JP2001004911A - Automatic focusing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten integration time by changing an integration finish value and the gain of an amplifying means in accordance with the emitted light quantity of flash light necessary for focus detection. SOLUTION: This device is equipped with a passive type automatic focusing(AF) sensor unit 21, a built-in flash device 71, and a main CPU 35 controlling the integration of the unit 21 and the light emission of the device 71. Then, the CPU 35 allows the CCD line sensor 211 of the unit 21 to start the integration while making the device 71 intermittently emit light, and raises the integration finish value by one step when the integrated value of the sensor 211 does not attain the integration finish value even when the device 71 is made to intermittently emit the light by specified number of times. When the integrated value does not attain even the integration finish value raised by one step, the CPU 35 repeatedly performs processing for raising the gain of the amplifying means 215 by one step every time the flash light is intermittently emitted by the specified number of times until the number of flash light emitting times attains the maximum one or the gain attains the maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device for a camera using a flash device as an auxiliary light source when an object has low brightness or low contrast.

[0002]

2. Description of the Related Art Usually, a so-called passive AF (automatic focus adjustment) camera emits light from an AF auxiliary light source built in a camera body when an object has low brightness or low contrast. A contrast pattern is projected on the subject as auxiliary light to generate contrast in the subject image received by the AF sensor, and focus detection is performed from the subject image. However, providing an auxiliary light source for focus detection separately from the flash device for photographing is costly. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 5-34577, the flash device is intermittently illuminated and used as auxiliary light. Some are intended to be used.

At the time of focus detection, an AF having a light receiving element
The sensor receives the subject light, photoelectrically converts and integrates the electric charge,
When the integration value of the AF sensor reaches the integration end value, the integration is terminated, and the integration value at the end of integration is detected based on the integration value amplified by a predetermined gain (amplification factor). When it is possible, integration is performed again while intermittently emitting flash light. At this time, when the subject distance is long, the amount of flash light required for focus detection is large, and therefore, the number of times of emission of auxiliary light must be increased in order for the integration value of the AF sensor to reach the integration end value. However, when the amount of light emission increases, the charging voltage of the flash device decreases, and when the number of times of light emission increases, the integration time increases, which is not preferable. To suppress the light emission amount, the gain of the integral value may be set high in advance. However, when the subject distance is short, the range of the amplified integral value exceeds the range in which the focus detection process can be performed, and an error occurs, and the detection accuracy is reduced. Will fall.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention changes the integration end value and the gain of the amplifying means in accordance with the amount of auxiliary light emission required for focus detection, thereby making it possible to shorten the integration time. It is an object to provide an automatic focusing device.

[0005]

An object of the present invention is to provide a light emitting means for emitting a flash for photographing a subject, receiving the subject light, integrating the subject image as electric charge, and integrating when the integrated value reaches an integration end value. Light-receiving means for terminating the operation, amplification means for amplifying the integral value of the light-receiving means at the end of integration with a predetermined gain, focus detection means for performing focus detection based on the integrated value amplified by the amplification means, and said focus detection means When it is not possible to detect the focus of the light, the light-emitting unit is integrated while the light-emitting unit is intermittently emitting light. An automatic focus adjustment device characterized by including integration control means for changing the integration end value and the gain of the amplification means in a stepwise manner every time light emission is performed. The integration control means preferably changes the integration end value and the gain of the amplifying means so as to shorten the time required for the integration value of the light receiving means to reach the integration end value. If the integral value of the light receiving means has not reached the integral end value even after the number of intermittent light emission, the integral end value is increased by one step, and the integral value of the light receiving means is increased by one step at this time. If not, it is preferable to increase the gain of the amplifying means by one step. Causing the light emitting means to emit light intermittently until the maximum number of times of light emission is reached,
When the number of times of light emission of the light emitting means has reached the maximum number of times of light emission, the integration of the light receiving means is terminated even if the integrated value of the light receiving means has not reached the integration end value changed in the predetermined step. Is good. Further, the integration control means
After the gain of the amplifying means reaches the maximum, it is preferable that the integration end value and the gain are not changed. According to the above configuration, the integration end value and the gain of the amplifying unit can be changed according to the number of times of light emission of the light emitting unit, and the integration time of the light receiving unit can be reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of an automatic focusing (AF) single-lens reflex camera to which the present invention is applied. The AF single-lens reflex camera includes a camera body 11 and an AF-compatible photographing lens 51 that is detachable from the camera body 11. The camera body 11 includes an automatic focus adjustment unit and a built-in flash device 71.

Most of the subject light flux entering the camera body 11 from the photographing lens 51 is reflected by the main mirror 13 toward the pentaprism 17 constituting the finder optical system, and is reflected by the pentaprism 17 from the eyepiece. Inject. Part of the subject light flux emitted from the pentaprism 17 enters the light receiving element of the photometric IC 18. On the other hand, the half mirror section 14 of the main mirror 13
A part of the light beam incident on the sub-mirror 15
Is reflected downward, and enters the AF sensor unit 21.

The photometric IC 18 inputs an electric signal, which has been photoelectrically converted in accordance with the amount of received light, to the main CPU 35 via the peripheral control circuit 23 as a photometric signal. Main CPU
Reference numeral 35 executes a predetermined exposure calculation based on a photometric signal, film sensitivity information, and the like, and calculates an appropriate shutter speed and aperture value for exposure. The exposure mechanism and the aperture mechanism 25 are driven based on the shutter speed and the aperture value to expose the film. Further, the peripheral control circuit 23 drives the mirror motor 31 via the motor drive circuit 27 to perform the up / down processing of the main mirror 13 during the photographing processing, and drives the film winding motor 33 after the exposure is completed. To wind up the film for one frame.

The AF sensor unit 21 is a so-called phase difference type distance measuring sensor, which divides a subject light beam which forms a subject image included in a focus detection area in a photographing screen (not shown) into two, and A CCD line sensor 211 that receives and integrates the two divided subject light beams and a monitor sensor 213 that checks the integrated value of the CCD line sensor 211 are provided. The signal charge integrated by the CCD line sensor 211 is converted into a voltage on a pixel-by-pixel basis, amplified by the amplifier 215, and output to the main CPU 35 as a video signal on a pixel-by-pixel basis.
It should be noted that when the integrated value of the monitor sensor 213 reaches the integration end value, the main CPU
Terminate the integration of 1.

The main CPU 35 calculates a defocus amount by a predetermined calculation based on the video signal input from the AF sensor unit 21. Next, the rotation direction and the number of rotations of the AF motor 39 (the number of pulses output by the encoder 41) are calculated based on the defocus amount. Then, the main CPU 35 drives the AF motor 39 via the AF motor driver 37 based on the rotation direction and the number of pulses. At the time of this driving, the main CPU 35
The pulse output from the encoder 41 is detected and counted in conjunction with the rotation of the motor 39, and the AF motor 39 is stopped when the count value reaches the number of pulses.

The rotation of the AF motor 39 is controlled by a joint 47 provided on a mount of the camera body 11 and a joint 57 provided on a mount of the photographing lens 51.
Is transmitted to the photographing lens 51 through the connection with the camera. Then, the focus adjusting lens 53 is moved forward and backward through the gear block 55.

The main CPU 35 receives data from a ROM 35a storing a control program and the like, a RAM 35b temporarily storing predetermined data for calculation and control, a reference timer 35c for clocking, a hard counter 35d, and an AF sensor unit 21. An A / D converter 35e for A / D converting the video signal to be output is built in, and an EEPROM 43 as an external memory means is connected. This EEPR
The OM 43 stores various constants specific to the camera body 11 and the like.

The camera body 11 has a built-in flash unit 71 which can be controlled by the main CPU 35 via the peripheral control circuit 23. Although the details of the built-in flash device 71 are not shown, the flash unit is provided above the pentaprism 17 and includes a light-emitting unit that moves between a pop-up position and a storage position. The light-emitting unit includes a xenon tube. The built-in flash device 71 is a flash that is used as normal shooting auxiliary lighting, but is used as an auxiliary light source for focus detection when focus cannot be detected because the subject has low luminance or low contrast. The built-in flash device 71 emits flash light when an FT signal (trigger signal) is input from the main CPU 35 via the peripheral control circuit 23, and performs charging when a charge signal (charge start signal) is input. The charge voltage is detected, and an RIF signal (charge voltage detection signal) is output to the main CPU 35 via the peripheral control circuit 23.

Further, the main CPU 35 includes a pop-up detection switch SWP for detecting that the built-in flash device 71 is popped up, a photometric switch SWS which is turned on when a release button (not shown) is half-pressed, and a release switch which is turned on when fully pressed. SWR, auto focus switch SW for switching between auto focus control and manual focus control
Power on / off to AF, peripheral control circuit 23, etc.
Main switch SWM is connected. Main C
The PU 35 displays the set modes such as AF, exposure, and shooting, the shutter speed, and the aperture value on the display 45. The display 45 usually includes two displays provided on the outer surface of the camera body 11 and in the finder field of view.

The main CPU 35 is a camera body 1
In addition to functioning as control means for generally controlling the camera lens 1 and the photographing lens 51, the built-in flash device 71 and the peripheral control circuit 23 and the like constitute light emission control means, and the peripheral control circuit 23 and the like. It constitutes integral control means for controlling the integral processing of the AF sensor unit 21.

On the other hand, the photographing lens 51 has a gear block 55 for driving the focus adjusting lens 53 in the optical axis direction, and an AF motor provided on a mount portion of the photographing lens 51 and connected to a joint 47 of the camera body 11. The lens-side joint 5 that transmits the rotation of 39 to the gear block 55
7, a lens CPU 61 and a distance switch 63 are provided.

The lens CPU 61 includes a focusing lens 5.
The position of No. 3 is detected as a distance code from the state of the distance switch 63 to obtain distance information. The lens CPU 61 is connected to the peripheral control circuit 23 of the camera body 11 through the connection of the electrical contact groups 59 and 49, and performs lens communication with the main CPU 35 via the peripheral control circuit 23. Execute and input lens data such as distance information, focal length information, and aperture information.

Referring to FIG. 2, the configuration of the AF sensor unit 21 including the CCD line sensor 211 in this embodiment will be described in more detail.

An AF sensor unit 21 receives a subject light and integrates the light as a charge into a CC as a light receiving means.
A monitor sensor 213 for monitoring the integrated value of the D line sensor 211 and the CCD line sensor 211, and a CC after the integration is completed.
An amplifier 215 is provided as amplification means for amplifying the integrated value of the D line sensor 211 with a predetermined gain and outputting the amplified value to the main CPU 35. Although not shown in detail, the CCD line sensor 211 independently integrates a photoelectric conversion element such as a photodiode that receives a subject light and performs photoelectric conversion, and a signal charge converted by each photoelectric conversion element for each photoelectric conversion element. And a charge holding unit that transfers and temporarily holds the charge integrated by the integration unit. The charges held by each charge holding unit are transferred to the CCD transfer unit 212,
The data is sequentially output from the transfer unit 212. The monitor sensor 213 is arranged in parallel with the CCD line sensor 211, and detects an integrated value of the CCD line sensor 211.

The CCD line sensor 211 includes a main CP
The integration process is started by the integration start signal from U35.
The photoelectric conversion element of the CCD line sensor 211 that has received the subject light photoelectrically converts the subject light, and the monitor sensor 213 monitors the integrated value integrated by the integration unit. Monitor sensor 2
When the integrated value of No. 13 reaches the integration end value (VAGC),
The charge integrated by the integration unit of the CCD line sensor 211 is transferred to the charge holding unit, and the integration is terminated.
Clear 3 The charge held in the charge holding unit is a CCD
The data is transferred to the transfer unit 212 and output from the CCD transfer unit 212. The charge is converted into a voltage in pixel units when output from the CCD transfer unit 212, and the output voltage signal is amplified by the amplifier 215 with a predetermined gain, and is taken into the main CPU 35 as a video signal in pixel units. The fetched video signal is converted into a digital signal by an A / D converter 35e and stored in a RAM 35b.
35 performs a defocus operation based on the signal stored in the memory.

When the integration process is performed without emitting the flash light, when the integration value of the monitor sensor 213 reaches the integration end value, an integration end signal is output to the CCD line sensor 211 to end the integration. When the integration of the CCD line sensor 211 is not completed within the preset maximum integration time, that is, when the integrated value of the monitor sensor 213 does not reach the integration end value within the preset maximum integration time. When the maximum integration time has elapsed, an integration end signal is output to cause the CCD line sensor 211 to end integration. The CCD line sensor 211 transfers the charge integrated by the integration unit to the charge holding unit in response to the integration end signal, and ends the integration. The monitor sensor 213 is cleared and returns to the initial state.

In the case where the integration process is performed while the flash light is intermittently emitted as the auxiliary light for focus detection, the monitor sensor 21 may emit the flash light intermittently a predetermined number of times.
When the integral value of the third signal does not reach the integral end value (VAGC), the integral end value is increased by one step so that the time until the integral value reaches the integral end value is shortened by one step.
Is compared with the integration end value increased by one step. If the integration value of the monitor sensor 213 still does not reach the integration end value increased by one step, the process of increasing the gain of the amplifier 215 by one step is repeatedly executed. are doing. In this process, when the number of times of flash light emission reaches the preset maximum number of times of light emission, the monitor sensor 213 is cleared by forcibly terminating even if integration of the CCD line sensor 211 is not terminated. After the gain is maximized, the integration end value and the gain are not changed.

FIG. 3 shows a CCD line sensor 2 which is executed while intermittently emitting flash light in this embodiment.
11 shows a timing chart relating to the integral control of No. 11. This integration control process is started on condition that the photometric switch SWS is turned on. When the photometric switch SWS is turned on,
The main CPU 35 outputs an integration start signal to cause the CCD line sensor 211 to start integration, and causes the built-in flash device 71 to emit light intermittently. The monitor sensor 213 monitors the integrated value of the CCD line sensor 211 when the integration is started. The integral value of the monitor sensor 213 changes in a direction lower than the initial value as the integration of the CCD line sensor 211 proceeds, and the main CPU 35
When it is detected that the integrated value of 13 has reached the integration end value (VAGC), an integration end signal is output, and the integration of the CCD line sensor 211 is ended. After the integration is completed, the monitor sensor 213 is cleared and returns to the initial state.

The main CPU 35 raises the integration end value by one level if the integration value of the monitor sensor 213 has not reached the integration end value even after the flash light is emitted twice. If the integral value of the monitor sensor 213 does not reach the integral end value increased by one step even if the integral end value is increased by one step, the gain of the amplifier 215 is increased by one step. Here, raising the integration end value by one step means lowering the VAGC output so that the difference (AGC level) between the monitor level before the start of integration and the integration end value (VAGC) becomes 1/2. .

Since the integrated value of the monitor sensor 213 has not reached the integration end value even after the fourth light emission, the AGC level is 倍 times, that is, の of the AGC level at the start of integration.
Double it. Then, the integral value of the monitor sensor 213 reaches the integral end value, so that the main CPU 35 detects at this time that the integral value of the monitor sensor 213 has reached the integral end value, outputs an integral end signal, and outputs the CCD end signal. The monitor sensor 213 is cleared by terminating the integration of the sensor 211, the integrated value is converted into a voltage signal, amplified by the amplifier 215 at the gain at the end of the integration, and input as a video signal in pixel units.

In the illustrated embodiment, if the integrated value of the monitor sensor 213 has not reached the integration end value even after the flash light is emitted twice, the AGC level is increased by a half unit. If the integral value of the input signal does not reach the integration end value increased by one step, the gain of the amplifier 215 is increased in units of two, but is not limited to this.

Next, the main operation of the single-lens reflex camera to which the present invention is applied will be described with reference to FIGS. FIG.
5 is a flowchart relating to the main processing of the single-lens reflex camera. In this main processing, the photometric switch SW
Wait for S to be turned on, and when the photometry switch SWS is turned on, execute photometry and exposure calculation processing (AE calculation processing) to obtain the optimal aperture value and shutter speed, and focus detection processing and lens drive processing (AF processing). Is executed, and when the release switch SWR is turned on, the exposure process is executed with the aperture value and the shutter speed obtained by the AE process.

This main process starts when a battery is loaded. In this process, first, a system port and the like are initialized (S101). And the main CPU
Cut off the power supply to circuits and components other than 35 (S103)
It waits until the photometric switch SWS is turned on (S105). When the photometric switch SWS is turned on (S105; Y), power supply to peripheral devices is started and a VDD loop process is executed (S107).

In the VDD loop processing, a VDD loop time timer is started (S109), and the state of each switch is checked (S111).
A predetermined lens communication is performed with the PU 61, and lens data such as an open aperture value, a minimum aperture value, and focal length data are input (S113).

Then, an AE operation is performed (S115).
A display related to photographing such as a shutter speed obtained by calculation is performed (S117). The AE calculation process is a process of measuring a subject brightness by the photometric IC 18 and calculating an appropriate shutter speed and an aperture value by a predetermined exposure mode, for example, a program exposure mode, based on the subject brightness data and the film sensitivity data.

Once the shutter speed and aperture value are determined, A
An AF process for moving the focus adjustment lens 53 so as to focus on the subject whose focus has been detected via the F sensor unit 21 is executed (S119). The AF process is repeated until the VDD loop time elapses (S121; N, S119).

When the loop time has elapsed (S121; Y), the state of the photometric switch SWS is checked (S123), and if it is on, the process returns to the VDD loop processing (S123; Y, S109).
If the photometry switch SWS is off (S123; N), it is checked whether the power hold flag is set (S125). If it is set, the VDD loop processing is repeated until the power hold time elapses (S12).
5; Y, S131; N). If the power hold timer is not set, the power hold timer is started (S125; N, S127), and the VDD loop processing is repeated until the power hold timer expires after the power hold flag is set (S129, S131; N, S109). ). Then, when the power hold time has elapsed, the power hold flag is cleared and the process returns to the power down process (S131; Y, S133, S10).
3).

[AF Process] The AF process executed in S121 will be described in more detail with reference to FIG. The AF process is a process of executing the focus detection process to move the focus adjustment lens 53 so as to focus on the subject whose focus has been detected, but executes the focus detection process without emitting flash light to execute the focus detection process. If it is determined that focus detection was not possible due to low brightness or the like, focus detection is performed again while intermittently emitting flash light, and the focus adjustment lens 53 is focused so as to focus on the detected subject. This is the process of moving.

When the AF process is started, it is first checked by the pop-up detection switch SWP whether the built-in flash device 71 is popped up (S201). If not popped up, the auxiliary light permission flag is cleared (S201; N, S203), and the use of the auxiliary light is prohibited.

The auxiliary light permission flag is a flag for permitting intermittent light emission of the built-in flash device 71 as auxiliary light for focus detection when focus detection is impossible due to low brightness or low contrast of the subject. It is cleared at the time of the first AF process.

If the pop-up is displayed, the auxiliary light mode flag is checked (S201; Y, S205). If the auxiliary light mode flag is in the clear state, the auxiliary light permission flag is set (S205; N, S207).

The auxiliary light mode flag is cleared at the first AF processing, and thereafter, the main CPU 35
Is set based on various conditions.

Next, it is checked whether or not the photometric switch SWS is on (S209). Photometric switch SW
If S is off, the auxiliary light mode flag, the auxiliary light second time flag, and the focusing flag are cleared, respectively, and the process returns (S209; N, S211).

If the photometering switch SWS is on (S209; Y), the in-focus flag is checked to determine whether the subject is in focus (S213), and if in focus, the process returns (S213; Y). . If the focus is not achieved, the integration process is started (S213; N, S215).

Although the details will be described later, in the first integration process, the AF sensor unit 21 performs the integration without causing the built-in flash device 71 to emit light, and the AF sensor unit 2
When the integration of 1 is completed, the main CPU 35 inputs the CCD video signal, converts it into a digital signal by the A / D converter 35e, stores the digital signal in the RAM 35b, and executes the defocus calculation to obtain the defocus amount.

Then, an auxiliary light mode check process is executed (S217). Although details will be described later in the auxiliary light mode check processing, the built-in flash is used when a valid operation result is not obtained in the integration processing in S215, when the integration time is longer than a predetermined time, or the like. Device 7
1 is intermittently emitted, and the integration process is executed again.

Then, it is checked whether or not a valid operation result is obtained in S215 or S217 by using an operation OK flag (S219). The calculation OK flag is a flag that is set when the calculated defocus amount is valid after the end of the defocus calculation. If the calculation OK flag is set (S219; Y), it is checked whether or not the calculated defocus amount is included in the range of the focusing width that can be regarded as in focus (S221), and the defocus amount is focused. If it is within the range of the width, the focus flag is set and the process returns (S221; Y,
S227).

If the defocus amount is out of the range of the focusing width (S221; N), since the subject is not in focus, the number of AF pulses is calculated from the defocus amount or the like (S223), and the calculated AF pulse number is calculated. Based on this, the AF motor 39 is driven to move the focusing lens 53, and the process returns (S225).

If the operation OK flag is not set (S219; N), it is checked whether the auxiliary light mode flag is set (S229). If the auxiliary light mode flag has not been set, the process returns as it is (S229; N). If the auxiliary light mode flag is set (S229; Y), the second auxiliary light flag is checked (S231).

If the second auxiliary light flag is cleared (S231; N), the focusing lens 5 is moved to a predetermined position.
3 is moved (S233), the second auxiliary light flag is set, and the routine returns (S235). The focus adjusting lens 53 is moved to, for example, a position at a shooting distance of 3 m.

If the auxiliary light second time flag is set (S231; Y), the auxiliary light permission flag is cleared, and
In other words, flash light emission is prohibited and the process returns (S2
37). That is, if the focus cannot be detected in the first AF process using the flash light in steps S229 to S237, the focus adjustment lens 53 is moved to a predetermined position, and the flash light is intermittently emitted at the moved position. Then, focus detection is performed again. If focus detection is still impossible, flash light as auxiliary light for focus detection is not emitted thereafter.

"Integration Processing" The integration processing executed in S215 will be described in more detail with reference to FIG. In this process, when the focus detection process is executed without emitting the flash light and the focus cannot be detected, the CCD line sensor 211 performs the integration while the flash light is intermittently emitted to execute the focus detection process. Do. At this time, if the integral value of the monitor sensor 213 has not reached the integration end value even after the flash light has been intermittently emitted a predetermined number of times, the integration end value is increased by one step, and the integration value is increased by one step. If the integrated value has not reached the integration end value that has been increased by one step, the process of increasing the gain of the amplifier 215 by one step is performed until the number of times of flash light emission reaches a predetermined maximum number of times or the gain becomes maximum. Repeatedly until it reaches.

Upon entering the integration processing, first, the auxiliary light permission flag is checked (S301). If the auxiliary light permission flag is set (S301; Y), the auxiliary light mode is checked (S303). The auxiliary light mode is cleared at the time of the first integration processing, and the auxiliary light mode check processing is being performed.
When a valid operation result was not obtained in the integration process of
This is set in S409 when conditions such as when the integration time is longer than a predetermined time are satisfied.

If the auxiliary light mode is not set (S303; N), the integration is started without emitting the flash light (S305). After the integration is completed, a CCD video signal is input (S307; Y, S309). The defocus calculation is executed to determine the defocus amount (S311), and it is determined whether the calculation result is valid (S313). If the calculation result is valid, the calculation OK flag is set and the routine returns (step S313). S313; Y, S3
15) Perform focusing processing based on the calculated defocus amount. If the operation result is not valid, the operation OK flag is cleared and the process returns (S313; N, S314). Since the auxiliary light mode flag is not set at the time of the first integration processing, focus detection is performed without emitting flash light.

When the auxiliary light mode is set (S3
03; Y), the charging voltage of the built-in flash device 71 is checked (S317), and if the charging voltage has not reached the auxiliary light level, it is charged to the auxiliary light level (S317; Y, S3).
19).

When the completion of charging of the built-in flash device 71 is detected (S317; N, S319), the integration end value (VAG) of the CCD line sensor 211 is passed through the peripheral control circuit 23.
C) is set (S321), the light emission number counter of the built-in flash device 71 is cleared (S323), and the comparison number is initialized (S325).

The number of comparisons is a value for setting the number of times of light emission for changing the integration end value. When the set number of times of comparison becomes equal to the number of times of light emission of the auxiliary light, the integration end value is changed.

Next, an integration start signal is output to cause the CCD line sensor 211 to start integration (S327), a light emission trigger signal is output (S329), and the built-in flash device 71 is made to emit light. Wait for the time to elapse (S33
1).

When the light emission time has elapsed, the trigger signal is turned off and the built-in flash device 71 stops light emission (S333).
The light emission number counter is incremented by one (S335). Then, it is checked whether or not a predetermined maximum number of times of light emission has been reached (S337). If the maximum number of flashes has not been reached (S3
37; N), it is checked whether or not the integral value of the monitor sensor 213 has reached the integral end value (S339).

When the maximum number of times of light emission has been reached (S337;
Y) or when the integration value of the monitor sensor 213 has reached the integration end value (S339; Y), a CCD video signal is input (S355), and defocus calculation is executed to obtain a defocus amount (S357). If the calculation result is valid, the calculation OK flag is set (S359; Y, S361), and if the calculation result is not valid, the calculation OK flag is cleared (S359; N, S362). Then, the built-in flash device 71 is charged to the auxiliary light charging level and the process returns (S36).
3).

If the integration value of the monitor sensor 213 has not reached the integration end value, it is checked whether the gain (amplification degree) of the amplifier 215 is maximum (S339; N, S34).
1) If the gain is not the maximum (S341; N), the number of times of light emission is compared with the number of comparisons (S343).

The number of comparisons is set at S325 for the first time,
After the first time, it is set in S345. If the number of times of light emission is equal to the number of comparisons (S343; N), the number of comparisons is reset to the sum of the number of times of light emission and the initial value of the number of comparisons (S345).
The GC level is halved (S347). By S343 to S347, the integration end value can be changed according to the number of times of flash light emission. For example, if the initial value of the number of comparisons is set to 2 in S325, every two intermittent emission of flash light, If the integral value of the monitor sensor 213 has not reached the integral end value, the integral end value is changed.

Then, the integral value of the monitor sensor 213 becomes 1
It is checked whether or not the AGC level has been multiplied by two (S349), and if not, the gain of the amplifier 215 is doubled (S349; N, S351). After changing the gain to twice, the apparatus waits for the set interval time until the next intermittent light emission (S353).

When the gain of the amplifier 215 is maximum (S341; Y) and when the number of times of light emission is not equal to the number of times of comparison (S343; N), the apparatus waits for a set interval time until the next intermittent light emission (S353).

If the integration value of the monitor sensor 213 has reached the integration end value (S349; Y), a CCD video signal is input (S355), and defocus calculation is executed to obtain a defocus amount (S357). ), It is determined whether or not the operation result is valid (S359).
The K flag is set (S359; Y, S361). If the operation result is not valid, the operation OK flag is cleared (S359;
N, S362), the built-in flash device 71 is charged to the auxiliary light charging level (S363).

"Auxiliary light mode check" The auxiliary light mode check processing executed in step S217 will be described in detail with reference to FIG. In the auxiliary light mode check processing, when the focus detection processing is executed without emitting the flash light and the focus cannot be detected, the auxiliary light mode flag is set and the focus is set while the flash light is intermittently emitted. This is a process for executing detection.

In this process, first, the state of the auxiliary light permission flag is checked (S401). If the auxiliary light permission flag is set (S401; Y), the auxiliary light mode flag is checked (S403). If the auxiliary light mode flag is not set (S403; N), the operation OK flag is checked. (S405).

If the calculation OK flag is cleared (S405; N), then the integration time is compared with a predetermined time (S407). Here, the integration time refers to a time taken from when the CCD line sensor 211 starts integration to when the integrated value of the monitor sensor 213 reaches the integration end value. If the integration time exceeds the predetermined time (S407; Y), that is, if the subject is dark, the auxiliary light mode flag is set (S409), and the integration process is performed again while intermittently emitting the auxiliary light (S411). .

The auxiliary light permission flag is cleared at the start of the AF processing, and is set in S207 during the first AF processing on condition that the built-in flash device 71 is popped up. After moving the 53, if the focus cannot be detected even if the focus detection processing is performed while intermittently emitting the flash light, the process is cleared in S237. The auxiliary light mode flag is set in S409 when the result of the focus detection processing performed without emitting the flash light and the detection result is invalid because the subject is dark. In other words, in the auxiliary light mode check processing, the integration processing (S411) is executed only once, while the built-in flash device 71 is intermittently emitting light. Since the auxiliary light mode flag has already been set for the second and subsequent times, the integration in S215 is performed. The auxiliary light is emitted intermittently in the processing, and the integration processing is not executed in this auxiliary light mode check. Further, after clearing the auxiliary light permission flag in S237 and prohibiting the emission of flash light, the auxiliary light permission flag in S207 is not set unless the photometric SW is turned off and the auxiliary light mode flag is cleared in S211. .

In the present embodiment, the light emitting means is described as the built-in flash device 71. However, the present invention is not limited to this.
The present invention can also be applied to an external flash device that can be controlled by U35.

[0066]

As is apparent from the above description, according to the present invention, when the light receiving means performs integration while the light emitting means is intermittently emitting light, the light emitting means is not operated until the integrated value of the light receiving means reaches the integration end value. Every time the light is emitted intermittently a predetermined number of times,
Since the process of stepwise changing the integration end value or the gain of the amplifying means is repeated, it is possible to reduce the number of light emission of the light emitting means and shorten the integration time of the light receiving means. Also,
In the present invention, the integration end value is increased by one step every time the light emitting means is intermittently emitted a predetermined number of times until the integral value of the light receiving means reaches the integration end value, and the integration value of the light receiving means is increased by one step to the integration end value. If the integration value of the light receiving means reaches the integration end value at an early stage of the integration processing, the error is reduced because the gain is low. It is also possible to improve the focus detection accuracy to a small extent.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of an embodiment of an autofocus single-lens reflex camera to which the present invention is applied.

FIG. 2 is a diagram illustrating a configuration of an AF sensor unit of the same-lens reflex camera.

FIG. 3 is a diagram showing a timing chart in an integration control process of the same-lens reflex camera.

FIG. 4 is a diagram showing a main flowchart relating to main operations of the same-lens reflex camera.

FIG. 5 is a diagram showing a flowchart relating to AF processing of the same-lens reflex camera.

FIG. 6 is a diagram showing a flowchart regarding integration processing of the same-lens reflex camera.

FIG. 7 is a view showing a flowchart relating to an auxiliary light mode check process of the same-lens reflex camera.

[Explanation of symbols]

 11 Camera Body 13 Main Mirror 14 Half Mirror 15 Sub Mirror 21 AF Sensor Unit 211 CCD Line Sensor 213 Monitor Sensor 215 Amplifier 35 Main CPU 51 Shooting Lens 53 Focusing Lens 71 Built-in Flash Device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H011 BA23 BB04 DA07 2H051 AA01 BA03 CA04 CC11 CC12 CC18 CD03 DA11 EB19 2H053 AA05

Claims (6)

[Claims] 1. A light emitting means for emitting a flash for photographing a subject, receiving the subject light, integrating the subject image as electric charges,
Light-receiving means for terminating integration when the integrated value reaches an integration end value; amplifying means for amplifying the integral value of the light-receiving means at the end of integration with a predetermined gain; and Focus detection means for performing focus detection, and when focus detection by the focus detection means is impossible,
Each time the light-emitting unit is intermittently emitted a predetermined number of times until the integration value of the light-receiving unit reaches an integration end value until the integration value of the light-receiving unit reaches an integration end value.
An automatic focus adjustment device comprising: an integration control means for changing the integration end value and a gain of the amplification means in a stepwise manner. 2. An automatic focusing apparatus according to claim 1, wherein said integration control means changes said integration end value so as to shorten the time required for the integration value of said light receiving means to reach said integration end value. An automatic focus adjustment device, characterized in that: 3. An automatic focusing apparatus according to claim 1, wherein said integral control means is configured to control the integral value of said light receiving means not to reach said integral end value even if said light emitting means is intermittently emitted a predetermined number of times. Wherein the integration end value is increased by one step so as to shorten the time required to reach the integration end value. 4. An automatic focusing apparatus according to claim 3, wherein said integral control means increases said integral end value by one step when said integral value of said light receiving means is increased by one step. The automatic focusing device increases the gain of the amplifying means by one step when the gain has not been reached. 5. The automatic focusing apparatus according to claim 1, wherein said integration control means is configured to control when the integrated value of said light receiving means has not reached the integration end value changed by said predetermined step. Means that the light-emitting means intermittently emits light until a preset maximum number of light-emitting times is reached, and when the number of light-emitting times of the light-emitting means reaches the maximum number of light-emitting times, the integration value of the light-receiving means is changed by the predetermined number of steps. An automatic focus adjustment device, wherein the integration of the light receiving means is terminated even if the value has not reached the value. 6. An automatic focusing apparatus according to claim 1, wherein said integration control means includes a predetermined integration end value and said predetermined integration end value after a gain of said amplification means reaches a maximum. An automatic focusing device, wherein the gain is not changed.