JPH0711616B2 - Autofocus device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus device that automatically adjusts a focus of a lens that is focused by an optical system other than the most object-side optical system.

2. Description of the Related Art As a case where focusing is performed by an optical system other than the optical system on the most object side, for example, the following cases can be considered.

Even if an interchangeable lens that does not have an AF function is attached to the camera body of an interchangeable lens camera that has an autofocus (AF) function, the AF function does not work.

Therefore, an autofocus device configured to activate the AF function by attaching an AF converter having the AF function between the camera body having the focus detection unit and the interchangeable lens not having the AF function has been conventionally used. Various proposals have been made. For example, it is proposed in JP-A-54-028133, JP-A-58-098711, JP-A-58-098712, and JP-A-58-114008.

Problems to be Solved by the Invention However, such a conventional autofocus device has the following problems.

(A) The focus detection unit only detects the front focus, the rear focus, and the focus, and does not perform the automatic focus adjustment operation in advance by obtaining the amount to move the converter lens. That is, since the converter lens is moved by the feedback control based on the front focus, rear focus, and focus detection data, problems such as hunting of the lens near the focus position are likely to occur, and this can be avoided. Has a problem that the moving speed (focusing speed) of the converter lens must be set low.

(B) Even though the focus detection unit provided in the camera body can obtain the defocus amount, only the front focus, rear focus, and focus signals are used for automatic focus adjustment. Since there is no focus detection function, the bending angle function of the focus detection unit is wasted, and the focusing accuracy is low.

The cause is that an accurate focus movement amount cannot be obtained because the relationship between the defocus amount and the focus movement amount of the converter lens is not linear.

The present invention has been made in view of the above circumstances, and increases the focusing speed and enhances the focusing accuracy by fully utilizing the defocus amount detection function of the focusing detection unit. The purpose is to

Another object of the present invention is to enable a more accurate automatic focus adjustment operation.

Means for Solving the Problems The present invention has the following configuration in order to solve the above problems.

That is, the autofocus device of the present invention has a structure as shown in the block diagram of FIG.

Defocus amount detecting means (DFDM) for detecting a defocus amount d by the first optical system (L) and the second optical system (CL) arranged on the film surface side of the first optical system (L) is provided. ing.

Further, the focusing movement amount x of the second optical system (CL) changes non-linearly with respect to the defocus amount d, but by referring to the position of the second optical system, the defocus amount d
Is provided with a defocus amount / focus movement amount data conversion means (DMDM).

Further, an optical system drive unit (LD) for moving the second optical system (CL) based on the data of the focus movement amount x from the defocus amount / focus movement amount data conversion unit (DMDM).
M).

Operation The operation of this configuration is as follows.

(I) The in-focus movement amount of the second optical system has an inherently non-linear relationship with the defocus amount. However, the defocus amount / focus movement amount data conversion means provides a certain one-to-one correspondence relationship between the defocus amount and the second optical system movement amount having such a non-linear relationship. It is a thing.
That is, the in-focus movement amount of the second optical system obtained by converting the defocus amount is a movement amount corresponding to making the defocus amount substantially zero.

Therefore, the defocus amount detected by the defocus amount detecting means is adjusted by the defocus amount / focus movement amount data converting means to make the defocus amount substantially zero, and the optimum focus of the second optical system. Converted to movement amount data.

In this way, the optical system driving means drives and controls the second optical system based on the focusing movement amount data obtained in advance before the actual focusing movement of the second optical system. Is controlled so that the defocus amount is substantially zero in the actual focusing movement.

That is, since the focus movement amount data is obtained in advance before the actual focus movement of the second optical system, the automatic focus adjustment operation functions extremely effectively. Therefore, it is possible to reliably prevent the occurrence of a problem such as hunting in the vicinity of the in-focus position of the second optical system as in the case of the conventional feedback control, and it is possible to perform autofocus at a high speed and a high accuracy. .

(Ii) Then, the function of the defocus amount detecting means originally provided in the autofocus device for obtaining the defocus amount is effectively utilized without waste in improving the focusing accuracy.

Principle of the Invention Hereinafter, between the camera body (C) having the defocus amount detection means and the interchangeable lens (B) having no AF function,
The principle of the present invention will be described based on an example in which an AF converter (A) having an AF function is mounted.

FIG. 2 is an interchangeable lens in which the rear principal point position of the second optical system (CL) in the AF converter is at a position separated from the film surface (FP) by a distance 1 and is in front of the second optical system (CL). The first optical system (not shown) has a focal point at a position a ₁ away from the second optical system (CL), and the image of the focal point is formed by the second optical system (CL). Distance from (FP) d
It represents a non-focused state in which the image is re-imaged at a position deviated by (defocus amount).

FIG. 3 shows the distance x from the state of FIG. 2 to the second optical system (CL).
The figure shows a state in which the final image is formed on the film surface (FP) by moving it only in the direction approaching the film surface (FP).

With the focal length of the second optical system (CL) as f, from the state of FIG. b ₁ = d + 1 ... (2)

Also, from the state of FIG. _{a 2 = a 1 -x ......... (} 4) b 2 = l-x ......... relationship (5).

From equations (3), (4), and (5), Is obtained.

By modifying the equation (6), a quadratic equation of x ² + (2f-l-a ₁ ) x + (a ₁ l-fl-a ₁ f) = 0 (7) is obtained.

However, from equation (1), f is the focal length of the second optical system (CL) in the AF converter, which is known. l is the distance between the rear principal point position of the second optical system (CL) and the film surface (FP) at the start of distance measurement, and d is the distance measured by the second optical system (CL) at the start of distance measurement. The distance between the image formation position and the film surface (FP), that is, the defocus amount.

X in the equation (7) is a movement amount (focus movement amount) of the second optical system (CL) necessary for focusing.

From equations (7) and (8), it can be understood that the focus movement amount x of the second optical system (CL) has a non-linear relationship with the defocus amount d.

Then, when the values of l and d at the start of distance measurement are obtained, since f is known, a ₁ can be obtained from the equation (8). If a ₁ is known, the second optical system (C
The in-focus movement amount x of L) can be obtained.

For example, the first optical system (photographing lens system; Gaussian lens system) in the interchangeable lens is composed of lenses L _{1 to} L ₆ ,
The second optical system in AF converter (A) (converter Lens) (CL) is supposed to be composed of a lens L ₇ ~L _11. The relationship among the radius of curvature, core thickness, refractive index and Abbe number of each lens is shown below.

The lenses L ₄ , L ₅ and the lenses L ₇ , L ₈ , L ₉ are in contact with each other. d ₂ , d ₄ , d ₆ , d ₉ , d ₁₅ and d ₁₇ are distances between adjacent lenses.

In this case, the focal length f of the second optical system (CL) in the AF converter (A) composed of the lenses L _{7 to} L ₁₁ is f = −139.95 [mm].

An adjacent distance d ₁₁ between the first optical system and the second optical system (CL) in the interchangeable lens including the lenses L _{1 to} L _6.
Fluctuates by moving the AF converter (A) away from the interchangeable lens and approaching the film surface (FP), or approaching the interchangeable lens and moving away from the film surface (FP).

When the adjacent distance d ₁₁ is d ₁₁ = 2.0, it focuses on infinity (shooting magnification β = 0), and when d ₁₁ = 5.0, it focuses on proximity.
It is assumed that the shooting magnification β is 1/10. Shooting magnification β is 0
The range from 1 to 1/10 can cover substantially the entire subject distance range.

The focal length f of the second optical system (CL) is f = -139.95, and the distance l between the rear principal point position of the second optical system (CL) and the film surface (FP).
And the defocus amount d which is the distance between the final image forming position and the film surface (FP), the focusing movement amount x of the second optical system (CL) is calculated based on the equation (7). Is shown in Table 1.

Further, l = 141 is a value when focusing on infinity.
In this case, as described above, d ₁₁ = 2.0 (shooting magnification β =
0), and in the case of d ₁₁ = 5.0 in which 3.0 is added to 2.0, l = 138 and the photographing magnification β = 1/10.

Expressions (7) and (8) are expressed by x ² + (2f-l-a ₁ ) x + (a ₁ l-fl-a ₁ f) = 0 (7) Therefore, the focus movement amount x is a function of f, l, and d. That is, x = F (f, l, d) ... (9).

In order to perform a highly accurate focusing operation, f is known, and l,
Needless to say, it is necessary to accurately obtain d.

However, as can be seen from Table 1, the film surface (F
When the defocus amount d, which is the shift amount with respect to P), is constant, the change in the focus movement amount x with respect to a small change in l, which is the position information of the second optical system (CL) of the AF converter (A), is very small. is there.

Therefore, the focusing movement amount x can be fairly accurately calculated based on the defocus amount d and the focal length f of the second optical system (CL) regardless of the position information l of the second optical system (CL). You can ask.

For example, when the defocus amount d is d = + 10, l
= 141 (shooting magnification β = 10), focus movement amount x = -1.9
If the average value of -1.939 of 23 and the focus movement amount x = -1.954 when l = 138 (shooting magnification β = 0) is adopted, the second optical system (CL) can be combined with a slight error of about 15μ. Focus can be controlled. About 15μ is well within the depth of focus for a normal shooting lens.

From the above, the focus movement amount x can be regarded as a relational number of f and d. That is, x = G (f, d) ... (10) From this, the defocus amount / focus movement amount data conversion means (DMD) in the configuration of the present invention.
As described above, M) is converted into data corresponding to the focusing movement amount x of the second optical system (CL) in the AF converter that changes non-linearly with respect to the defocus amount d. It was decided.

Of course, if the second optical system (CL) position data output means is provided and the focusing movement amount x is obtained from f, d, and l based on the equation (7), more accurate focusing control can be achieved. It goes without saying that you can do it.

Examples Hereinafter, the present invention will be described in detail based on the examples shown in the drawings. In this embodiment, the present invention is applied to an autofocus type camera.

FIG. 4 is a schematic sectional view of the autofocus type camera.

FIG. 4 shows an AF converter (A) and a conversion lens (B).
And the camera body (C) are shown.

The second optical system (CL) in the AF converter (A) is composed of a plurality of lenses, which will be hereinafter referred to as a converter lens (1).

A male helicoid (3) and a rectilinear groove (4) are provided on the outer circumference of the male helicoid cylinder (2) holding the converter lens (1). A female helicoid cylinder (6) having a female helicoid (5) screwed into the male helicoid (3) provided on the inner circumference has one end between the fixed outer cylinder (7) and the fixed inner cylinder (8). , Is rotatably fitted and held, and has a helicoid gear (9) on the outer periphery of the other end.

A pinion gear (1 that meshes with the helicoid gear (9)
A driven coupler (11), to which (0) is fixed, is rotatably supported by a fixed outer cylinder (7). A drive coupler (12) is engaged with the driven coupler (11), and the drive coupler (12) is linked to a motor (14) via a drive gear (13).

The straight advance key (15) extended from the fixed inner cylinder (8) is inserted into the straight groove (4) of the male helicoid cylinder (2) to restrict the rotation of the male helicoid cylinder (2). Therefore, when the female helicoid cylinder (6) rotates due to the rotation of the motor (14), the male helicoid cylinder (2) and the converter lens (1) move along the optical axis (16). That is, the converter lens (1) moves forward and backward by the normal rotation and reverse rotation of the motor (14).

A brush (17) is attached to the outer periphery of the female helicoid cylinder (6), and this brush (17) is attached to the cord plate (18) attached to the inner peripheral surface of the fixed outer cylinder (7). Sliding contact is possible. The code plate (18) outputs a signal corresponding to the rotation amount of the female helicoid cylinder (6). The rotation amount of the female helicoid cylinder (6) is the current position data L _P of the converter lens (1) along the optical axis (16) (this is shown in FIG.
Since corresponding equivalent) to the distance l of Figure 3, the code plate (18), current position data L _P converter lens (1)
Signal will be output.

The code plate (18) is a ROM attached to the fixed outer cylinder (7)
-It is connected to the IC (19) through the conductor (20). ROM-IC (19) is configured to specify an address based on the current position data L _P of the output converter lens (1) from the code plate (18).

The open signal pin interlocking lever (22) is rotatably supported by the fixed front cylinder (21) while being positioned between the fixed inner cylinder (8) and the fixed front cylinder (21), and by a spring (not shown), It is urged to rotate counterclockwise when viewed from the subject side.

On the rear surface of the release signal pin interlocking lever (22), the brush (2
3) is attached, and the brush (23) is configured to be slidably contactable with the code plate (24) attached to the front surface of the fixed inner cylinder (8).

An open signal pin (27) is projected from the male mount (26) of the removable interchangeable lens (B) to the female mount (25) attached to the fixed front cylinder (21).

When the interchangeable lens (B) is attached to the AF converter (A), the opening signal pin interlocking lever (22) is rotated against the biasing force due to the contact with the opening signal pin (27). As a result, the code plate (24) outputs a signal corresponding to the rotation amount of the opening signal pin interlocking lever (22). This signal is a signal corresponding to the open F value (aperture value) of the interchangeable lens (B).

The code plate (24) is connected to the ROM-IC (19) via a conductor (28). ROM-IC (19) is
The address is designated based on the data corresponding to the open F value of the interchangeable lens (B) output from the code plate (24).

The opening setting lever (29) is fixed to the fixed inner cylinder (8) of the AF converter (A). In the interchangeable lens (B), an aperture ring (31) is rotatably mounted between the male mount (26) and the fixed front cylinder (30), and the aperture interlocking lever (in the state linked to the aperture ring (31) ( 32) is projected.

When the interchangeable lens (B) is attached to the AF converter (A),
The aperture interlocking lever (32) of the interchangeable lens (B) is engaged with the opening setting lever (29), whereby the aperture interlocking lever (32) rotates to a predetermined position and the interchangeable lens (B).
Restrict the narrowing position of the aperture ring (31) at.

If the focus detection unit [including a light receiving unit (42) and a microprocessor (43) described later can detect the focus only up to the aperture value F8, the open setting lever (29) is set to F8. The lever may be configured so that it can only be narrowed down.

The interchangeable lens mounting signal pin (33) mounted on the female mount (25) so as to freely move back and forth is projected by the spring biasing force of the microswitch (34). When the interchangeable lens (B) is attached to the AF converter (A), the interchangeable lens attachment signal pin (33) is retracted and the micro switch (34) is closed. The micro switch (34) is connected via the conductor (35).
It is connected to the ROM-IC (19) and is configured so that power can be supplied from the camera body (C) to the ROM-IC (19) by closing the same.

A signal contact (36) is provided at the rear end of the fixed outer cylinder (7) of the AF converter (A). The signal contact (36) and the ROM-IC
(19) is connected via a conductor (37). A signal pin (39) is attached to the front ring (38) of the camera body (C), and when the AF converter (A) is attached to the camera body (C), the signal pin (39) and the signal contact point are attached. (3
6) is configured to be connected to.

The camera body (C) has a half mirror (40), a sub-mirror (41), a light receiving section (42) including an optical system for pupil division and CCD (charge coupled device), and a calculation for focus detection. A microprocessor (43) that controls focus control and a pulse encoder (44) are mounted.

The half mirror (40), the sub mirror (41), the light receiving unit (42), and the focus detection calculation unit of the microprocessor (43)
It corresponds to the defocus amount detecting means (DFDM) in FIG.

Signal pin (39), to microprocessor (43)
The light receiving section (42), the motor (14) and the photo interrupter (45) of the pulse encoder (44) are connected to each other. (46) is a slit plate of the pulse encoder (44).

The motor (14) corresponds to the driving means (LDM) of the second optical system (CL) in FIG.

As a component of the interchangeable lens (B), (47)
Is a male helicoid cylinder equipped with the first optical system (L), (4
8) is a female helicoid tube, (49) is a female helicoid tube (4
8) Operation ring, (50) is a straight groove, (51) is a straight key.

Next, the structure of the microprocessor (43) will be described with reference to FIG.

In FIG. 5, (CMC) is a microcomputer that controls exposure control, data transfer control, power supply control, and camera system sequence control. Below, this is called a control microcomputer (CMC).

(S ₁ ) is for pressing the release button (not shown) 1
It is a photometric switch that is closed at the stage. (S ₂ ) is a release switch that is closed in the second step of pressing down the release button.

When the photometric switch (S ₁ ) is closed, the control microcomputer (CM
An interrupt signal is input to the interrupt terminal (INT ₀ ) of C), and the control microcomputer (CMC) that is in the stopped state is driven,
The operation of the entire camera system starts. When the release switch (S ₂ ) is closed, the exposure control operation of the camera is started.

(S ₄ ) is a safety switch that is turned on when the exposure control operation is completed, and turned off when the film winding and the charge of the exposure control mechanism are completed. (SL) is a mounting switch that is turned on when the interchangeable lens (B), the adapter, or the like is mounted on the lens mounting portion of the camera body (C).

(BA) is the battery that powers the entire camera system, (C
V) is a power supply control circuit controlled by a signal from the output port (OP ₀ ) of the control microcomputer (CMC). This power supply control circuit (CV) constantly supplies power to the power line (V _DD ),
Power is supplied to the power supply line (+ V) only when the output port (OP ₀ ) is at the “L” level.

In addition, from the power line (+ V) to the photometry unit (LM), converter circuit (CEC), interface circuit (IFC), encoder (ENC) [≡ pulse encoder (44)] and exposure control circuit (EC). Power is supplied. The rest of the circuit is configured to be powered from the power supply line (V _DD ).

(LM) is a photometric unit composed of a photometric circuit and an A / D conversion circuit, (DP) is a display unit that displays exposure control data, and the like.
(DO) is a data output unit that outputs exposure control data such as film sensitivity. (EC) is the control microcomputer (CM
The exposure control unit controls the exposure based on the aperture value and exposure time data from C).

The control microcomputer (CMC) has a serial data input / output function, and the serial data input function is the interchangeable lens (B) or
Controls data input from the AF converter (A). The serial data output function controls the data output to the AF microcomputer (AMC).

(SV) is a switch that is turned on only when a normal interchangeable lens (old lens) (B) having no AF function is attached to the AF converter (A).

This switch (SV) is the micro switch (34) in Fig. 4.
Equivalent to.

In FIG. 5, (CEC) surrounded by a broken line is a converter circuit that controls data output in the AF converter (A).
(LP) is the current position data L _P of the converter lens (1)
Is a code plate for outputting, which corresponds to the code plate (18) in FIG.

(TP) is a code plate that outputs data corresponding to the open aperture value of a signal member indicating the open aperture value of the interchangeable lens (B) mounted on the AF converter (A). Corresponds to the code plate (24) in FIG.

The signal member may be a protrusion amount of the pin, a distance from the reference position of the pin when the interchangeable lens (B) is completely mounted, or an aperture value setting member such as an aperture ring (31). There are provided signal members and the like. In the case of the aperture value setting member, the signal of the set aperture value is output instead of the open aperture value.

(RO) is a ROM (Read Only Memory) in which various data are fixedly stored, and this ROM (RO) is the R of FIG.
Located in the OM-IC (19).

The relationship between the data stored in the ROM (RO) and the address is as shown in Table 2.

It should be noted that Tables 3 and 4 show a new lens with a fixed focal length and a new lens with a variable focal length (zoom lens) which are manufactured by directly matching with the autofocus device of the present invention which employs the new lens system. ) In the ROM
The relationship between the data stored in (RO) and the address is shown.

As can be seen from these tables, the camera body (C) reads 10 types of data. That is, the control microcomputer (CMC) sets the signal line (CSLE) connected to the output port (OP ₄ ) to the “L” level and performs the serial input / output operation 10 times. In one serial input / output operation, eight clocks are output from the clock output terminal (SCO) to the controller (LCC) of the converter circuit (CEC). In parallel with this clock, the parallel data from the selector (SE) is converted into serial data by the parallel-serial conversion circuit (PS) and transferred to the control microcomputer (CMC) of the camera body (C).

The controller (LCC) counts the clock and
Specify addresses in the order shown in the table. Then, the next address 04 _H, specifies the address 1 _H Based upper 4 bits are the count data, the lower 4 bits are code plate (TP)
Output the data from. Then, one address of the address 10 _H ~1F _H is specified, AF converter (A)
The AF aperture value data AFA _VO for the open aperture value or the set aperture value of the interchangeable lens (B) attached to is output.

When the interchangeable lens (B), which is not provided with a member for transmitting the data of the open aperture value and the set aperture value, is attached, the same data as when the brightest lens is attached from the code plate (TP) is attached. Is output and the AFA _VO data that causes the focus detection operation is transmitted. This will cause a malfunction when a dark lens that cannot perform the actual focus detection operation is mounted. However, it is still better than the case where the focus detection operation can be performed but the focus detection operation cannot be performed.

If address _21H is specified, the controller (LCC)
Sends a signal for outputting the data from the code plate (LP) to the selector (SE). Only in this case, the selector (SE) is not the data of ROM (RO) but the code board (L
Current position data of converter lens (1) L _P from P)
Is output.

After this, when the transfer of the data at addresses 22 _H and 23 _H is completed, the control microcomputer (CMC) stops the serial input / output operation and sets the signal line (CSLE) to the “H” level to convert the converter circuit. Stop the operation of (CEC).

It should be noted that fixed focus lens, variable focus lens (zoom lens) configuration, or, although not shown in the table, it can perform AF operation and aperture control suitable for this new camera system. Regarding the configuration of the intermediate accessory (new converter) mounted between the converter and the converter, see JP-A-59-084228 and JP-A-59-18.
8622, JP 59-188609, JP 59-0934
It is disclosed in Japanese Patent Laid-Open No. 10-58, Japanese Patent Laid-Open No. 59-140408, and the like, and it is known, and therefore its explanation is omitted.

(AMC) is a microcomputer for automatic focus adjustment (autofocus). In the following, this is referred to as the AF microcomputer (AMC). (DD) is a CCD (charge coupled device) that detects subject brightness distribution from two exit pupils of the photographing optical system. The optical system for light incidence on the CCD (DD) is described in, for example, JP-A-60-031109 and JP-A-60-03.
Since it is disclosed in Japanese Patent Publication No. 2014 and the like and is publicly known, description thereof will be omitted.

Regarding the configuration of the CCD (DD) light receiving element,
For example, it is disclosed in JP-A-60-031109, JP-A-59-126517, etc., and since it is publicly known, its explanation is omitted.

(IFC) drives the CCD (DD) based on the control signal from the AF microcomputer (AMC), A / D-converts the data of each light receiving element (pixel), and transmits it to the AF microcomputer (AMC). It is an interface circuit. Interface circuit (IFC)
The specific configuration of the above is disclosed, for example, in JP-A-59-126517 and JP-A-59-140408.
Since it is publicly known, its explanation is omitted.

(ADP) is a focus adjustment status display section. This focus adjustment status display section (ADP) lights the front pin display section (FF) when the output port (OP ₁₁ ) is at the “L” level, and outputs focus display portion when the port (OP ₁₂₎ is "L" level turns on the (FM), turns on the rear focus display unit (RF) when the output port (OP ₁₃₎ is "L" level, the output When the port (OP ₁₀ ) is at “L” level, the front pin display (FF) or rear pin display (R)
F) blinks.

(MC) is a control circuit of a motor (MO) [≡ motor (14)] for driving the converter lens (1). The motor control circuit (MC) controls the motor (MO) so that the converter lens (1) moves in the focusing direction from the front focus position when the output port (OP ₁₄ ) is at "L" level. Further, when the output port (OP ₁₅ ) is at the “L” level, the motor (MO) is controlled so that the converter lens (1) moves in the focusing direction from the rear focus position, and the output port (OP ₁₄ ),
When both (OP ₁₅ ) are at "L" level, the motor (MO) is braked to stop the converter lens (1) suddenly, and both output ports (OP ₁₄ ) and (OP ₁₅ ) are set to "L". Disables the motor (MO) at H "level.

The motor control circuit (MC) rotates the motor (MO) at high speed when the output port (OP ₁₆ ) is at "H" level, and the motor (MO) when the output port (OP ₁₆ ) is at "L" level. ) Rotate at low speed.

The rotational force of the motor (MO) is, for example, as disclosed in JP-A-59-140408 and JP-A-59-093410, a new interchangeable lens, a new converter, A
It is transmitted to the F converter.

Further, the rotation amount of the motor (MO) is monitored by the encoder (ENC), and the number of pulses corresponding to the rotation amount is output to the new interchangeable lens, the new converter, the AF converter, and the like.

The pulse from this encoder (ENC) is transmitted to the motor control circuit (MC) to control the speed of the motor (MO).
In addition, the clock input pin (SCK) of the AF microcomputer (AMC)
It is also transmitted to I).

The presettable event counter (ECO) (not shown) inside the AF microcomputer (AMC) presets the planned rotation amount N of the motor (MO). The presettable event counter (ECO) is For each pulse input at the clock input pin (SCKI),
Do 1 When the count value reaches zero, a counter interrupt occurs and the AF microcomputer (AMC) performs the interrupt process.

The switch (AFS) connected to the AF microcomputer (AMC) is
Turns on when the automatic focus adjustment mode (AF mode) is selected, and turns off when the manual focus adjustment mode (FA mode) is selected.

When the signal line (AFSTA) falls to "L" level, AF
The interrupt pin (INTA) of the microcomputer for AMC is interrupted, and the AF microcomputer (AMC) starts operating. on the other hand,
When the signal line (AFSTP) falls to "L" level, AF
The interrupt pin (INTB) of the microcomputer (AMC) for use is interrupted, and the AF microcomputer (AMC) stops after the specified operation.

When the signal line (DREQ) connected to the output port (OP ₁₇ ) goes to "L" level, the interrupt signal is input to the interrupt pin (INT ₁ ) of the control microcomputer (CMC) and the control microcomputer (CMC).
The data necessary for the AF microcomputer (AMC) is sent in series from. That is, when the signal line (CSAF) becomes "L" level, the control microcomputer (CMC) changes the AF microcomputer (A
MC) to send the necessary data in series.

To send such data, the AF microcomputer (AM
The control microcomputer (CMC) is connected to the serial input terminal (SIN) of C).
The serial output terminal (SOUT) of is connected. Furthermore, AF
For the synchronous clock input pin (SCKI) of the microcomputer (AMC) for control, the synchronous clock output pin (SCK) of the control microcomputer (CMC)
O) is connected.

Operation of Control Microcomputer (CMC) Next, the operation of the control microcomputer (CMC) will be described with reference to the flowchart of FIG.

When the photometric switch (S ₁ ) is closed in the first step of pressing down the release button, an interrupt signal is input to the interrupt terminal (INT ₀ ) of the control microcomputer (CMC) and the control microcomputer (CM
Driving of C) is started.

In step # 1, the power supply control circuit (CV) is operated to start power supply from the power supply line (+ V).

In step # 2, the signal line (CSLE) connecting the control microcomputer (CMC) and the converter circuit (CEC) is set to "L" level. As a result, the converter circuit (CEC) of the AF converter (A) [or the lens circuit of the mounted interchangeable lens] is activated.

In step # 3, the contents of the register (n) in the control microcomputer (CMC) are reset to zero (initial setting), and in step # 4, serial input / output operation (SIO) is executed.

As a result, the data read by the serial input / output register (IOR) in the control microcomputer (CMC)
5, the register (Rn) in the control microcomputer (CMC) [n =
0]. In step # 6, the content of the register (n) is incremented by 1.

In step # 7, it is determined whether the content of the register (n) becomes "9". If NO, the process returns to step # 4 and the operations of steps # 4 to # 7 are repeated until the content of the register (n) becomes "9". When the content of the register (n) becomes "9", the process proceeds to step # 8, the signal line (CSLE) is set to "H" level, and the converter circuit (CE
C) Disable [or lens circuit]. As a result, the data set in registers (R ₀ ) to (R ₉ ) is
It looks like Table 5.

That is, the data specific to the AF converter (A) stored in the ROM (RO) of the AF converter (A) is controlled by the control microcomputer (CM).
Transfer to C).

Here, a lens system equipped with the autofocus device according to the present invention is defined as a "new lens system", and an interchangeable lens suitable for the open photometric exposure calculation means included in the control microcomputer (CMC) in this new lens system. Is defined as a "new lens", and a converter that is also suitable is defined as a "new converter". The new lenses are shown in Tables 3 and 4
There are new lenses with fixed focal length and new lenses with variable focal length shown in the table.

In addition, the control microcomputer (CMC) in the new lens system
The interchangeable lens that is not compatible with the full-aperture metering exposure calculation means and the autofocus device possessed by is defined as "old lens".

The AF converter (A) shown in FIG. 4 is for performing autofocus with an old lens that is not compatible with the autofocus device of the new lens system, and this AF converter (A) is simply referred to as an AF converter. Sometimes.

In Table 6, the combination of the underlined old lens and the AF converter is the state shown in FIG.

As shown in Table 6, if the taking lens mounted on the camera body (C) is a new lens compatible with the new lens system or a combination of the new lens and the AF converter, the register (R ₀ ) The check data 88 _H is set in.

If the attached photographic lens is a combination with the AF converter (A) in FIG. 4 and an old lens that is not compatible with the new camera system (old lens system), the check data 80 is stored in the register (R ₀ ). _H is set.

Data shown in Table 5 is set in the registers (R ₁ ) to (R ₄ ) in the case of the new lens system, and data of ** _H is set in the case of the old lens system.

In the register (R ₅ ), in the case of the new lens system, if the new lens has a fixed focal length, the aperture value data for AF AFA _VO
(≡ open aperture value A _VO ) is set, and for a new lens (zoom lens) with a variable focal length, the maximum aperture value out of all the focal lengths is the AF aperture value data.
Set as AFA _VO . In the case of the old lens system, the open aperture value or set aperture value of the mounted interchangeable lens (B) is set in the register (R ₅ ) as AF aperture value data AFA _VO .

In the register (R ₆ ), in the case of the new lens system, in order to convert the defocus amount d into the data of the rotation amount N of the motor (MO) required to move the converter lens (1) to the in-focus position, The motor rotation amount conversion coefficient K _{D of} is set.

In the case of the old lens system, the focusing movement amount x for moving the converter lens (1) to the focusing position is obtained from the defocus amount d by a separate means as described later. It can be said that this means is the basis of the present invention.

Then, the motor rotation amount conversion coefficient K _D for converting the obtained focus movement amount x into data of the rotation amount N of the motor (MO) required to move the converter lens (1) to the focus position. Are set in the register (R ₆ ).

Registers (R ₇ ), (R ₈ ), (R ₉ ) are set with ** _H data in the case of the new lens system, and current position data of the converter lens (1) in the case of the old lens system.
L _P and converter lens (1) are the most camera body (C)
The position data L ₀ when the position is closest to the camera and the position data Lmax when the position is farthest from the camera body (C) are set.

When only the new converter is installed, the new converter converts the data from the new lens and sends the data to the camera body as shown in the above-mentioned known example. become. Also, when only the AF converter is installed, the switch (SV) is open, so the converter circuit (CEC) is not supplied with power, and the state is the same as when it is not installed. Further, the old lens alone cannot be mounted on the camera body because the structure of the mounting portion does not match.

As described above, the ROM (R
The reading of the unique lens data stored in O) is completed.

In step # 9, it is determined whether the mounting switch (SL) is on. If NO (OFF), it means that the taking lens system is not attached to the camera body (C), and the process proceeds to step # 14.

If YES, it means that the taking lens system has been installed, so move to step # 10 and check data.
Determine if 88 _H or 80 _H is being read.
That is, it is checked whether or not the taking lens system is suitable for autofocus.

If either data is read, the process proceeds to step # 11, and if no data is read, the process proceeds to step # 14.

Here, when the mounting switch (SL) is on and neither of the check data 88 _H and 80 _H has been read, for example, only the converter of the new lens system (new converter or AF converter) When it is installed, or when a shooting lens system that does not have a signal transmission function and has only a mount that fits the lens mounting part of the camera body (C) newly appears on the market, and that shooting lens system is installed. Is.

On the other hand, if the check data 88 _H or 80 _H is read, the process proceeds to step # 11, and the AF aperture value data AF
Determine if A _VO is less than a certain aperture value A _VC .

If the AF aperture value data AFA _VO is larger than the constant aperture value A _VC (in the case of NO), the CCD (DD) light receiving part will be “vibrated” by the aperture and focus detection will be accurate. Cannot be performed, the process proceeds to step # 14.

On the other hand, when the AF aperture value data AFA _VO is equal to or less than the constant aperture value A _VC (AFA _VO ≤A _VC ), focus detection can be accurately performed, and the process proceeds to step # 12.

In step # 12, the signal line (AFSTA) is set to "L" level to start the operation of the AF microcomputer (AMC). In step # 13, the input of the interrupt signal to the interrupt terminal (INT ₁ ) of the control microcomputer (CMC) is permitted, and the process proceeds to step # 14.

In step # 14, the data [B _V − (A _VO + ΔA _VZ )] (B _V ; subject brightness) is input from the photometry unit (LM) as photometry data, and in step # 15, the exposure control data output unit ( Input the exposure control data from (DO) and move to step # 16.

In step # 16, it is determined whether the mounting switch (SL) is on. If it is on, the process proceeds to step # 17, and if it is off, the process proceeds to step # 19.

At step # 17, the check data is checked.
If the check data 88 _H has been read, the aperture control is possible with the new lens system, so the flow shifts to step # 18, and open metering calculation is executed. On the other hand, check data
If 80 _H is read, it means that the lens system is an old lens system, and aperture control is impossible. Therefore, the process proceeds to step # 19, and the actual aperture photometry calculation is executed.

Also, if neither of the check data 88 _H and 80 _H has been read, the process proceeds to step # 19.

In the open photometric calculation step # 18, the photometric data, the B _V data of the object luminance, the data of the exposure value E _V, S _V the film sensitivity data, as the data of the exposure time T _V, B _V - are the _{(a VO + ΔA VZ),} E V = - by performing the calculation of _{{B V (a VO + ΔA} VZ)} + (a VO + ΔA VZ) + S V, and calculates an exposure value data E _V, this From exposure value data E _V to aperture value data A _V ,
Exposed time calculation data T _V.

On the other hand, in the actual aperture photometric calculation step # 19, the aperture value data of the imaging lens system is assumed to be A _V, the photometric data, because it is _{B V -A V, T V =} (B V -A V ) + S _V is calculated to calculate the exposure time data T _V ,
Aperture for the data A _V, leave the aperture value of the photographing lens system which is set in advance.

When step # 18 or step # 19 is completed, the process moves to step # 20, and the display unit (DP) such as exposure control data is driven to display the exposure control data calculated in step # 18 or step # 19. To do.

Next, in step # 21, it is determined whether or not the release switch (S ₂ ) is closed. If not closed, the process proceeds to step # 26. If it is closed, the process proceeds to step # 22, and it is determined whether or not the safety switch (S ₄ ) is off. The safety switch (S ₄ ) turns off when the charge to the exposure control mechanism is completed. If it is determined to be off, the process proceeds to step # 26, but if it is determined to be off, the process proceeds to step # 26.
Move to 23.

In step # 23, the signal line (AFSTP) is set to "L" level to stop the operation of the AF microcomputer (AMC). Then
In step # 24, the exposure control operation by the exposure control unit (EC) is executed, and in step # 25, it waits until the safety switch (S ₄ ) is turned on.

When the safety switch (S ₄ ) is turned on, the process proceeds to step # 26, and it is determined whether the photometric switch (S ₁ ) is turned on.

When the release switch (S ₂ ) is turned on in step # 21, it is determined in step # 26 that the photometric switch (S ₁ ) is turned on, and the process returns to step # 2 to perform the above-described data reading, calculation and display. Repeat the operation.

When the release switch (S ₂ ) is off in step # 21, it is determined in step # 26 whether the photometric switch (S ₁ ) is on. And if the metering switch (S ₁ ) is also off, it means that you are not willing to take a picture.
Move to 27.

In step # 27, the signal line (AFSTA) is set to "H" level, and in step # 28, the signal line (AFSTP) is set to "L" level, and after a certain period of time, set to "H" level. As a result, when the microcomputer for AF (AMC) remains in the operating state and the process proceeds to step # 28, the microcomputer for AF (AM
The operation of C) is forcibly stopped.

Next, in step # 29, the display unit (DP) for the exposure control data and the like is stopped and the data display is canceled. Furthermore, in step # 30, after setting to the state in which the input of the interrupt signal to the interrupt terminal (INT ₀ ) of the control microcomputer (CMC) is permitted, in step # 31 the operation of the power supply control circuit (CV) is stopped. Then, the power supply from the power supply line (+ V) is stopped. This stops the operation of the control microcomputer (CMC). That is, the power supply is automatically cut off to prevent wasteful power consumption.

INT ₁ interrupt subroutine When the control microcomputer (CMC) repeats the above-mentioned data reading, calculation and display operations, the interrupt signal from the AF microcomputer (AMC) is sent to the interrupt pin (INT ₁ ). When input, the control microcomputer (CMC) executes the flow shown in FIG. Hereinafter, this flow will be described.

In step # 36, the signal line (CSAF) is set to "L" level, and in step # 37, the content (check data) of the register (R ₀ ) is set in the serial input / output register (IOR),
In step # 38, the serial input / output operation (SIO) is executed for the AF microcomputer (AMC).

Next, in step # 39, the contents of the register (R ₆ ) (motor rotation amount conversion coefficient K _D or K _D ) are transferred to the serial input / output register (IO
R), and in step # 40, AF microcomputer (AMC)
The serial input / output operation (SIO) is executed to the motor rotation amount conversion coefficient K _D or K _D to the AF microcomputer (AMC).

In step # 41, it is determined whether the AF converter (A) is the AF converter of the old lens system, that is, whether the content of the register (R ₀ ) is the check data 80 _H. If NO, go to step # 48. If YES, the process proceeds to step # 42, and in the subsequent steps # 42 to # 47,
For registers (R ₇ ), (R ₈ ), and (R ₉ ),
The current position data L _P of the converter lens (1) in the case of the old lens system, the position data L ₀ when the converter lens (1) is closest to the camera body (C), and the farthest position from the camera body (C) AF with position data Lmax when
To the microcomputer (AMC) for use.

That is, the current position data L _P is obtained in steps # 42 and # 43, the closest approach position data L ₀ is obtained in steps # 44 and # 45, and the step # 46,
In # 47, the farthest position data Lmax is sent out.

Then, in step # 48, the signal line (CSAF) is set to "H" level, and in step # 49, the interrupt signal is input to the interrupt pin (INT ₁ ), and then the interrupt is applied first. Return to step.

During the operation of reading data from the taking lens system, the AF microcomputer (AMC) does not send an interrupt signal to the interrupt terminal (INT ₁ ) of the control microcomputer (CMC).

The above is the description of the operation of the control microcomputer (CMC). Table 7 shows the relationship between the type of photographic lens system, the presence / absence of focus detection, and open metering and actual aperture metering.

The combination of the underlined old lens and AF converter is the state shown in FIG.

When the AF converter (A) shown in FIG. 4 is mounted alone, the switch (SV) is off and the converter circuit (CEC) is inoperative, so the camera body (C) No data is sent to, and it is treated as unmounted.

The old lens cannot be mounted on the camera body (C) and the new converter because the mounts are different. It is not possible to attach a new lens or new converter to the AF converter (A) because the mount is different.

The AF converter (A) can be installed in the new converter. In this case, when the old lens is attached to the AF converter (A), focus detection and AF mode operation are performed, but when the old lens is not attached, focus detection and AF mode operation are not performed.

If there is a new lens in the new lens system that can detect focus but cannot operate in AF mode,
The new lens is configured so that it can be attached to the AF converter (A), and in addition to the data from the above-mentioned lens, the AF
It may be configured to add data for enabling and disabling AF, to convert AF disable data sent from a lens for which AF is not possible into AF enable data, and send it to the camera body (C). Other data may be converted in the same manner as the new converter.

Further, in order to distinguish such a new lens AF converter, another data is provided so that common data is output together with the old lens AF converter (A) and the new lens AF converter. , May be distinguished from other new lens systems. The check data is set to 88 _H because open metering can be used.

Operation of AF Microcomputer (AMC) Next, the operation of the AF microcomputer (AMC) will be described with reference to the flowchart of FIG.

When the signal line (AFSTA) falls to "L" level, AF
An interrupt signal is input to the interrupt terminal (INTA) of the microcomputer (AMC) for use, and the operation from step S1 is started.

In step S1, the input of the interrupt signal to the interrupt terminal (INTB) is permitted, and in step S2, the CCD (DD) integration operation is started. In step S3, the completion of the integration operation is waited for.

Next, in step S4, a termination check subroutine is executed. This subroutine will be described later.

After the end of this subroutine, the process proceeds to step S5, and the CCD
The data from (DD) is read into the AF microcomputer (AMC) via the interface circuit (IFC). In step S6,
The defocus amount d is calculated based on the read data. The calculation operation for calculating the defocus amount d has already been disclosed in, for example, Japanese Patent Laid-Open No. 59-126517 and is publicly known, so that the description thereof will be omitted.

In step S7, execute the termination check subroutine,
After that, the process proceeds to step S8. In step S8,
Determine whether the signal line (CSLE) is at "L" level.
When it is at "L" level, the control microcomputer (CMC) is reading data from the converter circuit (CEC).
After this reading operation is completed and the signal line (CSLE) becomes "H" level, the process proceeds to step S9.

In step S9, the signal line (DREQ) is set to "L" level, and an interrupt signal is sent to the interrupt terminal (INT ₁ ) of the control microcomputer (CMC). In step S10, the control microcomputer (CMC) waits for the signal line (CSAF) to go to "L" level.

When the signal line (CSAF) goes low, step S1
In step 1, execute serial input / output operation (SIO), and perform step S12.
Then, set the check data 80 _H or 88 _H , which is the contents of the serial input / output register (IOR), in the register (R ₁₀ ).

In step S13, execute the serial input / output operation (SIO) again,
In step S14, the motor rotation amount conversion coefficient K _D or K _D , which is the content of the serial input / output register (IOR), is registered (R ₁₁ )
Set to.

In step S15, it is determined whether the signal line (CSAF) remains at "L" level. If it remains at “L” level,
If it is at "H" level, the process proceeds to step S16.

That is, when the control microcomputer (CMC) determines that it is a new lens system (when the determination in step S15 is NO).
This is because the data transfer is stopped only by transmitting the 2-byte data (80 _H or 88 _H and K _D or K _D ) in steps S11 to S14.

When it is determined that the AF converter (A) in FIG. 4 is selected (when the determination in step S15 is YES), in steps S16 to S20, further 3 bytes of data (L _P , L _O, and Lmax) are added. The data is sent out and the AF microcomputer (AMC) sequentially reads these data (L _P , L _O , Lmax) and sets them in registers (R ₁₂ ), (R ₁₃ ), and (R ₁₄ ), respectively.

As a result, the data set in the registers (R ₁₀ ) to (R ₁₄ ) are as shown in Table 8.

When the AF microcomputer (AMC) finishes reading the lens data from the control microcomputer (CMC), step S22
Then, determine whether the switch (AFS) is set to AF mode or FA mode via the input port (IP ₁₀ ) of the AF microcomputer (AMC). If the FA mode is set, the process proceeds to step S23, and the FA mode subroutine is executed. This subroutine will be described later.

In the case of the system that has the AF enabled / disabled AF data mentioned above, this data is read from the control microcomputer (CMC), and AF enabled / AF disabled data is discriminated after step S22. If there is, it may be configured to move to step S23 and execute the FA mode subroutine.

If it is determined in step S22 that the AF mode is set,
Go to step S24, check data is 80 _H ,
That is, it is determined whether the AF converter (A) is attached. When the AF converter (A) is attached, the process proceeds to step S26, and when the AF converter (A) is not the new lens system, the process proceeds to step S25.

When it is determined in step S24 that the converter is the AF converter (A), in step S25 or step S26,
It is determined whether or not the brightness distribution is such that the defocus amount d can be detected. If the luminance distribution is detectable, the process proceeds to step S28 or step S39, respectively. On the other hand, if the luminance distribution is undetectable, the low contrast scan (hereinafter referred to as low contrast scan) subroutine of step S27 is executed. That is, an operation of searching for a detectable position is performed while moving the converter lens (1) (details will be described later).

The judgment as to whether or not the brightness distribution can be detected has already been made in JP-A-59-140408 and JP-A-60.
Since it is disclosed in Japanese Patent Publication No. 4914 and is publicly known, description thereof will be omitted.

If it is determined in step S24 that the lens system is the new lens system, the process proceeds to step S25, and if it is determined that the brightness distribution can be detected, the process proceeds to step S39. In step S39, based on the defocus amount d calculated in step S6, the focusing lens (AF converter,
Since there are cases of new lenses and new converters, we have decided to use "focusing lenses" for generality. ) To the in-focus position, the rotation amount N of the motor (MO) corresponding to the in-focus movement amount x required to move to the in-focus position is calculated by the calculation of N = d × K _D , and the process proceeds to step S40 to drive the motor. Execute the subroutine. This subroutine will be described later.

For AF converter (A), when judged to be detected in step S26, the process proceeds to step S28, the current position data L _P of the defocus amount d and the converter lens (1), the AF corresponding to the first table microcomputer the address of the look-up table in the ROM of the (AMC), based on the current position data L _P of the defocus amount d and converter lens (1), is moved converter lens (1) to the in-focus position The in-focus movement amount x of the converter lens (1) required for

The lookup table has AF in equations (7) and (8).
The specific numerical value of x when the specific numerical value (l, d) of the converter is input is fixedly stored in each address. That is, for example, a table in which the first table is made finer is stored in the ROM.

Next, in step S29, it is determined whether it is a front pin or a rear pin. If it is the front pin, the process proceeds to step S30, and if it is the back pin, the process proceeds to step S34.

In the case of the front pin, it is necessary to extend the converter lens (1) forward. Therefore, in step S30, even if Kuridaso forward movement amount x focus from the current position, in contact with the farthest position Lmax, determines whether a state not Kuridase to the position of the L _P + x (L _P + X> Lmax).

In this way, when it is determined that the focus is not achieved unless the motor (MO) is driven further than the farthest position Lmax before driving the motor (MO), the process proceeds to step S31, and the motor (M
O) is rotated at a high speed in the direction in which the converter lens (1) is extended (clockwise rotation). Then, in step S32,
Execute the end detection subroutine. This termination detection subroutine will be described later.

When the converter lens (1) is extended to the most separated position Lmax by the operation of the terminal end detection subroutine, the driving of the motor (MO) is stopped, and the front pin display portion (FF) blinks in step S33 (auto focus). No warning).
Then, the process returns to step S2 to perform the next measurement.

On the other hand, when it is determined in step S29 that the rear focus is the front focus instead of the front focus, the process proceeds to step S34, and even if the converter lens (1) is moved backward by the focusing movement amount x, the closest position is determined. the L ₀ abuts determines whether or not Kurikome to the position of the _{L P -x (L P -x <} L 0).

In this way, if it is determined that focusing will not be done unless the motor (MO) is driven in from the closest position prior to driving,
Similar to the case of the front pin, the process proceeds to step S35, and the motor (MO) is rotated at high speed in the direction (counterclockwise rotation) in which the converter lens (1) is retracted. Then, in step S36,
Execute the end detection subroutine.

When the converter lens (1) is moved up to the closest position L ₀ by the operation of the end detection subroutine, the motor (MO)
Stop driving, and in step S37, rear pin display (RF)
Flashes (warning that autofocus is not possible). Then, the process returns to step S2.

As described above, when the front focus display (FF) or the rear focus display (RF) blinks, the photographer cannot confirm that the focus state cannot be achieved only by the autofocus by the autofocus device. You can check. Therefore, by manually operating the operation ring (49) of the interchangeable lens (B), which is the old lens mounted on the AF converter (A), and moving the first optical system (L), the in-focus state can be achieved. Good.

When it is determined in step S30 or step S34 that autofocusing is possible only with the AF converter (A), the process proceeds to step S38 and the converter lens (1)
Motor (MO) required to move the focus movement amount x
The rotation amount N of is calculated by N = x × k _D. Then, the process proceeds to the motor drive subroutine of step S40.

Motor Drive Subroutine Next, the motor drive subroutine will be described with reference to FIG.

In step S45, the flags (LSF) and (ENF) are reset. The flag (LSF) means that the low-conscan operation is executed when it is "1" and it is not executed when it is "0". When the flag (ENF) is "1", the focusing lens hits the infinity position during low-con scan operation, and when it is "0", low-con scan is in progress, or normal focus detection is performed. It means that it is being broken.

The reason why the flags (LSF) and (ENF) are reset in step S45 is to cancel the in-focus detection that may have been impossible in the previous operation.

In step S46, it is determined whether the defocus amount d is in the in-focus area. When it is determined that it is in the in-focus area, the process proceeds to step S47 to display the in-focus state, and then returns to step S2 to execute the next measurement.

On the other hand, when it is determined that the motor rotation amount N is not in the in-focus area, the process proceeds to step S48, and it is determined whether the motor rotation amount N is smaller than the motor rotation amount Nn corresponding to the near focus area (N ≦ Nn). The motor rotation amount Nn corresponding to the near focus region, Nn = dn × K _D or an Nn = xn × k _D. However, dn is a near focus area in units of defocus amount, and xn is a near focus area in units of movement amount of the converter lens (1).

The width of the near focus area is the motor (MO) of any lens.
When the motor (MO) is braked to completely stop the movement of the lens during the high speed rotation of, the width is set so as not to pass the in-focus position.

In step S48, when the motor rotation amount N is in the close-focused area, the process proceeds to step S49, and the near zone flag (NZF) is set to "1". Then, step S50
Then, the calculated motor rotation amount N is preset in the presettable event counter (ECO). Step S
At 51, the motor (MO) is driven and rotated at a low constant speed, and then the process proceeds to step S55. This low speed rotation is controlled by monitoring the pulse from the encoder (ENC).

In step S48, when the motor rotation amount N is not in the close focusing area, the process proceeds to step S52, and the near zone flag (NZF) is reset to "0". Then, step S53
Then, data (N-Nn) obtained by subtracting the rotation amount Nn in the near focus area from the already calculated motor rotation amount N is preset in the presettable event counter (ECO). In step S54, the motor (MO) rotates at high speed, and the process proceeds to step S55 (no speed control is performed).

In step S55, the AF microcomputer (AMC) input terminal (CKI
Input to the interrupt terminal (INTB) of the interrupt signal generated when the content of the presettable event counter (ECO) is decremented to "0" by the pulse input from the encoder (ENC) to N). To allow

Then, the process proceeds to step S56, and it is determined whether or not it is the front pin. If it is the front pin, the process proceeds to step S57, the motor (MO) is rotated to the right, and the converter lens (1)
Is moved in the feeding direction (forward). If it is not the front pin, the process proceeds to step S58, the motor (MO) is rotated leftward, and the converter lens (1) is moved in the retracting direction (rearward).

After rotating the motor (MO) clockwise or counterclockwise, step S5
Go to 9 and execute the end detection subroutine.

Note that the focus lens of the new lens system and the focus lens [converter lens (1)] of the AF converter (A) shown in FIG. 4 have the same moving direction of the converter lens (1) with respect to the same focus shift direction. In some cases, the auto focus device of the present invention deals with this in reverse, but in order to deal with this, the motor (M
The drive mechanism of the focusing lens in each lens is configured such that the rotation direction of O) is the same.

Steps # 37 → # 38 → # 39 → # 40 of Fig. 7 explained above
→ # 41 → # 42 → # 43 → # 44 → # 45 → # 46 → # 47 and the flow of steps S24 → S26 → S28 in FIG. It corresponds to the focal movement amount data conversion means (DMDM).

The defocus amount detecting means (DFD
M) corresponds to the flow of steps S2 → S3 → S4 → S5 → S6 in FIG.

End Detection Subroutine Next, the operation of the end detection subroutine will be described with reference to FIG.

This termination detection subroutine is performed when it is determined in step S30 in FIG. 8 that the converter lens (1) is not focused unless it is further extended beyond the most separated position Lmax, or in step S34, the converter lens (1)
When it is determined that the focus is not achieved unless the position is further revolved beyond the closest position L ₀ , the motor (MO) is rotated at a high speed or is executed in the final step S59 of the motor drive subroutine.

In step S65, a presettable-even controller (EC
O) contents are set in the register (CR ₀ ) and step S66
And wait for a certain time. Then, in step S67, the contents of the presettable event counter (ECO) are stored in the register (C
R ₁ ).

In step S68, it is determined whether the contents of the register (CR ₀ ) and the contents of the register (CR ₁ ) match. If they do not match, it means that the slit plate (46) in the encoder (ENC) is rotating and the focusing lens is moving. In this case, the process proceeds to step S69, and sets the contents of the register (CR ₁₎ in the register (CR _0), the process returns to step S66.

If the contents of the register (CR ₀ ) and the contents of the register (CR ₁ ) match, the slit plate (4
This means that the rotation in 6) has stopped. That is, the motor (MO) is idling when the focusing lens hits the end of the movement (closest position L ₀ or farthest position Lmax for an AF converter; infinity position or closest position for a new lens). Become. In this case, the process proceeds to step S70 and the motor (MO) is stopped. Then, step S71
Then, the flags (LSF) and (ENF) are reset.

The reason why the flags (LSF) and (ENF) are reset in step S71 is to cancel the in-focus detection that may have been impossible in the previous operation.

After step S71, the process returns to step S33 (blinking front pin display) or step S37 (blinking rear pin display) in FIG. Therefore, even if the state of the front focus or the rear focus is detected, a warning is issued that the focus lens cannot be driven to the in-focus position, and the process returns to step S2 to execute the next measurement. To do.

Note that during normal focus adjustment operation, the contents of the presettable event counter (ECO) become "0" due to the pulse from the encoder (ENC) during the operation of steps S65 to S69, and the counter interrupt is generated. Therefore, the process proceeds to the counter interrupt subroutine of FIG.

The flow of steps S29 → S30 → S38 → S40 in FIG. 8 or steps S29 → S34 → S38 → S40, and
The flow of steps S45 → S46 → S48 to S59 in FIG. 9 corresponds to the optical system driving means (LDM) in the configuration of the invention.

Counter Interrupt Subroutine Next, based on FIG. 11, as a result of the converter lens (1) moving by the planned rotation amount N while the motor (MO) is being driven,
Focusing and the result of the presettable event counter (ECO) setting to "0" due to the pulse from the encoder (ENC), or the motor (MO) starts driving from outside the near focus area The operation when a counter interrupt occurs as a result of entering the near-focus area and setting the contents of the presettable event counter (ECO) to "0" by a pulse from the encoder (ENC) will be described.

When the counter interrupts, other interrupts are not permitted. In step S75, enable the input of interrupt signal to the interrupt terminal (INTB), and in step S76, set the motor (MO).
Brake on.

Next, the process proceeds to step S77, and it is determined whether the converter lens (1) has started moving from the near focus region by whether the near zone flag (NZF) is "1". When the movement starts from outside the near focus area, it means that the focusing lens has reached the near focus area, and the near zone flag (NZF) is "0". Therefore, the processing proceeds to step S80, and the near zone is performed. Set the flag (NZF) to "1". Then, the process proceeds to step S81, in which the rotation amount Nn of the near-focus area is set in the presettable event counter (ECO), and then the ninth
The process proceeds to step S51 in the figure, the motor (MO) is driven at a low speed, and the operations after step S51 are executed.

Note that the near zone flag (NZF) is set to "1" in step S80 when the counter is interrupted next (when the in-focus position is reached) and Y in step S77 described below.
This is because the process proceeds to step S78 as ES.

In step S77, the near zone flag (NZF) is set to "1".
If it is determined that the focus lens is moved from the near focus area, in this case, the step
Go to S78 and reset the near zone flag (NZF) to "0".

If the determination in step S77 is YES, the motor (MO) is rotating at a low speed, and therefore the focusing lens stops at the in-focus position by the motor brake in step S76. Therefore, in the following step S79, the focus display section (FM) is turned on, and then the process returns to step S2 to execute the next measurement.

Locon Scan Subroutine Next, the operation of the lowcon scan subroutine will be described with reference to FIG. This low contrast scan subroutine is for making the luminance distribution detectable while moving the focusing lens.

When it is determined that the defocus amount d cannot be detected in steps S25 and S26 in FIG. 8, the process shifts to the low-conscan subroutine in step S27. That is, the process proceeds to step S85, and it is determined whether the flag (LSF) is "1". This flag (LSF) is a flag that is set to "1" during the operation of the low contrast scan.

When the process shifts to the low contrast scan subroutine first, the flag (LSF) is "0", and thus the process proceeds to step S86. In step S86, it is determined whether the flag (ENF) is "1". When the flag (ENF) is set to "1", it means that the operation of the low-conscan has ended and the luminance distribution cannot continue to be detected. When this low-conscan subroutine is entered first Is "0", the process moves to step S87, the motor (MO) is rotated leftward at a high speed, and the converter lens (1) is moved to the closest position L _{0 in the} retracting direction (backward).

Next, in step S88, the contents of the presettable event counter (ECO) are set in the register (CR ₀ ), and in step S89, since the low contrast scan is in progress, the flag (L
After setting SF) to "1", the process returns to step S2.

If it is determined in step S85 that the flag (LSF) is "1", the luminance distribution is defective during the operation of the low contrast scan, and the process does not proceed to step S87 (the low contrast scan operation is performed). (While continuing), immediately return to step S2.

If YES in the determination in step S86, it means that the low-conscan operation is moving from the close position to the infinity position, or the low-con scan operation continues, but the brightness distribution continues. Is not defective, the process does not move to step S87 (the low-conscan is continued or the low-con scan operation is not performed), and the process immediately returns to step S2.

End Check Subroutine Next, the operation of the end check subroutine will be described with reference to FIG.

In the termination check subroutine of step S4 or step S7 in FIG. 8, the flag (LS
Judge whether F) is set to "1".
In the case of "0", the low contrast scan operation is not in progress, and therefore, the process proceeds to step S5 or step S8 in FIG.

On the other hand, if the flag (LSF) is "1", it means that the low-conscan operation is in progress, so the routine proceeds to step S91, where the contents of the presettable event counter (ECO) are stored in the register (C
R ₁ ).

Then, in step S92, it is determined whether the contents of the register (CR ₀ ) and the register (CR ₁ ) match. In this case, the register (CR ₀ ) has the contents of the presettable event counter (ECO) set in the previous low-conscan subroutine or termination check subroutine.

If the contents of the register (CR ₀ ) and the contents of the register (CR ₁ ) do not match in step S92, it means that the focusing lens is moving. In this case, the process proceeds to step S97 and the presettable event counter (E
After setting the contents of CO) in the register (CR ₀ ), the process proceeds to step S5 or step S8 in FIG.

On the other hand, if the contents of the register (CR ₀ ) and the contents of the register (CR ₁ ) match, it means that the focusing lens has stopped at the closest position or the infinity position and the motor (MO) is idling. Therefore, the process moves to step S93.
In step S93, after stopping the motor (MO), step S93
At 94, it is determined whether the flag (ENF) is set to "1".

This flag (ENF) is set to "1" when the focusing lens hits the closest position during low contrast scan operation.
This is the flag that is set to. In step S94,
If the flag (ENF) is set to "1", it means that the detection state was not reached while moving the focusing lens to the position corresponding to the infinity position after hitting the closest position. In this case, the process proceeds to step S98.

In step S98, the flag (LSF) is set to "0", and in step S99, the front pin display portion (FF) and the rear pin display portion (R
After flashing F) at the same time to give a warning that autofocus is not possible, the process returns to step S2.

On the other hand, if the flag (ENF) is "0" in step S94, it means that the closest position has been hit, and in this case, the process proceeds to step S95. In step S95, the flag (ENF) is set to "1", and in step S96, the motor (M
O) is reversed and the focusing lens is moved toward the infinity position. Then, in step S97, the contents of the presettable event counter (ECO) are stored in the register (C
After setting to R ₀ ), the process proceeds to step S5 or step S8 in FIG.

FA Mode Subroutine Next, the operation of the FA mode subroutine will be described with reference to FIG.

In step S101, the flags (LSF) and (ENF) are reset to handle switching from the AF mode to the FA mode.

In step S102, it is determined whether the defocus amount d can be measured. If the measurement is impossible, step S103
To the front pin display (FF) and rear pin display (R
After making F) blink, return to step S2. If the measurement is possible, the process proceeds to step S104, and it is determined whether or not it is in focus.

If it is in focus, the process proceeds to step S105, the focus display section (FM) is turned on, and the process returns to step S2.

On the other hand, if it is not in focus, the process proceeds to step S106, and it is determined whether or not it is the front focus. If it is the front pin, step S107
Proceeds to, whether the fourth diagram of AF converter (A) is mounted, the check data is judged by whether the 80 _H. If it is attached, the process proceeds to step S108, and the front pin display portion (FF) blinks. If not attached, the process proceeds to step S109, and the front pin display portion (FF) is turned on. Then, after the front pin display portion (FF) blinks or lights up, the process returns to step S2.

In step S106, when it is judged not to be the front focus, because it is the rear focus, the process proceeds to step S110, whether the AF converter (A) is mounted, the check data is judged by whether it is 80 _H . If the AF converter (A) is attached, the process proceeds to step S111, and the rear pin display portion (RF) blinks. If it is not attached, the process proceeds to step S112, and the rear pin display (R
Turn on F). Then, after the rear pin display portion (RF) blinks or lights up, the process returns to step S2.

INTB interrupt subroutine Next, the interrupt pin (INTB) in the AF microcomputer (AMC)
The interrupt subroutine for will be described with reference to the flowchart of FIG.

The signal line (AFSTP) from the control microcomputer (CMC) is "L"
When it falls to the level, the AF microcomputer (AMC) executes the operation based on the interrupt signal to the interrupt pin (INTB).

First, in step S120, the motor (MO) is stopped, and in step S121, the front pin display portion (FF), the rear pin display portion (RF), and the focus display portion (FM) are turned off. Then, step S122
Flag (LSF), (ENF) and near zone flag (NZ
F) is reset. Furthermore, in step S123, operation based on the interrupt signal to the interrupt terminal (INTA) is enabled,
Stop the operation of the AF microcomputer (AMC).

Another FA Mode Subroutine Next, an FA mode subroutine different from the FA mode subroutine shown in FIG. 14 will be described with reference to FIG.

Although not shown in FIG. 16, it has the same flow as steps S101 to S105 in FIG. When it is determined that not focus at step S104, the process proceeds to step S130, whether the AF converter (A) is mounted, the check data is judged by whether the 80 _H. When it is mounted, the process proceeds to step S131, the defocus amount d, based on the current position data L _P converter lens (1), if moving the converter lens (1) to the in-focus position focus movement The quantity x is calculated by using the look-up table of the ROM in the AF microcomputer (AMC) (same as step S28 in FIG. 8).

Then, in step S132, it is determined whether or not it is the front pin.
If it is the front pin, the process proceeds to step S133, and if it is the back pin, the process proceeds to step S136.

In step S133, set the converter lens (1) to the current position.
It is determined whether or not it can be brought into a focused state by moving a predetermined focusing movement amount x from L _P (L _P + x> Lmax).
This is the same as step S30 in FIG.

If the in-focus state is not achieved even if the converter lens (1) is moved to the farthest position Lmax, the process proceeds to step S135, the front pin display portion (FF) blinks, and if the in-focus state is achieved, the step S134 is performed. , And the front pin display (FF) lights up. Then, after blinking or lighting, the process returns to step S2.

If it is the rear pin in step S132, step S136
Then, it is determined whether or not the in-focus state is achieved even if the converter lens (1) is moved to the closest position L ₀ (L _P −x <L ₀ ). This is the same as step S34 in FIG.

If the in-focus state is not achieved even if the converter lens (1) is moved to the closest position L ₀ , the process proceeds to step S138,
When the rear pin display (RF) blinks and the subject is in focus,
The process moves to step S137, and the rear pin display section (RF) is turned on. Then, after blinking or lighting, the process returns to step S2.

If it is determined in step S130 that the AF converter (A) is not attached (check data is not 80 _H ), it is a new lens and new converter.
Go to and determine whether it is the front pin. For the front pin,
Go to step S140, light the front pin display (FF),
In the case of the rear pin, the process proceeds to step S141, the rear pin display portion (RF) is turned on, and the process returns to step S2.

In the embodiment of the present invention described above, the current position data L _P of the converter lens (1) and the focus movement amount x from the defocus amount d to the focus position are obtained, and then the mechanical distance from the converter lens (1) is determined. The amount of rotation N (= k _D × x) of the motor (MO) is calculated based on the conversion coefficient k _{D of the} system.

However, as shown in Table 1, even if the current position data L _P changes for the same defocus amount db, the focus movement amount x
Changes little. From this fact, when the converter lens (1) is attached, the focusing movement amount x is obtained from the defocus amount d only by using the look-up table in the AF microcomputer (AMC), and the converter lens The motor rotation amount N may be obtained based on the conversion coefficient k _D from (1).

Further, the data of the defocus amount d is configured to be transferred to the converter, and in the converter, the conversion coefficient K _{D including} both the optical system element and the mechanical system element as the address data is used for the AF from the defocus amount d. Alternatively, the motor rotation amount N may be obtained by transferring the data to the microcomputer (AMC), and the AF microcomputer (AMC) calculates N = d × K _D as in the case of a normal lens.

In the case of a system in which the lens control unit is provided on the lens and converter sides, the defocus amount d is transferred from the camera body (C) to the converter, and thereafter, on the camera body (C) side of the above embodiment. The motor rotation amount N may be obtained by the same process as the process of (1), and the motor (MO) in the AF converter may be rotated by this rotation amount N.

Alternatively, in such a system, the pulse for monitoring the lens movement is converted from the converter, the lens to the camera body (C).
In the case of the system that is sent to the device, the pulse count value (focus movement amount x) is detected and converted into the defocus amount d, and this data is compared with the detected defocus amount d, A stop signal of the motor (MO) may be sent from the camera body (C) to the converter, or the defocus amount d may be converted into the focus movement amount x, and this data may be compared with the count value. Good.

Further, in the above-mentioned embodiment, the information of the open aperture value or the set aperture value of the interchangeable lens (B) mounted in front of the converter is transmitted as it is to the camera body (C) as AFA _VO , but the converter is focused. If the teleconverter changes the distance, it is necessary to change the magnification. For example, if it is 2 times, it is 1 step, if it is 1.4 times, it is 0.5 step, and so on.

As a development of the present invention, without calculating the in-focus movement amount x from the defocus amount d, data of a fixed conversion coefficient K _D is sent out from the converter, and N = d as in a normal interchangeable lens. It is also conceivable to drive the lens in order to obtain × K _D. In this case, the lens may cause hunting near the in-focus position, and the in-focus speed may slightly decrease.
If it can be confirmed that there is no problem in practical use, adopting this method has the advantage that the cost of the converter can be reduced and the camera body does not need to be provided with a dedicated operation for the converter.

Effects According to the present invention, the following effects are exhibited.

(A) The defocus amount / focus movement amount data conversion means is
A certain one-to-one correspondence relationship is provided between the focusing movement amount and the defocus amount of the second optical system having a non-linear relationship, and the first defocus amount is obtained by converting the defocus amount. The in-focus movement amount of the two optical systems can be a movement amount at which the defocus amount becomes substantially zero.

The defocus amount / focus movement amount data conversion unit converts the defocus amount thus obtained into the optimum focus movement amount data of the second optical system so that the defocus amount becomes substantially zero. Convert to.

Then, since the optical system driving means drives and controls the second optical system based on the focusing movement amount data obtained in advance before the actual focusing movement of the second optical system, in the actual focusing movement, The movement of the second optical system can be controlled so that the defocus amount becomes substantially zero.

That is, since the focus movement amount data is obtained in advance before the actual focus movement of the second optical system, the automatic focus adjustment operation can be made to function extremely effectively. Therefore, it is possible to surely prevent the occurrence of a problem such as hunting in the vicinity of the in-focus position of the second optical system as in the case of the conventional feedback control, and perform the autofocus at a high speed and high accuracy. You can

(B) In addition, the function of the defocus amount detecting means originally provided in the autofocus device for obtaining the defocus amount can be effectively utilized without waste in improving the focusing accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIGS. 2 and 3 are explanatory views of the principle of the present invention, FIGS. 4 to 15 are related to an embodiment of the present invention, and FIG. FIG. 5 is a block diagram showing the structure of the microprocessor, FIG. 6 is a flowchart showing the operation of the control microcomputer, FIG. 7 is a flowchart of the INT ₁ interrupt subroutine, and FIG. 8 is AF. 9 is a flowchart showing the operation of the microcomputer for a motor, FIG. 9 is a flowchart of a motor drive subroutine, FIG. 10 is a flowchart of an end detection subroutine, FIG. 11 is a flowchart of a counter interrupt subroutine, and FIG. 12 is a flowchart of a low-conscan subroutine. , Fig. 13 is the flow chart of the termination check subroutine, Fig. 14 is the flow chart of the FA mode subroutine, and Fig. 15 is the INTB interrupt service. Flowchart of a routine, FIG. 16 is a flowchart of another FA mode subroutine. (A) …… AF converter (B) …… Interchangeable lens (L) …… First optical system (CL) …… Second optical system (1) …… Converter lens (DFDM) …… Defocus amount detection means ( DMDM) …… Defocus amount / movement amount data conversion means (LDM) …… Optical system driving means (PDOM) …… Position data output means (DD) …… CCD (42) …… Light receiving part (CMC) …… Control Microcomputer (AMC) …… AF microcomputer (MC) …… Motor control circuit (MO) …… Motor (14) …… Motor (LP) …… Code plate (18) …… Code plate (SE) …… Selector ( PS) ... Parallel-serial conversion circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page Examiner Shujiro Yokobayashi (56) References JP 58-168023 (JP, A)

Claims (2)

[Claims] 1. Defocus amount detecting means for detecting a defocus amount by a first optical system and a second optical system arranged on the film surface side of the first optical system, and a position of the second optical system. With reference to the defocus amount, defocus amount / focus moving amount data conversion means for converting the defocus amount into data corresponding to the focusing moving amount of the second optical system which changes non-linearly with respect to the defocus amount, An autofocus device comprising: an optical system drive unit that moves the second optical system based on the focus movement amount data from the defocus amount / focus movement amount data conversion unit. 2. The first optical system is an optical system provided in an interchangeable lens, and the second optical system is an optical system provided in an AF converter mounted on the film surface side of the interchangeable lens. The autofocus device according to claim 1, wherein the autofocus device is provided.