JPS60259908A - Focus detection apparatus with deviation detecting function - Google Patents

Abstract

PURPOSE:To use a photo-electricity conversion means in common for detection of deviation and focus, by storing an image signal obtained by photo-electricity conversion at the focused time and detecting a relative change between the image signal obtained by the photo-electricity conversion means subsequent to storing and stored one. CONSTITUTION:Memory means 8 memorizing an image signal obtained from photo-electricity conversion means 1a, 1b at the time of focusing, image signal obtained from the conversion means 1a, 1b subsequent to memory and image signal memorized by a memorizing means are applied simultaneously to an arithmetic processing circuit 2 for processing. As an image developing optical system such as, the secondary image developing lenses 13a, 13b, photo-electricity conversion element arrays 1a, 1b and arithmetic processing circuit 2 are used in common for predetection and focus detection, the predetection becomes available by fulfilling requirements for compactness and low-cost characteristic.

Description

[Detailed description of the invention] This invention relates to a point detection device.

When taking photographs, there are cases where pre-prints (such as hand-printing) occur when taking pictures, which has a negative impact on the image quality of the film and often results in wasted film. Conventional measures have been taken to prevent this.

The occurrence of a pre-nucleation can be detected using an acceleration sensor, etc., or, as shown in Japanese Patent Laid-Open No. 58-174928, the subject image is repeatedly sampled within a certain period of time, and old subject information and new nuclear subject information are collected. Detect pre by comparing.

A pre-detection device is known that issues a warning to the photographer.

However, since the former detects the presence mechanically, it is difficult to incorporate it into the camera. Cameras became larger and more expensive, making them unsuitable for small cameras. Also, the latter is for automatic focus control. □□． ．． ．． □1. Yu, wa 8. A, ya ] When incorporated into a beam camera, it is inevitable that the camera will become larger and more expensive.

An object of the present invention is to provide a focus detection device with a pre-detection function that can be provided with a pre-detection function while satisfying compactness and low cost.

In order to achieve this object, the present invention provides a storage means for storing an image signal obtained by the photoelectric conversion means at the time of focusing, and a storage means for storing the image signal obtained by the photoelectric conversion means after the storage. The present invention is characterized in that it is provided with a detection means for detecting a relative change with respect to an image signal, and that at least the photoelectric conversion means is used in both pre-detection and focus detection.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

1 to 4 show an embodiment of the present invention. la
, lb is a photoelectric conversion element array, 2 is an arithmetic processing circuit for processing the signals photoelectrically converted by the photoelectric conversion element arrays 1a and 1b, and 3 is a timing pulse generator that generates timing pulses TI and T2 as shown in FIG. vessel,
4 to 7 are timing pulses T1. A switch circuit is turned on and off by T2, 8 is a storage circuit that carries and stores the signal photoelectrically converted by the photoelectric conversion element array 1a through the switch circuit 4, and 9 is an OR gate.

10 is a photographing lens, 11 is an optical axis, 12 is a field lens, 13a and 13b are secondary imaging lenses arranged at symmetrical positions with respect to the optical axis 11 behind the field lens 12, and 14a and 14b are secondary lenses. Imaging lenses 13a, 13b
It is a diaphragm set near the .

Next, the operation will be explained. First, the focus detection method will be described. The field lens 12 forms an image of the exit pupil of the photographic lens 10 substantially on the pupil plane of the two secondary imaging lenses 13a and 13b. the result.

The light beams incident on the secondary imaging lenses 13a and 13b respectively correspond to the secondary imaging lenses 13a and 13b on the exit pupil plane of the photographic lens 10. They are emitted from areas of equal area that do not overlap each other. The aerial image formed near the field lens 12 is converted into a photoelectric conversion element array la, by secondary imaging lenses 13a and 13b.
When the image is re-formed on the plane lb, the two images on the photoelectric conversion element arrays 1a and lb change their positions based on the displacement of the aerial image position in the optical axis direction.

FIG. 4 far to (C) shows this state. As shown in FIG. 4 (al), at the time of focusing, the two images are located in the middle of the photoelectric displacement element arrays Ia and lb, Figure 4 (b
During rear focus, as shown in FIG. 1, the two images move away from the optical axis 11, and as shown in FIG. 4 (C1), during front focus, the two images move toward the optical axis 11. If this image intensity distribution is photoelectrically converted and the relative positional deviation of the two images is detected by electrical signal processing, it is possible to determine whether one is in focus.

Therefore, by using the fact that the amount of deviation between the two images and the amount of focusing error are proportional, the amount of movement of the photographing lens 10 is calculated by displacing one image relative to the other image. In other words, from the photoelectric conversion signals of the two images, the arithmetic processing circuit 2 shown in FIG. A computer calculates the amount of deviation between the two images) and calculates the amount of focusing error. For example, one image expressed by b <:+ is moved relative to the other image expressed by a (i) in terms of circuit processing, and the amount of movement until the two images match is calculated as the image shift. Calculate as a quantity. That is.

■=Σl a(it-b (i+1+i) l-Σ1a
The calculation formula (i+1)-b(i+m)1 is repeatedly calculated by sequentially applying the relative displacement door to each integer value within the set range.

Calculate the relative displacement m when the correlation quantity is zero. Relative displacement m
The amount of correlation when changing the value within the range of -4≦m≦+4) is
If the situation is as shown in FIG. 5, the correlation t V should be zero when the two images match, so the amount of image shift equivalent to 1.5 pitches will be reduced. At this time, the switch circuit 5.6 is kept in the on state by a circuit not shown, that is, the circuit is configured as shown in FIG. Note that the focus detection method described above is already known.

Next, pre-detection will be described. As mentioned above, the signals photoelectrically converted by the photoelectric conversion element arrays la and lb are processed in the arithmetic processing circuit 2 to perform focus detection, and the output signals of the focus control circuit photoelectric conversion element arrays 1a and 1b (not shown) are - In this state, when the timing pulse generator 3 generates the timing pulse T (see Fig. 2), the switch circuits 4 and 5 and the OR gate 9 open the gates, thereby turning on the switch circuit 6.
Photoelectric conversion element array la.

The signal photoelectrically converted by 1b is sent to the switch circuit 5.6.
The signal is inputted to the arithmetic processing circuit 2 via.

On the other hand, since the switch circuit 4 is on, the signal photoelectrically converted by the photoelectric conversion element array 1a is input to the storage circuit via the switch circuit 4, and is stored in the form of -.

Next, the timing pulse generator 3 generates a timing pulse T.
2 occurs, the switch circuit 7 and the OR gate 9 open their gates, turning on the switch circuit 6, and the signal photoelectrically converted by the photoelectric conversion element array 1b at the timing pulse 712 and the signal stored in the storage circuit 8. are respectively input to the arithmetic processing circuit 2, and the shift between the two images is detected. Pre is detected by associating the deviations between these two images as described below.

When there is no or small deviation between the two images ・・・・・・－・・・・・・・・・・・・ Win without playing.

According to this embodiment, the photoelectric conversion element array la.

The signals obtained by step 1b are extracted in time series, and the first signal extracted is stored.

Since the signal extracted immediately after that and the signal are simultaneously output to the arithmetic processing circuit 2 for arithmetic processing, the imaging optical system such as the secondary imaging lenses 13a, 13b, the photoelectric conversion element arrays 1a, 1b, Since the arithmetic processing circuit 2 is commonly used for pre-detection and focus detection, pre-detection can be performed while satisfying compactness and low cost.

In addition, it is easy to arrange a warning means such as a display inside the camera, and use the warning means to warn when a pre-load amount larger than a certain standard is detected, or to devise measures to prevent shirt release. Therefore, there is no need to waste film.

In this embodiment, the photoelectric conversion element array 1a+1b corresponds to the photoelectric conversion means of the present invention, the storage circuit 8 corresponds to the storage means, and the arithmetic processing circuit 2 corresponds to the arithmetic processing means and detection means.

In this embodiment, after performing focus detection, timing pulse T1. Although the output signals of the photoelectric conversion element arrays 1a and 1b were taken out in time series at the timing T2, the output signal of the photoelectric conversion element arrays 1a or 1b at the time of completion of focus detection is replaced with the signal at timing pulse 215. is also possible. Furthermore, when performing pre-detection, the signals when the two photoelectric conversion element arrays la and lb are in focus are used.

It goes without saying that it is also possible to use time-series image signals from one photoelectric conversion element array 1a or 1b. Furthermore, although the arithmetic processing circuit 2 is used for focus detection and pre-detection, the arithmetic processing circuit 2 only performs focus detection and detects relative changes in time-series image signals for pre-detection.

Another detection means may be provided.

The present invention can be applied not only to a focus detection device using a secondary imaging method, but also to a focus detection device using a blurring method or a focus detection device using a baseline distance meter method that uses a shift between two images.

As explained above, according to the present invention, there is provided a storage means for storing the image signal obtained by the photoelectric conversion means at the time of one focusing, and a storage means for storing the image signal obtained by the photoelectric conversion means after the storage, and the image signal obtained by the photoelectric conversion means and the image signal stored in the storage means. A detection means for detecting a relative change with the image signal is provided, and the photoelectric conversion means is shared for pre-detection and focus detection, thereby achieving compactness and low cost. , can be equipped with a pre-detection function.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a timing chart showing one timing pulse generated by the timing pulse generator shown in FIG.
Figure 3 is a schematic diagram showing the focus detection system of the secondary imaging method.
Figures (a) to fc) are diagrams showing the relationship between the focus adjustment state and image blur, Figure 5 is a diagram showing the calculation results based on the calculation formula, and Figure 6 is a diagram showing the electric current during focus detection in one embodiment of the present invention. FIG. 2 is a block diagram illustrating a connection state. 1a, 1b... photoelectric conversion element array, 2... arithmetic processing circuit, 3... timing pulse generator, 41-7.
...Switch circuit, 8...Memory circuit, 10...Photographing lens, 12...Field lens, ]3a, 13i
+...Secondary imaging lens, 'L, T2-...Timing pulse. 1 Patent applicant Canon Co., Ltd. Agent Nakamura Seed box 1 Figure 2 T2-m-'-m- Figure 3 Figure 4 (a) (b) (C)

Claims (1)

[Claims] 1. Photoelectric conversion means for detecting multiple images of a detection target;
In a focus detection device, the focus detection device includes arithmetic processing means for determining a focus state based on the relativity of a plurality of images, and a storage means for storing an image signal obtained by the photoelectric conversion means at the time of one focus, and a storage means for storing an image signal obtained by the photoelectric conversion means after storage. A focus detection device with a pre-detection function, characterized in that it is provided with a detection means for detecting a relative change between the image signal obtained by the conversion means and the image signal stored in the storage means.