JPH04538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures light by dividing a field into a plurality of regions, and extracts a proper light metering output for determining the proper exposure of the entire screen from a plurality of photoelectric outputs corresponding to the regions. This paper relates to improvements to multi-photometering devices.

The reason for dividing the field into multiple areas and metering is to obtain proper exposure even when shooting in backlit conditions. However, when high-brightness areas such as the sun enter the screen, conventional equipment results in images that are significantly underexposed. This is because even if the high-brightness area is only in one part of the screen, the absolute amount of brightness is greater than that of the main subject, and even if the brightness of both is averaged, the average value will be considerably larger than the brightness of the main subject.

On the other hand, when obtaining multiple photoelectric outputs corresponding to multiple areas, although part of the screen is below the photometric lower limit,
Photometry may be possible for the remaining portion. For example, this may be the case when the subject is illuminated by a spotlight. In contrast, conventional devices were almost powerless.

Furthermore, when the contrast in the screen is high, controlling the exposure for high-brightness or low-brightness areas can result in a photograph in which the low-brightness or high-brightness areas are crushed, making it unpleasant to view. be.

The purpose of the present invention is to analyze the situation of the subject based on the photoelectric output, and to obtain an appropriate photometric output even for the subject under the above-mentioned special conditions, especially when the screen contrast is high. The purpose of the present invention is to provide a multi-photometering device that has the following features.

Hereinafter, the field of view (hereinafter referred to as the screen) is the bottom surface,
The basic idea of the present invention will be described with reference to FIG. 1, which shows the screen and the brightness of each part of the screen as a three-dimensional diagram, with the brightness of each part of the screen being the height (vertical axis). When considering a screen as shown at the bottom surface S ₀ in FIG. 1a, the brightness of the screen determines one curved surface S ₁ . In reality, since photometry is performed using a finite number of photoelectric elements, the number of curved images that can be set up is a set of planes with the same number or fewer as the number of photoelectric elements. For example, when the screen is divided vertically, horizontally, and horizontally using four photoelectric elements, the curved surface representing the brightness of the screen is quantized and divided into stages as shown by quantization surfaces S ₂ to _{S 4} in Figures 1b and 1c. become. When comparing quantization planes S ₂ and S ₄ , the absolute levels of the brightness that make up the quantization planes are the same, but their positions on the screen are different, so it is difficult to obtain the correct exposure for which brightness. The judgment is also different. Also, when comparing quantization planes S ₂ and S ₃ , the level difference between adjacent luminances is the same, but the absolute value of the luminance between both quantization planes is different, so
Judgment for obtaining appropriate exposure will also be different. Now, we classify the shooting screen under all conditions into multiple categories based on information regarding brightness and information regarding position, and determine which brightness should be controlled for exposure in each category to obtain an overall appropriate exposure. Attach the correspondence. Then, on a screen under certain conditions, the brightness at which exposure control should be performed can be obtained from the information regarding the brightness and the information regarding the position.

In fact, as a result of making the above correspondences for screens under various conditions, it has been found that the brightness at which exposure control should be performed in order to obtain photographs with proper exposure converges to the following three levels. That is, the first brightness level exists between the maximum value of a plurality of photometric outputs and the average value of these photometric outputs;
The brightness level of is a level that almost matches the average value of these photometric outputs, and the third brightness level exists between the minimum value of these photometric outputs and the average value of these photometric outputs. There was found. This average value can be approximated by an average value, a median value, or a mode value.

From the above, if we compare the average value of multiple photoelectric outputs with each photoelectric output and standardize the brightness of each divided screen, we can simultaneously obtain information on the position and brightness of each screen. You will be able to do this. Therefore, the screen condition is detected by pattern analysis based on this normalized output, and this detection result is combined with the above 3.
By experimentally or empirically making these two brightness levels correspond to each other, it is possible to select the brightness level at which exposure should be controlled for the screen under various conditions.

On the other hand, the brightness level at which exposure should be controlled may be determined independently of pattern analysis. The difference between the maximum brightness and the minimum brightness is within a predetermined range, the variation in brightness within the screen is small, and the maximum brightness is within a predetermined range, and the bright light source spot light including the sun is present within the screen. This is a case where it can be determined that no such artificial light source exists. In this case, it has been found that good results can be obtained by adjusting the exposure for the second brightness level.

In addition, if there is a high brightness area represented by the sun or a low brightness area below the photometry lower limit in the screen, when setting the levels of the first to third brightness levels described above, the maximum value corresponding to the high brightness area and the photometry By ignoring the minimum value corresponding to the low brightness area below the lower limit, or by replacing these maximum and minimum values with other brightness values that exist within the screen, it is possible to obtain photometric information with proper exposure that is not affected by extreme high and low brightness. .

Furthermore, when adjusting the exposure to the first and third brightness levels, if the difference between the maximum brightness and the minimum brightness is more than a predetermined value, both brightness levels are corrected toward the second brightness level, thereby increasing the brightness. It is also possible to prevent photographs with blurred areas or low-brightness areas.

The present invention will be explained below based on examples. FIG. 2 is a block diagram showing an embodiment of the present invention. In the same figure, a photometry circuit 10 includes a photoelectric conversion element for photometering each area in which the field of view is divided into a plurality of areas,
It outputs independent analog photoelectric outputs P ₀ to _{P o-1} corresponding to each area of the field. It is assumed that the photoelectric outputs P ₀ to P _o-1 have been logarithmically compressed together with the film sensitivity (SV) information, and therefore the photoelectric outputs are expressed in EV values. The first maximum value detection circuit 100 has a photoelectric output
The maximum value Pmaxoriginal is detected from P ₀ to _{P o-1} . Also, the first minimum value detection circuit 99 similarly has P ₀
Detect the minimum value Pminoriginal from ~P _o-1 .
Further, as will be described later in the explanation of the blocking circuits 101 and 102, the second maximum detection circuit 11 outputs photoelectric power via analog switches 103 and 104.
Among P ₀ to _{P o-1,} those that do not exceed the threshold level are input, and the maximum value Pmax is detected from among these.
The average value detection circuit 12 is an analog switch 10.
5,106, the photoelectric outputs _P0 to Pn-1 that are between a plurality of threshold levels are input;
The average value of these, for example, the average value Pmean is detected. The second maximum value detection circuit 13 receives as input the photoelectric outputs P ₀ to _{P o-1} exceeding the threshold level through the analog switches 107 and 108, and detects the minimum value Pmin from these. Arithmetic circuit 14
receives the maximum value Pmax and the average value Pmean as input and generates the first photometric output PH (EV), that is, PH= _k1Pmax +(1- _k1 )Pmean (1). The arithmetic circuit 15 outputs the second photometric output PM.
(EV), that is, PM=Pmean (2), and can actually be used as the average value detection circuit 12. The arithmetic circuit 16 calculates the minimum value Pmin and the average value
Pmean and the third photometric output PL (EV),
That is, PL= _k2Pmin +(1- _k2 )Pmean...(3) is generated. The circuits 11 to 16 described above constitute an appropriate photometric output generation circuit. The arithmetic circuit 110 receives the photometric outputs PH and PM from the circuits 14 and 15, and outputs the fourth photometric output, that is, PHM=w ₁ · PH+
Outputs w ₂ ·PM (where w ₁ and w ₂ are weighting constants for the measurement output). Arithmetic circuit 111 is connected to circuits 15 and 1
The photometric outputs PM and PL are applied from 6 and 5.
Photometric output, i.e., PLM=w ₃・PM+w ₄・PL
(However, w ₃ and w ₄ are weighting constants for photometric output). The binarization circuit 17 is a part that performs standardization, and inputs the photoelectric outputs P ₀ to _{P o-1} and the average value P _neao , and outputs the reference output generated based on the average value Pmean and the photometry P ₁ to _{P o -1} to convert each photoelectric output to a logical output. Specifically, in the example,
The output Pi at the i-th position is compared with the average value Pmean, and if Pi≧Pmean, it is set to 1, and if Pi<Pmean, it is set to 0. If the normalized output is 1, then
This indicates that the i-th position is a brighter-than-average portion, and 0 indicates that it is a darker portion. That is, the standardization described above takes the form of binarization.

Alternatively, you can do the following. As a reference output based on the average value Pmean to divide the overall brightness into bright parts, dark parts, and intermediate parts.
In this method, Pmean + δH and Pmean - δL are set, and binarization is performed for each of these two reference levels. That is, 1 when Pi>Pmean+δH holds, 0 when Pi≦Pmean+δH holds, 1 when Pi≧Pmean−δL, and Pi<Pmean
It is set to 0 when −δL. In this case, the binarized output at the i-th position is two (2 bits). Pmean+δH,
When the outputs are arranged in the order of comparison of Pmean−δL, if the output is 11, it indicates a bright part, if the output is 00, it indicates a dark part, if it is 01, it indicates a part close to the average value (if it is 10, it does not exist) ). By dividing the brightness at that position into three levels in this way, more advanced pattern analysis becomes possible.

Of course, it is also possible to divide the binarization circuit into four or more stages, and the way of division may be changed depending on the position.

Next, the first judgment circuit 18 inputs the maximum value Pmax, judges Pa≦Pmax≦Pβ (4) (where Pa and Pβ are constants), and generates a logical output representing the judgment result. . Of course, the first determination circuit 18 is Pa,
Includes a circuit that generates a reference output corresponding to Pβ.
This determination operation is performed to identify whether the maximum value Pmax is caused by a bright light source including the sun or an artificial light source such as a spotlight.

The second judgment circuit 19 determines the maximum value Pmax and the minimum value
Using Pmin as input, calculate ΔP=Pmax−Pmin...(5), then judge a≦ΔP≦β...(6) (however, a and β are constants), and display the judgment result. Generates a logical output. Of course, the second determination circuit 19 includes a circuit that generates reference outputs corresponding to the constants a and β. This judgment operation judges the brightness distribution of the screen, and for example, if the brightness distribution is large and the main subject is on the low brightness side, the high brightness side will adjust the exposure to the low brightness side, or vice versa. This is done to prevent the phenomenon where if the main subject is on the bright side and the exposure is adjusted to the high brightness side, the low brightness side will be destroyed.

The classification circuit 20 receives logic outputs from circuits 17, 18, and 19, and n from a third judgment circuit 170, which will be described later.
flag and l from the second blocking circuit 102, which will be described later.
Using flags as input, it is determined to which predetermined category the combinational logic of these logical processes belongs. That is, classify. This predetermined category is 5
The control output corresponding to each category is selectively generated. Circuits 14, 15, 16,
Analog switches 21 and 2 are connected between 110 and 111 and the apex calculation circuit 24, respectively.
2, 23, 112, and 113 select the output corresponding to the classified category from among the first to fifth photometric outputs according to the control output of the classification circuit 20, and transmit the selected output to the apex calculation circuit 24.

The apex calculation circuit 24 generates an output corresponding to an appropriate exposure value (shutter speed and aperture value) based on the selected photometric output and other exposure factors from the information setting section 27, and outputs it using a known exposure control circuit. 25 and the exposure display circuit 26.

The first minimum value detection circuit 99 and the first maximum value detection circuit 100 receive the photoelectric outputs P ₀ to P _o-1 as inputs, and select the minimum value Pminoriginal maximum value from among them.
Detect Pmaxoriginal respectively. The third determination circuit 170 inputs the maximum value Pmaxoriginal from the first maximum value detection circuit 100 and the Pminortiginal from the first minimum value detection circuit 99, and determines whether Pmaxoriginal−Pminoriginal≦γ (where γ is a constant). Of course, this determination circuit 170 is
It includes a circuit that generates a reference output corresponding to the constant γ and a comparison circuit. This determination operation is for determining whether to extract the fourth or fifth photometric output. The output of this circuit is applied to classification circuit 20 as an n flag.

The first blocking circuit 101 receives the photoelectric outputs P ₀ -P _o1 as input and compares them with two threshold levels. The first threshold level Pth ₁ is set to approximately 16 EV, assuming that the daytime sun is present on the screen, and the second threshold level Pth ₂ is set to approximately 16 EV, assuming that the sun is present on the screen at dusk. It is set to be equivalent to 15EV. First, when there is a photoelectric output equal to or higher than the threshold level Pth ₁ , the analog switches 103, 105, and 107 are controlled to prevent the photoelectric output from being transmitted to the circuits 11, 12, and 13. However, when all the photoelectric outputs are equal to or higher than the threshold level Pth ₁ , the analog switches 103, 105, and 107 are controlled so that any one of the photoelectric outputs can be transmitted to the next stage circuit. The reason for this will be explained later. Next, when there is a photoelectric output equal to or higher than the threshold level Pth ₂ , analog switches 103 and 10
5, 107 and its photoelectric output circuit 11,
The transmission to 12 and 13 is blocked, but the number of blocks is kept below a certain number. This is because when photographing at dusk, the sun itself may be the subject of the photograph, and if all that information is blocked, the photographer's intentions may not be reflected.

The second blocking circuit 102 inputs the photoelectric outputs P ₀ to P _o-1 and compares them with a threshold level Pth ₀ corresponding to the lower limit of photometry. If there is a photoelectric output below Pth ₀ , the analog switches 104, 106, and 108 are controlled to prevent the photoelectric output from being transmitted to the circuits 11, 12, and 13. Then, the classification circuit 20 generates an l flag indicating whether the number of inhibitions is above or below a certain value.
to be applied.

The first and second blocking circuits 101 and 102 determine the number of blocked transmissions to the next stage circuit by the average value detection circuit 1.
2, and when calculating the average value, these cells are excluded from the calculation target.

Next, the operation and classification mode of the classification circuit 20 will be described in the case where the screen is divided into three and five parts.
Figures 3a and 3b show the divided state of the screen and the photoelectric output of each divided area.

(1) In Figure 3a, assuming a 6x6 camera, the screen is divided into a central area Da, an upper area Du, and a lower double input Dl, and the photoelectric output of each is represented by P ₀ to P _2. ing.

Each photoelectric output P ₀ ~ _{P 2} is the average value Pmean = (P ₀ + P ₁
+P ₂ )/3, and each region is P ₀ ~ _{P 2} ≧
When Pmean, it is expressed as a logical value of 1, and
When P ₀ to P ₂ <Pmean, it is represented by a logical value of 0. The classification circuit 20 determines that the combination of logical values is
() When the central area Dc is 0, or the lower area Dl
is 0 (at this time, the main subject is likely to be in the area De or Dl), turn on the analog switch 23 and output the third photometry output PL.
is transmitted to the apex calculation circuit 24. ()
When the center area Dc is 1 (at this time, there is a high possibility that the main subject exists in the area Dc), turn on the analog switch 21 and output the first photometric output.
The PH is transmitted to the apex calculation circuit 24.
() When the n flag is 1, that is, Pmaxoriginal
−When Pminoriginal≦γ, the screen is ()
If the state is , the analog switch 113 is turned on to extract the fifth photometric output PLM instead of the third photometric output PL, and if the screen is in the state ( ), the analog switch 113 is turned on to extract the fifth photometric output PLM instead of the third photometric output PL. The analog switch 112 is turned on to extract the fourth photometric output PHM.

This is the maximum value of the photoelectric output when the first or third photometric output is extracted.
This is because when the difference between Pmax and minimum min is small, that is, when the brightness of the subject is relatively uniform, correcting toward the average value often results in a more desirable photograph.

On the other hand, the first determination circuit 18 determines that pa≦Pmax≦
When Pβ, a logical value of 1 is output, and in other cases, a logical value of 0 is generated. Second
The determination circuit 19 generates an output of logical value 1 when a≦ΔP≦β, and generates an output of logical value 0 otherwise. When a logical value of 1 is applied from the first and second judgment circuits 18 and 19, the classification circuit 20 gives priority to the analog switch 22 even if the screen is in the above state () and (). is turned on and the second photometric output PM is transmitted to the apex calculation circuit 24.

(2) In Figure 3b, assuming a Leica camera, the screen has a central area Dc, an upper right area Dru,
Upper left area Dlu, lower right area Drl, lower left area
It is divided into Dll, and the photoelectric output of each is represented by _P0 to _P4 . Each photoelectric output _P0 to _P4 is compared with the average value Pmean in the same way as described above, and each region is represented by a logical value of 1 or 0. The classification circuit 20 determines that this combination is () when the central area Dc is 0, the left and right lower areas Dll, and when Drl is 0, the upper left area Dlu and the lower left area Dll are 0, the upper right area Dru.
When the lower right area Drl is 0, the analog switch 23 is turned on and the third photometry output PL is transmitted to the apex calculation circuit 24 (because the main subject is likely to exist in the 0 area at this time). . ()()() is the same as the operation described in section (1). This five-division example takes into consideration the fact that there are vertical and horizontal photographing positions, such as in a Leica camera.

Now, in the above-mentioned items (1) and (2), if there is a high brightness part above the threshold level Pth ₁ in a certain area of the screen, the photoelectric output of that area, for example P ₁ , is blocked and the average value is
Pmean′=(P ₀ +P ₂ )/2 or Pmean′=(P ₀
+P ₂ +P ₃ +P ₄ )/4. Therefore, using this average value, the circuit 17 and the arithmetic circuits 14, 15, 16
will work. That is, the circuit 17 converts each photoelectric output into a logic output based on this new average value Pmean', and the arithmetic circuits 14, 15, and 16 convert this output into a logic output.
Based on Pmean′, the modified photometric output PH,
Generates PM and PL. This modified photometric output is selectively extracted by the classification circuit 20 in the same manner as described above.

By the way, when the entire screen has high brightness and the brightness is the same, for example when photographing clouds, the maximum value Pmax of photoelectric output is only one circuit 11, 12,
13. Then, the maximum value, average value, and minimum value all match Pmax. At this time, the state of the screen becomes the state () in (1) and (2) above, and the second photometric output PM is selected, but PM=
Since it is Pmax, exposure control is performed for high brightness.

Next, the photoelectric outputs above the threshold level Pth ₂ are blocked from being transmitted to the circuits 11, 12, and 13 within a certain number, and the average value Pmean also decreases to a certain average value Pmean'' according to the number of blocks. This average value
It operates in the same way as the previous stage based on Pmean''.

As described above, correction for the presence of a high brightness area is performed when generating a photometric output.

On the other hand, if there is a photoelectric output below the threshold level Pth ₂ , this _{photoelectric} output, e.g.
Since the transmission to 12 and 13 is blocked, the absolute level of the average value increases and becomes Pmean=(P ₀ +P ₂ )/2 or Pmean=(P ₀ +P ₂ +P ₃ +P ₄ )/4. Therefore, the new first to fifth photometric outputs PH, PM, PL, ignoring the photoelectric output below the photometric lower limit,
PHM and PLM are obtained. This photometric output is selected by the classification circuit 20 in the same manner as described above. In this way, correction is performed when a low brightness portion exists within the screen.

The configuration of each block will be explained below.

FIG. 4 shows an example of a photoelectric element, in which a plurality of photoelectric elements are lined up, and can be constructed from a photo diode array, CCD, or the like. However, it is not necessarily necessary to form a matrix. By combining the outputs of the photoelectric elements, the photoelectric output in the above-mentioned divided regions is obtained.

FIG. 5 shows an example of a light receiving optical system. 31 is the fourth
A plurality of photoelectric elements shown in the figure include a photographing lens 32, a mirror 33, a film surface 34, and a film surface 35.
36 is a finder screen, and 36 is a lens for re-imaging the subject image formed on the finder screen on the light receiving element surface.

With the above configuration, the brightness of each part of the scene to be photographed can be measured, and a plurality of independent photometric information can be extracted.

FIG. 6a shows a circuit example of the maximum value detection circuits 11 and 100, and FIG. 6b shows a circuit example of the minimum value detection circuit 13. These circuits are known per se, using OP amplifiers and ideal diodes.

FIG. 7 shows an average value detection circuit 12 configured with resistors r, r/n and an OP amplifier _A1 , and the output of the OP amplifier is (P ₀ +P ₁ ...P _o1 )/n=Pmean
The following output is obtained.

FIG. 8 is a circuit example of the arithmetic circuits 14, 15, 16, with followers A ₁₀ to A ₁₂ and voltage dividing resistors R ₁ to
_R4 , the first to fifth photometric outputs PH,
PM, PL, PHM, and PLM can be obtained to satisfy equations (1), (2), and (3) by adjusting the partial pressure ratio.

FIG. 9 shows a circuit example of the first blocking circuit, in which the aforementioned number of blocking circuits is set to two. In the same figure, comparator C100, AND gate AND100, AND
101, flip-flops FF10 and FF11, a diode D100, a resistor R100, and an analog switch AS100. Circuit blocks are prepared corresponding to the number of photoelectric outputs. Here, five blocks are prepared corresponding to the photoelectric outputs _P0 to _P4 , and block _B1 is shown as a representative. however,
AND gates AND99 and AND97 and flip-flops FF12 and FF13 are dedicated to block _B1 .

Now, a clock pulse of a constant period is applied to the ring counter RC, and the output terminals q ₀ , q ₁ , q ₃ , q ₅ ,
Outputs are generated sequentially at q ₇ , q ₉ , and q ₁₀ according to the number of clock pulses. They are provided every other bit between terminals q ₁ -q ₉ , and a time lag of 1 bit is provided between each output. Binary counter BC1 uses the q ₀ output of ring counter RC as input, and the Q output and
The q ₀ output is ANDed by an AND 118, and a pulse of the q ₀ output is generated every two cycles. When the Q output is 1, the output is 0 and the transistor Tr
is turned off, and a voltage corresponding to the above threshold level Pth ₁ is applied to the inverting input terminal of the comparator of each block. Further, when the Q output is 0, the output becomes 1, the transistor Tr is turned on, and a voltage corresponding to the above-mentioned threshold level Pth ₂ is applied to the inverting input terminal of the comparator of each block. These comparators output 1 when PN>Pth (where PN is each photoelectric output and Pth is Pth ₁ or Pth ₂ ).
Next, the operation will be described.

When the Q output of the binary counter BC1 is 1; this is the mode in which PN>Pth ₁ is detected. Since the output of the OR gate OR110 is 1, the AND gate AND100 of the block _B1 flip-flops the output of the comparator C100 when receiving the _q1 output of the ring counter RC.
Apply to S input of FF10. Here, P ₀ >
If Vth is ₁ , the comparator C100 outputs 1, so the flip-flop FF10 outputs 1 to the Q output. flip flop at the same time
FF11 outputs 1 to the Q output, turns off analog switch AS100 (switch AS100 and switches AS101 to AS104 (not shown) correspond to analog switch 103 in FIG. 2), and switches _P0 to the next stage. Not transmitted to the circuit. This operation is time-divided by the q ₁ to _{q 9} outputs of the ring counter RC and sequentially moves toward the block that receives the photoelectric output P ₄ as an input. the result,
From the block inputting the photoelectric output of PN>Pth ₁ , the photoelectric output is sent to the next circuit, namely the second maximum value detection circuit 11 and the average value detection circuit 1 mentioned above.
2. It is not transmitted to the second minimum value detection circuit 13. On the other hand, the a ₀ output of the AND gate AND100 is input to the AND gate AND110 which inputs the q ₁ output of the ring counter RC, and when both the a ₀ output and the q ₁ output are 1, the AND gate
AND110 outputs 1, or gate OR11
1 to the binary counter BC2. Similarly, the a ₁ , a ₂ , a ₃ , and a ₄ outputs of the AND gates of each block are synchronized with the q ₃ , q ₅ , q ₇ , and q ₉ outputs, respectively, to the binary counter BC2.
is input. Therefore the binary counter BC
2 counts 1 of the a ₀ to a ₄ outputs.

However, the Q of binary counter BC1
Since the output is 1, the output of the OR gate OR110 is 1 regardless of the count value of the counter BC2. Therefore, when p ₀ to p ₄ > Pth ₁ , all photoelectric outputs are blocked from being transmitted to the next stage circuit, but when the count value of binary counter BC2 is 5, that is, "101" in binary code, Sometimes the Q ₁₀ output of binary counter BC2
_Q12 output becomes 1, and gate AND98
outputs 1, 1 enters the set input of flip-flop _FF2 , output Q becomes 1, 1 enters the set input of flip-flop FF13, output Q becomes 1, and Q becomes 0. (The reset timing relationship is the same as FF10 and FF11.) Therefore, the output of the AND gate AND99 is set to 0, and the analog switch AS100 is turned on. As a result, the photoelectric output P ₀ is transmitted to the next stage circuit. Here, if the anode terminal of the diode D100 is made higher than the Pth ₂ equivalent voltage by the amount lowered by the diode using the variable resistor R100, the photoelectric output P ₀ is limited to the Pth ₂ equivalent voltage. This is based on the consideration that when the entire screen is bright, overexposure can produce more realistic photographs.
When the count value of the binary counter BC2 is 5 or less, the output of the NOR gate NOR100 is 1, and the AND gate AND99 transmits the Q output of the flip-flop FF12 to its analog switch AS100.

Further, when the count value of the binary counter BC2 becomes 2 or more, the output of _{Q11, Q12} , or the output of the AND gate AND115 becomes 1, and at this time, the NOR gate NOR100 outputs 0. Then, the AND gate AND116 resets the binary counter BC1 when the _q10 output of the ring counter RC becomes 1, so when the _q1 output becomes 1 again, the Q output becomes 1, and as a result, PN>Pth It does not shift to the mode that detects ₂ .

When the Q output of the binary counter BC1 is 0; in this case, the mode is to detect PN>Pth ₂ . When the output of the NOR gate NOR100 is 1, the output of the OR gate OR110 is 1. That is, when the count value of the binary counter BC2 is 2 or less, that is, when the Q ₁₀ output is 1 or the Q ₁₁ output is 1.

Now, if the count value of counter BC2 is 0,
Noah Gate NOR100, Or Gate OR110
Since outputs 1, the comparators of each block compare the threshold level Pth ₂ and the photoelectric outputs P ₀ to _{P 4} respectively. Then, when there is a photoelectric output of Pth ₂ or more, for example, when P ₀ , P ₁ , P ₂ > Pth ₂ ,
a ₀ , a ₁ , a ₂ output becomes 1. and q ₁ , q ₃ , q ₅
Each AND gate AND11 by applying the output
0 to AND112 outputs 1, which is counted by counter BC2. Therefore, the outputs of Q ₁₀ and Q ₁₁ are 1, so the AND gate AND115 outputs 1, and the NOR gate NOR100 and the OR gate OR
110 outputs 0. As a result, if two or more photoelectric outputs are blocked, no more will be blocked. In other words, blocks that operate successively in chronological order do not perform blocking operations. Note that due to restrictions on the blocking operation, there is a possibility that photoelectric output of Pth ₂ or more will be transmitted to the next stage circuit, but this is due to the diode D.
100 to D104 and the resistors R100 to R104, the voltage is limited to the voltage equivalent to Pth ₂ , so there is no problem.

Furthermore, the AND gates AND117 and AND118
generates a reset pulse for flip-flops FF10 and FF11, and adjusts the reset timing of FF10 and FF11 so that AND118 generates output 1 after AND117 generates output 1.

FIG. 10 shows a circuit example of the second blocking circuit, in which the number of blocking circuits is set to the constant number of blocking circuits 3 described above. In the same figure; the voltage corresponding to the threshold level Pth ₀ is the resistance R20
0 and comparators C200-C
204 is applied to the in-phase input terminal. The photoelectric outputs _P0 to _P4 are applied to the inverting input terminals of the comparators C200 to C204, and each comparator has PN
<Pth ₀ (However, PN is any P ₀ to P ₄ ), output 1 is generated. Analog switches AS200 to AS provided corresponding to each comparator
Reference numeral 204 blocks the transmission of the photoelectric output to the next stage circuit with the output 1 of the corresponding comparator. Analog switches AS200 to AS204 each have analog switches AS10 for each block described in FIG.
0 to AS104 (AS101 to AS104 are omitted in FIG. 9) are connected in series. Analog switch block B ₁₀ ,
B ₁₁ corresponds to circuits 103, 105, 107 and circuits 104, 106, 108 in FIG. 2, respectively.

Ring counter RC200 sequentially generates q ₀ , q ₁ , q ₃ , q ₅ , q ₉ , and q ₁₀ outputs by applying a clock pulse. The outputs q ₁ to _{q 9} are output with a time lag of one bit of the counter. Now, when the _q0 output of the ring counter RC200 becomes 1, the binary counter BC3 is reset. When the q ₁ output becomes 1, the gate of the AND gate AND200 opens and the output of the comparator C200 becomes an OR gate.
Transmit to OR200. At this time, comparator C
If the output is 1 of 200 (P ₀ <Pth ₀ ), the binary counter BC3 counts this output 1. below,
As the outputs of q ₁ to q ₀ of the ring counter RC200 sequentially become 1, a similar operation is performed as an AND gate.
Transition to AND201~AND204, photoelectric output
If there is one among P ₁ to P ₄ that satisfies PN<Pth ₀ , the binary counter BC3 advances the count by that number. When the count value of the binary counter BC3 becomes 3, both the _Q20 output and the _Q21 output become 1, the output of the AND gate AND205 becomes 1, and the output 1 of the OR gate OR201 causes the Q output of the flip-flop FF20, that is, the l flag. becomes 1. Similarly, the l flag is 1 when the count value of the binary counter BC3 is 4 or 5.

When the operation progresses and the _q10 output of ring counter RC200 becomes 1, when the count value of binary counter BC3 is 3 or more, inverter INV20
AND gate with output 0 applied from 0
Since the output of AND206 is 0, flip-flop FF20 is not reset, and the l flag maintains 1. Then, in the next cycle, if the number of inhibitions is 2 or less, the output of the inverter INV200 is 1, so the l flag becomes 0.

In addition, Q ₂₀ output of binary counter BC3, Q ₂₂
When both outputs are 1, the number of blocks is 5, and the entire screen is below the lower limit of photometry. Therefore, if this is detected by the AND gate AND207, it is possible to indicate that photography is not possible by lighting up the light emitting diode LED.

FIG. 11 shows an example of the average value detection circuit.
In the same figure; since the blocking operation by the first blocking circuit (high brightness side) and the blocking operation by the second blocking circuit (low brightness side) cannot occur at the same time in normal photographing conditions, the addition circuit 40 is an OR gate. Configured.

Each field effect transistor FET conducts when its gate is 1.

When the blocking number is 0, all gates are 1 and all FETs are conductive, so the composite feedback resistance R is r/5 1/R=2/r+2/r+1/r=5/r, R=r
/5 That is, (P ₀ /r+P ₁ /r+...+P ₄ /r)·r/5=Pall/5=Pmean where Pall is the sum of the unblocked photoelectric outputs.

When the blocking number is 1, FETO becomes non-conductive, R=1/2/r+2/r=r/4, Pall/4=Pmea
n When the number of blocking is 2, FET1 becomes non-conductive, R=1/2/r+1/r=r/3, Pall/3=Pmea
n When the number of blocking is 3, FET0 and 1 become non-conductive, R=-1/2/r=r/2, Pall/2=Pmean When the number of blocking is 4, FET1 and 2 become non-conductive, R=1/1/r=r, Pall=Pmean FIG. 12 is a circuit diagram of the classification circuit 20. This figure shows an example in which the screen is divided into five parts as shown in Fig. 3b.

The in-phase input terminal of comparator C1 has a constant Pa.
An input corresponding to the constant Pβ is applied to the inverting input terminal of the comparator C2. On the other hand, an input corresponding to the constant a is applied to the in-phase input terminal of the comparator C3, and an input corresponding to the constant β is applied to the inverting input terminal of the comparator C4. Comparator C5
An input corresponding to the constant γ is applied to the in-phase input terminal of . The inverting input terminals of comparators C7 to C11, which use the photoelectric outputs _P0 to _P4 as in-phase inputs,
A reference input equivalent to Pmean−δL is applied.
This level reduction corresponding to δL is intended to more reliably perform the binary change on the low luminance side of the photoelectric outputs P ₀ to _{P 4} . A reference input equivalent to Pmean+δH is applied to the inverting input of the comparator C6, which uses the photoelectric output P ₀ as the in-phase input. This level increase corresponding to δH is to ensure more reliable binarization on the high brightness side of the photoelectric output _P0 .

The long maximum value Pmax is input to the inverting input terminal of the comparator C1 and the in-phase input terminal of the comparator C2. The luminance difference ΔP is input to the reaction input terminal of the comparator C3 and the in-phase input terminal of the comparator C4. The outputs of the comparators C1 to C4 are input to the AND gate AND1. When the output of the AND gate AND1 becomes 1, the outputs of the comparators C1 to C4 all indicate 1, and Pα≦Pmax≦Pβ ...(7)(a) and α≦ΔP≦β ...(7)( b) is true. The output of the AND gate AND1 is set as the M flag. When the M flag is 1, the output of OR gate OR1 becomes 1, and analog switch 2
2 is turned on to select the second photometric output PM. This is because equation (7)(b) holds, which indicates that there is a certain degree of brightness difference, but if equation (7)(a) holds, that is, the maximum value falls within a certain range. This is because when the subject is exposed to light, there is no backlight and the appropriate exposure level is around the average value. Note that this holds true even if the photoelectric output on the high-brightness side or the low-brightness side is blocked. The photoelectric output P ₀ is input to the in-phase input terminals of comparators C6 and C7, and the photoelectric outputs P ₁ , P ₂ , P ₃ and P ₄ are input to the comparators C8 and C7.
9, C10 and C11 in-phase input terminals. Further, an output Pmean+δH is inputted to the inverting input terminal of the comparator C6, which increases the average value to a constant level. The output of the comparator C6 becomes 1 when the photoelectric output _P0 of the central region Dc is higher than the average value Pmean by a discernible amount (by δH), indicating that the central part of the photographic screen is a bright part. There is. On the other hand, the inverting input terminals of the comparators C7 to C11 are outputted by lowering the average value by a certain value, Pmean-.
δL is input. Comparators C7 to C11
When the output of 0 becomes 0, the photoelectric outputs P ₀ to P ₄ are lower than the average value Pmean to a discernible extent (by δL), and the screen corresponding to the photoelectric outputs P ₀ to _{P 4} has become a dark area. It shows.

Note that, as is clear from the comparators C ₆ and C ₇ , P ₀ is normalized by binarizing each of the two reference levels near the average value.

Comparator C6 for AND gate AND2,
C9, C10 output and M flag inverter
The output inverted by INV1 is input. The output of the AND gate AND2 becomes 1 because P ₀ > Pmean + δH (The central area Dc is a bright area) P ₂ ≧Pmean-δL P ₄ ≧Pmean-δL (The lower half areas Drl and Dll are not dark areas)... ...(8) holds true and the M flag is 0. In such a state, the central region Dc is bright and the upper half region is bright.
When Dru and Dlu are dark, it is like a spot light.

Therefore, equation (8) becomes the condition for determining that the main subject is in the bright area. The output of the AND gate AND2 is set as the H flag. When the H flag is 1, the analog switch 21 is turned on and the first photometric output PH is selected.

The output of C7 goes into inverter INV3. Now, if P ₀ <Pmean-δL (9) (the central area Dc is a dark area) holds true, the output of the comparator C1 is 0 and the output of the inverter INV3 is 1.

Also, the outputs of comparators C8 and C9 enter the NOR gate NOR1.

If P ₁ <Pmean−δL P ₂ <Pmean−δL ……(10) (left half areas Dlu and Dll are dark areas), the outputs of comparators C8 and C9 are both 0 and the output of NOR gate NOR1 is 1. Become.
Similarly, P ₂ <Pmean−δL P ₄ <Pmean−δL …(11) (lower half regions Drl and Dll are dark areas) and P ₃ <Pmean−δL P ₄ <Pmean−δL …(12) ( If the right half areas Dru and Drl are dark areas), then Noah Gate NOR2 and
The output of NOR3 becomes 1. The outputs of the inverter INV3 and the NOR gates NOR1 to NOR3 are input to the OR gate OR3, and if any output is 1, the output of the OR gate OR3 becomes 1. In other words, if any of equations (9) to (12) hold, the OR gate
This means that the output of OR3 will be 1. If formula (9) holds true, this means that the center of the image plane, where there is a high probability that the main subject is located, is a dark area, and it is better to set the exposure to the low brightness side. However, even if the center of the screen is bright, it is often due to the brightness of the background, and it cannot necessarily be determined that the main subject is in the bright area. In fact, in backlit situations, the brightness of the main subject will be close to the brightness of the lower part of the screen.
Therefore, if equation (11) holds true, it is better to determine that the main subject is in a dark area and select the third photometric output PL. If equations (10) and (12) hold true, it is considered that the image was taken with the camera held in a vertical position. As described above, each of equations (9) to (12) becomes a condition for determining that the main subject is in a dark area. At this time, the output of OR gate OR3 becomes 1.

If there is a certain number of photoelectric outputs below the photometric lower limit,
The flag becomes 1. Then, the output of the OR gate OR2 becomes 1 and the first photometric output PH is selected. This is because when there are many photoelectric outputs that are below the photometric lower limit, there is a high probability that photometry is possible due to the brightness of a part of the photoelectric element, and it is better to select the high brightness side.

ΔP, that is, Pmaxoriginal−Pminoriginal is input to the inverting input terminal of comparator C5, and when ΔP<γ (13) (where γ is a constant) holds, the output of comparator C5 becomes 1. This is a case where the measured luminance difference is relatively small, and correcting it toward the average value will bring the exposure closer to the correct exposure.

The output of comparator C5 is inverter INV2
is reversed. The output of the inverter INV2 and the H flag are input to the AND gate AND3. The output of the AND gate AND3 becomes 1 when equation (13) does not hold and the H flag is 1. That is, when the high brightness side is selected and the brightness difference is large, the output of the OR gate OR2 becomes 1 and the first photometric output PH is selected.

The l flag is input to the inverter INV4 and inverted, and the inverter INV4, the output of the comparator C5, and the H flag are input to the AND gate AND4. The output of the AND gate AND4 becomes 1 because formula (13) holds true, and the H flag is 1 and the L flag is 0.
It's time. That is, when the high brightness side is selected and the brightness difference is small, the fourth photometric output PHM, for example, when w ₁ =w ₂ =0.5, (PH+PM)/2 is selected.

The outputs of the OR gate OR3 and the inverters INV1 and INV4 are input to the AND gate AND7. The output of the AND gate AND7 becomes 1 because l,
This is when the M flag is 0 and the output of the OR gate OR3 is 1. That is, this is a case where the low luminance side is selected. Now, let the output of the AND gate AND7 be the L flag.

The L flag and the output of the comparator C5 are input to the AND gate AND5, and the low luminance side is selected.
When the brightness difference is small, the output is 1, and when the fifth photometric output PLM, for example, w ₃ =w ₄ =0.5, (PM+PL)/2 is selected.

The L flag and the output of the inverter INV2 are input to the AND gate AND6, and the low brightness side is selected.
When the brightness difference is large, the output becomes 1 and the third photometric output PL is selected.

The M, L, and l flags are input to the NAND gate, and become 1 when all of them are 0. it is,
This is a case where it is not determined whether the main subject is in a bright area or a dark area. At this time, the or gate
The output of OR1 becomes 1, and the second photometric output PM is selected.

In the embodiment, element 10 in FIG. 2 is a photometric circuit;
13 is an output circuit, elements 101, 103, 10
5 and 107 respectively constitute selection means.

As described in detail above, the present invention divides the field into a plurality of regions and performs photometry, and among the photometry outputs corresponding to the plurality of regions, those exceeding a threshold value (Pth ₂ in the example) are used to determine the appropriate exposure. Since it is not involved in the output means that obtains the signal, it is possible that sunlight etc. will be reflected in the photo and the photo will be underexposed based on the extremely high brightness metering output, or conversely, the photo will be extremely exposed such as a night view. It can prevent you from going overboard. On the other hand, for example, if too many photometric outputs that exceed the threshold on the high-brightness side are ignored, appropriate exposure will be determined using only a small amount of photometric output that is below the threshold, and contrary to the case described above, there is a risk of overexposure. However, in the present invention, when the number of photometric outputs exceeding a threshold value exceeds a predetermined number, the photometric outputs exceeding the predetermined number are made to be involved in the output means for obtaining a signal regarding proper exposure, thereby increasing the probability of correct exposure. You can get it at

[Brief explanation of drawings]

Figure 1 is a diagram showing the brightness distribution of the field (screen).
FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG.
The figure shows how the screen is divided, Figure 4 shows an example of a photoelectric element array, Figure 5 shows an example of a light receiving optical system, and Figure 6 shows an example of a maximum value and minimum value detection circuit. 7 is a diagram showing an example of an average value detection circuit,
Fig. 8 is a diagram showing an example of an arithmetic circuit, Fig. 9 is a diagram showing an example of the first blocking circuit, Fig. 10 is a diagram showing an example of the second blocking circuit, and Fig. 11 is a diagram showing an example of the second blocking circuit. FIG. 12 is a diagram showing an example of a circuit, and FIG. 12 is a diagram showing an example of a classification circuit. [Explanation of symbols of main parts], 10...photometering circuit,
11-16... Appropriate photometry output generation circuit, 17...
Standardization circuit, 18, 19, 170...determination circuit,
20...Extraction circuit.

Claims (1)

[Scope of Claims] 1. A photometry circuit that measures light by dividing a field into a plurality of areas and generates a plurality of photometry outputs corresponding to the plurality of photometry areas, and a system that determines appropriate exposure based on the plurality of photometry outputs. In a multi-photometering device equipped with an output circuit that generates an output, the photometric output is compared with a threshold value, and photometric outputs exceeding the threshold value are not involved in the output circuit, while the photometric outputs to be uninvolved exceed a predetermined number. 1. A multi-photometering device characterized by comprising a selection means for causing the output circuit to take part in the photometry output exceeding the predetermined number when the number exceeds the predetermined number. 2. The multi-photometering circuit according to claim 1, wherein the selection means converts the photometry outputs exceeding the predetermined number into a predetermined value and transmits the converted value to the output circuit.