JPS6048009B2 - camera focus detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of deflecting both or one of two divided images of the same subject in opposite directions, and the relative deviation of the two subject images becomes 0 when they are in focus. This relates to an electrical processing method for a focus detection device that performs electrical focus detection using a pair of photoelectric conversion elements by applying the principle of a focus adjustment method called the double image matching method. It is characterized by changing the sign of the focus detection output, eliminating the influence of variations in output between photoelectric conversion element groups, and eliminating pseudo-focus signals that occur when there are no subjects on the same plane. The present invention relates to a focus detection device for a camera.

Conventionally, many focus detection devices have been devised that utilize changes in spatial frequency or changes in contrast of a subject image.

Recently, many systems have been devised that apply the principle of the so-called double image matching system described above, and some of them have been put into practical use.
However, most of them utilize the fact that the focus detection output shows the maximum value, minimum value, or extreme value when the focus is met, so the focus detection output is the entire focus detection range, that is, the focal point from infinity to the near point of the photographic lens. A detection measurement was required to detect the in-focus position once. Furthermore, since it is difficult to stop the photographic lens or the like at the moment when a focus signal is received from the electric circuit, a mechanism is required to memorize that position and return it to the focus position. Therefore, it has been difficult to follow a subject moving at high speed and instantly output a focus signal.
Moreover, the photographer is only notified of whether the camera is in focus or not, and it is difficult to inform the photographer of the state when the camera is not in focus (for example, front focus, back focus). For this reason, only automatic focus detection could be performed, and a driving circuit for the photographic lens and its power supply were also required, making the device itself large and complex. In addition, the influence of variations in output between photoelectric conversion element groups cannot be ignored, and when they are configured on the same chip, there is a drawback that the chip size becomes large. However, if you think about it, the reason why photographers, especially beginners, find it difficult to focus by themselves is not only due to individual differences in eye function, but also because the display is based on analog vision. There is also the idea that if it is possible to digitally determine, for example, front focus, focus, rear focus, or the success or failure of focus matching, there is no need to perform automatic focus detection, and that a so-called focus detector is sufficient. Based on the above idea, an object of the present invention is to obtain a focus detection signal necessary for constructing a focus indicator, and to perform focusing by moving a photographic lens etc., and to adjust the output between a group of photoelectric conversion elements. Ideal, with no influence of variations, no need for a drive circuit, and no individual differences. - Provides a focus detection device for a camera that can perform precise focusing.

Of course, when used as an automatic focus detection device, a simple device that does not require measurement of the entire imaging area as described above can be obtained. The present invention will be explained below with reference to the drawings. 1st
The figure is a schematic diagram of an embodiment of a focus detection device suitable for the focus detection processing method according to the invention.

1 is a subject; 2, 3, 4, and 5 are total reflection mirrors; 6 and 7 are projection lenses for projecting the image of subject 1 onto photoelectric conversion element groups 8 and 9; and 8 and 9 are photoelectric conversion elements. ,,(1
2...D5, d″1, d″2...d″
This is a photoelectric conversion element group having 5.

1, 2, and 3, for the purpose of simplifying the explanation, it is assumed that the number of elements in each photoelectric conversion element group is five, and that a photodiode is used as the photoelectric conversion element. 10 is an electrical processing device for realizing the electrical processing method according to the present invention.

FIG. 2 shows the light-receiving surface of each photoelectric conversion element/element of the photoelectric conversion element groups 8 and 9, and the rotation direction of the total reflection mirror 3 and the center line 3'' coincide with each other.

Note that the size of the light-receiving surface is the same for each photoelectric conversion element, and the photoelectric properties are all the same within each photoelectric conversion element group. Also optically,
Photoelectric conversion basic edition, and d″1, d2 and d″2...D
5 and d″5 correspond to each other, and outputs 11, i″1, . . . I5, l″5 are proportional to the amount of incident light. Third
Figures a to e illustrate the state in which the subject image on the photoelectric conversion element groups 8 and 9 moves due to the rotation of the total reflection mirror 3 in one direction. It shows that different subject images are projected onto the light receiving surface of each photoelectric conversion element.

FIG. 4 is a focus detection output diagram applying the conventional double image matching method, in which the horizontal axis corresponds to the focal point position, that is, the movement of the total reflection mirror 3 in FIG. 1.

The vertical axis shows the focus detection output at that time. FIGS. 5 and 6 show each focus detection output obtained by applying the electrical processing method according to the present invention.

Symbols A, b, c, d, and e in Figures 4 to 6 represent the third
They correspond to figures A, b, c, d, and e.

FIG. 7 shows an example of an electrical processing device 10 for realizing the electrical focus detection processing method according to the present invention, which includes a switch circuit 11, a logarithmic compression circuit 13, an amplifier circuit 12, an A/D converter 14, and an I/O board. 15, RONdOm-Acc
essMemOry (hereinafter referred to as RAM) 16, Rea
d-0n1yMem0ry (hereinafter referred to as ROM) 17,
A microprocessor 18, an I/O board 19, and a focus indicator and photographic lens control circuit 20 that receive a focus detection signal according to the present invention are included, and solid arrows indicate the direction of data (output of each photoelectric conversion element). , the dashed arrows represent the direction of each control signal. Figure 8 is an example of a case where a focus indicator is displayed in the finder 21, and when out of focus, L
An indicator 22 or 24 such as an ED is displayed, and when focus is achieved, 23 is displayed to make the photographer aware.

FIG. 9 shows a combined view of the total reflection mirror 3 and the photographing lens 26, which are combined by a lever 25 to complete the focus detection method according to the present invention.

Further, 27 indicates the main body of the camera. FIG. 10 shows an embodiment in which the microprocessor 18, switch circuit 11, etc. in FIG. 7 are not used, and the absolute value circuits Al, . A,...
・AJ4, Bl, B, ...BJ4, differential circuit C
l, Dl, comparators 28, 29, NOR circuit 30
, voltage dividing resistors Rl, r2, and terminals 31, 32, and 33 are signal terminals representing each focal position state.

Note that the symbol ε1 is an element that sets the focusing range (E
1〉O). Also Ll, L2...I-,,...L
n, L″1, L″2...L″5,...L″
. indicates a logarithmic compression circuit. FIG. 11 is a flowchart for controlling the entire circuit of FIG. 7.

Nao L. is an element for setting the focusing range like ε1. Next, each operation of the embodiment of the present invention will be explained according to the drawings.

In FIG. 1, a subject 1 passes through total reflection mirrors 2 and 4 and is projected onto a photoelectric conversion element group 8 by a projection lens 6, while a subject 1 passes through total reflection mirrors 3 and 5 and is projected onto a photoelectric conversion element group 9 by a projection lens 7. projected on. The image projected onto the element group 9 is a subject image corresponding to the rotation of the total reflection mirror 3. At that time, each photoelectric conversion element Dl, d2...D5,
d″1, d″2...d″5 have outputs 11, i2...I5, i″1, 1゛2 proportional to the amount of incident light.
. A detailed diagram of groups 8 and 9 is shown in Fig. 2. Dl, d2...
...D5, d''1, d''2...d''5 is each photoelectric conversion element constituting the photoelectric conversion element groups 8 and 9 as described above, and the figure shows the arrangement of the light receiving surface. The subject image of the subject 1 is projected onto the photoelectric conversion element group 8 at the same location regardless of the movement of the total reflection mirror 3, and at that time, the output of each photoelectric conversion element, . . . D5 is Il, i2, i3, l
4, obtain i5. Furthermore, a subject image moving in a direction parallel to the center line 3'' is projected onto the photoelectric conversion element group 9 by the rotation of the total reflection mirror 3. At this time, if the total reflection mirror 3 is rotated in only one direction, the photoelectric conversion The object image on the conversion element group 9 also moves in one direction, and in the focused state, the positionally equal object image is projected onto the opposing photoelectric conversion element group, so the output ratio between adjacent photoelectric conversion elements also changes. It will also be equal, i.e. 1
1/1215=i″4/i″5. In Figure 3, to simplify the subject image, the subject image with different illuminance is ◇O
In the diagram shown as Δ, which shows how the image changes due to the rotation of the total reflection mirror 3 in one direction, the right side of a-e shows the photoelectric conversion element group 8, which changes the subject image as described above. indicates a stationary state.

The figure on the left is a diagram of the state of the subject image projected onto the photoelectric conversion element group 9 when the total reflection mirror 3 scans in one direction, for example from far away from the subject to the near point, and the image is A. ，
It changes as b, c, d, and e. Figure c is a diagram in which the subject image is projected onto the photoelectric conversion element group 9 at exactly the same position as the subject image on the photoelectric conversion element group 8, indicating that focusing has been achieved. Now, the output of the photoelectric conversion element onto which the object image of the object marked ◇ is projected is a1 (however, a1>0), and the output of the photoelectric conversion element onto which the object image of the object marked O is projected is A2 (however, A2
〉0), A3 is the output of the photoelectric conversion element on which the object image of the Δ-marked object is projected (however, A3>0), and A is the output of the photoelectric conversion element on which no other object image is projected. (However, A.
>O), a1 half A2+. If A3≠AO, then in the conventional electric focus detection method that applies the double image matching formula, the focus detection output can be expressed as the sum of the absolute values of the output differences of the corresponding photoelectric conversion elements, so the focus detection output can be expressed as . If Ut is \I
Day 1 & breath m: It can be expressed as d19V~'l.

From now on, 10ge will be written as 10g.

However, n is the number of elements in each photoelectric conversion element group, I. ．． ,i″.
indicates the output of each photoelectric conversion element Dm, d''. FIG. 3 shows the case where n=5 in the above equation. The focus detection output (2) of a to e in FIG.

0, is, Therefore, at the focal point c, the focus detection output is ■.

, , will be 0, and will be a positive value in other cases. In other words, focus detection output ■ at the focal point. ．． t obtains the minimum value 0. Also, the focus detection output of a.■. . , and b, generally a>b
It is considered that 1 or e>d. The present invention is characterized in that focus detection can be performed including front and rear focus states that are out of focus, which cannot be recognized by the focus detection method described above.

That is, by determining the output difference between adjacent photoelectric conversion elements in the same group of the two photoelectric conversion element groups, the influence of output variations between the photoelectric conversion element groups is removed, the output difference is converted into an absolute value, and the photoelectric conversion element is Find the difference again diagonally between the conversion element groups,
Also, do the same thing with the diagonals in the opposite direction, find the difference between them,
Front focus, rear focus, and focus matching are detected based on their correlation, and when they match, the output difference becomes 0, so by detecting the ratio of the output difference to O, it is possible to detect focus matching. Based on the ratio, it is possible to determine whether the focus is true or false. Furthermore, by logarithmically compressing the output of the photoelectric conversion element, it is possible to cope with a wide range of brightness. The electrical processing method of the present invention is shown below, and each focus detection output 3 power is determined for each diagram in FIG. 3 based on the processing method.

(However, m=1, 2, 3...n-2) That is, ■ in the above equation. ．． The focus detection method according to the processing method of the present invention is to perform focus detection by detecting the ratio of positive, negative, and 0 values of I3(m). From a″e in Figure 3 to ■0ut1(m)9■0ut2〈m) and ■.U,3(
m), at this time ◇ on each photoelectric conversion element group 8, 9
, 0, and Δ are projected, and the outputs are respectively Al,
Assuming that a2, a3, a″1, a″2, a″3 are the outputs when there is no subject as AO and a″o, respectively, and there is no variation in the output within each photoelectric conversion element group, ■o=■
″0, ■1=V″1, ■2=■″2, V3=V″3, V
4=V″4 holds true.

(However, ■.Half V1, half V2, half ■3, half V4) Considering the above, ■ in a-e in Figure 3.

Utl(m),■01i2(m)9V0ut3(m))Next, in each figure. ．． T3 (n1) positive, negative, O
When counting the number of , (a) 0 positive values, 0 negative values, 0 values of 0, 3 unknown (b) 3 positive values, 0 negative values, 0 value 0, 0 unknown (C) 0 positive values, 0 negative values, 3 0 values, 0 unknown (d) 0 positive values, 3 negative values, 0 0 values , 0 unknowns (e) 0 positive values, 0 negative values, 0 0 values, 3 unknowns In the case of (a) and (e), the focus detection output V.

Although the sign of ut3 (g) is unknown, in the case of (a), it is the focus detection output V. . ll(6) is the focus detection output V. O. 2
(Compared to..., each output is far from the point where it becomes O, so in general
It seems likely that this will happen. Yotsute ■. Ut3(...
) is considered to have a large number of positive numbers. Similarly, in (e), ■. ．． It is thought that there are many negative numbers of 3. At the in-focus point (c), the focus detection output VO. l3 (VO.
The number of positive and negative outputs of l3 (..) is only 0, and the number of 0 outputs is the largest. Also (c)
When the subject image moves closer to the a side, the number of positive outputs increases, and on the (e) side, the number of negative outputs increases. In this way, the distinction between front focus, rear focus, and focus alignment is the focus detection output ■.

U. This can be done by detecting the number of positive outputs of 3, the number of negative outputs, and the number of 0 outputs. Note that if two out of the three outputs are known, the other one is automatically determined, so it is only necessary to detect the number of two out of the three outputs. Furthermore, since the output between the photoelectric conversion element groups is not directly calculated, there is no influence of variations between the photoelectric conversion element groups. FIGS. 4 to 6 show changes in each focus detection output depending on the focus position.

The symbols A, b, c, d, and e in the figures correspond to the focal positions of each figure shown in FIG. Figure 4 shows the focus detection output using the conventional double image matching method. . , which shows a minimum value of 0 at the focal point c, and positive values to the left and right of it. Figure 5 is ■. Detection output V for obtaining Ut3(6). ．． tl(.n) and V. It is a figure of ut2 (g). Generally, V in FIG. ．． l(m) and ■. Ut2(..) is the focus detection output V in FIG. O,
It can be considered that the minimum value 0 of is shifted left and right. That is, as explained in FIG. 3, the point at which the output difference between corresponding photoelectric conversion elements becomes O is the detection output ■. 0,1 (ml is point d, ■012 (6) is point b, and other points are the focus detection output ■ in Fig. 4.

. It follows the change in 1.

Furthermore, at the focal point c, as is clear from the explanation of FIG. 3, the focus detection output is ■. 0,1,. n) and ■Okan2(m
) take the same value, so ■0ut1(6) and ■0ut2(
The graphs of m) always intersect.

Figure 6 shows focus detection output■.

o,3 shows the changing state, and the solid line is V. . The number of positive outputs of 3, the dashed line is V.

. , is the number of negative outputs of . In this way, by using the focus detection method according to the present invention, focus detection output ■ is obtained before and after the focus matching position. The states of o and 3 change, and the state of the focal position can be determined. Note that the positive output of (2) 0ut3 also produces a slightly negative value l at points c to e as shown in the figure. The same applies to negative output. Furthermore, if there are some objects in focus that are out of focus, ■0. A case in which the output of t3 (Tn) becomes 0 is detected to some extent (this case is a pseudo-in-focus state), but the rate is smaller than in a true in-focus state. In the focus detection method according to the present invention, it is necessary that the object image on the photoelectric conversion element groups 8 and 9 maintain a certain degree of clarity within the detection range. Because when the clarity is lost ~
VO Rei 1 (m): 0) VO Rei 2 (m) half 0, so V.
．． The value is 7 because t3(6)-d is 0 and misfocus detection is performed. In this case, a method using an approximate contrast such that the output reaches its maximum value near the focal point, for example, may be used in combination with the sum of the absolute values of the differences in the outputs of adjacent photoelectric conversion elements. However, if the photographer is also provided with conventional eye focusing, he or she will recognize that the point at which the image loses sharpness is clearly out of focus.
It's not a big problem. FIG. 7 shows an example of an electrical processing device 10 for implementing the present invention, in which a microprocessor such as an Intel 8080 is used to control and calculate each circuit.

Photoelectric conversion elements Dl, d2 of photoelectric conversion element groups 8, 9...
...D5, d"1, d"2...The output of d"5 is proportional to the amount of incident light, and the microprocessor 18
The outputs 11, i2, . ...I5,i″1,1
``2...i''5 are each 10g (11), IOg
(12)・・・10g (15,10g(1″1)
, 10g (1″2)...10g (1″5). The output of each photoelectric conversion element described above is converted from an analog value to a digital value by the A/D converter 14, and
/O boat 15 and is stored in RAMl6 under the control of microprocessor 18, and sequentially stored in ROMl7.
Calculations are performed by a program stored in the I
Focus detection output (■) is passed through the /0 boat 19 to the circuit 20 for controlling the focus indicator, photographic lens, etc. Outputs 0t3.

In addition, Fig. 11 shows the microprocessor 1 in Fig. 7.
8 shows a flowchart of the control program of No. 8. This program is stored in the ROM mentioned above. Moreover, the switch circuit 11,
Although the order of the logarithmic compression circuit 13 and the amplifier circuit 12 may be arbitrary, the number of circuits configured before the switch circuit 11 is equal to the number of photoelectric conversion elements. The amplifier circuit 12 is not required unless necessary. ．． Furthermore, if logarithmic compression processing is performed within the microprocessor 18, the calculation time will increase, the program etc. will become complicated, and it will also take up a large amount of storage capacity, so it is not possible to perform the processing before the A/D converter 14 as shown in FIG. good.
By doing this, the ratio of focus detection outputs can be calculated as a difference, which is very advantageous in terms of the processor 18, program, storage capacity, etc.

That is, the formula for 10g(11/I2) is 10g(11)-1
0g (12), 10g (11) becomes A1, 10g (
12), then the above equation 4 becomes a simple subtraction equation of A1-. In addition, if there are various problems in the output between photoelectric conversion elements in the same group, such as variations due to manufacturing reasons, you can store the correction data in ROM17 and perform the following calculation. , variations in photoelectric conversion elements, etc. can be corrected. That is, in the same human light, the output of each photoelectric conversion element is α1, α2...α5, α1, α2
...α″5, and the output of each photoelectric conversion element when the subject image is incident is Jl,i2...I5,i″1,i
If "2...i"5, each corrected output of the photoelectric conversion element Pl, P2...P5, P"1, P
"2...P"5 is P1=i1/α1, P2=I
2/α2...P5=I5/α5, P″1=i″1
/α″1, P″2=i″2/α″2 ...P″5=
) i″5/α″5, and if logarithmically reduced, each output is 10g (P1) = 10g (11) - 10g (α1) ・
...and becomes a form of subtraction. Therefore, 10g for correction (
α1), 10g(α2), etc. are stored in the ROM, and the output from the logarithmically compressed output from each photoelectric conversion element becomes the output after correction. All you have to do is apply. FIG. 8 shows the focus detection output ■ according to the present invention.

. , 3, an example is shown in which a focus indicator is configured in the finder 21 to display the in-focus state. For example, when the indicators 22 and 24 such as LEDs are displayed, rotating the photographing lens in the direction of the displayed arrow approaches the in-focus state, and when in focus, the indicator 23 such as an IED is displayed. It's getting old. In this way, the focus indicator to which the present invention is applied is visually and sensually superior to the conventional eye focus adjustment mechanism. Note that in order to realize an automatic focus detection device, the above-mentioned focus detection output V is required. O. 3 to rotate, reverse rotate, or stop the motor for driving the photographic lens. In FIG. 9, the rotation of the photographic lens 26 and the rotation of the total reflection mirror 3 are connected by a lever 25, and by rotating the photographic lens by the photographer's hand, the total reflection mirror 3 also rotates, and the focus at that time is This is an example of a coupling mechanism for displaying a match state in a finder or the like. FIG. 10 shows an electrical processing device 10.
This is an example of realizing this without using the microprocessor, switch circuit, etc. shown in FIG.

That is, the focus detection output is ■0. ,1(M,=110ge(
1″4m-3/i″4m-2)-10ge(14..-
1/I4. n) 1 and ■0ut2(m): 110ge(14o./I4m-2
)-10ge(1″4..-1/i″4..): (However, m = 1, 2...(n+1)/4), Ll, L2... ...L5, ...Ln,
L″1, L″2...L″5,...L″.

is a logarithmic compression circuit, and absolute value circuits Al, Bl...
AJ4 and BJ4 inputs each have 10g (1″1/i″2
)-10g (13/I4), 10g (11/I2)-1
0g (1''3/i゛4)... is input.Therefore, the focus detection output V is input to one input terminal of the differential circuit C1.
. O,l(1), but the other input terminal has V. ut2
(1) is input, ■0ut1(1)>■0ut2(1
) i.e.■. If Ut3(1)>0, the voltage dividing resistor Rl,r
2, a divided voltage is generated at the (+) input terminal of the comparator 28. In other words, this output is ■. This is an output having a positive output of 0t3.

Also, the differential circuit D1 allows V, x. ,l(1KV0ut2
(1) That is, when Vou, 3 (1) <0, the voltage dividing resistor R
The output voltage divided by l and r2 is outputted from the comparator 29 (+
) terminal. In other words, this output is ■. This is an output portion with a negative output of 0.3.

Also, due to the other differential circuit C1. . ．． 3(..) is a positive output, the differential circuit 28 receives the output from the differential circuit D1.
. ,3,. ) is a negative output is input to the comparator 29. That is, V. When S Ot3 have positive outputs, the (+) input terminal of the comparator 28 has Sxr2.
×VO/(r1+R2) is input and comparator 2
O is input to the (+) input terminal of 9, and Sxr2×VO/
(r1+R2)> In the case of E1, the signal terminal 33 is Hi
gll, and by the NOR circuit 30, the 31st terminal is 10
The W1 or 32 terminal is also 10W, and the combination of this signal is
Control circuit 2 for focus detection indicator, photographic lens, etc. in Fig. 7
By inputting 0, the display 2 such as LED in Figure 8
2, 23, and 24, and can also be used to control the driving circuit of the photographing lens. Note that when the focus matches, that is, when the inputs to the (+) input terminals of the comparators 28 and 29 are smaller than ε1, the terminal 31 becomes Hlgh. That is, the terminals 32 and 33 indicate the front focus and rear focus states, and the terminal 31 indicates the in-focus state. ε1 indicates an element that sets the focusing range, VO indicates the supply voltage, and High>1
There is a relationship of 0w, and both High and lOw differential circuits Cl,
Dl, the comparators 28 and 29, and the output voltages of both poles of the NOR circuit 30 are shown, and there is a relationship of VO=HigFl.
If n is not a multiple of 4, photoelectric conversion elements will remain, so n is preferably a multiple of 4. FIG. 11 is a flowchart of a program when the microprocessor shown in FIG. 7 is used.

The logarithmically compressed outputs of each photoelectric conversion element from the I/0 boat 15 in FIG. 7 are expressed as Pl, P″1, P2, P″
2... P5, P''5 (however, the value of the number n of photoelectric conversion elements in the figure is 5) are read in order and stored in the RAM 16, taken out sequentially, and placed between predetermined photoelectric conversion elements. Obtain the output difference and obtain ■0.1<Ml9■0ut2(m).These are the terms (1) and (2) for calculation.Calculate (
In sections 3) and (4), convert the above value into an absolute value and perform calculations (5
) in term V. O. Subtraction is performed to find (g). Next ■
.

. Count the number of positive and negative 3 (..).

The value of the last row indicates the number of positive values, and L2 indicates the number of negative values. Depending on the value, L1 becomes L. When L2 is larger than L2, a front pin (or rear pin) signal is output, and when L2 is larger than L2, a rear pin (or front pin) signal is output, and both Ll and l2 are L. I/0 boat 1 outputs a focus signal when it is smaller than
9 and input to a control circuit 20 for the focus indicator, photographic lens, etc. still! is an element for setting the in-focus range, similar to the above-mentioned E1. Also, the switch circuit is controlled when reading Pm and P''., and the output of a predetermined photoelectric conversion element is input to the I/0 port 15.This cycle is repeated to perform focus adjustment.The start term is, for example, focus detection. This means activating a focus detection device such as a start switch.In this way, the computing power of a microprocessor is sufficient for simple functions such as addition/subtraction, judgment, and absolute value conversion.Also, photoelectric conversion The number n of elements may be any number, but the larger the number, the better.The format for processing the output of the photoelectric conversion element may be parallel or millial, analog value or digital value, and any base may be used for logarithmic compression. In this embodiment, only one of the subject images is biased by the mirror, but the mirrors may be biased in opposite directions.In other words, if the subject image is relatively shifted due to a change in the subject distance, any optical system can be used. Of course, a single-lens reflex camera may also be used.In this way, the present invention uses the focus detection output . It is possible to configure a focus indicator that detects , rear focus, and focus condition, removes false focus signals, and displays true focus, and also configures an automatic dynamic focus detection device. Not only does it provide an electrical focus detection device that can adequately track moving objects, it can also be applied to all electrical focus detection devices that apply the double image matching method, and it can also be applied to a wide range of distance measuring devices other than cameras. An electrical focus detection device is provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of a focus detection device suitable for the focus detection processing method according to the present invention. FIG. 2 is a configuration diagram of each light receiving surface of the photoelectric conversion element groups 8 and 9. Figure 3 A, b, c, d, and e are photoelectric conversion element groups 8 and 9.
This is a state diagram of the upper subject image, where A, b, c, d, and e indicate out-of-focus states, and c indicates in-focus states. FIG. 4 is an example of a focus detection output using the conventional double image matching method. FIGS. 5 and 6 are diagrams of focus detection outputs output by the focus detection method according to the present invention. FIG. 7 shows an example of an electrical processing device 10 for implementing the electrical focus detection processing method according to the present invention. FIG. 8 shows an example in which a focus indicator is provided within the finder 21. FIG. 9 shows an example of a method of combining the total reflection mirror 3 and the photographing lens 26. FIG. 10 is an example of an electrical processing device 10 for realizing the electrical focus detection processing method according to the present invention without using a microprocessor and a switch circuit. 1st
Figure 1 is No. 7 shows a flowchart for controlling the entire circuit of FIG. 1
: Subject, 2, 3, 4, 5: Total reflection mirror, 3″: Center line, 6, 7: Projection lens, 8, 9: Photoelectric conversion element group, 1
0: Electrical processing device, 11: Switch circuit, 12: Amplification circuit, 13: Logarithmic compression circuit, 14: A/D converter, 15,191/0 boat, 16R0nd0m-Acc
essMemOry(RAM), 17:Read-0n
1yMem0ry (ROM), 18: Microprocessor, 20: Control circuit for focus indicator, photographic lens, etc.
21 Finder, 22, 23, 24: Display device such as LED, 25: Lever, 26: Photographic lens, 27: Camera body, Cl, Dl: Differential circuit, 28, 29: Comparator, 30: NOR circuit , 31, 32, 33: signal terminals representing each focal position, Dl, 4...Dn, d
``1, d''2...d''.

Claims (1)

[Claims] 1. Dividing the same subject into two optically equal subject images, biasing each of the subject images in opposite directions or one side, and converting changes in the relative position of each of the subject images into electrical signals. In the focus detection optical system for projecting onto the second group of photoelectric conversion element groups, V is detected from the output of each of the photoelectric conversion element groups.
_o_u_t_(__m_)=｜loge(i'_m/i
'_m_+_1)-loge(i_m_+_1/i_m
＿＋＿２）｜,V_o_u_t_2_(__m_)=｜l
oge(i_m/i_m_+_1)-loge(i'_
m_+_1/i'_m_+_2) | and further V_
o_u_t_(_m_)=V_o_u_t_1_(_m
＿)−V_o_u_t_2_(__m_) (However, m=1,
2, 3... n-2), a circuit that determines the sign of V_o_u_t_3_(_m_), and a circuit that measures the number of outputs with the same sign. Device (where n is the number of elements in each photoelectric conversion element group, m is the number of the photoelectric conversion element and each output corresponding to it, i_1 to i_n, i'_1 to i'_n are proportional to the amount of incident light of each photoelectric conversion element ). 2. The focus detection device for a camera according to claim 1, characterized in that a photodiode is used in the photoelectric conversion element group. 3 V_o_u_t_1_(_m_) and V_o_u_
t_2_(_m_) is V_o_u_t_1_(_m_)
=｜loge(i'_4_m_-_3/i'_4_m_
-_2)-loge(i_4_m_-_1/i_4_m
) | and V_o_u_t_2_(_m_) = |loge(
i_4_m_-_3/i_4_m_-_2)-loge
(i'_4_m_-_1/i'_4_m) | (where m=
1, 2...(n+1)/4) A focus detection device for a camera according to claim 1, wherein the arithmetic circuit is configured so as to satisfy the following equation. 4. The camera focus detection device according to claim 1, characterized in that a microprocessor is used for calculation and control. 5. The camera focus detection device according to claim 4, wherein the output of the photoelectric conversion element is logarithmically compressed and then converted into digital data. 6. The camera focus detection device according to claim 4, characterized in that the storage device includes a correction amount for correcting variations in the output of each element of the photoelectric conversion element group.