JPH0215209A - Automatic focusing camera - Google Patents

Abstract

PURPOSE:To follow the action of a dynamic object even if focus detection becomes impossible temporarily and to drive a lens by obtaining the changing amount of defocus quantity from its changing speed caused by the movement of the object, and driving the focusing lens based on the changing amount. CONSTITUTION:A focus detecting means 1 detects the focusing state of a photographing lens, and outputs the defocus quantity (DFO). It is a variable and its mark indicates the direction of the defocus quantity and its absolute value indicates the magnitude of the defocus quantity. A changing speed detecting means 2 detects the changing speed VHO due to the movement of the object, and a changing amount detecting means 3 outputs the changing amount DELTADF of the defocus quantity, based on the speed VHO. A reliability deciding means 4 decides the reliability of the DFO from the focus detecting means 1, and when the DFO is unreliable, the focusing lens is driven by means of a lens driving means 5 based on the changing amount DELTADF, so that the lens can follow the movement of the object.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic focusing camera that drives a focusing lens toward an in-focus position according to a focus detection result. It is particularly suitable for cameras.

[Prior Art] Conventionally, in Japanese Patent Application Laid-open No. 61125311, tracking control is performed in an automatic focusing camera to drive a lens in accordance with the speed of the subject when the previous and current defocus directions are the same. It is proposed that. However, this prior art does not propose performing tracking control in a state where focus detection is impossible.

[Problems to be Solved by the Invention] Automatic focusing cameras have a problem in that the focusing accuracy when photographing a moving subject is lower than the focusing accuracy when photographing a still subject. This is because if the subject is moving, even if the lens is driven to the in-focus position at the time of the current focus detection and the shutter is released, the subject will deviate from the in-focus position until the shutter is released. Therefore, as in the prior art described above, when the defocus direction is the same between the previous and current shots, it is considered that the subject is moving, and tracking control is performed to drive the lens in accordance with the speed of the subject. It will be done. Such tracking control is performed on the premise that the focus detection result is reliable, and the concept of performing tracking control even when the focus detection result is unreliable has not been proposed in the past. For example, Japanese Patent Application Laid-Open No. 58158624 proposes not to drive the lens if it is determined that the reliability of focus detection is low during continuous shooting. However, when continuously photographing a dynamic subject, if the lens is not driven, the lens will follow the movement of the dynamic subject and the amount of defocus will increase, making focus detection increasingly difficult.

The present invention has been made in view of the above points, and its purpose is to enable the lens to be driven to follow the movement of a dynamic subject even if focus detection becomes temporarily impossible. The purpose is to provide an autofocus camera.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the automatic focusing camera according to the present invention, as shown in FIG. Based on the output of the focus detection means (1) that detects (defocus DFO), the change speed detection means (2) that detects the change speed VHO of the amount of defocus due to the movement of the subject, The amount of change Δ in the amount of defocus due to the movement of the subject
A change amount output means (3) for outputting DF, a reliability determination means (4) for determining reliability of focus detection, a lens drive means (5) for driving a lens for focus adjustment, and a reliability determination means for determining reliability. and tracking control means (6) for controlling the lens driving means (5) based on the output of the variation output means (3) when the reliability of focus detection is determined to be low by the means (4). This is a characteristic feature.

Here, when the camera is a reflex camera having a continuous shooting mode, the tracking control means (6) controls the lens driving means (5) based on the amount of change ΔDF during mirror up.
It is preferable to use it as a means for controlling. Further, when the reliability determination means (4) determines that the reliability of focus detection is low for a predetermined number of consecutive times, the tracking cancellation means (7)
It is preferable to prohibit the operation of the follow-up control means (6).

However, FIG. 1 is an explanatory diagram showing the configuration of the present invention in functional blocks, and in the embodiments described later, the main part of the above configuration is realized by a microcomputer program. To show a specific correspondence, the focus detection means (1) is #107 in FIG. #113, the rate of change detection means (2) at #313 in FIG. 10, the amount of change output means (3) at #405 in FIG.
4) is #308 in FIG. 10, the lens driving means (5) is #359 in FIG. 11, and the tracking control means (6) is #357 in FIG. In #359, the following cancellation means (7) is the 10th
Each corresponds to #311 in the figure.

[Effect] Hereinafter, the operation of the present invention will be explained with reference to FIG.

The focus detection means (1) detects the focus state of the photographic lens with respect to the subject to be focused, and outputs the amount of defocus (defocus DFO). Here, defocus D
FO is a variable whose sign indicates the direction of defocus and whose absolute value indicates the magnitude of defocus.

The change speed detection means (2) is a multiple defocus DFO.
From this, the rate of change VHO of the defocus DFO due to the movement of the subject is detected. Then, the change amount output means (3) outputs the change amount ΔDF (=vHoxT) in the amount of defocus due to the movement of the subject based on this change rate VHO.

The reliability determining means (4) determines whether the defocus DFO determined by the focus detecting means (1) is reliable. When the defocus DFO is reliable, the focusing lens is driven toward the in-focus position by the lens driving means (5) based on the defocus DFO.

At this time, if the change amount ΔDF is not zero, the focus position may be corrected by adding the change amount ΔDF to the defocus DFO. On the other hand, if the defocus DFO is unreliable, the defocus DFO is regarded as zero, and the focus adjustment lens is controlled by the lens drive means (5) under the control of the tracking control means (6) based on the amount of change △DF. is driven to follow the movement of the subject. In this case, although the subject is not necessarily in focus, at least the lens is driven to follow the movement of the subject, so the focus will not deviate significantly from the subject. Therefore, later on, when the defocused DFO returns to a reliable state,
Focus can be achieved with a small amount of lens drive. In addition,
When the defocus DFO is unreliable for a predetermined number of consecutive times, the following control means (
6) is prohibited. This can prevent lens driving based on uncertain information from continuing for a long time.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a single-lens reflex camera with interchangeable lenses, where 101 is a camera body and 102 is a zoom lens which is an example of an interchangeable lens (photographing lens). A main mirror 103 is composed of a reflecting part and a transmitting part. The light passing through the photographic lens is reflected by the reflecting part of the main mirror [03], and is then sent to the finder optical system (not shown).
While being led to the
Leads to 4. Sub mirror 104 is main mirror 103
The light that has passed through is reflected to the focus detection module 105.

FIG. 3 is a miniature view of the camera body 101 from the front. As mentioned above, 101 is a camera body] 03 is a main mirror, 105 is a focus detection module, 106 is a mechanical unit 1~ configured to automatically perform mirror up, exposure operation, and film winding-E (s). Since these are not directly related to the present invention, their explanation will be omitted.

FIG. 4 shows a circuit diagram of a camera to which the present invention is applied. Reference numeral 201 is a camera control microcomputer that performs functions such as sequence control of the entire camera, exposure calculation control, and auto-focus (hereinafter abbreviated as AP) calculation control. It is equipped with input/output terminals P1 to P21, etc. 202 is an AF distance measuring unit that measures the amount of defocus of a subject image, and includes a one-dimensional self-scanning image sensor (hereinafter abbreviated as CCD), a CCD drive unit, an A/D conversion unit, and a reference power source for A/D conversion. Consists of sources etc. The image information obtained by this CCD is
The data is taken into the CPU 201 via the data bus 201a. 203 is a display unit consisting of a liquid crystal display (LCD) or a light emitting diode (LED), and displays the shutter speed Tv and aperture value A, which are the calculation results of automatic exposure (hereinafter abbreviated as AE) sent from the CPU 201.
This display unit 203 displays information such as v, focus/out-of-focus, and shooting mode. A lens data circuit 204 is provided inside each interchangeable lens 102 and stores the maximum aperture value, minimum aperture value, focal length, extension amount conversion coefficient necessary for focus adjustment, etc., and is used to connect the interchangeable lens 102 to the camera body. 101, the data is transmitted to the camera body 101 via an electrical contact provided near the mounting part. 6205 indicates the brightness B of the subject.
It is a photometry unit that measures v, and includes a photoelectric conversion element for light reception, A/
It is composed of a D conversion section, a reference voltage source for A/D conversion, a data exchange section with the CPU 201, etc., and measures the light that has passed through the photographic lens according to a command from the CPU 201. Reference numeral 206 denotes a film sensitivity reading unit that automatically reads the sensitivity of the loaded film, and reads the film sensitivity of the film cartridge chamber through an electrical contact provided in the cartridge chamber of the camera.

1) Each information of the display section 203, lens data circuit 204, photometry section 205, and film sensitivity reading section 206 is transmitted as a serial signal via the serial data bus 20lb to the serial input/output section 201c (in the figure, the serial I10
(abbreviated as ). 207 is film winding.
This is a driver control unit for exciting the sequence motor M1 for rewinding, the AF momo-M2 for driving the lens for AF, and various magnets required during exposure operation. It is controlled by control outputs 11CMDO to CMD8. S
W1 to SW3 and SW5 to 5WIO are switches, one end of which is grounded, and the other end connected to input terminals P1 to P7, P2O, and P21, respectively. SWl is a switch that turns ON when film charging starts and turns OFF when film charging is completed. SW2 is a switch that turns ON while the mirror is up and turns OFF when mechanical charging is completed. SW3 is a switch that turns 0N1 multiple times while the film is running.
This is a switch that repeats 0FF. SW5 is a photometry switch that is turned on at the first step of pressing down a shutter button (not shown), and the CPU 201 outputs a signal to start photometry and distance measurement. While this switch SW5 is ON, if the lens is in an out-of-focus position due to distance measurement, the lens continues to be driven, and when it reaches the in-focus position, the lens stops driving, but while the lens is being driven, the shutter The button is released,
When the switch SW5 is turned off, the driving of the lens is stopped. SW6 is turned on in the second step of pressing down the shutter button.
This is a release switch, and if this switch SW6 is turned on when release is possible, the CPU
201 commands a release operation. Note that when the release switch SW6 is turned on, the photometry switch SW5 is configured to be kept in the on state. SW7 is a film detection switch provided in the film travel path. When there is film at this film detection switch SW7, the switch SW7 is OFF, and when the film runs out, it is ON. When rewinding, When this switch SW7 changes from OFF to ON, it indicates that the film is slightly out of the cartridge, and is used as a switch for determining the end of rewinding. SW8 is a cartridge detection switch provided near the electrical contact of the film sensitivity reading unit 206 provided in the cartridge chamber of the camera, and is turned ON when a cartridge is placed in the cartridge chamber and the back cover is closed. , it will be in the OFF state if there is no cartridge. SW9 is a back cover opening/closing switch, which is turned ON when the back cover is completely closed. 5WIO is a multiple exposure mode changeover switch, and when it is turned on, the multiple exposure mode is set.

RESET is set to control power supply voltage +vDD by resistor R1.
After the power is turned on, capacitor C1 is charged via resistor R1, and the CPU 201 is reset when the voltage changes from the "lL0ulI+" level to the "High" level. X is a crystal oscillator for providing a clock signal to the CPU 201.

Next, the driver control section 207 and each control section will be explained. ICMg is a magnet for holding the first shutter curtain, and when the control output line ICMGO reaches the ``Loud'' level, the magnet ICMH is energized and the first shutter curtain is held. 2CMg is a magnet for holding the second shutter curtain, and the control output line 2CMGO is I L
When the Z level reaches 0III+, the magnet 2CMg is energized, the second shutter curtain is held, and after releasing the first shutter shutter, the second shutter is released.
The time it takes for the curtain shutter to release its hold corresponds to the shutter speed. FMg is a magnet for locking the aperture of the photographic lens, and the control output line FMGO is
When the l+t level is reached, the magnet FMH is energized to hold the aperture locking member, and when the holding is released,
The aperture lock member is actuated to lock the aperture in place.

RMg is a magnet for the release, and the control output line R
When MGO is at 1'L 0ulI+ level for a certain period of time,
The release member is unlocked, the aperture is narrowed down, and the mirror is raised.

Q1 to QIO are sequence motor M and AF momo-M
This is the second driving transistor. This Z-Kensmoke M1 has two types of coils inside, and can obtain the characteristics of high-torque, low-speed rotation and low-torque, high-speed rotation.It is possible to switch between both characteristics, and it is also possible to rotate in the forward and reverse directions of each. Transistors Q1 to Q6 are connected in this manner.

That is, the high speed side terminal I of the sequence motor M1 is 1.
The low speed terminal C is connected to a common connection point between transistors Q1 and Q2, the low speed terminal C is connected to a common connection point between transistors Q3 and Q4, and the remaining common terminal C is connected to a common connection point between transistors Q5 and Q6. Table 1 shows how the rotational state of the sequence motor M1 changes depending on the on/off states of the 1-transistor transistors Q1 to Q6.

Table 1 Note that in this embodiment, the high speed brake is not used, and only the low speed brake is used. Therefore, what is described as a brake in the following explanation is a low-speed brake SBR.
It is about. Q7 to QIO are transistors for driving the AF momo-M2, and are connected in a bridge shape so that the AF momo-M2 can rotate in forward and reverse directions. AF Momo-M2
Rotate in the forward direction to extend the lens, and in the reverse direction to retract the lens.

OM1~○M ], O is each transistor Q1~Q10
This is the control output line for the switching link.

211.2]-2 is an aperture encoder and an AF encoder consisting of photocouplers, and input signal lines PTI, P
It is connected to the driver control unit 207 by T2.

The aperture encoder 21] monitors the stroke of the aperture preset lever at the time of release, and at the time of release, the light emitted by the light emitting diode 21a is detected by the foI-1-run sister 211b, and is sent to the driver control unit via the input signal line PT. 207 is input. Then, after being waveform-shaped into a pulse by this driver control unit 207, it is sent to the input terminal P18 of the CPU 20 via the output signal line FP. The AP encoder 212 is for monitoring the rotation speed of the AF Momo-M2 for driving the lens during AF, that is, the amount of movement of the lens.
Light emission from the light emitting diode 21.2a is detected by the photodiode 1 to the transistor 212b, and is input to the I/river control unit 207 via the input signal line PT2. and,
After being waveform-shaped into a pulse by this driver control unit 207, it is sent to the input terminal P19 of the CPU 201 via the output signal line AFP. This output signal line AFP is C
It is also connected to a counter 201d inside the PU 201, and is used to monitor the extended position of the photographic lens. That is, the counter 201d is cleared to O at the end of the lens ω, and when driving in the near direction, the counter 201d is cleared to O at the end of the lens ω.
By setting the down count during directional driving, it is possible to obtain the number of pulses extended from the ω end of the lens at any time. This AFP signal is also connected to an interrupt terminal (not shown) of the CPU 201, and an interrupt is generated at the falling edge of the AFP signal. Further, the CPU 201 has a built-in timer 201e, and is configured to be able to read the time by counting an internal clock.

Furthermore, the CPU 201 has a built-in so-called E2PROM 201f that can only be electrically written and read, and retains memory contents even when the power is turned off. Also, C.P.
U201 includes an interrupt timer (not shown) that generates a timer interrupt when a set time has elapsed.

(Margin below) Table 2 In the table, H is “High” level. L means "Lo..." level.

Table 3 In the table, H is “use-high” level. L means 'LoIlI'° level.

CMDO to CMD8 are control output lines output from output terminals P8 to P16 of the CPU 201 to control the driver control unit 207, and CMDO and CMDI are control output lines R for controlling magnets RMg and FMg, respectively.
Control MGO, FMGO, CMD2. CMD3 controls control output lines ICMGO and 2CMGO for controlling magnets ICMg and 2CMg, respectively. Also, CM
Control output lines OM1 to OM6 for driving the sequence motor M1 are controlled by D4 to CMD6, and CMD7. CMD8
Control output line OM7 to 0M for driving AF motor M2
Control l0. Table 2 shows the control of the sequence motor M1, and Table 3 shows the control of the AF motor M2. In the table, H means "High" level and L means "Low level."

AMg is a lock release magnet that holds the film still, and is a magnet for releasing the film. CPU2 via resistor R2
01 output terminal P17. Transistor Ql
The connection point between the base of 1 and the resistor R2 is grounded via the resistor R3. The output terminal P17 of the CPU 201 is normally “Lo”.
ud'' level and the transistor Qll is off, so the magnet AMH is not energized and holds the suction piece by suction.In order to release the engagement between the winding stop and the winding stop lever, the CPU 201 Output terminal P17?
When it reaches the 'Hi) (h''' level, the magnet AMg is energized and the attraction force disappears.

Next, a series of release operations in this embodiment will be explained with reference to FIG. As shown in the figure, the release operation is roughly divided into four sequences: mirror up, exposure, mechanical charge, and film charge.

In the mirror-up sequence, the main mirror sub-mirror is retracted, and the aperture of the photographic lens is disengaged to narrow the aperture. In the exposure sequence, the exposure time (shutter speed) is controlled by controlling the first and second curtains of the focal plane shutter. In the mechanical charge sequence, the main mirror, sub-mirror, photographic lens aperture, and shutter curtains 1 and 2 are energized by springs for the next release.

In the film charge sequence, the film is advanced.

A more detailed explanation will be given below using time chart 1~. As already explained in FIG. 4, the switch SW6 is
By pressing down the shutter button two steps, it turns on and starts the release operation. When the release operation starts, first, by setting the control output line RMGO to the "Loud'" level, the release magnet RMg is energized,
Release the main mirror that is biased by the spring. As a result, the main mirror is retracted to the finder side, and the sub-mirror is also retracted in conjunction with the main mirror. Next, the control output line FMGO is set to ``Low''.
``By making it a lever, it is possible to lock the diaphragm.
energize F M g to release the diaphragm of the photographic lens which is biased by the spring. When the lock is released,
The aperture starts, but the state of the aperture at this time is 4th.
As explained in the figure, input from the monitor photo I to the transistor 211b to the driver control unit 207,
The waveform-shaped FP multiplied signal is input to the CPU 201 . The CPU 201 generates a number of FP multiplication signals corresponding to the aperture value based on a predetermined exposure calculation, and outputs a control output line FMGO.
By setting the aperture to the 'High' level, the aperture is stopped and the photographing lens is set to the desired aperture value.Next, in order to perform the exposure operation, the 'Lou+' level is set at the start of the release.
Among the control output lines ICMGO2CMGO that are set to the 'High' level, one of the control output lines ICMGO is set to the 'High' level. As a result, one curtain of the focal plane shutter runs. After the exposure time based on the predetermined exposure calculation has elapsed, the other control output line 2CMGO is set to the "High" level, thereby causing the two curtains of the focal plane shutter to run and exposure control to be performed. After exposure, a mechanical charge sequence begins. In the mechanical charge sequence, first, a high 1-lux is required when starting the Z-Ken Smoke M1, so it is driven in low-speed mode F (L), and then, when the specified rotation speed is reached, low-torque high-speed rotation is performed. Switch to high-speed mode F(H). As a result, the sequence motor M1 can be driven efficiently, and high-speed mechanical charging and film charging can be achieved.

This rotation of the Z-ken smoke M1 causes the main mirror and the submirror to be lowered and biased by the spring, and at the same time, the aperture of the photographing lens and the first and second curtains of the focal plane shutter are also biased by the spring. When this mechanical charging is completed, as already explained, the switch SW2 is turned off as a mechanical charging completion signal. CPU
When the switch 201 detects that the switch SW2 is turned off, it shifts to the film charging sequence. This releases the lock that fixes the film and starts winding the film. At this point, switch SW1 for monitoring film charging is turned on, and film winding is performed by sequence motor M1. When film winding for one frame is completed, switch SWI is turned to O.
It becomes an FF and is notified to the CPU 201. CPU20]
When it detects that the switch SWI is OFF, it applies a brake (not shown) to stop the sequence motor M1. This completes the release operation for one frame.

Next, while the switch SW6 is ON, the sequence for continuous shooting mode 1 in which the camera is released continuously will be explained, including the focus detection operation, with reference to the time chart shown in FIG. Section I in FIG. 6 indicates the first frame of continuous shooting, and section ■ indicates the second frame of continuous shooting. The section I of the first frame of continuous shooting is as explained in FIG. By the way, in order to perform focus detection, it is necessary that the main mirror and sub-mirror are lowered and stable. Therefore, the switch SW2 is turned OFF, and after the mechanical charging is completed and a period of time for mirror stabilization is waited, CCD integration is started. In this embodiment, this waiting time is set to 30 m5ec. 1 in the figure.
The part indicated by is the CCD integration time, D, and the part indicated by is CC.
It shows the data dump time for A/D converting the pixel data of D and taking it into the memory of the CPU 201. When the pixel data of the CCD is taken into the CPU 201, reliability of defocus, defocus direction, and focus detection is determined by predetermined calculations. Since this focus detection calculation is not directly related to the present invention, a description thereof will be omitted. Well, 1
When the first film charge is completed, switch SW1
is turned OFF, and the low speed brake SBR is applied to the sequence motor M.

At this point, the CPU 201 determines whether the switch SW6 is ON. If the switch SW6 is ON and the continuous shooting mode is set, then the second frame, which is indicated by section 3, starts to be released. In the case of this second frame, in order to release the film immediately after charging the film, in order to ensure that the film stops, wait for a while with the low speed brake SBR applied to the Z-Kensmoke M, and press the release magnet RM.
g is energized. Now, if the result obtained in calculation 1 is that the camera is in focus, you can take an in-focus photo even if you release the camera next time with the photographic lens stopped, but if it is not in focus, you can continue to release the camera next time. For example, out-of-focus photos may be taken. In particular, when shooting in continuous shooting mode, there are many cases where the subject is moving and the defocus changes over time, so in calculation 1, the defocus due to the movement of the subject is Detect minutes. By performing this defocus drive while the mirror is up, it is possible to obtain an in-focus photograph even at the next release. A in Figure 6
The AF Momo-M2 column shows the driving state of the photographing lens by AF Momo-M2, and one line indicates the OFF state and the AFM
indicates that it is being driven in either direction.

To compensate for the defocus amount obtained as a result of calculation 1 or for the movement of the subject, the photographing lens is driven during mirror up in the next section (3). Further, when the control output line RMGO is at the "'Lou+" level, that is, when the release magnet RMg is energized, the AF momo-M2 is de-energized. this is,
The current flowing through the release magnet RMg is very large, and if AF Momo-M2 is driven during this time, the driving accuracy of AF Momo-M2 will drop, or the current will flow to the release magnet RMg. This is to avoid the problem that the mirror may not be able to be raised because the current decreases and the lock for raising the mirror is released.

Thereafter, similarly to the first frame, the release is continued while the switch SW6 is ON.

Next, the operation of this embodiment will be explained using the flowcharts from FIG. 7 onwards. FIG. 7 is a flowchart when the photometry switch SW5 mentioned above is turned on. When the switch SW5 is OFF, the camera is in a low power consumption mode, a so-called sleeve mode. When the switch SW5 is turned on, clock oscillation starts and is activated. C
When the PU 201 is activated, it sends an activation signal and a clock to the peripheral IC in #101, and performs activation processing such as initializing the boat. Next, in #102, flags, constants, etc. used in the program are initialized. continue,#
At 103, switches in each part of the camera body are checked, and serial communication is performed with the flash, lens, display element, etc. Further, in order to discharge unnecessary charges from the COD, which is a focus detection element, initialization is performed at #104.

Next, the process proceeds to focus detection processing CD INTA (#105 and subsequent steps). First, prior to the integration of COD, #10
In step 6, the integration start time is input to the memory TMI of the CPU 201 from the timer and saved.

Similarly, the counter indicating the lens position mentioned above is read and saved in the memory T1. Thereafter, in step #107, CCD integration is performed to obtain a signal level appropriate for focus detection. When the CCD integration is completed, the timer value is saved in the memory TM2 and the counter value is saved in the memory T2 in #108. Next, in #109, save the value of the memory TM in the memory TML, and save the value of the memory TM in the memory TM (TM2
- Save TMl)/2. TMI and TM2 indicate the integration start and end times, respectively, (TM2TMI)
/2 means the time of the center of integration. That is, #109
Then, the previous integration center time is saved in the memory TML, and the current integration center time is saved in the memory TM. Similarly, regarding the counter value, the value of the memory MI is safe in the memory MIL in #110, and the value of the memory MI is saved in the memory MI (T2'
- Save Tl)/2. As mentioned above, since the counter value corresponds to the lens position, Tl and T2 indicate the lens position at the start and end of integration, respectively, and (T2 - Tl
)/2 indicates the lens position at the center of integration. That is, in #110, the previous lens position of the center of integration is saved in MIL, and the lens position of the current center of integration is saved in MI.

Next, in #111, each pixel data of the CCD is sent to the CPU2.
Dump data to be input to 01. Using this CCD pixel data, before starting the focus detection calculation, the value of the memory DFO is saved in the memory LDF in #112. At this point, focus detection by CCD integration in #1o7 is not performed, so the process in #here2 is to save the previously detected focus DFO in the memory LDF. In #113, #10
Focus detection calculations are performed based on the CCD pixel data integrated in step 7, and the defocus DFO and telefocus direction of the photographing lens as well as the reliability of focus detection are calculated. Next, serial communication and exposure calculation are performed in #114.
The photometric value is displayed, each switch is sensed, etc. For example, switch SW5 is OFF between #107 and #114.
When F is reached, it is detected in #114, processing such as display off, motor off, etc. is performed, and the state shifts to sleeve state I\ again. When the serial communication and exposure calculation are completed, the process proceeds to #115, where it is determined based on the flag VLYF whether or not a snapshot is currently being taken. This continuous shooting flag ■L Y F is set when the photographer switches to continuous shooting mode during the winding operation, which will be explained later.
! Set to 1 if selected. If the continuous shooting flag ■LYF is 1 after determining #15, then the quick shooting AF (
The flow branches to #301). The flowchart of continuous shooting AF will be explained in detail later using FIG. 10.

Now, if the continuous shooting flag V L Y F is 0, #1]
The process advances to step -6, and it is determined whether or not the camera is in focus. In this focus determination, if the reliability of the focus detection in #113 is higher than a predetermined value and the defocus DFO is smaller than a predetermined amount, it is determined that the focus is in focus. The predetermined amount in this case is set to 100 μm. In addition, this value is 60μm + 8
1) may be set. Here, FNO is the F number of the aperture value.

In addition, this predetermined amount is the E2P of the CPU 201 explained earlier.
It is written in ROM20 if. by this,
Users who desire high precision can write small values, while those who desire feel and focusing time can write large values, making it possible to respond to users in detail.

#] If focus is determined in 16, proceed to #117,
Focus is displayed. After in-focus display, exposure recalculation and serial communication are performed. This is done in order to reflect the focus detection result in the exposure calculation. Thereafter, the process waits while performing serial communication in #120 until the ON state of the switch SW6 is detected in #11.

#] If it is determined that the focus is not in focus in 16, #12J
The process proceeds to the subsequent out-of-focus processing 0UTFS.

First, in #122, the focus display is turned off, and then in #123, as a result of the focus detection calculation, if it is determined that the focus detection result is not used due to low reliability, that is, it is determined that the focus is low, the AF mode is turned off.
In order to perform the next focus detection without driving M2,
The process branches to focus detection processing CDINTA after #105. If it is not low contrast, proceed to #124 and A, F.
After starting the drive of the motor M2 and waiting until the drive is completed in #125, the process proceeds to focus detection processing CD INTA starting from #105 in order to perform the next focus detection. In #124, the number of drive pulses ERRCNT for the AF motor M described above is calculated by multiplying the defocus DFO by the conversion coefficient KL obtained from the photographic lens.

In other words, the number of drive pulses ERRCNT is ERRCN T
= Determined by DFOXKL. #125
Now, the AFP for monitoring the rotation of AF Momo-M2.
A until the signal is detected for the number of drive pulses ERR, CNT.
F momo-M2 is driven. Note that this conversion coefficient K L
differs depending on the focal length of each photographic lens, and is sent from the photographic lens through serial communication. Thereafter, the same process is repeated again from #105 until focus is determined in #116.

Next, a description will be given of the processing after the ON of the switch SW6 is detected in #119. In #126, it is determined whether the number of drive pulses ERRCNT is smaller than the constant NPI written in the aforementioned E2PR○M2O1f (#126). The number of driving pulses ERRCNT is a constant NP
If the number is greater than I, a constant N is added to the drive pulse number ERRCNT.
Please reset PI #127>, drive pulse number ERRCN
If T is smaller than the constant NPI, continue as #12
Proceed to 8. In #128, it is determined whether the defocus DFO determined in focus in #116 is smaller than the constant DFCI. If DFO<DFCl, the process branches to release (#131) to immediately perform a release operation. If DFO≧DFC1, proceed to #129,
It is determined whether the number of drive pulses ERRCNT is smaller than 4 pulses. If the drive pulse number ERRCNT is smaller than 4 pulses, the process immediately branches to release (#131). If the number of driving pulses ER, RCN T is 4 pulses or more in #129, driving of the AF momo-M2 is started in #130. In the processes from #126 to #131, it is determined whether or not to drive the photographing lens during mirror up.

As already explained, in #116, focus determination is performed based on whether the detected defocus is within a predetermined defocus range. If this focusing range is shifted by a very small amount, accuracy will increase, but it will take time to achieve focusing due to variations in focus detection, camera shake by the photographer, etc. Alternatively, problems such as small hunting of the photographic lens may occur. Furthermore, when the subject is a moving object, the detected defocus changes moment by moment, so no focus determination is made. For this reason, this focusing range is set to be wide enough to absorb variations in focus detection or changes in defocus due to changes in the subject. However, in this case, the defocus corresponding to the focusing range remains as an error. For this reason, this remaining defocus is used during mirror up to create an even more accurate autofocus camera. Also, in order to shorten the time until release, the number of pulses that can be driven during mirror up is limited to a constant NPI #126. #127), if sufficient accuracy is ensured, that is, in #128 DFO<D
If it is FCI, or if the drive pulse number ERRCNT is smaller than 4 in #129, AF Momo-M2
The drive accuracy of the camera is also taken into consideration, and the shutter is released immediately.

Next, a series of release controls (from #201 onwards) including mirror up, exposure time control, mechanical charging, and film winding will be explained using FIG. First, #2
At #02, the flag RMGONF indicating that the release magnet (RMg) is energized is set to 1, and at #203
In step #204, power is applied to AF MOMO-M2 (○FFL), in step #204, power is applied to release magnet RMg, shutter curtain holding magnet) ICMg, and 2 CM g. after that,#
After waiting for a time at 205, the energization to the release magnet RMg is set to 0FFL at #206, and the flag R is set at #207.
Clear MGONF to O. Through the processes from #2b04 to #206, the main mirror sub-mirror is unlocked and mirror-up is started. Also,#
Magnet R by the processing of 202, #203, #207
While power is being supplied to MF1, power supply to AP Momo-M2 is prohibited. Specifically, AF Momo-M2 is controlled by a timer interrupt that occurs every predetermined time.
When the flag RMGONF is 1, ON and braking of AF MOMO-M2 are both prohibited, and AF MOMO-M2 is turned OFF.

When the flag RMGONF is reset, driving of the AF momo-M2 is automatically restarted by a timer interrupt. The above process requires a large current to energize the release magnet RMg, and when AF Momo-M2 is energized, the current flowing to the magnet RMg is insufficient, and the lock cannot be released and the mirror cannot be raised. This is done to prevent any inconvenience.

When the mirror up is started, the magnets 1 to FMg for locking the aperture are subsequently energized in #209.

As a result, the diaphragm of the photographic lens is unlocked and the aperture of the photographic lens is started. At #210, the pulses of the aperture encoder 211 described above are sent to Curran 1, and when the pulses set by the exposure calculation are divided, at #211, the magnet FMFi is de-energized and the aperture is fixed. After this, at #212, release magnet RMg
Wait for the predetermined time L1 to elapse after energizing #2J.
Proceed to step 3. In #213, in order to prevent the photographing lens from being driven during exposure, turn off the power to the AF MOMO-M2, and then in #214 turn off the sequence motor M.
Make it F. As already explained, in the case of the second and subsequent frames of quick shooting, the brake of the Z-Kensmoke M1 is applied until it is turned off at #214.

#215: Magnet for holding shutter 1 curtain], C
By turning off the power to M, the first curtain of the focal plane shutter runs, waits for the shutter speed in #216, and turns off the power to the magnet 2CM8 for holding the second shutter curtain in #217. west,
Run the second curtain of the focal plane shutter.

This completes the exposure. In #218, the timer value is saved in the memory TIME1. At #219, in order to wait for the second curtain of the focal plane shutter to complete its travel, it waits for a predetermined time t18 to elapse, and then moves to winding (#220).

In the hoisting routine shown in FIG. 9, first, the sequence motor Ml is energized in low speed mode in #221, and
After waiting for a predetermined time until the rotational speed of the motor M1 increases at #22, high-speed mode energization is performed at #223. As a result, the mechanical charging progresses, and the process waits until the switch SW2, which is the mechanical charging completion signal, turns OFF at #224.

When the switch SW2 is turned OFF and the mechanical charge sequence is completed, the main mirror and the sub-mirror are down, so TTL photometry becomes possible and photometry is started at #225. In order to proceed to the film charge sequence, as described above, the stop release mcnet A M g for stopping the film is energized for a predetermined time t6 (#226).

After that, wait for a predetermined time tlo (#227>) and move on to #228. This predetermined time tlo is set to 3Qmsec in this embodiment, and is a waiting time to stabilize the submirror. In #228 In this case, it is determined whether or not the quick shooting mode is selected by the photographer, and if it is, the continuous shooting flag VLYF is set to 1 in #229 without indicating that quick shooting is in progress. In order to perform focus detection next time, focus detection processing C after #105
Proceed to DINTA (#230). On the other hand, if it is not the snapshot mode, the #
After waiting at 231, focus detection processing CD after #105
Proceed to INTA.

The automatic focus adjustment operation during quick shooting will be explained using the flowchart shown in FIG. #1 from #230 in Figure 9
Focus detection processing CD after 05 1. After proceeding to NTA, focus detection calculation and exposure calculation are performed as explained in FIG. 7, and the process branches to continuous shooting AF (#301) in #115. Next, at #302, exposure calculation and serial communication based on the photometric values started at #225 in FIG. 9 are performed.

This makes it possible to always obtain appropriate exposure even if the subject brightness changes during quick shooting. Subsequently, in #303, the process waits until the switch SWI is turned off. That is,
Focus detection during film charging is limited to one time. This is to prioritize the next release since it is a quick shooting mode.

When the OFF state of the switch SWI is detected, the film charging sequence has ended, so the sequence motor M1 is immediately braked at #304. In #306, it is determined whether the time required to wind the film is longer than a predetermined time. Film winding time varies greatly depending on the tension of the film, power supply conditions, number of frames, etc. If it is determined in #3.6 that the film winding is slow, then in #307 the following mode flag TF and the following initial flag Tl5TF are reset, respectively. The following mode flag TF will be explained later, but when the subject is a moving object, it is set in the following mode to correct the movement of the subject. When it is determined in #306 that the film winding is slow, the interval between snapshots is long and an error occurs in the correction of the subject's moving bones, so the tracking mode flag TF is reset.

In #308, it is determined whether the focus detection result is low contrast. If the contrast is not low, the process branches to #309 and the previous ignore flag LIF is reset. This previous ignore flag LIF is set when the next release is performed while ignoring low contrast during continuous shooting. Next, in #310, VHO is stored in VHI as the previous defocus speed (velocity at the image plane of the subject), and in #313, the current defocus speed VHO is stored in VHI.
seek.

The calculation of the defocus speed VHO in #313 is performed as follows. At the time of #313, the current focus detection result is stored as a defocus DFO. The previous focus detection result is saved in the memory LDF by the process #112 in FIG. Also, the lens position at the center of integration of the CCD that obtained the defocused DFO is:
Through the process #110 in FIG. 7, the lens position at the center of integration of the CCD at which the previous defocus LDF was calculated is saved in the memory MIL. As a result, the defocus change δDF caused by the movement of the subject is: δDF=DFO-LDI-(MI-MIL)/KL...
・It is calculated as ■. DFO-LDF is the change in defocus, and (M I - M I L)/KL is the defocus due to the movement of the lens during that time. On the other hand, the time Δt required during that time can be determined by subtracting the previous integration center time from the current integration center time.

From the process #109 in FIG. 7, Δt=TM-TML...■ is calculated. From equations (1) and (2), the subject speed VHO is determined as VHO-δDF/Δt.

After determining the subject velocity VHO in #313, the process proceeds to #319. On the other hand, if it is determined in #308 that the contrast is low, the process advances to #311. In #311,
Determine whether the previous ignore flag LIF is 1 or 0. If it is cleared to 0, proceed to #312, set the previous ignore flag LIF, and set the current detected defocus DFO.
Set 0 to 0 and drive pulse number ERRCNT to 0. #3
In step 11, if the previous ignore flag LIF is set to 1, the process branches to the cancellation routine 0UTRV2 in #314, and in #315, the following mode flag TF and the following initial flag Tl5TF, which will be explained later, are reset, respectively.
After clearing the continuous shooting flag VLYF in #317, the 7th
Jump to #121 0UTFS in the diagram (#318
). As described above, when low contrast is detected twice in a row during focus detection during continuous shooting by the processing from #308 to #318, the continuous shooting mode is canceled, the release operation is prohibited, and the process shown in FIG. According to the flowchart explained in , release is prohibited until focus is achieved.

As a result, in the case of a moving subject, even if the subject moves out of the focus frame during quick shooting or a subject with no contrast enters the picture, it is possible to take the picture at least once, reducing the probability of missing a so-called dramatic moment. is significantly reduced. Furthermore, the probability of significant defocusing is low. In particular, in the snapshot mode, the photographer often wants to give priority to the release, and this is particularly effective. Moreover,
If low contrast is detected twice in a row,
Since rapid shooting is interrupted at the point where the lens is in focus again, the release will not be continued with large defocus, and this may occur if the photographer is careless and takes continuous shots of an unintended subject, or if he or she moves his/her hand in front of the photographic lens. Even in cases where the film is covered with dirt, the film is not wasted. #312 has low contrast this time, so defocus DFO1
The number of drive pulses ERRCNT is undefined. Therefore, each of these is set to 0. Furthermore, since the defocus speed VHO cannot be calculated, it is not updated.

That is, the previously detected defocus speed VHO is used. Subsequently, in #3]9, it is determined whether or not the tracking mode is currently set. If the tracking mode flag TF has been reset and the tracking mode is not activated, the process advances to #320 and the defocus speed VH determined in #313 is
Compare ○ with constant VEI, and if VHO>VEI, set constant FZRE to INFZ which is the focusing range in #321.
If LI is VHO≦VEI, set it to constant F in #322.
Set ZREL2 respectively. FZRELL is F
It is set narrower than Z RE L 2. That is,
When the defocus speed V HO is small, the subject is stationary, and in this case the defocus change due to subject movement is small, so a wide focusing range is set, and when the defocus speed V HO is large, , since the defocus change is large, set a narrow focusing range. As a result, when the subject is stationary, there is little need to drive the photographic lens, and stable and fast shooting is possible.If the defocus speed VHO is greater than the predetermined speed VEI, By using a narrow focusing range, we achieved high-precision snapshots with little tracking lag. In addition, these constants VE], FZRELI, and FZREL2 are CPU
It is written in E2PROM201f in 201,
It can be rewritten according to the photographer's preference. In #323, the focus range INF set in #32] and #322
Z and the currently detected defocus DFO will be compared. If the defocus DFO is smaller than the focusing range INFZ, it is determined that the accuracy is sufficiently high, and the process proceeds to #370, where it is determined whether the switch SW6 is ON. If switch SW6 is ON, the photographer has requested the next release, and the camera jumps to the next release (#37).
. In other words, since the accuracy is ensured, the next release is performed without performing mirror-up driving. If switch SW6 is ○FF, release processing after #372 is 0.
Branches to UTRV, and in #373 and #374, continuous shooting flags V L, Y F, and initial tracking flag T1. After resetting the STF, select #105 for the next focus detection.
Jump to the subsequent focus detection process CDINTA (#
375).

On the other hand, in the judgment of #323, the currently detected defocus DFO
If the value is greater than or equal to the focusing range INFZ, the process advances to #324 to determine whether the photographic lens is driven or in tracking mode. In #324, it is determined whether the subject brightness is bright or dark. Specifically, the determination is made based on the integration time of the CCD and the gain multiplied by the output data, and if it is dark, the process branches to #333. If it is bright, the process proceeds to #325 and calculates the image magnification β of the subject. In #326, it is determined whether the image magnification β is larger than the constant BETALOCK. β> B E T A L O
In the case of CK, the process branches to #333. β≦BETA
In the case of LOCK, the process proceeds to #327, and it is determined whether the defocus speed VHO is greater than the constant RVMIN. If VHO≦RVMIN, the process branches to #33B, and if VHO>RVMIN, the process branches to #328. #328 Defocus speed V HO is constant R
Compare with VMAX.

If VHO≧RVMAX, branch to #333 and VHO
If HO<RV M A,X, proceed to #329. In #329, determine whether the current and previous defocus speeds obtained in #3]0 and #313 ■HOVH1 are in the same direction or in opposite directions, and if they are in the opposite direction, branch to #336. and # in case of same direction
Proceed to 330. #330 Follow-up first flag T], S
Determine whether TF is set to 1. If it is cleared to 0, branch to #335 and set to 1. If it is already set to 1, follow the mode in #331. The flag TF is set to 1 and jumps to the follow-up processing routine RNAFTI.

Through the processes from #323 to #332, tracking modes 1 to 1 for correcting changes in defocus due to movement of the subject are determined. In other words, if it is determined in #324 that the subject is dark, the CCD integration takes time and the noise component is large, so the defocus speed V HO cannot be adjusted accurately.
Since it is not required, it is not possible to enter follow mode. Also,
If it is determined in #326 that the image magnification is large,
Similarly, tracking mode cannot be used because the photographer's camera shake has a large effect. If the defocus speed VHO is less than the constant RVMIN in #327, it is impossible to determine whether the defocus change is caused by variations in focus detection or by the movement of the subject, and in order to avoid erroneous correction,
I can't enter follow mode. Even if the defocus change occurs due to the movement of the subject, the speed is slow, so the defocus change is small and can be ignored even without correction.

If it is determined in #328 that VHo≧RVMAX,
The change in defocus is abnormally large and cannot be considered to be a movement of the subject; it is determined that the subject has changed, that is, the camera has been shaken, and the tracking mode cannot be entered. If the directions of the previous and current defocus speeds VHI and VHO are reversed in #329, it is thought that the focus detection is unstable or the subject is moving irregularly, and there is a high possibility that incorrect correction will be made. I can't enter it. Furthermore, #330, #331, #33
By performing the process 5, the tracking mode is entered when the determination conditions #323 to #329 are passed twice in succession. This makes it possible to reliably determine whether or not the subject is a moving object, and there is no risk of erroneous correction. Also, the constant BETAL
OCK, RVMIN, and RVMAX are written in the E2PROM 201f built in the CPU 201.

If the direction of the defocus speed VHO is reversed in #329, particularly unstable focus detection or subject movement is expected, so proceed to the cancellation process 0UTRV3 after #336, and set the tracking mode flag in #337. TF, the initial tracking flag Tl5TF, and the continuous shooting flag VLYF are reset, and the process jumps to focus detection processing CDINTA from #105 onward to perform the next focus detection (#338). As a result, the next release is prohibited, and as explained in FIG. 7, the lens is driven until the lens is brought into focus again, so there is no need to worry about out-of-focus photography being performed.

If it is determined in #324, #326, #327, #328, and #330 that the process branches to #333, the currently detected defocus DFO is compared with the constant INFZEl. When DFO<INFZEI, the defocus is not very large and the reliability of focus detection is high, and sufficient accuracy is ensured even if the taking lens is driven by this amount of defocus while the mirror is up and the next release is performed. Therefore, the process branches to the drive routine RNMTR during mirror up. D
In the case of FO≧INFZE1, the defocus is large and if the next release is performed as it is, there is a possibility that accuracy cannot be ensured, so the canceling process 0UTRV2 hejump is performed (#334). By performing the processing in #333 and #334, when the defocus is small, high-precision automatic focusing and high-speed continuous shooting can be achieved by driving the mirror up, and when the defocus is large, it is possible to perform a transformation inspection. Highly accurate automatic focusing is achieved because the lens is brought out and focused.

In addition, if the defocusing process ○UTFS is entered after the cancellation process 0UTRV2 from #334, as explained in Fig. 7, the lens is driven by the amount of defocus DFO obtained during quick shooting this time, and then refocused. The detection is fast and accurate. Also, the constant INFZEI is the E2PR of CPU201.
It is written in the OM20if and can be changed according to the user's preference.

Now, the follow-up process RNAFTI executed by branching based on the determination in #319 or jumping from #332 will be explained with reference to FIG. First, in #340,
It is determined whether the directions of the current and previous defocusing speeds VHO and VHI are the same. If the directions are different, it is possible that the subject suddenly stopped, changed direction, or shook the camera. In this case, #3
The process branches to step 41, jumps to cancellation processing 0UTR, V3, cancels the tracking mode, and performs automatic focusing operation until focus is achieved again. This causes the subject to suddenly stop,
Even if you change direction or shake the camera, you can achieve high-precision focusing without making erroneous corrections.

If they are in the same direction, proceed to #342 and (VH
Compare O+VH1)/2 with the constant AVESH. (VH
O+VH1)/2 indicates n ] VHi from the process of #310, and becomes a weighted average value. In the above formula, n is the number of loops, and V Hi indicates the previous speed.

That is, in #342, the weighted average value and the constant AVES H
Compare with. The weighted average value is a constant A V E S i (
In the following cases, the weighted average value is reset to the defocus speed ■HO in #343, and if it is larger than the constant AVESH, the process directly proceeds to #344. In other words, in the case of low speeds, by performing weighted averaging, stable correction is achieved that absorbs variations in focus detection, etc., and in the case of subjects approaching at constant speed, the change in defocus is approximately equal to the distance. 2
Since the value increases in inverse proportion to the power of the speed, this achieves correction with good responsiveness and little follow-up delay at high speeds. Note that the constant A VE S H is E2PR, 0M201. It is written in f.

In #344, calculate the image magnification β and use the constant BETALOC
Compare with K2. As the image magnification increases, the influence of camera shake increases as described above, so the canceling process 0UTRV2 hejump is performed in #347, and the tracking mode is also exited. In addition, the constant BETALOCK2 is the E2PR of the CPU 201.
OM201. f and the constant BETALO
It is set larger than CK. #345 compares the defocus speed VHO with the constant RVOUT, and if the defocus speed VHO is within RVOUT, the defocus speed is sufficiently slow, and #347 Branch to. #346
Now, the defocus speed VHO and the constant RVMAX2 will be compared. Defocus speed V HO is R, VMAX2
If this is the case, it is determined that the defocusing speed is so fast that even if follow-up correction is performed, the delay will be large and defocusing will occur, and the process branches to #347. In step #347, the process jumps to the cancellation process 0UTRV2, cancels the tracking mode, prohibits the next release, and performs focus detection again. As a result, in the case of a very high-speed subject, the release is prohibited, and it is possible to prevent the camera from taking a picture of a subject that is too slow to follow. #344~#
The H.346 processing prevents erroneous correction and achieves highly accurate correction.

Subsequently, follow-up correction calculation 1 is performed in #348 to calculate the number of drive pulses ERRCNT. This calculation will be explained in detail later using FIG. 12. In #34, the defocus MDF after tracking correction is compared with the constant INFZE2. If the defocus after tracking correction is large, the process branches to #350 and jumps to the cancellation process 0UTRV21 from #316 onwards (FIG. 10) in order to improve accuracy.

As a result, only the continuous shooting flag V L Y F is cleared, the tracking mode is maintained, and the out-of-focus processing is shifted to 0UTFS. Constant INFZE2 is E2PR of CPU201
OM20] is written in Go. Also, this constant IN
FZE2 is the constant INFZE explained in #333
Set to greater than 1. This is because tracking correction is required, and unless the correction amount is large, the process cannot proceed to #351.

The steps after #351 are mirror-up drive processing, and #33
This is the branch from #3 or the flow from #349. First, in #352, it is determined whether the switch SW6 is ON. If the switch SW6 is OFF, the next release is not requested, so the process branches to #363 and the release process 0
Jump to UTRV. Subsequently, in #353, the number of driving pulses ERRCNT and the constant NPI are compared. As explained in FIG. 7, the constant NP is the number of pulses that can be driven during mirror up. If the number of driving pulses ERRCNT is less than or equal to the constant NPI, driving is possible during mirror up, and the process branches to #359.

If the number of driving pulses ERRCNT exceeds the constant NPI, the mirror cannot be driven for long while the mirror is up, so a driving time is required before starting the next release. Also, this A
The time required to drive the F Momo-M2 varies depending on the power supply conditions, characteristics of the interchangeable lens, etc. For this reason, the time until the next release start is fixed at 4.0 + n5ec, and if the number of driving pulses ERRCNT is 4Qmsec and the number of pulses that can be driven during mirror up next time (within constant NP2>), AF MOMO-M2 The number of driving pulses ERRC is
If NT exceeds the constant NP2, refocus detection is performed. As a result, 40 m5ec even in moving body mode
The tracking correction can be made accurately. Furthermore, even if you wait 40m5ec, the rapid shooting speed will only drop from 3 frames per second to 2.7 frames per second, and the deterioration of the continuous shooting feel will be minimal. moreover,
When the number of driving pulses ERRCNT exceeds the constant NP2, refocusing is detected, which solves the problem that the error associated with lens driving increases indefinitely.

If ERRCNT≦NPI in #353, the process advances to #354 and the tracking flag TF is determined. If #354 is tracking mode (TF=1), tracking correction calculation 2 for 40m5ec is performed in #355, if TF=0, #355 is skipped, and in both cases, drive pulse number ERRCN is set in #356.
Compare T with constant NP2. Drive pulse number ERRCNT
If exceeds the constant NP2, the process branches to #364 and jumps to the cancellation process UTRV2. #349, #35
If the next release is to be performed by driving during mirror up without detecting the focus again in the determination in step 6, it is determined that the camera is in focus, and the focus display is maintained. Subsequently, in #357, driving of the AF Momo-M2 is started, and in #358, the process waits for a time of 4Qmsec. At #359, the drive of the AF momo-M2 is started in case it branches from #353, and the process proceeds to continuous shooting release processing RNRELESE from #360 onwards. #3
61 is continuous shooting, so in order to completely stop the film, the camera waits for a predetermined time t11, and then jumps to the next release. As is clear from the above explanation, in the tracking mode, it is necessary to correct the defocus change caused by the subject, so the next release is not performed while the photographing lens remains stopped.

Next, the follow-up correction calculations after #401 will be explained with reference to FIG. First, in #402, it is determined whether the current focus detection was low contrast. If the contrast is not low, a correction time T is determined in #403.

The time of the current CCD integration center is saved in the memory TM, and by subtracting the value in the memory TM from the current timer value TC and adding the mirror up time of 7Qmsec, the time from the current integration center to the next exposure can be calculated. Time is needed. In the case of low contrast, the process proceeds to #404 to find the time T from the previous exposure time to the next exposure time.

As explained in Figure 8, the previous exposure time is stored in the memory T.
It is saved in IME1. Therefore, subtract the value of memory T I ME 1 from the current timer value TC and get 7.
All you have to do is add 0 m5ec. That is, #402~
In #404, when the contrast is not low, the calculation is performed based on the current defocus DFO, and when the contrast is low, the calculation is performed assuming that the defocus was 0 during the previous exposure.

Next, in #405, the defocus speed VHO is set to the above #
Multiply by the time T obtained in step 403 or #404 to obtain the correction amount ΔD
I'm looking for F. Next, in #406, the defocus speed VHO and the constant VVH are compared. If VHO>VVH and the defocus speed is fast, it is determined in #407 whether the subject is approaching or going away, and if the subject is approaching, the correction amount ΔDF is multiplied by 1.25 (#408).

As mentioned above, if the subject approaches in the optical axis direction at a constant speed, the defocusing speed will increase in inverse proportion to the square of the subject distance.
The defocusing speed also increases during the time T determined in step 3 or #404. In order to correct this error, the correction amount ΔDF is multiplied by 1.25. When the subject is far away, the defocus speed becomes slower, so the correction amount Δ
Multiply DF by 0.75 (#409). Next, #410
This time detected defocus DFO and defocus speed VH
Check the direction of O, and if the direction is the same, the corrected defocus MDF will be DFO + ΔDF (#411)
. If the direction is different, the currently detected defocus DFO is compared with the correction amount ΔDF in #412, and DFO≦ΔDF is determined.
If so, set ΔDF-DFO in the corrected defocus MDF (#413). If DFO>ΔDF, the photographic lens must be driven in the direction opposite to the defocus speed direction, which means that a large defocus is detected in the direction opposite to the defocus speed direction. Therefore, assuming a backlash error due to the reversal of the photographic lens or abnormal movement of the subject, the stack is initialized in #414, and the next release is prohibited by proceeding to the release process ○UTRV21 in #415. , performs refocus detection. Once the corrected defocus MDF is determined in #411 and #413, it is multiplied by the coefficient KL for converting the defocus into the number of pulses in #4.1.6 to determine the number of drive pulses E R, R
Seraize CNT from 1 to 1 and return (#41.7).

This allows highly accurate correction even when the subject is moving at high speed, and can handle both approaching and receding subjects. Furthermore, as is clear from the explanation of FIG.
Even when low contrast 1 to last are ignored once in #308 to #312, the correction for the movement of the subject is performed correctly.

Finally, timer interrupts and ARP interrupts will be explained.

FIG. 13 shows a timer interrupt processing routine for driving the AF motor M2. The CPU 201 has a built-in interrupt timer (not shown) that generates a timer interrupt when a set time has elapsed. When a timer interrupt occurs, #5
At step 02, the interrupt timer IT is reset. As a result, the interrupt timer IT automatically generates a timer interrupt when the set time has elapsed after the current timer interrupt occurs.

Subsequently, the flag RMGONF is determined in #503, and if it is set, the release magnet RMg is being energized, so the AF MOMO-M is turned OFF as described above (#505). If the flag RMGONF is reset to 1 or higher, the AF motor M2 is energized in #504 and the process returns (#506).

FIG. 14 shows an AFP interrupt processing routine that occurs at the falling edge of the AFP signal. When an AFP interrupt occurs, the number of drive pulses ERRCNT is decreased by one in #602. In #603, the number of drive pulses ERRCNT becomes O, and it is determined whether the drive of the AF motor M2 has ended. If the number of driving pulses E RRCN T is not O and the driving of the AF motor M2 is not completed, the process advances to #604 and the interrupt timer IT is reset. In #605, the flag RMGONF is checked. Flag RM G
If ONF is set and the release magnet RMtr is energized, the AF motor M2 is turned off in #608. If the flag RMGONF has been reset, the brake is applied to the AF motor M2 in #606, and the process returns (#607). On the other hand, if the driving of the AF motor M2 has been completed in the determination of #603, then #6
The process branches to step #609, and the AF motor M2 is de-energized in step #609. Next, in #610 and #611, timer interrupts and AFP interrupts are inhibited, respectively, and the process returns (#6
07). As described above, the AF motor M2 is driven by the timer interrupt and the AFP interrupt, and is controlled to be OFF while the release magnet RM8 is energized.

[Effects of the Invention] In the automatic focusing camera of the present invention, even when the reliability of focus detection is low, the amount of change in the amount of defocus is determined from the speed of change in the amount of defocus due to the movement of the subject, and this change is detected. Since the focus adjustment lens is driven based on the amount, the lens can be driven to at least follow the movement of the subject, and there is an effect that the focus can be prevented from being largely deviated from the subject.

Note that when the present invention is applied to a reflex camera having a quick-shooting mode, if the lens is driven based on the amount of change while the mirror is up, tracking control can be performed only when release is necessary. This makes it possible to omit lens driving based on uncertain information when there is no need to release the lens.

In addition, if the state in which focus detection is determined to be unreliable occurs a predetermined number of times in a row, the tracking control is canceled. It can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of the present invention, Fig. 2 is a side view of a camera as an embodiment of the invention, Fig. 3 is a front view of the same, and Fig. 4 is a block circuit of the same. 5 and 6 are operational waveform diagrams, and FIGS. 7 to 14 are flowcharts showing the same operation. (1) is focus detection means, (2) is change rate detection means, (
3) is a variation output means, (4) is a reliability judgment means, and (5
) is a lens driving means, (6) is a follow-up control means, and (7) is a follow-up canceling means.

Claims (3)

[Claims] (1) Focus detection means for detecting the amount of defocus of the photographing lens with respect to the subject to be focused on, change rate detection means for detecting the rate of change in the amount of defocus due to movement of the subject, and based on the output of the change rate detection means change amount output means for outputting the amount of change in defocus amount due to movement of the subject;
a reliability determining means for determining the reliability of focus detection; a lens driving means for driving a lens for focus adjustment; and a change amount output means when the reliability determining means determines that the reliability of focus detection is low. An automatic focusing camera comprising: tracking control means for controlling a lens driving means based on the output. (2) The camera is a reflex camera having a continuous shooting mode in which the release operation continues continuously during the release operation, and the tracking control means is means for controlling the lens driving means based on the amount of change while the mirror is up. An autofocus camera according to claim 1, characterized in that: (3) Claim 1 further comprising tracking canceling means for prohibiting the operation of the tracking control means when a state in which the reliability of focus detection is determined to be low by the reliability determining means continues for a predetermined number of times. Autofocus camera as described.