JPS6134514A - Focus determination device - Google Patents

Abstract

PURPOSE:To detect the volume of defocus of photographic lens in a short time by calculating the corelation between two figure patterns read by a sensor in time series at a CCD corelation meter and obtaining a phase shift extent from the time giving the maximum value of calculated result. CONSTITUTION:A CCD corelation meter 13 and a peak position detecting circuit 17 are driven by the output signal of a line sensor driving circuit 19 which drives based on the control signal outputted from a CPU18 which is a control circuit. Through the CPU18, short forcus, long focus and just focus is displayed to display circuit 20 by the value of (m) including a sign in case of focus aide, or the defocus extent is drived to output a signal to a photographic lens driving circuit 21 in case of auto-focus, then the photographic lens is driven to the right focal position. In such a focus determination device, the time necessary for the calculation of detection of focus is the charge transfer time inside the CCD corelation meter, therefore, the time is substantially shorter compared with the normal calculating operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a focus detection device M5 for an eye reflex camera, a microscope, etc., and more particularly to a focus detection device that utilizes lateral displacement of an image.

(Prior Art) FIG. 12 shows an example of a conventional block diagram of a focus detection device that utilizes lateral shift in response to defocus of a photographic lens. A self-scanning image line sensor 1, such as a COD or MOS type, is placed on the cutting surface of the photographic lens. optical elements that cause misalignment;
For example, stripe mask (Japanese Patent Laid-Open No. 59-15207
(see publication).

Microprism (see Japanese Patent Laid-Open No. 58-59418).

fly-eye lens (see % JP-A No. 54-159259), one using a re-imaging lens (JP-A-54-1)
04859) etc. are arranged. These optical elements separate the light beam that mainly passed through one half of the photographing lens from the light beam that mainly passed through the other half. If the output of the light receiving element that receives the light flux that mainly passes through one half of the photographic lens is [An], and the output of the light receiving element that receives the light flux that mainly passes through the other half of the lens is [Bn], then As shown in FIG. 15, the output of the line sensor 1 is that when the photographic lens is defocused, the hoe is lateral shifted L/L, and the direction of image shift is opposite when the front focus is on and when the rear focus is on. Also, when focusing, [An]”
[It becomes Bnko.

In FIG. 12, the output from the line sensor 1 is A/D converted by A/D conversion circuit # & 6 via an output processing circuit 2 consisting of a sample hold circuit, an amplification path, etc.: RA
The data is input to a storage circuit 4 such as M and stored therein. These output processing circuits 2. The A/D converter 3 and the memory circuit 4 are each controlled by a control circuit (hereinafter abbreviated as CPU) 5, and the 2-in sensor 1 is controlled via a line drive circuit 8 which is controlled by the CPU 5. It looks like this. This CPU 5 has an arithmetic function, and the memory (b) path 4
It is configured to perform arithmetic processing on the data and output the photographing lens pin information to the display device 6 or to the photographing lens driving circuit 167.

With this configuration, the anakig output of the line sensor 1 is A/D converted, and based on the data, the KCPU 5
In this case, software calculations are performed to detect focus, which requires a certain amount of calculation time. In particular, digital calculations have the drawback of requiring a considerable amount of time to perform the correlation calculation required to determine the amount of image shift during autofocus operation.

(Objective) In view of the above-mentioned points, an object of the present invention is to provide a focus detection device having a CCD correlator that can determine the amount of lateral shift of an image according to the defocus of a photographing lens in an extremely short time. shall be.

(Summary) The CCD calculates the cross-correlation of two hoe patterns read out in time series obtained from the line sensor, which is a group of light receiving elements that receives images that are laterally shifted according to the defocus of the photographic lens.
This method is characterized in that it calculates using a correlator, calculates the amount of phase shift between two iron patterns from the time when the maximum value of the correlation output is given, and calculates the defocus signal of the photographing lens in an extremely short time. It is a focus detection device.

(Example) Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 is a pull diagram showing the configuration of a light receiving section and a calculation section in the focus detection device of this embodiment. CC which is the light receiving part
The D line sensor 9 includes a photodiode archipelago ~An that receives the light flux that has mainly passed through one half of the photographic lens, and a photodiode array B, ~Bn that receives the light flux that has mainly passed through the other half of the photographic lens. It has a 7-otodiode array 10 in which A is arranged alternately.
n.

When appropriate charges are accumulated in the seven photodiode array 10 made of Bn, the transfer gate 11A transfers the charges accumulated in the photodiode arrays A1 to Anic to the CCID shift register 12A. Also, similarly.

The transfer gate 11B transfers the charges accumulated in the photodiode arrays 81 to Bn to the COD shift register 12B. The charges transferred to this COD shift register are transferred by a transfer link (not shown).

CCD shift register 14At14 of CCD correlator 13
Sent to B. One CCD shift register 14A transfers the signal charges of the photodiode rows λ1 to An to the left in the drawing, and the other COD shift register 14B transfers the signal charges of the photodiode rows 81 to Bn to the right in the drawing. The CCD shift registers 14A and 14B are connected to a multiplier 15 and an adder 16, respectively, as shown, and constitute a CCD correlator 13. The output of the adder 16 is designed to provide a cross-correlation function of [An], [Bn], which is the output of the photodiode arrays Al to An and B1 to Bn, which are sampled time series data. (For the CCD correlator with
Correlator using Change-
CoupledDevices” 19715 IEE
RInternational 5olid-8ta
te C1rcuit Conference, PP
, 198-199. ) Here, the outputs of the photodiode arrays A1 to An, B, to Bn are [An, [Bn
If both have distributions as shown in Figure 2, then
In other words, consider the state in which the image is in focus.

Transfer lock φAt at the timing shown in Figure 3
'B is supplied to the CCD shift registers 14A and 14B, respectively, and the charges in the CCD shift registers 14A and 14B at each time point "N-17" N+l+ are as shown in FIG. CC this cross-correlation
For each of the four central portions of the D shift registers 14A and 14B, the output of the CCD correlator 15 is as shown in FIG. It is clear from FIG. 4 that the correlation output is maximum when 1=1N. In addition, the time standard is
For example, the reference 1o may be set to the time when the first transfer lock is supplied after the charges of the 7-otodiode array 10 are transferred to the CCD shift registers 12A, 12B.

If the transfer signals φ and φ to be supplied to the CCD shift registers 14A and 14B are set as shown in FIG. 6, the output of the CCD correlator 13 becomes as shown in FIG. 8 with reference to FIG. . In this case as well, the correlator output becomes maximum when 1=1N.

As shown in FIG. 9, when the horizontal shift lid of the image is ΔX,
The defocus amount ΔZ is given by A. Here, θ is the inclination with respect to the optical axis of the principal ray of the light beam that has mainly passed through one side of the photographic lens, and is determined by the F value of the photographic lens and the configuration of the light beam splitting means.

When a horizontally shifted image is received by a 7-otodiode array, there is a relationship between the pitch of the 7-otodiode array and P.
As shown in FIG. 10, the images are laterally shifted from each other by m pieces. In this case, as shown in FIGS. 6 and 7, if the COD correlator is driven, the maximum value of the output of the COD correlator will be t=t=f:mΔt @--
--<5). Here, 2 corresponds to the front pin and the rear pin, respectively, and Δt = 1. +1-t
It is i.

Therefore, by measuring the time t at which the maximum value of the output of the COD correlator is given, ±m can be found from equation (3), and the defocus amount can then be found.

FIG. 11 is a block diagram showing the configuration of a focus detection device of the present invention using the CCD line sensor 9 and CCD correlator 16 described above.

The output from the CCD line sensor 9 is sent to a CCD correlator 13, and the output is sent to a peak position detection circuit 17Vc that detects the time when the maximum value of the correlation output is given.

Cholera CCD line sensor 9, CCD correlator 13
and the peak position detection circuit 17 is a control circuit CP0
They are each driven by an output signal from a line sensor drive circuit 19 which is driven based on a control signal output from a line sensor drive circuit 18 . The output m of the peak position detection circuit 170 represents each defocus amount and in-focus state of the front bin and rear focus, but this is sent via the CPU 18 to the above m including the sign in the case of focus aid. Based on the values, the front focus, rear focus, and focus state are displayed on the display circuit 20, and in the case of autofocus, the defocus is determined according to the above equation (4), and a signal is output to the photographing lens drive circuit 21. , the photographing lens is driven to the focusing position VC.

As mentioned above, in the focus detection device of the present invention, the calculation time required for focus detection is the charge transfer time within the CCD correlator 13, which is extremely short compared to the case where conventional digital calculation is used. Become.

Also, the driving method of the COD correlator is shown in Fig. M3 and Fig. 4.

Although not limited to FIGS. 6 and 7, COD
Several other variations can be easily devised by those skilled in the art by changing the configuration of the correlator.

Furthermore, the CCD line sensor 9 and the CCD correlator 13 are
It can be integrated into a chip.

(Effects of the Invention) As described above, according to the present invention, by using a COD correlator in a focus detection device using a CCD line sensor, the photographic lens can be defocused in an extremely short time required for charge transfer. You can find the quantity.

Furthermore, since the CCD line sensor and CD correlator can be integrated into one chip, the signal processing circuit becomes simple.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing an example of the light receiving section and calculation section used in the present invention, Fig. 2 is a diagram showing the output characteristics of the photodiode array when focusing, and Fig. 3 is a transfer diagram. The fourth diagram is a diagram showing the timing of the transfer lock, the fourth diagram is a diagram showing the charge state in the COD shift register when the transfer lock shown in Figure 3 above is supplied, and the fifth diagram is the diagram shown in the diagram shown in Figure 4 above. Figure 6 is a characteristic diagram showing the output of the correlator in the charge state of IIi!
Prisoner. FIG. 7 is a diagram showing the charge state in the COD shift register when the transfer lock shown in FIG. 6 above is supplied, and FIG. 8 shows the output of the correlator in the charge state shown in FIG. 7 above. Characteristic diagram, Figure 9 is a schematic # diagram of the detection optical system showing the relationship between the amount of lateral shift and the amount of defocus, Figure 10 is a line diagram showing the output of the 2-in sensor in the state of lateral shift, and Figure 11 is , a block configuration diagram of a focus detection device showing an embodiment of the present invention, FIG. 12 is a block diagram showing the structure of a conventional focus detection device, and FIG.
, Bn is a diagram showing the output. 9..1.@@*Bottle CCD line sensor 10-...-
...7 Otodiode array (second photo-receiving element group) 13@... CCD correlator 14A, 14B-φ・COD shift register 111- tN-+ tN++ tN-+ LN++ Published by R 1A 11 Ohahachinohe, SSE Proceedings Amendment (spontaneous) Indication of Wang case 1982 Patent Application No. 155934 2
, Title of the invention Focus detection device 6, Relationship to the person making the correction Patent applicant address 2-46-2 Hatagaya, Shibuya-ku, Tokyo Name (037) Olympus Optical Industry Co., Ltd. 4,
Agent Address: 5-52-14-5 Matsubara, Setagaya-ku, Tokyo.
66 Contents of the amendment in the “Claims” column and “Detailed Description of the Invention” column of the specification to be amended (1) Amend the “Claims” stated on the first page of the specification as shown in the attached sheet. do. (2) "Line drive" described in page 6, line 14 of the specification
is corrected to "line sensor drive". (Attachment) [2. Claims: The imaging lens has first and second light-receiving element groups on the light-emitting side, and the first and second light-receiving element groups have lateral misalignment on the light-incidence side. The light receiving element of the first group of light receiving elements projects a beam of light that has mainly passed through the first half of the exit pupil of the imaging lens, and projects onto each of the light receiving elements of the second group of light receiving elements. has a means for projecting the light flux that has mainly passed through the second half of the exit pupil of the imaging lens, and has a means for projecting the light flux that has mainly passed through the second half of the exit pupil of the imaging lens, and is capable of projecting the first and second photoelectric conversion signal trains obtained from the first and second light receiving element groups. The cross-correlation is calculated using a COD correlator, and the first. A focus detection device characterized in that focus detection is performed by detecting the amount of phase shift of a second photoelectric conversion signal train. ”

Claims (1)

[Claims] The imaging lens has first and second light-receiving element groups on the light-emitting side, and has an optical element that causes lateral displacement on the light-incidence side of the first and second light-receiving element groups, and the first light-receiving element has Each light-receiving element of the element group projects a beam of light that has mainly passed through the first half of the exit pupil of the imaging lens, and each light-receiving element of the second light-receiving element group projects a beam that has mainly passed through the first half of the exit pupil of the imaging lens. It has a means for projecting the light flux that has mainly passed through the half surface, and calculates the cross-correlation of the first and second photoelectric conversion signal trains obtained from the first and second light receiving element groups using a CCD correlator. , a focus detection device that performs focus detection by detecting the amount of phase shift between first and second photoelectric conversion signal trains.