JPH03249717A - Automatic focus adjusting device for camera - Google Patents

Abstract

PURPOSE:To convert a defocusing quantity into a driving quantity with simple constitution by finding information of a deviation in the focusing point of a focus lens group in the direction of the optical axis first and then finding the driving quantity of the focus lens group when the defocusing quantity is converted into the driving quantity of the focus lens group. CONSTITUTION:This device is provided with an information detecting means 1 which detects the quantity of the deviation between the image formation plane of subject light passed through a photographic lens 5 and a film surface and the direction of the deviation, an extension quantity detecting means 4 which detects the quantity of the extension of the focus lens group of the photographic lens from a reference position, and a focus group deviation information determining means 2 which determines the quantity and direction of the deviation in the extension quantity in the optical axis direction about the focusing position of the focus group according to the deviation information. Then an arithmetic means 3 determines a driving quantity required for the focusing of the focus group from the output of the extension quantity detecting means 4 and the output of the focus group deviation information determining means 2. Consequently, the deviation in focus can be converted into the driving quantity with the simple constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic focus adjustment device for a camera, specifically an automatic focus adjustment device for a photographic lens of a camera, etc.
The present invention relates to an automatic focusing device for a lens in which the amount of movement of a focusing optical system (focusing lens group) in the optical axis direction and the amount of driving of a driving member for a focusing operation have a non-linear relationship.

[Prior Art] A lens in which the amount of movement of a focusing optical system in the optical axis direction and the amount of driving of a focusing lens group (hereinafter referred to as the focusing group) for driving the focusing optical system have a non-linear relationship. For example, there is a zoom lens having a varifocal optical system in which the amount of extension of the focusing optical system in the optical axis direction from an infinity position corresponding to the same subject distance differs depending on the set focal length.

In such an optical system, the focal plane shifts as the focal length changes due to zooming for the same subject distance. In order to correct this focus shift, the amount of extension of the focusing optical system in the optical axis direction must be changed to an appropriate amount during zooming. As a driving method for the above-mentioned optical system that corrects the movement of the focus due to zooming, the necessary extension amount of the focusing optical system in the optical axis direction, which varies depending on the focal length, is approximated by a single function, and the focal length is adjusted to the focal length. A metric ring has been proposed in which the range of use of this function is changed accordingly.

However, it is difficult to directly adjust the driving amount of such a lens based on the out-of-focus. In other words, when focusing using a distance cam, the rotation angle of the distance ring and the amount of movement of the focusing optical system in the optical axis direction are not in a proportional relationship.
The focus shift could not be converted into the rotation angle of the distance ring, that is, the amount of drive for focus adjustment of the focusing optical system, or the angle could not be converted. Furthermore, the range of use of the function changes depending on the amount of lens extension or zooming, which makes it increasingly difficult to convert out-of-focus into the amount of drive of the focus group for focus adjustment.

Therefore, in order to eliminate such drawbacks, we created a data table in a storage means that stores the drive amount for focus adjustment necessary for focusing based on each focal length information, each extension amount, and out-of-focus information (defocus amount). Japanese Unexamined Patent Publication No. 64-59311 proposes a method in which focus adjustment is made possible by storing the values as follows and setting the drive amount according to each detected value.

[Problems to be Solved by the Invention] However, the method disclosed in Japanese Unexamined Patent Publication No. 64-59311 requires storage means with a huge storage capacity, which is difficult to implement at present.

In view of this situation, it is an object of the present invention to provide a method for focusing with a simple configuration in an optical system in which the amount of drive of the focus group and the amount of movement of the focus group in the optical axis direction have a non-linear relationship. To provide an automatic focus adjustment device for a camera that can convert blurring into a driving amount.

[Means and effects for solving the problems] FIGS. 1A to 1C show the concept of the present invention. As shown in FIG. 1A, the basic configuration of the automatic focusing device for a camera according to the present invention detects deviation information for detecting the amount and direction of deviation between the imaging plane of the subject light that has passed through the photographic lens 5 and the film plane. means 1, an extension amount detection means 4 for detecting the extension amount of the focus lens group of the photographing lens 5 from the reference position, and a deviation amount of the extension amount of the focus lens group in the optical axis direction from the in-focus position based on the deviation information. and a focus group deviation information determining means 2 for determining the direction of deviation, and an output of the feeding amount detecting means 4 and the focus group deviation information determining means 2.
The present invention is characterized by comprising a calculation means 3 for determining the amount of drive necessary for focusing the focus group from the output of the focus group.

[Function] This automatic focus adjustment device adjusts the direction of deviation in the optical axis direction between the imaging plane of the subject light that has passed through the photographic lens 5 and the film plane.
The focus is determined by calculating the deviation between the in-focus position of the focus group of the photographing lens 5 in the optical axis direction and the current position based on the output signal of the deviation information detection means 1 that detects the amount of deviation. The group deviation information determining means 2 converts the information into a signal indicating the direction and amount of deviation of the focus group from the in-focus point in the optical axis direction. Further, the focus group drive amount calculating means 3 determines the drive amount of the focus group necessary for focusing from the current position of the focus group and information on the direction and amount of shift of the focus group in the optical axis direction. and outputs it as the focus group drive amount. That is, when converting the focus shift into the drive amount of the focus group, first, information on the shift in the optical axis direction of the in-focus point of the focus group is obtained, and then the drive amount of the focus group is obtained.

In addition, in a zoom lens with a varifocal optical system, the amount of extension of the focusing optical system in the optical axis direction from the infinity position corresponding to the same subject distance, or the set focal length, In order to correct the amount of extension in the axial direction, the necessary extension amount of the focusing optical system in the optical axis direction, which varies depending on the focal length, is approximated by a single function, and the range of use of this function is changed depending on the focal length. Regarding the above, as shown in FIG. 1B, a focal length information detection means 6 is provided for detecting information from the focal length adjustment optical system 5a, and based on the set focal length information output from the focal length information detection means 6, the above focus group shift information is determined. In determining means 2,
The output signal of the deviation information detection means 1 is converted into a signal indicating the direction and amount of deviation of the focus group in the optical axis direction according to the focal length information set above.

In addition, in the case of the above-mentioned zoom lens, as shown in FIG. 1C, the focal length information detection means 6 is used similarly to FIG.
Based on the set focal length information that is the output,
In the focus group drive amount calculation means 3, the direction and amount of deviation of the focus group in the optical axis direction are determined according to the set focal length information and the current extension position signal of the focus group from the extension amount detection means 4. Converts a signal indicating the focus group drive amount to a focus group drive amount.

Furthermore, regarding the formula (function) that determines the shape of the distance cam of a zoom lens as described above, the relationship between the distance of the subject and the amount of extension of the focusing optical system in the optical axis direction with respect to that distance is well expressed as a first-order hyperbolic function. Since it can be approximated, the error will be smaller if it is set to a hyperbolic function. In particular, the formula for the distance cam is θ-0 at the wide end of the lens, and θ at the close-up and telephoto directions.
is positive, and the lift amount of the cam is Z, A, and -Bo are constants of the distance cam formula, then Z-Bo/ (Ao 10) or Z-B / (A + θ) - Bo/A.

By setting it to 0, the calculation in the focus group drive amount calculating means 3 can be easily and accurately calculated.

[Example] Hereinafter, an example will be described in which the present invention is applied to an interchangeable lens camera having an AF function and disclosed in Japanese Patent Application No. 60-275251.

FIG. 2 is an overall block diagram mainly showing the power supply of the camera system to which the present invention is applied. The voltage vcc of the power supply battery 11 becomes DC/Vcc when the power switch 12 is closed.
The voltage is boosted by the DC converter 13, and the voltage between the lines DI is set to a constant voltage vDD of 0° 1. Main CPU 14 between lines no and p,
Bipolar ■Circuit 15. Bipolar 1 circuit 16, strobe control circuit 17. Lens specific data circuit 18a,
Lens fixed data circuit 18b, data pack circuit 19
are connected, and the power supply control of the bipolar circuit 15 is performed by a signal from the power control circuit of the main CPU, and the power supply control of the Pipo 91 circuit 16 to data pack circuit 19 is controlled by the power control from the bipolar circuit 15. This is done by a signal.

Focus sensor 20. A/D converter 21. AF CPU
The AF block consisting of 22 is a power supply control transistor 2
3 via line io, 1. The main CPU 14 controls the power supply to this AF block.
This is done by controlling the transistor 23 on and off using a signal from the AF power control circuit.

The AP CPU 22 is a circuit for performing AF algorithm calculations, and is connected to an AF display circuit 24 that displays in-focus/out-of-focus status. The main CPU 14 is a circuit for controlling sequences of the entire camera such as winding, rewinding, and exposure sequences, and is connected to a display circuit 25 for displaying other than the above-mentioned focus display. Bipolar ■Circuit 1
Reference numeral 5 denotes a circuit including various drivers necessary for camera sequences such as winding and rewinding motor control, lens drive, and shutter control, and is connected to an AF motor drive circuit 26, an AF auxiliary light circuit 27, and the like. The bipolar 1 circuit 16 is a circuit mainly responsible for photometry, and has a photometry element 28. The strobe control circuit 17 is for controlling the light emission of a built-in or external strobe 29. The lens-specific data circuit 18a is a circuit that stores unique lens data necessary for AF, photometry, and other camera control, which differs for each interchangeable lens. Among the lens data contained in this lens-specific data circuit 18a, the data necessary for AF includes the lens magnification coefficient (optimal AF coefficient), macro identification signal, absolute distance coefficients a, b,
Power focus duty coefficient 1 coefficient 1 number rate coefficient accuracy threshold ETh.

These include the direction of lens movement and the aperture F value. The storage section from which these data are read is changed according to the information on the focal length that has been set, and the data is switched as necessary. The lens fixed data circuit 18b is a circuit that stores data necessary for fixed calculations that do not differ for each interchangeable lens. Furthermore, the data of the lens specific data circuit 18a and the lens fixed data circuit 18b are stored in the main CP in the camera.
It may also be stored in a memory such as U14 or AFFCPU22.

The bipolar ■ circuit 15 monitors the state of the power supply voltage vDD, and when the power supply voltage drops below the specified voltage, it sends a system reset signal to the main CPU 14 to supply power to the bipolar ■ circuit 15 to data pack circuit 19, and Focus sensor 20° A/D converter 21 and A
The power supply to the AF block consisting of the FFCPU 22 is cut off. Power is supplied to the main CPU 14 even if the voltage is below the specified voltage.

FIG. 3 is a system diagram showing the transmission and reception of signals centered on the AF block. The AFFC CPU 22 and the main CPU 14 transmit and receive data through a serial communication line, and the direction of the communication is controlled by a serial control line. The content of this communication is
These are unique lens data in the lens unique data circuit 18a and absolute distance information. Also, from the main CPU 14
The camera mode (AF single mode/AF sequence mode/power focus (hereinafter referred to as P
(abbreviated as F) mode/other mode) information is decoded through the model line. Furthermore, main C
AFENA (AF
The AFFC enable) signal is a signal that controls the start and stop of each AF and PF mode.
An EOFAF (end of AF) signal sent from the PU 22 to the main CPU 14 is a signal that is issued at the end of the operation in the AF or PF mode, and is a signal that permits transition to the exposure sequence.

In addition, the bipolar circuit 15 decodes the AF motor control line signal from the AFFC CPU 22, and
Drives the F motor drive circuit 26. The AF motor (lens drive motor) is driven by the output of the AF motor drive circuit 26.
31 rotates, slits 32 provided at equal intervals in the rotating member of the lens barrel rotate, and a photo interrupter 33 is formed in which a light emitting part 33g and a light receiving part 33b are disposed facing each other across the path of the slit 32. Count the slits 32. That is, the slit 32 and the photo interrupter 33
constitutes the lens movement amount detection section 34, and the address signal (count signal of the slit 32) emitted from the movement amount detection section 34 is waveform-shaped and taken into the AFFC CPU 22.

The sub lamp (hereinafter abbreviated as S lamp) signal sent from the AF1#CPU 22 to the bipolar circuit 15 is the AF signal.
A signal controlling the auxiliary open circuit 27 turns on the S lamp 27a when the subject is in low light (low brightness) and low contrast.

The AFF indicator circuit 24 connected to the AFFC CPU 22 includes a focus display LED (light emitting diode) 2 that lights up when the focus is focused.
4a and an LED 2 for displaying failure to focus, which lights up when it is impossible to focus.
4b. Note that this AFFCPU 22 includes a clock oscillator 35. A reset capacitor 36 is connected.

Further, the AF CPU 22 and the A/D converter 21 exchange data via a pass line, and the direction of the data transmission is controlled by a pass line control signal. Then, a sensor switching signal and a system clock signal are sent from the AFFCPU 22 to the A/D converter 21. The A/D converter 21 is, for example, a C
A CCD drive clock signal and a CCD control signal are sent to the focus sensor 20 consisting of a CD, and the focus sensor 20
Read the D output and display the read analog value on the CCD.
The output is digitally converted and sent to the AFFC CPU 22.

Next, a photographic lens optical system that can be attached to a camera having an automatic focus adjustment device of the present invention will be explained with reference to FIG. This photographic lens optical system may be fixed to the camera body, or may be replaceable. Further, the optical system is not limited to the one described in this embodiment, and any lens for photographing a camera may be used.

In this photographic lens optical system, the amount of extension of the focusing optical system in the optical axis direction from the infinity position corresponding to the same subject distance is
The zoom lens consists of five groups that differ depending on the set focal length. That is, the lens Ll~
The first group consists of L3.

The second group consists of L4 to L7, and the third group consists of L8 to Llo.
A fourth group consisting of groups Ll, ~L14 and Ll,.

It is composed of a fifth group lens optical system consisting of lens L16, and the state shown in FIG. 11 shows the state at the telephoto end, which has the maximum focal length.

This zoom lens has a focal length of 131.5044 on the telephoto side.
It is a grave, and the wide side is 36.2932■1.

The following Table 2 shows the focal length, principal point position, and
This shows data on group thickness.

Table (Configuration of each group [mml)] This zoom lens optical system allows the first
The position of the fourth group lens changes from the group lens, and the fifth group lens is fixed so as not to move. Also, the change in the spacing between each lens group is not constant, and the changing spacing is
As shown in FIG. 11, the distance between the first and second groups is Dl, the second
- 3rd group interval is D2, 3rd-4th group interval is D3, 4th-
Table 3 shows the interval data of each group for each focal length, assuming that the interval between the fifth groups is D4.

Below, in the margin, data on the amount of zoom operation is also recorded in Table 3. This zoom operation amount is the operation amount (rotation amount) of the zoom ring for zooming this lens. The total operating amount of the zoom ring of this zoom lens from wide to telephoto is 73.5 degrees. The zoom operation amounts in Table 3 are expressed based on wide angle. By operating the zoom ring, the position of the optical system is changed to achieve the focal length shown in the table. This focal length is at infinity.

Further, focus adjustment of this lens is performed by moving the first group and the second group by the same amount along the optical axis. Table 4 shows the amount of extension of the focusing optical system for each focal length shown in Table 3, depending on the subject distance.

As shown in Table 4 below, the subject distance is 1.5 mm from infinity.
It is 2 m. If the closest distance is 1.2 m, the distance is 0.
The payout amount is 58,934 ms, while in tele it is 2
．． A feedout amount of 86037 ms is required.

That is, in this zoom lens, the amount of extension of the focusing optical system in the optical axis direction corresponding to the same subject distance differs depending on the focal length that changes due to the zooming operation. As a result, zooming and focus movement also occurs. For this reason, the zooming focus movement is corrected by approximating the amount of extension that varies depending on the focal length with a single function, and changing the usage range of this function according to the set focal length.

The distance cam function used for this expansion is θ-0 at the wide end of the lens, θ is positive in the close-up direction and telephoto direction, and A o
” If BO is a constant of the above distance cam function, the function value Z(θ) when θ is Z(θ)-B/(A+θ)-Bo/A.

0 ・・・・・・・・・(1) The constant A o ” B o is optimized to eliminate zooming focus movement.For optimization, the subject distance for each focal length is (1, 2m), the amount of change in the usage range of the above function (7L5 degrees) according to the focal length, and the usage range of the above function (36, 5 degrees) according to the subject distance. 75 degrees) is used.In other words, θ corresponding to infinity for wide is 0 degrees, 38.75 degrees for close range of 1.2 m, θ corresponding to infinity for tele is 73.5 degrees, At the closest distance of 1.2 m to the telephoto, θ is 110.25 degrees.At this time, the constant of the optimized distance cam function is Ao--180,877879 (angular unit system) Bo--
320,2401813 (angular unit system). 12th
The figure shows the shape based on this distance cam function. The solid curved line is the shape of the distance cam. The O mark on the line is the delivery position at a close distance of 1.2 m at each focal length. The values indicated by XA and XB in the figure are distance cam constants Ao and B. It is. Further, the values indicated by the sS and /T boxes in the figure are the sum of squared errors and the average value of the errors, respectively. In this way, according to the distance cam determined using the above method, the deviation in the amount of extension of the focusing optical system due to zooming when the subject distance is 1.2 m is 0.0 on average.
It will be about 0001 mm.

Also, the drive pulse actually used to drive this lens system is 1408.4 for the distance cam angle 3B, 75 degrees.
Pulse. In the unit system using this pulse, the constant A o SB O of the above optimized distance cam function is Ao--8158,698050 (drive pulse unit system)
B, --12255,396077 (drive pulse unit system).

Next, the data of the focus shift according to the subject distance at each focal length (36, 29 (2 to 131.5044) shown in Table 3 above is listed and shown in Table 5 below as a defocus table. The subject distance is
Infinity (indicated as 99999.99mm in the table), 8000mm, 6000mm, 4000mm
, 3000mm.

They are 2000mm, 51600mm, and 1200mm.

The horizontal axis represents the lens extension position according to each subject distance, and the vertical axis represents the distance of the subject from the lens.

Figures 13 and 14 show wide (focal length B6.293 mm) and tele (focal length B 131.50 mm), respectively.
4mm), as shown in Table 5 above, and the amount of movement (L) of the focus group necessary to move the focus group and bring it into focus when this focus deviation (d) occurs.
) is shown.

In this graph, the circles indicate the out-of-focus data shown in Table 5 above and the amount of focus group movement necessary for focusing. The solid line shows the relationship between this focus shift (d) and the amount of focus group extension (L) necessary for focusing, as shown in (d) and (
L-(Bl-(A-B/(A+d)l+(C-
di......(2) It is expressed by the following approximate expression. The error between this approximation formula and the actually required amount of feed is 0.0001 mm or less for both overshoot and undershoot. For telephoto, both overshoot and undershoot are about 0.001 mm.

Optimized AF coefficients A and B for each focal length.

C is shown in Table 6.

Optimal AF coefficient table (Focus deviation [mml Focus group movement amount) Next, an algorithm for converting the focus deviation into a driving amount for focusing the focus group will be explained with reference to FIG. 15.

This part corresponds to the focus group shift information determining means 2 in FIG.
This corresponds to the focus group drive amount calculation means 3.

First, focus shift information (d) from the shift information detection means 1 that detects the direction and amount of focus shift is converted to the focal point detected by the focal length detection means 9 in the optimal AF calculation section 7 (focus group shift information determination section). Optimal AF coefficients A, B, and C in the unique data storage circuit section 18a of the lens suitable for distance information
is converted into the movement jl (L) in the optical axis direction necessary for focusing the focus group. The unit of the focus shift information (d) is [mm], and the unit of the required movement amount of the focus group is [m].
m], then (L) can be found using the coefficients in Table 6 above and equation (2) above.

Thereafter, in the distance ring rotation amount calculation section (focus group drive amount calculation means) 8, information on the amount of movement in the optical axis direction necessary for focusing the focus group is stored in the unique data storage circuit section 18a of the lens, or Distance cam function constant A o −B o written as an immediate value in the calculation program
and the distance cam function, the rotation amount of the distance ring for AF (
(focus group drive amount). The calculation formula at this time is as shown in Fig. 16: Sl: rotation amount of the distance cam due to zooming S2: amount of use of the distance cam for extending the lens during distance measurement P: amount of distance ring used for AF Rotation amount L: Amount of movement in the optical axis direction necessary for focusing the focus group xO: Total lift amount of the distance cam at the expected focus position xi:
Distance cam lift amount x2 due to S1: Assuming the distance cam lift amount due to S2, L-xo - (xl+x2) Also, from the distance cam function formula (1), x O-B / (A o + S 1 + S 2
10P) BoZA.

x 1-B / (A o + S 1 ) Bo
/A.

x2+xl-B / (Ao+S1+52)BoZA
.

,',L-B/(Ao+S1+S2+P)B/
(Ao+81+82),',P-B/(L+(Bo/(Ao+51+32)
)))(Ao+S1+82) An arithmetic expression for determining the amount of rotation of the distance ring necessary for focusing for AF is derived.

The distance cam formula is 2(θ)− instead of the above formula (1).
Similar results can be obtained using B/(Ao+θ).

The amount of rotation of the distance cam due to zooming (Sl) above is the zoom operation amount shown in FIG. 12 above. This may be retrieved from the unique data storage section of the lens depending on the focal length information as shown in FIG. 15, or if the focal length information to be detected is based on the amount of rotation of the distance cam, It may be obtained as is or by calculation.

In order to express the angle in a pulse unit system that indicates the position of the focus group, the data in Table 3 requires the number of pulses per unit rotation angle (1406.4 pulses/36.75 degrees in this example).
All you have to do is multiply by

Since the optical system of this embodiment is a zoom lens, focal length information is required for calculation.

In particular, it is a zoom lens in which the amount of extension of the focus group differs depending on the focal length depending on the subject at the same distance.
Since a mechanism for correcting this characteristic is incorporated, values corresponding to the focal length and the amount of extension of the focus group are required for the coefficients and data for calculation. In this way, the calculation in this part can be set according to the characteristics of each lens.

The important thing is that the information on the out-of-focus information is used to calculate the drive amount of the focus group necessary for focusing.

Next, we will explain the algorithm for calculating the absolute distance of the subject you are trying to focus on.

First, from the signal from the focus group drive amount calculation means mentioned above and the signal of the extension position where the focus group is currently stopped, calculate the extension amount (x) of the focus group from the reference position to achieve the ideal focusing state. demand.

As described above, in this embodiment, the signal from the focus group drive amount calculation means as the deviation between the focus extension position of the focus group and the current extension position, and the reference position where the focus group is currently stopped (in this embodiment Using the signal of the extension position from the infinity position), the amount of extension from the reference position of the focus group that ideally focuses on the subject is calculated predictably, and the absolute distance of the subject is determined using that value.

Next, a flowchart of the program operation of the microcomputer centered on the AF block shown in FIG. 3 of the camera having the automatic focus adjustment device of the present invention will be explained. The AF block is connected to the main CP as shown in Figure 2.
By activating the AF power control circuit U14, the transistor 23 is turned on and the power supply voltage V
DD is supplied, thereby beginning execution of the power-on reset routine shown in FIG.

When this power-on reset routine is started, first, the AF block drive circuit is initialized in the <I10 initialization> subroutine. Specifically, the AF display circuit 24° AF motor drive circuit 26
and turning off the AF auxiliary optical circuit 27, etc. and the main CPU
Initialization of the serial communication line with 14 is performed.

Next, in the ``Damn Read'' subroutine, the main C
After reading the model line signal (mode signal) from the PU 14 and determining which lens drive mode to execute, the <timer> routine waits a certain period of time, and then the "Damn Read" routine is executed again. The time at which the mode is switched is read. Then, the process returns to the first mode read until the mode switching is completed. mode/
The reason why the ``read'' subroutine is passed through twice with the ``timer'' in between is to prevent reading errors at the time of mode switching.

When the mode has been reliably switched and the mode before and after the switch is the same, the mode after the switch is read and a transition is made to the subroutine for each mode. In other words, the lens drive modes are <lens reset>, <
PF (power focus)>, <AFSIN (AF
When one of these modes is selected, the subroutine of the selected mode is executed, and then the process returns to the above-mentioned routine 110 Initialize.

<Lens Reset>, <PF>, <AFSIN>.

When none of the <AFSEQ> modes is selected and the <Other> mode is selected, this is treated as mere noise, and the above ■10 initialization is performed in the <Timer> routine after a certain period of time. Return to >.

Here, the operation of the lens reset mode is to forcibly retract the lens to the infinite (flash) position, thereby changing the relative distance signal, that is, the distance measurement output signal output from the focus sensor 20. This is an initialization operation for replacing the pulse movement number from the position at infinity (oo) with the number of pulses and converting it into an absolute distance signal, that is, an operation for clearing the absolute distance counter. If [Lens Reset] is selected, for example, 5ms after clearing this absolute distance counter.
After that, it returns to the J10 initialization operation. Also, <
In the PF> mode, the distance ring of the lens is driven not manually but by the lens drive motor 31, and the focusing operation of the lens is performed using manual focusing or focus aid. More specifically, the PFUP (up) operation switch S%1, which will be described later. .

Turn on operation switch SW2 for PFDN (down).

When the lens is turned off, the lens is extended and retracted. Furthermore, the operation in the <AFS IN> mode is a one-shot AF operation, and the focus is locked after the AP operation for the subject. Furthermore, <A
The FSEQ> mode is continuous AF, and in this mode, as long as the first stage of the release button continues to be operated, the AF operation will be performed continuously for a period of time.

By the way, as operation switches for each mode of lens drive, four operation switches sw-5w4 are used, as shown in Table 1 below.

Below is the margin table (*Can be either ON or OFF) 1. second operation switch sw,
8w2 is commonly used in AF mode and PF mode, and the third operation switch SWs is used for AF when it is off.
mode, PF mode is selected when it is on. 1st in AF mode. When the second operation switch SW1 and 8W2 are both off, the lens reset mode is set, when both are on, the AFSEQ mode is set, and when the first operation switch SW1 is off and the second operation switch sw2 is on, the AFSIN mode is set. In the PF mode, when the second operation switches 1j and 8w2 are both off or on, the stop mode is in effect, and when the first operation switch SWl is on, the motor rotates the distance ring toward the short distance side. When the second operation switch SW2 is on, the PFD rotates the distance ring toward the far side and retracts the lens.
It becomes N (down) mode. Also, the fourth operation switch S
W4 does not change regardless of whether it is on or off in any of the AF modes, or whether it is on or off in the stop mode of the PF modes. Hl (high speed) when turned on in PF mode
mode, the lens drive motor 31 rotates at high speed and coarse movement of the range ring is performed, and when it is off, it enters LO (low speed) mode, where the motor 31 (see Figure 3) rotates at low speed and fine movement of the range ring is performed. .

Next, operations in each lens drive mode will be explained using flowcharts shown in FIGS. 5 to 9.

If the <AFSIN> mode is selected, the <AFSIN> routine shown in Figure 5 is executed, and the main CP
It is detected whether the -AFENA signal from U14 is at "H" level (active). With the first operation of the release button, the AFENA signal becomes active, AF operation is started, and the <AFS IN2> subroutine is called. However, the second operation of the release button is accepted when the AF operation is completed, a focused state is obtained, and the exposure sequence is started.

In <AFS IN2>, as will be described later, CCD integration of the focus sensor 20, calculation of distance measurement output, lens driving, etc. are performed. And the AF of this <AFSIN2>
Focus is the result of movement.

Out of focus is displayed by monitoring the AF status flag after the <AFSIN2> operation. The AF status flags include a low contrast flag (a flag set to "1' when the subject is in low contrast, hereinafter abbreviated as LC flag"), and a movement flag (when the subject is moving).
The flag set to ``1'' (hereinafter abbreviated as M flag) and the closest approach flag (the flag set to ``1'' when the lens is extended beyond the closest distance, hereinafter abbreviated as N flag). Of these,
Focusing is possible when any of the flags is "0", and it is impossible to focus if any of the above flags is set.As a result of monitoring the AF status flag, it was found that the AF status flag was "0°". If the focus is OK, the LED 24a of the AF display circuit 24 indicates that the focus is OK.
If the F status flag is not "02", the LED 24b indicates that the focus is not possible.If the F status flag is not "02", the LED 24b indicates that the focus is not possible.If the F status flag is not "02", the LED 24b indicates that the focus is not possible.If the F status flag is not "02", the LED 24b will wait until the AFENA signal becomes "L" level, and return when the AFENA signal becomes "L" level. If it's hot,
When the EOFAF signal is issued, the AF operation is completed, and the main CPU 14 enters a state of waiting for the second operation of the release button, that is, the start of the exposure sequence. And AFE
A check is made for the NA signal. In other words, when -degree focusing is completed, even if the AFENA signal is active, subsequent lens operation is prohibited and the focus indicator LED2
4a remains lit, and the focus is locked. AFENA signal from main CPU 1.4 is “
When the level becomes L° (inactive), the process returns to the initial operation of the power-on reset flow shown in FIG.

While the mote with <AFSIN> above is operating, <AFS IN
The program operation of subroutine 2> is performed as shown in FIG. First, in order to compare the previous distance measurement calculation value (the previous output pulse of the focus sensor 20) and the current distance measurement calculation value (the current output pulse of the focus sensor 20),
The ETRYC retry flag is cleared, and the maximum number of distance measurements in a series of AF operations is set in the AF loop counter. After this, above a certain brightness, the CCD will definitely
CCD in the ITIME register so that the integration is done.
The maximum value of integration time is set. Then, the AF status flag is cleared, and the S lamp flag is also cleared. The operations in the flow up to this point complete the initialization operation before starting AF.

After this, the lens read> routine is called, and after each lens data stored in the lens specific data circuit 18a is read out, the <AF> routine for distance measurement is called.
> routine is called.

In this <AF> subroutine, S
It is determined whether or not it is necessary to light the lamp 27a. If it is necessary to light the lamp 27a, the S lamp flag is set, and if it is not necessary, it is cleared. Also, a low light flag (a flag set to 1'' when the subject is low light, hereinafter abbreviated as LL flag) and an LC flag are set or cleared.

Now, after the distance measuring operation of <AF>, when both the LL flag and the LC flag are cleared, the routine of <pulse> is called and the amount of lens drive is calculated.

In this <Pulse> routine, as shown in Figures 7A and N7B, the AF (distance measurement) calculation output value obtained in the above <AF> routine is converted into the drive amount of the focus group for each photographing lens. , the necessary lens-specific data (optimal AF coefficients A, B).

C and information on the amount of rotation of the distance cam corresponding to the focal length) is read out from the unique data circuit 18a in accordance with the set focal length. Next, information regarding the amount of drive of the focus group in the optical axis direction from the current position of the focus group to the expected focus position is calculated using the read optimal AF coefficient and AF calculation output value. After that, focusing takes into account the shape of the non-linear distance cam based on the information on the rotation amount of the distance cam according to the set focal length, the current position of the focus group, and the information on the amount of movement of the focus group in the optical axis direction. The number of pulses (address signals) (LPLS) corresponding to the drive amount of the group is calculated.

Next, in the subroutine 1.Pulses> above, the number of pulses (L P
After determining L S), determine the absolute distance of the subject and photographing magnification before driving the lens to the focused state.<0BJDA
TA> subroutine is executed.

FIG. 8 is a flowchart of the <0BJDATA> subroutine. In the figure, it is checked whether the direction in which the photographing lens is moved is from the infinity end to the close end. If this is the case, the number of pulses from the infinity end at the current position of the focus group of the photographing lens set in the absolute distance counter (DISC
NT) and the number of pulses (LPLS) corresponding to the amount of movement from the current position to the subject's planned focus position obtained in the above routine Pulse>, and calculate the distance from the infinity end of the subject's planned focus position. The pulse number is stored in the pulse number (OBJPLS).

If not in the feeding direction, that is, in the drawing direction, the number of pulses from the infinite end at the current position (DISCNT)
The number of pulses (LPLS) corresponding to the amount of movement from the current position to the expected focus position is subtracted from the target position, and the subtraction result is stored in the number of pulses from the infinity end of the expected focus position (OBJPLS). This subtraction result is negative, a completely borrowed
When appears, the expected focus position will be even closer to infinity than the infinity end, but since this is still the infinity end, <0B
JPLS-0>Set the number of pulses from the infinite end of the planned focusing position (OBJPLS) to 0. If you do this,
It is also possible to improve distance measurement accuracy.

The number of pulses from the infinity end at the expected focusing position (OBJPLS) obtained by adding or subtracting in accordance with the extending direction and retracting direction, the absolute distance coefficient a,
<0BJD, according to the absolute distance coefficients a and b corresponding to the set focal length read from the lens specific data circuit 18a in the routine ``b, and magnification coefficient readout''.
IST-OBJPLS, absolute distance coefficient> routine to obtain the object distance (OBJDIST).

In addition, the number of pulses from the infinity end (OBJPLS) at the above scheduled focusing position is the absolute distance coefficient a,
<OBJMUL←0BJP> according to the magnification coefficient according to the set focal length read from the lens specific data circuit 18a in the routine ``b and magnification coefficient reading''.
LS, magnification coefficient> is calculated, and the photographing magnification (OBJMUL) of the subject is determined. By the way, the absolute distance coefficients a, b and magnification coefficient read out from the lens specific data circuit 18a in the above-mentioned routine of reading absolute distance coefficients a, b, magnification coefficient can be selected or corrected accordingly in the focal length and macro range. It is also possible to calculate and use it. Then, these object distances (OBJDIST
) and imaging magnification (OBJMUL) are <0BJDIST,
In the routine of OBJMUL communication, main CPU1
4 will be sent.

In main CPU14, <0BJDIST, OBJ M
UL reception>, the object distance M (OBJDIST)
) and magnification (OBJMUL) to determine whether strobe balax correction (or auto zoom) is necessary. If necessary, perform zooming calculations for strobe balax correction and auto zoom drive. C
Based on this calculation result, the PU 14 drives an actuator and a zoom actuator for balax correction in parallel with lens drive for focus adjustment, which will be described later.

In this way, in the present invention, the lens extension position that would be in an ideal in-focus state is determined from the lens drive amount until focusing and the current lens extension amount, and the object is brought into focus before the lens is moved. Calculate the absolute distance shooting magnification when focusing.

Thereafter, the AF calculation output value (ERROR) is compared with the AF accuracy threshold ETh read from the lens specific data circuit 18a, and the AF calculation output value (ERROR) is compared with the AF accuracy threshold ETh read from the lens specific data circuit 18a.
ROR) is larger than the AF accuracy threshold ETh, the process proceeds to (2) and the RETRY flag is determined. 1
In the second AF operation, since the RETRY flag is 02, the number of drive pulses is saved after the RETRY flag is set. Since the RETRY flag is set in the second and subsequent AF operations, the current number of drive pulses and the previous number of drive pulses are compared. At this time, if the number of pulses this time is smaller by the amount of movement than the number of pulses last time, it means that the lens drive has brought it closer to the in-focus point, so the next lens drive will bring it even closer. It was decided that the current pulse would be saved instead of the previous pulse, and <M
DRIVAF> routine is called to drive the lens. Also, the absolute distance counter has a distance ring of infinity (■).
The number of drive pulses from the position is set.

The purpose of comparing the previous pulse and the current pulse is to
The purpose is to prevent divergent behavior of the entire sequence. Possible ways to compare the two are (current pulse number):(previous pulse number X O,5), or (current pulse number)=(previous pulse number X 1.5). If the AF sequence system is likely to be in a divergent state, it may be possible to perform the AF operation while the subject is moving, so in this case,
Immediately stop lens driving, set the M flag to prevent unnecessary AF operations, and return.

After the lens is driven by <MDRIVAF>, 1 is subtracted from the distance measurement value of the AF operation set in the AF small loop counter. As a result, if the value of the AF small loop counter is not 0, the ITIM
Set the integration time in the E register, and then set the AFENA
When the signal is active (that is, the first operation of the release button is on), for the next AF operation,
Return to O. In this way, each time the AF operation between 0 and 0 is repeated, the value of the AF small loop counter is decremented once, and the value of the AF small loop counter gradually approaches the in-focus point, or the value of the AF small loop counter reaches 0. Even if the AF calculation output value (ERROR) or the above AF accuracy threshold ET
If it does not become smaller than h, it is assumed that it is impossible to focus and M
A flag will be set.

As a result of the AF operation between 0 and 0, if ERROR<ETh, that is, if the AF calculation output value (ERROR) falls within the focus error range, the AF status flag is cleared to indicate that the in-focus state has been reached. , return.

Here, after the <AF> operation described above, if the LL flag or LC flag is set, the state of the S lamp flag is tested. At this time, if the S lamp flag had been set to "1" in advance, the low light and low contrast state would have occurred even though the S lamp 27a was lit during the integration operation for AF. Therefore, in this case, the LC flag is tested again, and in the case of low contrast, the only lens NF (unable to focus) routine is called to actively display the inability to focus. That is, in this lens NF> routine, the lens is first extended to the closest position, and then moved to infinity (clo).
), and the user is actively notified of the inability to focus by moving the lens significantly. Note that the lens operation indicating inability to focus may be an operation of moving the lens from the infinity (c-3) position to the closest position. In addition, in this lens NF>, an absolute distance counter is used to save the number of drive pulses (number of movement address signals) from the infinity (oo) position of the lens distance ring by hitting the infinity (oo) position. is initialized. If the contrast is not low, it means that the AF calculation was performed even though the light was low, so in this case, the value returns to 0.

Also, if the S lamp flag was cleared in advance, it means that the S lamp 27a was previously off, so if the LL flag or LC flag is set, set the S lamp flag. , proceed to [F].

Therefore, the S lamp 27a will be lit in the second and subsequent AF operations.

In addition, if the subject is moving, that is, it is a moving object, by measuring the distance to the subject multiple times, it is possible to find the speed of the subject's movement. AF that follows a moving object becomes possible. This multiple AF may be performed with AF driving in between.

It is also possible to predict the movement of a moving object, predict time delays such as mirror up, and set a predicted drive amount when performing AP drive.

FIG. 9 is a flowchart of the subroutine <AFSIN2A> when tracking and AFing such a moving object. Only the routines related to moving object tracking in the flowchart of the subroutine AFSIN2> shown in FIG. 6 are extracted. This is what is shown.

In the figure, the explanation of the routine already explained in FIG. 6 is omitted, and only the change routine will be explained.

In Figure 9, <AF>, <Pulse>, <0BJDJ
Information on object distance (OBJDIST) and photographing magnification (OBJMUL) obtained through signal processing in subroutines such as ST> is used to determine whether or not it is in focus in the focus determination routine. For status information, the subroutine (AFSIN2) of the flow <AFSIN> shown in FIG.
Next return〉. If the focus is not focused, the process proceeds to a routine that determines whether or not the first AF is out of focus.
If MDRIvAF>, the first time) is not AF, that is, if AF has been performed multiple times, then the previous time is 0BJDIS.
The routine proceeds to a routine that calculates T-this time 0BJDIST> and determines its size. This time last time 0BJDIST-this time 0
If the difference between the previous object distance information (OBJDIST) obtained in the routine <BJDIST> and the current information is large, a pulse correction> is performed, and if it is sufficiently small, the process directly proceeds to the routine <MDRIVAF>. Next, the process proceeds to a routine to determine whether it is predictive AF or not, and the purpose of moving object tracking is to track a moving object to find the subject distance, and also to determine if the moving object has moved between the end of AF and the actual shooting. With predictive AF, which predicts the position where the object will be and focuses on the predicted position, it is useless to perform AF any further, so the subroutine <AFS IN2> in the flow of <AFS IN> shown in FIG. 5 is used. Return to the next routine. Also, if not, proceed to the routine 0BJDIST←0BJDIST>, and store the information on the subject distance (C0BJDIST) that has been set this time in the memory area that stores the object distance (OBJDIST) information obtained last time. After that, the process returns to the <AF> subroutine, and the above operations are repeated until focus is determined.

In this embodiment described above, the lens-specific data necessary for calculation, such as the absolute distance coefficients a and b and the magnification coefficient, are stored in the lens-specific data circuit 18a, and are read out and used. It goes without saying that if this lens-specific data is written as an immediate value in the program in a camera with a fixed lens, the memory circuit can be omitted. The absolute distance and photographic magnification of the subject were calculated before focus determination, but even if you execute the <0BJDATA> routine only after focus determination, as shown in Figure 10, it will still not work according to the ideal focus position. The absolute distance of the subject and the magnification can be determined.

[Effects of the Invention] As described above, according to the present invention, the amount of movement of the focusing lens group in the optical axis direction and the amount of driving of the drive member for focus adjustment operation are non-linear. In a related lens optical system, when converting the focus shift into the drive amount of the focus lens group, first obtain information about the shift in the optical axis direction of the in-focus point of the focus lens group, and then calculate the drive amount of the focus lens group. Therefore, it is possible to provide an automatic focus adjustment device for a camera that can convert out-of-focus into a driving amount with a simple configuration.

[Brief explanation of drawings]

1A to 1C are conceptual diagrams of an automatic focus adjustment device for a camera according to the present invention. FIG. 2 is a block diagram of an electric circuit mainly for power supply of a camera system to which the present invention is applied. The figure is a block system diagram showing the transmission and reception of signals centering on the AF block in Figure 2 above, and Figures 4 to 10 show the program operations centered around the AF CPU shown in Figure 3 above. 11 is a configuration diagram of a photographing optical system consisting of a zoom lens used in an embodiment of the present invention; FIG. 12 is a diagram showing the relationship between distance cam function and cam lift amount; Figures 13 and 14 are graphs showing the relationship between the amount of extension required for focusing and the amount of defocus for wide and tele, respectively. Figure 15 shows the relationship between the focus shift and the amount of defocus required for focusing. A block diagram illustrating an algorithm for converting into a driving amount for focusing, Figures 1 and 6 are diagrams showing the relationship between the lift amount of the distance cam, the amount of rotation of the distance cam, and the amount of rotation of the distance ring. . 1.....Breaking information detection means 2............Focusing lens group deviation information determining means 3
...Focusing lens group drive amount calculation means 4...
...Feeding amount detection means 5...Photographing lens

Claims (1)

[Claims] (1) In a camera automatic focus adjustment device in which the amount of drive of the drive member for focus adjustment operation and the amount of movement of the focusing lens group have a non-linear relationship, the imaging plane of the subject light transmitted through the photographic lens a displacement information detecting means for detecting the amount and direction of displacement between the focusing lens group and the film surface as displacement information; a feeding amount detecting means for detecting the amount of feeding of the focusing lens group from the reference position; a focusing lens group deviation information determining means for determining the deviation amount and direction of the driving amount in the optical axis direction with respect to the focusing position of the focusing lens group; and an output of the extension amount detecting means and the focusing lens group deviation information determining means. An automatic focusing device for a camera, comprising: arithmetic means for determining a driving amount of the driving member for advancing the focusing lens group based on an output of the above.