Optical device, imaging apparatus, display system, and mobile device

Abstract

To provide an optical device that can be miniaturized and can reduce a change in optical element holding power due to a change in temperature.SOLUTION: An optical device has a lens barrel that accommodates an optical element, and a pressing ring 30 that holds the optical element. The pressing ring includes an outer frame part 31 that is in contact with the lens barrel, a beam part 32 that is in contact with the optical element and is elastically deformable, and a connection part that connects the outer frame part and the beam part with each other. The beam part includes a first curved surface that faces the optical element, and a second curved surface that faces the outer frame part. The second curved surface is separated from the outer frame part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an optical device, an imaging device, a display system, and a moving device. [Background technology]

[0002] In recent years, various vehicle cameras have been used in the automotive industry to improve safety and support autonomous driving. For example, there are sensing cameras that obtain external conditions such as the distance to the vehicle ahead, and viewing cameras that capture the surroundings of the vehicle such as the driver's blind spot. These vehicle cameras are used in harsh temperature environments such as inside the car in midsummer and outside the car in midwinter, so they are required to maintain their optical performance over a wide temperature range.

[0003] On the other hand, vehicle cameras are composed of various parts such as multiple lenses, a lens barrel that houses the lenses, and a presser ring that fixes the lenses, and each part expands and contracts as the temperature changes. Therefore, since the linear expansion coefficient of the lens is generally small compared to that of the lens barrel, at high temperatures, the lens rattles, causing a shift in the lens spacing and a change in optical performance due to lens decentering, and at low temperatures, the optical performance changes due to lens surface deformation caused by tightening the lens.

[0004] Therefore, for example, in Patent Document 1, a holding arm is provided on the pressing ring, and the lens is held by elastic deformation.

[0005] Also, for example, in Patent Document 2, a metal plate that is elastically deformable in the tangential direction of the lens is provided to hold the lens. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 63-45562 [Patent Document 2] DE102006060088 specification Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional technology disclosed in the above-mentioned Patent Document 1, the elastic modulus of the holding arms needs to be small to cope with harsh temperature environments, and there is a risk that the lens barrel will become large if the holding arms are made long. Alternatively, the elastic modulus can be reduced by making the holding arms thinner, but this may result in the strength of the holding arms becoming weak.

[0008] Furthermore, in the conventional technology disclosed in the above-mentioned Patent Document 2, the lens is held by sheet metal that elastically deforms in the tangential direction, which requires space to be provided between the mounting plate and the bar, which can result in the lens barrel becoming larger.

[0009] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, one object of the present invention is to provide an optical device that can be made compact and that can reduce changes in the holding force of an optical element due to temperature changes. [Means for solving the problem]

[0010] In order to achieve the above object, an optical device according to one aspect of the present invention comprises: A lens barrel that houses an optical element; a pressing ring for holding the optical element; the pressing ring includes an outer frame portion that comes into contact with the lens barrel, a beam portion that comes into contact with the optical element and is elastically deformable, and a connecting portion that connects the outer frame portion and the beam portion, the beam portion includes a first curved surface facing the optical element and a second curved surface facing the outer frame portion, The second curved surface is spaced apart from the outer frame portion. Effect of the Invention

[0011] According to the present invention, it is possible to provide an optical device which can be miniaturized and in which changes in optical element holding force due to temperature changes can be reduced. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of an optical device 100 according to a first embodiment of the present invention, taken along a YZ plane passing through an optical axis. [Diagram 2] 1A is a front view of a first pressing ring 30 according to the first embodiment of the present invention as viewed from the -Z direction, and FIG. 1B is a perspective view of the first pressing ring 30 according to the first embodiment of the present invention. [Diagram 3] 1A is a front view of a first pressure ring 30 having an arc-shaped beam portion according to a first embodiment of the present invention, as viewed from the Z direction, and FIG. 1B is a front view showing an example configuration of a pressure ring 36 having a straight-line beam portion 37. [Figure 4] 1A is a front view of a pressure ring having an arc-shaped beam portion according to a first embodiment of the present invention, and FIG. 1B is a front view of an example configuration of a pressure ring 80 having a cantilever-shaped beam portion 82 as viewed from the Z direction. [Diagram 5] 5 is a graph for comparing the relationship between temperature and fastening load in FIG. 4(A) and FIG. 4(B). [Figure 6] 10(A) is a front view of a first pressing ring 66 according to a second embodiment of the present invention as viewed from the Z direction, and FIG. 10(B) is a front view of a first pressing ring 66 according to a second embodiment of the present invention as viewed from the -Z direction. [Figure 7] FIG. 11 is a front view of a first pressing ring 70 according to a third embodiment of the present invention, as viewed from the Z direction. [Figure 8] 1 is a diagram showing an example of a configuration in which an imaging device 86 according to an embodiment of the present invention is mounted on a moving body 85. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment. In each drawing, the same members or elements are given the same reference numerals, and duplicated descriptions are omitted or simplified.

[0014] <Example 1> Hereinafter, the configuration of an optical device 100 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the optical device 100 according to the first embodiment of the present invention cut along a YZ plane passing through the optical axis. In Fig. 1, the +Z direction is the object side, and the -Z direction is the image side.

[0015] In the optical device 100, the fifth lens 15, the fourth lens 14, the spacer 60, the third lens 13, and the second lens 12 are stored in the lens barrel 20 in this order. Furthermore, by pressing the second lens 12 with the first pressing ring 30, the fifth lens 15 is brought into contact with the first abutment surface 21 of the lens barrel 20, and the second lens 12, the third lens 13, the spacer 60, the fourth lens 14, and the fifth lens 15 are fixed.

[0016] Here, the first press ring 30 has a male thread on its outer periphery, and is fastened to a female thread provided on the inner periphery of the lens barrel 20. Note that a spacer 60 is disposed to maintain the third lens 13 and the fourth lens 14 at a predetermined distance.

[0017] Thereafter, sealing material 40 is stored in recess 23 of barrel 20, first lens 11 is stored in barrel 20, and first lens 11 is pressed by second pressing ring 50, whereby first lens 11 is abutted against second abutment surface 22, and first lens 11 and sealing material 40 are fixed. First lens 11 to fifth lens 15 function as optical elements.

[0018] The inner periphery of the second pressing ring 50 has a female thread, which is fastened to a male thread provided on the outer periphery of the lens barrel 20 that houses the optical element. The sealing material 40 is a resin such as an adhesive or an O-ring made of rubber, and prevents dust and moisture from entering the optical device 100 from the object side.

[0019] With this configuration, the optical device 100 holds a plurality of lenses and forms an image of light from the object side on an image sensor (not shown). For convenience, five lenses are used in the first embodiment, but the number of lenses is not limited to five. An imaging device is configured by the optical device 100 and an imaging element that images an object via the optical device, and the imaging device is mounted on, for example, a vehicle as a moving body.

[0020] Next, the structure of the first pressing ring 30 according to the first embodiment of the present invention will be described in detail with reference to Figures 2 to 5. Figure 2(A) is a front view of the first pressing ring 30 according to the first embodiment of the present invention as viewed from the -Z direction.

[0021] The first press ring 30 is configured with an outer frame portion 31 having a male screw portion on its outer periphery that abuts against and fastens to the lens barrel 20 described above, and an arc-shaped beam portion 32 that abuts against the peripheral portion of the second lens 12 and is elastically deformable. That is, the beam portion 32 is configured as an arc centered on the optical axis of the lens. Also, the arc-shaped beam portion 32 has a bridge structure in which at least a portion of the beam portion 32 is separated from the outer frame portion 31. That is, an arc-shaped long hole 35 is formed between the arc-shaped beam portion 32 and the outer frame portion 31.

[0022] Furthermore, convex portions 33 are provided in, for example, three places in the center of arc-shaped beam portion 32, and convex portions 33 abut against second lens 12 in the Z direction (thrust direction). That is, beam portion 32 has convex portions 33 that abut against the lens in a part (for example, three places) of beam portion 32. Note that convex portions 33 are disposed at three places along the circumferential direction of beam portion 32 at approximately equal angular intervals (i.e., every 120 degrees).

[0023] Then, by tightening the aforementioned male screw portion of the first pressure ring 30, the arc-shaped beam portion 32 elastically deforms in the optical axis direction of the lens as an optical element, and applies a load in the -Z direction to the second lens 12 to press it.

[0024] 2(B) is a perspective view of the first presser ring 30 according to the first embodiment of the present invention. Since the arc-shaped beam portion 32 is elastically deformed, the thickness in the Z direction (thrust direction) is preferably thinner than the thickness in the Z direction of the outer frame portion 31, and the radial width of the arc-shaped beam portion 32 on the XY plane is preferably longer than the width of the arc-shaped beam portion 32 in the Z direction (thrust direction).

[0025] That is, it is desirable that the thickness of the beam portion 32 in the optical axis direction of the lens is thinner than that of the outer frame portion 31, and that the width of the beam portion 32 in the direction perpendicular to the optical axis is greater than the width in the optical axis direction.

[0026] Fig. 3(A) is a front view of a first pressing ring 30 having an arc-shaped beam portion according to Example 1 of the present invention as viewed from the Z direction, and is a diagram for explaining the effect of the configuration of Example 1. Fig. 3(B) is a front view showing an example of the configuration of a pressing ring 36 having a linear beam portion 37.

[0027] For comparison, the outer diameter of the outer frame 31 is the same, and the length is set so that the spring constant of the arc-shaped beam 32 in Fig. 3(A) and the straight beam 37 in Fig. 3(B) are the same. The dashed lines in Fig. 3(A) and (B) represent the effective beam diameters D1 and D2 of the lenses held by the respective holding rings, and it can be seen that the relationship is D1>D2.

[0028] 3(A) according to the first embodiment of the present invention, the first pressing ring 30 having the arc-shaped beam portion 32 has an arc-shaped first curved surface 32a that follows the outer periphery of the lens on the optical axis side of the lens. The first curved surface 32a faces the lens and is partially in contact with the lens.

[0029] Therefore, even if the outer frame portion 31 has the same outer diameter, it can hold a larger lens. Moreover, the beam portion 32 has a second curved surface 32b facing the outer frame portion 31. Moreover, the second curved surface 32b is arc-shaped in a cross section perpendicular to the optical axis of the optical element.

[0030] Conversely, when holding a lens of the same size, a presser ring with a smaller configuration can be used. Therefore, as in the first embodiment, it is preferable that the arc of the arc-shaped beam portion 32 in this embodiment is configured as an arc along a circle centered on the optical axis of the lens to be held.

[0031] Fig. 4(A) is a front view of a first pressing ring 30 having an arc-shaped beam according to the first embodiment of the present invention as viewed from the Z direction, and shows a configuration having an arc-shaped beam 32 in the same configuration as Fig. 3(A). Meanwhile, Fig. 4(B) is a front view of a configuration example of a pressing ring 80 having a cantilever-shaped beam 82 as viewed from the Z direction, and shows an example of a configuration in which the beam 82 is cantilever-shaped in a pressing ring 80 having a similar shape to Fig. 4(A).

[0032] Moreover, Fig. 5 is a graph for comparing the relationship between temperature and fastening load in Fig. 4(A) and Fig. 4(B). The solid line in Fig. 5 is a graph for explaining the relationship between temperature and fastening load in the configuration of Fig. 4(A), and the dashed line is a graph for explaining the relationship between temperature and fastening load in the configuration of Fig. 4(B).

[0033] For comparison, the inner diameter of the arc-shaped beam 32 in Fig. 4(A) is the same as the inner diameter of the cantilever-shaped beam 82 in Fig. 4(B). The arc-shaped beam 32 shown in Fig. 4(A) has a larger distance from the force point to the fulcrum than the cantilever-shaped beam 82 shown in Fig. 4(B), so it has a smaller spring constant and, as shown in Fig. 5, the load fluctuation due to temperature fluctuation is smaller.

[0034] As described above, according to the first embodiment of the present invention, by forming the beam portion 32 of the first pressing ring 30, which is a pressing ring for a lens, in an arc shape, it is possible to reduce the spring constant of the beam portion 32 of the pressing ring without increasing the diameter of the pressing ring. Also, it is possible to reduce the change in the lens holding force over a wide temperature range.

[0035] <Example 2> FIG. 6(A) is a front view of a first pressing ring 66 according to the second embodiment of the present invention as viewed from the Z direction, and FIG. 6(B) is a front view of a first pressing ring 66 according to the second embodiment of the present invention as viewed from the -Z direction.

[0036] The arc-shaped beam portion 32 of the first pressure ring 30 in Example 1 is connected in the circumferential direction, while the arc-shaped beam portion 62 of the first pressure ring 66 in Example 2 is separated into three in the circumferential direction by three gaps 63 provided in the circumferential direction.

[0037] Moreover, each of the arc-shaped beam portions 62 separated into three has a gap between it and the outer frame portion 61, and is connected to the outer frame portion 61 by two connection portions 64. In the second embodiment, the arc-shaped beam portion 62 is separated into three in the circumferential direction by three gaps 63 provided in the circumferential direction, but the number of gaps is not limited to three, and may be two, or may be four or more.

[0038] Reference numeral 65 denotes a convex portion provided in the center of the arc-shaped beam portion 62, and the convex portions 65 are provided in, for example, three places and are configured to abut against the second lens 12 in the Z direction (thrust direction). In addition, an arc-shaped elongated hole 67 is formed between the arc-shaped beam portion 62 and the outer frame portion 61.

[0039] Even with the configuration of Example 2, as in Example 1, it is possible to reduce the spring constant of beam portion 32 of the pressure ring without increasing the diameter of the pressure ring, and furthermore, it is possible to stably maintain the lens holding force over a wide temperature range.

[0040] In the second embodiment, the beam portion 62 is divided along the outer periphery of the lens by the gap 63, and it is desirable that the sum of the lengths of the inner peripheries of the beam portions 62 be 70% or more of the length of the outer periphery of the lens in order to reduce the spring constant of the beam portions 62 and stably maintain the lens holding force.

[0041] <Example 3> 7 is a front view of a first pressing ring 70 according to Example 3 of the present invention as viewed from the Z direction. In Example 2, the three separated arc-shaped beam portions 62 are connected to the outer frame portion 61 by two connecting portions 64, respectively, whereas in the configuration of Example 3, the three separated arc-shaped beam portions 72 are connected to the outer frame portion 71 by one connecting portion 73, respectively, which is different.

[0042] Moreover, an arc-shaped long hole 74 is formed between the arc-shaped beam portion 72 and the outer frame portion 71. Incidentally, in the third embodiment, the arc-shaped beam portion 72 is also separated into three in the circumferential direction by three gaps provided in the circumferential direction, but the number is not limited to three, and may be two, or may be four or more.

[0043] Even with the configuration of Example 3, as in Examples 1 and 2, it is possible to reduce the spring constant of beam portion 72 of the pressure ring without increasing the diameter of the pressure ring, and further, it is possible to stably maintain the lens holding force over a wide range of temperatures.

[0044] In the third embodiment, the beam portion 72 is also divided by gaps along the outer periphery of the lens, but in a cross section perpendicular to the optical axis of the optical element, the sum of the lengths of the inner peripheries of the first curved surfaces 32a of the beam portion 72 is preferably 70% or more of the outer periphery of the lens. This makes it possible to reduce the spring constant of the beam portion 72 and stably maintain the lens holding force.

[0045] Fig. 8 is a diagram showing a configuration example in which an imaging device 86 according to an embodiment of the present invention is mounted on a moving body 85. The moving body 85 is equipped with the imaging device 86, and is capable of moving while holding the imaging device 86. Note that Fig. 8 shows a case in which the moving body 85 is an automobile (vehicle), but the moving body is not limited to an automobile, and may be any movable device, such as a ship, a train, an airplane, or a drone.

[0046] The mobile object 85 is equipped with an in-vehicle system (driving assistance device) (not shown) for assisting a user (such as a driver or a passenger) (not shown) using images acquired by an imaging device 86. 8 shows a case where the imaging device 86 is installed on the side of the moving body 85, the imaging device 86 may be installed in front or behind the moving body 85. In addition, two or more imaging devices 86 may be installed in two or more places on the moving body 85.

[0047] The imaging device 86 has the optical device 100 described above and an imaging element such as an image sensor (not shown), captures an image of the surroundings of the moving object 85, and generates image data. The image data is displayed on a display device such as an in-car display (not shown). This constitutes a display system including the imaging device and the display device that displays an image obtained based on the output of the imaging device.

[0048] The optical system (optical element) of the optical device 100, which is composed of multiple lenses, is an optical system (lens) in which the imaging magnification differs between a first angle of view (first field of view) 87 at the center and a second angle of view (second field of view) 88 outside the first angle of view 87.

[0049] The light receiving surface of the image sensor includes a first region for capturing an image of an object included in a first angle of view 87, and a second region for capturing an image of an object included in a second angle of view 88. Furthermore, the number of pixels per unit angle of view in the second region is greater than the number of pixels per unit angle of view in the first region.

[0050] That is, the resolution at a second angle of view 88 (second region) which is a peripheral angle of view of the optical system (lens) of the imaging device 86 is higher than the resolution at a first angle of view 87 (first region) which is a central angle of view of the optical system (lens). Note that, here, the increase in image height per unit angle of view is defined as the resolution.

[0051] 8, for example, when the imaging device 86 is disposed on the side of the moving body 85, a natural sense of perspective can be obtained when the user gazes at the vicinity of the front wheels of the moving body 85 or a vehicle behind by displaying an image corresponding to the second angle of view 88 on a display unit such as an electronic mirror. Driving assistance for the user can also be provided by displaying an image corresponding to the first area (first angle of view 87) on a display unit such as an in-vehicle display.

[0052] In addition, the optical device 100 of the imaging device 86 mounted on the moving body 85 as described above has the configuration as in Examples 1 to 3, so that the spring constant of the beam portion 32 of the pressing ring can be reduced without increasing the diameter of the pressing ring, thereby realizing a compact imaging device. Also, a stable lens holding force can be maintained even against sudden temperature changes, so that high quality images can be obtained.

[0053] Although the present invention has been described in detail based on the preferred embodiments, the present invention is not limited to the above embodiments, and various modifications are possible based on the spirit of the present invention, and are not excluded from the scope of the present invention. The present invention includes the following combinations.

[0054] (Configuration 1) An optical device comprising a lens barrel that houses an optical element, and a presser ring that holds the optical element, the presser ring comprising an outer frame portion that contacts the lens barrel, a beam portion that contacts the optical element and is elastically deformable, and a connection portion that connects the outer frame portion and the beam portion, the beam portion comprising a first curved surface that faces the optical element and a second curved surface that faces the outer frame portion, and the second curved surface that is spaced apart from the outer frame portion.

[0055] (Configuration 2) The optical device according to configuration 1, wherein the beam portion is elastically deformable in the optical axis direction of the optical element.

[0056] (Configuration 3) The optical device according to configuration 1 or 2, wherein the beam portion is configured as an arc centered on the optical axis of the optical element.

[0057] (Configuration 4) The optical device according to any one of configurations 1 to 3, wherein the beam portion has a convex portion that comes into contact with the optical element at a part of the beam portion.

[0058] (Configuration 5) An optical device described in any one of configurations 1 to 4, characterized in that the thickness of the beam portion in the optical axis direction of the optical element is thinner than that of the outer frame portion, and the width of the beam portion in the direction perpendicular to the optical axis of the optical element is longer than the width in the optical axis direction.

[0059] (Configuration 6) An optical device described in any one of configurations 1 to 5, characterized in that in a cross section perpendicular to the optical axis of the optical element, the sum of the lengths of the inner circumferences of the first curved surfaces of the beam portion is 70% or more of the length of the outer circumference of the optical element.

[0060] (Configuration 7) The optical device according to any one of configurations 1 to 6, wherein the resolution at the peripheral angle of view is higher than the resolution at the central angle of view, where the increase in image height per unit angle of view is taken as the resolution.

[0061] (Configuration 8) The optical device according to any one of configurations 1 to 7, wherein the second curved surface has an arc shape in a cross section perpendicular to the optical axis of the optical element.

[0062] (Configuration 9) An imaging apparatus comprising the optical device according to any one of configurations 1 to 8, and an imaging element that captures an image of an object via the optical device.

[0063] (Configuration 10) A display system comprising: the imaging device according to configuration 9; and a display device that displays an image obtained based on an output of the imaging device.

[0064] (Configuration 11) A moving device comprising the imaging device according to configuration 9, the moving device being capable of holding and moving the imaging device. [Explanation of symbols]

[0065] 11. First lens 12 Second lens 13 Third lens 14 Fourth lens 15. Fifth lens 20. Telescope tube 21...First abutment surface 22...Second abutment surface 23...Recess 30...First presser ring 31 Outer frame 32 Arc-shaped beam 33...Convex shape 40....Sealing material 50···Second presser ring 60···Spacer

Claims

1. A lens barrel that houses an optical element; a pressing ring for holding the optical element; the pressing ring includes an outer frame portion that comes into contact with the lens barrel, a beam portion that comes into contact with the optical element and is elastically deformable, and a connecting portion that connects the outer frame portion and the beam portion, the beam portion includes a first curved surface facing the optical element and a second curved surface facing the outer frame portion, The optical device according to claim 1, wherein the second curved surface is spaced apart from the outer frame portion.

2. The optical device according to claim 1 , wherein the beam portion is elastically deformable in the optical axis direction of the optical element.

3. 2. The optical device according to claim 1, wherein the beam portion is formed as an arc having a center on the optical axis of the optical element.

4. 2. The optical device according to claim 1, wherein the beam portion has a convex portion that comes into contact with the optical element.

5. The optical device according to claim 1, wherein the thickness of the beam portion in the optical axis direction of the optical element is thinner than that of the outer frame portion, and the width of the beam portion in the direction perpendicular to the optical axis of the optical element is longer than the width in the optical axis direction.

6. 2. The optical device according to claim 1, wherein in a cross section perpendicular to the optical axis of the optical element, the sum of the lengths of the inner circumferences of the first curved surfaces of the beam portion is 70% or more of the length of the outer circumference of the optical element.

7. 2. The optical device according to claim 1, wherein the resolution is defined as an increase in image height per unit angle of view, and the resolution at a peripheral angle of view is higher than the resolution at a central angle of view.

8. 2. The optical device according to claim 1, wherein the second curved surface has an arc shape in a cross section perpendicular to the optical axis of the optical element.

9. 9. An imaging apparatus comprising: the optical device according to claim 1; and an imaging element for imaging an object via the optical device.

10. 10. A display system comprising: the imaging device according to claim 9; and a display device that displays an image obtained based on an output of the imaging device.

11. A moving device comprising the imaging device according to claim 9, the moving device being capable of holding and moving the imaging device.

Images