JPH0280026A - Detecting device for line of sight - Google Patents

Abstract

PURPOSE:To correctly detect the line of sight direction even if an eyepiece section and an eye under test are not matched correctly by calculating the rotating angle of the line of sight and the relative displacement quantity between this device and the eye under test and determining the line of sight direction of the eye under test based on the calculated results. CONSTITUTION:An eye under test 3 is biased by the displacement quantity S, and the line of sight is directed in the direction of the angle theta. If the coordinates of the iris contour at the rotating angle theta and the displacement quantity S are set to (X1, Y1), (X2, Y2) and the image formation positions on a sensor are set to (-f, K1), (-f, K2), -f:X1= K1:Y1, -f:X2:K2:Y2, thereby K1 and K2 are expressed as shown in the equation (1). Personal errors of these quantities can be practically referred as constants, (b), (c), (l), (gamma), and (a) are referred as constants, the equation (1) is simultaneous equations on and S, thus thetaand S can be determined by resolving the equation (1). The solutions are determined, the coordinates of the right end and the left end of the iris contour are determined by an image sensor, then the rotation quantity and the displacement quantity of an eyeball, i.e., the direction of the line of sight, can be correctly determined.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for detecting the direction of the line of sight, and particularly to a device for detecting the direction of the line of sight, and in particular, a device for detecting the direction of the line of sight even when the eye to be examined and the detection optical system of the detection device are eccentric. The present invention relates to an accurate detection device suitable for use in combination with an optical device such as a camera.

[Conventional technology]

2. Description of the Related Art Apparatuses for detecting the line of sight direction of an eye to be examined are well known. For example, Journal of 0ptical 5o
Society of America, vol, 63.
No. 8. The method described on pages 921 and below or the method disclosed in JP-A-61-172552 projects a light beam to the anterior segment of the subject's eye and utilizes the Purkinje image, which is an image reflected by the cornea or crystalline lens.・It is something to do. Apart from this, a configuration as shown in FIG. 8 has been proposed as a line of sight detection method using the outline of the iris.

This method takes advantage of the fact that the iris (the black part of the eye) has a lower emissivity than the sclera (the white part of the eye), and it is relatively easy to detect the boundary between the two. Both horizontal sides of the sclera (scleral border) are illuminated in a spot or strip shape. The reflected light is received by two light receiving elements, and the horizontal eye movement amount (rotation angle) is detected from the difference signal. Further, the amount of eye movement in the vertical direction is detected based on the sum signal of the two light receiving elements. An infrared light emitting diode is used as the light source, and an infrared photodiode is used as the light receiving element to eliminate any discomfort to the human eye.

However, since this device is based on the premise that the optical axis of the detection device and the optical axis of the eye to be examined are aligned, it is possible to use this device with the eye of the eye carelessly looking into the eyepiece of an optical device such as an ocular reflex camera. It is unsuitable when there is a high possibility that eccentricity will be included between the optical axis of the eyepiece lens and the axis of the eyeball.

Incidentally, the need to detect the direction of the line of sight of the subject's eye when looking into a single-lens reflex camera has increased recently due to advancements in camera automatic focus detection technology, which has expanded the field of view for detecting focus to include multiple fields, not just the center of the screen. There is now a need for an input means to quickly select one of them, or for other shooting conditions of the camera, such as switching between average metering and weighted metering, or selecting one of multiple shooting modes. This is based on the desire to simplify the means for selecting and inputting one of the following. Such a need exists not only in cameras but also in observation devices such as microscopes, position alignment devices, and the like.

[Problems to be Solved by the Invention] The purpose of the present invention is to accurately detect the direction of line of sight when an observer looks into the eyepiece, even if the eyepiece and the subject's eye are not accurately aligned. shall be.

[Means for solving problems]

The present invention includes an imaging means for imaging the anterior segment of the eye to be examined, and coordinates on the imaging means for a plurality of predetermined points at the boundary between the sclera and the iris of the eye to be examined from the output signal of the imaging means. The apparatus is equipped with a calculation means for calculating the rotation angle of the line of sight and the amount of relative displacement between the present device and the eye to be examined using the above equation, and further calculating the direction of the line of sight of the eye to be examined from the results of these calculations.

〔Example〕

The present invention will be described in detail below, and first the basic idea will be described using FIG. The figure corresponds to a horizontal optical cross section, where l indicates a line sensor, 2 indicates an imaging lens, and 3 indicates an eyeball to be examined. Let f be the set distance between the line sensor l and the imaging lens 2, and let l be the distance between the eye 3 and the eyepiece 2, which occupy a position conjugate with the line sensor 1. The X coordinate is taken on the optical axis of the imaging lens 2, and the X coordinate is taken perpendicular to the X coordinate through the principal point of the imaging lens 2.

Further, b is the radius of the iris, C is the radius of curvature of the anterior surface of the cornea, γ is the distance from the center of rotation O of the eyeball to the anterior surface of the cornea, and S represents the amount of displacement between the optical axis of the imaging lens and the axis of the eyeball.

In the state depicted in the figure, the eye 3 to be examined is eccentric by a displacement amount S and directs its line of sight in the direction of the angle θ. When people see things, they see with the macula, which is slightly off the axis of the eye, so there is a certain amount of deviation between the axis of the eye and the axis of vision, but this can be handled by offset.

The coordinates of the iris contour when the rotation angle θ and the displacement amount S are (xI+
” 1) + (X 2 + Y 2 ), the imaging position on the sensor is (-f, K, ), (-f,
If K 2), then from this, 2 becomes as follows.

However, a=c-by:P.

Now, since individual differences in these quantities can be regarded as constants in practice, b, c, I! , γ, and a are constants, equation (1) becomes a simultaneous equation regarding θ and S, and by solving this equation, θ and S can be obtained. The solution is therefore that if the coordinates of the left and right ends of the iris contour are determined using an image sensor, the amount of rotation and displacement of the eyeball, that is, the direction of the line of sight can be determined accurately.

FIG. 2 shows an apparatus in which a line-of-sight detection apparatus implementing the above method is incorporated into a camera.

In the figure, 10 is a photographing lens, 11 is a main mirror, and the main mirror 11 reflects most of the light flux that has passed through the photographic lens 10.
Allow some parts to pass through. 12 is a sub-mirror, and main mirror 11
The light flux that has passed through the camera body is reflected to the bottom of the camera body. 1
3 is a focus detection unit having a plurality of distance measuring fields.

14 is a focus plate, 15 is an information display board, which displays, for example, a distance measurement field mark in the photographing screen as shown in FIG.
Displays exposure control modes such as Tv, P, and M, and focus modes such as S (single), C (continuous), and 9M (manual). You can register the selected mode by looking at either the exposure mode display or the focus mode display in synchronization with pressing the release button (not shown), or you can also register one of the distance measurement fields. .

16 is a pentaprism, and 17 is an eye bead.

Reference numeral 18 denotes an optical path splitting mirror, which uses a guichroic mirror, for example, to transmit visible light and reflect infrared light.

19 is an imaging lens, and the combination of this imaging lens 19 and the eyepiece 17 corresponds to the imaging lens 2 in FIG. La, lb, and lc are line fist image sensors, and three of them are arranged in parallel in a direction perpendicular to the drawing.

The lighting system will be described later.

Let us consider the case where the display in the finder is as shown in FIG. 3 mentioned above. The photographer looks at the center row to select the AF point/light metering point, the top row to select the exposure control mode, and the bottom row to select the focus mode. Determination of which row the user is gazing at is performed by determining which sensor has the widest iris image formed on the sensors la to IC. That is, if the value (2 for Kl-) in the sensor 1a is larger than the value (2 for Kl-) in the other sensors, it is determined that the focus mode corresponding to the sensor 1a has been selected. Similarly, (KI K2
) If the value of (KI K2) at the sensor 1c is the maximum, it is determined that the exposure control mode has been selected. Naturally, in the case of a camera, the relative position of the detection system and the eyeball also changes when detecting the line of sight in the vertical direction. Therefore, the direction of the line of sight cannot be determined accurately unless the amount of rotation and displacement are accurately grasped. However, in this case, the intervals between the three rows are sufficiently far apart, so even if the exact direction of the line of sight is not known, it is sufficient to know the approximate direction of the line of sight. To do this, all you have to do is compare the widths of the iris on the three sensors, that is, (KI K2), and find out which sensor has the maximum width.

And once you know which row the photographer is staring at,
Next, determine which one you have selected. this is,
When comparing which sensor has the maximum width of the iris, use 2 for . In other words, 1+ on the sensor corresponding to the row that the photographer is looking at.
The rotation angle θ and the displacement amount S are calculated using K2 and equation (2), and the accurate direction of the line of sight is determined. It is possible to know what the photographer intended from the direction of this line of sight. It goes without saying that calculation of equation (2) can be performed using the microcomputer 20 inside the camera.

In this way, by roughly determining the direction of the vertical line of sight and accurately determining the direction of the horizontal line of sight, it is possible to know where the photographer's line of sight is directed in the viewfinder display shown in Figure 3. Can be done.

Note that in order to increase the contrast of the iris contour and increase the detection accuracy, light sources 7a and 7b are actually used as shown in FIG.
to illuminate the iris contour. This light source is preferably an infrared light emitting element. This is because projecting light within the human visibility range makes it difficult for the photographer to observe the viewfinder (
Because it does. In addition, an infrared light emitting element is used as a light source, and 18
By using a dichroic mirror for the mirror, it is possible to prevent light loss in both the line-of-sight detection system and finder system.

[Other Examples]

In the previous example, the field of view line selected by the photographer was well-defined in the vertical direction, so the line of sight detection in the vertical direction was only rough, but as shown in Figure 5, there were many distance measurement and photometry points. If it is assumed that distance measurement and photometry are to be performed at any point on the entire screen, the line of sight in the vertical direction must also be accurately detected. An example of such a case is shown below.

In order to accurately detect the line of sight in the vertical direction, it is necessary to know two coordinates of the iris contour on the sensor in the vertical direction. It would be most advantageous in terms of accuracy if points A and A' in FIG. 6 could be detected, but since these points are hidden by the eyelids and cannot be detected, we will instead detect points B and B'. Note that C is a detection point when detecting the line of sight in the horizontal direction. In this case, the layout will be as shown in FIG. 1 is an area sensor. Signal processing the output of the area sensor, extract the horizontal line where the width of the iris is maximum, find the coordinates K Hl, K H2 of the iris contour on this line, and calculate (2
) is used to find the lateral rotation angle θH and shift amount SH.

Next, a vertical line corresponding to B and B' is extracted from the coordinates of C (K H2), and on that line, the coordinates of the iris contour Kv1. 2 is obtained, and the vertical rotation angle θV and shift amount Sv are obtained using equation (2).

In this way, by determining the amount of displacement and rotation in the vertical and horizontal directions and using these to determine the exact direction of the line of sight, it is possible to accurately determine where in the viewfinder the photographer is gazing.

〔Effect of the invention〕

As explained above, in the present invention, an image of the iris contour is formed on an image sensor, and the coordinates of the imaged position are used to determine the rotation angle and displacement of the line of sight. It is now possible to accurately detect the direction of the line of sight even when the relative position of the line of sight detection system and the eyeball is displaced.

[Brief explanation of the drawing]

Figure 1 is a diagram of the principle of the present invention, Figure 2 is a layout diagram of the first embodiment, Figures 3 and 5 are diagrams showing examples of displays in the finder, Figure 4 is a perspective view of the illumination system, Figure 6 is a diagram showing the measurement points of the iris contour, Figure 7 is a layout diagram of the second embodiment,
FIG. 8 is an explanatory diagram of a conventional example. 1 is an image sensor, 12 is an imaging lens, 3 is an eyeball, 1
8 is a half mirror or dichroic mirror, 17
is an eyepiece lens, 16 is a pentaprism, 7a, 7
b is a light source for illumination. CM Fig. 5 Fig. 6 <a><b> Fig. 7 Fig. 8 (A horizontal direction output! Cross direction same output

Claims (5)

[Claims] (1) An imaging means for imaging the anterior segment of the eye to be examined, and coordinates on the imaging means for a plurality of predetermined points at the boundary between the sclera and iris of the eye to be examined from the output signal of the imaging means, and these coordinates are 1. A visual line detection device, comprising a calculation means for calculating the rotation angle of the visual line and the amount of relative displacement between the device and the eye to be examined, and further determining the direction of the visual line of the eye to be examined from the results of these calculations. (2) The line of sight detection device according to claim 1, further comprising illumination means for illuminating the eye to be examined. (3) The imaging means is a line that horizontally images the eye to be examined.
The line of sight detection device according to claim 1, which includes an image sensor. (4) The line of sight detection device according to claim 1, wherein three line image sensors are arranged in parallel. (5) The line of sight detection device according to claim 1, wherein the device is attached to a camera body.