JPH01287513A - Interchangeable lens type automatic focus adjusting device and its interchangeable lens - Google Patents

Abstract

PURPOSE:To increase the probability that a focusing state is entered without reference to whether a focus shifts to a front or rear focus side at the start of focus detection by setting the initial position of the lens to a nearly intermediate position in a movable range when a special lens is mounted. CONSTITUTION:When the interchangeable lens 1 is mounted, a data output means 14 outputs 1st data LCPR indicating that the rough focus adjustment lens of the interchangeable lens 1 is wider than its fine focus adjustment range, so a lens position determining means 13 determines the initial position Ns of the focus adjusting member 13 at the nearly intermediate position Nmax/2) of the movable range NL=0 to Nmax of the focus adjusting member 13. Then a lens driving means 22 is so controlled under the control of a control means so as to drive the focus adjusting member 13 to the initial position Ns determined by the initial position determining means 23 before a focus adjusting means 21 performs focus detecting operation. Consequently, the probability that focusing is successful is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an interchangeable lens automatic focusing device and its interchangeable lenses, and is used, for example, in a single-lens reflex camera with an automatic focusing function. It is.

[Prior art 1] Conventionally, in an automatic focus adjustment device that detects the focus state of a lens for photographing and drives the lens to the in-focus position, the time required to drive the lens to the in-focus position after focus detection is fixed. It has been proposed to initially set the lens to an intermediate position each time a photograph is taken (U.S. Pat. No. 4,265)
, No. 528).

However, in this prior art, the initial position is not changed depending on the type of lens to be attached.

[Problems to be Solved by the Invention] When attempting to expand the group of interchangeable lenses in a single-lens reflex camera with an automatic focus adjustment function, a demand arises to add a lens for macro photography of life size or larger. However, with this type of lens, depending on the initial position of the focusing member, it may not be possible to focus when changing the magnification.

The present invention has been made in view of these points, and its purpose is to provide an interchangeable lens type automatic focusing device and a device that increases the probability of focusing even when a special interchangeable lens is attached. Our goal is to provide interchangeable lenses.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
As shown in the figure, a manually operable focus coarse adjustment member (1
1) and a fine focus adjustment member (13) that can be electrically operated from the outside via a power transmission mechanism (12), and the first one has a coarse focus adjustment range that is wider than a fine focus adjustment range.
An interchangeable lens (1) is used which is provided with data output means (14) for outputting data LCPR and second data REVmax indicating the fine focus adjustment range. In addition, the lens-interchangeable automatic focusing device (2) used in combination with the interchangeable lens (1) includes a focus detection means (21) for detecting the focus state of the interchangeable lens (1), and a focus detection means (21) based on the focus detection result of the interchangeable lens (1
) lens driving means for driving the focusing member (13) of <
22) and data output means (14) for the interchangeable lens (1)
When reading the first data LCPR from
Based on the data RE V wax of the focusing member (
13) is set to a substantially intermediate position (N wax/
2), and when the first data LCPR is not read, the initial position of the focusing member (13) is determined based on the third data regarding the focal length r.
r), and a focus adjustment member (13) at the initial position Ns determined by the initial position determination means (23) before the focus detection means (21) performs the focus detection operation. and control means (24) for controlling the lens drive means (22) to drive the lens drive means (22).

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

In the interchangeable lens (1) shown in FIG. 1, coarse focus adjustment is performed in advance with a coarse focus adjustment member (11). Then, when the focus detection means (21) is operated, the focus state of the lens (1) is detected. The focus state of the lens (1) is usually detected as the amount of defocus (defocus amount) from the in-focus position, and the front bin and the back bin are distinguished by the sign thereof. Based on the focus detection result of the focus detection means (21), the lens drive means (22) drives the power transmission mechanism (12) so that the amount of defocus from the in-focus position becomes zero.
A fine focus adjustment member (13) is driven via the. 1st
When the interchangeable lens (1) shown in the figure is attached,
Since the first data LCPR indicating that the coarse focus adjustment range of the interchangeable lens (1) is wider than the fine focus adjustment range is output from the data output means (14), the lens position determination means (3) Based on the second data REVsax indicating the focus fine adjustment range, the initial position Ns of the focus adjustment member (13) is set to the movable range NL of the focus adjustment member (13) = 0.
˜NIIa× (N...ax/2) is determined. Under the control of the control means (24), before the focus detection means (21) performs the focus detection operation, the focus adjustment member (
The lens driving means (22) is controlled to drive the lens driving means (22). Therefore, in the present invention, as long as the coarse focus adjustment member (11) is in focus, even if there is a focus adjustment error on either the front bin side or the rear focus side, the focus adjustment error is within half of the movable range Ns+ax of the focus fine adjustment member (13), the focus detection means (21)
By operating the focus fine adjustment member (13), a more accurate focusing state can be achieved.

Note that when the first data LCPR is not read, it means that a normal interchangeable lens is attached, and with a normal interchangeable lens, the focal length is adjusted according to the focal length f, rather than being initially set to the middle position of the movable range. Since the probability that the focus can be detected is higher if the initial setting is made to a position where a predetermined imaging magnification β can be obtained, the initial position N5=Nb of the focus adjustment member (13) is set based on the third data regarding the focal length f. (f
) to determine. This makes it possible to increase the probability that focus can be detected regardless of the type of interchangeable lens.

[Embodiment] FIG. 2 is a block circuit diagram showing the circuit configuration of a camera as an embodiment of the present invention. However, illustrations of parts not directly related to the focus detection operation are omitted. (
μC) is a microcomputer that performs calculations and sequence control for focus adjustment. (LEC) is a lens circuit provided in the interchangeable lens, which transmits information specific to the interchangeable lens to the microcomputer (μC). (A.F.C.
) is a focus detection circuit that photoelectrically converts the subject light that has passed through the lens and outputs focus detection data.
μC). (DSP) is a display circuit that displays the focus of the lens and indicates that focus cannot be detected. (ILM) is an auxiliary light emitting device that irradiates the subject with auxiliary light for focus detection. (M) is a motor for driving the focusing lens of the interchangeable lens, and the lens drive circuit (L
The lens drive circuit (LDC), which extends and retracts the lens under the control of the DC), receives a motor drive speed signal, a motor drive direction signal, and a motor stop control signal from a microcomputer (μC). Enter
Based on this, the motor (M) is driven. (ENC)
is an encoder that detects the amount of rotation of the motor (M) and outputs pulses to the microcomputer (μC) according to a predetermined amount of rotation of the motor (M).

Here, the microcomputer (μC) uses a lens position counter N to know the amount of lens extension from the infinity position, which is the most retracted state, as an absolute amount.
, is built-in. This lens position counter N is reset to NL=0 by an internal command when the lens is retracted to the infinite position, and when the lens is extended, the encoder (ENC) is reset by an internal command.
When the lens is retracted, it is counted down according to pulses from the encoder (ENC) according to an internal command. When the lens is extended to the closest position, the value of the lens position counter N becomes N1-=Naax. This maximum extension amount N max differs depending on the lens, and is read from the lens circuit (LEC) into the microcomputer (μC) as lens-specific information.

In addition, the lens circuit (L E C) has a rotation speed of the rotation axis (rotation axis on the lens side that is combined with the rotation axis on the camera body side) for driving the focusing lens in the lens. Information REVmax is stored in memory.

In the camera body, the reduction ratio of the reduction mechanism (not shown) placed between the motor (M) and the rotating shaft on the camera body side, and the encoder per rotation of the motor (M) <E S
From the number of pulses from C), the maximum edge amount N +
I'm looking for sax. For example, in PA, the reduction ratio is 1/20, the number of encoder (ENC) pulses is 20 per revolution,
If RE V wax is 3 rotations, N wax = 20
x20x3=1200.

(BAT) is a power supply battery, and a microcomputer (
μC) and other circuits. Power battery (BA
A time constant circuit consisting of a series circuit of a resistor (R1) and a capacitor (C1) is connected to both ends of the resistor (T).
The connection point between R1) and the capacitor (C1) is connected to the power-on reset terminal (RES) of the microcomputer (μC). When the power supply battery (BAT) is connected, a power supply voltage is applied between the power terminal (Vce) and the ground terminal (GND) of the microcomputer (μC), and the microcomputer (μC) becomes active, but the capacitor ( The microcomputer (μC) does not operate until the charging voltage of C1), that is, the voltage applied to the reset terminal (RES) of the microcomputer reaches a predetermined voltage. When the voltage of the capacitor (C1) exceeds the predetermined voltage, The microcomputer (μC) is reset,
The operation starts from step #5 (see FIG. 3), which will be described later.

(SR) is a reset switch, and this switch is OFF.
When N is pressed, the lens is reset to the initial position. (S
ω) is an infinity position detection switch, which is turned on when the lens is retracted to the infinity position. (SN) is a main switch, which is turned on when using the camera. (S
l) is the shooting preparation switch, and normally the release button (
- (SAF
) is the AF mode switch, and this switch (SAF
) is ON, the autofocus mode that drives the lens to the goldfish position is selected based on the focus detection result, and when the switch (S AF) is OFF', the autofocus mode is selected based on the focus detection result. A manual focus mode is selected in which only the focus is displayed and the lens is not driven. (8M2) is a macro zone switch, which is opened when the zoom ring is set to the macro zone in a zoom lens with a macro mechanism. When the macro zone is set, autofocus mode is disabled, so in order to notify the microcomputer (μC) of this,
The lens circuit (LEC) outputs a signal SMZ indicating the macro zone to the microcomputer (μC).

Next, the focus adjustment operation of the camera will be explained with reference to a flowchart. When the power-on reset is performed, the microcomputer (μC) executes the programs starting from #5 shown in FIG. First, reset all flags in #5. Next, turn on the main switch (SN) in #10.
Determine whether.

If the main switch (SN) is not ON, repeat the determination in #10 until the main switch (SM) is turned ON.
) is ON, the lens initial position calculation subroutine (Fig. 9) is executed in #15, the ■ renormalization subroutine (Fig. 10) is executed in #2°, and the lens initial position setting is performed in #25. After executing the subroutine (Figure 11),
At #30, it is determined whether the main switch (SM) is OFF. If the main switch (SN) is OFF, the subroutine ① renormalization is executed in #35, and the process returns to #10. #
If the main switch (SM) is not OFF at 30, #
Proceed to step 45.

FIG. 9 is a flowchart showing the contents of a subroutine for calculating the lens initial position. When this subroutine is called, first, lens data is input from the lens circuit (LEC) for $1000.

From the lens circuit (LEC), the lens attachment signal IC
P, macro zone signal SMZ, macro lens attachment signal LCPR5, maximum rotation speed of focusing wheel REV
wax, focal length f, conversion coefficients, etc. are input to a microcomputer (μC). Here, the conversion coefficient is a coefficient for converting the defocus amount DF into the lens drive amount ΔN.

Table 1 shows the address of the data ROM in the lens circuit (LEC), the bits within that address, and the information assigned to each bit.As shown in the table, addresses OOH to 03H include: 8-bit data b each
0 to b are stored. A lens attachment signal CP is stored at address 00H. This signal is for example “
10101010" data.Address OIH
The macro zone signal SMZ is assigned to the least significant bit b0, and if b,=1, the macro zone, b
If 0=0, it means a non-macro zone.

The remaining 7 bits b1 to b of the address OIH store logarithmically compressed data on the focal length.The least significant bit b0 of the address 02H is assigned a macro lens signal LCPR of equal or larger magnification. If ,b,=1, it is a macro lens with a magnification larger than the same size, and b,=.

If so, it means that it is not a macro lens that is larger than the same magnification.

The remaining 7 bits b1 to b of address 02H store the rotation speed REVmay of the rotation axis of the lens. Conversion coefficient K is stored at address 03H.

In #1004, the maximum rotation speed REVma of the lens rotation axis
The maximum feeding amount N + *ax is determined from x as described above. In #1005, it is determined whether there is a macro lens attachment signal LCPR of equal or larger magnification. If in #1005 a macro lens of equal or larger magnification is attached, in #1006 the maximum lens defocus amount DFea=Nmax/K is determined from the maximum lens extension amount Nwax. Here, the maximum defocus amount DF- is a defocus amount that covers the range from the closest position to the infinity position of the lens. #
In step 1007, the defocus amount DFs for setting the lens initial position is set to DF wheel/2, and the process returns to the step in which the subframe was called. Note that the maximum defocus amount DFn for a macro lens of equal or larger magnification may be stored in a memory within the camera body.

#1005 does not have a macro lens of 1x or higher (
Then, in #1008, defocus JiDFb is determined. This defocus amount DFb is the defocus amount from an infinity position to the lens position fNb determined according to the focal length f. Information on the lens position Nb, which has been set in advance with consideration, is read from the ROM table.

Table 2 shows commonly used photographic magnification β and lens position N determined accordingly for lenses with various focal lengths.
The defocus amount DFb corresponding to b and the maximum defocus amount DF11 of the lens are shown. DFa is the defocus amount that allows focus detection, which is determined by the configuration of the focus detection circuit N (AFC), and the focus detection range is 2x 2D
Becomes Fa.

In #1010, it is determined whether DFb>DFa.

If DFb>DFa in #1010, the defocus amount DFs for one set of initial lens values is set to DFa in #1030.
Then, in #1060, the lens position set flag 5ETF is set to 1, and the process returns to the step where the subroutine was called. If DFb≦DFa in #1010, #10
20 is the defocus amount DFs for setting the lens initial position.
is DFb, and #1050 is the lens position set flag 5.
Set ETF to 1 and return to the step where the subroutine was called.

In the above table of Table 1, when SMZ=1, it is a macro zone.
=O means it is not a macro zone, LCPR=1
When , it indicates that the macro lens is equal to or larger than the same magnification, and when LCPR=O, it indicates that it is not a macro lens that is equal to or greater than the same magnification.

Table 2 However, in the above table, * is when the zoom lens with a diameter of 28 to 135 aue is at 135-, and t is when the zoom lens with a diameter of 70 to 210 aue is at 210
This is data when the customer is at 300m5 with a zoom lens of 75-300m+*.

FIG. 12 is a diagram for explaining the meaning of steps #1010 to #1030. Figure (a) shows a case where the defocus amount DFb from the lens position Nb to the infinity position determined according to the imaging magnification β is larger than the defocus amount DFa that allows focus detection. is set as DFs=DFa. Therefore, at the lens initial position N5=DFsXK, the infinity position is included within the focus detectable range 2DFa, and if the focus cannot be detected, it is only necessary to scan in the direction in which the lens is extended. indicates the case where the defocus amount DFb from the lens position Nb to the infinity position determined according to the imaging magnification β is less than the defocus amount DFa that allows focus detection; in this case, DFs=DFb It is said that In this case as well, lens initial position N5=DFs
For XK, the focus detection range is 2DF at infinity.
If the focus cannot be detected, it is only necessary to scan in the direction in which the lens is extended.

FIG. 13 is a diagram for explaining the meaning of steps #1004 to #1007. The figure shows an area larger than the same size (
The positional relationship between the subject, lens, and film surface for focusing at 1.5x to 3x) is indicated by the solid line 0. L, F
It is shown in In other words, when the magnification is 3x, the subject position is point 01, the lens position is point L1, and the film surface is at point F+. In-focus occurs when point L2 and the film surface are at point F2. When the magnification is 1.5x to 3x, the subject position, lens position, and film plane are respectively 0. The object is in focus when it is on the trajectory indicated by L and F.

FIG. 14 is a sectional view of an enlarged close-up photographing device that can easily change the magnification while maintaining the above relationship. When you hold the variable power adjustment knob 150 and rotate the variable power cam ring 160 around the optical axis C,
The lens moving frame 170 and the camera moving frame 180 each move along the optical axis C. The cam shape of the variable magnification cam ring 160 is designed so that these movement amounts maintain the relationship between the lens position and the film surface shown by solid lines and F in FIG. 13. Therefore, if the subject is located at the position indicated by the solid line 0 in FIG. 13, it is possible to change the magnification while maintaining the in-focus state just by the above operation. When the coarse focus adjustment knob 110 is rotated, the entire lens 100 and camera are moved up and down with respect to the stage 190 by the rack 111 and pinion 112, so that the subject comes to the position indicated by aO in FIG. Can be adjusted. By rotating the focusing cam ring 130, the lens 100 can be moved up and down by a certain amount with respect to a reference position within the lens movement frame 170. Here, the reference position means a position on the solid line in FIG. The focus adjustment cam ring 130 is an interlocking gear 121.12.
It is interlocked with the rotation shaft 120 via 2. This rotation axis 1
20 is fitted to a rotating shaft for driving a lens in a camera body whose mount portion is attached to a bayonet 181;
Rotationally driven by a motor inside the camera body. If focus adjustment by the coarse focus adjustment knob 110 is not complete, a known automatic focus adjustment mechanism built into the camera body is used to adjust the focus adjustment cam ring via the rotation shaft 120 and interlocking gears 121 and 122. Rotate lens 130 and
By driving only the lens in the optical axis direction, accurate focusing can be achieved.

In FIG. 13, as a result of the coarse focus adjustment using the coarse focus adjustment knob 110, when the subject is not at the position indicated by the solid line 0 but at the position indicated by the broken line 0' (or 0''), it is aligned with the film plane F. The position of the lens 100 for focusing is indicated by the broken line L' (
or L″).

When automatic focusing is performed with the imaging magnification set to 3x, the lens comes to the position indicated by point A' (or A'') and focuses.

Thereafter, when the magnification adjustment knob 150 is rotated to change the magnification, the lens 100 is moved by the magnification cam ring 160 along a trajectory indicated by a dashed line starting from point A' (or A''). , strictly speaking, on the dashed line.

Although it is impossible to maintain focus because the lens is out of focus position indicated by (or L"), the subject position indicated by the broken line 0° (or O") and the subject indicated by the solid line 0. Since the difference from the position is not very large, the amount of defocus will not be large, and focusing can be easily achieved by performing automatic focus adjustment after changing the magnification.

Conversely, when operating the coarse focus adjustment knob 110, the lens 100 is not at the reference position shown by the solid line, but at point A' (
or A''), even if you can focus accurately by operating the coarse focus adjustment knob 110, it means that the subject position is set to the position indicated by the broken line 0° (or O''). Therefore, the focus shifts after the magnification change operation is the same as in the above case.

Also, when the lens 100 is at point B' (or B'') near the limit of the range in which it can move up and down from the reference position indicated by the solid line (between the solid lines L AF' and LAF'), When focusing is achieved by operating the coarse focus adjustment knob 110, the reference position of the lens 100 for focusing is shown on the low magnification side by a broken line trajectory starting from point B' (or B''). The displacement from (trajectory shown as a solid line) increases,
Solid lines L AF' and LAF indicate the movable range of the lens 100
” (As a result, after changing the magnification to the lower magnification side, the movable range of the lens 100 for focusing will be exceeded. Therefore, you will have to repeat the coarse movement operation again. It won't happen.

As is clear from the above, the coarse focus adjustment knob 1
10, it is necessary to set the lens 100 at the reference position in advance. Further, during automatic focus adjustment, it is necessary to have a movable range up and down by a certain amount from the reference position. Therefore, in this embodiment, when a macro lens of equal or greater magnification is attached, the defocus amount DFs at the initial position of the lens is set to half the maximum defocus amount DFm.

FIG. 10 is a flowchart showing the contents of the subroutine of (1) renormalization. When this routine is called, lens retraction is started in #1100, and it is determined in #1105 whether the infinity position detection switch (Sω) is ON. If the switch (Soo) is not turned on in #1105, the determination operation in #1105 is repeated until the switch (Soo) is turned on. If the lens is retracted to the infinity position in #1105 and the switch (Soo) is turned on,
Lens retraction is stopped in #1110, lens position counter NL is reset in #1115, and the subroutine returns to the called step.

FIG. 11 is a flowchart showing the contents of the subroutine for setting the lens initial position. When this subroutine is called, in #1200, the defocus amount DFs for setting the lens initial position is multiplied by the conversion coefficient K to calculate the lens drive amount ΔN=DFsXK from the infinity position, and #1
At step 205, lens extension is started. In #1210,
It is determined whether the lens drive amount has reached ΔN. #1210
If the lens drive amount has not reached ΔN in #1210, repeat the determination operation in #1210 until the lens drive amount reaches ΔN.If the lens drive amount reaches ΔN in #1210, #12
At step 15, lens driving is stopped and the subroutine returns to the called step.

Returning to the flow of FIG. 3, in #45, it is determined whether the AF mode switch (SAF) is ON.

If the AF mode switch (SAF) is not ON in #45, set the flag MP indicating manual focus mode to 1 in #50, and proceed to #80.
If the F mode switch (SAF) is ON, it is determined in #55 whether the flag MF is 1. MF=1 in #55
If so, it means that the switch (SAF) has just been turned on, and in #60, set the flag MF to 0 and proceed to #65. In #65 to #75, the above-mentioned lens initial position calculation,
■Execute each subroutine of renormalization and lens initial position setting to set the lens initial position, and then #1
Proceed to #45. If MF = 1 in #55, it means that the switch (S AF) has been ON before.
Proceed to #80.

In #80, the presence or absence of the lens attachment signal ICP is determined.

If the lens is not attached at #80, the flag LENOF indicating that the lens is not attached is set to 1 at #100, and the process proceeds to #105.If the photographic lens is attached at #80, the flag is set at #90. Determine whether LENOF is 1. If LENOF=1 in #90, it means that the lens has just been attached, and the flag LENOF is set in #95.
After setting F to 0 and setting the lens initial position in #65 to #75, proceed to #145. If LENOF is not 1 in #90, it means that the lens has been attached before, and #105 Proceed to.

At #105, the macro zone switch (SMZ) is turned on.
In other words, it is determined whether the zoom lens is in the macro zone. #105 is the macro zone switch (S
M2) is not ON, that is, if it is in the macro zone, the macro zone switch (SMz) is turned OFF in #110.
The flag SMZOFF indicating that is 1 is set, and #12
Proceed to 5, macro zone switch (SMZ) at #105
If it is ON, it is determined in #115 whether the flag SMZOFF is 1. If SMZOFF=1 in #115, it means that the macro zone switch (SM2) has just been turned on, and after setting the flag SMZOFF to O in #120 and setting the lens initial position in #65 to #75. , proceed to #145. If SMZOFF=1 is not found in #115, it means that the macro zone switch (SMZ) has been turned on before, and proceed to #125.

In #125, it is determined whether the reset switch (SR) is ON. If the reset switch (SR) is not ON in #125, the reset switch (SR) is turned on in #130.
The flag 5ROFF indicating that is OFF is set to 1,
Proceed to #145, reset switch (SR) at #125
If it is ON, it is determined in #135 whether the flag 5ROFF is 1.

If 5ROFF=1 in #135, it means that the reset switch (SR) has just been turned on, and #140
After setting the flag S and ROFF to 0 and setting the lens initial position in #65 to #75, proceed to #145, #13
If 5ROFF is not 1 in 5, it means that the reset switch (SR) has been turned on before, and the lens has already been set to the initial position, so #65 to #
The process proceeds to #145 without performing the lens initial position setting in step 75.

Therefore, after setting the lens initial position (#15 to #25) immediately after turning on the main switch (SN),
Immediately after the F mode switch (S AF) is turned on, immediately after the lens is attached, or the macro zone switch (SM
Immediately after the reset switch (Z) is turned on, or the reset switch (S
(#1
55), lens initial position set (#65 to #
75) is performed, and in other cases, the initial lens position is not set. Therefore, when shooting similar scenes or when shooting multiple photos in succession, the previous lens position is If there is a high probability of focusing in the vicinity, the lens initial position is not set, which reduces power consumption compared to a case where the lens initial position is set every time the focus is detected. time is shortened.

In #145, it is determined whether the photographing preparation switch (Sl) is ON. If the photographing preparation switch (Sl) is not turned on, the entire display is turned off in #40 and the process returns to #30. Below, #30, #45, #80, #105, #125
, #145, main switch (SM), AF mode switch (SAF), lens attachment signal ICP, macro zone switch (SMZ), reset switch (SR), and shooting preparation switch (Sl). Monitor status.

In the middle of this loop, the main switch (SM) is turned off.
When it is, as mentioned above, ■ Renormalization (#35)
and wait until the main switch (SM) is turned on again (#10 >, and in the middle of the loop, if any of the switches (SAF), (SMZ), or (SR) is turned on, Alternatively, each time the lens is attached, set the lens initial position (#65 to #75). In this way, the camera will switch to the shooting preparation switch (Sl).
When the photographing preparation switch (Sl) is turned on in #145, the process advances to #155 (FIG. 4) to start focus detection.

In #155, it is determined whether a low contrast scan end flag LSENDF, which will be described later, is 1.

Initially, since LSENDF=O, focus detection is performed in #175, and it is determined in #180 whether focus detection is impossible. If the focus cannot be detected in #180, the process proceeds to #285 (FIG. 7) to perform focus determination. If the focus cannot be detected in #180, it is determined in #185 whether the brightness is low. If the brightness is low in #185, #
Proceed to 330 (Fig. 8). If the brightness is not low in #185, in #190 and #191 (Fig. 5), (N a + ax - N L)/K > D Fa or N L/ K > Determine whether D F a −■ is satisfied. If condition (2) is not satisfied in #190 and #191, the entire focus range of the lens is included in the focus detectable range 2DFa. However, the fact that focus cannot be detected means that there is no way that focus can be detected even if a low contrast scan (operation of detecting focus without driving the lens and searching for a position where focus can be detected) is performed. It is wasteful to perform a low contrast scan. Therefore, without performing the low contrast scan, the process proceeds to #255 (see FIG. 7), and a focus detection failure display is performed.

If condition ■ is satisfied in #190 or #191, #
At 192, it is determined whether Nwax/2K≦DFa−■ is satisfied. Here, N wax/2
is the amount of defocus (ie, DF ratio/2) from the intermediate position to the final position of the photographic lens, and is determined according to the attached lens. Further, as described above, 2DFa is a defocus amount that allows focus detection, determined by the configuration of the focus detection circuit (AFC), and is a constant on the camera body side. If condition ■ is satisfied in #192, if the lens is in the intermediate position, the entire focus range of the lens N
Since 5ax/K is included in the focus detectable range 2DFa, there is no need to take the trouble of performing a low contrast scan.Therefore, in order to move the lens to the intermediate position Nmax/2, #
At 193, lens drive amount ΔN = Nmax/2-NL
is calculated, and lens driving is started in #1941. #
In 1942, it is determined whether the lens drive amount has reached ΔN. If the lens driving amount has not reached ΔN in #1942, the determination operation in #1942 is repeated until the lens driving amount reaches ΔN.

If the lens drive amount reaches ΔN in #1942, #194
After the lens drive is stopped in Step 3 and focus detection is performed in Step #195, it is determined in Step #196 whether focus detection is impossible. #1
If the focus cannot be detected in 96, the focus cannot be detected even if the low-contrast scan is performed, and it is wasteful to perform the low-contrast scan. Therefore, without performing a low contrast scan, proceed to #255 (Fig. 7) to display a focus detection failure display.If the focus is not detectable, proceed to #285 (Fig. 7) to perform a focus judgment. move on.

If condition (■) is not satisfied in #192, the entire focus range of the lens is Nmax/no matter where you change the lens position.
K cannot be covered within the focus detectable range 2DFa. Therefore, in this case, low contrast scanning is unavoidably performed, but the range of low contrast scanning should be limited to the narrowest possible range. We have devised ways to reduce the time required for low-contrast scanning. That is, in #198 (FIG. 6), the scanning amount in the feeding direction is calculated as ΔN=Nmax-NL-DPIIXK.

This is because even if you do not extend it to the maximum extension position WNmax, if you extend it to the front position by DFaXK, the maximum extension position Nwax will also be within the focus detectable range 2DFa. ,
In #200, it is determined whether the flag FOWF is 1. This flag FOWF is a flag indicating that scanning is to be performed in the direction (FOWard). When performing a low contrast scan for the first time, the flag FOWF is reset, so FOWF is not 1. Therefore,
First, proceed to #205, set FOWF=1 in #205, and proceed to #220. In #220, a signal is output to the lens drive circuit (LDC) to drive the lens (in the direction of extension), and in #225, focus detection is performed. After this, it is determined in #230 whether focus detection is impossible. If the focus cannot be detected in #230, the flag FOWF is reset in #233, and the process proceeds to #285 (Fig. 7) to perform focus determination.
If the focus cannot be detected in #230, it is determined in #235 whether the lens drive amount has reached ΔN. If the lens driving amount has not reached ΔN at 8235, the process returns to #225, and it is determined whether the focus cannot be detected without continuing the lens driving in the extending direction. If the lens drive amount has reached ΔN in #235, the lens drive is stopped in #24o, and the lens drive is stopped in #245.
It is determined whether the lens position set flag 5ETF is 1 or not. If 5ETF=1 in #245, it can be determined that the focus cannot be detected over the entire focus range of the lens without scanning in the renormalization direction. ), and if 5ETF is not 1 in #245, it is determined in #250 whether the flag FOWF is 1.

If FOWF=1 in #250, this means that the lens position where focus detection was possible was not found even though scanning was performed in the extending direction, so return to #200 to scan in the retracting direction. . If FOWF=1 in #200, it means that the scan in the feed-out direction has already been completed, so in #210, the scan amount in the renormalization direction is ΔN −D F a X K −N
Calculate as L. This is because the infinity position will also fall within the focus detectable range 2DFa, even if the focus is not retracted to the infinity position, if the focus is retracted to a position in front of DFax.

In #215, the flag FOWF is set to 0 to indicate that the scan is in the renormalization direction, and the process proceeds to #220.
220 outputs a signal to the lens drive circuit (LDC) to drive the lens (in the retraction direction), and #225 to
After #245, the process returns to #250. This time, FOW
Since F=1, it does not return to #200 and #2
Proceed to 55 (Figure 7), that is, at #250, FOWF=
If it is not 1, it means that both the scanning in the extending direction and the scanning in the retracting direction were performed, but the lens position where the focus could be detected could not be found, so #25
5 indicates that focus cannot be detected.

If focus detection becomes possible at #23o during scanning in the retraction direction, the flag FOWF is reset at #233, and the process proceeds to #285 (FIG. 7) to perform focus determination.

When displaying focus detection failure in #255 (Fig. 7), #2
At 60, set the low contrast scan end flag LSENDF to 1
shall be. This flag is a flag to indicate that the lens position 1 where the focus can be detected was not found even though the low contrast scan was performed. Note that if the focus cannot be detected even though the entire focus range of the lens is included in the focus detection range 2DFa (specifically, #191 or #19
6 to #255), the flag LSE is set in #260 even if low contrast scan is not actually performed.
Let NDF be 1. This is because it is impossible to find a lens position where the focus can be detected even if a low contrast scan is performed.
After returning OWF to 0, press #270 to turn the shooting preparation switch (
SL) is ON. If the photographing preparation switch (Sl) is not ON in #270, the entire display is erased in #40 and the process returns to #30. Press #270 to turn on the shooting preparation switch (
Sl) is ON, focus detection is performed in #275, and #
In step 280, it is determined whether focus detection is impossible. If the focus cannot be detected in #280, the process returns to #270.

If it is not possible to detect the focus in #280, set the lens position set flag 5ETF to O in #285, set the low contrast scan end flag LSENDF to O in #290, and set the lens position set flag 5ETF to O in #290.
5 to determine whether the image is in focus.

If it is determined that the focus is not in focus in #295, the process proceeds to #300, where the in-focus and focus detection failure display is erased, and the lens drive amount ΔN=DFX is determined based on the defocus IDF in #305.
K is calculated and lens driving is started in #310. #31
In step 1, it is determined whether the lens drive amount has reached ΔN. #
If the lens driving amount has not reached ΔN in step 311, the determination operation in #311 is repeated until the lens driving amount reaches ΔN. If the lens driving amount reaches ΔN in #311, #3
At step 12, the lens drive is stopped and the process returns to #270.

If the shooting preparation switch (Sl) remains ON in #270, focus detection is performed in #275, and then in #280 to #290
After that, the focus judgment is performed again in #295, and the above-mentioned #30
Since the lens is driven toward the in-focus position in steps #5 and #310, there is a high possibility that the focus will be achieved here. If the focus is determined in #295, the focus is displayed in #315, and it is determined in #320 whether the photographing preparation switch (Sl) is ON. At #320, the shooting preparation switch (Sl) is set to O.
If N, the determination operation of #320 is repeated until the photographing preparation switch (Sl) is no longer ON, resulting in a so-called focus lock state. Although unrelated to the present invention, in a camera in focus priority mode, when release is permitted in this focus locked state and the release forceps (not shown) are pushed to the second stroke,
A camera performs a release operation. If the photographing preparation switch (Sl) is no longer ON in #320, the display is turned off in #40 and the process returns to #30. That is, by turning off the photographing preparation switch (Sl), the above-mentioned focus lock state is released.

After the shooting preparation switch (Sl) is turned off, it is turned on again.
If so, it may be determined as LSENDF-1 in #155. This was previously set as the shooting preparation switch (S).
I turned on l) and performed focus detection, but the focus could not be detected.
This is a case where a lens position where focus detection is possible cannot be found even after performing a low contrast scan, or a case where a lens position where focus detection is possible cannot be found even after performing a low contrast scan. In this case, the flag LS is set in #157.
Return ENDF to 0, set the lens initial position in #65 to #75, and proceed to #145. Note that when proceeding to #157, be sure to only proceed when the shooting preparation switch (Sl) is turned on after being turned off. It is.

At this time, the reason for setting the lens initial position is that the low contrast scan end flag L S E N D F 1
This is because the probability that the subject you want to photograph exists near the current lens position is low, and especially when low-contrast scanning is actually performed, the lens position may be near infinity or the closest position. Since it is biased,
This is because it is necessary to return it to its proper position.

Next, when passing through #330 in Figure 8, it is determined in #185 and #180 (Figure 4) that the brightness is low and focus cannot be detected, so auxiliary light emission is necessary. However, there are cases where it is useless to emit the auxiliary light, so #3
The determination is made in steps 30 and #335. Here, the auxiliary light emitting device (ILM) shown in FIG. On the other hand, the focus detection circuit (AFC) includes a light emitting diode and an optical system for projecting light.
It includes a TTL phase difference detection power type focus detection optical system, and its optical axis coincides with the optical axis of the photographing lens. Therefore, the luminous flux range of the optical system for auxiliary light projection and the luminous flux range for focus detection have a disparity, and from a predetermined distance in front of the photographic lens (varies depending on the angle of view), the luminous flux range for focus detection The luminous flux range of is completely included in the luminous flux range of the optical system for auxiliary light projection.This distance is the lower limit of the range in which the auxiliary light can illuminate the subject to enable focus detection, and it is closer than this. It is useless to emit auxiliary light on the subject. Further, when a long focal length lens is attached to the camera, the auxiliary light is vignetted by the lens barrel, so the auxiliary light does not hit the subject, and even if the auxiliary light is emitted, it may be wasted. Note that the lower limit of the range in which the subject can be illuminated to enable focus detection with fill light can be reduced by adopting a TTL fill light system, but the upper limit of the range in which focus detection is possible with fill light irradiation can be made smaller. The thing is, the reach distance of the auxiliary light is about 10 mm at most, so we can't expect much from it.Therefore, in #330, the focal length of the lens is r.
is 2501 or more, and in #330 f≧25
If it is 0, it is determined that the auxiliary light may be vignetted due to the long lens length, and the auxiliary light is not emitted and #190 (
Proceeding to FIG. 5), it is determined whether a low contrast scan is necessary. In addition, when shooting with a long focal length lens, there are many long-distance shots where the auxiliary light does not reach, so there is not much problem with disabling the auxiliary light, unless it is #330 and f≧250.
At step 335, it is determined whether there is a macro lens attachment signal LCPH of equal or greater magnification. If a macro lens of 100% magnification or higher is attached in #335, it is determined that the shooting is at close range, which is closer than the lower limit of the range where focus detection is possible with auxiliary light irradiation.
Without emitting the auxiliary light, the process proceeds to #190 (FIG. 5), where it is determined whether a low contrast scan is necessary. If in #335 a macro lens of equal or larger magnification is not attached, an auxiliary light is emitted in #340, focus detection is performed in #345, and it is determined in #350 whether focus detection is impossible. The auxiliary light is emitted only for a predetermined period of time for each focus detection. If focus cannot be detected in #350, proceed to #395. If focus cannot be detected in #350, use an intermediate distance within the range where focus can be detected using an auxiliary light (e.g. 4 m), or a distance where there are relatively many photographic scenes. (For example, 3m) To adjust the lens position to Do, #
At 355, lens drive amount ΔN-(f2/Do)XK-Nl
- is calculated, and lens driving is started in #360. 4
In 361, it is determined whether the lens drive amount has reached ΔN.

If the lens driving amount has not reached ΔN in #361, the determination operation in #361 is repeated until the lens driving amount reaches ΔN. If the lens drive amount reaches ΔN in #361, #
At 362, lens driving is stopped. Then, the auxiliary light is emitted in #370, the focus is detected in #375, and the focus is detected in #380.
Determine whether focus detection is impossible. If it is not possible to detect the focus in #380, proceed to #395. If it is not possible to detect the focus in $380, display that the focus cannot be detected in #385,
In #390, it is determined whether the photographing preparation switch (Sl) is ON. At #390, the shooting preparation switch (Sl) is turned on.
If so, return to #375. If the shooting preparation switch (Sl) is not ON in #390, turn off the display in #40,
Return to #30.

In #395, the focus detection failure display is erased, and in #400, it is determined whether focus is achieved. If the focus is #400, #4
In step 20, an in-focus display is performed, and in step #425, it is determined whether the photographing preparation switch y (Sl) is ON. If the shooting preparation switch (Sl) is ON in #425, the determination in #425 is repeated until the shooting preparation switch (Sl) is no longer ON, and if the shooting preparation switch (Sl) is no longer ON in #425. , erase the display in #40, and return to #30. #4
If it is not in focus with 00, set the defocus amount DF with #405.
The lens driving amount ΔN=DFXK is calculated from the above, and lens driving is started in #410. In #412, it is determined whether the lens drive amount has reached ΔN. If the lens drive amount has not reached ΔN in #412, the determination operation in #412 is repeated until the lens drive amount reaches ΔN. If the lens drive amount reaches ΔN in #412, the lens drive is stopped in #413. , it is determined in #415 whether the photographing preparation switch (Sl) is ON. If the photographing preparation switch (Sl) is ON in #415, the process returns to #370; if not, the display is turned off in #40, and the process returns to #30.

[Effects of the Invention] In the lens interchangeable automatic focusing device of the present invention,
When the special lens is attached, the initial position of the lens is set to approximately the middle position of the movable range, so it is possible to secure approximately the same focus adjustment range on the front focus side and the rear focus side, and the focus This has the effect that the probability of reaching the in-focus state increases regardless of whether the focus is shifted toward the front focus side or the rear focus side when detection is started.

Further, in the interchangeable lens of the present invention, first data indicating that the coarse focus adjustment range is wider than the fine focus adjustment range, and second data indicating the movable range of the fine focus adjustment member are output. This has the effect that the lens-interchangeable automatic focus adjustment device can easily determine whether a special lens is attached by detecting the first data.
Further, there is an effect that the initial position of the lens can be easily set based on the second data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a block circuit diagram of an embodiment of the present invention, and FIGS.
12 and 13 are explanatory views of the same operation, and FIG. 14 is a cross-sectional view of the enlargement variable power device used in the above. (1) is an interchangeable lens, (2) is an automatic focus adjustment device, (1)
1) is a coarse focus adjustment member, (12) is a power transmission mechanism, (
13) is a focus fine adjustment member, (14) is a data output means, (21) is a focus detection means, (22) is a lens driving means, (23) is an initial position determining means, and (24) is a control means.

Claims (6)

[Claims] (1) An automatic focus adjustment device that is used in combination with an interchangeable lens that has a built-in data output means that outputs lens-specific data and that is equipped with a focus adjustment member that can be electrically operated from the outside via a power transmission mechanism, a focus detection means for detecting a focus state of the interchangeable lens; a lens drive means for driving a focus adjustment member of the interchangeable lens based on a focus detection result by the focus detection means; and a first data read from the data output means of the interchangeable lens. an initial position determining means that determines the initial position of the focus adjusting member to be approximately the middle position of the movable range of the focus adjusting member when the focus adjusting member is moved; 1. A lens-interchangeable automatic focus adjustment device comprising: control means for controlling a lens drive means to drive a focus adjustment member to an initial position. (2) The data output means is means for outputting second data regarding the movable range of the focus adjustment member, and the initial position determination means determines the initial position of the focus adjustment member from the second data read from the data output means of the interchangeable lens. 2. The lens-interchangeable automatic focusing device according to claim 1, wherein the lens-interchangeable automatic focusing device is a means for determining. (3) The data output means is a means for outputting third data regarding the focal length of the interchangeable lens, and when the first data is not read from the data output means of the interchangeable lens, the initial position determining means is a means for outputting third data regarding the focal length of the interchangeable lens. 3. The lens-interchangeable automatic focus adjustment device according to claim 1, further comprising means for determining the initial position of the focus adjustment member from third data read from the output means. (4) In an interchangeable lens that includes a coarse focus adjustment member that can be operated manually and a fine focus adjustment member that can be electrically operated from the outside via a power transmission mechanism, the coarse focus adjustment range is wider than the fine focus adjustment range. 1. An interchangeable lens comprising: a data output means for outputting first data indicating the focus adjustment range and second data indicating the focus fine adjustment range. (5) The interchangeable lens according to claim 4, wherein the lens is for macro photography at a magnification of 100% or more. (6) The lens has variable magnification, and the focus adjustment error caused by the coarse focus adjustment member at a predetermined magnification is magnified by the variable power operation, and is larger than the fine focus adjustment range at other magnifications. The interchangeable lens according to claim 4 or 5, characterized in that: