Lens unit and imaging device

Abstract

To realize lens units and imaging devices that achieve high product quality. [Solution] The lens unit (100A) has a lens barrel (2) that houses internal components including a plurality of lenses (L2~L5) and spacers (S1~S5), including a rear lens (L5), on the eyepiece side of the front lens (L1). The eyepiece side surface of the front lens (L1) abuts against the lens barrel (2) in the axial direction, and the internal components are biased axially from the eyepiece side toward the front lens (L1). The lens barrel (2) has an inner diameter greater than or equal to the inner diameter of the portion that houses the rear lens (L5).

Description

Technical Field

[0007]

[0001] The present invention relates to a lens unit and an imaging device.

Background Art

[0002] In a lens unit disposed outside the vehicle cabin, an O-ring or a heater may be incorporated to prevent the intrusion of water or the like into the lens barrel, prevent the lens surface from becoming cloudy, and for snow melting (Patent Documents 1 and 2). In recent years, with the improvement in the performance of lenses, the requirement for the positional accuracy of the lens when incorporated has also increased. Various other aspects of lens units that can be mounted on in-vehicle cameras have been developed (Patent Document 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the prior art as described above, it is difficult to align the components of the lens unit with each other, and there is a risk that the product quality may vary due to tolerances.

[0005] For example, in the aspect of Patent Document 1, the distance between the first lens held by the cylindrical lens holder and the other lens groups varies greatly due to the cumulative tolerances of the components.

[0006] In the aspect of Patent Document 2, there is a risk that the amount of compression of the O-ring may vary due to the cumulative tolerances of the lenses.

[0007] The embodiment described in Patent Document 3 is such that the lens barrel is divided into a first housing section that houses a first lens group and a second housing section that houses a second lens group communicating with the first housing section. When processing these housing sections, it is necessary to chuck one housing section for processing and then re-chuck the other housing section for processing. When re-chucking is required in this way, the coaxiality between the first housing section and the second housing section deteriorates.

[0008] One aspect of the present invention aims to realize a lens unit and an imaging device that achieve high product quality. [Means for solving the problem]

[0009] To solve the above problems, a lens unit according to one aspect of the present invention is a lens unit comprising a front element lens, a lens barrel housing the front element lens, and a functional component sandwiched between the front element lens and the lens barrel, wherein the lens barrel houses an internal component including a plurality of lenses, including a rear element lens, and a spacer, on the eyepiece side of the front element lens, the eyepiece side surface of the front element lens is in contact with the lens barrel in the axial direction, the internal component is biased axially from the eyepiece side toward the front element lens, and the portion of the lens barrel on the objective side of the portion housing the rear element lens has an inner diameter greater than or equal to the inner diameter of the portion housing the rear element lens.

[0010] To solve the above problems, an imaging device according to one aspect of the present invention comprises a lens unit according to the above-described aspect of the present invention and an image sensor that receives light that has passed through the lens barrel of the lens unit. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to provide a lens unit and an imaging device that achieve high product quality. [Brief explanation of the drawing]

[0012] [Figure 1]This is a schematic cross-sectional view showing the configuration of a lens unit according to Embodiment 1 of the present invention. [Figure 2] This is a schematic cross-sectional view showing the configuration of an imaging device according to Embodiment 1 of the present invention. [Figure 3] This is a schematic cross-sectional view showing the configuration of a lens unit according to Embodiment 2 of the present invention. [Figure 4] This is a schematic cross-sectional view showing the configuration of a lens unit according to Embodiment 3 of the present invention. [Figure 5] This is a schematic cross-sectional view showing the configuration of a lens unit according to Embodiment 4 of the present invention. [Modes for carrying out the invention]

[0013] [Embodiment 1] [Lens Unit] One embodiment of the present invention will be described below. Figure 1 is a schematic cross-sectional view showing the configuration of a lens unit according to Embodiment 1 of the present invention. Details of the optical systems of each lens provided in the lens unit are omitted from the illustration.

[0014] As shown in Figure 1, the lens unit 100A includes at least a lens group L (lenses L1 to L5), a lens barrel 2, spacers S1 to S5, an O-ring 40, and an eyepiece-side retaining ring 50. In Figure 1, the upper side of the lens unit 100A is the objective lens side, and the lower side is the side where the image sensor, described later, is installed, the so-called eyepiece side.

[0015] The lens barrel 2 houses at least a lens group L inside the barrel. In this embodiment, the lens barrel 2 holds five lenses L1 to L5 as the lens group L. The lens L1 located closest to the objective lens is the so-called front lens L1. Further towards the eyepiece from the front lens L1 are multiple lenses L2 to L5. The lens L5 located closest to the eyepiece is the so-called rear lens L5.

[0016] In other words, it can be said that the lens barrel 2 houses the front lens L1 and also houses internal components on the eyepiece side of the front lens L1. In this case, the internal components include the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5, as well as spacers S1 to S5. Specifically, as the internal components, from the side close to the front lens L1 towards the eyepiece side, there are spacer S1, the second lens L2, spacer S2, the third lens L3, spacer S3, the fourth lens L4, spacer S4, the rear lens L5, and spacer S5, and these are housed in the lens barrel 2 in this order. Note that the internal components may include the optical filter F shown in FIG. 1.

[0017] Note that FIG. 1 shows the optical axis X of the lens group L. The optical axis X is located on the same line as the central axis of the lens barrel 2. Hereinafter, the direction along the central axis of the lens barrel 2 is referred to as the axial direction.

[0018] The lens barrel 2 has a lens barrel main body 20 and an objective side pressing ring 21 attached to the objective side end of the lens barrel main body 20. The lens barrel २ has a male screw portion 20a provided on the outer peripheral surface on the objective side of the lens barrel main body 20 and screwed with a female screw portion 21c provided on the inner peripheral surface of the objective side pressing ring 21, and these are screwed together. The lens barrel 2 includes an optical incident portion 22 that opens on the object side in the objective side pressing ring 21. The opening diameter 22w of the optical incident portion 22 is configured to be smaller than the lens outer diameter L1w of the front lens L1.

[0019] The eyepiece side pressing ring 50 described above is arranged at the eyepiece side end of the lens barrel 2. The eyepiece side pressing ring 50 has a male screw portion 50c provided on the outer peripheral surface and a female screw portion 20c provided on the lens barrel main body and screwed together.

[0020] The eyepiece side pressing ring 50 is an annular structure, and the central part of the ring is open, and the light that has passed through the rear lens L5 and the optical filter F passes through. The eyepiece side pressing ring 50 will be described later.

[0021] The front lens element L1 has its eyepiece-side surface in contact with the lens barrel 2 in the axial direction. Specifically, the outer diameter L1w of the front lens element L1 is larger than the outer diameters of the other lenses L2 to L5. The other lenses L2 to L5 have the same outer diameter. Consequently, the inner diameter of the area in the lens barrel body 20 that houses the other lenses L2 to L5 and spacers S1 to S5, i.e., the aforementioned internal components (which can be considered equal to the diameters of the other lenses L2 to L5), is smaller than the inner diameter of the area that houses the front lens element L1 (which can be considered equal to L1w in Figure 1).

[0022] Accordingly, at the boundary between the area housing the other lenses L2-L5 and spacers S1-S5 and the area housing the front lens L1, a contact surface 25 is provided in an annular shape around the optical axis X, extending radially toward the objective side. The eyepiece-side surface of the front lens L1 is in contact with this contact surface 25. The area of ​​the front lens L1 that is in contact with the contact surface 25 is a non-optically effective area.

[0023] As mentioned above, the front lens L1 is biased toward the eyepiece side by the objective side retaining ring 21 with a predetermined biasing force from the objective side. As a result, the eyepiece side surface of the front lens L1 is in firm contact with the contact surface 25.

[0024] The lens barrel 2 has a recess 26 along the circumferential direction at the boundary between the inner surface of the area housing the front lens L1 and the contact surface 25. An O-ring 40, which is a functional component, is housed in the recess 26. The O-ring 40 is sandwiched between the front lens L1 and the lens barrel 2 (lens barrel body 20).

[0025] The O-ring 40 is compressed between the front lens element L1 and the side of the recess 26, creating a liquid-tight seal between the front lens element L1 side of the O-ring 40 and the spacer S1 side of the O-ring 40. This sealing by the O-ring 40 prevents water from entering the barrel of the lens barrel 2 from outside the lens unit.

[0026] There are no particular restrictions on the material of the O-ring 40, but EPDM (ethylene propylene rubber), NBR (nitrile rubber), VMQ (silicone rubber), etc. can be used. Among these, EPDM is preferable from the viewpoint of operating temperature range, weather resistance, water resistance, and chemical resistance.

[0027] The front lens L1 is biased toward the eyepiece with a predetermined biasing force by the objective side retaining ring 21 from the objective side, and the eyepiece side retaining ring 50 is screwed onto the eyepiece side end of the inner surface of the lens barrel 2 (lens barrel body 20), so that the aforementioned internal components are biased axially by the front lens L1 and the eyepiece side retaining ring 50. In other words, the aforementioned internal components are biased axially from the eyepiece side toward the front lens L1 (which is biased toward the eyepiece side relative to the lens barrel 2). As a result, the spacer S1 can be said to be sandwiched between the front lens L1 and the second lens L2. Furthermore, spacer S2 is sandwiched between the second lens L2 and the third lens L3, spacer S3 is sandwiched between the third lens L3 and the fourth lens L4, spacer S4 is sandwiched between the fourth lens L4 and the rear lens L5, and spacer S5 is sandwiched between the rear lens L5 and the optical filter F. The optical filter F is biased toward the objective by the eyepiece-side retaining ring 50.

[0028] As mentioned above, the other lenses L2 to L5 have the same outer diameter. Also, the spacers S1 to S5 have the same outer diameter as the other lenses L2 to L5. For this reason, the part of the lens barrel 2 (lens barrel body 20) that houses the internal components has the same inner diameter along the axial direction. In other words, the part of the lens barrel 2 (lens barrel body 20) that is on the objective side of the part that fits with the rear lens L5 has the same inner diameter as the part that fits with the rear lens L5. To put it another way, the part of the lens barrel 2 (lens barrel body 20) that houses the internal components has the same inner diameter as the part that fits with the rear lens L5.

[0029] The telescope tube 2 (telescope tube body 20) may be made of resin or metal. Spacers S1 to S5 can be made using well-known spacer materials. Lenses L1 to L5 may be glass lenses or resin lenses.

[0030] When assembling the lens unit 100A as described above, the material of the lens barrel body 20 is processed to include an area for housing the front lens element L1 and areas for housing the other lenses L2 to L5 and spacers S1 to S5. In this processing, with the material of the lens barrel body 20 chucked, the areas for housing the other lenses L2 to L5 and spacers S1 to S5 are formed first, and then, while still chucked, the area for housing the front lens element L1 is continuously formed.

[0031] After preparing the lens barrel body 20 with each region formed in this manner, an O-ring 40 is placed in the recessed portion 26. Then, the front lens L1 is placed in the region that houses the front lens L1, and the objective-side retaining ring 21 is screwed on from the objective side. As a result, the front lens L1 contacts the contact surface 25 and is biased toward the eyepiece side with a predetermined biasing force. In this state, the lens barrel 2 has the front lens L1 at the bottom on the objective side and is open on the eyepiece side. Next, the internal components are sequentially placed in the open portion, that is, the region that houses the other lenses L2 to L5 and spacers S1 to S5. Finally, the optical filter F is placed, and the eyepiece-side retaining ring 50 is screwed onto the eyepiece side of the lens barrel body 20, thereby biasing it from the eyepiece side toward the objective side.

[0032] As described above, with the lens unit 100A of this embodiment, the internal components are biased axially from the eyepiece side toward the front lens L1, so that the tolerance of the distance between the front lens L1 and the other lenses L2 to L5 can be suppressed.

[0033] Furthermore, with lens unit 100A, since the eyepiece-side surface of the front lens L1 is in axial contact with the contact surface 25 of the lens barrel 2, the tolerance for the amount of compression of the O-ring 40 can be reduced.

[0034] Furthermore, the parts of the lens barrel that fit with each of the other lenses L2 to L5 (the parts that house the internal components) have the same diameter. In other words, the inner diameter of the part of the lens barrel that houses the internal components is the same as the outer diameter of the other lenses L2 to L5. Because of this configuration, as mentioned above, the lens barrel 2 (lens barrel body 20) can be formed with the same chuck processing, and this configuration does not cause the deterioration of coaxiality that is a concern in the prior art.

[0035] Based on the above, the lens unit 100A of this embodiment achieves high product quality.

[0036] [Imaging device] An embodiment of an imaging device equipped with the lens unit 100A described above will now be explained.

[0037] Figure 2 is a schematic diagram of the imaging device 400 of this embodiment, and is a cross-sectional view along the optical axis. The imaging device 400 includes the lens unit 100A shown in Figure 1 and an image sensor 300 arranged on the eyepiece side of the lens unit 100A. The image sensor 300 receives light that has passed through the lens groups L1 to L5 of the lens unit 100A.

[0038] Although the lens unit 100A is equipped with an optical filter F on the eyepiece side, the optical filter F may also be placed between the lens unit 100A and the image sensor 300.

[0039] Furthermore, the imaging device 400 may include a housing that houses the lens unit 100A and the image sensor 300.

[0040] [Embodiment 2] Other embodiments of the present invention are described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0041] In the above-described Embodiment 1, the lenses L2 to L5 located closer to the eyepiece than the front lens L1 have the same outer diameter. In contrast, in this embodiment, each of the multiple lenses L2 to L5 has a different outer diameter. The lens unit 100B of this embodiment will be described below with reference to Figure 3.

[0042] Figure 3 is a schematic cross-sectional view showing the configuration of the lens unit 100B of this embodiment, and corresponds to Figure 1. As shown in Figure 3, in the lens unit 100B, among the lenses L2 to L5 located closer to the eyepiece than the front lens L1, the rear lens L5 has the smallest outer diameter. Specifically, the outer diameters of the lenses increase in the order of rear lens L5, fourth lens L4, third lens L3, and second lens L2.

[0043] In other words, the inner diameter of the part of the lens barrel 2 that fits with lenses L2 to L5 differs for each lens.

[0044] When assembling the lens unit 100B of this embodiment, the material of the lens barrel body 20 is chucked to form the internal space from the eyepiece end to the objective end, and then the eyepiece retaining ring 50 is screwed onto the eyepiece side of the lens barrel body 20. Next, the optical filter F, spacer S5, rear lens L5, and spacer S4 are housed in that order, the second lens L2 is housed, then spacer S1 is housed, and the O-ring 40 is placed in the recess 26. Then, the front lens L1 is housed in the area for housing the front lens L1, and the objective retaining ring 21 is screwed onto it from the objective side. As a result, the front lens L1 contacts the contact surface 25 and is biased toward the eyepiece with a predetermined biasing force, while also being biased from the eyepiece side.

[0045] The lens unit 100B of this embodiment achieves the same effects as in Embodiment 1 and realizes a lens unit 100B with high product quality. Specifically, in the lens unit 100B of this embodiment, the internal components are biased axially from the eyepiece side toward the front lens L1, so the tolerance of the distance between the front lens L1 and the other lenses L2 to L5 can be suppressed.

[0046] Furthermore, with lens unit 100B, since the eyepiece-side surface of the front lens L1 is in axial contact with the contact surface 25 of the lens barrel 2, the tolerance for the amount of compression of the O-ring 40 can be reduced.

[0047] Furthermore, the parts of the lens barrel 2 (lens barrel body 20) that fit with the other lenses L2 to L5 have a minimum diameter on the rear lens L5 side, and the diameter widens towards the objective side. As a result, the lens barrel 2 (lens barrel body 20) can be formed with the same chuck processing as described above, and this configuration does not cause the deterioration of coaxiality that is a concern in conventional technology.

[0048] [Embodiment 3] Other embodiments of the present invention are described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0049] In the above-described Embodiment 1, an O-ring 40 (Figure 1) is provided as a functional component. In contrast, this embodiment differs from Embodiment 1 in that it is equipped with a heater as a functional component and does not have an O-ring. This embodiment will be described below with reference to Figure 4.

[0050] Figure 4 is a cross-sectional view showing the configuration of the lens unit 100C of this embodiment, and is a drawing corresponding to Figure 1. The lens unit 100C has a notched groove 27 provided on the contact surface 25 of the lens barrel body 20.

[0051] The notched groove 27 is provided adjacent to the optical axis X side of the annular contact surface 25, and opens toward the objective lens side as well as toward the optical axis X side. The notched groove 27 is configured in an annular shape around the optical axis X. A heater 60, which is a functional component, is installed in the notched groove 27.

[0052] The heater 60 is annular in shape and has a power supply route (not shown) provided for it. As shown in Figure 4, by positioning the heater 60 on the eyepiece side of the front lens L1, it is possible to raise the temperature of the front lens L1 using the heat from the heater 60. This prevents condensation from forming on the front lens L1 due to the temperature difference between the ambient temperature and the front lens L1, thereby providing a highly reliable lens unit. The heater 60 can be any well-known heater that can be mounted on a lens unit.

[0053] [Embodiment 4] Other embodiments of the present invention are described below. For the sake of clarity, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0054] In the above-described embodiment 1, the eyepiece-side retaining ring 50 is screwed onto the eyepiece side of the telescope tube 2 (telescope tube body 20), thereby biasing the internal components from the eyepiece side toward the objective side. In contrast, in this embodiment, the eyepiece side of the telescope tube 2 is not provided with a retaining ring. Instead, a crimping portion 28 is provided on the eyepiece side of the telescope tube body 20A itself.

[0055] The crimping portion 28 can bias the internal components housed in the telescope tube 2 (telescope tube body 20A) from the eyepiece side to the objective side. As a result, the internal components are biased axially by the front lens L1, which is biased toward the eyepiece side by the objective side retaining ring 21.

[0056] The lens unit 100D of this embodiment can achieve the same effects as in Embodiment 1.

[0057] 〔summary〕 As is clear from the above description, the lens unit of the first aspect of the present invention is a lens unit comprising a front element lens, a lens barrel housing the front element lens, and a functional component sandwiched between the front element lens and the lens barrel, wherein the lens barrel houses internal components including a plurality of lenses, including a rear element lens, and spacers, on the eyepiece side of the front element lens, the eyepiece side surface of the front element lens abuts the lens barrel in the axial direction, the internal components are biased axially from the eyepiece side toward the front element lens, and the portion of the lens barrel on the objective side of the portion housing the rear element lens has an inner diameter greater than or equal to the inner diameter of the portion housing the rear element lens. According to the first aspect, a lens unit of high product quality can be realized.

[0058] Specifically, since the internal components are biased axially from the eyepiece side toward the front lens element, the tolerance for the distance between the front lens element and the other lenses can be reduced.

[0059] Furthermore, according to the first embodiment, since the eyepiece-side surface of the front lens element is in contact with the lens barrel in the axial direction, the tolerance for the amount of compression of the O-ring can be reduced when the functional component is an O-ring.

[0060] Furthermore, according to the first embodiment, the portion of the lens barrel closer to the objective lens than the portion housing the rear lens element has an inner diameter greater than or equal to the inner diameter of the portion housing the rear lens element. As a result, the lens barrel can be formed using the same chucking process as described above, and the deterioration of coaxiality that is a concern in the prior art does not occur.

[0061] In a second embodiment of the present invention, the lens unit may have an O-ring as the functional component in the first embodiment. The second embodiment is suitable for sealing the eyepiece side of the front lens element.

[0062] In a third aspect of the present invention, the lens unit may have a heater as the functional component in the first or second aspect. According to the third aspect, by placing the heater on the eyepiece side of the front lens element, it is possible to raise the temperature of the front lens element by the heat of the heater. This is suitable for suppressing condensation on the front lens element due to the difference between the ambient temperature and the temperature of the front lens element.

[0063] In the fourth aspect of the present invention, the lens unit, in any of the first to third aspects, may have the same outer diameter for each of the plurality of lenses, and the same inner diameter for the portion of the lens barrel that houses the internal components as for each of the lenses. According to the fourth aspect, the lens barrel can be machined with the same chuck, so the central axis of the lens barrel can be realized with high precision.

[0064] In the fifth aspect of the present invention, the lens unit, in any of the first to fourth aspects, has an outer diameter that decreases towards the eyepiece side of the plurality of lenses, and the portion of the lens barrel that houses each of the plurality of lenses has a different inner diameter for each lens, with the portion housing the rear lens having the smallest inner diameter. According to the fifth aspect, since the lens barrel has an inner diameter greater than or equal to the inner diameter of the portion housing the rear lens, the lens barrel can be machined with the same chuck, and thus the central axis of the lens barrel can be realized with high precision.

[0065] In the sixth aspect of the present invention, the lens unit may have a lens barrel made of resin or metal, as described in any of the first to fifth aspects. If the lens barrel is made of resin, it is suitable for mass production, inexpensive, and allows for weight reduction of the product. If the lens barrel is made of metal, it does not expand due to moisture absorption, making it possible to create a product that is more resistant to changes over time.

[0066] A lens unit according to a seventh aspect of the present invention may, in any of the first to sixth aspects, have a lens barrel comprising a lens barrel body and an objective-side retaining ring attached to the objective-side end of the lens barrel body, wherein the front element lens is housed in the lens barrel body and biased toward the eyepiece side by the objective-side retaining ring. According to the seventh aspect, the biasing force of the front element lens relative to the lens barrel body can be adjusted by the degree to which the objective-side retaining ring is tightened, and the internal components are housed in the lens barrel in a state in which the front element lens is well biased axially from the eyepiece side toward the front element lens.

[0067] In the eighth aspect of the present invention, the lens unit, in any of the first to seventh aspects, further includes an eyepiece-side retaining ring or a crimping portion at the eyepiece-side end, and the internal components may be configured to be biased axially from the eyepiece side by the eyepiece-side retaining ring or the crimping portion. According to the eighth aspect, if an eyepiece-side retaining ring is provided, the biasing force toward the objective side can be adjusted by how tightly the eyepiece-side retaining ring is tightened. Furthermore, if a crimping portion is provided, biasing of the internal components can be achieved by a simple operation of fitting.

[0068] An imaging device according to the ninth aspect of the present invention comprises a lens unit according to any of the first to eighth aspects, and an image sensor that receives light that has passed through the lens barrel of the lens unit. According to the ninth aspect, an imaging device equipped with a lens unit of high product quality can be realized.

[0069] This configuration makes it possible to provide a lens unit suitable for in-vehicle cameras. This is expected to create an environment that promotes automation, such as autonomous driving of automobiles. Therefore, the present invention is expected to contribute to achieving the Sustainable Development Goals (SDGs) related to the expansion of technological innovation and the promotion of sustainable industrialization.

[0070] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0071] 2 Telescope tubes 20, 20A Telescope Tube Body 25 Contact surface 28 Crimping section 40 O-rings (functional parts) 60 Heater (Functional component) 100A, 100B, 100C, 100D lens units 300 image sensors 400 Imaging device L1 front element lens L2 Second lens (internal component) L3 Third lens (internal component) L4 4th lens (internal component) L5 rear lens element (internal component) S1, S2, S3, S4, S5 Spacers (internal parts)

Claims

1. A lens unit comprising a front element lens, a lens barrel housing the front element lens, and a functional component sandwiched between the front element lens and the lens barrel, The aforementioned lens barrel houses internal components including a plurality of lenses, including a rear lens, and a spacer, on the eyepiece side of the front lens. The eyepiece-side surface of the front lens element is in contact with the lens barrel in the axial direction. The aforementioned internal component is biased axially from the eyepiece side toward the front lens element. The portion of the lens barrel closer to the objective lens than the portion housing the rear lens element has an inner diameter greater than or equal to the inner diameter of the portion housing the rear lens element. Lens unit.

2. The aforementioned functional component is an O-ring. The lens unit according to claim 1.

3. The aforementioned functional component is a heater. The lens unit according to claim 1.

4. The outer diameters of each of the aforementioned lenses are equal to each other. The inner diameter of the portion of the lens barrel that houses the internal components is the same as the outer diameter of each lens. The lens unit according to claim 1.

5. The outer diameter of each lens in the aforementioned plurality of lenses is smaller towards the eyepiece side. The portion of the lens barrel that houses each of the multiple lenses has a different inner diameter for each lens, with the portion housing the rear lens having the smallest inner diameter. The lens unit according to claim 1.

6. The aforementioned lens barrel is made of resin or metal. The lens unit according to claim 1.

7. The lens barrel comprises a lens barrel body and an objective-side retaining ring attached to the objective-side end of the lens barrel body. The aforementioned front lens element is housed in the lens barrel body and is biased toward the eyepiece side by the objective side retaining ring. The lens unit according to claim 1.

8. The aforementioned telescope tube further includes an eyepiece-side retaining ring or a crimping portion at the eyepiece-side end, The internal component is biased axially from the eyepiece side by the eyepiece side retaining ring or the crimping portion. The lens unit according to claim 1.

9. An imaging device comprising a lens unit according to any one of claims 1 to 8, and an image sensor that receives light that has passed through the lens barrel of the lens unit.

Images