JPS63134923A - Photometric device - Google Patents

Abstract

PURPOSE:To calculate a correct photometric value as the whole field, by deriving a difference of luminance information of the center part of the field and luminance information of the peripheral part of the field, and correcting a photometric value in accordance with this difference. CONSTITUTION:A field is divided into center areas 2A, 2B, and a peripheral area 2C, and luminance information VA, VB and VC of each area is derived by photodetectors 8-10. A selecting circuit 14 derives a difference between the center area luminances VA, VB and the peripheral area luminance VC, and outputs a corrected value V2 corresponding to this difference. Also, center luminance arithmetic means 15, 16 calculate luminance information V1 of the center are from said luminance information VA, VB. A field luminance arithmetic means 22 subtracts said luminance correcting information V2 from said center are luminance information V1, and outputs a corrected photometric device V1-V2.

Description

[Detailed Description of the Invention] [Industrial Applicability Meter] The present invention is a method of dividing a subject into a plurality of regions, obtaining luminance information for each of the plurality of regions, and obtaining a photometric value by various calculations. The present invention relates to a photometric device.

[Prior art]

2. Description of the Related Art Conventionally, various photometry devices have been proposed that divide a field into a plurality of regions, measure light for each region, and use these plurality of photometry values to give an appropriate exposure to a photographic screen.

For example, Japanese Utility Model Publication No. 51-9271 proposes a photometry device that uses the arithmetic average value of the maximum value and the minimum value among the outputs from a plurality of charging elements to obtain an appropriate photometry value. However, with this metering device, if the background is particularly bright or dark, the subject may be underexposed or
Otherwise, there was a problem of overexposure.

(Objective of the Invention) The present invention is a suitable photometering device that assumes that the main subject is in the center of the field, and in particular, calculates appropriate photometering values based on luminance information in the center area of the screen. The purpose of the present invention is to provide a photometric device that makes it possible to

In order to achieve the above object, the present invention divides a field into at least a central region and a peripheral region, obtains luminance information, determines Xi degree difference information between the central region luminance and peripheral region luminance, and obtains the luminance difference information. The present invention is characterized by a photometric device that corrects the center area brightness information using a correction value based on the brightness information of the entire object field.

〔Example〕

FIG. 1 is a schematic diagram of an optical system when the present invention is applied to a single-lens reflex camera. In the figure, 1 is a tit lens;
2 is a quick return mirror, 3 is a focus plate, 4 is a pentaprism, 5 is an imaging lens, 6 is a light receiving section, and 7 is an image plane. In this embodiment, a subject image formed on a focusing plate 3 by a photographing lens 1 is guided and imaged onto a light receiving section 6 by an imaging lens 5, and photometry is performed.

FIG. 2 is an explanatory diagram of the light-receiving surface of the light-receiving section 6 shown in FIG. 1. In FIG. 2, 2A and 2B are central areas at the center of the field, and 2c are peripheral areas at the periphery of the field.

In this embodiment, as shown in FIG. 2, a plurality of light-receiving elements that can receive light from the field area at positions corresponding to each area are arranged,
The field of view is divided into three regions 2A, 2B, and 2C, and field brightness is photometered for each region.

FIG. 3, FIG. 4, and FIG. 5 are circuit diagrams for explaining the circuit configuration of this embodiment.

In FIG. 3, 8, 9, and 10 are silicon photodiodes (SPD) corresponding to the three regions 2A, 2B, and 2C in FIG. 2, respectively, and the photocurrent iA corresponds to the brightness of each region. , iB, 1. to occur. +1.12.13
is a logarithmic compression circuit that logarithmically compresses these photocurrents and outputs voltage values V, , V, , VC. Voltage VA, V
a, Vc is constant al+2+83 (≧O), b
(>O) and photocurrents IA, 1B, t(), it can be expressed as follows.

V, =a, +b-ILn iA V,=a2+b−j! ni.

Vc: B3+b-j2nic However, it is assumed that al+2+a3 is set in advance in the logarithmic compression circuits 11, 12, and 13 so that VA=V,=VC when the brightness of each area is equal. 14 is a logarithmic compression circuit 11°12.1. M) Output voltage V
A, V8. V, , respectively at the input terminal Ill+ 112+
I13 is a selection circuit that determines which arithmetic circuit to select from among correction value arithmetic circuits corresponding to a plurality of arithmetic expressions or a plurality of correction constants, which will be described later. 15
．． 16 is a resistor having the same resistance value, and constitutes an average value circuit as a central luminance calculation circuit. The output voltage (1) of the central brightness calculation circuit is (VA+VB)/2. Reference numeral 17 denotes an operational amplifier, which is used as a voltage follower by connecting its output end and negative phase input end, and the output voltage v1 of the central brightness calculation circuit is input to the positive phase input end. The output terminal voltage of the operational amplifier 17 is the voltage vI regardless of the circuit state after the output terminal. 18°19.20.
21 is a resistor having the same resistance value, and 22 is an operational amplifier.

The resistors 18.19, 20.21 and the operational amplifier 22 constitute a subtraction circuit, which serves as a photometric value calculation circuit. If the voltage output from the 01 output terminal of the selection circuit 14 is V2, the output voltages of this photometric value calculation circuit are V, -V2.

In this embodiment, these voltages V and -V2 represent photometric values that will be described later.

FIG. 4 is a circuit diagram of the selection circuit 14 in FIG. 3.

In FIG. 4, 23, 24, 25, and 26 are resistors having the same resistance value, and 27 is an operational amplifier, which constitutes a first subtraction circuit. Similarly, 28, 29 and 30, 31 are resistors having the same resistance value, and 32 is an operational amplifier, which constitutes a second subtraction circuit. The first subtraction circuit has a voltage ■.

and voltage V, are input, and the output voltage is V.

-■8. The second subtraction circuit has voltage ■8 and voltage V.
C is manually powered and its output voltage ■.

-Va. 33 is a reference voltage generation circuit which generates a reference voltage Vr.
It is generating l.

34 is a comparator, the voltage VC is input to the positive phase input terminal, the reference voltage Vrl is input to the negative phase input terminal, and ■
. When ≧Vrl, an H level voltage is output, and VekuV
When rl, an L level voltage is output. In the embodiment, the reference voltage ■r1 is set at a level that allows it to be determined whether the object is outdoors or indoors. 35 is a reference voltage generation circuit which generates the reference voltage ■P! + vPI++ V
Oa+VQb'l'' occurs.

The reference voltage generation circuit 35 has a control terminal B/U, to which the output voltage of the comparator 34 is input as a control voltage. The reference voltage when the H level control voltage or human input is applied to the control terminal B/U.
pa: vPl+ vPb=V P2. VQa=
V Ql, V Qb= V Q2. On the other hand, an L-level control voltage is manually applied to terminal B/U, and Tatoki (7) reference voltage 'a: V - = V P31 V pb = V
p4゜■Qa ” VO3* vQb ” ” 04
far. Reference voltage VPI~V P41 V Ql~V
The code of 04 is VPI, vP3+V Ql+V 0
3 is positive, vP2+ VF4. "Q2+vQ4 is negative.The relationship between this reference voltage is V,2<O<
VPl, VO2<O<VQI,VF6<O<V
F6, ■. 4<O<V Q3. 36.37 is a comparator, 38.39 is an inverter, and 40 is an AND gate. The positive phase input terminals of the comparators 36 and 37 are connected to the operational amplifiers 27 and 27 of the first subtraction circuit. The output voltage V,
-VA will be done manually. The negative phase input terminal of the comparator 36 is connected to the control terminal B/D of the base J$ voltage generation circuit 35.
The reference voltage VPL or VF6 is manually inputted according to the H level and L level of the controller Jl/'E voltage inputted to the IH. Similarly, the reference voltage VF6 or VF6 is input to the negative phase input terminal of the comparator 37. 41.42 is a comparator, 43.44 is an inverter, and 45 is an AND gate. The output voltage vc-V of the operational amplifier 32 of the second subtraction circuit is connected to the positive phase input terminals of the comparators 41 and 42.
a is input. At the negative phase input terminal of the comparator 41,
The reference voltage VQI or ■ depends on the H level or L level of the control voltage input to the control terminal B/U of the reference voltage generation circuit 35. 3 is input. Similarly, the reference voltage ■ is applied to the negative phase input terminal of the comparator 42. 2 or ■. 4 is input. The output terminals of the comparators 36, 37, 41 and 42 have an H level voltage when V+≧V-, depending on the magnitude of the positive phase input terminal voltage V+ and the negative phase input terminal voltage V-.
When V+<V-, an L level voltage is output.

The input terminal of the AND gate 40 is connected to the output terminal of the inverter 38 and the output terminal of the comparator 37.
A and the two output voltages VPa and V of the reference voltage generation circuit 35
A comparison is made of the size of Pb. When Va-VA≧■, the output voltage of the comparator 36 becomes H level, and the output voltage of the AND gate 40 and inverter 39 becomes L level. When VPb≦VB-vA<VPa, the output voltage of the AND gate 40 becomes H level, and the comparator 3
The output voltages of 6 and inverter 39 become L level. and V, -VA.

<V p b, the output voltage of the inverter 39 is H
level, comparator 36 and AND gate 40
The output voltage becomes L level. Similarly, the input terminal of the AND gate 45 is connected to the output terminal of the inverter 43 and the output terminal of the comparator 42, and is connected to the output terminal of the comparator 41.
, 42, the inverter 43, 44 and the AND gate 45 compare the output voltage VC-V of the operational amplifier 32 and the two output voltages V(,a, vQb) of the reference voltage generation circuit 35.Vc-Va≧ When VQa, the output voltage of the comparator 41 becomes H level, and the output voltage of AND gate 45 and inverter 44 becomes L level.When VOb≦vc-vI, <vQ, the output voltage of AND gate 45 becomes H level. Therefore, the output voltage of the comparator 41 and the inverter 44 becomes L level.Then, VC-V.

<Vob, the output voltage of the inverter 44 becomes H level, and the output voltages of the comparator 41 and AND gate 45 become L level. 46 to 54 are AND gates, a comparator 36, an AND gate 40. How to combine the H level and L level of the output terminal of the inverter 39,
Comparator 41. ANDGATE 45. Inverter 44
In other words, the magnitude relationship between the output voltages V and -V of the operational amplifier 27 and the two output voltages VPa+vpb of the reference voltage generation circuit 35, and the output voltage vc- of the operational amplifier 32 are determined by the combination of the H level and L level at the output end of the ■, and the two output voltages V Q a + V of the reference voltage generation circuit 35
9 of 46 to 54 depending on the combination of size relationship of Ob
One of the AND gates outputs an H level, and the other AND gates output an L level.

55 is a gate circuit, which is an AND gate.

It is composed of a combination of OR gates, etc. This gate circuit 55 is supplied with the outputs of the AND gates 46 to 54 described above, and output signals 55a to 55 for control, which will be described later.
Outputs 55i.

56.57 and 58.59 are resistors with the same resistance value, 6
0 is an operational amplifier and constitutes the third subtraction circuit. A voltage V is applied to the third subtraction circuit.

and ■. is input, and its output voltages are V, -V.

It is. 61.62 are resistors with the same resistance value,
It constitutes a division circuit. Resistance 56° 57.5B, 59
, the operational amplifier 60 and the resistors 61 and 62, the two arithmetic expressions v, -v,.

It constitutes an arithmetic circuit corresponding to (Va-Vc)/2. 80, 90 are operational amplifiers, 81 to 83, and 91 to 93 are resistors having the same resistance value, forming an inverting amplifier circuit. The output of the third subtraction circuit is supplied to the negative phase input terminal of the operational amplifier 80, and therefore the output of the operational amplifier 80 is a voltage (Va vc). Also, operational amplifier 90
The output of the divider circuit is supplied to the negative phase input terminal of the operational amplifier 90, so the output of the operational amplifier 90 becomes the voltage -(v8VC)/2.

63 is a reference voltage generation circuit, which generates reference voltages Vr2 to Vr.
Generates 5. Note that this reference voltage is Vr2゜V r3>
O, -V-4, -Vrs<0, and furthermore, V
r2>V-3,l V-41>1-vrsl is set. 64 to 72 are analog switches, and the input terminal of the analog switch 64 has a voltage ■.

-Vc is the voltage (v
e VC)/2, the reference voltage Vr2 is at the input end of the analog switch 66, the reference voltage Vr3 is at the input end of the analog switch 67, the reference voltage -Vr4 is at the input end of the analog switch 68, and the reference voltage Vr4 is at the input end of the analog switch 69. The input terminal of the analog switch 71 receives the reference voltage -Vr5, the input terminal of the analog switch 71 receives the voltage -(Va Vc), and the input terminal of the analog switch 71 receives the reference voltage -Vr5.
A voltage -(va vc)/2 is applied to the input terminal of 2. Also, the input terminal voltage of the analog switch 70 is Ov
It is. The output terminals of the analog switches 64 to 72 are connected to each other and output the θ1 output terminal, that is, the ■2 voltage.

Further, the output signal 55a of the gate circuit 55 described above is supplied to the control terminal of the analog switch 64, and when this output signal 55a is at H level, the analog switch 64
Similarly, 55b is connected to the control terminal 65, 55c is connected to the control terminal 66, and 55c is connected to the control terminal 67. 55d, 55e to the control terminal 68, 55f to the control terminal 69, 55g to the control terminal 70, 71
55h is supplied to the control terminal of , and 55i is supplied to the control terminal of 72. As shown above,
Resistor 56, 57, 58, 59, operational amplifier 60, resistor 6
1, 62, a reference voltage generation circuit 63 and analog switches 64 to 72 constitute a plurality of correction value calculation circuits corresponding to a plurality of calculation formulas and a plurality of correction constants, and the vA
, VB, and Vc constitute a selection circuit that selects the output voltage by controlling the output signal of the gate circuit 55.

Incidentally, FIG. 5 shows an example of a combination of AND gates, OR gates, etc. configured in the gate circuit 55 described above. In Fig. 5, θR1 to θR7 are OR gates, ANDI
~ANDIO is the 7-channel F-gate, and INI is the inverter. The gate circuit 55 in FIG. 4 outputs output signals 55a to 55a to 55a to 55a in response to the output signals of the AND gates 46 to 54 and the output signal of the comparator 34, as described below.
55i, various configurations can be considered for assembling each gate, and FIG. 5 shows an example of the configuration.

Next, FIG. 3 while referring to FIGS. 6 to 8.

The operation of the circuits shown in FIGS. 4 and 5 will be explained. In FIG. 3, the output voltage Vl of the central luminance calculation circuit is always the voltage (VA+VB)/2 regardless of the value of VC.

(1) ′: Luminance signal ■ obtained from the area 2c at the periphery of the field area 6 shown in Fig. 52. is larger than the reference voltage Vrl, that is, when V (> V r +), it is determined that the subject is outdoors (when there is a bright subject such as the sky in the background, and the peripheral area of the screen is determined to be bright) ,
At this time, the constant reference voltage vP1. VP2+ vO
l, ■02 (Relationship of reference voltage is V P2<O< V
p+, V02<0ku■. 1), the photometric value V is obtained by the following operation.

- Find V2.

Specifically, when The luminance signal difference ΔCB in the region 2C is a predetermined value ■ on the + side. 1, and at this time the main subject is in area 2A and area 2B.
It can be concluded that there are many cases in which both of these conditions exist. Therefore, in order to apply an appropriate voltage to the main subject, the photometric values V, -V, target the luminance signals VA, V of area 2A and area 2B, and the correction value v2 is set to 0, and the following calculation formula is used. ■Seek more.

V+ −V2 = (VA +Va) / 2 −
3, 4, and 5. First, the selection circuit 14 in FIG. 4 will be explained. The photometric signal (voltage) VC in the peripheral area 2C is greater than the reference voltage vr. Therefore, the comparator 34 outputs the H level, and therefore the H level is output to the control terminal B/U of the reference voltage generation circuit 35.
A level signal is supplied, and the reference voltage of the circuit 35 is v8
=■Pl+ vPb=vP2, Voa=Vo+, V
oh=Voz. On the other hand, the output signals (voltages) V and -VA of the operational amplifier 27 meet the condition of V P2<ΔaA<VPI, so the output of the comparator 36 becomes L level, the output of the comparator 37 becomes H level, and the AND gate 4
The output of 0 becomes H level. Further, since the output signal (voltage) Vc Va of the operational amplifier 32 satisfies Vo, <Δca, the output of the comparator 41 becomes H level, and the output of the comparator 42 becomes H level. Therefore, only the AND gate 49 has an H level output, and the H level output of this AND gate 49 and the AND gates 46 to 48.50
54 and the H level output of the comparator 34, the gate circuit 55 sets only the output signal 55g to the H level, and the other output signals 55a to 55f.

55h and 55i are set to L level, and the voltage at the θ1 output terminal is set to 0.
■. Therefore, the voltage (VA+VB)/2 is output from the operational amplifier 17 in FIG. 3, and Ov is supplied to the negative phase input terminal of the operational amplifier 22, so the operational amplifier 22
2's output 1-V2 becomes the voltage (VA +v, )/2.

Specifically, as shown in FIG. 7(b), the luminance signal Δ between the area 2A and the area 2B is larger than the predetermined value VPI on the + side, and furthermore, the luminance signal difference Δc8 between the area 2B and the area 2C is Since it is larger than the predetermined value VQI on the + side, it can be determined that the main subject is often present in the entire region 2A and a part of the region 2B.

The photometric values V and -V2 are obtained from the following calculation formula (2), with the correction value (2) being Vr2.

'/I V2 = (VA + Va)/2-v, 2
m■Then, the circuit operation is such that comparators 34, 36, 37, 41 and 42 all output H level, only AND gate 46 outputs H level, and the other AND gates 47 to 54 output L level. . Therefore, the gate circuit 50 includes the comparator 34 and the AND gates 46 to 5.
In response to the output of the operational amplifier 17, the output signal 55ceH level is set, and the output signals 55a, 55b, 55d to 55i are set to the L level, and the output of the operational amplifier 17 becomes the voltage (VA+V[l)/2
Therefore, the output v1-V2 of the operational amplifier 22 is (VA +
va )/2 Vr2.

Specifically, as shown in FIG. 7(C), area 2
The luminance signal difference ΔBA between A and area 2B is a predetermined value VP on the + side.
On the other hand, the luminance signal difference Δ between area 2B and area 2C is larger than I. is small, so in this case it can be determined that the main subject exists in the entire area 2A, or that the main subject is particularly small in many cases. In this case, in order to give appropriate exposure to the main subject, the photometric values V, -V2 are (1-2).
Similarly, by setting the correction value V2 to Vr2, it is obtained from the following calculation formula (2).

Vl - V2 = (VA'+VB) / 2-V,
2...■Then, the circuit operation is performed by the comparator 34,
36, 37 and 42 all output H level, while comparator 41 outputs L level, and AND gate 45
outputs H level, antenna 4F outputs H level, and other AND gates 46, 48 to 54 output L level. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, and sets the output signal 55c to the H level, and then the output signal 55a.

55b, 55d to 55i are set to L level, the output of the operational amplifier 17 becomes the voltage (VA + Va)/2, and the output V, -V2 of the operational amplifier 22 becomes (VA + Va)/2.
2 Vr2.

Specifically, as shown in FIG. 7(d), area 2
The luminance signal difference ΔBA between A and area 2B is a predetermined value VP on the + side.
On the other hand, the luminance signal difference ΔCB between area B and area C is a predetermined value ■ on one side. 2, so in this case, the main subject is about the same size as the case described in (1-3) above, and there is a fairly high-intensity subject in area 2B (for example, the sun, reflections on the sea surface, etc.) It can be determined that there is a subject with considerably high brightness in area 2B in a landscape photograph or the like. In this case, the correction value ■2 is set to the luminance signal difference V11 - VC.
Using (Va Vc)/2, it is calculated from the following arithmetic expression (2).

VI V2 = (VA +VB) / 2- (
VB - VC)/2...■Then, the circuit operates as follows: comparators 34, 36 and 37 output H level, while comparators 41 and 42 output L level,
AND gate 48 outputs H level, and other AND gates 46, 47, 49 to 54 output L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, and sets the output signal 55b to H.
level, and furthermore, the output signals 55a, 55c to 55i are set to L.
As a level, the output of the operational amplifier 17 is a voltage (VA +
VB )/2, and the output of the operational amplifier 22 is V, -V2.
is (VA + Va) / 2 (Va Vc)
/ It becomes 2.

Specifically, as shown in FIG. 7(e), area 2
The brightness signal difference Δ between area A and area 2B is small, and the brightness signal difference ΔCB between area 2B and area 2C is a negative value and has a larger absolute value than VB2, so in this case, the main subject is in areas 2A and 2B.
However, whitishness can be determined in large cases that exist on both sides. Therefore, at this time, in order to provide an exposure that highlights the main subject, the photometric value V, -
V2 is the brightness signal difference V of the correction value ■2.

Using -Vc and setting (V, -vc)/2, it is calculated from the following arithmetic expression (2).

V+ -Vz = (VA +V11) / 2-
(va - vc) /2...■Then, the circuit operation is such that the comparators 34 and 37 output H level,
On the other hand, the comparators 36, 41 and 42 output L level, the AND gate 40 outputs H level, the AND gate 51 outputs H level, and the other AND gates 46 to 5'0.52 to 54 output L level. Outputs L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the ant gates 46 to 54 and sets the output signal 55b to H.
level and further output signal 55a.

With 55c to 55a set to L level, operational amplifier 17 (7
) output is voltage (VA + VB) / 2tt”
), operational amplifier 22 output V, -Vz is (VA +V, )
/2-(va-vo)/2.

(ta), specifically, as shown in FIG. 7(f), the area 2
The luminance signal difference ΔBA between A and area 2B is a negative value and a predetermined value V
The absolute value is larger than P2, and the luminance signal difference ΔC5 between area B and area 2C is also a negative value, and the absolute value is larger than the predetermined value VQ2, so in this case, the main subject is the entire area 2A and area 2B.
It can be determined that this is a medium-sized case where the object exists in a part of the object and the object is whitish. In this case, in order to give an exposure that highlights and depicts the main subject as in the case (1-5) above, the photometric values V and -V2 are adjusted by the brightness signal difference V, -V.

Using (va-VC), it is calculated from the following arithmetic expression (2).

V+ -Vz = (VA +Va)/2-(va
-V()...■Then, the circuit operation is such that the comparator 34 outputs the H level, while the comparators 36 to 42 output the L level, and the AND gate 54 outputs the H level.
level, and the other AND gates 46 to 53 are L.
Output the level. Therefore, the gate circuit 55 receives the outputs of the comparator 34'EL and the AND gates 46 to 54, sets the output signal 55a to H level, and further changes the output signal 55b to 55.
5i is set to L level, the output of the operational amplifier 17 is the voltage (
VA+V, )/2, and the output of the operational amplifier 22 is V 1
V2 is (VA +V!1)/2- (VB -Vc
).

Specifically, as shown in FIG. 7(g), area 2
The luminance signal difference ΔaA between A and area 2B is a negative value and a predetermined value V
The absolute value is larger than P□, and the luminance signal difference Δ,B between area 2B and area 2C is small, so in this case, the main subject exists in the entire area 2A, or the main subject is particularly small. , and the main subject is a whitish subject. In this case as well, in order to obtain an exposure in which the main subject is depicted as a highlight, the correction value v2 is calculated using the luminance signal difference VB-V, (V, -
Vc ) is calculated using the following arithmetic formula (2).

V (Vz = (VA+ Va) / 2- (V
a - Vc )...■Then, the circuit operation is such that the comparators 34 and 42 output H level, while
Comparators 36, 37 and 41 output L level,
AND gate 45 outputs H level and AND gate 53
outputs H level, and the other AND gates 46 to 52
．． 54 outputs L level. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55a to H level, and further changes the output signal 55a to the H level.
When b~55i is set to L level, the output of the operational amplifier 17 becomes the voltage (VA+VB)/2, and the output V, -V2 of the operational amplifier 22 becomes (vA+vB)'/2C
VB-■c).

Specifically, as shown in FIG. 7(h), the area 2
The brightness signal difference Δ between A and 2B is a negative value and the absolute value is larger than the predetermined value VP2, and the brightness signal difference Δco between the areas 2B and 2C is larger than the predetermined value VOI. When the size is similar to the case described in (1-1) above and there is a difference in brightness in the main subject part, and area 2A is slightly high brightness, or when area 2B is in a landscape photograph, etc. It can be determined that this is a case where the subject is occupied by a subject with considerably low brightness.

In this case, the correction value v2 is set to Vr, 3(0<Vr3<Vr
2) is obtained from the following arithmetic expression (2).

VI V2 = (VA + Va)/
2-Vr3...■Then, the circuit operation is such that comparators 34, 41 and 42 output H level, while comparators 36 and 37 output L level, AND gate 52 outputs H level, and other AND gates output H level. Gate 46~
51, 53, and 54 output L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, and sets the output signal 55d to H level, and the output signals 55a to 55C355e to 551.
is set to L level, the output of the operational amplifier 17 is the voltage (VA
+V11)/2, and the output V of the operational amplifier 22,
-V2 becomes (VA +VB)/2 Vr3.

Specifically, as shown in FIG. 7(i), area 2
The luminance signal difference Δ between A and area 2B is smaller, and area 2
The luminance signal difference Δca between B and area 2C is also small, and in this case it can be determined that the main subject occupies the entire field, or there is no intention to set the main subject, such as in a landscape. In this case, areas 2A, 2B and 2
With the brightness of c as the target and the correction value v2 set to 0, it is determined by the following calculation formula (2).

vl-■2=(■6+V!I)/2...■Then, the circuit operation is such that comparators 34, 37 and 42 are high
On the other hand, comparators 36 and 41 output L level, ungates 40.41 output H level, AND gate 50 outputs H level, and other AND gates 46 to 49.51 to 54 output high level. outputs L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the analog games 1, 46 to 54, and sets the output signal 55g to H level, and further outputs the output signals 55a to 55f, 55h,
55i is set to L level, the output of the operational amplifier 17 becomes the voltage (VA +Va )/2, and the output V, -V2 of the operational amplifier 22 becomes (VA +V, )/2! becomes.

(2) Second diagram: Area 2C around the shown field area 6
When the luminance signal vc obtained from the reference voltage Vrl is smaller than the reference voltage Vrl, that is, ■. When it is determined that the room is in a room with a wall or the like in the background as < v rl, in this case as well, the luminance signal difference Δ□ and the luminance signal difference Δca are determined as in (1) above. Te constant VP3. VF6. V.O.
31VO4 (VF6<0<V P3.V oa<
0 < V oa), the photometric value V is calculated by the following operation.
, -V2 is determined.

Specifically, as shown in FIG. 8(a), the brightness signal difference Δ8A between the area 2A and the area 2B becomes small, and the brightness signal difference ΔBA between the area 2B and the area 2C is larger than the predetermined value VOa. In this case, it can be determined that the main subject is large, existing in both areas 2A and 2B, and is a dark subject.

In this case, the photometric values V and -V are used to provide exposure such that the main subject portion is rendered in shadow.

is the correction value V2, using the luminance signal difference V, -V, -(v
a − vc )/2 and is calculated from the following calculation formula [phase].

VI V2 = (VA+Va)/2” (Va
-Vc) / 2 ... [phase] Then, in the circuit operation, since the photometric signal (voltage) VC of the outermost region 2C is smaller than the reference voltage Vrl, the comparator 34 outputs the L level, and therefore the reference voltage An L level signal is supplied to the control terminal B/D of the generation circuit 35, and the reference voltage of the circuit 35 is V Pa=■P3+V Pb=V
P4*V oa=V o8. Vob=Vo4
Tonal. On the other hand, the comparator 36 outputs L level,
On the other hand, comparators 37, 41 and 42 output at H level, AND gate 40 outputs H level, AND gate 49 outputs H level, and AND gates 46 to 4
8.50 to 54 output L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55i to H level, further sets the output signals 55a to 55h to L level, and outputs the operational amplifier 17 to the voltage (■i+Va)/ 2, and the output V, -V2 of the operational amplifier 22 is (VA +VB
)/2+ (Va −Vc )/2.

Specifically, as shown in FIG. 8(b), the luminance signal difference Δ□ between the area 2A and the area 2B is larger than the predetermined value VP3, and the luminance signal difference Δca between the area 2B and the area 2C is the predetermined value VO.
Since it is larger than 3, it can be determined that the main subject is present in all of the area 2A and part of the area 2B, and that it is a dark subject. In that case, in order to give the main subject an exposure that will be depicted as a shadow in the same manner as in 2-13 above, the photometric values V and -V2 should be changed to the correction value v2.
is determined by the following arithmetic expression (2), using the luminance signal difference V and -VC as -(va vc).

VI V2 = (VA + Va) / 2
+ (Va −Vc) ・・
・■Then, the circuit operation is such that the comparator 34 outputs the L level, while the comparators 36 to 42 all output the H level, the AND gate 46 outputs the H level, and the other AND gates 47 to 54 output the L level. Output. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55h to the H level, further sets the output signals 55a to 55g, and 55i to the L level, and outputs the operational amplifier 17 to the voltage (VA + va
)/2, and the outputs v, -v2 of the operational amplifier 22 are (V
A + vB)/2+ (VaVC).

Specifically, as shown in FIG. 8(c), the area 2A
The luminance signal difference Δ5A between the region 2B and the region 2B is much smaller than the predetermined value VP3, while the luminance signal difference ΔC6 between the region 2B and the region yg2C is small. It can be determined that this is a case where the distance is small and the subject is dark. In this case, in order to give an exposure that gives a sharp depiction of the main subject, the photometric values V, -V, and the correction value ■2 are set to the brightness signal difference V.
Using a-Vc and setting it as -(Va-Vc), it is determined by the following arithmetic expression @.

VI −V2 = (VA +VB) / 2+ (
Va - Vc )...@Then, the circuit operation is as follows: comparators 34 and 41 output L level, comparators 36.3 and 42 output H level, and AND gate 45 outputs H level, AND gate 47 outputs H level, and the other AND gates 46, 48 to 54 output L level. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55h to the H level, further sets the output signals 55a to 55g, and 55i to the L level, and outputs the operational amplifier 17 to the voltage (VA+Ve). /2, and the output V, -V2 of the operational amplifier 22 is (vA+V,)/2+
(Va-Vc").

Specifically, as shown in FIG. 8(d), the luminance signal difference Δa between the area 2A and the area 2B is larger than the predetermined value VP3, and the luminance signal difference Δca between the area 2B and the area 2C is a negative value. The predetermined value is ■. Since the absolute value is larger than 4, the main subject is as described above (
It can be determined that this is a case where the object is a normal object of approximately the same size as in case 2-3) and there is a high-luminance object (for example, an electric light) in the region 2B. Area 2 indoors as in this case
When there is a high brightness subject in B, it can be said from the data that the influence of this high brightness is less than when the outdoor sun etc. is located in area 2B, so the photometric values V, -V,
is obtained from the following arithmetic expression 0, with the correction value ■2 as a negative value VrS.

v+ −Va = (VA +Va )/2+Vrs
=@Then, the circuit operation is such that comparators 34, 41 and 42 output L level, while comparators 36 and 3
7 outputs H level, AND gate 48 outputs H level, and other AND gates 46, 47, 49 to 54
outputs L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55f to H level, and further outputs the output signals 558 to 55e, 55g to 551.
is set to L level, the output of the operational amplifier 17 is a voltage (V,
+VB)/2, and the output V of the operational amplifier 22, -V2
is (VA +VB)/2+Vrs.

Specifically, as shown in FIG. 8(e), region 2
The luminance signal difference ΔaA between A and area 2B is small;
and the luminance signal difference Δ between the area 2C and the area 2C. , is a negative value and the predetermined value VO
Since the absolute value is larger than 4, the main subject is in areas 2A and 2B.
It is determined that this is the case where the light exists in both areas and only the areas 2A and 2B are illuminated by the light.

The photometric value VI-V2 is determined by the following calculation formula, with the correction value v2 set as O. Then, the circuit operates as follows: comparators 34, 36° 41 and 42 output L level, while comparator 37 outputs H level.
AND gate 40 outputs H level, AND gate 51 outputs level, and the other AND gates 46' to 50 and 52 to 54 output L level. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55g to H level, and further sets the output signals 55a to 55f, 55h, 5
5i is set to L level, the output of the operational amplifier 17 is the voltage (
VA+Va)/2, and the output of the operational amplifier 22 is V, -
V is also (VA+Ve)/2.

Specifically, as shown in FIG. 8(f), the area 2A
A luminance signal difference Δ between and area 2B, A is a negative value and a predetermined value v,
4, and the luminance signal difference Δca between area 2B and area 2C is also a negative value, and the absolute value is larger than the predetermined value VQ4, so if the main subject exists in all of area 2A and part of area 2B. In this case, it can be determined that all of the area 2A and a part of the area 2B are illuminated by the light. In this case, it is necessary to correct using a correction coefficient more than in case (2-5) above in order to give appropriate exposure to the main subject, and the photometric value V1 - V, is a negative value of the correction value v2. The value -Vr4 (1-Vr41>I-vrsl) is calculated using the following arithmetic expression (2).

V+ −V2 = (″”VA + Va) / 2
+ Vr< -@Then, the circuit operation is such that all the comparators 34 to 42 output L level, and the AND gate 54
outputs H level, and the other AND gates 46 to 53
outputs L level. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, sets the output signal 55e to H level, and further outputs the output signals 55a to 55.
55d.

When 55f to 55i are set to L level, the output of the operational amplifier 17 becomes the voltage (VA+Va)/2, and the operational amplifier 22
The output V, -V, is (VA +V,)/2 + V
It becomes r4.

Specifically, as shown in FIG. 8(g), the area 2
The luminance signal difference ΔI between A and area 2B is negative and has a predetermined value VP.
4, and the luminance signal difference Δca between area 2B and area 2C is small, so in this case, the main subject is in area 2.
It can be determined that the main subject exists in the entire area A, or the main subject is small and exists in a part of the area 2A. In this case, in order to give appropriate exposure to the main subject, the photometric values v, -V2 are calculated using the following formula, with the correction value v2 set as -Vr4, as in (2, -6). .

V+ -V2 = (VA +V@)/'2+Vr4
...[Phase] And the circuit operation is performed by comparators 34 and 3.
6°37 and 41 output L level, on the other hand, comparator 42 outputs H level, AND gate 45 outputs H level, AND gate 53 outputs H level,
The other AND gates 46 to 52.54 output L level. Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, and outputs the output signal 5.
5e to H level, and output signals 55a to 55d, 55
When f~55i is set to L level, the output of the operational amplifier 17 becomes the voltage (VA + Va) /2, and the operational amplifier 22
The output V, -V2 becomes (VA +V11)/2+Vr4.

Specifically, as shown in FIG. 8(h), the area 2
The luminance signal difference Δ□ between A and area 2B is a negative value and has a predetermined value VP.
4, and the luminance signal difference Δca between area 2B and area 2C is larger than the predetermined value VQ3. This may be the case when there is a difference in brightness in some areas, and area 2A has a slightly high brightness, but the subject as a whole is blackish, or when a subject with considerably low brightness occupies area 2B in an H1 landscape photograph, etc. It can be determined that In this case,
The photometric value v, -V2 is the correction value V2, and the luminance signal difference Vl, -v
Using c, -(Vav c ) / 2 is calculated using the following arithmetic expression O.

V, -V, = (VA + Va) / 2 + (Va - Vc) / 2 ... 0 Then, the circuit operation is such that comparators 34, 36 and 37 output L level, while comparators 41 and 42 output H level. The AND gate 52 outputs an H level, and the other AND gates 46 to 51, 53, and 54 output an L level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, and sets the output signal 55i to H.
level, and further output signals 55a to 55g, 55h to L
As a level, the output of the operational amplifier 17 is a voltage (VA+V
a)/2, and the outputs V, -V, of the operational amplifier 22 are (
VA + VB)/2+ (va-VC)/2.

Specifically, as shown in FIG. 8(i), the area 2
The luminance signal difference ΔIIIA between A and area 2B is small, and
The brightness between area 2B and area 2C (the a difference Δca is also small, so if the main subject occupies the entire field at this time,
Alternatively, it can be determined that the main subject is not particularly set, such as in a landscape photograph. In this case, the photometric value vl-v2 is calculated using the following calculation formula [
phase].

vl −V2 = (VA + Va) / 2
...@Then, the circuit operation is performed by the comparator 34,
36 and 42 output L level, while comparator 3
7.41 outputs H level, AND gate 40.45 outputs H level, AND gate 50 outputs H level, and other AND gates 46 to 49. 51 to 54 output L level.
Output the level.

Therefore, the gate circuit 55 receives the outputs of the comparator 34 and the AND gates 46 to 54, changes the output signal 55g to H level, and further outputs the output signals 55a to 55f, 55h, 55.
i is set to L level, the output of the operational amplifier 17 is a voltage (V
A + Va )/2, and the output V of the operational amplifier 22 is
-V is also (V A + V a )/2.

The features of the photometric device according to the embodiments described above are as follows:
Assuming that the main subject is located in the center of the field area, the size of the main subject can be determined and correction can be made in accordance with the size of the main subject.

Furthermore, when the photometry device of this embodiment detects that the subject is whitish or blackish, it intentionally depicts highlights (highlight control) so that whitish subjects appear white and dark subjects appear black. Shadow depiction (shadow control) is corrected, and the amount of correction is changed depending on the size of the main subject, making it possible to control photometric values extremely effectively.

In addition, in the explanatory diagrams of FIG. 7 and FIG. 8 used in the explanation of the above-mentioned embodiment, the values of the brightness level of each area 2A to 2C are as follows.
When the brightness difference between adjacent areas is small, the same level is shown, but this is a thermal theory, and in actual photometry, there will be some difference (it means that the brightness difference is smaller than the predetermined value compared, for example, VPI). ), FIGS. 7 and 8 serve only as explanatory diagrams to facilitate understanding of the present invention.

In the above embodiment, there are two calculation methods for the photometric values V and -V2: one when the luminance at the periphery of the screen is high and one when the luminance is low.
Although we have divided the cases into three cases, in addition to the case where the brightness in the peripheral area of the screen is medium, a more detailed case classification may be performed in the same manner as described above to obtain the photometric value.

Alternatively, the field of view may be divided into three or more annular regions, and the luminance signal difference between adjacent regions may be used.

Note that the present invention is not limited to single-lens reflex cameras, but can also be favorably applied to lens-shutter cameras and the like. In this embodiment, the selection circuit is constructed of a logic circuit, but it is of course a matter of course that the present invention can also be implemented by performing software processing using a microcomputer.

(Effects of the Invention) As explained above, the present invention is a suitable photometry device that assumes that the main subject is in the center of the field, and uses the luminance information of the center area of the field as a reference. By using the brightness difference information between the brightness information of the central part and the brightness information of the peripheral part of the object field to selectively determine the correction value and determine the photometric value by calculation, the conventional center It is possible to provide an extremely effective photometry device that takes advantage of the advantages of partial photometry and incorporates the advantages of conventional center-weighted average photometry.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical system as an embodiment when the present invention is applied to a single-lens reflex camera. FIG. 2 is an explanatory diagram showing a plurality of photometric areas on the light receiving surface of the light receiving means of FIG. 1 according to the embodiment of the present invention. FIG. 3 is a circuit diagram of an embodiment of the present invention. FIG. 4 is a detailed circuit diagram of the selection circuit of FIG. 3. FIG. 5 is a circuit diagram showing an example of the gate circuit of FIG. 4. FIG. 6 is an explanatory diagram illustrating the photometric value calculation formula selected in FIG. 3. 7 and 8 are explanatory diagrams showing the levels of photometric values obtained using the photometric value calculation formula selected in FIG. 3. FIG. 2A, 2B, 2C --- Each light receiving area 6 ---
---------1------------Light receiving section 14------
-------1--------1 transition selection circuit lido CQ) (b), h) (C) (L)

Claims (2)

[Claims] (1) A light-receiving means consisting of a plurality of light-receiving sections that roughly divides the field into a central region at the center and a peripheral region outside the central region, and obtains luminance information for each region, and corresponds to the central region. central brightness calculating means for calculating brightness information of a central region based on the output of the light receiving section corresponding to the peripheral area; peripheral brightness calculating means for calculating brightness information of the peripheral area based on the output of the light receiving section corresponding to the peripheral area; brightness difference calculation means for calculating brightness difference information based on the output of the light receiving section corresponding to the central region and the output of the light receiving section corresponding to the peripheral region; Correction value calculation means for calculating brightness correction information; Field brightness calculation means for calculating brightness information as a field by correcting the brightness information of the central area using the brightness correction information. Photometering device. (2) A photometric device according to claim 1, wherein the central region is multi-divided.