JP2007254203A - Method for strengthening multi-lens array - Google Patents

Abstract

The present invention provides a multilens array strengthening method capable of uniformly strengthening the entire surface and improving heat resistance and the like.
A lens unit having a plurality of small lenses arranged in a matrix.
Are immersed in a substantially vertical position with respect to the liquid surface LS of the molten salt solution LQ accommodated in the strengthening treatment tank 20, and a large number of small lenses 12a are included in the molten salt solution LQ. The turning process in which the surface of the formed lens portion 12 is directed toward the liquid surface LS of the molten salt solution LQ, and the surface of the lens portion 12 of the multi-lens array 10 is directed in the direction of the liquid surface LS of the molten salt solution LQ. Salt solution L
A swinging step of swinging in the horizontal direction along the liquid surface LS of Q, a pulling-up step of pulling up the strengthened multi-lens array 10 from the molten salt solution LQ, and the multi-lens array 10
The multi-lens array 10 is reinforced by a cooling process in which slow cooling and natural cooling are performed.
[Selection] Figure 2

Description

The present invention relates to a method for strengthening a multi-lens array used in an electro-optical device such as a projector.

In the projector, light emitted from the illumination optical system is modulated according to image information (image signal) by a liquid crystal light valve or the like, and an image is displayed by projecting the modulated light on a screen.
In general, the illumination optical system of the projector is provided with a first multi-lens array and a second multi-lens array for the purpose of making the intensity distribution of light irradiating the liquid crystal light valve substantially uniform. Each multi-lens array includes a large number of small lenses arranged in a matrix on a base portion having a substantially rectangular outer shape, and the light bundle emitted from the light source device is reflected by the large number of small lenses of the first multi-lens array. After being divided into a number of partial beam bundles and passing through a second multi-lens array comprising a number of small lenses corresponding to the number of small lenses of the first multi-lens array,
It is superimposed on the liquid crystal light valve via a superimposing lens.

These multi-lens arrays are press-molded using a translucent glass substrate to prevent deformation of the light bundle emitted from the light source device due to heat and deterioration over time and to ensure stable display quality. Manufactured by. Furthermore, the press-molded multi-lens array
In order to further reduce cracks and breakage due to heating during use, strengthening treatment by ion exchange is performed, and mechanical strength and heat resistance strength may be improved.
As a strengthening treatment method by ion exchange, a chemical strengthening method for a glass disc in which a glass disc is immersed in a chemical strengthening treatment solution using a jig and subjected to a chemical strengthening treatment has been proposed (for example, see Patent Document 1). .

JP-A-7-176045

However, when performing the strengthening process by ion exchange, it is necessary to bring the entire surface of the multi-lens array to be strengthened into contact with the strengthening process liquid. However, in the multi-lens array, a large number of small lenses arranged in a matrix are connected so that a concave portion is formed at the boundary between adjacent lens surfaces. For this reason, when the multi-lens array is immersed in the tempering treatment liquid, bubbles entrained in the recess remain, and the tempering treatment liquid does not come into contact with the bubble portions, so that uniform tempering treatment quality cannot be obtained. Further, since the strengthening treatment liquid is at a high temperature (about 300 ° C. to 600 ° C.), it is required to immerse the multi-lens array in the strengthening treatment liquid so that the strengthening treatment liquid is not scattered.

Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for strengthening a multi-lens array in which a uniform strengthening process can be performed on the entire surface and heat resistance and the like are improved.

In order to solve the above problems, the multilens array strengthening method of the present invention is a method of strengthening a multilens array in which a large number of small lenses are integrally formed on one surface with a strengthening treatment liquid, A dipping step of immersing the multi-lens array in the strengthening treatment liquid in a state where the surface on which the plurality of small lenses are formed is substantially perpendicular to the liquid surface of the strengthening treatment solution; A turning step of directing the surface of the multi-lens array on which the plurality of small lenses are formed in the direction of the liquid surface of the strengthening treatment liquid.

According to this, when the multi-lens array is immersed in the strengthening treatment liquid, the surface on which the multiple lenses of the multi-lens array are formed is kept substantially perpendicular to the strengthening treatment liquid surface. By immersing (immersion process), scattering of the tempering treatment liquid due to resistance during immersing can be minimized, and various adverse effects on workers and work environments caused by the tempering treatment liquid heated to a high temperature can be prevented. Moreover, when the multi-lens array is immersed in the reinforced treatment liquid by directing the surface on which the multiple lenses of the multi-lens array are formed in the reinforced treatment liquid, to the liquid surface of the reinforced treatment liquid (swivel process), Air bubbles that enter and remain in the recesses formed at the boundaries of many small lenses are removed from the recesses, and the entire surface of the multi-lens array comes into contact with the strengthening solution, so that the entire surface is uniformly strengthened. Thus, a multi-lens array with improved heat resistance and the like is obtained.

The multilens array strengthening treatment method of the present invention is characterized in that an immersion speed for immersing the multilens array in the strengthening treatment liquid is 20 to 30 cm / min.
According to this, the immersion speed for immersing the multi-lens array in the strengthening treatment liquid is 20-30 c.
By being m / min, uniform reinforcement processing can be performed on the entire surface of the multi-lens array. When the immersion speed exceeds 30 cm / min, air is entrained in a large number of small lenses formed on one surface of the multi-lens array, and bubbles are likely to be generated in the concave portions formed at the boundary portions of the small lenses. On the other hand, when the immersion speed is less than 20 cm / min, a temperature difference is generated between the region immersed in the strengthening treatment liquid and the region not yet immersed, leading to cracking of the multi-lens array.

Further, in the multilens array strengthening method of the present invention, after the turning step, the multilens array is in a state in which the surface on which the plurality of small lenses are formed faces the liquid surface direction of the strengthening treatment liquid. A rocking step of rocking in the horizontal direction along the liquid surface of the strengthening treatment liquid is further provided.

According to this, after the turning step, the surface on which the multiple small lenses of the multi-lens array are oriented in the liquid surface direction of the tempering treatment liquid, is swung in the horizontal direction along the liquid surface of the tempering treatment liquid. By moving, when the multi-lens array is immersed in the tempering treatment liquid, minute bubbles remaining in the recesses formed at the boundary portions of many small lenses are more easily removed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the structure of the multi-lens array subjected to the reinforcement process will be described.

In a projector that is incorporated and used, the multi-lens array is generally emitted from a first multi-lens array that divides a light beam emitted from a light source device into a plurality of partial beam bundles, and the first multi-lens array. And a second multi-lens array that aligns the central axis of each of the partial light beams substantially parallel to the system optical axis of the projector, and has a function of making the light intensity distribution substantially uniform. .

FIG. 1A is a schematic front view of a multi-lens array, and FIG.
It is a cross-sectional schematic diagram in A surface, FIG.1 (c) is a cross-sectional schematic diagram in the BB surface of the same figure (a). The multi-lens array shown in FIG. 1 illustrates the first multi-lens array.
In FIG. 1, the multi-lens array 10 is made of a transparent glass material (glass material) and includes a base portion 11 and a lens portion 12. As the glass material, optical glass such as white plate glass or quartz glass can be used.

The base portion 11 is formed of a plate body having a substantially rectangular outer shape, the lens portion 12 is formed on one flat surface 11a, and the other surface has a flat flat surface 11b. The flat surfaces 11a, 1
Reference numeral 1b denotes a reference surface for manufacturing, assembling, and the like of the multi-lens array 10 and has a positioning function when the multi-lens array 10 is incorporated in a casing of a liquid crystal projector.

The lens portion 12 protrudes from the flat surface 11 a into a substantially rectangular region of the one flat surface 11 a of the base portion 11 that is separated by a predetermined dimension from each outer edge of the substantially rectangular outer shape of the multi-lens array 10. A large number of small lenses 12a are arranged in a matrix. In the case of this embodiment, for example, a total of 48 small lenses 12a are formed, with six rows in the horizontal direction (x-axis direction) and eight rows in the vertical direction (y-axis direction).

Each of the small lenses 12a is a plano-convex eccentric lens having a substantially rectangular outline, and is a system optical axis 10a of the multi-lens array 10 (an axis that penetrates the center of the lens portion 12 in a substantially rectangular planar region in the thickness direction). ) And an x-axis (or y-axis) orthogonal to each other. A substantially rectangular outline of each small lens 12a is set so as to be almost similar to a liquid crystal light valve (liquid crystal panel) of a projector in which the multi-lens array 10 is used.
Further, the lens surfaces of the small lens 12a are connected so as to be continuous, and a concave portion α is formed at the boundary between adjacent lens surfaces.

Further, the thickness of the small lenses 12 a arranged along the x-axis direction is determined by the multi-lens array 10.
It is set to increase sequentially from the center side to the outer periphery side. Small lens 1
The thickness 2a is the maximum distance between the flat surface 11b and the lens surface of the small lens 12a. Small lens (outermost peripheral small lens) 12a formed on the outermost periphery of the rectangular region in the case of the present embodiment.
Is approximately 3.5 mm, for example, and the thickness (the distance between the flat surface 11 a and the flat surface 11 b) of the base portion 11 of the plate is approximately 2.5 mm. That is, the flat surface 11a of the base portion 11
The step amount (projection amount) with respect to the small lens 12a at the outermost periphery is about 1 mm.
The multi-lens array 10 configured as described above can be manufactured by supplying glass material to a mold having a pair of molds, heat-softening the glass material in the mold, and press molding.

Next, the strengthening process of the multi-lens array 10 will be described.
The strengthening treatment of the multi-lens array 10 is a method in which the multi-lens array 10 is immersed in a strengthening treatment liquid melted by heating, and the metal ions in the surface layer of the multi-lens array 10 are ion-exchanged with the metal ions in the strengthening treatment liquid. The ion exchange method is used. As the ion exchange method, a low temperature type ion exchange method, a high temperature type ion exchange method, a surface crystallization method, and the like are known. However, from the viewpoint of energy efficiency, or the deformation of the glass (multi-lens array 10) during ion exchange. It is preferable to use a low-temperature ion exchange method from the viewpoint of less generation.

In the low-temperature ion exchange method, the multi-lens array 10 is immersed in a tempering treatment liquid in a temperature region below the glass transition point (Tg), and alkali metal ions near the surface of the multi-lens array 10 are ionized therefrom. Substituting alkali metal ions with a large radius, and by increasing the volume of the ion exchange part, a strong compressive stress in the direction along the glass surface is generated on the surface layer of the glass (for example, a depth of about 20 to 30 μm), This is a method of increasing the mechanical strength and heat resistance strength.

As the strengthening treatment liquid used for ion exchange, a molten salt solution LQ melted by heating is used. Examples of the molten salt include molten salts such as potassium nitrate (KNO ₃ ), sodium nitrate (NaNO ₃ ), potassium carbonate (K ₂ CO ₃ ), and mixtures of these salts (for example, KNO ₃ + Na
NO ₃ , KNO ₃ + K ₂ CO ₃ ) molten salts, or Cu, Ag, Rb, Cs
And a molten salt mixed with an ionic salt such as the above.

The temperature of the molten salt solution LQ as the strengthening treatment liquid at the time of ion exchange is preferably a high temperature in order to promote ion exchange, but in order to prevent deformation of the multi-lens array 10, the multi-lens array 10 to be processed is processed. It is preferable that the glass transition point (Tg) or less. For example, a multi-lens array 1 made of a glass material having a glass transition point of 450 ° C. to 800 ° C.
When processing 0, the temperature of the molten salt solution LQ is about 300 ° C to 600 ° C.
The immersion time is several hours to several tens of hours, and is desirably about 18 hours in order to sufficiently obtain the effect of the strengthening treatment.

Further, when the multi-lens array 10 is strengthened, the temperature difference between the multi-lens array 10 and the molten salt solution LQ prevents the multi-lens array 10 from cracking or cracking, or the molten salt in the molten salt solution LQ. In order to prevent crystallization on the lens surface of the lens portion 12 (small lens 12a), it is desirable to preheat the multilens array 10 before immersing the multilens array 10 in the molten salt solution LQ. The preheating temperature is desirably a temperature difference of about 100 ° C. from the temperature of the molten salt solution LQ.

The strengthening process of the multi-lens array 10 includes a dipping step of immersing the multi-lens array 10 in a molten salt solution LQ as a strengthening treatment liquid, and a liquid surface of the molten lens solution LQ in the immersed molten salt solution LQ. , A turning step for pulling the multi-lens array 10 out of the molten salt solution LQ, and a cooling step for cooling the multi-lens array 10 lifted from the molten salt solution LQ.

FIG. 2A is a schematic diagram for explaining the immersion process of the multi-lens array, and FIG. 2B is a schematic diagram for explaining the turning process of the multi-lens array.

2A and 2B, the strengthening treatment tank 20 that performs the strengthening process of the multi-lens array 10 contains a molten salt solution LQ as a strengthening treatment liquid that is heated and melted in the treatment tank. ing.
The molten salt solution LQ is, for example, a salt solution in which potassium nitrate (KNO ₃ ) 99.995 wt% and anhydrous silicic acid 0.005 wt% are heated and melted. The temperature of the heated molten salt solution LQ is about 435 ° C to 445 ° C.

The multilens array 10 to be strengthened is set on a mounting jig (not shown) or the like, and the mounting jig is placed on the strengthening processing tank 20 (the liquid level LS of the molten salt solution LQ contained) by a hanging tool (not shown). Is retained. In addition, the hanging tool is relative to the liquid level LS of the molten salt solution LQ.
It is configured to be movable in the horizontal direction and the vertical direction, and further includes a mechanism for rotating, rotating and swinging the mounting jig.

The multi-lens array 10 is set on the mounting jig in order to prevent a portion where the multi-lens array 10 does not contact the molten salt solution LQ as much as possible.
2a is supported and held at a plurality of locations such as sandwiching the flat surface 11a and the flat surface 11b (see FIG. 1) of the base portion 11 outside the substantially rectangular region arranged in a matrix. Further, the hanger holds the surface of the lens unit 12 in which a large number of small lenses 12a of the multi-lens array 10 are arranged in a matrix in a state of being kept substantially perpendicular to the liquid level LS of the molten salt solution LQ. The

Prior to the dipping step of dipping the multi-lens array 10 in the molten salt solution LQ, the multi-lens array 10 is preheated. The multi lens array 10 is preheated by the multi lens array 1
This is performed to prevent the multi-lens array 10 from cracking due to a temperature difference between the multi-lens array 10 and the molten salt solution LQ when 0 is immersed in the molten salt solution LQ.

As shown in FIG. 2A, preheating of the multi-lens array 10 is performed by heating the molten salt solution L.
This is done using Q.
First, the lid of the strengthening treatment tank 20 in which the molten salt solution LQ is accommodated is removed to open the treatment tank. Then, the multi-lens array 10 is moved to a position about 50 cm above the liquid surface of the molten salt solution LQ accommodated in the opened strengthening treatment tank 20 and held at that position for about 0.5 to 1 hour. Done. When the preheating time is longer than 1 hour, productivity is lowered, and when it is shorter than 0.5 hour, cracking due to a temperature difference cannot be prevented. By this preheating, the temperature of the multi-lens array 10 is preheated to about 350 ° C.
The preheated multi-lens array 10 proceeds to an immersion process.

In FIG. 2A, in the dipping process, the entire pre-heated multi-lens array 10 is dipped in the molten salt solution LQ accommodated in the strengthening treatment tank 20.
The immersion of the multi-lens array 10 in the molten salt solution LQ is substantially the same as the surface LS of the lens portion 12 in which a large number of small lenses 12a of the multi-lens array 10 are arranged in a matrix with respect to the liquid surface LS of the molten salt solution LQ. This is done in a vertical state. By immersing in the molten salt solution LQ in a substantially vertical state, scattering of the molten salt solution LQ due to resistance at the time of immersion is minimized, and the worker and working environment by the molten salt solution LQ heated to high temperature Can prevent various harmful effects.

The immersion speed for immersing the multi-lens array 10 in the molten salt solution LQ is about 20 to 30 cm / min. When the immersion speed exceeds 30 cm / min, air is entrained in a large number of small lenses 12a of the multi-lens array 10 described later, and minute bubbles β are generated in the concave portions α formed at the boundary portions of the small lenses 12a. easy. In addition, if the immersion speed is less than 20 cm / min, a temperature difference occurs between a region immersed in the molten salt solution LQ and a region not yet immersed, leading to cracking of the multi-lens array 10.

In addition, when the multi-lens array 10 is immersed in the molten salt solution LQ, air entrained by a large number of small lenses 12a arranged in a matrix of the multi-lens array 10 is formed at the boundary portions of the large small lenses 12a. Enters the recessed portion α and remains as minute bubbles β. This phenomenon occurs due to variations in the entrance angle of the multi-lens array 10 immersed in the liquid surface LS of the molten salt solution LQ, the immersion speed, and the like, and it is estimated that the degree of occurrence is different.
And the multi lens array 10 immersed in the molten salt solution LQ transfers to a turning process.

As shown in FIG. 2B, in the swiveling process, in the molten salt solution LQ, the multi-lens array 10 is substantially parallel to the surface of the lens unit 12 on which a large number of small lenses 12a arranged in a matrix are formed. It is turned around the axis. Multi-lens array 10 shown in FIG.
Of the multi-lens array 10 includes a system optical axis 10a (see FIG. 1) and a base portion 11.
This is an axis substantially parallel to the surface of the lens portion 12 at the intersection 10b where the flat surface 11a intersects.
As a result, the surface of the lens portion 12 on which a large number of small lenses 12a are formed becomes the reinforcing treatment tank 20.
Is directed in the direction toward the liquid surface LS of the molten salt solution LQ contained in the liquid crystal, the minute bubbles β remaining in the concave portion α float up from the concave portion α toward the liquid surface LS, and are removed from the concave portion α.

The pivot axis of the multi-lens array 10 that is pivoted in the molten salt solution LQ is not limited as long as it is an axis that is substantially parallel to the surface of the lens portion 12 on which a large number of small lenses 12a are formed. As long as the surface of the lens part 12 on which the 12a is formed is directed in the direction along the liquid surface LS of the molten salt solution LQ accommodated in the strengthening treatment tank 20, any position may be used. The turning in the present embodiment includes rotation that rotates or reverses by circular movement in one direction, and rotation that turns or reverses by circular movement in the forward and reverse directions.
Further, the swiveled multi-lens array 10 may be swung about several times although the surface of the lens portion 12 may be directed at least once in the direction along the liquid surface LS of the molten salt solution LQ. Is preferred.

Then, in the turning step, the multi-lens array 10 swung in the molten salt solution LQ is further subjected to the molten salt on the surface of the lens portion 12 on which the multiple small lenses 12a of the multi-lens array 10 are formed after the turning step. It is preferable that the multi-lens array 10 is swung in the horizontal direction along the liquid surface LS in a state in which the solution LQ is directed in the direction along the liquid surface LS (rocking step). As a result, the minute bubbles β remaining in the recess α are more easily removed from the recess α. In addition,
The rocking speed for rocking the multi-lens array 10 is preferably about 20 to 30 cm / min, which is substantially the same as the immersion speed.

Then, the multi-lens array 10 that has completed the turning process is held in the molten salt solution LQ accommodated in the strengthening treatment tank 20 in a state of being immersed for about 18 hours. Thereby, alkali metal ions near the surface of the multi-lens array 10 are replaced with alkali metal ions having a larger ion radius, and the multi-lens array 10 is subjected to a strengthening process.
Then, the multi-lens array 10 that has been subjected to the strengthening process moves to a lifting process.

In the pulling process, the multi-lens array 10 subjected to the strengthening process is pulled up from the molten salt solution LQ stored in the strengthening tank 20.
The speed at which the molten salt solution LQ is pulled up is about 20 to 30 cm / min, which is substantially the same as the dipping speed. This lifting is performed by operating the hanger, and the multi-lens array 10 set on the mounting jig is substantially the same as when the preheating is performed, above the liquid level LS of the molten salt solution LQ accommodated in the strengthening treatment tank 20. Move to a position of about 50 cm and stop.
Then, the multi-lens array 10 pulled up from the molten salt solution LQ moves to a cooling process.

In the cooling process, the multi-lens array 10 pulled up from the molten salt solution LQ is gradually cooled and naturally cooled.
The slow cooling of the multi-lens array 10 is held and cooled for about one hour in a state where it moves to a position above the liquid level LS of the molten salt solution LQ and stops. Thereby, the multi-lens array 1
The temperature of 0 drops to about 300 ° C.

Then, after the slow cooling, the strengthening treatment tank 20 containing the molten salt solution LQ is covered, and natural cooling is performed until the temperature of the multi-lens array 10 returns to about room temperature.
In this cooling step, the multi-lens array 10 is gradually cooled and naturally cooled, so that the thermal distortion of the multi-lens array 10 can be suppressed.
Then, the multi-lens array 10 naturally cooled to about room temperature is removed from the hanger and the mounting jig, and the strengthening process of the multi-lens array 10 is completed.

A heat shock test by a water cooling method was performed on the multi-lens array 10 subjected to the reinforcement treatment as described above, and the effect of the reinforcement treatment was confirmed.
The heat shock test was performed using 20 multilens arrays 10 subjected to the strengthening process as samples. First, the multi-lens array 10 was heated in an oven having a furnace temperature of 190 ° C. for 1 hour. Then, the heated multi-lens array 10 is
It was taken out from the oven and immediately put into water having a water temperature of 20 ° C. As a result, sample 2
It was confirmed that there was no occurrence of cracks in all of the zero multi-lens arrays 10 and that the reinforcing treatment was sufficiently performed.

According to the multilens array enhancement processing method described above, the following effects can be obtained.

When the multi-lens array 10 is immersed in the molten salt solution LQ as the strengthening treatment liquid,
By immersing the surface of the lens portion 12 on which a large number of small lenses 12a arranged in a matrix form are kept substantially perpendicular to the liquid surface of the molten salt solution LQ (immersion step), Scattering of the molten salt solution LQ due to this resistance is minimized, and various adverse effects on workers and work environments caused by the molten salt solution LQ heated to a high temperature can be prevented.

In addition, the surface of the lens portion 12 on which a large number of small lenses 12a are formed in the liquid of the molten salt solution LQ is directed toward the liquid surface LS of the molten salt solution LQ (swivel process), whereby the multi-lens array 10
Is immersed in the molten salt solution LQ, the bubbles β entrained by a large number of small lenses 12a and entering the concave portions α formed at the boundary portions of the large number of small lenses 12a are removed from the concave portions α, and the multilens When the entire surface of the array 10 is in contact with the molten salt solution LQ, the entire surface can be uniformly strengthened, and the multi-lens array 10 with improved heat resistance and the like can be obtained.

Moreover, the immersion speed which immerses the multi lens array 10 in molten salt solution LQ is 20-30c.
By being m / min, uniform reinforcement processing can be performed on the entire surface of the multi-lens array 10. When the immersion speed is higher than 30 cm / min, when the multi-lens array 10 is immersed in the molten salt solution LQ, air is entrained by a large number of small lenses 12a formed in the lens portion 12, and the boundary of the small lenses 12a. The bubble β is likely to be generated in the recess α formed in the portion. In addition, if the immersion speed is less than 20 cm / min, a temperature difference occurs between a region immersed in the molten salt solution LQ and a region not yet immersed, leading to cracking of the multi-lens array 10.

In the above embodiment, the multi-lens array 10 to be reinforced is set on a mounting jig or the like and processed one by one. However, instead of the mounting jig, a basket or a net-like container is used. Alternatively, a large number of multi-lens arrays 10 may be set.

The multiple multi-lens array 10 in this case is a clip provided corresponding to the multiple multi-lens array 10 in, for example, a box-shaped basket or a net-like container. 11b (see FIG. 1) or a container having a cage or mesh shape, pressed by a flexible spring provided so as to press the opposite end faces of the rectangular base 11 from both sides Is held in a direction perpendicular to the bottom surface of the plate. Then, the dipping process, the turning process, and the like are performed on the entire basket or net-like container in the same manner as in the individual reinforcing treatment methods.
Thereby, although the large-sized reinforcement | strengthening process tank 20 is required, productivity of reinforcement | strengthening process improves significantly.

(A) is a front schematic diagram of a multi-lens array. (B) is a cross-sectional schematic diagram in the AA surface of the multi lens array shown to (a). (C) is a cross-sectional schematic diagram in the BB surface of the multi lens array shown to (a). (A) is a schematic diagram explaining the immersion process of a multi lens array. (B) is a schematic diagram explaining the turning process of a multi lens array.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Multi lens array, 10a ... System optical axis, 10b ... Intersection, 11 ... Base part,
11a, 11b ... flat surface, 12 ... lens part, 12a ... small lens, 20 ... strengthening treatment tank, LQ
... Molten salt solution as strengthening treatment liquid, LS ... Liquid surface of molten salt solution LQ, α ... recess, β ... air bubbles.

Claims (3)

A method of strengthening a multi-lens array in which a large number of small lenses are integrally formed on one surface with a strengthening treatment liquid,
An immersion step of immersing the multi-lens array in the strengthening treatment liquid in a state where the surface on which the plurality of small lenses are formed is maintained substantially perpendicular to the liquid surface of the strengthening treatment liquid;
A strengthening process for the multi-lens array, comprising: a turning step in which a surface of the multi-lens array in which the plurality of small lenses are formed is directed in a liquid surface direction of the strengthening process liquid. Method. In the reinforcement processing method of the multi lens array according to claim 1,
A multilens array strengthening method, wherein an immersion speed of immersing the multilens array in the strengthening solution is 20 to 30 cm / min. In the reinforcement processing method of the multi lens array according to claim 1 or 2,
After the turning process,
A swinging step of swinging the multi-lens array in a horizontal direction along the liquid surface of the strengthening treatment liquid in a state where the surface on which the plurality of small lenses are formed faces the liquid surface direction of the strengthening treatment liquid. ,
A multilens array reinforcement processing method, further comprising:

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