JP2887210B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus used for a video movie, an electronic still camera, and the like.

[0002]

2. Description of the Related Art Single-chip solid-state imaging devices such as video movies and electronic still cameras are provided with a color filter array to obtain color signals, and contain high frequency components corresponding to the pitch of the color filter array. A false color signal is generated from the subject. Further, the single-plate solid-state imaging device includes a solid-state imaging device having discontinuously and regularly arranged pixels, and a false signal is generated from a subject including a high frequency component corresponding to a pixel pitch. . Therefore, an optical low-pass filter is provided in the optical system of the single-plate solid-state imaging device in order to prevent generation of a false signal and a false color signal. As the optical low-pass filter, a filter in which three or more quartz plates and one infrared cutoff filter are laminated is usually used.

FIG. 2 shows a schematic configuration diagram of an example of a conventional imaging device having the above-mentioned optical low-pass filter. In the imaging device shown in FIG. 2, the solid-state imaging device 10 and a ceramic package 13 are fixed at the bottom of the package 13 via an adhesive layer 14, and the solid-state imaging device 10 is connected via bonding wires 15a and 15b. It is connected to external leads 16a and 16b. Package 1
A protective plate 12 made of glass is attached to the opening 3 via an adhesive layer 11. An optical low-pass filter formed by laminating the quartz plates 17a, 17b and 17c and the infrared cutoff filter 18 is arranged on the light incident surface side of the solid-state imaging device 10. On the imaging surface of the solid-state imaging device 10, a microlens array 19 may be formed.

Further, in order to reduce the size of an imaging device having the above-mentioned optical low-pass filter, an imaging device having a structure in which a solid-state imaging device is sealed using a transparent resin has been proposed ( IEICE Technical Report CP
M90-41). FIG. 3 shows a schematic configuration diagram of an imaging device having the above structure. In the imaging device shown in FIG.
The solid-state image sensor 20 and the mount 21 are fixed via an adhesive layer 22, and the solid-state image sensor 20 and the external leads 23a and 23b are connected via bonding wires 24a and 24b. Solid-state imaging device 20
The mount 21, the bonding wires 24a and 24b, and some of the external leads 23a and 23b are integrally sealed with a transparent resin 25. An optical low-pass filter formed by laminating a quartz plate and an infrared cutoff filter is arranged on the light incident surface side of the solid-state imaging device as in the imaging device shown in FIG. Here, the transparent resin 2
5, the light incident surface 25a is sufficiently polished. Further, a glass plate may be provided on this surface (Japanese Patent Application Laid-Open No. 60-1985).
-18941).

[0005]

The package 13 in the image pickup apparatus shown in FIG. 2 has a problem that it is heavy, large, and expensive. The imaging device shown in FIG. 3 has a problem that the surface of the imaging surface of the solid-state imaging device is covered with a transparent resin, and the microlens array cannot be installed on the imaging surface.

On the other hand, an optical low-pass filter having a structure in which the quartz plate and the infrared cutoff filter are laminated is heavy and large, and it is necessary to sufficiently polish the quartz plate surface one by one. Is inferior to mass production,
There is a problem that it is expensive. In order to solve the above problems, an optical low-pass filter comprising a diffraction grating has been developed (Japanese Patent Publication No. 49-20105, Japanese Patent Application Laid-Open No. 48-53741, and Japanese Patent Publication No.
No. 42849). The MTF (M) of an optical low-pass filter composed of a diffraction grating having
Odulation Transfer Function
on) The characteristics are shown in FIG. The period of the diffraction grating is represented by d,
The width of the convex portion of the diffraction grating is represented by a, the distance between the diffraction grating and the surface of the solid-state imaging device or a color filter array surface formed on this surface (hereinafter, these are collectively referred to as an imaging surface) is represented by b, When the wavelength of the incident light is represented by λ, the cutoff frequencies fa and fb shown in the MTF characteristics of FIG. 4 are represented by the following equations. (I) When a ≦ d / 2, fa = a / bλ (1) fb = (da) / bλ (2) (ii) When d / 2 <a <d, fa = (da) / bλ (3) fb = a / bλ (4)

[0007] The spatial frequency of a subject that generates a false signal is determined by the pixel cycle of the solid-state image sensor, and the spatial frequency of the subject that generates the false color signal is determined by a set of cycles of a color filter array. The cutoff frequencies fa and fb are set so that these spatial frequencies are cut off, and the equations (1) and (2) are set according to the values.
Or d, a, and b are obtained using Expressions (3) and (4). By using the diffraction grating obtained in this way, generation of a false signal and a false color signal can be prevented.

The cut-off frequency of the optical low-pass filter comprising the diffraction grating varies depending on the value of the distance b between the optical low-pass filter and the imaging surface, as is apparent from the above-mentioned equations (1) to (4). . If the cutoff frequency deviates from the above-mentioned preset value, a false signal and / or a false color signal may be generated, and the distance b between the optical low-pass filter and the imaging surface becomes an accurate value. It is necessary to dispose an optical low-pass filter and a solid-state image sensor in the same. However, the above distance b is small, usually in the range of 5 to 1000 microns, and it is difficult to arrange at a precise position.

SUMMARY OF THE INVENTION It is an object of the present invention to dispose an optical low-pass filter having a diffraction grating which blocks a false signal and / or a false color signal and a solid-state image sensor at a position where the distance to an imaging surface is accurate. It is an object of the present invention to provide a small, lightweight, low-cost imaging device.

[0010]

According to the present invention, an object of the present invention is to provide an optical low-pass filter comprising a diffraction grating and a solid-state image pickup device laminated via a spacer, and a solid-state image pickup device having an image pickup side. An imaging member having a hollow portion, a mount portion on which the imaging member is mounted, a bonding wire connecting the solid-state imaging device and the external lead, and a part of the external lead are integrally sealed with resin. Of the solid-state imaging device
On the imaging surface or on the color filter array formed on it
A micro lens array is formed on
This is achieved by an imaging device having a hollow portion on a lens array .

As described above, the mark is provided on the imaging surface side of the solid-state imaging device.
By providing the micro lens array, the light collection efficiency is increased, and high sensitivity is obtained .

[0012]

The present invention will be described below in detail with reference to examples.

Embodiment 1 FIG. 1 shows a schematic configuration diagram of an example of an imaging apparatus according to the present invention. Figure 1
In the imaging device shown in FIG. 1, an optical low-pass filter 1 composed of a diffraction grating and a solid-state imaging device 3 are stacked via a spacer 2 having a square U-shape planar shape. One of an imaging member having a hollow portion 30, a mount portion 5 on which the imaging member is mounted, bonding wires 8a and 8b connecting the solid-state imaging device 3 to external leads 7a and 7b, and one of the external leads 7a and 7b. Is sealed with a resin 9. The lattice plane of the optical low-pass filter 1 faces the solid-state imaging device. A color filter array may be formed on the imaging surface of the solid-state imaging device 3 . The microlens array 4 on a color filter array formed on or on the imaging surface of the solid-state imaging device 3 is Ru is formed. The light incident surface 1a of the optical low-pass filter 1 may be covered with a sealing resin 9.

Optical low-pass filter 1 according to the present invention
Have a one-way grid or two-way grids that intersect each other. The grating has a cross-sectional shape such as a rectangular wave, trapezoidal wave, sine wave, etc., and typically has a depth in the range of 0.1 to 1 micron. The grating surface of the optical low-pass filter 1 may face the light incident surface side.

The microlens array 4 has a size corresponding to the pixels of the solid-state image sensor and is made of a hemispherical transparent material. The incident light is converged due to the difference in the refractive index between the air in the hollow portion and the transparent material, and the efficiency of light collection on the solid-state imaging device is increased. Thereby, the sensitivity of the solid-state imaging device is improved.

The spacer 2 is formed by patterning a resin film having a predetermined thickness and a photosensitive resin having a predetermined thickness.
An adhesive containing beads or rods having a predetermined diameter in an adhesive can be used. Preferably, the thickness of the spacer is in the range of 5 to 1000 microns.
The thickness of the spacer provides a distance between the imaging surface and the optical low-pass filter at which the spatial frequency that generates the false signal and / or the false color signal is cut off. The spacer 2 is installed on the solid-state imaging device 3 so as not to cover the imaging region of the solid-state imaging device 3. When the spacer 2 is installed on the solid-state imaging device 3, the spacer 2 is installed so that there is no gap in which the resin for sealing flows into the hollow portion 30 between the optical low-pass filter 1 and the solid-state imaging device 3.

As the sealing resin 9, an epoxy resin or the like can be used. When the light incident surface 1a of the optical low-pass filter 1 is covered with a sealing resin, the resin needs to be transparent. on the other hand,
When the light incident surface 1a of the optical low-pass filter 1 is not covered with the sealing resin 9, the resin does not need to be transparent, and a resin containing a filler made of an inorganic material such as silica may be used. Can be used. A resin containing a filler is preferable because it has a small molding shrinkage and a coefficient of thermal expansion. Further, as the sealing resin 9, a resin containing a black pigment can be used,
By using the resin, generation of stray light can be prevented.

[0018]

According to the present invention, the solid-state image sensor and the optical low-pass filter, which is arranged at a precise position with respect to the imaging surface and is composed of a diffraction grating for blocking false signals and / or false color signals, are integrated. Thus, a compact, lightweight, low-cost imaging device can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an imaging device of the present invention.

FIG. 2 is a schematic configuration diagram of an example of a conventional imaging device.

FIG. 3 is a schematic configuration diagram of another example of a conventional imaging device.

FIG. 4 shows M of an optical low-pass filter composed of a diffraction grating.
It is a TF characteristic diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical low-pass filter 2 Spacer 3 Solid-state image sensor 4 Micro lens array 5 Mounting part 7a, 7b External lead 8a, 8b Bonding wire 30 Hollow part 9 Resin for sealing

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-152287 (JP, A) JP-A-1-300572 (JP, A) JP-A-1-254912 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01L 27/14

Claims (1)

(57) [Claims] 1. An imaging member having a hollow portion on an imaging surface side of an imaging low-pass filter, comprising: an optical low-pass filter including a diffraction grating and a solid-state imaging device laminated via a spacer; a mount portion to be, a bonding wire for connecting the solid-state image pickup element and the external lead, and part of the external leads are integrally sealed with a resin, Ta solid
Color filter formed on or on an imaging surface of an image element
A microlens array is formed on the array,
An imaging device having a hollow portion on a microlens array .