JPH063492B2 - Automatic focus adjustment device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focus detection device that receives a subject image formed by a taking lens to detect the focus of the taking lens with respect to the subject. More specifically, the present invention relates to an automatic focus detection device provided with a control unit that operates when the above focus detection result is not reliable.

Conventional technology Conventionally, as a result of focus detection without emitting auxiliary light source,
If the subject is determined to have low contrast,
It is known that the auxiliary light source is caused to emit light to perform focus detection again (Japanese Patent Laid-Open No. 54-126023). However, there are some subjects that have low contrast even if the subject brightness is high, and even if the auxiliary light source emits light to such a subject, the low contrast cannot be easily eliminated.

Further, it is also known that the focus detection is performed again while driving the focusing lens when the subject is judged to have a low contrast based on the focus detection result (JP-A-57-196219 and JP-A-58-58). 1109
issue). However, when the subject brightness is low, it is quite difficult to find the focusing lens position where the contrast becomes high, no matter how much focus detection is performed while driving the focusing lens.

It is an object of the present invention to provide an automatic focus detection device that overcomes the above-mentioned drawbacks of the prior art and can perform appropriate focus detection operations for various subjects.

The automatic focus detection device of the present invention includes means for determining the reliability of the focus detection result and means for determining whether or not the subject has low brightness, and the reliability of the focus detection result is low and the subject If the brightness is low, the auxiliary light is emitted to perform focus detection again.If the reliability of the focus detection result is low and the subject brightness is not low, focus detection is performed again while driving the focusing lens group. It is characterized by doing.

Embodiment FIG. 1 is a block diagram showing the basic configuration of the present invention.
Reference numeral (10) is a photographing lens, and the light transmitted through the photographing lens is received by the light receiving section (1). This light receiving part (1) has 2
A small number of light receiving element rows are provided, and each light receiving element row captures light from different exit pupils of the taking lens.
The light receiving optical system is configured so that light is received at the substantially planned focal plane of (10). (2) is a drive circuit of the light receiving section (1),
When the terminal (21) of the arithmetic / control circuit (3) becomes "High",
The light receiving operation of the light receiving section (1) is controlled via the terminal (31), and the data obtained by A / D converting the output of each light receiving element of the light receiving section (1) is operated via the terminal (32). 3) and the discrimination circuit (4). The terminal (20) outputs a "High" signal when the subject has low brightness. The calculation / control circuit (3) sets the terminal (21) to “High” when the light receiving section (1) and the drive circuit (2) perform the measurement operation of the incident light amount distribution on the light receiving element array, and the drive circuit (2) When all the data are fetched from, the same pin is set to “Low”. Then, based on the captured data, the movement amount and the movement direction until the photographing lens (10) reaches the in-focus position, or a signal indicating that it is in the in-focus state is calculated, and the movement amount data is output to the terminal (33) To the terminals (23) and (24), and the terminal (21) is set to "High" again.

The discriminating circuit (4) reads the data from the drive circuit (2) and discriminates whether or not the contrast of the subject light on the light receiving element array is sufficient. If the contrast is insufficient, the data of the movement amount calculated by the arithmetic / control circuit (3) is not reliable, so the terminal (25) is set to “High.” (5) is the display circuit and the terminal. The front focus, rear focus, and focus are displayed based on the signals from (23) and (24). Furthermore, if the terminal (25) becomes "High", the automatic focus adjustment operation will not be performed normally and a warning will be displayed. Do.

(7) is a logic circuit, and if the terminal (26) is "Low" without low contrast, the terminals (25) and (27) are "Low". At this time, the controller (8)
The motor (9) is driven based on the direction signals from 3) and (24). Then, the focusing optical system of the taking lens (10) is driven, and the number of pulses corresponding to the driving amount is output from the encoder (6), and the number of pulses matches the movement amount data from the terminal (33). Then, the motor (9) is stopped.
Since the measurement signal is repeatedly output from the terminal (21) of the arithmetic / control circuit (3), the measurement of the incident light amount distribution is performed even while the lens is moving. Therefore, the arithmetic control circuit inputs the pulse from the encoder (6) and outputs the movement amount data in which the lens movement amount is corrected to the terminal (33) while the lens is moving. Then, the movement amount data is sequentially updated, and the fact that the lens has reached the in-focus position is indicated by the calculation / control circuit (3).
(When the calculated value is within the focus area) or controller (8)
When it is determined by (when the movement amount data and the number of pulses from the encoder match), the movement of the lens (10) is stopped.

The discrimination circuit (4) discriminates that the contrast is low, the terminal (25) becomes “High”, and the terminal (20) becomes “Hi” at low brightness.
When the light emission enable signal is input from the terminal (22), the output terminal (27) of the logic circuit (7) becomes “High. At this time, drive the motor (9) of the controller (8) to start. Instead, the arithmetic / control circuit (3) sets the terminal (21) to "High" to start the next measurement operation. At this time, the terminal (27) is
Since it is gh, the output (28) of the AND circuit (11) becomes “High” and the light emission drive circuit (12) operates to operate the xenon tube (13) for pre-irradiation.
Emits light. Then, the arithmetic / control circuit (3) calculates the amount of movement of the focusing optical system of the photographing lens based on the measured value at this time, and the controller (8) drives the lens (10) based on this amount of movement. . In this mode, the arithmetic / control circuit (3) does not output a "High" signal from the terminal (21) unless a "High" signal is input from the terminal (38). And shooting lens
When the controller (8) determines that the focusing optical system of (10) has moved by the calculated movement amount, the rotation of the motor (9) stops and the terminal (38) becomes "High". Terminal (2
When 1) becomes “High” and the measurement using the second preliminary irradiation starts, and the lens moves by the movement amount calculated based on it, the movement of the lens (10) stops and the automatic focus adjustment operation starts. finish.

Even if the terminal (25) is "High" at low contrast and the terminal (20) is "High" at low brightness, when the light-emission enable signal is not input from the terminal (22) or at low contrast
Even if (25) is "High", it is not low brightness and the terminal (20) is "Lo".
When it is "w", the terminal (26) of the logic circuit (7) becomes "High". At this time, the controller (8) moves the lens regardless of the output of the arithmetic / control circuit (3). When the discriminator circuit (4) discriminates that the measured value is no longer low contrast and sets the terminal (25) to "Low", the logic circuit (7) sets the terminal (26) to "Low" and the above calculation is performed. The operation moves to move the lens based on the movement amount data. The determination circuit (15) inputs the pulse from the encoder (6) when the terminal (26) is “High”, and the focusing optical system of the photographing lens (10) moves to the infinity focus position or the closest distance focus position. When the focusing optical system reaches either end, the terminal (36) is set to “High”.
Then, the rotation direction of the motor (9) by the controller (8) is reversed. When the other end is reached, the lens (10) has been scanned over the entire area, and the terminal (37) is set to "High" to drive the motor (9) by the controller (8).
To stop the rotation of. At this time, if the light emission enable signal is input from the terminal (22), the logic circuit (7) sets the terminal (27) to "High" and shifts to the automatic focus adjustment operation using the preliminary irradiation described above.

FIG. 2 is a circuit diagram showing the entire camera system to which the present invention is applied. The light receiving part (FMD) is a CCD (Charge Coup
LED device) is provided with two rows of light receiving elements, and each light receiving element row is a light receiving portion that receives visible light including near infrared light among subject light from the exit pupil of the photographing lens. Incidentally, various optical systems for receiving light have been omitted because they have been proposed, but for example, those shown in JP-A-57-49841 may be used. (COC) is a control circuit that controls the operation of the light receiving unit (FMD). Further, (MCO1) is a microcomputer for automatic focus adjustment, and (MCO2) is a microcomputer for controlling the operation of the camera (hereinafter referred to as a microcomputer). First, the photometric operation by the above parts will be described.

When the terminal (O3) of the microcomputer (MCO1) becomes “High”, a “High pulse is output from the terminal (φR) of the control circuit (COC), and the analog switch (AS2) becomes conductive,
The plurality of charge storage units of the CCD (FMD) are connected to terminals (AN
It is charged to the output voltage of the constant voltage source (E1) via M). Then, when the terminal (φR) becomes “Low”, charges corresponding to the amount of light received by each light receiving unit are accumulated in the charge storage unit.
At this time, a signal corresponding to the accumulated charges by the monitor light receiving unit (not shown) in the CCD (FMD) is output to the terminal (ANM).
Output from the comparator (AC) because the terminal (φR) is "Low" at this time, the analog switch (AS1) is conducting.
It is given to the inverting input terminal of 1). The output voltage gradually decreases as the charge is accumulated. At this time, in the mode in which the flash preliminary light emission by the electronic flash device is not performed, the terminal (O1) becomes “Low”, the analog switch (AS3) becomes conductive, and the output voltage of the constant voltage source (E2) In the flash preliminary light emission mode, the terminal (O1) is "High", the analog switch (AS4) is conductive, and the output voltage of the constant voltage source (E3) is applied to the non-inverting input terminal of the comparator (AC1).

When the monitor output from the terminal (ANM) of the light receiving unit (FMD) reaches the level of the low voltage source (E2) or (E3), the output (STP1) of the comparator (AC1) is inverted to "High" and the control circuit (COC ) Output a transfer pulse from the terminal (φT) of the charge storage unit, the charge accumulated in the charge storage unit corresponding to the amount of light received by each light receiving unit is transferred to the transfer gate, and the transfer pulse (φ1), (φ2). , (Φ
Based on 3), a signal of accumulated charge is sequentially sent from the terminal (ANS) to the control circuit (COC). Control circuit (COC)
Then, the signals sent from the terminal (ANS) are sequentially A-D
Conversion, and each time one A-D conversion is completed, the terminal (AD
A pulse is output to E), and the A-D converted data is output to the output terminal (ADD).

Further, when the transfer pulse is not output from the terminal (φT) even after a certain period of time has elapsed since the start of charge accumulation, it means that the brightness of the subject is low, and in this case, the pulse is output from the terminal (O2). When this pulse is input, the control circuit (COC) outputs a transfer pulse (φT) regardless of the output of the comparator (AC1).

When performing pre-irradiation with an electronic flash device, the terminal (O
1) becomes “High”, and the voltage from the constant voltage source (E3) is input to the non-inverting terminal of the comparator (AC1). The output potential of this constant voltage source is higher than the output potential of the constant voltage source (E2). Therefore, the transfer pulse (φT) is output at a time point when the amount of charge accumulated by the monitor unit is smaller than that when the preliminary irradiation is not performed.
When performing pre-irradiation with flash light, the intensity of flash light changes abruptly.
This is to prevent the charge storage unit from overflowing and being unable to measure the correct light amount distribution.

As described above, the microcomputer (M
When the terminal (O3) of CO1) becomes “High”, a pulse is output from the one-shot circuit (OS1), and this pulse is output via the AND circuit (AN1) and the terminal (JB1).
A light emission start signal is sent to the electronic flash device via (JF1). Even if the preliminary irradiation is performed, if the transfer pulse (φT) is not output even after a certain period of time, a pulse is output from the terminal (O2) to forcibly output the transfer pulse to perform the charge storage operation. Stop. By the way, the fixed time for limiting the accumulation time is shorter than that when the preliminary irradiation is not performed. This is because the flash light emission time is short and it is not necessary to lengthen the integration time.

When the microcomputer (MCO2) reads data from the electronic flash device (FLC), the data contains a signal indicating whether or not preliminary irradiation is possible. When a signal indicating that preliminary irradiation is possible is input, the microcomputer (MCO2) sets the terminal (O16) to "High. The microcomputer (MCO1) operates in the mode in which preliminary irradiation is performed if the terminal (i2) is" High ". If it is “Low”, it is determined that the operation in the pre-irradiation mode is impossible.

(MDR) is a circuit for driving a motor (MO) for focus adjustment. When the focus detection result is the front pin and the lens needs to be retracted, the terminal (O of the microcomputer (MCO1)
4), when it is necessary to pay out with the rear pin, the terminal (O
5) becomes “High. The rotation of the motor (MO) is transmitted to the lens side (LE) via the lens driving unit (LD) to adjust the focus of the lens.
The drive amount of D) is converted into a pulse signal by the encoder (ENC), and the pulse signal is converted by the microcomputer (MCO1).
Is input to the clock input terminal (CPI) of and the drive amount is counted. Further, the pulse from the encoder (ENC) is input to the motor drive circuit (MDR) and used as a reference signal for driving the motor (MO) so that the lens driving speed becomes constant.

(FDP) is a display unit that displays a focus adjustment state, and displays a front focus state, a focus state, a rear focus state, and a focus adjustment failure warning according to data from the output terminal (OP1) of the microcomputer.

The switch (SMB) shown in the upper left corner of the figure is the main switch, and (BB) is the power supply battery. From the power battery (BB), the microcomputer (MCO1), (MCO1), (MCO1) via the main switch (SMB) and the power line (+ E)
Power is directly supplied to CO2). The switch (S1) is a photometric switch that is closed at the first step of pressing the release button (not shown). When this switch (S1) is closed, the inverter (IN3), AND circuit (AN3), OR circuit An interrupt signal is input to the interrupt terminal (it) of the microcomputer (MCO2) via (OR4), and the terminal (O12) is set to "High" to drive the transistor (BT) via the inverter (IN6).
1) is made conductive and the inverters (IN3) to (IN6), AND circuits (AN2), (A) are connected via the power supply line (+ V).
N3), OR circuit (OR4), microcomputer (MCO1),
Power supply to circuits other than (MCO2) is started. And
The power-on reset circuit (PO
1) Reset pulse is output from power line (+
The circuit supplied with power from V) is reset. When the terminal (O12) becomes "High", the AND circuit (AN
3) is disabled, (AN2) is activated, and the interrupt signal from the switch (S1) is not input.

The switch (S2) is a release switch which is closed by the second step of pressing the release button, and the switch (S4) is opened when the exposure control operation is completed and closed when the charge of the exposure control mechanism (not shown) is completed. It is a reset switch. Therefore, when the release switch (S2) is closed while the charge of the exposure control mechanism is completed and the reset switch (S4) is closed, the terminal (via the AND circuit (AN2) and the OR circuit (OR4) ( An interrupt signal is input to it).

A block (EDO) at the center of the drawing is a block for outputting the set exposure control data, and the set data is sequentially read from the terminal (IP10) based on the read signal from the terminal (OP13). (LMC) is an exposure photometric circuit, and the analog input terminal (ANI) for A / D conversion has a photometric circuit (LM).
The output of C) is input. Also, a microcomputer (MCO2)
As a reference voltage for the D-A converter of the photometric circuit (LM
The reference voltage in C) is input to the terminal (VRI). (EX
D) is a display circuit for displaying the exposure control value and is a terminal (OP14)
The exposure control value is displayed based on the display data from.
(EXC) is an exposure control circuit which controls the aperture and the exposure time based on the signal from the terminal (OP15). In addition, the terminal (TIE) becomes “High” from the time of shutter release to the time when a certain time has elapsed after the trailing curtain starts running, and the integration operation for controlling the flash emission amount at the time of shooting is enabled.

(LEB) is an interface circuit for reading data from the circuit (LEC) on the lens side. As described above, when the transistor (BT1) becomes conductive, the power line (+
Power is supplied from V) to the circuit (LEC) on the lens side through the terminals (JB11) (JL1). When the terminal (O15) of the microcomputer (MCO2) becomes "High", the interface circuit (LEB) becomes operable, and the terminals (JB12), (JL2) become "High", and the circuit (LEC) on the lens side becomes ) Also becomes operable. In the circuit (LEC) on the lens side, the ROM for fixedly storing the exposure control data and the automatic focus adjustment data peculiar to the conversion lens at a plurality of addresses, and the addresses of the ROM are terminals (JB13), (JL3). If the lens is a zoom lens, based on the clock pulse input via the, the addressing means for sequentially specifying based on the output of the code plate corresponding to the clock pulse and the focal length,
The data output from the ROM in parallel is output to the terminal (JB1
3), based on the clock pulse input via (JL3), the terminals (JL4), (JB1
4) through parallel-serial conversion means for outputting via.

The data fixedly stored in the ROM include check data for confirming mounting, which is provided in common for all interchangeable lenses, open aperture value data, maximum aperture value (aperture when the aperture diameter is minimum). Value data, open metering error data, focal length data, aperture change amount data according to the focal length set by the zoom lens, and the like. Furthermore, a conversion coefficient (KD) for converting the defocus amount detected by the focus detection device into a lens drive amount, and near infrared light so as to prevent the subject from feeling dazzling during preliminary irradiation with a flash. To correct the in-focus position deviation (difference in defocus amount) between the near-infrared light and visible light caused by irradiating the Data (IRD) to correct the above, when the driving direction of the lens is changed from one direction to the other direction, the drive shaft is driven extra by the play of the camera-side drive shaft and the lens-side follower. The extra drive amount when it is necessary to do, that is, the backlash data (B
LD) etc.

Eight clock pulses are output from the terminal (SCP) of the microcomputer (MCO2), and the lens side circuit (LE
In C), every time 8 clock pulses are input, RO
The address of M is updated, and the data fixedly stored at the designated address is sequentially output in series based on the clock pulse and sequentially read from the serial input / output terminal (SIO) of the microcomputer (MCO2). .

(FLB) is an electronic flash device control circuit, and (FLC)
Is a circuit in the electronic flash device. A specific example of the circuit (FLC) in the electronic flash device is shown in FIG. 3, and the operation using the electronic flash device will be described below in conjunction with FIG. Third
In the figure, (BF) is a power supply battery of the electronic flash device,
(SMF) is a main switch. (DD) is a booster circuit, and the high voltage terminal on the secondary winding side of the booster circuit (DD) is connected to the main capacitor (C) via the diode (D1).
2), and the main capacitor (C2) is charged by the voltage of the high voltage terminal. Further, the low voltage terminal of the secondary winding is connected to the capacitor (C1) through the diode (D2), and the output voltage thereof charges the capacitor (C1). When the main switch (SMF) is closed, the transistors (BT2) and (BT3) become conductive, and the boosted output from the voltage stabilization circuit (CV) or the output of the power supply battery (BF) via the diode (D3). Power is supplied to the power supply line (VF) through the transistor (BT3). Electric power is supplied from the power supply line (VF) to all circuits whose power supply path is not shown in FIG. When power supply from the power supply line (VF) is started, a reset signal is output from the power-on reset circuit (PO2), and the digital circuit section is reset. Switch (SO
F) is a switch that is opened and closed in the same phase in conjunction with the main switch (SMF). And resistances (R1) to (R4)
Is a resistor that divides the charging voltage of the main capacitor (C2), and (VC) is a constant voltage source. When the potential of the connection point between the resistors (R1) and (R2) exceeds the potential of the constant voltage source (VC), the output of the comparator (AC21) becomes "High", and when this signal becomes "High, the xenon tube ( XE
The capacitor (C2) is charged up to the minimum voltage required for 1) to emit light, and when the light emission start signal is input, the xenon tube (XE2) starts to emit light. The potential at the connection point between the resistors (R2) and (R3) is the constant voltage source (V
When the output potential of C) is exceeded, the comparator (AC22)
Output becomes "High. In this case, the xenon tube (XE
This means that the voltage of the main capacitor (C2) has been charged to the voltage required for the amount of light emitted in 2) to reach the nominal amount of light emission, and a charge complete signal is sent to the camera body and the display circuit (CDP) Charging completion is displayed.
When the potential at the connection point between the resistors (R3) and (R4) exceeds the output potential of the constant voltage source (VC), the comparator (AC2
The output of 3) becomes “High.” At this time, the xenon tube (XE2) for shooting emits light at a nominal value, and the xenon tube (XE1) for preliminary irradiation emits light a predetermined amount of time twice. It indicates that the main capacitor (C2) has been charged up to a certain value, and this signal is sent to the camera side as a preliminary irradiation enable signal Note that the switch (SS) is a switch that can be manually switched, and this switch (SS) If is connected to the terminal (EN), the preliminary irradiation enable signal is sent to the camera side, but if connected to the terminal (DEN), the input to the terminal (PCH) is always "Low" and the preliminary irradiation enable signal is sent. Is not sent to the camera side, the camera does not go into the preliminary irradiation mode, and the output of the OR circuit (OR20) is "Low".
As it is, it does not emit light.

(TR1) and (TR2) are xenon tubes (XE1),
Trigger (XE2), thyristor (SC1), (S
Trigger circuit for conducting C2), (ST1), (ST
2) is a stop circuit that makes the thyristors (SC1) and (SC2) non-conductive and stops the light emission of the xenon tubes (XE1) and (XE2). In addition, xenon tube (XE
1) is for pre-irradiation, and a filter (FLT) that transmits near-infrared light and cuts visible light having a shorter wavelength than near-infrared light is provided at the light emission position of this xenon tube (XE1). Therefore, the person of the subject does not feel dazzling when the preliminary irradiation is performed.

In Fig. 2, when the terminal (O13) of the microcomputer (MCO2) becomes "High", the data can be exchanged between the camera and the electronic flash device. And the distance of 50 µsec from the electron (O14) of the microcomputer (MCO2). When the pulse is output, this pulse is sent to the flash device via terminals (JB2) and (JF2), and the mode discrimination circuit (FMS) shown in Fig. 3 transfers the data from the flash to the camera by this pulse. Mode (DO
M) is set to “High.” Then, the data output circuit (DOU) in FIG. 3 becomes operable. When a clock pulse is output from the clock pulse output terminal (SCP) of the microcomputer (MCO2), The clock pulse is input to the terminal (SCP) of the data output circuit (DOU) of FIG. 3 via the terminals (JB2) and (JF2), and power is supplied by the electronic flash device based on this clock pulse. Power supply signal, a signal to the terminal (PCH) indicating that the electronic flash device is ready for pre-irradiation, a charge completion signal to the terminal (CHC), and whether or not the dimming operation has been performed. Signals to the indicated terminal (FDC) are sequentially output from the terminal (SOU), and the terminals (JF3) and (JB
It is sent to the camera side via 3). Other data to be sent include, for example, the maximum / minimum light emission amount data of the flash, the aperture value set by the flash, the bounce state, and whether or not the flash is a multi-flash. Then, when the data transfer is completed, a pulse is output from the terminal (r2), the mode discrimination circuit (FMS) enters the initial state via the OR circuit (OR12), and the terminal (DOM) becomes "Low".

Next, from the terminal (O14) of the microcomputer (MCO2), 100 μs
When a pulse of ec width is output, the mode discrimination circuit (FM
S) makes the terminal (DIM) "High. Then the data input circuit (DIM) becomes active. And the microcomputer (MCO2) of the camera body outputs a clock pulse from the terminal (SCP) and outputs this clock pulse. Based on this, data such as aperture value for flash photography, exposure time, film sensitivity shooting distance, etc. is output from the terminal (SIO) to the data input circuit (DIM) via the terminals (JB3) and (JF3). Then, the display based on the read data is displayed on the display circuit (DSP).

Microcomputer (MCO2) to start exposure control operation
Output a pulse of 150 μsec width from the terminal (O14). Then, the mode discrimination circuit (FMS) sets the terminal (FLM) to "Hi".
gh As a result, the light emission control circuit (FLC) is activated and light emission control is performed. When the front contact of the focus plane shutter of the camera is completed and the X contact (SX) of the camera is closed, a light emission start signal is input from the terminals (JB4) and (JF4) to the terminal (STA) and the terminal (α1).
Emits a light emission start signal. At the same time, the terminal (α3) is inverted from “High” to “Low”, and this signal is sent to the camera side through the terminals (JF3) and (JB3). ", The photometric integration circuit (not shown) in the circuit (FLB) is reflected from the subject illuminated by the flash light,
The amount of light that has passed through the aperture (not shown) of the taking lens is integrated, and when the integrated amount reaches an analog value corresponding to the film sensitivity from the analog output terminal (ANO), the terminal (JB2)
A pulse for stopping light emission is output to. This pulse is transmitted through the terminal (JF2) to the terminal (S) of the light emission control circuit (FLC).
TP). Then, a light emission stop signal is output from the terminal (α2) and the light emission of the xenon tube (XE2) is stopped. Further, the light emission stop signal from the terminal (α2) is also sent to the display circuit (FDP) and the X contact (SX) is opened when the exposure control operation is completed. Based on this signal, the X contact (SX) is opened. The terminal (df) becomes “High” for a certain time from
During this period, it is displayed that the dimming operation has been performed. Further, this signal is also sent to the camera side via the data output circuit (DOU). When the X contact (SX) is opened, a pulse is output from the terminal (r3), the mode discrimination circuit (FMS) is reset via the OR circuit (OR12), and the terminal (FLM) becomes "Low". .

In the preliminary irradiation mode, (O of the microcomputer (MCO1)
When the signal of “High” is output from the terminal (O3) in the state of 1) being “High”, a pulse is output from the one-shot circuit (OS1) and the pulse is output from the AND circuit (AN1). Is output. This pulse is input to the AND circuit (AN20) of FIG. 3 through terminals (JB1) and (JF1). At this time, the output of the D flip-flop (DF21) becomes "High", the output of the comparator (AC23) becomes "High", and the OR circuit (OR
Since the output of 20) is "High", the pulse input to the AND circuit (AN20) is output from the AND circuit (AN20) .This pulse is sent to the trigger circuit (TR1) and pre-irradiated by the xenon tube (XE1). Then, the pulse from the AND circuit (AN20) sets the flip-flop (RF20) so that the reset state of the counter (CO6) is released and the counter (CO6) starts counting. After a certain time elapses, the terminal (f1) of the decoder (DE6) becomes "High" and a pulse is output from the one-shot circuit (OS22).
This pulse is sent to the light emission stop circuit (ST1) to stop the preliminary irradiation by the xenon tube (XE1). Further, when the terminal (f1) of the decoder (DE6) becomes "High", the flip-flop (RF20) is passed through the OR circuit (OR22).
Are reset, the counter (CO6) is reset, and the terminal (f1) becomes "Low". The output pulse of the AND circuit (AN20) is a D flip-flop (DF
It is sent to the clock pulse input terminal of 20), the "High output" of the comparator (AC23) is latched, and the Q output of the D flip-flop (DF20) becomes "High".

Even when the charge voltage of the main capacitor (C2) is lowered and the output of the comparator (AC23) is "Low" when the second pulse is output from the AND circuit (AN20), at the time of the first light emission. D flip-flop (DF2
Because the Q output of 0) is "High", the OR circuit (OR2
The output of 0) is "High" and the AND circuit (AN2
A pulse is output from 0). Then, the pulse causes the same light emitting operation as described above. Also, the Q output of the D flip-flop (DF21) becomes “High” by this pulse. Then, the pulse is output from the one-shot circuit (OS20), and the pulse is output from the one-shot circuit (SO21) at the falling edge of this pulse. Then, the D flip-flops (DF20) and (DF21) are reset to return to the initial state.

FIG. 4 is a flowchart showing the operation of the microcomputer (MCO2) shown in FIG. The operation of the system shown in FIG. 2 will be described below with reference to this flowchart. When the photometric switch (S1) is closed and an interrupt signal is input to the terminal (it), the microcomputer (MCO2) starts its operation. First, the flag L
It is determined whether MF is "1". This flag LMF is set to "1" if the exposure control data has been calculated, but it has not been calculated yet when the photometry switch (S1) is closed and an interrupt signal is input. Flag L
Since MF is "0", the process proceeds to step S2. S2
In the step of, the terminal (O12) is set to “High” to turn on the transistor (BT1) to start power supply through the power supply line (+ V). Data is captured and the conversion coefficient (KD) required for automatic focus adjustment is input to the terminal (OP10).
In addition, the correction data for the focus position of the near infrared light and the visible light (I
RD) to terminal (OP11), backlash data (B
LD) is output to the terminal (OP12), and the input terminals (IP2) and (IP of the microcomputer (MCO1) for automatic focus adjustment are output.
3), (IP4). Then, the output terminal (O10) is set to "High. This signal is input to the interrupt terminal (it2) of the microcomputer (MCO1), and when this signal is output, the microcomputer (MCO1) starts its operation.

In step S6, a block (ED
O), and then serial I / O operations to serially capture the data from the flash. Then, in step S8, it is determined whether or not a signal capable of preliminary irradiation is input, and if input, the terminal (O16)
To "High", and if not input, set the terminal (O16) to "Lo".
Set to w "and move to step S11.

In step S11, the terminal (O18) is set to "High. When this signal is read by the input terminal (i5) of the microcomputer (MCO1), the microcomputer (MCO1) performs AD conversion operation by the microcomputer (MCO2). The focus detection operation by illuminating the xenon tube is stopped and the microcomputer (MCO2) is connected to the input terminal (i15).
Has "High", and if "High", this pin (i15) has "Low". The output terminal (O8) of the microcomputer (MCO1) is connected to the input terminal (i15), and this terminal is "High" while the xenon tube emits light to perform the focus detection operation. Therefore, the microcomputer (MCO2) uses this input terminal
While (i15) is "High", AD conversion operation is not performed. When the terminal (i15) is "Low" or "Lo"
When it becomes "w", the photometric output from the photometric circuit (LMC) is AD converted, and the terminal (O18) is set to "Low" to output a signal indicating that AD conversion is in progress. Now you have captured all the data required for the exposure calculation.

Next, in steps S15 and S16, exposure calculation for steady light and flash light is performed. Then, it is determined whether the flag RLF is "1". If RLE is "1", it means that the process has moved to this step despite the interruption by the release switch (S2), and the process moves to step S33 which will be described later for release. On the other hand, if the flag RLF is "0", it means that the process is moved to this step by the interruption by the photometric switch (S1), and the process is moved to step S18, and the flag LMF is set to "1" to enable the interruption. Step 20
Move to. In step S20, serial input / output operation is performed to send data to the electronic flash device (FLC). Step S
In step 21, it is determined whether or not the power supply signal is read from the electronic flash device, and if the power supply signal is read, the flash light data is sent to the display unit (EXD). Move to S40. Then, in step S40, it is determined whether or not the terminal (i12) is "High" while the photometric switch (S1) remains closed. If "High", the process returns to step S3 to repeat the same operation as described above. . On the other hand, when it is determined in step S40 that the terminal (i12) is "Low", the terminal (O10) is set to "Low" to stop the automatic focus adjustment operation, set the flag LMF to "0", and set the terminal to "0". (O12) to "Lo
w ”to make the transistor non-conductive and the power line (+
The power supply from V) is stopped, the display on the display unit (EXD) is turned off, and the microcomputer (MCO2) stops operating.

When an interrupt signal is input while the exposure control data is calculated, the process proceeds to step S31 and terminals (O10), (O16)
Is set to “Low” and a signal to stop the automatic focus adjustment operation is output. Then, the flag RLF is set to "1" to indicate that the interrupt has been performed by the release switch (S2).
Then, the process proceeds to step S33. In step S33, it is determined whether the input terminal (i11) is "High". If "High", the process proceeds to step S3 for exposure calculation, and if "Low", the process proceeds to step S34 for exposure control. This input terminal (i11) is the output terminal (O of the microcomputer (MCO1)
7), this terminal outputs the following signals. First, during the automatic focus adjustment operation that does not use preliminary irradiation, a "High" signal is output until the movement of the taking lens is completely stopped, and a "Low" signal is output when it is completely stopped. While the terminal (i11) is "High", the microcomputer (MCO2) does not shift to the exposure control operation, so that it is possible to prevent an erroneous operation such that the exposure control operation is executed while the photographing lens is moving. On the other hand, when performing the automatic focus adjustment operation using the preliminary irradiation, even if the automatic focus adjustment operation is stopped for a fixed time (for example, 200 msec) from the time when the preliminary irradiation is performed, the automatic focus adjustment operation is automatically performed by the microcomputer (MCO2). Even if a signal to stop the focus adjustment operation is input, “High
Signal is output. Therefore, the exposure control operation is not performed for at least a fixed time from the time when the preliminary irradiation is performed,
The calculation operation for exposure control is repeated. This is executed when the A-D conversion of the output of the photometric circuit (LMC) and the preliminary irradiation are mistakenly overlapped, and the exposure is controlled by the exposure control value based on the incorrect A-D conversion data. Will be prevented. Further, even if the pre-illuminated flash light is near-infrared light, the person as the subject may feel dazzling and may close the eyelids. However, after a certain period of time, the eyelids will be opened and you will be able to shoot with a normal expression.

When the terminal (i11) becomes "Low", the process proceeds to step S34, it is determined whether the power supply signal is input from the flash, and if it is input, the exposure control data for the flash light is input to the control unit (EXC). If the power supply signal is not input, the exposure control data for stationary light is sent to the control unit (EXC). Then, the exposure control operation is started. Then, the microcomputer (MCO2) waits until the exposure control operation is completed, the reset switch (S4) is opened, and the terminal (i10) becomes "Low". Then, when the terminal (i10) becomes "Low", it is determined in step S40 whether or not the photometric switch (S1) is closed, and if it is closed, the process proceeds to step S3 described above to capture data, calculate The display operation is repeated, and if the photometric switch (S1) is not closed, the microcomputer (MCO2) stops the operation after proceeding to step S41 and performing the same operation as described above.

FIGS. 5-1 to 5-3 are flowcharts showing the operation for automatic focus adjustment by the microcomputer (MCO1). The operation of the circuit of FIG. 2 for automatic focus adjustment will be described below with reference to FIGS. 5-1 to 5-3. When the terminal (O10) of the microcomputer (MCO2) becomes "High" to start the automatic focus adjustment operation, an interrupt signal is input to the terminal (it2) and the operation of the microcomputer (MCO1) starts. First, the step # 1 Then, the terminal (O7) is set to "High" in order to notify the microcomputer (MCO2) that the automatic focus adjustment operation is being performed. Then, the interrupt by the terminal (it1) and the counter is enabled, the interrupt by the timer is disabled, the terminal (O3) is set to “High”, and the CCD (F
The charge accumulation operation by MD) is started. In the following description, the reference numerals indicating counters and registers that are not enclosed in parentheses are those in the microcomputer.

In step # 4, the contents of a counter COR for counting an external or internal clock in the microcomputer (MCO1) are set in the register ECR1. As will be described later, this is data necessary for calculating the amount of movement of the lens during focus detection in order to perform focus detection while moving the taking lens, and is not necessary at the time of the first measurement. #
In step 5, it is determined whether the flag FLF is "1". This flag is set to "1" when the preliminary irradiation by the flash is performed, and is set to "0" when the measurement using only the stationary light is performed. During the first measurement, the preliminary irradiation is not necessarily performed, the flag FLF is "0", and the process proceeds to step # 6.

In step # 6, a fixed value Ka is set in the timer register TIR1. The register TIR1 is a register for counting time by software, and there is a timer counter TIC that counts the internal clock independently of software, and when the content of this counter TIC becomes "0", a timer interrupt is taken. . And register ECR4
The contents of the counter COR are set in and the fixed value K1 is set in the timer register TIR2. This register TIR
Similarly to TIR1, 2 is a register for counting time by software. Then, the operation of subtracting "1" from the content of the timer register TIR2 and determining whether the content of the register TIR2 is "0" is repeated and waits for a fixed time. After a certain period of time, in step # 11, it is determined whether or not the input terminal (i3) is "Low", and if it is "Low", the automatic focus adjustment operation is performed from the microcomputer (MCO2) as described above. Since a signal for stopping the operation is input, the operation for stopping the automatic focus adjustment operation starting from step # 209 is performed. On the other hand, terminal (i3)
Is "High", the flag FPF is set to "1" in step # 12.
Determine whether or not. This flag FPF is "1" when the motor (MO) is stopped as in the first measurement. Therefore, if the flag FPF is "1" and the motor (MO) is stopped, the process proceeds from step # 12 to step # 15, and at step # 6, the fixed value Ka is set.
Subtract "1" from the register TIR1 in which
It is determined whether or not the content of TIR1 has become "0". If not "0", the process returns to step # 7 and the same operation is repeated. When the output of the comparator (AC1) in FIG. 2 is inverted to "High" while this operation is repeated, a transfer pulse is output from the terminal (φT) of the control circuit (COC), and this pulse is an interrupt terminal. When input to (it1), the microcomputer (MCO1) starts operation from step # 24, and when it is determined in step # 16 that the content of the register TIR1 has become "0", # 21. At the step, a pulse is output to the terminal (O2) to forcibly stop the accumulation operation as described above, the flag TOF is set to "1", the operation is terminated, and an interrupt signal to the terminal (it1) is waited for. Here #
The time from when the accumulation operation is started in step 3 to when it is determined in step # 16 that the content of the register TIR1 is "0" is a fixed time, and the accumulation time is longer than this. It doesn't happen.

Flag FP when the motor (MO) is driven
Since F is "0", the process proceeds from step # 12 to step # 13. In step # 13, the counter CO
The contents of R are set in the register ECR5. Then, in step # 14, the contents of the register ECR4 which set the contents of the counter COR in step # 7 and this register ECR are set.
Compare with the contents of 5. A certain time has passed between the steps of # 7 and # 13, and if the lens does not move during this time, no clock pulse is input from the encoder (ENC) and (ECR4) = (ECR5). ing.
Therefore, even if the motor (MO) is driven, the lens has reached the end position (infinity position or closest position) and the lens has stopped moving. In this case, the flag LSF ("0" during normal focusing operation, a low contrast signal indicating that the contrast of the subject image is low is output, and "1" when scanning a range position other than low contrast. If the value is "1", the scan is being performed at low contrast. # 15
If it is "0", the normal focusing operation is being performed, and the process proceeds to step # 63.

If the flag FLF is "1" in the step # 5, the flash light is pre-illuminated, and at this time, the process proceeds to the step # 17. At this time, a fixed value Kf is set in the register TIR1 and "1" is subtracted from the register TIR1 to determine whether the terminal (i3) is "Low". If "High", the content of TIR1 is "0". If it is not "0", the operation of returning to step # 18 is repeated, and if the content of TIR1 becomes "0" in step # 20, the operation proceeds to step # 21 and the above-mentioned operation is performed. In this pre-irradiation mode, the limit of the storage time is much shorter than in the case of the stationary light mode.This is configured in this way for the following reasons. Uses light in the near-infrared region so that the human being, who is the subject, does not feel dazzling.On the other hand, when pre-irradiation is not performed, it is measured with ambient light, but ambient light is generally white light.
Therefore, when both lights are mixed and measured, the effect of chromatic aberration on the defocus amount cannot be corrected unless the mixing ratio is known. Therefore, in the pre-irradiation mode, in order to prevent the stationary light component from being measured as much as possible, the longest accumulation time is set to be almost equal to the light emission time of the xenon tube (EX1) so that accurate chromatic aberration can be corrected. It has become. Further, in the pre-irradiation mode, the motor (MO) is not driven during the measurement, so that the end detection operation of whether the lens has reached the end is not performed.

When a transfer pulse is output from the terminal (φT) of the control circuit (COC) and an interrupt signal is input to the terminal (it1), the operation from step # 24 is started. In step # 24, the terminal (O8) is set to "Low" so that the microcomputer (MCO2) can perform AD conversion. Then, it is possible to interrupt the terminal (it1) and set the terminal (O3) to "Low" to make the counter CO
The contents of R are taken into the register ECR2. This is data for correcting an error due to the movement of the lens when the lens is moved during measurement. Next, the A / D converted data of the amount of light received by each light receiving unit output from the control circuit (COC) is sequentially fetched, and the A / D converted data corresponding to all the light receiving units is fetched. Transition. In step # 29, it is determined whether the flag FLF is "1",
If it is "1", an interrupt by a timer (a function will be described later) is enabled and the process proceeds to step # 32. If it is not "1", it is determined whether the flag TOF is "1".
The flag TOF becomes "1" in step # 22 when the storage time has reached the limited time. Therefore, F
When the LF is “0” and the TOF is “1”, it means that the ambient light mode has a low brightness, so that the flag LLF is set to “1” in step # 31, and otherwise the flag LLF is set in step # 32.
Is set to "0", and the flag TOF is set to "0" in # 33.
In # 34, the degree of correlation between the two rows of light receiving portions is obtained based on the output from the light receiving portion (FMD), and the defocus amount and the defocus direction are calculated from this correlation degree. This operation is performed, for example, as proposed in US Pat. No. 4,333,007. The calculated defocus amount is | LD |
When LD> 0, the direction of defocus is the front pin, LD
When <0, it is the rear pin.

In step # 35, it is determined whether or not the flag FLF is "1", and when the FLF is "0" and the measurement is performed with the stationary light (visible light), the calculated data LD is directly changed to the correct value L.
If Dt and FLF is “1”, it is a pre-irradiation mode. At this time, since measurement with near infrared light is performed,
In order to correct only the difference between the in-focus position with visible light and the in-focus position with near-infrared light, that is, IRD, LD-IRD is calculated, and this calculated value is set as the correct defocus amount LDt. Although the data sent from the lens is used as it is as the data IRD, for example, the lens stores correction data for a specific wavelength, data of the wavelength of the preliminary irradiation light source is obtained, and this wavelength is used. The correction data may be converted into data corresponding to, and the defocus amount may be corrected by the converted correction data.

In # 38, it is determined whether the terminal (i3) is "Low" and "Low"
If so, the process proceeds to step # 209 as described above. On the other hand, if the terminal (i3) is "High", then it is determined whether or not the measured data has low contrast. This low contrast is determined by each light receiving unit of the light receiving element array between adjacent light receiving units. The total of the absolute values of the output differences is calculated, and when the total is less than or equal to a predetermined value, it may be determined that the contrast is low .. In the case of low contrast, the light distribution states of the two light receiving element rows are compared. Since the defocus amount is calculated by doing so, the calculated defocus amount is unreliable.
The operation shifts to step 0 and the operation for low contrast is performed. If it is determined in step # 39 that the contrast is not low, the flag LCF1 is set to "1" in step # 40.
Determine whether or not. Then, the flag LCF1 is "1".
If so, the previous measured value is low contrast, and in this case, it is determined in step # 41 whether the flag FLF is "1". If the flag FLF is "1", the preliminary irradiation by the flash is performed in this measurement, so the operation from step # 170 is performed. On the other hand, if the flag FLF is "0", the previous measurement was low contrast, and the contrast was sufficient in this measurement without performing preliminary irradiation. At this time, the flags LCF1, L
CF2, SEF1, SEF2, and LSF are set to "0", it is determined whether the flag TIF is "1", and if not "1", the operation from # 50 is performed. In this case, the measured value was low contrast, and the measured value was not low contrast during the measurement while moving the lens until the measured value was not low contrast (hereinafter referred to as low contrast scan mode). This is the case, and at this time, the operation moves to move the lens based on the defocus amount from step # 50. If the flag TIF is "1" in step # 43, the lens is scanned in the low-contrast scan mode over the entire area, and a measurement value other than low contrast is not obtained during the measurement, and the lens is stopped for a certain period of time. Is repeated (hereinafter referred to as the low-con stopped mode). In this case, the counter CO
Since R is in a mode (timer mode) for counting the internal clock of the microcomputer (MCO1), the event count mode (mode for counting clock pulses from the encoder (ENC)) is set and the flag FPF is set to "1", TIF. Is set to "0" and the process proceeds to step # 50 and then to the step from # 50 to perform the same operation as when the first measurement value is not low contrast.

When the flag LCF1 is "0" in the step of # 40, or when the flag TIF is "0" in the step of # 43, or when the step of # 46 is followed by the step of # 50. In step # 50, the defocus amount LDt is multiplied by the conversion coefficient KD to calculate the lens movement amount ND. next,
LID is data in a range that can be regarded as in-focus, and is multiplied by a conversion coefficient KD to move the lens movement amount IFD in the in-focus region.
To calculate. In the step of # 52, the flag FPF is "1".
If it is "1", the process proceeds to step # 75, and if "0", the process proceeds to step # 53. Therefore, the motor (M
If O) is driven, the process proceeds to step # 53, and if the motor (MO) is not driven, the process proceeds to step # 75.

In the step of # 53, the register ECR1 which takes in the contents of the counter COR at the start of charge accumulation in the light receiving unit (FMD)
Then, the amount τ of movement of the lens during charge accumulation is calculated by obtaining the difference τ in content output from the register ECR2 that has taken in the content of the counter COR at the end of accumulation. Then, the contents of the counter COR at this point are set in the register ECR3, the difference t between the contents of the registers ECR2 and ECR3 is obtained, and the movement amount t of the lens during the defocus amount calculation is calculated. The calculated defocus amount is regarded as a value based on the measurement value in the middle of the movement of the lens during the accumulation time, and the calculated lens movement amount ND is τ / 2 + t from the measurement point. Is moving, and in step # 56, | ND | − (τ / 2 + t) = NDc is calculated to correct the moving amount. In step # 57, the corrected movement amount data | NDc | and in-focus area data IFD are compared, and if | NDc | IFD, it means that the focus area has been entered and the process proceeds to step # 58. Then terminal (O4),
(O5) is set to "Low" to stop the motor (MO), flags IFF and FPF are set to "1", and the process returns to step # 2 to perform focus detection for confirmation.

When it is determined in step # 57 that | NDc |> IFD, the process proceeds to step # 61 to set the contents of the counter COR in the register ECR3, and the contents of the counter COR and the counter COR at the time of step # 27. The contents of the register ECR2 in which the contents are set are compared. And (ECR2)
If it is determined that = (ECR3), the lens has reached the end, and the terminal (O
4) and (O5) are set to "Low" to stop the rotation of the motor (MO) and flags ENF and FPF are set to "1".
Return to step and repeat the measurement.

When it is determined in step # 62 that (ECR2) ≠ (ECR3), it is determined in step # 66 whether the correction data NDc has a negative value. If the value is negative, the correction amount (τ / 2 + t) is larger than the calculated movement amount | ND |, which means that the lens has passed the in-focus position. Therefore, in this case
Go to step 71 and set terminals (O4) and (O5) to “Lo
As w ", the rotation of the motor (MO) is stopped and the flags SCF and FPF are set to" 1 "to return to step # 2 and focus detection for confirmation is performed.

If it is determined in step # 66 that NDc> 0, then it is determined in step # 67 whether the lens driving direction is the retraction direction (ND> 0). Then, if ND> 0, it is determined whether the flag SIF is "1" in step # 68, and if ND <0 (feeding direction), in step # 69. This flag SIF is "1" if the moving direction of the lens at this point is the retracting direction, and "0" if it is the retracting direction. Therefore, the flag SIF is "0" in the step of # 68, or the flag SIF is in the step of # 69.
Is "1", it means that the moving direction of the lens at this time and the calculated moving direction of the lens are reversed, and the process proceeds to step # 71 described above to stop the motor (MO) and set the flag SCF. , FPF is set to "1" and the process returns to step # 2 to perform focus detection for confirmation. On the other hand, if the direction is not reversed, the data NDc calculated in the step # 56 is set in the counter COR, the process returns to the step # 2, and the next measurement is performed.

When the flag FPF is "1" in step # 52, the motor (MO) is stopped and focus detection is performed without preliminary irradiation. In this case, first | ND | IFD
If | ND | IFD is determined, the in-focus display is performed in step # 76, and the operation is stopped by shifting to step # 211 described later. On the other hand, if | ND |> IFD, the process proceeds to step # 80 in FIG. 5-2. In steps # 80 to # 82, the flag IF
It is determined whether F, SCF and ENF are "1". These flags are "1" when the moving lens is once stopped and focus detection for confirmation is performed as described above, and any one of the flags is "1".
If so, move to step # 84. # 84 to # 86
In the step of, the same as the steps of # 67 to # 69 described above, it is determined whether or not the direction in which the lens has been driven by that time and the direction obtained by the focus detection this time are coincident with each other and inverted. If so, the flag SIF is inverted in steps # 87 and # 88, and the value obtained by adding the backlash data (BLD) to the data of the movement amount | ND | is set in the counter COR in step # 91. Go to step. On the other hand, if the directions are the same, it is determined in step # 89 whether the flag ENF is "1". If the flag ENF is "1", it means that the lens has reached the end as described above. At this time, since the lens cannot be driven in the calculated direction, a warning is displayed. The operation is stopped by shifting to step # 211 described later. On the other hand, if the flag ENF is "0", the movement amount data | ND | is set in the counter COR in the step # 95 and the process shifts in the step # 96.

When the flags ENF, SCF and IFF are all "0", it is the case of the first focus detection operation, and the moving direction is determined in step # 92. If ND> 0, the flag SIF is set to "1", N.
If D <0, SIF is set to "0", the movement amount data | ND | is set in the counter COR in step # 95, and the process proceeds to step # 96.

In step # 96, the event count mode is set and the data set in the counter COR is subtracted by the clock pulse input from the encoder (ENC). Then, depending on the moving direction, the terminal (O4) or (O
5) is set to "High" to start the rotation of the motor (MO), set the flags FPF, IFF, SCF and ENF to "0", and display the front pin or the rear pin according to the contents of the flag SIF. Returning to step 2, the next focus detection operation is performed.

If it is determined in step # 39 that the measurement result has low contrast, the process proceeds to step # 110. In step # 110, it is determined whether the flag FPF is "1". If it is "1", it means the first measurement, and the process proceeds to step # 111. In step # 111, it is determined whether the flag LLF is "1". This flag LLF is # 29-
As described in step # 33, this flag is "1" when the subject brightness is low.
If F is "1", the process proceeds to # 112, and if F is "0", the process proceeds to # 121.

In step # 112, it is determined whether the terminal (i2) is "High". If the terminal (i2) is "Low", it is determined in step # 113 whether the flag SEF2 is "1". As will be described later, the flag SEF2 is a flag that becomes “1” when the lens scans the entire area in the low contrast scan mode, so that if it is “1”, the process proceeds to step # 144 to be described later. If the flag SEF2 is "0", the low contrast scan mode from # 121 is entered.

If it is determined in step # 112 that the terminal (i2) is "High", it is possible to emit light for pre-irradiation at this time, and the operation proceeds to pre-irradiation mode operation from # 114. In step # 114, flags FLF, FFF, LC
F1 is set to "1" and FPF is set to "0". Flag FL
F is a flag for indicating the preliminary irradiation mode, F
FF is a flag that becomes "1" when the first measurement is performed in the preliminary irradiation mode, and LCF1 is a flag that becomes "1" immediately when it is determined that the contrast is low. In the step of # 115, the terminal (O1) is set to "High" so that the focus detection operation is performed in the preliminary irradiation mode, and (O8) is set to "High" to perform the operation in the preliminary irradiation mode. By A-
Send a signal to instruct the D conversion operation to be prohibited. Then, it is determined whether or not the signal indicating that the A-D conversion is being performed is input from the microcomputer (MCO2) to the terminal (i5), and if the terminal (i5) is "High and the A-D conversion is being performed". After the A-D conversion is completed and (i5) becomes "Low", the focus detection operation of pre-irradiation is performed.

In step # 117, a constant value T0 is set to a timer counter TIC for performing preliminary irradiation and counting a constant time (for example, 200 msec). This counter T
The IC counts down based on the clock pulse inside the microcomputer (MCO1), and when the internal becomes "0", the timer interrupt is taken if it is possible, and the operation of step # 260 described later is performed. Return to the original flow. In # 118, the flag RSF is set to "1". This flag RSF is set to "1" until a fixed time elapses after the preliminary irradiation is performed, and is set to "0" in the step of # 260 when the fixed time elapses and the timer is interrupted. While the flag RSF is "1", the output terminal (O
7) is "High" and the microcomputer (MCO2) does not shift to the exposure control operation. When the timer interrupt is disabled, the interrupt operation is not possible even if the timer TIC becomes "0". If it is not performed and the timer interrupt is enabled, the timer interrupt is immediately applied and the operation by the timer interrupt is performed.

When the flag RSF is set to "1" in step # 118,
Returning to the step of # 2, the focus detecting operation for performing the preliminary irradiation is executed.

When the flag LLF is "0" in the step of # 111, or when the flag SEF2 is "0" in the step of # 113, the process shifts to the step of # 121 to start the operation in the low contrast scan mode. First, the flags LCF1, LCF2, LS
F is set to "1", it is determined which defocus direction is calculated next, and the flag S is determined according to the determined direction.
IF is set to "1" or "0" and the lens is moved in that direction. Then, a warning is displayed, the flag FPF is set to "0", the interrupt signal is not accepted when the content of the counter COR becomes "0", the process returns to step # 2, and the next measurement is performed. Let

If the flag FPF is "0" in step # 110, # 140
Then, it is determined whether the flag FLF is "1". If the flag FLF is "1", it means that the focus detection result in the preliminary irradiation mode is low contrast. At this time, the terminal (O1) is set to "Low" and the process proceeds to step # 200 in Fig. 5-3. And # 200
In the step 1), it is determined whether the flag FFF is “1”, and if the flag FFF is “1”, the first focus detection is performed in the preliminary irradiation mode. At this time, the flag FFF is set to “0”. Then, the process returns to step # 115 described above, and the operation in the second preliminary irradiation mode is performed. on the other hand,
If the flag FFF is "0" in step # 200, it means that the second measurement is performed in the preliminary irradiation mode. At this time, a warning is displayed and the timer interrupt is enabled.
The process moves to step 211 to stop the operation.

If the flag FLF is "0" in step # 140, then it is determined in step # 142 whether the flag TIF is "1". If the flag TIF is "1", the low contrast stop mode is set and the process returns to step # 2 to perform the next measurement. If the flag TIF is "0" in step # 142, then it is determined in step # 143 whether the flag SEF2 is "1". If the value is "1", it means that only the low-contrast focus detection value is obtained even if the lens scans the entire area in the low-con scan mode. At this time, the operation of the low-con stop mode from # 144 is started. To do.

In the step # 144, the fixed data T1 is stored in the counter COR.
To the timer mode in which the contents of the counter COR are subtracted by the clock pulse inside the microcomputer (MCO1), the flag TIF is set to "1" and the counter interrupt is enabled, and the procedure returns to step # 2 to perform the measurement. Let In this mode, focus detection is repeated with the lens stopped for a certain period of time, and if a measurement value that is not low contrast is obtained during this period, the lens is driven by the movement amount data based on this measurement value and the focus of low contrast is maintained for a certain period of time. When only the detected value is obtained, the same operation as the first measurement is performed again.

If it is determined in step # 143 that the flag SEF2 is "0", then in step # 150 the flag LCF1 is set.
It is determined whether is "1". When it is not "1", the focus detection value up to the previous time is not low contrast, but is suddenly low contrast in this focus detection. At this time, the process shifts to step # 151, the flag LCF1 is set to "1", the LCF2 is set to "0", and the terminal (O
4) and (O5) are set to "Low" to stop the operation of the motor (MO), the flag FPF is set to "1", the process returns to # 2 and focus detection is performed again. Flag LC in step # 150
If F1 is "1", then in step # 155 the flag LC
It is determined whether F2 is "1". And the flag LCF
If 2 is "0", the previous focus detection value suddenly becomes low contrast, and the current focus detection value obtained by re-performing focus detection is also low contrast. Therefore, in this case, the operation for starting the low contrast scan mode described above is performed from step # 121.

When the flag LCF2 is "1" in step # 155, the operation is in the low-con scan mode. In this case,
In step 156, the contents of the counter COR are registered in the register EC.
In step # 157, it is determined whether or not the contents of the register ECR2, which is set to R3 and the content of the counter COR is fetched in step # 27, matches. If they do not match, the lens has not reached the end, and therefore the process returns to step # 3 to perform the focus detection operation. On the other hand, register EC
If the contents of R2 and ECR3 match, the lens has reached the end, and the motor (M
O) is stopped. Then, in step # 159, it is determined whether or not the flag SEF1 is "1". If the flag SEF1 is "1", it means that the lens has reached one end, and therefore the lens has reached both ends and the entire area is reached. Has been scanned. Therefore, at this time, the flag SEF2 is set to "1" and the process proceeds to the step of # 112 to confirm whether or not the preliminary irradiation is possible from the flash. If the preliminary irradiation is possible, the preliminary irradiation mode is changed to the preliminary irradiation. If is not possible, it shifts to the low contrast stop mode.

If the flag SEF1 is "0" in the step of # 159, it means that the lens has reached the terminal end for the first time in the low contrast scan mode. In this case, the flag SIF is reversed and the rotation direction of the motor (MO) is also reversed. Set SEF1 to "1" and return to step # 3 to perform measurement.

If the flag FLF is "1" in step # 41, it means that the result of measurement in the preliminary irradiation mode is not low contrast. At this time, the process proceeds to step # 170 in Fig. 5-3. In step # 170, the terminal (O1) is set to "L".
ow ”, and the lens movement amount ND and the focus area IFD are calculated from the defocus amount data LDt and the focus area data obtained in step # 37 and the conversion coefficient KD.
Then, if | ND | IFD is set in the step # 173, the in-focus display is performed, the flag FFF is set to "0", and the flow shifts to the step # 211 to end the operation.

When it is determined in step # 173 that | ND |> IFD, the process proceeds to step # 180, where | ND | is set to the counter COR, the event count mode is set to enable the counter interrupt, and the timer interrupt is disabled. And And flag F
Whether the FF is "1" is determined, and if it is "1", it means that the first measurement is performed in the preliminary irradiation mode. At this time, the process directly proceeds to step # 188. on the other hand,
If FFF is "0", it means that the second measurement is performed. At this time, the process proceeds to step # 178, and the data LND in the vicinity of the focus is multiplied by the conversion coefficient KD to calculate the data NFD in the vicinity area. Then, in step # 179 |
It is determined whether ND | NFD. ｜ N
When D |> NFD, it is considered that normal operation is not performed in the first focusing operation, or the second focus detection result is unreliable. Furthermore, it is difficult to accurately move the lens to the in-focus position with only one movement of the lens due to variations in the conversion coefficient, and it is considered that the in-focus operation cannot be performed basically. Therefore, in this case, the process proceeds to step # 201 to issue a warning, then the timer interruption is enabled, and the process proceeds to step # 211 to stop the operation.

If it is determined in step # 179 that | ND | NFD is determined, it is considered that normal control operation is possible. Therefore, determine the moving direction next, and check whether the moving direction is reversed from the previous one. To determine. Then, if it is determined that it is reversed, | ND | + BLD is calculated to correct the movement amount data | ND | by the amount of backlash data, and this data is reset to the counter COR. On the other hand, if it is not inverted, the data set in step # 180 remains unchanged and the process proceeds to step # 188. Then, the direction of movement is determined, a signal corresponding to that direction is set in the flag SIF, and the motor (MO) is rotated in the determined direction.

Next, after setting the contents of the counter COR in the register ECR2 and waiting for a certain period of time, it is determined whether or not the terminal (i3) is "Low". If it is "Low", the timer interrupt is enabled and the step # 209 is performed. Move to. On the other hand, if "High", the process proceeds to # 196 and the contents of the counter COR are set in the register EC.
Set to R3. Then, in step # 197, register E
It is determined whether or not the contents of CR2 and ECR3 match. If (ECR2) ≠ (ECR3), ECR3
The contents of is set to ECR2 and the process returns to step # 194.
Therefore, in the preliminary irradiation mode, if data is obtained by measurement, the lens is driven based on this data, but the measurement operation is not performed during this driving. When the lens moves by the calculated amount of movement, a counter interrupt is applied and the lens is stopped, as will be described later, and if it is the first time, the operation moves to the second time, and if it is the second time, the focus display is performed. Stop the operation. When it is detected that the lens reaches the end in step # 197, terminals (O4), (O5)
Set to “Low” to stop the motor. Then, in step # 200, it is determined whether the flag FFF is "1",
If it is "1", it is the first measurement, so set the flag FFF to "0".
As a result, the procedure returns to step # 115 described above, and the measurement is performed in the second preliminary irradiation mode. On the other hand, if it is determined in step # 200 that the flag FFF is "0", this means that the lens has reached the end by the second operation. In this case, a warning is displayed and the timer is displayed. Enables interrupts and moves to step # 211 to stop operation.

When the content of the counter COR becomes "0", the counter is interrupted and the operation from step # 230 is performed. In step # 230, it is determined whether the flag TIF is "1".
When the value is "1", the constant time has elapsed in the low contrast stop mode, and only the measured value of the low contrast is obtained during this period. At this time, it is possible to interrupt and the flags TIF and SEF are set.
1, SEF2, LCF1, LCF2, LSF are set to "0", the flag FPF is set to "1", the event count mode is set, and the process returns to step # 2. Therefore, the measurement is performed in the same state as the first measurement.

When the flag TIF is "0" in step # 230, it means that the movement amount of the lens has moved by the calculated movement amount. In this case, the motor (MO) is stopped to enable the interrupt. Then, in step # 235, it is determined whether the flag FLF is "1". If it is "1", it means the pre-irradiation mode, and the process proceeds to step # 238. In step # 238, it is determined whether or not the flag FFF is "1". If the flag FFF is "1", it means that the second focusing operation in the pre-irradiation mode has been completed, the focusing display is performed, and the timer interrupt is possible. Then, the process proceeds to step # 211. On the other hand, if the flag FFF is "1", it means that the first focusing operation is completed in the preliminary irradiation mode, and the flag FFF is set to "0".
The process returns to step 115 and the second focusing operation is performed.

If the flag FLF is "0" in step # 235, the preliminary irradiation is not performed, a measured value that is not low contrast is obtained, and the lens is moved by the calculated movement amount. At this time, the flags IFF and FPF are set to "1".
Return to step 2 and ask for confirmation measurements.

If a timer interrupt occurs, flag RS will be sent in step # 260.
Return F to "0" to return to the operation when an interrupt occurs. As with other interrupts, once the timer interrupt has been interrupted, the interrupt is disabled thereafter unless the interrupt is enabled.

In the steps # 11, # 19, # 38, and # 195, the terminal (i3) goes to "Lo".
If it is determined that it has become "w", the terminal is connected in step # 209.
(it1) and the interruption by the counter COR are prohibited, the event count mode is set, and the process proceeds to step # 213. On the other hand, from the steps of # 76, # 90, # 176, # 203, and # 243, the process moves to the step of # 211 and the terminal (i
t1) and counter COR cannot be interrupted, and terminal (i3)
Wait for “Low”. When the terminal (i3) becomes "Low", the process proceeds to step # 213. In step # 213, terminals (O4) and (O5) are set to "Low" to stop the motor (MO), and then the display is turned off. Then, the terminals (O1), (O2), (O3), (O6) are set to "Low".
As a result, the operation of the circuit for automatic focus adjustment is stopped. Then, all flags except RSF, FPF and SIF are set to "0" to set the flag FPF to "1". Next, the contents of the counter COR are set in the register ECR2, and after waiting for a fixed time, the contents of the counter COR are set in the register ECR2.
Set to CR3. And (ECR2) = (ECR3)
If (ECR2) ≠ (EC
R3), the contents of register ECR3 are registered in register ECR2
Set to and return to step # 219. And (ECR
If 2) = (ECR3), the movement of the lens is in a completely stopped state, and the process proceeds to step # 223.

In step # 223, it is determined whether the flab RSF is "1". If it is "1", preliminary irradiation is performed for a certain time (200
It means that (msec) has not elapsed, and waits for the flag RSF to become “0” after a fixed time has elapsed. And flag R
When SF is "0" or "0", #
In step 224, the terminal (O7) is set to “Low” to enable the exposure control operation by the microcomputer (MCO2).
The microcomputer (MCO1) stops its operation by enabling the interrupt to 2).

Effect According to the automatic focus detection device of the present invention, when the reliability of the focus detection result is low and the subject brightness is low, the auxiliary light is emitted to perform the focus detection again, and the reliability of the focus detection result is low. If it is low and the subject brightness is not low, focus detection is performed again while driving the focusing lens group, so that it is possible to perform appropriate focus detection operations according to the subject brightness.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a circuit diagram showing the entire camera system to which the present invention is applied, and FIG. 3 is a specific example of the flash (FLC) shown in FIG. Circuit diagram, Fig. 4 shows the microcomputer (MCO2) in Fig. 2.
5-1, 5-2, 5-showing the operation of
FIG. 3 is a flowchart showing the operation of the microcomputer (MCO1) shown in FIG. Photographing lens → 10 Driving means → 9 Focus detection means → 1.2.3. Reliability determination means → 4, (# 39) Light emitting means → 12.13 Luminance determination means → 1.2, (# 111) First control Means- # 39-110-118-2 Second control means- # 39-110-121-133-3 Third control means- # 39-40-50-73-2

Continuation of front page (56) Reference JP-A-48-53717 (JP, A) JP-A-54-126023 (JP, A) JP-A-58-132733 (JP, A) JP-A-58-58508 (JP , A) JP 59-195605 (JP, A)

Claims (3)

[Claims] 1. A photographic lens, a driving means for driving a focusing lens in the photographic lens, a focus detecting means for receiving an image of an object formed by the photographic lens, and performing focus detection of the photographic lens for this object, and a focus. Reliability determining means for determining the reliability of the detection operation of the detecting means, light emitting means for emitting auxiliary light for illuminating the subject, brightness determining means for determining whether or not the subject has low brightness, and reliability determining When the means determines that the reliability of the detection operation of the focus detection means is low and the brightness determination means determines that the subject has low brightness, the auxiliary light is emitted to cause the focus detection means to perform the detection operation again. When the control means of No. 1 and the reliability determination means determine that the detection operation of the focus detection means is unreliable and the brightness determination means determines that the subject is not of low brightness, the detection operation with high reliability is performed. The second determination means controls the focus detecting means to repeatedly perform the detecting operation while controlling the driving means to drive the photographing lens until the operation is obtained. If it is determined to be high, a third control means for controlling the drive means based on the detection result of the focus detection means to drive the photographing lens to the in-focus position, the automatic focus adjustment device characterized by the above-mentioned. . 2. The focus detecting means receives and integrates a subject image formed by a taking lens with a large number of light receiving elements arranged in a row, and the reliability determining means receives a contrast value obtained from the light receiving element row. The automatic focus adjustment device according to claim 1, wherein the reliability of the detection operation of the focus detection means is determined based on the above. 3. The brightness determining means determines that the subject has low brightness by detecting that the light reception integrated output of the light receiving element array has not reached a predetermined value within a predetermined time. The automatic focus adjusting device according to claim 2.