KR20120127560A - Safe eye detection - Google Patents

Abstract

PURPOSE: A system for detecting eyes and an operating method thereof are provided to supply information to various systems by safely detecting a position and a direction of eyes. CONSTITUTION: A camera(220) senses main light reflected from a subject to generate an image. A signal source driver(302) supplies a driving signal to a light source(204). A processor(304) processes the image to detect an eye position of the subject. A proximity sensor detects the proximity of the subject to an eye detecting system. The processor controls the signal source driver to adjust the driving signal of the main light resource according to the proximity of the subject. [Reference numerals] (302) Signal source driver; (304) Processor; (308) Camera controller

Description

Eye detection system and its operation method {SAFE EYE DETECTION}

The present invention relates generally to the field of eye detection. More particularly, the present invention relates to a method and apparatus for the safe detection of eye position and gaze direction.

Eye detection systems based on analysis of epipolar stereo images of the face have achieved a high degree of precision in recording the location and gaze direction of the human eye. A simple optical approach to implementing such a system is to illuminate the eye using infrared (IR) light. Light reflected from the interior surface of the eye is detected by an imager. Two sets of images appear through the imager by means of two groups of IR light sources. These light sources can be separated in time, or can have different wavelengths, and the image can be separated by time-gating or wavelength filtering. These images can produce bright circles that represent pupil locations.

The disadvantage of this approach is that it cannot be used if the object is not in close proximity to the light source and the imager. This is because more powerful IR light sources should be used. Such light sources pose a threat to safety when the subject is too close to the light source and stares directly at the light source. Prolonged exposure of such high intensity signals may cause eye damage. For example, if the system is safely designed at distances greater than 12 cm, this approach will not work if the object is more than 2 m away from the detector, for example in a TV implementation.

Another approach uses telephoto lenses, passive illumination, and conventional image processing, but this approach only works when there is adequate ambient lighting, not through sunglasses. In addition, this requires significant computational resources to locate the eye.

It is therefore an object of the present invention to provide a method and apparatus for safe detection of the eye position and gaze direction that resolves at least some of the foregoing.

The present invention generally relates to the safe detection of the position of the eye. Objects and features of the present invention will become apparent to those of ordinary skill in the art upon consideration of the following detailed description.

In one embodiment of the present invention, the eye detection system for the safe detection of the position of the eye of the subject estimates the distance from the eye detection system to the subject, and the eye detection system when the object is too close to the eye detection system. Reduce the output level of at least one main light source. If the object is not too close to the eye detection system, the output level of at least one primary light source of the eye detector is increased if the output level is below a predetermined maximum output level. Primary light from at least one primary light source is reflected from the subject and sensed by the imager to obtain one or more images from which the position of the subject's eye is evaluated.

Thus, according to the present invention, a method and apparatus are provided for the safe detection of the position of the eye and the gaze direction.

1 is a flowchart of a method consistent with an embodiment of the present invention.
2 is a schematic diagram of an eye detection system consistent with an embodiment of the invention.
3 is a block diagram of an eye detection system consistent with an embodiment of the invention.
4 is a schematic diagram of an eye detection system in accordance with another embodiment of the present invention.
5 is a block diagram of an eye detection system in accordance with another embodiment of the present invention.

The novel features which are believed to be characteristic of the invention are disclosed in the appended claims. However, by reading the accompanying drawings in conjunction with the following detailed description of exemplary embodiments, the invention itself will be best understood, as well as the preferred forms of use and further objects and advantages of the present invention.

As the invention allows for many different forms, one or more specific embodiments will be shown and described in detail in the form of figures, the disclosure of which is considered to be illustrative of the principles of the invention and is shown in the specific embodiments shown and described. It is not intended to limit the invention. In the following detailed description, like reference numerals are used to describe corresponding parts at the same, similar or different views of the drawings.

1 is a flow diagram of a method consistent with one embodiment of the present invention. This flowchart describes a method for the safe operation of an eye detection system that irradiates an object using infrared (IR) light. Referring to FIG. 1, following the start block 102, the distance from the IR light source to the subject of the eye detection system is evaluated. This can be done in a variety of ways. In one embodiment of the invention an infrared proximity sensor is used. This sensor can be integrated into an eye detection system. In another embodiment of the present invention, an IR light source and an imager of an eye detection system are used as the proximity sensor. In yet another embodiment, the intensity of the IR light reflected from the object is measured. In another embodiment, the size of the image of the subject's pupil is specified and used to assess the distance of the subject. In still another embodiment, the size of the elliptical face is specified and the distance is assessed. It will be apparent to those of ordinary skill in the art that various approaches are combined to measure distance to the subject to provide higher precision or higher reliability.

At decision block 106 a check is made to determine whether the object is too close to the IR light source. This determination may be based on the current output level of the IR light source and the estimated distance to the object. If it is determined that the object is too close, the output level of the IR light source is reduced at block 108. The output level of the IR light source may be reduced to zero if suitable for that application. Once the output level is reduced, the flow returns to block 104. As indicated in the case where it is determined that the object is not too close, a check is made to branch from decision block 106 toward NO to determine that at decision block 110 the output level of the IR light source is set to the maximum level. If the output level is not maximum, branching away from decision block 110 towards NO as indicated, the output level is increased at block 112. The output level may be increased by increment or set to a maximum level. If indicated, branching away from decision block 110 toward YES and the output level is at maximum, or if the output level is increased at block 112, flow continues to block 114 and eye detection is performed. Only one eye detection measurement may be made or the eye detection may be performed for a predetermined length of time. The flow then returns to block 104.

In this way the output level is adjusted depending on the distance between the eye detection system and the subject. This prevents the subject from being exposed to unsafe levels of IR light when in proximity to the IR light source of the eye detection system.

2 is a schematic diagram of an eye detection system consistent with one embodiment of the present invention. In FIG. 2, the support structure 202 supports the first IR light source 204 driven by the first drive signal 206 and the second IR light source driven by the second drive signal 210. In this embodiment, the first IR light source 204 is an 'off-axis' light source and the second light source 208 is an 'on-axis' light source. In one embodiment of the present invention, the first light source and the second light source may be light emitting diodes (LEDs). The light source may emit light of a different wavelength, for example, the first light source 204 may emit light of 850 nm, and the second light source may emit light of 780 nm, and vice versa. Do. The first light source 204 emits to the object 212 along the optical path 214, and the second light source 208 emits to the object 212 along the optical path 216. Light from all light sources passes through the eye of the object 212 and is reflected along the optical path 218 of the imager 220 from the retina of the back of the eye. The imager includes an array of optical sensors such as a photodiode. In one embodiment, the imager may be a silicon detector, such as a CMOS optical imager with a mega-pixel array. Numerous pixels in the array increase the sensitivity of the eye detector. The sampled signal from the imager is processed to provide information related to the eyes of the object 212. This imager 220 outputs an image signal 222.

3 is a block diagram of an eye detection system in accordance with one embodiment of the present invention. Referring to FIG. 3, the eye detection system includes a signal source driver 302 that generates a first drive signal 206 at a first light source 204 and a second drive signal 210 at a second light source 208. Include. The signal source driver 302 can control the output of the IR light source by changing the amplitude of the drive signal or by changing the pulse width of a pulse width modulated signal. The output of the light source may be controlled to ensure that the light reflected from the object 212 is within the desired range. A processor 304, such as a digital signal processor, controls the signal source driver 302 to control the levels of the signals 206 and 210 in response to the image signal 222 received from the imager 220. can do. For example, light sources 204 and 208 can be used with the imager 220 as a proximity sensor to assess the distance of the object from the light sources 204 and 208. Instead, the intensity of light reflected from the target retina may be measured, or the size of the image of the retina may be measured, or the size of the face may be measured. The intensity of the reflected light increases as the object approaches the eye detector, thus providing an assessment of the object's proximity. In addition, the size of the image of the retina increases as the subject approaches the eye detection system, thus providing an assessment of the subject's proximity. As another test, the distance between the images of the two retinas may be measured. Wide spacing indicates that the subject is close to the eye detector. However, narrow spacing may not indicate that the object is far away. The processor 304 receives and analyzes the signal 222 from the imager to perform eye detection and evaluate the proximity of the subject. Eye detection information 306 can be used to control various systems. For example, as shown in FIG. 3, eye detection information 306 can be passed to a camera controller 308 that controls pan, tilt, and zoom of the camera 310. . One application of such a system is face recognition. The pan, tilt, and zoom of the camera can be used to position the image in a preferred location within the image frame to ensure an optimized size of the image. This can analyze the image and reduce the amount of post processing that ensures maximum image quality.

4 is a schematic diagram of an eye detection system in accordance with another embodiment of the present invention. In FIG. 4, one of the support structures 220 supports a signal emitter 402. Light from signal emitter 402 is transmitted along signal path 404. When the object 212 or other object is close to the eye detector, the signal is reflected from the object 212 along the signal path 406 to the signal detector 408. The signal emitter 402 may be, for example, an IR light source such as an LED, in which case the wavelength of the IR light source is selected to be different depending on the light emitted by the IR light sources 204 and 208. The signal detector 408 may be a positive-intrinsic-negative (PIN) photodiode. The IR light source may be switched OFF or operated at a reduced output level when a signal reflected from the object 212 is detected by the signal detector 408.

5 is a block diagram of an eye detection system in accordance with another embodiment of the present invention. In addition to the IR light sources 204 and 208 and the signal detector 408 used for eye detection, the system may include a signal emitter 402 and a signal detector 408 used for detecting object proximity. . The signal emitter 402 reflects off the object 212 and emits a signal that the signal detector 408 receives. Processor 304 controls signal source driver 302 to control the levels of signals 206 and 210 in response to image signal 222 received from imager 220. Signal emitter 402 and signal detector 408 may be positioned relative to each other to prevent signals from the emitter from reaching the detector via a direct path. In addition, processor 304 may control signal source driver 302 to control signals used to drive signal emitter 402. The processor 304 may receive and analyze the signal 222 from the imager, and may also receive the signal from the signal detector 408 to evaluate the proximity of the object. The light source can be switched OFF when the object is too close to the IR light source and can be operated at a reduced output level.

Eye detection systems can be used to provide information to various systems. These include a camera that tracks the subject's face, an optical display that darkens or switches off to save power when no eyes are watching, and an optical display that controls the orientation of the image to match the viewer's orientation. And a computer interface and other gaze-controlled targeting system for manipulating around the display screen to select objects for the user to view.

Those skilled in the art will recognize that the present invention has been disclosed as exemplary embodiments. However, the present invention is not limited to the above exemplary embodiments, as the present invention may be implemented by hardware specific equivalents such as hardware and / or dedicated processors, such as those shown and disclosed. Similarly, general purpose computers, microprocessor based computers, digital signal processors, microcontrollers, dedicated processors, custom circuits, AISC, dedicated hard wired logic, and / or programmable gate arrays (PGAs) may also be used. It may be used to construct alternative equivalents of embodiments of the present invention.

While the present invention has been disclosed in combination with specific embodiments, it is evident that numerous alternatives, modifications, combinations, and variants will be apparent to those of ordinary skill in the art in view of the above detailed description. Accordingly, the invention includes all such alternatives, modifications, and variants that fall within the scope of the appended claims.

Claims (17)

An operation method of an eye detection system for safely detecting an eye position of a subject,
Evaluating the distance from the eye detection system to the subject, if the subject is too close to the eye detection system, reducing the output level of at least one primary light source of the eye detection system, The distance estimation step of increasing the output level of the at least one primary light source of the eye detection system if the object is not too close to the eye detection system and the output level is less than a predetermined maximum output level;
Sensing primary light from the at least one primary light source reflected from the object to obtain at least one image,
Detecting an eye position of the subject according to the at least one image
How the Eye Detection System Works.
The method of claim 1,
Evaluating the distance from the eye detection system to the subject,
Emitting light from the second light source,
Sensing light from the second light source reflected from the object to obtain a reflected light signal;
Analyzing the reflected light signal to evaluate a distance from the eye detection system to the subject;
How the Eye Detection System Works.
The method of claim 2,
The second light source is an infrared light source,
Sensing light from the second light source reflected from the object is performed by an infrared light detector
How the Eye Detection System Works.
The method of claim 1,
Evaluating the distance from the eye detection system to the object includes processing the at least one image to evaluate the intensity of primary light reflected from the eye of the object.
How the Eye Detection System Works.
The method of claim 1,
Evaluating the distance from the eye detection system to the object includes processing the at least one image to evaluate the size of the image of the primary light reflected from the eye of the object.
How the Eye Detection System Works.
The method of claim 1,
Evaluating the distance from the eye detection system to the subject includes processing the at least one image to evaluate the size of a face image of the subject.
How the Eye Detection System Works.
The method of claim 1,
If the object is closer than the minimum safety distance to the first level, the output level of the at least one primary light source of the eye detection system is reduced from the first level to a lower level.
How the Eye Detection System Works. The method of claim 1,
Controlling an external device according to whether an eye position of the object is detected;
How the Eye Detection System Works.
The method of claim 1,
Controlling an external device according to the eye position of the subject;
How the Eye Detection System Works.
The method of claim 9,
The external device includes a camera
How the Eye Detection System Works.
The method of claim 9,
The external device includes a visual display screen
How the Eye Detection System Works.
An eye detection system for safely detecting a subject's eye position,
At least one primary light source operable to emit primary light,
An imager operable to sense primary light reflected from the object and generate an image therefrom;
A signal source driver operable to provide a drive signal to the at least one primary light source;
A processor operable to process the image to detect an eye position of the subject;
A proximity sensor operable to detect proximity of the subject to the eye detection system,
The processor is operable to control the signal source driver to adjust a drive signal to the at least one primary light source in accordance with the proximity of the object to the eye detection system.
Eye detection system.
13. The method of claim 12,
The proximity sensor,
A second light source operable to emit a second light;
A light detector operable to sense a second light reflected from the subject;
Eye detection system.
The method of claim 13,
The primary light comprises infrared light having a first wavelength and the second light comprises infrared light having a second wavelength
Eye detection system.
An eye detection system for safely detecting a subject's eye position,
At least one primary light source operable to emit primary light,
An imager operable to sense primary light reflected from the object and generate an image therefrom;
A signal source driver operable to provide a drive signal to the at least one primary light source;
A processor operable to process the image to detect an eye position of the subject,
The processor evaluates the proximity of the object to the eye detection system and controls the signal source driver to adjust the drive signal to at least one primary light source in accordance with the object's proximity to the eye detection system. Additionally operable
Eye detection system.
The method of claim 15,
The processor is operable to process the image generated by the imager to evaluate the proximity of the object to the eye detection system to evaluate the size of the image of the primary light reflected from the eye of the subject.
Eye detection system.
The method of claim 15,
The processor is operable to process the image generated by the imager to evaluate the proximity of the object to the eye detection system to evaluate the intensity of the primary light reflected from the eye of the object.
Eye detection system.

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