JPH10160905A - Production of microlens substrate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the production of a substrate and to reduce the cost of an optical device by selectively forming light shielding films in the spacing parts of microlenses by a self-alignment method using the microlenses as a mask. SOLUTION: A transparent electrode 11 for electroplating is formed on one surface of the transparent substrate 10 and the surface thereof is provided with the plural microlenses 15. Next, the substrate 10 formed with the microlenses 15 and a nickel electrode 22 are immersed into a nickel sulfamate bath 21 which is an electrolyte dissolved with nickel ions 20. The plus side of an external DC power 25 is connected to a nickel power source 22 and the transparent electrode 11 of the microlens substrate is connected to the minus side. When the power source is turned on, the nickel ions are eluted from the nickel electrode 22 and the nickel is deposited on the exposed part of the transparent electrode 11 immersed into the liquid. On the other hand, the nickel is not deposited on the surfaces of the microlenses 15 which are insulators and, therefore, the light shielding films 27 are selectively formed in the parts where the microlenses 15 are not formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-dimensional image sensor used for a solid-state image pickup device such as a CCD or a facsimile or a display device such as a compact projection type color liquid crystal display device or a thin color liquid crystal display device. The present invention relates to a method for manufacturing a microlens substrate to be obtained and a liquid crystal display device using the microlens substrate.

[0002]

2. Description of the Related Art In the above-mentioned various optical devices, microlenses are used in combination with various optical elements and optical components. For example, incident light is converted into a photoelectric conversion area in order to increase the sensitivity of an optical pickup means used for a laser disk, a compact disk or a magneto-optical disk, a solid-state image sensor such as a CCD, or a one-dimensional image sensor used for a facsimile or the like. A microlens is used as a means for condensing light into the light. Microlenses are also used as means for converging incident light to pixel openings in order to increase the effective aperture ratio of liquid crystal display devices.

[0003] Since the diameter of the microlens is extremely small, it is difficult to manufacture the microlens by polishing or machining like a normal lens, and a manufacturing method using a lithography technique has been proposed. There are various methods for manufacturing a microlens using this lithography technique. As a method for easily manufacturing a large number of microlenses, a heat sagging method (Zoran D. Popov) is used.
ic et al. , Appl. Optics, 2
7p. 1281 (1988)). In this heat sagging method, a photoresist is coated on a substrate, a film-like microlens pattern is formed by photolithography technology, and the microlens pattern is heated at a temperature equal to or higher than the glass transition point of the photoresist to flow. And deforming the outer surface into a hemispherical surface by the surface tension to obtain a convex microlens.

By the way, in the above-mentioned various optical devices, it is general to form a microlens array by arranging microlenses in an array. In such a microlens array, if there is a portion that does not contribute to light collection in a gap between adjacent microlenses (a portion where the microlens is not formed), light to be incident on the microlens is incident as stray light from that portion. Therefore, the performance of the microlens, the optical element and the optical component used in combination with the microlens is greatly reduced. For example, in the case of a liquid crystal display device, since this stray light is condensed on the pixel opening, there arises a problem that the color purity is lowered and the image quality is lowered.

In order to prevent this, it is desirable to form a light-shielding film having an opening corresponding to the shape of each microlens array. As a method for forming such a light-shielding film, for example, a method disclosed in JP-A-7-174902 can be considered. That is, an Al film or the like is vapor-deposited on the surface of a substrate on which a microlens is formed, and a resist is applied thereon, and a resist mask having a predetermined opening in a microlens formation portion is formed by lithography. Using the resist mask, the Al film or the like is etched to form a light-shielding film pattern, and after removing the resist, a microlens is formed thereon by the above-described heat sagging method or the like, so that the gap is formed by the light-shielding film. A covered microlens array is obtained.

[0006]

However, the method for forming a light-shielding film disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-174902 has a large number of steps and a high alignment between the light-shielding film pattern and the microlens pattern. It is not an efficient method because it needs to be done with precision. In addition, in consideration of the alignment error, it is necessary to narrow the opening of the light-shielding film. In that case, however, there is a problem that the amount of light transmitted through the microlens is reduced and the light-collecting performance is reduced.

The present invention has been made to solve such problems of the prior art, and has a method of manufacturing a microlens substrate capable of easily manufacturing a microlens having excellent light-collecting performance and a color purity. It is an object of the present invention to provide a liquid crystal display device having good and excellent image quality.

[0008]

A method of manufacturing a microlens substrate according to the present invention comprises the steps of forming an electrode for electrolytic plating on a substrate, and forming a plurality of microlenses on the electrode for electrolytic plating. Performing electroplating using the electrode for electroplating as one electrode, and forming a metal light-shielding film pattern complementary to the microlens pattern on the microlens non-formed portion of the electrode for electroplating,
Thereby, the above object is achieved.

In the step of forming the microlenses, a film-like microlens pattern made of a photoresist is formed on the electrode for electrolytic plating, and the film-like microlens pattern is heated to a temperature equal to or higher than the glass transition point. The microlens whose outer surface has become a part of a sphere by heating may be manufactured.

A liquid crystal display device according to the present invention is a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates. The substrates are bonded,
Thereby, the above object is achieved.

The operation of the present invention will be described below.

In the present invention, the microlens functions as a mask during electrolytic plating, and a metal light-shielding film is selectively formed on a portion where the electrode for electrolytic plating is exposed without forming the microlens. Is done. Therefore, there is no need to align the microlens pattern and the light-shielding film pattern as in the conventional method of manufacturing a microlens substrate,
The process becomes very simple.

Further, when the step of forming the microlenses is performed by a heat sag method, a large number of microlenses can be easily formed.

By bonding the microlens substrate manufactured as described above to one of the substrates constituting the liquid crystal display element, stray light incident from the gap between the microlenses is shielded by the light shielding film, and the color purity is reduced. And deterioration of image quality can be prevented.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1H is a sectional view showing a microlens substrate 28 of Embodiment 1.

The microlens substrate 28 has a transparent electrode 11 for electrolytic plating provided on one surface of the transparent substrate 10 and a plurality of microlenses 15 provided thereon. On a portion of the transparent electrode 11 where the microlenses 15 are not formed, a light-shielding film 27 made of metal is formed by electrolytic plating.

The microlens substrate 28 is manufactured, for example, as follows.

First, as shown in FIG. 1A, a transparent electrode 11 for electrolytic plating is formed on one surface of a transparent substrate 10 by a sputtering method or the like. In this embodiment, the IT
The transparent electrode 11 was formed using O (indium tin oxide).

Next, as shown in FIG. 1B, a photoresist 12 is applied on the transparent electrode 11 by a spinner.
Pre-firing is performed. In this embodiment, TF-20 manufactured by Shipley was used as the photoresist 12.

Subsequently, as shown in FIG. 1C, a microlens pattern 13 is formed by photolithography. In this embodiment, the micro lens pattern 1
The shape of No. 3 was a stripe type.

Thereafter, as shown in FIG. 1 (d), the lens pattern is heated to a temperature equal to or higher than the glass transition point using a hot plate 14 to fluidize the lens pattern. The resulting microlens 15 is formed. Although the shape of the outer surface of the microlens 15 varies depending on the height of the microlens 15 from the transparent electrode 11 (or the thickness of the microlens pattern 13),
What is necessary is just to make it the outer surface become a part of spherical surface. In the present embodiment, a lenticular type microlens is used in accordance with the stripe-shaped pixel arrangement of the liquid crystal display element in order to use the microlens substrate in the single-panel liquid crystal display device of the second embodiment described later.
The outer surface of the microlens was a hemisphere, the lens pitch was 90 μm, and the center thickness was 10 μm. The refractive index of the photoresist was 1.60, and the focal length of the lenticular lens was 0.35 mm as measured in air.

Next, as shown in FIG. 1E, the substrate 10 on which the microlenses 15 are formed and the nickel electrode 22 are placed in a nickel sulfamate bath 21 which is an electrolytic solution in which nickel ions 20 are dissolved. Immerse. The nickel sulfamate bath 21 is composed of nickel chloride and boric acid with nickel sulfamate as a main component, and the temperature of the thermostat 24 is set in a range of 40 ° C to 60 ° C. In addition, the plus side of the externally provided DC power supply 25 is connected to the nickel electrode 22, and the minus side is connected to the transparent electrode 11 of the microlens substrate.

Subsequently, as shown in FIG. 1F, when the DC power supply 25 is turned on, nickel ions are eluted from the nickel electrode 22 and nickel is deposited on the exposed portion of the transparent electrode 11 immersed in the liquid. Precipitates. On the other hand, since nickel does not precipitate on the surface of the microlens 15 which is an insulator,
The light-shielding film 27 is selectively formed in a portion where the microlens 15 is not formed.

Thereafter, as shown in FIG. 1 (g), when the thickness of the light shielding film 27 reaches a thickness necessary for light shielding, the DC power supply 25 is turned off and the microlens substrate is pulled up.

Finally, the electrolytic solution adhering to the microlens substrate is washed away with ultrapure water and dried to form a light-shielding film 27 in the gap between the microlenses 15 as shown in FIG. The completed microlens substrate 28 is completed.

As described above, a light-shielding film can be selectively formed on a portion where a microlens is not formed by a self-alignment method using a microlens as a mask, so that a high-performance microlens substrate can be easily manufactured. can do.

In this embodiment, nickel is used as a light shielding film material from the viewpoint of good corrosion resistance and chemical stability. However, the present invention is not limited to this, and various metals can be used. Further, the electrolytic plating solution is not limited to the above-described one, and an electrolytic plating solution in which metal ions corresponding to the metal to be plated are dissolved can be used. For example, when the plating material is copper, a mixed solution of copper sulfate and sulfuric acid can be used, and when the plating material is iron, a mixed solution of ferrous chloride and calcium chloride can be used.

(Embodiment 2) FIG. 2 is a schematic diagram showing a projection type color liquid crystal display device of Embodiment 2. The detailed structure of such a liquid crystal display device is described in, for example, JP-A-4-6053.
No. 8 discloses this. In the following description,
R, G, and B represent red, green, and blue, respectively.

In this liquid crystal display device, the light from the white light source 30 is reflected directly or by the spherical mirror 31, and the light is reflected by the dichroic mirror 33R through the condenser lens 32.
The light enters 33G and 33B. Dichroic mirror 33
Light incident on R, 33G, and 33B is selectively transmitted or reflected by each wavelength band to become a light flux of R, G, and B. After passing through the microlens substrate 34 and the liquid crystal display element 35, the field lens 36 and the projection The light is projected on a projection screen 38 via a lens 37.

The white light source 30 is a metal halide lamp,
A halogen lamp, a xenon lamp, or the like can be used. In this embodiment, a metal halide lamp having a power of 150 W and an arc length of 5 mm is used as the white light source 30.

The spherical mirror 31 is arranged on the back of the white light source 30 so that its center coincides with the white light source 30, and the condenser lens 32 is arranged on the front of the white light source 30 so that its focus coincides with the white light source 30. I have. With this arrangement, the light emitted from the white light source 30 and emitted from the condenser lens 32 becomes a substantially parallel white light flux. The method of obtaining a parallel light beam from the white light source 30 is not limited to such a method, and a method using a paraboloid of revolution or a method using a spheroidal mirror and an integrator in combination can be appropriately selected.

Dichroic mirrors 33R, 33G, 3
3B has a characteristic of selectively reflecting light in each of red, green, and blue wavelength bands and transmitting light in other wavelength bands. These are arranged at different angles in the order of 33R, 33G, and 33B on the optical axis, and are arranged in a fan shape.

The microlens substrate 34 and the liquid crystal display element 35 have a structure as shown in the sectional view of FIG. In FIG. 3, a polarizing plate and an alignment film, which are components of the liquid crystal display element 35, are omitted for simplification.

The liquid crystal display element 35 has a liquid crystal layer 42 filled with twisted nematic (TN) liquid crystal between an active matrix substrate 41 made of a glass plate and a counter substrate 40. Active matrix substrate 41
Has rectangular pixels 43R arranged in a matrix.
A thin film transistor (not shown) for switching between 43B and 43G is provided, and the TN liquid crystal is driven for dynamic display via the thin film transistor. In the present embodiment, the pixel pitch is 90 μm × vertical.
Pixels 43R, 43G corresponding to red, green, and blue are arranged in a stripe arrangement of 30 μm in width and 450 × 600 pixels.
43B was disposed on the side surface of the liquid crystal layer 42 of the glass substrate 41.

In the liquid crystal display element 35, the opposite substrate 40 is bonded to the microlens substrate 34 with an adhesive 48. The microlens substrate 34 is provided with a vertically long lenticular lens 44 having a width of 90 μm and extending over three pixels of R, G, and B of the liquid crystal display element 35, and is configured to perform color display without using a color filter. That is, the dichroic mirrors 33R, 33G, 33B
R, G, and B light beams incident at different angles from
A pixel 43R corresponding to the lenticular lens 44,
43G and 43B are respectively distributed and radiated to each pixel 43R,
The light transmitted through 43G and 43B is transmitted to the field lens 36.
Then, the light is projected on the projection screen 38 via the projection lens 37, whereby a color display is obtained. As described in the first embodiment, the lenticular lens 44 is formed on the transparent substrate 46 by a heat sagging method, and the microlens substrate 34 is formed on a portion of the transparent electrode 47 where the lenticular lens 44 is not formed by the electrolytic plating method. Light shielding film 45
Is formed.

In this liquid crystal display device, the effect of the light shielding film provided on the microlens substrate 34 is shown in FIGS.
This will be described with reference to FIG. Note that the description will be made by taking the G pixel as an example, but the same applies to the R and B pixels.

When no light-shielding film is provided on the microlens substrate 34, color mixing occurs as follows. As shown in FIG. 4, the G light flux is perpendicularly incident on the lenticular lens 50 and is collected on the G pixel 51. On the other hand, the R light flux incident on the lenticular lens 50 is condensed on the R pixel as shown in FIG. 3, but the R light flux incident on the gap 52 of the lenticular lens 50 is shown in FIG. It passes through the gap 52. Similarly, as for the light flux of B, the light incident on the lenticular lens 50 is condensed on the pixel of B as shown in FIG. 3, while the light incident on the gap 53 of the lenticular lens 50 is shown in FIG. Pass through the gap 53. The R light flux transmitted through the gap portion 52 and the B light flux transmitted through the gap portion 53 are not bent by the lenticular lens 50, and proceed straight as they are to enter the G pixel 51. Thus, the G pixel 5
Since the R light beam and the B light beam that should not be incident on 1 are incident, color mixing occurs. As a result, the purity of the color that the G pixel 51 should originally display is reduced, and the image quality is reduced.

On the other hand, when a light shielding film is provided on the microlens substrate 34, color mixing can be prevented as follows. As shown in FIG. 5, the lenticular lens 5
Even if the R light flux enters the zero gap, it is reflected or absorbed by the light shielding film 62 provided in the gap. Further, even if the light flux B enters the gap of the lenticular lens 50, it is reflected or absorbed by the light shielding film 63 provided in the gap. As described above, since neither the R light beam nor the B light beam reaches the G pixel 61, color mixing does not occur.
As a result, the chromaticity coordinates of the G pixel on the xy chromaticity coordinate diagram were (0.350, 0.620), and high color purity was secured. The same applies to the R pixel and the G pixel. The chromaticity coordinates of the R pixel are (0.630,
0.340), and the chromaticity coordinates of the G pixel are (0.160,
0.108), and high color purity could be secured in each case.

In this embodiment, a projection type color liquid crystal display device having a microlens substrate has been described. However, a microlens substrate manufactured by the method of manufacturing a microlens substrate according to the present invention is applicable to other optical devices. It is also possible. For example, a solid-state image sensor such as a CCD, a one-dimensional image sensor used for a facsimile, or the like, a thin liquid crystal display device, and the like can be given.

[0041]

As described in detail above, according to the present invention,
Since a light-shielding film can be selectively formed in a gap between microlenses by a self-alignment method using a microlens as a mask, a resist mask for forming a light-shielding film can be used as in a conventional method of manufacturing a microlens substrate. There is no need to form separately. Accordingly, the manufacture of the microlens substrate is significantly simplified, and the cost of the optical device having the microlens substrate can be reduced. Further, since it is not necessary to narrow the opening of the light-shielding film unlike the conventional method for manufacturing a microlens substrate, the light-collecting performance of the lens can be improved.

By bonding the microlens substrate manufactured according to the present invention to a liquid crystal display device, a bright, high-quality liquid crystal display device with good color reproducibility can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a manufacturing process of a microlens substrate according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a liquid crystal display device according to a second embodiment.

FIG. 3 is a cross-sectional view illustrating a configuration of a liquid crystal display element and a microlens substrate in a liquid crystal display device according to a second embodiment.

FIG. 4 is a cross-sectional view for explaining color mixing when a light blocking film is not provided on a microlens substrate in a second embodiment.

FIG. 5 is a cross-sectional view for explaining an effect when a light shielding film is provided on a microlens substrate in the second embodiment.

[Explanation of symbols]

 10, 46 Transparent substrate 11, 47 Transparent electrode 15 Micro lens 27, 45, 62, 63 Light shielding film 28, 34 Micro lens substrate 30 White light source 31 Spherical mirror 32 Condenser lens 33R, 33G, 33B Dichroic mirror 35 Liquid crystal display element 36 Field lens 37 Projection lens 38 Screen 43R, 43G, 43B, 51 Pixel 44, 50 Lenticular lens 52, 53 Gap

Claims (3)

[Claims] A step of forming an electrode for electrolytic plating on a substrate; a step of forming a plurality of microlenses on the electrode for electrolytic plating; and performing electrolytic plating using the electrode for electrolytic plating as one electrode. Forming a metal light-shielding film pattern complementary to the microlens pattern on the non-microlens-formed portion of the electrode for electrolytic plating. 2. The step of forming the micro lens,
A film-like microlens pattern made of photoresist is formed on the electrode for electrolytic plating, and the film-like microlens pattern is heated to a temperature equal to or higher than the glass transition point to make the outer surface part of a spherical surface. The method for manufacturing a microlens substrate according to claim 1, wherein the microlens is manufactured. 3. A liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates.
A liquid crystal display device, to which a microlens substrate manufactured by the method for manufacturing a microlens substrate according to 1 is bonded.