Compound eye camera based on electrowetting liquid diaphragm and adaptive imaging method

Abstract

The invention provides a compound eye camera based on an electrowetting liquid diaphragm and a self-adaptive imaging method. The compound eye camera comprises a plurality of sub-imaging units, a transparent substrate, an image sensor and a driving control module, the sub-imaging unit comprises a focusable lens and an electrowetting liquid diaphragm and is used for collecting sub-view field imaging light beams and regulating and controlling an imaging aperture; the transparent substrate is used for bearing the sub-imaging units; the image sensor is used for acquiring an image formed by the sub-imaging unit; the driving control module is used for providing driving signals for the focus-adjustable lens and the electrowetting liquid diaphragm in the sub-imaging unit; the driving control module sends a driving signal to each sub-imaging unit of the compound eye camera, and regulates and controls the size and the shape of an aperture diaphragm of each sub-imaging unit, so that the self-adaptive regulation and control of the imaging brightness of the compound eye camera is realized, and a scene irradiated by light with non-uniform intensity is clearly imaged. Or self-adaptive regulation and control of the imaging modulation degree are realized so as to selectively distinguish the target from the background.

Description

I. Technical Field

[0001] This invention relates to a compound eye camera and imaging method, and more specifically, to a compound eye camera and adaptive imaging method based on an electrowetting liquid aperture. II. Background Technology

[0002] The compound eye is a visual imaging organ composed of multiple ommatidia, possessing advantages such as a large imaging field of view and high dynamic sensitivity. The multi-aperture imaging structure of the compound eye breaks the spatial bandwidth product limitation of single-aperture imaging structures, inspiring researchers to develop a series of biomimetic compound eye cameras. However, most biomimetic compound eye cameras, once manufactured, have a fixed imaging aperture, making it difficult to adjust the pupil size and shape like the human eye or a cat's eye. This results in insufficient imaging adaptability; for example, it is difficult to adapt to different lighting environments, identify objects at different distances, and selectively distinguish between targets and backgrounds. Therefore, compound eye cameras lacking imaging aperture adjustment capabilities have many limitations in practical imaging applications.

[0003] Traditional cameras typically use mechanically driven components to adjust the aperture, thereby regulating image brightness and depth of field. However, this mechanical adjustment method results in a large lens assembly size and weight, as well as high power consumption. In compound-eye cameras composed of multiple sub-imaging units, this not only severely impacts the camera's structural compactness and reduces the aperture duty cycle, but also significantly increases the operating cost. Furthermore, this mechanical adjustment method is slow, difficult to adapt to highly dynamic scenes, and the aperture often maintains only a single rotationally symmetrical shape, lacking directional selectivity, which presents significant limitations. Therefore, there is an urgent need to invent a compound-eye camera with flexible and adjustable aperture size and shape, low power consumption, fast response, and high integration. III. Summary of the Invention

[0004] This invention proposes a compound eye camera based on an electrowetting liquid aperture and an adaptive imaging method. (See attached diagram) Figure 1 As shown, the compound eye camera includes several sub-imaging units, a transparent substrate, an image sensor, and a drive control module. Each sub-imaging unit includes a focusable lens and an electrowetting liquid aperture for collecting sub-field-of-view imaging beams and adjusting the imaging aperture. The electrowetting liquid aperture includes a sidewall electrode assembly, an insulating cavity, a solid lens, a first window glass, a transparent conductive liquid, a stained insulating liquid, and a second window glass. The inner surfaces of the electrodes in the sidewall electrode assembly are coated with a dielectric layer and a hydrophobic layer. The transparent substrate supports the sub-imaging units. The image sensor acquires images formed by the sub-imaging units. The drive control module provides drive signals to the focusable lens and the electrowetting liquid aperture in the sub-imaging units.

[0005] A schematic diagram of the structure and working state of the electrowetting liquid aperture in the neutron imaging unit of this invention is attached. Figure 2As shown. In the initial unpowered state, the dyed insulating liquid floats on top of the transparent conductive liquid, forming a ring structure. The area on the surface of the transparent conductive liquid not covered by the dyed insulating liquid has high light transmittance and serves as the aperture stop of the sub-imaging unit, with a diameter of a. 10 When the same voltage U is applied to all electrodes in the sidewall electrode group A AndU A When the driving voltage exceeds the threshold voltage, the dyed insulating liquid spreads towards the center under the effect of electrowetting, and the aperture stop maintains its circular shape, with its diameter shrinking to a. 11 a 11 10 As attached Figure 2 As shown in (a). When the same voltage U is applied to only a pair of opposing electrodes in the sidewall electrode group. B AndU B When the driving voltage exceeds the threshold voltage, the dyed insulating liquid flows under the effect of electrowetting, and the aperture stop takes on a long strip shape with a major axis length of a. 1a The length of the minor axis is a 1b a 1b 10 1a As attached Figure 2 As shown in (b), the size and shape of the aperture stop formed by the electrowetting liquid aperture stop are controlled by the voltage applied to the sidewall electrode assembly. Under different energizing states, the aperture stop stops exhibit circular shapes of different sizes, or elongated shapes of different sizes and along the major axis. A top view schematic diagram is attached. Figure 3 As shown.

[0006] In this invention, the optical power of the adjustable lens within the sub-imaging unit can be controlled by a driving signal to compensate for the focal plane drift of the sub-imaging unit caused by the change in interface curvature during aperture adjustment of the electrowetting liquid aperture, or to directly adjust the focal plane of the sub-imaging unit.

[0007] The schematic diagram illustrating the principle of adaptive imaging brightness control using the compound eye camera based on an electrowetting liquid aperture proposed in this invention is attached. Figure 4 As shown, when the target is illuminated by light of non-uniform intensity, the drive control module sends drive signals to each sub-imaging unit of the compound eye camera, so that the sub-imaging unit imaging the area of ​​the target illuminated by strong light has a smaller aperture stop and maintains focus on the target, and the sub-imaging unit imaging the area of ​​the target illuminated by weak light has a larger aperture stop and maintains focus on the target. At this time, the images of each sub-field of view captured by the compound eye camera are clear and have appropriate brightness, and there is no problem of image information loss due to overexposure or underexposure.

[0008] ​​​An adaptive imaging method for a compound eye camera based on an electrowetting liquid aperture, as proposed in this invention, is illustrated in the attached diagram, which demonstrates the principle of selectively distinguishing between targets and backgrounds through adaptive adjustment of imaging modulation. Figure 5 As shown. When a target and a background interference exist simultaneously in the imaging scene, and the spatial frequencies of the target and background interference image information differ, the drive control module sends drive signals to each sub-imaging unit of the compound eye camera. This causes the aperture stops of the sub-imaging unit imaging the region of interest (ROI) and the sub-imaging unit imaging the region of non-ROI to take on different sizes and long-axis elongated shapes. The modulation transfer function of the sub-imaging unit changes accordingly, resulting in a decrease in the contrast of the background image in the image captured by the sub-imaging unit imaging the ROI, allowing the ROI image to be clearly presented. Conversely, in the image captured by the sub-imaging unit imaging the region of non-ROI, the background image and the ROI image are mixed or blurred, and the ROI image cannot be clearly presented.

[0009] This invention proposes a compound eye camera based on an electrowetting liquid aperture, which significantly improves imaging adaptability compared to traditional compound eye cameras. In this proposed compound eye camera, the aperture size and shape of each sub-imaging unit are controlled solely through the electrowetting effect, without relying on any mechanical moving parts. This not only provides the compound eye camera with ample freedom of imaging adjustment but also ensures rapid adjustment, compact structure, and low driving power consumption. The compound eye camera and imaging method proposed in this invention can achieve regionalized and localized imaging adjustment through selective control of sub-imaging units, making it well-suited for imaging scenes with localized dynamic changes.

[0010] Preferably, the adjustable focus lens in the sub-imaging unit is an electrowetting liquid lens, a dielectric electrophoretic liquid lens, an electrostatic liquid lens, or a liquid crystal lens.

[0011] Preferably, the compound eye camera contains M≥2 sub-imaging units, and the sidewall electrode group of the electrowetting liquid aperture in the sub-imaging unit contains N≥4 electrodes, while ensuring that N is an even number.

[0012] Preferably, the density of the transparent conductive liquid in the electrowetting liquid aperture is not less than the density of the dyed insulating liquid.

[0013] Preferably, under normal operating conditions of the sub-imaging unit, at least one of the focusing lens and the solid lens of the electrowetting liquid aperture is a positive lens. IV. Description of the attached drawings

[0014] Appendix Figure 1 This is a schematic diagram of a compound eye camera based on an electrowetting liquid aperture according to the present invention.

[0015] Appendix Figure 2 This is a schematic diagram of the structure and working state of the electrowetting liquid aperture in the neutron imaging unit of the present invention. (a) Schematic diagram of the working state when all electrodes in the sidewall electrode group are subjected to the same voltage; (b) Schematic diagram of the working state when a pair of opposing electrodes in the sidewall electrode group are subjected to the same voltage.

[0016] Appendix Figure 3 These are top-view schematic diagrams of the electrowetting liquid aperture in the neutron imaging unit of the present invention under different energized states. (a) Top-view schematic diagram of the sidewall electrode group without energization; (b) Top-view schematic diagram of all electrodes in the sidewall electrode group when the same voltage is applied; (c) Top-view schematic diagram of a pair of opposing electrodes in the sidewall electrode group when the same voltage is applied; (d) Top-view schematic diagram of another pair of opposing electrodes in the sidewall electrode group when the same voltage is applied.

[0017] Appendix Figure 4 This is a schematic diagram illustrating the principle of adaptive brightness control in a compound eye camera based on an electrowetting liquid aperture proposed in this invention.

[0018] Appendix Figure 5 This is a schematic diagram illustrating the principle of selectively distinguishing between targets and backgrounds using a compound eye camera based on an electrowetting liquid aperture proposed in this invention.

[0019] Appendix Figure 6 These are top views of the electrowetting liquid aperture under different energized states in a specific embodiment of the present invention. (a) Top view when all electrodes in the sidewall electrode group are subjected to the same voltage; (b) Top view when a pair of opposing electrodes in the sidewall electrode group are subjected to the same voltage.

[0020] Appendix Figure 7 The figures show the experimental results of adaptive brightness control of an imaging device using a compound eye camera based on an electrowetting liquid aperture in a specific embodiment of the present invention. (a) Imaging experimental optical path; (b) Image captured by the compound eye camera before imaging adjustment; (c) Image captured by the compound eye camera after imaging adjustment.

[0021] Appendix Figure 8 The images show experimental results of selectively distinguishing between targets and backgrounds using a compound eye camera based on an electrowetting liquid aperture in a specific embodiment of the present invention. (a) Imaging experimental optical path; (b) Image captured by the compound eye camera before imaging adjustment; (c) Image captured by the compound eye camera after imaging adjustment.

[0022] The figure labels in the above figures are as follows:

[0023] (1) Sub-imaging unit, (2) Transparent substrate, (3) Image sensor, (4) Drive control module, (5) Adjustable focus lens, (6) Electrowetting liquid aperture, (7) Side wall electrode group, (8) Insulating cavity, (9) Solid lens, (10) First window glass, (11) Transparent conductive liquid, (12) Dyed insulating liquid, (13) Second window glass.

[0024] It should be understood that the above figures are merely schematic and not drawn to scale. The number of sub-imaging units in the compound eye camera and the number of electrodes in the sidewall electrode group of the electrowetting liquid aperture are only schematic. Increasing or decreasing the number of sub-imaging units in the compound eye camera and the number of electrodes in the sidewall electrode group of the electrowetting liquid aperture are essentially the same as the present invention and also fall within the protection scope of this patent. V. Detailed Implementation Methods

[0025] The following detailed description of an embodiment of a compound eye camera based on an electrowetting liquid aperture and an adaptive imaging method proposed in this invention further illustrates the invention. It is important to note that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of protection of this invention. Non-essential improvements and adjustments made to this invention by those skilled in the art based on the above description are still within the scope of protection of this invention.

[0026] This embodiment of a compound eye camera based on an electrowetting liquid aperture includes nine sub-imaging units, a transparent substrate, an image sensor, and a drive control module. Each sub-imaging unit includes one electrowetting liquid lens and one electrowetting liquid aperture, which are tightly fitted together. The electrowetting liquid lens has a light-transmitting aperture of 10 mm. When a driving voltage of 0 to 100 V is applied to the electrowetting liquid lens, the corresponding optical power variation range is +35.0 D to +47.1 D. The electrowetting liquid aperture includes a sidewall electrode group, an insulating cavity, a solid lens, a first window glass, a transparent conductive liquid, a dyed insulating liquid, and a second window glass. The sidewall electrode group includes four identical and symmetrically arranged electrodes made of copper with a 3 μm thick Parylene C dielectric layer and a 100 nm thick Teflon layer plated on the inner surface. TMThe AF2400 hydrophobic layer and insulating cavity are made of insulating resin. The solid lens is a plano-convex lens with a focal length of 24.2mm. The first window glass is flat soda-lime glass with an indium tin oxide conductive layer coated on its surface. The transparent conductive liquid is a mixture of tetrabutylammonium chloride and propylene glycol. The dyed insulating liquid is a mixture of isoparaffinic liquid dissolved with oily dyeing powder and p-bromoethylbenzene. The second window glass is flat soda-lime glass. The inner diameter of the insulating cavity of the electrowetting liquid aperture is 8mm. At an ambient temperature of 23℃, the volumes of the transparent conductive liquid and the dyed insulating liquid contained in the electrowetting liquid aperture are 180μL and 22μL, respectively. In the unenergized state, the dyed insulating liquid floats on top of the transparent conductive liquid and forms a ring structure. The diameter of the area on the surface of the transparent conductive liquid not adhered to by the dyed insulating liquid is 5.07mm. Figure 6 As shown in (a), when the same voltage from 0 to 30V is applied to all electrodes in the sidewall electrode group, the corresponding variation range of the aperture diameter formed by the electrowetting liquid aperture is from 5.07mm to 1.53mm. However, when the voltage reaches 35V or higher, the transparent conductive liquid surface of the electrowetting liquid aperture is covered by a dyed insulating liquid, i.e., the aperture aperture formed by the electrowetting liquid aperture is closed; as shown in the attached figure. Figure 6 As shown in (b), when the same voltage from 0 to 70V is applied to a pair of opposing electrodes in the sidewall electrode group, the aperture aperture formed by the electrowetting liquid aperture forms an elongated shape as the voltage increases. The maximum length of the long axis reaches 8mm, and the minimum length of the short axis reaches 0.84mm. The long axis is parallel to the line connecting the pair of opposing electrodes to which the voltage is applied. The long and short axis directions of the aperture aperture formed by the electrowetting liquid aperture can be adjusted by changing the opposing electrodes to which the voltage is applied.

[0027] The experimental results of a specific implementation of the compound eye camera based on an electrowetting liquid aperture using this embodiment to achieve adaptive control of imaging brightness are shown in the attached figure. Figure 7 As shown in the attached document. Figure 7 As shown in (a), an acrylic target printed with nine different animal patterns was used as the target, positioned 165 mm away from a compound eye camera based on an electrowetting liquid aperture. The nine different animal patterns were located within the field of view of nine sub-imaging units, with four patterns illuminated by a beam of 1700 lux and the remaining patterns illuminated by a beam of 760 lux. (See attached image.) Figure 7 As shown in (b), when no voltage is applied to the electrowetting liquid apertures in the nine sub-imaging units and a 12V voltage is applied to the electrowetting liquid lenses, the images captured by the compound eye camera show that the pattern illuminated by the 1700 lux beam is overexposed, while the pattern illuminated by the 760 lux beam is clearly visible; see attached image. Figure 7As shown in (c), when the drive signals of the four sub-imaging units that image the pattern illuminated by the beam of 1700 lux are adjusted, such that all electrodes in the sidewall electrode group of the electrowetting liquid aperture are applied the same voltage of 30V and the electrowetting liquid lens is applied the voltage of 31V, the aperture of the sub-imaging unit is reduced. It can be seen from the image captured by the compound eye camera that all nine animal patterns are clearly presented, thus proving that the compound eye camera based on the electrowetting liquid aperture has achieved brightness adaptive imaging control.

[0028] The experimental results of a specific implementation of the compound eye camera based on an electrowetting liquid aperture in this embodiment to selectively distinguish between targets and background are shown in the attached figure. Figure 8 As shown in the attached document. Figure 8 As shown in (a), an acrylic target with a total of nine "smiley face" and "sad face" patterns is used as the target, positioned 165 mm from the compound eye camera based on an electrowetting liquid aperture. An acrylic target with vertical stripes of 0.2 mm linewidth and a 1:1 fringe period is used as the interfering background, positioned 245 mm from the compound eye camera based on an electrowetting liquid aperture. The nine "smiley face" and "sad face" patterns are located within the field of view of the nine sub-imaging units. (See attached image.) Figure 8 As shown in (b), when a 60V voltage is applied to a pair of opposing electrodes parallel to the long side of the stripes in the nine sub-imaging units, and a 32V voltage is applied to the electrowetting liquid lens, it can be seen from the images captured by the compound eye camera that the target and background images are superimposed, and the "smiley face" and "sad face" patterns cannot be clearly presented; as shown in the attached image. Figure 8 As shown in (c), when the driving signals of the five sub-imaging units that image the "smiley face" pattern are adjusted, such that a 60V voltage is applied to the pair of opposing electrodes perpendicular to the long side of the stripe in the electrowetting liquid aperture and a 32V voltage is applied to the electrowetting liquid lens, the long axis direction of the aperture aperture changes accordingly, and the imaging modulation of the spatial frequency of the interfering background image features decreases. It can be seen from the image captured by the compound eye camera that the "smiley face" pattern is clearly presented, thus proving that the compound eye camera based on the electrowetting liquid aperture achieves selective differentiation between the target and the background.

Claims

1. A compound eye camera based on an electrowetting liquid aperture and an adaptive imaging method, characterized in that, The compound eye camera comprises several sub-imaging units, a transparent substrate, an image sensor, and a drive control module. The sub-imaging units include a focusable lens and an electrowetting liquid aperture, used for collecting sub-field imaging beams and adjusting the imaging aperture. The transparent substrate is used to support the sub-imaging units. The image sensor is used to acquire images formed by the sub-imaging units. The drive control module is used to provide drive signals to the focusable lens and the electrowetting liquid aperture in the sub-imaging units. The adaptive imaging method using this compound eye camera is described as follows: When the target is illuminated by light of non-uniform intensity, the drive control module sends drive signals to each sub-imaging unit of the compound eye camera, so that the sub-imaging unit that images the area of ​​the target illuminated by strong light has a small aperture stop and maintains focus on the target, and the sub-imaging unit that images the area of ​​the target illuminated by weak light has a large aperture stop and maintains focus on the target. The images of each sub-field of view captured by the compound eye camera are clear and have appropriate brightness. When a target and a background interference exist simultaneously in the imaging scene, and the spatial frequencies of the target and background interference image information differ, the drive control module sends drive signals to each sub-imaging unit of the compound eye camera. This causes the aperture stops of the sub-imaging unit imaging the region of interest (ROI) and the sub-imaging unit imaging the region of non-ROI to take on different sizes and long-axis elongated shapes. The modulation transfer function of the sub-imaging unit changes accordingly, resulting in a decrease in the contrast of the background image in the image captured by the sub-imaging unit imaging the ROI, and a clearer presentation of the ROI image. Conversely, in the image captured by the sub-imaging unit imaging the region of non-ROI, the background image and the ROI image are mixed or blurred, and the ROI image cannot be clearly presented.

2. A compound eye camera based on an electrowetting liquid aperture according to claim 1, characterized in that, The electrowetting liquid aperture in the compound eye camera comprises a sidewall electrode assembly, an insulating cavity, a solid lens, a first window glass, a transparent conductive liquid, a dyed insulating liquid, and a second window glass. The inner surfaces of the electrodes in the sidewall electrode assembly are coated with a dielectric layer and a hydrophobic layer. In the initial unpowered state, the dyed insulating liquid floats on top of the transparent conductive liquid and forms a ring structure. The area on the surface of the transparent conductive liquid not adhered to by the dyed insulating liquid serves as the aperture stop of the sub-imaging unit, with a diameter of a. 10 When the same voltage U is applied to all electrodes in the sidewall electrode group A And U A When the driving voltage exceeds the threshold voltage, the dyed insulating liquid spreads towards the center under the effect of electrowetting, and the aperture stop maintains its circular shape, with its diameter shrinking to a. 11 a 11 10 When the same voltage U is applied to only one pair of opposing electrodes in the sidewall electrode group B And U B When the driving voltage exceeds the threshold voltage, the dyed insulating liquid flows under the effect of electrowetting, and the aperture stop takes on a long strip shape with a major axis length of a. 1a The length of the minor axis is a 1b a 1b 10 1a .​​​ 3. A compound eye camera based on an electrowetting liquid aperture according to claim 1, characterized in that, The adjustable focus lens in the sub-imaging unit is an electrowetting liquid lens, a dielectric electrophoretic liquid lens, an electrostatic liquid lens, or a liquid crystal lens.

4. A compound eye camera based on an electrowetting liquid aperture according to claim 1, characterized in that, The number of sub-imaging units M contained in a compound eye camera is greater than or equal to 2.

5. In a compound eye camera based on an electrowetting liquid aperture according to claim 2, the number of electrodes N in the sidewall electrode group of the electrowetting liquid aperture is ≥4, and N should be an even number.

6. A compound eye camera based on an electrowetting liquid aperture according to claim 2, characterized in that, The density of the transparent conductive liquid in the electrowetting liquid aperture is not less than the density of the dyed insulating liquid.

7. A compound eye camera based on an electrowetting liquid aperture according to claim 1 or 2, characterized in that, Under normal operating conditions of the sub-imaging unit, at least one of the focusing lens and the solid lens of the electrowetting liquid aperture is a positive lens.

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