Disappearance suppression device, disappearance suppression system, and disappearance suppression method

Abstract

Provided is a disappearance suppression device which, when a human views a retinal image formed on the retina of the human's eyeball by a display device worn on the eyeball, suppresses disappearance of the viewed image caused by adaptation of the visual function. The disappearance suppression device comprises a determination unit that determines whether or not there has been a change in the retinal image for a predetermined time or more, and a variation part that causes a variation in the retinal image when it has been determined that there has been no change in the retinal image for the predetermined time or more. The variation part may generate a variation in the retinal image corresponding to a fixational eye movement which is at least one of tremor, drift, and microsaccade.

Description

Disappearance prevention device, disappearance prevention system, and disappearance prevention method

[0001] The present invention relates to a disappearance prevention device, a disappearance prevention system, and a disappearance prevention method.

[0002] Patent Document 1 states that "by randomly setting the ω,n coefficients, such as by shifting the entire image or a part of the image displayed on the contact lens type display device 11 by n pixels at ω degrees, fixation of the fixational eye movement is reduced or eliminated" (0161). [Prior art documents] [Patent documents] [Patent document 1] JP 2016-002353 General disclosure

[0003] In a first aspect of the present invention, there is provided a disappearance prevention device for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball. The disappearance prevention device includes a determination unit that determines whether the retinal image has not changed for a predetermined time or more, and a variation unit that varies the retinal image when it is determined that the retinal image has not changed for the predetermined time or more.

[0004] The above-mentioned disappearance prevention device may further include a displacement detection unit that detects a displacement of the display device relative to the eyeball. In any of the above-mentioned disappearance prevention devices, the determination unit may determine whether or not there has been no change in the retinal image for the predetermined time or more based on the detection result of the displacement detection unit.

[0005] In any of the above-described disappearance prevention devices, the deviation detection unit may detect the magnitude of the deviation. In any of the above-described disappearance prevention devices, the determination unit may determine that there has been no change in the retinal image for the predetermined time or more when a deviation of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or more.

[0006] In any of the above-mentioned loss prevention devices, the judgment unit may determine whether the retinal image has not changed for more than the predetermined time based on the display image displayed on the display device to form the retinal image on the retina and the detection result of the deviation detection unit.

[0007] In any of the above-described disappearance prevention devices, the deviation detection unit may detect the magnitude of the deviation. In any of the above-described disappearance prevention devices, the determination unit may determine that the retinal image has not changed for the predetermined time or more when the deviation of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or more and when the displayed image has not changed for the predetermined time or more.

[0008] Any of the above disappearance prevention devices may include an eyelid opening / closing determination unit that determines whether an eyelid on the eyeball is open or closed. In any of the above disappearance prevention devices, the determination unit may determine whether the retinal image has not changed for more than the predetermined time based on a display image that is displayed on the display device to form the retina on the retina, the detection result of the misalignment detection unit, and the determination result of the eyelid opening / closing determination unit.

[0009] In any of the above-described disappearance prevention devices, the deviation detection unit may detect the magnitude of the deviation. In any of the above-described disappearance prevention devices, the determination unit may determine that the retinal image has not changed for the predetermined time or more if the deviation of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or more, if the displayed image has not changed for the predetermined time or more, and if it has been determined that the eyelids have not closed for the predetermined time or more.

[0010] Any of the above disappearance prevention devices may include an eyelid opening / closing determination unit that determines whether an eyelid on the eyeball is open or closed. In any of the above disappearance prevention devices, the determination unit may determine whether the retinal image has not changed for the predetermined time or more based on the detection result of the misalignment detection unit and the determination result of the eyelid opening / closing determination unit.

[0011] In any of the above-described disappearance prevention devices, the deviation detection unit may detect the magnitude of the deviation. In any of the above-described disappearance prevention devices, the determination unit may determine that there has been no change in the retinal image for the predetermined time or more when a deviation of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or more and when it has been determined that the eyelids have not been closed for the predetermined time or more.

[0012] In any of the above-mentioned loss prevention devices, the judgment unit may judge whether there has been no change in the retinal image for more than the predetermined time based on a display image displayed on the display device to form the retinal image on the retina.

[0013] In any of the above-described loss prevention devices, the determination unit may determine that there has been no change in the retinal image for more than the predetermined time when there has been no change in the display image for more than the predetermined time.

[0014] Any of the above disappearance prevention devices may include an eyelid opening / closing determination unit that determines whether an eyelid on the eyeball is open or closed. In any of the above disappearance prevention devices, the determination unit may determine whether the retinal image has not changed for the predetermined time or more based on a display image that is displayed on the display device to form the retina image on the retina and a determination result of the eyelid opening / closing determination unit.

[0015] In any of the above-mentioned disappearance prevention devices, the judgment unit may determine that there has been no change in the retinal image for more than the predetermined time if there has been no change in the displayed image for more than the predetermined time and if it is determined that the eyelids have not been closed for more than the predetermined time.

[0016] Any of the above disappearance prevention devices may include an eyelid opening / closing determination unit that determines whether an eyelid on the eyeball is open or closed. In any of the above disappearance prevention devices, the determination unit may determine whether the retinal image has not changed for the predetermined time or more based on a determination result of the eyelid opening / closing determination unit.

[0017] In any of the above-mentioned disappearance prevention devices, the judgment unit may determine that there has been no change in the retinal image for more than the predetermined time when it is determined that the eyelids have not been closed for more than the predetermined time.

[0018] In any of the above-described disappearance prevention devices, the variation section may vary the retinal image by mechanically varying the display device.

[0019] In any of the above-mentioned loss prevention devices, the variation unit may vary the retinal image by electronically varying the display image displayed on the display device to form the retinal image on the retina.

[0020] In any of the above-mentioned loss prevention devices, the variation unit may vary the retinal image by electronically flashing the display image displayed on the display device to form the retinal image on the retina.

[0021] In any of the above-described disappearance prevention devices, the variation unit may generate a variation in the retinal image corresponding to at least any one of fixational eye movements such as tremor, drift, and microsaccade.

[0022] In any of the above-described loss prevention devices, the deviation detection unit may detect the deviation by irradiating a boundary portion between the iris and the sclera of the eyeball with infrared light and detecting the amount of reflected light.

[0023] In any of the above-described disappearance prevention devices, the determination unit may determine whether the portion of the display image determined to have no change for the predetermined time or more is a first portion displayed in a central portion including the fovea centralis on the retina, or a second portion displayed in a peripheral portion around the central portion. In any of the above-described disappearance prevention devices, if the determination unit determines that the portion determined to have no change for the predetermined time or more is the first portion, the determination unit may cause the variation unit to vary the retinal image, thereby generating a displacement of the retinal image corresponding to at least one of tremor and drift instability. In any of the above-described disappearance prevention devices, if the determination unit determines that the portion determined to have no change for the predetermined time or more is the second portion, the determination unit may cause the variation unit to vary the retinal image, thereby generating a displacement of the retinal image corresponding to at least one of tremor and drift instability.

[0024] In a second aspect of the present invention, there is provided a disappearance prevention device for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball. The disappearance prevention device includes an output unit that outputs a signal for varying the retinal image at predetermined time intervals, and a variation unit that varies the retinal image by mechanically varying the display device when the signal is input.

[0025] A third aspect of the present invention provides a contact lens display, comprising any one of the disappearance prevention devices described above, the display device, and a contact lens incorporating the display device and the disappearance prevention device.

[0026] In the contact lens display described above, when the movement section mechanically moves the display device, the contact lens may hold the display device so as to absorb the movement of the display device.

[0027] In a fourth aspect of the present invention, there is provided a disappearance prevention device for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, The disappearance prevention device includes a determination unit that determines whether the retinal image has not changed for a predetermined time or more, and a communication unit that, when it is determined that the retinal image has not changed for the predetermined time or more, transmits to an external portable information device an instruction signal to vary the retinal image by electronically varying or blinking a display image to be displayed on the display device in order to form the retinal image on the retina.

[0028] In a fifth aspect of the present invention, there is provided a disappearance prevention device for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising at least a displacement detection unit that detects a displacement of the display device with respect to the eyeball or an eyelid opening / closing determination unit that detects the opening / closing of an eyelid on the eyeball, and a communication unit that transmits the detection result of the displacement detection unit or the determination result of the eyelid opening / closing determination unit to an external portable information device, and receives from the portable information device an instruction signal for varying the retinal image or an image signal that has been processed to vary the retinal image by displaying an electronically varying or flashing display image on the display device to vary the retinal image in response to the portable information device determining, based on the detection result or the determination result, that there has been no change in the retinal image for a predetermined period of time or more.

[0029] In a sixth aspect of the present invention, there is provided a disappearance prevention device for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball. The disappearance prevention device includes a determination unit that determines whether the retinal image has not changed for a predetermined time or more based on at least a displacement of the display device relative to the eyeball or the opening and closing of an eyelid on the eyeball, and a communication unit that transmits the determination result of the determination unit to an external portable information device and, in response to the transmission of the determination result, receives from the portable information device an instruction signal for varying the retinal image or an image signal that has been processed to vary the retinal image by displaying an electronically varying or flashing display image on the display device.

[0030] In a seventh aspect of the present invention, there is provided a disappearance prevention device for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball. The disappearance prevention device includes a communication unit that receives an instruction signal from an external portable information device to vary the retinal image when the external portable information device determines that the retinal image has not changed for a predetermined time or more, and a variation unit that varies the retinal image based on the instruction signal.

[0031] In an eighth aspect of the present invention, there is provided a contact lens display comprising any one of the above disappearance prevention devices, the display device, and a contact lens incorporating the display device and the disappearance prevention device.

[0032] In a ninth aspect of the present invention, there is provided a loss prevention system for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball. The loss prevention system includes a loss prevention device attached to the eyeball and a portable information device that communicates wirelessly with the loss prevention device, wherein at least one of the loss prevention device and the portable information device has a determination unit that determines whether the retinal image has not changed for a predetermined period of time or more, and the portable information device has a variation unit that varies the retinal image by electronically varying or blinking a display image displayed on the display device to form the retinal image on the retina when it is determined that the retinal image has not changed for the predetermined period of time or more.

[0033] In the above-mentioned loss prevention system, the loss prevention device may have a second variation unit that varies the retinal image by mechanically varying the display device when it is determined that there has been no change in the retinal image for more than the predetermined time.

[0034] In any of the above-described loss prevention systems, the loss prevention device may have a displacement detection unit that detects displacement of the display device relative to the eyeball. In any of the above-described loss prevention systems, the determination unit included in the loss prevention device may determine whether or not there has been no change in the retinal image for the predetermined time or more based on the detection result of the displacement detection unit.

[0035] In any of the above-described loss prevention systems, the loss prevention device may have an eyelid opening / closing determination unit that determines whether an eyelid on the eyeball is open or closed. In any of the above-described loss prevention systems, the determination unit included in the loss prevention device may determine whether the retinal image has not changed for the predetermined time or more based on a determination result of the eyelid opening / closing determination unit.

[0036] In any of the above loss prevention systems, the determination unit of the portable information device may determine, based on the displayed image, whether or not there has been any change in the retinal image for more than the predetermined time.

[0037] Any of the above-described loss prevention systems may further include the display device and a contact lens incorporating the display device and the loss prevention device.

[0038] In a tenth aspect of the present invention, there is provided a disappearance prevention method for preventing a visual image formed on the retina of a person's eyeball by a display device attached to the person's eyeball from disappearing due to adaptation of the visual function, the disappearance prevention method comprising: determining whether the retinal image has remained unchanged for a predetermined time or more; and varying the retinal image when it is determined that the retinal image has remained unchanged for the predetermined time or more.

[0039] In an eleventh aspect of the present invention, there is provided a method for preventing a visual image formed on a retina of a person's eyeball by a display device attached to the person's eyeball from disappearing due to adaptation of the visual function, the method comprising: outputting a signal for varying the retinal image at predetermined time intervals; and, when the signal is output, varying the retinal image by mechanically varying the display device.

[0040] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also be inventions.

[0041] 1 is a schematic diagram illustrating an overview of a contact lens display 11 according to a first embodiment when not attached to a human eyeball 1. FIG. 2 is a schematic diagram illustrating an overview of a contact lens display 11 according to the first embodiment when attached to a human eyeball 1. FIG. 3 is a schematic diagram illustrating fixational eye movement of the eyeball 1. FIG. 4 is a flowchart showing an example of an operation flow of a disappearance prevention method executed by the contact lens display 11 of the first embodiment, for preventing a visual image from disappearing due to adaptation of the visual function. FIG. 5 is a schematic diagram illustrating an overview of a contact lens display 12 according to a second embodiment. FIG. 6 is a schematic diagram illustrating an overview of a contact lens display 13 according to a third embodiment. FIG. 7 is a schematic diagram illustrating an overview of a contact lens display 14 and a disappearance prevention device 104 according to a fourth embodiment. FIG. 8 is a schematic diagram illustrating an overview of a contact lens display 15 according to a fifth embodiment. FIG. 9 is a schematic diagram illustrating an overview of a disappearance prevention system 51 according to a sixth embodiment. FIG. 10 is a schematic diagram illustrating an overview of a disappearance prevention system 52 according to a seventh embodiment. FIG. 11 is a schematic diagram illustrating an overview of a disappearance prevention system 53 according to an eighth embodiment. 13 is a schematic diagram for explaining an outline of a disappearance prevention system 54-1 according to a ninth embodiment, and a schematic diagram for explaining an outline of a disappearance prevention system 54-2 according to a tenth embodiment.

[0042] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0043] FIG. 1 is a schematic diagram illustrating an overview of a contact lens display 11 according to the first embodiment when not attached to a person's eyeball 1. FIG. 2 is a schematic diagram illustrating an overview of a contact lens display 11 according to the first embodiment when attached to a person's eyeball 1. The contact lens display 11 shown in FIG. 1 is attached to a person's eyeball 1 as shown in FIG. 2. The eyeball 1 may be the person's right eye or left eye. The contact lens display 11 may be attached to each of the person's left and right eyeballs 1, or may be attached to only one of the eyeballs 1. In FIG. 2, the eyeball 1 is indicated by a dashed line and everything other than the eyeball 1 is indicated by a solid line, and this also applies to the subsequent figures.

[0044] The contact lens display 11 communicates wirelessly with an external mobile information terminal 6 and forms a retinal image on the retina of the eyeball 1 based on an image signal received from the mobile information terminal 6. The contact lens display 11 according to the first embodiment comprises a contact lens 20, a display device 30, and a disappearance prevention device 101.

[0045] The contact lens 20 is a circular plate-like body having a transparent spherical shape, and has the same external shape as a normal contact lens. In this application, the term "transparent" refers to transparency at least in the visible light range, except for unavoidable absorption at specific wavelengths, unless otherwise specified.

[0046] The contact lens 20 is a soft contact lens or a scleral lens. The contact lens 20 houses the display device 30 and the disappearance prevention device 101. Therefore, the display device 30 and the disappearance prevention device 101 are not exposed to the outside and do not come into contact with the eyeball 1 of the person wearing the contact lens display 11. The contact lens 20 may have refractive power or may not have refractive power. As will be described in detail later, the disappearance prevention device 101 may mechanically fluctuate, for example, vibrate or displace, the display device 30. In this case, the contact lens 20 may hold the display device 30 so as to absorb the fluctuation of the display device 30. In this configuration, the contact lens display 11 can mitigate the impact that the fluctuation of the display device 30 caused by the disappearance prevention device 101 may have on the eyeball 1.

[0047] When the contact lens display 11 is attached to the eyeball 1, the display device 30 is located at a portion of the cornea 5 of the eyeball 1 facing the pupil 2. The display device 30 projects the display image input from the disappearance prevention device 101 onto the retina of the eyeball 1, displaying a retinal image on the retina.

[0048] When the contact lens 20 is a soft contact lens, the display device 30 may be a pixel-by-pixel type (see, for example, the non-patent document "S. Lan, X. Zhang, M. Taghinejad, S. Rodrigues, Z.-T. Lee, Z. Liu, and W. Cai, "Metasurfaces for Near-Eye Augmented Reality," ACS Photonics, vol. 6, no. 4, 864-870 (2019)") or a holographic type (see, for example, the non-patent document "J. Sano and Y. Takaki, "Holographic Contact Lens Display That Provides Focusable Images for Eyes," Opt. Express, vol. 29, 10568-10579 (2021)" or the patent document "International Publication WO 2023 / 153129"). A1" and the patent document "Patent Publication No. 2024-073220").

[0049] When the contact lens 20 is a scleral lens, the display device 30 may be any of a pixel-by-pixel method, a holographic method, and a projector method (see, for example, the non-patent document "J. Sano, and Y. Takaki, "Holographic Contact Lens Display That Provides Focusable Images for Eyes," Opt. Express, vol.29, 10568-10579 (2021)" and the non-patent document "M. Wiemer, and R. Winoto, "Mojo Lens - AR Contact Lenses for Real People," 2021 IEEE Hot Chips 33 Symposium (HCS), Palo Alto, CA, USA, 2021, pp. 1-56").

[0050] In the pixel-by-pixel display device 30, a micro-optical element such as a micro Fresnel lens or metasurface is attached to each pixel of the display, and an image is projected onto the retina of the eyeball 1. In the holography display device 30, a spatial light modulator is illuminated with laser light from a laser backlight, and an image is projected onto the retina of the eyeball 1. In the projector display device 30, a projection lens is combined with the display, and an image is projected onto the retina of the eyeball 1.

[0051] As displays for the pixel-by-pixel method and the projector method, liquid crystal displays, organic EL displays, and micro LED displays can be used. In the holography method, liquid crystal elements can be used as spatial light modulators.

[0052] A scleral lens is a hard contact lens with a larger diameter than a soft contact lens, and is supported by the sclera 4 rather than the cornea 5 located on the external side of the pupil 2 and iris 3 of the eyeball 1. Because the scleral lens is thicker than a soft contact lens, it is applicable to a projector-type display device 30 that requires the display and projection lens to be spaced a predetermined distance in the depth direction, for example, a distance of several mm. Note that in the pixel-by-pixel method, such a distance is not necessary because a micro-optical element is directly attached to one surface of the display, and in the holography method, such a distance is not necessary because a spatial light modulator is directly placed on one surface of the laser backlight.

[0053] The disappearance prevention device 101 is a device that prevents a visual image formed on the retina of the eyeball 1 by a display device 30 attached to the person's eyeball 1 from disappearing due to visual adaptation. As will be described in detail later, disappearance of a visual image due to visual adaptation occurs when there is no change in the retinal image for a certain period of time or more. This certain period of time may be, for example, calculated experimentally or may be a known period of time. As will be described in detail later, the disappearance prevention device 101 determines whether or not there is a change in the retinal image based on a predetermined period of time corresponding to the certain period of time.

[0054] When a person's eyeball 1 gazes at a single point in the outside world, the retinal image on the retina attempts to remain still, but this movement is called fixational eye movement (see, for example, non-patent literature "RM Pritchard, "Stabilized Images on the Retina," Scientific American, vol. 204, 72-78 (1961)" and non-patent literature "S. Martinez-Conde, SL Macknik, DH Hubel, "The Role of Fixational Eye Movements in Visual Perception," Nature Reviews Neuroscience, vol.5, 229-240 (2004)"). This causes the retinal image of the single point to move on the retina, thereby changing the retinal image and preventing the disappearance of the visual image due to adaptation of the visual function.

[0055] FIG. 3 is a schematic diagram for explaining fixational eye movements of the eyeball 1. As shown in FIG. 3, fixational eye movements are classified into three types: tremor, drift, and microsaccade. Tremor is the smallest and most random vibration of the three types, with a vibration amplitude on the retina equivalent to that of approximately one photoreceptor cell, i.e., a cone, a displacement amplitude on the cornea 5 of approximately 1 μm, and a vibration frequency of approximately 90 Hz. Drift, as shown by the dashed-line frame in FIG. 3, is an overall displacement as the duration of tremor, with a displacement on the retina equivalent to that of approximately 10 cones, a displacement amplitude on the cornea 5 of approximately 10 μm, and a displacement time of approximately 100 ms. Microsaccade is the largest displacement of the three types, with a linear displacement, a displacement on the retina equivalent to that of 10 cones, a displacement amplitude on the cornea 5 of several tens of μm, and a displacement time of approximately 25 ms. Since the contact lens 20 is attached to the cornea 5 , the displacement on the cornea 5 can be considered to be substantially equal to the displacement on the contact lens 20 .

[0056] As described above, the display device 30 is contained within the contact lens 20, which is a soft contact lens or a scleral lens. When worn on the eyeball 1, soft contact lenses and scleral lenses adhere more firmly to the eyeball 1 than hard contact lenses. Therefore, when worn on the eyeball 1, the contact lens 20, which is a soft contact lens or a scleral lens, is less likely to slip off due to blinking or eyeball rotation.

[0057] Therefore, if the retinal image formed on the retina of the eyeball 1 by the display device 30 contained in the contact lens 20 is a still image and the eyelids of the eyeball 1 do not blink for a certain period of time or more, even if the eyeball 1 makes small eye movements, there is a high possibility that the retinal image formed on the retina will not change and the visual image will disappear. Note that even if the display device 30 is configured to incorporate a rotation angle sensor and change the image in accordance with the rotation of the eyeball 1, there is a high possibility that the visual image will disappear under the same conditions as above when the eyeball 1 gazes at a single point. Note that in AR display, in which the retinal image formed on the retina by the display device 30 is superimposed on the external scenery, it is necessary to further increase the adhesion between the eyeball 1 and the contact lens 20, which further increases the possibility that the visual image will disappear.

[0058] Therefore, the disappearance prevention device 101 prevents the disappearance of the visual image due to adaptation of the visual function by varying the retinal image when the retinal image formed on the retina of the eyeball 1 by the display device 30 attached to the person's eyeball 1 does not change for a predetermined period of time or more. The change in the retinal image described above can mean any of the following: a change in the retinal image on the retina due to fixational eye movement of the eyeball 1; a change in the retinal image on the retina due to the contact lens display 11 being displaced from a reference position on the eyeball 1; a change due to the retinal image being a moving image; and disappearance of the retinal image due to the closing of the eyelids on the eyeball 1 by blinking, etc. The disappearance prevention device 101 can also be defined as a device that artificially generates a change equivalent to the change in the retinal image caused by fixational eye movement when it is determined that none of these have occurred for a predetermined period of time.

[0059] The disappearance prevention device 101 according to the first embodiment includes a determination unit 110, a variation unit 120, a deviation detection unit 130, an eyelid opening / closing determination unit 140, and a communication unit 150. These components of the disappearance prevention device 101 are connected to each other by electrical wiring. In Fig. 1, the direction of signal flow between each component of the disappearance prevention device 101 is indicated by black arrows. This also applies to the subsequent figures, and redundant explanations will be omitted.

[0060] The determination unit 110 determines whether the retinal image formed on the retina of the eyeball 1 by the display device 30 has not changed for a predetermined period of time or more. As an example, the determination unit 110 of this embodiment determines whether the retinal image has not changed for a predetermined period of time or more based on the display image displayed on the display device 30 to form the retinal image on the retina, the detection result of the misalignment detection unit 130, and the determination result of the eyelid open / close determination unit 140. The determination unit 110 of this embodiment analyzes an image signal received from the mobile information terminal 6 via the communication unit 150, and determines whether the display image based on the image signal has not changed for a predetermined period of time or more. When the determination unit 110 of this embodiment determines that the retinal image has not changed for a predetermined period of time or more, it outputs an instruction signal to the variation unit 120 to vary the retinal image.

[0061] The variation unit 120 varies the retinal image when the determination unit 110 determines that there has been no change in the retinal image for a predetermined period of time or more. As an example, the variation unit 120 of this embodiment includes an actuator 121 and an image processing device 123. The variation unit 120 may vary the retinal image by mechanically varying the display device 30 using the actuator 121, or may vary the retinal image by electronically varying or blinking the display image displayed on the display device 30 using the image processing device 123. In the following description, mechanically varying the display device 30 may sometimes be simply referred to as "varying the display device 30."

[0062] The actuator 121 may include, for example, an electromagnetic actuator, a piezoelectric actuator, an electrostatic actuator, etc. The actuator 121 artificially generates a fluctuation equivalent to fixational eye movement in the display device 30 in accordance with an instruction signal input from the determination unit 110.

[0063] As described above, when the actuator 121 moves the display device 30, the display device 30 may be configured to move within the contact lens 20. In this case, the movement of the display device 30 may be absorbed by the contact lens 20 and not be transmitted to the outside of the contact lens 20.

[0064] The image processing device 123 inputs an image signal received from the portable information terminal 6 via the communication unit 150 to the display device 30, and causes a display image based on the image signal to be displayed on the display device 30. The image processing device 123 processes the image signal in accordance with an instruction signal input from the determination unit 110, and causes an electronically varying or blinking display image to be displayed on the display device 30. As will be described in detail in other embodiments below, the disappearance prevention device 101 may not be equipped with the image processing device 123, and in this case, the disappearance prevention device 101 may receive an image signal from the portable information terminal 6 and input it to the display device 30, or the display device 30 may receive the image signal directly using its own antenna.

[0065] The variation of the retinal image by the variation unit 120 may be a variation corresponding to a variation of the retinal image caused by fixational eye movement of the eyeball 1. The variation unit 120 may generate a variation of the retinal image corresponding to at least any one of fixational eye movement such as tremor, drift, and microsaccade. The variation of the retinal image by the variation unit 120 may refer to vibrating the retinal image on the retina like tremor and drift, or may refer to linearly displacing the retinal image on the retina like drift and microsaccade. The variation unit 120 varies the retinal image with a displacement width of 1 μm to several tens of μm, a displacement time of 10 ms to 100 ms, and a vibration frequency of about 90 Hz, for example.

[0066] The misalignment detection unit 130 detects misalignment of the display device 30 with respect to the eyeball 1. More specifically, the misalignment detection unit 130 may detect misalignment of the contact lens 20 with respect to a reference position on the eyeball 1, for example, with respect to the boundary between the iris 3 and the sclera 4 of the eyeball 1.

[0067] The misalignment detection unit 130 of the present embodiment includes, for example, a light source 131 and a photodetector 133. When the contact lens display 11 is properly attached to the eyeball 1, for example, when the contact lens 20 is attached so that the center of the contact lens 20 coincides with the center of the pupil 2, the light source 131 and the photodetector 133 are located at the boundary between the iris 3 and the sclera 4 of the eyeball 1. For example, the misalignment detection unit 130 of the present embodiment detects the misalignment by irradiating the boundary between the iris 3 and the sclera 4 of the eyeball 1 with infrared light using the light source 131 and detecting the amount of reflected light using the photodetector 133. The misalignment detection unit 130 may further detect the magnitude of the misalignment.

[0068] The eyelid open / close determination unit 140 determines whether the eyelid on the eyeball 1 is open or closed. When the contact lens display 11 is attached to the eyeball 1, the eyelid open / close determination unit 140 may be located, together with the display device 30, at a portion of the cornea 5 of the eyeball 1 facing the pupil 2. The eyelid open / close determination unit 140 determines whether the eyelid on the eyeball 1 is open or closed, and outputs the determination result to the determination unit 110.

[0069] The communication unit 150 communicates wirelessly with the portable information terminal 6 and receives an image signal from the portable information terminal 6. The communication unit 150 outputs the received image signal to the determination unit 110 and the image processing device 123. Note that, as will be described in detail in another embodiment below, the communication unit 150 may receive an arbitrary signal from the determination unit 110 and transmit the signal to an external device such as the portable information terminal 6.

[0070] The portable information terminal 6 may be carried by, for example, a person wearing the contact lens display 11 on the eyeball 1, and communicates wirelessly with the disappearance prevention device 101. The portable information terminal 6 may be, for example, a smartphone, a tablet terminal, a PC (personal computer), etc. The portable information terminal 6 transmits an image signal of a display image to be displayed on the display device 30 of the contact lens display 11 to the disappearance prevention device 101 via wireless communication.

[0071] As described above, the determination unit 110 of the disappearance prevention device 101 determines whether the retinal image formed on the retina of the eyeball 1 by the display device 30 has not changed for a predetermined period of time or more, and the variation unit 120 of the disappearance prevention device 101 varies the retinal image if it is determined that the retinal image has not changed for a predetermined period of time or more. As described above, if the retinal image on the retina is varying due to fixational eye movement, the visual image will not disappear due to adaptation of the visual function. Some reports state that it takes several seconds for the visual image to disappear, while other reports have experimentally confirmed that it takes approximately 80 ms or less (see, for example, non-patent document "S. Martinez-Conde, SL Macknik, DH Hubel, "The Role of Fixational Eye Movements in Visual Perception," Nature Reviews Neuroscience, vol. 5, 230 (2004)"). Therefore, the determination unit 110 of the disappearance prevention device 101 may, for example, determine whether the retinal image has not changed for 80 ms or more. That is, the predetermined time may be, for example, 80 ms.

[0072] As an example, the determination unit 110 may determine whether or not there has been no change in the retinal image for a predetermined time or longer based on the detection result of the deviation detection unit 130. As a more specific example, the determination unit 110 may determine that there has been no change in the retinal image for a predetermined time or longer when a deviation of 10 μm or more of the display device 30 from a predetermined position on the eyeball 1 has not been detected for a predetermined time or longer.

[0073] As described above, among the types of fixational eye movement, drift and microsaccades displace the retinal image on the retina, and of the drift and microsaccades, drift, which displaces the retinal image by a smaller amount, has a displacement width of approximately 10 μm. Therefore, as in this example, the determination unit 110 may use whether the magnitude of the displacement of the display device 30 detected by the displacement detection unit 130 is 10 μm or more as a criterion for determining whether or not there is a change in the retinal image.

[0074] In this example, the predetermined position on the eyeball 1 may be, for example, the reference position described above. The same applies to the other examples that follow. Note that in this example, the determination unit 110 does not use the determination result of the eyelid open / close determination unit 140 to determine whether or not there is a change in the retinal image, so the disappearance prevention device 101 does not need to include the eyelid open / close determination unit 140.

[0075] As another example, the determination unit 110 may determine whether there has been no change in the retinal image for a predetermined period of time or more based on the determination result of the eyelid open / close determination unit 140. As a more specific example, the determination unit 110 may determine that there has been no change in the retinal image for a predetermined period of time or more when it is determined that the eyelids are not closed for a predetermined period of time or more. Note that in this example, the determination unit 110 does not use the detection result of the misalignment detection unit 130 to determine whether there has been a change in the retinal image, and therefore the loss prevention device 101 does not need to be equipped with the misalignment detection unit 130.

[0076] As another example, the determination unit 110 may determine whether the retinal image has not changed for a predetermined time or more based on the display image displayed on the display device 30 to form a retinal image on the retina. As a more specific example, the determination unit 110 may determine that the retinal image has not changed for a predetermined time or more if the display image has not changed for a predetermined time or more. In this example, the determination unit 110 does not use the detection result of the misalignment detection unit 130 and the determination result of the eyelid opening / closing determination unit 140 to determine whether the retinal image has changed, so the disappearance prevention device 101 does not need to be equipped with the misalignment detection unit 130 and the eyelid opening / closing determination unit 140.

[0077] As another example, the determination unit 110 may determine whether the retinal image has not changed for a predetermined period of time or more based on the display image displayed on the display device 30 to form a retinal image on the retina and the detection result of the deviation detection unit 130. As a more specific example, the determination unit 110 may determine that the retinal image has not changed for a predetermined period of time or more if a deviation of 10 μm or more of the display device 30 from a predetermined position has not been detected for a predetermined period of time or more and if there has been no change in the display image for a predetermined period of time or more. Note that in this example, the determination unit 110 does not use the determination result of the eyelid opening / closing determination unit 140 to determine whether the retinal image has changed, so the disappearance prevention device 101 does not need to be equipped with the eyelid opening / closing determination unit 140.

[0078] As another example, the determination unit 110 may determine whether the retinal image has not changed for a predetermined period of time or more based on the display image displayed on the display device 30 to form a retinal image on the retina and the determination result of the eyelid opening / closing determination unit 140. As a more specific example, the determination unit 110 may determine that the retinal image has not changed for a predetermined period of time or more if the display image has not changed for a predetermined period of time or more and if it is determined that the eyelids are not closed for a predetermined period of time or more. Note that in this example, since the determination unit 110 does not use the detection result of the misalignment detection unit 130 to determine whether the retinal image has changed or not, the disappearance prevention device 101 does not need to be equipped with the misalignment detection unit 130.

[0079] As another example, the determination unit 110 may determine whether there has been no change in the retinal image for a predetermined time or longer based on the detection result of the misalignment detection unit 130 and the determination result of the eyelid open / close determination unit 140. As a more specific example, the determination unit 110 may determine that there has been no change in the retinal image for a predetermined time or longer when a misalignment of the display device 30 of 10 μm or more from a predetermined position has not been detected for a predetermined time or longer and when it has been determined that the eyelids have not been closed for a predetermined time or longer.

[0080] In this embodiment, the determination unit 110 determines whether or not there has been no change in the retinal image for a predetermined time or longer based on the display image displayed on the display device 30 to form a retinal image on the retina, the detection result of the deviation detection unit 130, and the determination result of the eyelid open / close determination unit 140. More specifically, the determination unit 110 determines that there has been no change in the retinal image for a predetermined time or longer if a deviation of 10 μm or more of the display device 30 from a predetermined position has not been detected for a predetermined time or longer, if there has been no change in the display image for a predetermined time or longer, and if it has been determined that the eyelids are not closed for a predetermined time or longer.

[0081] 4 is a flowchart showing an example of the operation flow of the disappearance prevention method for preventing the disappearance of a visual image due to visual adaptation, which is executed by the disappearance prevention device 101 of the contact lens display 11 of the first embodiment. As an example, the operation flow shown in FIG. 4 starts when the disappearance prevention device 101 establishes wireless communication with the mobile information terminal 6 and starts receiving an image signal from the mobile information terminal 6 while the contact lens display 11 is attached to the person's eyeball 1.

[0082] If the eyelid open / close determination unit 140 determines that the eyelids have not been closed for a predetermined time or longer (step S101: YES), the deviation detection unit 130 has not detected a specific deviation of the display device 30 for a predetermined time or longer (step S103: YES), and the display image displayed on the display device 30 has not changed for a predetermined time or longer (step S105: YES), the determination unit 110 determines that the retinal image has not changed for a predetermined time or longer, the variation unit 120 varies the retinal image (step S107), and the operation flow ends. The specific deviation may be a deviation of 10 μm or more from a predetermined position. For example, the determinations in steps S101 to S105 are all performed at the same time, but may also be performed at different times. The order of steps S101 to S105 shown in FIG. 3 is merely an example, and the determinations of steps S101 to S105 may be performed in any order; that is, steps S101 to S105 may be performed in any order.

[0083] In step S101, if the eyelid opening / closing determination unit 140 does not determine that the eyelids have not been closed for a predetermined period of time or longer (step S101: NO), that is, if the eyelid opening / closing determination unit 140 determines that the eyelids have been closed within that period of time, the determination unit 110 determines that there has been a change in the retinal image within that period of time, and repeats step S101.

[0084] In step S103, if the deviation detection unit 130 detects a specific deviation of the display device 30 within a predetermined time (step S103: NO), the judgment unit 110 determines that there has been a change in the retinal image within that time, and returns to step S101.

[0085] In step S105, if the determination unit 110 determines that a change has occurred in the display image within the predetermined time (step S105: NO), the determination unit 110 determines that a change has occurred in the retinal image within that time, and returns to step S101. The determination unit 110 may detect a temporal change in the display image by, for example, calculating the difference between the display image of the current frame and the display image of the previous frame.

[0086] With regard to step S101, the eyelid opening / closing determination unit 140 may, for example, have a light-emitting element and a light-receiving element for determining whether an eyelid on the eyeball 1 is open or closed. More specifically, the eyelid opening / closing determination unit 140 may emit light from the light-emitting element toward the outside world and receive light incident from the outside world with the light-receiving element. The eyelid opening / closing determination unit 140 may determine whether an eyelid on the eyeball 1 is open or closed based on a signal output from the light-receiving element. For example, in the eyelid opening / closing determination unit 140, the light-receiving element may be configured to respond to light in the emission wavelength band of the light-emitting element.

[0087] In this case, if the eyelid on the eyeball 1 is closed, the light emitted from the light-emitting element is reflected by the back side of the eyelid, and the reflected light is incident on the light-receiving element located near the light-emitting element and received by the light-receiving element. The eyelid open / close determination unit 140 may determine that the eyelid is closed when a signal is output from the light-receiving element that receives the light emitted from the light-emitting element in this manner.

[0088] On the other hand, if the eyelid on the eyeball 1 is open, the light emitted from the light-emitting element travels directly to the outside world. Therefore, the light emitted from the light-emitting element does not enter the light-receiving element. The eyelid open / close determination unit 140 may determine that the eyelid is open when the light emitted from the light-emitting element is not received and therefore no signal is output from the light-receiving element.

[0089] Alternatively, the eyelid opening / closing determination unit 140 may have only a light receiving element that outputs a signal in response to receiving external light entering from the outside world, in which case it may be determined that the eyelid is open when a signal is output from the light receiving element.

[0090] The eyelid opening / closing determination unit 140 may have a pressure sensor for determining whether the eyelid on the eyeball 1 is open or closed in addition to or instead of an optical element for determining whether the eyelid on the eyeball 1 is open or closed. For example, the eyelid opening / closing determination unit 140 may store, as a reference value, the pressure that the pressure sensor receives from the eyelid when the eyelid on the eyeball 1 is closed, and determine whether the eyelid is open or closed by comparing the output value from the pressure sensor with the reference value.

[0091] Regarding step S107, as described above, the variation unit 120 may vary the retinal image by varying the display device 30 using the actuator 121, or may vary the retinal image by electronically varying or blinking the display image displayed on the display device 30 by processing the image signal received from the mobile information terminal 6 using the image processing device 123 and inputting it to the display device 30.

[0092] For example, the image processing device 123 may electronically shift the display position of the displayed image by synchronizing the timing of image data read from the frame buffer storing image information with the timing of image display by the display device 30, thereby causing changes in the retinal image corresponding to fixational eye movements. For example, from the perspective of shifting the display position of the displayed image as quickly as possible, i.e., shifting the image, when reading the image from the frame buffer, skipping several of the first scan lines may be performed to move the image upward. For example, leaving several scan lines blank and then reading the first scan line may be performed to move the image downward. For example, skipping several of the first pixels when reading pixels on each scan line may be performed to move the image leftward. For example, leaving several pixels blank and then reading the first pixel may be performed to move the image rightward. The image processing device 123 may artificially generate fluctuations corresponding to the three types of fixational eye movements described above by changing the manner in which the displayed image vibrates or displaces.

[0093] For example, the image processing device 123 may flicker the display image at a frequency of 90 Hz or less to correspond to tremor, which has a vibration frequency of approximately 90 Hz, and may also flicker the display image at a frequency of 60 Hz or more so that flicker is not perceived, thereby fluctuating the retinal image.

[0094] 4 is repeated as long as the disappearance prevention device 101 continues to receive image signals from the mobile information terminal 6. Note that the person wearing the contact lens display 11 can operate the mobile information terminal 6 to terminate the transmission of image signals from the mobile information terminal 6 to the disappearance prevention device 101.

[0095] The disappearance prevention device 101 for the contact lens display 11 according to the first embodiment described above determines whether the retinal image formed on the retina of the eyeball 1 by the display device 30 attached to the person's eyeball 1 has not changed for a predetermined period of time or more, and fluctuates the retinal image if it is determined that the retinal image has not changed for the predetermined period of time or more. In this way, the disappearance prevention device 101 can prevent the visual image that is viewed by a person from disappearing due to adaptation of the visual function.

[0096] In the contact lens display 11 according to the first embodiment described above, the judgment unit 110 of the disappearance prevention device 101 may determine whether the portion of the displayed image that is determined to have not changed for a predetermined period of time or more is a first portion displayed in the central portion including the fovea centralis on the retina, or a second portion displayed in the peripheral portion around the central portion.

[0097] It is known that tremor and drift are involved in suppressing image loss when an image is displayed near the fovea of ​​the retina, and that microsaccades are involved in suppressing image loss when an image is displayed in the peripheral part of the retina.

[0098] Therefore, when the determination unit 110 determines that the portion determined to have not changed for a predetermined time or more is the first portion, the variation unit 120 may vary the retinal image to generate a displacement of the retinal image corresponding to at least one of the fixation eye movements, tremor and drift. The variation unit 120 may vary only the first portion of the display image using the image processing device 123, thereby generating the displacement only in the portion of the retinal image corresponding to the first portion.

[0099] On the other hand, when the determination unit 110 determines that the portion determined to have not changed for a predetermined time or more is the second portion, the determination unit 110 may cause the variation unit 120 to vary the retinal image, thereby generating a displacement of the retinal image corresponding to the fixation eye movement of the microsaccade. The variation unit 120 may cause the image processing device 123 to vary only the second portion of the display image, thereby generating the displacement only in the portion of the retinal image corresponding to the second portion.

[0100] 5 is a schematic diagram for explaining an overview of the contact lens display 12 according to the second embodiment. The disappearance prevention device 102 for the contact lens display 12 according to the second embodiment differs from the disappearance prevention device 101 for the contact lens display 11 according to the first embodiment in that the variation unit 120 does not have an image processing device 123, i.e., the variation unit 120 does not vary the display image using the image processing device 123. Since the other components of the disappearance prevention device 102 are similar to the corresponding components of the disappearance prevention device 101, the same reference numbers as those of the components of the disappearance prevention device 101 are used and redundant explanations will be omitted.

[0101] In the disappearance prevention device 102 of the second embodiment, the variation unit 120 varies the retinal image by varying the display device 30 using the actuator 121. The communication unit 150 communicates wirelessly with the mobile information terminal 6 and receives an image signal from the mobile information terminal 6. The communication unit 150 inputs the received image signal to the display device 30. The disappearance prevention device 102 of the second embodiment also has the same effect as the disappearance prevention device 101 of the first embodiment.

[0102] 6 is a schematic diagram for explaining an outline of the contact lens display 13 according to the third embodiment. The disappearance prevention device 103 of the contact lens display 12 according to the third embodiment differs from the disappearance prevention device 101 of the contact lens display 11 according to the first embodiment in that the movement unit 120 does not have an actuator 121. Other components of the disappearance prevention device 103 are similar to the corresponding components of the disappearance prevention device 101, so the same reference numerals as those of the respective components of the disappearance prevention device 101 are used and redundant explanations will be omitted.

[0103] In the disappearance prevention device 103 of the third embodiment, the variation unit 120 varies the retinal image by electronically varying or blinking the display image displayed on the display device 30 by the image processing device 123. The disappearance prevention device 103 of the third embodiment also has the same effect as the disappearance prevention device 101 of the first embodiment.

[0104] 7 is a schematic diagram for explaining an overview of the contact lens display 14 and disappearance prevention device 104 according to the fourth embodiment. The disappearance prevention device 104 according to the fourth embodiment differs from the disappearance prevention device 101 of the contact lens display 11 according to the first embodiment in that it exists separately from the contact lens display 14, i.e., the disappearance prevention device 104 is not included in the contact lens 40 of the contact lens display 14. Another difference is that the disappearance prevention device 104 does not include a misalignment detection unit 130 or an eyelid opening / closing determination unit 140, and the movement unit 120 of the disappearance prevention device 104 does not include an actuator 121 or an image processing device 123. Another difference is that the contact lens display 14 includes an antenna 41 and an actuator 43 in addition to the display device 30 as components included in the contact lens 40.

[0105] Other components of the disappearance prevention device 104 are similar to the corresponding components of the disappearance prevention device 101, so the same reference numerals as those of the components of the disappearance prevention device 101 are used and redundant explanations are omitted. Also, the antenna 41 and actuator 43 of the contact lens display 14 have the same functions as the communication unit 150 and actuator 121 of the disappearance prevention device 101, so redundant explanations are omitted.

[0106] The disappearance prevention device 104 of the fourth embodiment may be carried by, for example, a person wearing the contact lens display 14 on the eyeball 1 and wirelessly communicates with the contact lens display 14 and the mobile information terminal 6. The disappearance prevention device 104 may be, for example, a smartphone, a tablet terminal, a PC (personal computer), or the like. The disappearance prevention device 104 may be integrated with the mobile information terminal 6. In the disappearance prevention device 104, the determination unit 110 analyzes an image signal received from the mobile information terminal 6 via the communication unit 150 and determines whether the display image based on the image signal has not changed for a predetermined period of time or more. If the determination unit 110 of this embodiment determines that the retinal image has not changed for a predetermined period of time or more, it outputs an instruction signal to the variation unit 120 to vary the retinal image. The determination unit 110 may output the image signal to the variation unit 120 together with the instruction signal.

[0107] The variation unit 120 processes the image signal in accordance with the instruction signal input from the judgment unit 110 to display an electronically varied or flashing display image on the display device 30 and vary the retinal image, and may input the processed image signal to the display device 30 via the communication unit 150 of the disappearance prevention device 104 and the antenna 41 of the contact lens display 14.

[0108] The variation unit 120 may vary the retinal image by transmitting an instruction signal to vary the display device 30 to an actuator 43 provided in addition to the display device 30 of the contact lens 20 via the communication unit 150 of the disappearance prevention device 104 and the antenna 41 of the contact lens display 14. The disappearance prevention device 104 of the fourth embodiment also has the same effect as the disappearance prevention device 101 of the first embodiment.

[0109] 8 is a schematic diagram for explaining an overview of the contact lens display 15 according to the fifth embodiment. The disappearance prevention device 105 of the contact lens display 15 according to the fifth embodiment differs from the disappearance prevention device 101 of the contact lens display 11 according to the first embodiment in that it does not include the determination unit 110, the image processing device 123, the misalignment detection unit 130, and the eyelid opening / closing determination unit 140, but instead includes an output unit 160. The other components of the disappearance prevention device 105 are similar to the corresponding components of the disappearance prevention device 101, so the same reference numbers as those of the components of the disappearance prevention device 101 are used and redundant explanations will be omitted.

[0110] In the disappearance prevention device 105 of the fifth embodiment, the output unit 160 outputs a signal for varying the retinal image formed on the retina of the eyeball 1 by the display device 30 at predetermined time intervals. The time interval may be, for example, 80 ms, similar to the determination criterion in the determination unit 110 of the disappearance prevention device 101 of the first embodiment.

[0111] The communication unit 150 communicates wirelessly with the portable information terminal 6 and receives an image signal from the portable information terminal 6. The communication unit 150 inputs the received image signal to the display device 30. When the signal is input from the output unit 160, the variation unit 120 varies the retinal image by varying the display device 30 using the actuator 121. The disappearance prevention device 105 of the fifth embodiment also has the same effect as the disappearance prevention device 101 of the first embodiment.

[0112] 9 is a schematic diagram for explaining an overview of a disappearance prevention system 51 according to a sixth embodiment. The disappearance prevention system 51 includes a disappearance prevention device 106 and a portable information device 201. By cooperating the disappearance prevention device 106 and the portable information device 201, the disappearance prevention system 51 prevents the disappearance of a visual image due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball 1 by a display device 30 attached to the person's eyeball 1. The same applies to multiple disappearance prevention systems according to the following multiple embodiments, and redundant explanations will be omitted.

[0113] The disappearance prevention device 106 according to the sixth embodiment may be part of the configuration of the contact lens display 16, similar to the disappearance prevention device 101 according to the first embodiment. Specifically, the contact lens display 16 includes the disappearance prevention device 106, a display device 30, and a contact lens 20 incorporating the display device 30 and the disappearance prevention device 106.

[0114] The disappearance prevention device 106 for the contact lens display 16 according to the sixth embodiment differs from the disappearance prevention device 101 for the contact lens display 11 according to the first embodiment in that it does not include a variable unit 120, i.e., it does not include an actuator 121 or an image processing device 123. Other components of the disappearance prevention device 106 are similar to the corresponding components of the disappearance prevention device 101, so the same reference numbers as those of the components of the disappearance prevention device 101 are used and redundant explanations will be omitted.

[0115] In the disappearance prevention device 106 of the sixth embodiment, when the determination unit 110 determines that there has been no change in the retinal image for a predetermined period of time or more, it outputs to the communication unit 150 an instruction signal to cause the external portable information device 201 to vary the retinal image by electronically varying or blinking the display image to be displayed on the display device 30. In this embodiment, as in the first embodiment, the determination unit 110 determines whether there has been no change in the retinal image for a predetermined period of time or more based on the display image to be displayed on the display device 30 to form a retinal image on the retina, the detection result of the misalignment detection unit 130, and the determination result of the eyelid opening / closing determination unit 140.

[0116] Communication unit 150 communicates wirelessly with portable information device 201 and receives an image signal from portable information device 201. Communication unit 150 inputs the received image signal to determination unit 110 and display device 30. Communication unit 150 transmits the instruction signal input from determination unit 110 to portable information device 201.

[0117] The portable information device 201 may be carried by a person wearing the contact lens display 16 on the eyeball 1, for example, and communicates wirelessly with the loss prevention device 106. The portable information device 201 may be, for example, a smartphone, a tablet terminal, a PC (personal computer), etc. The portable information device 201 transmits an image signal of a display image to be displayed on the display device 30 of the contact lens display 16 to the loss prevention device 106 via wireless communication. The same applies to multiple portable information devices according to multiple embodiments below, and redundant explanations will be omitted.

[0118] Portable information device 201 according to this embodiment includes variation unit 220 and communication unit 250. When variation unit 220 receives the above-mentioned instruction signal from disappearance prevention device 106 via communication unit 250, it processes the image signal to display an electronically varying or blinking display image on display device 30 and vary the retinal image, and inputs the processed image signal to display device 30 via communication unit 250 of portable information device 201 and communication unit 150 of disappearance prevention device 106.

[0119] The specific method of processing the image signal by the variation unit 220 of the portable information device 201 may be the same as the processing method by the variation unit 120 of the disappearance prevention device 101 according to the first embodiment, and a duplicated description will be omitted. The disappearance prevention device 106 in the disappearance prevention system 51 of the sixth embodiment also achieves the same effect as the disappearance prevention device 101 of the first embodiment by cooperating with the portable information device 201.

[0120] In this embodiment, the determination unit 110 of the disappearance prevention device 106 may determine whether or not there has been any change in the retinal image for a predetermined period of time or longer based on at least one of the display image displayed on the display device 30 to form a retinal image on the retina, the detection result of the misalignment detection unit 130, and the determination result of the eyelid opening / closing determination unit 140. If the determination unit 110 does not make the determination based on the display image, the communication unit 150 may input the image signal received from the portable information device 201 to the display device 30 without inputting it to the determination unit 110. In this case, the disappearance prevention device 106 does not use the image signal, and therefore, as described above, the display device 30 may receive the image signal directly using its own antenna. As explained in the first embodiment, if the judgment unit 110 does not make the judgment based on the detection result of the deviation detection unit 130, the disappearance prevention device 106 does not need to be equipped with the deviation detection unit 130, and if the judgment is not made based on the judgment result of the eyelid opening / closing judgment unit 140, the disappearance prevention device 106 does not need to be equipped with the eyelid opening / closing judgment unit 140.

[0121] In the present embodiment, when the determination unit 110 of the loss prevention device 106 determines that there has been no change in the retinal image for a predetermined period of time or more, it transmits the above-mentioned instruction signal to the external portable information device 201 via the communication unit 150, and the variation unit 220 of the portable information device 201 processes the image signal as described above in accordance with the instruction signal. Alternatively, when the determination unit 110 of the loss prevention device 106 determines that there has been no change in the retinal image for a predetermined period of time or more, it may transmit the determination result to the external portable information device 201 via the communication unit 150, and the variation unit 220 of the portable information device 201 may process the image signal as described above based on the determination result or in response to receiving the determination result. In this case, the communication unit 150 of the loss prevention device 106 may receive the processed image signal from the portable information device 201 in response to transmitting the determination result.

[0122] FIG. 10 is a schematic diagram for explaining an overview of a disappearance prevention system 52 according to the seventh embodiment. The disappearance prevention system 52 according to the seventh embodiment includes a disappearance prevention device 107 and a portable information device 202. Like the disappearance prevention device 101 according to the first embodiment, the disappearance prevention device 107 according to the seventh embodiment may be part of the configuration of the contact lens display 17. The disappearance prevention device 107 for the contact lens display 17 according to the seventh embodiment differs from the disappearance prevention device 101 for the contact lens display 11 according to the first embodiment in that it does not include the determination unit 110, the misalignment detection unit 130, or the eyelid opening / closing determination unit 140. Other components of the disappearance prevention device 107 are similar to the corresponding components of the disappearance prevention device 101, and therefore the same reference numerals as those of the components of the disappearance prevention device 101 are used, and redundant description will be omitted.

[0123] In the disappearance prevention device 107 of the seventh embodiment, when the external portable information device 202 determines that the retinal image has not changed for a predetermined time or longer, the communication unit 150 receives an instruction signal for varying the retinal image from the portable information device 202. The communication unit 150 outputs the received instruction signal to the variation unit 120. As an example, the communication unit 150 outputs the received instruction signal to at least one of the actuator 121 and the image processing device 123 included in the variation unit 120.

[0124] In the disappearance prevention device 107 of the seventh embodiment, the variation unit 120 varies the retinal image based on the instruction signal. Similar to the variation unit 120 of the disappearance prevention device 101 of the first embodiment, the variation unit 120 of the disappearance prevention device 107 of the seventh embodiment has an actuator 121 and an image processing device 123. When the instruction signal is input from the external portable information device 202 via the communication unit 150, the variation unit 120 may vary the retinal image by varying the display device 30 with the actuator 121, or may vary the retinal image by electronically varying or blinking the display image displayed on the display device 30 with the image processing device 123.

[0125] The portable information device 202 according to the seventh embodiment includes a determination unit 210 and a communication unit 250. The determination unit 210 determines whether the retinal image has not changed for a predetermined period of time or longer based on the display image displayed on the display device 30 to form a retinal image on the retina. As a more specific example, the determination unit 210 analyzes the image signal and determines that the retinal image has not changed for a predetermined period of time or longer if the display image based on the image signal has not changed for a predetermined period of time or longer. If the determination unit 210 determines that the retinal image has not changed for a predetermined period of time or longer, it inputs an instruction signal for changing the retinal image to the change unit 120 of the loss prevention device 107 via the communication unit 250 of the portable information device 202 and the communication unit 150 of the loss prevention device 107. The loss prevention device 107 in the loss prevention system 52 according to the seventh embodiment also achieves the same effect as the loss prevention device 101 according to the first embodiment by cooperating with the portable information device 202.

[0126] 11 is a schematic diagram for explaining an outline of the disappearance prevention system 53 according to the eighth embodiment. The disappearance prevention system 53 according to the eighth embodiment roughly corresponds to a configuration obtained by combining the configuration of the disappearance prevention system 51 according to the sixth embodiment and the configuration of the disappearance prevention system 52 according to the seventh embodiment, and the same reference numerals are used for corresponding components, and duplicated explanations will be omitted.

[0127] The disappearance prevention system 53 according to the eighth embodiment includes a disappearance prevention device 108 and a portable information device 203. The disappearance prevention device 108 according to the eighth embodiment may be part of the configuration of the contact lens display 18, similar to the disappearance prevention device 101 according to the first embodiment.

[0128] The disappearance prevention device 108 for the contact lens display 18 according to the eighth embodiment differs from the disappearance prevention device 101 for the contact lens display 11 according to the first embodiment in that the variation unit 120 does not have an image processing device 123, i.e., the variation unit 120 does not vary the display image using the image processing device 123. Instead, the variation unit 220 of the portable information device 203 varies the display image. Furthermore, the determination unit 110 of the disappearance prevention device 108 determines whether there has been no change in the retinal image for a predetermined period of time or more, without basing it on the variation of the display image. In other words, the disappearance prevention device 108 does not analyze the image signal for this determination, nor does it process the image signal to vary or blink the display image to be displayed on the display device 30. The other components of the disappearance prevention device 108 are similar to the corresponding components of the disappearance prevention device 101, and therefore the same reference numerals as those of the components of the disappearance prevention device 101 are used, and redundant explanations will be omitted.

[0129] In the disappearance prevention system 53 according to the eighth embodiment, at least one of the disappearance prevention device 108 and the portable information device 203 has a determination unit that determines whether or not the retinal image has not changed for a predetermined period of time or more. In the example shown in FIG. 11 , the disappearance prevention device 108 has a determination unit 110, and the portable information device 203 also has a determination unit 210.

[0130] The determination unit 110 of the disappearance prevention device 108 determines whether or not there has been any change in the retinal image for a predetermined period of time or longer based on the detection result of the misalignment detection unit 130 and the determination result of the eyelid opening / closing determination unit 140. The determination unit 210 of the portable information device 203 analyzes the image signal described above and determines whether or not there has been any change in the display image based on the image signal for a predetermined period of time or longer.

[0131] In this embodiment, if portable information device 203 has determination unit 210 and disappearance prevention system 53 determines whether or not there has been a change in the retinal image for a predetermined period of time or more based solely on fluctuations in the displayed image, then portable information device 108 does not need to have determination unit 110, misalignment detection unit 130, or eyelid open / close determination unit 140. In this embodiment, if portable information device 108 has determination unit 110 and disappearance prevention system 53 determines whether or not there has been a change in the retinal image for a predetermined period of time or more without based on fluctuations in the displayed image, then portable information device 203 does not need to have determination unit 210.

[0132] In this embodiment, the portable information device 203 has a fluctuation unit 220, and the disappearance prevention device 108 also has an actuator 121 as the fluctuation unit 120, but the disappearance prevention device 108 does not have to have the actuator 121, that is, it does not have to have the fluctuation unit 120. Note that in this embodiment, the actuator 121 as the fluctuation unit 120 is an example of a second fluctuation unit. The disappearance prevention device 108 in the disappearance prevention system 53 of the eighth embodiment also has the same effect as the disappearance prevention device 101 of the first embodiment by working in cooperation with the portable information device 203.

[0133] 11 , when the determination unit 110 of the disappearance prevention device 108 determines that the retinal image has not changed for a predetermined time or longer, the determination unit 110 transmits the determination result to the external portable information device 203 via the communication unit 150, and the variation unit 220 of the portable information device 203 may generate an instruction signal for varying the retinal image based on the determination result or in response to receiving the determination result, or may process the image signal as described above. In this case, the communication unit 150 of the disappearance prevention device 108 may receive the instruction signal or the processed image signal from the portable information device 203 in response to transmitting the determination result. When the communication unit 150 of the disappearance prevention device 108 receives the instruction signal from the portable information device 203, the disappearance prevention device 108 may further include, in addition to or instead of the actuator 121, an image processing device 123 that processes the image signal to vary or blink the displayed image based on the instruction signal and inputs it to the display device 30.

[0134] As another example of a case in which the communication unit 150 of the disappearance prevention device 108 receives the instruction signal from the portable information device 203, the disappearance prevention device 108 may output the instruction signal to an actuator or image processing device provided in the contact lens display 18. In this case, the disappearance prevention device 108 may not include the actuator 121 and the image processing device 123, that is, may not include the variation unit 120. In this case, the disappearance prevention device 108 does not use an image signal, and therefore, as described above, the display device 30 may receive the image signal directly using its own antenna.

[0135] FIG. 12 is a schematic diagram for explaining an overview of a disappearance prevention system 54-1 according to the ninth embodiment. The disappearance prevention system 54-1 according to the ninth embodiment includes a disappearance prevention device 109-1 and a portable information device 203. Like the disappearance prevention device 101 according to the first embodiment, the disappearance prevention device 109-1 according to the ninth embodiment may be part of the configuration of the contact lens display 19-1. The disappearance prevention device 109-1 of the contact lens display 19-1 according to the ninth embodiment differs from the disappearance prevention device 101 of the contact lens display 11 according to the first embodiment in that it does not include a determination unit 110. Since the other components of the disappearance prevention device 109-1 are similar to the corresponding components of the disappearance prevention device 101, the same reference numbers as those of the components of the disappearance prevention device 101 are used, and redundant explanations will be omitted.

[0136] In the disappearance prevention device 109-1 of the ninth embodiment, the communication unit 150 transmits the detection result of the deviation detection unit 130 or the determination result of the eyelid opening / closing determination unit 140 to the external portable information device 203, and the determination unit 210 of the portable information device 203 determines whether or not the retinal image has not changed for a predetermined time or more based on at least one of the display image to be displayed on the display device 30 to form a retinal image on the retina, the detection result of the deviation detection unit 130, and the determination result of the eyelid opening / closing determination unit 140. When the determination unit 210 determines that the retinal image has not changed for a predetermined time or more, it outputs an instruction signal to the variation unit 220 to vary the retinal image.

[0137] In response to receiving the instruction signal, the variation unit 220 generates an instruction signal for causing the variation unit 120 of the disappearance prevention device 109-1 to vary the retinal image, and transmits the generated instruction signal to the disappearance prevention device 109-1 via the communication unit 250. The instruction signal generated by the variation unit 220 is an instruction signal for causing the image processing device 123 of the disappearance prevention device 109-1 to process an image signal so as to display an electronically varied or flashing display image on the display device 30, or an instruction signal for causing the actuator 121 of the disappearance prevention device 109-1 to vary the display device 30.

[0138] When portable information device 203 determines based on the above-described detection result or judgment result that the retinal image has not changed for a predetermined period of time or more, communication unit 150 of disappearance prevention device 109-1 receives an instruction signal for varying the retinal image from portable information device 203. Communication unit 150 inputs the instruction signal to variation unit 120.

[0139] As another example of a case in which the communication unit 150 of the disappearance prevention device 109-1 receives the instruction signal from the portable information device 203, the disappearance prevention device 109-1 may output the instruction signal to an actuator or image processing device provided in the contact lens display 19-1. In this case, the disappearance prevention device 109-1 does not need to include the actuator 121 and the image processing device 123, that is, it does not need to include the variable unit 120. The disappearance prevention device 109-1 in the disappearance prevention system 54-1 of the ninth embodiment also achieves the same effect as the disappearance prevention device 101 of the first embodiment by working in cooperation with the portable information device 203.

[0140] FIG. 13 is a schematic diagram for explaining an overview of a disappearance prevention system 54-2 according to the tenth embodiment. The disappearance prevention system 54-2 according to the tenth embodiment includes a disappearance prevention device 109-2 and a portable information device 203. Like the disappearance prevention device 101 according to the first embodiment, the disappearance prevention device 109-2 according to the tenth embodiment may be part of the configuration of the contact lens display 19-2. The disappearance prevention device 109-2 of the contact lens display 19-2 according to the tenth embodiment differs from the disappearance prevention device 101 of the contact lens display 11 according to the first embodiment in that it does not include the determination unit 110 and the variation unit 120, i.e., the actuator 121 and the image processing device 123. Other components of the disappearance prevention device 109-2 are similar to the corresponding components of the disappearance prevention device 101, and therefore the same reference numerals as those of the components of the disappearance prevention device 101 are used, and redundant description will be omitted.

[0141] In the disappearance prevention device 109-2 of the tenth embodiment, the communication unit 150 transmits the detection result of the deviation detection unit 130 or the determination result of the eyelid opening / closing determination unit 140 to the external portable information device 203, and the determination unit 210 of the portable information device 203 determines whether or not the retinal image has not changed for a predetermined time or more based on at least one of the display image to be displayed on the display device 30 to form a retinal image on the retina, the detection result of the deviation detection unit 130, and the determination result of the eyelid opening / closing determination unit 140. When the determination unit 210 determines that the retinal image has not changed for a predetermined time or more, it outputs an instruction signal to the variation unit 220 to vary the retinal image.

[0142] In response to receiving the instruction signal, the variation unit 220 processes the image signal as described above and transmits the processed image signal to the disappearance prevention device 109-2 via the communication unit 250. In this case, the communication unit 150 of the disappearance prevention device 109-2 receives the processed image signal from the portable information device 203 in response to the portable information device 203 determining, based on the detection result or judgment result described above, that there has been no change in the retinal image for a predetermined period of time or more. The communication unit 150 inputs the processed image signal to the display device 30. In this case, the disappearance prevention device 109-2 does not use an image signal, and as described above, the display device 30 may receive the image signal directly using its own antenna. The disappearance prevention device 109-2 in the disappearance prevention system 54-2 of the tenth embodiment also achieves the same effects as the disappearance prevention device 101 of the first embodiment by cooperating with the portable information device 203.

[0143] The contact lens displays described in the above embodiments may be capable of detecting information related to fixational eye movement. Since fixational eye movement can reflect a person's psychological state (see, for example, ZM Hafed, JJ Clark: "Microsaccades as an Overt Measure of Covert Attention Shifts", Vision Research, 42, 2533-2545 (2002)) the contact lens displays described in the above embodiments may be used to obtain information related to a person's mental state and emotions.

[0144] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0145] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically indicated as "before," "prior to," etc., and that any order may be used unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using terms such as "first," "next," etc. for convenience, this does not mean that the process must be performed in that order. [Other Possible Items] [Item 1] A disappearance prevention device that prevents a visual image formed on the retina of a person's eyeball by a display device attached to the person's eyeball from disappearing due to visual adaptation, the disappearance prevention device comprising: a determination unit that determines whether the retinal image has not changed for a predetermined period of time or more; and a variation unit that varies the retinal image when it is determined that the retinal image has not changed for the predetermined period of time or more. [Item 2] The disappearance prevention device according to item 1, further comprising a displacement detection unit that detects displacement of the display device relative to the eyeball, wherein the determination unit determines whether or not there has been no change in the retinal image for the predetermined time or longer based on a detection result from the displacement detection unit. [Item 3] The disappearance prevention device according to item 2, wherein the displacement detection unit detects a magnitude of the displacement, and the determination unit determines that there has been no change in the retinal image for the predetermined time or longer if a displacement of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or longer. [Item 4] The disappearance prevention device according to item 2, wherein the determination unit determines whether or not there has been no change in the retinal image for the predetermined time or longer based on a display image that is displayed on the display device to form the retinal image on the retina and on a detection result from the displacement detection unit. [Item 5] The disappearance prevention device according to Item 4, wherein the deviation detection unit detects the magnitude of the deviation, and the determination unit determines that there has been no change in the retinal image for the predetermined time or longer if a deviation of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or longer and if there has been no change in the displayed image for the predetermined time or longer.[Item 6] The disappearance prevention device according to Item 2, further comprising an eyelid open / close determination unit that determines whether an eyelid on the eyeball is open or closed, wherein the determination unit determines whether there has been no change in the retinal image for the predetermined time or longer based on a display image to be displayed on the display device to form the retinal image on the retina, the detection result of the deviation detection unit, and the determination result of the eyelid open / close determination unit. [Item 7] The disappearance prevention device according to Item 6, further comprising: an eyelid open / close determination unit that determines whether there has been no change in the retinal image for the predetermined time or longer based on a display image to be displayed on the display device to form the retinal image on the retina, the detection result of the deviation detection unit, and the determination result of the eyelid open / close determination unit. [Item 8] The disappearance prevention device according to Item 2, further comprising an eyelid open / close determination unit that determines whether an eyelid on the eyeball is open or closed, wherein the determination unit determines whether there has been no change in the retinal image for the predetermined time or longer based on the detection result of the deviation detection unit and the determination result of the eyelid open / close determination unit. [Item 9] The disappearance prevention device according to Item 8, wherein the deviation detection unit detects the magnitude of the deviation, and the determination unit determines that there has been no change in the retinal image for the predetermined time or longer if a deviation of 10 μm or more from a predetermined position on the eyeball has not been detected for the predetermined time or longer and if it is determined that the eyelid has not been closed for the predetermined time or longer. [Item 10] The disappearance prevention device according to Item 1, wherein the determination unit determines whether there has been no change in the retinal image for the predetermined time or longer based on a display image displayed on the display device to form the retinal image on the retina. [Item 11] The disappearance prevention device according to Item 10, wherein the determination unit determines that the retinal image has not changed for the predetermined time or longer when the display image has not changed for the predetermined time or longer.[Item 12] The disappearance prevention device according to item 10, further comprising an eyelid open / close determination unit that determines whether an eyelid on the eyeball is open or closed, wherein the determination unit determines whether there has been no change in the retinal image for the predetermined time or longer based on a display image that is displayed on the display device to form the retinal image on the retina and a determination result of the eyelid open / close determination unit. [Item 13] The disappearance prevention device according to item 12, further comprising an eyelid open / close determination unit that determines whether there has been no change in the retinal image for the predetermined time or longer based on a determination result of the eyelid open / close determination unit. [Item 15] The disappearance prevention device according to Item 14, wherein the determination unit determines that the retinal image has not changed for the predetermined time or more when it is determined that the eyelids have not closed for the predetermined time or more. [Item 16] The disappearance prevention device according to Item 1, wherein the variation unit varies the retinal image by mechanically varying the display device. [Item 17] The disappearance prevention device according to Item 1, wherein the variation unit varies the retinal image by electronically varying a display image displayed on the display device to form the retinal image on the retina. [Item 18] The disappearance prevention device according to Item 1, wherein the variation unit varies the retinal image by electronically blinking a display image displayed on the display device to form the retinal image on the retina. [Item 19] The disappearance prevention device according to Item 1, wherein the variation unit generates a variation in the retinal image corresponding to at least any one of tremor, drift, and microsaccade. [Item 20] The disappearance prevention device according to Item 2, wherein the deviation detection unit detects the deviation by irradiating a boundary portion between the iris and the sclera of the eyeball with infrared light and detecting the amount of light reflected therefrom.[Item 21] The determination unit determines whether the portion of the displayed image determined to have no change for the predetermined time or more is a first portion displayed in a central portion including the fovea centralis on the retina, or a second portion displayed in a peripheral portion around the central portion; if it determines that the portion determined to have no change for the predetermined time or more is the first portion, it causes the variation unit to vary the retinal image to generate a displacement of the retinal image corresponding to at least one of fixational eye movement of tremor and drift; and if it determines that the portion determined to have no change for the predetermined time or more is the second portion, it causes the variation unit to vary the retinal image to generate a displacement of the retinal image corresponding to fixational eye movement of a microsaccade. [Item 21] The disappearance prevention device described in Item 11. [Item 22] A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device worn on the person's eyeball, the disappearance prevention device comprising: an output unit that outputs a signal for varying the retinal image at predetermined time intervals, and a variation unit that varies the retinal image by mechanically varying the display device when the signal is input. [Item 23] A contact lens display comprising the disappearance prevention device according to any one of items 1 to 22, the display device, and a contact lens incorporating the display device and the disappearance prevention device. [Item 24] The contact lens display according to item 23, wherein when the variation unit mechanically varies the display device, the contact lens holds the display device so as to absorb the variation of the display device.[Item 25] A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising: a determination unit that determines whether the retinal image has not changed for a predetermined period of time or more; and a communication unit that, when it is determined that the retinal image has not changed for the predetermined period of time or more, transmits an instruction signal to an external portable information device to vary the retinal image by electronically varying or blinking the display image displayed on the display device in order to form the retinal image on the retina. [Item 26] A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising: a displacement detection unit that detects at least a displacement of the display device relative to the eyeball, or an eyelid opening / closing determination unit that detects the opening / closing of the eyelid on the eyeball; and a communication unit that transmits the detection result of the displacement detection unit or the determination result of the eyelid opening / closing determination unit to an external portable information device, and receives from the portable information device an instruction signal to vary the retinal image, or an image signal that has been processed to vary the retinal image by displaying an electronically varied or flashing display image on the display device to vary the retinal image, depending on whether the portable information device determines, based on the detection result or the determination result, that there has been no change in the retinal image for more than a predetermined time. [Item 27] ​​A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising: a judgment unit that judges whether there is no change in the retinal image for a predetermined period of time or more based on at least a displacement of the display device relative to the eyeball or the opening and closing of the eyelid on the eyeball; and a communication unit that transmits the judgment result of the judgment unit to an external portable information device and, in response to the transmission of the judgment result, receives from the portable information device an instruction signal for varying the retinal image, or an image signal that has been processed to vary the retinal image by displaying an electronically varying or flashing display image on the display device.[Item 28] A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising: a communication unit that receives an instruction signal from an external portable information device to vary the retinal image when the external portable information device determines that there has been no change in the retinal image for a predetermined period of time or more, and a variation unit that varies the retinal image based on the instruction signal. [Item 29] A contact lens display comprising: the disappearance prevention device according to any one of Items 25 to 28, the display device, and a contact lens incorporating the display device and the disappearance prevention device. [Item 30] A loss prevention system that prevents a visual image from disappearing due to adaptation of visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the system comprising: a loss prevention device attached to the eyeball; and a portable information device that wirelessly communicates with the loss prevention device, at least one of the loss prevention device and the portable information device having a determination unit that determines whether the retinal image has not changed for a predetermined period of time or more, and the portable information device having a variation unit that varies the retinal image by electronically varying or blinking an image displayed on the display device to form the retinal image on the retina, if it is determined that the retinal image has not changed for the predetermined period of time or more. [Item 31] The loss prevention system according to Item 30, wherein the loss prevention device has a second variation unit that varies the retinal image by mechanically varying the display device, if it is determined that the retinal image has not changed for the predetermined period of time or more. [Item 32] The disappearance prevention system according to Item 30, wherein the disappearance prevention device has a displacement detection unit that detects displacement of the display device relative to the eyeball, and the determination unit of the disappearance prevention device determines whether there has been any change in the retinal image for more than the predetermined time based on the detection result of the displacement detection unit.[Item 33] The disappearance prevention system according to item 30, wherein the disappearance prevention device has an eyelid open / close determination unit that determines whether an eyelid on the eyeball is open or closed, and the determination unit of the disappearance prevention device determines whether there has been no change in the retinal image for the predetermined time or longer based on a determination result of the eyelid open / close determination unit. [Item 34] The disappearance prevention system according to item 30, wherein the determination unit of the portable information device determines whether there has been no change in the retinal image for the predetermined time or longer based on the displayed image. [Item 35] The disappearance prevention system according to item 30, further comprising: the display device; and contact lenses incorporating the display device and the disappearance prevention device. [Item 36] A disappearance prevention method for preventing a visual image from disappearing due to visual adaptation when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention method comprising: determining whether the retinal image has not changed for a predetermined period of time or more; and varying the retinal image when it is determined that the retinal image has not changed for the predetermined period of time or more. [Item 37] A disappearance prevention method for preventing a visual image from disappearing due to visual adaptation when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention method comprising: outputting a signal for varying the retinal image at predetermined time intervals; and varying the retinal image by mechanically varying the display device when the signal is output.

[0146] REFERENCE SIGNS LIST 1 Eyeball 2 Pupil 3 Iris 4 Sclera 5 Cornea 6 Portable information terminal 11 Contact lens display 20 Contact lens 30 Display device 101 Disappearance prevention device 110 Determination unit 120 Variation unit 121 Actuator 123 Image processing device 130 Misalignment detection unit 131 Light source 133 Photodetector 140 Eyelid opening / closing determination unit 150 Communication unit 12 Contact lens display 102 Disappearance prevention device 13 Contact lens display 103 Disappearance prevention device 14 Contact lens display 40 Contact lens 41 Antenna 43 Actuator 104 Disappearance prevention device 15 Contact lens display 105 Disappearance prevention device 160 Output unit 51 Disappearance prevention system 16 Contact lens display 106 Disappearance prevention device 201 Portable information device 220 Variable unit 250 Communication unit 52 Disappearance prevention system 17 Contact lens display 107 Disappearance prevention device 202 Portable information device 210 Determination unit 53 Disappearance prevention system 18 Contact lens display 108 Disappearance prevention device 203 Portable information device 54-1 Disappearance prevention system 19-1 Contact lens display 109-1 Disappearance prevention device 54-2 Disappearance prevention system 19-2 Contact lens display 109-2 Disappearance prevention device

Claims

1. A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the eyeball, the disappearance prevention device comprising: a determination unit that determines whether the retinal image has not changed for more than a predetermined time; and a variation unit that varies the retinal image when it is determined that the retinal image has not changed for more than the predetermined time.

2. A disappearance prevention device as described in claim 1, further comprising a displacement detection unit that detects displacement of the display device relative to the eyeball, and the determination unit determines whether there has been any change in the retinal image for more than the predetermined time based on the detection result of the displacement detection unit.

3. The disappearance prevention device according to claim 2, wherein the judgment unit judges whether the retinal image has not changed for more than the predetermined time based on the display image displayed on the display device to form the retinal image on the retina and the detection result of the deviation detection unit.

4. A disappearance prevention device as described in claim 2, further comprising an eyelid opening / closing determination unit that determines whether the eyelid on the eyeball is open or closed, and the determination unit determines whether the retinal image has not changed for more than the predetermined time based on the display image displayed on the display device to form the retinal image on the retina, the detection result of the deviation detection unit, and the determination result of the eyelid opening / closing determination unit.

5. A disappearance prevention device as described in claim 2, further comprising an eyelid opening / closing determination unit that determines whether the eyelid on the eyeball is open or closed, and the determination unit determines whether there has been any change in the retinal image for more than the predetermined time based on the detection result of the deviation detection unit and the determination result of the eyelid opening / closing determination unit.

6. The disappearance prevention device according to claim 1, wherein the determination unit determines whether the retinal image has not changed for more than the predetermined time based on a display image displayed on the display device to form the retinal image on the retina.

7. A disappearance prevention device as described in claim 1, further comprising an eyelid opening / closing determination unit that determines whether the eyelid on the eyeball is open or closed, and the determination unit determines whether there has been any change in the retinal image for more than the predetermined time based on the determination result of the eyelid opening / closing determination unit.

8. The disappearance prevention device according to claim 1, wherein the variation unit varies the retinal image by mechanically varying the display device.

9. The disappearance prevention device according to claim 1, wherein the variation unit varies the retinal image by electronically varying the display image displayed on the display device in order to form the retinal image on the retina.

10. The disappearance prevention device according to claim 1, wherein the variation unit varies the retinal image by electronically blinking the display image displayed on the display device to form the retinal image on the retina.

11. A disappearance prevention device according to claim 1, wherein the variation unit generates a variation in the retinal image corresponding to at least one of fixational eye movements such as tremor, drift, and microsaccade.

12. The disappearance prevention device according to claim 2, wherein the deviation detection unit detects the deviation by irradiating the boundary between the iris and sclera of the eyeball with infrared light and detecting the amount of reflected light.

13. A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the eyeball, the disappearance prevention device comprising: an output unit that outputs a signal to vary the retinal image at predetermined time intervals; and a variation unit that varies the retinal image by mechanically varying the display device when the signal is input.

14. A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising: a determination unit that determines whether the retinal image has not changed for a predetermined period of time or more; and a communication unit that, when it is determined that the retinal image has not changed for the predetermined period of time or more, transmits an instruction signal to an external portable information device to vary the retinal image by electronically varying or blinking the display image displayed on the display device in order to form the retinal image on the retina.

15. A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising at least a displacement detection unit that detects displacement of the display device relative to the eyeball, or an eyelid opening / closing determination unit that detects the opening / closing of the eyelid on the eyeball, and a communication unit that transmits the detection result of the displacement detection unit or the determination result of the eyelid opening / closing determination unit to an external portable information device, and receives from the portable information device an instruction signal to vary the retinal image, or an image signal that has been processed to vary the retinal image by displaying an electronically varied or flashing display image on the display device to vary the retinal image, in response to the portable information device determining, based on the detection result or the determination result, that there has been no change in the retinal image for more than a predetermined period of time.

16. A disappearance prevention device that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention device comprising: a judgment unit that judges whether there is any change in the retinal image for a predetermined period of time or more based on at least the displacement of the display device relative to the eyeball or the opening and closing of the eyelids on the eyeball; and a communication unit that transmits the judgment result of the judgment unit to an external portable information device and, in response to the transmission of the judgment result, receives from the portable information device an instruction signal to vary the retinal image, or an image signal that has been processed to vary the retinal image by displaying an electronically varied or flashing display image on the display device.

17. A disappearance prevention device that prevents a visual image formed on the retina of a person's eyeball by a display device attached to the person's eyeball from disappearing due to adaptation of the visual function, the disappearance prevention device comprising: a communication unit that receives an instruction signal from an external portable information device to vary the retinal image when the external portable information device determines that there has been no change in the retinal image for a predetermined period of time or more; and a variation unit that varies the retinal image based on the instruction signal.

18. A disappearance prevention system that prevents a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the disappearance prevention system comprising: a disappearance prevention device attached to the eyeball; and a portable information device that communicates wirelessly with the disappearance prevention device, wherein at least one of the disappearance prevention device and the portable information device has a determination unit that determines whether the retinal image has not changed for a predetermined period of time or more, and the portable information device has a variation unit that varies the retinal image by electronically varying or blinking the display image displayed on the display device to form the retinal image on the retina when it is determined that the retinal image has not changed for the predetermined period of time or more.

19. A method for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the eyeball, the method comprising: determining whether the retinal image has not changed for a predetermined period of time or more; and varying the retinal image when it is determined that the retinal image has not changed for the predetermined period of time or more.

20. A method for preventing a visual image from disappearing due to adaptation of the visual function when a person views a retinal image formed on the retina of the eyeball by a display device attached to the person's eyeball, the method comprising: outputting a signal for varying the retinal image at predetermined time intervals; and, when the signal is output, varying the retinal image by mechanically varying the display device.

Images