JP3116358B2 - Focus detection photometer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection photometry device that obtains a highly stable photometry value using a focus detection device using a CCD line sensor.

2. Description of the Related Art Conventionally, there has been known a focus detection photometry device that obtains a spot photometry output at a central portion based on a photoelectric conversion output of a focus detection device that performs focus detection at a central portion of a shooting screen. For example,
Japanese Patent Application Laid-Open No. 62-188916 discloses a device that calculates the total average of the pixel outputs of a CCD line sensor provided for focus detection and uses it as a photometric value at the center.

[Problems to be Solved by the Invention] However, in a photometric device using such a conventional focus detecting device, that is, a so-called focus detecting photometric device,
When the focus detection area 100 has a cross-shaped two-dimensional shape as shown in the figure, the photometric value of a subject having a stripe-shaped luminance distribution 102 as shown in FIG. When calculated from the overall average, Fig. 16 (B)
When the angle of view is slightly changed as described above, the photometric value greatly fluctuates due to a slight change in the angle of view about the element width of the line sensor, and there is a problem that reliability and stability are lacking.

The present invention has been made in view of such a conventional problem, and has a stable and reliable photometry that is not affected by a slight change in the angle of view or the like from the output of the photoelectric conversion element array for focus detection. It is an object of the present invention to provide a focus detection photometry device capable of obtaining a value.

[Means for Solving the Problems] First, the present invention is directed to a focus detection device that obtains a photometric value based on a light receiving output of a first photoelectric conversion unit having a linear focus detection region.

According to the present invention, such a focus detection device includes a second photoelectric conversion unit having a linear focus detection region that intersects a focus detection region of the first photoelectric conversion unit, and a second photoelectric conversion unit. A photometric calculation means for calculating a photometric value by correcting a light receiving signal of the first photoelectric conversion means based on the output signal.

Here, the photometric calculation means includes a correction coefficient calculation means for calculating a correction coefficient from an output signal of the second photoelectric conversion means, and a photometry based on a value obtained by multiplying the output signal of the first photoelectric conversion means by the correction coefficient. And a photometric value calculating means for calculating a value.

Further, the correction coefficient calculating means obtains a correction coefficient based on an output signal of a portion where the first and second photoelectric conversion means intersect each other and an output signal of the second photoelectric conversion means.

Further, the correction coefficient calculating means, the output of the second photoelectric conversion means and _{(c 1, c 2, ···} , c m) and the output signal of the intersections of the first photoelectric conversion means (C _{k +1} , c _{k + 2} , ..., c _{k + i} )
Where f (c) = {(c ₁ +... + C _m ) / m} / {(c _{k + 1} +... + C _{k + i} ) / i} Is calculated as

Further, the photometric value calculating means multiplies the correction coefficient by the sum of outputs of the first photoelectric conversion means, and divides the result by the accumulation time of the photoelectric conversion means to obtain a photometric value.

The correction coefficient is determined based on a weighting coefficient corresponding to a position in the photoelectric conversion unit.

The correction computation means outputs a second photoelectric conversion means _{(c 1, c 2, ···} , c m), the weighting factor for the position in the second photoelectric conversion means (v ₁ to v _m ), The output signal of the intersection area with the first photoelectric conversion means is _represented by (c _{k + 1} , c _{k + 2} ,.
c _{k + i),} when the weighting coefficient for the position in the first photoelectric conversion means and (u ₁ ~u _m), the correction coefficient f a (c), f (c) = [{(v 1 × c ₁ ) + (v ₂ × c ₂ ) +... + (V _m × c _m )｝ / (v ₁ + v ₂ +... + V _m )] / [｛(v _k−1 × c _{k + 1)} ) + (V _k × c _k ) + (v _{k + 1} × c _{k + 1} )｝ / (v _k−1 + v _k + v _{k + 1} )].

[Operation] According to the focus detection photometry device of the present invention having such a configuration, when calculating photometry values of a subject having a two-dimensional spread in a shooting screen, line sensors (focus detection elements) crossing each other are calculated. In the case of, for example, an XY cross shape, it is considered that the distribution state of the element row output of the line sensor in the Y direction is satisfied in the vicinity along the line sensor in the X direction. The luminance of the subject in an area covered by the line sensor, for example, a rectangular area is estimated and calculated.

Therefore, the change in the angle of view, which is about the element width of the line sensor, which has been a problem in the related art, is so small as to be smaller than the size of the area to be measured, so that it has almost no effect, and a highly stable photometric value is obtained. be able to.

Embodiment First, the principle of the present invention will be described for a focus detection photometry device having a cross-shaped detection area 100 as shown in FIG.

In FIG. 1, the cross direction (X
Direction) A pair of light receiving element rows (photoelectric conversion element rows)
Row, B row, and the light receiving element row in the vertical direction (Y direction) is C row,
Let it be column D.

Here, the light-receiving outputs of rows A and B, where n light-receiving elements are arranged, are A
The received light data obtained by the D conversion is A = a1, a2,..., An B = b1, b2,..., Bn, and the received light output of the C and D columns in which m light receiving elements are arranged , C = c1, c2,..., Cm D = d1, d2,. For example, when the defocus amount is zero (at the time of focusing), the light receiving data A and B are obtained by re-imaging light beams that have passed through different pupil regions of the photographing lens for the same subject. They have the same value. Therefore, the value of (A + B) / 2 may be used as the luminance information of the subject, or only one of A and B may be used. Light reception data C, D
The same applies to. Hereinafter, the description will be made assuming that the light receiving data A and C are used as the luminance information.

 Next, an example of the luminance distribution of the subject is shown in FIG.

In FIG. 2, light receiving element row A is arranged on the X axis, and Y
The light receiving element rows C are arranged on the axis. The E axis orthogonal to the X and Y axes represents the brightness of the subject.

As the photometric value of the subject as shown in FIG. 2, an average height of a solid, that is, an average subject brightness is adopted as shown by a broken line in FIG. Here the light receiving element array A, Paying attention to the detection region and C, the data sequence a ₁ ~a _n of column A FIG. 4 (A)
As shown in FIG. 4, it is luminance distribution information of the X-axis cross section of the solid in FIG. 2, and similarly, the data strings c ₁ to _cm of the C column, as shown in FIG. This is luminance distribution information of the Y-axis cross section.

In normal photographing, the size of the subject is sufficiently larger than the focus detection area, and the luminance distribution has a two-dimensional spread over the photographing screen. Therefore, as a method for obtaining the average height (average subject brightness) “” of the solid shown in FIG. 3, the outputs of the light receiving element arrays for focus detection in the form of lines intersecting each other are multiplied, and one of the light receiving element arrays, for example, Y
It is considered that the output distribution state of the light receiving element array C in the axial direction is established also in the vicinity of the other light receiving element array, for example, along the light receiving element array A in the X-axis direction, and the two intersecting light receiving element arrays A and C cover. A method of calculating the average luminance of the subject in the rectangular area is used.

When now focusing on the intersection region of the light receiving element C1~Cm of the light receiving element A1~An and C columns from column A as shown in FIG. 5, present in the crossing area A _j-1 ~A _{j + 1} and C _k- Each of the three light receiving elements _{1 to} C _{k + 1} measures the same area. Therefore, A, C of the intersection area
The sum of the outputs of the light receiving elements in the column has the same value.

(A _j-1 + a _j + a _{j + 1} ) = (c _k-1 + c _k + c _{k + 1} ) Here, the output data c ₁ to _cm of the light receiving elements in column C are the light receiving elements Aj in the X-axis direction. Can be regarded as the luminance distribution information of the cross section in the Y-axis direction of the subject in the vicinity of the photometric region. That is, data metering along the luminance distribution of the subject on the Y-axis coordinate position of the X axis position of the light receiving element Aj is at c ₁ to c _m, the average photometry output of the Y-axis section.

For (c ₁ + c ₂ +... + C _m ) / m, the light receiving elements Aj in row A output the photometric data _aj as the photometric output.

Therefore, the average photometric data a _j ′ of the Y-axis slice cross section at the position corresponding to Aj on the X-axis can be expressed by the following equation.

a _j ′ = (c ₁ + c ₂ +... + c _m ) / m = (c _k-1 + c _k + c _{k + 1} ) × (c ₁ + c ₂ +... + cm) / ｛(c _k-1 + c _k + c _{k) +1} ) × m｝ = (a _j−1 + a _j + a _{j + 1} ) × (c ₁ + c ₂ +... + Cm) / ｛(c _k-1 + c _k + c _{k + 1} ) × m｝ a _j × 3 × (c ₁ + c ₂ +... + C _m ) / {(c _k-1 + c _k + c _{k + 1} ) × m} = a _j × {(c ₁ + c ₂ +... + C _m ) / m} / ｛( c _k-1 + c _k + c _{k + 1} ) / 3｝ = a _j × f (c) (1) where f (c) is a correction coefficient, and therefore, the correction coefficient f ( c) is obtained as f (c) = {(c ₁ + c ₂ +... + c _m ) / m} / {(c _k-1 + c _k + c _{k + 1} ) / 3} (2)

Similarly, the Aj-1 corresponding position, the Aj + 1 corresponding position, the Aj-2 corresponding position,..., The A1 corresponding position, and the An corresponding position may be considered to be similar to the Aj corresponding position in the luminance distribution in the Y-axis direction. _{, a j-1 '= a} j-1 × f (c) a j + 1' = a j + 1 × f (c) · · · · · · a n '= a n × f (c) is obtained Can be Therefore, the average photometry data of the rectangular area is expressed by the following equation.

a ′ = (a ₁ + a ₂ +... + a _n ) × f (c) / n (3) This equation (3) is finally summarized as follows.

_{a '= {(a 1 +} ... + a n) × (c 1 + ... + c m) × 3} / {n × m × (c k-1 + c k + c k + 1)} ··· (4) and The photometric value can be obtained by dividing the value calculated from Expression (4) by the CCD accumulation time and multiplying the result by a predetermined coefficient.

The principle of the photometric value calculation according to the present invention has been described above. FIG. 6 shows a flowchart of an algorithm for realizing the photometric value calculation.

First, step S1 in FIG. 6 (steps are hereinafter omitted)
It calculates an integrated value Σa of the pixel output a ₁ ~a _n from the light receiving element A1~An the A string like. Next, proceed to S2, and the light receiving element in column C
It calculates an integrated value Σc of the pixel output c ₁ to c _m from C1-Cm.
Next, in S3, the pixel output integrated value S of the vertical / horizontal row overlap portion is calculated from the three pixel outputs _ck-1 to _{ck + 1 of the} vertical / horizontal column A and the vertical / horizontal column C in the overlap portion. Next, the average photometric data a 'of the rectangular area is calculated as in S4, and finally, the average photometric data a' is divided by the CCD accumulation time T and multiplied by a predetermined coefficient B to calculate the photometric value as in S5.

Next, an embodiment in which the focus detection photometry device of the present invention is applied to a single-lens reflex camera will be described with reference to FIG.

In FIG. 7, the interchangeable lens 10 for the camera body 20 is detachably mounted on a mount. In a state where the lens 10 is mounted, a photographic light beam arriving from a subject passes through the photographic lens 11 and is partially reflected by a main mirror 21 provided on a camera body 20 and guided to a finder, and another part is a main mirror. The light passes through 21 and is reflected by the sub mirror 22 to be guided to the AF module 30 as a light beam for focus detection and photometry.

 An example of the configuration of the AF module 30 is shown in FIG.

In FIG. 8, the AF module 30 includes a field mask 31, a field lens 32, and two pairs of re-imaging lenses 28A, 28A.
A focus detection optical system 25 comprising B, 29A and 29B, and a photoelectric conversion means 3 such as a CCD comprising two pairs of light receiving sections 38A and 38B and 39A and 39B.
It is composed of five.

In such a configuration, two sets of regions 18A and 18B and a region 1 symmetrical with respect to the optical axis 17 included in the exit pupil 16 of the photographing lens 11
The light beams passing through 9A and 19B form a primary image near a field mask 31 having an opening shape corresponding to the entire focus detection area as shown in FIG. A part of the primary image formed at the opening of the field mask 31 is further combined with the field lens 32 and two sets of re-imaging lenses 28A and 28B and 29A and 29B to form two sets of light receiving parts 38A and 38B of the photoelectric conversion means 35. A pair of secondary images is formed on each of 39A and 39B.

As is well known, by detecting the relative positional relationship between the paired secondary images in the light receiving portion arrangement direction on the photoelectric conversion means 35, the defocus amount of the photographing lens can be detected.

FIG. 9 shows the arrangement of the light receiving section on the photoelectric conversion means 35. The light receiving sections 38A and 38B each include n light receiving elements A1 to An and B1 to B
n, when the primary image coincides with the film surface (at the time of focusing), the corresponding light receiving elements, ie, A1 and B1, A2 and B2,
Are arranged to be equal. The same applies to the light receiving units 39A and 39B.

The light-receiving elements forming the light-receiving sections 38A, 38B, 39A, and 39B are configured by charge storage elements such as photodiodes, and perform charge storage for a charge storage time according to the illuminance on the photoelectric conversion means 35. The output of the light receiving element can be controlled to an appropriate output level.

Referring again to FIG. 7, the sensor control means 40
A charge accumulation start and end command is received from the port P3 of 00, and a control signal corresponding to the command is given to the photoelectric conversion means 35 to control the charge accumulation time of the photoelectric conversion means 35. Also, a transfer clock signal or the like is given to the photoelectric conversion means 35, and the light receiving element signal output is transferred to the CPU 100 in time series.
To port P3. The CPU 100 starts the AD conversion of the light receiving element output signal input to the port P1 by the built-in AD converting means in synchronization with this signal, and obtains AD conversion data according to the number of light receiving elements. When the AD conversion is completed, the defocus amount is detected from the obtained data by a three-point interpolation method disclosed in Japanese Patent Application Laid-Open No. 60-37513 by the present applicant.

After calculating the defocus amount by processing the data, the CPU 100 displays the display units 51, 5 of the AF display means 50 based on the defocus amount.
The display mode of 2, 53, 54 is controlled using the port P2. The setting information (AF mode, MF mode) of the AF mode selection means 76 is sent to the port P11 of the CPU 100, and when the AF mode is set, C
The PU 100 controls the driving direction and the driving amount of the AF motor 60 using the port P12 based on the defocus amount, and moves the photographing lens 11 to a focal point via the photographing lens drive system 65.

The CPU 100 performs data processing in accordance with the algorithm shown in FIG. 6 based on the obtained data before or after the calculation of the defocus amount in parallel or in time series, and calculates the photometric value. Further, photometric values other than the spot photometric value are calculated based on the output signal of the photometric means 90 sent to the port P5. CPU100
Is based on the spot metering or other metering mode setting information of the metering mode selection means 78 sent to the port P9,
The display mode of the display units 81 and 82 of the photometric display unit 80 is controlled using the port P4. Further, the setting information (manual, shutter priority A) of the AE mode selection means 77 sent to the port P10
E, aperture priority AE, program AE, daylight sync, etc.), the CPU 100 determines the shutter control unit 70, the aperture control unit 72, and the flash control unit from the calculated photometric value.
74 is controlled singly or in parallel using ports P6 to P8 to give proper exposure to the film.

The above is the outline of the configuration and operation of the embodiment in which the focus detection photometry device according to the present invention is applied to a single-lens reflex camera.

Next, the fact that the photometric value calculation method of the present invention has higher stability than the conventional photometric value calculation method will be described.

As a conventional example, there is known a method of calculating photometric data as a total average of light receiving element data. The calculation formula is as follows.

_{a "= (a 1 + a} 2 + ... + a n + c 1 + c 2 + ... + c m) / (n + m) , where. during the first metering considered a subject having a luminance distribution shown in FIG. 10, n = 99 pieces The light receiving data a1 to a99 of the light receiving elements A1 to A99 have the values shown in FIG. 11 (A), and m = 4
It is assumed that the light receiving data c1 to c49 of the nine light receiving elements C1 to C49 have the values shown in FIG. 11B.

In this case, the photometric data a ″ according to the conventional method and the photometric data a ′ according to the present invention are as follows.

[Conventional] a ″ = (a ₁ + a ₂ +... + A ₉₉ + c ₁ + c ₂ +... + C ₄₉ ) / (99 + 49) = {(200 × 99) + (50 × 23) + (200 × 26)} / 148 = 26150/148 = 177 [present _{invention] a '= {(a 1} + ... + a 99) × (c 1 + ... + c 49) × 3} / {(99 × 49 × (c 24 + c 25 + c 26)} = [(200 × 99) + {(50 × 23) + (200 × 26)} × 3] / {99 × 49 × (200 × 3)} = 130 Next, if the shooting angle of view is slightly changed, Then, the photometric data as shown in FIG. 12 is obtained by the photometry, and the conventional data a ″ and the data a ′ of the present invention are as follows.

[Conventional] a ″ = {(50 × 99) + (50 × 26) + (200 × 23)} / 148 = 73 [Invention] a ′ = [(50 × 99) × ｛(50 × 26) + (200 × 23)｝ × 3] / {99 × 49 × (50 × 3)} = 120 As is clear from this specific example, according to the conventional method, the photometric data is 59% due to a slight change in the angle of view. , While the method of the present invention falls within a 9% change.
The change in the photometric value according to the method of the present invention with respect to the change in the angle of view is close to the change in the photometric value of the spot photometric method using a conventional SPD light receiving element, and is equivalent to the conventional feeling of use and has little uncomfortable feeling. Operability is good.

As described above, the focus detection photometry device according to the present invention can obtain a photometry value with high stability and good operability, but the method of calculating the photometry value is not limited to the above.

As an application example of the above-described calculation method of the present invention, by multiplying the light receiving element data by a weighting coefficient corresponding to the position of the light receiving element, a center-weighted spot metering device or a lower-weighted spot metering device can be obtained. Is also possible.

Hereinafter, an application example of multiplying by a weighting coefficient will be described.

If the weighting coefficient for the pixel output c ₁ to c _m of the light-receiving element C1~Cm column C v and ₁ to v _m, the first (2) for obtaining the correction coefficient f (c) is amended as follows Can be

f (c) = [{( v 1 × c 1) + (v 2 × c 2) + ... + (v m × c m)} / (v 1 + v 2 + ... + v m)] / [{(v _{k-1 × c k-1} ) + (v k × c k) + (v k + 1 × c k + 1)} / (v k-1 + V k + v k + 1)] ··· (5) then, the weighting factor for the pixel output a ₁ ~a _n of light receiving elements A1~An column a if u ₁ ~u _n, with the weighting coefficients of the Y-axis slice sections at Ai corresponding positions in an arbitrary position The average photometric data _ai 'is given by the following equation.

a _i ′ = u _i × a _i × f (c) (6) Therefore, the light receiving elements A1 to An in row A and the light receiving element C1 in row C
Equation (3) for calculating the average photometric data of a rectangular area composed of .about.Cm is given by the following equation after receiving weighting corresponding to i.

_{a '= [{(u 1} × a 1) + (u 2 × a 2) + ... + (u n × a n)} × f (c)] / (u 1 + u 2 + ... + u n) ·· - (7) the weighting factor u ₁ ~u _n and v ₁ to v _m may be a continuously and smoothly varying variable, for the calculation simpler, some sections to set the stepwise heavy with May be set so as to change. To give an example of the center-weighted formula,
As shown in FIGS. 17 (A) to 17 (C), the light receiving elements A1 in row A
The light-receiving elements C1 to Cm in the columns .about.An and C are each divided into three sections, and the weighting coefficient for each section may be set as follows.

For column A (A1 to An), the following three sections are weighted as shown in FIG. 17 (A). Section 1 ≦ i <(n / 3): u _i = 1 section (n / 3) ≦ i ≦ {(2 × n) / 3}: u _i = 2 section {(2 × n) / 3} < i ≦ n: u _i = 1 Similarly, weighting is applied to the C columns (C1 to Cm) as shown in FIG. 17 (B). Section 1 ≦ i <(m / 3): v _i = 1 section (m / 3) ≦ i ≦ {(2 × m) / 3}: v _i = 2 section {(2 × m) / 3} < i ≦ m: v _i = 1 Accordingly, when weighting is performed on the rows A and C as described above, the shape of the photometric sensitivity distribution (relative sensitivity by weighting) of the rectangular area becomes as shown in FIG. 17 (C). .

In addition, as an example of the lower-priority type, when the CPU 100 determines that the direction of the light receiving element C1 in column C is heaven and that the direction of Cm is ground by an attitude detecting means or the like not shown in FIG. ,
The weighting coefficient for each section may be set as follows.

For column A; interval 1 ≦ i <(n / 3): u _i = 1 interval (n / 3) ≦ i ≦ {(2 × n) / 3}: u _i = 2 interval ｛(2 × n) / 3｝ <i ≦ n: u _i = 1 For column C; section 1 ≦ i <(m / 3): v _i = 1 section (m / 3) ≦ i ≦ {(2 × m) / 3}: v _i = 2 Section {(2 × m) / 3} <i ≦ m: v _i = 2 The division of the section is not limited to three, and the assignment of weighting coefficients is not limited to the above. .

The weighting coefficient may be automatically selected by the CPU 100 according to the characteristics of the light receiving element data, or may be selected by the light metering mode selection unit 78 or AF.
The selection may be made in conjunction with the mode selection means 76.

A plurality of weighting coefficients can be set.
As shown in FIGS. 13 (A) to 13 (C), in accordance with the setting of the center emphasis in the photometric display means 80, when the center emphasis is low, similar to the contour display of the map, FIG. Thus, when the center importance is medium, the display is performed as shown in FIG. 13B, and when the center importance is high, the display is performed as shown in FIG. 13C.

Also, the output contrast of the light receiving element data is much more extreme than in the examples of FIGS. 10 (B) and 11 (B), and the reliability of the data in the low output part is extremely low, If it is determined that there is no photometry value, the area for photometric value calculation may be limited. For example, when the output in the vicinity of the last received light data an in the row A is extremely low, or when the output in the vicinity of the first received light data a1 and in the vicinity of the last received light data an is extremely low, FIG. Photometric display means 80
The limited photometric value calculation area shown in FIGS. 14B and 14C is displayed from the area display of FIG.

Further, as an example of the photometric value calculation algorithm of the focus detection photometric device according to the present invention, a correction coefficient is first obtained from the element outputs of the light receiving element rows in the vertical direction, and then multiplied by the sum of the element outputs of the light receiving element rows in the horizontal direction. Although the algorithm for calculating the photometric data was shown, the conversely, first, a correction coefficient was obtained from the element outputs of the light receiving element rows in the horizontal direction, and then multiplied by the sum of the element outputs of the light receiving element rows in the vertical direction to obtain the photometric data. It goes without saying that an algorithm for calculation may be used.

Specifically, the pixel output integrated value S of the vertical and horizontal A and C column overlap portions in S3 in FIG. 6 may be calculated from a _{j-1 to} a _{j + 1} .

Since (a _j-1 + a _j + a _{j + 1} ) and (c _k-1 + c _k + c _{k + 1} ) have the same value, the calculated photometric data is also the same.

Although the present embodiment has been described with reference to the case where the detection area of the similar two-dimensional shape is a cross shape, in the case of the H shape as shown in FIG. ₁ using a to c _m and receiving data e ₁ to e _m of column E, the region sandwiched by the light-receiving element array C1~Cm and E1~Em is, c ₁ ~ in the manner described in the specification of the present invention Correction coefficient g obtained from _cm
And (c), may be used an intermediate value of the correction coefficient g (e) obtained from e ₁ to e _m multiplied in a ₁ ~a _n.

More specifically, the correction coefficient g (c) obtained from c ₁ to _cm when the light receiving data of the C column in the intersection area between the A column and the C column is c _{k−1 to} c _{k + 1.} ) Is as follows.

g (c) = {(c ₁ + c ₂ +... + c _m ) / m} / {(c _k−1 + c _k + c _{k + 1} ) / 3} (8) The received light data of column E in the intersection area of
if _{e k-1 ~e k + 1} , the correction coefficient obtained from the e ₁ to e _m g
(E) is similarly expressed by the following equation.

g (e) = {(e 1 + e 2 + ... + e m) / m} / {(e k-1 + e k + e k + 1) / 3} ··· (9) an intermediate of the two correction factors if the use of a simple average as the value, the correction factor by multiplying the a ₁ ~a _n is, g (c, e) = {g (c) + g (e)} / 2 ··· (10) , and the The average photometric data a _i ′ with the weighting coefficient of the Y-axis slice section at an arbitrary position corresponding to Ai is given by the following equation.

a _i ′ = u _i × a _i × f (c) Therefore, the average photometry data of the rectangular area is finally expressed by the following equation.

_{a '= {(a 1 +} a 2 + ... + a n) × g (c, e)} / n = [{(a 1 + a 2 + ... + a n) × 3} / (n × m × 2)] × [(C ₁ + c ₂ + ... + c _m ) / (c _k-1 + c _k + c _{k + 1} ) +｝ (e ₁ + e ₂ + ... + e _m ) / (e _k-1 + e _k + e _{k + 1} ) ｝] (11) The method of obtaining the correction coefficient of the intermediate value is not limited to the above. For simplicity of calculation, g
In the case where (c) and g (e) can be regarded as substantially the same, g (c, e) = g (c). In this case, Expression (8) becomes the same as Expression (4). The same is obvious even when g (c, e) = g (e). Further, it is needless to say that the weighting coefficients can be multiplied together.

Also, it determines the interpolation correction coefficient h (i) according to the distance from the column C and column E of a ₁ ~a _n, may be multiplied in a ₁ ~a _n.

 Hereinafter, a method of obtaining the interpolation correction coefficient h (i) will be described.

The correction coefficient g (c) obtained by the above equation (5) is A
This is a correction coefficient based on luminance distribution information of a cross section in the Y-axis direction of the subject near the photometric region of the light receiving element A1 in the row. Further, the correction coefficient g (e) obtained by the above equation (6) is a correction coefficient based on the luminance distribution information of the section in the Y-axis direction of the subject in the vicinity of the photometry area of the light receiving element An in the A-th row.

Therefore, among the light receiving elements A1 to An in row A on the X-axis, the average photometric data _ai 'of the Y-axis slice cross section at an arbitrary position corresponding to Ai is _ai ' = a if Ai is close to A1. regarded as _i × g (c), Ai is the closer to an, regarded as _{a i '= a i × g} (e). When Ai is located between A1 and An, it can be considered that _ai ′ = _ai × {g (c) + g (e)} / 2.

From the above relationship, when the interpolation correction coefficient h (i) as a function of i representing a continuous position is expressed as an equation, the following equation is obtained.

h (i) = [{(n−i + 1) × g (c)} + {(i−1) × g (e)}] / n (1 ≦ i ≦ n) (12) The average photometric data a _i ′ of the Y-axis slice cross-section at the position corresponding to Ai at the position (1) can be expressed by the following equation.

a _i ′ = h (i) × a _i (13) The average photometric data of the rectangular area composed of the light receiving element rows C1 to Cm, E1 to Em and A1 to An is given by the following equation. Become.

a ′ = {(a ₁ × h (1)) + (a ₂ × h (2)) +... + (a _n × h (n))} / n (14) The interpolation correction coefficient h The method of obtaining (i) is not limited to the above. For example, for simplicity of calculation, A
The light receiving elements A1 to An in the row may be divided into three sections, and the interpolation correction coefficient h (i) for each section may be represented by the following numerical values.

Section 1 ≦ i <(n / 3): h (i) = g (c) Section (n / 3) ≦ i ≦ {(2 × n) / 3}: h (i) = {g (c) + g (E)｝ / 2 section {(2 × n) / 3} <i ≦ n: h (i) = g (e)
The division of the section is not limited to three. Also,
Of course, the weighting coefficients can be multiplied together.

[Effects of the Invention] As described above, according to the focus detection photometry device of the present invention, a large change in photometry value due to a slight change in the angle of view can be avoided, and a stable photometry value can be obtained with high accuracy. In addition, the operability is good because it has characteristics similar to those of the conventional spot metering.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a detection area of the present invention; FIGS. 2 and 3 are explanatory views of an example of a luminance distribution of a subject; FIG. 4 is an explanatory view of a light receiving element output corresponding to FIGS. FIG. 5 is a partially enlarged view of a detection area; FIG. 6 is a block diagram relating to photometric value calculation of the focus detection photometry device according to the present invention; FIG. 7 is a configuration diagram of the focus detection photometry device according to the present invention; FIG. 9 is a diagram illustrating a photoelectric conversion unit; FIG. 10 is a diagram illustrating an example of a luminance distribution of another subject; FIGS. 11 and 12 are diagrams illustrating a detection optical system used in the present invention; FIG. 13 is an explanatory view of an application example of the photometric mode display means; FIG. 14 is an explanatory view of another application example of the photometric mode display means; FIG. 15 is a view of another detection area. FIG. 16 is an explanatory view showing an example of a subject to explain a conventional problem when the angle of view is slightly changed; FIG. A) ~ (C) is an explanatory view of the sensitivity distribution profile applications multiplied by the weighting factor. [Description of Signs of Main Parts] 10: Photo Lens 20: Camera Body 30: AF Module 50: AF Display 60: AF Motor 80: Metering Mode Display 100: CPU

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Iwasaki 1-6-3 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Works Co., Ltd. (56) References JP-A-62-188916 (JP, A) Sho 62-19824 (JP, A) JP-A Sho 62-6231 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B ^7/ 00-7/28 G02B ⁷ /28-7 / 40 G03B 3/00-3/12

Claims (7)

(57) [Claims] 1. A focus detection device for obtaining a photometric value based on a light reception output of a first photoelectric conversion means having a linear focus detection area, wherein the linear detection means has a linear focus detection area of the first photoelectric conversion means. A second photoelectric conversion unit having a focus detection area, and the first photoelectric conversion unit based on an output signal of the second photoelectric conversion unit.
And a photometric calculation means for calculating the photometric value by correcting the light receiving signal of the photoelectric conversion means. 2. The photometric operation means includes: a correction coefficient operation means for calculating a correction coefficient from an output signal of the second photoelectric conversion means; and a multiplication coefficient multiplied by the output signal of the first photoelectric conversion means. 2. The focus detection / photometry device according to claim 1, further comprising: a photometry value calculation unit configured to calculate the photometry value based on the calculated value. 3. The correction coefficient calculating means includes: an output signal at a portion where the first and second photoelectric conversion means intersect each other;
The focus detection photometry device according to claim 2, wherein the correction coefficient is obtained based on an output signal of the second photoelectric conversion unit. Wherein said correction coefficient calculating means, outputs of said second photoelectric conversion means _{(c 1, c 2, ···} , c m) and, the first
(C _{k + 1} , c _{k + 2} ,
.., C _{k + i} ), the correction coefficient f (c) is expressed as f (c) = {(c ₁ +... + C _m ) / m} / ｛(c _{k + 1} +. The focus detection photometry device according to claim 2 or 3, wherein the focus detection photometry device is calculated as + c _{k + 1} ) / i｝. 5. The photometric value calculating means calculates a photometric value by multiplying the correction coefficient by a total sum of outputs of the first photoelectric conversion means and dividing by a storage time of the photoelectric conversion means. 3. The focus detection photometer according to claim 2, wherein: 6. The focus detection photometer according to claim 2, wherein the correction coefficient is determined based on a weighting coefficient corresponding to a position in the photoelectric conversion means. Wherein said correction calculation means, wherein the output of the second photoelectric conversion means _{(c 1, c 2, ···} , c m), the weighting factor for the position of the photoelectric conversion means of the second (V _{1 to} v _m ), the output signal of the intersection area with the first photoelectric conversion means is _represented by (c _{k + 1} , c _{k
k + 2} ,..., c _{k + i} ), and when the weighting coefficient for the position in the first photoelectric conversion means is (u _{1 to} u _m ), the correction coefficient f
(C) is calculated by f (c) = [{(v ₁ × c ₁ ) + (v ₂ × c ₂ ) +... + (V _m × c _m )} / (v ₁ + v ₂ +... + V _m )] / [{(V _k-1 × c _{k + 1} ) + (v _k × c _k ) + (v _{k + 1} × c _{k + 1} )} / (v _k-1 + v _k + v _{k + 1} )] 7. The focus detection device according to claim 6, wherein the calculation is performed.