Light modulating eyewear assembly

[0002] The present invention relates generally to eyewear, especially liquid crystal eyewear, whose light transmissivity can be varied and more particularly to eyewear whose transmissivity can be varied in response to and as a function of directionally controlled ambient light and still more particularly to eyewear of this type in which its light transmissity can also be varied in response to and as a function of the light intensity of a cooperating head mounted display, a computer display or other such display which is used outdoors.

[0003] Liquid Crystal eyewear used as light variable sunglasses are known in the art. For example, see for example U.S. Pat. No. 5,952,988 that issued to Moddel and that is incorporated herein by reference. This particular design and others in the art use a photo-detector to measure the ambient light reaching the glasses and changes in light transmissivity depending on the ambient light level. A problem with these different eyewear designs is that they respond generally to the surrounding ambient light. Thus, if it is a sunny day but the user, who is standing in the sun, is looking into the shade, the surrounding light will cause the eyewear to darken making it more difficult to see into the shade. As will be seen hereinafter, the present invention solves this problem by making the eyewear respond directionally to the ambient light and, thus, provides an advantage to the user who wished to focus his or her attention in a specific direction.

[0004] Another advantage of the present invention, as will also be seen, is its use with head mounted displays and computers intended to be used in ambient light of varying intensity, for example outdoors. The eyewear is designed in accordance with the present invention such that its light transmissivity is, at least in part, made responsive to and a function of the general light level of the display. Thus, in the case of, for example, a head mounted display in which the user views the display with one eye outdoors, the other eye which would otherwise be subject to the variability of ambient outdoor light can be protected by the eyewear. That is, the eyewear in accordance with the present invention can be controlled in cooperation with the head mounted display so that the light intensity reaching both eyes of the user are approximately the same.

[0005] As will be disclosed in more detail herein after, the present invention, in accordance with one embodiment provides for a light modulating cell assembly especially suitable as eyewear, comprising: (a) a light modulating cell arrangement including a light modulating medium, preferably liquid crystal, positionable in front of the eye of a user and configured so as to be able to change the state of its light modulating medium in a way which changes the transmissivity of light passing through the light modulating medium from the ambient surroundings before reaching the eye; (b) a light transmissivity control arrangement including a light detector for changing the light modulating state of said light modulating medium, at least in part, in response to and as a function of the level of light reaching said detector from the ambient surroundings; and (c) a light blocking arrangement at least partially surrounding said detector for allowing only light from a limited range of ambient directions to directly reaching said detector.

[0006] In accordance with another embodiment there is provided a light modulating cell assembly especially suitable for use for eyewear and for use with a head mounted display or a computer display having its own light intensity, comprising: (a) a light modulating cell arrangement including a light modulating medium, again preferably liquid crystal, positionable in front of the eye of a user and configured so as to be able to change the state of its light modulating medium in a way which changes the transmissivity of light passing through the light modulating medium from the ambient surroundings before reaching the eye; and (b) a light transmissivity control arrangement including auxiliary means for controlling the state of said light modulating medium such that the light passing through the light modulating medium from the ambient surroundings is maintained at a controlled intensity, at least in part, in response to and as a function of the light intensity of said display and so long as the ambient light which would otherwise reach said light detector does not drop below that intensity.

[0007] In the drawings:

[0008] FIG. 1 is a diagrammatic illustration of liquid crystal eyewear in accordance with the present invention;

[0009] FIG. 2A is an enlarged diagrammatic illustration of a feature of the eyewear of FIG. 1, specifically of its photocell arrangement constructed in accordance with the present invention to provide light directionality to the eyewear;

[0010] FIGS. 2B-2D are further embodiments of the arrangement of FIG. 2B; and

[0011] FIG. 3 is a diagrammatic illustration of liquid crystal eyewear designed in accordance with the present invention to cooperate with a head mounted display, a computer display or a like displays.

[0012] FIG. 4 is a diagrammatic illustration of liquid crystal eyewear in accordance with still another embodiment of the present invention.

[0013] Turning now to the drawings, attention is first directed to FIG. 1 which discloses eyewear, specifically a pair of liquid crystal eyewear 10 designed in accordance with the present invention. With the exception of the present invention, the eyewear 10, may be like those in the above recited patent application or they may be conventional and readily provide by those with ordinary skill in the art. Thus, they include a frame 12 including wearing stems 14. Eyewear 10 also include a liquid crystal cell arrangement 16 including liquid crystal material 18. While not shown, the liquid crystal cell arrangement 16 includes other typical components necessary to make it work in the intended manner including a suitable light detector 20.

[0014] A typical pair of liquid crystal eyewear 10 operates to vary the light passing there through from the ambient surrounding to the user's eyes 22. Thus, as seen in FIG. 1, bright ambient light 24 is attenuated by the liquid cell arrangement 16 so that less intense light 26 reaches eyes 22. This is because the light detector 20 detects the bright light 24 and causes arrangement 16 to lighten or darken its liquid crystal material 18 in some pre-configured proportion to the brightness of light 24. The opposite is also true. That is, if the ambient surroundings are relatively dark, for example when the user walks into a shadow, the light detector 20 detects this and through its cooperating readily providable circuitry (not shown) causes arrangement 16 to lighten its liquid crystal material 18.

[0015] In accordance with one aspect of the present invention eyewear 10 also includes a light blocking arrangement 28 shown in FIG. 2A. This arrangement 28 is configured to allow only light from a limited range of ambient directions to directly reach the detector's active surface 30. In this particular embodiment, the light blocking arrangement 28 is designed as an open ended cone with the smaller of the open ends resting against and surrounding surface 30 such that the axis 32 of the cone is normal to surface 30. In this way, only ambient light within the acceptance angle A of the cone will reach the surface 30 directly, that is, without reflecting off the inner wall of light blocking arrangement 28. In this way, if the user has his or her back or side to the sun or the sun is overhead and is looking into the shade, for example, less light will impinge on surface 30 than would be the case without arrangement 28 and eyewear 10 will remain lighter (more light transparent) than would otherwise be the case, thereby allowing the user to see better. This certainly is advantageous for a user of the liquid crystal eyewear 10 who happens to be operating a laptop computer at a table outside with the sun shining down. But for the light blocking arrangement 28, the eyewear 10 might be darker than it would otherwise be without arrangement 28, making it more difficult for the user to view the computer's display.

[0016] After having actually tested light blocking arrangement 28 with a number of different acceptance angles, it was found that the most ideal angle for acceptance angle a is about 40°. One reason for this is as follows. Without eyewear 10, if a visual image, as viewed by an individual, contains excessive bright regions within this acceptance region, they can be disturbing to the viewer. However, bright regions outside this 40° acceptance angle are not nearly as bothersome to the viewer, with or without eyewear 10.

[0017] Indeed, applicants have found not only that angle a is ideally 40° but that the entire cone should be tilted downward about 10°. Thus, a second light blocking arrangement 34, tilted downward about 10°, is shown in FIG. 2B. In this case angle a remains at 40° and angle b, the tilt angle, is 10°. Clearly, it is to be understood that the generally cone shaped configurations of arrangement 28 and arrangement 34 do not have to be circular cones shapes but could take on various other shapes, for example, they could be oval, square, rectangular or the like, so long as they functioned in the manner described. Also, rather than a generally cone shaped configuration, the light blocking arrangement could be constructed of an array of louvered shutters, as in the case of arrangement 36 in FIG. 2C or any other mechanical light blocking shape. Also, it could operate to block light from active surface 30 by means of an optical lens. Such an arrangement 38 is shown in FIG. 2D. In this case, one with ordinary skill in the optics art could readily design an appropriate light blocking lens to serve as arrangement 38 and function to allow only light within the appropriate acceptance angle a to reach surface 30.

[0018] As indicated above, the light detector 20 detects the bright light 24 and causes arrangement 16 to lighten or darken its liquid crystal material 18 in some pre-configured proportion to the brightness of light 24. Typically, this is done in relatively real time in direct proportion, for example in linearly proportion with the brightness of light 24. Specifically, as the light 24 increases and decreases in brightness, as detected by light detector 20, the liquid crystal eyewear 10 respectively darkens and lightens linearly proportionately and as the brightness changes, in other words, in real time. However, while eyewear 10 can also operate in this way, in accordance with another aspect of the present invention, it is provided with delay circuitry so as not to flicker back and forth between brightness levels if the eyewear 10 is subjected to rapid changes in brightness such as, for example, the strobe effect that occurs when the user rides under trees. In this and similar cases, the delay prevents the eyewear 10 from switching back and forth. If this effect is short lived, eyewear 10 remains at the level it was at the beginning of the strobe effect. On the other hand, if the strobe effect continues, the eyewear 10 is provided with light integrating circuitry which averages the light and dark extremes reaching its light detector 20 so that the eyewear 10 stays at a generally constant level somewhere between the extremes. FIG. 3 illustrates this particular configuration with both the delay and integration features as eyewear 10′ generally. Eyewear 10′ includes the same liquid crystal cell arrangement 16 and frame 12 as well as light detector 20, as illustrated diagrammatically in FIG. 3. However, the circuitry 40 cooperating with detector 20 to drive the liquid crystal cell arrangement 16 in response to and as a function of the light received at detector 20 includes all of the circuit components including a delay circuit and an integration circuit to operate eyewear 10′ in the manner just described. While circuitry 40 is not shown in detail, it will be appreciated that one with ordinary skill in the art, in view of the teachings herein, would be able to readily provide necessary circuit components.

[0019] Still referring to FIG. 3, Circuitry 40 can also be readily provided in accordance with still another aspect of the present invention with a circuit that insures that the transmissivity of liquid crystal cell arrangement 16 remains at a pre-adjusted constant intensity. In this way, the constant intensity can be selected to correspond to that of a head mounted display, a computer display or the like which generally operates at an approximately constant intensity. In this way, the eyewear 10′, in this case operating as a monocle, could be used by one eye of the user so as to control the ambient light while viewing the display. Obviously, this assumes that the ambient light does not drop in intensity below the pre-adjusted level.

[0020] Referring now to FIG. 4, still another eyewear embodiment is illustrated, specifically eyewear 10″. Like the earlier described embodiments, this one includes the same arrangement 16 and frame 12. It does not necessarily require a light detector 20 but does include circuitry 40′ which connects with both arrangement 16 and a display 42, for example a head mounted display, a computer display or the like, as shown in FIG. 4. This circuitry 40′ includes the necessary circuit components to insure that the transmissivity of arrangement 16 tracks that of the display. While circuitry 40′ is not shown in detail, it will be appreciated that one with ordinary skill in the art, in view of the teachings herein, would be able to readily provide necessary circuit components.

[0021] In all of the cases described above, the eyewear described includes a light transmissivity modulating means in the form of a liquid crystal cell arrangement. It is to be understood that other modulators could be provided such as electrochromic and suspended particle devices. Also, while only the mechanical cone was shown in both on-axis and tilted axis positions, it is to be understood that other embodiment shown on-axis could readily be provided in tilted position similar to FIG. 2B.