JPH0556355A - Photoelectric converter - Google Patents

Abstract

PURPOSE:To enable a precise photoelectric conversion signal processing by replacing the signal of a defective picture element existing in an area sensor with the signal of the normal picture element in the neighborhood. CONSTITUTION:The fourth picture element from the right of a video signal 522 corresponds to the defective picture element, and the signal of the picture element is deteriorated. Then, when the position of the defective picture element is preliminarily recognized in the checking process or the like, the position information is stored in an EEPROM in a microcomputer. Then, at the time of operating the adding processing of the video signal, the video signal corresponding to the defective picture element is replaced with the signal of an another adjacent normal picture element by using the information. That is, the signal of the fourth picture element from the right of a signal 522' is prepared by replacing the video signal corresponding to the defective picture element with the fourth picture signal from the right of a signal 523, and a signal 531 is prepared by adding signals 521, 522', and 523-525 at every horizontal picture element. At that time, the signal 531' is approximate to the actual one, so that an error can be reduced by operating a focus detecting processing by using the signal 531'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device and a focus detection device capable of performing focus detection in an arbitrary plurality of areas within a photographic screen using the conversion device.

[0002]

2. Description of the Related Art Conventionally, as an automatic focus detecting device for a camera, there have been proposed a lot of devices capable of detecting focus at a plurality of points on a photographing screen.

A conventional photoelectric conversion sensor used in such a device is one in which a finite number of sensor rows corresponding to the respective focus detection points are arranged on the same substrate. Specific configurations include, for example, JP-A-63-1906 and JP-A-63-1906.
No. 172209, JP-A 1-271716, and the like.

One of the conventional examples will be briefly described with reference to the focus detection optical system shown in FIG. Field lens 40,
It is composed of a porous field mask 41, a secondary imaging lens 42 in which two positive lenses are arranged in parallel, and a sensor chip 43 in which a plurality of pairs of sensor rows are arranged. The porous field mask 41 is provided at a position in the vicinity of a planned image forming surface of a photographing lens (not shown), and the openings 41a, 41b, and 41c respectively determine the focus detection area in the photographing screen. The secondary imaging lens 42 uses a sensor array pair 4 for a part of the subject image limited by the opening 41a.
The image is re-formed on 3a and 43b. Similarly, the subject image limited by the opening 41b or 41c is re-imaged on the sensor row pair 43c, 43d or 43e, 43f, respectively. The subject image signal of each sensor array pair is read as an electric signal, and focus detection calculation is executed in the processing device. In this way, the focus state of the photographing lens with respect to the subject within the focus detection visual field determined by each aperture is detected. When the focus detection fields determined by the three openings are applied to the photographing screen, for example, 49L, 49C, 4 of the photographing screen 47 of FIG.
Corresponds to the 9R position.

When the number of focus detection visual fields is at most several and the visual field position is fixed, the sensor array is discretely arranged on the sensor chip corresponding to each detection visual field position as in the above example.
Generally, a structure for providing a sensor driving circuit is provided in a region between each sensor array on the chip.

When it is desired to increase the number of focus detection fields of view more than before or to change the field of view position according to the situation,
Photoelectric conversion elements are arranged regularly in two dimensions vertically and horizontally,
It is desirable to use a so-called area sensor. Especially when it is desired to change the visual field position, the visual field mask is not the porous visual field mask having the opening corresponding to the focus detection visual field as described above, but all the plural focus detection visual fields as shown in the visual field mask 41 of FIG. The one having only one large opening 41R included is used.

Since the basic principle of the focus detection system of the form shown in FIG. 8 follows the conventional form shown in FIG. 9, the same components are designated by the same reference numerals. The field mask 41 is provided at a position in the vicinity of the planned image forming surface of the photographing lens (not shown), and the area limited by the single wide opening 41R is the focus detectable range. A diaphragm plate 44 is placed in front of the secondary imaging lens 42, and each of the diaphragm holes 44P and 44Q regulates a light beam incident on each positive lens. The position of the diaphragm plate 44 is substantially in an image forming relationship with the position of the exit pupil of the photographing lens by the power of the field lens 40. The secondary imaging lens 42 including a pair of positive lenses reimages the subject image determined by the opening 41R on the pair 43P and 43Q of the area sensor.
The subject image signal on one of the area sensors is read as electrical information, and focus detection calculation is executed in the processing device.

In FIG. 8, the area sensor 43 is shown as having two light receiving areas 43P and 43Q separated from each other, but if the predetermined controllability is obtained, it is a continuous light receiving area. But of course it's good.

By the way, in general, a main subject and its background coexist in the photographing screen at the same time, so that the screen region targeted for focus detection must be limited in some way.

In the conventional example shown in FIG. 9, each opening of the field mask 41 serves to limit the optical area. Further, therefore, only the sensor array having a shape corresponding to each aperture needs to be arranged on the expected image forming surface of the secondary image forming lens.

In the form as shown in FIG. 8 using the area sensor, there is no means for optically limiting the area, so an electric means must be provided. Specifically, for example, the subject image information of a part of the light receiving area of the area sensor is selectively read out, or the information of a specific area in the subject image information read out in a wide range is selectively processed. Thus, the focus state is detected in the local area of the photographing screen.

[0012]

However, when the area sensor is used as the focus detection sensor, the following problems occur.

That is, the area sensor chip has a large number of photoelectric conversion elements arranged on the chip surface as compared with the line sensor, and the number of pixels is large in absolute amount, so that pixel defects are likely to occur.
If one defective pixel is not allowed when using the area sensor, the yield becomes extremely low, which leads to an increase in product cost, which is not feasible, and it is necessary to allow some defective pixels. However, if there is a defective pixel in the area where the focus detection processing is performed, an error is naturally included in the processing result for that area, and an accurate focus detection operation cannot be guaranteed.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems. When a defective pixel is present in a part of the area sensor, the signal of that pixel is not used but instead the neighborhood signal is used. By substituting the normal pixel signal of
An object of the present invention is to provide a charge conversion device that can take out highly accurate pixel signals without reducing the yield of the area sensor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The photoelectric conversion device according to the present invention will be described below by taking the case where it is adopted for focus detection as an example.

FIG. 1 is a block diagram showing an embodiment in which the charge conversion device according to the present invention is used in a focus detection device.

In the figure, 43 is an area sensor, and an interface circuit 60 is connected to the area sensor 43 to perform area designation and accumulation control which will be described later. The interface circuit 60 is connected to a microcomputer 61 which is a processing device. Microcomputer 61 is CP
It has a U (central processing unit), a ROM, a RAM, and an EEPROM (electrically erasable programmable ROM), and executes focus detection processing according to a program stored in the ROM.

Position information of the focus detection area and position information of the defective pixel of the area sensor are stored in advance in the EEPROM in the adjustment process and the like.

FIG. 2 shows a schematic flow of a program for focus detection processing stored in the ROM.

When the microcomputer 61 starts the focus detection process, it goes through step (01) to step (0
The sensor accumulation of 2) is executed, and the subject image signal accumulated in the sensor is read in the next step (03).

When the reading of the image signal is completed, the process proceeds to the next step (04).

In step (04), the area for focus detection is determined.

When the focus detection area on the photographing screen is determined, the selection area on the sensor chip is calculated based on the information stored in the EEPROM. Then, the subject image signal in that area is actually converted into a shape suitable for focus detection processing.

The process here will be described in a little more detail.

It is assumed that the area for focus detection is temporarily set to the area 210C on the screen 210 of FIG. For the selection of the area here, a rule such as priority of the central area of the screen or priority of the selection result of the previous time is often used, but since the area selection is not directly related to the present invention, detailed description thereof is omitted.

Now, when the area for focus detection on the photographing screen is determined to be 210C, the corresponding area on the sensor chip is shown in FIG.
a, 230b) is calculated. EEPROM
May store detailed position information for each position on the screen, or assume the positions and shapes of some typical focus detection areas on the screen in advance, and calculate the corresponding areas on the chip. The position and shape may be stored.

When the shape of the focus detection area on the sensor chip is calculated in step (04), the next step (0
In 5), the subject image signal is processed based on it. This processing will be described with reference to FIG.

The rectangular subject area on the photographing screen is like a solid line area 52 on the part 50 of the sensor chip. Although FIG. 5 shows the sensor light receiving area on one side of FIG. 4, the other light receiving area is the same.

When the focus detection process is actually performed, since the phase difference detection type of the embodiment detects the phase difference in the one-dimensional direction, the object information of the area having the two-dimensional direction is converted into the one-dimensional direction. Need to be converted into information. For that purpose, as shown in FIG. 5, the image signal in the horizontal direction in the area is added for each pixel unit in the vertical direction by using the subject image signal stored in the RAM inside the microphone computer to obtain 1 The three-dimensional image signal 53 may be generated. The focus detection processing calculation is performed on the one-dimensional signal 53.

Now, let us assume that there is a defective pixel 54 inside the target area 52 for focus detection processing on the sensor. At this time, FIG. 6 shows the state of the video signals arranged in each vertical direction.

In the figure, reference numerals 521 to 525 represent the read video signals in the respective vertical directions. Signal 52
The fourth pixel from the right of 2 corresponds to the defective pixel 54, and the signal of this pixel is lowered as shown in the figure. Signals 521-5
The signal obtained by adding 25 directly to each horizontal direction is the signal 531.
become that way. The fourth signal from the right of 531 is lowered due to the influence of defective pixels. When the focus detection processing is performed based on this signal 531, it is obvious that the processing result has some errors.

Therefore, if the position of the defective pixel is known in advance during the inspection process or the like, the position information is stored in the EEPROM in the microcomputer 61 shown in FIG. Then, when the addition processing of the video signals is performed, the information is used to replace the video signal corresponding to the defective pixel position with, for example, a signal of another normal pixel adjacent to the defective pixel position. This will be explained with reference to FIG. 7.
The signal of the fourth pixel is obtained by replacing the signal 523 with the fourth pixel signal from the right.
A signal obtained by adding 1,522 ′ and 523 to 525 for each horizontal pixel is 531 ′. In this case, the signal 531 'is closer to the actual signal than the signal 531 of FIG.
If the focus detection processing is performed by using, the error can be suppressed to be extremely small.

If there is no defective pixel on the area sensor, or if there is no defective pixel in the area such as the area 51 indicated by the broken line in FIG. Needless to say, the pre-replacement process is not necessary.

Returning to FIG. 2, in the next step (06), a well-known focus detection calculation is used from the one-dimensional image signal generated in the previous step (05) to determine the target photographing screen area. Detect focus condition.

In the above-mentioned embodiment, the photoelectric conversion device of the present invention is used for focus detection, but it is explained.
It goes without saying that the present invention can be used in measuring devices other than those for focus detection.

[0036]

As described above, according to the present invention, even if there is a defective pixel in the area sensor, the signal of the neighboring pixel is used instead of the signal of the defective pixel. Therefore, the photoelectric conversion signal processing can be performed with high accuracy without lowering the yield of the area sensor chip.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a photoelectric conversion device according to the present invention.

FIG. 2 is a program flow chart showing an example when performing focus detection processing using the apparatus of FIG.

FIG. 3 is an explanatory diagram showing a measurement target region.

FIG. 4 is an explanatory diagram showing a sensor area corresponding to the target area of FIG. 3;

FIG. 5 is an explanatory diagram illustrating pixel output processing of a sensor.

FIG. 6 is an explanatory diagram showing an output of a sensor.

FIG. 7 is an explanatory diagram showing the output of the sensor together with FIG.

FIG. 8 is a configuration diagram showing an optical system when the photoelectric conversion device according to the present invention is used in a focus detection device.

FIG. 9 is a configuration diagram showing an optical system in a conventional photoelectric conversion device.

10 is an explanatory diagram showing a measurement target region in the photoelectric conversion device shown in FIG.

[Explanation of symbols]

 43 Sensor chip 61 Microcomputer

Claims (3)

[Claims] 1. A charge conversion device having an area sensor in which photoelectric conversion pixel sections are two-dimensionally arranged and a processing circuit for extracting and processing a signal from a predetermined range of the sensor. A photoelectric conversion device characterized in that a signal from a defective pixel is replaced with a signal from another pixel for processing. 2. The photoelectric conversion device according to claim 1, wherein a signal from a defective pixel among the pixels in the sensor is replaced with a signal from a pixel adjacent to the defective pixel for processing. 3. The photoelectric conversion device according to claim 1, wherein the processing circuit is a focus detection processing circuit that detects a focus state based on the extracted signal.