JP2019020505A - Lens unit - Google Patents

Abstract

To provide a lens unit that, when a temperature environment repeatedly changes during the use of an on-vehicle camera, can reliably maintain optical performance compared with the prior art.SOLUTION: A lens unit 10 comprises: a plurality of lenses L1 to L6 including a positive displacement lens (fifth lens L5) having positive eccentricity sensitivity in which when the lens becomes eccentric in a predetermined direction with respect to the optical axis Z1 of the entire system, an image forming position is displaced in the predetermined direction, and a negative displacement lens (fourth lens L4) having negative eccentricity sensitivity in which when the lens becomes eccentric in the predetermined direction with respect to the optical axis Z1 of the entire system, an image forming position is displaced in a direction opposite to the predetermined direction; and a resin ring 16 that is made of resin, holds the adjacent positive displacement lens and negative displacement lens in the plurality of lenses, and fixes the direction and amount of eccentricity of the positive displacement lens and negative displacement lens with respect to the optical axis Z1 of the entire system.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lens unit in which a plurality of lenses are combined.

  In recent years, surveillance cameras and in-vehicle cameras (hereinafter referred to as in-vehicle cameras) have become widespread. Car-mounted cameras are used in harsh environments such as large temperature changes. For this reason, a lens used for a vehicle-mounted camera or the like is required to have good durability against the environment or a change in the environment, and to maintain optical performance even when there is a temperature change or the like. For example, a lens used for an in-vehicle camera is provided as a lens unit in which a glass lens press-fitted into a lens frame is housed in a lens barrel (Patent Document 1).

JP 2014-170123 A

  A lens unit such as an in-vehicle camera may have a fixed relative positional relationship, such as an interval between a plurality of lenses included in the lens unit. This is because, if the relative positional relationship between the lenses is fixed as described above, almost constant optical performance can be maintained regardless of the environmental temperature.

  However, even if the distance between the lenses is fixed at the beginning of manufacturing the lens unit as described above, the relative positional relationship of the lenses changes while the environmental temperature repeatedly changes during use of the on-vehicle camera or the like. May end up. As a result, the optical performance may change over the long term.

  An object of the present invention is to provide a lens unit that can suppress a change in optical performance even when a temperature environment repeatedly changes during use of an in-vehicle camera or the like, and can maintain the optical performance more reliably than in the past.

  The lens unit of the present invention includes a positive displacement lens having a positive decentering sensitivity in which an imaging position is displaced in a predetermined direction when decentered in a predetermined direction with respect to the optical axis of the entire system, and an optical axis of the entire system. A plurality of lenses including a negative displacement lens having a negative eccentricity sensitivity in which an imaging position is displaced in a direction opposite to a predetermined direction when decentered in a predetermined direction, and made of resin, and among the plurality of lenses And a resin ring that holds the positive displacement lens and the negative displacement lens adjacent to each other and fixes the direction and amount of eccentricity of the positive displacement lens and the negative displacement lens with respect to the optical axis of the entire system.

  The inner diameter of the lens holding portion of the resin ring is preferably smaller than the outer diameters of the positive displacement lens and the negative displacement lens to be held.

  It is preferable that the resin ring has a plurality of protrusions protruding toward the inner peripheral side.

  The resin ring has an interval along the direction of the optical axis of the entire system between the positive displacement lens or negative displacement lens held by the resin ring and the positive displacement lens or other lens adjacent to the negative displacement lens held by the resin ring. It is preferable that the spacer be maintained.

  The resin ring preferably holds one positive displacement lens and one negative displacement lens.

  It is preferable that the positive displacement lens held by the resin ring has the highest eccentric sensitivity among the plurality of lenses, and the negative displacement lens held by the resin ring preferably has the lowest eccentric sensitivity among the plurality of lenses.

  The positive displacement lens and the negative displacement lens held by the resin ring are preferably a combination of lenses having the closest diameters among a plurality of lenses.

  The positive displacement lens and the negative displacement lens held by the resin ring are a combination of a lens having the smallest diameter and a lens having the second smallest diameter among the plurality of lenses, or two of the smallest diameters among the plurality of lenses. A combination of lenses is preferred.

  When one lens out of a plurality of lenses is decentered by a certain amount in a certain direction, and when another lens is placed at a certain position, the amount of displacement of the imaging position due to the decentering of one lens is compared In addition, the positive displacement lens and the negative displacement lens held by the resin ring are a combination of a lens having the largest absolute value of the displacement amount and a lens having the second largest displacement amount among the plurality of lenses. Is preferred.

  As a plurality of lenses, in order from the object side, a first lens having negative power, a second lens having positive power, a third lens having positive power, and a fourth lens having negative power, It is preferable that a fifth lens having a positive power and a sixth lens having a positive power are provided, and the resin ring holds the fourth lens and the fifth lens.

  The lens unit of the present invention can maintain optical performance more reliably than before when the temperature environment repeatedly changes during use of an in-vehicle camera or the like.

It is sectional drawing of a lens unit. It is sectional drawing of a 4th lens, a 5th lens, and a resin ring. It is a front view of a resin ring. It is explanatory drawing which shows the change of the optical axis when the position of a 4th lens changes. It is explanatory drawing which shows the change of the optical axis when the position of a 4th lens changes. It is explanatory drawing which shows the change of the optical axis when the position of a 5th lens changes. It is explanatory drawing which shows the change of the optical axis when the position of a 5th lens changes. It is a graph which shows the relationship between the frequency | count of a thermal shock, and the variation | change_quantity of an optical axis. It is a graph which shows distribution of the variation | change_quantity of the optical axis after giving the thermal shock 500 times.

  As shown in FIG. 1, the lens unit 10 includes a lens barrel 11 made of metal (for example, aluminum (Al)) and a plurality of lenses housed in the lens barrel 11. The plurality of lenses included in the lens unit 10 are, for example, in order from the object side, a first lens L1 having negative power, a second lens L2 having positive power, and a third lens L3 having positive power. This is a six-lens configuration including a fourth lens L4 having negative power, a fifth lens L5 having positive power, and a sixth lens L6 having positive power. The plurality of lenses form a subject image on an imaging surface of an image sensor (not shown) connected to the image plane side of the lens unit 10. These lenses L1 to L6 are all made of glass.

  The lens unit 10 includes an arbitrary number of lenses other than the six-lens configuration including the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the sixth lens L6. In addition, a plurality of lenses having an arbitrary power configuration can be mounted. In the present embodiment, the lens unit 10 includes the six lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the sixth lens L6. Shall. The optical axis Z1 of the lens unit 10, that is, the optical axis Z1 of the entire system substantially coincides with the central axis of the lens barrel 11 at least when the lens unit 10 is assembled.

  The lens unit 10 includes an infrared cut filter 12, a presser ring 13, a spacer 14, a spacer 15, a resin ring 16, a presser ring 17, and a presser ring 18 in addition to the lenses L1 to L6. The infrared cut filter 12 removes or reduces the infrared component when the plurality of lenses form a subject image. The presser ring 13 is a metal (for example, aluminum (Al)), and is an annular pressing member that presses the front surface (object side surface) of the first lens L1 against the lens barrel 11. By pressing the front surface of the first lens L <b> 1 using the presser ring 13, the lens unit 10 stores the lenses L <b> 1 to L <b> 6 in the lens barrel 11.

  The spacer 14 is a metal (for example, aluminum (Al)), and is disposed between the second lens L2 and the third lens L3. The spacer 14 keeps the distance between the second lens L2 and the third lens L3 in the lens barrel 11. The spacer 15 is made of metal (for example, aluminum (Al)) and is disposed in the lens barrel 11 between the third lens L3 and the fourth lens L4. The spacer 15 keeps the distance between the third lens L3 and the fourth lens L4.

  The resin ring 16 is made of resin and is a lens frame that holds the adjacent fourth lens L4 and fifth lens L5. Further, as shown in FIG. 2, the lens holding portion 21 of the resin ring 16 contacts and holds the side surfaces of the fourth lens L4 and the fifth lens L5. Further, the inner diameter of the lens holding portion 21 is smaller than the outer diameters of the fourth lens L4 and the fifth lens L5 to be held. That is, the resin ring 16 is a lens frame that holds the press-fitted fourth lens L4 and fifth lens L5.

  More specifically, as shown in FIG. 3, the resin ring 16 has a plurality of protruding portions 22 that protrude toward the inner peripheral side. And the diameter Da of the resin ring 16 measured in the protrusion part 22 is smaller than the diameter D4 of the 4th lens L4 (Da <D4). The diameter D4 of the fourth lens L4 is not the diameter of the optical surface but the diameter including the flange when having a flange. Similarly, the diameter Da of the resin ring 16 measured at the protrusion 22 is smaller than the diameter D5 of the fifth lens L5 (Da <D5). The diameter D5 of the fifth lens L5 is a diameter including the flange when having a flange.

  The resin ring 16 also functions as a spacer that maintains a distance along the direction of the optical axis Z1 of the entire system between the lens held by the resin ring 16 and another lens adjacent to the lens held by the resin ring 16. For example, the resin ring 16 protrudes toward the sixth lens L6, and a position with respect to the lens barrel 11 is determined by contacting the positioning convex portion 11a in the lens barrel 11 in the vicinity of the tip. On the other hand, the sixth lens L6 is inserted into the lens barrel 11 from the side opposite to the resin ring 16 and comes into contact with the positioning convex portion 11a for positioning the resin ring 16, so that the position relative to the lens barrel 11 is determined. As a result, the resin ring 16 functions as a spacer that determines the relative positions of the fifth lens L5 and the sixth lens L6. In addition, by changing the length or shape of the resin ring 16, the resin ring 16 can be used as a spacer that determines the relative positions of the third lens L3 and the fourth lens L4.

  The presser ring 17 is a metal (for example, aluminum (Al)), and is an annular pressing member that presses the rear surface (image-side surface) of the sixth lens L6 against the lens barrel 11. By pressing the rear surface of the sixth lens L <b> 6 using the presser ring 17, the lens unit 10 stores the lenses L <b> 1 to L <b> 6 in the lens barrel 11. The presser ring 17 locks the infrared cut filter 12 from the sixth lens L6 at a certain position. The presser ring 18 is made of metal (for example, made of SUS), and is an annular presser member that holds the infrared cut filter 12 against the presser ring 17 and the lens barrel 11 by being fixed to the presser ring 17 with a screw, for example. The presser ring 18 holds the infrared cut filter 12 together with the presser ring 17.

  As described above, the lens unit 10 fixes the lenses L <b> 1 to L <b> 6 in the lens barrel 11. In the lens unit 10, the lenses L1 to L6 are glass lenses that are less expanded or contracted due to temperature changes than the resin. In the lens unit 10, except for the resin ring 16, the lens barrel 11, the presser ring 13, the spacer 14, the spacer 15, the presser ring 17, and the presser ring 18 are all made of metal. Therefore, changes in optical performance due to temperature changes are suppressed.

  The reason why the relative positions of the fourth lens L4 and the fifth lens L5 are fixed using the resin ring 16 is as follows.

  First, as shown in FIG. 4, among the lenses L1 to L6, the first lens L1, the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are fixed, and the fourth When the lens L4 is decentered in a predetermined direction (Y direction positive side in FIG. 4) with respect to the optical axis Z1 of the entire system, the optical axis Z1 of the entire system is inclined to the Y direction negative side. As a result, the imaging position is displaced to the Y direction negative side. Further, as shown in FIG. 5, the first lens L1, the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are fixed, and the fourth lens L4 is light of the entire system. When decentered to the Y direction negative side with respect to the axis Z1, the optical axis Z1 of the entire system is inclined to the Y direction positive side. As a result, the imaging position is displaced to the Y direction positive side. That is, in the lens unit 10 constituted by the lenses L1 to L6, when the fourth lens L4 is decentered in the predetermined direction with respect to the optical axis Z1 of the entire system, the imaging position is in the predetermined direction (the fourth lens L4 is A decentered direction) is a lens having “negative decentering sensitivity” that is displaced in the opposite direction (hereinafter referred to as “negative displacement lens”).

  Next, as shown in FIG. 6, among the lenses L1 to L6, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are fixed, and When the five lenses L5 are decentered in a predetermined direction (Y direction positive side in FIG. 6) with respect to the optical axis Z1 of the entire system, the optical axis Z1 of the entire system is inclined to the positive side of the Y direction. As a result, the imaging position is displaced to the Y direction positive side. Also, as shown in FIG. 7, among the lenses L1 to L6, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are fixed, and the fifth When the lens L5 is decentered to the Y direction negative side with respect to the entire system optical axis Z1, the entire system optical axis Z1 is inclined to the Y direction negative side. As a result, the imaging position is displaced to the Y direction negative side. That is, in the lens unit 10 constituted by the lenses L1 to L6, when the fifth lens L5 is decentered in the predetermined direction with respect to the optical axis Z1 of the entire system, the imaging position is in the predetermined direction (the fifth lens L5 is It is a lens (hereinafter referred to as a “positive displacement lens”) having a “positive eccentric sensitivity” that is displaced in the decentered downward direction).

  Therefore, if the fourth lens L4, which is a negative displacement lens, and the fifth lens L5, which is a positive displacement lens, are decentered by the same amount in the same direction (for example, the Y direction positive side or the Y direction negative side). The inclination of the optical axis Z1 of the entire system due to the eccentricity of the fourth lens L4 and the fifth lens L5 can be at least partially offset. As a result, the optical performance of the lens unit 10 can be maintained even when an external force is applied due to temperature change or vibration during use, and the fourth lens L4 and the fifth lens L5 are decentered. Therefore, in the lens unit 10, the resin ring 16 holds the fourth lens L4 that is a negative displacement lens and the fifth lens L5 that is a positive displacement lens, and is positive with the fourth lens L4 that is a negative displacement lens. The direction and amount of eccentricity with respect to the optical axis Z1 of the entire system of the fifth lens L5, which is a displacement lens, are fixed.

  Generally speaking, since the resin has a larger expansion or contraction due to a temperature change than a metal, using the resin ring 16 that is a resin lens frame is an optical performance of the lens unit 10 due to the temperature change. It is not advantageous to suppress changes in However, if the fourth lens L4, which is a negative displacement lens, and the fifth lens L5, which is a positive displacement lens, are fixed using a metal lens frame instead of the resin ring 16, it is more necessary than the case where the resin ring 16 is used. The clearance (clearance for inserting the lens into the lens frame) must be large. For this reason, when a metal lens frame is used, the decentering of the fourth lens L4, which is a negative displacement lens, and the fifth lens L5, which is a positive displacement lens, with respect to the optical axis Z1 of the entire system is less than when the resin ring 16 is used. Differences in direction and quantity are likely to occur. And the effect which maintains the optical performance of the lens unit 10 with respect to a temperature change reduces. Therefore, in the lens unit 10, the resin lens 16 is used to hold the fourth lens L4 that is a negative displacement lens and the fifth lens L5 that is a positive displacement lens, and the fourth lens that is a negative displacement lens. The direction and amount of decentering with respect to the optical axis Z1 of the entire system of L4 and the fifth lens L5 which is a positive displacement lens are fixed. If the resin ring 16 is used to fix the fourth lens L4, which is a negative displacement lens, and the fifth lens L5, which is a positive displacement lens, there is an advantage that the cost can be reduced compared to the case where a metal lens frame is used.

  When the lens unit includes a plurality of lenses including a positive displacement lens and a negative displacement lens, as shown by the lens unit 10, a positive displacement lens and a negative displacement lens that are adjacent to each other among the plurality of lenses using a resin ring. If the direction and amount of decentering with respect to the optical axis of the entire system of the positive displacement lens and the negative displacement lens are fixed, it is easy to maintain optical performance against temperature changes. In particular, it is suitable for a lens unit used for an in-vehicle camera or the like. That is, in the case of a lens unit used for an in-vehicle camera or the like, since the temperature change in the usage environment is large, even if the relative positions of the lenses L1 to L6 are substantially fixed as in the lens unit 10, When a large temperature change is applied, it is almost inevitable that the positional relationship between the lenses L1 to L6 changes. However, like the lens unit 10 described above, a resin ring is used to hold the adjacent positive displacement lens and negative displacement lens among a plurality of lenses, and the eccentricity of the positive displacement lens and the negative displacement lens with respect to the optical axis of the entire system. If the direction and amount are fixed, the optical performance can be maintained well even in a lens unit used for an in-vehicle camera or the like.

  For comparison, the lens unit 10 of the present invention and the lens unit of the comparative example that does not use the resin ring 16 are respectively manufactured, and a thermal shock test is performed assuming a large temperature environment change that the in-vehicle lens unit receives, The positional deviation of the optical axis Z1 due to the manufacturing error was measured. In the thermal shock test, the lens unit 10 of the present invention and the lens unit of the comparative example are exposed to an environment of −40 ° C. for 30 minutes and a process of exposing the lens unit 10 to an environment of 105 ° C. for 30 minutes (heat cycle). Thus, this one set of steps was regarded as one thermal shock. Further, in order to be positioned as an acceleration test, the amount of change (inclination angle) of the optical axis Z1 of the entire system is added each time a thermal shock is applied with reference to the optical axis Z1 after adding a thermal shock of 100 times or more and removing manufacturing errors. ) Was measured. Then, as shown in FIG. 8, the change amount of the optical axis Z1 of the lens unit 10 (solid line) of the present invention is less than 1.0 minute, but the change amount of the optical axis Z1 of the lens unit of the comparative example is 1. Over 5 minutes. As can be seen from this result, the lens unit 10 of the present invention is more stable against thermal shock or heat cycle than the lens unit of the comparative example.

  In addition, 30 lens units 10 of the present invention and 30 lens units of comparative examples were manufactured, respectively, and after applying thermal shock 500 times, the variation of the change amount of the optical axis Z1 was measured. Then, as shown in FIG. 9, the lens unit 10 of the present invention and the lens unit of the comparative example both differ in the amount of change in the optical axis Z1 for each individual. However, in the lens unit 10 of the present invention, the variation range of the optical axis Z1 is 0.1 to 0.9 (min), whereas the lens unit of the comparative example has a variation amount of the optical axis Z1. The range varied from 0.1 to 1.8 (min). Also from this result, it can be seen that the lens unit 10 of the present invention is more stable against thermal shock or heat cycle than the lens unit of the comparative example.

Table 1 shows lens data of the lens unit 10 in the embodiment. The lenses L1 to L6 constituting the lens unit 10 are all spherical lenses. Reference numeral “i” denotes a surface number “i” given in order from the object side surface of the first lens L1, a radius of curvature Ri (unit: mm), a surface interval Di, and a refractive index with respect to the d-line (wavelength 587.6 nm). n, Abbe number νd (= (nd−1) / (n _F −n _C ); n _F is the refractive index for the F-line (wavelength 486.1 nm), and n _C is the refractive index for the C-line (wavelength 656.3 nm). Is). The “aperture stop” is formed by the spacer 15, and the IRCF is the infrared cut filter 12. CG is a cover glass of an image sensor (not shown).

上記実施形態のレンズユニット１０は、第４レンズＬ４が負変位レンズであり、第５レンズＬ５が正変位レンズであるが、より具体的には、表２において、レンズＬ１〜Ｌ６のうち、特定の１つのレンズが所定方向（図４〜７におけるＹ方向）に１０μｍ偏心した場合における結像位置の変位量（単位：μｍ）を示す。結像位置の変位量は、図４〜７におけるＹ方向正側を「＋」とし、Ｙ方向負側を「−」としている。また、表２に示す結像位置の変位量（大きさ）は、一定の偏心量に対する結像位置の変化量という点で「感度（偏心感度）」の大きさということができる。

In the lens unit 10 of the above embodiment, the fourth lens L4 is a negative displacement lens and the fifth lens L5 is a positive displacement lens. More specifically, in Table 2, among the lenses L1 to L6, the specific lens The displacement amount (unit: μm) of the imaging position when one lens is decentered by 10 μm in a predetermined direction (Y direction in FIGS. 4 to 7). The displacement amount of the imaging position is “+” on the Y direction positive side in FIGS. 4 to 7 and “−” on the Y direction negative side. Further, the displacement amount (magnitude) of the imaging position shown in Table 2 can be referred to as the “sensitivity (eccentricity sensitivity)” in terms of the change amount of the imaging position with respect to a certain amount of eccentricity.

表２から分かる通り、レンズユニット１０においては、第１レンズＬ１と第４レンズＬ４が負変位レンズであり、第２レンズＬ２、第３レンズＬ３、第５レンズＬ５、及び第６レンズＬ６が正変位レンズである。

As can be seen from Table 2, in the lens unit 10, the first lens L1 and the fourth lens L4 are negative displacement lenses, and the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are positive. It is a displacement lens.

  In the above embodiment, the resin ring 16 is used to fix the decentering direction and amount of the fourth lens L4 and the fifth lens L5. However, as can be seen from Table 2, in the lens unit 10, the resin ring 16 is the same. The direction and amount of the eccentricity of the third lens L3 that is a positive displacement lens and the fourth lens L4 that is a negative displacement lens may be fixed using the resin ring. Similarly, the lens unit 10 uses a resin ring similar to the resin ring 16 to fix the decentering direction and amount of the first lens L1 that is a negative displacement lens and the second lens L2 that is a positive displacement lens. Also good. Similar to the resin ring 16 or the resin ring 16 in any one or a combination of the first lens L1 and the second lens L2, the third lens L3 and the fourth lens L4, or the fourth lens L4 and the fifth lens L5. The effect of the present invention can be obtained by fixing the direction and amount of eccentricity using the resin feeling.

  The positive displacement lens held by the resin ring 16 or the resin ring similar to the resin ring 16 has the highest decentration sensitivity among the plurality of lenses included in the lens unit 10 and is similar to the resin ring 16 or the resin ring 16. It is particularly preferable that the negative displacement lens held by the resin ring has the lowest decentration sensitivity among the plurality of lenses included in the lens unit 10. If the combination of lenses having the maximum and minimum eccentric sensitivity is held by the resin ring 16 or a resin ring similar to the resin ring 16 and the direction and amount of eccentricity are fixed, other combinations of positive displacement lenses and negative displacement lenses can be used. This is because the effect of suppressing changes in optical performance due to temperature changes or repeated temperature changes is higher than in the case of fixing the direction and amount of eccentricity. From this viewpoint, in the above embodiment, the resin ring 16 is used to fix the direction and amount of eccentricity of the fourth lens L4 and the fifth lens L5. Note that “maximum” and “minimum” described here are not the absolute values (absolute values of the values shown in Table 2) of the change amount of the imaging position, but the moving directions (positive or negative of the values shown in Table 2). Judgment based on the amount of displacement including).

  In addition, the positive displacement lens and the negative displacement lens held by the resin ring 16 or a resin ring similar to the resin ring 16 are preferably a combination of lenses having the closest diameter among the plurality of lenses included in the lens unit 10. This is because the resin ring 16 or a resin ring similar to the resin ring 16 can be easily press-fitted. In the lens unit 10 of the above embodiment, the combination of the fourth lens L4 and the fifth lens L5 is the combination of the lenses having the closest diameter among the combinations of the adjacent positive displacement lens and the negative displacement lens. The “lens combination having the closest diameter” includes a combination of two lenses having the same diameter.

  The positive displacement lens and the negative displacement lens held by the resin ring 16 or a resin ring similar to the resin ring 16 are the lens having the smallest diameter and the lens having the second smallest diameter among the plurality of lenses included in the lens unit 10. Or a combination of two lenses having the smallest diameter among the plurality of lenses included in the lens unit 10. This is because the resin ring 16 or a resin ring similar to the resin ring 16 can be easily press-fitted. In the lens unit 10 of the above embodiment, the combination of the fourth lens L4 and the fifth lens L5 is a combination of two lenses having the smallest diameter among the combinations of the adjacent positive displacement lens and the negative displacement lens.

  In addition, when one lens out of a plurality of lenses included in the lens unit 10 is decentered by a predetermined amount in a predetermined direction and another lens is disposed at a predetermined position, image formation due to the decentering of the one lens is performed. When comparing the displacement amount of the position (see Table 2), the positive displacement lens and the negative displacement lens held by the resin ring 16 or a resin ring similar to the resin ring 16 are a plurality of lenses included in the lens unit 10. A combination of a lens having the largest absolute value of displacement and a lens having the second largest absolute value of displacement is preferable. If the combination of lenses with the maximum and minimum absolute values of the displacement is held by the resin ring 16 or a resin ring similar to the resin ring 16 and the direction and amount of eccentricity are fixed, other combinations of positive displacement lenses and negative This is because the effect of suppressing the change in the optical performance due to the temperature change or the repetition of the temperature change is higher than in the case of fixing the direction and amount of the eccentricity of the displacement lens. As shown in Table 2, in the above embodiment, the combination of the fourth lens L4 and the fifth lens L5 is a combination of a lens having the largest absolute value of displacement and a lens having the second largest absolute value of displacement. is there.

  In the above embodiment, the resin ring 16 holds one positive displacement lens and one negative displacement lens. However, the resin ring 16 or a resin ring similar to the resin ring 16 has one or more positive displacement lenses. A displacement lens and one or more negative displacement lenses can be held. That is, the resin ring 16 can hold three or more lenses. In this case, the effect of the present invention can be obtained if at least one positive displacement lens and one negative displacement lens are held.

DESCRIPTION OF SYMBOLS 10 Lens unit 11 Lens barrel 12 Infrared cut filter 13, 17, 18 Presser ring 14, 15 Spacer 16 Resin ring 21 Lens holding part 22 Projection part

Claims (10)

A positive displacement lens having positive decentering sensitivity that shifts the imaging position in the predetermined direction when decentered in the predetermined direction with respect to the optical axis of the entire system, and decentered in the predetermined direction with respect to the optical axis of the entire system A plurality of lenses including a negative displacement lens having a negative eccentricity sensitivity in which the imaging position is displaced in a direction opposite to the predetermined direction,
The positive displacement lens and the negative displacement lens that are made of resin and that are adjacent to each other among the plurality of lenses are held, and the decentering direction of the positive displacement lens and the negative displacement lens with respect to the optical axis of the entire system and A resin ring to fix the amount;
A lens unit comprising:   The lens unit according to claim 1, wherein an inner diameter of the lens holding portion of the resin ring is smaller than outer diameters of the positive displacement lens and the negative displacement lens to be held.   The lens unit according to claim 1, wherein the resin ring has a plurality of protrusions protruding toward an inner peripheral side.   The resin ring is the light of the entire system including the positive displacement lens or the negative displacement lens held by the resin ring and the other lens adjacent to the positive displacement lens or the negative displacement lens held by the resin ring. The lens unit according to any one of claims 1 to 3, wherein the lens unit is a spacer that maintains an interval along the axial direction.   The lens unit according to claim 1, wherein the resin ring holds one positive displacement lens and one negative displacement lens.   The positive displacement lens held by the resin ring has the highest decentration sensitivity among the plurality of lenses, and the negative displacement lens held by the resin ring has the decentration sensitivity among the plurality of lenses. The lens unit according to claim 1, which is a minimum.   The lens unit according to any one of claims 1 to 6, wherein the positive displacement lens and the negative displacement lens held by the resin ring are a combination of lenses having the closest diameters among the plurality of lenses.   The positive displacement lens and the negative displacement lens held by the resin ring are a combination of a lens having the smallest diameter and a lens having the second smallest diameter among the plurality of lenses, or the most among the plurality of lenses. The lens unit according to claim 1, which is a combination of two lenses having a small diameter. When one lens of the plurality of lenses is decentered by a predetermined amount in the predetermined direction and another lens is disposed at a predetermined position, the amount of displacement of the imaging position due to the eccentricity of the one lens is determined. When comparing
The positive displacement lens and the negative displacement lens held by the resin ring are a lens having the largest absolute value of the displacement amount and a lens having the second largest displacement amount among the plurality of lenses. It is a combination, The lens unit of any one of Claims 1-8. As the plurality of lenses, in order from the object side, a first lens having negative power, a second lens having positive power, a third lens having positive power, and a fourth lens having negative power A fifth lens having a positive power and a sixth lens having a positive power,
The lens unit according to claim 1, wherein the resin ring holds the fourth lens and the fifth lens.

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