVG eyepiece. This fiber rod system requires no IIT and does not provide light at the output wavelength of the cathode light emitting layer. In addition, the fiber rod system does not seem to suggest a way to provide an electronically generated image.

Another method for fiber rod systems is to project an electronically generated IR or IR proximity image onto the large screen that substantially surrounds the user. The user then sees the screen through the NVG. These systems have some drawbacks, such as limiting the user's movement and orientation in places where the screen is visible through NVG.

Moreover, typical large screen systems use projection light to produce screen images. One of the simplest and most effective ways to project light onto a large peripheral screen is to place the projected light source near the center of curvature of the screen. Unfortunately, in such places, the user can block such projection light while roaming the artificial environment. To avoid this blocking, the environment may use more than one source or place the light source in a bad place at the time of image generation.

The present invention relates to a low light viewing system, and more particularly to a low brightness viewing system for generating simulated images to a user.

1 is a schematic diagram of a conventional low brightness perspective instrument comprising an image intensifier tube (IIT) and associated optics;

2 is a detailed block diagram of the IIT of FIG. 1;

3 is a diagram of a combined image perceived by a user by a combination of light and background light of an image source;

4 is a schematic diagram of a night vision simulator comprising an infrared beam scanned over a night vision input,

5 is a side view of a head wear night vision simulator including a tied IR source,

6 is a schematic diagram of an IR scanning system suitable for use as an image source in the FIG. 2 display;

7 is a schematic diagram of a simulator embodiment including an LCD panel with an infrared backlight;

8 is a schematic of a simulator embodiment including a FED emitter,

9 is a plan view of a simulation environment including a plurality of users and a central control system including a computer controller and rf links;

10 is a schematic diagram of a display embodiment including a scanning light beam and a reflected visible beam activating a wavelength conversion phosphor;

11 is a schematic representation of a head wearable display embodiment including a scanned invisible radiation beam that activates a wavelength converting phosphor that produces a visible image;

12 is a schematic diagram of a color display system using multiple wavelengths of invisible radiation sources to selectively activate wavelength selective phosphors;

FIG. 13 is a plan view of a biaxial MEMS scanner for use in the display of FIG. 4. FIG.

(Summary of invention)

According to an embodiment of the present invention, the display device includes a night vision glasses and an infrared source. In one embodiment, the infrared source is a scanning light beam display device comprising a scanning system and an infrared light emitter. This infrared source receives an image signal from a control electronics that displays the image to be viewed. This control electronics operates the light emitter, which emits modulated light with an intensity corresponding to the desired image. At the same time, a scanning mirror inside the scanning system scans the modulated light through a raster pattern that almost passes over the image enhancer tube of the night vision glasses.

In response to the incident infrared light, the IIT outputs visible light for the user to see. In one embodiment, the input to the IIT is closed so that ambient light does not affect the IIT.

In one embodiment including a scanner, the scanner includes two uniaxial scanners, while in other embodiments the scanner is a biaxial scanner. In one embodiment, the scanner is a mechanically resonant scanner. The scanner may be a separate scanner, an acoustic optical scanner, a microelectromechanical (MEMs) scanner, or another type of scanner.

In another embodiment, the scanner may be replaced with a liquid crystal display with an infrared backlight. This LCD is addressed in conventional form according to the image data. When the pixel is operated, the pixel transmits infrared light to the IIT. In response, the IIT outputs visible light to the user.

In another embodiment, the scanner is replaced with an emitter panel of the field emission display. In this embodiment, the IIT cathode can also be removed. The emitter panel then emits electrons directly into NVG's microchannel accelerator. These accelerated electrons activate the cathode light-emitting material of the NVG to produce output light for viewing.

In another embodiment, an invisible radiation source, such as an ultraviolet or infrared light source, emits phosphors. The phosphor then emits light of visible wavelengths. In one embodiment, if the invisible radiation source is infrared, the wavelength is selected in the region determined to be safe for human vision.

In another embodiment of the invention, the display uses multiple invisible radiation sources, such as laser diodes, to drive the wavelength selective phosphor compound on the screen. Each phosphor compound emits visible light at its own visible wavelength in response to a selected one of the light sources. The electronic controller modulates each of the invisible radiation sources in accordance with image information made of an image signal such as a conventional video signal. The scanner then scans the modulated light of all of the light sources over the phosphor compound in a rough stripe pattern. The phosphor compound thus emits light at respective visible wavelengths with an intensity corresponding to the modulated intensity of the corresponding invisible radiation. Each location on the screen thus emits light having the color and intensity indicated by the image signal, producing each pixel of the image.

There are a variety of techniques that allow the user to visually display graphical or video images. Recently, very small displays have been developed for partial or enlarged viewing applications. In such applications, the displays are positioned to produce an image 60 in the partial region 62 of the user's field of view 64, as shown in FIG. Thus, the user can see both the displayed image 66 and the background information 68.

One example of a small display is a scanning beam display as disclosed in US Pat. No. 5,467,104 to Furness et al., Entitled " VIRTUAL RETINAL DISPLAY, " incorporated herein by reference. In scanning displays, a scanner such as a scanning mirror or an acoustooptic scanner scans the modulated light beam onto the retina of the seeker. The scanned light enters the eye through the pupil of the seeker and forms an image on the retina by the cornea. The user perceives an image corresponding to the modulated light image on the retina. Other examples of small displays include small LCDs, field emission displays (FEDs), plasma displays, and small cathode ray tube based displays (CRTs). Such other types of displays are known in the art.

As disclosed herein, such a small display can be made suitable for activating a photoluminescent material to produce visible images at selected wavelengths other than those of the small display. For example, such small displays may activate the cathode light emitting material of the NVG, producing a perceived image that mimics the perceived image when the NVG is used to see a low luminance image environment. The first embodiment of such a system shown in FIG. 4 includes an IR scan light beam display 70 positioned to scan an input beam to NVG 72. In response to the light of the IR display 70, the NVG 72 outputs visible light for the viewer's eye 54 to see. The IR display 70 includes four main parts, each of which is described in detail below.

First, the control electronics 76 provide an electrical signal that controls the operation of the display 70 in response to the video signal V _IM from an image source 78 such as a computer, TV receiver, video cassette player, or other similar device. . Although the block diagram of FIG. 4 shows an image source 78 directly connected to the control electronics 76, one skilled in the art knows another way of coupling the video signal V _IM to the control electronics 76. . For example, when the user wants to use it, the rf transmitter and the receiver may communicate the video signal V _IM as described with reference to FIG. 9. Alternatively, when the control electronics 76 are configured for low power consumption, such as a portable computer, the control electronics 76 are carried by the user and driven by batteries.

The second portion of the display 70 includes a light source 80 that outputs a modulated light beam 82 having a modulation corresponding to information in the video signal V _IM . The light source 80 may include a direct modulated light emitter, such as a laser diode or light emitting diode (LED), or may comprise a continuous light emitter directly modulated by an external modulator, such as an acoustic optical modulator. Preferably, while the light source 80 emits IR or IR near light, other wavelengths may be used for some applications. For example, in some cases NVG 72 may use a phosphor having sensitivity at other wavelengths (eg, visible or ultraviolet light). In such a case, the wavelength of the light source 80 may be selected to correspond to the phosphor.

The third portion of the display 70 is a scanner assembly 84 that scans the modulated beam 82 of the light source 80 through a two-dimensional scan pattern, such as a thin stripe pattern. One example of such a scanner assembly is the same as disclosed in U.S. Patent No. 5,557,444 to Melville et al., Entitled "MINIATURE OPTICAL SCANNER FOR A TWO-AXIS SCANNING SYSTEM," hereby incorporated by reference. Mechanical resonant scanner. However, other scan assemblies such as microelectromechanical (MEMs) scanners and aco-optical scanners are also within the scope of this invention. MEMs scanners are desirable for some applications due to their low weight and small size. Such scanners are uniaxial or biaxial. One example of such a MEMS scanner is disclosed in US Pat. No. 5,629,790 to Neukermans et al. Under the name "MICROMACHINED TORSIONAL SCANNER", which is incorporated herein by reference. Since the light source 80 and the scanner assembly 84 can be operated at relatively low power, the portable battery pack provides the necessary power for the light source 80, the scanner assembly 84, and in some applications the control electronics 76. can do.

The fourth portion of the display 70 is formed of imaging optics 86. Although the imaging optics 86 are represented by a single lens in FIG. 4, as will be appreciated by those skilled in the art, the imaging optics 86 become more complicated, for example, when the beam 82 is focused or shaped. For example, imaging optics 86 may include one or more lenses or diffractive optical elements. In other cases, the imaging optics may be completely excluded or the input lens 88 of the NVG 72 may be used. In addition, when an alternative structure (described later in FIGS. 7 and 8), such as an LCD panel or field emission display structure, replaces the image source 78 and the scanner assembly 84, the imaging optics 86 is a known principle. It may be modified according to.

The imaging optics 86 output the scanning beam 82 over the input lens 88 or directly over the IIT 96 of the NVG 72. The NVG 72 responds to the scanning beam 82 and generates visible light to project into the user's eye 54 as described above.

Although the elements are shown diagrammatically, as will be appreciated by those skilled in the art, components are typically sized and shaped to be mounted directly to NVG 72 as shown in FIG. 5. In this embodiment, the first portion of display 70 104 is mounted to the lens frame 106, and the second portion 108 is supported separately, for example, on the waist belt. The portions 104, 108 are linked by an optical chain and an electron chain 110 that carries optical and electronic signals from the second portion 108 to the first portion 104. An example of a fiber-coupled scan display is disclosed in US Pat. No. 5,596,339 to Furness et al. Entitled "VIRTUAL RETINAL DISPLAY WITH FIBER OPTIC POINT SOURCE", incorporated herein by reference. . As will be appreciated by those skilled in the art, in applications where the control electronics 76 (FIG. 3) are compact, the light source may be incorporated into the first portion 104 and the chain 110 may be excluded.

When the first portion 104 is mounted to the lens frame 106, the lens frame 106 connects infrared light to the IIT 112 at the first portion. IIT 112 converts infrared light into visible light presented to the user by eyepiece 114.

6 shows one embodiment of a mechanically resonant scanner 200 suitable for use with the scanner assembly 84. The resonant scanner 200 includes a horizontal scanner 201 including a moving mirror 202 mounted to the spring plate 204 as a main horizontal scanning element. The dimensions of the mirror 202 and the spring plate 204 and the material properties of the spring plate 204 are selected such that the mirror 202 and the spring plate 204 have a natural vibration frequency of 1-100 Hz. The ferromagnetic material mounted to the mirror 202 is driven by a pair of electromagnetic coils 206 and 208 to provide the driving force to the mirror 202 to initiate and maintain vibration. Drive electronics 218 provide electrical signals for actuating coils 206 and 208.

Vertical scanning is provided by a vertical scanner 220 configured very similarly to the horizontal scanner 201. Like the horizontal scanner 201, the vertical scanner 220 includes a mirror 222 driven by a pair of coils 224, 226 in response to an electrical signal from the drive electronics 218. However, since the oscillation speed is much lower for vertical scanning, the vertical scanner 220 typically does not resonate. Mirror 222 receives light from horizontal scanner 201 and causes vertical deflection at about 30-100 Hz. Advantageously, at lower frequencies the mirror 222 can be significantly larger than the mirror 202, thus reducing the difficulty in positioning the vertical scanner 220.

Details of the virtual retina display and mechanical resonant injection are described in US Pat. No. 5,557,444 to Melville et al. Under the name "MINIATURE OPTICAL SCANNER FOR A TWO AXIS SCANNING SYSTEM", hereby incorporated by reference. It is disclosed in more detail in the call.

As an alternative, a vertical mirror can be mounted on a pivoting shaft and driven by an induction coil. Such injection assemblies are commonly used in bar code scanners. As discussed below, in some applications, vertical and horizontal scanners may be combined into a single biaxial scanner.

In operation, the light source 80 driven by the image source 78 (Fig. 4) outputs a light beam modulated according to the video signal. At the same time, the drive electronics 218 activate the coils 206, 208, 224, 226 to vibrate the mirrors 202, 222. The modulated light beam strikes the vibrating horizontal mirror 202 and is then horizontally deflected by an angle corresponding to the instantaneous time of the mirror 202. This deflected light strikes the vertical mirror 222 and then is deflected at a vertical angle corresponding to the instantaneous time of the vertical mirror 222. The modulation of the light beam is synchronized with the horizontal and vertical scans so that the beam color and intensity at each of the mirror positions correspond to the desired image. Therefore, the beam “draws” a virtual image directly on the IIT 112 (FIG. 4). As will be appreciated by those skilled in the art, several components of the scanner 200 have been omitted for brevity of representation. For example, vertical and horizontal scanners 201 and 220 are typically mounted at fixed relative positions relative to the frame. Additionally, the scanner 200 typically includes one or more pivoting mirrors so that the beams strike each mirror 202.222 at an appropriate angle. For example, when the turning mirror sends a beam, the beam hits one or both of the mirrors 202 and 222 several times to increase the effective angle range of the optical scan.

As will be appreciated by those skilled in the art, various image sources such as LCD panels and field emission displays are suitable for use in place of scanner assembly 84 and light source 80. For example, another embodiment of the NVG simulator 600 as shown in FIG. 7 is formed of an LCD panel 602, an IR backlight 604, and an NVG 72. The IR backlight 604 is formed of an IR source array 606, a back reflector 608, and a diffuser 610, such as an LED or laser diode. Those skilled in the art will appreciate many other structures that can provide infrared or other light for spatial modulation by the LCD panel.

The LCD panel 602 is structurally similar to a conventional polarization-based LCD panel except that the characteristics of the liquid crystal and polarizer are adjusted to respond to the IR wavelength. LCD panel 602 is addressed in a conventional manner to activate each location within a two-dimensional array. In places where the image is intended to contain IR light, the LCD panel selectively passes IR light from the backlight 604 to the NVG 72. The NVG 72 responds as described above by emitting visible light to be projected into the user's eye 54.

As shown in FIG. 8, another embodiment in accordance with this invention provides an input to NVG 72 using a field emission display structure. In this embodiment, emitter panel 802 receives control signals from FED drive electronics 804 and emits electrons in response. Emitter panel 802 may be a known emitter panel such as used in commercial field emission displays. The typical emitter panel structure shown in FIG. 8 is formed of an array of emitter sets 806 aligned with the extraction grid 808. Typically the emitter sets 806 are a group of one or more commonly connected radioactive discontinuities or "tips" that emit electrons when subjected to a high electric field. Extraction grid 808 is a conductive grating of one or more conductors. The emitter set 806 emits electrons as the drive electronics 804 induces a voltage difference between the peripheral area of the extraction grid 808 and the emitter set 806. By selectively controlling the voltage between each emitter set 806 and the periphery of the grid 808, the drive electronics 804 can control the location and speed of the electrons being emitted.

The high voltage anode 810 supported by the transparent plate 812 attracts the emitted electrons. As the electrons move to the transparent plate 812, they hit the cathode luminescent coating 814 covering the anode 810. In response, cathodic luminescent coating 814 emits infrared light in the impact zone, the intensity of which corresponds to the rate at which electrons strike the impact zone. The infrared light passes through the transparent plate 812 and enters the NVG 72. The drive electronics 804 determine the speed and location of the emitted electrons according to the image signal, so that the infrared light corresponds to the image signal. As before, NVG 72 emits visible light in response to infrared light to be projected into the user's eye 54.

As shown in FIG. 9, participant 900 may use display 70 of FIG. 5 in a simulated environment that allows for virtually unlimited workouts. In this embodiment, as participant 900 wears display 70, second portion 108 is secured around the waist and first portion 104 is mounted to head wear NVG 72. Additionally, the first portion 104 includes a position monitor 906 and a gaze tracker 908 that identify the location of the participant in the environment and the direction of the user's gaze.

Those skilled in the art know a number of feasible position trackers such as acoustic sensors and optical sensors. Moreover, although participant 900 is shown wearing position monitor 906, position monitor 906 may be fixedly positioned within or around the environment or may include a movable portion and a fixed portion. Similarly, various eye tracking structures can be used. In the embodiment of FIG. 9, the gaze tracker utilizes multiple reference reflectors 910 located throughout the environment 902 or above the participant 900. To detect the position, the eye tracker 908 emits one or more IR beams into the environment 902. IR beams may be generated by the image source 78 or at separate IR sources mounted to the first portion 104. The emitted IR beams strike and reflect the reference reflector 910. Since each reference reflector 910 has a clear and identifiable pattern of spatial reflectivity, this reflected light is modulated into a pattern corresponding to the particular reference reflector 910. The detector mounted on the first portion 104 receives the reflected light to generate an electrical signal representing the reflection pattern of the reference reflector 910. Chain 110 carries this electrical signal to second portion 108.

The second portion 108 includes an rf transceiver 904 with a mobile antenna 905 that sends data corresponding to the detected reflected light and state information to the electronic controller 911. The electronic controller 911 is a microprocessor-based system that determines a desired image under the control of a software program. The controller 911 receives information about the participant's location, status, and gaze direction from the transceiver 904 via the base antenna 907. In response, the controller 911 identifies the appropriate image data and sends this image data to the transceiver 904. The second portion 108 then sends signals to the first portion 104 via the chain to cause the scanner assembly 84 and the image source 78 to provide an IR input to the NVG 72. Thus, the participant 900 recognizes images corresponding to the participant's position and gaze direction through the NVG 72.

To allow external monitoring of activities in the environment, the display 912 coupled to the electronic controller 911 shows an image of the environment as viewed by the participant 900. Scenario input devices 914, such as CD-ROMs, magnetic disks, video tape players, or similar devices, and data input devices 916, such as keyboards or voice recognition modules, so that operations within the environment 902 are as desired. Can be adjusted and deformed.

The embodiments herein are described as using scanned infrared light, but this invention is not necessarily so limited. For example, in some cases it may be desirable to scan ultraviolet light or visible light over a photoactivated screen. Ultraviolet light scanning can be particularly useful for injecting known up-converting phosphors, or for injecting phosphors that are commonly found in fluorescent lamps.

One example of such a structure is shown in FIG. 10, where the scanning beam display 1000 is formed of a UV light source 1002 aligned to the scanner assembly 1004. The UV light source 1002 may be a discrete laser, laser diode or LED emitting UV light.

The control electronics 1006 drives the scanner assembly 1004 through a rough thin stripe pattern. Additionally, control electronics 1006 activates UV light source 1002 in response to video signals from video input devices 1008 such as computers, rf receivers, FLIR sensors, video cassette recorders, and other conventional devices. .

The scanner assembly 1004 is positioned to scan the UV light of the UV light source 1002 onto the screen 1010 formed of the glass or plexiglass plate 1012 coated with the phosphor layer 1014. In response to incident UV light, phosphor layer 1014 emits light of a wavelength visible to the human eye. The intensity of this visible light will correspond to the intensity of the incident UV light, and then the intensity of the incident UV light will correspond to the image signal. Thus, the viewer recognizes the visible image corresponding to the image signal. As will be appreciated by those skilled in the art, the phosphor layer 1014 emits light over a large range of angles, such that the screen 1010 effectively acts as an exit pupil expander that facilitates the capture of an image by the user's eye. increase the effective numerical aperture.

In addition to the scanned UV source, the embodiment of FIG. 10 also includes a visible light source 1020, such as a red laser diode, and a second scanner assembly 1022. The control electronics 1006 controls the second scanner assembly 1022 and the visible light source 1020 in response to the second image signal from the second image input device 1024.

In response to the control electronics, the second scanner assembly 1022 scans visible light onto the screen 1010. However, the phosphor is chosen not to emit light of other wavelengths in response to visible light. Instead, phosphor layer 1014 and plate 1012 are configured to diffuse visible light. The phosphor layer 1014 and the plate 1012 thus operate in the same manner as commercially available diffusers, allowing the viewer to see a red image corresponding to the second image signal.

In operation, the UV and visible sources 1002 and 1020 produce two separate images that can be activated independently and superimposed. For example, in an airplane, the UV light source 1002 may present various data or text from a sensor such as an altimeter, but the visible light source 1020 may be activated to display a FLIR alert.

Although the display of FIG. 10 is shown to include two separate scanner assemblies 1004, 1022, one of ordinary skill in the art would appreciate that a single scanner assembly can scan both UV and visible light by aligning two sources into the same scanner assembly. I will understand that. Those skilled in the art will also understand that this invention is not limited to UV and visible light. For example, when infrared phosphors or other IR sensitive components are used, the light sources 1002 and 1020 may be two infrared sources. Alternatively, light sources 1002 and 1020 may include infrared and visible light sources or infrared and UV sources.

Scanning light of a first wavelength onto a wavelength converting medium, such as a phosphor, is not limited to night vision applications. For example, as shown in FIG. 11, a scanning light beam head wearable display (HMD) 1100 includes a phosphor plate 1102 that is activated by the scanning light beam 1104 to produce a perspective image for a user. The HMD 1100 may be used as a general-purpose display rather than a night vision aid.

In this embodiment, the HMD 1100 includes a frame 1106 that is configured similar to conventional eyewear so that a user can comfortably wear the HMD 1100. The frame 1106 supports the fluorescent plate 1102 and the image source 1108 in a relatively aligned manner so that the light beam strikes the fluorescent plate 1102. The image source 1108 includes a direct modulation laser diode 1112 and a small scanner 1110 such as a MEMs scanner operating under the control of the electronic control module 1116. Laser diode 1112 preferably emits invisible radiation, such as infrared or ultraviolet light. However, other wavelengths, such as red or near UV, may be used for some applications.

The scanner 1110 is a biaxial scanner that receives the light of the diode 1112 and sends it back over the phosphor plate 1102 through a roughly striped pattern. In response to the scanning beam 1104, the phosphor on the phosphor plate 1102 emits light of visible wavelengths. This visible light goes to the user's eye 1114 and the user observes an image corresponding to the modulation of the scanning beam 1104.

The image may be color or black and white depending on the pattern of the phosphor plate. In the case of a color display, the fluorescent plate 1102 includes rows with a certain gap, and each row contains its own phosphor configured to emit light of red, green or blue wavelengths as shown in FIG. The control module 1116 controls the relative intensity of the scanning light beam for each location to generate the appropriate levels of red, green and blue light for each pixel.

To maintain synchronization of the light beam modulation and side position, the HMD 1100 uses active feedback control in which one or more sensor high speed photodiodes 1118 are installed adjacent to the scanner 1110. The small reflector 1120 mounted on the phosphor plate 1102 returns the end of the scanning beam 1104 to the photodiode 1118 at the end of each horizontal scan. In response to the reflected light, the photodiode 1118 provides the control module 1116 with an electrical error signal indicative of the phase relationship between the beam position and the beam modulation. In response, the control module 1116 adjusts the timing of the image data and ensures that the diode 1112 is properly modulated at each scan location.

Another method for generating images of different colors with phosphors is presented in FIG. 12. The display 1150 of FIG. 12 includes a multiwavelength source 1152 that provides optical input to the scanner 1154. In turn, the scanner 1154 scans light onto the screen 1156 coated with the wavelength selective phosphor layer 1158.

Multi-wavelength source 1152 is formed of four IR laser diodes 1160 emitting light of slightly different wavelengths. For example, in one application the laser diode 1160 emits light at wavelengths over a range of 900-1600 nm. Each of the laser diodes 1160 is a driver circuit 1164 in response to selected components of the input video signal V _IM from a signal source 1166, such as a TV receiver, a computer, a video cassette receiver, a flight control system, and some other type of image source. Are driven independently. The driver circuit 1164 extracts selected components such as RGB components of the image signal V _IM and provides corresponding electrical signals to the respective laser diodes 1160. In response to each electrical signal, each laser diode 1160 emits infrared light of a corresponding intensity level.

Beam combiner 1162 combines the light from laser diode 1160 to produce a single beam comprising intensity modulated light of four different wavelengths λ ₁ -λ ₄ . The scanner 1154 scans this combined beam in the form of a horizontal stripe on the screen 1156.

The combined beam hits the phosphor layer 1158 so that light is emitted at each location. Phosphor layer 1158 includes a plurality of wavelength selective phosphor combinations, each phosphor combination emitting light at its own visible wavelength in response to each of wavelengths λ ₁ -λ ₄ . These phosphors have been demonstrated by SRI and are available from SRI and Kodak. For example, the first of the phosphor combinations emits green light in response to light of the first IR wavelength λ ₁ . The intensity of this green light corresponds to the light intensity of the first IR wavelength λ ₁ , and then the light of the first IR wavelength λ ₁ corresponds to the green component of the video signal V _IM . Because IR light of various wavelengths is scanned simultaneously, and because the visible colors depend on the intensity of the respective wavelength component rather than the beam position, the alignment issues described for the embodiment of FIG. 11 are significantly reduced.

This embodiment has been described as including four independent laser diodes 1160, but the invention is not so limited. For example, other infrared sources such as LEDs may be suitable for certain applications. Similarly, the number of laser diodes 1160 may be four or more or less. In a typical RGB system, the number of laser diodes 1160 is typically three. However, other numbers may be appropriate depending on the spectral response or other response of the phosphor conjugate and the desired information content of the displayed image. Moreover, although beam coupler 1162 is presented as a four-to-one-fiber combinier, other beam combiners such as free-space optics, integrated optics, or polymer waveguides may be used. . In some applications, light modulators such as interferometric modulators may be incorporated into the beam combiner 1162 such that the laser diodes are driven at a constant intensity. Additionally, although the exemplary embodiment includes a single scanner 1154 that scans all three wavelengths of light, the present invention is not so limited. In some applications more than one scanner 1154 may be used.

In order to reduce the size and load of the first portion 104, it is desirable to reduce the size and load of the scanning assembly 58. One way to reduce size and load is to replace the mechanical resonant scanners 200 and 220 with microelectromechanical (MEMS) scanners as disclosed in the following US patent. Named US Patent No. 5,629,790 issued to Neukermans et al. Under the name MICROMACHINED TORSIONAL SCANNER, each of which is incorporated herein by reference. A biaxial scanner 1200 is formed on a silicon substrate 1202 as disclosed herein and shown in FIG. Biaxial scanner 1200 includes mirror 1204 supported by both curved portions 1206 that link mirror 1204 to pivotable support 1208.

Since the curved portion 1206 is to be twisted and turned, the mirror 1204 is rotated about the support 1208 about the axis defined by the curved portion 1206. In one embodiment, the rotation of the mirror 1204 defines a horizontal scan of the scanner 1200.

The second pair of curved portions 1212 couple the support 1208 to the substrate 1202. Since the dimensions of the curved portion 1212 are to be twisted and bent, the support 1208 pivots relative to the substrate 1202. Preferably, in selecting the mass and dimensions of the mirror 1204, support 1208 and bend 1212, the mirror resonates horizontally at 10-40 Hz at high Q and the support 1208 pivots at 60 Hz or more. do.

In a preferred embodiment, the mirror 1204 is pivoted by applying an electric field between the plate 1214 on the mirror 1204 and the conductor on the base (not shown). This is called capacitive drive because plate 1214 acts as one plate of capacitor and the conductor in the base acts as the second plate. As the voltage between the plates increases, a force is applied to the mirror 1204 by the electric field so that the mirror 1204 pivots about the bend 1206. The mirror 1204 periodically scans by periodically changing the voltage applied to the plates. Preferably, since the voltage changes at the mechanical resonance frequency of the mirror 1204, power consumption is reduced in vibration of the mirror 1204.

The support 1208 is pivoted magnetically in accordance with the requirements of the particular application. A stator magnet 1205 is positioned around the support 1208 and a conductive path 1207 on the support 1208 carries current. Changing the current causes the magnetic force to change at the support, which causes movement. Preferably, the support 1208 and the bend 1212 are sized so that the support 1208 can respond at frequencies above the desired refresh rate of about 60 Hz. Those skilled in the art will appreciate that a capacitive or electromagnetic drive may be applied to pivot both the mirror 1204 and the support 1208 and other drive mechanisms such as piezoelectric drives may be applied to pivot the mirror 1204 or the support 1208. Will recognize.

While the invention has been disclosed herein by way of example embodiments, the structures and methods disclosed herein may vary within the spirit and scope of the invention. For example, the positions of the various components will change. In one example of repositioning, the UV source 1002 and the visible source 1020 may be positioned on either side of the screen 1010. Moreover, although the horizontal scanner 200 is described as preferably mechanically resonating at the scanning frequency, the scanner 200 may be non-resonant in some applications. For example, if the scanner 200 is used for "stroke" or "calligraphic" scanning, a non-resonant scanner would be better. Furthermore, although the input signal is disclosed as originating from an electronic controller or a predetermined image input, those skilled in the art may provide a video signal by a portable video camera (either alone or in combination with the electronic controller). It will be appreciated that this configuration is particularly useful in simulation environments involving multiple participants since each participant's video camera can provide local video input, thus reducing the complexity of the control system. Accordingly, this invention is limited only by the appended claims.

Claims (31)

In the display for generating a visible image in response to an input video signal having a plurality of components, A base plate and a wavelength conversion coating sensitive to output light in the first visible wavelength range in response to light of the first input wavelength, and output light in the second visible wavelength range in response to light in the second input wavelength. Screen included, A first light emitter operative to emit modulated light of the first input wavelength in response to a first component of the video signal; A second light emitter operative to emit modulated light of the second input wavelength in response to a first component of the video signal; An input is optically aligned to receive light from the first and second light sources, an output is optically aligned to send light received at the input to the screen, and in response to a drive signal to receive the received light A display comprising a scanner assembly for scanning in a periodic pattern over a wavelength conversion coating. The method according to claim 1, Wherein the first input wavelength is an invisible wavelength. The method according to claim 2, Wherein the first input wavelength is an invisible wavelength. The method according to claim 1, And the scanner assembly includes a mirror mounted to pivot about an axis of rotation. The method according to claim 1, The scanner assembly includes a microelectromechanical scanner having a mirror positioned to deflect light received at the input. The method according to claim 1, The wavelength conversion coating comprises a first infrared sensitive phosphor compound, wherein the first input wavelength is an infrared wavelength. The method according to claim 1, The wavelength conversion coating comprises a second infrared sensitive phosphor compound sensitive to the second input wavelength. The method according to claim 1, Wherein the first light source is a first laser diode. The method according to claim 8, And the first light source comprises an external modulator. The method according to claim 8, And the second light source is a second laser diode. The method according to claim 1, A beam coupler sandwiched between the scanner assembly and the first and second light sources, the beam combiner having a first input aligned with the first light source, a second input aligned with the second light source, and And a combiner output aligned to the scanner assembly, wherein the combiner is sensitive to produce a single combined beam from the modulated light of the first wavelength and the modulated light of the second wavelength. A video signal source for generating a video signal corresponding to a desired video; A screen having a wavelength conversion coating that emits visible light in response to invisible radiation; A light source emitting invisible radiation modulated according to the video signal in response to the video signal; A scanner positioned to receive the modulated light and operative to scan the received light in a periodic pattern on the screen. The method according to claim 12, And the light source comprises a first infrared laser operative to emit light in a first wavelength range. The method according to claim 13, Wherein the light source comprises a second infrared laser operative to emit light in a second wavelength range that is different from the first range. The method according to claim 14, And the wavelength conversion coating emits visible light of a first color in response to light in the first wavelength range, and emits visible light of a second color different from the first color in response to light in the second wavelength range. The method according to claim 12, And wherein said wavelength converting coating comprises a plurality of phosphor combinations, each of which emits light of visible wavelengths in response to invisible light of respective wavelengths. The method according to claim 12, And the scanner is a MEMS scanner. The method according to claim 12, The scanner includes a resonant scan portion. The method according to claim 12, Wherein said periodic pattern is an approximately fine striped pattern. Generating light of a first invisible wavelength; Generating light of a second invisible wavelength; Modulating light of the first invisible wavelength into a first portion of image information; Modulating light of the second invisible wavelength into a second portion of the image information; Scanning the light of the first invisible wavelength in a periodic pattern; Scanning the light of the second invisible wavelength in a periodic pattern; Converting the scanned light of the first invisible wavelength into light of a first visible wavelength; Converting the scanned light of the second invisible wavelength into light of a second visible wavelength; And And transmitting the converted light of the first and second visible wavelengths to a user. The method of claim 20, Modulating the light with the image information Emitting continuous wave light of the first invisible wavelength to a light source; And modulating the continuous wave light with an external amplitude modulator separate from the light source. The method of claim 20, Scanning the light of the first invisible wavelength in a periodic pattern comprises sending the light of the first invisible wavelength through an approximately thin stripe pattern. The method according to claim 22, Directing the light of the first invisible wavelength through a substantially fine stripe pattern comprises returning the light of the first invisible wavelength to a scanning mirror. The method of claim 20, And converting the scanned light of the first invisible wavelength into light of the first visible wavelength comprises shining the scanned light onto a phosphor combination. The method of claim 20, Combining the light of the first and second invisible wavelengths prior to scanning the light of the first and second invisible wavelengths. The method of claim 20, Generating light of the first invisible wavelength comprises activating a laser diode. The method of claim 26, And modulating the light of the first invisible wavelength into a first portion of the image information comprises modulating a drive current with a laser diode. Generating a first electrical video signal corresponding to the first portion of the image to be viewed; Generating a second electrical video signal corresponding to the first portion of the image to be viewed; Applying the first video signal to a first image source; Applying the second video signal to a second image source; Emitting infrared light of a first wavelength range in response to the popular first image signal; Emitting infrared light having a second wavelength range different from the first wavelength range in response to the applied second image signal; Sending the emitted infrared light of the first wavelength to a wavelength converting material; Sending the emitted infrared light of the second wavelength to a wavelength converting material; Emitting visible light of a first visible wavelength to the wavelength converting material in response to the emitted light of the first wavelength; And Emitting visible light of a second visible wavelength to the wavelength converting material in response to the emitted emission light of the second wavelength. The method according to claim 28, Sending the emitted infrared light of the first wavelength to a wavelength converting material comprises scanning the infrared light of the first wavelength through an approximately thin stripe pattern. The method of claim 29, Sending the emitted infrared light of the second wavelength to a wavelength converting material comprises scanning the infrared light of the second wavelength through an approximately thin stripe pattern. The method of claim 30, Scanning the infrared light of the first wavelength through an approximately thin stripe pattern Sending infrared light of the first wavelength onto a scanning mirror; Pivoting the scan mirror through a periodic scan pattern.