Imaging lens and imaging device

Abstract

According to the imaging lens and the imaging device, even if the number of times of reflection is increased, the same reflection light guide element can be used. According to one aspect of the present application, the imaging lens comprises, in order according to a transmission order of light from an object side: a diaphragm; the lens group comprises at least one lens with positive focal power and at least one lens with negative focal power; and the reflection light guide element is used for emitting the light to the imaging element. The reflective light guide element has a plurality of reflective surfaces, and a light path is reflected n times on the plurality of reflective surfaces (n is an integer of 5 or more).

Description

Technical Field

[0001] This application relates to an imaging lens and an imaging device. Background Technology

[0002] Typically, wide-angle fixed-focus lenses mounted on smartphones extend along the thickness of the smartphone body to achieve focusing. This method of moving the lens along the thickness of the smartphone body is beneficial for achieving a thinner smartphone design. Telephoto lenses, due to their longer focal lengths, can use a periscope design. However, a periscope design means that the thickness of the smartphone body is determined by the size of the sensor's shorter side or the lens's aperture number. Therefore, telephoto lenses with large sensor sizes and small aperture numbers are not conducive to achieving a thinner smartphone body.

[0003] Furthermore, when reducing the thickness of a smartphone body using a periscope design, the lens may be made by cutting a circular lens section. However, in this case, the lens yield rate will be lower because it is impossible to mold the plastic lens and perform eccentric adjustments by rotation during lens mounting. Summary of the Invention

[0004] [The technical problem the invention aims to solve]

[0005] When installing a telephoto lens, using a reflective surface to refract light incident on the thickness of the smartphone body to increase the optical length is beneficial for achieving a thinner smartphone body. However, generally speaking, as the number of reflections of a single reflective light guide element increases, it is often necessary to add another reflective light guide element to the optical system to further increase the number of reflections. Therefore, with the increase in the number of reflections, it is difficult to further reduce the thickness of the smartphone body.

[0006] This application addresses the aforementioned problems and aims to provide an imaging lens and imaging device that allows the same reflective light guide element to be used even when the number of reflections increases.

[0007] [Methods for solving technical problems]

[0008] To address the aforementioned problems and achieve the stated objective, one aspect of this application provides an imaging lens, comprising, in the order of light transmission from the object side: an aperture stop; a lens group including at least one lens with positive optical power and at least one lens with negative optical power; and a reflective light guide element for directing light towards an imaging element. The reflective light guide element has multiple reflective surfaces, and the light path undergoes n reflections (n ​​is an integer of 5 or higher) on these surfaces.

[0009] [Technical Effects of the Invention]

[0010] According to one aspect of this application, the same reflective light guide element can still be used when the number of reflections increases. Attached Figure Description

[0011] Figure 1 This is a schematic diagram illustrating the structure of the imaging lens according to the first embodiment.

[0012] Figure 2 This is a diagram illustrating the margin setting.

[0013] Figure 3A It is an aberration diagram of astigmatism based on the imaging lens in Example 1.

[0014] Figure 3B It is an aberration diagram based on the spherical aberration of the imaging lens in Example 1.

[0015] Figure 3C It is an aberration diagram based on the distortion aberration of the imaging lens in Example 1.

[0016] Figure 3D It is an aberration diagram based on the magnification chromatic aberration of the imaging lens in Example 1.

[0017] Figure 4 This is a schematic diagram illustrating the structure of the imaging lens based on Example 2.

[0018] Figure 5A It is an aberration diagram of astigmatism based on the imaging lens in Example 2.

[0019] Figure 5B It is an aberration diagram based on the spherical aberration of the imaging lens in Example 2.

[0020] Figure 5C It is an aberration diagram based on the distortion aberration of the imaging lens in Example 2.

[0021] Figure 5D It is an aberration diagram based on the magnification chromatic aberration of the imaging lens in Example 2.

[0022] Figure 6 This is a schematic diagram illustrating the structure of the imaging lens based on Example 3.

[0023] Figure 7A It is an aberration diagram of astigmatism based on the imaging lens in Example 3.

[0024] Figure 7B It is an aberration diagram based on the spherical aberration of the imaging lens in Example 3.

[0025] Figure 7C It is an aberration diagram based on the distortion aberration of the imaging lens in Example 3.

[0026] Figure 7D It is an aberration diagram based on the magnification chromatic aberration of the imaging lens in Example 3.

[0027] Figure 8 This is a schematic diagram of the light path of an effective ray and the light path of a ghost ray, based on an example.

[0028] Figure 9 This is based on an example of how to cut off the light from a ghost image.

[0029] Figure 10 This is a schematic diagram illustrating the principle of cutting off ghost light from effective light.

[0030] Figure 11 yes Figure 9 A schematic diagram of another display form of the imaging lens shown.

[0031] Figure 12A It is an aberration diagram of astigmatism based on the imaging lens in Example 4.

[0032] Figure 12B It is an aberration diagram based on the spherical aberration of the imaging lens in Example 4.

[0033] Figure 12C It is an aberration diagram based on the distortion aberration of the imaging lens in Example 4.

[0034] Figure 12D It is an aberration diagram based on the magnification chromatic aberration of the imaging lens in Example 4.

[0035] Figure 13 This is a schematic diagram of an optical functional component that can be used in a reflective light guide element, based on an example.

[0036] Figure 14A This is a schematic diagram of the reflectivity wavelength characteristics of an example low-reflectivity black absorbing film.

[0037] Figure 14B This is a schematic diagram illustrating the black absorbing coating to be applied around the aluminum-enhanced reflective film.

[0038] Figure 15 This is a schematic diagram illustrating the wavelength characteristics of the reflectivity of an incident-dependent film.

[0039] Figure 16 This is a schematic diagram illustrating the structure of an example of an imaging apparatus according to the second embodiment.

[0040] Figure 17 This is a structural diagram of a camera unit based on an example camera.

[0041] Figure 18 This is a schematic diagram of the form factor of an example foldable smartphone.

[0042] Figure 19 This is a schematic diagram of the installation of an example imaging lens.

[0043] Figure 20 This is a schematic diagram of an imaging lens with a negative P_margin, based on an example.

[0044] Figure 21 This is a schematic diagram of the structure of a smartphone equipped with a periscope lens, based on an example. Detailed Implementation

[0045] The imaging lens and imaging device of the present application embodiments will now be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to the following embodiments.

[0046] Example

[0047] First Embodiment

[0048] Figure 1 This is a schematic diagram illustrating the structure of the imaging lens 1 according to the first embodiment. Figure 1 The structure of the imaging lens 1 shown is an example for brief illustration. Figure 1 In the middle, the left side is a schematic diagram of superimposing the optical paths of the principal ray, the upper ray, and the lower ray onto the imaging lens 1, and the right side is... Figure 1 The left figure shows a schematic diagram of the light path of the light rays passing through the lens optical axis within the reflective light guide element 30. Furthermore, Figure 1 The parameters of the imaging lens 1 are shown in the accompanying figures. Figure 1 The parameters shown in the text will be explained in detail later.

[0049] First, combined Figure 1 The imaging lens 1 shown here provides a brief description of the structure of an imaging lens with five reflections. In the following description, [the following will be...]. Figure 1 The imaging lens 1 shown on the right is called the right figure, and will be... Figure 1 The imaging lens 1 shown on the left is called the left image. Unless otherwise specified, it can refer to either the left or right image.

[0050] The imaging lens 1 includes an aperture stop 10, a lens group 20, and a reflective light guide element 30. Light from the object side is transmitted sequentially through the aperture stop 10, the lens group 20, and the reflective light guide element 30. The light passing through the reflective light guide element 30 is directed towards the infrared filter 40. A [missing information - likely a component or element] is provided on one side of the infrared filter 40. Figure 1 Imaging elements not shown in the image (see [reference]) Figure 2 The imaging element 50 shown.

[0051] It should be noted that, in addition to the aperture stop 10, lens group 20, and reflective light guide element 30, the imaging lens 1 may also include a color correction component, such as... Figure 1 The infrared filter 40 shown, or other optical elements.

[0052] Structure of the lens group

[0053] Hereinafter, the first lens, second lens, third lens, and fourth lens will be referred to as first lens L1, second lens L2, third lens L3, and fourth lens L4, respectively. In the attached drawings and tables, the corresponding lens elements will be labeled with L1, L2, L3, and L4, respectively.

[0054] Figure 1 The lens group 20 shown is a four-element lens group, which includes, from the object side, a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. Since the lens group 20 is a four-element structure, the first lens L1 corresponds to the lens through which light rays from the object side first pass, and the fourth lens L4 corresponds to the lens through which light rays from the object side finally pass. It should be noted that in the case of a five-element lens group, the "final lens" is the fifth lens L5, and in the case of a six-element lens group, the "final lens" is the sixth lens L6.

[0055] Figure 1 The structure of the imaging lens 1 shown is an example of a four-element lens group 20, but even if the lens group 20 has a different number of elements, such as a five-element or a six-element lens, the imaging lens 1 can still have the same overall structure as described below.

[0056] Lens group 20 includes at least one lens with positive optical power and at least one lens with negative optical power. Figure 1 In the structure of the imaging lens 1 shown, the first lens L1 and the second lens L2 are lenses with positive optical power, and the third lens L3 and the fourth lens L4 are lenses with negative optical power.

[0057] Structure of reflective light guide element

[0058] The reflective light guide element 30 guides the light rays incident from the incident surface 301 of the reflective light guide element 30 to its exit surface 302. Figure 1 The outline of the reflective light guide element 30 shown is an example, and its partial outline structure enables the incident light to be reflected internally.

[0059] Figure 1 The reflected light guide element 30 shown is a prism with a five-fold reflection design. It has a first inclined surface 303, a first plane 304, a second plane 305, and a second inclined surface 306, and the angles between these surfaces are such that the incident light undergoes total internal reflection. For example, as... Figure 1As shown in the right figure, light rays incident on the incident surface 301 along the optical axis of the lens undergo total internal reflection in sequence on the first inclined surface 303, the first plane 304, the second plane 305, the first plane 304, and the second inclined surface 306. After the fifth total internal reflection, the light rays exit from the exit surface 302 of the reflective light guide element 30 and are directed towards the infrared filter 40.

[0060] It should be noted that when an optical system with a longer focal length is used to extend the optical path inside the reflective light guide element 30, the reflective light guide element 30 can not only be a five-fold reflection design, but also have six or more reflections.

[0061] In the case of six reflections, the first plane 304 and the second plane 305 extend further, and since the number of reflections becomes even, the second inclined plane 306 is parallel to the first inclined plane 303. In this case, the infrared filter 40 is disposed on one side of the second plane 305, and light is incident on the second plane 305. In this case, the imaging element (see...) Figure 2 The imaging element 50 shown is also disposed on one side of the second plane 305.

[0062] In the case of seven reflections, the first plane 304 and the second plane 305 extend further, and since the number of reflections is odd, just like in the case of five reflections, the direction of the second inclined plane 306 is... Figure 1 The second inclined plane 306 shown is parallel. In this case, it is similar to... Figure 1 In the arrangement shown, the infrared filter 40 is disposed on one side of the first plane 304, and light is incident on the first plane 304. In this case, the imaging element (see...) Figure 2 The imaging element 50 shown is also disposed on one side of the first plane 304.

[0063] Furthermore, depending on the number of reflections, the first plane 304 and the second plane 305 can be appropriately extended, and the second inclined plane 306 can also be adjusted in its arrangement direction according to the parity of the number of reflections. Therefore, it can be considered that the reflective light guide element with an n-fold reflection structure will direct the light towards the photosensitive surface of the imaging element located on the side of the reflective surface where the (n-1)-fold reflection occurs after the nth reflection.

[0064] Since the following description of the reflective light guide element 30 is based on the reference... Figure 1 The example shown is an odd-numbered reflection structure, so both the incident surface and the exit surface are located on the first plane.

[0065] In such Figure 1In the outline of the reflective light guide element 30 shown, both the incident surface 301 and the exit surface 302 correspond to the first plane. In the first plane, the area that serves as the incident surface 301 is different from the area that serves as the exit surface 302. When light is incident into the interior of the reflective light guide element 30 at a total internal reflection angle, the first plane including the incident surface 301 and the exit surface 302 acts as a reflective surface.

[0066] According to such Figure 1 In the structure shown, the incident surface 301 performs total internal reflection on light rays reflected from the first inclined surface 303 with an incident angle greater than or equal to a predetermined angle. The exit surface 302 performs total internal reflection on light rays reflected from the second plane 305 with an incident angle greater than or equal to a predetermined angle towards the second inclined surface 306. The predetermined angle is an incident angle that satisfies the condition for total internal reflection. It should be noted that in the case of an even-numbered reflection structure, the exit surface performs total internal reflection on light rays with an incident angle greater than or equal to a predetermined angle towards the second inclined surface 306.

[0067] Here, the first inclined surface 303, the first plane 304, the second plane 305, and the second inclined surface 306 are examples of "reflective surfaces".

[0068] It should be noted that when there are surfaces in the "reflective surfaces" such as the first inclined surface 303, the first plane 304, the second plane 305, and the second inclined surface 306 that do not meet the effective total internal reflection angle, a reflective material can be applied to the target surface (excluding the incident surface 301 and the exit surface 302) to reflect light. For example, a metal-enhanced reflective film can be formed as a metal reflective coating by metal vapor deposition. As an example, the metal reflective coating can be an aluminum reflective coating, such as an aluminum metal-enhanced reflective film.

[0069] Furthermore, when it is necessary to change the reflectivity according to the incident angle of light, a dichroic reflector can be set on the reflective surface to increase the reflectivity of effective light and remove or reduce ineffective light.

[0070] Detailed explanations of the aluminum reflective coating and dichroic mirrors will follow.

[0071] Other structures

[0072] Infrared filter 40 is an example of a color difference correction component that performs infrared absorption. The color difference correction component can be replaced with other components that perform color correction as needed, and is not limited to infrared absorption.

[0073] The lens group 20 of the imaging lens 1 may have a structure driven by a drive device such as a voice coil motor (VCM) and mechanically extend and retract along the thickness direction P1 of the imaging device body.

[0074] When adopting such Figure 1 The structure shown, i.e., when the exit surface 302 and the incident surface 301 of the reflective light guide element 30 are both located on the first plane, the infrared filter 40 and the surface not on the first plane... Figure 1 The imaging element shown in the figure (such as Figure 2 The imaging element 50 shown is positioned on the same plane as the incident surface 301, facing each other. It should be noted that in the case of an even-numbered reflection structure, since the exit surface is located on the second plane, the infrared filter 40 and the imaging element (see...) are positioned... Figure 2 The imaging elements 50 shown are positioned on a second plane so that they face each other.

[0075] The imaging element comprises multiple pixels arranged in a two-dimensional array and performs photoelectric conversion on light from the object, outputting pixel signals. The imaging element 50 is an image sensor, such as a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS), used to image the object.

[0076] Parameter Description

[0077] The following is about Figure 1 The parameters of the imaging lens 1 shown are explained below. It should be noted that even if the lens group 20 uses a different... Figure 1 The lens structures shown share common parameters as long as they have the same constituent elements.

[0078] First, regarding Figure 1 The parameters shown in the left figure are explained below. P_od represents the distance between the optical axis of the lens group 20 and the optical axis of the light ray emitted from the reflective light guide element 30 to the imaging element, in millimeters (mm). L represents the distance from the vertex of the first lens L1 to the reflective light guide element 30. Pref_d represents the distance between the incident surface 301 of the reflective light guide element 30 and the intersection point where the lens optical axis intersects with the first inclined surface 303. Here, the lens optical axis refers to the optical axis of the center of the lens in the lens group 20, in millimeters (mm). P_t represents the thickness of the reflective light guide element 30 in the direction of the lens optical axis, in millimeters (mm).

[0079] Secondly, regarding Figure 1 The parameters shown in the right figure will be explained. θ represents the angle between the incident surface 301 of the reflective light guide element 30 and the inclined surface of the first inclined surface 303. In... Figure 1In the outline example of the reflective light guide element 30 shown, the angle between the emitting surface 302 and the inclined surface of the second inclined surface 306 is also θ, and the values ​​of θ mentioned above are the same. It should be noted that in the case of an even-numbered reflection structure, the emitting surface is located on the second plane; therefore, the second plane is parallel to the plane shown above. Figure 1 The angle between the first inclined plane 303 and the second inclined plane 306 shown is θ. The unit of θ is degrees (deg). PL represents the optical length of the light ray propagating along the optical axis of the lens inside the reflective light guide element 30.

[0080] In addition, EFL represents the focal length of the entire lens. dd represents half the diagonal dimension of the photosensitive surface of the imaging element. EPD represents the exit pupil diameter. P_margin represents the margin parameter described later. f_F represents the focal length (combined focal length) of the front lens in lens group 20 excluding the last two lenses. f_B2 represents the focal length (combined focal length) of the last two lenses in lens group 20.

[0081] Optical setting conditions

[0082] The inventors simulated optical systems under various settings and derived particularly effective optical settings for designs with five or more reflections.

[0083] (Condition 1)

[0084] 4 < EFL / dd

[0085] (Condition 2)

[0086] EPD / PL < 0.24

[0087] (Condition 3)

[0088] P_margin = PL_1 - PL_2 > 0

[0089] (Condition 4)

[0090] f_F > 0

[0091] (Condition 5)

[0092] f_B2 < 0

[0093] (Condition 6)

[0094] -1.5 < f_B2 / f_F < -0.5

[0095] (Condition 7)

[0096] L > P_t

[0097] (Condition 8)

[0098] EPD / Pref_d < 3.25

[0099] Condition 1 concerns the conditions for achieving five or more reflections in a telephoto lens system.

[0100] Condition 2 concerns the proper setting of the optical length.

[0101] Condition 3 concerns setting a margin within the reflective light guide element 30. The margin will be discussed later. Figure 2 Please provide a detailed explanation.

[0102] Condition 4 concerns the condition for the front lens in lens group 20, excluding the last two lenses, to have positive optical power.

[0103] Condition 5 concerns the condition that makes the last two lenses in lens group 20 have negative optical power.

[0104] Condition 6 concerns the constraint on the focal length ratio. When within this range, the back focal length can be lengthened to facilitate settings that favor five or more reflections.

[0105] Condition 7 concerns the condition that the thickness of the reflective light guide element 30 in the direction of the lens optical axis is less than the thickness of the lens group 20.

[0106] Condition 8 concerns the use of distance Pref_d to increase the optical length.

[0107] Explanation of the margin in condition 3

[0108] The following explains the case where a margin is set in a reflective light guide element 30 having five or more reflections. When fabricating a reflective light guide element 30 having five or more reflections, a margin as described below needs to be set.

[0109] Figure 2 This is a diagram illustrating the margin setting. (In...) Figure 2 In the imaging lens 1 shown, for example, Figure 1 The left figure shows the light rays incident on imaging lens 1, illustrating the direction of P2 ( Figure 2 (As shown) The main ray a1, upper ray a2, and lower ray a3 in the light beam that converges to the photosensitive surface of the imaging element 50 at the position furthest from the optical axis of the lens. The lower ray a3 refers to the ray that passes through the lens group 20 in the beam and is directed toward the imaging element 50, i.e., the first ray.

[0110] like Figure 2As shown, in the case of a five-reflection structure, a margin is provided inside the reflective light guide element 30 between the position b1 of the third reflection of the lower ray a3 and the surface where the fifth reflection occurs, i.e., between the surface of the second plane 305 and the junction b2 of the second plane 305 and the second inclined plane 306. Figure 2 In the code, the parameter P_margin indicates the setting position of the margin. Additionally, the parameter AREA1 is added to describe the margin. P_margin is the parameter used to represent the numerical value of the margin.

[0111] The following expressions (1) and (2) are for... Figure 2 The margin parameter P_margin in the imaging lens 1 shown is a formula and an exemplary expression generalized to structures with five or more reflections. Here, n is the number of reflections within the reflective light guide element, and n is an integer greater than or equal to 5.

[0112] <expression (1)>

[0113] Expression (1) is the expression for the incident light ray a3 parallel to the optical axis of the lens.

[0114] AREA1 = (EPD / 2) / LTL*(LTL-L)

[0115] PL_2 = AREA1 + P_t*TAN(θ*2)*(n-4) + (AREA1*TANθ + Pref_d)*TAN(2*θ)

[0116] <Expression (2)>

[0117] In fact, since the lower ray a3 is not strictly parallel to the optical axis of the lens, it is necessary to correct it based on expression (1) and in combination with the incident angle deviation of the lower ray a3, resulting in expression (2). For example, when the incident angle deviation is 1°, the following expression (2) can be obtained.

[0118] AREA1 = (EPD / 2) / LTL*(LTL-L)

[0119] PL_2' = AREA1 + P_t*TAN((θ+1)*2)*(n-4) + (AREA1*TAN(θ+1) + Pref_d)*TAN(2*(θ+1))

[0120] <Conditions>

[0121] When actually fabricating a reflective light guide element 30 with five or more reflections, the following conditions should be met:

[0122] (Condition 3)

[0123] P_margin = PL_1 - PL_2 > 0

[0124] Where PL_1 = P_od - (P_t-Pref_d) / TANθ

[0125] As described above, expressions (1) and (2) are exemplary expressions when generalizing P_margin to reflection structures of order five or higher. Specifically, expressions (1) and (2) include: a method based on... Figure 1 The structure of the imaging lens 1 shown includes an expression for extending five reflections to an odd number of reflections exceeding five, and an expression for an even number of reflections structure that extends five reflections to at least six.

[0126] Condition 3 also holds true when the number of reflections exceeds five. For example, in the case of six reflections, since the second inclined plane 306 is parallel to the first inclined plane 303, the lower ray a3 incident inside the reflective light guide element 30 is at position b1 where it undergoes its fourth reflection. A margin is provided between position b1 and the surface where the sixth reflection occurs, i.e., between the boundary b2 between the surface position of the first plane 304 and the surface of the first plane 304 and the second inclined plane 306. Furthermore, in the case of seven reflections, a margin is provided inside the reflective light guide element 30 between position b1 where the lower ray a3 undergoes its fifth reflection and the surface where the seventh reflection occurs, i.e., between the surface position of the second plane 305 and the boundary b2 between the surface of the second plane 305 and the second inclined plane 306.

[0127] In other words, in the case of n reflections (n ​​being an integer of 5 or more), a margin is set between the position where the lower ray a3 undergoes the (n-2)th reflection and the surface undergoing the nth reflection inside the reflective light guide element 30. Through condition 3, when the imaging lens includes a reflective light guide element with five or more reflections, the arrangement of the lens and the reflective light guide element can satisfy the condition of "margin > 0".

[0128] It should be noted that expressions (1) and (2) are based on the following: Figure 1 The imaging lens 1 shown is an exemplary structure that enables five or more reflections. It is not necessarily limited to a structure that satisfies the relationship between expression (1) or expression (2).

[0129] Example

[0130] Conditions 1 through 8 can be combined appropriately as needed. The following shows some structures of the imaging lens 1, along with simulation results of implementation data satisfying the above conditions.

[0131] First, Example 1 shows, as follows Figure 1 The image lens 1 shown is an example of an exemplary structure. Examples 2 and 3 subsequently illustrate examples with different lens configurations. It should be noted that, unless otherwise stated, the five reflection paths in the image lens all employ the same... Figure 1 The same display format is shown in the left figure. Furthermore, starting with Example 2, as... Figure 1 The common elements in the imaging lens 1 shown, such as aperture 10, lens group 20, reflective light guide element 30 and infrared filter 40, are still referred to by the same names as aperture, lens group, reflective light guide element and infrared filter, respectively, but their reference numerals are changed in each example.

[0132] Example 1

[0133] Example 1 is in Figure 1 In the exemplary structure of the imaging lens 1 shown, an example is a four-element lens group 20 with a 35mm equivalent focal length of 132mm and an aperture number (FNO) of 3.5 achieved by a 1 / 2-inch sensor. Tables 1 to 4 below provide examples of such... Figure 1 The table is a summary of the optical parameters of the exemplary configuration of the imaging lens 1 shown.

[0134]

[0135] Table 1 shows the radius of curvature R, spacing D, refractive index Nd, Abbe number Vd, and focal length.

[0136] In addition, Table 1 shows the positions of the aperture 10, the lenses of the lens group 20, the reflective light guide element 30, and the infrared filter 40. For example, the data marked "STO" in the "Surface Number" column is the data for the aperture 10. The data marked "3" and "4" in the "Surface Number" column are the data for the first lens L1, where "3" is the object-side surface data and "4" is the imaging-side surface data. Similarly, the data marked "5" and "6" in the "Surface Number" column are the data for the second lens L2, where "5" is the object-side surface data and "6" is the imaging-side surface data. The data marked "7" and "8" in the "Surface Number" column are the data for the third lens L3, where "7" is the object-side surface data and "8" is the imaging-side surface data. The data marked "9" and "10" in the "Surface Number" column are the data for the fourth lens L4, where "9" is the object-side surface data and "10" is the imaging-side surface data.

[0137] The data marked "11" in the "Surface Number" column is the data for the reflective light guide element 30, and the data marked "13" in the "Surface Number" column is the data for the infrared filter 40.

[0138] Additionally, in Table 1, f_B2 represents the focal length (combined focal length) of the two rear lenses. The "two rear lenses" refer to the lens through which the object-side light rays last pass and the lens preceding it in the lens configuration. f_F represents the focal length (combined focal length) of the front lens excluding the two rear lenses. The "front lens excluding the two rear lenses" refers to all other lenses in the lens configuration besides the aforementioned two rear lenses.

[0139] Due to such Figure 1 The structure shown is a four-element lens group 20, therefore f_F is the focal length of the first two lenses, namely the first lens L1 and the second lens L2. In the case of a five-element lens group, f_F is the focal length of the first three lenses from the first lens L1 to the fifth lens L5. In the case of a six-element lens group, f_F is the focal length of the first four lenses from the first lens L1 to the sixth lens L6.

[0140] It should be noted that the perspective from which this data is examined is the same in other examples.

[0141]

[0142] Table 2 shows the shape data of the aspherical surfaces in lens group 20 (surface numbers 3 to 10).

[0143]

[0144] Table 3 shows the following... Figure 1 All key parameter data of the exemplary structure of the imaging lens 1 shown are as follows. LTL is the parameter for the total length of the lens, representing the total optical path length from the vertex of the first surface of the first lens L1 to the photosensitive surface. da is the parameter for the diameter of the aperture stop 10. DFOV is the parameter for the diagonal field of view of the lens. FNO is the aperture number. EFL is the focal length of the entire lens, corresponding to the focal lengths of the first lens L1 to the fourth lens L4 in Table 1. Other parameters have been described above and will not be repeated here.

[0145]

[0146] Table 4 shows the data related to the structure of the reflective light guide element 30. It should be noted that the parameter symbols in Table 4 have already been explained above and will not be repeated here.

[0147] Figure 3A , Figure 3B , Figure 3C and Figure 3D Here is the aberration diagram of imaging lens 1 according to Example 1.

[0148] Figure 3A An aberration diagram of astigmatism with the imaging plane as the reference is shown, where the horizontal axis represents image height and the vertical axis represents aberration magnitude. Figure 3A This illustrates the case where the maximum image height is achieved when the diagonal field of view (DFOV) of imaging lens 2 is 18.435°. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 3A In the aberration diagram of the astigmatism of imaging lens 2 shown, the aberrations on the tangential surface at a wavelength of 550 nm are shown as solid lines, and the aberrations on the sagittal surface are shown as dashed lines. The tangential surface is the plane that contains the principal ray passing through imaging lens 2 and the optical axis of imaging lens 2. The sagittal surface is the plane that contains the principal ray passing through imaging lens 2 and is perpendicular to the tangential surface.

[0149] Figure 3B An aberration diagram of spherical aberration with the imaging plane as the reference is shown, where the horizontal axis represents image height and the vertical axis represents aberration magnitude. Figure 3B This shows the case where "aperture number Fno=3.552". In the case of... Figure 3B In the aberration diagram of the optical system of the lens group 21 shown, the aberration at a wavelength of 650 nm is shown as a dotted line, the aberration at a wavelength of 555 nm is shown as a solid line, and the aberration at a wavelength of 470 nm is shown as a dashed line.

[0150] Figure 3C An aberration diagram showing distortion aberrations relative to the imaging plane is presented, with the horizontal axis representing image height and the vertical axis representing aberration magnitude. Figure 3C This illustrates the case where the maximum image height is achieved when the diagonal field of view (DFOV) of imaging lens 2 is 18.435°. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 3C In the aberration diagram of the imaging lens 2 shown, the aberration at a wavelength of 550 nm is shown as a solid line.

[0151] Figure 3D An aberration diagram of chromatic aberration with magnification relative to the imaging plane is shown, where the horizontal axis represents image height and the vertical axis represents aberration magnitude. Figure 3D This illustrates the case where the maximum image height is achieved when the diagonal field of view (DFOV) of imaging lens 2 is 18.435°. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 3D In the aberration diagram of the magnification chromatic aberration of the imaging lens 2 shown, the aberration on the sagittal plane at a wavelength of 550 nm is shown as a solid line, and the aberration on the tangential plane is shown as a dashed line.

[0152] from Figure 3A , Figure 3B , Figure 3C and Figure 3D It can be seen that various aberrations have been appropriately adjusted. Furthermore, in cases such as Figure 1 In the exemplary structure of the imaging lens 1 shown, P_margin is 0.378 mm as shown in Table 3, based on the settings in Tables 1 to 4. As described above, since the conditional expression "P_margin = PL_1 - PL_2' > 0" is also satisfied, and as shown in Table 3... Figure 1 As shown in the optical path, "P_margin>0" holds true, therefore the structure can be fabricated and the five-reflection configuration can be realized.

[0153] Example 2

[0154] Example 2 is in Figure 4 The exemplary structure of the imaging lens 2 shown is an example of a five-element lens group 21 with a 35mm equivalent focal length of 136mm and an aperture of f / 4.0 achieved by a 1 / 2-inch sensor. Figure 4 This is a schematic diagram illustrating the structure of the imaging lens 2 in Example 2. For example... Figure 4 As shown, the imaging lens 2 includes a five-element lens group 21. Figure 4 The imaging lens 2 shown includes an aperture stop 11, a lens group 21, and a reflective light guide element 31. The light rays from the object side pass through the aperture stop 11, the lens group 21, and the reflective light guide element 31 in sequence before hitting the infrared filter 41.

[0155] Tables 5 to 8 are for example Figure 4 The table summarizes the optical parameters of the imaging lens 2 shown. Figure 5A , Figure 5B , Figure 5C and Figure 5D It is based on the aberration diagram of imaging lens 2 in Example 2.

[0156]

[0157]

[0158]

[0159]

[0160] from Figure 5A , Figure 5B , Figure 5C and Figure 5D It can be seen that all aberrations have been appropriately adjusted. Furthermore, when the imaging lens 2 is set using the settings in Tables 5 to 8, P_margin is 0.657 mm, as shown in Table 7. As mentioned above, since the condition "P_margin = PL_1 - PL_2' > 0" is also satisfied, and as shown in Table 7... Figure 4 As shown in the optical path, "P_margin > 0" holds true, therefore the five-piece structure can be fabricated, and the five-reflection configuration can be realized.

[0161] Example 3

[0162] Example 3 is in Figure 6In the exemplary structure of the imaging lens 3 shown, an example is a four-element lens group 22 with a 35mm equivalent focal length of 129mm and an aperture of f / 4.0 achieved by a 1 / 2-inch sensor. Figure 6 This is a schematic diagram illustrating the structure of imaging lens 3 in Example 3. For example... Figure 6 As shown, the imaging lens 3 includes a four-element lens group 22. Figure 6 The imaging lens 3 shown includes an aperture stop 12, a lens group 22, and a reflective light guide element 32. Light from the object side passes sequentially through the aperture stop 12, the lens group 22, and the reflective light guide element 32 before reaching the infrared filter 42.

[0163] Tables 9 to 12 are for example Figure 6 The table summarizes the optical parameters of the imaging lens 3 shown. Figure 7A , Figure 7B , Figure 7C and Figure 7D Here is the aberration diagram of the imaging lens 3 according to Example 3.

[0164]

[0165]

[0166]

[0167]

[0168] from Figure 7A , Figure 7B , Figure 7C and Figure 7D It can be seen that all aberrations have been appropriately adjusted. Furthermore, when the imaging lens 3 is set using the settings in Tables 9 to 12, P_margin is 4.470 mm, as shown in Table 11. As mentioned above, since the condition "P_margin = PL_1 - PL_2' > 0" is also satisfied, and as shown in Table 11... Figure 6 As can be seen from the optical path shown, the condition "P_margin > 0" is satisfied, therefore the structure can be fabricated and the five-reflection configuration can be realized.

[0169] Methods to reduce or cut off unnecessary light in reflective light guide elements

[0170] Next, as Figure 6 Taking the imaging lens 3 shown as an example, we will explain how to reduce or cut off unnecessary light rays when applying a five-fold reflection structure. First, we will explain how to cut off ghost light, which is an unnecessary light ray.

[0171] Figure 8 yes Figure 6The diagram shows the optical paths of the effective light rays and the ghost light rays in the imaging lens 3. The optical path of the effective light rays represents the light ray path required to generate an image of the object. Figure 8 The image beam B is shown superimposed on the beam paths of the principal ray, lower ray, and upper ray. Figure 8 In the diagram, the light path of ghost beam B is represented by a solid diagonal line.

[0172] In such Figure 8 In the reflective light guide element 32 with a five-fold reflection structure shown, until the incident light from the lens group 12 exits towards the infrared filter 42, the ghost image light B passes through a similar range to the effective light path at a different angle. Therefore, it is difficult to distinguish between the space through which only the effective light passes and the space through which only the ghost image light B passes. Consequently, it is not possible to cut off the ghost image light B by dividing the reflective light guide element into a portion through which only the ghost image light B passes and applying a light-blocking ink or setting grooves; this method is only suitable for cases with a small number of reflections.

[0173] Figure 9 This is based on an example of how to cut off ghost light B. For example... Figure 9 The imaging lens 4 shown is for, as Figure 8 An example of an imaging lens 3 shown with an air layer configured to cut off the ghost image light B. Because... Figure 9 The structure shown has two air layers, so in the following description, the reflective light guide element 32 is divided into three parts to provide two air layers, but the reflective light guide element 32 is not limited to being divided into three parts.

[0174] The division refers to dividing the same reflective light guide element 30 by setting an air layer medium with a very small width, rather than separating it into multiple different reflective light guide elements.

[0175] like Figure 9 As shown, in the reflective light guide element 33 of the imaging lens 4, in the light path from the lens group 23 into the reflective light guide element 33, with the lens optical axis of the lens group 23 as a reference, a first air layer 1001 and a second air layer 1002 are set in a diagonal direction. Figure 9 The aperture 13, lens group 23, infrared filter 43, and imaging element 53 shown correspond to, as follows: Figure 8 The structure of the aperture 12, lens group 22, infrared filter 42 and imaging element 52 shown is illustrated.

[0176] like Figure 9 The reflective light guide element 33 shown herein, by means of, as Figure 8 The reflective light guide element 32 with a five-fold reflection structure shown is divided into three parts, with a first air layer 1001 set at the first dividing point and a second air layer 1002 set at the second dividing point.

[0177] In such Figure 9 In the reflected light guide element 33 shown, such as Figure 9 As shown by the dashed line, the straight line extending from the first air layer 1001 and the straight line extending from the second air layer 1002 are diagonally divided and intersect on one side of the first plane where the incident surface of the reflective light guide element 33 is located.

[0178] like Figure 9 The reflective light guide element 33 shown is an optical system that divides the light rays entering the reflective light guide element 33 from the lens optical axis of the lens group 23 into three parts at an angle of 90°±30°. In other words, the first air layer 1001 and the second air layer 1002 are respectively positioned at an angle of 90°±30° to the light rays entering the reflective light guide element 33 from the lens optical axis of the lens group 23.

[0179] It should be noted that, in cases such as Figure 9 In the example, the first air layer 1001 and the second air layer 1002 are set by division. However, the first air layer 1001 and the second air layer 1002 can also be formed by setting grooves or the like in the division direction of the reflective light guide element 33.

[0180] Figure 10 In such Figure 9 The schematic diagram shown illustrates the principle of cutting off the ghost image light B from the effective light in the imaging lens 4. Figure 10 The beam paths of the principal ray, lower ray, and upper ray are shown, as well as those superimposed on... Figure 9 The optical path of the ghost image beam B on the imaging lens 4 is shown. Figure 9 In the diagram, the light path of ghost beam B is represented by a solid diagonal line.

[0181] In such Figure 10 In the structure of the imaging lens 4 shown, inside the reflective light guide element 33, the incident angle of the effective light when it strikes the boundary surface of the first air layer 1001, which has a different medium, is small. Furthermore, the incident angle of the effective light when it strikes the boundary surface of the second air layer 1002, which has a different medium, is also small. Therefore, the effective light can pass through the first air layer 1001 and the second air layer 1002, and travel along the boundary surface of the second air layer 1002, which has a different medium. Figure 8 A similar light path is shown to reach the photosensitive surface.

[0182] Conversely, in the ray of ghost image B, there are some rays whose incident angles satisfy the condition of total internal reflection when they are incident on the boundary surface of the first air layer 1001, which has a different medium. Figure 10Arrows q1 and q2 shown indicate the incident and reflection directions of the ghost image light B incident at an angle of total internal reflection in the first air layer 1001, respectively. As described above, in the light rays of the ghost image light B, those rays incident on the first air layer 1001 at an angle of total internal reflection are reflected and cut off from the direction of the photosensitive surface.

[0183] Furthermore, the remaining portion or all of the light rays in the ghost beam B will also be cut off due to total internal reflection when they are incident on the boundary surface of the second air layer 1002, which has a different medium. Figure 10 Arrows q3 and q4 shown indicate the incident and reflection directions of the ghost image light B that undergoes total internal reflection on the first plane, respectively. These ghost image light rays B that undergo total internal reflection on the first plane will then strike the second air layer 1002. Figure 10 Arrows q4 and q5, as shown, indicate the incident and reflection directions of light rays incident at a total internal reflection angle when the ghost image light is incident on the boundary surface of the second air layer 1002, which has a different medium. As described above, it is precisely because of the presence of the second air layer 1002 that the remaining light rays in the ghost image light B are cut off by reflection.

[0184] Therefore, because the ghost image light B is cut off by the first air layer 1001 and the second air layer 1002, the ghost image light cannot reach the photosensitive surface.

[0185] It should be noted that the medium here is air, because the interiors of both the first air layer 1001 and the second air layer 1002 are filled with air. Although the first and second media are described as air in the above description, the first and second media are not limited to air.

[0186] When the refractive indices of the first and second media are less than the refractive index of the reflective light guide element 33, and the first and second media are diagonally positioned relative to the optical axis of the lens, it is sufficient that the refractive index of the media is sufficient to cause total internal reflection of a portion of the target light rays in the transmitted light. Since the ghost light B is included in the transmitted light, the purpose of positioning the first and second media diagonally relative to the optical axis of the lens is to allow the ghost light B to enter the transmission area at an incident angle different from that of the effective light rays.

[0187] Furthermore, the first and second media should be media with a refractive index sufficient to cause total internal reflection of the ghost image B at the expected incident angle. The refractive index sufficient to cause total internal reflection of the ghost image B at the expected incident angle refers to a certain refractive index difference between the media and the media of the reflective light guide element 33, a difference that ensures total internal reflection at the expected incident angle.

[0188] In terms of materials, such as Figure 10In the structure shown, for example, the interior of the first air layer 1001 can be made of a glass material with a specific refractive index to ensure total internal reflection of light in the directions indicated by arrows q1 and q2. Similarly, the interior of the second air layer 1002 can also be made of a glass material with a specific refractive index to ensure total internal reflection of light in the directions indicated by arrows q4 and q5. Of course, the interiors of the first air layer 1001 and the second air layer 1002 can also be filled with media other than glass.

[0189] Furthermore, even if the number of reflections of the reflective light guide element is greater than five, a medium can be placed inside the reflective light guide element in a similar manner as described above. This medium can both allow effective light rays, such as image light, to pass through and cut off the ghost image light B at the angle that causes total internal reflection.

[0190] Example 4

[0191] Example 4 is in Figure 9 In the exemplary structure of the imaging lens 3 shown, an example is a four-element lens group 23 with a 35mm equivalent focal length of 131mm and an aperture of f / 4.0 achieved by a 1 / 2-inch sensor.

[0192] Tables 13 to 16 are for example Figure 9 The table summarizes the optical parameters of the exemplary configuration of the imaging lens 4 shown. Figure 11 yes Figure 9 A schematic diagram of another display form of the imaging lens 4 shown. Figure 11 Using a linearized light path representation of the unreflected light path, the first air layer 1001 and the second air layer 1002 in the first air layer of the three-part optical system (prisms 33a, 33b, 33c and the reflective light guide element 33 of the imaging lens 4) are shown, arranged as follows: Figure 9 The imaging lens 4 shown.

[0193] Figure 12A , Figure 12B , Figure 12C and Figure 12D It is based on the aberration diagram of imaging lens 4 in Example 4.

[0194]

[0195] In Table 13, the data for "Surface Number" from "11" to "15" correspond to the data for the reflective light guide element 33. Specifically, "Surface Number" "11" corresponds to the data for prism 33a, and "12" corresponds to the data for the prism air gap, i.e., the first air layer 1001. Furthermore, "Surface Number" "13" corresponds to the data for prism 33b, and "14" corresponds to the data for the prism air gap, i.e., the second air layer 1002. Additionally, "Surface Number" "15" corresponds to the data for prism 33c.

[0196]

[0197]

[0198]

[0199] from Figure 12A , Figure 12B , Figure 12C and Figure 12D It can be seen that all aberrations have been appropriately adjusted. Furthermore, when the imaging lens 4 is configured according to Tables 13 to 16, P_margin is 0.948 mm, as shown in Table 15. As mentioned above, since the condition "P_margin = PL_1 - PL_2' > 0" is also satisfied, this structure can be fabricated, and the five-reflection configuration can be achieved.

[0200] Other optical functional components as reflective light guide elements

[0201] The following section will describe various optical functional components that can be used to guide effective light to a photosensitive surface.

[0202] Figure 13 This is a schematic diagram of an optical functional component that can be used in a reflective light guide element, based on an example. Figure 13 The imaging lens 5 shown is adopted Figure 9 The structure of imaging lens 4 shown is an example lens. Similar to... Figure 10 , Figure 13 The imaging lens 5 shown illustrates the optical path superimposed on the imaging lens.

[0203] Figure 13 The aperture 14, lens group 24, infrared filter 44, and imaging element 54 of the imaging lens 5 shown correspond to, respectively, the following: Figure 9 The aperture 13, lens group 23, infrared filter 43, and imaging element 53 are shown. Figure 13 The reflected light guide element 34 shown is for... Figure 9 The reflective light guide element 33 shown is an example of an optical functional component.

[0204] Figure 13The aluminum reflective coating 2000, black absorbing coating 3000, light-shielding filter 4000, and dichroic reflector 5000 shown are examples of optical functional components. These optical functional components can be selectively used depending on the shape of the reflective light guide element, etc.

[0205] exist Figure 13 In the reflected light guide element 34 shown, an aluminum reflective coating 2000 is applied to the first inclined surface 343. Furthermore, a dichroic reflector 5000 is disposed on the second inclined surface 346. The dichroic reflector 5000 refers to an aluminum-enhanced reflective film having an incident-dependent coating layer, which is an optical functional component whose reflectivity changes according to the incident angle of light.

[0206] Furthermore, a black absorbing coating 3000 is applied around the aluminum reflective coating 2000, which acts like a mask to cut off unwanted light. Additionally, a black absorbing coating 3000 is also applied around the dichroic reflector 5000, which also acts like a mask to cut off unwanted light.

[0207] The black absorbing coating 3000 is an example of a low-reflection black absorber that can be appropriately applied to a portion of the surface of the reflective light guide element 34.

[0208] It should be noted that the coating can be formed by conventional methods such as vacuum evaporation and sputtering, and these methods can be performed in a suitable manner.

[0209] Furthermore, light-shielding filters 4000 are inserted into the respective ends of the first air layer 1001 and the second air layer 1002 to cut off unnecessary light. Other low-reflection black absorbers can also be provided by means of coating or other methods, and are not limited to the insertion of light-shielding filters 4000.

[0210] Figure 14A This is a schematic diagram of the reflectivity wavelength characteristics of an example low-reflectivity black absorbing film. Figure 14A An example of a low-reflectivity black absorbing film shown is a black absorbing coating, with reflectivity wavelength characteristics at incident angles of -10°, 0°, and 10° relative to a 45° reference. Figure 14A The reflectivity of the absorbing coating shown is close to 0% across almost the entire visible light region. Therefore, by using this black absorbing coating, unwanted light can be reduced.

[0211] Figure 14B This is a schematic diagram of a black absorbing coating 3000 applied around an aluminum-reinforced reflective film, based on an example. Figure 14BThe black absorbing coating 3000 shown is formed around the aluminum-enhanced reflective film of the aluminum reflective coating 2000 by depositing a low-reflectivity black absorbing film material off-axis. A similar method is used when the black absorbing coating 3000 is formed around the dichroic reflector 5000.

[0212] As described above, by offsetting the optical axis and depositing a low-reflectivity black absorption film, it is possible to achieve... Figure 14B The effective ray a11 shown is reflected as ray a12, and the ray b1 incident at a position more than a certain distance from the optical axis reaches the surface used to cut off stray light.

[0213] Figure 15 This is a schematic diagram illustrating the wavelength-dependent reflectivity of an incident-dependent film. Figure 15 In order to illustrate the difference in wavelength characteristics as the incident angle changes, a dashed line shows an example of wavelength characteristics when the incident angle is 30°, and a solid line shows an example of wavelength characteristics when the incident angle is 60°.

[0214] like Figure 15 As shown, in the case of light rays with an incident angle of 30° and those with an incident angle of 60°, the red component in the light ray with an incident angle of 60° is weakened. Therefore, when a dichroic reflector 5000 is set, the human eye finds it difficult to perceive ghost light because the red light decreases with the change of the incident angle.

[0215] As described above, according to the first embodiment, the same reflective light guide element can achieve five or more reflections. Furthermore, since it is designed to perform five or more reflections within the same reflective light guide element, by vertically aligning the imaging element with the lens optical axis, it can be applied to a thinner imaging device body.

[0216] Second Embodiment

[0217] The structure of the imaging device according to the second embodiment will be described below. It should be noted that the imaging device is described below using a smartphone as an example, but the imaging device is not limited to smartphones. If it is an imaging device, it can also be applied to other forms, such as tablet terminals.

[0218] Figure 16 This is a schematic diagram illustrating the structure of an example of an imaging apparatus according to the second embodiment. Figure 16 An example of the external structure of a smartphone 200, which serves as an imaging device according to a second embodiment, is shown.

[0219] Figure 16The right and front views of the smartphone are shown. The smartphone 200 includes a camera unit 201 and a slim body 202. As shown in its right view, the example smartphone 200 adopts a slim design, with the camera unit 201 having a thickness of 13.5mm and the body 202 having a thickness of 9.1mm.

[0220] Figure 17 This is a structural diagram of a camera based on an example camera unit 201. Figure 17 The camera unit 201 shown has two cameras, including a wide-angle camera and a telephoto camera. In the lens housings of these two cameras, the lens housing 211 of the telephoto camera is a lens housing with an imaging lens employing a five-fold reflection structure.

[0221] Figure 18 This is a schematic diagram of an example foldable smartphone. Because the imaging lens employing a five-fold reflection structure can reduce the thickness of the reflective light guide element, this imaging lens is also suitable for foldable smartphones with a thinner body 202. As an example, Figure 18 The foldable smartphone shown has two cameras: one of the two lens housings 212 is a wide-angle camera, and the other is a telephoto camera.

[0222] Figure 19 This is a schematic diagram of the installation of an example imaging lens. Figure 19 The imaging lens structure shown is an example of an imaging lens employing a five-fold reflection structure. This imaging lens includes an aperture stop 15, a lens group 25, and a reflective light guide element 35, with the first plane of the reflective light guide element 35 facing the infrared filter 45 and the imaging element 55. Light from the object side passes sequentially through the aperture stop 15, the lens group 25, and the reflective light guide element 35 before reaching the infrared filter 45.

[0223] Figure 19 The camera unit 201 shown protrudes outward from the body 202. Since a portion of the lens group 25 protrudes from the body 202, the camera unit 201 also protrudes from the body 202. A VCM or similar device for driving the lens group 25 can be provided in the camera unit 201.

[0224] In addition, to achieve camera image stabilization correction, a camera image stabilization correction function can be added by moving the lens group 25 or the imaging element 55 through an appropriate driver.

[0225] Part of the lens group 25 is housed inside the body 202. A depth space for accommodating the lens is formed between the object-side surface (front) of the body 202 and the reflective light guide element 35, along the thickness direction of the body 202. An infrared filter 45 and an imaging element 55 are disposed within this space. This arrangement allows for a reduction in the thickness of both the camera unit 201 and the body 202.

[0226] It should be noted that the shapes of the reflective light guide elements shown in the first embodiment, second embodiment, etc., are merely examples. For instance, the incident surface and the exit surface of the reflective light guide element can be planar, but these surfaces are not limited to planar surfaces. One or both of the incident surface and the exit surface can be non-planar. For example, these surfaces can be inclined surfaces or other shapes. In this case, the infrared filter and the imaging element can be configured according to the direction of the light emitted from the exit surface.

[0227] As described above, the imaging device according to the second embodiment can achieve a thinner body. Furthermore, by vertically aligning the imaging element with the lens optical axis, the body thickness can be further reduced.

[0228] Explanation of the structure where the P_margin of the imaging lens is negative

[0229] Figure 20 This is a schematic diagram of an imaging lens with a negative P_margin, based on an example. Figure 20 The imaging lens shown includes an aperture stop 16, a lens group 26, and a reflective light guide element 36. Light from the object side passes sequentially through the aperture stop 16, the lens group 26, and the reflective light guide element 36 before reaching the infrared filter 46. Figure 20 The optical settings of the imaging lenses shown are represented by Tables 17 to 20.

[0230]

[0231]

[0232]

[0233]

[0234] Use such as Figure 20 When the optical settings are shown, in Figure 20 In the third reflection of the light path, the margin essentially disappears, and the value of P_margin becomes negative. In Table 19, P_margin is -0.020mm, which is a negative value.

[0235] As mentioned above, it may become difficult to fabricate an imaging lens with a five-fold reflection structure if the conditional expression “P_margin = PL_1 - PL_2’ > 0” is not satisfied.

[0236] Comparison with periscope structure effects

[0237] The following section will explain the differences in performance compared to periscope smartphones.

[0238] Figure 21 This is a schematic diagram of a smartphone with a periscope lens installed, based on an example. The periscope lens unit includes a single-reflection prism 60 and a lens group 70. The periscope lens unit is disposed within the smartphone, and the optical axis of the lens group 70 is perpendicular to the thickness direction of the smartphone. In other words, in the periscope structure, parameters such as the height of the prism and the lens diameter of the lens unit affect the thickness of the smartphone.

[0239] For example, for a conventional periscope telephoto lens with a 4mm (1 / 2 inch) high sensor, a 35mm equivalent focal length of 131mm, and an aperture of f / 3.5, the aperture diameter is φ7.1. Since the prism height is approximately 8.3mm and the lens module thickness is approximately 9.8mm, this lens cannot be fitted into the slim smartphone body 202, which is only 9.1mm thick. Otherwise, the layout area of ​​the internal circuit board of the smartphone would be significantly limited, resulting in a significant increase in the overall size of the device.

[0240] On the other hand, compared with periscope lens units, the structure provided by the present invention has advantages in the thickness and length of the optical unit, which can increase the space for the internal circuit board and battery of the smartphone.

[0241] It should be noted that the smartphone dimensions and other optical settings shown in the accompanying drawings are merely examples, and therefore the values ​​are not limited to these values ​​and can be appropriately changed as needed without departing from the spirit of the invention.

[0242] Although certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of protection of the invention. In fact, the novel embodiments described herein can be implemented in various other forms. Furthermore, various omissions, substitutions, and formal changes can be made to the embodiments without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover all forms or modifications falling within the scope and spirit of the invention.

[0243] [Explanation of Attached Images and Symbols]

[0244] 1, 2, 3, 4, 5: Imaging lenses

[0245] 10, 11, 12, 13, 14: Aperture

[0246] 20, 21, 22, 23, 24: Lens groups

[0247] 30, 31, 32, 33, 34: Reflective light guide elements

[0248] 40, 41, 42, 43, 44: Infrared filters

[0249] 50, 52, 53, 54, 55: Imaging elements

[0250] 200: Smartphones

[0251] 201: Camera Department

[0252] 202: Fuselage

[0253] 211, 212: Lens housing

[0254] 301: Incident surface

[0255] 302: Exit surface

[0256] 303: First inclined plane

[0257] 304: First plane

[0258] 305: Second plane

[0259] 306: Second slope

[0260] L1: First lens

[0261] L2: Second lens

[0262] L3: Third lens

[0263] L4: Fourth Lens

[0264] L5: Fifth Lens

[0265] 1001: First air layer

[0266] 1002: Second air layer

[0267] 2000: Aluminum Reflective Coating

[0268] 3000: Black light-absorbing coating

[0269] 4000: Light-blocking filter

[0270] 5000: Dichroic mirror

[0271] 33a, 33b, 33c: Prisms in an optical system consisting of three parts.

Claims

1. An imaging lens characterized by, In order from the light transmission order of the light from the object side, the imaging lens includes: a diaphragm; a lens group including at least one lens having positive refractive power and at least one lens having negative refractive power; and a reflection light guide element for guiding the light to the imaging element, wherein the reflection light guide element has a plurality of reflection surfaces, and the light path is reflected n times on the plurality of reflection surfaces, n being an integer of 5 or more.

2. The imaging lens of claim 1, wherein, In the lens group, the first lens through which the light from the object side first passes is a lens having positive refractive power, and the final lens through which the light from the object side finally passes is a lens having negative refractive power.

3. The imaging lens of claim 1 or 2, wherein, The reflection light guide element guides the light from the lens group and guides the light which has been reflected n times in the reflection light guide element through the plurality of reflection surfaces to the light-receiving surface of the imaging element provided on the side of the reflection surface on which the n-1th reflection is performed.

4. The imaging lens of any of claims 1-3, wherein, The condition "4 < EFL / dd" is satisfied, where EFL is the focal length of the entire lens, and dd is the half size of the diagonal direction of the light-receiving surface of the imaging element.

5. The imaging lens of any of claims 1 to 4, wherein, The condition "EPD / PL < 0.24" is satisfied, where EPD is the exit pupil diameter, and PL is the optical length of the light path of the light passing through the reflection light guide element along the lens optical axis of the lens group.

6. The imaging lens of any of claims 1-5, wherein, In the plurality of light rays of the light beam which converges at a position away from the lens optical axis of the lens group to be imaged on the light-receiving surface of the imaging element, for the light path of a first light ray which is a light ray passing through the side of the lens group close to the imaging element, a margin is provided between the position at which the n-2th reflection is performed in the reflection light guide element and the surface at which the nth reflection is performed.

7. The imaging lens according to claim 6, wherein when the first light ray is incident on the reflection light guide element parallel to the lens optical axis of the lens group and is reflected n times in the reflection light guide element, n being an integer of 5 or more, the following conditions are satisfied: AREA1 = (EPD / 2) / LTL * (LTL - L); PL_2 = AREA1 + P_t*TAN(θ*2)*(n-4) + (AREA1*TANθ + Pref_d)*TAN(2*θ); PL_1 = P_od - (P_t - Pref_d) / TANθ; where EPD is the exit pupil diameter, LTL is the total lens length, L is the distance from the lens vertex of the first lens of the lens group to the reflection light guide element, P_t is the thickness of the reflection light guide element in the direction of the lens optical axis, Pref_d is the distance from the incidence surface of the reflection light guide element on which the light from the lens group is incident to the intersection point of the lens optical axis and the first inclined surface at which the first reflection is performed, and θ is the angle between the incidence surface of the reflection light guide element and the inclined surface of the first inclined surface; when the incidence angle of the first light ray with respect to the lens optical axis has a deviation of 1° and the first light ray is reflected n times in the reflection light guide element, n being an integer of 5 or more, the following conditions are satisfied: AREA1 = (EPD / 2) / LTL * (LTL - L); PL_2' = AREA1 + P_t*TAN((θ+1)*2)*(n-4) + (AREA1*TAN(θ+1) + Pref_d)*TAN(2*(θ+1)); and the margin is "PL_1 - PL_2'" and satisfies: PL_1 - PL_2' > 0.

8. The imaging lens of any of claims 1-7, wherein, satisfies "f_F > 0", where f_F is the focal length of the remaining lenses in the lens group excluding the final lens and the lens preceding the final lens in the order of transmission of light from the object side.

9. The imaging lens of any of claims 1-8, wherein, satisfies "f_B2 < 0", where f_B2 is the focal length of the final lens and the lens preceding the final lens in the order of transmission of light from the object side in the lens group.

10. The imaging lens of any of claims 1-9, wherein, satisfies "-1.5 < f_B2 / f_F < -0.5".

11. The imaging lens of any of claims 1-10, wherein, satisfies "L > P_t".

12. The imaging lens of any of claims 1-11, wherein, satisfies "EPD / Pref_d <3.25".

13. The imaging lens of any of claims 1-12, wherein, the reflective light guide element is provided with a first medium and a second medium on the path of light rays from the lens group, the refractive indices of the first medium and the second medium being different from the refractive index of the medium of the reflective light guide element; and the first medium and the second medium are diagonally arranged with respect to the lens optical axis of the lens group, the angle of the diagonal being such that total reflection of the partial light rays occurs, and the extension lines of the first medium and the second medium intersect each other.

14. The imaging lens of claim 13, wherein, the reflective light guide element is provided with a low-reflection black absorber at at least one end of the first medium or at least one end of the second medium to reduce or cut off the passage of partial light rays.

15. The imaging lens of any of claims 1-14, wherein, the reflective light guide element is an optical system that divides the light rays passing inside the reflective light guide element and propagating along the lens optical axis of the lens group at an angle of 90°±30°.

16. The imaging lens of any of claims 1-15, wherein, at least one of the plurality of reflecting surfaces is a surface forming the shape of the reflective light guide element and is arranged at an angle such that total reflection of the incident light occurs.

17. The imaging lens of any of claims 1-16, wherein, the reflective light guide element has reflecting surfaces partially formed of a reflecting material.

18. The imaging lens of any of claims 1-17, wherein, the reflecting surfaces of the reflective light guide element have a dichroic mirror whose reflectivity varies with the incident angle of the light rays.

19. The imaging lens of any of claims 1-18, wherein, a low-reflection black absorber is provided on part of the surface of the reflective light guide element to reduce or cut off the reflection of partial light rays.

20. An imaging device, comprising: comprises: the imaging lens according to any one of claims 1 to 19; and the imaging element for imaging an object through the imaging lens.

Images