JPS60233513A - Focus detection device with shake detection function - Google Patents

Abstract

PURPOSE:To make the constitution of a range detecting device provided with a blur detecting function simple and small in size by storing three groups of photoelectric converting outputs of two images by different optical paths, and detecting a range and a blur based on the respective storage contents of other image, which have been stored simultaneously. CONSTITUTION:Three groups of photoelectric outputs of two images passing through different optical paths by line sensors 1a, 1b are stored successively in storing circuits 4-6 through an A/D converter 2, a distributor 1, etc. The contents of these circuits 4-6 are selected by selecting circuits 7, 8 which are brought to sequence control, the storage contents of other image from one of the circuits 4-6, or the storage contents of the same image before or after the circuits 4-6 are processed by a correlation processing circuit 9, and a range or a blur quantity is detected. In this way, the constitution of a range detecting device provided with a blur detecting function becomes simple and small in size by this electrical blur detection which requires no mechanical mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a distance detection device with a pre-detection function suitable for cameras.

(Background of the Invention) In photography, blurring (such as camera shake) occurs during photography, which adversely affects the image quality of the film, often resulting in wasted film. Conventional measures to prevent this.

It is possible to detect the occurrence of an image using an acceleration sensor, etc., or, as shown in Japanese Patent Laid-Open No. 58-174928, repeatedly sample the subject image within a certain period of time, and collect old subject information and new liquid subject information. Detect pre by comparing.

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

However, since the former method detects the predetermined position mechanically, when it is incorporated into a camera, the camera becomes larger and more expensive, making it unsuitable for small cameras. Moreover, since the latter is provided separately from the distance detection device for automatic focus control, if it is incorporated into the camera, it is inevitable that the camera will become larger and more expensive.

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

(Features of the Invention) In order to achieve the above object, the present invention provides at least three image signals that temporarily store two image signals output from a photoelectric conversion means.
A set of storage means, a distribution means for distributing the image signal to the storage means, and during distance detection, select separate signals stored simultaneously, and input them to the arithmetic processing means to calculate the distance, and during pre-detection, select the separate signals stored simultaneously, A selection means is provided for selecting the same image signals stored in succession and inputting the same image signals to the arithmetic processing means to calculate the pre-amount. and at least one of the previous image signals are always stored, and distance calculation and pre-calculation are selectively performed.

(Embodiments of the Invention) The present invention will be described below in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing one embodiment of the present invention. 1 a * 1 b is an (n+1.) bit line sensor such as a charge-coupled device (CCD) that detects the subject image, 2 is an A/D converter, and 3 stores the signal from A/D converter 2. A distributor that distributes to circuits 4.5.6, 7.8 a selection circuit that selects and outputs one of the signals input from the memory circuit 4.5.6, and 9 a selection circuit from 7.8 to A correlation processing circuit 10 performs correlation processing on input signals by shifting the phase thereof to detect each state of front focus, in-focus, and rear focus; 10 is a lens drive circuit 11 based on a signal from the correlation processing circuit 9; 13 is a pre-calculation storage circuit that detects and stores the pre amount based on the signal from the correlation processing circuit 9; 14 is a ternary counter; Distributor 31 selection circuit 7.8. Distance measurement processing storage circuit 10. Pre-calculation memory circuit 1
3 and a sequence control circuit that controls a drive circuit to be described later.

Reference numeral 15 denotes an accumulation time control circuit that controls the charge accumulation time in the picture elements so that the outputs of the line sensors la and lb reach a predetermined level; and 16, a drive system that controls the transfer of the charges accumulated in the picture elements. A drive circuit including a drive system that serially transfers the charge accumulated in the picture element, 17 is the threshold value of the pre-amount (tolerable limit)
18 is a comparator that compares the signal from the pre-calculation storage circuit 13 with the signal from the threshold value setting circuit 17. The threshold value of the accumulation time is set (the faster the accumulation time, the more the comparator %19 is set). The threshold value setting circuit 20 is a signal from the accumulation time control circuit 15 and the threshold value setting circuit 19. 21 is an AND gate, and 22 is a warning circuit for issuing a manual warning.

Next, the operation will be explained. The present invention is an arrangement of a distance measuring system using a so-called image shift detection method, and various methods have been proposed for this image shift detection method, but basically the distance measuring system uses two separate optical paths. Compare the phases of the subject images.

The front focus, in-focus, and rear focus conditions are determined using a triangulation method. That is, to explain using FIG. 1, in order to compare the phases of the images in line 5, the two images are decomposed into fine picture elements, and two time-series image signals "=(aio
, all ・"aiTh) * Bl"'(boo
+ bn ・= bin ) as rai 4 sensor a
, 1b, and the correlation processing circuit 9 performs correlation processing, such as changing the difference between the two image signals and shifting the phase of the image signals to be compared, to focus on the front side.

Detects focus and rear focus. At this time, the drive circuit 16 drives the light. Sensor a * 1 b
transfers the charge accumulated in the picture element to the transfer section and reads it out serially, and the accumulation time control circuits 1 and 5 are connected to the licensor 1a,
The accumulation time to the picture element is controlled so that the output of 1b is at a predetermined level. Furthermore, since the correlation processing in the correlation processing circuit 9 is generally performed by shifting the phases of the two corresponding image signals A+*Bt, the previous image signal AI(+*B10) is transferred to the A/D converter 2.
converts it into a digital signal and stores it in two storage circuits (
For example, memory circuit 5.6) control circuit (sequence control circuit 1)
It is controlled by a ternary counter (corresponding to the omitted circuit).

The above-mentioned matters have been explained in various prior inventions and are also the same in this embodiment, so further explanation will be omitted here, and only the main parts of the present invention will be described below with reference to FIG. state

The memory circuit 5 stores the previous image signal Ao, and the memory circuit 6 stores the image signal B0. After the accumulation time.

When image signal A1 is input from line sensor 1a.

The distributor 3 outputs the signal to the memory circuit 4, and when the image signal horse is input from the line sensor 1b, the memory circuit 5 (at this time, the previous image signal stored in the memory circuit 5 is erased). output to).

Next, in order to perform pre-detection, the sequence control circuit 14 selects the image signal Be stored in the storage circuit 6 by the selection circuit 7, the image signal B stored in the storage circuit 5 by the selection circuit 8, and the image signal B stored in the storage circuit 5 by the selection circuit 8. of.

Each is output to the correlation processing circuit 9. Similarly, in order to perform distance detection, the selection circuit 7.8 outputs the image signals A+ and Bt stored in the storage circuit 4.5 to the correlation processing circuit 9. after that.

As shown in FIG. 2, the output of the distribution 1 selection circuit 7.8 to the storage circuits 4-6 dynamically changes depending on the contents of the ternary kakunta arranged in the sequence control circuit 14.

By the way, if the subject does not move and the camera does not shake, the first image signals A+(B+) and (i+
1) The image signal AI+1 (Bt+1) of the second time should be exactly the same. If we focus on image signals B+ and BI+1, and if B1'=B1+x, then this means that the image has moved only within a range of 5, which is ignored with respect to the picture element pitch.

This is when the distance detection device considers it to be in focus*
This calculation processing method is extremely similar to the determination that Ai=Bt. However, in reality, even if the subject is exactly the same, BI# may be BI+1 due to fluctuations in the amount of light, so the threshold value set in the threshold value setting circuit 17 and the output value of the pre-calculation storage circuit 13 (pre-amount ) is compared with the comparator 18,
If B1YBl+1, a low level signal (determined to be an allowable pre amount) is output. Also.

Naturally, if the subject is bright, the shutter speed is fast, and therefore some pre-precision can be tolerated. If the accumulation time is fast, the signal will be lower level than the comparator 20 (even if there is camera shake, it is determined that it is acceptable because the shutter speed is fast)
output. Therefore, below a certain amount of light, the image signal B
1 (At) and the image signal ratio +1 (Aj+t) exceed a predetermined value, the alarm circuit 2 is activated by the AND gate 21.
A signal of 2 high level is output, and the warning circuit 22 issues a warning to the photographer. The most common way to issue a warning at this time is to use a 5-display display or the like to flash the front thread, but other methods include disabling shirt release or using a program to perform high-speed shirt release. It is also easy to shift to the seconds side.

According to this embodiment, as shown in FIG. 1, the distributor 3.
Pre-detection can be performed by simply adding one memory circuit 4 (5, 6), one selection circuit 7, one ternary counter.

That is, since most parts can be shared, the camera does not become larger.

(Correspondence between the invention and the embodiments) In this embodiment, the line sensors 1a + 1b are the photoelectric conversion means of the present invention, and the memory circuits 4 to 6 are the three sets of memory means, and the distributor 3 is the distribution means. The selection circuit 7.8 corresponds to the selection means, the correlation processing circuit 9, the distance measurement processing storage circuit 10, and the pre-calculation storage circuit 13 correspond to the calculation processing means.

(Modification) In the embodiment shown in FIG. 1, the image signal n = (au+, an-
a+n) first, and then the image signal BI=(bI
O1bIln...b%n), but the license sensor f
Depending on the structure of ar1b, aha, boo,
ass, bll"'aln+1)in may be read out alternately, and in this case, they are sequentially and alternately output to the storage circuit to be distributed. Also, assuming the brightness of the subject to the storage time of the line sensors 1a and 1b, Although a threshold value has been set, it is also possible to determine from the shutter speed.

Furthermore, the threshold value is determined by the threshold value setting circuit 17 according to the aforementioned accumulation time or shutter speed.

It is also easy to automatically correct it.

(Effects of the Invention) As explained above, according to the present invention, at least three image signals outputted from the photoelectric conversion means are temporarily stored.
a set of storage means, a distribution means for distributing the image signal to the storage means, and at the time of distance detection, selecting separate signals stored at the same time, selecting an operation sign, inputting it to the operation processing means, and calculating the pre amount. At least three sets of storage means constantly store the two latest image signals and at least one of the previous image signals, and select between the distance calculation and the pre-calculation. Since this is done in a consistent manner, the photoelectric conversion means and the arithmetic processing means can be used both for distance detection and pre-detection. Therefore, it is possible to provide a pre-detection function while satisfying compactness and low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a timing diagram of signal processing in each circuit shown in FIG. 1. 1 a * 1 b... Line sensor, 3... Distributor, 4-5-... Memory circuit, 7, 8... Selection circuit, 9
. . . Correlation processing circuit, 10 . . . Distance measurement processing calculation circuit, 1
3.--Pre-arithmetic storage circuit, 14. Sequence/sequence control circuit, 18.20. Comparator, 22. Warning circuit. Al, Ao − +, B+ + Bo”-B4
・”Image signal. Patent applicant Minoru Nakamura, Canon Co., Ltd. agent

Claims (1)

[Claims] 1. In a distance detection device comprising a photoelectric conversion means for detecting two images of a detection target formed by passing through different optical paths, and an arithmetic processing means for calculating the relativity of the images, from the photoelectric conversion means to at least three sets of storage means for temporarily storing the two output image signals; a distributing means for distributing the image signals to the storage means; and at the time of distance detection, selecting separate image signals stored at the same time and performing the calculation. selection means for inputting the image signals into the processing means to calculate the distance, selecting the same image signals stored sequentially in time at the time of pre-detection, and inputting the same image signals to the arithmetic processing means to calculate the pre amount; A distance detection device with a pre-detection function.