JPH01201634A - Focusing device for zoom lens camera - Google Patents

Abstract

PURPOSE:To execute focusing with high accuracy by deriving a conversion coefficient from a storage means, based on a set focal distance which is detected, and also, deriving a lens moving amount based on an object distance and driving a focusing lens based on this operational value. CONSTITUTION:A lens moving amount stored based on an object distance which is measured by a non-TTL distance measuring means 1 is derived by an arithmetic means 5. Also, a conversion coefficient for converting a lens moving amount in a reference focal distance to a lens moving amount in each focal distance is stored in a second storage means 4, and a conversion coefficient stored based on a set focal distance which is detected by a detecting means 2 is derived by the arithmetic means 5. Moreover, by the arithmetic means 5, a focusing lens is driven based on the operational value of the lens moving amount in the focal distance from the lens moving amount and the conversion coefficient. In such a way, it is possible to cope enough even when curve data are comparatively small, and also, the number of divisions of distance data is large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to a focusing device for a zoom lens camera, more specifically, in a zoom lens camera having a non-TTL distance measuring means, the focus adjustment device adjusts the focusing lens according to zooming. The present invention relates to a focus adjustment device that automatically performs a focus adjustment operation.

[Prior Art] In a zoom lens camera that uses an inner focus method for focus adjustment, if the focal length differs even if the subject distance is the same, the extension position of the rear group lens will differ, so the amount of lens extension must be adjusted according to zooming. It has to change. Therefore, the applicant has determined the distance at infinity (cx3) for each focal length.

The focus adjustment device stores each curve of the amount of lens extension at the closest point, and calculates the amount of lens extension from each data of focal length and subject distance by dividing the distance from flash to closest point into 64 sections. proposed (patent application 1986-
No. 128745).

[Problems to be Solved by the Invention] However, the above focus adjustment device is applied to a video camera, and when applied to a silver halide film camera, the number of distance divisions is insufficient. Unable to adjust focus. Furthermore, in the above-mentioned apparatus, since curves of the lens extension amount tα are recorded for each of a plurality of focal lengths, it is necessary to use a microcomputer with a large storage capacity, which increases the cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a focus adjustment device for a zoom lens camera that can sufficiently cope with a case where distance data is divided into a large number of parts with a relatively small amount of curve data.

[Means and effects for solving the problem] The focus adjustment device for a zoom lens camera of the present invention is applicable to a zoom lens camera in which the amount of movement of the focusing lens from the reference position with respect to a subject image at the same distance changes depending on the set focal length. , as shown in FIG. 1, the amount of movement of the focusing lens with respect to the distance to the subject at at least one reference focal length is stored in the first storage means 3, and the non-TTL distance measuring means 1
When the subject distance is measured, the arithmetic means 5 calculates the stored lens movement amount based on the measured subject distance. Further, a conversion coefficient for converting the amount of lens movement at the reference focal length into the amount of lens movement at each focal length is stored in the second storage means 4, and the set focal length is detected by the detection means 2. Then, the stored conversion coefficient is determined by the calculation means 5 based on the detected set focal length. Then, the calculation means 5 performs a calculation to obtain the lens movement amount at the focal length from the lens movement amount and the conversion coefficient,
Based on this calculated value, the driving means 6 drives the focusing lens.

[Example] First, a basic system of a zoom lens camera to which the present invention is applied will be explained based on FIG. 2.

A CPU (Central Processing Unit) 11 is constituted by a one-chip microcomputer that controls the entire camera, receives a basic clock from an oscillation circuit 12, and starts operation by resetting a reset circuit 13.

The reset circuit 13 is activated when a battery is inserted and when a power switch (not shown) is turned on.

Works by turning off.

E2-PROM14 is in camera state (winding 1 frame, etc.)
It is a non-volatile memory that stores adjustment data (shutter control, lens drive).For this reason, even if the battery is removed, the camera can return to its previous state.
- The PROM 14 stores the amount of deviation in the amount of lens extension caused by variations in each lens, as will be described later. While data is being written to the E2-PROM 14, the reset operation of the reset circuit 13 is prohibited. E2-P
When the ROM 14 is set to read mode, the DX code is first input to the E2-PROM 14 via the DX terminal 15.
Subsequently, the data is input to the CPU 1l via the serial line. Thereafter, it is input to the E2-PROM 14, and then manually input to the CPU II via the serial line. After this, the data in the E''-PROM 14 is input to the CPU II.

The AFIC 16 is a phase difference type AF (autofocus) sensor provided at a non-TTL distance measurement position, and its distance data is sent to the CPU II. The CPU 11 turns on the auxiliary light lamp 17 in accordance with the operation of the APIC 16 when the photometric value is below a certain value (dark). The EXT terminal 18 is a connection terminal for an external device, and an optional automatic adjuster or the like is connected thereto.

E2-PROM14. AF I C16 and EXT terminal 18 use the CPU II board for H effect.
It is connected to the same serial line and exchanges data with the CPU 11 through serial communication.

5-W19 is a camera operation switch, which includes a release switch, a mode changeover switch, and the like. The LED 20 is a light emitting diode located in the viewfinder, and includes a light emitting diode for displaying a strobe light emission notice, 9 focus display, and the like. LCD
21 is a liquid crystal display board for displaying the number of frames, camera mode, etc. The IFIC 22 is an interface I that has a decoding function that performs photometry with a photometry unit 23 and selects a motor in the camera based on instructions from the CPU II.
It is C.

M24. M25. M26 are respectively S
ν 2 Yatsuta Motor 9 winding/rewinding motor, zoom motor, IFIC22
The motor is driven via the motor driver IC 27 by the decoded signal. M24 drives the lens during normal rotation,
The shutter is driven during reverse rotation. When driving the lens,
The reset position of the lens is confirmed by the on (open) state of the switch 28, and the control position is confirmed by the number of pulses of the photointerrupter 29. When the shutter is driven, the reset position is confirmed when the switch 30 is on, and the aperture control is
This is done by adjusting the pulse width of 24. This adjustment value is stored in R2-FROM14. M
25 winds the film in the forward direction and rewinds the film in the reverse direction. One-frame advance control of the film is performed by counting the number of pulses of the photointerrupter 31. Photo interrupter 29.
31 are turned on only when M 24° or M 25 is selected, respectively, and the photointerrupter output is input to the CPU II via the IFI C22. The zoom position of M26 can be detected by a zoom encoder 32.

DATEM33 is a date module that records data such as the date and hour on the film, and 5TRB34 is a strobe.

Here, the zoom encoder 32 will be explained. Third
As shown in the diagram, the zoom encoder 32 has a zoom ring 40.
It consists of a thin film-like conductor pattern that is integrally attached to the outer peripheral surface of the conductor, and a conductive contact piece and a resistor group that are in sliding contact with the conductor pattern. M2
6 (see FIG. 2) rotates, the zoom ring 40 rotates, and a cam (not shown) inside the zoom ring moves the zoom lens back and forth, changing the focal length. Focal length is zoom ring 4
It is obtained by detecting the position of the zoom encoder 32 on 0.

Eight contact pieces T for detecting the position of the zoom encoder 32. - T7 is attached to the fixed frame 41, and is connected to the ground terminal AD of CPUII and the resistor R1, respectively.
, R2, R3, R4゜ND Connected to one end of each of R5, R6, and R7. The value of the above resistance is (R/R) - (R3/R) - (R5/
R6)-1,67. The other ends of the resistors R1 and R2 are connected together and
Connected to the D conversion terminal AD. The MA ends of resistors R3 and R4 are also connected to each other and connected to A/D conversion terminal A of CPU II.
The other ends MB of resistors R5 and R6 are similarly connected to A/D conversion terminals AD and 1Mo. The other end of resistor R7 is the CPU II reference voltage Vre.
It is connected to the terminal ADVref' to which f' is applied. This resistor R7 is a protective resistor in case the reference voltage V rcf' is short-circuited to the ground terminal GND.

The conductor pattern of the zoom encoder 32 is shown expanded in FIG. 4(A). The above 8 contact pieces T-T
The contact piece T at both ends. The conductive patterns Po and P7, on which the conductive patterns Po and T7 are in sliding contact, respectively, are formed of a continuous conductive material around the entire zoom area along the circumferential direction of the zoom ring 40, and are supplied with the ground potential GND and the reference voltage V rer, respectively. ing.

Pattern P1 of each row in which the contact piece Tl-T6 between them contacts
~P6 are each made of an isoelectric body formed in a discontinuous shape in the circumferential direction of the zoom ring 40 as shown. Electrically, the patterns P1 to P6 in each column are partially the conductive pattern P, as shown in the figure.

An electrode pattern PG (shown with fine diagonal lines in the upper right corner) connected to the ground potential GND and applied with the ground potential GND,
It consists of an electrode pattern Pv (shown with coarse diagonal lines downward to the right) connected to the conductive pattern P7 and applied with the reference voltage Vrer, and an electrodeless part where no electrode pattern exists.

Therefore, when the contact pieces T1 to T8 slide on the patterns P1 to P6 of the zoom encoder 32 as the zoom ring 40 rotates, each of the patterns P1 to T8 slides on the patterns P1 to P6 of the zoom encoder 32.
~Due to the shape of P6, the contact pieces T1 to T6 are attached to the zoom ring 4.
64 combinations of code signals from the start point 0 to the end point 63 of the zoom encoder position are detected according to the rotational position of the zoom encoder.

Note that in FIG. 4(A) above, the electrode pattern P c
Since the dotted portion on , Pv is an auxiliary pattern for preventing malfunction, basically the electrode pattern in this portion may be removed to form an electrodeless portion.

FIG. 4(B) shows 64 code signals of the patterns P1-P6 read by the contact pieces T1 to T6. In this code signal table, when the contact pieces T1 to T6 are applied with the reference voltage Vrer, they are "1", and when they are applied with the ground potential GND, they are '0'.

Here, if we pay attention only to patterns Pl and R2, these two
By reading two patterns by contact pieces T1 and T2, 4
two states (0,0), (0,1).

(1, 1), (1, 0) can be determined, so the A/D conversion terminal AD of CPU II can be determined by the resistors R1 and R2.
ZMA can determine four levels as shown in the table below.

In other words, the input to the A/D conversion terminal ADZM by the combined resistance of resistors R1 and R2 is the reference voltage Vref.
When is set to 1, R, + R2-1,67, so as shown in the table above, 0-0.22, 0.27-0
．． It is divided into four levels: 47.0.52~0.72.0.77~l. CPU II A/D conversion terminal AD
Since zMA has high impedance, the above pattern Pl
, P2, if one of the patterns is off, the level will be that of the other pattern.

Other two A/D conversion terminals AD of CPUI 1
The configuration related to AD is also the same, and ZMB'
There is ZMC.

Since the zoom encoder 32 has a pattern of six columns, it is possible to detect a total of 64 (0 to 63) encoder positions. Encoder position 1 is the wide (wide-angle) end position, encoder position 60 is the tele (telephoto) end position, and encoder position 63 is the macro position. Encoder positions 61° and 62 are intermediate areas where no photographs can be taken, and encoder position 0 is an out-of-wide position.

As described above, each A/D conversion terminal ADZMA'AD
ZMB that divides the input to AD into 4 levels
' ZMC makes post-processing very easy. That is, the result of A/D conversion is a 6-bit signal in total, of which the upper 2 bits are "00" and "01".

It has already been divided into four levels corresponding to "10" and "11" (binary numbers), so there is no need to newly divide the A/D conversion input into levels. Also, the variation range is very large, so the resistance varies.

Even if there are variations in the reference voltage V ref', stable results can always be obtained.

Further, as shown in FIG. 3, resistors R1 and R2 are connected to each other and connected to the A/D conversion terminal A D Z of CPU 1.
By suspending the other end connected to M to the reference voltage V rcr via a high resistance value resistor R8, the contact piece T
1. Even if both T2 are in contact with the non-electrode portions (OF, F), it can be determined as "11" (binary number). Such a configuration has two patterns P1. This helps prevent malfunctions when the distance between P2 is narrow, and also simplifies the structure of the electrode pattern.

Next, calculation of the amount of lens extension for autofocus will be explained. Distance data 1 of the reciprocal of the subject distance Ω
/Ω is given to the CPU 1 by the AFIC 22 as data of 6 integer bits and 6 decimal bits. Since this camera is of an inner focus type, as shown in FIG. 6, even at the same distance, the amount of lens extension (lens extension pulse) S differs depending on the zoom position (focal length). That is, in Fig. 6, the tele end is standard.

The curves in each state at the wide end are representatively drawn, but the lens is only extended so that there are 60 different lens extension curves from wide end position 1 to tele end position 60. . Tatashi,
Since CPU II does not have enough capacity to store all curves, 20 points of lens extension ff1s from 0 to 20, where distance data 1/N is an integer, are stored in ROM only for curve 45 at the tele end. There is. The data of this lens extension amount S at the telephoto end is ST.

(J=0 to 20). The curves for each focal length other than the tele end are on a line that internally divides the tele end curve 45 at a certain ratio for any distance data 1/R, so they are multiplied by the zoom factor of the tele end curve 45. By doing this, it is possible to approximately obtain the curves for each focal length other than the telephoto end. Therefore, in the ROM in CPUI I, if the zoom coefficient for each focal length is Cf, the zoom coefficient Cf 1 (i-1 to 60) corresponding to 60 curves is 2.
billion. That is, the zoom coefficient Cf corresponding to the encoder value i of the zoom encoder 32 is stored in the ROM within the CPU 11.

Therefore, if you now operate the zoom ring 40 to set the zoom encoder value i, this set encoder value i
The zoom coefficient Cf corresponding to the current value is read out from the ROM. On the other hand, the lens extension amount at the telephoto end is read out from the ROM in accordance with the subject distance measured by the APIC 16.

Based on this lens extension amount at the telephoto end, the CPU II performs a calculation using the zoom coefficient Cf, and the lens extension amount at the set zoom encoder value i is determined.

Here, the integer part of the data of AFIC22 is a.

Assuming that the decimal part is b, the lens extension amount (extension pulse) S at the zoom encoder value i can be obtained by the following simple formula.

S (b (STa+1-8Ta) +ST l ・Cf1 (1) Such a calculation formula can be calculated satisfactorily even on a 4-bit microcomputer with few calculation instructions. In the macro mode, the curve is completely different from the one shown in Figure 6, so the macro curve is specially stored in the CPU II. The same is true.

The above is a case where the zoom lens is as designed, but in reality there are variations for each lens, so the curve shown in Figure 6 will shift upward or downward in parallel due to this variation. result. Of course, this amount of parallel movement differs depending on the lens, but
Even if the amount of deviation is adjusted to 0 at the wide end position, the amount of deviation will not be 0 at the zoom positions in between.
The result will be as shown in the figure. As can be seen from FIG. 7, since the adjustment has been made at the wide end position 1 and the telephoto end position 60, the amount of deviation is O.

Therefore, in this camera, the above deviation data is stored in the E2-PR0M14 as five data Dk (k=0 to 4). This stored data is small (Zoom encoder value 0 where the lower 4 bits of the A/D converted value are all "0000" (OH in hexadecimal, the same applies below)
, 16 (IOH), 32 (20H), 48 (3'
There are 5 data: OH), 64 (40H), and each is different. , Dl.

D2. D3. Store as D4. However, the points where the zoom encoder position is 0 and 64 cannot be measured.
At all times, 1 (IH), 16 (IOH)
, 32 C20H), 48 (30H).

60 (3CH), and from the measurement data D' when the zoom encoder position is at the wide end position 1 and the measurement data D4' when the zoom encoder position is at the tele end position 60, the number of deviation pulses at each point is calculated.
Data D at point 4. - Find D4. That is, Do and D4 are determined by the following equations (2) and (3).

Do-Do'-(Dl-D.')/15...(2
)D4-D3+(D4'-D3)/12......(
3) Then, based on the calculated deviation data of the five points at the zoom encoder position i, the number of deviation pulses at other unstored zoom encoder positions i is determined by interpolation calculation.

Here, the delivery pulse movement QZS in the case of the zoom encoder 1jIi is obtained as follows.

Zs −D, + (D(,+1)−D,)・ib...
(4) In equation (4), ia is an integer value of the upper 2 bits when the zoom encoder value 1 is expressed in binary, and ib is a decimal value of the lower 4 bits.

The delivery pulse movement QZs in equation (4) above can also be sufficiently calculated with a 4-bit microcomputer.

According to the above calculation results, the actual payout amount is S+Zs. Furthermore, as is clear from the above equations (2) and (3), even if the adjustment at the tele end position and wide end position is off (even if it is not 0), this can be adjusted from E2-FROM1.
Correction can be made by storing it in 4.

As mentioned above, in this embodiment, first, the APIC16
Obtain distance information, use that data to search for the lens extension amount data for telephoto mode stored in CFULL, then obtain the zoom coefficient Cf from the zoom encoder value i, perform calculations in CFULL, and find the current focal point. Find the amount of lens extension at the distance. Furthermore, here, the variation data D for each camera is calculated from the zoom encoder value i by E2-
The lens is read out from the FROM 14, and the above-mentioned lens extension amount is corrected to obtain the actual lens extension amount.

[Effects of the Invention] As described above, according to the present invention, it is possible to accurately calculate feedout data for an almost infinite number of distance divisions with a relatively small amount of stored data. The calculation formula is also very simple. In particular, since no mechanical cam is required, the structure is simple and the cost can be reduced significantly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the outline of a focus adjustment device for a zoom lens camera according to the present invention, FIG. 2 is a block diagram showing a basic system of a zoom lens camera to which the present invention is applied, and FIG. , an electric circuit diagram showing the configuration of the zoom encoder in FIG. 2 above, and FIGS. 4(A) and (B) are developed diagrams of the encoder pattern on the zoom ring in FIG. 3 above, and its relation to the encoder position. Figure 5 is a diagram to explain the lens extension amount with respect to the AF sensor output. Figure 6 is a diagram to explain the correction movement of the lens extension amount with respect to the zoom encoder position. It is. 1...Non-T T L 13 range means 2...
...... Detection means 3 ..... First storage means 4 ..... Second storage means 5 ..... Calculation Means 6... Drive means 11... CPU (first storage means, second storage means, calculation means)

Claims (1)

[Claims] (1) In a zoom lens camera in which the amount of movement of the focusing lens from the reference position relative to a subject image at the same distance changes depending on the set focal length, a non-TTL distance measuring means for measuring the subject distance and the above set focal length are detected. a detection means; a first storage means for storing the amount of movement of the focusing lens relative to the distance to the subject at at least one reference focal length; a second storage means for storing a conversion coefficient to be converted; a conversion coefficient is obtained from the second storage means based on the detected set focal length, and the conversion coefficient is calculated from the first storage means based on the measured subject distance; Determine the amount of lens movement from the means,
A focal point of a zoom lens camera, comprising: a calculating means for calculating from the lens movement amount and the conversion coefficient; and a driving means for driving the focusing lens based on the calculated value of the calculating means. Regulator.