WO2015008579A1

WO2015008579A1 - Array lens manufacturing method, array lens, and array lens unit

Info

Publication number: WO2015008579A1
Application number: PCT/JP2014/066475
Authority: WO
Inventors: 原明子
Original assignee: コニカミノルタ株式会社
Priority date: 2013-07-18
Filing date: 2014-06-20
Publication date: 2015-01-22
Also published as: CN105392617A; JPWO2015008579A1

Abstract

Provided is an array lens manufacturing method for which the variation in pitch between lens elements with changes in temperature is substantially the same for repeated temperature changes and hysteresis related to expansion and contraction has been substantially resolved. The array lens manufacturing method comprises: a forming process for integrally forming array lenses (10, 20), in which multiple lens elements (10a, 20a) arranged two dimensionally in the directions orthogonal to an optical axis (OA) and support sections (10b, 20b) connecting the multiple lens elements (10a, 20a) are formed, from resin; and a heat treatment process for performing, after the forming process, a heat treatment on the array lenses (10, 20) at a temperature of (Tg)-65°C to (Tg)-10°C for 24 to 168 hours when (Tg) is the glass transition temperature.

Description

Array lens manufacturing method, array lens, and array lens unit

The present invention relates to a resin array lens manufacturing method, an array lens, and an array lens unit, which have a plurality of lens elements arranged in a direction orthogonal to the optical axis, and are particularly incorporated in an imaging device or the like.

Demand for thinning of imaging optical systems in recent years has been greatly increased. In order to respond to this, the manufacturing accuracy has been improved in response to the shortening of the overall length due to optical design and the accompanying increase in error sensitivity. The technique of obtaining an image with an element is insufficient.

Therefore, the optical system called compound-eye optical system, which performs final image output by dividing the area of the image sensor and arranging the optical system in each area and processing the resulting image in combination, is made thinner Attention has been paid to meet the demands for the above, and various compound eye optical systems have been proposed so far.

If the camera function of a mobile communication terminal or the like incorporating an image pickup optical system is used continuously, the temperature of the sensor of the image pickup device rises. When the array lens used as the compound-eye optical system is made of glass, the pitch variation between the lenses hardly occurs even when the temperature changes. However, when the array lens is made of resin, when the temperature changes, a pitch variation between the lenses occurs due to linear expansion. Here, even if the temperature change (temperature increase / decrease) is repeated, if the amount of pitch fluctuation at each temperature is always the same, even if the temperature rises by continuing to use the camera, each individual pixel on the desired pixel Lens displacement can be easily corrected by image processing, and processing such as super-resolution becomes easy. However, pitch fluctuations (resin expansion) due to temperature changes are not the same. For example, even if the temperature is the same, if the position between individual lenses changes between when the temperature rises and when the temperature falls, this pitch fluctuation. As a result, processing such as super-resolution may become complicated and problems may occur.

In the field of optical pickup lenses, not imaging lenses, there are those that perform heat treatment or wet heat treatment (also referred to as annealing treatment) after molding (see, for example, Patent Documents 1 and 2). By performing the annealing treatment, the optical performance is stabilized and the aberration performance can be improved by relieving the stress of the lens which is a molded product. On the other hand, in the imaging system lens incorporated in the imaging device, a monocular lens is generally used, which is larger than the optical pickup system lens, and the imaging device and the lens are mounted by assembling the imaging device or mounting a focusing mechanism. Since the optical performance as high as that of the lens of the optical pickup system was not required, the annealing treatment was not required.

JP 2008-287817 A JP 2010-271372 A

The present invention relates to an array lens manufacturing method, an array lens, and an array lens in which the pitch variation between the lens elements in the direction orthogonal to the optical axis with respect to the temperature change is substantially the same with respect to the temperature change, and hysteresis related to expansion and contraction is substantially eliminated. The purpose is to provide units.

In order to solve the above problems, the array lens manufacturing method according to the present invention includes a plurality of lens elements that are two-dimensionally arranged in a direction orthogonal to the optical axis and a support that connects the plurality of lens elements. The molding process of integrally molding the array lens with resin, and after the molding process, when the glass transition temperature is Tg, the temperature is Tg−65 ° C. or more and Tg−10 ° C. or less for 24 hours or more and 168 hours or less. A heat treatment step for performing heat treatment.

According to the above method for manufacturing an array lens, the heat treatment is performed under the above conditions, whereby the molding distortion of the array lens is reduced or eliminated by releasing the stress. As a result, the pitch variation in the direction perpendicular to the optical axis between the lens elements with respect to the temperature change becomes substantially the same at each temperature, and an array lens in which hysteresis related to expansion and contraction is substantially eliminated can be obtained. As a result, for example, even if the camera continues to be used and the temperature rises, the deviation of the individual lens elements from the desired pixel can be easily corrected by image processing, and processing such as super-resolution becomes possible. Here, the hysteresis related to expansion and contraction refers to a phenomenon in which the relative positions of the individual lens elements shift at the same temperature when the temperature rises and when the temperature falls.

That is, the present invention has found a problem peculiar to an array lens in which the distance between the optical axes of a plurality of lens elements arranged two-dimensionally in a direction orthogonal to the optical axis expands and contracts according to the environmental temperature. It is a thing. More specifically, due to the structure of the array lens, if the thickness in the optical axis direction is t, at least one of the vertical dimension and the horizontal dimension in the direction perpendicular to the optical axis is often 10t to 30t, depending on the environmental temperature. The amount of change is much larger in the direction perpendicular to the optical axis than in the optical axis direction. For this reason, it has been conceived that it is necessary to consider the expansion and contraction in the direction orthogonal to the optical axis in the array lens. Further, when the array lens of the present invention is used as an imaging system lens, it can be corrected by image processing even if the resin is slightly deteriorated and yellowed due to overheating to reduce distortion. The degree of freedom of heating conditions can be increased. By setting the heating temperature to Tg−65 ° C. or higher, the effect of eliminating hysteresis by heating can be secured. Further, by setting the heating temperature to Tg−10 ° C. or less, the resin does not melt and the molded surface shape can be maintained. Moreover, the effect of an annealing process can be made sufficient by making the said heating into 24 hours or more, and yellowing can be suppressed by making it into 168 hours or less.

In addition, Tg said by this application is a glass transition temperature, and means the value measured with the temperature increase rate of 10 degrees C / min by the differential scanning calorimetry based on the measuring method JISK7121.

In particular, in a multilayer array lens, due to the above-described hysteresis related to expansion and contraction, the difference in the pitch between the lens elements in the direction perpendicular to the optical axis becomes an optical axis shift, which adversely affects the optical performance. Therefore, by substantially eliminating the hysteresis, it is possible to suppress the irreversible optical axis shift and maintain the desired optical performance by substantially changing the pitch interval due to the temperature change of the lens elements of the array lens. .

1A is a cross-sectional view of an imaging apparatus including an array lens according to an embodiment, and FIG. 1B is a plan view of the array lens shown in FIG. 1A. 2A and 2B are conceptual sectional views of a molding die for molding an array lens. 3A to 3E are diagrams for explaining the manufacturing process of the array lens. It is a conceptual diagram explaining the heating apparatus used for the heat treatment process among the manufacturing processes of an array lens. It is a figure explaining the Example of an array lens. It is a figure explaining the comparative example with respect to the array lens of an Example.

Hereinafter, an array lens and the like according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1A and 1B, the stacked array lens unit 100 is incorporated in the imaging apparatus 1000.

The illustrated laminated array lens unit 100 is a laminated body in which a plurality (specifically, two) of

array lenses

10 and 20 are stacked, and is used as a compound eye optical system. The first and

second array lenses

10 and 20 are square plate-like members extending in parallel to the XY plane, and are stacked in the Z-axis direction perpendicular to the XY plane and joined to each other.

In addition to the array lens unit 100 described above, the imaging apparatus 1000 includes a sensor array 60 having a plurality of detection units (sensor elements) 61 provided corresponding to the individual composite lenses 1a constituting the array lens unit 100. And an image processing unit 65 that performs image processing conforming to the visual field division method or the super-resolution method on the image signals detected by the sensor array 60. Here, the array lens unit 100 is housed in a rectangular frame-like case 50 joined to the sensor array 60.

In the array lens unit 100, the first array lens 10 on the object side is an integrally molded product made of resin and has a rectangular (substantially square in the illustrated example) outline when viewed from the central axis AX direction or the Z-axis direction. The first array lens 10 includes a plurality of lens elements 10a, each of which is an optical element, and a support portion 10b that connects the plurality of lens elements 10a. The plurality of lens elements 10a constituting the first array lens 10 are two-dimensionally arranged on square lattice points (16 × 4 × 4 in the illustrated example) arranged in parallel to the XY plane. Each lens element 10a has a first optical surface 11a that is convex on the first main surface 10p on the object side, and a second optical surface 11b that is concave on the second main surface 10q on the object side. Both

optical surfaces

11a and 11b are aspherical surfaces, for example. The support portion 10b is a flat plate-like portion, and includes a plurality of peripheral portions 10c so as to surround each lens element 10a.

The second array lens 20 on the image side is an integrally molded product made of resin and has a rectangular (substantially square in the illustrated example) outline when viewed from the central axis AX direction. The second array lens 20 includes a plurality of lens elements 20a, each of which is an optical element, and a support portion 20b that connects the plurality of lens elements 20a. The plurality of lens elements 20a are two-dimensionally arranged on square lattice points (16 × 4 × 4 in the illustrated example) arranged in parallel to the XY plane. Each lens element 20a has a first optical surface 21a that is concave on the first main surface 20p on the object side, and a second optical surface 21b that is convex on the second main surface 20q on the image side. Both

optical surfaces

21a and 21b are aspherical surfaces, for example. The support portion 20b is a flat plate-like portion and includes a plurality of peripheral portions 20c so as to surround each lens element 20a.

The first and

second array lenses

10 and 20 are aligned and bonded or bonded to each other with an adhesive such as a photo-curable resin. By such joining or adhesion, an array lens unit 100 including a large number of synthetic lenses 1a arranged two-dimensionally in a matrix is obtained. The optical axis OA of each synthetic lens 1a is parallel to the entire central axis AX. The plurality of synthetic lenses 1a arranged two-dimensionally on the lattice points corresponds to a single-eye lens of a field division method or a super-resolution method. Here, the field division method means that images of different fields of view formed by the respective composite lenses 1a, which are individual compound optical systems, are joined together by image processing (specifically, digital data processing). This is a method for obtaining one image. The super-resolution method is a method of obtaining one high-resolution image by image processing from images of the same field of view formed by the respective composite lenses 1a that are individual compound optical systems.

The first and

second array lenses

10 and 20 are heat-treated at a temperature of Tg−65 ° C. or higher and Tg−10 ° C. or lower for 24 hours or longer and 168 hours or shorter after molding, where the glass transition temperature of the resin is Tg. Has been given. As a result, the first and

second array lenses

10 and 20 are substantially free from hysteresis related to expansion and contraction with respect to the distance d between the optical axes OA of the

lens elements

10a and 20a. For example, the heat treatment is performed on the optical axes OA for two pairs of lens elements 10a that are farthest apart from each other with respect to different reference directions (in the present embodiment, the X-axis direction and the Y-axis direction) among the lens elements 10a constituting the array lens 10. The distances d1 and d2 (for example, unit mm) and the hysteresis of the temperature fluctuation with respect to the diagonal direction are substantially eliminated.

The array lens unit 100 is subject to calibration for image processing when the camera is used because the pitch between the optical axes varies due to temperature rise. Through a series of operations in calibration, for example, for the focus (Z-axis direction), the focus calculated based on the in-focus position extracted from the images close to the focus extracted from the plurality of image signals, the defocus amount, and the like. The amount of difference from the focal position is calculated, and correction information unique to the array lens unit 100 is obtained. Similarly, with respect to the deviation in the X-axis direction and the Y-axis direction, correction information unique to the array lens unit 100 is obtained by calibration.

An incident aperture plate 45 fixed by adhesion to the case 50 or the like is disposed on the object side of the case 50 that houses the array lens unit 100. Although a detailed description is omitted in the case 50 and the entrance diaphragm plate 45, a large number of openings are formed corresponding to the lens elements 10a and the like. A thin light-shielding diaphragm plate may be provided between the first array lens 10 and the second array lens 20 or on the image side of the second array lens 20.

Hereinafter, a method for manufacturing the array lens unit 100 will be described. The manufacturing process of the array lens unit 100 includes a molding process, a heat treatment process, a coating process, and a lamination process.

[Molding process]
First, the first and

second array lenses

10 and 20 are molded. The first array lens 10 and the like are formed by injection molding.

FIG. 2A is a diagram for explaining a mold for molding the first array lens 10. The mold apparatus 70 includes a first mold 71 and a second mold 72. The first mold 71 and the second mold 72 are mold-matched at the mold-matching surface PL, and a cavity 70 a is formed between the

molds

71 and 72. A transfer surface 71c for transferring the shape of the first array lens 10 on the first main surface 10p side is formed on the first mold 71 so as to face the cavity 70a, and the second mold 72 has a second mold 72. A transfer surface 72c for transferring the shape of the first array lens 10 on the second main surface 10q side is formed. The transfer surfaces 71c and 72c have a plurality of

optical transfer portions

71g and 72g arranged two-dimensionally at a part thereof in order to transfer the

optical surfaces

11a and 11b of the lens element 10a. In the first mold 71, the mold part 71i forming the transfer surface 71c is integrally formed, and in the second mold 72, the mold part 72i forming the transfer surface 72c is formed integrally. Has been. In the mold apparatus 70, a gate GA communicating with the cavity 70a is formed. In this case, the gate GA is disposed not on the center of the transfer surfaces 71c and 72c but on the side, and injection molding is performed by a side gate method.

FIG. 2B is a conceptual cross-sectional view illustrating the overall structure of the mold apparatus 70. The runner RA is connected to the cavity 70a of FIG. 2B through the gate GA, and the runner RA is connected to the sprue SP on the resin supply side. As a result, the molten resin J from the sprue SP obtained by melting the thermoplastic resin fills the runner RA and fills the cavity 70a through the gate GA. By separating the first mold 71 and the second mold 72 after cooling the molten resin J, a sprue portion 81 corresponding to the sprue SP, a runner portion 82 corresponding to the runner RA, and a gate corresponding to the gate GA. A molded product 80 including the portion 83 and the array lens body 84 corresponding to the cavity 70a is formed. Here, the gate section 83 is subjected to gate cut processing, and the first array lens 10 is obtained by the array lens body 84 at the tip of the gate section 83.

The second array lens 20 is also molded by the same method as the first array lens 10. That is, the second array lens 20 is also manufactured by injection molding a thermoplastic resin by a side gate method.

[Heat treatment process (annealing process)]
Next, heat treatment is performed on the first array lens 10 in the heat treatment step. Specifically, as shown in FIG. 3A, the first array lens 10 is subjected to heat treatment using a thermostatic bath M1 or the like. The heating condition is that the temperature is Tg−65 ° C. or higher and Tg−10 ° C. or lower and is 24 hours or longer and 168 hours or shorter when the glass transition temperature of the resin that is the material of the first array lens 10 is Tg. The heat treatment is more preferably Tg−65 ° C. or higher and Tg−10 ° C. or lower for 48 hours or longer and 168 hours or shorter. As shown in FIG. 4, the thermostatic chamber M <b> 1 includes a heating chamber 91 having a heat insulating wall, a pair of heaters 92 that raise the temperature in the heating chamber 91, a temperature sensor 93 that measures the temperature in the heating chamber 91, and a heating A decompression device 94 that decompresses the inside of the chamber 91 and a control device 95 that controls the operation of each unit 92, 93, 94 are provided. The control device 95 operates the heater 92 while monitoring the output of the temperature sensor 93 to maintain the inside of the heating chamber 91 at a predetermined temperature between Tg−65 ° C. and Tg−10 ° C. The first array lens 10 is placed on a shelf 91a in the heating chamber 91, and is subjected to heat treatment (annealing treatment) under the above conditions. In addition, since the inside of the heating chamber 91 is decompressed by the decompression device 94, it is a kind of vacuum container.

By the heat treatment process, in the first array lens 10, the hysteresis related to expansion and contraction is substantially eliminated with respect to the interval between the optical axes OA of the lens elements 10a. This is because molding distortion due to flow of the chain resin composition, molding distortion due to residual stress due to curing shrinkage, and the like are released by heating. The heating conditions in the heat treatment step can be different depending on the type of resin, and are appropriately selected from the above condition range so as to obtain a hysteresis elimination effect by heating.

Note that the second array lens 20 is also heat-treated by the same method as the first array lens 10, whereby the hysteresis related to expansion and contraction with respect to the interval between the optical axes OA of the lens elements 20a is substantially eliminated. When an array lens unit is configured by stacking two array lenses, the light of each lens element 10a of the first array lens 10 is eliminated by eliminating the hysteresis of both the first array lens 10 and the second array lens 20. The axis OA and the optical axis OA of each lens element 20a of the second array lens 20 are displaced in substantially the same manner when the temperature changes, and the mutual eccentricity of each lens element 10a and each lens element 20a can be suppressed, and the optical performance can be suppressed. Deterioration can be suppressed. In addition, it is more preferable that the two array lenses are made of the same material having the same optical characteristics. In this case, mutual eccentricity can be prevented.

Further, the heat treatment step is preferably performed after the molding step and before other processing (in the present embodiment, before the coating step). Thereby, it is possible to prevent the pitch fluctuation from affecting other processing.

In addition, when the array lens that has undergone the heat treatment process repeatedly expands and contracts due to temperature changes, the maximum optical axis distance between the lens elements is Lmax, and the maximum optical axis at the same temperature when the temperature rises and falls When the difference in distance is δ, it is preferable that the following conditional expression is satisfied.
δ ≦ Lmax / 3750
When the difference δ in the maximum optical axis distance between the lens elements satisfies the above formula, the positional fluctuation due to expansion and contraction due to temperature change is small, for example, the linear expansion coefficient is about 2.4 × 10 ⁻⁶ [K ⁻¹ ]. This sensor array can be easily corrected by image processing, and processing such as super-resolution becomes easy. The maximum inter-optical axis distance Lmax in the case such as FIG. 1B, when the maximum value of the distance between the optical axes of the Y-direction d1, X direction the maximum value of the distance between the optical axis and d2, {(d1 ² + D2 ² ) ^1/2 }, and the difference δ in the maximum distance between the optical axes corresponds to the variation in Lmax.

[Coating process]
Next, a coating such as an antireflection film is applied to the surface of the first array lens 10. Specifically, as shown in FIG. 3B, a single-layer or multilayer thin film is formed on the surface of the first array lens 10 using a vapor deposition apparatus M2 or the like. Thereby, an antireflection effect is imparted to the

optical surfaces

11 a and 11 b of the first array lens 10.

The second array lens 20 is also coated by the same method as the first array lens 10.

[Lamination process]
Next, the molded first and

second array lenses

10 and 20 are laminated.
The second array lens 20 is positioned and stacked above the first array lens 10. At this time, as shown in FIG. 3C, an adhesive B such as a photocurable resin is applied in advance on the support portion 10b of the first array lens 10, and as shown in FIG. 3D, the first array lens is applied. 10 are stacked by aligning and overlapping with the second array lens 20.

Next, as shown in FIG. 3E, the adhesive is cured by irradiating the first array lens 10 or the second array lens 20 with ultraviolet rays. Thereby, the array lens unit 100 fixed in a state where the first and

second array lenses

10 and 20 are laminated is obtained. The array lens unit 100 and the sensor array 60 shown in FIG. 1A and the like are housed in a case 50, and an imaging device 1000 is obtained.

In the above description, the adhesive B is not applied on the first array lens 10 before the first and

second array lenses

10 and 20 are stacked, but after the first and

second array lenses

10 and 20 are stacked. An adhesive may be applied. Further, an adhesive may be applied to the second array lens 20 side. In addition, the array lens unit 100 is housed in the case 50 after the first and

second array lenses

10 and 20 are stacked. However, the first and

second array lenses

10 and 20 are individually positioned and housed in the case 50. Thereafter, the imaging apparatus 1000 may be assembled by bonding.

According to the array lens manufacturing method and the like, the heat treatment is performed under the above conditions, so that the molding distortion of the first and

second array lenses

10 and 20 and the array lens unit 100 is relieved or eliminated by releasing the stress. As a result, the pitch variation in the direction perpendicular to the optical axis between the

lens elements

10a and 20a with respect to the temperature change becomes substantially the same at each temperature, and an array lens and an array lens unit in which hysteresis related to expansion and contraction is substantially eliminated can be obtained. As a result, for example, even if the camera continues to be used and the temperature rises, the deviation amount of the

individual lens elements

10a and 20a from the desired pixel becomes stable and can be easily corrected by image processing, super-resolution, etc. Can be processed. Since the array lens unit 100 is used as an imaging system lens, it can be corrected by image processing even if the resin is excessively heated to reduce distortion and the resin is slightly deteriorated and yellowed, so that the heating condition is higher than that of the optical pickup system lens. The degree of freedom can be increased. By setting the heating temperature to Tg−65 ° C. or higher, the effect of eliminating hysteresis by heating can be secured. Further, by setting the heating temperature to Tg−10 ° C. or less, the resin does not melt and the molded surface shape can be maintained.

On the other hand, if the heat treatment process is not performed after molding, hysteresis regarding expansion and contraction remains, and due to the difference between the temperature rise and the temperature drop, the distance between the optical axes of the lens elements (pitch) is different even at the same temperature, Deviation occurs. For example, in the case of a 4 × 4 array lens of 10 mm square, the thickness is about 0.5 mm, the pitch between the optical axes of the lens elements is about 2 to 3 mm, and hysteresis regarding expansion and contraction remains in the array lens. The effect of pitch deviation is increased.

〔Example〕
Hereinafter, examples of the present embodiment will be described.
APL5514ML (made by Mitsui Chemical Co., Ltd.) and ZEONEX E48R (made by Nippon Zeon Co., Ltd.), which are cycloolefin polymers, are used as materials, and a disk-shaped flat plate having a diameter of 11 mm and a thickness of 3 mm is prepared by injection molding. Then, after the molding, heat treatment was performed with various heating temperatures and heating times as shown in Table 1 below. Thereafter, heating and cooling were performed at a temperature of 25 ° C. to 90 ° C. at 0.5 ° C./min as one cycle, and two cycles (first cycle and second cycle) were repeated. During these two cycles, using the thermal / stress / strain measuring device EXSTAR TMA / SS6000 (manufactured by Hitachi High-Tech Science Co., Ltd.), the temperature increases at 25 ° C to 85 ° C in 10 degree increments at each temperature rise and fall. Was measured for linear expansion. Yellowing was measured by a Hitachi spectrophotometer U-4100 in accordance with test method ASTM D-1003.
Evaluation criteria for hysteresis related to stretching and yellowing of the material are as follows. Regarding hysteresis, when the difference in thickness measurement values is less than 0.5 μm, it is represented by the symbol ◎, when it is 0.5 or more and less than 0.8 μm, it is represented by the symbol ○, and when it is 0.8 μm or more, it is represented by the symbol ×. did. Moreover, 90% or more of the yellowing was set as symbol ◯, and less than 90% was set as symbol x.
Table 1 shows the results.

As shown in Table 1, when the glass transition temperature is Tg, when a heat treatment process is performed in which the heat treatment is performed at a temperature of Tg−65 ° C. or more and Tg−10 ° C. or less for 24 hours or more and 168 hours or less, repeated heating and cooling are performed. At that time, it was found that the dimensional difference at the same temperature could be suppressed within an allowable range, the hysteresis could be eliminated, and yellowing would not occur. In addition, Tg of APL5514ML is 147 degreeC, and Tg of ZEONEX E48R is 139 degreeC. In addition, it was found that if the time is 48 hours or longer and 168 hours or shorter, the dimensional difference at the same temperature can be further reduced even when heating and cooling are repeated.

In addition, for the sample of APL5514ML, the sample subjected to the heat treatment step at 90 ° C. (Tg−57 ° C.) for 48 hours and the sample not subjected to the heat treatment were heated from 25 ° C. to 90 ° C. at 0.5 ° C./min. Cooling was repeated for two cycles (first cycle and second cycle), and changes in expansion and contraction were confirmed.

FIG. 5 shows the change in linear expansion of the sample after the heat treatment process. In FIG. 5, the horizontal axis indicates the temperature of the sample, and the vertical axis indicates the displacement in the thickness direction of the sample. As shown in the figure, in both the first cycle and the second cycle, the amount of variation in the temperature change of the sample was substantially the same, and the linear expansion coefficient (ppm) was substantially the same. That is, it can be seen that the hysteresis in the temperature change is substantially eliminated.

FIG. 6 shows the change in linear expansion of the sample that was not subjected to the heat treatment step. As shown in FIG. 6, in the first cycle, the displacement of the sample at the time of temperature rise and that at the time of temperature fall greatly differed, and the linear expansion coefficient was not the same. That is, it can be seen that there is a hysteresis in the temperature change.

The array lens according to the present embodiment has been described above, but the array lens according to the present invention is not limited to the above. For example, in the above-described embodiment, the shapes and sizes of the first and second

optical surfaces

11a, 11b, 21a, and 21b can be appropriately changed according to applications and functions. Further, although the outer shape of the first and

second array lenses

10 and 20 is a quadrangle, it may be other shapes such as a circle.

Moreover, in the said embodiment, although the 1st and

2nd array lens

10 and 20 was formed using the thermoplastic resin, even if it forms using other resin materials, such as a thermosetting resin and a photocurable resin. Good.

In the above embodiment, the first and

second array lenses

10 and 20 are molded by injection molding, but may be molded by other molding methods such as molding or press molding.

In the above embodiment, the coating process is performed after the heat treatment process, but the coating process may not be performed. Moreover, you may perform another process instead of a coating process.

In the above embodiment, the heat treatment step is performed before the first and

second array lenses

10 and 20 are bonded. However, the heat treatment step may be performed after the bonding.

In the above-described embodiment, two array lenses are stacked. However, only one single layer may be used without stacking. Further, three or more array lenses may be laminated.

In the above embodiment, the decompression device 94 is provided in the thermostatic chamber M1, but the decompression device 94 may not be provided.

Claims

A molding step of integrally molding an array lens formed with a plurality of lens elements two-dimensionally arranged in a direction orthogonal to the optical axis and a support portion for connecting the plurality of lens elements;
After the molding step, the array lens has a heat treatment step of performing a heat treatment at a temperature of Tg-65 ° C. to Tg-10 ° C. for 24 hours to 168 hours when the glass transition temperature is Tg. Manufacturing method.
The method of manufacturing an array lens according to claim 1, wherein the heat treatment step is performed after the molding step and before another processing.
The method for producing an array lens according to claim 1 or 2, wherein the resin material is a cycloolefin polymer.
The array lens manufacturing method according to any one of claims 1 to 3, wherein the array lens satisfies the following conditional expression when expansion and contraction associated with a temperature change are repeated.
δ ≦ Lmax / 3750
However,
Lmax: Maximum optical axis distance between lens elements δ: Difference in maximum optical axis distance at the same temperature when temperature rises and when temperature falls
A resin-made array lens in which a plurality of lens elements arranged two-dimensionally in a direction perpendicular to the optical axis and a support portion for connecting the plurality of lens elements are formed,
An array lens that satisfies the following conditional expression when it repeatedly expands and contracts due to temperature changes.
δ ≦ Lmax / 3750
However,
Lmax: Maximum optical axis distance between lens elements δ: Difference in maximum optical axis distance at the same temperature when temperature rises and when temperature falls
The array lens according to claim 5, wherein the material of the array lens is a cycloolefin polymer.
An array lens unit in which a plurality of array lenses according to claim 5 or 6 are laminated.
The array lens unit according to claim 7, wherein the stacked array lenses are two, and are formed of a material having the same optical characteristics.