JP4907859B2 - Microlens array element design method - Google Patents

Description

The present invention relates to a method for designing a microlens array element.

  A microlens array is an optical element in which microlenses are arrayed, but a microlens that is a convex lens is a microlens corresponding to the arrangement of each microlens by condensing transmitted light for each microlens. It is used to efficiently illuminate such areas and increase the light utilization efficiency.

  As an example, in a “transmission type TFT liquid crystal projector”, liquid crystal driving units using TFTs are arranged in a liquid crystal panel in an array as a black matrix corresponding to the liquid crystal pixels. In order to increase the illumination efficiency of the illumination light, a microlens array is provided on the light incident side to the liquid crystal panel. It has been practiced that light is condensed in the vicinity of the matrix opening to reduce the “light blocking rate by the black matrix” of the illumination light, thereby improving the light utilization efficiency and displaying a bright image.

  In recent years, liquid crystal panels and the like have become more compact, and the light source lamps for illumination have been increased in power. As a result, the energy density of the light condensed on the liquid crystal pixel portion has increased, and “damage of the liquid crystal due to the condensed light energy is increased. ”Is increasing, and the tendency of the liquid crystal panel to have a short lifetime has appeared.

  In general, a microlens array is provided with a cover glass for protecting the microlens surface on the microlens surface side. Conventionally, the microlens array side and the cover glass generally have a “transparent adhesive”. When the illumination light passes through the adhesive layer, a part of the illumination light is absorbed by the adhesive layer, which is a cause of reducing the light utilization efficiency.

  Furthermore, since the lens surface of the microlens and the adhesive are in contact with each other, the “refractive index difference between the adhesive and the microlens at the contact portion” is reduced. It is necessary to make the lens surface curvature of the lens “larger than in the air”, and when trying to obtain a microlens with the desired lens diameter, the “lens surface height” increases, and the processing time of the microlens array There is also a problem that it becomes difficult to increase the manufacturing efficiency of the microlens array.

  A countermeasure for such a problem has not been known so far as the inventors know.

In view of the above, the present invention has an object to provide a novel design method of a microlens array element in order to realize a microlens array element that can effectively solve the above problems.

The microlens array element that is the object of the design method of the present invention is that “a condensing microlens having a function of condensing in a black matrix opening of a liquid crystal pixel in a liquid crystal panel corresponds to each liquid crystal pixel in the liquid crystal panel. The top of each microlens constituting the microlens array is a “plane part perpendicular to the optical axis”, and the diameter of the plane part is that of the black matrix. It is set smaller than the diameter of the opening . The flat portion at the top of the microlens is formed so as to alleviate excessive condensing of illumination light onto the liquid crystal pixels.

This microlens array element is integrated with the microlens array so that a “parallel plate-shaped cover glass for protecting the microlens” is substantially parallel to the microlens array on the microlens surface side of the microlens array. Provided .
The light condensing property by the microlens is relaxed by the plane portion at the top of each microlens, and the ratio of the area of the plane at the top of the microlens: s to the effective lens area of the microlens: S: s / S
Α, the distance between the plane portion and the cover glass: dt, and the diameter of the lens effective area: DL
Ratio: When dt / DL is β, the range of the tilt angle of the light beam tilted with respect to the microlens optical axis is ± 10 degrees, and the transmittance of the illumination light beam incident on each microlens as illumination light is 0. as will be .8 above, the parameters: alpha, determined the beta.

The microlens array element designed by the design method of claim 1 is a medium having a refractive index difference of 0.1 or more with respect to the material of the microlens array between the microlens array and the cover glass. The medium is a medium whose refractive index is smaller by 0.1 or more than the material of the microlens array (hereinafter the same) , and effectively increases the refractive action of the lens surface of the microlens at the boundary between the medium and the microlens. The medium is a transparent adhesive.

In the microlens array element is designed in the design method according to claim 2, the medium between the microlens array and the cover glass is: "substantially refractive index 1 has a" medium.
It between the microlens array and the cover glass Ru can also be a "substantial vacuum", it is also possible to "air"). Thus, the so-called “medium having a refractive index of 1” according to claim 2 is a concept including a vacuum state.

In the microlens array element designed by the design method according to claim 1, the planar portion of the top of each microlens in the microlens array has a refractive index of 0.1 or more than the material of the microlens array as described above. It is joined to the cover glass by a “small transparent adhesive” .

Thus, the adhesive used for joining the flat part of the top part of the microlens and the cover glass fills the space between the microlens array and the cover glass.

In the micro lens array element to be designed in the design method according to claim 2, between the microlens array and the cover glass "substantially refractive index: 1 having a" medium, the medium as "substantial vacuum" Alternatively, it may be “air”.

A microlens array element designed and manufactured by the above design method can be combined with a “liquid crystal panel having a black matrix” to constitute a liquid crystal panel unit.

That is, the light incident side of the liquid crystal panel, is designed by the above design method, the microlens array element manufactured provided, each microlens in the microlens array of the microlens array elements, and the individual liquid crystal pixels in the liquid crystal panel corresponding and is arranged, with each micro-lens has a function of condensing inside the black matrix opening portion of the liquid crystal pixels corresponding to "illumination light, the plane of the microlens tops, excessive condenser to the liquid crystal pixels of the illumination light It is formed so as to alleviate "a.

  In other words, the illumination light transmitted through the microlens is effectively condensed in the opening of the black matrix and effectively avoids the light shielding by the black matrix, but excessive condensing is mitigated by the action of the flat portion at the top of each microlens. Therefore, the light energy does not concentrate excessively on the minute area of the liquid crystal pixel.

In the designing method according to claim 1, the parameters: α, β are the conditions:
(1) β ≦ −5.3α ² + 1.7α + 2.1
To be satisfied .

In the design method according to claim 2, the parameters: α and β are the conditions:
(2) β ≦ −4.8α ² + 1.5α + 1.8
To be satisfied .

In addition, the space | interval: dt between the plane part of a microlens top part and a cover glass is an "actual mechanical space | interval."
The liquid crystal panel unit can form an antireflection film on the microlens array and the cover glass .

The conditions (1) and (2) will be described .
In condition (1), between the microlens array and the cover glass, a transparent adhesive having a refractive index difference of 0.1 relative to the material of the microlens array (with a refractive index of 0.1 relative to the material of the microlens array). In a case where the lens surface shape of the microlens is a spherical surface, the intensity of light transmitted through the liquid crystal panel unit is 1.

  If the top part of the spherical surface is flattened to be a flat part, the parameter α increases as the area of the flat part increases. At this time, the condition for the intensity of the light transmitted through the liquid crystal panel unit to be 0.8 or more, that is, “the condition that the parameters: α and β must be satisfied for the illumination light transmission efficiency to be 0.8 or more” Is the condition (1).

In condition (2), when the medium between the microlens array and the cover glass is substantially a medium having a refractive index of 1 (vacuum state or air), and the lens surface shape of the microlens is spherical, the liquid crystal The intensity of light transmitted through the panel unit is 1.
When the top portion side of the spherical surface is flattened to be a plane portion, the parameter α increases as the area of the plane portion increases. At this time, the condition for the intensity of the light transmitted through the liquid crystal panel unit to be 0.8 or more, that is, “the condition that the parameters: α and β must be satisfied for the illumination light transmission efficiency to be 0.8 or more” Is the condition (2).

  That is, if the shape of the entire microlens surface of the microlens array is a spherical shape, “the illumination light can be efficiently concentrated on the opening of the black matrix”, but in this way, the concentration is too strong and the liquid crystal receives it. Damage is great. The shape of the microlens surface is “referenced to the above spherical shape”, and the top is flattened to form a flat surface (so that the above-mentioned standard spherical shape is cut by the flat surface and the cut surface becomes the flat surface. When the area of the plane portion increases, the refracting surface portion (spherical surface portion) of the microlens decreases, and the degree of collection of illumination light by the lens action of the refracting surface portion decreases. By making α and β satisfy the conditions (1) and (2), the transmission efficiency is 0.8 or more as compared with the case of using “a microlens having a reference spherical shape without a flat portion at the top”. Can be realized.

Note that a decrease in parameter: α means that “the area of the planar portion of the top portion of the microlens becomes smaller and approaches a spherical shape”, and therefore, parameter: α cannot be brought close to 0 without limitation. The lower limit of the design parameter: α is set according to the condition that “the flat portion at the top of the microlens alleviates excessive condensing of illumination light onto the liquid crystal pixels”. As a guideline for the lower limit of the parameter: α, 0.001 can be mentioned.

Note that the use of a microlens array and a microlens array element to be designed are not limited to the liquid crystal panel unit, it can be used for various optical elements.

As described above, when the microlens array element manufactured according to the design method of the present invention is combined with a liquid crystal panel, the plane part of the top of each microlens alleviates excessive condensing of illumination light onto the liquid crystal pixels. Liquid crystal damage due to the concentration of light energy is effectively mitigated, and shortening of the life of the liquid crystal panel can be effectively reduced or prevented.

In the microlens array element manufactured according to the design method of claim 1, a medium having a refractive index difference of 0.1 or more with respect to the material of the microlens array is provided between the microlens array and the cover glass. Makes it possible to relatively increase the action of the refractive surface of the microlens, reduce the increase in curvature of the lens surface of the microlens, reduce the lens surface height, and reduce the processing time of the microlens array. Efficiency can be increased.

Moreover, in the microlens array element manufactured according to the design method of claim 2, the problem of light absorption by the adhesive is fundamentally caused by setting a substantial vacuum state or air between the microlens array and the cover glass. Can be solved.

The liquid crystal panel unit using the microlens array element manufactured according to the design method of the present invention has a long life and good light utilization efficiency by using the microlens array element of the present invention. Therefore, by using this liquid crystal panel unit for a liquid crystal projector, it is possible to display a bright and high quality image with a long life.

Embodiments of the invention will be described below.
FIG. 1 illustrates an example of the configuration of a liquid crystal panel unit .
In FIG. 1, reference numeral 10 denotes a liquid crystal, reference numeral 12 denotes a microlens array, reference numeral 14 denotes a cover glass, and reference numeral 17 denotes a black matrix.
The microlens array 12 is “one side (the lower surface in the drawing) is flat”, and a series of microlenses 121 are two-dimensionally arranged on the surface on the cover glass 14 side.

  The black matrix 17 is formed on one side of a transparent parallel substrate (not shown). The liquid crystal portions corresponding to the openings of the black matrix 17 are “liquid crystal pixels”. The liquid crystal 10 is sealed in a predetermined alignment state between a transparent parallel plate (not shown) on which the black matrix 17 is formed and a flat surface of the microlens array 12.

The microlens array 12 is formed by two-dimensionally arraying condensing microlenses 121 having the same shape, but the top 121A of each microlens 121 constituting the microlens array 12 is “perpendicular to the optical axis. It is referred to as “planar part” .
The “portion excluding the plane portion 121A” of the microlens 121 is a curved surface shape having a lens action, for example, “spherical shape”.

  The cover glass 14 provided on the microlens surface side of the microlens array 12 is for protecting the microlens 121 and has a “parallel plate shape”, and is substantially parallel to the microlens array 12. It is provided integrally with the microlens array 12. That is, the microlens array 12 and the cover glass 14 are integrated with each other to constitute a “microlens array element”. As a means for integrating the two, known appropriate means such as adhesion and glass bonding can be used.

In FIG. 1, “a gap portion between the microlens array 12 and the cover glass 14” indicated by reference numeral 15 is a medium having a refractive index difference of 0.1 or more with respect to the material of the microlens array 12 . The medium can have a refractive index of 1 substantially . In order to realize this, the gap portion 15 between the microlens array 12 and the cover glass 14 may be in a “substantially vacuum state”, or the gap portion 15 between the microlens array and the cover glass is air. It may be .

As shown in FIG. 1A, the microlens array 12 and the cover glass 14 may be integrated by being “arranged substantially in parallel with each other with the gap portion 15 therebetween”. as shown in, may be planar portion 121A of the microlens 121 top in the microlens array 12 is a "configuration which is joined to the cover glass 14".

"Joining the flat portion 121A and the cover glass 14 of the microlens 121 top" is may be the "adhesive bonding" may be "joined by glass bonding method" may be "joined by crimping".

  As shown in FIG. 1, when light (for the sake of simplicity, a parallel light beam) is incident from the side of the cover glass 14 (upper side of the drawing), the lens action of the microlens 121 is “other than the flat portion at the top of the lens surface”. The “curved surface portion” has a condensing effect, but the flat surface of the top of the microlens has no lens effect.

  Therefore, the light beam incident on the flat surface portion 121A of the microlens 121 is transmitted through the microlens 121 without being subjected to the lens action, but the light beam portion incident on the curved surface portion around the flat surface portion is opened by the lens function. Condensed near the area.

That is, the liquid crystal panel unit shown in FIGS. 1A and 1B includes a liquid crystal panel having a black matrix 17 and microlens array elements (microlens array 12 and cover glass 14 provided on the light incident side of the liquid crystal panel. The microlens 121 in the microlens array 12 of the microlens array element is an individual liquid crystal pixel (liquid crystal corresponding to the opening of the black matrix 17) in the liquid crystal panel. The microlens 121 has a “function of condensing illumination light into the black matrix opening of the corresponding liquid crystal pixel” and the flat portion 121A at the top of the microlens is “liquid crystal of illumination light”. It has the function of “relaxing excessive light collection on the pixel”.

The microlens array 12 and the cover glass 14 as possible out to film a "antireflection film". In the embodiment shown in FIG. 1, the microlens array 12 constitutes “a part of a liquid crystal panel”.

FIG. 2 shows a “conventional liquid crystal panel unit” for comparison . In order to avoid complications , the same reference numerals as those in FIG.
In FIG. 2, reference numeral 13 denotes a microlens array, reference numeral 131 denotes an individual microlens, and reference numeral 16 denotes a “transparent adhesive layer that bonds the microlens array 13 and the cover glass 14”.

  In the case of the liquid crystal panel unit of FIG. 2, each microlens 131 of the microlens array 13 has, for example, a spherical shape and has a condensing function, and the light beam incident on the microlens 131 is collected near the opening of the black matrix 17. Although the light is condensed, the light energy is concentrated at a high density in the portion indicated by reference numeral 100 in FIG. 2, and the liquid crystal panel 10 is greatly damaged by the concentrated light energy, and the life of the liquid crystal panel is shortened. .

  In addition, since the microlens array 13 and the cover glass 14 are bonded by the “transparent adhesive layer 16”, when the illumination light passes through the adhesive layer 16, a part is absorbed by the adhesive layer 16. This contributes to a decrease in light utilization efficiency.

  Further, since the lens surface of the microlens 131 and the adhesive layer 16 are in contact with each other, the “refractive index difference between the adhesive and the microlens” at the contact portion is reduced, so that a desired refractive action is realized on the microlens lens surface. Then, the lens surface curvature of the microlens 131 needs to be “larger than that in the air”. Therefore, when trying to obtain the microlens 131 having a desired lens diameter, the height of the lens surface increases. This increases the processing time of the lens array and causes a reduction in the manufacturing efficiency of the microlens array.

The liquid crystal panel unit shown in FIG. 1 can effectively solve these problems.
That is, each microlens 121 has a function of “condensing illumination light into the black matrix opening of the corresponding liquid crystal pixel”, and the planar portion 121A at the top of the microlens “excess condensing illumination light onto the liquid crystal pixel”. Therefore, the light energy is not excessively concentrated on a specific portion of the liquid crystal 10, and the damage to the liquid crystal 10 due to the concentration of the light energy can be effectively reduced.

  Further, if the medium between the microlens array 12 and the cover glass 14 is set to a “vacuum state or an air state”, light is not absorbed in the medium portion, and the refractive index difference between the microlens 121 and the medium is large. Therefore, the desired refractive power can be realized with “relatively small lens surface curvature”, and furthermore, since the top of the lens surface is a flat portion, the lens surface height itself of the microlens 121 is also small, and the microlens can be formed in a short time. In other words, the processing time of the microlens array is prolonged and the manufacturing efficiency of the microlens array is not reduced.

  Further, when the microlens array 12 and the cover glass 14 are bonded with a transparent adhesive, even if the refractive index difference is reduced and the curvature of the lens surface is increased, the top of the lens surface is a flat portion. The lens surface height itself of the microlens 121 can be reduced, and there is no “deterioration of the manufacturing efficiency of the microlens array due to a long processing time of the microlens array” as described above.

  Further, since the lens surface height of the microlens 121 is small, even when the microlens array 12 and the cover glass 14 are bonded, the adhesive layer can be made thin, and “light absorption by the adhesive” can be effectively reduced.

  As is apparent from the above description, the “illumination light” of each microlens 121 is adjusted by adjusting the ratio between the “curved surface portion having a lens action” and the “planar portion not having a lens action” of the microlens 121. Can be adjusted by adjusting the function of condensing the light into the black matrix opening of the corresponding liquid crystal pixel and the function of reducing excessive condensing of the illumination light to the liquid crystal pixel. It is possible to optimize so as to obtain efficient illumination while effectively mitigating.

Hereinafter, specific examples of the design method will be described. First, “reference examples” to be compared with the examples will be described. The reference example is an example of “conventional liquid crystal panel unit”. In order to avoid complications, the same reference numerals as in FIG. 2 are used.

"Reference example"
FIG. 3A shows “a configuration of one liquid crystal pixel portion” in the reference example. The microlens array 13 is formed by arranging microlenses 131 in a two-dimensional square matrix on a glass plate having a refractive index of 1.5, and the arrangement pitch of the microlenses 131 is 15.5 μm. Reference symbol Ax indicates the optical axis of the microlens 131.

  The microlens 131 has a lens effective diameter: 15.5 μm (= arrangement pitch), a lens surface height (height from a “reference surface” indicated by a broken line): 7.5 μm, and the lens surface has a spherical shape. The height from the surface on the liquid crystal 10 side of the microlens array 13 to the reference surface is 27.5 μm. The liquid crystal 10 has a layer thickness of 3.0 μm and a refractive index of 1.5.

  The surface of the microlens array 13 on the microlens 131 side and the cover glass 14 are bonded with a transparent adhesive 16. The adhesive 16 has a refractive index of 1.4 (that is, a refractive index difference with respect to the material of the microlens array 13: 0.1), and the distance between the top of the microlens 131 and the cover glass 14 is 5.0 μm. The opening diameter D of the opening of the black matrix 17 is 11.5 μm × 12.0 μm.

  FIG. 3B shows a state in which “a parallel light beam is incident from the cover glass 14 side” in the reference example. As shown in the figure, the parallel light flux is condensed on the vicinity 100 of the center of the opening of the black matrix 17 while being transmitted through the liquid crystal 10 by the condensing action of the micro lens 131.

In a state where the liquid crystal panel unit is actually used, the illumination light for illuminating the liquid crystal panel unit is “a state close to a parallel light flux”, but it is not a strict parallel light flux.
FIG. 3C shows a simulation result in the case where the light beam is incident from the side of the cover glass 14 assuming a “light beam in a state close to an actual illumination light beam”. Compared with the state of FIG. 3B, the “degree of light collection” of the light condensed on the opening of the black matrix 17 is slightly lower than that of FIG. Although the “diameter of the light beam transmitted through the portion” is larger than that in the case of FIG. 3B, the concentration state of the light energy is still high. The above assumed illumination light flux has a range of “tilt angle of the light beam tilted with respect to the optical axis” within ± 10 degrees.

  In the case of FIG. 3C in the reference example, the illumination light transmission efficiency (the intensity of light passing through the opening of the black matrix 17 / the intensity of light incident on the microlens 131) is set to a reference value of 1.

Hereinafter, specific examples of the liquid crystal panel unit using the microlens array element specifically designed by the design method of the present invention and produced according to the design are given as Examples 1 and 2.
FIG. 4 shows a “configuration of one liquid crystal pixel portion” in the first embodiment. In order to avoid complications, the same reference numerals as in FIGS. 1 and 3 are used for those which are not likely to be confused.
In FIG. 4A, the microlens array 12 is obtained by forming microlenses 121 on a glass plate having a refractive index of 1.5, and the arrangement pitch and effective diameter of the microlenses 121 are both of the reference example. And 15.5 μm.

  The microlens 121 is formed with a planar portion 121A perpendicular to the optical axis having a diameter of 4.2 μm at the top of the lens, and the lens surface height (height from the “reference plane” indicated by the broken line to the planar portion 121A) is 2. The curved surface portion around 3 μm and the flat surface portion 121A has a “spherical shape”. The height from the surface on the liquid crystal 10 side of the microlens array 12 to the reference surface is 32.7 μm. The liquid crystal 10 is the same as in the reference example.

  The medium between the surface of the microlens array 12 on the microlens 121 side and the cover glass 14 is an “air layer”. The distance between the flat surface 121A at the top of the microlens 121 and the cover glass 14 is 5.0 μm. The opening diameter of the opening of the black matrix 17: D (= 11.5 μm × 12.0 μm) is the same as the reference example.

  FIG. 4B shows a state in which a parallel light beam is incident from the cover glass 14 side in the first embodiment. As shown in the figure, the parallel light flux incident on the curved surface portion around the microlens 121 is condensed near the center of the opening of the black matrix 17 while being transmitted through the liquid crystal 10 by the condensing action of the curved surface portion of the microlens 121. To do. On the other hand, the light incident on the flat surface 121A at the top of the microlens 121 passes through the microlens 121 without being subjected to lens action, passes through the liquid crystal 10 as a parallel light flux, and passes through the opening of the black matrix 17.

  For this reason, “concentration of excessive light energy on a minute portion of the liquid crystal 10” is effectively avoided as compared with the case of the reference example, and damage to the liquid crystal is effectively reduced.

  FIG. 4C shows an incident from the cover glass 14 side on the liquid crystal panel unit of the first embodiment, assuming a “light beam in a state close to an actual illumination light beam (the same light beam used for the simulation in the reference example)”. The simulation result when it is made to show is shown. Compared with the state of FIG. 4B, in the state of FIG. 4C, the “degree of light collection” of the light condensed on the opening of the black matrix 17 is lower than in the case of FIG. “The diameter of the light beam transmitted through the opening of the black matrix 17” is larger than that in the case of FIG.

In the case of FIG. 4C of Example 1, the illumination light transmission efficiency was 0.97 with respect to the reference value of the reference example: 1.
That is, in the first embodiment, the transmission efficiency of illumination light is effectively reduced in the case of the reference example while effectively reducing excessive concentration of light energy on a specific portion of the liquid crystal 10 (a portion near the center of the opening of the black matrix 17). A value approximately equivalent to is obtained.

  In the case of Example 1, when an antireflection film was formed on the front and back surfaces of the cover glass 14 and the microlens surface of the microlens array 12, the transmission efficiency of illumination light was set to 1.04 with respect to the reference value of 1. I was able to improve.

  FIG. 5 shows a “configuration of one liquid crystal pixel portion” in the second embodiment. In order to avoid complications, the same reference numerals as in FIGS. 1 and 3 are used for those that are not likely to be confused. In FIG. 5A, the microlens array 12 is obtained by forming microlenses 121 on a glass plate having a refractive index of 1.5, and the arrangement pitch and effective diameter of the microlenses 121 are those of the reference example. And 15.5 μm.

  The microlens 121 is the same as that of the first embodiment, and a planar portion 121A perpendicular to the optical axis having a diameter of 4.2 μm is formed at the top of the lens, and the planar portion 121A is formed from the lens surface height (the “reference plane” indicated by the broken line). The height is 2.3 μm, and the curved surface portion around the planar portion 121A has the same spherical shape as that of the first embodiment. The height from the surface on the liquid crystal 10 side of the microlens array 12 to the reference surface is 32.7 μm as in the first embodiment. The liquid crystal 10 is the same as in the reference example.

  The surface of the microlens array 12 on the microlens 121 side is bonded to the cover glass 14, and the medium in the gap between the two is air. The opening diameter of the opening of the black matrix 17: D (= 11.5 μm × 12.0 μm) is the same as the reference example.

  FIG. 5B shows a state in which a parallel light beam is incident from the cover glass 14 side in the second embodiment. As shown in the drawing, the parallel light flux portion incident on the “spherical curved surface portion” around the microlens 121 is condensed near the center of the opening of the black matrix 17 while being transmitted through the liquid crystal 10 by the condensing action of the curved surface portion. To do. On the other hand, the light incident on the flat surface 121 </ b> A at the top of the microlens 121 passes through the microlens 121 without being subjected to lens action, passes through the liquid crystal 10 as a parallel light flux, and passes through the opening of the black matrix 17.

  For this reason, it is effectively avoided that excessive light energy is concentrated on a minute portion of the liquid crystal 10, and damage to the liquid crystal is effectively reduced.

  FIG. 5C shows an incident from the side of the cover glass 14 on the assumption that the light beam in the state close to the actual illumination light beam (the same light beam used for the simulation in the reference example) is applied to the liquid crystal panel unit of the second embodiment. The simulation result when it is made to show is shown. Compared with the state of FIG. 5B, the “degree of light collection” of the light condensed on the openings of the black matrix 17 is lower than that of FIG. 5B, and the light is transmitted through the openings of the black matrix 17. The diameter of the luminous flux to be generated is larger than that in the case of FIG.

In the case of FIG. 5C of Example 2, the transmission efficiency of illumination light was 0.98 with respect to the reference value of the reference example: 1.
That is, while effectively reducing excessive concentration of light energy on a specific portion of the liquid crystal 10 (a portion in the vicinity of the center of the opening of the black matrix 17), the transmission efficiency of the illumination light is substantially equal to that in the reference example. Is obtained.

  In the case of FIG. 5C of Example 2, when an antireflection film is formed on the front and back surfaces of the cover glass 14 and the microlens surface of the microlens array 12, the transmission efficiency of the illumination light is set to a reference value of 1. On the other hand, it could be improved to 1.05.

FIG. 6 is a diagram for explaining the conditions (1) and (2).

  FIG. 6A shows the state of FIG. 3A representing the reference example 1 described above. In this case, a microlens array in which the top portion of the microlens 131 is flattened to form a flat portion is denoted by reference numeral 130 in FIG. Reference numeral 1310 denotes a microlens, and the top flat portion is indicated by reference numeral 1310A. In the microlens 1310, “the shape of the spherical surface other than the flat surface portion 1310A” is the same as the spherical shape of the microlens 131.

At this time, in the case where the region 16A between the microlens array 130 and the cover glass 14 is filled with “a transparent adhesive having a refractive index difference of 0.1 with respect to the material of the microlens array 130”, When plotting the values of the aforementioned parameters: α and β when the “illumination light transmission efficiency” is 0.8, the values are as shown in FIG. A curve indicated by a solid line that approximates the plot points (indicated by black circles, the same applies below) with a quadratic function by the least squares method (the same applies to the following).
β = −5.3α ² + 1.7α + 2.1
Therefore, in order to realize the transmission efficiency of 0.8 or more, it is sufficient to satisfy the condition (1).

Incidentally, the conditions under which the transmission efficiency is 0.95 or more under the same conditions as above are as shown in FIG.
(3) β ≦ −4.0α ² + 0.79α + 0.82
It is.

Further, when the medium in the region 16A between the microlens array and the cover glass is substantially one having a refractive index of 1 (vacuum or air), the illumination light transmission efficiency is 0.8. Plotting the values of parameters: α and β are as shown in FIG. A solid curve is obtained by approximating the arrangement of these plot points with a quadratic function using the method of least squares.
β = −4.8α ² + 1.5α + 1.8
Therefore, it is only necessary to satisfy the condition (2) in order to realize the transmission efficiency of 0.8 or more.

Incidentally, the conditions under which the transmission efficiency is 0.95 or higher under the same conditions as above are as shown in FIG.
(4) β ≦ −3.97α ² + 0.8α + 0.75
It is.

  The above conditions (1) to (4) are the same even if the spherical shape of the microlens, the size of the effective lens surface, the size of the opening of the black matrix, and the like are different. Condition (3) and condition (4) are substantially the same.

  As apparent from FIGS. 7 to 10, in the region where the transmission efficiency of the illumination light is larger than 0.8 or 0.95, the parameter β becomes smaller (that is, the plane of the top of the microlens). Higher transmission efficiency can be obtained even if the size of the plane portion is increased as the distance between the portion and the cover glass becomes smaller.

  When the flat surface of the top of the microlens is brought into contact with the cover glass, the parameter: β is 0. At this time, as is clear from FIGS. 7 to 10, the largest value is allowed for the parameter: α. Will be. For example, in either case of FIG. 7 or FIG. 9, up to about α = 0.8 is allowed, and in the case of FIG. 8 or FIG. 10, up to about α = 0.5 is allowed.

Looking at the satisfaction of the above conditions in the cases of Examples 1 and 2, in Example 1, since α = 0.07 and β = 0.32 , the value on the right side of Condition (2) is
−4.8 × 0.0049 + 1.5 × 0.07 + 1.8 = 1.88 ( > 0.32 )
And the value on the right side of condition (4) is
-3.97 × 0.0049 + 0.8 × 0.07 + 0.75 = 0.79 (> 0.32)
Therefore, in Example 1, both the conditions (2) and (4) are satisfied.

In Example 2, since α = 0.07 and β = 0.0, the value on the right side of the condition (2) is
−4.8 × 0.0049 + 1.5 × 0.07 + 1.8 = 1.88 (> 0.0)
And the value on the right side of condition (4) is
-3.97 × 0.0049 + 0.8 × 0.07 + 0.75 = 0.79 (> 0.0)
Thus, also in Example 2, both the conditions (2) and (4) are satisfied.

It is a figure for demonstrating embodiment of a liquid crystal panel unit. It is a figure for demonstrating the conventional liquid crystal panel unit. It is a figure for demonstrating the example of a reference | standard. FIG. 3 is a diagram for explaining Example 1; FIG. 6 is a diagram for explaining a second embodiment. It is a figure for demonstrating invention of Claim 11 and 12. It is a figure for demonstrating conditions (1). It is a figure for demonstrating conditions (3). It is a figure for demonstrating conditions (2). It is a figure for demonstrating conditions (4).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal 12 Micro lens array 121 Micro lens 121A Plane part orthogonal to the optical axis of micro lens top part 14 Cover glass 17 Black matrix

Claims (2)

A microlens array in which light-collecting microlenses having a function of condensing in a black matrix opening of a liquid crystal pixel in a liquid crystal panel are arrayed corresponding to each liquid crystal pixel in the liquid crystal panel;
Top of individual microlenses constituting the microlens array, in order to alleviate the condenser due to the microlens, is a flat section perpendicular to the optical axis, and an opening diameter of the flat portion of the black matrix smaller set than the diameter of the part,
The microlens surface of the microlens array, the parallel plate-shaped cover glass to protect the microlenses in the substantially parallel to the microlens array, the microlens array and provided integrally with,
A method of designing a microlens array element in which a gap between the microlens array and the cover glass is filled with a transparent adhesive having a refractive index difference of 0.1 with respect to the material of the microlens array,
The area of the plane part of the top part of the microlens: ratio of s to the effective lens area of the microlens: S: s / S is α, the distance between the plane part and the cover glass: dt, and the diameter of the effective lens area: Ratio with DL: dt / DL as β , α and β as design parameters,
The range of the tilt angle of the light beam tilted with respect to the optical axis of the micro lens : ± 10 degrees as a design condition,
The above design parameters: α and β, conditions:
(1) β ≦ −5.3α ² + 1.7α + 2.1
The design method of the microlens array element is characterized in that the transmittance of the illumination light beam incident as the illumination light on each microlens is set to 0.8 or more by setting so as to satisfy the above. A microlens array in which light-collecting microlenses having a function of condensing in a black matrix opening of a liquid crystal pixel in a liquid crystal panel are arrayed corresponding to each liquid crystal pixel in the liquid crystal panel;
Top of individual microlenses constituting the microlens array, in order to alleviate the condenser due to the microlens, is a flat section perpendicular to the optical axis, and an opening diameter of the flat portion of the black matrix smaller set than the diameter of the part,
The microlens surface of the microlens array, the parallel plate-shaped cover glass to protect the microlenses in the substantially parallel to the microlens array, the microlens array and provided integrally with,
A medium having substantially a refractive index of 1 is formed between the microlens array and the cover glass.
A method of designing a microlens array element, comprising:
The area of the plane part of the top part of the microlens: ratio of s to the effective lens area of the microlens: S: s / S is α, the distance between the plane part and the cover glass: dt, and the diameter of the effective lens area: Ratio with DL: dt / DL as β , α and β as design parameters,
The range of the tilt angle of the light beam tilted with respect to the optical axis of the micro lens : ± 10 degrees as a design condition,
The above design parameters: α and β, conditions:
(2) β ≦ −4.8α ² + 1.5α + 1.8
The design method of the microlens array element is characterized in that the transmittance of the illumination light beam incident as the illumination light on each microlens is set to 0.8 or more by setting so as to satisfy the above.

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