Canon Patent Application: Eye controlled focus for Mirrorless Cameras

When I started to read this patent, I went, wow this is complicated, and then, all of a sudden I went.. no this isn't it, this can't be ... 

If you were like me and honed your skills on Canon EOS-3 or Elan IIe and the like cameras you will remember Canon's Eye controlled focus.  This is different than Eye detection AF of today's mirrorless cameras where the camera detects eyes in the image.  Eye controlled focus uses the photographer's eye position to determine what the focus point is. You don't have to use a joystick, a touchpad, you simply look at where you want the focus to be.

I know this is one of the most highly sought after requests that I've seen over the years - for Canon to bring back eye controlled focus.

What we have here, and I never really ever say this, but you saw it here first; is Eye controlled focus for a mirrorless camera.

This patent literature, it could be because it's machine translated from Japanese is anything but clear, but look at the diagram shown at the start of this article.

We have a mirrorless camera (Canon specifically states this by including item 10, which is a display element for the viewfinder).  The important pieces are 13a-13f which are light sources for illuminating the line of sight of the photographer's pupil. The half mirror is in place so that 16 and 17 which is the image sensor that is used to monitor where the eye position based upon the pupil location.

The actual patent text of that, for the more in-depth study is (machine translated);

In addition, a display element 10 composed of a liquid crystal or the like for displaying a captured image, a display element driving circuit 11 for driving the display element 10, and an eyepiece 12 for observing a subject image displayed on the display element 10 are provided. Has been placed.   Reference numerals  13a to 13b denote light sources for illuminating the photographer's eyeball 14 for detecting the direction of the line of sight from the relationship between the elephant and the pupil reflected by the cornea reflection of the light source conventionally used in a single-lens reflex camera or the like. The infrared light emitting diode is disposed around the eyepiece 12. The illuminated eyeball image and the image by corneal reflection of the light sources 13a to 13b are transmitted through the eyepiece lens 12, reflected by the light splitter 15, and the eyeball lens in which the photoelectric element array of the CCD ridge is arranged two-dimensionally by the light receiving lens 16. An image is formed on the image sensor 17. The light receiving lens 16 positions the pupil of the photographer's eyeball 14 and the image sensor 17 for the eyeball in a conjugate imaging relationship. The line-of-sight direction is detected by a predetermined algorithm, which will be described later, from the positional relationship between the eyeball imaged on the eyeball image sensor 17 and the corneal reflection of the light sources 13a to 13b. 

The technical diagram isn't much different than what Canon used on their film cameras.

For instance, this is the diagram from the Canon A2E brochure describing eye controlled focus. 

Do keep in mind though that today's image sensors are far more advanced than the CCD sensors back in the 90's that Canon had to work with for their film cameras with eye controlled focus.

So what's this patent really about? This patent is about automating the calibration and automatically recognizing the subject in which the photographer is looking at thus improving the usability.

The present invention has been made in view of the above problems, and in a subject recognition device having a line-of-sight detection device, while accurately recognizing a subject to be watched by a photographer and automating a gaze position calibration operation, The purpose is to improve the convenience of the photographer. 

Of course with any patent application or patent, there is no guarantee it will end up in an actual product.  What they do, however, is show us areas of Canon research and development.

Japan Patent Application 2019-129461