The field of the invention is that of display systems carried by the head of a user. These systems enable in particular the display of information superimposed on the outside view. They are notably known as see-though head-mounted display (HMD) systems. They can be monocular or binocular. They are used in various applications. There may be cited their use in the cockpits of civil and military aircraft where they are used to present to the pilot essential information concerning piloting or navigation.
These HMD generally display virtual information at a given fixed distance from the user. This method has a number of disadvantages:
When a person looks at an object, by deformation of the crystalline lens each eye accommodates on the object to see it clearly. The two eyes converge simultaneously toward the object. The brain merges the two images coming from the left eye and the right eye in order to see only one non-duplicated object.
When a virtual image is presented to the user in binocular mode in the binocular HMD 1, there can be a difference between the projection distance of the image, which is conventionally at optical infinity for aeronautical applications, and the real distance of the element of the outside view onto which the displayed image is superimposed. Thus in
Of course, the angular differences between the perceived images are smaller than is shown diagrammatically in
Different technical solutions have been proposed to overcome these different problems. The US application 2013/0088413 entitled “Method to Autofocus on Near-Eye Display” describes a display system in which the distance of the virtual image is adjustable, this distance being a function of the distance of the real objects in the outside view. This latter distance is determined either by an autofocus system as found in still cameras and video cameras or by a distance measuring system that functions by emitting optical or ultrasound signals. However, these various means for determining the distances of the various real objects of the outside view cannot tell which object the user is actually looking at.
The US application 2013/0241805 entitled “Using convergence angle to select among different UI elements” describes a display system including an eye-tracker enabling the angle of convergence between the two eyes of the user to be determined, the objects looked at to be deduced from this, and virtual images to be displayed accordingly. However, the virtual image always remains displayed at the same distance.
Thus these two technical problems do not make it possible to solve completely the problem raised by the superimposition of a virtual image on a real object.
The head-mounted display system in accordance with the invention combines and adds to the above two systems to obtain a system that simply and optimally corrects both the accommodation problem and the binocular merging problem. There is then no longer any visual perception conflict between the view and the information displayed by the display system. The observer sees clearly the HMD image or images and the outside view, with no image duplication. To be more precise, the invention consists in a head-mounted display system intended to be worn by a user, said display system being monocular and including at least one display device, an eye-tracker and graphic generator means, the display device including a display, a collimator optic and an optical combiner enabling an image from the display to be superimposed on an outside view, characterized in that:
the eye-tracker includes means for determining the angle of convergence of the two eyes of the user and the resulting accommodation;
the collimator optic includes means for projecting the image produced by the display at a distance that is a function of said accommodation;
the graphic generator means enable said image to be displayed at a position that is a function of said accommodation.
Said system is advantageously binocular and includes at least one second display device, the second display device including a second display, a second collimator optic and a second optical combiner enabling a second image from the second display to be superimposed on the outside view, the second collimator optic including means enabling the image from the second display to be projected at a distance that is a function of said accommodation and the graphic generator means enabling the second image to be displayed at a position that is a function of said accommodation.
Said display system advantageously includes a second eye-tracker, the two eye-trackers including means for determining the angle of convergence of the two eyes of the user and the resulting accommodation.
The information from the eye-tracker or eye-trackers is advantageously used to modify the parameters of the displayed image.
The information from the eye-trackers is advantageously used to monitor the vigilance of the user.
The head-mounted display system is advantageously an aeronautical system, the user being an aircraft pilot.
The invention will be better understood and other advantages will become apparent on reading the following description given by way of non-limiting example and thanks to the appended figures, in which:
The display system in accordance with the invention can be monocular or binocular. The principal application of the system in accordance with the invention is to assist with piloting aircraft. Such a system can be used for all applications necessitating the superimposition of synthetic images on the outside world. The possibility of producing head-mounted display systems at low cost makes it possible to envisage a great variety of application, as much in the transport system as in professional applications necessitating a near view or consumer applications. By way of non-limiting example,
The following description uses the same reference numbers as
As synergy exists between accommodation and the convergence of the eyes, it is possible to deduce the accommodation effort and therefore the distance of the observed object entirely from the measurement of the convergence angle of the eyes produced by the eye-tracker or eye-trackers. The distance between the user and the element of the outside view they are looking at is therefore known.
Knowing this accommodation and convergence information, the graphic generator means adjust simultaneously and in real time:
As seen in
Using eye-trackers has other advantages. Thus the eye-tracker can serve as means for interaction with the HMD. The parameters of the displayed image can therefore be modified as a function of the knowledge of what object is being looked at. Another advantage is that the eye-tracker can serve as means for monitoring the vigilance of the user. This function can be particularly useful for all piloting applications.
It is equally possible to complement the head-mounted display system in accordance with the invention by adding a posture detector system enabling the posture of the head of the user relative to a known frame of reference to be known perfectly.
There exist various techniques for identifying an object in space. Electromagnetic detection may be used. A sender is disposed in the fixed frame of reference and a receiver in the mobile frame of reference. Passive or active optical detection may equally be used. In the latter case, the display device carries light-emitting diodes the position of the emission from which is identified by means of video cameras. All these techniques are known to the person skilled in the art. They are compatible with operation in real time and adapt easily to the display system in accordance with the invention.
Number | Date | Country | Kind |
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1402529 | Nov 2014 | FR | national |