JPH0792371A - Preliminary irradiation device for detecting focus - Google Patents

Abstract

PURPOSE:To obtain an excellent contrast output regardless of a subject distance by freely varying the emitted light quantity of preliminary irradiation based on the reflection luminance of an object, to prevent a remarkable release time lag in consecutive light emission and further, to execute light emission at a desired guide number regardless of the charging voltage of a main capacitor. CONSTITUTION:The object is preliminarily irradiated with a stroboscope unit 6 at the time of measuring and a CPU 1 controls the light emission of the stroboscope unit 6 in its preliminary irradiation to set the emitted light quantity, to discriminate the intensity of the light of the object and to detect the charging voltage of the stroboscope unit 6. Thus, the emitted light quantity at the time of measuring is set in accordance with the light intensity and the charging voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection preliminary irradiation device for irradiating a subject with auxiliary light when focus detection is performed by an automatic focus detection device in a photographing device such as a camera.

[0002]

2. Description of the Related Art Conventionally, a focus detection device used in a photographing device such as a camera adopts a passive AF method in which a subject light incident through a photographing lens is divided into two images and the focus is adjusted based on the phase shift. Has been done. An integral type light receiving element is mainly used in this focus detection device, and when light is incident on the integral type light receiving element, charges are accumulated and integrated accordingly, and a predetermined amount is determined according to the integrated charges. Is output. Further, in this integral type light receiving element, the product of the illuminance or the luminance and the integral time is made constant so as to keep the output constant.

Further, for example, JP-A-59-195605.
The publication discloses a technique relating to a focus detection device that detects low luminance of an object using an integral type light receiving element and controls the light emitting operation of a light emitting section.

When photographing with such an image pickup device,
Since focus adjustment is difficult when the subject is dark, auxiliary light is emitted toward the subject by the focus detection preliminary irradiation device. In such a focus detection preliminary irradiation device,
Since the amount of light emission is determined mainly by the amount of charge accumulated in the capacitor, the amount of light emission could be controlled freely by appropriately setting the capacitance of the capacitor.

[0005]

However, in the above-described technique, since the light is always emitted with the same guide number, the desired contrast cannot be obtained due to the high and low reflected brightness of the subject. Further, in the case of continuous light emission, it is necessary to supplement the electric charge of the main capacitor between light emission, which causes a problem that the release time lag increases.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to change the emitted light amount of preliminary irradiation on the basis of the reflected brightness of a subject and to obtain a good contrast output regardless of the subject distance. To obtain and prevent a significant release time lag when emitting light continuously,
Also, the light is emitted at a desired guide number regardless of the charging voltage of the main capacitor.

[0007]

In order to achieve the above object, in the focus detection pre-irradiation device of the present invention, a flash light emitting means for pre-irradiating an object at the time of measurement, and light emission during pre-irradiation of the flash light emitting means. A light emission control means for controlling the light emission light quantity setting means for setting the light emission light quantity of the flash light emitting means,
A light intensity determination means for determining the light intensity of the light of the subject,
And a detection unit for detecting the charging voltage of the flash light emitting unit, wherein the amount of light emitted during measurement is variable in response to the output of the light intensity determination unit and the output of the charging voltage detection unit. Characterize.

[0008]

That is, in the focus detection pre-irradiation device of the present invention, the flash light emitting means pre-irradiates the subject at the time of measurement, and the light emission control means controls the light emission during the pre-irradiation of the flash light emitting means to set the light emission amount setting means. Sets the amount of light emitted from the flash emitting means, the light intensity determining means determines the light intensity of the light of the subject, and the detecting means detects the charging voltage of the flash emitting means. Then, in response to the output of the light intensity determining means and the output of the charging voltage detecting means, the amount of emitted light at the time of measurement is made variable.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a control system of a focus detection preliminary irradiation device according to an embodiment of the present invention. In FIG. 1, the CPU 1 sequentially executes programs stored in advance in an internal ROM (not shown) to control peripheral integrated circuits (ICs) and the like. Then, the autofocus (AF) IC2
The TTL phase difference detection method is adopted for the automatic focus adjustment by. Then, the subject light passes through the taking lens 28, the condenser lens 26 and the separator lens 25L,
AF AF system 27 including
2 arranged on the upper surface of the photosensor arrays 24L, 24
Upon reaching R, the AFIC2 performs processing such as light amount integration and quantization, which will be described later, and the distance measurement information is transmitted from the AFIC2 to C.
It is transferred to PU1.

Further, the photosensor array 24L,
If there is a variation in the characteristics of each element of 24R, accurate distance measurement information cannot be obtained as it is. Therefore, in this embodiment, information regarding the variation of the photosensor arrays 24L and 24R is previously stored in the EEPROM 3 which is a nonvolatile recording element. The correction calculation of the distance measurement information obtained from the AFIC 2 is stored in the CPU 1 and stored. That is, this E
Various adjustment values such as mechanical variations and electrical characteristic variations of various elements are stored in the EPROM 3 in advance, and various calculations can be performed by sending these adjustment values to the CPU 1 as necessary. In this embodiment, the data transfer between the CPU 1, the AFIC 2 and the EEPROM 3 is performed by serial communication.

Then, the data bag 5 imprints the date on the film based on the control signal output from the CPU 1. The light quantity of the imprinting lamp of the data bag 5 changes stepwise depending on the film ISO sensitivity. Furthermore, interface (IF) IC7
Performs 4-bit parallel communication with the CPU 1 to measure subject brightness, camera internal temperature, waveform shaping of output signals such as photo interrupters, motor constant voltage drive control, temperature stability, temperature proportional voltage, and other various constants. It performs voltage generation, battery remaining amount check, infrared remote control reception, control of motor driver ICs 8 and 9, control of various LEDs, power supply voltage check, booster circuit control, and the like.

Then, the silicon photodiode (SP
D) 23 measures the subject brightness. This SPD23
The light-receiving surface of is divided into two parts, the central part of the screen and its peripheral part. There are two parts, the spot metering which measures the light only in a part of the center of the screen and the average metering which uses the whole screen.
Do street photometry. When the SPD 23 outputs a current according to the subject brightness to the IFIC 7, the IFIC 7
Then, the output from this SPD23 is converted into a voltage and CP
Transfer to U1. Then, the CPU 1 performs the exposure calculation, the judgment of the backlight, and the like on the basis of the voltage information.

Further, when the circuit built in the IFIC 7 outputs a voltage proportional to the absolute temperature, the signal is A / D converted by the CPU 1 and output as a temperature measurement value of the temperature inside the camera. The value is used in mechanical members whose state changes with temperature, correction of electric signals, and the like. Further, in the waveform shaping of the photo interrupter or the like, the photocurrent of the output of the photo interrupter or the photo reflector is compared with the reference current, and output as a rectangular wave from the IFIC 7.
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 the communication with the CPU 1. Further, the battery remaining amount is checked by dividing the voltage across the battery when a low resistance is connected to both ends of the battery (not shown) and passing a current inside the IFIC 7 to obtain C
It is output to PU1 and A / D converted in this CPU1 to obtain an A / D value.

In the reception of the infrared light remote controller, modulated infrared light is emitted from the light emitting LED 21 of the remote controller transmitting unit 20, and the infrared light is received by the light receiving silicon photodiode 22. Done in. The output signal of the silicon photodiode 22 is IFIC.
After processing such as waveform shaping is performed inside 7, the data is transferred to the CPU 1. In addition, IFIC7 is used for low-voltage monitoring of the power supply voltage.
Is provided with a dedicated terminal for that purpose, and if the power supply voltage input to the dedicated terminal falls below a specified value, the IFI
The reset signal is output from C7 to CPU1, and the CPU
Runaway of 1 is prevented in advance. The control of the booster circuit is to activate the booster circuit when the power supply voltage drops below a predetermined value.

Further, the IFIC 7 is provided with an LED 1 for displaying in the finder such as the end of AF distance measurement and the warning of strobe light emission.
9 or LE used for photo interrupter etc.
D is connected, and the on / off of these LEDs and the control of the amount of emitted light are controlled by the CPU 1, the EEPROM 3, and the IFI.
Communication is performed between C7 and IFIC7 directly performs. The IFIC 7 also controls the constant voltage of the motor. Further, the motor driver IC 8 includes a shutter charge (SC) motor 12 for film feeding and shutter charging, a lens drive (LD) motor 13 for focus adjustment,
It drives the three motors of the lens frame zooming (ZM) motor 14, the booster circuit, the self-timer operation display LED, and the like. The IFIC 7 receives a signal from the CPU 1 for control of these operations, such as "which device is driven", "whether the motor is normally or reversely rotated", or "braking", and the like. This is performed by the IFIC 7 controlling the motor driver IC 8.

Whether the SC motor 12 is in the shutter charge, film winding, or rewinding state is detected by the SCPI 15 using the photo interrupter and the clutch lever, and the information is stored in the CPU.
1 is transferred. The amount of lens extension is detected by the LDPI 16 attached to the LD motor 13, and its output is waveform-shaped by the IFIC 7 and then transferred to the CPU 1. Furthermore, the amount of zooming out of the lens frame is Z
It is detected by MPI18 and ZMPR17. Then, when the lens frame is between the TELE end and the WIDE end, the ZMPR 17 is configured to pick up the reflection of the silver seal attached to the lens frame. The output of this ZMPR 17 is input to the CPU 1 to detect the TELE end and the WIDE end.

Further, the ZMPI 18 is attached to the ZM motor 14, the output of which is waveform-shaped by the IFIC 7 and then input to the CPU 1 to detect the amount of zooming from the TELE end or the WIDE end. Then, the motor driver IC 9 drives the AV motor 10 which is a stepping motor for driving the aperture adjusting unit by the control signal from the CPU 1, and the AVPI 11 waveform-shapes the output by the IFIC 7 and outputs the output to the CPU 1 to determine the aperture open position. Detect. Further, the liquid crystal display panel 4 displays the number of film frames, the photographing mode, the strobe mode, the aperture value, the remaining battery level, and the like according to the signal sent from the CPU 1. Then, the strobe circuit 6 gives a necessary brightness to the subject by causing the arc tube to emit light when the brightness of the subject is insufficient at the time of shooting or AF distance measurement. Based on a signal from the CPU 1, the IFI
Controlled by C7.

Then, the first release switch R1
The SW is turned on when the release button is half pressed, and the distance measuring operation is performed. Second release switch R2
The SW is turned on when the release button is fully pressed, and the photographing operation is performed based on various measured values. Zoom up switch ZUSW and zoom down switch ZD
SW is a switch for zooming the lens frame, and when ZUSW is turned on, zooming is performed in the long focus direction, and when ZDSW is turned on, zooming is performed in the short focus direction.

When the self-switch SELFSW is turned on, the self-timer photographing mode or the remote control standby state is set. In this state, if the R2SW is turned on, self-timer shooting is performed, and if a remote control transmitter 20 performs a shooting operation, shooting by the remote control is performed. When the spot switch SPOTSW is turned on, the "spot photometry mode" is set in which photometry is performed only in a part of the center of the photographing screen. This is photometry by an AF sensor described later. Incidentally, S
In normal photometry with POTSW turned off, evaluation photometry is performed by the photometric SPD 13. Furthermore, PCT1SW to PCT
The 4SW and the program switch PSW are changeover switches for the "program shooting mode", and the photographer selects a mode according to the shooting conditions. When the PCT1SW is turned on, the "portrait mode" is set, and the aperture and shutter speed are determined so that the depth of field becomes shallow within the proper exposure range.

When the PCT2SW is turned on, the "night view mode" is set, and the value is set to be one step lower than the value of the proper exposure at the time of normal photographing. When the PCT3SW is turned on, the "landscape mode" is set, and the aperture and shutter speed values are determined so that the depth of field is as deep as possible within the proper exposure range. Further, when the PCT4SW is turned on, the "macro mode" is set, which is used during close-up photography. still,
Two or more of these PCT1SW to PCT4SW cannot be selected at the same time.

Further, PSW is a normal "program shooting mode" changeover switch, and by pressing the PSW, the PCT1SW to PCT4SW are reset and the AV priority program mode described later is reset.
Further, when the AV priority switch AVSW is turned on, the shooting mode becomes the "AV priority program mode". In this mode, the photographer determines the AV value, and the shutter speed is determined by a program according to the AV value. In this mode, the PCT2SW and PCT4SW have no function as described above and serve as AV value setting switches. Furthermore, PCT2
SW is a switch for increasing the AV value, and PCT4SW is A
It is a switch that reduces the V value.

Further, the strobe switch STSW is a switch for changing the strobe emission mode, and is usually "automatic emission mode (AUTO)" or "red-eye reduction automatic emission mode (A).
UTO-S) "," Forced flash mode (FILL-I)
N) ”and“ strobe off mode (OFF) ”. The panorama switch (PANSW) is a switch for detecting whether the shooting state is panoramic shooting or normal shooting, and is turned on during panoramic shooting. When the shooting mode is panorama, photometric correction calculation and the like are performed. This is because at the time of panoramic photography, a part of the upper and lower parts of the photographing screen is masked, and accordingly, a part of the photometric sensor is also masked, so that accurate photometry cannot be performed.

Further, the back cover switch BKSW is a switch for detecting the state of the back cover, and the closed state of the back cover is turned off. When the state of the BKSW changes from on to off, loading of the film is started. The shutter charge switch SCSW is a switch for detecting shutter charge. Further, the mirror-up switch MUSW is a switch for detecting the mirror-up and is turned on by the mirror-up. And DX
The switch DXSW is a switch for reading the DX code indicating the film sensitivity printed on the film cartridge and for detecting the presence or absence of film loading, and is composed of five switch groups (not shown).

Next, FIG. 2 is a diagram showing a detailed structure of the AFIC 12. In the figure, the sensor control circuit SCC
Controls the operation of the entire AFIC 2 according to the control signal from the CPU 1. When the sensor control circuit SCC receives the reset signal AFRES from the CPU 1, it supplies the reset signal to each block in the AFIC 2 to start the accumulation operation. Then, during the accumulation operation, the signal AFEND is held at the low level "L" and output to the CPU 1.

The CPU 1 constantly monitors the signal AFEND, outputs the signal AFEXT when the low level "L" section exceeds the integration limit time, and the sensor control circuit SCC compulsorily responds to the signal AFEXT. Stop the accumulation operation. Further, the sensor control circuit SCC outputs signals A to E to the sensor circuit SC to switch the sensitivity mode, and communicates the sensor data D (I) to the CPU 1 by the signals CLK and DATA.
Although the photodiode PD and the sensor circuit SC will be described later, when the sensor circuit SC ends the accumulation operation, the accumulation end signal TS is sent to the latch circuit LC and the OR generation circuit OR.
Output to C.

The accumulation end signal TS of the sensor circuit SC which has completed the charge accumulation first in the photoelectric conversion element array is converted into a signal OR via the OR generation circuit ORC and the sensor control circuit S.
The signal is input to CC, and the sensor control circuit SCC outputs this as a signal TOR (see TOR in FIG. 4F). Further, the accumulation termination signal TS from the sensor circuit SC which has completed the accumulation of the charge in the photoelectric conversion element array is the AND generation circuit A.
The signal AFE is sent by the NDC via the sensor control circuit SCC.
The ND is output (see FIG. 4 (e)). In the explanation below,
The L section of the signal AFEND shown in FIG. 4 (e) is referred to as integration time TE.

Then, the CPU 1 detects the high level "H" from the low level "L" of the signal AFEND to determine the end of integration of the AF sensor, measures the time of the low level "L" section, and determines the integration limit. I do. Further, the clock pulse generator CG generates a clock pulse CP for digitizing the charge storage time TS into the sensor data D (I), and in FIG. And the cycle is
The clock pulse CP increasing as shown in (g) is generated. This change in the period has a relation that the charge storage time TS is almost inversely proportional to the light intensity incident on the photodiode PD.

Then, when the accumulation end signal TS from the sensor circuit SC which has completed the first charge accumulation in the photoelectric conversion element is input to the OR generation circuit ORC, the switch SW is closed by the signal ORS. When the switch SW is turned on, the counter COT starts counting the clock pulses CP of the clock generator CG.

Therefore, the counter output 0 is latched in the latch circuit LC of the photodiode PD which receives the strongest light in the photoelectric conversion element array. Then, in other photodiodes, the charge accumulation time becomes longer as the incident light intensity is smaller, and a time difference occurs until the accumulation end signal TS is generated. Therefore, the counter outputs corresponding to this time difference are latched in the latch circuits LC. To be done.

Further, the OR generation circuit ORC validates only the storage end signal TS from the sensor circuit SC which is not shown but corresponds 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 TS from a predetermined number of left and right sensor circuits SC in this range are excluded and input to the OR generation circuit ORC. Not not.

Next, FIG. 3 is a diagram showing a more detailed structure of the sensor circuit SC in the AFIC 2. In the figure, the sensor circuit SC switches the operation mode according to the subject brightness, and is set to the "high sensitivity mode" when the subject has low brightness and to the "low sensitivity mode" when the subject has high brightness.

Then, first, the sensor control circuit SCC is set to the "high sensitivity mode", so that the signals A to E are output to the sensor circuit SC so that AS1 is off, AS2 is on and AS3 is on.
Set to ON, AS4 OFF, AS5 ON. In this state, both ends of the storage capacitor CI are short-circuited, and are fixed and reset to the potential V2 by the operation of the operational amplifier AP. Further, the cathode of the photodiode PD is connected to the fixed potential Vr, and a photocurrent corresponding to the amount of received light is generated. Then, when the AS3 is turned from ON to OFF, the storage operation is started, and a photocurrent corresponding to the amount of light received by the photodiode PD flows into the storage capacitor CI,
A charge corresponding to this is accumulated.

At the same time, the output P2 of the operational amplifier AP
The electric potential of is lowered from the reset electric potential V1 with an inclination according to the amount of received light (see FIG. 4 (c)). The output P2 of the operational amplifier AP is connected to the inverting input terminal of the comparator CP whose non-inverting input terminal is fixed to the predetermined potential V3. When the output P2 of the operational amplifier AP exceeds the potential V3, the output of the comparator CP is output. P3 is inverted from the high level "H" to the low level "L", and the accumulation end signal T is passed through AS4.
Output S. The first signal of the accumulation end signal TS is output as the signal TOR via the OR generation circuit ORC and the sensor control circuit SCC described above (see FIG. 4 (f)).

Further, the last signal of the accumulation end signal TS is output as the signal AFEND via the AND generation circuit ANDC and the sensor control circuit SCC described above (FIG. 4 (e)). If the shortest storage time in the photoelectric conversion element array is shorter than the predetermined time, the operation is switched to the "low sensitivity mode" and the storage operation is performed again (see FIGS. 5 (h) to 5 (m)). In this "low sensitivity mode", the sensor control circuit S
Signals A to E are set by CC, and AS1 is turned on, AS2 is turned off, AS3 is turned off, AS4 is turned off, and AS5 is turned on. In the low sensitivity mode, the operational amplifier AP operates as a comparator whose non-inverting input terminal is fixed to V2. The inverting input terminal P1 of the comparator AP is fixed to the potential V1 and resets the junction capacitance CJ.

Then, the signal A is inverted and AS1 is turned off, and the junction capacitance CJ of the photodiode PD is discharged by a photocurrent corresponding to the amount of received light received by the photodiode PD, so that the inverting input terminal P1 of the comparator AP is discharged. The potential rises from the reset potential V1 with a slope according to the amount of received light. Further, the clock generator CG and the counter COT are reset when the accumulation starts, and the comparator AP
When the potential of the inverting input terminal P1 of the comparator AP exceeds the potential V2, the output P2 of the comparator AP is inverted from the high level "H" to the low level "L", and the accumulation end signal TS is output via AS5.

Further, as in the high sensitivity mode, the switch SW is turned on via the OR generation circuit ORC in response to the accumulation end signal TS from the sensor circuit SC whose accumulation has been completed earliest, and the signal TOR is outputted from the sensor control circuit SCC. Is output. Then, in accordance with the accumulation end signal TS from the sensor circuit SC whose accumulation has been completed latest, the AND generation circuit ANDC
The signal AFEND is output from the sensor control circuit SCC via. Furthermore, letting To be the storage time corresponding to the photodiode PD having the largest incident light amount in the photoelectric conversion element array, that is, the storage time corresponding to the shortest, that is, the signal TOR described above, is To. Counter output D (I) latched in the latch circuit LC corresponding to the charge accumulation time T (I) corresponding to the diode PD
And have the following relationship.

[0037]

[Equation 1] This equation is modified to digitize the counter output D
(I) is expressed by the following equation.

[0038]

[Equation 2]

Since the charge storage time T (I) is proportional to the amount of light incident on each photodiode, a subject image signal can be obtained by reading the above D (I). Then, the counter COT stops counting after counting 8 bits. Therefore, the output of the element in which the intensity of light incident on the photodiode PD is weak and the charge storage time T (I) is longer than a predetermined time determined by To is fixed at "255".

Next, FIG. 6 is a diagram showing a detailed structure of the strobe circuit 6. In the figure, the power source E is a DC / voltage that boosts the power source voltage until the strobe can emit light.
The DC converter 52 is connected in parallel, and this DC
The output of the / DC converter 52 has a main capacitor M
A main capacitor voltage measuring circuit 53 for measuring the voltage charged in C is connected. And the above DC / DC
The output of the converter 52 is connected to a trigger circuit 54 that applies a trigger for light emission to a Xe (xenon) tube 57, and is further connected to a main capacitor MC that stores light emission energy via a diode D1. The power source E is connected in series with a Xe tube 57 that consumes the energy of the main capacitor MC connected to the cathode of the diode D1 and emits light, and a light emission amount control circuit 55 that controls the amount of light emitted from the Xe tube 57. A power supply control circuit 56 for controlling the supply of the power E is connected to the emission light amount control circuit 55. The CPU 1 controls the DC / DC converter 52, the main capacitor voltage measuring circuit 53, the trigger circuit 54, the emitted light amount control circuit 55, and the power supply control circuit 56 by the IFIC 7.
Is controlled as an interface.

Next, FIG. 7 is a diagram showing a configuration in which the strobe circuit 6 is further embodied. As shown in the figure, in the main capacitor voltage measuring circuit 53, resistors R1 and R2 are connected in series, and a capacitor C is connected to the resistor R2.
1 are connected in parallel, and the connection point of the resistors R1 and R2 is connected to the VST terminal of the CPU 1. Then, this main capacitor voltage measuring circuit 53
Activates the DC / DC converter 52, and the resistor R1,
The voltage across the resistor R2 generated by the voltage division ratio of R2
The voltage of the main capacitor MC is measured by monitoring at 1 and multiplying the voltage of the main capacitor MC by the voltage division ratio of the resistor. The capacitor C1 is for smoothing the measured voltage.

In the trigger circuit 54, a resistor R3 and a thyristor D2 are connected in series, and a capacitor C2 and a trigger coil T1 b are connected between the anode and GND of the thyristor D2.
-A is connected in series, similarly the capacitor C3 and the resistor R4 are connected in series between the anode of the thyristor D2 and GND, and the secondary winding T1-c of the trigger coil T1 is connected to the outer wall of the Xe tube 7, The connection point between the capacitor C3 and the resistor R4 is connected to the cathode of the Xe tube 57, and the thyristor D2
The gate of is connected to the STON terminal of the CPU 11. The trigger circuit 54 is also used as a voltage doubler circuit for applying a trigger to the Xe tube 57 and at the same time applying a negative main capacitor voltage to the cathode of the Xe tube 57 to facilitate the emission of light from the Xe tube 57. ing.

Now, the operation of the trigger circuit 54 will be described in more detail. First, the DC / DC converter 52
Is started for a certain period of time, and the output charge current is passed through the resistors R3 to the capacitors C2 and C3 to perform charging, the charged charges are at a high level "H" at the gate of the thyristor D2.
By inputting a signal, the anode of thyristor D2 =
Conduction between the cathodes, from the capacitor C2 to the thyristor D
2, between the primary side a-b of the trigger coil T1, the capacitor C
When a current flows to the secondary coil 2 and a current flows to the primary side of the trigger coil T1, an interlinking magnetic flux with respect to the secondary coil of the primary coil is generated in the trigger coil T1. High voltage is induced.

Further, from the capacitor C3 to the thyristor D
2, a current flows through the resistor R4 and the capacitor C3, and the sannode voltage of the thyristor D2 instantly becomes 0 V from the initial light emission possible voltage value of the Xe tube 57. Therefore, the capacitor C3
The voltage on the anode side of the Xe tube 57 becomes 0V to a negative Xe tube light emission voltage, and the diode D3 causes Xe tube to emit Xe.
The cathode voltage of the tube 57 is held, and the voltage doubler circuit is driven in which the double Xe tube light emission voltage is applied to both ends of the Xe tube 57.

The emitted light amount control circuit 55 is composed of a Xe tube 57.
A diode D3 and an insulated gate bipolar transistor IGBT1 are connected in series between
The Zener diode D4 is connected in parallel between the gate and the emitter of 1, the collector and the emitter of the transistor Tr1 are connected in parallel, the cathode of the Zener diode D4 is connected to the power supply control circuit 56, and the transistor Tr is connected.
The base of No. 1 is connected to the STOFF terminal of the CPU 1 via the resistor R6.

In the emitted light quantity control circuit 55, the insulated gate bipolar transistor I is connected to the zener diode D4 by the voltage supplied from the power supply control circuit 56.
A gate voltage of the GBT1 is created and the IGBT1 is turned on. At this time, the light emission current flows from the Xe tube 57 to the diode D3 and the IGBT 1 due to the activation of the trigger circuit 54. Then, when a light emission stop signal is input from the CPU1 to the STOFF terminal to the transistor Tr1 via the resistor R6, the transistor Tr1 operates, the gate charge of the IGBT1 is discharged, the IGBT1 is turned off, and the light emission current is stopped.

In the power supply control circuit 56, the transistor Tr2 and the resistor R5 are connected in series, and the resistors R7 and R5 are connected.
8 and a transistor Tr3 are connected in series, and a resistor R9
Is connected to the G-ON terminal of the CPU 11. Then, the power supply control circuit 56 is
When the ON signal is input from the G-ON terminal of the G-ON terminal and the transistor Tr3 is activated and the transistor Tr2 is activated, the charge of the main capacitor MC is supplied to the emission light amount control circuit 55, and when the OFF signal is input, the emission light amount control circuit. The supply of charges to 55 is stopped. In order to measure the voltage of the main capacitor MC, it is executed by calling a charging voltage check subroutine, and the light emission possible voltage value is stored in advance in a storage area (not shown) in the CPU 1. The details of this will be described later.

Next, the sequence of the subroutine "first release" executed by the camera to which the present invention is applied will be described in detail with reference to the flowchart of FIG. First, set G-ON to high level "H" (step S
101), a subroutine "charging voltage check" which will be described later
Is executed (step S102). Subsequently, a later-described subroutine "AF distance measurement" is executed (step S10).
3), it is determined whether or not the AF distance measurement result is undetectable by referring to the undetectable flag (step S104).

If the AF distance measurement result is detected, it is determined whether or not the auxiliary light is emitted during the AF distance measurement by referring to the auxiliary light flag (step S105). When the auxiliary light is off, the focus flag is referred to determine whether or not the focus is achieved (step S107). If the focus is achieved, the focus is displayed by the LED display in the viewfinder or the sound of the buzzer. After the G-ON is set to the low level "L" (step S108) (step S112), the process returns.

On the other hand, if the object is out of focus in step S107, a subroutine "lens drive" described later is executed,
The lens is driven based on the result of the AF distance measurement (step S109). Then, the focus flag is referred to determine whether or not the focus is achieved (step S110). If the focus is achieved, the focus display is performed (step S108). If the focus is not achieved, the auxiliary light flag is referenced. If the auxiliary light is off, the process branches to step S103. If the auxiliary light is on, the process branches to step S102 to check the charging voltage.
When the auxiliary light is emitted again, the emission time is corrected by the charging voltage, the process returns to step S103, and the subroutine "AF distance measurement" is executed again.

If it cannot be detected in step S104, non-focus display is performed by the LED in the finder in step S111, G-ON is set to low level "L" (step S112), and the process returns.

If the auxiliary light is emitted during AF distance measurement, that is, if the auxiliary light is on in step S105, the light amount over flag and the light amount under flag are referred to. If the amount of light is over or under, the distance measurement result is not reliable, so the process returns to step S103, the amount of auxiliary light is changed, and AF is performed again.
Perform distance measurement. If the amount of light is appropriate, the processes after step S107 are performed as in the case of turning off the auxiliary light.

Next, the sequence of the subroutine "charging voltage check" executed in step S102 of FIG. 8 will be described in detail with reference to the flowchart of FIG.
Measure the voltage of the power supply E in the strobe circuit 6 described above.
The temperature of the power source E is measured and stored (step 201) (step S202). And this step S2
Based on the results of the power supply voltage and temperature in 01 and S202, the time for performing precharge for the voltage check is determined (step S203).

Then, a high level "H" signal is input from the STCHRG terminal to activate the DC / DC converter 52 and start charging (step S204). Then, charging is performed for the time determined in step S203 (step S205), the voltage of the main capacitor MC is A / D converted from the VST terminal, and the A / D value is stored (step S206).

Further, the A / D value measured in step S206 is compared with the light-emission enable voltage A / D value stored in advance in the EEPROM 3 (step S207). If the measured voltage is high, the operation proceeds to step S208 and the light-emission enable flag is set. Is set, and if the measured voltage is low, the process proceeds to step S209 to clear the light emission enable flag. Then, a low level "L" signal is input to the STCHRG terminal, the operation of the DC / DC converter 52 is stopped (step S210), and this subroutine is finished (step S211).

Next, referring to the flowchart of FIG.
The subroutine "A" executed in step S103 of FIG.
The sequence of “F distance measurement” will be described in detail. First, in step S300 of FIG. 10, the subroutine “AF sensor integration” is executed, and the photoelectric conversion element array 2 in the AFIC 2 is executed.
AF sensor integration by 4R and 24L is performed. Here, the AF optical system 27 for forming a subject image on the photoelectric conversion element arrays 24R and 24L will be described.
By dividing the subject image formed by the photographing lens 28 into two subject images by the re-imaging optical system, re-imaging on the photoelectric conversion element array, and detecting the positional shift between the two subject images. Focus detection optical systems for performing focus detection are already known.

As shown in FIG. 11, a typical one is composed of a condenser lens 26 located in the vicinity of the image plane 122 of the taking lens 28 and a pair of re-imaging lenses 25R and 25L. Then, when the subject image 123 is formed on the image plane 122 when the taking lens 28 is in focus,
The subject image 123 is re-formed by the condenser lens 26 and the pair of re-imaging lenses 25R and 25L on the secondary imaging surface 127 of the photoelectric conversion element array perpendicular to the optical axis O, and the first subject image 123L. , The second subject image 123R. Then, the photographing lens 28 is in front of the focus, that is, the image plane 1
When the subject image 124 is formed in front of 22, the subject images 124 are re-imaged perpendicularly to the optical axis O so that they are close to each other, and the first subject image 124L and the second subject image 124L are formed. Object image 124R. Further, the photographing lens 28 is rear-focused, that is, the subject image 125 is located behind the image plane 122.
, The subject images 125 have optical axes O
The image is re-formed perpendicularly to the optical axis O at a position away from the first subject image 125L and the second subject image 125R. These first and second subject images are oriented in the same direction, and the focus state of the photographing lens 28 is detected including the front focus and the rear focus by detecting the interval between the parts corresponding to each other in both images. can do.

Next, referring to the flowchart of FIG.
The sequence of the subroutine "AF sensor integration" executed in step S300 of FIG. 10 will be described in detail. When this routine is entered, it is first determined whether or not the strobe-off mode is set, and if it is the strobe-off mode, the integration limit time is set to twice the normal limit (2.TL) (steps S400 and S401). . Subsequently, it is determined whether or not the AF sensor integration is started by referring to the flag (step S402), and if the integration is not in progress, the integration is started (step S403). This integration is started by the CPU1 reset signal AFRE to the AFIC2.
S is output and started.

On the other hand, if the integration has started in step S402, the process proceeds to step S405, and it is determined whether or not it is the fill light mode in which the subject is irradiated with fill light to perform integration (step S405). If it is not the auxiliary light mode, the process proceeds to step S410, and it is determined whether or not the integration is completed by referring to the integration end output AFEND of the sensor control circuit SCC in the AFIC2 (step S40).
7).

Then, when this integration is completed, the routine returns, and when it is not completed, the routine proceeds to step S411, where it is determined whether or not the integration limit time has been reached. If this integration time exceeds this integration limit time, A
The integration operation of FIC2 is forcibly stopped (step S
412). If the integration limit time has not been exceeded, the process returns to step S402 and steps S402 and S40.
The loop of S5, S410 and S412 is repeated until the integration is completed or the integration limit time is reached. In addition, the integration time corresponds to the integration control circuit AFEND signal by the interrupt processing RAM
Stored in.

On the other hand, if the mode is the auxiliary light mode in step S405, the process advances to step S406 to execute a subroutine "illumination of auxiliary light", which will be described later, to illuminate the auxiliary light in a certain pattern for a certain time. When the integration is completed during the irradiation of the auxiliary light (AFEND signal), the integration time is fetched by interrupt processing and stored in a predetermined RAM. Furthermore, when the integration is not completed in step S407, the integration operation is forcibly stopped in step S408, the integration limit flag is set in step S409, and then the process returns to complete the integration control operation (step S).
413).

Since the integration limit time described above is provided to prevent the integration time from increasing and the time lag from increasing when the subject has low luminance, when the subject has low luminance, the image of the subject is reduced. The signal may not be obtained correctly. Therefore, when the integration time exceeds a predetermined value, the subject is irradiated with auxiliary light at the time of the next integration to compensate for the shortage of the subject light amount. By the way, the camera of the present invention has a "strobe off mode" in addition to the normal "strobe low-brightness automatic light emission mode" as a shooting mode, and when shooting in a place where stroboscopic photography is prohibited or unfavorable Used temporarily. In this case, irradiation of strobe light as auxiliary light is also prohibited, and at the same time, steps S400 and S4 are performed.
As shown by 01, the integration limit time is set to double to prevent deterioration of focus detection accuracy at low brightness.

Next, referring to the flowchart of FIG.
Strobe circuit 6 executed in step S406 in FIG.
The sequence of the subroutine "illumination of auxiliary light" by will be described in detail.

When the subroutine "illumination of auxiliary light" is called, the number of times of emission of AF auxiliary light is set (step S
501), a subroutine "light emission correction" described later is executed according to the A / D value of the above-mentioned charging voltage check (step S502).

This subroutine "light emission correction" is to correct the light emission time by the A / D value output in the subroutine "charge voltage check" as shown in FIG. That is, when the charge A / D value is smaller than # VOL1 (step S520), AGNO is set to #N.
It is shifted by 2 (step S521). When the charge A / D value is larger than # VOL1 (step S52
0), and compares the charge A / D value with # VOL2 (step S522). If the charge A / D value is smaller than # VOL2, AGNO is shifted by # N1 (step S523). Here, comparison with charge A / D value #VOL
1 and VOL2 have a relationship of # VOL2># VOL1.
And this AGNO corresponds to the table of FIG.
N1 and # N2 correspond to the shift amount on the table, and # N2
># N1.

By the way, the above-mentioned subroutine "light emission correction" is performed by shifting the light emission time, but it is the same as that of correcting the light emission time itself. That is,
As shown in FIG. 15, the light emission time table is selected according to the A / D value shown in the charging voltage check subroutine. When the charge A / D value is smaller than # VOL1 (step S550), the AGNO table data is substituted from the AFGNO table data (step S551). Then, the charging voltage A / D value is #VOL.
When it is larger than 1 (step S550), the charging voltage A /
The D value is compared with # VOL2 (step S552). When the charge A / D value is smaller than # VOL2 (step S552), the AFGNO table data is set to AFGNO.
Substitute from the table data of NO B (step S55
3) If the charge A / D value is greater than # VOL2 (step S552), the AFGNO table data is set to AF.
Substitute from the table data of GNO A. In addition, this A
The table data of the light emission time from FGNO A to AFGNO C is as shown in FIG.

When the sequence returns to the subroutine "illumination of auxiliary light" in this way, the subroutine "precharge" is then executed (step 503). The sequence of this subroutine "precharge" is as shown in FIG. still,
Since this is almost the same as the sub routine "charging voltage check" shown in FIG. 9, the description thereof is omitted here.

Then, the subroutine "light emission" is executed (step S504). The sequence of this subroutine "light emission" is as shown in FIG. When this subroutine is entered, the light emission time for obtaining the required light emission amount is read (step S701), and a high level "H" signal is output from the STON terminal to emit light (step S702). Then, the light emission is continued for the time read in step S701 (step S703), and when a predetermined time elapses, the process proceeds to step S704 and the STOFF terminal is set to the high level "H".
A signal is input to turn off the IGBT 1 and stop the emission of the Xe tube 57. Then, the STON terminal is set to low level "L" (step S705), the STOFF terminal is set to low level "L" (step S706), STON, STOF.
With the F terminal in the initial state, the subroutine returns to "charging voltage check", and proceeds to step S505. And AF
An interval time is set in order to determine the cycle of the auxiliary light (step S505), and the light emission is continued until the predetermined number of times of light emission comes, and when the light emission of the predetermined number of times ends, the process returns (steps S506 and S507).

Next, in step S301 of FIG. 10, a sensor read operation is performed. That is, from the CPU 1 to the AFIC
When a clock is input to the CLK terminal of the sensor control circuit SCC in the circuit 2, the count output D (I) latched by each latch circuit LC in synchronization with this clock is output as D as sensor data.
The sensor data D (I) is sequentially output to the ATA terminal, and the CPU 1 sequentially stores the sensor data D (I) in a predetermined RAM (not shown). When the reading of all the sensor data D (I) is completed, the communication of the sensitivity data DK indicating whether the operation mode of the sensor circuit SC is the high sensitivity mode or the low sensitivity mode is also performed.

Subsequently, in step S302 of FIG. 10, the photometric value of the subject is calculated using the sensor data D (I).
This photometric value is used not only for calculating exposure data and determining the necessity of auxiliary light, but also for determining the reliability of the obtained sensor data. The sensor data D (I) and the charge storage time T
Since (I) has the relationship of the above equation (1), a photometric value can be obtained by obtaining the storage time T (I) of each element from each sensor data D (I).

On the other hand, since the integration time TE is the accumulation time corresponding to the element having the smallest amount of light incident on the photodiode PD as described above, the sensor data D (I) corresponding to this element is the same for all elements. It is the maximum value. Therefore, when the maximum sensor data is DMAX, the integration time TE can be expressed by the following equation by applying the above equation (1).

[0072]

[Equation 3] Therefore,

[0073]

[Equation 4] Therefore, the accumulation time To of the element having the largest amount of light incident on the photodiode PD in the photoelectric conversion element array can be obtained. Substituting this into equation (1) above,

[0074]

[Equation 5] Thus, the integration time TE, the maximum sensor data DMAX, and the sensor data D (I) can be used to calculate the storage time T (I) of each element.

Here, when obtaining the photometric value, it is effective to use the average value of the accumulation time T (I) obtained from each sensor data D (I). Further, if the element in the central portion of the photoelectric conversion element array is obtained, it is possible to delete the portion of the background image or the like where the subject image is not formed. In addition, the above A
Since the first and second subject images divided by the F optical system are equal, either one of the photoelectric conversion element rows 24L or 24
It suffices to calculate R. Therefore, the average accumulation time Tba
r is given by the following equation.

[0076]

[Equation 6] When this is approximated, it is shown as the following equation.

[0077]

[Equation 7] Further, the average accumulation time Tbar is logarithmically compressed, and the photometric value E is expressed by the following equation.

[0078]

[Equation 8]

The correction value HE is the photometric value E and the integration time TE.
It is an adjustment value for correcting the relationship of, and is stored in the EEPROM 3 for each camera by measuring the integration time for a uniform light source. This is because the optical system varies from camera to camera and the sensitivity varies from photoelectric conversion element to photoelectric conversion element. Also, AFI
Since the correction value HE is different between the high-sensitivity mode and the low-sensitivity mode of C2, it has each correction value.

By the way, in this embodiment, the photometric value is calculated using the integration time TE, but the time in the L section of the TOR signal output from the TOR terminal of FIG. 3 (see FIG. 4F) is calculated. When To = TOR is measured, the above equation (1) is applied to calculate the accumulation time T (I) of each element, and the average accumulation time T'of the number of elements n is calculated as follows. .

[0081]

[Equation 9] The photometric value E ′ can be similarly obtained by applying this to the equation (8).

[0082]

[Equation 10]

Then, in step S303 of FIG.
When the subroutine "auxiliary light determination" is executed and the amount of light is insufficient due to low brightness during integration of the AFIC2, it is determined whether the auxiliary light for illuminating the subject with the auxiliary illumination light needs to be turned on or not. A process of setting the amount of auxiliary light is performed.

The sequence of the subroutine "auxiliary light determination" executed in step S303 of FIG. 10 will be described in detail below with reference to the flowchart of FIG. First, whether the integration this time is performed in the high sensitivity mode or not is referred to in the sensitivity data DK. In the low sensitivity mode, the brightness of the subject is sufficiently high and auxiliary light is not required, and therefore the process returns as it is (step S801). Then, in the high-sensitivity mode, the process proceeds to the next step, and it is determined whether or not the auxiliary light is emitted during this integration (step S802). If the auxiliary light is not emitted, whether the auxiliary light is required for the next integration is determined. Determine whether or not. Here, the integration time TE of the AFIC2 and the judgment value Ts1
When the integration time TE is longer than the above, it is judged that the auxiliary light is necessary when the subject has low brightness.

Subsequently, when the flag F AGNO = 1 (step S815), a subroutine "AGN" described later is executed.
"O initial setting" is performed to set the irradiation light amount of auxiliary light.
Strobe light is used as auxiliary light in this embodiment.
GNO is set (step S804). Then, the auxiliary light request flag is set (step S805) and the process returns (step S814). The flag F AGNO is
It is an initial setting request flag for the irradiation light amount of auxiliary light.

Here, the sequence when the auxiliary light is emitted in this integration will be described. When the integration time is short, that is, when the subject is located at a close range or the irradiation light amount of the auxiliary light is too large, the sensor data output from the AFIC2 has a large variation and reproducibility with respect to the subject image. Since bad data is easily obtained, the correlation calculation result using this sensor data is unreliable.

For example, FIG. 20 shows the relationship between the storage time TS and the storage voltage VS during integration while projecting the auxiliary light. The figure shows three cases of A, B, and C where the amount of light incident on the subject image photoelectric conversion element has a ratio of 1: 2: 4. Further, FIGS. 17C and 17B also show the timing of irradiating the subject with periodic strobe pulse light as auxiliary light and the timing of the signal AFRES. For convenience of explanation, let C be the element having the largest amount of incident light among all the photoelectric conversion elements.

The accumulation determination voltage V3 is set for such an accumulated waveform, and the accumulation time TS (FIG. 20) corresponding thereto is set.
(F), (e), (d) TSA, TSB, TSC) and the above equation (2) relating to the quantization method can be applied to calculate the digitized sensor data D (I). By the way, when the incident light amount has a ratio of 1: 2: 4 and no auxiliary light is emitted, that is, the sensor data D (I) in the stationary light mode is expressed by the equation (2) as D (I) = 0, 137 and 205, and this sensor data does not change even if the absolute value of the incident light amount or the accumulation determination voltage V3 changes, as long as the incident light amount ratio does not change.

However, even when the incident light quantity ratio does not change when the auxiliary light is projected, the sensor data D
(I) may change, and it may be difficult to accurately recognize the subject image. That is, in FIG. 20, in order to simplify the change in the brightness of the subject, that is, the change in the absolute value of the amount of light incident on the photoelectric conversion element, the change in the accumulation determination voltage V3 is replaced.

Further, FIG. 21 is a diagram showing a difference from the change in the sensor data DS of the photoelectric conversion elements B and C when the accumulation judgment voltage V3 is changed, with the sensor data DS in the stationary light mode as a reference. Is.

As is clear from the figure, the error ΔDS of the sensor data D (I) at the time of projecting the auxiliary light shows a larger value as the accumulation determination voltage V3 is lower. In other words, the sensor data error ΔDS is larger as the subject reflectance is higher or the auxiliary light projection light amount is larger, so that accurate subject image data cannot be obtained. As a result, the accuracy of focus detection is significantly reduced.

Further, it is also shown that the sensor data error ΔDS becomes larger as the accumulation time TS is shorter. Therefore, the shorter the accumulation time TS is, the lower the focus detection accuracy is. By setting an appropriate amount of auxiliary light in consideration of the distance and controlling so as to obtain an appropriate accumulation time, accurate subject image data can be obtained and focus detection accuracy can be maintained even when the auxiliary light is projected. Therefore, when the integration time TE is shorter than the predetermined value, it is determined that the reliability is low, the irradiation light amount of the auxiliary light is reduced, and the AF sensor integration is performed again.

Now, in step 806, the integration time T
The first judgment is made by comparing E with a predetermined value TS2. Then, if the integration time TE ≧ TS2, the light amount is not over, so the routine returns. If the integration time TE <TS2, it is judged that the light amount is over, and the light amount over flag is set (step S807), and the auxiliary light amount is lowered. For AGN
A predetermined number N is subtracted from O to obtain a new AGNO (step S808).

Subsequently, in step S809, the AG
If NO is smaller than "1", the light amount control range shown in FIG. 20 is exceeded, that is, the subject is located at a very short distance and the reflectance is high, so the undetectable flag is set (step S813), and returns (step S814).

On the other hand, in step S809, AGNO
If ≧ 1, a second determination is made in step S810. Here, for the first determination value TS2 described above, TS2>
The second judgment value TS3, which is TS3, is compared with the integration time TE.
This is for determining the case where the light amount of the second level is larger and for more effectively setting the appropriate auxiliary light amount AGNO. Then, if the integration time TE ≥TS2, the light amount is over, but since the light amount for the first level is over, the flow returns as it is and the above-mentioned AGNO = AGN
ON is saved. On the other hand, the integration time TE <T
In the case of S3, since the light quantity of the second level is larger, the predetermined quantity M is subtracted from AGNO in order to further decrease the light quantity of auxiliary light, and a new AGNO is obtained (step S
811).

Succeedingly, in a step S812, this AG
When NO is smaller than "1", the light amount control range is exceeded as in the above case, and therefore the undetectable flag is set and the process returns (step S814). In the present embodiment, the integration time TE is used for the determination of the light amount over, but it is also effective to make the determination using the photometric value E, the peak accumulation time TOR and the combination thereof.

Next, referring to the flowchart of FIG. 22,
The sequence of the subroutine "initial setting of AGNO" executed in step S804 of FIG. 19 will be described. The present invention has a macro mode as a shooting mode, and is set to the macro mode when the macro mode SW is turned on by the photographer.

First, it is checked whether the macro mode is set as the photographing mode (step S901). In the macro mode, the photographer intends to photograph a subject located in the close range, and accordingly, the auxiliary light amount AGNO is set to a relatively small light amount AGNO = D appropriate for the close subject. Yes (step S907).

On the other hand, if the macro mode is not set, the flow advances to step S902. Then, the light quantity AGNO of the auxiliary light is set to a predetermined value according to the focal length f of the taking lens (step S902). In addition, with a taking lens (28 to 180 mm) having a general focal length, the taking magnification is 1
It is known that / 40 to 1/60 has the highest frequency. Therefore, the subject distance having a high shooting frequency is almost determined according to the focal length, and the auxiliary light amount A corresponding to this is determined.
GNO is initialized. In this embodiment, the focal length is divided into three areas, and an appropriate amount of auxiliary light is set for each. That is, first, the auxiliary light amount AGNO = A corresponding to the first focal length region on the most Wide side is set (step S9).
02).

Then, in step S903, Z
The value of the zoom pulse ZP from the MPI 60 is compared with the first determination value ZP1 to determine whether it is the region 1. Then, in the case of region 1, the process directly returns (step S90).
8). If it is not the region 1, the appropriate auxiliary light amount AGNO = B is set in the region 2 which is the intermediate region (step S904), and similarly, the zoom pulse ZP and the second determination value ZP2 are compared to be the region 2. It is determined whether or not (step S905). Then, similar processing is performed on the area 3 as well, after setting the auxiliary light amount AGNO = C for the area 3 (step S906), the process returns (step S).
908).

In this embodiment, the initial setting value of the auxiliary light amount AGNO is set according to the focal length of the taking lens, but in addition to this, the F number of the taking lens, the above-mentioned photometric value E, the integration time TE, or The same effect can be obtained by changing the peak accumulation time TOR. Further, it may be determined by a combination of these.

FIG. 23 is a table showing the numbers (1 to 12) of the auxiliary light amount AGNO and the GNO value of AGNO. This is the shortest shooting distance of the camera and the optimum auxiliary light amount AGNO suitable for a subject with high reflectance, and the optimum auxiliary light for a subject with a longest shooting distance and low reflectance during flash photography determined by the flash GNO during shooting. Light intensity AGNO
The maximum value of is divided. An appropriate one is selected from these auxiliary light amounts AGNO. On the software, the number (1 to 12) is designated and AGNO is selected.

Next, in step S304 of FIG. 10, the undetectable flag is referred to, and if undetectable, step S31.
In step 9, the out-of-focus flag is set and the sequence of the subroutine "AF distance measurement" is completed. On the other hand, if it is not undetectable, the light amount over flag is referred to in step S305. Then, when the light amount is over, the process returns, and the AF distance measurement routine is called again through the main flow to execute the AF sensor integration while irradiating the set AGNO auxiliary light. Further, when the light amount is not over, the process proceeds to step S306 of illuminance distribution correction.

Then, in the illuminance distribution correction in step S306, the non-uniformity correction of the obtained subject image signal is performed. This is due to the uneven illuminance on the AF sensor surface due to the re-imaging optical system and the photodiode P of the photoelectric conversion element array.
This is to correct sensitivity variations caused by variations in D, storage capacitors, and the like. The correction coefficient calculated by the sensor data D (I) of each element with respect to the uniform light source is stored in the EEPROM 3 for each element in advance, and the correction coefficient is read every time the subject image signal is detected, and the correction calculation is performed for each element. To do. This correction coefficient is obtained as follows. That is, assuming that the photoelectric conversion element output Do (I) with respect to the uniform light source, the accumulation time T (I) of each element is expressed by the following equation from the above equation (1).

[0105]

[Equation 11]

Here, To is the storage time of the photoelectric conversion element having the largest amount of incident light in the photoelectric conversion element array. Ideally, for a uniform light source, the storage time of all elements should be To, but in reality, the above-mentioned factors cause variations. As a correction method, a correction coefficient that matches each accumulation time T (I) with To is obtained. Further, the correction coefficient H (I) is calculated by the formula (1
Using 1), the following equation is obtained.

[0107]

[Equation 12] Then, the sensor data D (I) before correction obtained by detecting the subject image signal The corrected sensor data D ′ using the correction coefficient H (I)
(I)

[0108]

[Equation 13] Becomes

This correction coefficient H (I) must be transformed into a form that can be easily stored in the EEPROM 3. Since the storage capacity of the EEPROM 3 is limited, in order to effectively store the correction coefficient within this range, the correction coefficient H (I) is set to the constants AS and B.
S deforms and compresses as in the following equation.

[0110]

[Equation 14]

In the following, when the constants are actually determined as an example, variations in illuminance on the surface of the AF sensor due to the re-imaging optical system and variations in sensitivity of the AF sensor including the photoelectric conversion element array, for example, are ±. Assuming 15%, the range of the correction coefficient H (I) is as follows. 1 ≤ H (I) ≤ 1.15 On the other hand, in order to keep the deformation correction coefficient H '(I) at, for example, 4 bits due to the storage capacity limitation of the EEPROM 3, the constants AS and BS = 104 may be set. in this case,

[0112]

[Equation 15] And the following range is possible. 0 ≤ H '(I) ≤ 15.6 Further, using the above equation (13), H from the above equation (12)
When (I) is deleted, the corrected sensor data D '(I) is expressed by the following equation.

[0113]

[Equation 16] Here, a constant CS is added so that D '(I) <0 does not hold. For example, if CS = 40,

[0114]

[Equation 17]

From the above, formula (13) is the correction coefficient H '(I) calculation formula, and formula (15) is the illuminance distribution correction formula. Since the amount of incident light is small in the photoelectric conversion element array, the sensor data D (I)
In the case where the quantization limit is 255, the illuminance distribution is not corrected because the incident light amount is not photoelectrically converted correctly.

Next, in step S307 of FIG. 10, a subroutine "correlation calculation" is executed to perform a correlation calculation on the two object images to detect the interval between the two images. Here, the first subject image is the L image, and the first subject image signal is L (I). Further, the second subject image is an R image, and the second subject image signal is R (I). I is an element number, which is 1, 2, 3, ..., 64 in the order of arrangement in this embodiment. That is, each of the element arrays 92L and 92R has 64 elements.

The sequence of the subroutine "correlation operation" executed in step S307 of FIG. 10 will be described below with reference to the flowchart of FIG. First, the variables SL, SR, and J have initial values of "5",
Set "37" and "8" (steps S1001, S1
002). This SL is a variable for storing the leading number of the small block element array for correlation detection from the subject image signal L (I), and SR is for the small block element row for correlation detection from the subject image signal R (I). The head number is a variable that is stored, and J is a variable that counts the number of times the small block moves in the subject image signal L (I). And the correlation output F (S)
Is calculated by the following formula (step S1003).

[0118]

[Equation 18]

In this case, the number of elements in the small block is 27. The number of elements of the small block is determined by the size of the distance measuring frame displayed on the finder and the magnification of the detection optical system. Then, the minimum value of the correlation output F (S) is detected. That is, F (S)
And Fmin if F (S) or Fmin
Substitute F (S) for min and set SL, SR at that time to SLM,
Store as SRM (steps S1004, S100
5).

Further, SR is decremented and J is decremented (step S1006). If J is not "0", the correlation calculation is repeated (step S1007). That is, the small block position in the image L is fixed, and the small block position in the image R is shifted by one element to obtain the correlation. And when J becomes "0". Next, add 4 to SL and SR
Is incremented by 3 to continue the correlation calculation (step S100
8). That is, the correlation calculation is repeated while shifting the small block position in the image L by four elements. When the value of SL reaches 29, the correlation calculation ends (step S1009). As described above, the correlation calculation can be efficiently performed, and the minimum value of the correlation output can be detected. The position of the small block showing the minimum value of the correlation output indicates the positional relationship of the image signals having the highest correlation. Then, in order to determine the correlation of the detected block image signal having the highest correlation, the correlation outputs FM and FP shown by the following equations are calculated (step S1010).

[0121]

[Formula 19]

That is, the correlation output when the object image R is displaced by ± 1 element with respect to the small block position showing the minimum correlation output is calculated. At this time, FM, Fmin, and FP have a relationship as shown in FIGS. Note that FIG.
The horizontal axes of (a) and (b) represent the position of the photoelectric conversion element, and the vertical axis represents the correlation output. The correlation output F (S) becomes "0" at the point ZR. On the other hand, when the correlation is low, it does not become "0".

Then, in order to determine the correlation, the correlation indices SK and FS shown in the following equations are obtained (step S10).
11). When FM ≧ FP SK = (FP + Fmin) / (FM-Fmin) (21) FS = FM-Fmin (22) When FM <FP SK = (FM + Fmin) / (FP-Fmin) (23) FS = FP-Fmin (24) The correlation index SK is SK = 1 when the correlation is high, and SK> 1 when the correlation is low. Therefore, it is possible to determine whether or not the detected image shift amount is reliable based on the value of the correlation index SK. The correlation index FS is
Since it corresponds to the contrast of the small block image signal having the highest correlation, the larger the value, the higher the contrast.

Next, in step S308 of FIG. 10, the correlation indices SK and FS are used to determine the correlation. By the way, the correlation index SK is actually the first or the first due to variations in the optical system, noise of the photoelectric conversion element, conversion error, or the like.
Since the second subject images do not completely match, the correlation index SK does not become "1". Therefore, the predetermined judgment value α
To determine. A predetermined judgment value β is used for the correlation index FS. That is, it is determined that there is a correlation only when SK ≦ α and FS ≧ β, and SK> α or FS <β
In the case of No, it is determined that there is no correlation and it is determined that AF detection is impossible, and the detection impossible flag is set. These judgment values α and β vary depending on the product, and the shooting mode and AF
EEPR because different judgment values are used depending on the operation mode
Each is stored in OM3. If there is a correlation in step S308, the image shift amount is calculated in step S309.

Here, the interval ZR between the first and second object images
Is S _o in FIG. 25 (a), therefore, when FM ≧ FP, ZR = SRM−SLM + (FM−FP) / {(FM−Fmin) · 2} (25) When FM <FP, ZR = SRM -SLM + (FP-FM) / {(FP-Fmin) · 2} (26).

Next, the image shift amount ΔZR from the focus is expressed by the following equation. ΔZR = ZR−ZR0 (27) Here, ZR0 is the object image interval at the time of focusing and is stored in the EEPROM 3 for each camera.

Next, in step S310 of FIG. 10, this image shift amount ΔZR is converted into the defocus amount ΔDF. The amount of deviation of the image formation position with respect to the film surface on the optical axis,
That is, the defocus amount ΔDF can be calculated by the following equation. ΔDF = BD / (AD-ΔZR) -CD (28) where AD, BD, and CD are constants determined by the AF optical system. This is disclosed in Japanese Patent Laid-Open No. 62-100718.

Next, in step S311 of FIG. 10, aberration correction is performed. That is, because the spherical aberration of the taking lens 28 affects the focal length and the focusing extension position, the in-focus position of the AF optical system shifts, which is corrected. This correction value is corrected using the correction value stored in the EEPROM 3 according to the focal length of the taking lens 28 and the subject distance.

Succeedingly, in a step S312 of FIG. 10, a release focus shift correction process for correcting a focus shift at the time of exposure is performed. This is for predicting and correcting the shift of the image forming position during the photographing aperture operation, and since the details are disclosed in Japanese Patent Laid-Open No. 4-30669, the description thereof will be omitted here.

Succeedingly, in a step S313 of FIG. 10, it is determined whether or not the detected defocus amount ΔDF is within the focusing allowable range. The permissible focus range is determined by the depth of field, that is, the aperture value at the time of shooting and the focal length of the shooting lens. Since the detected defocus amount varies greatly when a low-contrast subject, a low-luminance subject, auxiliary light irradiation, or a long focal length of the photographing lens, the focus allowable range is expanded to stabilize the AF operation. If it is within the focus allowable range, the focus flag is set in step S315 and the process returns. If the focus is out of the allowable range, step S
At 314, the lens drive pulse amount is calculated.

Since various methods have been proposed in the past for converting the detected defocus amount ΔDF into the lens aperture amount ΔLK in the optical axis direction, detailed description thereof will be omitted here. For example, in the one disclosed in JP-A-64-54409, it is calculated by the following formula. ΔLK = Aa− (Aa × Ba) / (Aa + ΔDF) + Ca × ΔDF (29) Here, Aa, Ba, and Ca are constants stored for each focal length.

The focusing lens of the taking lens 28 is driven by the LDM 13 via a gear train, and the moving amount of the focusing lens is input to the IFIC 7 as an AFPI pulse by the LDPI 16. Therefore, the AFPI per unit extension amount can be calculated based on the lens extension amount ΔLK in the optical axis direction.
When the lens driving pulse amount DP is obtained by multiplying the pulse number K, it is shown by the following equation. DP = K × ΔLK (30) Note that the image shift amount ΔZR in the equation (27) and the defocus amount ΔDF in the equation (28) are both values with a sign. When the value is positive, the direction in which the lens is extended by the rear pin (imaging on the rear side of the film surface) is shown, and when the value is negative, the direction in which the lens is extended by the front pin (imaging on the front side of the film surface) is indicated.

Then, if there is no correlation in step S308 of FIG. 10, the auxiliary light mode flag is referred to in step S316 to check whether or not this time the AF sensor integration auxiliary light irradiation has been performed. If the auxiliary light is off, the non-focus flag is set in step S319, and the sequence of the subroutine "AF distance measurement" is ended.

On the other hand, if the auxiliary light is "ON", the process proceeds to step S317, and the subroutine "increase the amount of auxiliary light"
Execute the sequence of. Hereinafter, the sequence of the subroutine "increase auxiliary light amount" executed in step S317 of FIG. 11 will be described with reference to the flowchart of FIG.

First, with reference to the integration limit flag, it is determined whether the integration time TE exceeds the integration limit time TL (step S1101). Here, in the case of the integration limit, it is highly possible that proper subject image data could not be obtained due to the shortage of the amount of auxiliary light, and the correlation could not be obtained. In this case, a predetermined number L is added to the auxiliary light amount AGNO to newly obtain A
GNO is set (step S1102). This is to obtain more appropriate subject image data by irradiating the increased amount of auxiliary light when the auxiliary light mode sensor is integrated next time. Further, it is determined whether the new AGNO is within the control range (step S1103). If AGNO> 12, the control range shown in FIG. 20 has been exceeded, so the undetectable flag is set in step S1104 and the process returns (step S1105). In such a case, there are situations such as "the subject is located at a long distance", "the reflectance is low", and "the brightness is very low".
On the other hand, when AGNO ≦ 12, the control is within the control range, and the process directly returns.

In step S1101, if it is not the integral limit, it is unlikely to be improved even if the amount of auxiliary light is increased. Therefore, in step S1104, the undetectable flag is set and the process returns (step S1).
105).

In this embodiment, the shortage of the auxiliary light irradiation light amount is determined by determining whether or not the integration limit is reached. However, instead of the integration time TE (accumulation time of the element having the smallest received light amount in the photoelectric conversion element array), the TOR signal (accumulation time of the element having the largest received light amount in the photoelectric conversion element array) is used for determination. Is also effective. Alternatively, the determination may be made using the photometric value E described above. Alternatively, more effective control can be performed by making a determination based on a combination of the integration times TE, TOR, and the photometric value E.

Next, the undetectable flag is referred to in step S318 of FIG. If it cannot be detected, the out-of-focus flag is set in step S319 and the process returns. On the other hand, if it cannot be detected, the process directly returns to call AF distance measurement again in the main flow.
Then, the taking lens 101 is driven based on the result of the AF distance measurement in FIG.

The sequence of the subroutine "lens drive" executed in step S109 of FIG. 8 will be described below with reference to the flowchart of FIG. First, A
It is determined whether the number of lens driving pulses calculated in the F distance measurement process is larger than a predetermined value (step S1201). For this predetermined determination value, the number of lens drive pulses that can always drive the lens within the in-focus range with one lens drive is used. Here, it is set to 400 pulses, for example.

If the lens driving pulse number is less than 400 pulses, the process proceeds to step S1202, and it is determined by a flag whether the backlash drive has already been completed. If the backlash drive has not been completed, the process proceeds to step S1203. , It is determined whether or not the lens driving direction is reversed from the last time. If it is the same as the previous lens drive direction, the lens drive is executed based on the lens drive pulse number of the AF distance measurement result in step S1204. Further, in step S1205, the focus flag is set and the process returns. As described above, the number of drive pulses is always in focus with one lens drive, and since the lens drive direction is the same as the previous time, there is no backlash, so AF is not performed again and focus is achieved.

Subsequently, returning to step S1202, it is determined whether the backlash drive has been completed by referring to the backlash drive completed flag. If the backlash has been completed, the process advances to step S1204 to drive the lens, and step S1205.
Then, the focus flag is set and the process returns. Then, returning to step S1203, when the lens driving direction is the reverse direction with respect to the previous time, the process proceeds to step S1206 to calculate the backlash amount. The amount of backlash changes depending on the focal length and the driving direction of the taking lens, so calculations are made accordingly.

Subsequently, in step S1207, the lens is driven by the number of lens drive pulses corresponding to the backlash amount based on the calculated backlash amount. Then, in step S1208, the backlash driven flag is set and the process returns. In this case, AF distance measurement processing and lens drive processing are performed again on the main flow.

Next, returning to step S1201, if the number of lens driving pulses calculated by the AF distance measurement is 400 pulses or more, the process proceeds to step S1209, and a predetermined value is subtracted from the lens driving pulse to obtain a new lens driving pulse. To do. This predetermined value is a correction value indicating a position before the focal point in the lens drive pulse, and is 200 pulses here, for example.

Then, in step S1210, lens driving is performed based on the corrected lens driving pulse. With this lens drive, even if there is backlash, it will be removed. Further, in step S1211, the backlash driven flag is set and the process returns. As a result, the lens is in the position of 200 pulses as the driving pulse number before the focusing point, so that AF distance measurement and lens driving processing are called again in the main flow to bring the lens into focus.

Further, the above-mentioned correction value is set so as to give a feeling of speed of the AF operation related to the display of the viewfinder (not shown) of the camera. For example, consider a case in which AF distance measurement and lens drive processing are repeated twice to focus from a state where the defocus amount is large. When the stop position of the first lens drive is relatively close to the in-focus point, for example, when 50 pulses in the front are in focus in the viewfinder,
At 0 pulse, the focus is still out of focus. When the second lens drive is executed from this state, the focus is achieved in any case, but the latter viewfinder provides a more sense of speed when the focus is out of focus. Therefore,
Since the appearance of the above-mentioned finder greatly changes depending on the focal length of the taking lens, the correction value is changed accordingly.

The sequence of the subroutine "first release" executed in the camera to which the present invention is applied has been described above. Next, with reference to the flowchart of FIG. 28, the subroutine executed in the camera to which the present invention is applied. The sequence of "second release" will be described.

When the second release R2SW is pressed to enter this subroutine, the G-ON terminal is set to the high level "H", the power supply control circuit 56 is turned "on", and the electric charge is supplied to the gate terminal of the IGBT 1 (step S1301). .
Then, the subroutine "red-eye emission" is executed (step S1302).

The sequence of the subroutine "red-eye reduction light emission" by the flash circuit 16 is as shown in the flowchart of FIG. That is, this sub-routine is the same as the above-mentioned sub-routine “auxiliary light irradiation” sequence and the number of times of light emission in step S1401 and step S14
The operation is the same except that the interval time of 04 is slightly different, and the amount of emitted light in step 1403 is also preset.

Then, the mirror is raised (step S
1303), if flash firing is required, step S
If the flash emission is unnecessary in step 1305, the flow advances to step S1308 (step S1304). Then, the above-mentioned subroutine "pre-charge" is executed (step S1305). When step S1305 ends, the front curtain is started (step S1306), and when the front curtain ends, the above-mentioned subroutine "light emission" is executed (step S1307).

On the other hand, when the stroboscopic light emission is not necessary in step S1304, the front curtain is started (step S1308), and then the process proceeds to step S1309. Then, the rear curtain is started to end the exposure (step S1309), and the mirror is moved down (step S13).
10), the shutter is charged to the initial state (step S1311), and the film is wound up (step S13).
12), the "L" signal is input to the G-ON terminal (step S1313), the power supply to the gate of the IGBT 1 is prohibited, and the photographing ends (step S1314).

As described above in detail, in the present invention, the preliminary illumination is performed with a desired light emitting guide number regardless of the charging voltage of the main capacitor, so that the release time lag can be reduced.

[0152]

According to the present invention, the amount of emitted light of the preliminary irradiation can be freely changed based on the reflected brightness of the object, a good contrast output can be obtained regardless of the object distance, and it is remarkable in the case of continuous light emission. It is possible to provide a preliminary irradiation device for focus detection which can prevent a release time lag and can emit light with a desired guide number regardless of the charging voltage of the main capacitor.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a control system of a focus detection preliminary irradiation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a detailed configuration of an AFIC2.

FIG. 3 is a diagram showing a detailed configuration of a sensor circuit SC in the AFIC2.

FIG. 4 is a time chart for explaining the operation of AFIC2.

FIG. 5 is a time chart for explaining the operation of AFIC2.

FIG. 6 is a diagram showing a detailed configuration of a flash circuit 6.

7 is a diagram showing a more detailed configuration of a strobe circuit 6. FIG.

FIG. 8 is a flowchart showing a sequence of a subroutine “first release” executed by a camera to which the present invention has been applied.

9 is a flowchart showing a sequence of a subroutine "charging voltage check" executed in step S102 of FIG.

10 is a flowchart showing a sequence of a subroutine "AF distance measurement" executed in step S103 of FIG.

FIG. 11 is a diagram showing a configuration of an AF optical system 27 for forming a subject image on the photoelectric conversion element arrays 24R and 24L.

12 is a flowchart showing a sequence of a subroutine "AF sensor integration" executed in step S300 of FIG.

13 is a flowchart showing a sequence of a subroutine "illumination of auxiliary light" by the strobe circuit 6 executed in step S406 of FIG.

14 is a flowchart showing a sequence of a subroutine "light emission correction" executed in step S502 of FIG.

FIG. 15 is a flowchart showing a sequence of an improved example of a subroutine “light emission correction” executed in step S502 of FIG.

FIG. 16 is a diagram showing a table for selecting a light emission time according to a charge A / D value.

FIG. 17 is a flowchart showing a sequence of a subroutine “precharge” executed in step S503 of FIG.

FIG. 18 is a flowchart showing a sequence of a subroutine “light emission” executed in step S504 of FIG.

19 is a flowchart showing a sequence of a subroutine "auxiliary light determination" executed in step S303 of FIG.

FIG. 20: Accumulation time TS during integration while projecting the auxiliary light
FIG. 5 is a diagram showing the relationship between the storage voltage VS and the storage voltage VS.

FIG. 21 is a diagram showing a change from the change in the sensor data DS of the photoelectric conversion elements B and C when the accumulation determination voltage V3 is changed with reference to the sensor data DS in the stationary light mode as a reference.

22 is a flowchart showing a sequence of a subroutine "initial setting of AGNO" executed in step S804 of FIG.

FIG. 23: Auxiliary light intensity AGNO number (1 to 12) and A
It is a figure which shows the table | surface of GNO value of GNO.

24 is a flowchart showing a sequence of a subroutine "correlation calculation" executed in step S307 of FIG.

FIG. 25 is a diagram showing a relationship between the position of a photoelectric conversion element and a correlation output value.

FIG. 26 is a flowchart showing a sequence of a subroutine “increase auxiliary light amount” executed in step S317 of FIG.

FIG. 27 is a flowchart showing a sequence of a subroutine “lens drive” executed in step S109 of FIG.

FIG. 28 is a flowchart showing a sequence of a subroutine “second release” executed in the camera to which the present invention has been applied.

FIG. 29 is a flowchart showing the sequence of the subroutine “red-eye reduction light emission” executed in step S1302 of FIG. 28.

[Explanation of symbols]

1 ... CPU, 2 ... AFIC, 3 ... EEPROM, 4 ... Liquid crystal display panel, 5 ... Data bag, 6 ... Strobe unit, 7 ... IFIC, 8, 9 ... Motor driver IC, 10
... AV motor, 11 ... AVPI, 12 ... Shutter charge motor, 13 ... Lens driving motor, 14 ... Zooming motor, 15 ... SCPI, 16 ... LDPI, 17 ...
ZMPR, 18 ... ZMPI, 19 ... Viewfinder display LED, 20 ... Remote control transmission unit, 21 ... Projection LED, 22, 23 ... Silicon photodiode, 24
L, 24R ... Photo sensor array, 25L, 25R ... Separator lens, 26 ... Condenser lens, 27 ... AF
Optical system, 28 ... Shooting lens.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0065

[Correction method] Change

[Correction content]

This subroutine "light emission correction" is to correct the light emission time by the A / D value output in the subroutine "charge voltage check" as shown in FIG. That is, when the charge A / D value is smaller than # VOL1 (step S520), AGNO is set to #N.
It is shifted by 2 (step S521). When the charge A / D value is larger than # VOL1 (step S52
0), and compares the charge A / D value with # VOL2 (step S522). If the charge A / D value is smaller than # VOL2, AGNO is shifted by # N1 (step S523). Here, the comparison value with the charge A / D value #VOL
1 and VOL2 have a relationship of # VOL2># VOL1.
And this AGNO corresponds to the table of FIG.
N1 and # N2 correspond to the shift amount on the table, and # N2
># N1.

Claims (1)

[Claims] 1. Flash emission means for pre-illuminating an object during measurement, emission control means for controlling emission of the flash emission means during pre-irradiation, and emission amount setting means for setting the emission intensity of the flash emission means. An output of the light intensity determination means and an output of the charging voltage detection means, the light intensity determination means for determining the light intensity of the light of the subject, and the detection means for detecting the charging voltage of the flash light emitting means. A preliminary irradiation device for focus detection, characterized in that the amount of emitted light at the time of measurement is variable in response to and.