JP2021182065A - Lens alignment structure - Google Patents

Abstract

To provide an alignment structure for an imaging lens that realizes high performance while having a low height.SOLUTION: An imaging lens 1, of which a front group 110 and a rear group 120 are sequentially arranged from an object side, has an alignment structure including: a lens 10 that is located on the image side of the front group, and includes a first planar section 12a having a first protrusion 12b; and a lens 20 that is located on the object side of the rear group, and includes a second planar section 21a provided on a surface on the object side and having a second protrusion 21b. The first protrusion 12b and the second protrusion 21b are formed on respective circumferences around an optical axis X. The diameter of an inner peripheral surface 12c of the first protrusion 12b is larger than the diameter of an outer peripheral surface 21c of the second protrusion 21b. The lens alignment structure is bonded and fastened while the first protrusion 12b is in contact with the second planar section 21a, or the second protrusion 21b is in contact with the first planar section 12a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a alignment structure of a lens constituting an image pickup lens.

In recent years, various products have been equipped with a camera function. Images obtained through a camera are required to have high-definition image quality, and as products are made smaller and thinner, image pickup lenses are also required to be made smaller and thinner.

In the solid-state image sensor, the reduction of the pixel pitch is promoted in order to support high-definition image quality. On the other hand, the number of image pickup lenses tends to be increased in order to cope with high-definition image quality. However, as the number of constituents increases, it becomes difficult to perform highly accurate optical axis alignment due to the influence of member accuracy, combination error, and the like. In order to obtain an image pickup lens that satisfies the demand for low profile and sufficiently exerts the performance of the individual image pickup device, it is necessary to align the optical axis with higher accuracy.

Patent Document 1 discloses a lens unit that can easily adjust the optical axis and can be made thinner.

Patent Document 1 has a configuration in which the flange portion of the first lens and the front surface of the protruding portion provided on the frame body are flush with each other, and a thin light-shielding film is attached to at least one of these surfaces. By doing so, the lens unit is made thinner, and a frame opening is formed in the protruding portion provided at the front end of the frame body in order to position the second lens in the optical axis direction, and the air hearing solidified by this frame opening is used. A lens unit for adjusting the optical axis by moving the first lens in a direction orthogonal to the optical axis is disclosed.

International Publication No. 2013/0471998

In the lens unit described in Patent Document 1, it is difficult to align the center of the opening of the light-shielding film having the function of a diaphragm with the optical axis. Further, since a light-shielding film exists between the first lens and the second lens and the optical axes of both are adjusted via the light-shielding film, the thickness of the light-shielding film and the flatness of both sides vary in accuracy. , There are problems such as deterioration of the resolution performance of the lens unit.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a highly accurate lens alignment structure.

In order to solve the above problems, the alignment structure of the lens of the present invention includes a first lens barrel, a front group having at least one lens housed in the first lens barrel, and a second lens barrel. In the imaging lens in which the rear group having at least two lenses housed in the second lens barrel is arranged in order from the object side, the lens located on the image side of the front group is the surface on the image side. It has a first optically effective portion and a first plane portion perpendicular to the optical axis. The first plane portion is located around the first optically effective portion, and the first plane portion is light. The lens, which has a first protrusion protruding in a direction parallel to the axis and is located on the most object side of the rear group, has a second optically effective part on the surface on the object side and a second portion perpendicular to the optical axis. It has a flat surface portion, the second flat surface portion is located around the second optical effective portion, and the second flat surface portion has a second protrusion portion protruding in a direction parallel to the optical axis. The first protrusion and the second protrusion are each formed on the circumference centered on the optical axis, and the diameter of the inner peripheral surface of the first protrusion is the diameter of the outer peripheral surface of the second protrusion. Larger or the diameter of the outer peripheral surface of the first protrusion is smaller than the diameter of the inner peripheral surface of the second protrusion, the first protrusion is on the second plane, or the second protrusion is on the first plane. It is configured to be adhesively fixed in contact with the optical axis.

The alignment structure of the above lens is a structure in which the first protrusion formed in the front group and the second protrusion formed in the rear group are loosely fitted so that their respective optical axes can be aligned to some extent. It has become. Further, when the protrusion abuts on the flat surface of the other lens, the position in the optical axis direction is determined, and the predetermined lens spacing is maintained with high accuracy. That is, if the front group is placed in the rear group, a certain degree of resolution is generated, so that an initial peak can be generated in an MTF measuring instrument or the like that monitors the resolution. After that, precise alignment can be performed by adjusting so that the peak is maximized in the gap between the protrusions.

The resolution evaluator, measuring instrument, centering jig, etc. used for centering may be appropriately selected and manufactured according to the specifications such as the shape and performance of the image pickup lens.

Further, in order to solve the above problems, the alignment structure of the lens of the present invention consists of two lenses housed in the front group, and the lens located on the image side of the front group is on the surface on the object side. It has a third optically effective portion and a third plane portion perpendicular to the optical axis, the third plane portion is located around the third optically effective portion, and the third plane portion is the optical axis. The lens, which has a third protrusion protruding in a parallel direction and is located on the object side of the front group, has a fourth optically effective part on the surface on the image side and a fourth plane perpendicular to the optical axis. The fourth plane portion has a portion, the fourth plane portion is located around the fourth optically effective portion, and the fourth plane portion has a fourth protrusion portion that protrudes in a direction parallel to the optical axis. The three protrusions and the fourth protrusion are each formed on the circumference centered on the optical axis, and the diameter of the outer peripheral surface of the third protrusion is larger than the diameter of the inner peripheral surface of the fourth protrusion. Smaller or the diameter of the inner peripheral surface of the third protrusion is larger than the diameter of the outer peripheral surface of the fourth protrusion, the third protrusion is on the fourth plane, or the fourth protrusion is on the third plane. Includes structures that are adhesively fixed in contact with each other.

The alignment structure of the above lens is when the front group is composed of two lenses. For example, a structure in which a positive refractive power is applied to a lens located on the object side (light ray incident side) in the front group and a negative refractive power is applied to a lens located on the image side can be considered. That is, the structure is such that the image pickup lens is made thinner with a positive lens located on the object side, and the chromatic aberration generated by this positive lens is corrected by the negative lens located on the image side. When a strong refractive power is applied to the lens, the error sensitivity increases, and a slight optical axis shift between the lenses causes performance deterioration. In such a case, the performance deterioration can be suppressed by adopting the alignment structure of the above lens. The two lenses housed in the front group are not limited to positive and negative, and are appropriately selected according to the specifications and performance of the imaging lens. For example, when the first lens has a positive refractive power and the second lens has a positive refractive power to reduce the thickness, the first lens has a negative refractive power and the second lens has a positive refractive power. The alignment structure of this lens can be applied to various types of image pickup lenses, such as a combination of a first lens having a negative refractive power and a second lens having a negative refractive power.

Further, in order to solve the above problems, the alignment structure of the lens of the present invention has a difference between the diameter of the inner peripheral surface of the first protrusion and the diameter of the outer peripheral surface of the second protrusion, or the outer circumference of the first protrusion. When the difference between the diameter of the surface and the diameter of the inner peripheral surface of the second protrusion is D1, it is desirable that the following conditional expression (1) is satisfied.
(1) 5 μm <D1 <50 μm

The conditional expression (1) is the difference between the diameter of the inner peripheral surface of the first protrusion and the diameter of the outer peripheral surface of the second protrusion, or the diameter of the outer peripheral surface of the first protrusion and the inner peripheral surface of the second protrusion. It properly defines the difference in diameter. By setting the range of the conditional expression (1), the initial peak of the resolution can be made to appear when the front group is placed in the rear group.

Further, in order to solve the above problems, the alignment structure of the lens of the present invention has a difference between the diameter of the inner peripheral surface of the third protrusion and the diameter of the outer peripheral surface of the fourth protrusion, or the outer circumference of the third protrusion. When the difference between the diameter of the surface and the diameter of the inner peripheral surface of the fourth protrusion is D2, it is desirable that the following conditional expression (2) is satisfied.
(2) 5 μm <D2 <50 μm

The conditional expression (2) is the difference between the diameter of the inner peripheral surface of the third protrusion and the diameter of the outer peripheral surface of the fourth protrusion, or the diameter of the outer peripheral surface of the third protrusion and the inner peripheral surface of the fourth protrusion. It properly defines the difference in diameter.

By setting the range of the conditional expression (2), the initial peak of the resolution can be made to appear as the front group when the two sheets constituting the front group are overlapped.

Further, in order to solve the above problems, the alignment structure of the lens of the present invention has an inner peripheral surface of the first protrusion and an outer peripheral surface of the second protrusion, or an outer peripheral surface of the first protrusion and the second protrusion. It is desirable that the inner peripheral surface of each of the above is formed by an inclined surface.

By forming inclined surfaces on the inner peripheral surface of the first protrusion and the outer peripheral surface of the second protrusion, or on the outer peripheral surface of the first protrusion and the inner peripheral surface of the second protrusion, respectively, the front group is reared. Since it serves as a guide when placing in a group, it is possible to prevent errors during assembly.

Further, in order to solve the above problems, the alignment structure of the lens of the present invention has an inner peripheral surface of the third protrusion and an outer peripheral surface of the fourth protrusion, or an outer peripheral surface of the third protrusion and the fourth protrusion. It is desirable that each of the inner peripheral surfaces of the above is formed with an inclined surface.

Each lens is formed by forming an inclined surface on the inner peripheral surface of the third protrusion and the outer peripheral surface of the fourth protrusion, or on the outer peripheral surface of the third protrusion and the inner peripheral surface of the fourth protrusion, respectively. Since the inclined surface serves as a guide when stacking, it is possible to prevent errors during assembly.

Further, in order to solve the above problems, in the centering structure of the lens of the present invention, the plurality of lenses constituting the rear group are arranged on the facing surfaces of the adjacent lenses with respect to the optical effective portion and the optical axis, respectively. It has a vertical flat surface portion, the flat surface portion is located around the optical effective portion, the flat surface portion has a protrusion portion protruding in a direction parallel to the optical axis, and the protrusion portion is centered on the optical axis. It is desirable that the lens is formed on the circumference of the lens and that the protrusions of adjacent lenses are fitted to each other.

By fitting a plurality of lenses housed in the rear group at the protrusions, the optical axis can be easily aligned.

Further, in order to solve the above problems, in the centering structure of the lens of the present invention, in the plurality of lenses constituting the rear group, one of the protrusions is applied to the flat surface portion of the surface on which the adjacent lenses face each other. It is desirable to be in contact.

A predetermined lens spacing is determined by bringing one of the protrusions into contact with the flat surface of the surface on which the adjacent lenses face each other.

Further, in order to solve the above problems, in the alignment structure of the lens of the present invention, the outer peripheral surface of at least one lens in the rear group is fitted to the inner peripheral surface of the second lens barrel. Is desirable.

By fitting the outer peripheral surface of at least one lens in the rear group to the inner peripheral surface of the second lens barrel, the optical axes of the rear group and the second lens barrel can be aligned.

Further, in the alignment structure of the lens, it is desirable that the following conditional expression (3) is satisfied when the angle formed by the inclined surface of the protrusion and the optical axis is α.
(3) 10 ° <α <30 °

The conditional expression (3) is a range in which misalignment is unlikely to occur when each lens is placed.

Regarding the conditional expression (3), the following conditional expression (3a) is in a more preferable range.
(3a) 10 ° <α <20 °

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a highly accurate lens alignment structure.

It is a figure which shows the structure of the image pickup lens which has the alignment structure of the lens which concerns on 1st Embodiment of this invention. It is an exploded view of the image pickup lens shown in FIG. It is a figure which shows the structure of the front group and the rear group of the image pickup lens shown in FIG. It is a figure which shows the structure of the image pickup lens which has the alignment structure of the lens which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the image pickup lens which has the alignment structure of the lens which concerns on 3rd Embodiment of this invention. It is an exploded view of the image pickup lens shown in FIG. It is a figure which shows the structure of the front group and the rear group of the image pickup lens shown in FIG. It is a figure for demonstrating the angle α formed by the inclined surface of the protrusion, and the optical axis in this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

The optical axis X referred to here is the central axis of the image pickup lens, and is shown by a alternate long and short dash line for the sake of explanation, but it does not have a physical substance. Further, the state in which the optical axes match here means a state in which the error is within an allowable range, that is, a state in which the required optical performance is satisfied.

Further, for convenience of explanation, the same reference numerals are added to the configurations having the same functions as the configurations described in the specific items, and the description thereof will be omitted.

(First Embodiment)
The first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 shows a cross-sectional view of an image pickup lens 1 provided with a lens alignment structure according to the first embodiment of the present invention, in which one lens is used in the front group and five lenses are used in the rear group as a whole. The alignment structure of the front group and the rear group of the image pickup lens composed of six lenses is shown.

As shown in FIG. 1, the lenses constituting the image pickup lens 1 are housed in the first lens barrel 101 and the first lens barrel 101 in order from the object side (upper part of the drawing) to the image side (lower part of the drawing). A front lens group 110 composed of a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, and a second lens barrel 201 and a second lens barrel 201 housed in the second lens barrel 201. It is composed of a rear group 120 including a sixth lens 60.

Further, in the rear group 120, between the second lens 20 and the third lens 30, between the third lens 30 and the fourth lens 40, between the fourth lens 40 and the fifth lens 50, and the fifth lens. A light-shielding plate 500 is arranged between the 50 and the sixth lens 60, respectively. The light-shielding plate 500 is for blocking unnecessary light generated inside the image pickup lens 1, and has an annular shape having an opening having an opening having a diameter almost the same as the diameter of the maximum effective light ray passing through the optically effective part of each lens. It is a member of the flat plate. The light-shielding plate 500 is made of a material having light-shielding performance.

Next, the structures of the front group 110 and the rear group 120 will be described below with reference to FIGS. 2 and 3.

The first lens barrel 101 is formed in a cylindrical shape having an object-side opening 101a and an image-side opening 101b. Around the object-side opening 101a, a surface 101c perpendicular to the optical axis X is formed on the object side, and a receiving surface 101d perpendicular to the optical axis X is formed on the image side thereof. Further, an inclined surface 101e projecting from the receiving surface 101d toward the image side is formed. The object-side opening 101a is the aperture stop of the image pickup lens.

Around the optically effective portion 11 on the object side of the first lens 10, a flat surface portion 11a and a flat surface portion 11b protruding toward the object side from the flat surface portion 11a are formed, and each plane is an inclined surface extending toward the object side. It is connected at 11c.

When the first lens 10 is inserted into the first lens barrel 101, the flat surface portion 11b of the first lens 10 comes into contact with the receiving surface 101d of the first lens barrel 101, and the first lens barrel 101 comes into contact with the inclined surface 101e. The inclined surface 11c of 1 lens 10 comes into contact with the inclined surface 11c. When the flat surface portion 11b of the first lens 10 comes into contact with the receiving surface 101d of the first lens barrel 101, the positions of both optical axes in the X direction are determined. When the inclined surface 11c of the first lens 10 comes into contact with the inclined surface 1e of the first lens barrel 101, both optical axes coincide with each other. After that, the outer peripheral portion 13 of the first lens 10 and the inner peripheral portion 101f of the first lens barrel 101 are fixed by the adhesive 300. The adhesive 300 may be applied to the inner circumference 101f of the first lens barrel 101 in advance. Further, the fixing method is not limited to adhesion, but welding or the like may be used.

The second lens barrel 201 is formed in a cylindrical shape having an object-side opening 201a and an image-side opening 201b. A surface 201c perpendicular to the optical axis X is formed on the object side around the object side opening 201a, and a receiving surface 201d perpendicular to the optical axis X is formed on the image side thereof. Further, the shape of the inner peripheral portion of the cylinder has a step of 2e, 2f, 2g, and 2h according to the diameter of the outer circumference of each lens to be housed.

The second lens 20 to the sixth lens 60 each have an optically effective portion and a plane portion perpendicular to the optical axis X on the surface on the object side and the surface on the image side, respectively. The plane portion perpendicular to the optical axis X is located around the optically effective portion. An annular protrusion protruding from a flat surface perpendicular to the optical axis is formed on the lens surface facing the lens. The annular protrusions are each formed on the circumference centered on the optical axis, and the facing protrusions are fitted to each other. Further, the annular protrusion is in contact with a flat surface portion perpendicular to the optical axis X of the lens to which one of them faces.

The flat surface portion 21a formed on the object side of the second lens 20 abuts on the receiving surface 201d formed inside the second lens barrel 201 and perpendicular to the optical axis X. The outer peripheral portion 22c of the protrusion 22b formed on the image side of the second lens 20 fits into the inner peripheral portion 31c of the protrusion 31b formed on the object side of the third lens 30, and the protrusion of the third lens 30 is formed. The tip of the portion 31b abuts on the flat surface portion 22a on the image side of the second lens 20. As a result, the optical axes X of both lenses coincide with each other, and the lens spacing is determined. The light-shielding plate 500 is arranged inside the inner peripheral portion 31c of the protrusion 31b on the object side of the third lens 30. Further, the light-shielding plate 500 is arranged in an appropriate play space formed between the protrusion 22b on the image side of the second lens 20 and the third lens 30.

The outer peripheral portion 32c of the protrusion 32b formed on the image side of the third lens 30 fits into the inner peripheral portion 41c of the protrusion 41b formed on the object side of the fourth lens 40. The tip of the protrusion 41b abuts on the flat surface 32a on the image side of the third lens 30. As a result, the optical axes X of both lenses coincide with each other, and the lens spacing is determined. The light-shielding plate 500 is arranged inside the inner peripheral portion 41c of the protrusion 41b on the object side of the fourth lens 40. Further, the light-shielding plate 500 is arranged in an appropriate play space formed between the protrusion 32b on the image side of the third lens 30 and the fourth lens 40.

The outer peripheral portion 42c of the protrusion 42b formed on the image side of the fourth lens 40 fits into the inner peripheral portion 51c of the protrusion 51b formed on the object side of the fifth lens 50. The tip of the protrusion 51b abuts on the flat surface 42a on the image side of the fourth lens 40. As a result, the optical axes X of both lenses coincide with each other, and the lens spacing is determined. The light-shielding plate 500 is arranged inside the inner peripheral portion 51c of the protrusion 51b on the object side of the fifth lens 50. Further, the light-shielding plate 500 is arranged in an appropriate play space formed between the protrusion 42b on the image side of the fourth lens 40 and the fifth lens 50.

The outer peripheral portion 52c of the protrusion 52b formed on the image side of the fifth lens 50 fits into the inner peripheral portion 61c of the protrusion 61b formed on the object side of the sixth lens 60. The tip of the protrusion 61b abuts on the flat surface 52a on the image side of the fifth lens 50. As a result, the optical axes X of both lenses coincide with each other, and the lens spacing is determined. The light-shielding plate 500 is arranged inside the inner peripheral portion 61c of the protrusion 61b on the object side of the sixth lens 60. Further, the light-shielding plate 500 is arranged in an appropriate play space formed between the protrusion 52b on the image side of the fifth lens 50 and the sixth lens 60.

The second lens 20 to the fifth lens 50 are in a state of being loosely fitted with the second lens barrel 201, respectively. On the other hand, the outer peripheral portion 63 of the sixth lens 60 and the inner peripheral portion 201h of the second lens barrel 201 are fitted to each other. Therefore, the optical axis X of the sixth lens 60 and the second lens barrel 201 are in the same state. When the optical axes X of the sixth lens 60 and the second lens barrel 201 match, the optical axes X of the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 are also second. It is in a state corresponding to the optical axis X of the lens barrel 201.

The lens fitted to the inner peripheral portion of the second lens barrel 201 is not limited to the sixth lens 60. One of the lenses housed in the rear group 120 may be fitted to the inner peripheral portion of the second lens barrel 201.

After the sixth lens 60 is fitted to the second lens barrel 201, the adhesive 300 is applied to the flat surface portion 62a on the image side of the sixth lens 60 and fixed. The fixing method is not limited to adhesion, but welding or the like may be used.

The rear group completed above is placed on a positioning jig (not shown). An optical evaluation device (not shown) such as an MFT measuring device is directly connected to the positioning jig so that the output value of the resolution performance of the image pickup lens can be confirmed while mounted on the positioning jig. It has become. These devices can be obtained by improving the shape according to the work. For the planar position adjustment between the rear group and the evaluator, for example, an XY table or the like is used.

The rear group 120 is placed on a positioning jig, and the rear group is adjusted and fixed in a plane at a position where the peak value output from the evaluator is maximized.

After that, the front group 110 is placed in the rear group 120. The first lens 10 housed in the front group 110 has a first optical effective portion 12 and a first plane portion 12a perpendicular to the optical axis X on a surface on the image side thereof. The first plane portion 12a is located around the first optically effective portion 12. The first plane portion 12a has a first protrusion 12b that protrudes in a direction parallel to the optical axis X.

On the other hand, the lens located closest to the object side of the rear group 120, that is, the second lens 20, has the second optically effective portion 21 and the second plane portion 21a perpendicular to the optical axis X on the surface on the object side. have. The second plane portion 21a is located around the second optically effective portion 21. The second plane portion 21a has a second protrusion 21b that protrudes in a direction parallel to the optical axis X.

Here, the first protrusion 12b and the second protrusion 21b are each formed in an annular shape on the circumference centered on the optical axis X. The inner peripheral surface 12c of the first protrusion 12b is set to be larger than the outer peripheral surface 21c of the second protrusion 21b. Therefore, when the front group 110 is placed on the rear group 120, the first protrusion 12b and the second protrusion 21b are loosely fitted. This difference in diameter is the appropriate gap D1 for centering, as shown in FIG. Further, since the rising surface of the first protrusion 12b and the second protrusion 21b is an inclined surface, the first protrusion 12b serves as a guide when the first protrusion 12b and the second protrusion 21b are mounted, and the position shift during the placement is prevented. Further, since the tip end portion of the first protrusion 12b is in contact with the second flat surface portion 21a, the lens distance between the front group 110 and the rear group 120 is accurately maintained.

Further, since the optical axes X of the front group 110 and the rear group 120 are located in the region of the gap D1, the optical axes X are aligned to some extent, and an initial peak appears from the evaluator. After that, the front group is moved horizontally and adjusted to the position where the peak is maximized. After aligning in this way, the adhesive 300 flows in from the gap 400 between the front group 110 and the rear group 120 to fix the first plane portion and the second plane portion, and the image pickup lens 1 is completed.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a cross-sectional view of an image pickup lens 2 provided with a lens alignment structure according to a second embodiment of the present invention. In the second embodiment, the structure in which the protrusions of the front group and the rear group are loosely fitted is different from that of the first embodiment. Therefore, only the gist thereof will be described, and the common parts will be designated by the same reference numerals. The explanation is omitted.

As shown in FIG. 4, the first lens 10 housed in the front group 110 has a first optical effective portion 12 and a first plane portion 12a perpendicular to the optical axis X on a surface on the image side thereof. Have. The first plane portion 12a is located around the first optically effective portion 12. The first plane portion 12a has a first protrusion 12b that protrudes in a direction parallel to the optical axis X.

On the other hand, the lens located closest to the object side of the rear group 120, that is, the second lens 20, has the second optically effective portion 21 and the second plane portion 21a perpendicular to the optical axis X on the surface on the object side. have. The second plane portion 21a is located around the second optically effective portion 21. The second plane portion 21a has a second protrusion 21b that protrudes in a direction parallel to the optical axis X.

Here, the first protrusion 12b and the second protrusion 21b are each formed in an annular shape on the circumference centered on the optical axis X. The outer peripheral surface 12c of the first protrusion 12b is set smaller than the inner peripheral surface 21c of the second protrusion 21b. Therefore, when the front group 110 is placed on the rear group 120, the first protrusion 12b and the second protrusion 21b are loosely fitted. This difference in diameter is the appropriate gap D1 for centering, as shown in FIG. Further, since the rising surface of the first protrusion 12b and the second protrusion 21b is an inclined surface, the first protrusion 12b serves as a guide when the first protrusion 12b and the second protrusion 21b are mounted, and the position shift during the placement is prevented. Further, since the tip end portion of the first protrusion 12b is in contact with the second flat surface portion 21a, the lens distance between the front group 110 and the rear group 120 is accurately maintained.

Since the optical axes X of the front group 110 and the rear group 120 are located in the region of the gap D1, the optical axes X are aligned to some extent, and an initial peak appears from the evaluator. After that, the front group is moved horizontally and adjusted to the position where the peak is maximized. After aligning in this way, the adhesive 300 flows in from the gap 400 between the front group 110 and the rear group 210 to fix the first lens 10 and the second lens 20, and the image pickup lens 2 is completed.

(Third Embodiment)
A third embodiment of the present invention will be described with reference to FIGS. 5 to 7. FIG. 5 shows a cross-sectional view of an image pickup lens 3 provided with a lens alignment structure according to a third embodiment of the present invention. In the third embodiment, the number of lenses stored in the front group is two, the number of lenses stored in the rear group is four, and the two lenses in the front group are adjusted as compared with the first embodiment. The difference is that the second lens located on the image side of the front group and the third lens located on the object side of the rear group perform the centering of the front group and the rear group. Only the gist thereof will be described, and the common parts will be designated by the same reference numerals as those in the first embodiment and the description thereof will be omitted.

As shown in FIG. 5, the lenses constituting the image pickup lens 3 are housed in the first lens barrel 101 and the first lens barrel 101 in order from the object side (upper part of the drawing) to the image side (lower part of the drawing). The front group 111 including the first lens 10 and the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, and the third lens 30, housed in the second lens barrel 202 and the second lens barrel 202, and the second lens barrel 202. It is composed of a rear group 121 including a sixth lens 60.

Further, in the rear group 121, light is shielded between the third lens 30 and the fourth lens 40, between the fourth lens 40 and the fifth lens 50, and between the fifth lens 50 and the sixth lens 60, respectively. The plate 500 is arranged. The function, shape, and material of the light-shielding plate 500 are the same as those described in the first embodiment.

The positional relationship between the first lens barrel 101 of the front group 111 and the first lens 10 is the same as that of the first embodiment.

In the third embodiment, the structure is such that the first lens 10 and the second lens 20 in the front group 111 are aligned.

The second lens 20 is placed on a positioning jig (not shown). An optical evaluation device (not shown) such as an MFT measuring device is directly connected to the positioning jig so that the output value of the resolution performance of the image pickup lens can be confirmed while mounted on the positioning jig. It has become. These devices can be obtained by improving the shape according to the work. For the planar position adjustment between the second lens 20 and the evaluator, for example, an XY table or the like is used.

The second lens 20 is placed on a positioning jig, and the second lens 20 is adjusted and fixed in a plane at a position where the peak value output from the evaluator is maximized.

After that, the first lens 10 housed in the first lens barrel 101 is placed on the second lens 20. At this time, the second lens 20 has a third optically effective portion 21 and a third plane portion 21a perpendicular to the optical axis X on the surface on the object side. The third plane portion 21a is located around the third optically effective portion 12. The third plane portion 21a has a third protrusion 21b that protrudes in a direction parallel to the optical axis X.

On the other hand, the image-side surface of the first lens 10 has a fourth optical effective portion 12 and a fourth plane portion 12a perpendicular to the optical axis X. The fourth plane portion 12a is located around the fourth optically effective portion 12. The fourth plane portion 12a has a fourth protrusion 12c that protrudes in a direction parallel to the optical axis X.

Here, the third protrusion 21b and the fourth protrusion 12b are each formed in an annular shape on the circumference centered on the optical axis X. The outer peripheral surface 21c of the third protrusion 21b is set smaller than the inner peripheral surface 12c of the fourth protrusion 12b. Therefore, when the first lens 10 is placed on the second lens 20, the third protrusion 21b and the fourth protrusion 12b are loosely fitted. This difference in diameter is the appropriate gap D2 for alignment as shown in FIG. Further, since the rising surfaces of the third protrusion 21b and the fourth protrusion 12b are inclined surfaces, they serve as guides when mounting and prevent misalignment during mounting. Further, since the tip end portion of the fourth protrusion 12b is in contact with the third flat surface portion 21a, the lens distance between the first lens 10 and the second lens 20 is accurately maintained.

Since the optical axes X of the first lens 10 and the second lens 20 are located in the region of the gap D2, the optical axes X are aligned to some extent, and an initial peak appears from the evaluator. After that, the first lens 10 is moved horizontally and adjusted to the position where the peak is maximized. After aligning in this way, the adhesive 300 flows into the outer peripheral side of the lens to fix the first lens 10 and the second lens 20, and the front group 111 is completed.

The rear group 121 of the third embodiment is the rear group of the first embodiment changed from 5 to 4, and the optical axis of each lens is aligned, the height in the optical axis direction (lens spacing) is set, and the lens barrel is used. Aligning the optical axis with the 202 and fixing the lens barrel 202 and the lens are the same as in the first embodiment.

The rear group 121 is placed on a positioning jig, and the rear group is adjusted and fixed in a plane at a position where the peak value output from the evaluator is maximized.

After that, the front group 111 is placed in the rear group 121. At this time, the lens located on the image side of the front group 111, that is, the second lens 20, has the first optical effective portion 22 and the first plane portion 22a perpendicular to the optical axis X on the surface on the image side. And have. The first plane portion 22a is located around the first optically effective portion 22. The second plane portion 22a has a first protrusion 22b that protrudes in a direction parallel to the optical axis X.

On the other hand, the lens located closest to the object side of the rear group 121, that is, the third lens 30, has the second optically effective portion 31 and the third plane portion 31a perpendicular to the optical axis X on the surface on the object side. have. The third plane portion 31a is located around the third optically effective portion 31. The third plane portion 31a has a third projection portion 31c that protrudes in a direction parallel to the optical axis X.

Here, the first protrusion 22b and the second protrusion 31b are each formed in an annular shape on the circumference centered on the optical axis X. The outer peripheral surface 22c of the first protrusion 22b is set smaller than the inner peripheral surface 31c of the second protrusion 31b. Therefore, when the front group 111 is placed on the rear group 121, the first protrusion 22b and the second protrusion 31b are loosely fitted. This difference in diameter is the appropriate gap D1 for centering, as shown in FIG. Further, since the rising surface of the first protrusion 22b and the second protrusion 31b is an inclined surface, it serves as a guide when mounting and prevents misalignment during mounting. Further, since the tip end portion of the second protrusion 31b is in contact with the first flat surface portion 22a, the lens distance between the front group 111 and the rear group 121 is accurately maintained.

Since the optical axes X of the front group 111 and the rear group 121 are located in the region of the gap D1, the optical axes are aligned to some extent, and an initial peak appears from the evaluator. After that, the front group 111 is moved horizontally and adjusted to the position where the peak is maximized. After aligning in this way, the adhesive 300 flows in from the gap 400 between the front group 111 and the rear group 121 to fix the front group 111 and the rear group 121, and the image pickup lens 3 is completed.

Although the third embodiment has described an example in which the first lens 10 and the second lens 20 of the front group 111 are pre-aligned, the present invention is not limited thereto. For example, the second lens 20 may be placed on the rear group 121, aligned, and then adhesively fixed, and then the first lens 10 may be placed, aligned, and then adhesively fixed.

In the above embodiment, when the gap (alignment range) between the first protrusion and the second protrusion is D1, the following conditional expression (1) is satisfied.
(1) 5 μm <D1 <50 μm
By satisfying the conditional expression (1), the initial resolution peak before the alignment of the front group and the rear group is likely to appear.

Further, in the third embodiment, when the gap (alignment range) between the third protrusion and the fourth protrusion is D2, the following conditional expression (2) is satisfied.
(2) 5 μm <D2 <50 μm
By satisfying the conditional expression (2), the initial resolution peak before the alignment of the front group composed of two sheets is likely to appear.

Further, an inclined surface is formed on the surface where the first protrusion and the second protrusion face each other, and the angle α formed by the inclined surface and the optical axis satisfies the following conditional expression (3). It has become.
(3) 10 ° <α <30 °
By satisfying the conditional expression (3), when the group is moved in the horizontal direction at the time of centering, it is possible to prevent an error during assembly due to riding.

(Additional notes)
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the basic configuration such as the shape of each lens and the number of lenses may be appropriately selected.

1, 2, 3: Imaging lens 10: 1st lens 20: 2nd lens 30: 3rd lens 40: 4th lens 50: 5th lens 60: 6th lens 110, 111: front group 120, 121: rear group 101: 1st lens barrel 201, 202: 2nd lens barrel 300: Adhesive 500: Shading plate 12: 1st optical effective part 21: 2nd optical effective part 31: 3rd optical effective part 12a: 1st flat surface Part, 4th flat surface portion 21a: 2nd flat surface portion, 3rd flat surface portion 12b: 1st protrusion, 4th protrusion 21b: 2nd protrusion, 3rd protrusion X: optical axis L1: 1st lens L2: 2nd lens L3: 3rd lens L4: 4th lens L5: 5th lens L6: 6th lens

Claims (9)

A first lens barrel, a front group having at least one lens housed in the first lens barrel, a second lens barrel, and at least two lenses housed in the second lens barrel. In the rear group having, and in the image pickup lens arranged in order from the object side,
The lens located most on the image side of the front group has a first optical effective portion and a first plane portion perpendicular to the optical axis on the surface on the image side, and the first plane portion is The first plane portion is located around the first optically effective portion, and the first plane portion has a first protrusion portion that protrudes in a direction parallel to the optical axis.
The lens located most on the object side of the rear group has a second optical effective portion and a second plane portion perpendicular to the optical axis on the surface on the object side, and the second plane portion is The second plane portion is located around the second optically effective portion, and the second plane portion has a second protrusion portion that protrudes in a direction parallel to the optical axis.
The first protrusion and the second protrusion are each formed on the circumference centered on the optical axis, and are also formed.
The diameter of the inner peripheral surface of the first protrusion is larger than the diameter of the outer peripheral surface of the second protrusion, or the diameter of the outer peripheral surface of the first protrusion is the diameter of the inner peripheral surface of the second protrusion. Smaller than the diameter,
A alignment structure of a lens, characterized in that the first projection portion is adhered and fixed to the second plane portion or the second projection portion is in contact with the first plane portion. The lens housed in the front group consists of two lenses.
The lens located on the image side of the front group has a third optical effective portion and a third plane portion perpendicular to the optical axis on the surface on the object side, and the third plane portion is the above-mentioned. The third plane portion is located around the third optically effective portion, and the third plane portion has a third protrusion portion that protrudes in a direction parallel to the optical axis.
The lens located on the object side of the front group has a fourth optical effective portion and a fourth plane portion perpendicular to the optical axis on the surface on the image side, and the fourth plane portion is the above-mentioned. Located around the fourth optical effective portion, the fourth plane portion has a fourth projection portion that protrudes in a direction parallel to the optical axis.
The third protrusion and the fourth protrusion are each formed on the circumference centered on the optical axis, and are also formed.
The diameter of the outer peripheral surface of the third protrusion is smaller than the diameter of the inner peripheral surface of the fourth protrusion, or the diameter of the inner peripheral surface of the third protrusion is the diameter of the outer peripheral surface of the fourth protrusion. Larger than the diameter,
The lens according to claim 1, wherein the third protrusion is adhesively fixed to the fourth flat surface portion or the fourth protrusion portion is in contact with the third flat surface portion. Alignment structure. The difference between the diameter of the inner peripheral surface of the first protrusion and the diameter of the outer peripheral surface of the second protrusion, or the diameter of the outer peripheral surface of the first protrusion and the diameter of the inner peripheral surface of the second protrusion. The alignment structure of the lens according to claim 1, which satisfies the following conditional expression (1) when the difference is D1.
(1) 5 μm <D1 <50 μm The difference between the diameter of the outer peripheral surface of the third protrusion and the diameter of the inner peripheral surface of the fourth protrusion, or the diameter of the inner peripheral surface of the third protrusion and the diameter of the outer peripheral surface of the fourth protrusion. The alignment structure of the lens according to claim 2, wherein the difference is D2, and the following conditional expression (2) is satisfied.
(2) 5 μm <D2 <50 μm The inner peripheral surface of the first protrusion and the outer peripheral surface of the second protrusion, or the outer peripheral surface of the first protrusion and the inner peripheral surface of the second protrusion are each formed by an inclined surface. The alignment structure of the lens according to claim 1. The inner peripheral surface of the third protrusion and the outer peripheral surface of the fourth protrusion, or the outer peripheral surface of the third protrusion and the inner peripheral surface of the fourth protrusion are each formed by an inclined surface. 2. The alignment structure of the lens according to claim 2. The rear group has an optically effective portion and a flat surface portion perpendicular to the optical axis, respectively, on opposite surfaces of adjacent lenses, and the flat surface portion is located around the optically effective portion. The flat surface portion has a protrusion portion that protrudes in a direction parallel to the optical axis.
The protrusions are formed on the circumference centered on the optical axis, and the protrusions are formed on the circumference.
The alignment structure of the lens according to claim 1 or 2, wherein the protrusion is fitted. The alignment structure of the lens according to claim 7, wherein one of the protrusions is in contact with the flat surface portion of the surface on which the adjacent lenses face each other. The alignment structure of the lens according to claim 1, wherein the outer peripheral surface of at least one lens in the rear group is fitted to the inner peripheral surface of the second lens barrel.

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