JP5690130B2 - Pupil diameter measuring device - Google Patents

Description

  The present invention relates to a pupil diameter measuring device that measures an actual pupil diameter.

  Conventionally, as a technique for measuring a pupil, a technique described in Patent Document 1 below is known.

  In Patent Document 1, a subject such as a normal healthy person measures a pupil as his / her own biological index. In Patent Document 1, a reflecting surface having a reflecting function that enables observation of an image of one's own pupil, an alignment mark that aligns the pupil of the subject, and a subject's pupil are arranged so as to sandwich the reflecting surface. An infrared imaging device, an infrared illumination means for illuminating the pupil of the subject, a projection optical system that projects an image of the pupil of the subject on the imaging surface of the external imaging device, and based on pupil image information sent from the infrared imaging device It is described that calculation analysis of the size of the pupil is performed.

JP 2007-144113 A

  However, in the above-described pupil diameter measuring apparatus, it is necessary to accurately determine the distance from the pupil to the infrared imaging element and the actual size within the imaging range of the infrared imaging element. For this reason, this pupil diameter measuring apparatus cannot accurately calculate the pupil diameter unless the distance and the imaging range are calibrated.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and provides a pupil diameter measuring device that can measure the pupil diameter with high accuracy without adjusting the distance from the imaging device or the like. With the goal.

A pupil diameter measuring apparatus according to a first invention that solves the above-mentioned problem is a pupil diameter measuring apparatus that measures a pupil diameter of a subject, an index irradiating unit that irradiates an index near the pupil of the subject, and the index An image acquisition unit that acquires a captured image including a pupil, an index image that extracts an index image from the captured image, calculates an actual size of the index image in the captured image, and a pupil image that is extracted from the captured image A pupil diameter calculating unit that calculates the actual size of the pupil of the subject using the actual size of the index image calculated by the index size calculating unit , and the index irradiating unit has the predetermined size Irradiating an index, the index size calculation unit calculates the actual size per pixel by comparing the predetermined size and the size of the index image in the captured image, the pupil diameter calculation unit, The finger And the actual size per one pixel, which is calculated by the size calculating unit, by multiplying the number of pixels the pupil image, and calculates the actual size of the pupil of the subject.

The pupil diameter measuring apparatus according to the first invention, wherein the index irradiating unit irradiates two or more indexes, and the index size calculating unit is an actual irradiation of the subject. Compare the size of the index or the interval between the indexes with the size of multiple index images in the captured image or the interval between the index images, and calculate the actual size per pixel for each size or for each interval. It is characterized by doing.

A pupil diameter measuring apparatus according to a second invention, wherein the index irradiating unit is arranged in at least one direction of a vertical direction or a horizontal direction to irradiate a plurality of indexes. .

A pupil diameter measuring apparatus according to a third aspect of the present invention is characterized in that the index irradiation unit is arranged in a grid and irradiates a plurality of indexes.

The pupil diameter measuring apparatus according to any one of the first to third inventions, wherein the fifth invention is the size of the first index image or the interval between the first index images and the actual index size or index Calculated from the first actual size per pixel calculated from the interval between and the size of the second index image or the interval between the second index images and the actual size of the second index or the interval between the second indexes. The second actual size per pixel is interpolated to calculate a size per pixel between the first actual size and the second actual size.

In the pupil diameter measuring apparatus according to the fifth invention, the sixth invention is characterized in that the index size calculation unit is configured such that the size of the first index image or the interval between the first index images and the actual size of the first index. Or the first actual size per pixel calculated from the interval between the first index images and the size of the second index image or the interval between the second index images and the actual size of the second index or the second The second actual size per pixel calculated from the interval between the indexes is interpolated by a curve.

A pupil diameter measuring apparatus according to any one of the first to sixth aspects, a seventh aspect of the present invention, the index is characterized by a Purkinje image.

The pupil diameter measuring apparatus according to any one of the first to seventh inventions, wherein the eighth invention includes a reflecting portion disposed so as to face the pupil of the subject, and the index irradiating portion is indexed by the reflecting portion. Is reflected, and an index is irradiated in the vicinity of the pupil of the subject.

  According to the present invention, the index is irradiated near the pupil, the index image is extracted from the captured image, the actual size of the index image is calculated, the pupil image is extracted from the captured image, and the pupil of the subject is used using the actual size of the index image. Therefore, the pupil diameter can be measured with high accuracy without calibrating the pupil diameter measurement condition.

It is a perspective view of a pupil diameter measuring device shown as one embodiment of the present invention. It is a side view of a pupil diameter measuring device shown as one embodiment of the present invention. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a block diagram of the structure which irradiates a single parameter | index. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows the captured image acquired when a single parameter | index is irradiated. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a block diagram of the structure which irradiates a some parameter | index. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows the captured image acquired when a some parameter | index is irradiated. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows the relationship between the actual parameter | index, the parameter | index on a captured image, and the actual size of an image range. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows the influence at the time of a single parameter | index irradiation, and the effect at the time of several parameter | index irradiation when a parameter | index is missing and irradiated or extracted. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows a mode when a Purkinje image is irradiated. 5 is a flowchart showing an operation procedure for measuring a pupil diameter by irradiating a single index in the pupil diameter measuring apparatus shown as an embodiment of the present invention. 5 is a flowchart showing an operation procedure for measuring a pupil diameter by irradiating a plurality of indices in the pupil diameter measuring apparatus shown as an embodiment of the present invention. 6 is a flowchart showing an operation procedure for measuring the pupil diameter by controlling the irradiation timing of a single index in the pupil diameter measuring apparatus shown as an embodiment of the present invention. 5 is a flowchart showing an operation procedure for measuring the pupil diameter by controlling the irradiation timing of a plurality of indices in the pupil diameter measuring apparatus shown as an embodiment of the present invention. In the pupil diameter measuring apparatus shown as one embodiment of the present invention, (a) is an explanatory diagram for changing the actual size per pixel for each region including an index, and (b) is 1 for each region including an index interval. It is explanatory drawing which changes the actual size per pixel. In the pupil diameter measuring apparatus shown as an embodiment of the present invention, (a) is an explanatory diagram for interpolating the actual size per pixel of an adjacent area including an index, and (b) is an adjacent area including an index interval. It is explanatory drawing which interpolates the actual size per pixel for every. In the pupil diameter measuring apparatus shown as an embodiment of the present invention, (a) is an explanatory diagram in which the actual size per pixel of an adjacent region including an index is curve-interpolated, and (b) is an adjacent including an index interval. It is explanatory drawing which carries out curve interpolation of the actual size per pixel for every area | region. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a top view which shows the state which irradiated the some parameter | index to the eyeball. It is a figure which shows the state which has arrange | positioned the single parameter | index in the grid shape in the pupil diameter measuring apparatus shown as one Embodiment of this invention. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows the state which has arrange | positioned the space | interval formed with two parameter | indexes in the shape of a grid. It is a figure which shows the state which has arrange | positioned LED which irradiates a single parameter | index circularly in the pupil diameter measuring apparatus shown as one Embodiment of this invention. In the pupil diameter measuring apparatus shown as one Embodiment of this invention, it is a figure which shows arrangement | positioning of LED for making the space | interval formed with two parameter | index circular.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The pupil diameter measuring apparatus to which the present invention is applied does not require calibration such as the distance between the pupil and the camera position in order to measure the pupil diameter, and improves the measurement accuracy. For this purpose, the pupil diameter measuring device images an index irradiated to the periphery of the pupil or the face, and calculates the actual size of the imaging range. This will be described below.

[Basic configuration of pupil diameter measuring device]
This pupil diameter measuring apparatus is configured as shown in FIGS. 1 and 2, for example. The pupil diameter measuring device includes camera units 1A and 1B (hereinafter simply referred to as “camera unit 1” when collectively referred to), half mirror 2, and index irradiation units 3A and 3B (hereinafter simply referred to as “ It is referred to as an index irradiation unit 3 ”), a head holder 4 and a jaw holder 5.

  The camera unit 1 includes a right-eye camera unit 1A including an eyeball of a subject's right eye as an imaging range, and a left-eye camera 1B including an eyeball of the subject's left eye as an imaging range. The camera unit 1 generates a captured image including a pupil and an index using light received through the half mirror 2.

  The half mirror 2 is provided at a position facing the pupil of the subject. The half mirror 2 is configured such that the outside world can be seen in a state in which the subject is looking straight in a state where the subject holds the eyeball with the head holder 4 and the jaw holder 5. Thereby, the pupil diameter measuring apparatus can measure the pupil diameter in a so-called daily vision state in which the subject is brightly lit without largely obstructing the field of view.

  When the index irradiating unit 3 is arranged toward the half mirror 2, the half mirror 2 reflects the index light irradiated from the index irradiating unit 3 in the vicinity of the pupil. The half mirror 2 is preferably a mirror that transmits visible light and totally reflects infrared light, but actually has about 10% reflection of visible light and transmission of infrared light.

  In this embodiment, although the structure provided with the half mirror 2 is shown, even if it is not provided with the half mirror 2, the camera part 1 may be installed in the test subject's substantially front, and a test subject's pupil may be imaged. .

  The index irradiator 3 is composed of an IR-LED or a laser, and irradiates index light with high directivity and low diffusivity. Thereby, LED3a can irradiate the test subject's pupil vicinity or face with the parameter | index by which the dimension was set previously, or the some parameter | index with which the space | interval was set beforehand. The index irradiation unit 3 may be used in combination with an IR-LED for pupil detection.

  The index irradiation unit 3 includes an index irradiation unit 3A obliquely above and an index irradiation unit 3B diagonally below the eyeball of the subject. Each index irradiation part 3A, 3B has a plurality of LEDs 3a built in a rod-shaped housing. Each LED 3a is positioned in the vicinity of the pupil or the face of the subject whose irradiation direction is the imaging range of the camera unit 1. It is desirable that the index irradiation unit 3 does not enter the field of view of the subject. For example, it is desirable that the index irradiation unit 3 is arranged so as not to fall within a range of 120 degrees or more in the vertical direction within the visual field.

  The LED 3a is preferably a laser that is positioned in class 1 according to JIS C 6802 classification. That is, the LED 3a irradiates near the pupil of the subject, and is a laser that is safe under a reasonably foreseeable driving situation. It is necessary to have an intrinsically safe level of laser.

  The LED 3a of the index irradiating unit 3 is controlled by the index size / pupil diameter calculating unit 12 to control irradiation timing such as switching between on and off. Thus, a single index or a plurality of indices can be selected and irradiated near the pupil of the subject. Furthermore, the index irradiating unit 3 can irradiate the index with any one of the plurality of index arrangements as described later.

  Such a pupil diameter measuring device is provided with a reflecting portion such as the half mirror 2 in front of the subject, and the index irradiated from the index irradiating unit 3 is reflected by the reflecting portion and guided near the pupil of the subject. As a result, the index irradiating unit 3 is not disposed in front of the pupil, and space saving is possible. Moreover, when the half mirror 2 is used as a reflection part, a pupil diameter can be measured in the state close | similar to the daily life of the state where the front of eyes was open | released. As a result, the vicinity of the eye of the subject is covered, the vicinity of the eyeball becomes dark and the pupil diameter increases, and it is possible to avoid an increase in cost that the daily pupil diameter cannot be measured unless the brightness is adjusted by illumination or the like.

  Hereinafter, a specific example in which the pupil diameter measuring apparatus having the above-described configuration measures the pupil diameter will be described with reference to FIGS. 3 to 9.

[Pupil diameter measuring device using a single index]
FIG. 3 shows a configuration of the above-described pupil diameter measuring device that emits a single index.

  This pupil diameter measuring apparatus includes an index irradiation unit 3 as a single light source. The index irradiation unit 3 irradiates a single index 20 in accordance with a control signal from the index size / pupil diameter calculation unit 12. In addition, the index irradiation part 3 should just irradiate the single parameter | index 20 by which the magnitude | size was preset by single or several LED3a among several LED3a. As a result, the single index 20 is applied to the face around the pupil 101 and the iris 102. It should be noted that the irradiation of the index 20 does not always have to be performed during the measurement, and may be performed only at the timing immediately before measuring the pupil diameter.

  The camera unit 1 captures a single index 20 by the index irradiation unit 3 and generates a captured image 111 as shown in FIG. The captured image 111 includes a pupil image 101A, an iris image 102A, and an index image 20A.

  The pupil diameter measuring device includes a pupil / index extraction unit 11 and an index size / pupil diameter calculation unit 12. The pupil / index extraction unit 11 and the index size / pupil diameter calculation unit 12 are realized by processing in a personal computer or the like (not shown).

  The pupil / index extraction unit 11 extracts the pupil image 101A and the index image 20A from the captured image 111 captured by the camera unit 1. At this time, the pupil / index extraction unit 11 extracts the pupil image 101A and the index image 20A based on the luminance in the captured image 111. The binarization threshold value for extracting the pupil image 101A and the index image 20A is set in advance. For example, the darkest luminance circular area in the captured image 111 is extracted as the pupil image 101A, and the brightest circular area in the captured image 111 is extracted as the index image 20A.

  The index size / pupil diameter calculation unit 12 calculates the actual size of the pupil image 101A using the pupil image 101A and the index image 20A extracted by the pupil / index extraction unit 11. At this time, the index size / pupil diameter calculation unit 12 calculates the actual size of the index image 20A (for example, the diameter) in the captured image 111, and uses the calculated actual size of the index image 20A. The actual size of the diameter of the pupil 101 of the subject is calculated.

  Specifically, the index size / pupil diameter calculation unit 12 compares the actual size of the index 20 irradiated to the subject with the size of the index image 20A in the captured image 111, and calculates the actual size per pixel. To do. The actual size per pixel is a coefficient for converting the size [pixel] of the pupil image into the actual size [mm] of the pupil. For example, in the captured image 111, when the dimension of the single index 20 irradiated by the index irradiation unit 3 is a [mm] and the index image 20A is s [pixel], per pixel in the captured image 111 The dimension is a / s [mm].

  Then, the index size / pupil diameter calculation unit 12 multiplies the calculated actual size [mm] per pixel by the number of pixels corresponding to the diameter of the pupil image 101A to calculate the actual size [mm of the subject's pupil 101]. ] Is calculated. For example, as shown in the upper part of FIG. 7, when the diameter of the pupil image 101A in the captured image 111 is x [pixels], the pupil diameter can be obtained by ax / s [mm].

  As described above, according to this pupil diameter measuring apparatus, the index 20 having a predetermined size is irradiated, and the size [pixel] of the index image 20A in the captured image 111 is used for each pixel of the captured image 111. The actual size [mm] can be obtained. Thereby, according to this pupil diameter measuring apparatus, the number of pixels of the pupil image 101A can be converted into the actual size [mm] of the pupil diameter using the actual size per pixel.

  Therefore, according to this pupil diameter measuring apparatus, it is possible to measure the pupil diameter with high accuracy without performing calibration of pupil diameter measurement conditions.

[Pupil diameter measuring device using multiple indices]
Next, in the above-described pupil diameter measuring apparatus, a configuration for irradiating a plurality of indices is shown in FIG.

  This pupil diameter measuring apparatus irradiates a plurality of indexes 20 by a plurality of LEDs 3a, like the index irradiation unit 3 shown in FIGS. At this time, the index irradiation unit 3 controls which LED 3 a is turned on according to the control signal of the index size / pupil diameter calculation unit 12. As a result, the plurality of indexes 20 are irradiated onto the face around the pupil 101 and the iris 102 at predetermined intervals. It should be noted that the irradiation of the index 20 does not always have to be performed during the measurement, and may be performed only at the timing immediately before measuring the pupil diameter.

  Moreover, it is desirable to irradiate the plurality of indexes 20 as a Purkinje image, for example, as shown in FIG. A Purkinje image is a corneal reflection image that appears bright when the cornea is irradiated with point light source illumination. This Purkinje image is known to be used in, for example, a corneal reflection method that measures eye movement.

  When IR-LED is used as the light source of the index irradiating unit 3, the black part of the pupil is emphasized. And since it is also used as illumination near the eyes, the luminance in the middle is extremely bright, so that a Purkinje image corresponding to the position of the LED 3a appears clearly. It should be noted that the irradiation with the Purkinje image in this way can be realized even when the above-described single index is irradiated.

  The camera unit 1 images a plurality of indexes 20 by the index irradiation unit 3 to generate a captured image 111 as shown in FIG. The captured image 111 includes a pupil image 101A, an iris image 102A, an index image 20A, and an index image 20B.

  The pupil / index extraction unit 11 extracts the pupil image 101A, the index image 20A, and the index image 20B from the captured image 111 captured by the camera unit 1. At this time, the pupil / index extraction unit 11 extracts the pupil image 101A, the index image 20A, and the index image 20B based on the luminance in the captured image 111. The binarization threshold value for extracting the pupil image 101A, the index image 20A, and the index image 20B is set in advance. For example, the darkest circular area in the captured image 111 is extracted as the pupil image 101A, and the brightest circular area in the captured image 111 is extracted as the index image 20A and the index image 20B.

  The index dimension / pupil diameter calculation unit 12 calculates the actual size of the pupil image 101A using the pupil image 101A, the index image 20A, and the index image 20B extracted by the pupil / index extraction unit 11. At this time, the index size / pupil diameter calculation unit 12 calculates the actual size of the interval between the index image 20A and the index image 20B in the captured image 111, and the actual size of the calculated interval between the index image 20A and the index image 20B. Is used to calculate the actual diameter of the pupil 101 of the subject.

  Specifically, the index dimension / pupil diameter calculation unit 12 calculates the actual size per pixel by comparing the actual interval of the index 20 irradiated to the subject with the size of the index image 20A in the captured image 111. To do. For example, as shown in the lower part of FIG. 7, in the captured image 111, the interval between the two indexes 20 irradiated by the index irradiation unit 3 is b [mm], and the interval between the index image 20A and the index image 20B is s. In the case of [pixel], the size per pixel in the captured image 111 is b / s [mm].

  Then, the index size / pupil diameter calculation unit 12 multiplies the calculated actual size [mm] per pixel by the number of pixels corresponding to the diameter of the pupil image 101A to calculate the actual size [mm of the subject's pupil 101]. ] Is calculated. For example, when the diameter of the pupil image 101A in the captured image 111 is x [pixel], the pupil diameter can be obtained by bx / s [mm].

  Therefore, according to this pupil diameter measuring apparatus, it is possible to measure the pupil diameter with high accuracy without performing the calibration of the pupil diameter measuring conditions, similarly to the pupil diameter measuring apparatus using a single index.

  Further, when the size of the index 20 is used as described above, as shown in the left column of FIG. 8, if a part of the index 20 is missing and irradiated or extracted, the size of the original index 20 is obtained. The pupil diameter is measured by a size D ′ different from D. Then, an error occurs in the actual size per pixel determined based on the index image, and the exact actual pupil size cannot be converted from the pupil image.

  However, according to this pupil diameter measuring apparatus, since the interval between the indexes 20 is used, as shown in the right column of FIG. 8, even if the index 20 is missing, the original interval D and the actual interval The difference from D 'is small and is not easily affected by the actual size conversion accuracy. Therefore, according to this pupil diameter measuring apparatus, the actual size conversion accuracy of the pupil diameter can be increased as compared with the pupil diameter measuring apparatus using a single index.

  Further, according to this pupil diameter measuring apparatus, by using a Purkinje image as the index 20, the actual size per pixel can be calculated closer to the pupil with respect to the pupil diameter position to be measured. Thereby, according to this pupil diameter measuring apparatus, the pupil diameter can be measured with higher accuracy. Further, according to this pupil diameter measuring apparatus, the index irradiating unit 3 can be used in combination with a light source for measuring the pupil diameter, and the system configuration can be simplified.

[Operation procedure of pupil diameter measuring device]
Next, an operation procedure in the above-described pupil diameter measuring apparatus will be described with reference to FIGS. 10 to 13.

  FIG. 10 shows an operation procedure by the pupil diameter measuring apparatus using a single index.

  In step S1, the pupil diameter measuring apparatus irradiates a single index 20 near the pupil of the subject from the index irradiation unit 3.

  In the next step S2, the camera unit 1 acquires a captured image in the imaging range including the index 20 and the pupil irradiated in step S1.

  In the next step S3, the pupil / index extraction unit 11 extracts an index image from the captured image acquired by the camera unit 1 in step S2.

  In the next step S4, the index dimension / pupil diameter calculation unit 12 measures the number of pixels of the captured image as the size of the index image extracted in step S3.

  In the next step S5, the index size / pupil diameter calculation unit 12 captures an image from the relationship between the actual index size [mm] determined in advance and the index image size [pixel] on the captured image. The actual size per pixel on the image is calculated.

  In the next step S6, the pupil / index extraction unit 11 extracts the pupil image acquired in step S2, and the index size / pupil diameter calculation unit 12 measures the number of pixels of the pupil image.

  In the next step S7, the index size / pupil diameter calculator 12 calculates the actual size of the pupil diameter by multiplying the number of pixels of the pupil image measured in step S6 by the actual size per pixel calculated in step S5. To do.

  Thereby, the pupil diameter measuring apparatus can irradiate a single index and measure the pupil diameter with high accuracy.

  FIG. 11 shows an operation procedure by the pupil diameter measuring apparatus using a plurality of indices.

  In step S1, the pupil diameter measuring device first irradiates a single index 20 near the pupil of the subject from the index irradiation unit 3, and in step S2, the camera unit 1 includes the index 20 irradiated in step S1. A captured image is acquired in an imaging range including the pupil.

  In the next step S3 ', the pupil / index extracting unit 11 extracts a plurality of index images from the captured image acquired by the camera unit 1 in step S2.

  In the next step S4 ', the index size / pupil diameter calculation unit 12 measures the number of pixels of the captured image as the interval between the index images extracted in step S3'.

  In the next step S5 ′, the index size / pupil diameter calculation unit 12 captures the captured image based on the relationship between the actual index interval [mm] determined in advance and the index image interval [pixel] on the captured image. Calculate the actual size per pixel above.

  In the next step S6, the pupil / index extraction unit 11 extracts the pupil image acquired in step S2, and the index size / pupil diameter calculation unit 12 measures the number of pixels of the pupil image.

  In the next step S7, the index size / pupil diameter calculation unit 12 multiplies the number of pixels of the pupil image measured in step S6 by the actual size per pixel calculated in step S5 ′ to obtain the actual size of the pupil diameter. calculate.

  Thereby, the pupil diameter measuring device can irradiate a plurality of indices and measure the pupil diameter with high accuracy.

  In the operation of the pupil diameter measuring apparatus described above, it is desirable that the index size / pupil diameter calculation unit 12 controls the index irradiation timing of the index irradiation unit 3. This pupil diameter measuring apparatus shows an operation when a single index is used, and FIG. 13 shows an operation using a plurality of indices.

  First, in step S10, the index size / pupil diameter calculation unit 12 determines whether or not to measure the pupil diameter. At this time, the index size / pupil diameter calculation unit 12 determines that measurement of the pupil diameter is to be performed when there is an input operation such as pressing a measurement start button (not shown), and the process proceeds to step S1. To proceed.

  The index dimension / pupil diameter calculation unit 12 controls the index irradiation unit 3 to perform the irradiation of the index in step S1, and controls the camera unit 1 to acquire the captured image in step S2 at the timing immediately thereafter. Make it. Thereby, the timing which irradiates a parameter | index from the parameter | index irradiation part 3 can be performed immediately before acquiring a captured image with the camera part 1. FIG.

  As described above, according to this pupil diameter measuring device, when the distance between the camera unit 1 and the pupil changes between the previous pupil diameter measurement and the current pupil diameter measurement, and the actual size per pixel changes. Even so, the pupil diameter can be measured with high accuracy. Further, according to this pupil diameter measuring apparatus, there are advantages in that the measurement of the pupil diameter does not interfere with the daily vision of the subject and the power saving required for the irradiation, compared to the case where the index is always irradiated.

[Specific example of measuring the actual size per pixel]
Next, a specific example in which the actual size per pixel is determined using the size of two or more indexes or the interval between two or more indexes in the above-described pupil diameter measuring apparatus will be described.

  The pupil diameter measuring device irradiates two or more indices by the index irradiating unit 3, and the actual size for each index irradiated to the subject by the index size / pupil diameter calculating unit 12 and the index in the captured image. The actual size per pixel is calculated for each index by comparing a plurality of sizes between images. Alternatively, the pupil diameter measuring device emits three or more indices by the index irradiating unit 3, and the actual interval between the indices irradiated to the subject by the index dimension / pupil diameter calculating unit 12 and the captured image The actual size per pixel is calculated for each interval between the indexes by comparing a plurality of intervals between the index images.

At this time, the index irradiation unit 3 is arranged in at least one direction of the vertical direction or the horizontal direction and irradiates a plurality of indexes.
As shown in FIG. 14A, consider a case where two indicators such as indicators 20a and 20b are irradiated and the actual size per pixel is obtained based on the size of each indicator.

  In this case, the size of the actual index image irradiated in advance from the index irradiation unit 3 is a [mm], but on the captured image, the index 20a is S1 [pixel], and the index 20b is Assume that S2 [pixel].

  When the index size / pupil diameter calculation unit 12 detects a difference in the number of pixels between the index 20a and the index 20b, the index size / pupil diameter calculation unit 12 sets an image area 201 including the index 20a and an image area 202 including the index 20b in the captured image. . The image area 201 and the image area 202 are set with the midpoint between the center point of the index 20a and the center point of the index 20b as a boundary.

  Then, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 201 to a / S1 [mm]. On the other hand, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 202 to a / S2 [mm].

  As a result, the pupil diameter measuring device can detect the pixels included in the image area 201 of the pupil image and the image area 202 even if the pupil image appears in the captured image across the image area 201 and the image area 202. With the included pixels, the actual size per pixel can be changed, and the actual size per pixel can be multiplied by the number of pixels in the pupil image.

  As described above, according to this pupil diameter measuring apparatus, it is possible to improve the measurement accuracy of the pupil diameter by irradiating at least two or more indices and optimizing the actual size per pixel for each adjacent index. .

  Further, in the case of a pupil diameter measuring apparatus that uses an interval between indexes, as shown in FIG. 14B, three indexes 20a, 20b, and 20c are irradiated to acquire two intervals.

  In this case, the interval between the actual index images irradiated from the index irradiating unit 3 in advance is b [mm], but on the captured image, the interval between the indices 20a and 20b is t1 [pixel]. It is assumed that t2 [pixel] is between 20b and 20c.

  When the index size / pupil diameter calculation unit 12 detects a difference in the number of pixels at the intervals t1 and t2, the index size / pupil diameter calculation unit 12 sets an image area 201 including the indices 20a and 20b and an image area 202 including the indices 20b and 20c. To do. The image area 201 and the image area 202 are set with the center point of the index 20b as a boundary.

  Then, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 201 to b / t1 [mm]. On the other hand, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 202 to b / t2 [mm].

  Thereby, the pupil diameter measuring device changes the actual size per pixel between the image area 201 and the image area 202 even if the pupil image appears in the captured image straddling the image area 201 and the image area 202. The actual size per pixel can be multiplied by the number of pixels in the pupil image.

  As described above, according to this pupil diameter measuring apparatus, it is possible to improve the measurement accuracy of the pupil diameter by irradiating at least two or more indices and optimizing the actual size per pixel for each adjacent index. .

  In addition, it is desirable that the pupil diameter measuring device interpolates the actual size per pixel determined in the adjacent image region. Therefore, the index size / pupil diameter calculation unit 12 calculates the first actual size per pixel calculated from the size of the first index image and the actual size of the first index, the size of the second index image, and the actual first size. The second actual size per pixel calculated from the size of the two indices is interpolated to calculate the size per pixel between the first actual size and the second actual size. Alternatively, the index size / pupil diameter calculation unit 12 may calculate the first actual size per pixel calculated from the interval between the first index images and the actual first index interval, the second index image interval, and the actual second index image. The second actual size per pixel calculated from the index interval is interpolated to calculate the size per pixel between the first actual size and the second actual size.

  Specifically, as shown in FIG. 15A, the size of the actual index image that is determined in advance and is irradiated from the index irradiation unit 3 is a [mm]. Assume that the index 20a is S1 [pixel] and the index 20b is S2 [pixel].

  When the index size / pupil diameter calculation unit 12 detects the difference in the number of pixels between the index 20a and the index 20b, the image area 201 including the area on the left side from the center point of the index 20a in the captured image, and the center of the index 20a An image area 202 including an area from the point to the center point of the index 20b and an image area 203 including a right area from the center point of the index 20b are set.

  Then, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 201 to a / S1 [mm]. On the other hand, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 203 to a / S2 [mm]. Further, the index size / pupil diameter calculation unit 12 calculates the actual size per pixel in the image region 202 as the actual size a / S1 per pixel in the image region 201 and the actual size a / S2 per pixel in the image region 203. Interpolated value of At this time, the index size / pupil diameter calculation unit 12 linearly interpolates the actual size a / S1 per pixel and the actual size a / S2 per pixel.

  This linear interpolation includes, for example, the actual size of the image region 202 such that the actual size a / S1 in the image region 201 and the actual size a / S2 of the image region 203 gradually change with a linear inclination.

  Further, as shown in FIG. 15B, the interval between the actual index images irradiated in advance from the index irradiation unit 3 is b [mm], but the index 20a, Assume that t1 [pixel] is between 20b and t2 [pixel] is between the indicators 20b and 20c.

  When the index size / pupil diameter calculation unit 12 detects the difference in the number of pixels between the interval between the indexes 20a and 20b and the interval between the indexes 20b and 20c, the index size / pupil diameter calculation unit 12 An image area 201 including the area, an image area 202 including an area from the midpoint between the indices 20a and 20b to a midpoint between the indices 20b and 20c, and an image including an area on the right side from the midpoint between the indices 20b and 20c. An area 203 is set.

  Then, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 201 to b / t1 [mm]. On the other hand, the index size / pupil diameter calculation unit 12 sets the actual size per pixel in the image region 203 to b / t2 [mm]. Further, the index size / pupil diameter calculation unit 12 calculates the actual size per pixel in the image region 202 as the actual size b / t1 per pixel in the image region 201 and the actual size b / t2 per pixel in the image region 203. Interpolated value of At this time, the index size / pupil diameter calculation unit 12 linearly interpolates the actual size b / t1 per pixel and the actual size b / t2 per pixel.

  As a result, the pupil diameter measuring device can change the actual size per pixel for each position of the pupil image that appears in the captured image without the actual size per pixel changing in steps between adjacent image regions. . Therefore, according to this pupil diameter measuring apparatus, the measurement accuracy of the pupil diameter can be improved by optimizing the actual size per pixel.

  Further, in this pupil diameter measuring apparatus, when interpolating between adjacent image regions, the index size / pupil diameter calculating unit 12 calculates one pixel from the size of the first index image and the actual size of the first index. It is desirable to interpolate the first actual size per hit and the second actual size per pixel calculated from the size of the second index image and the actual size of the second index using a curve. Alternatively, the index size / pupil diameter calculation unit 12 may calculate the first actual size per pixel calculated from the interval between the first index images and the actual first index interval, the second index image interval, and the actual second index image. It is desirable to interpolate the second actual size per pixel calculated from the index interval with a curve.

  For example, when the image areas 201 to 203 are set as shown in FIG. 15A, the index size / pupil diameter calculation unit 12 calculates the actual size per pixel of the image area 202 as shown in FIG. The actual size a / S1 per pixel and the actual size a / S2 per pixel are set to values obtained by curve interpolation. Further, when the image areas 201 to 203 are set as shown in FIG. 15B, the index size / pupil diameter calculation unit 12 calculates the actual size per pixel of the image area 202 as shown in FIG. The actual size b / t1 per pixel and the actual size b / t2 per pixel are set to values obtained by curve interpolation.

  The method of curve interpolation is based on the difference in actual size b / t per pixel based on the difference in spacing between adjacent image regions. Specifically, the eyeball of the subject has a convex surface when viewed from the index light incident side, and the distance between the position of the camera unit 1 and each position on the eyeball is different by the convex surface. Therefore, even if the indicators are irradiated at equal intervals, in fact, as shown in FIG. 17, the interval e between the central portions is the longest among the intervals a to i between the indicators, and the interval becomes shorter as the interval between the ends becomes shorter. It is assumed that Therefore, the index size / pupil diameter calculation unit 12 performs curve interpolation between adjacent intervals so as to absorb the change in the actual size per pixel corresponding to the difference in the interval.

  Thereby, the pupil diameter measuring device can further improve the measurement accuracy of the pupil diameter by optimizing the actual size per pixel as compared with the case of linear interpolation.

[Arrangement example of multiple indicators]
Next, an example of the arrangement of a plurality of indices in the above-described pupil diameter measuring device will be described.

  The pupil diameter measuring device may be arranged in a grid shape by the index irradiating unit 3 to irradiate a plurality of indices.

  As shown in FIG. 18, the pupil diameter measuring apparatus using the size of the index arranges two indices in two directions, for example, the vertical direction and the horizontal direction. The index irradiating unit 3 irradiates each index so that the plurality of LEDs 3a designated by the index size / pupil diameter calculating unit 12 are turned on and has a predetermined size a [mm], and is arranged in a grid shape. Each indicator can be placed.

  As shown in FIG. 19, the pupil diameter measuring apparatus using the interval between indexes arranges, for example, 6 indexes so that one interval can be acquired in the vertical direction and two intervals can be acquired in the horizontal direction. Note that FIG. 19 shows an example in which six indicators are irradiated. However, it is only necessary to irradiate a plurality of indicators so as to acquire a vertical interval and a horizontal interval, or intervals in arbitrary plural directions. The index irradiating unit 3 illuminates each index so that the plurality of LEDs 3a designated by the index size / pupil diameter calculating unit 12 are turned on and the predetermined interval b [mm] is set in both the vertical and horizontal directions. Thus, each index can be arranged in a grid.

  As described above, the pupil diameter measuring device obtains the actual size per pixel between the adjacent indexes by arranging the indexes in a grid shape, and among the actual sizes per pixel for each adjacent interval, The actual size of the pupil can be determined using the near actual size per pixel. Therefore, the measurement accuracy of the pupil diameter can be further increased. That is, in FIGS. 14 to 17 described above, the indicators are arranged only in one direction, but by arranging them in a grid shape, the actual size per pixel can be acquired in two directions, the vertical direction or the horizontal direction.

  Further, as described above, this pupil diameter measuring apparatus may of course perform linear interpolation or curve interpolation on the actual size per pixel. Further, by arranging in a grid shape, it is possible to improve the interpolation accuracy when performing curve interpolation along the actual eyeball shape.

  In addition, in order to arrange in a grid shape, it is sufficient that there are at least three indexes, and a triangular shape may be used.

  Furthermore, as another example of the arrangement of the indices, a circular shape can be considered. For this reason, the pupil diameter measuring device arranges the LEDs 3a of the index irradiation unit 3 so as to surround the camera unit 1 in a circular shape. Thereby, the pupil diameter measuring apparatus can arrange | position a parameter | index not only in one direction but two-dimensionally, the index irradiation part 3 avoiding the camera part 1, and can raise the precision of pupil diameter measurement.

  Specifically, as shown in FIG. 20, the LED 3a is arranged so as to irradiate an index having a size of a [mm], or as shown in FIG. 21, the index can be irradiated at intervals of b [mm]. The LED 3a is disposed.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

1 Camera unit 2 Half mirror 3 Index irradiation unit 3a LED
4 Head holder 5 Jaw holder 11 Pupil / index extraction unit 12 Index size / pupil diameter calculation unit

Claims (8)

A pupil diameter measuring device for measuring a pupil diameter of a subject,
An index irradiating unit that irradiates an index near the pupil of the subject; and
An image acquisition unit for acquiring a captured image including the index and the pupil;
An index image is extracted from the captured image, and an index size calculator that calculates the actual size of the index image in the captured image;
A pupil diameter calculation unit that extracts a pupil image from the captured image and calculates the actual size of the pupil of the subject using the actual size of the index image calculated by the index size calculation unit ;
The index irradiation unit irradiates the index of a predetermined size,
The index size calculation unit calculates the actual size per pixel by comparing the predetermined size with the size of the index image in the captured image,
The pupil diameter calculation unit calculates the actual size of the pupil of the subject by multiplying the actual size per pixel calculated by the index size calculation unit and the number of pixels of the pupil image. Diameter measuring device. The indicator irradiation unit irradiates two or more indicators,
The index dimension calculation unit compares the size of the actual index irradiated to the subject or the interval between the indices, the size of a plurality of index images in the captured image or the interval between the index images, The pupil diameter measuring device according to claim 1 , wherein an actual size per pixel is calculated for each size or interval. The pupil diameter measuring device according to claim 2 , wherein the index irradiation unit is arranged in at least one direction of a vertical direction or a horizontal direction to irradiate a plurality of indexes. The pupil diameter measuring device according to claim 3 , wherein the index irradiating unit is arranged in a grid and irradiates a plurality of indices. The first actual size per pixel calculated from the size of the first index image or the interval between the first index images and the actual index size or the interval between the indexes, and the size or second of the second index image Between the first actual size and the second actual size by interpolating the second actual size per pixel calculated from the interval between the index images and the actual size of the second index or the interval between the second indexes. The pupil diameter measuring device according to any one of claims 1 to 3 , wherein a size per pixel is calculated. The index dimension calculation unit calculates the first index per pixel calculated from the size of the first index image or the interval between the first index images and the actual size of the first index or the interval between the first index images. The actual size and the second actual size per pixel calculated from the size of the second index image or the interval between the second index images and the actual size of the second index or the interval between the second indexes The pupil diameter measuring apparatus according to claim 5 , wherein interpolation is performed by the following. The indicator is the pupil diameter measuring apparatus according to any one of claims 1 to 6, characterized in that a Purkinje image. Comprising a reflecting portion arranged to face the subject's pupil;
The pupil diameter measuring device according to any one of claims 1 to 7 , wherein the index irradiation unit irradiates an index in the vicinity of the pupil of the subject by reflecting the index by the reflection unit. .

Images