JPH08201873A - Exposure determining apparatus for camera - Google Patents

Abstract

PURPOSE: To carry out proper exposure by carrying out proper correction even in complicated luminous distribution conditions by a photometric sensor with a few divisions and calculating correction values based on the brightness difference between the center of a subject field and the peripheral part of the field and the photographing magnification to provide exposure close to the proper exposure. CONSTITUTION: Photometric values of the center of a subject field and the periphery, brightness difference between the center and the periphery and distribution information, the subject distance information, a focal distance information of a photographing lens, and a photographing mode are inputted to a computing part 3 from a photometric part 1, a reverse light determining part 2, a distance measuring part 4, a zoom part 5, and a photographing mode setting part 6, respectively. In the computing part 3, the average photometric value at the center focal point and the photographic magnification of a subject can be computed based on respective information. Further, based on the photographic magnification and the brightness distribution information, a factor γ1 is computed and information and the average photometric value at the center focal point to be calculated based on the brightness difference and the γ1 in the case the photographic mode is a specified mode can be computed and thus a proper exposure value can be calculated. Based on the proper exposure value computed by the computing part 3, exposure is carried out by an exposure controlling part 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera exposure determining device, and more particularly to a camera exposure determining device for dividing a field of view and performing photometry to obtain a proper exposure of a main subject.

[0002]

2. Description of the Related Art Conventionally, when a photograph is taken with a camera, the exposure field is determined by photometry of the field. For example,
In the technique disclosed in Japanese Patent Laid-Open No. 62-203141,
The field of view is divided into multiple concentric areas for photometry, the shooting magnification β is calculated from the subject distance and focal length, and if it is determined that the subject has a magnification corresponding to the central photometry element, the photometry distribution Then, the correction amount is calculated from the brightness difference and the center focus average value is corrected.

Further, in Japanese Patent Application No. Hei 6-271211, which is a prior application by the applicant of the present application, in order to improve the accuracy of FM calculation when a strobe occurs, the accuracy of distance measurement in the wide vicinity where the accuracy of distance measurement is poor is improved. The technology to do this is described.

[0004]

By the way, the technique disclosed in Japanese Patent Laid-Open No. 62-20314 makes correction only when it is determined that the subject matches the central area, and therefore, it can be used for all magnifications. In order to make them correspond, it is necessary to divide them into concentric circles. Therefore, the area of one divided cell becomes small and the photocurrent becomes small. Therefore, in order to enable accurate photometry at low luminance, a dedicated amplifier must be provided near the photometric sensor. Therefore, there are problems that the cost is increased and the shape of the element is increased.

The present invention has been made in view of the above problems, and it is possible to provide an exposure closer to a proper exposure by appropriately performing correction even under a complicated brightness distribution condition without increasing the number of photometric sensors. An object is to provide an exposure determination device for a camera.

[0006]

That is, the present invention provides an exposure determining apparatus for a camera, which comprises at least a central portion of a photographing screen and a photometric means for measuring the entire photographing screen excluding the central portion. Based on the output of the photometric means, it is determined whether or not the main subject is in the backlit state, and the first computing means for computing the first photometric value, the focal length information of the photographing lens, and the main subject distance information are used. And an output means for outputting a correction coefficient for correcting the first photometric value on the basis of the shooting magnification and the backlit state, and the first photometric value and the correction coefficient. And a second calculation means for outputting a value obtained by calculating as a second photometric value.

[0007]

According to the present invention, at least the central portion of the photographing screen,
In a camera exposure determination device equipped with photometric means for photometrically measuring the entire area of a photographic screen excluding the central portion, based on the output of the photometric means, whether or not the main subject is in a backlit state based on the output of the photometric means. Is determined and the first photometric value is calculated. Further, the photographing magnification of the main subject is obtained according to the focal length information of the photographing lens and the main subject distance information, and the correction for correcting the first photometric value based on the photographing magnification and the backlit state. The coefficient is output by the output means. Then, a value obtained by multiplying the first photometric value by the correction coefficient is output from the second computing means as the second photometric value. Accordingly, the subject distance information is used when the correction value is calculated based on the shooting magnification, and the correction value is suppressed so that the calculated correction value does not become an abnormal value on the wide side where the distance measurement accuracy is low.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention and is a block diagram showing an outline of an exposure determining device of a camera.

In FIG. 1, the output of the photometric unit 1 such as a photometric sensor that outputs the photometric values at the center and the periphery of the field is the backlight determination for determining whether the brightness distribution of the field is backlight or forward light. It is supplied to the arithmetic unit 3 via the unit 2 or directly. The calculation unit 3 includes a distance measuring unit 4 for outputting distance information of a main subject in the scene, a zoom unit 5 for outputting focal length information, and a shooting mode setting for setting a shooting mode and outputting mode information. Various information is supplied from the unit 6. Then, the proper exposure value is output from the calculation unit 3 to the exposure control unit 7.

In such a structure, when the photometric values at the center and the periphery of the field are output from the photometric section 1, the backlight determination section 2 obtains the difference in brightness between the center and the periphery and the subject is photographed. It is determined whether the field brightness distribution is backlight or forward light, and the brightness difference and brightness distribution information are output. On the other hand, the distance measuring unit 4 outputs distance information of the main subject in the scene, and the zoom unit 5 outputs focal length information by changing the focal length of the taking lens. Further, the shooting mode setting unit 6 outputs information on the set shooting mode.

Then, the photometric value from the photometric unit 1, the brightness difference and the brightness distribution information from the backlight determination unit 2, the subject distance information from the distance measuring unit 4, the focal length information from the zoom unit 5, the photographing mode setting unit 6 from the photographing mode. Are input to the calculation unit 3, respectively. In the calculation unit 3, the central focus average photometric value is obtained from the photometric value, and the photographing magnification of the subject is obtained from the subject distance information and the focal length information. Further, the first coefficient γ ₁ is calculated from the photographing magnification and the luminance distribution information, and when the photographing mode is a predetermined mode, the luminance difference and the first coefficient γ ₁ are calculated.
_The information obtained from ₁ and the center-weighted average photometric value are calculated to obtain the proper exposure value. Then, based on the proper exposure value obtained by the calculation unit 3, the exposure control unit 7
Is exposed at.

FIG. 2 is a circuit diagram showing the details of the above-described camera exposure determination device. In FIG. 2, the main CPU 10 sequentially executes programs recorded in its internal ROM to control peripheral ICs and the like. To the main CPU 10, an AFIC 11 which is an IC for autofocus (AF) and an EEPROM 12 which is a non-volatile element are connected. In addition, in this camera, the autofocus system adopts the TTL phase difference detection system.

The main CPU 10 has a liquid crystal display panel 13, a date module 14, a strobe unit 15, and an interface IC (IFIC) 16.
Is connected. The IFIC 16 receives the infrared remote controller. That is, the light emitting diode for emitting light (LE) attached to the remote control transmission unit 17
The modulated infrared light is emitted from D) 18, and the infrared light is received by the light-receiving silicon photodiode (SPD) 19 connected to the IFIC 16. The output of the SPD 19 is transferred to the main CPU 10 after undergoing processing such as waveform shaping inside the IFIC 16.

The IFIC 16 is connected to an LED 20 for display in the finder for the end of AF distance measurement, a strobe light emission warning, or an LED used for a photointerplater or the like. Further, the IFIC 16 is connected with a photometric sensor 21 for photometrically measuring the entire photographing screen, a motor driver 22 for driving various motors, which will be described later, and a photo reflector (WPR) 23 for detecting a film feeding amount.

The motor driver 22 includes a sequence motor (M1) 24 for film feeding, shutter charging, and mirror driving, a lens driving LD motor (M2) 25 for focus adjustment, and a lens frame zooming unit. ZM motor (M3) 26, LED 27 for self-timer operation display, front curtain magnet (MGF) 28 for attracting and holding the front curtain of the focal plane shutter, and rear curtain magnet (for attracting and holding the rear curtain of the focal plane shutter). MGS) 29 is connected.

In the vicinity of the sequence motor 24, the LED motor 25, and the ZM motor 26, shutters,
A charge photo interrupter (SCPI) 31, a lens photo interrupter (LDPI) 32, a zooming photo reflector (ZMPR) 33, and a zooming photo interrupter (ZMPI) 34 are provided and are connected to the main CPU 10 and the IFIC 16.

A diaphragm photo interrupter (AVP)
I) 35 is provided in the vicinity of a stepping motor (AV motor; M4) 36 for driving the aperture adjustment unit, and is connected to the motor driver 22 and the IFIC 16. The AV motor 36 is driven by the main CPU 10 via a motor driver 37.

Further, the main CPU 10 is connected with various switches 40 to 52, 55 to 63, which will be described in detail later, and a piezoelectric buzzer (PCV) 65 which emits a sound when the focus is adjusted during autofocus and the switch is operated. There is.

First, the AFIC 11 includes the main CPU 10
Reset signal of AFIC11 (AFRES) Sig
1 is sent and reset. Light from the subject reaches a photosensor array arranged on the upper surface of the AFIC 11 through a taking lens (not shown). Then AFI
Inside C11, processing such as light quantity integration and quantization is performed. Then, the focus shift amount is calculated as the distance measurement information.

When the light amount integration is completed, the signal (AFEND) Sig2 indicating that the light amount integration is completed is sent to the main CP.
Sent to U10. AFIC 11 and main C for distance measurement information
A signal (AFCEN) indicating that communication between PUs 10 is performed
Sig3, data signal (DATA) Sig4, synchronization clock signal (CLK) Sig5, main CPU10
Transferred to

By the way, if the characteristics of the respective elements of the photosensor array vary, accurate distance measurement information cannot be obtained as it is. Therefore, the EEPROM 12
The variation information of the photosensor array is stored in advance, and the main CPU 10 performs the correction calculation of the distance measurement information obtained from the AFIC 11.

In addition, the EEPROM 12 stores various adjustment values such as mechanical variations and variations in electrical characteristics of various elements. These adjustment values activate the EEPROM 12 as needed. That is, a signal (EPCEN) Sig7, a data signal (DATA) Sig8, and a synchronous clock signal (CLK) S that make the communication possible.
Reading can be performed by ig9. The main CPU
Data is exchanged among the 10, AFIC 11, and EEPRM 12 by serial communication. A more detailed description will be given later.

In the date module 14, the main CPU
The imprint signal Sig10 from 10 imprints the date on the film. The light emission time of the projection lamp changes stepwise depending on the film ISO speed.

The IFIC 16 is activated by an IFIC activation signal (IFCENb) Sig11 from the main CPU 10. Then, the main CPU 10 and the latch signal (LATCH) Sig12, 4-bit bus line signals (D0b to D3b) Sig13 to Sig16, D / Ab.
Parallel communication is performed by using the signal Sig17, measurement of subject brightness, measurement of camera internal temperature, waveform shaping of output signal of photointerplater, constant voltage drive control of motor, temperature stable voltage, temperature proportional voltage, etc. Generation of various constant voltage, battery remaining amount check, infrared light remote control reception,
Control of the motor driver, control of various LEDs, low voltage monitoring of the power supply voltage, control of the booster circuit, etc. are performed.

The latch signal Sig12 is a signal for timing the reading of the signal on the bus line.
The D / Ab signal is a 4-bit bus line signal Sig1.
3 to Sig16 are signals indicating whether they indicate an address or data. D /
When the Ab signal is "high level (H)", the 4-bit bus line signals Sig13 to Sig16 represent addresses,
4 bits when the D / Ab signal is "low level (L)"
The bus line signals Sig13 to Sig16 represent data.

The subject brightness is measured by a photometric sensor 21 which is composed of two-divided silicon photodiodes (SPD).
Is performed using. The light-receiving surface of the photometric sensor 21 is divided into two parts such as a screen central part and its peripheral part, and spot photometry for performing photometry only in a part of the screen center,
Two types of photometry can be performed: average photometry using the entire screen.

From the photometric sensor 21, a current corresponding to the brightness of the subject is output to the IFIC 16. IFIC16
Then, the output from the photometric sensor 21 is converted into a voltage and transferred to the main CPU 10. The main CPU 10 performs exposure calculation, backlight judgment, etc. based on the voltage information.

For measuring the temperature inside the camera, a voltage proportional to the absolute temperature is output from the circuit built in the IFIC16.
A value is obtained by subjecting the signal to A / D conversion in the main CPU 10. The obtained temperature measurement value is used for, for example, correcting a mechanical member whose state changes with temperature or an electric signal.

In the waveform shaping of the photo-interplater or the like, the photocurrent of the output of the photo-interplater or the photo-reflector is compared with the reference current and output from the IFIC 16 as a rectangular wave. At this time, noise is removed by giving a hysteresis to the reference current. Further, the reference current and the hysteresis characteristic can be changed by communicating with the main CPU 10.

To check the remaining capacity of the battery, a low resistance is connected to both ends of the battery, and the voltage across the battery when a current is applied is divided inside the IFIC 138 so that the CPU 120
To the CPU 10 and the CPU 10 performs A / D conversion to obtain a voltage value. For reception of the infrared light remote controller, modulated infrared light is emitted from the LED 18 for light projection of the remote controller transmission unit 17, and the infrared light is received by the SPD 19 for light reception.
Will be received at. The output of the SPD 18 is subjected to processing such as waveform shaping in the IFIC 16 and then output from the main CPU 10.
Transferred to

The IFIC 16 performs low voltage monitoring of the power supply voltage. That is, the IFIC 16 is provided with a dedicated terminal, and when the voltage input to the IFIC 16 falls below a specified value, a reset signal is output from the IFIC 16 to the main CPU.
10 is output to the CPU 10 to prevent runaway of the CPU 10 and the like. The control of the booster circuit is to operate the booster circuit when the power supply voltage drops below a predetermined value.

On / off of these LEDs and control of the amount of emitted light are performed by communication between the main CPU 10, the EEPROM 12 and the IFIC 16, and are directly controlled by the IFIC 16. What is controlled is SCPI31 LE
LED current Sig2 of D current Sig21 and LDPI32
2, LED current Sig23 of ZMPR33, ZMPI3
The LED current Sig24 of No. 4, the LED current Sig25 of the AVPI35, the LED current Sig19 of the WPR23, and the in-finder display LED 20 are on and off.

In the constant voltage drive control of each motor, the drive voltage can be set stepwise by communicating with the main CPU 10. The motor driver 22 performs film feeding, shutter charging, and mirror driving,
Sequence motor 24, LD motor 25, ZM motor 2
The driving of the three motors 6 and 6, the driving of the booster circuit, the driving of the LED 27 for displaying the self-timer operation, the control of the front curtain magnet 28 and the rear curtain magnet 29, and the like are performed.

These operation controls, for example, which device is driven, whether the motor is normally or reversely rotated,
The signal from the main CPU 10 is IFI
C16 receives this IFIC16 and the motor driver 22
Signal S for turning on / off each transistor (not shown) of
It is controlled by ig18. Whether the sequence motor 24 is in the shutter charge, film winding, or film rewinding state is detected by the SCPI 31 which is a photointerplater for detection, and the signal Sig26 is used as the main C signal.
It is output to PU10.

The lens extension amount is detected by the LDPI 32 attached to the LD motor 25, and its output Sig2
7 is the main CPU 1 after the waveform is shaped by the IFIC 16.
Sent to 0.

The zooming state of the lens frame is detected by ZMPI 34 and ZMPR 33 built in the lens frame.
When the lens frame is between TELE (tele end) and WIDE (wide end), the high reflection part provided on the lens frame is ZMPR3.
No. 3, and the non-reflecting portions are so arranged as to oppose to each other in other ranges.

As a result, the output Sig2 of the ZMPR 33 is output.
By inputting 8 to the main CPU 10, the tele end and the wide end can be detected. The ZMPI 34 is attached to the ZM motor 26, and its output Sig 29 is IF.
After the waveform is shaped by the IC 16, it is input to the main CPU 10 and the amount of zooming from the tele end or the wide end is detected.

The motor driver 37 is the AV motor 3
6 is an on / off signal (ENA) from the main CPU 10.
It is driven by the Sig 30 and the forward / reverse rotation signal (IN) Sig 31. In addition, AVPI35
The output Sig32 is waveform-shaped by the IFIC 16 and input to the main CPU 10 to detect the aperture open position.

The liquid crystal display panel 13 is a main CPU.
Segment signal (SEG) Sig3 sent from 10
4. The common signal (COM) Sig35 is used to display the number of film frames, shooting mode, strobe mode, aperture value, remaining battery level, and the like.

The strobe unit 15 is for causing the light emitting tube to emit light to give a required luminance to the subject when the subject's luminance is insufficient at the time of photographing or autofocus distance measurement. This strobe unit 15
Is controlled by the signal from the main CPU 10 by the strobe charge signal (STCHG) Sig36 of the IFIC 16, the strobe light emission start signal (STON) sig37, and the signal (STRG) Sig38 for controlling the trigger circuit. ing. Furthermore, the charging voltage of the strobe is
The VST signal Sig39 is sent to the main CPU 10.

The WPR 23 is arranged so as to face the perforation of the film. Since the light reflectance differs between the film surface and the perforation portion, the output of the WPR 23 differs when corresponding to each. That is, since the WP 23 alternately faces the film surface and the perforation during film feeding,
The output Sig20 of the WPR 23 has a pulse shape. Therefore, by counting the number of pulses, the film 1
It is possible to detect the movement amount of the frame.

In the switches 40 to 52, the key signal 0
To 5 (KEY0 to KEY5) Sig40 to Sig45 and key common 0 to 2 (KEYCOM0 to 2) Sig46
~ Sig48 is detected. From these signals, it is possible to know which of the switches 40 to 52 is on.

Since the KEY0 to KEY5 are normally pulled up inside the main CPU 10, the signal level thereof is in the "H" state. Here, for example, KEYC
It is assumed that the OMSig 46 is "L", the KEYCOMSig 47 is "H", and the KEYCOMSig 48 is "H". At this point, a first release switch 4 which will be described later
When 0 is turned on, the KEY0Sig 40 changes from "H" to "L". Therefore, KEYCOM0-2S
ig46 to 48 signal levels and KEY0 to 5Sig4
If the signal levels of 0 to 45 are known, the switches 40 to 52
It is possible to know which of the two is on.

KEYCOM0 to 2Sig46 to 48
Cannot be more than one "L" at the same time. The switch 40 is a first release switch (1RSW), which is turned on when the release button is half-pushed and is for performing a distance measuring operation. The switch 41 is a second release switch (2RSW), which is turned on when the release button is fully pressed, and the photographing operation is performed based on various measured values.

Switches 42 and 43 are a zoom up switch (ZUSW) and a zoom down switch (ZDS).
W), which is a switch for zooming the lens frame. When ZUSW 42 is turned on, ZDS moves in the long focus direction.
When W43 is turned on, zooming is performed in the short focus direction.

The switch 44 is a self switch (SELF).
SW), and when this SELFSW 44 is turned on,
The camera enters the self-timer shooting mode or the remote control standby state. In this state, if the 2RSW 41 is turned on, self-timer photographing is performed, and if a photographing operation is performed by the remote control transmitter, photographing by the remote control is performed.

The switch 45 is a spot switch (SP
OTSW). When the SPOT SW 45 is turned on, the spot metering mode is set in which the AFIC 11 measures only part of the center of the photographing screen for metering. In addition, SPOTSW45
For normal metering when is off, the photo sensor 2
1 is used.

Picture 1 switch (PCT1SW) 46
A picture 4 switch (PCT4SW) 49 and a program switch (PSW) 50 are program photographing mode changeover switches, and the photographer selects a mode according to photographing conditions.

The portrait mode in which the PCT1SW 46 is turned on is set, and the aperture and shutter speed are determined so that the depth of field becomes shallow within the proper exposure range. P
When the CT2SW 47 is turned on, the night view mode is set, and the value is set one step lower than the value of the proper exposure at the time of normal shooting. When the PCT3SW 48 is turned on, the landscape mode is set, and the values of the aperture and the shutter speed are determined so that the depth of field is as deep as possible within the proper exposure range. When the PCT4SW49 is turned on, the stop motion mode is set, and the shutter speed is set to be as high as possible. At this time, the red-eye prevention mode of the flash mode cannot be used.

The above PCT1SW46 to PCT4SW4
9 cannot select more than one at the same time. The switch 50 is a normal program shooting mode switch (P
SW). When the PSW 50 is pressed, the PCT1SW46 to PCT4SW49 are reset and the AV priority program mode described later is reset.

A strobe switch (STSW) 51 is a strobe light emission mode changeover switch. This STS
By operating W51, the normal automatic light emission mode (AUTO) and the red-eye reduction automatic light emission mode (AUTO-
S), forced light emission mode (FILL-IN), and strobe off mode are switched.

The switch 52 is an AV priority switch (AV
SW). Now, when the AVSW 52 is turned on, the shooting mode becomes the aperture priority program mode. In this mode, the photographer determines the AV value (aperture)
The shutter speed is determined by the program according to the value. In this aperture priority program mode, the PCT
The 2SW47 and the PCT4SW49 have no function as described above and serve as an AV value setting switch. PCT2SW47
Is a switch for increasing the AV value, and PCT4SW4
Reference numeral 9 is a switch for reducing the AV value.

The power switch (PWSW) 55 is the main switch of this camera. Panorama switch (P
ANSW) 56 is a switch for detecting whether the shooting state is panoramic shooting or normal shooting, and is turned on during panoramic shooting.

The back cover switch (BKSW) 57 is a switch for detecting the state of the back cover, and is in the off state when the back cover is closed. When the BKSW 57 shifts from the on state to the off state, film loading is started.

Shutter charge switch (SCSW) 5
Reference numeral 8 denotes a switch for detecting shutter charge. The mirror up switch (MUSW) 59 is a switch for detecting the mirror up, and is turned on when the mirror is up.

The DX switch (DXSW) 60 is a D indicating the sensitivity of the film printed on the film cartridge.
This is a switch for reading the number of X-code images and the exposure range, and for detecting the presence or absence of film loading. Although not shown, the DXSW 60 is composed of a group of 10 switches.

Pop-up switch (PUPSW) 61
Is a switch for controlling the strobe. PUPSW6
1 is interlocked with the movement of the strobe light emitting portion, and is turned on when the light emitting portion is raised to perform strobe charging. Also, the subject has low brightness and the flash mode is Auto.
If the PUPSW 61 is on while the flashing is on, strobe emission is permitted.

The rewind switch (RWMSW) 62 is a switch for forcibly rewinding the film. RW
If the MSW 160 is on, the film is forced to rewind.

The switch 63 is a switch (XSW) for adjusting the timing of strobe light emission. This XSW
63 is turned on when the front curtain of the shutter has finished running and is turned off when the shutter charge is completed.

FIG. 3 is a diagram showing a detailed structure of the AFIC 11. In the figure, the sensor control circuit (SC
C) 11 ₁ controls the operation of the entire AFIC 11 according to the control signal from the main CPU 10. Upon receiving the reset signal (AFRES) Sig1 from the main CPU 10, the sensor control circuit 11 ₁ supplies the reset signal to each block in the AFIC 11 to start the accumulation operation. During the accumulation operation, the AFEND signal Si
It holds g2 at "L" and outputs it to the main CPU 10.

The main CPU 10 sends the AFEND signal Sig.
2 is monitored at all times, and when the section of "L" exceeds the integration limit time, the AFEXT signal Sig2 'is output, and the sensor control circuit 11 ₁ outputs the AFEXT signal Si.
The accumulation operation is forcibly stopped according to g2 '.

Further, the sensor control circuit 11 ₁ outputs signals A to E to the sensor circuit (SC) 11 ₃ to switch the sensitivity mode, and at the same time, CLKSig5, DATA.
The sensor data D (I) is communicated to the main CPU 10 by the signal Sig4. Although the photodiode (PD) 11 ₂ and the sensor circuit 11 ₃ will be described later, when the sensor circuit 11 ₃ finishes the accumulation operation, the accumulation end signal T _S is sent to the latch circuit (LC) 11 ₄ and the OR generation circuit (ORC). Output to 11 ₅ .

The accumulation end signal T _S of the sensor circuit 11 ₃ which has completed the charge accumulation in the photoelectric conversion element array _first is input to the sensor control circuit 11 ₁ as an OR signal via the OR generation circuit 11 _5. . The sensor control circuit 11 ₁ outputs this as a T _OR signal. Further, the accumulation end signal T _S from the sensor circuit 11 ₃ which has completed the accumulation of the charges in the photoelectric conversion element array lasts, and the AND generation circuit (ANDC) 11 ₆
As a result, the AFEND signal Sig2 is output via the sensor control circuit 11 ₁ .

Then, the main CPU 10 sends AFEND
The low level "L" to high level "H" of the signal Sig2
Is detected to determine the end of integration of the AFIC 11, the time in the low level “L” section is measured, and the integration limit is determined.

Next, an accumulation end signal T _S from the sensor circuit 11 ₃ which has completed the first charge accumulation in the photoelectric conversion element.
Is input to the OR generation circuit 11 ₅ , the switch (SW) 11 ₇ is closed by the ORS signal. This switch 1
When ₁₇ is turned on, the counter (COT) 11 ₈ receives the clock pulse (C) of the clock generator (CG) 11 _9.
Start counting P).

Therefore, the latch circuit 11 _{4 of the} photodiode 11 ₂ which receives the strongest light in the photoelectric conversion element array.
, The counter output “0” is latched. And
In other photodiode 11 _2, as the charge accumulation time of light intensity incident is small is increased, difference in time accumulation end signal T _S is generated is generated. Therefore, the counter output corresponding to this time difference is latched in the latch circuit 11 ₄ .

Further, the OR generation circuit 11 ₅ validates only the storage end signal T _S from the sensor circuit 11 ₃ corresponding to the photodiode (not shown) corresponding to the photodiode located in the central range of the photoelectric conversion element array. . Here, since there is a possibility that the backlight of the main subject background on both sides of the photoelectric conversion element array may enter, the accumulation end signals T _S from a predetermined number of left and right sensor circuits 11 ₃ in this range are excluded, and the OR generation circuit 11 is excluded. You have not entered ₅ .

It is possible to obtain the luminance from the integration time by averaging the averaged values of the storage times of the predetermined elements in each element array by a plurality of integration operations. A detailed description of this accumulation time is omitted because it is described in Japanese Patent Application No. 6-271211, which is a prior application by the present applicant.

FIG. 4 shows a photometric sensor 21 for photometrically measuring the object field.
It is the figure which showed the example of a pattern. In this case, the pattern 21a in the central portion for photometry of the main subject and the pattern 2 in the peripheral portion for photometry of the luminance of the periphery of the main subject and the background
It consists of 1b.

Next, referring to the flowchart of FIG.
A series of processing operations of the camera will be described. First, step S
At 1, initial settings necessary for a series of camera operations are performed. Next, in step S2, half-depression of the shutter release button, that is, the ON state of the 1RSW 40 is detected. Here, when the ON of the 1RSW 40 is detected, the process proceeds to step S3, the integration start signal is given to the AFIC 11, and the integration is started.

Then, in step S4, the AFIC11
Since the integration completion signal is output from when the integration is completed,
Wait until the signal is output. Next, in step S5, AF information is fetched from the AFIC 11 upon completion of integration, the amount of focus shift is obtained, and the drive direction and drive amount of the focusing lens are obtained. If in focus, a focus signal is output. Further, spot photometry for converting the integration time into the brightness information of the AF area is performed. The conversion of the integration time into the luminance signal is described in Japanese Patent Application No. 6-271211, which is a prior application by the applicant of the present application, and therefore will be omitted. The spot photometric value obtained here is defined as BV _AF .

Next, in order to calculate the distance to the object from the driving amount of the focusing lens, the focus determination is made in step S6. Here, when the focusing lens is not in focus, the process proceeds to step S7, and the focusing lens is driven based on the driving direction and the driving amount of the focusing lens obtained in step S5. Then, it returns to step S2. On the other hand, if it is determined in step S6 that the subject is in focus, the process proceeds to step S8, and photometric calculation is performed to obtain an appropriate exposure value from the photometric value.

Then, in step S9, it is detected whether or not the release button is fully pressed, that is, whether or not the 2RSW 41 is turned on. If the release button has not been fully pressed, the process returns to step S2. If the release button is fully pressed, the process proceeds to step S10, and the TV value (shutter speed) obtained in step S8, AV
The exposure is performed based on the value. Then, step S11
At, the exposed film surface is wound up one frame.

Next, the processing operation for performing the photometric calculation will be described with reference to the flow charts of FIGS. First, in step S21, the luminance signal of the photometric sensor (170) is converted into a voltage signal by the IFIC 16, and the main C
The brightness value is obtained by A / D conversion in the PU 10. Here, the brightness value of the central portion 21a shown in FIG. 4 is BV _B , and the brightness value of the peripheral portion 21b is BV _C.

Next, in step S22, a center-weighted average photometric value (BV _AVE ) is calculated from the brightness values of the central portion 21a and the peripheral portion 21b obtained in step S21. The calculation formula is as follows.

[0076]

[Equation 1]

Subsequently, in step S23, the central portion 21a
And the brightness difference ΔBV between the peripheral portion 21b and the peripheral portion 21b are calculated by the following equation (2). ΔBV = | BV _B −BV _C | (2) Then, in step S24, in order to determine whether the luminance distribution of the main subject is backlit or forwardlit, BV _B and BV
V _c is compared. Here, in the case of BV _B ≦ BV _c , the main subject is darker than the peripheral portion, so it is determined that the subject is backlit,
It proceeds to step S25. On the other hand, in the case of BV _B > BV _c , the main subject is brighter than the peripheral portion, so it is determined that the subject is normal light and the process proceeds to step S26.

In step S25, the backlight flag is set to "1". Further, in step S26, the forward light flag is set to "1". Then, step S
At 27, the photographing magnification β of the main subject is calculated. The subject distance information is obtained by the AF process (step S5 in FIG. 3).

The focal length information is first converted from the count number of the ZMPI 34 into a zoom encoder value, and then from the zoom encoder value into focal length information. The photographing magnification is calculated by the following equation (3).

Shooting magnification (β) = focal length information (f) / subject distance information (L) (3) In step S28, the coefficient γ ₁ is used by using the shooting magnification β and the backlight and forward light flags. Is required. This coefficient γ
The method for obtaining ₁ is as follows. First, the following Table 1 is referred from β, the backlight, and the forward light flag.

[0081]

[Table 1]

When β matches, the corresponding data of γ ₁ is used, but β is 0.
If it is between 063 and 0.03, the data of each γ ₁ is proportionally distributed. That is, it is obtained by interpolation calculation. In the case of normal light, γ ₁ = 0.375,
In the case of backlight, γ ₁ = 1.5 is calculated (see FIG. 8). In this way, the data shown in Table 1 are calculated in an analog manner, and γ ₁ is obtained as a smooth value.

Next, in step S29, the coefficient γ ₂ is obtained from the zoom encoder value. This coefficient γ ₂ is
It is a coefficient that controls the effectiveness of the correction amount in consideration of the distance measurement accuracy, and is obtained by referring to Table 2 below.

[0084]

[Table 2]

When the zoom encoder is from "0 (that is, the zoom is on the wide side)" to "14 (that is, the zoom is near the standard)", the distance measuring accuracy is poor, so the correction coefficient γ ₂
Should be in the range of 0 to 1.

Next, in step S30, based on the information obtained in steps S27 to S29, the following (4)
The correction value is obtained according to the formula. ADJ = [Delta] BV * [gamma] ₁ * [gamma] ₂ (4) Then, in step S31, a process of applying an upper limit is performed so that the correction value does not become a large value. If ADJ is larger than 1.5 EV, step S
Proceed to 32, and 1.5 EV enters ADJ.

In step S33, it is determined whether the shooting mode is portrait. If it is the portrait mode, the process proceeds to step S34, and if it is another mode, the process proceeds to step S35.

In step S34, the BV value is calculated according to the following equation (5). _{BV = BV AVE -ADJ ... (5} ) Further, in step S35, BV according to the following equation (6)
The value is calculated.

BV = BV _AVE (6) Next, in step S36, the DX code read by the DXSW 60 is converted into an SV value (film sensitivity). Then, in step S37, the EV value is obtained from the BV value and the SV value. The calculation formula is as follows.

EV = BV + SV (7) Further, in step S38, the AV value and the TV value are obtained from the EV value according to the following equation (8).

EV = AV + TV (8) FIG. 9 is a diagram for explaining the effect of the same embodiment. As the conditions at the time of shooting, the photometric values of the central portion and the peripheral portion are BV _B = 15 and BV _c = 16.5, respectively, and the peripheral portion is brighter than the central portion (ΔBV = 1.5), so backlighting is performed. Has been determined. The focal length (zoom encoder = 30) at the time of shooting is f = 100 mm, and the distance to the subject is 3.0 m.

When β is calculated from the above information, β =
It becomes 0.03. Furthermore, from Tables 1 and 2 above, γ ₁ , γ
_{When 2} is obtained, γ ₁ = 0.5 and γ ₂ = 1.0. Also, the calculation of the center-weighted average photometric value BV _AVE is as follows.

[0093]

[Equation 2] Then, the proper exposure value when the shooting mode is the portrait mode, the _{BV = BV AVE -ΔBV · γ 1} · γ 2 = 15.7-1.5 · 0.5 · 1.0 = 14.95 .

When the photographing mode is other than the portrait mode, BV = 15.7 is the proper exposure value. In the above-described first embodiment, the portrait mode is a shooting mode that is premised on shooting a person. Therefore, although β and γ _{1 in} Table 1 above are set according to the photographing situation of the person, these data tables may be changed according to the object to be photographed.

Next, a second embodiment of the present invention will be described. The second embodiment differs from the above-described first embodiment in the photometric processing operation. FIG. 10 is a flowchart for explaining the processing operation for performing the photometric calculation according to the second embodiment. It should be noted that steps S41 to S50 in the flowchart of FIG. 10 are processes for performing a limiter on the corrected exposure value with the spot photometric value, which is the same as steps S21 to S30 of the flowchart of FIG. Is omitted.

At step 51, the BV value is obtained from ADJ and BV _AVE obtained at step S50. Next, in step S52, it is determined whether BV is smaller than BV _{AF of the} spot portion. BV is BV
If it is smaller than _{AF, the} process proceeds to step S53, and if not, the process proceeds to step S54.

At step S53, the photometric value BV is added to the BV value.
_AF enters. Subsequent steps S54 to S56 are the same as steps S36 to S38 in FIG. 7, and therefore description thereof will be omitted.

According to the above embodiment of the present invention, the following constitution can be obtained. (1) At least a photometric unit that outputs luminance signals in the center and the periphery of the object scene, a determination unit that obtains the luminance distribution of the object object and outputs luminance distribution information, and a measurement unit that outputs distance information to the main subject. Distance means, zoom means for changing the focal length of the taking lens and outputting focal length information, the photometric value, luminance difference, luminance distribution information, subject distance information, and focal length information are input, The center-weighted average photometry value is obtained from the above photometry values, the photographing magnification of the subject is obtained from the subject distance information and the focal length information, and exposure correction information is calculated from this photographing magnification and luminance distribution information. An exposure determination device for a camera, comprising: an arithmetic unit that outputs an appropriate exposure value based on a weighted average photometric value.

(2) At least the photometric means for outputting the brightness signals in the center and the periphery of the field, the judgment means for obtaining the brightness distribution of the field and outputting the brightness distribution information, and the distance information to the main subject are displayed. Distance measuring means for outputting, zoom means for changing focal length of the taking lens and outputting focal length information, photographing mode setting means for setting photographing mode and outputting mode information, the photometric value, and brightness difference , Brightness distribution information, subject distance information, focal length information, and shooting mode are input, the center-weighted average photometric value is obtained from the above photometric values, and the subject's shooting magnification is determined from the subject distance information and the focal length information. Then, the exposure correction information is calculated from the shooting magnification and the brightness distribution information, and when the shooting mode matches at least one predetermined shooting mode, the exposure correction information and the center-weighted average photometry value are calculated. An exposure determining device for a camera, comprising: a calculating unit that calculates and outputs an exposure value.

(3) At least the photometric means for outputting the luminance signal of the center and the periphery of the field, the determination means for obtaining the brightness distribution of the field and outputting the brightness distribution information, and the distance information to the main subject are displayed. A distance measuring means for outputting, a zoom means for changing the focal length of the taking lens and outputting focal length information, and a spot metering means for metering a narrow range of the object field,
The photometric value, the brightness difference, the brightness distribution information, the subject distance information, and the focal length information are input, the center-weighted average photometric value is obtained from the above photometric value, and the subject distance information and the focal length information are used to determine the subject. Obtain the shooting magnification, calculate the exposure correction information from this shooting magnification and brightness distribution information, and when the calculation result based on this exposure correction information and the center-weighted average photometry value is larger than the spot photometry value, An exposure determining apparatus for a camera, comprising: an arithmetic unit that outputs a limited exposure value.

(4) At least the photometric means for outputting the luminance signal of the center and the periphery of the field, the determination means for obtaining the brightness distribution of the field and outputting the brightness distribution information, and the distance information to the main subject are displayed. Distance measuring means for outputting, zoom means for changing focal length of the taking lens and outputting focal length information, the photometric value, luminance difference, luminance distribution information, subject distance information, and focal length information. Input, obtain the center-weighted average photometric value from the photometric value, obtain the photographing magnification of the subject from the subject distance information and the focal length information, obtain the exposure correction coefficient from the photographing magnification and the luminance distribution information, and obtain the luminance difference and this An exposure determining device for a camera, comprising: an arithmetic unit that outputs an appropriate exposure value calculated based on the exposure correction information obtained by a coefficient and the center-weighted average photometric value.

(5) At least the photometric means for outputting the luminance signal of the center and the periphery of the field, the determining means for obtaining the brightness distribution of the field and outputting the brightness distribution information, and the distance information to the main subject are displayed. Distance measuring means for outputting, zoom means for changing focal length of the taking lens and outputting focal length information, the photometric value, luminance difference, luminance distribution information, subject distance information, and focal length information. The center-weighted average photometry value is obtained from the above photometry values, the photographing magnification of the subject is obtained from the subject distance information and the focal length information, and the first exposure correction coefficient is obtained from the photographing magnification and the luminance distribution information to obtain the focal length. Calculation of obtaining a second exposure correction coefficient from the information and outputting a proper exposure value calculated based on the exposure correction information obtained from the brightness difference, the first coefficient and the second coefficient, and the center-weighted average photometry value. Equipped with means An exposure determination device for a camera characterized by the above.

[0103]

As described above, according to the present invention, the subject distance,
Since it is possible to determine the appropriate exposure compensation amount by judging from the focal length and brightness difference, when the photographer selects the photography mode for the main subject, the exposure compensation is better, and a simple operation makes it more appropriate. You can get exposure. For example, it is possible to prepare a data table corresponding to each of a child mode for taking a picture of a child, an object mode for taking an object larger than a person, and a macro mode for taking a small object such as an insect.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention and is a block diagram showing an outline of an exposure determining device of a camera.

FIG. 2 is a circuit configuration diagram showing details of an exposure determination device of a camera.

3 is a block diagram showing a detailed configuration of the AFIC 11 of FIG.

FIG. 4 is a diagram showing an example of a pattern of a photometric sensor 21 that measures a field.

FIG. 5 is a flowchart illustrating a series of processing operations of the camera.

FIG. 6 is a flowchart illustrating a processing operation for performing photometric calculation.

FIG. 7 is a flowchart illustrating a processing operation for performing photometric calculation.

FIG. 8 is a characteristic diagram showing a relationship between a photographing magnification β and a coefficient γ ₁ .

FIG. 9 is a diagram for explaining the effect of the first embodiment.

FIG. 10 is a flowchart illustrating a processing operation for performing photometric calculation according to the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photometric unit, 2 ... Backlight determination unit, 2 ... Calculation unit, 4 ... Distance measuring unit, 5 ... Zoom unit, 6 ... Shooting mode setting unit, 7 ... Exposure control unit, 10 ... Main CPU, 11 ... AFIC, 12 … E
EPROM, 13 ... Liquid crystal display panel, 15 ... Strobe unit, 16 ... Interface IC (IFIC), 1
7 ... Remote control transmission unit, 21 ... Photometric sensor, 21a
... central part, 21b ... peripheral part, 22, 37 ... motor driver, 24 ... sequence motor (M1), 25 ... LD motor (M2), 26 ... ZM motor (M3), 31 ... shutter interrupt photo interrupter (SCPI) ), 32
... Lens photo interrupter (LDPI), 33 ... Zooming photo reflector (ZMPR), 34 ... Zooming photo interrupter (ZMPI), 35 ... Aperture photo interrupter (AVPI), 36 ... Stepping motor (AV motor; M4), 40 ... First release switch (1RSW), 41 ... Second release switch (2RSW), 42 ... Zoom up switch (Z
USW), 43 ... Zoom down switch (ZDSW),
52 ... AV priority switch (AVSW), 60 ... DX switch (DXSW).

Claims (3)

[Claims] 1. An exposure determining device for a camera, comprising at least a central part of a photographing screen and a photometric means for measuring the entire photographing screen excluding the central part, wherein a main subject is output based on an output of the photometric means. Determines whether or not the backlight is in the backlit state, calculates the first photometric value, calculates the photographing magnification of the main subject according to the focal length information of the photographing lens and the main subject distance information, Outputting means for outputting a correction coefficient for correcting the first photometric value based on the photographing magnification and the backlit state, and a value obtained by calculating the first photometric value and the correction coefficient
And a second calculation means for outputting as a photometric value of the exposure determination device of the camera. 2. A second output means for outputting a new correction coefficient different from the correction coefficient based on the focal length information of the taking lens, wherein the second calculation means has the first photometric value. The exposure determination device for a camera according to claim 1, wherein a value obtained by calculating the correction coefficient and the new correction coefficient is output as a second photometric value. 3. The second calculation means, when the second photometric value exceeds the photometric value of the central portion of the photographing screen,
The exposure determination device for a camera according to claim 1, wherein the photometric value of the central portion of the photographing screen is output as a second photometric value.