JP2710257B2 - Microlens array inspection method and inspection apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inspecting a microlens array used for a liquid crystal display device or the like.

[0002]

2. Description of the Related Art The above-mentioned liquid crystal display device is not limited to a direct view type,
Demand is increasing as a projection type display element for a projection television or the like. When the liquid crystal display element is used as a projection type, if the screen is enlarged with the conventional number of pixels, the screen roughness becomes conspicuous. In order to obtain a detailed image even if the screen is enlarged, it is necessary to increase the number of pixels. However, when the number of pixels in the liquid crystal display element is increased, especially in an active matrix type liquid crystal display element, the area occupied by the portion other than the pixel becomes relatively larger than the area of the pixel portion, and the black matrix covering the portion other than the pixel is And the area contributing to display decreases, thereby decreasing the aperture ratio of the liquid crystal display element. When the aperture ratio is reduced, the screen becomes darker, and there is a disadvantage that the image quality is reduced.

In order to prevent a decrease in aperture ratio due to such an increase in the number of pixels, it has been proposed to form a microlens for each pixel on one surface of a liquid crystal display device (Japanese Patent Application No. 60-1985). No. 165621-165624). The microlens array in which the microlenses are provided corresponding to the respective pixels has a function of condensing the light blocked by the black matrix into the pixels, thereby enabling efficient use of the light. As a micro lens, roughly divided
There are a hemispherical microlens having a hemispherical convex portion on the surface and a type which functions as a lens by forming a refractive index distribution region in a substrate.

[0004]

However, in order to sufficiently exert the effect of the micro lens, there are the following problems.

If the focal length of the microlens varies due to unevenness of the resist formed in the process of manufacturing the microlens array, it becomes difficult for light to converge on the microlens and each pixel of the liquid crystal display element. Part of the light that should be focused on the microlenses and pixels is absorbed by the black mask. For this reason, when an image displayed on the liquid crystal display element is projected, the illuminance varies on the screen. Also, when the manufactured microlens array is warped more than the allowable limit or when there is a cumulative error in the lens arrangement cycle, light is hardly condensed in the pixels of the liquid crystal display element, and the illuminance variation and light amount This can cause a drop. Therefore, before the microlens array and the liquid crystal display element are bonded to each other, it is necessary to measure the light collecting effect of the microlens array related to the variation in the illuminance and the decrease in the amount of light with the microlens array alone.

It is not meaningful to measure the pitch unevenness of the lens array, the unevenness of the focal length, and the amount of warpage independently of each other, and it is necessary to measure the light-collecting effect in a state where all these parameters are integrated. It is. However, conventionally, there is no inspection apparatus capable of measuring the light-collecting effect of the microlens array in the above-described state, and measurement has not been possible.

The present invention has been made in order to solve such a problem, and it is possible to inspect the light-collecting effect by integrating all parameters contributing to the light-collecting effect in a state of a single microlens array. It is an object of the present invention to provide a method and apparatus for inspecting a microlens array that can be performed.

[0008]

According to a method of inspecting a microlens array of the present invention, a microlens array having a plurality of microlenses is set, and parallel light is emitted toward the set microlens array. A reference mask having a plurality of apertures is arranged near the parallel light passing through the microlens and converging , and the amount of light passing through each aperture of the reference mask is detected. Is achieved. Further, the positional relationship between the microlens array and the reference mask may be detected, and the reference mask may be moved based on the detection result. The inspection apparatus for a microlens array according to the present invention includes: a setting unit for setting a microlens array in which a plurality of microlenses are formed; an optical system that emits parallel light toward the set microlens array; A reference mask having a plurality of openings disposed near where the parallel light from the system passes through the microlenses and converges , and a light detection means for detecting the amount of light passing through each opening of the reference mask And thereby the above object is achieved.

As the light detecting means, a plurality of illuminometers and a plurality of photodiodes can be used. Further, it is also possible to adopt a configuration in which one illuminometer is scanned, or a configuration in which a light quantity distribution is urged using a CCD camera, and this is quantified.

[0010] The apparatus may further include a position detecting means for detecting a positional relationship between the microlens array and the reference mask, and a mechanism for moving the reference mask based on a detection result by the detecting means.

[0011]

In the method and apparatus for inspecting a microlens array according to the present invention, the light emitted from the light source is applied to the reference mask after passing through the microlens array. The intensity of the light transmitted through the microlens array and the reference mask is measured by a light detection unit arranged on the light traveling direction side of the reference mask. On the other hand, the light reflected by the reference mask is captured by position detection means such as a CCD camera, and the positional relationship between the microlens array and the reference mask is detected based on the captured image.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An inspection method and an inspection apparatus according to the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram of a microlens array inspection apparatus according to the present invention, FIG. 2 is a detailed view of mounting a microlens array, and FIG. In this inspection apparatus, light emitted downward from a light source 1 is provided to a convex lens 5 through a diffusion plate 2, a slit 3, and a half mirror 4, and is converted into parallel light by the convex lens 5.

On the opposite side of the convex lens 5 from the light source 1, a matrix type reference mask 6 having a large number of openings is provided.
On the light source 1 side of the reference mask 6, a microlens array 7 having microlenses corresponding to each of the openings is set. The reference mask 6 is used in place of a liquid crystal display element (not shown) in which a black matrix is formed. The openings of the reference mask 6 are formed at positions and sizes corresponding to the respective openings of the black mask. ,
Inspection by the micro lens array 7 alone is enabled.

A glass plate 8 is provided between the reference mask 6 and the micro lens array 7. This glass plate 8
Is incorporated in the holder 13 that has been processed with high precision. The holder 13 has a spring lever 13a and three-point supports 13b, 13c, 13d as shown in FIG.
Are three-point support parts 13b, 13 with spring lever 13a.
By being pressed against c and 13d, positioning can be performed with good reproducibility. Further, this holder 13 is also
As shown in the figure, the base 15 provided with the spring lever 15a and the three projections 15b, 15c, and 15d is provided with three projections 15b and 15 using the spring lever 15a.
c, 15d to be positioned with good reproducibility. The microlens array 7 is attached to the holder 13 in advance, and after removing dust and foreign matter by washing, the microlens array 7 is set in the apparatus.

For example, nine illuminometers 9 are provided on the opposite side of the reference mask 6 from the light source 1, and the reference mask 6 and the illuminometer 9 are mounted on a tilt stage 10, and the tilt stage 10 is an XYZθ stage 11. Attached to. The XYZθ stage 11 can move in vertical and horizontal directions on a horizontal plane and in a vertical direction, and can rotate around a vertical axis.

The micro-lens array 7 is provided beside the half mirror 4 by utilizing the reflected light from the reference mask 6.
A CCD camera 12 for detecting a positional relationship between the half mirror 4 and the reference mask 6 is provided with the half mirror 4 in the field of view.

The inspection apparatus for a microlens array according to the present embodiment is configured as described above. As the light source 1, a random mix type fiber light source is used. The light transmitted through the diffusion plate 2 is completely diffused and has a diameter of 27 mm.
The light is stopped down by a slit 3 having a hole, and passes through a half mirror 4 to enter a convex lens 5.

The half mirror 4 has a diameter of, for example, 170 mm.
The one having a thickness of 1 mm was used, and the convex lens 5 was, for example, one having a diameter of 100 mm and a focal length of 200 mm. The light that has passed through the convex lens 5 becomes parallel light and enters the microlens array 7. The light incident on the microlens array 7 is condensed by the microlens and condensed on the opening of the reference mask 6, and the light passing through the opening is incident on the illuminometer 9.

The illuminometer 9 is, for example, 14 mm in diameter and 1 height.
Nine small ones having a size of 0 mm are used and are evenly arranged below the microlens array 7 as shown in FIG. When the microlens array 7 is warped as shown in FIG.
Part of the light condensed by the microlens 14 is absorbed by the reference mask 6 and the portion where the intensity of the light reaching the illuminometer 9 is reduced, and the entire light condensed by the microlens 14 is A phenomenon occurs in which there is a portion that reaches. Therefore, by measuring the intensity of the light transmitted through the reference mask 6 by the illuminometer 9 and grasping the distribution of the light intensity, the light condensing effect of the microlens can be inspected.

Incidentally, in order to perform the above inspection with high accuracy, it is necessary to maintain the parallelism of the microlens array 7. As means for this, for example, the holder 13 is removed before the inspection, and an optical flat is placed on the projection on the upper surface of the tilt stage 10 to which the reference mask 6 is attached, and XY
The positional relationship between the Zθ stage 11 and the tilt stage 10 is adjusted to bring the reference mask 6 into close contact with the optical flat, and in this state, the holder 13 and the reference mask 6 are positioned by minimizing the number of Newton rings. It is advisable to employ means for performing parallel alignment with the above.

The alignment between the microlens array 7 and the reference mask 6 at the time of the above inspection may be performed as follows. Moire fringes generated when the reflected light from the reference mask 6 is observed by the CCD camera 12 through the half mirror 4 or the like are monitored by the CCD camera 12 so that the moire fringes have a predetermined shape on a predetermined position. ,
The XYZθ stage 11 and the tilt stage 10 are operated. Thereby, the alignment with the microlens can be easily performed.

The thickness of the glass plate 8 is preferably as follows. For example, when a glass substrate having a thickness of 1.1 mm is used as a substrate of a liquid crystal display element to which a microlens array is attached, if the refractive index of the glass is 1.53, the focal length f of the microlens in the air is:
Since the thickness of the glass is 1.1 mm, f = 1100 μm
m / 1.53 = 720 μm. In this case,
Assuming that the thickness of the glass plate 8 is 550 μm, the value converted to the focal length of the glass plate 8 in the air is 550 μm /
1.53 = 360 μm. Therefore, it is possible to lower the reference mask 6 by 360 μm to condense the light of the microlens on the reference mask 6. As a result, it is possible to leave a 360 μm gap between the glass plate 8 and the reference mask 6. it can. Therefore, even if the holder 13 is attached after the reference mask 6 is positioned,
The mask surface of the reference mask 6 does not rub against the glass plate 8, and the mask surface is not damaged.

(Embodiment 2) FIG. 4 is a front view showing another embodiment of the present invention. In this embodiment, a number of photodiodes 19 are provided below the reference mask 6 instead of the illuminometer.
Is provided. The photodiode 19 is mounted on the tilt stage 10 together with the reference mask 6, and the tilt stage 10 is mounted on the XYZθ stage 11. The arrangement of the photodiode 19 is shown in FIG.
As shown in FIG. 7, the microlens array 7 is arranged vertically and horizontally to face almost the entire surface. Therefore, the light incident on the microlens array 7 is condensed by the microlens and condensed on the opening of the reference mask 6, and the light transmitted through the opening is incident on the photodiode 19. The photodiode 19 used had a diameter of 1.5 mm.

In this embodiment using the photodiode 19 as the light detecting means as described above, the diameter is about 10 mm even if it is small, and as shown in FIG. Also, a large light detection area can be taken, and detailed measurement can be performed.

(Embodiment 3) FIG. 7 is a front view showing still another embodiment of the present invention. In this embodiment, one illuminometer 9 is scanned. Specifically, the reference mask 6 and the illuminometer 9 are attached to the XY stage 20 and X
The Y stage 20 is attached to the tilt stage 21,
The tilt stage 21 is attached to the XYZθ stage 11. The XY stage 20 has a vertical
The microlens can be inspected by moving the illuminometer 9 in the horizontal and vertical directions, and by moving the illuminometer 9 in the vertical and horizontal directions, that is, by scanning.

In the case of this embodiment, when the measurement is performed with a plurality of illuminometers as in the first and second embodiments, the light receiving surface of the illuminometer is physically limited. It becomes possible. In addition, when a plurality of illuminometers and the like are used, there is an advantage that a single circuit is required for each, and a complicated circuit configuration can be prevented.

(Embodiment 4) FIG. 8 is a front view showing still another embodiment of the present invention. In this embodiment, a diffusion plate 22 and another CCD camera 29 are arranged below the reference mask 6 as light detection means for detecting a light amount distribution of transmitted light from the reference mask 6. After once transmitting the transmitted light from the reference mask 6 onto the diffusion plate 22, the light is projected onto the CCD camera 29.
, And sends the image of the CCD camera 29 to the image capturing device 24 through a cable. Furthermore, by dividing the image plane into 515 × 512 by the image capturing device 24 and quantifying the light intensity of the transmitted light and processing the data with a personal computer or the like, the light quantity distribution can be measured with high resolution and easily. Has become.

The reference mask 6, the diffusion plate 22, and the CCD
The camera 29 is mounted on the tilt stage 23, and the tilt stage 23 is mounted on the XYZθ stage 11. Further, the diffusion plate 22 existing between the reference mask 6 and the CCD camera 29 functions to suppress the generation of moire fringes due to the difference in the arrangement cycle of the CCD elements of the reference mask 6 and the CCD camera 12. Thereby, the in-plane distribution of the intensity of the light transmitted through the reference mask 6 can be observed without light interference. The distance between the diffusion plate 22 and the reference mask 6 is preferably within a range between a state of being in close contact and a state of being separated by 20 mm.

(Embodiment 5) FIG. 9 is a front view showing still another embodiment of the present invention. In this embodiment, the half mirror 4 and the CCD camera 12, CC provided in FIG.
Remove the D camera 29 and newly add the total reflection mirror 25 and C
The CD camera 26 is fixed at the position shown in the figure. CC
The image of the D camera 26 is sent to an image capturing device 27 and a monitor television 28 through a cable.

The total reflection mirror 25 and the CCD camera 26 are X
Stage 11 is independent of the YZθ stage 11 and does not move by the operation of positioning the microlens array 7 by operating the XYZθ stage 11. For this reason, the micro lens array 7 can be fixed at a fixed position in the screen.
It is not necessary to perform the position correction process when obtaining the in-plane distribution of the light-condensing effect for the image obtained in step (1).

The diffusion plate 22 has the following advantages when the attachment and detachment are simplified. That is,
With the diffusion plate 22 attached, the light-collecting effect of the microlens array 7 can be measured. On the other hand, in the case of the removed state, the moire fringes generated when observing the transmitted light passing through the microlens array 7 and the reference mask 6 are monitored on the monitor television 28 so that the moire fringes have a predetermined shape. By operating the XYZθ stage 11, fine adjustment of the alignment of the microlens array 7 can be performed.
Therefore, in the case of this embodiment, there is an advantage that one CCD camera can be reduced.

In each of the above-described embodiments, telecentric illumination in which light incident on the microlens array 7 is parallel light is used. In the case of this illumination, parallel light from the light source 31 passes through the microlens array 32 and the opening of the reference mask 33, as schematically shown in FIG.
The light is condensed by the field lens 36 and is projected on the screen 35 via the projection lens 34. Therefore, as shown in FIG. 11, since the light incident on the microlens array 32 is parallel light, it is preferably used when the pitch of the microlenses and the aperture pitch are the same.

Apart from such telecentric illumination, as shown in FIG. 12, the distance between the diffuser plate 2 and the convex lens 5 is made larger than the focal point f of the convex lens 5 so that the light converges on the microlens array 7. There is Koehler illumination that makes the light incident. The present invention can use that lighting. In Koehler illumination, as shown in FIG. 13, parallel light from a light source 31 is converged by a field lens 36, passes through a microlens array 32 and an opening of a reference mask 33, and is projected on a screen 35 via a projection lens 34. Configuration. Therefore, as shown in FIG. 14, the light incident on the microlens array 32 is converged. Therefore, it is preferable to use the microlens array 32 when the microlens pitch is larger than the opening pitch of the reference mask 33. The selection of which of the two illuminations is used is determined according to the optical system in which the microlens array is actually used.

[0035]

According to the microlens inspection method and the inspection apparatus of the present invention, the intensity of light transmitted through the microlens array and the reference mask is arranged on the side of the reference mask in the light traveling direction. The light intensity distribution related to the light condensing effect of the microlens array can be easily and accurately measured by performing the measurement with the light detecting means. For this reason, it is possible to prevent variations in illuminance and a decrease in light amount, and it is possible to sufficiently exert the effect of the microlens.

[Brief description of the drawings]

FIG. 1 is a front view showing a microlens array inspection apparatus according to the present embodiment.

FIG. 2 is a detailed mounting diagram of a microlens array.

FIG. 3 is a cross-sectional view of a portion near a microlens array.

FIG. 4 is a front view showing a microlens array inspection apparatus according to another embodiment of the present invention.

FIG. 5 is a plan view showing an arrangement state of photodiodes used in the embodiment of FIG.

FIG. 6 is a plan view showing the arrangement of the illuminometer used in the embodiment of FIG.

FIG. 7 is a front view showing a microlens array inspection apparatus according to still another embodiment of the present invention.

FIG. 8 is a front view showing a microlens array inspection apparatus according to still another embodiment of the present invention.

FIG. 9 is a front view showing a microlens array inspection apparatus according to still another embodiment of the present invention.

FIG. 10 is a schematic diagram showing an inspection method of a microlens array when using telecentric illumination.

FIG. 11 is a sectional view showing a microlens array and a reference mask which are preferably used in the method of FIG. 10;

FIG. 12 is an explanatory diagram of Koehler illumination.

FIG. 13 is a schematic diagram showing an inspection method of a microlens sieve when Koehler illumination is used.

FIG. 14 is a sectional view showing a microlens array and a reference mask which are preferably used in the method of FIG. 13;

[Explanation of symbols]

 Reference Signs List 1 light source 2, 22 diffuser plate 3 slit 4 half mirror 5 convex lens 6 reference mask 7 micro lens array 8 glass plate 9 illuminometer 10, 21, 23 tilt stage 11 XYZ θ stage 12, 26, 29 CCD camera 13 holder 15 base 19 photo Diode 20 XY stage 24, 27 Image capturing device 25 Total reflection mirror

Continued on the front page (72) Kazuhide Ueda, 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Prefecture Inside Sharp Corporation (72) Tokihiko Shinomiya 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka 72) Inventor Yoko Iwakoshi, 22-22 Nagaikecho, Abeno-ku, Osaka, Osaka, Japan (72) Inventor Takeshi Shibuya 22-22 Nagaikecho, Abeno-ku, Osaka, Osaka, Sharp Corporation

Claims (10)

(57) [Claims] 1. A microlens array in which a plurality of microlenses are formed is set, parallel light is emitted toward the set microlens array, and the parallel light passes through the microlens and converges in the vicinity. A method for inspecting a microlens array, comprising: disposing a reference mask having a number of openings, and detecting a light amount of light passing through each opening of the reference mask. 2. The microlens array inspection method according to claim 1, further comprising: detecting a positional relationship between the microlens array and a reference mask, and moving the reference mask based on the detection result. 3. A setting means for setting a microlens array in which a plurality of microlenses are formed; an optical system for emitting parallel light toward the set microlens array; Pass through lens and converge
An inspection apparatus for a microlens array, comprising: a reference mask having a plurality of openings disposed in the vicinity of the reference mask; and a light detection unit for detecting the amount of light passing through each opening of the reference mask. 4. The apparatus according to claim 3, further comprising: a position detecting means for detecting a positional relationship between the microlens array and the reference mask; and a mechanism for moving the reference mask based on a detection result by the detecting means. Inspection device for micro lens array. 5. A CC for detecting moire fringes formed by light reflected from the reference mask, wherein the position detecting means captures moire fringes formed by light reflected from the reference mask.
The inspection apparatus for a microlens array according to claim 4, further comprising a D camera. 6. The microlens array inspection apparatus according to claim 3, wherein said light detecting means comprises a plurality of illuminometers. 7. The microlens array inspection apparatus according to claim 3, wherein the light detection means comprises a plurality of photodiodes. 8. The microlens array inspection according to claim 3, wherein the light detection means is a mechanism for scanning one illuminometer in a direction crossing the light passing through each opening of the reference mask. apparatus. 9. The microlens array inspection apparatus according to claim 3, wherein said light detection means comprises a CCD camera and an image capturing device for quantifying a light amount distribution captured by said CCD camera. 10. The light detecting means includes: a CCD camera;
6. The microlens array inspection apparatus according to claim 5, further comprising an image capturing device for digitizing a light amount distribution captured by the CCD camera, wherein the CCD camera is shared with a CCD camera for capturing moiré fringes.