JPH08201681A - Optical instrument having line-of-sight detecting device - Google Patents

Abstract

PURPOSE: To select a desired focus detecting region without completely making the line of sight coincident with the focus detecting region by selecting a focus detecting region corresponding to a region for deciding the line of sight in which the line of sight is located when the user's line of sight is located in the region for deciding the line of sight provided by including the focus detecting region. CONSTITUTION: In a range finding arithmetic circuit, deviation value calculating parts 201-205 calculate the deviation value of two images by performing correlation arithmetic based on the principle of range finder. Defocusing amount calculating parts 206-210 calculate the defocusing amount of a photographing lens from the deviation values outputted from the deviation value calculating parts 201-205, respectively. A range finding point selecting part 211 selects range finding points represented by A1-A1 based on the information of the direction of the line of sight calculated in a line-of-sight arithmetic circuit CKT. The photographing lens is driven through a lens control circuit LKT so as to minimize the defocusing amount from a sensor corresponding to the range finding point selected by the range finding point selecting part 211.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye-gaze detecting device for detecting the eye-gaze position of a user and an optical instrument having the eye-gaze detecting device.

[0002]

2. Description of the Related Art Conventionally, as a visual axis detecting device for optically detecting the visual axis (visual axis) of a user, Japanese Patent Laid-Open No. 61-17255.
There is No. 2.

This is to detect from the first Purkinje image, which is a reflection image from the anterior surface of the cornea generated by illuminating the user's eye with parallel light, and the position of the center of the pupil. Based on FIG. Explain.

In the figure, 501 is the cornea, 502 is the sclera, and 50
3 is an iris, 504 is a light source, 506 is a projection lens, 507
Is a light receiving lens, 509 is an image sensor, and 510 is a half mirror. O'is the center of rotation of the eyeball, O is the cornea 5
The center of curvature of 01, a, b, the pupil edge portion which is the boundary position between the iris 503 and the pupil, c is the center of the pupil, and d is the first
This is the Purkinje image generation position. A is the optical axis of the light receiving lens 507, which coincides with the X axis in the figure. B is the optical axis of the eyeball.

The light source 504 is an infrared light emitting diode which is insensitive to the user and is arranged on the focal plane of the light projecting lens 506. The infrared light emitted from the light source 504 becomes parallel light by the light projecting lens 506 and is reflected by the half mirror 510 to illuminate the cornea 510. Part of the infrared light reflected on the surface of the cornea 510 passes through the half mirror 510 and is received by the light receiving lens 507 at the position d ′ on the image sensor 509.
Image on. In addition, the pupil edge portions a and b are connected to the image sensor 5 via the half mirror 510 and the light receiving lens 507.
Images are formed at positions a ′ and b ′ on 09. Light receiving lens 507
When the rotation angle θ of the optical axis a of the eyeball with respect to the optical axis a is small, and the z coordinates of the pupil edge portions a and b are z _a and z _b , the coordinate z _c of the central position c of the pupil is z _c ≈ It is expressed as (z _a + z _b ) / 2.

Further, if the z coordinate of the first pull-enki image generation position d is z _d and the distance between the center of curvature O of the cornea 501 and the center c of the pupil is oc —, the rotation angle θ of the eyeball optical axis a is oc — The relational expression of sin θ≈z _c −z _b is satisfied. Therefore, by detecting the positions of the eyeball feature points (the first Purkinje image z _d ′ and the pupil edge portions z _a ′ and z _b ′) that are projected on the image sensor 509, the rotation angle θ of the eyeball optical axis a is determined. It becomes At this time (1)
The formula is β · oc − · sin θ ≒ [(z _a '-z _b ') / 2]-
It can be replaced with z _d '. However, β is the distance l ₁ between the first Prekinje image generation position and the light receiving lens 507 and the light receiving lens 50.
7 is a magnification determined by the distance l ₀ between the image sensor 509 and the image sensor 509, and usually has a substantially constant value.

Based on the above principle, the direction of the line of sight can be detected.

Further, the present applicant has proposed an optical device which utilizes the position of the user's line of sight detected as described above and is combined with a focus detection device having a plurality of focus detection regions.
That is, the focus detection area that matches the user's line-of-sight position is selected from the plurality of focus detection areas, and the focus detection operation is performed on the selected focus detection area.

[0009]

In the above-mentioned conventional example, the desired focus detection area could not be selected unless the user's line-of-sight position perfectly matches the focus detection area. However, it is known that the gaze position always changes even if the human eye intends to gaze at one point.

The change of the line-of-sight position means that the eyeball moves to change the image formed on the retina. The eyeballs continue this movement all the time, and the eye movements cannot be stopped. In other words, even if a human does not intentionally move his / her limbs in a certain state, his / her muscles cannot vibrate and cannot be kept in a certain state. Similarly, the eyeball is also moved by muscles, so it is not possible to stop the line of sight at a certain point. Furthermore, it is said that as a characteristic of eyeball tissue, vision is gradually lost when the image is fixed at the same position on the retina for a long time. Further, even if the eye movement can be completely stopped, the line-of-sight position cannot be perfectly matched with the focus detection region if the error generated at the time of line-of-sight detection is large.

Therefore, it is extremely difficult to stabilize the line-of-sight position even if the user intentionally matches the line-of-sight with the desired focus detection region. It could not be perfectly matched with the focus detection area.

[0012]

In order to solve the above-mentioned problems, the present invention provides a focus detecting means for detecting a focus for each of a plurality of focus detecting areas and a visual axis detecting means for detecting a visual line of a user. In an optical device having a line-of-sight detection device having, when the user's line-of-sight is located in the line-of-sight determination region provided by enclosing the focus-detection region, a focus detection region corresponding to the line-of-sight determination region in which the line-of-sight is located. By including the selecting means for selecting, the user can select a desired focus detection area by locating the line of sight within the visual axis determination area including the focus detection area.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the drawings.

FIG. 1 corresponds to the position of the eyeball when light is applied to the eyeball to form a reflected image on a linear or area type photoelectric conversion element such as a CCD and the central part of the eyeball is horizontally scanned. It is a horizontal scanning signal.

As is clear from FIG. 1, the corneal reflection image can be accurately detected because the signal level is very strong, but since the boundary of the tissue of the eyeball has low contrast, the boundary between the iris and the pupil, It is quite difficult to detect the iris part, which is the boundary between the white and black eyes, with high accuracy. Fortunately, however, it is known that the size of the pupil changes depending on the surrounding brightness.

That is, since the pupil functions as a diaphragm so that the amount of light incident on the retina is constant, it changes in a constant relationship depending on the brightness of the external environment.

FIG. 2 is a graph showing the relationship between the brightness of outside light, which is the brightness of the outside world, and the diameter of the pupil.

Of course, there are individual differences, but in general, FIG.
It changes according to the relationship shown in.

The present invention utilizes a luminance meter (exposure meter) for measuring changes in the brightness of the outside, which is used in, for example, a camera, and predicts the pupil diameter by its output to detect the line-of-sight position. To do.

FIG. 3 is a characteristic diagram of a camera luminance meter (exposure meter). Relationship between E _V values (the details will be described later) is a result of photometry of the brightness L and the camera of the photometry circuit is the brightness of the outside world is as shown in FIG.

FIG. 4 is an example of a conversion diagram (map) for determining the diameter of the pupil from the luminance meter of the camera.

[0022] For example the diameter of the pupil at the time of between the luminance is L ₁ ~L ₂ when predicts that D ₁ of the L ₂ ~L ₃ is D _2, L ₃ ~
It is possible to obtain information on the diameter of the pupil corresponding to the brightness of the outside world by predicting D ₃ when L ₄ .
The intervals of L ₁ , L ₂ , L ₃ , L ₄ ... May be appropriately selected as required. In addition, the luminance L (cd /
It is known that the relationship between m ² ) and the size of the pupil diameter d (mm) is, for example, d = 5-3 tanh (0.4 logL) according to Crawford's equation.

On the other hand, it is known that the E _V value of the camera is expressed by the following formula 2 ^EV = (S / K) × L S, and the film sensitivity K is expressed by the calibration constant of the exposure meter. possible to find the diameter of the pupil camera exposure meter corresponds to E _V value measured can be.

[0024] that this exposure meter E _V value measured is get information photographer from which corresponds to the amount of light entering the viewfinder optical system of the camera to estimate the diameter of the pupil when looking through the viewfinder of the camera I can.

FIG. 5 shows an embodiment of an optical block of a camera having the visual axis detection device for a camera of the present invention.

Reference numeral 1 is a taking lens, 2 is a quick return mirror, 3 is a focusing plate, 4 is a condenser lens, and 5 is a pentaprism, which form a normal finder optical meter. Reference numeral 6 denotes a condenser lens for photometry, and 7 denotes a photometry element which forms a photometry system together with a finder system.

Reference numeral 8 is a sub-mirror, 9 is a field mask, 10 is a field lens, 11 is an AF light beam folding mirror, 1
Reference numeral 2 is a secondary imaging lens, and 13 is a photoelectric conversion element, which form a focus detection system.

Reference numeral 14 denotes an eyepiece lens having a beam splitter which transmits visible light and reflects infrared light inside, 15 is a lens for both projecting and receiving light, 16 is a beam splitter, 17 is an infrared LED for projecting light, and 18 is a linear or area. Type CC
It is a photoelectric conversion element such as D and forms a visual axis detection device. 19 is the photographer's eyes, 19-1 is the cornea, 19-
2 is an iris and 19-3 is a lens. 20 is a shutter and 21 is a film.

The light projected from the infrared LED 17 is converted into a parallel light flux by the light projecting lens 15 and applied to the eyeball 19. The reflected light from the cornea 19-1 and the iris 19-2 is configured to form an image on the photoelectric conversion element 18 via the light receiving lens 15.

Since infrared light for detecting the line of sight is hardly sensed by the eyes, the diameter of the pupil does not change due to this light, and the diameter of the pupil changes only by the visible light from the finder system. Therefore, information on the diameter of the pupil of the photographer can be obtained from the output signal from the photometric element 7.

From the viewpoint of enhancing the safety of the visual axis detection system, it is preferable that the energy of infrared light applied to the eyes is small. Therefore, by reducing the transmittance of the beam splitter 16 and increasing the reflectance, almost all of the light reflected from the eye is imaged on the photoelectric conversion element 18, so that the amount of light irradiated to the eye is minimized. Can be suppressed.

FIG. 6 shows an example of an electric circuit block in the case of inputting line-of-sight information to a camera by using this line-of-sight detection device. S _{1 to} S ₅ are photoelectric conversion elements for dividing and measuring the photographic screen, LD _{1 to} LD ₅ are logarithmic conversion elements, and OP _{1 to} OP ₅ are operational amplifiers, which constitute a photoelectric conversion circuit. The outputs of these photoelectric conversion circuits are the multiplexer M.
A / D conversion is performed by the AD conversion circuit AK in time series via P, and the photometric output corresponding to each photoelectric conversion element is output by the photometric output calculation circuit LM. With respect to the output of the photometric output calculation circuit LM, the average value or the center-weighted value calculation circuit AM outputs the average value or the center-weighted value, and the pupil diameter calculation circuit XE calculates and outputs the pupil diameter based on this output. . Information from the photoelectric conversion element CS for detecting the line of sight such as 18 and information from the pupil diameter calculating circuit XE are calculated by the line of sight calculating circuit CKT, and the direction of the line of sight is output. Based on the output of the line-of-sight calculation circuit CKT, that is, based on the position of the line of sight of the photographer in the finder, one is to correct the weight of the evaluation of the evaluation calculation circuit EM so as to make it heavy in the direction of the line of sight, and to perform the calculation. According to the result, the exposure amount control circuit FKT is configured to perform the exposure amount control.

The other is configured such that the distance measuring calculation circuit AKT selects a focus detection area corresponding to the direction of the line of sight,
The lens is controlled through the lens control circuit LKT.

The line-of-sight calculation circuit CKT is shown in FIG.

FIG. 7 shows an example of the internal structure of the line-of-sight calculation circuit CKT, in which 101 is a photoelectric conversion element C for line-of-sight detection.
A pupil edge detection unit that detects the edge of the pupil based on the information from S and the diameter of the pupil that is output from the pupil diameter calculation circuit XE, and 102 is the center of the pupil that detects the center of the pupil based on the output from the pupil edge detection unit 101. A detection unit, 103 is a corneal reflection image position detection unit, and 104 is a visual axis calculation unit, which detects the visual line direction based on the pupil center and the corneal reflection image position (first Purkinje image).

In the distance measuring method of this embodiment, five distance measuring points are set, and the focus can be detected for each subject at each distance measuring point. As shown in FIG. 8, the distance measuring units A _{1 to} A corresponding to the respective distance measuring points are displayed on the screen.
₅ is provided, and the line-of-sight detection visual fields K _{1 to} K ₅ are set so as to surround the distance measuring units A _{1 to} A ₅ . When there is a line of sight in any of the line-of-sight detection visual fields K _{1 to} K ₅ , the distance measurement calculation circuit AKT selects a distance measurement point corresponding to the line-of-sight detection visual field unit in which the line of sight is present. The lens control circuit LKT is driven with an object whose focus can be detected by the selected distance measuring point as a main object.

FIG. 9 shows an example of the internal structure of the distance measurement calculation circuit AKT.

Reference numerals 201 to 205 are shift amount calculation units for calculating the shift amounts of the two images by performing a correlation calculation based on the distance measuring principle described later, and 206 to 210 are shift amount calculation units 201 to 2
The defocus amount calculation unit 211 calculates the defocus amount of the photographing lens based on the deviation amount output from each of the reference numerals 05, and the distance measuring units A _{1 to} A ₅ based on the information on the direction of the line of sight calculated by the line-of-sight calculation circuit CKT. Is a distance measuring point selecting unit for selecting a distance measuring point represented by
The taking lens is driven via the lens control circuit LKT so as to minimize the defocus amount (selected from 206 to 210) from the sensor corresponding to the distance measurement point selected in 11.

FIG. 10 shows an example of the multi-photometry unit of the camera of this embodiment. B _{1 to} B ₅ are photometric units. For example, when the line of sight enters the range of the visual line detection visual field K ₁ , the photometric unit B
The weighting evaluation calculation is performed by the evaluation calculation circuit EM so that the weight of ₁ becomes large.

FIG. 11 shows an example of the internal configuration of the evaluation operation circuit EM. Reference numerals 301 to 305 denote photoelectric conversion elements S _{1 to} S _5.
Corresponding to the photometric value output unit, 306 is a weighting calculation unit, is configured to perform the optimum weighted photometric calculation based on the contrast of these photometric value output,
As described above, in the present embodiment, the information on the direction of the line of sight output from the line-of-sight calculation circuit CKT is input to the weighting calculation unit 306, and the weighting calculation is performed so as to perform weighting on the line-of-sight direction. .

Therefore, the optimum exposure amount can be obtained only by the photographer directing his or her line of sight to the main subject.

Further, there is a phase difference method as a focus detection method for a single-lens reflex camera. FIG. 13 is an explanatory view of focus detection of the phase difference method, in which the left side is an optical path diagram of the focus detection optical system and the right side is. 3 is a light amount distribution chart on a light amount detecting element (hereinafter referred to as a line sensor).

In the figure, 601 is a field mask, 602 is a field lens, 603 is a secondary imaging lens, 604 is a line sensor, and 605 is a photographing lens. The field lens 602 is arranged in the vicinity of the film equivalent surface of the taking lens 605 and the exit pupil of the taking lens 605 and the secondary imaging lens 6
The entrance pupil of 03 is set so as to satisfy the conjugate relationship. Further, a diaphragm (not shown) is arranged near the entrance pupil plane of the secondary imaging lens 603, and the diaphragm is set to a size such that the light flux passing through the aperture cannot be blocked in the photographing lens 605. .

The subject light emitted from the point light source P on the optical axis of the taking lens 605 (parallel to the X axis in the figure) is imaged in the vicinity of the visual field mask 601 via the taking lens 605. The subject light that has passed through the opening of the field mask 601 passes through the field lens 602, is converged by the secondary imaging lens 603, and is projected onto the line sensor 604. The field mask 601 has an opening corresponding to the focus detection area on the photographing screen, and prevents light from outside the focus detection area from being guided to the line sensor 604. Secondary imaging lens 6
No. 03 has a focal length and arrangement so that a subject image on the film equivalent surface of the taking lens 605 is re-imaged on the line sensor 604 at a predetermined magnification. The secondary imaging lenses 603 are arranged symmetrically parallel to and decentered from the optical axis of the taking lens 605, and each of the secondary imaging lenses 603 is arranged.
Receives light fluxes from different areas within the exit pupil of the taking lens 605 and forms an image on each of the line sensors 604 including a pair of line sensors a and b.

FIG. 13A shows a state in which the positional relationship between the subject P, which is a point light source, the taking lens 605, and the film equivalent surface satisfies the in-focus state. A light amount distribution on the line sensor 604 at this time is shown in FIG. 13D, and a light amount distribution having a sharp peak is generated at a substantially central position of each line sensor a and b, and the interval between peak positions is l ₀
Is.

L ₀ is an independent value determined by the configuration of the focus detection optical system.

FIG. 13B shows an optical path diagram in a front focus state in which the taking lens 605 is extended to the subject side, and the light amount distribution on the line sensor 604 at this time is shown in FIG.
As described above, the distribution with low sharpness is exhibited, and the interval l between the peak positions of the light amount distributions on the line sensors a and b is narrower than the interval l _{0 in the} focused state. Since the difference Δl (= 1−l ₀ ) between the peak position intervals has a corresponding relationship with the defocus amount of the photographing lens 605, focus detection is performed from this amount Δ1.

FIG. 13C shows an optical path diagram in a state in which the taking lens 605 is retracted to the film equivalent surface side and is in a pinned state. The light amount distribution on the line sensor 604 at this time is shown in FIG.
As shown in (F) of 3, the distribution of low sharpness is exhibited, and the interval l between the peak positions on the line sensors a and b is wider than the interval l ₀ in the focused state. The difference between these intervals Δl
Since (= 1-l ₀ ) has a correspondence relationship with the defocus amount of the taking lens, focus detection is performed from this amount Δl.
Even in the case of a normal subject having a luminance distribution, the subject images on the line sensors a and b are correlated, and the shift amount of the two images (Δ
Focus detection is performed according to l).

FIG. 14 is a perspective view of another focus detection optical system for detecting the focus of a plurality of areas on the screen.

In the figure, reference numeral 701 is a visual field mask, and 701a, 701a
01b, 701c, 701d and 701e are openings of the visual field mask, 731, 732, 733 and 734 are secondary imaging lenses, 740, 741, 742, 743, 744 and 74.
5,746,747,748,749 are line sensors,
Reference numeral 706 is an aperture, and 761, 762, 763 and 764 are apertures of the aperture, and the field lens is omitted.

Since the field mask 701 is arranged near the focal plane of the taking lens, the opening of the field mask 701 coincides with the focus detection area. 2 in the opening of the visual field mask 701
The line sensor group 704 is arranged at the position of the conjugate image formed by the next imaging lens group 703.

Aperture of field mask 701 and secondary image formation 70
3 and Table 1 show the correspondence with the line sensor 704.

[0053]

[Table 1]

Each corresponding line sensor 742 and 743
744 and 745, 748 and 749, 740 and 741,74
By taking the correlation between the output signals of 6 and 747, the focus position of each distance measuring visual field portion is detected as in the case described above.

[0055]

As described above, according to the present invention,
In an optical instrument having a focus detection unit for detecting the focus for each of a plurality of focus detection regions and a line-of-sight detection device having a line-of-sight detection unit for detecting the line-of-sight of the user, a line-of-sight determination including the focus detection region is provided. When the user's line of sight is located within the area, the user has a selecting means for selecting a focus detection area corresponding to the line-of-sight determination area in which the line of sight is located, so that the user has a line-of-sight determination area including the focus detection area. A desired focus detection area can be selected if the line of sight is located inside.

Therefore, a desired focus detection area can be selected without completely matching the line of sight with the focus detection area.

Further, by providing the line-of-sight determination area, it is possible to obtain the effect that the detection error of the line-of-sight detection means can be absorbed.

[Brief description of drawings]

FIG. 1 is a diagram showing a horizontal scanning signal corresponding to the position of an eyeball.

FIG. 2 is a diagram showing a relationship between luminance and a diameter of a pupil.

FIG. 3 is a characteristic diagram of a luminance meter (light meter) of a camera.

FIG. 4 is a conversion diagram for calculating a pupil diameter from a luminance meter of a camera.

FIG. 5 is an optical block diagram showing an embodiment of a camera with a line-of-sight detection device.

FIG. 6 is a block diagram of an electric circuit of the embodiment shown in FIG.

7 is a block diagram of the line-of-sight calculation circuit of FIG.

FIG. 8 is a diagram showing a multi-point distance measuring unit.

FIG. 9 is a block diagram of a distance measurement calculation circuit.

FIG. 10 is a diagram showing a multi-photometric unit.

FIG. 11 is a block diagram of an evaluation calculation circuit.

FIG. 12 is a schematic view of a conventional visual line detection device that detects a visual line using a corneal reflection image and the center of a pupil.

FIG. 13 is a diagram illustrating the principle of a phase difference type focus detection system.

FIG. 14 is a perspective view of a photometry and ranging system.

[Explanation of symbols]

1 ... Lens for photographing 2 ... Quick return mirror 3 ... Focus plate 4 ... Condenser lens 5 ... Penta prism 6 ... Photometric condenser lens 7 ... Photometric element 8 ... Sub-mirror 9 ... Field mask 10 ... Field lens 11 ... AF light beam folding mirror 12 ... Secondary imaging lens 13 ... Photoelectric conversion element 14 ... Eyepiece lens 15 ... Lens for both projection and reception 16 ... Beam splitter 17 ... Infrared LED for projection 18 ... Photoelectric conversion element (linear or area type) 19 ... Eyeball 20 ... Shatter 21 ... Film

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Claims (7)

[Claims] 1. An optical instrument having a focus detection unit for detecting focus for each of a plurality of focus detection regions and a line-of-sight detection device having a line-of-sight detection unit for detecting the line-of-sight of a user, the focus detection region being included. When the user's line of sight is located within the line-of-sight determination region provided as a line-of-sight determination region, a line-of-sight detection device is provided that has a selection unit that selects a focus detection region corresponding to the line-of-sight determination region in which the line of sight is located. Optical equipment. 2. A focus detection unit for detecting focus for each of a plurality of focus detection regions, a line-of-sight detection unit for detecting the user's line of sight, and a line-of-sight determination region including the focus detection region. Based on the detection result of the line-of-sight detection means,
And a determination unit that determines which of the plurality of visual line determination regions the visual line of the user is located in, and a selection unit that selects the focus detection region from the determination result of the determination unit. An optical device having a characteristic line-of-sight detection device. 3. An optical device having a line-of-sight detection device having focus detection means for detecting the focus of each of a plurality of focus detection areas and a line-of-sight detection means for detecting the line-of-sight of the user, wherein the focus detection means is the use. An optical system having a line-of-sight detection device for selecting a focus detection region based on the position of the line of sight of a person, wherein a line-of-sight determination region for selecting the focus detection region is set so as to surround the focus detection region. machine. 4. The optical device having the visual line detection device according to claim 1, wherein the visual line determination areas are set adjacent to each other. 5. A plurality of line-of-sight determination areas set adjacent to each other and a direction of the user's line-of-sight to determine which of the line-of-sight determination areas the user's line of sight is located in. An optical device having a visual axis detection device having. 6. An optical device having the line-of-sight detection device has a focus detection unit capable of performing focus detection with respect to a plurality of focus detection regions in a screen, and each of the plurality of focus detection regions is the plurality of line-of-sight lines. The optical device having the visual line detection device according to claim 5, wherein the optical device is set so as to be included in the determination region. 7. An optical device having the line-of-sight detection device includes a photometric unit capable of performing photometry on a plurality of photometric regions within a screen, and a photometric control unit for controlling the photometric unit. The region corresponds to each photometric region, and the photometric control means weights the photometric region corresponding to the visual line determination region where the visual line of the user is located. An optical instrument including the line-of-sight detection device according to item 6.