JP7419900B2 - Rotation angle detection device for three-dimensional objects, retinal projection display device, head-mounted display device, optometry device, and input device - Google Patents

Description

The present invention relates to a rotation angle detection device for a three-dimensional object, a retinal projection display device, a head-mounted display device, an optometry device, and an input device.

The development of technology to detect the angle of rotation of three-dimensional objects with curvature, such as eyeballs, is progressing, and the position of the pupil of the eyeball (line of sight) based on the angle of rotation is used to create interfaces for controlling electronic devices and wearable displays such as head-mounted displays. It is expected to be applied to a variety of applications, including supporting image formation for devices, collecting gaze data from skilled engineers, and analyzing product attention.

Further, a configuration is disclosed in which the tilt position of the eyeball is detected by irradiating light onto the eyeball from a light source unit including a plurality of light emitting units that emit light with directionality, and detecting the receiving position of the reflected light by the eyeball. (For example, see Patent Document 1).

However, with the configuration of Patent Document 1, the rotation angle of the eyeball, etc. may not be detected with high accuracy because the light receiving position of only a portion of the reflected light is detected at the end of the light receiving position detecting means.

An object of the present invention is to improve the detection accuracy of the rotation angle of a three-dimensional object having curvature.

A rotation angle detection device for a three-dimensional object according to one aspect of the present invention includes a light source means including a plurality of light emitting sections, and a light source means that directs light emitted from the plurality of light emitting sections toward an illuminated surface having a curvature of the three-dimensional object. The plurality of light emitting parts includes a focusing reflection means for reflecting and focusing the light, and a light receiving position detecting means for receiving the reflected light reflected by the irradiated surface of the light and detecting a light receiving position of the reflected light. are arranged at non-uniform intervals, and the light receiving position detecting means detects the reflected light derived from the light emitted from the first light emitting part of the plurality of light emitting parts from one end of the light receiving position detecting means. When receiving light by a predetermined distance at the center side of the light receiving position detection means, the reflected light originating from a second light emitting section different from the first light emitting section among the plurality of light emitting sections is The light is received at the center of the light receiving position detecting means by the predetermined distance from the other end of the light receiving position detecting means.

According to the present invention, the detection accuracy of the rotation angle of a three-dimensional object having curvature can be improved.

FIG. 1 is a diagram illustrating a configuration example of a pupil position detection device according to an embodiment. FIG. 3 is a diagram showing an example of the relationship between rotation of the eyeball and the incident position of the laser beam on the PSD, where (a) is a diagram with the eyeball not rotating, and (b) is a diagram with the eyeball being rotated. be. It is a figure which shows the example of the condition which an off-axis optical system should satisfy|fill, (a) is a figure which shows the distance between elements, (b) is a figure which shows the geometric distance relationship expressed with a coaxial optical system. FIG. 3 is a diagram illustrating an example of the relationship between the effective area diameter of the concave mirror and the beam radius on the PSD light receiving surface. FIG. 2 is a block diagram showing an example of a hardware configuration of a processing unit according to an embodiment. It is a block diagram showing an example of functional composition of a processing part concerning an embodiment. 7 is a flowchart of an example of processing by the pupil position detection device according to the embodiment. 1 is a diagram illustrating a configuration example of a pupil position detection device according to a first embodiment. It is a figure of the example of the relationship between the rotation angle of an eyeball and the light receiving position by PSD, (a) is a figure of a light receiving position change according to the rotation angle of an eyeball, and (b) is a figure of a position in PSD. 2A and 2B are diagrams showing an example of arrangement of a plurality of light emitting units, in which (a) is a diagram showing a relationship between an anchor position and a position of a light emitting unit, and (b) is a diagram showing a position of each light emitting unit in a VCSEL. It is a figure which shows the example of the light-receiving area of PSD when an eyeball rotates in two axial directions. 3A and 3B are diagrams of other examples of light receiving position adjusting means, in which (a) is a cross-sectional view when a prism structure is used, (b) is a cross-sectional view when a diffraction structure is used, and (c) is a cross-sectional view when a lens array is used. (d) is a plan view when a two-dimensional lens array is used. FIG. 2 is a diagram illustrating a reflective condensing element including a liquid crystal reflective condensing structure. FIG. 3 is a diagram illustrating a light distribution state of liquid crystal molecules within a liquid crystal reflective light condensing structure. FIG. 3 is a diagram illustrating the light distribution state of incident and output light rays by a liquid crystal reflective light condensing structure. FIG. 3 is a diagram illustrating a light guide member coupling optical system using a liquid crystal reflective light condensing structure. FIG. 7 is a diagram illustrating a configuration example of a retinal projection display device according to a second embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate.

In the embodiment, a pupil position detecting device of an eyeball will be described as an example of a rotation angle detecting device for a three-dimensional object, and a case where the pupil position detecting device is mounted on a glasses-type support will be described as an example.

In each embodiment, the right eyeball of a "person" will be described as an example, but the same applies to the left eyeball. It is also possible to provide two optical devices or two retinal projection display devices and apply them to the eyeballs of both eyes.

[Embodiment]
<Configuration example of pupil position detection device 10>
FIG. 1 is a diagram illustrating an example of the configuration of a pupil position detection device 10 according to an embodiment.

As shown in FIG. 1, the pupil position detection device 10 includes a VCSEL (Vertical Cavity Surface Emitting Laser) 1, a concave mirror 2, a PSD (Position Sensitive Detector) 3, and a processing unit 100. has.

The VCSEL 1, concave mirror 2, and PSD 3 are arranged on an optical system support 4. The optical system support 4 is tiltably fixed to a spectacle frame 22 of a spectacle-type support 20 including a spectacle lens 21 and a spectacle frame 22 via a ball joint 4a. The inclination of the optical system support 4 can be adjusted via the ball joint 4a. The ball joint 4a constituting the installation fine adjustment mechanism can be fixed by using mechanical pressure between the spherical structure and its outer shell structure, or by fixing the ball joint 4a between the magnetized spherical structure and the metal opening structure. A fixing method using magnetic force can be used.

The glasses-type support 20 can be worn on a person's head. When the glasses-type support 20 is attached, the optical system including the VCSEL 1, the concave mirror 2, and the PSD 3 is placed close to the eyeball 30 (in front of the eye).

The VCSEL 1 as an example of "light source means" has a plurality of light emitting parts arranged two-dimensionally within a plane. Each light emitting section emits laser light having directivity and a finite spread angle. Here, the emitted laser light is an example of "light". Moreover, "a plurality of light emitting parts" is synonymous with "a plurality of light emitting points" or "a plurality of light emitting elements".

However, the light source means is not limited to a VCSEL as long as it can emit light. The light source means may be configured by two-dimensionally arranging a plurality of LDs (laser diodes) or LEDs (light emitting diodes) in a plane that emit laser light. Alternatively, a pulsed laser that emits pulsed laser light may be used. Furthermore, the light source means may be configured by combining a plurality of types of light sources.

Further, the wavelength of the laser light emitted from the VCSEL 1 is preferably the wavelength of near-infrared light, which is invisible light, so as not to obstruct the visibility of the "person" whose pupil position is being detected. However, the light is not limited to this, and visible light may be used.

The laser beam L0 emitted from the VCSEL 1 directs the space in front of the eyes toward the concave mirror 2 in a direction substantially parallel to the face of the person wearing the spectacle-type support 20 or the lens surface of the spectacle lens 21 worn. propagate. Further, the laser beam L0 is a diverging beam that propagates while expanding the beam diameter due to diffraction at the exit opening of the VCSEL 1. The divergence angle of the diverging light can be controlled by the shape of the aperture of the exit section. The laser beam L0 propagates while diverging and enters the concave mirror 2.

The concave mirror 2, which is an example of a focusing and reflecting means, has a reflecting surface with curvature, reflects the incident laser beam L0, and irradiates the eyeball 30 with a focused laser beam (also expressed as focused light) L1. The focused laser beam L1 enters the vicinity of the pupil 31 of the eyeball 30. The center of curvature of the concave surface of the concave mirror 2 is located off the optical axis of the optical path from the VCSEL 1 to the concave mirror 2, and the optical system including the VCSEL 1, the concave mirror 2, and the PSD 3 constitutes a so-called off-axis optical system. ing.

In the off-axis optical system according to the embodiment, the light before reaching the eyeball 30 propagates through the space in front of the eye adjacent to the eyeball 30 by turning around at least once or more without being reflected or scattered by the eyeball 30. , has reached the eyeball 30.

The angle of incidence of the focused laser beam L1 on the eyeball 30 is adjusted so that it enters the center of the pupil 31 of the eyeball 30 at a predetermined angle during normal vision. Further, the VCSEL 1 can emit laser light from a plurality of light emitting parts, and the laser light emitted from the plurality of light emitting parts is irradiated to a plurality of places on the eyeball 30 or irradiated to the eyeball 30 at a plurality of angles. Ru.

In addition to having a plurality of light emitting sections as described above, the VCSEL 1 is capable of high-speed modulation. By time-modulating the laser light irradiated to the eyeball 30 and extracting a component with a modulation frequency that matches the incident laser light from the output signal obtained by the PSD 3, the influence of light from the external environment (without modulation) can be eliminated. can be removed. As a result, the SN ratio can be improved, which is advantageous in detecting the pupil position in a bright environment. Furthermore, the amount of laser light irradiated onto the eyeball can also be reduced.

The pupil surface (corneal surface) of the eyeball 30, which is an example of the irradiated surface, is a transparent body containing water and generally has a reflectance of about 2 to 4%. The focused laser beam L1 that has entered the vicinity of the pupil 31 of the eyeball 30 is reflected (also expressed as reflected light) on the surface of the pupil 31 of the eyeball 30, and the reflected light propagates toward the PSD 3. In addition, below, in order to simplify description, the surface of the eyeball 30 may be called the eyeball 30, the surface of the pupil 31 may be called the pupil 31, and the surface of the cornea 32 may be called the cornea 32.

Here, the curvature of the reflective surface of the concave mirror 2 is determined so as to offset the divergence of the reflected laser light due to the curvature of the eyeball 30 or the cornea 32. By doing so, it is possible to prevent the beam diameter of the laser light L2 propagating toward the PSD 3 from expanding on the light receiving surface of the PSD element.

Although a concave mirror is shown as an example of a focusing/reflecting means, it is not limited to this as long as it can focus (converge) light; A wavefront control element using a diffractive optical element, a diffractive optical element, etc. may also be used.

Furthermore, if an anamorphic aspheric surface with different curvatures in two orthogonal directions within a plane intersecting the optical axis of the focused laser beam L1 is used as the concave surface of the concave mirror, the beam diameter of the laser beam L2 can be further miniaturized. This is preferable because the beam can be shaped into an isotropic state.

Furthermore, the irradiated surface is not limited to the eyeball 30, and the embodiment can be applied to any three-dimensional object having a curvature. For example, the embodiment can be applied to a three-dimensional object that includes a rotating body that is rotatable around a rotation center and a curved body that has a center of curvature, and the position of the center of rotation and the position of the center of curvature are different.

The PSD 3, which is an example of a "light receiving position detection means", detects the current value according to the distance of the incident light to the electrode in two orthogonal directions within the light receiving surface, and calculates the incident light from the ratio of the current values in the two orthogonal directions. It is a two-dimensional optical position detection element that calculates and outputs a detection signal indicating the position of light. The PSD 3 can output a detection signal indicating the position of a beam spot formed on the light receiving surface of the PSD 3.

More specifically, the PSD 3 includes four output terminals, a resistive film is disposed on a continuous light receiving surface (a light receiving surface not divided into pixels), and electrode pairs are provided in two orthogonal directions. The photocurrent generated at the beam spot position is divided into four parts depending on the distance from each output terminal. At this time, the electrical resistance caused by the resistive film acts so that the longer the distance between the beam spot position and the output terminal, the smaller the current. The PSD 3 can detect the electrical signal that has passed through the resistive film through four terminals, and can output a detection signal indicating the position within the light receiving surface obtained by electrical post-processing.

Further, the PSD 3 can convert the current generated by photoelectric conversion into an analog voltage signal and output it as a detection signal from four terminals. In other words, the PSD 3 can detect the position of incidence by determining the distance to each terminal using surface resistance.

By the way, when an image sensor (imaging device) is used as a light receiving position detection means instead of PSD3, the output result of the image sensor changes depending on the intensity of light incident on each pixel, and when the intensity is low, the output current decreases. . In order to reduce the influence of noise light such as sunlight, it is necessary to increase the output of the light source to increase the intensity of the light incident on the image sensor. In this case, increasing the intensity of the incident light is not preferable from the viewpoint of safety for the eyes.

Furthermore, in the case of an image sensor, image processing is required to detect the position, but a positional accuracy error may occur during the processing, and the processing load also increases.

By using PSD3 as a light receiving position detection means, the position is detected using the current division ratio (ratio) divided between the output terminals, so the position of the incident light can be detected without depending on the intensity of the incident light. , which is suitable because it does not require image processing.

However, the configuration of the PSD 3 described above is just an example, and other configurations may be used. Although an example of a two-dimensional PSD that detects a two-dimensional position within the light-receiving surface is shown as the PSD 3, a one-dimensional PSD that detects a one-dimensional position within the light-receiving surface may also be used.

The processing unit 100 outputs a control signal to drive the VCSEL 1 to emit light. Furthermore, the processing unit 100 receives a detection signal from the PSD 3 and executes a process of detecting the position of the pupil 31 of the eyeball 30, as described later. For example, the processing unit 100 can be placed in the eyeglass frame 22 or the like.

Since the position of the beam spot formed by the laser beam L2 on the light receiving surface of the PSD 3 changes depending on the inclination of the eyeball 30, the processing unit 100 detects the pupil position of the eyeball 30 by converting the detection signal of the PSD 3 into coordinate information. can do.

The PSD 3 can detect the position of the reflection point and the direction of the normal vector on the eyeball 30, and the pupil position detection device 10 can detect the position and normal vector of the detected reflection point and the surface shape model of the eyeball. Based on the correspondence, the pupil position can be "estimated".

Although FIG. 1 shows an example in which the optical system and the processing unit are arranged in the eyeglass frame 22, the present invention is not limited to this, and a head-mounted display, a headgear-type holding structure, or the like may be used.

<Following operation of the pupil position detection device 10 to eye movement>
Next, the operation of the pupil position detection device 10 to follow eyeball movements will be described.

Since the eyeball 30 makes eyeball movements such as rotation, the direction of the laser light L2 changes due to the rotation, which may cause the laser light L2 to deviate from the light receiving surface of the PSD 3. In contrast, the pupil position detection device 10 can prevent the laser beam L2 from deviating from the light receiving surface of the PSD 3 by performing control to sequentially or selectively change the light emitting portion that causes the VCSEL 1 to emit light.

FIG. 2 is a diagram illustrating the relationship between the rotation of the eyeball 30 and the incident position of the laser beam L2 on the PSD 3, in which (a) is a diagram illustrating a state where the eyeball is not rotated (during normal vision), and (b) ) is a diagram illustrating a state in which the eyeball is rotating.

FIG. 2 shows the propagation of laser light emitted from the two light emitting parts of the VCSEL 1. Laser light 11 emitted from one light emitting part is shown by a solid line, and laser light 12 emitted from the other light emitting part is shown by a broken line.

In FIG. 2A, the laser beam 11 reflected by the eyeball 30 is incident near the center of the light receiving surface of the PSD 3. In FIG. Therefore, the PSD 3 can detect the position of the laser beam 11 on the light receiving surface, and the pupil position detection device 10 can detect the position of the pupil 31 based on the detection signal of the PSD 3.

On the other hand, since the laser beam 12 reflected by the eyeball 30 does not enter the light receiving surface of the PSD 3, the PSD 3 cannot detect the position of the laser beam 12 on the light receiving surface, and the pupil position detection device 10 detects the position of the pupil 31. Unable to detect location.

Moreover, when the eyeball 30 rotates significantly, the laser beam 11 reflected by the eyeball 30 does not enter the light receiving surface of the PSD 3, as shown in FIG. 2(b). Therefore, the PSD 3 cannot detect the position of the laser beam 11 on the light receiving surface, and the pupil position detection device 10 cannot detect the position of the pupil 31.

On the other hand, since the laser beam 12 reflected by the eyeball 30 is incident near the center of the light receiving surface of the PSD 3, the PSD 3 can detect the position of the laser beam 12 on the light receiving surface, and the pupil position detection device 10 can detect the position of the pupil 31 based on the detection signal of the PSD 3.

In this way, the pupil position of the eyeball 30 can only be detected in a limited angular range with light from only one light emitting part, but by changing the light emitting part of the VCSEL 1, it is possible to detect the position of the pupil of the eyeball 30 using light emitted from one of the light emitting parts. Laser light can be made incident on the light receiving surface of the PSD 3. Thereby, even if the eyeball 30 rotates, it is possible to reduce the situation in which the laser light reflected by the eyeball 30 does not enter the light receiving surface of the PSD 3, and to expand the range in which the pupil position can be detected.

In other words, the PSD 3 detects the slight movement of the laser beam 12 based on the rotational movement of the eyeball 30, and the array of the plurality of light emitting parts of the VCSEL 1 detects the coarse movement of the laser beam 12 based on the rotational movement of the eyeball 30. In detecting the rotational angle of the rotational movement of 30, it is possible to achieve both high detection resolution and a wide detection range.

The light emitting section of the VCSEL 1 can be changed in time series according to (following) the eye movement of the eyeball 30 using a drive signal from the processing section 100. Furthermore, by controlling the light emitting section according to the rotational movement of the eyeball 30, it is possible to improve the efficiency of light use and shorten the estimation time.

However, it is not necessarily necessary to change the light emitting part of the VCSEL 1 according to the rotational movement of the eyeball. For example, the pupil position detection device 10 causes the light emitting part of the VCSEL 1 to raster scan (sequentially emit light) at predetermined time intervals independently of eye movement, and determines the coarse movement position of the eyeball 30 based on the detection signal of the PSD 3 in that case. It may also be possible to detect.

In addition, in FIG. 2, in order to simplify the explanation, only the laser light emitted from two light emitting parts is illustrated, but more light emitting parts of the VCSEL 1 can be used according to the rotation of the eyeball 30. In this case, it is preferable to optimize the number and position of the light emitting parts of the VCSEL 1 according to the size of the light receiving surface of the PSD 3 and the size of the eyeball 30 so that the position of the pupil 31 can be detected appropriately.

<Conditions for off-axis optical system>
Next, conditions to be satisfied by the off-axis optical system including the VCSEL 1, concave mirror 2, and PSD 3 will be described.

In this embodiment, a concave mirror is used as a condition for the laser beam emitted from the VCSEL 1 to enter the light receiving surface of the PSD 3, and as a condition for the focused laser beam L1 to be converted into parallel light after being reflected by the cornea 32. The diameter of the effective area (area that can reflect laser light; effective diameter) of No. 2 is determined.

FIG. 3 is a diagram explaining the conditions that an off-axis optical system should satisfy, where (a) is a diagram explaining the distance between elements, and (b) is a diagram explaining the geometric distance relationship expressed in a coaxial optical system. It is a diagram.

As shown in FIG. 3A, the distance from the VCSEL 1 to the concave mirror 2 is d0, the distance from the concave mirror 2 to the cornea 32 is d1, and the distance from the cornea 32 to the PSD 3 is d2. Further, focusing on the curvature and effective area of the concave mirror 2, for simplicity, a coaxial optical system in which the VCSEL 1, the concave mirror 2, and the PSD 3 are coaxially arranged is assumed.

FIG. 3(b) shows that the diverging laser beam from the VCSEL 1 enters the concave mirror 2, the laser beam reflected by the concave mirror 2 enters the cornea 32 while converging, and then the laser beam reflected by the cornea 32 The figure shows how the light enters the PSD3. A position 41 indicates the position of the light emitting part of the VCSEL 1, a position 42 indicates the position of the surface of the cornea 32, and a position 43 indicates the position of the surface of the concave mirror 2.

The beam radius hPSD can be calculated using the following equation (1) derived by ray tracing using the ABCD matrix.

（１）式において、ｒｃは角膜３２の曲率半径、ｈＰＳＤはＰＳＤ３の受光面でのレーザ光のビームの半径、Ｄｍは凹面ミラー２の有効領域の直径、λはＶＣＳＥＬ１の波長、ｈＵＬはＰＳＤ３の受光面でのレーザ光の、設計者が決定するビームの半径の上限値である。また、中央の式の第２項で、凹面ミラー２で反射後のレーザ光の回折によるレーザ光の広がりの効果が重畳されている。

In equation (1), rc is the radius of curvature of the cornea 32, hPSD is the radius of the laser beam on the light receiving surface of the PSD 3, Dm is the diameter of the effective area of the concave mirror 2, λ is the wavelength of the VCSEL 1, and hUL is the radius of the PSD 3. This is the upper limit value of the radius of the laser beam on the light receiving surface, determined by the designer. Furthermore, in the second term of the central equation, the effect of the spread of the laser beam due to the diffraction of the laser beam after being reflected by the concave mirror 2 is superimposed.

Based on equation (1), the diameter Dm of the effective area of the concave mirror 2 can be determined from equation (2).

ここで、図４は、（２）式に基づき取得された、凹面ミラー２の有効領域の直径Ｄｍと、ＰＳＤ３の受光面でのレーザ光のビームの半径ｈＰＳＤとの関係の一例を示す図である。

Here, FIG. 4 is a diagram showing an example of the relationship between the diameter Dm of the effective area of the concave mirror 2 and the radius hPSD of the laser beam on the light receiving surface of the PSD 3, obtained based on equation (2). be.

In the relationships shown in FIG. 4, the upper limit of the radius hPSD of the laser beam on the light receiving surface of the PSD 3 is hUL = 200 um, the distance d1 from the concave mirror 2 to the cornea 32 is 24 mm, the radius of curvature rc of the cornea 32 is 8 mm, The wavelength λ of the laser light is 940 nm. Although these values are values assuming the glasses-type support body 20, arbitrary values may be set depending on the purpose and environment of use.

In FIG. 4, as the diameter Dm of the effective area of the concave mirror 2 becomes smaller, the radius hPSD of the beam on the light receiving surface of the PSD 3 rapidly expands due to diffraction. Furthermore, as the diameter Dm of the effective area of the concave mirror 2 increases, the radius hPSD of the beam on the light receiving surface of the PSD 3 gradually increases. As the beam radius hPSD increases, the position detection resolution of the laser beam by the PSD 3 decreases.

As shown in FIG. 4, the diameter Dm of the effective area of the concave mirror 2 has an appropriate range in order to minimize the radius hPSD of the beam on the light receiving surface of the PSD 3. The gray hatched area is an appropriate range, which is the range of the diameter Dm of the effective area of the concave mirror 2 that satisfies equation (2). Applying equation (2), the diameter Dm of the effective area of the concave mirror 2 is determined by 0.225 mm≦Dm≦2.574 mm. By satisfying this condition, the radius hPSD of the beam on the light receiving surface of the PSD 3 can be set to 200 μm or less, and the position detection resolution of the laser beam by the PSD 3 can be made appropriate.

If d0 = 24√3 (mm) as a condition for the laser beam to enter the eyeball 30 at an incident angle of 60°, then the laser beam emitted from the VCSEL 1 has a divergence angle of approximately 7.1° or less in full width. Although necessary, this divergence angle can be realized by controlling the aperture of the VCSEL 1.

<Configuration example of processing unit 100>
Next, the hardware configuration of the processing unit 100 according to the embodiment will be described. FIG. 5 is a block diagram illustrating an example of the hardware configuration of the processing unit 100.

The processing unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an SSD (Solid State Drive) 104, a light source drive circuit 105, and an A/D. It has an (Analog/Digital) conversion circuit 106 and an input/output I/F (Interface) 107. Each of them is interconnected by a system bus 108.

The CPU 101 reads programs and data from a storage device such as the ROM 102 and the SSD 104 onto the RAM 103 and executes processing, thereby controlling the entire processing unit 100 and realizing functions described below. Note that some or all of the functions of the CPU 101 may be realized by hardware such as an ASIC (application specific integrated circuit) or an FPGA (field-programmable gate array).

The ROM 102 is a nonvolatile semiconductor memory (storage device) that can retain programs and data even when the power is turned off. The ROM 102 stores programs and data such as a BIOS (Basic Input/Output System) and OS settings that are executed when the processing unit 100 is started. The RAM 103 is a volatile semiconductor memory (storage device) that temporarily holds programs and data.

The SSD 104 is a nonvolatile memory that stores programs for executing processing by the processing unit 100 and various data. Note that the SSD may be an HDD (Hard Disk Drive).

The light source drive circuit 105 is an electric circuit that is electrically connected to the VCSEL 1 and outputs a drive signal such as a drive voltage to the VCSEL 1 according to an input control signal. The light source drive circuit 105 can drive a plurality of light emitting parts included in the VCSEL 1 to emit light simultaneously or sequentially. Furthermore, by modulating the cycle of the drive voltage, it is possible to drive the light emission with different light emission cycles.

As the drive voltage, a voltage waveform of a rectangular wave, a sine wave, or a predetermined waveform can be used. The light source drive circuit 105 can modulate the cycle of the drive voltage signal by changing the cycle (frequency) of the voltage waveform.

The A/D conversion circuit 106 is an electric circuit that is electrically connected to the PSD 3 and outputs a digital voltage signal obtained by A/D converting the analog voltage signal output from the PSD 3.

The input/output I/F 107 is an interface for connecting to external devices such as a PC (Personal Computer) and video equipment.

Next, the functional configuration of the processing section 100 will be explained. FIG. 6 is a block diagram illustrating an example of the functional configuration of the processing unit 100. As shown in FIG. 6, the processing section 100 includes a light emission driving section 110, a detection signal input section 111, a calculation section 120, and a pupil position output section 130.

The light emitting drive unit 110 outputs a drive signal with a cycle T1 to the VCSEL1, and drives the light emitting unit included in the VCSEL1 to emit light with a cycle T1. The light emission driving section 110 can be realized by the light source driving circuit 105 or the like.

The detection signal input unit 111 is realized by the A/D conversion circuit 106 and the like, and outputs a digital voltage signal obtained by A/D converting the analog voltage signal input from the PSD 3 to the eye rotation angle estimation unit 121 included in the calculation unit 120. .

The calculation unit 120 includes an eye rotation angle estimation unit 121 and a pupil position acquisition unit 122, and executes calculation processing to acquire the pupil position of the eyeball 30 based on the input signal from the detection signal input unit 111.

The eyeball rotation angle estimation section 121 estimates the rotation angle of the eyeball 30 based on the input signal from the detection signal input section 111 and outputs the estimated rotation angle data to the pupil position acquisition section 122. The pupil position acquisition unit 122 executes a process of acquiring the position of the pupil 31 based on the estimated rotation angle of the eyeball 30. The acquired position data of the pupil 31 is output to an external device or the like via the pupil position output unit 130 realized by the input/output I/F 107 or the like.

<Processing by pupil position detection device 10>
Next, processing by the pupil position detection device 10 will be explained.

Here, in the pupil position detection device 10, as a preliminary preparation for pupil position detection, calculation formulas for the incident angle at which the laser beam irradiated onto the eyeball 30 by the VCSEL 1 enters the eyeball 30 and the rotation angle of the eyeball 30 are determined in advance. Therefore, these will be explained first.

The formula for calculating the rotation angle of the eyeball 30 is a linear function or a quadratic function. However, the formula is not limited to this, and the format of the formula is not limited as long as it can determine the rotation angle from the incident angle of the laser beam and the position on the light receiving surface of the PSD 3. As a simple approximation formula, this embodiment employs a calculation formula using a quadratic function.

A surface shape model of the eyeball 30 can be used to determine the angle at which the laser beam enters the eyeball 30. For example, a schematic model of the eye that has been known for a long time as a general eyeball surface shape model (see, for example, "Optical Mechanism of the Eye", Precision Instruments 27-11, 1961), etc. can be used.

On the other hand, the angle of incidence of the laser light on the eyeball 30 is determined in advance by ray tracing calculation or the like so that the position of incidence of the laser light on the PSD 3 is at the center of the light receiving surface.

In addition, the incident position of the laser beam on the light receiving surface of the PSD 3 should be theoretically analyzed based on the incident angle of the laser beam on the eyeball 30, the reflection position of the laser beam on the eyeball 30, and the inclination of the contact surface of the eyeball 30. I can do it. Then, from the solution of the theoretical analysis, it is possible to determine an inverse calculation formula (approximate formula) for estimating the rotation angle of the eyeball 30 by polynomial approximation.

The inverse calculation formula for estimating the incident angle of the laser beam on the eyeball 30 and the rotation angle of the eyeball 30 is stored in a memory such as the ROM 102 or the SSD 104 of the processing unit 100, and is used to change the light emitting unit by the light emission driving unit 110 or perform calculations. It is referred to in the pupil position acquisition processing performed by the unit 120.

Next, FIG. 7 is a flowchart showing an example of processing by the pupil position detection device 10.

First, in step S71, the light emission driving section 110 drives the VCSEL 1 to emit light at the light emission period T1.

Subsequently, in step S72, the detection signal input unit 111 inputs the detection signal of the PSD 3 and outputs it to the eyeball rotation angle estimation unit 121 included in the calculation unit 120.

Subsequently, in step S73, the eyeball rotation angle estimation unit 121 calculates the eyeball rotation angle by substituting the input signal from the detection signal input unit 111 into an inverse calculation formula for estimating the rotation angle. Then, the calculated eyeball rotation angle data is output to the pupil position acquisition unit 122.

Subsequently, in step S74, the pupil position acquisition unit 122 acquires the pupil position using the eyeball surface shape model based on the input eyeball rotation angle data. The acquired pupil position data is output to an external device via the pupil position output unit 130.

In this way, the processing unit 100 can acquire the position of the pupil 31 of the eyeball 30 based on the detection signal output by the PSD 3, and can output the acquired position data to an external device.

<Effects of the pupil position detection device 10>
The development of technology to detect pupil position (line of sight) has progressed, and it has become useful as an interface for controlling electronic devices using line of sight, image formation support in wearable video display devices such as head-mounted displays or near-eye displays, and line of sight for skilled engineers in factories, etc. It is expected to be applied to a variety of applications, including data collection and product attention analysis (logging). In particular, pupil position detection devices that function as an interface between electronic devices and people require real-time performance and a reduction in size and weight.

With conventional technology, the reflected image of the eyeball is acquired under a lighting environment, and the pupil position is detected by an image processing unit based on pattern matching, which requires a large image processing load.Also, real-time performance and detection resolution of the pupil position are insufficient. There was a trade-off relationship between the two. Furthermore, it was necessary to install an imaging device, a processor, a driving power source, etc., making it difficult to make the device smaller and lighter.

Furthermore, as a conventional technique, a technique has been disclosed in which the pupil position is detected at high speed by a non-imaging method that does not use an imaging system by detecting the temporal change in the reflected light intensity of a laser beam that is scanned at high speed on the eyeball surface. However, with this technique, the diameter of the laser beam expands on the light-receiving surface of the photodetector due to reflection from the eyeball or cornea, which has a large curvature, making it impossible to appropriately detect the pupil position.

In the embodiment, a VCSEL 1 that emits light, a concave mirror 2 that converts the light into focused light and returns the focused light toward an irradiated surface having a curvature, and a reflected light of the focused light by the irradiated surface. An off-axis optical system including a PSD 3 that receives the reflected light and detects the position of the reflected light is placed in front of the eye.

More specifically, before reaching the eyeball 30, the light propagates through the space in front of the eye adjacent to the eyeball 30, turning around at least once or more without being reflected or scattered by the eyeball 30, and then reaches the eyeball 30. . Further, the concave mirror 2 emits focused laser light toward the eyeball 30.

Thereby, the curvature of the eyeball 30 or the cornea 32 can be offset by the curvature of the focused laser beam, so that the laser light reflected by the eyeball 30 or the cornea 32 can be prevented from spreading.

In addition, the diameter (aperture) Dm of the effective area of the concave mirror 2 is controlled by adjusting the distance d0 (see Figure 3) from the VCSEL 1 to the concave mirror 2 and changing the diameter of the laser beam irradiation range on the concave mirror 2. It is possible to do so. By determining the diameter (aperture) Dm of the effective area of the concave mirror 2 so as to satisfy the condition of equation (2), the diameter Dm of the effective area of the concave mirror 2 can be increased, and the laser beam can be focused with a large aperture. Therefore, the diameter of the beam at the light receiving surface of the PSD 3 can be reduced.

In this way, by miniaturizing the diameter of the laser beam on the light receiving surface of the PSD 3, the position detection resolution of the PSD 3 and the detection accuracy of the pupil position can be ensured, and the pupil position can be detected appropriately. .

[First embodiment]
Next, the pupil position detection device 10a according to the first embodiment will be described.

In the pupil position detection device, when the laser light emitted from each of the plurality of light emitting parts and reflected by the eyeball reaches the light receiving position detecting means, only a portion of the laser light is received at the end of the light receiving position detecting means. Errors may occur in the detection results of the rotation angle of the eyeball and the pupil position due to the position being detected. Furthermore, since this error differs between adjacent light emitting units, the rotation angle of the eyeball and the pupil position may not be detected continuously and with high precision.

In this embodiment, the light receiving position detecting means detects reflected light originating from the first light emitting part of the plurality of light emitting parts by a predetermined distance from one end of the light receiving position detecting means toward the center of the light receiving position detecting means. When receiving light, the light receiving position is detected by the predetermined distance from the other end of the light receiving position detection means for reflected light originating from a second light emitting part different from the first light emitting part of the plurality of light emitting parts. Light is received at the center of the means.

In other words, when the reflected light originating from the light emitted from the first light emitting section is received at one end of the light receiving position detecting means, the light emitted from the second light emitting section is also reflected at the other end of the light receiving position detecting means. The reflected light beams are received overlappingly by a predetermined distance. This prevents only a portion of the laser beam from being received at the end of the light receiving position detection means, and enables highly accurate detection of the rotation angle and pupil position of the eyeball.

<Configuration example of pupil position detection device 10a>
FIG. 8 is a diagram illustrating an example of the configuration of the pupil position detection device 10a. The X direction shown in FIG. 8 indicates the horizontal direction, the Y direction indicates the vertical direction, and the Z direction indicates the normal viewing direction in a state where the eyeball is not rotated. The Z direction is a direction perpendicular to both the X direction and the Y direction, and is a direction corresponding to the front of the person wearing the glasses-shaped support 20.

As shown in FIG. 8, the pupil position detection device 10a includes a VCSEL 1a. The VCSEL 1a is arranged on the +Z direction side of the PSD 3 and irradiates the concave mirror 2 with a laser beam L0. Like the VCSEL 1, the VCSEL 1a has a plurality of light emitting sections ch1 to ch8 (hereinafter referred to as light emitting sections ch if not distinguished. Also, illustrations are omitted in FIG. 8), and each light emitting section ch has a directivity. A laser beam L0 having a finite spread angle is emitted. However, as described below, the intervals between the light emitting parts channels in the plurality of light emitting parts channels are configured to be non-uniform.

The laser beam L0 is reflected by the concave mirror 2 and is irradiated toward the eyeball 30 as a focused laser beam L1. The laser beam L2 reflected by the eyeball 30 reaches the light receiving surface of the PSD 3. The PSD 3 detects the receiving position of the laser beam L2. Here, the laser beam L2 corresponds to "reflected light originating from the light emitted from the light emitting section."

Although the pupil position detection device 10a does not include the ball joint 4a, it can also be configured to include the ball joint 4a.

<Relationship between the rotation angle of the eyeball 30 and the light receiving position by the PSD 3>
Next, the relationship between the rotation angle of the eyeball 30 and the receiving position of the laser beam L2 by the PSD 3 will be described with reference to FIG. 9. Here, FIG. 9 is a diagram illustrating an example of the relationship between the rotation angle of the eyeball 30 and the light receiving position by the PSD 3, and (a) is a diagram showing a change in the light receiving position according to the rotation angle of the eyeball 30. b) is a diagram explaining the position in PSD3.

The horizontal axis in FIG. 9A indicates the rotation angle θx of the eyeball 30 in the horizontal direction (X direction in FIG. 8), and the vertical axis indicates the light receiving position z in the Z direction by the PSD 3. Further, graphs G1 to G8 are plots of simulation results of light receiving positions by the PSD 3 of reflected light originating from the laser light L0 emitted by the eight light emitting units ch1 to ch8 in the VCSEL 1a.

The light emitting parts ch1 to ch8 are light emitting parts arranged in the Z direction within the VCSEL 1, and the relative positions with respect to the eyeball 30 are different for each of the light emitting parts ch1 to ch8.

Graph G1 in FIG. 9(a) is for light emitting part ch1, graph G2 is for light emitting part ch2, graph G3 is for light emitting part ch3, graph G4 is for light emitting part ch4, graph G5 is for light emitting part ch5, and graph G6 is for light emitting part ch5. The graph G7 corresponds to the light emitting part ch6, the graph G8 corresponds to the light emitting part ch8, and the graph G8 corresponds to the light emitting part ch8.

Further, areas A1 to A8 represent light receiving areas of the laser beam L2 in the PSD 3 corresponding to the light emitting sections ch1 to ch8. In FIG. 9(a), each of the areas A1 to A8 is represented by a rectangle with a broken line and L-shaped figures arranged at the four corners. Note that the length along the horizontal axis of the graph in areas A1 to A8 is a length corresponding to the rotation angle θx of the eyeball 30.

In FIG. 9(a), area A1 is for light emitting part ch1, area A2 is for light emitting part ch2, area A3 is for light emitting part ch3, area A4 is for light emitting part ch4, area A5 is for light emitting part ch5, and area A6 is for light emitting part ch5. The area A7 corresponds to the light emitting part ch6, the area A7 corresponds to the light emitting part ch8, and the area A8 corresponds to the light emitting part ch8.

Furthermore, the end positions C1 to C8 in FIG. 9(a) correspond to the rotation angle θx of the eyeball 30 when the light emitted from the light emitting parts ch1 to ch8 lands on the end position (z=-2 mm) of the PSD 3. ing.

Note that the length of the light receiving area of the PSD 3 in the Z direction is ±2 mm. Furthermore, in FIG. 9A, the simulation is performed by limiting the rotation of the eyeball 30 to a one-dimensional horizontal direction.

As shown in FIG. 9A, the manner in which the light receiving position changes in the PSD 3 according to the rotation angle θx of the eyeball 30 is different between the minus side and the plus side of the rotation angle θx of the eyeball 30. Furthermore, the horizontal lengths of the areas A1 to A8 are also different. Further, as shown in the graphs G1 to G8, the state of change in the light receiving position in the PSD 3 depending on the rotation angle θx of the eyeball 30 is different for each of the light emitting units ch1 to ch8.

On the other hand, FIG. 9(b) shows the light receiving surface 3a of the PSD 3. The light receiving surface 3a is a plane along the YZ plane. When the eyeball 30 rotates in the horizontal direction, the position of the laser beam L2 changes in the Z direction.

In FIG. 9(b), the laser light _L26 is the laser light L2 derived from the laser light L0 emitted by the light emitting part ch6 of the light emitting parts ch1 to ch8. Further, the laser light _L27 is the laser light L2 derived from the laser light L0 emitted by the light emitting part ch7 of the light emitting parts ch1 to ch8.

In this embodiment, when the PSD 3 receives the laser beam _L26 at the center position 3c by a distance d from the end 3b of the light receiving surface 3a on the +Z direction side, the PSD 3 moves the end 3d of the light receiving surface 3a on the −Z direction side The arrangement of the light emitting unit ch is predetermined so that the laser beam _L27 is received closer to the center position 3c by a distance d.

In other words, when the PSD 3 receives the laser light L2 ₆ originating from the light emitting part ch6 at the end 3b of the PSD 3, the PSD 3 also receives the laser light L2 ₇ originating from the light emitting part ch7 by the distance d on the end 3d side. Duplicate light reception is possible. This distance d is preferably larger than the diameter of the laser beam L2. Further, the area where the PSD 3 receives light in duplicate is hereinafter referred to as an overlapping area.

FIG. 9 shows an example in which the distance d is set to a distance corresponding to 1 degree of the rotation angle θx of the eyeball 30. Overlapping regions B1 to B7 indicated by diagonal lines in FIG. 9(a) are overlapping regions corresponding to a rotation angle θx of 1 degree.

More specifically, the overlapping region B1 is an overlapping region between the laser light L2 originating from the light emitting section ch1 and the laser light L2 originating from the light emitting section ch2, and the overlapping region B2 is an overlapping region between the laser light L2 originating from the light emitting section ch2 and the emitted light. The overlapping region B3 is an overlapping region between the laser beam L2 originating from the light emitting section ch3 and the laser light L2 originating from the light emitting section ch4. Similarly, the overlapping regions B4 to B7 are overlapping regions between the laser beams L2 originating from the light emitting sections ch4 to ch7 and the laser beams L2 originating from the light emitting sections ch5 to ch8.

Here, the light emitting section ch6 is an example of a "first light emitting section", and the light emitting section ch7 is an example of a "second light emitting section". However, the "first light emitting section" may be any of the light emitting sections ch1 to ch8, and the "second light emitting section" may be any of the light emitting sections ch1 to ch8. It is more preferable that the "first light emitting section" and the "second light emitting section" are adjacent to each other because the arrangement of the light emitting sections ch can be easily determined.

Further, the end 3b corresponds to "one end of the light receiving position detecting means", and the end 3d corresponds to "the other end of the light receiving position detecting means". The center position 3c side corresponds to "the center side of the light receiving position detection means".

<Example of arrangement of multiple light emitting parts in VCSEL 1a>
Next, when the PSD 3 receives the laser beam L2 originating from the first light emitting section at the center side of the PSD 3 by a distance d from the end 3b, the PSD 3 receives the laser light L2 originating from the second light emitting section from the end 3b. The arrangement of the light emitting parts ch1 to ch8 in the VCSEL 1a to receive light at the center side of the PSD 3 by a distance d from 3d will be explained.

FIG. 10 is a diagram illustrating an example of the arrangement of a plurality of light emitting sections channels in the VCSEL 1a. It is a figure showing the position of light emitting part ch.

Here, the anchor refers to a target for determining the position of the light emitting section ch of the VCSEL 1a. In FIG. 10, a predetermined rotation angle of the eyeball 30 is used as an anchor. Anchors θ _x,1 to θ _x,8 in FIG. 10(a) mean rotation angles of the eyeball 30 corresponding to the end positions C1 to C9 in FIG. 9(a).

"Position of light emitting part" in FIG. 10(a) indicates the position of the light emitting part of the VCSEL 1a for achieving the target corresponding to the anchor. This position is calculated by simulation, and corresponds to the distance from the center (center of gravity) of the VCSEL 1a.

As shown in FIG. 10(a), when the anchor θ _x,1 is -21.64 degrees, the light emitting part ch should be placed at the position ΔZ ₁ , and the anchor θ _x,2 is -18.61 degrees. In this case, the light emitting section ch may be placed at the position _ΔZ2 . Similarly, when the anchors θ _x,3 to θ _x,8 are −15.38 to +12.19 degrees, the light emitting parts ch may be arranged at positions ΔZ ₃ to ΔZ ₈ , respectively.

In this embodiment, the light emitting part ch1 is arranged at the position ΔZ ₁ , the light emitting part ch2 is arranged at the position ΔZ ₂ , the light emitting part ch3 is arranged at the position ΔZ ₃ , the light emitting part ch4 is arranged at the position ΔZ 4, and the light emitting part ch 4 is arranged at the position ΔZ ₄ . The light emitting part ch5 is arranged at _ΔZ5 . Further, a light emitting part ch6 is arranged at a position ΔZ ₆ , a light emitting part ch7 is arranged at a position ΔZ ₇ , and a light emitting part ch8 is arranged at a position ΔZ ₈ .

FIG. 10(b) shows light emitting parts ch1 to ch8 arranged in the VCSEL 1a so as to correspond to positions ΔZ ₁ to ΔZ ₈ . As shown in FIG. 10(b), the light emitting parts ch1 to ch8 are arranged such that the distance between adjacent light emitting parts ch is different for each adjacent light emitting part ch. In other words, the light emitting parts ch1 to ch8 are arranged at non-uniform intervals.

Here, a calculation method for determining the positions of the light emitting sections ch of the VCSEL 1a will be explained using the light emitting sections ch6 and ch7 as an example.

Based on the principle of ray tracing, it is assumed that the relationship between the light receiving position z of the laser beam L2 on the light receiving surface 3a of the PSD 3 and the position Δz of the light emitting part ch of the VCSEL 1a is determined in advance as Z=f(Δz; θx). The function f can be expressed mathematically based on the positional relationship among the VCSEL 1a, the concave mirror 2, the PSD 3, and the eyeball 30 (corneal part), and a model of the eyeball shape.

First, in order to find the reference light emitting part ch, numerically solve Δz6 and θx,6 that satisfy {f(Δz6;θx,6)=-2, f(Δz6;-θx,6)=2} do. That is, it is adjusted to a symmetrical angle such that θx,7=-θx,6.

Next, in the positive direction of the rotation angle θx of the eyeball 30, Δz7 and θx,8 that satisfy {f(Δz7; θx, 7-1°)=-2, f(Δz7; θx, 8)=2} are numerically determined. to solve the problem. In addition, in the negative direction of the rotation angle θx of the eyeball 30, Δz5 and θx,5 are numerically set so as to satisfy {f(Δz5; θx,5)=-2, f(Δz5;θx,6+1°)=2}. to solve the problem.

By sequentially repeating the above calculation for Δz1 to Δz4, Δz8, and θx,1 to θx,4, the position of the light emitting part ch of the VCSEL 1a can be calculated.

When the light emitting parts ch1 to ch8 are arranged as shown in FIG. 10(b), when the PSD 3 receives the laser beam L2 originating from the first light emitting part at the center side of the PSD 3 by a distance d from the end part 3b, The PSD 3 can receive the laser light L2 originating from the second light emitting section at the center of the PSD 3 by a distance d from the end 3d.

With this, when the laser light L2 originating from the first light emitting part is received at one end of the PSD 3, the laser light L2 originating from the second light emitting part can also be received at the other end of the PDS3, so that the laser light L2 is not lost. , the rotation angle θx of the eyeball 30 can be detected.

In the above example, the adjacent light emitting parts ch6 and ch7 were described as an example of the first light emitting part and the second light emitting part, but the invention is not limited to this, and the first light emitting part and the second light emitting part are adjacent to each other. It does not have to be a light emitting part.

<Example of correspondence to rotation of the eyeball 30 in two axis directions>
In the example described above, the case where the eyeball 30 rotates along the horizontal direction has been described, but the embodiment is also applicable to the case where the eyeball 30 rotates in two axial directions.

FIG. 11 is a diagram illustrating an example of the light receiving area of the PSD when the eyeball 30 rotates in two axial directions. FIG. 11 shows a light receiving area where the PSD 3 receives the laser beam L2 originating from each light emitting unit channel of the VCSEL 1a on the light receiving surface 3a with respect to the rotation of the eyeball 30 in the X and Y directions in FIG. In this case, the plurality of light emitting sections ch in the VCSEL 1a are two-dimensionally arranged within the ΔyΔz plane (see FIG. 10(b)). Here, the X direction in FIG. 8 corresponds to a "predetermined direction," and the Y direction in FIG. 8 corresponds to a "crossing direction."

Similarly to FIG. 9(a), a broken-line rectangle with L-shaped figures arranged at the four corners in FIG. 11 indicates area A. The length of region A along the horizontal axis in FIG. 11 is a length corresponding to the rotation angle of the eyeball 30 in the X direction. Further, the length of region A along the vertical axis in FIG. 11 is a length corresponding to the rotation angle of the eyeball 30 in the Y direction.

The overlapping area B indicated by diagonal lines indicates an overlapping area in the X direction corresponding to 1 degree of the rotation angle θx of the eyeball 30 and an overlapping area in the Y direction corresponding to 1 degree of the rotation angle θy of the eyeball 30. . When detecting the rotation angle of the eyeball 30 in the two-axis directions, the positions of the plurality of light emitting sections ch in the VCSEL 1a are determined in advance so that an overlapping region B is provided on all sides of the region A.

<Other examples of light receiving position adjusting means for laser beam L2>
In the example described above, when the PSD 3 receives the laser beam L2 originating from the first light emitting section at the center side of the PSD 3 by a distance d from the end 3b, the PSD 3 receives the laser light L2 originating from the second light emitting section from the end 3b. An example is shown in which the light emitting parts ch1 to ch8 in the VCSEL 1a are arranged at non-uniform intervals as a light receiving position adjusting means for receiving light at the center of the PSD 3 by a distance d from the part 3d. However, the light receiving position adjusting means is not limited to adjusting the arrangement of the light emitting sections ch1 to ch8.

FIG. 12 is a diagram illustrating another example of the light receiving position adjusting means for the laser beam L2, in which (a) is a cross-sectional view showing a configuration example when using the prism structure 15a, and (b) is a diffraction structure 15b. (c) is a cross-sectional view showing an example of the configuration when using a lens array 15c; (d) is a plan view showing an example of the configuration when using a two-dimensional array of lens arrays 15d. It is.

The prism structure 15a is an optical element provided with a plurality of minute prisms. In the prism structure 15a, a plurality of prisms are arranged in one-to-one correspondence with the light emitting sections channels of the VCSEL 1a. By making the slopes of the prisms different for each prism, the propagation direction of the laser beam 1 emitted from each light emitting section channel can be made different for each light emitting section channel.

As a result, when the light emitting sections channels in the VCSEL 1a are arranged at regular intervals, the function of the light receiving position adjusting means can be realized, and the same effect as adjusting the arrangement of the light emitting sections channels in the VCSEL 1a can be obtained.

The diffraction structure 15b is an optical element in which a fine periodic structure for diffracting the laser beam L1 is formed. By varying the period of the periodic structure in one-to-one correspondence with the light-emitting sections channels, the propagation direction of the laser beam 1 emitted from each light-emitting section channel can be made different for each light-emitting section channel.

As a result, when the light emitting sections channels in the VCSEL 1a are arranged at equal intervals, the function of the light receiving position adjusting means can be realized, and the same effect as adjusting the arrangement of the light emitting sections channels in the VCSEL 1a can be obtained.

The lens array 15c is an optical element provided with a plurality of microlenses. In the lens array 15c, a plurality of lenses are arranged in one-to-one correspondence with the light emitting sections channels of the VCSEL 1a. By varying the amount of eccentricity of the lens with respect to the light emitting section ch for each lens, the propagation direction of the laser beam 1 emitted from each light emitting section ch can be made different for each light emitting section ch.

As a result, when the light emitting sections channels in the VCSEL 1a are arranged at regular intervals, the function of the light receiving position adjusting means can be realized, and the same effect as adjusting the arrangement of the light emitting sections channels in the VCSEL 1a can be obtained.

The prism structure 15a, the diffraction structure 15b, and the lens array 15c all correspond to deflection means that deflects the light emitted from each of the plurality of light emitting sections ch.

Further, as shown in FIG. 12(d), the present invention can also be applied to a case where the light emitting parts channels of the VCSEL 1a are arranged two-dimensionally. By using the lens array 15d in which a plurality of microlenses are arranged in two dimensions, the propagation direction of the laser beam 1 emitted from each light emitting section channel can be made different in two dimensions for each light emitting section channel.

Similarly, by using a prism structure in which a plurality of minute prisms are arranged in two dimensions or a diffraction structure in which the period of the periodic structure is different in two dimensions, the laser beam 1 emitted from each light emitting section channel can be It is also possible to make the propagation direction different for each light emitting unit channel.

<Operations and effects of the pupil position detection device 10a>
As explained above, in this embodiment, when the PSD 3 receives the laser beam L2 derived from the light emitted from the first light emitting section at the center side of the PSD 3 by a distance d from the end 3b of the PSD 3, the PSD 3 The laser beam L2 originating from the light emitted from the two light emitting parts is received at the center of the PSD 3 by a distance d from the end 3d of the PSD 3.

As a result, when the laser beam L2 originating from the first light emitting section is received at one end of the PSD 3, the laser light L2 originating from the second light emitting section can also be received at the other end of the PDS 3, so that the laser light L2 is not lost. , the rotation angle θx of the eyeball 30 can be detected. This prevents only a portion of the laser beam L2 from being received at the end of the PSD 3, and the rotation angle and pupil position of the eyeball 30 having a curvature can be detected with high precision.

Further, in this embodiment, when the PSD 3 receives the laser light L2 originating from the first light emitting part at the center side of the PSD 3 by a distance d from the end 3b of the PSD 3, the laser light L2 originating from the second light emitting part is transmitted to the PSD 3. The function of a light receiving position adjusting means for receiving light at the center of the PSD 3 by a distance d from the end 3d is realized by arranging a plurality of light emitting parts channels in the VCSEL 1a at non-uniform intervals.

Since the VCSEL 1a is manufactured using a semiconductor process, the spacing between the light emitting parts channels can be easily adjusted. Therefore, the function of the light receiving position adjusting means can be easily realized. Further, it is more preferable to arrange the plurality of light emitting sections in the VCSEL 1a so that the intervals between adjacent light emitting sections are gradually different, since the intervals between the light emitting sections can be adjusted more easily.

Here, the term "the spacing between adjacent light emitting sections channels gradually differing" means that the spacing between adjacent light emitting sections channels gradually decreases, or the spacing between adjacent light emitting sections channels gradually changes. It means to be arranged so that it becomes larger. Specifically, a light emitting part ch1 and a light emitting part ch2 are arranged with an interval e1, an adjacent light emitting part ch2 and a light emitting part ch3 are arranged with an interval e2 slightly smaller than the interval e1, and an adjacent light emitting part ch3 This is a case where the light emitting parts ch4 are arranged at an interval e3 slightly smaller than the interval e2. Alternatively, the interval e2 may be slightly larger than the interval e1, and the interval e2 may be slightly larger than the interval e1.

Further, the light receiving position adjusting means described above is not limited to adjusting the arrangement of the light emitting sections ch1 to ch8 in the VCSEL 1a. The effect of the light receiving position adjusting means can also be obtained by a deflection means that deflects the light emitted from each of the plurality of light emitting sections ch. Examples of such light receiving position adjusting means include the prism structure 15a, the diffraction structure 15b, and the lens array 15c.

Further, a plurality of light emitting units channels are arranged two-dimensionally, and the PSD 3 directs the laser beam L2 originating from the first light emitting unit to the center side of the PSD 3 by a distance d from one end of the PSD 3 in the X direction, or to one end of the PSD 3 in the Y direction. When receiving light from one side of the center of the PSD 3 by a distance d, the laser beam L2 originating from the second light emitting part disposed away from the first light emitting part in the X direction is transferred to the other end of the PSD 3 in the X direction. The laser beam L2 originating from the third light emitting section, which is disposed at a distance d from the first light emitting section in the Y direction, is received at the center of the PSD 3 by a distance d from the other end of the PSD 3 in the Y direction. It is also possible to receive light at the center.

With this configuration, the rotation angle in the two-axis directions and the pupil position of the eyeball 30 having curvature can be detected accurately over a wide range.

Further, in this embodiment, an example of the pupil position detection device 10a that detects the rotation angle of the eyeball 30 and detects the pupil position of the eyeball 30 based on this rotation angle is shown, but the present invention is not limited to this.

The rotation angle detection device of a three-dimensional object according to the embodiment is, for example, a three-dimensional object that includes a rotating body that is rotatable about a rotation center and a curved surface body that has a center of curvature, and that detects the position of the rotation center and the curvature. Even for three-dimensional objects having different center positions, it is possible to accurately detect the rotation angle of the three-dimensional object over a wide range.

Hereinafter, a modification of the pupil position detection device according to the embodiment will be described.

(First modification)
The pupil position detection device according to this modification includes, in place of the concave mirror 2, a first reflective condensing element 200 having a liquid crystal part 202 filled with an anisotropic molecular material. Here, the anisotropic molecular material refers to a liquid crystal material and the like.

FIG. 13 is a diagram illustrating an example of the configuration of an off-axis optical system using the first reflective condensing element 200. As shown in FIG. 13, the first reflective condensing element 200 includes a support substrate 201, a liquid crystal section 202, and a quarter wavelength shift section 203. Here, the first reflective condensing element 200 is an example of a "focusing reflection means", and the liquid crystal section 202 is an example of an "encapsulating section".

The linearly polarized light emitted from the VCSEL 1 is converted into circularly polarized light by the quarter wavelength shift section 203 and enters the liquid crystal section 202 . The light reflected by the liquid crystal section 202 toward the eyeball 30 passes through the quarter wavelength shift section 203 in the opposite direction, is converted into linearly polarized light again, and enters the corneal surface of the eyeball 30 . Thereafter, the light reflected on the corneal surface enters the PSD 3.

Further, as shown in FIG. 14, the liquid crystal section 202 includes a support substrate 2021, an alignment film 2022, an alignment film 2023, and a transmission support substrate 2024 that transmits light.

The space inside the film formed by the alignment film 2022 and the alignment film 2023 contains liquid crystal molecules 2025. The liquid crystal molecules 2025 are spirally arranged in a direction perpendicular to the planes of the alignment films 2022 and 2023.

The alignment of liquid crystal molecules 2025 is spatially controlled by alignment films 2022 and 2023. Specifically, the inside of each of the alignment films 2022 and 2023 is divided into minute spatial regions, and each region is irradiated with UV light polarized in a specific direction to perform optical alignment. The alignment of liquid crystal molecules 2025 in each minute spatial region is controlled.

In other words, the liquid crystal molecules 2025 are oriented to form a three-dimensional quasi-periodic structure inside the liquid crystal section 202. Here, the quasi-periodic structure refers to a structure in which the structural period or its phase is spatially adjusted so as to exhibit light-gathering properties.

From the right to the left in FIG. 14, the light incident on the liquid crystal section 202 passes through the transparent support substrate 2024 and the alignment film 2023, is reflected by the action of the liquid crystal molecules 2025, and then passes through the alignment film 2023 and the transmission support substrate 2024. The light passes through in the opposite direction to the forward direction and is emitted from the liquid crystal section 202.

In the example of FIG. 14, by adjusting the alignment direction on the surface of the alignment film 2022 or 2023 corresponding to the starting position of the helical structure by the liquid crystal molecules 2025, the equiphase plane 2026 of the curve representing the helical structure is aligned with the incident direction of light. It is curved in a concave shape. Thereby, the liquid crystal molecules 2025 function as a lens, and the light reflected by the action of the liquid crystal molecules 2025 and traveling to the right in the figure can be focused. Since a known technique (for example, see Nature Photonics Vol. 10 (2016) p. 389) can be applied to the technique of making liquid crystal molecules function as an optical element such as a lens, a more detailed explanation will be omitted here. Note that in FIG. 13, 2027 indicated by a dashed-dotted line indicates light that enters the liquid crystal section 202, and 2028 indicated by a dashed-two dotted line indicates light reflected by the liquid crystal section 202 and condensed.

Next, the optical characteristics of the liquid crystal section 202 will be further explained with reference to FIG. 15. FIGS. 15A and 15B show a liquid crystal section 202 that focuses right-handed circularly polarized light. The liquid crystal section 202 has different reflection or transmission characteristics for right-handed polarized light and left-handed polarized light, depending on the rotation direction of the liquid crystal molecules 2025.

In FIG. 15A, light that has been converted into circularly polarized light by a quarter wavelength shifter 203 enters a liquid crystal section 202. In FIG. The light reflected by the liquid crystal section 202 is returned to linearly polarized light by passing through the quarter-wave plate again in the opposite direction, and is irradiated onto the eyeball 30. In order to reduce the penetration of laser light into the eyeball 30 as much as possible, the linearly polarized light is preferably S-polarized light having an electric field vibration plane in a direction perpendicular to the plane of the drawing.

On the other hand, FIG. 15(b) shows an example in which the light beam from the VCSEL 1 is randomly polarized light without polarization control. Of the randomly polarized light incident on the liquid crystal section 202, only the right-handed circularly polarized light is reflected by the support substrate 2021 and collected, passes through the quarter wavelength shift section 203, and is converted into linearly polarized light. On the other hand, the left-handed polarized light component passes through the support substrate 201 as it is and is not irradiated onto the corneal surface.

In the pupil position detection device according to this modification, the three-dimensional alignment distribution of the liquid crystal molecules 2025 can be controlled by two-dimensional alignment control of the alignment films 2022 and 2023, and as a result, the reflection and diffraction efficiency is high, and the thin The first reflective condensing element 200 can be provided. Further, it is possible to impart polarization selectivity to the first reflective condensing element 200, and it is possible to provide a pupil position detection device that reduces the number of optical components and ensures eye safety against laser light.

(Second modification)
The pupil position detection device according to this modification includes a second reflective condensing element 210 containing an anisotropic molecular material.

FIG. 16 is a diagram illustrating an example of the configuration of an off-axis optical system using the second reflective condensing element 210. As shown in FIG. 16, the second reflective condensing element 210 includes a liquid crystal section 211, a light guide means 212, and a quarter wavelength shift section 213. Here, the second reflective condensing element 210 is an example of a "focusing reflection means", and the liquid crystal section 211 is an example of an "anisotropic molecular material section".

The liquid crystal section 211 is provided so as to be in contact with the light guiding region interface of the light guiding means 212. Inside the liquid crystal section 211, like the liquid crystal section 202 described above, liquid crystal molecules are oriented to form a three-dimensional quasi-periodic structure inside the liquid crystal section 211.

The light emitted from the VCSEL 1 is coupled into the light guiding means 212 via the slope of the incident end of the light guiding means 212. Although it may be coupled into the light guiding means 212 via a grating, in consideration of the simplicity and accuracy of mounting, it is preferable to arrange the mounting board surface of the VCSEL 1 and the light guiding means 212 at right angles. .

The light coupled into the light guiding means 212 undergoes repeated total reflection at the interface of the light guiding means 212 and propagates inside the light guiding means 212 to the vicinity in front of the eyes. Of the light internally propagated through the light guiding means 212, right-handed circularly polarized light or left-handed circularly polarized light is selectively reflected by the liquid crystal section 211 and condensed by the lens function of the liquid crystal section 211, and the light is focused at 1/4 wavelength. After being converted into linearly polarized light (S-polarized light) by the shift unit 213, the corneal surface of the eyeball 30 is irradiated with the light.

Note that when using the light guiding means 212, it is difficult to irradiate the corneal surface with light at a shallow angle, so the light is reflected by the liquid crystal section 211 near the front of the eyeball 30. In this case, in order to make the light enter the PSD 3, it is necessary to condense the light at a position (specular reflection position) shifted toward the PSD 3 from the pupil center position on the cornea.

In the pupil position detection device according to this modification, the light emitted from the VCSEL 1 can be irradiated onto the corneal surface after securing the optical path length within the light guiding means 212, so that the device can be miniaturized. Further, the VCSEL 1, the light guiding means 212, the PSD 3, etc. can be configured integrally.

[Second embodiment]
Next, a retinal projection display device according to a second embodiment will be described with reference to FIG. 17.

FIG. 17 is a diagram illustrating an example of the configuration of a retinal projection display device according to this embodiment.

The retinal projection display device 60 includes an RGB (Red, Green, Blue) laser light source 61, a scanning mirror 62, a plane mirror 63, a half mirror 64, an image generation section 65, and a pupil position detection device 10a. There is.

The RGB laser light source 61 temporally modulates and outputs laser light of three colors of RGB. The scanning mirror 62 two-dimensionally scans the light from the RGB laser light source 61. The scanning mirror 62 is a MEMS mirror or the like. However, the present invention is not limited to this, and any mirror that has a reflecting part that scans light, such as a polygon mirror or a galvano mirror, may be used. MEMS mirrors are advantageous in terms of size and weight reduction. Note that the driving method of the MEMS mirror may be any of electrostatic, piezoelectric, electromagnetic, and the like.

The plane mirror 63 reflects the scanning light from the scanning mirror 62 toward the half mirror 64 . The half mirror 64 transmits a portion of the incident light and reflects a portion toward the eyeball 30 . The half mirror 64 has a concave curved shape, focuses the reflected light near the pupil 31 of the eyeball 30, and forms an image at the position of the retina 33. As a result, an image formed by the scanning light is projected onto the retina 33. Light 61a indicated by a broken line in the figure represents light that forms an image on the retina 33. Note that in the half mirror 64, the amount of reflected light and transmitted light does not necessarily have to be one to one.

The pupil position detection device 10a detects the position of the pupil 31 according to eye movement, and transmits a feedback signal of the position of the pupil 31 to the image generation unit 65.

The image generation unit 65 has a deflection angle control function of the scanning mirror 62 and a light emission control function of the RGB laser light source 61. The image generation unit 65 also receives a feedback signal of the position of the pupil 31 from the pupil position detection device 10a. The deflection angle of the scanning mirror 62 and the light emission of the RGB laser light source 61 are controlled according to the position of the pupil 31 detected by the pupil position detection device 10a, and the projection angle of the image or the image content is rewritten. Thereby, it is possible to form an image on the retina 33 that follows (eye tracking) the change in the position of the pupil 31 due to eyeball movement.

In the example described above, the retinal projection display device 60 is a head mounted display (HMD), which is a wearable terminal, but the present invention is not limited to this. The retinal projection display device 60 as a head-mounted display is not only attached directly to a person's head, but also indirectly attached to a person's head via a member such as a fixing part (head mounted display). (a wearable display device). Alternatively, a binocular retinal projection display device may be used, in which a pair of retinal projection display devices 60 are provided for left and right eyes.

[Comparative example]
Here, US2016/0166146 according to a comparative example and the pupil position detection device 10a according to the embodiment will be compared.

In the device according to the comparative example, a laser light source is used, the laser light is scanned by a MEMS mirror, and the incident angle of the light to the eyeball is changed. In contrast, in the embodiment, a VCSEL having a plurality of light emitting parts is used as a light source, and the incident angle of light to the eyeball is changed by changing the light emitting parts of the VCSEL. In the embodiment, the angle of incidence of light on the eyeball is changed in this way without using a movable part. Therefore, compared to a structure having a movable part, it is more resistant to vibrations, external shocks, etc.

In the device according to the comparative example, the reflected light intensity of the light irradiated to the cornea is detected by a photodetector, whereas in the embodiment, a PSD is used to detect the position of the light reflected by the eyeball and incident on the light receiving surface of the PSD. Detect. PSD detects the position of the incident light without depending on the light intensity, so even if there is a difference in the amount of reflected light due to the position of light reflection on the eyeball, etc., the PSD can detect the position of the incident light without being affected by the difference in the amount of reflected light. Sensitive position detection is possible. As a result, the tilted position of the eyeball, such as the pupil, can be detected with high precision.

In the embodiment, a light emitting drive unit 110 is provided, and the light emitting drive unit 110 shifts the positions of the light emitting parts of the VCSEL and the light emission timing between the light emitting parts and lights them up individually. This allows coarse movements of the eyeballs to be captured so that reflected light from the eyeballs falls on the light-receiving surface of the PSD, and minute movements of the eyeballs can be captured by position detection using the PSD.

In the device according to the comparative example, the eyeball position is estimated from two peak intensities (reflection positions on the cornea at two points) on the time axis of the light reflected by the eyeball. In the embodiment, the eyeball position is estimated based on the reflection position of one point on the eyeball, such as the cornea. Therefore, the VCSEL and PSD do not necessarily have to be in symmetrical positions. In embodiments, the PSD may not be placed near the specular (specular) angle of the eye, but may be placed on the same side as the VCSEL.

Although examples of embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications may be made within the scope of the gist of the present invention as described in the claims. It is possible to transform and change.

Further, information on the pupil position detected by the pupil position detection device 10a can also be used for eye tracking in an input device of an electronic device. For example, the output of the pupil position detection device 10a shown in FIG. 1 may be used for eye tracking as input information to an electronic device. In other words, it is possible to configure an input device including the pupil position detection device 10a. This makes it possible to realize input to electronic equipment that is robust against head position deviations and the like.

It can also be used in optometric equipment that has the function of detecting the tilt of the eyeball and the position of the pupil (cornea). An optometry device refers to a device that can perform various tests such as a visual acuity test, an eye refractive power test, an intraocular pressure test, and an axial length test. An optometry device is a device that can perform eye examinations without contacting the eyeballs, and includes a support part that supports the subject's face, an optometry window, and a display that keeps the subject's eyeball direction (direction of line of sight) constant during the eye exam. It has a display section, a control section, and a measurement section. In order to improve the measurement accuracy of the measurement unit, the patient is required to stare at a single point without moving their eyes (line of sight), and the test subject fixes his or her face on the support and stares at the object displayed on the display through the optometry window. . At this time, when detecting the tilted position of the eyeball, the eyeball tilted position detection device of this embodiment can be used. The eyeball tilt position detection device is placed on the side of the measurement unit so as not to interfere with the measurement. The eyeball tilt position (line of sight) information obtained by the eyeball tilt position detection device can be fed back to the control unit, and measurements can be made in accordance with the eyeball tilt position information.

1a VCSEL (an example of light source means)
2 Concave mirror (an example of focusing reflection means)
3 PSD (an example of light receiving position detection means)
3a Light receiving surface 3b End (an example of one end)
3c Center position (an example of center)
3d End (an example of the other end)
10a Pupil position detection device (an example of a rotation angle detection device for a three-dimensional object)
15a Prism structure (an example of deflection means)
15b Diffraction structure (an example of deflection means)
15c Lens array (an example of deflection means)
20 Spectacle type support 21 Spectacle lens 22 Spectacle frame 30 Eyeball (an example of an irradiated surface, an example of a three-dimensional object)
31 Pupil 32 Cornea 33 Retina 60 Retinal projection display device 61 RGB laser light source 62 Scanning mirror 63 Plane mirror 64 Half mirror 65 Image generation unit 100 Processing unit 101 CPU
102 ROM
103 RAM
104 SSD
105 Light source drive circuit 106 A/D conversion circuit 107 Input/output I/F
110 Light emission drive unit 111 Detection signal input unit 120 Calculation unit 121 Eyeball rotation angle estimation unit 122 Pupil position acquisition unit 130 Pupil position output unit ch Light emission unit X direction Horizontal direction (an example of a predetermined direction)
Y direction Vertical direction (an example of cross direction)
Z direction Normal viewing direction θx, θy when the eyeball is not rotated Rotation angle d Distance (an example of a predetermined distance)

JP 2019-154815 Publication

Claims (13)

a light source means comprising a plurality of light emitting parts;
a focusing reflector that reflects and focuses the light emitted from the plurality of light emitting units toward an irradiated surface having a curvature of a three-dimensional object;
light receiving position detection means for receiving the reflected light reflected by the irradiated surface of the light and detecting the light receiving position of the reflected light,
The plurality of light emitting parts are arranged at non-uniform intervals,
The light receiving position detecting means detects the reflected light derived from the light emitted from the first light emitting part of the plurality of light emitting parts by a predetermined distance from one end of the light receiving position detecting means toward the center of the light receiving position detecting means. When receiving light, the reflected light originating from a second light emitting section different from the first light emitting section among the plurality of light emitting sections is transmitted at the predetermined distance from the other end of the light receiving position detecting means. A rotation angle detecting device for a three-dimensional object that receives light only at the center of the light receiving position detecting means. The rotation angle detection device for a three-dimensional object according to claim 1, wherein the first light emitting section and the second light emitting section are adjacent to each other. The rotation angle detection device for a three-dimensional object according to claim 1 , wherein the plurality of light emitting units are arranged such that intervals between adjacent light emitting units gradually differ. The rotation angle detection device for a three-dimensional object according to any one of claims 1 to 3 , further comprising deflection means for deflecting light emitted from each of the plurality of light emitting units. The plurality of light emitting parts are arranged two-dimensionally,
The light receiving position detection means includes:
The reflected light originating from the light emitted from the first light emitting section is directed toward the center of the light receiving position detecting means by the predetermined distance from one end of the light receiving position detecting means in a predetermined direction, or at an intersection that intersects with the predetermined direction. When receiving light on either side of the center of the light receiving position detecting means by the predetermined distance from one end of the light receiving position detecting means in the direction,
The reflected light derived from the light emitted from the second light emitting section, which is disposed away from the first light emitting section in the predetermined direction, is transmitted by the predetermined distance from the other end of the light receiving position detection means in the predetermined direction. 5. The rotation angle detection device for a three -dimensional object according to claim 1, wherein the light is received at the center of the light receiving position detection means. The reflected light derived from the light emitted from the third light emitting section disposed apart from the first light emitting section in the intersecting direction is transmitted by the predetermined distance from the other end of the light receiving position detecting means in the intersecting direction. 6. The rotation angle detecting device for a three-dimensional object according to claim 5 , wherein the light is received at the center of the light receiving position detecting means. 7. The rotation angle detection device for a three- dimensional object according to claim 1, wherein the light source means is a vertical cavity surface emitting laser. The three-dimensional object includes a rotating body rotatable around a rotation center and a curved body having a center of curvature,
The rotation angle detection device for a three-dimensional object according to any one of claims 1 to 7 , wherein the position of the center of rotation and the position of the center of curvature are different. The rotation angle detection device for a three-dimensional object according to claim 8 , wherein the three-dimensional object is an eyeball. A retinal projection display device comprising the rotation angle detection device for a three-dimensional object according to any one of claims 1 to 9 . A head-mounted display device comprising the rotation angle detection device for a three-dimensional object according to claim 1 . An optometry apparatus comprising the rotation angle detection device for a three- dimensional object according to claim 1 . An input device comprising the rotation angle detection device for a three-dimensional object according to any one of claims 1 to 9 .

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