JPH07322153A - Solid-state image pickup element - Google Patents

Abstract

PURPOSE:To suppress the effect of dust stuck to the light incidence face without providing a glass plate on the surface of a resin package. CONSTITUTION:The solid-state image pickup element is provided with photoelectric transducers 15a and 15b which the object image is formed on light reception face by a focus detection optical system, and the formed optical image is converted into an electric signal and is outputted, ana this output is used for focus detection. With respect to this solid-state image pickup element, the light incidence surface of the package where photoelectric transducers 15a and 15b are sealed up with light-transmissive resin is a resin face as it is, and a distance d=Ce (C is the refractive index of the resin of the package) between the light reception face of photoelectric transducers and the incidence face of the resin package is determined so as to satisfy 15p<={e/(l-e)}g where (g), l, (p), and (e) are exit pupil dimensions of the focus detection optical system in the picture element array direction of photoelectric transducers, the length of the optical path expressed in terms of air between the exit pupil and the light reception face, the picture element pitch of photoelectric transducers, and the length of the optical path expressed in terms of air between the incidence surface of the package and the light reception face respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device in which a photoelectric conversion element for image detection used in optical instruments such as various cameras and optical measuring instruments is packaged with resin.

[0002]

2. Description of the Related Art As a conventional solid-state image pickup device used in a focus detection device, a device in which a photoelectric conversion element is sealed with a transparent synthetic resin material and a light incident surface thereof is covered with a glass plate is known. There is. If the transparent resin material is used as it is as the element surface without using a glass plate, the resin generally tends to be charged with static electricity,
There is a problem that dust adheres to the light incident surface, which is the element surface, which prevents detection of correct image information and causes a focus detection error.
Therefore, as a dustproof measure, a glass plate is attached to the surface of the element. It is possible to add an additive to the resin to make it less likely to be charged with static electricity, but the light transmittance will decrease,
It cannot be used for this type of sealed package.

Therefore, in the conventional solid-state image pickup device having a glass plate on the surface of the device, there is a problem that the manufacturing cost is increased due to the material cost of the glass and the work cost for sticking the glass.

An object of the present invention is to provide a solid-state image pickup device which suppresses the influence of dust adhering to the light incident surface without providing a glass plate on the surface of the resin package.

[0005]

In the solid-state image pickup device according to the present invention, the photoelectric conversion element is package-sealed with a light-transmitting resin, and the light-incident surface of the package remains a resin surface. The distance between the resin package and the incident surface of the resin package is determined by the following equation. 15p≤ {e / (l-e)} g

Here, g is the exit pupil size of the focus detection optical system in the pixel arrangement direction of the photoelectric conversion element, l is the air-converted optical path length between the exit pupil and the light receiving surface, and p is the pixel of the photoelectric conversion element. The pitch, e is the air-equivalent optical path length between the package incident surface and the light receiving surface of the photoelectric conversion element.

[0007]

Even if dust adheres to the light incident surface of the package, the image is blurred on the light receiving surface of the photoelectric conversion element, so that it does not affect the focus detection accuracy.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example in which the present invention is applied to a so-called phase difference detection type focus detection apparatus. Here, the focus detection device AFD includes a condenser lens 11,
Split pupil mask 12 and separator lenses 13a and 13b
Has a well-known focus detection optical system, and a pair of the subject 2 is formed on the light receiving surface of the photoelectric conversion elements 15a and 15b (for example, CCD line sensor) sealed with resin in the solid-state image sensor 14 by this optical system. The next image is formed. Then, the planned displacement between the focus detection surface 10 and the actual image formation surface is obtained from the amount of deviation between the pair of images on the photoelectric conversion elements 15a and 15b.

In the solid-state image pickup device according to the present invention, the light incident surface of the resin package for sealing the photoelectric conversion elements 15a and 15b is a resin surface.

Next, the principle of detection will be described with reference to FIG. 2 schematically showing the symbols common to those in FIG.

The focus detection device ADF is arranged behind the objective lens 21 so that the light receiving surfaces of the CCD line sensors 15a and 15b are conjugate with the focus detection surface 10. The light that has passed through the objective lens 21 then passes through the condenser lens 11, and the portions that have passed through the two openings in the split pupil mask 12 therein are the separator lenses 13a or 13b, respectively.
Via the line sensor 15a or 1 of the solid-state image sensor 14
Reach 5b.

When the image formed by the objective lens 21 is correctly formed on the focus detection surface 10, that is, when the image is in focus, the secondary image is correctly formed on the light receiving surfaces of the line sensors 15a and 15b. At this time, the line sensors 15a and 15
The interval between the pair of secondary images on b is a predetermined value.

On the other hand, the focus detection surface 1 by the objective lens 21
When the image on 0 is blurred, the secondary image is blurred, and the interval between the pair of secondary images on the line sensors 15a and 15b also changes. That is, in FIGS. 3A to 3C, photoelectric conversion signals obtained from the line sensors 15a and 15b are represented by A and B, respectively, and when focusing, as shown in FIG. The waveforms are almost the same, and the intervals between the waveforms of the signals A and B are deviated in the direction of narrowing or widening in the figure at the time of front pinning and rear pinning. Therefore, the pair of photoelectric conversion signals from the line sensors 15a and 15b can be fetched into the microcomputer and calculated to obtain the secondary image interval and detect the defocus amount.

Here, consider the case where a small dust adheres to the light incident surface of the solid-state image pickup device 14 and the light flux which is poured into the line sensor 15a is blocked. When the dust position is close to the light receiving surface of the line sensor 15a, that is, when the distance between the light incident surface of the solid-state image sensor 14 and the light receiving surface of the line sensor is small, the influence is large, as shown in FIGS. It becomes an output, and it becomes difficult to accurately obtain the secondary image interval. However, if the dust position is far away, the shadow of the dust will be blurred and its effect will be small. The situation during this period will be described with reference to FIG.

In the figure, reference numeral 22 denotes a virtual image by the separator lens 13a of the split pupil mask 12, and the line sensor 15a is shown at an optically equivalent position by removing the surrounding package. Now, minute dust is generated by the line sensor 15a.
If the distance e is away from the light receiving surface of, the opening width of the virtual image 22 of the split pupil (the opening width in the pixel arrangement direction of the line sensor 15a) is g, and the distance between the virtual image 22 and the light receiving surface of the photoelectric conversion element 15a. Where l is and the size of the dusty shadow is m, there is the following relationship. m = {e / (l-e)} g (1)

As can be seen from the equation (1), the larger e is, the more blurred the shadow of dust becomes and the thinner it becomes, so that the influence on the image on the line sensor is reduced. If m in the equation (1) is set to be 15 to 20 times or more the line sensor pixel pitch p, it is almost unaffected by a substance that adheres well to the resin and has a size of so-called fluff.

Here, the pixel pitch of the line sensor is
It is determined by the balance of the amount of light poured into one pixel of the line sensor, the resolution, the size of the device, etc., but for example p = 20 μm, g
= 1.5 mm and l = 6 mm, e> 1.3 mm is required for m> 20p, and e> 1 mm is also required for m> 15p. If the refractive index of the resin of the package is C, the distance from the light receiving surface of the line sensor to the surface of the solid-state image sensor is d, and the air-equivalent path length is e, then d = Ce (2) > 1.3mm, d> 1.3C
It should be mm.

<Modification> FIG. 6 shows a modification of the solid-state image pickup device 24 according to the present invention.
The D line sensors 25a and 25b are sealed with a transparent resin material, and the separator lenses 23a and 23b are provided on the element surface.
Is integrally formed with a resin material.

According to this embodiment, the work of adjusting the position of the separator lens and the solid-state image pickup device 24 is unnecessary, and the assembling property is remarkably improved.

Although the embodiment described above is the phase difference detection method, any other focus detection method such as the contrast method may be used as long as it is a device for performing focus detection based on the image signal detected by the solid-state image sensor. It can be applied to both.

[0021]

According to the present invention, the distance between the light receiving surface of a photoelectric conversion element such as a CCD line sensor, which is packaged in a transparent resin, and the light incident surface of the package is determined by the shadow of dust adhering to the package surface. The length of the solid-state image sensor is set so that it will not be affected by focus detection on the light-receiving surface, so there is no need to provide a glass plate to prevent dust from adhering to the package surface, and the cost of the focus detection device can be reduced. .

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a focus detection apparatus using a solid-state image sensor according to the present invention.

FIG. 2 is a schematic diagram illustrating the focus detection principle of the embodiment.

FIG. 3 is a diagram illustrating an output example of the solid-state image sensor according to the embodiment.

FIG. 4 is a diagram illustrating the influence of dust in the output example of FIG.

FIG. 5 is a diagram for explaining the influence of dust position on output.

FIG. 6 is a diagram showing a modified example.

[Explanation of symbols]

 10: Focus detection surface 11: Condenser lens 12: Divided pupil mask 13a, 13b, 23a, 23b: Separator lens 14, 24: Solid-state image sensor 15a, 15b, 25a, 25b: Line sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04N 5/232 A

Claims (1)

[Claims] 1. A photoelectric conversion element for forming a subject image on a light receiving surface by a focus detection optical system, converting the formed optical image into an electric signal for output, and utilizing the output for focus detection. In the solid-state imaging device, the light incident surface of the package in which the photoelectric conversion element is sealed with a light-transmissive resin is a resin surface, and the exit pupil size of the focus detection optical system in the pixel arrangement direction of the photoelectric conversion element is set to 15 p ≦ 15, where g is the air-equivalent optical path length between the exit pupil and the light-receiving surface, p is the pixel pitch of the photoelectric conversion element, and e is the air-equivalent optical path length between the package entrance surface and the light-receiving surface. {E / (l-e)}
A solid-state imaging device, characterized in that a distance d = Ce (where C is a refractive index of a resin of the package) between the light receiving surface of the photoelectric conversion element and the resin package incident surface is determined so that g is satisfied.