JPS63136012A - Method and device for automatic focus adjustment - Google Patents

Abstract

PURPOSE:To make an accurate automatic focus adjustment by performing arithmetic operation on a conversion lens side as logarithmically compressed data corresponding to focal length set by variable power operation, expanding a conversion focal length set by variable power operation, expanding a conversion coefficient logarithmically on a camera body side, and calculating a driving quantity from this data and a defocusing quantity. CONSTITUTION:The conversion coefficient K expanded logarithmically by a logarithmic expanding circuit LL is multiplied by the defocusing quantity from a range measurement processing circuit 6 to calculate the quantity of driving for moving a lens FL for focus adjustment to a focusing position. A driving mechanism 8 rotates a motor selectively to move an interchangeable lens FL through clutches 1 and 2 after speed reduction. Then, an encoder 10 which is interlocked with the driving mechanism 8 outputs a pulse signal every time the lens FL for focus adjustment is moved by a specific quantity and a counter 11 counts it. A comparator 9 compares data from a multiplying circuit 7 with data from the counter 11, judges that the FL for focus adjustment moves to be focusing position when both data matches with each other, and outputs a motor stop signal to the driving mechanism 8. Thus, an automatic focus adjustment is made.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to detecting the amount of deviation from the expected focal position of an imaging device of an object to be focused by receiving light from an object to be focused that has passed through an interchangeable lens. Detects the corresponding amount of defocus, drives the driving means on the camera body side based on this amount of defocus,
The present invention relates to an automatic focus adjustment method and apparatus that transmits the driving force to a focus adjustment member of an interchangeable lens to move an imaging position and perform automatic focus adjustment.

(Prior Art) Since the detected defocus amount and the drive amount of the driving means have a substantially proportional relationship, the drive amount is calculated by multiplying the defocus amount by an appropriate conversion coefficient. This conversion coefficient data changes depending on the optical characteristics such as the focal length and lens configuration of the interchangeable lens and the focus adjustment mechanism. In other words, the conversion coefficient data differs for each interchangeable lens. Therefore, this conversion coefficient data can be set in the interchangeable lens, the conversion coefficient data can be read from the interchangeable lens by the camera body, and the drive amount can be calculated from this data and the defocus amount. However, some interchangeable lenses, such as a variable magnification lens of the 1ri lens extending type, change the conversion coefficient data as the focal length changes due to the variable magnification operation. In the case of such a variable power lens, there is an R on the variable power lens side.
A storage element such as an OM is provided, and conversion coefficient data is fixedly stored in this ROM according to the focal length, and the conversion coefficient data at an address corresponding to the focal length set by the zooming operation is read into the camera body. Devices that calculate the drive amount from this data and the defocus amount are already known. Conventionally, in this type of equipment, RO
Only the conversion coefficient data regarding the lens is stored in M, and a dedicated ROM must be produced for each lens, which poses a problem of increasing the price of lenses produced in small quantities.

As a device to solve this problem, a plurality of types of conversion coefficient data are fixedly stored in a ROM, and type code generation means for generating a lens type code is provided.According to this type code, conversion coefficient data of the lens is transferred from the ROM. is read into the camera body, and the amount of drive is calculated from this data and the amount of defocus.However, even with this device, there is a limit to the capacity that can be stored in the ROM.
The problem remained that if a large capacity ROM was provided, the cost would increase. In addition, for ROM development, RO
Since conversion coefficient (conversion coefficient) number data fixedly stored in M is required,
Optical design and vAJI of the lens in common ROM
Since the A2 total had to be completed, the optical design, lens barrel design, and ROM development could not be carried out at the same time, which caused the problem that the lead time until mass production was extended by the ROM development period.

Furthermore, since the conversion coefficient data is fixedly stored in the ROM, it is not possible to change the conversion coefficient data by partially changing the lens specifications, which poses a problem that greatly limits product improvement.

As a solution to the above-mentioned problem, converting coefficient data to RO
A conceivable method is to calculate the focal length according to the focal length set by the variable magnification operation without storing it fixedly in a memory element such as M. However, there is the following problem.

If the conversion coefficient data is made to be able to accommodate a lens that changes over a very wide range, such as a variable magnification lens of the curved lens type, the number of bits will increase. Therefore,
Such conversion coefficient data consists of an exponent part and a significant figure part, and the driving amount of the driving means is calculated on the camera body side from the conversion coefficient data consisting of the exponent part and the significant figure part and the defocus amount.

However, the conversion coefficient consisting of an exponent part and significant figure part is R
Although it is easy to store a fixed J value in the OM, it is extremely difficult to calculate this value according to the focal length set by the variable magnification operation.

(Purpose) The present invention has the objective of adjusting the conversion coefficient ' for converting the amount of defocus detected by the camera body into the amount of drive transmitted from the camera body to the interchangeable lens, so that it is always appropriate for the focal length i set by the zooming operation. We aim to provide an automatic focus adjustment method and device that transmits accurate data to the camera body, enables accurate automatic focus adjustment, shortens lead time to mass production, and responds to changes in specifications. do.

(Means for Solving the Problem) The present invention corresponds to the setting j, j4-point distance at by the magnification changing operation, and the conversion coefficient for converting the amount of defocus to the amount of drive transmitted from the camera body to the interchangeable lens. (Calculated on the interchangeable lens side as logarithmically compressed data, serially output to the camera body, logarithmically expanded (exponentialized) the conversion coefficient data read from the interchangeable lens on the camera body side, and based on this data and the defocus amount. +1 is added to calculate the amount of drive of the focus adjustment member.

(implementation@) The present invention will be explained below with reference to Examples.

FIG. 1 is a block diagram showing an automatic focus adjustment camera system to which the present invention is applied. The left side of the constant chain line is the interchangeable lens (X), the right side is the camera body (Y) side, and the clutch (1), (2) Mechanically, the terminal (Po
)~(Pn)? They are electrically connected via (BO) to (B4).

Interchangeable lens (X) heat point adjustment lens (FL) * variable magnification lens (ZL)? The light from the heat-containing object that has passed through the master lens (ML) is reflected by the reflection mirror (3) of the camera body (Y).
) is configured so that the light passes through a part of the translucent mirror provided at the center of the mirror, is reflected by the sub-mirror (4), and is received by the focal position detection element (5).

The distance measurement processing circuit (6) receives f from the focal position detection element (5).
Based on No. 6, calculate the defocus amount ΔL and defocus direction corresponding to the deviation from the planned focal position.

The drive mechanism (8) selectively rotates the motor clockwise and counterclockwise based on the defocus direction data;
Clutch (1) after decelerating its rotation? (2) to the transmission mechanism (DR) of the interchangeable lens, and the focus adjustment lens (FL) is moved to perform focus adjustment.

The lens information output circuit (LD) on the interchangeable lens side is provided with an encoder (ENC) that is linked to the variable magnification operation member (ZR), and data corresponding to the set focal length is input thereto. Based on this data, the conversion coefficient data for converting the amount of defocus into the amount of movement of the focusing lens is converted into logarithmically compressed data at the terminals (PO) to (B4)t (B
The information is read by the lens information reading circuit (LR) on the main body side via Q) to (B4). Logarithmic expansion circuit (LL
) logarithmically expands (exponentializes) the logarithmically compressed conversion coefficient data read by the lens information reading circuit (LR) and converts it into data that is easy to handle in the next multiplication circuit (7). The multiplication circuit (7) uses the conversion coefficient from the logarithmic expansion circuit (LL) and the defocus amount Δ from the distance measurement processing circuit (6).
L is multiplied by 1γ to calculate the drive FIJJ amount for moving the focus adjustment lens (PL) to the in-focus position. Drive mechanism (8
) is provided with an encoder (10), and the drive mechanism (8
) outputs a pulse signal every time the focusing lens (FL) is moved by a predetermined amount, and a counter (11) counts this pulse. The comparison circuit (9) compares the data from the multiplication circuit (7) and the data from the counter (11), and when both data match, it determines that the focus adjustment lens (FL) has moved to the in-focus position and starts driving. A morph stop signal is output to the ff1l structure (8).

In the above description, the overall function of the present invention has been shown in a block diagram. Next, the lens information output circuit (LD) on the interchangeable lens side will be described in detail.

Figure 2 is a block diagram showing the transmission of lens information, with the camera body (X) on the left side of the dashed line and the interchangeable lens (Y) on the right side.
) side lens information output circuit.

The terminal (BO) on the camera body side is connected to the rtFii output terminal and the power input terminal (Pa) on the interchangeable lens side. (B,) on the camera body side is connected to the counter (B,) via the input terminal (Pl) and impark (IN) on the interchangeable lens side.
Go, ), (Go'Good) is connected to the Nori set Kishi 1 child (RE).

This input terminal (Pl) is "High'" while receiving information from the interchangeable lens, and the counter (COI) is
), (Co□) are in the reset release state.

The output terminal (B2) on the camera body side sends the Y1 pulse from the camera body to the interchangeable lens side via the input terminal (B2) of the interchangeable lens in order to synchronize the electrical operation between the interchangeable lens and the camera body. Counter (COI) terminal (C
L) is followed by “C”.

The counters (COI) and (co□) are 3-bit pinary counts, and the counters (Co,') count the rising edge of the I'J pulse from the input terminal (B2), From the rising edge of the second clock pulse to the rising edge of the next clock pulse, set the carry node 1 child (CY) to °'High.The counter (
Co□) counts the rising edge of this carry terminal (CY), and the counter (Co□) flu increases by 1 each time the first pulse of the 8th clock pulse rises.

The 3-bit output (E2 to EO) of the counter (CO2) is input to the decoder (DE2).
From N), the output terminal (So) = (St) t (Sz) according to the contents of the counter (Co□)
? (SJ)t(Si) is sequentially set to "High"', and select number 1d is output to the decouple selector (DSL).

When the data select signal (So) from the decoder (DE2) is “High”, the data selector (DSL)
″.

In this case, the lens specific information (AI) set in the input glass (AI, ~A I o') is used as the output glass (Is~I o').
o), then Data Select No. 13 (St)
becomes “High”, the input terminal (B I s ~ B
The lens specific information (BI) set to Io) is output to the output terminals (Is to Io). Similarly, when the data select signal advances to (Sz)pC53)-(S-), the input terminals (CIS to CIo)t(D
I5~D Io)t (E Is~E Io)
Lens specific information (CI)t (DI)t set to
(E I) are sequentially output to the output terminals (Is to Io). ), the counter (CO2) and decoder (DE2)
) and the data selector (DSL) are shown in Table 1.

Table 1 The lens specific information (AI') set to the input terminal of the data selector (DS) is set with an information identification code "000001" that identifies the quantity and content of the lens specific information set and output by this lens. If the lens has a large amount of information, the information identification code "ooooio" is set. The camera body reads this identification code and selects the subsequent information reading method. The function code set to (BI) is automatic wringer 47. If V is built in, set (BIO) to 'Hi g h''. and if the focus adjustment lens is extended in the counterclockwise direction (B
I2) is set to "High'". (
CI) is AV Moe (
AV=Log2 p2) is 1/8 E V 1
It is set at 11th place. For example, when the aperture is open (Ij is F
:2.5 is easy, and its AY ratio is 2+5/8, so it is determined as ""010101 pa and d. In addition, the odd f,
In the case of a lens whose open aperture changes by operation, the most open aperture is set. For (DI), the focal length of a fixed focus coarse array lens is set to 3 Log, f, which is the logarithm value of the shortest focal length f to the base of 2 for a variable focal length lens. has been done.

For example, if the fish spot distance and koshiki are f = 35 mm, the value is “10100”.
1". Then, in (EI), a focus adjustment lens is planned based on the amount of defocus Δd that corresponds to the amount of deviation of the imaging position of the subject to be focused detected by the camera body from the fixed focal point t. A conversion coefficient K is set to correspond to the amount of movement ΔL toward the prefecture single point position.With this), the shift of the imaging plane when the lens is moved by ΔL!1lII
:b''!, the ratio of Δd and ΔL is expressed as Kd=ΔL/Δd, and the helicoidal lead of the focus adjustment member is HL.

When the reduction ratio of the transmission mechanism is GL, the following relational expression (ζ) is given: K=Kd/(GLXHL). Furthermore, it is known that the relationship Kd=ff2/f2 approximately holds true if the focal length of the entire optical system is f and the focal length of the optical system for focus adjustment is ff. 41' (There.

Therefore, when the focal pressure fif doubles, as in the case of a +]υ variable magnification lens, Kd x and the change conversion coefficient K
Since it changes over a very wide range of 1/4 times, it becomes impossible to cope with the number of JJ and ff elements of the input glass (EI). Therefore, the coefficient KL that makes the conversion coefficient K a logarithmically compressed fraction is expressed as K L = 16 LO92K + 64, and KLflu is set to the input terminal (EI). For example, if the conversion coefficient K is 0. For 1, "001011""
becomes. Note that in the case of a variable magnification lens, the conversion coefficient on the long focal point side where the conversion coefficient is the smallest is set.

The decoder (DEN) outputs the decouple select signal (So-5-) to the deku selector (DS, ), and at the same time also outputs a part of the output 1Ei (Sz~s,) to the deku selector (DSz). Output. The data selector (DS2) is the decoder (DEz). Rec I No. 13 (S2) is “High’”
When , the amount of information change per unit movement (
CJ) is output to the output terminals (Js~Jo), and similarly, when the decouple select signal advances to C53) and (54), the human power terminals (DJ, ~D J +)t (
Information change amount (DJ) set to E Js ~ E, J,)
t (EJ)'' are sequentially output to the output terminals (Js to Jo). ), the counter (COz) and decoder (
Table 2 shows the relationship between DE2) and the data selector (DSz).

The information change amount (CJ) set to the input terminal of the data selector (DS2) is set to the amount of change ΔAV of the open aperture per unit movement amount corresponding to the focal length of the lens whose open aperture ratio changes due to the zooming operation. ing.

For example, when the open aperture value on the short focus side is F2=2.5*the open aperture value on the short focus side is F2=3.5, the total amount of change AVO is AVO=Log□ F22−Log□ Fl'=(09
□(3,5)2Logz (2,5)2=1 (EV
) Since the resolution of the encoder (ENC) is 15 steps,
Open aperture change amount ΔF of it position movement amount = 1/15
(EV) and placed this in 1/64E111th place.
101°' is set.(DJ) is the unit diameter!
A focal length change amount Δf per liI amount is set. For example, short focus side fl=35mm, long focus side f2=13
The total amount of change fO in case of 0mm is fO=8Lo9z F2-8109□ f1=8Lo9z
130-8LO9z 35=15.15 The workpiece per unit movement (!, point distance sequence change Δf=15°15/15, which is set as "0100"' in the 2 quasi expression with 1/4 unit) Then, ((EJ) is set to the conversion coefficient change amount per 111th position movement.For example, the conversion coefficient of 35 mm on the short focus side is 1 = 1.3.
7, if the focal length changes by a factor of 3.7 to the long focal point side of 135 mm, the conversion coefficient is 1/13.7 times from the relationship Kd = ff2/f2 in 11υ, that is, the long focal point side is 135 mm.
The conversion coefficient K 2 =0.1, and 1tK2 is logarithmically compressed (total change in coefficient KL to +U)
O is KLO=16LoqzK1 16LO9zK2”
16 Log21.37- I G Log20.1=
60.4 Conversion coefficient change amount Δ of fli position movement = 60°4
/15 and "100°" is set.

In addition, in the case of a fixed focus lens or a lens in which each information does not change due to zooming operation, each input terminal (CJz "CJ
o-)t (DJ4~DJ+)t (EJs~E
J3) is set to 0゛°. Also, the accuracy required to set the amount of change in each information and the possible changes in the amount of change1^
Depending on the number of input terminals of the DQ selector (DSz) and the output position of (d) when outputting the input information to the output nodes (Js to Jo), the number of input terminals of the DQ selector (DSz) can be adjusted to correspond to the amount of change in each information.
(It has not been decided yet. - The data selector explained above (
Lens specific information (AI) input to the manual terminal of the DSL)
t (BI) t (Ci) t (DI), (E I) and the amount of change in information CC that is applied to the human input of Data Select (DS7)).

(DI) and (EJ) are set when the zero circuit is installed in the lens barrel or during the preparation stage)? It can be set with . To set each bit of information to "0", connect the corresponding input terminal to ground, and to set it to "1", connect the corresponding input terminal to the power supply line (+VF).

To easily adjust the magnification lens, an encoder that outputs a 4-bit (J) corresponding to the relative movement amount from the reference position to the set position is activated by operating the coarse focus row magnification operation member (not shown). (ENC) is provided.

The conduction pattern of the encoder (ESC) is such that the amount of change in the information per the 111th position movement amount (1 step of the encoder) set at the input terminal of the song J Pei Deku Select (DSz) is synchronized with the amount of change indicated by the actual lens. ing.

The sliding member (VC) is interlocked with the coarse focus row magnification changing operation member, and the thermal focal length is set at any one of setting positions ① to 09. The conductive pattern (COM) is grounded, and the other conductive patterns (EC::s to ECo) are connected to the power supply line (-VF) via resistors, respectively. Therefore, the contact piece of the Ji'f moving member (VC) is connected to the conductive pattern (EC
3 to ECo), the conductive pattern (C:OM) and the conductive pattern (EC3 to ECo) that is in contact with the sliding member (VC) ), and the signal output becomes "Low". Also, although it is non-contact (J output is High)
"become.

The output of the conduction pattern (EC3) of the encoder (ENC) is connected to the - input terminal of AND gate (ANA) (AN8), and the input terminal of
The output terminal (S4) of the gate (DE2) is connected to the output terminal (S4) of the gate (DE2), and the output of the gate (AND) is connected to the output terminal (S4) of the gate (DE2). input terminal and multiplier circuit (MLT) input terminal (K3)
connected to. The output of the conduction pattern (ECz) is connected to the other input pH1J of the exclusive OR gate (ER2) via impark (IN, ), and the output of the exclusive OR gate (ER
The output of z) is exclusive or game! -(ER,) and the input terminal 91 (K2) of the multiplication circuit (MLT). The output of the conduction pattern (EC,) is connected to the other input terminal of the exclusive OR gate (ER,') via the impark (IN, ), and the output of the exclusive OR gate (ERI) is connected to the exclusive OR gate 1-(ERO). It is connected to one input terminal and the input terminal (K1) of the multiplication circuit (MLT). Furthermore, the output of the conduction pattern (ECo) is connected to the other input terminal of the exclusive OR gate (ERo) via the inverter (INo), and the output of the exclusive OR gate (ERo) is connected to the input terminal (K ,) connected to. ), the encoder (ENC) output (EC3 to ECo) at the focal length setting position ■ to ■ and tick 1-
Table 3 shows the relationship between the output (S, l) of the multiplier circuit (DE2) and the output signal to the human power node J (K, ~Ko) of the multiplier circuit (MLT).
Shown below.

(Left below) Table 3 The conduction pattern of the encoder (ENC) is the output (E Cs
~ECo) is provided so that it becomes a gray second. The output node 4 (S4) of the decoder (DEz) is °'L
ow”, 1% based on the setting position of the fish spot distance r?Jt.
The relative movement amount to the set position when the IJ position is set is output to the input terminals (K3 to Ko) of the multiplication circuit (MLT). In addition, when the output terminal (S4) of the decoder (DE2) is "High", the relative movement amount up to the setting position 16 when the focal length setting position ■ is the reference position is the input to the multiplier circuit (MLT). It is output to the terminals (K3 to Ko).

In this way, the output node (S4) of the dego 1-der (DE2)
The reason why the reference position of the point distance sequence is switched to ■ when the signal is ``High b'''' will be explained with reference to FIG. 3.

In FIG. 3, the horizontal axis shows the setting positions of the encoder (ENC) from ■ to ■, and the vertical axis corresponds to the lens specific information item. In this lens, there are three types of lens-specific information that change when the focal length is changed: the maximum aperture value, the focal length, and the (conversion coefficient) shown in Figure 3. Among these, the maximum aperture fI
The point distance between /i and S1 changes in the direction in which the °C Luns specific information increases as the encoder (ENC) setting position advances from ■ to ■.

However, the conversion coefficient changes in the opposite direction.

Therefore, for the open aperture and focal length, specify the encoder (ENC) setting position ■ where the information A1-1 is minimum as the reference position, and input the open aperture (tri) at this reference position to the data selector (DSL). To the terminals (CIs to CIo),
The focal lengths are set to the input terminals (DI5 to Dlo), respectively. Also, the transform coefficient is minimized by the encoder (E
NC) The setting position (2) is designated as the reference position, and the conversion coefficient at this reference position is set to the input terminal (E2, ~EIo) of the data selector (DS, ). Then, depending on the difference in C1 reference position ■ or ■, the relative movement amount from the reference position input to the input terminals (K3 to KO) of the multiplier circuit (MLT) to the set position is switched as shown in Table 3. .

Multiplier circuit (MLT) is data selector (DSz)
From the output terminals (Js to Jo), input terminals (K3
~'Ko) is used as a multiplier to obtain the amount of change.

J5 J4 J3 J2 JI JO... Multiplicand (4
1st place information change amount)X K3 to 2 KI KG...
・Multiplier (relative movement amount) Figure 4 Single point left chain Right side is multiplier circuit (
I am a friend of MTL's circuit structure. This first multiplication uses a bit shift addition method, and the principle of this will be explained using the following equation.

The multiplicand (6 bits) is shifted to the left one bit at a time, and the digits (4 bits) of the multiplier are arranged and added.

At this time, each pitch of the multiplier I・(Ko )t(KI)t
(K2)? (K3) is “1′′
If so, add it, and if “0”′, do not add it and multiply by fl
li is required. Next, according to this jCt principle, the circuit 44a Jλ is multiplied by 12 circuits (
(MLT) will be explained.The multiplication circuit (MLT) is made up of the following four circuits.

First, let the unit information change amount 5: the multiplicand to the 6-bit human power node 1 child (Is~Jo) of A (additional 11 digit discrimination circuit).
and input the relative movement amount as a multiplier to the 4-bit input terminals (K3 to KO). In this case, if the input signal of the input terminal (Ko) is “1'°, then the AND gate (ANO5)*
(ANO4)? (ANO3)t (ANO2
)t(ANOl) gate is opened, 6-bit input node;
The unit information change amount of children (J5 to Jo) is B (multiplier Kl
jKo digit addition circuit). In addition, a manual terminal (K
o) input (if the iJ number is "'0pa
ANO5) t (ANO4)? (ANO3)t
(ANO2).

The gate of (ANOI) closes and B (multiplier Kt s Ko
All 'C'0°' is output to the digit adder circuit (digit addition circuit), so the multiplier (Ko) digit is not added.Similarly, if the input ffi number of the input terminal (K1) is "1'°, the AND gate (AN15)j (AN14), (AN13)?
(AN12).

(ANII)? The gate of (ANIO) opens, and the unit information change amount of the input terminals (Js to Jo) is output to B (multiplier of 1°K (, phase addition circuit). The input signal of the input terminal (K2) is If it's 1 pa, it's an anime game) (A N25)
p(AN24)? (AN23) t (AN2
2) The gates of j (AN21) and j (AN20) open and the unit information change amount of the input terminals (J, to Jo) is output to C (a circuit that adds two digits to the multiplier). Soshi゛(、Jinrikibushi 1st child(
If the input number 1+j of N3) is "'1", then Antogame-1-
(AN35)t (AN34)t(AN33), (A
The gates of N32), (AN31), and (AN30) are opened, and the color information change amount is output from input terminals (Js to Jo) 4' to D (multiplier: +44j addition circuit).

The unit information change amount output from A (additional digit discrimination circuit) is calculated for each digit of the multiplier by B (multiplier 'Kl t Ko digit addition circuit).
, C (2-digit addition circuit for the multiplier), and D (3-digit addition circuit for the multiplier). The left side is added in the form L-L. Then, the OR gate (OR23) of
R35) t(E R33) p(E R31)
t (ER29) outputs a 7-bit change amount as a multiplication result.

One point in Figure 4! □The additional circuit (ADD) on the left side of the chain is
This is a circuit configuration of the adder circuit (ADD) in FIG. 1. Input lens specific information at the reference position to the 6-bit input terminals (I5 to Io) from the data selector (DSL), and multiply the amount of change output from the multiplier circuit (MLT) on the right side tilted to the left at one point in Figure 4. input, the amount of change is added to the lens specific information at the reference position, and the addition result is output to the output terminal (0, ~Oo)
is output to. By this addition, the open aperture ratio, focal length, and conversion coefficient at the focal length r41 setting position are determined.

Note that the information identification code and function code are information that does not change due to the coarse focus column magnification change operation, so the amount of change output from the multiplier circuit (MLT) is all "0", and therefore, the amount of change output by the adder circuit (ADD) is There is no change in the information content.

Referring back to FIG. 2, the explanation will be given again.

3-bit output (CZ~Co) of counter (COI)
is input to a decoder (DE,), and this decoder (D
From E, ), Table 4
Outputs the number shown in .

Table 4 The output terminals (Do ~ Dy) of the decoder (DE, ) are connected to one input terminal of the AND gate (A No ~ ANy), and the other is connected to the output terminal (00
~0. ), and the AND gate (ANo~AN7)
The output of is OR game 1-(OR), QWJ child (R3) t(
A signal is output to the camera body side (X) via BE).

When the counter advances by one at the rising edge of the clock pulse, the output core 4 (Do) of the decoder (DEI) becomes “High”.
h'', the gate of Antoge 1 (A No ) is opened, and No. 13 of the output terminal (Oo) of the adder circuit is outputted via the OR gate (OR). In this way, every time the clock pulse rises, The output node 1 of the adder circuit (
Oo～0. ) signal is sent one bit at a time from the least significant bit to the camera body side (X) via AN2, OR gate (OR), node 1 child (R3), and 1 Lf. The number is output.

In this section, we will return to FIG. 1 for explanation.

The conversion coefficient data KL output from the lens information output circuit (LD) is a logarithmic fE reduction index (terminals (Po) to (
R4) and (Bo) to (R4) are read by the lens information reading circuit (LR) on the main body side.

This conversion factor fiKL is multiplied by the defocus amount in the multiplication circuit (7) to calculate the drive amount for moving the focusing lens (FL) to the in-focus position.

However, since the number KL read from the interchangeable lens side is logarithmically compressed using the formula shown as KL = 16 LO92K + 64,
It is difficult to handle for those who are on the first level. Therefore, a logarithmic expansion circuit (LL) which logarithmically expands (exponentializes) this KL count into a conversion coefficient K of logarithmic compression 1)υ calculates data that can be easily handled by the multiplication circuit (7).

(IL-6S/16 To perform logarithmic expansion (exponentialization): = 2 Conversion body RKIi: It can be calculated using the formula, but since the calculation is complicated, logarithmic expansion (exponentialization) is performed using the following approximation method. .

The conversion coefficient data KL, which is logarithmically compressed data from an interchangeable lens, is expressed in the upper four bits as shown below.

The lower 4 bits are used as the decimal part, and 1 is added to this as the integer part to obtain (1).

1, by subtracting 4 from the binary number consisting of Kx Kz K+ Ko ``”””' (1) and E3Ez E+ Eo, and shifting several of the above (1) by the amount of fl calculated by this. , 1pJjl't is calculated as an approximation to the conversion coefficient (^).Table 5 shows the conversion coefficient KL as logarithmically compressed data output from the interchangeable lens, the conversion coefficient KA calculated by numerical calculation, and the approximation method described in 11υ. Indicate the calculated conversion coefficient aKB and check the accuracy of the ζ approximation value.

Kl calculated by the approximation method is slightly larger than KA (Lfi) calculated by numerical calculation.
If the focus adjustment member is moved by a large amount, the focus adjustment member may pass the intended focus position and end up hunting in front of or behind the intended focus device. Therefore, as a measure to make the KEI calculated by the approximation method as close as possible to 111, the data selector (DSl) shown in Figure 2
The conversion coefficient on the long focal point side set at the input terminal (EI) of the camera may be set to a slightly smaller value (i.m.).

(Margin below) (J C1(J u (J (J (J IJ u I)
J u IJ CJ LJ IJ IJ IJ lj
1. J IJ lj Ij lj ++1 Multiplying circuit (7
) to calculate the drive amount for moving the focus adjustment lens (FL) to the in-focus position. The drive mechanism (8) selectively rotates the morph clockwise and counterclockwise based on the defocus direction data from the distance measurement processing circuit (6), and after decelerating the rotation, the clutch (1) t(2) ) to move the interchangeable lens (FL). The focus adjustment lens (FL) is connected to the encoder (10) linked to the drive mechanism (8).
) is moved by a predetermined amount, a pulse signal is output, and the counter (11) counts this pulse. Comparison circuit (9
) compares the data from the multiplication circuit (7) and the data from the counter (11), and when both data match, it is determined that the focus adjustment (FL) has moved to the in-focus position, and the drive mechanism (
8) outputs a motor stop signal.

In the embodiments described above, the circuit section of the present invention is formed by individual circuit elements.
Although the circuit section on the camera body side shown in Figure 1 and the entire lens information output circuit section shown in Figure 2 are constructed with microprocessors such as one-chip microcomputers, the automatic focus adjustment device of the present invention can be operated in a sequential manner. May be controlled.

(Effects of the Invention) The present invention sets the conversion coefficient at the reference focus position 1ii (long focus side) as logarithmically compressed data, outputs the relative movement amount from the reference focus position to the set focus position due to the magnification change operation, The configuration is such that the amount of change in the conversion coefficient per unit amount of movement can be set, the amount of change is obtained by multiplying the amount of relative movement and the amount of change in the conversion coefficient, and the amount of change is combined with the amount of change (IiI reference reference focal position focal side)
By adding the conversion coefficients, the conversion coefficients are logarithmically compressed and output as data to the camera body in response to the focal length changing operation, and the conversion coefficients read from the interchangeable lens are logarithmically expanded on the camera body side. Since the MATIJJ amount of the focus adjustment member is calculated from this data and the defocus amount, the conversion coefficient at the reference focal position (long focal length side) and the conversion coefficient change amount per unit movement amount can be set using the lens mirror. This can be implemented at the time the information output circuit is built into the body. Therefore, unlike in the past, it is no longer necessary to manufacture and store ICs including ROM for each lens, which reduces development costs, reduces existing λ1i negative Jim, and produces only one IC. Effective in reducing unit costs.

Further, according to the present invention, since the method is not a method of outputting fixed storage information of the ROM, there is an effect that the problem of the lead time until mass production being prolonged by one development period of the ROM can be eliminated.

In addition, even if the conversion coefficients change due to a partial change in the lens specifications, we will
This can be achieved by changing the setting of the conversion coefficient or the amount of change in the conversion coefficient M'l per 1i<positional fusion, which has the effect of increasing the degree of freedom in product improvement.

Since the conversion coefficients transmitted from the interchangeable lens to the camera body are logarithmically compressed data, an information output circuit that always calculates appropriate conversion coefficients in response to zooming operations can be easily realized. Then, on the camera body side, the conversion coefficients read from the interchangeable lens and converted into logarithmically compressed data must be logarithmically expanded. Therefore, the 1.1 number expansion was determined by an approximation method, which simplified the circuit or calculation algorithm.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a camera system with automatic one-point adjustment to which the present invention is applied, Figure 2 is a block diagram showing transmission of lens information, and Figure 3 is the relationship between lens adjustment information and encoder setting position. FIG. 4 is a circuit diagram showing the circuit configuration of the addition circuit and the multiplication circuit. CO+ t CO
E + t D E z・・・・・・Decoder, AI* BI* CIt DIt EI・・・・・・
...Lens specific information, DS+, DSz...
・・Data select, CItDJtEJ・・・・・・
...Amount of information change, ADD...Addition circuit, MLT...Multiplication circuit, ENC...
...Encoder.

Claims (3)

[Claims] (1) Receiving the light from the object to be focused that has passed through the interchangeable lens, calculate the amount of defocus corresponding to the amount of deviation of the imaging position of the object to be focused from the expected focal position, and based on this amount of defocus, In an automatic focus adjustment method in which a driving means on the camera body side is driven and the driving force is transmitted to a focus adjustment member of an interchangeable lens to move the imaging position, the amount of defocus is transmitted from the camera body to the interchangeable lens. The conversion coefficient for converting into a quantity is calculated on the interchangeable lens side as logarithmically compressed data corresponding to the focal length set by the magnification operation, and is serially output to the camera body. An automatic focus adjustment method characterized in that the amount of drive of a drive means is calculated from this data and the amount of defocus. (2) A focus adjustment member that moves the imaging position of the object to be focused by the focus adjustment optical system, and a drive means on the camera body side when attached to the camera body, and the driving force of the drive means is applied to the focus adjustment member. a transmission mechanism for transmitting the data to the drive means, a calculation means for calculating a conversion coefficient for converting the defocus amount into the drive amount of the drive means as logarithmically compressed data corresponding to the focal length set by the zooming operation, and this data. A variable magnification lens for automatic focus adjustment, characterized in that it is equipped with a data output means for serially outputting data to a camera body. (3) A detection means that receives light from the object to be focused that has passed through the interchangeable lens and detects an amount of defocus corresponding to the amount of deviation of the imaging position of the object to be focused from the expected focal position; A driving means that is connected to the transmission mechanism and drives a focus adjustment member to move the imaging position; and a driving means that logarithmically expands the conversion coefficient data sent out from the interchangeable lens, and calculates the driving amount of the driving means from this data and the defocus amount. An automatic focus adjustment camera comprising: calculation means for calculating .