JPH06205260A - Camera - Google Patents

Abstract

PURPOSE:To provide the camera by which object distance information closer to an actual value with high accuracy is obtained through zoom tracking calculation. CONSTITUTION:Zoom tracking control is executed by a zoom tracking control block 7 in the zooming operation in this camera. Furthermore, when distance information is required, the zoom tracking control block 7 reads data relating to a tracking curve stored in a memory 15 and obtains a difference between a best focal position in an actual value of the focus lens 4 and a designed best focal position based on the tracking data and calculates a distance corresponding to the actual value of the focus lens 4 based on the difference data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly, to a camera which performs zoom tracking control and which can obtain highly accurate subject distance information.

[0002]

2. Description of the Related Art Conventionally, in many video cameras and the like, a zoom tracking control operation for correcting a focus position is performed during zooming of a zoom lens. FIG. 25 is, for example, a zoom tracking curve showing changes in the focus lens correction position with respect to the position of the variator lens in the zoom lens in the zoom tracking operation (hereinafter referred to as the zoom lens position). For each zoom lens position, the focus lens is moved along the curve shown in FIG.

Conventionally, various types of methods have been proposed as zoom tracking control methods using the zoom tracking curve of FIG. For example, "NATIONAL TECHN
ICAL REPORT "(VOL. 37 NO.3 JUN. 1991, P338-344)
The zoom tracking method of the zoom lens of the video camera described in () reads the table data of the zoom tracking curve stored in the memory and interpolates the table to calculate the appropriate amount of movement of the focus lens and perform tracking. It is a thing.

The zoom tracking method based on the table interpolation will be described in detail with reference to FIG.
Of the 5 zoom tracking curves, the reference subject distance L1 (= ∞) and the subject distance L2, and further the distances L1 and L2
It is the diagram which extracted and showed the tracking curve with respect to the to-be-photographed object distance L3 interpolated between. The points A1 and A2 indicating the focus lens positions with respect to the object distances L1 and L2 at the zooming position Za are set as
Points B1 and B2 indicating the position of the focus lens with respect to the object distances L1 and L2 in b. Note that these data are assumed to be stored in the memory applied to the camera. Then, the positions A1, B1 and A2, B2
The amount of extension is set to values Db and Dd as shown in the figure.

Now, it is assumed that the zoom lens is at the position Za and the focus lens is located at the position A3 on the tracking curve of the object distance L3. The position A3 is the focus lens position A1 with respect to the zoom position Za.
A2 extension amount Db and focus lens positions A1, A
It can be relatively defined from the delivery amount Da of 3. Therefore, it is assumed that the zoom lens position changes to Zb. Assuming that the tracking curve of the object distance L3 changes so as to keep the delivery ratio Da / Db, which is the ratio of the delivery amount by the focus lens positions A1 and A2, at a constant value, the delivery amount from the position B1. D
c is obtained, and as a result, the position B3 is obtained. The feed ratio Da / Db, which is the constant value, is 1 which is the reference value of the tracking interpolation calculation applied to the embodiment described later.
Correspond to one.

However, what is actually manufactured includes variations in manufacturing of the lens and the lens frame. That is, a design value tracking curve LT0.5 that gives an appropriate position determined by the design shown in FIG.
A tracking curve that gives a proper position in an actual product with respect to (curve for subject distance of 0.5 m) to LT∞ (curve for subject distance at infinity) is, for example, a design value tracking curve LT as shown in FIG. The actual value tracking curve deviates from LP0.5 to LP∞. When tracking control is performed, the actual value tracking curve L
Areas R1, R2, R3 between lines to which P corresponds respectively
The tracking drive curve is obtained by interpolating the inside with a constant ratio, and tracking is executed. Therefore, correct tracking control can be performed as long as the curve shapes of the design value curve LT and the actual value curve LP match.

For a camera in which the curve shapes of the design value curve LT and the actual value curve LP in tracking control do not match, the zoom of the camera of Japanese Patent Application No. 4-288921 previously proposed by the present applicant is proposed. The tracking control method is effective. In this tracking control, the change in the difference between the zoom tracking curve, which is the designed value in design, and the actual tracking curve is approximated by a quadratic curve.
Tracking control is performed along the next curve.

As shown by the tracking curve in FIG. 29, the actual value tracking curve LP and the theoretical design value tracking curve LT are the zoom position at the wide end (hereinafter referred to as the W end) and the telephoto end. It is assumed that the actual tracking curve LP is adjusted at the end (hereinafter referred to as the T end) so as to match the theoretical tracking curve LT.

At the zoom lens position X1 in FIG. 30, the operation when the focus lens is at the position P1 which is the in-focus position and then zooming to the zoom lens position X2 will be described. First, on the actual value curve LP. The focus position P2 on the design value curve LT where the W and T ends coincide with the focus lens position P1 which is the position is obtained. This operation is the same as the above-mentioned Japanese Patent Application No. 4-288921.
No. WT inter-WT correction calculation.

Next, the focus lens position P3 with respect to the zoom position X2 is obtained along the design value zoom tracking curve LT. Therefore, the "WT correction calculation" at the zoom lens position X2 is performed again. That is, the correction position P4 of the focus lens on the actual value curve with respect to the focus position P3 on the design value curve LT is obtained. This position P4 is a point at which focusing can be actually obtained at the zoom lens position X2. Finally, the focus lens is driven from the position P1 to the zoom tracking correction position P4, and one zoom tracking operation is completed.

It should be noted that the subject distance giving the actual tracking curve LP shown in FIG. 29 and the subject distance giving the tracking curve LT of the design value corresponding to the curve LP and having the W end and the T end coincident with each other are not necessarily the same. Not something to do. For example, as shown in FIG. 29, the subject distance 2
Actual tracking curve LP2 for m and W end, T
The design value tracking curves LT1 and LT2 whose ends match are
The curve exists between the design value tracking curves LT1 and LT2 corresponding to the subject distances of 1 m and 2 m, and is different from the curve LT2 corresponding to the distance of 2 m.

[0012]

However, the above conventional table interpolation method or the above-mentioned Japanese Patent Application No. 4-28892.
In the zoom tracking operation by the “WT correction calculation” of the first camera, although the correction drive to the predicted focus position of the focus lens is performed, the design value tracking curve LT used for each tracking control is It does not necessarily correspond to the actual subject distance.

Therefore, when the proper light emission control in the strobe light emission and the display of the object distance in the viewfinder are performed, there is a problem that accurate object distance information cannot be obtained by the tracking calculation using the design value tracking curve LT. In particular, in a camera that performs focusing control based on the contrast information included in the image signal of the image sensor, the subject distance information itself cannot be obtained, which is particularly unsatisfactory. However, if a large number of zoom tracking curves corresponding to actual values are associated with subject distance information and stored in the memory, the memory capacity becomes too large, which causes a practical problem.

The present invention has been made in order to solve the above-mentioned inconvenience, and obtains distance information corresponding to the actual value of the focus lens proper position by zoom tracking calculation, and if necessary, accurate object distance. It is intended to provide a camera capable of obtaining information.

[0015]

The camera of the present invention has a zoom function as a design value of an appropriate position of the focusing lens for maintaining a focused state when the magnification of the zoom lens changes under a constant object distance. The zoom tracking data holding means for holding tracking data, and the zoom tracking data holding means for holding the actual value of the proper position of the focusing lens for maintaining the in-focus state when the magnification of the zoom lens changes under a constant object distance. And a calculating unit for calculating a subject distance corresponding to an actual value of the proper position of the focusing lens calculated by the correcting unit. It is characterized by that.

[0016]

When obtaining the subject distance information, the subject distance corresponding to the actual value is calculated based on the proper position of the focusing lens calculated by the correction means.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main configuration of a video camera of the present invention, and the camera of the present embodiment is a camera capable of performing zoom tracking control. The zoom tracking control is performed by the conventional "table interpolation calculation", "WT correction calculation", and the like. Then, the focusing control of the present camera is of a type in which the focus determination is executed regarding the level of the high frequency component included in the video signal. In this method, the distance information itself of the subject cannot be directly obtained. Therefore, this camera obtains subject distance information using the tracking curve used for zoom tracking control when subject distance information is needed during flash photography or when distance information is displayed in the viewfinder. Is possible.

In the focusing operation of the camera of this embodiment, a manual focus (hereinafter referred to as M
And a second mode F, which is a second priority mode that prioritizes an autofocus (hereinafter, referred to as AF) operation, and an MF mode that is a first priority mode that prioritizes an operation. , M temporarily during F mode operation
It is possible to switch to F processing. Further, it is a camera that enables the focusing target area designated in the MF mode to be the focusing target area of the AF processing during the F mode operation as it is.

Therefore, the camera described above captures a subject image and outputs a video signal, and a camera unit 101 and a camera unit 1.
01, a recording unit 102 for recording the video signal output from the recording medium 101 on a predetermined recording medium, the camera unit 101, and the recording unit 102.
And a recording / standby (hereinafter referred to as REC / STANDBY) switch 104 for instructing a recording operation and a recording standby operation.

The main structure of the camera section 101 is shown in FIG.
As shown in the block diagram of FIG. 3, the first lens group 1 is a fixed lens group which is a zoom lens having a four lens group, the zoom lens is a second lens group for zooming 2, the third lens group 3 is a fixed lens group, and the third lens group is a third lens group. Focus lens 4 of the fourth group lens and subject 2
A CCD 5 for converting an image of 0 into an electric signal, a video circuit 6 for converting an image pickup signal of the CCD 5 into a video signal and outputting the video signal to a recording circuit (not shown), and a zoom switch for instructing a zoom operation in the tele and wide directions. 12, 13 and a zoom switch detection block 14 for recognizing that the zoom switch has been pressed by the output signals of the zoom switches 12 and 13 and the zoom direction, and an EEPROM or the like, which is a zoom tracking data holding means of a designed value. And the memory 15, which is a zoom tracking control block 7 for performing zoom tracking control based on signals from the zoom switches 12 and 13, and the zoom lens drive block for driving the zoom lens 2 based on signals from the zoom switch. 8 and the amount of movement of the zoom lens 2 are detected and the signal is A zoom encoder 9 that is input to the king control block 7, a drive block that drives the focus lens 4 based on the outputs of the zoom tracking control block 7 and the AF control block 10, and includes a stepping motor and the like. The focus lens drive block 11 and the AF control block 10 described later are included.

Although the third lens group 3 is fixed in this embodiment, it may be moved to assist the focus lens 4 in accordance with the function of the zoom lens 2. Further, the moving position of the focus lens 4 does not need to be detected because the drive block 11 is composed of the stepping motor, so that the encoder for the focus lens is unnecessary. The zoom tracking control block 7 calculates a distance corresponding to the actual value of the correct position of the focus lens calculated by the correction means for performing a correction calculation based on the zoom tracking data stored in the memory 15. It also has a built-in calculation means.

The AF control block 10 extracts from the video circuit block 6 AF evaluation information indicating the degree of focusing included in the video signal, in this case, contrast information in the hill climbing focusing method, and drives the focus lens. A block for outputting an AF control signal of the focus lens to the block 11, a focusing target information holding unit that holds information regarding a target of focusing adjustment in an MF mode described later, and the focusing target information holding unit. A focus object recognition unit is also built in for starting the focus adjustment operation by AF for the focus adjustment target corresponding to the held information in (3).

The detailed structure of the AF control block 10 is as follows.
As shown in FIG. 3, a BPF (bandpass filter) 21 for taking in a video signal, an A / D conversion circuit 22 for A / D converting the high frequency signal extracted by the BPF 21, and the A
The D / D conversion output is displayed on the shooting screen 40, for example, in the divided area A.
An area division circuit 23 that divides the image into 9 to I (see FIG. 4),
The extracted signal corresponding to each area is integrated, and the integrated value is AF-converted.
An integration circuit 24 for outputting to the arithmetic circuit 25, a tracking circuit 28 for detecting the tracking area of the corresponding moving subject by taking in the brightness information, color information, and angle of view information of the object, and the integrated value from the integration circuit 24. An area having a higher AF evaluation value obtained more is set as an AF target area, or a tracking area from the tracking circuit 28 is set as an AF target area which is a focusing target area, and a lens control system is combined with the AF target area. AF calculation circuit 25 for performing focus control, MF operation and A
An MF / AF switch 32 which is a mode switching means for instructing a mode switching of the F operation, and an MF switch 30 for short-distance focusing of a short-distance direction operation means for instructing focusing in the short-distance direction in the MF mode.
Similarly, in the MF mode, the MF switch 31 for long-distance focusing of the long-distance direction operation means for instructing focusing in the long-distance direction, and the MF / AF switch 3
2, a switch detection circuit 29 that converts the output from the MF switches 30 and 31 into a control signal and outputs the control signal to the AF operation circuit 25, and a display of information such as the AF operation mode and AF area executed by the AF operation circuit 25. The display circuit 26 outputs data to an electronic viewfinder (hereinafter referred to as EVF) 27, and the EVF 27.

The MF switch 30 and the MF switch 31 are both two-stage operation type switches, and when a finger touches the operating portion of these switches, first, the first
It is composed of capacitance-type first-stage switches 30a and 31a that output a stepwise operation signal, and second-stage switches 30b and 31b that output a second-step operation signal when further pressed. The switches 30a and 30b may be first-stage switches of the two-stage push operation switch instead of the capacitance type. In addition, the MF switches 30, 3
1 may be a switch structure that interlocks with the rotating ring.
In this case, the switches 30a and 31a are capacitance-type switches that detect that a finger touches the ring, and the switches 30b and 31b are switches that output a pulse signal as the ring rotates.

The calculation processing operation of the object distance information of the camera of the present embodiment having the above-mentioned configuration will be described. In this calculation process, zoom tracking calculation or the like is performed, but at that time, the zoom lens 2 and the focus lens 4 are not directly driven, but only the zoom tracking calculation or the like is performed to calculate the corresponding object distance information. Only do.

FIG. 5 is a diagram showing an example of the zoom tracking curve of this camera. The horizontal axis is the position of the zoom lens 2, the W end position is ZW, and the T end position is ZT.
And Further, the current zoom lens position is ZS.
The vertical axis represents the position of the focus lens 4. The tracking curves LT ∞, LTb, and LTa are design value tracking curves for the subject distances ∞ (infinity), 2 m, and 1 m, respectively. The W and T ends of the tracking curve LTa are set as tracking points PE and PC.
Further, the tracking points PD and P∞ at the T end of the design value curves LTb and LT∞ are set. Then, the tracking point PC,
The focus lens positions with respect to PD are FT1 and FT2. Furthermore, the tracking point P ∞ and the tracking point P
The focus lens position difference between C and PD is XT1 and XT2. On the other hand, the value of the difference between the focus lens positions of the tracking points LTa and LT∞ at the W end is XW1.

Further, the focus lens position which is actually in focus at the current zoom lens position ZS is FS0, and the actual value tracking curve passing through the tracking point PA is LPb. The tracking points at the W and T ends of this curve are adjusted in advance and coincide with the points PE and PC on the design value curve LTa close to the curve. Then, the tracking curve designed by the focus lens 4 to focus on the distance of the object in focus is the design curve LTb. In addition,
Tracking curves LPb, L for zoom lens position ZS
The tracking points on Ta and LT ∞ are PA, PB and PS. Then, the focus lens positions with respect to the tracking points PA and PB are set to FS0 and FS1. Further, the value of the difference between the focus lens positions of the tracking points PB and PS is XS1.
And

The flow of the distance information calculation process shown in FIG. 6 will be described by applying the values on the tracking curve of FIG. 5 above. First, in steps S1 and S2, the current focus lens position FS0 and zoom lens position ZS are shown. To read. In step S3, the "WT correction calculation" process is performed,
Select the design value curve LTa where the W and T ends match,
The focus lens position FS1 on the zoom lens position ZS of the curve is calculated. The "WT correction calculation" process is the same as the process described in the zoom tracking control system of the camera of Japanese Patent Application No. 4-288921.

Then, in step S4, the calculation reference value is calculated. As the calculation method of the calculation reference value, there are three kinds of methods as will be described later, and the reference extension ratio Da / Db by the table interpolation calculation or the curves LTa and LT∞ at the W end (zoom lens position ZW). The difference XW1 between the upper focus lens positions is obtained. Then, in step S5, the zoom lens position ZT at the T end is fetched. In step S6, zoom tracking calculation along the design value curve LTa is performed to obtain the focus lens position FT1 at the zoom lens position ZT. This calculation method also corresponds to the process of step S4 described above, as will be described later. There are three methods. Then, in step S7, based on the focus lens position FT1, a deviation of the amount of extension from the focus lens position FT2 at the T end on the design value curve LTb corresponding to the currently focused object distance is obtained, and the focus is calculated from the value. Find the lens position FT2. The calculation formula for obtaining the deviation of the feeding amount is: deviation of the feeding amount = FT1−FT2 = P × XT1 + Q ...
………… Indicated by (1). However, the above values P and Q are values unique to each lens, are measured at the time of assembly adjustment, and are stored in the EEPROM or the like.

Then, in step S8, a corresponding object distance L2 is obtained from the focus lens position FT2. Its calculation formula, L2 = over (f ² / XT2) ....................................... and (2). In step S9, the data of the subject distance L2 is output to the strobe control system (not shown) or the display circuit 26. After that, this processing ends.

Now, three methods of the subroutine processing called in the above step S4 and step S6 will be described. First, the first method is an operation method of performing zoom tracking calculation by obtaining a reference extension ratio which is an operation reference value for zoom tracking calculation by table interpolation. 7 and 8 are flowcharts of subroutines "calculation of calculation reference value" and "zoom tracking calculation" which are called in steps S4 and S6, respectively. In addition, when adopting this method, RO
It is necessary to store 8 to 10 tracking curve data in the memory such as M for table interpolation.

Subroutine "calculation of calculation reference value" in FIG.
In step S11, first, in step S11, a corresponding design value tracking curve, for example, the curve LTa in FIG.
It is checked which of the areas (areas) R3, R2 and R1 indicated by. In step S12, the focus lens positions above and below the corresponding area are read. For example, if the area is the area between the curves L2 and L1 shown in FIG. 26, the values of the focus lens positions FA2 and FA1 at the tracking points A2 and A1 are read. In step S13, the difference between the values of the lens positions FA2 and FA1 is calculated, and the feeding amount Da is calculated.
Ask for. Further, in step S14, the zoom lens position Z
Focus lens position FS on curve LTa above S
1, that is, when the curve is on the curve L3 in FIG. 26, the difference between the lens position FA3 and the focus lens position FA1 is calculated to obtain the extension amount Db. Subsequently, in step S15, a calculation reference value for tracking calculation, here, a reference payout ratio Da / Db is calculated.

Next, the processing of the subroutine "zoom tracking calculation" will be described. First, step S21
At, the focus lens positions FB2 and FB1 of the tracking points B2 and B1 of the tracking curves L2 and L1 on the zoom lens position Zb are obtained (see FIG. 26). In the case of the present embodiment, the zoom lens position Zb corresponds to the zoom lens position ZT at the T end in FIG. In step S22, the difference between the lens positions FB2 and FB1 is calculated to obtain the extension amount Dd. Further, step S23
26 and the standard extension ratio Da / Db obtained by the "calculation of the calculation reference value" subroutine in FIG. 7, the extension amount Dc at the zoom lens position Zb in FIG.
Is calculated. In step S24, the target focus lens position FB3 on FIG. 26 is obtained from the lens position FB1 and the extension amount Dc. This lens position FB3 is shown in FIG.
Above, the tracking point P at the T end of the zoom lens position
This corresponds to the focus lens position FT1 with respect to c.

Next, the second method of the three methods of the processing of steps S4 and S6 is based on the tracking curve data at the object distance ∞ and the extension ratio corresponding to each zoom position. This is a calculation method in which the amount of W edge extension, which is a calculation reference value, is obtained and zoom tracking calculation is performed. 9 and 10 show steps S4 and S6, respectively.
Sub-routine called "Calculation of calculation reference value",
It is a flowchart of "zoom tracking calculation."
When this method is adopted, it is necessary to store the tracking curve data at the object distance ∞ and the feed ratio data (ratio DATA) which is the ratio of the feed amount to the W end feed amount in a memory such as a ROM. There is. The details of the feeding ratio data and the like are described in Japanese Patent Application No. 4-268877.

Subroutine "calculation of calculation reference value" in FIG.
In step S31, first, in step S31, the designed focus lens position FS1 corresponding to the actual focus lens position FS0 and the data stored in the ROM that correspond to the object distance ∞ at the zoom lens position ZS. Feed amount ∞DATA (ZS) and feed amount XS1 (Fig. 5
See). In step S32, the W-end feed-out amount XW1, which is a value corresponding to the zoom lens position ZS, and which is the calculation reference value, is obtained from the feed-out ratio DATA (ZS) stored in the ROM and the feed-out amount XS1. The process ends.

Next, the processing of the subroutine "zoom tracking calculation" shown in FIG. 10 will be described. First, in step S35, the feed amount XT1 at the T end in FIG. 5 is obtained from the feed amount XW1 corresponding to the W end and the ratio DATA (ZT). In step S36, the target focus lens position FT1 is calculated from the amount of extension XT1 at the T end and the amount of extension ∞DATA (ZT) stored in the ROM at the subject distance ∞, and the processing of this subroutine ends.

Subsequently, of the three methods of the processing of steps S4 and S6, the third method is the tracking curve data at the object distance ∞,
This is a calculation method in which the zoom tracking calculation is performed by obtaining the W-end extension amount that is the calculation reference value from the extension ratio calculated from the coefficients α and β corresponding to each zoom lens position.
11 and 12 are flowcharts of subroutines "calculation of calculation reference value" and "zoom tracking calculation" which are called in steps S4 and S6, respectively. When this method is adopted, the tracking curve data at the subject distance ∞ and the coefficients α and β for obtaining the extension ratio corresponding to each zoom lens position are stored in the memory such as the ROM.
It is necessary to store and store the feed-out ratio data (ratio DATA (ZT)) which is one data for the W-end feed-out amount at the T-end. The details of the feeding ratio data and the like are described in Japanese Patent Application No. 4-268877.

In the subroutine "calculation of calculation reference value" of FIG. 11, first, in step S41, the designed focus lens position FS1 corresponding to the actual focus lens position FS0 and the data stored in the ROM are used. Therefore, the extension amount XS1 (see FIG. 5) is obtained from the extension amount ∞DATA (ZS) corresponding to the object distance ∞ at the zoom lens position ZS. In step S42, the zoom lens position ZS corresponding value, the coefficient .alpha. (ZS) and the coefficient .beta. (ZS) for obtaining the ratio DATA (ZS), and the ratio DATA (ZS) which is the feed ratio from the feed amount XS1. Ask for. Further, in step S43, the W-end feed-out amount XW1, which is a calculation reference value, is obtained from the feed-out amount XS1 and the feed-out ratio (ratio DATA (ZS)), and the processing of this subroutine ends.

Next, the processing of the subroutine "zoom tracking calculation" shown in FIG. 12 will be described. First, in step S45, the feed ratio (ratio DATA (ZT)) at the T end is read from the ROM. Step S
46, the feed amount XT1 at the T end in FIG. 5 is set to the feed amount XW1 corresponding to the W end and the ratio DATA.
(ZT) and In step S47, the target focus lens position FT1 is calculated from the extension amount XT1 at the T end and the extension amount ∞DATA (ZT) at the subject distance ∞ stored in the ROM, and the processing of this subroutine ends.

As described above, in the subject distance information calculation processing of the camera of the present embodiment, when distance information is needed for stroboscopic photography, display of the subject distance, etc., the lens is driven virtually, that is, the lens is actually driven. Without performing, zoom tracking is performed to the T end only by calculation. At this time, manufacturing variation correction is performed. Then, it is possible to obtain accurate distance information by performing correction based on the feed amount deviation correction formula at the T end (the above formula (1)). The characteristic of this calculation processing is that the existing electric zoom tracking control processing is used as it is,
The point is that an accurate distance can be obtained by the above-mentioned formula for correcting the deviation of the delivery amount at the end.

In the present embodiment, the tracking calculation for obtaining the object distance is performed at the zoom lens position T.
Although it is performed at the end, the present invention is not limited to this, and the tracking calculation may be performed at another zoom lens position or a plurality of zoom lens positions. In short, it suffices to find the shift in the amount of extension by tracking calculation and find the correct subject distance.

Further, the reason why the tracking calculation point is selected not on the W end but on the T end as in this embodiment is that the tracking curve interval is generally narrow on the W end side with respect to each object distance, and on the T end side. This is because the interval of the tracking curve is wide and the selectivity is good, so that the precision is better when the calculation is performed on the T end side.

Next, the focusing operation of the video camera of the present embodiment will be described with reference to the block diagrams of FIGS.
Further, description will be made with reference to the flowcharts of FIGS. Conventionally, in focusing control in a video camera, a central area-focusing AF (autofocus) operation is used to perform a hollow focus operation, or a horizontal crossing that makes the AF operation unnatural when a moving object passes in front of the main subject. When it is predicted that unstable focusing operation at the time will occur,
In order to prevent this, the photographer switches to the MF (manual focus) operation each time. Therefore, not only the operation becomes complicated, but also the timing of shooting is inevitable.

Further, in the conventional one, the AF mode and the MF are
Processing independent of the (manual focus) mode is performed, and processing such as mutual information exchange is not performed. In other words, systematic AF is possible even in MF mode.
The evaluation value for, for example, the contrast information is obtained, but it is not particularly used, and the circuit consumes unnecessary power. Further, when the MF mode is switched to the AF mode, the focusing target area is set in the center of the screen, and it is difficult to reflect the intention of the photographer. In such a case, there is also proposed a camera that incorporates a line-of-sight detection sensor that detects where the photographer is looking, and determines the focusing target area based on the output of the sensor. However, the control unit becomes large and becomes an expensive product.

Furthermore, in the conventional camera, AF, AE
A product having a built-in automatic tracking function of a target subject in (automatic exposure control) has also been commercialized, but the operation of capturing and locking the target subject at the beginning of shooting was complicated. That is, a complicated work such as putting a subject in the center of the screen and pressing a switch for locking the subject is required.
Furthermore, the target subject cannot be positioned at any position on the screen, resulting in an unnatural shooting screen. As another method of capturing the subject, a method of inputting arbitrary position information on the screen with a trackball, a joystick, etc. and then operating the subject lock switch is also conceivable, but the operation is also complicated and costly. It was a disadvantage, and the operation of the trackball, joystick, etc. also led to camera shake photography.

This camera enables focusing control that solves the above-mentioned problems, and is a camera that performs AF control by automatic tracking. The focusing control is shown in FIGS. AF control block 1
0 etc.

Explaining the details of the control operation, first,
When the power switch of the camera is turned on, the processing of the shooting main routine shown in FIG. 13 is started. And
In step S51, the camera unit 101, the recording unit 102, etc. shown in FIG. 1 are initialized. At that time, the focusing target area in the AF process is set to the center. Step S52
At, the on / off of the REC / STANDBY switch 104 is checked. If the STANDBY side is on, the process proceeds to step S53, and if the REC side is on, the process jumps to step S55.

In step S53, the camera unit 10
1. The recording unit 102 performs a standby process for recording operation. Then, the process proceeds to step S54, and a subroutine "MF processing" to which manual focus described later is preferentially applied is called. On the other hand, in step S55, a recording operation process of recording the video signal output from the camera unit 101 in the recording unit 102 is performed. Then, step S56
Then, the subroutine "F-mode processing", which has priority to AF operation but can easily select MF operation, which will be described later, is called.

In the normal photographing according to the routine shown in FIG. 13, after the standby process is completed, the MF / AF switch is operated to turn on the AF side, and REC / STANDB is set.
When the Y switch 104 is operated to shift to the recording operation, the "F mode processing" in which AF is preferentially selected in the standby mode by the photographer intentionally and locked in the subject focused by the MF operation.
You can move to. In the conventional art, the subject at the center of the screen is designated as the subject to be subjected to AF at this time, and the intention of the photographer is not reflected. Further, as will be described later, in the F mode processing, it is possible to easily shift to the temporary MF mode.

As a modification, the above step S54
In the subroutine "F mode processing" in step S56
It is also possible to have a routine that calls a subroutine "MF processing" for performing the MF operation at. In this modification, the AF operation is prioritized during the standby processing.

The subroutine "F mode processing" called in the main routine will be described with reference to the flowchart of FIG. First, in step S60, the on / off state of the MF / AF switch 32 is checked. If the MF side is on, the process jumps to step S62, and if the AF side is on, the process proceeds to step S61. In step S61, the MF switch 3 for near focus is used.
It is checked whether the photographer's finger is in contact with the 0, 31 first stage switch 30a or 31a, that is, the on / off state of the switch. If it is turned on, the photographer is currently performing the AF operation, but the MF mode is temporarily set because there is a possibility that the incomplete focusing, unstable focusing due to crossing, etc. may occur, and the AF lock is performed. To perform step S62. Also, the switch 30
If a or 31a is off, it is determined that the MF operation is not necessary, and the process proceeds to step S64.

In step S62, the subroutine "MF processing", which will be described later, is called and the MF operation is executed. Further, in step S64, a subroutine "AF process" described later is called and the AF operation is executed. After that, in step S63, the EVF 27 displays whether the current process is the MF process or the AF process, and the present routine ends.

Step S54 of the main routine or step S62 of the subroutine "F mode processing".
The subroutine "MF processing" called in step 1 will be described with reference to the flowchart of FIG. First, in steps S70 and 71, the on / off states of the second-stage switches 30b and 31b of the near and far focus MF switches are checked. If they are on, steps S73 and
Alternatively, it jumps to 74 and drives the focus motor to the near or far focus distance side. Then, step S7
Go to 5. If the switches 30b and 31b are off, the process proceeds to step S72, the focus motor is stopped, and the process proceeds to step S75. Note that, in the conventional MF operation, the operation within the above-described operation range is performed from step S70, but in the present embodiment, the processing of step S75 and subsequent steps is further executed.

That is, in step S75, the subroutine "focus area determination" is called. This process
For example, on the photographing screen 40 shown in FIG. 4, the contrast information, which is the evaluation value of the in-focus state for the areas A to I, is compared, and the area with the highest in-focus degree is detected. Details of this processing will be described later. After that, step S
At 76, the focusing area is displayed on the EVF 27, and this routine ends.

Next, the above-mentioned subroutine "F mode processing"
The subroutine "AF processing" called in step S6 will be described with reference to the flowchart of FIG. First, in step S81, automatic tracking processing is performed. This process is the brightness information,
This is a process in which the tracking circuit 28 determines the current AF target area to be tracked with respect to the previous AF target area based on the color information and the angle of view information. After the MF operation, the previous target area is the step S in the above-mentioned “MF processing”.
The area determined in 75 is adopted. The details of the processing in step S81 will be described later with reference to FIG.

Subsequently, in step S82, the EVF2 is set to the target area for this time determined in step S81.
Display on 7. At this time, the photographer can check whether the area automatically selected by the automatic tracking is different from the intended area. Then, the process proceeds to step S83, and the hill-climbing AF process is executed. This AF
Processing is the AF evaluation value for the target area this time,
That is, the peak point is detected based on the value of the contrast information.

FIG. 19 is a characteristic diagram showing a change in the AF evaluation value with respect to the focus lens position. The hill climbing processing operation will be specifically described with reference to this diagram. In FIG. First, position Q1
If so, first, the ascending direction of the AF evaluation value characteristic line is confirmed, and the focus lens 4 is driven in the ascending direction while taking in the AF evaluation value. When the characteristic line starts to fall after passing the peak point Q2 of the AF evaluation value, the peak point Q2
It is determined that the light has passed 2 and the focus lens 4 is driven in the return direction. Then, the focus lens position F2 when the peak point is reached is adopted as the focus position, and this routine is ended.

Next, the subroutine "focus area determination" called in the subroutine "MF processing" of FIG. 15 will be described with reference to the flowchart of FIG. First, in step S91, for example, the AF evaluation values of the areas A to I obtained by dividing the photographing screen 40 shown in FIG. In step S92, the area area is normalized. In this process, for example, when the area including the center is different from J to K as shown in the shooting screen 40A of FIG. 20, the evaluation values cannot be compared, and thus the evaluation value is normalized to an evaluation value corresponding to a reference area. Is. Then, step S93
In, the AF evaluation values for the respective areas are compared, the area showing the highest value is designated as the target area, and this routine ends.

Next, regarding the processing of the subroutine "automatic tracking" called in the subroutine "AF processing",
This will be described with reference to the flowchart of FIG. Step S
At 95 and 96, the luminance and color information, which is the tracking information of the target area this time, are fetched. Then, in step S97, when the zoom operation is performed this time, the tracking information is corrected according to the change in the angle of view. In this process, for example, when the shooting screen 40B of FIG. 21A is changed to the shooting screen 40C of FIG. 21B by the zooming operation, the subject image on the target area “G” is the current target. It will be located in area "G '". Therefore,
The tracking information is also a process for fetching data corresponding to the target area "G '" of this time.

Subsequently, in step S98, it is checked whether or not the current brightness and color information in the target area is different from the previous information. When there is no change, this routine is finished as it is. If there is a change, the process proceeds to step S99 to compare the brightness and color information of the previous target area with the brightness and color information of the area around the current target area. Then, the area recognized as having the highest correlation is registered as a new target area, and this routine ends.

As described above, in the focusing operation of the camera of this embodiment, as shown in the flow chart of FIG. 14, when an unstable state of the AF operation is expected due to the transverse cut or the like during AF shooting, the MF switch is used. 30a,
Alternatively, by simply touching 31b with a hand, the focus is locked, and a defect due to AF can be avoided. Further, when the contact with the switch is released, the original AF operation state is restored, so that the complexity of the operation is improved.

Further, as shown in FIG. 15, the screen area that the photographer has intentionally focused on in the MF processing is taken in as the focus area. Therefore, when the AF operation is subsequently switched to, the area becomes the AF area. This is adopted, and AF operation that reflects the will of the photographer is possible. Further, since the focusing area is displayed on the EVF 27, an operation error can be immediately detected.

Further, as shown in FIG. 18, also in the automatic tracking process, the focusing information of the focusing area obtained by the MF process is used to determine the target area of the automatic tracking after switching to the AF operation. Therefore, it is possible to accurately capture the subject with a device having a simple configuration and a simple operation.

In the zoom tracking control of the video camera of this embodiment, the above-mentioned conventional Japanese Patent Application No. 4-288 is used.
The difference between the actual value and the design value on the zoom tracking curve according to the zoom tracking control system of the camera of No. 921 is calculated by the "WT correction calculation" process, and then the calculation reference value is calculated to perform the tracking drive of the focus lens. Then, in order to perform the “WT correction calculation”,
Assuming a design value curve LTa in which the W end and the T end point of the curve match the actual value tracking curve LPb shown in FIG. 5, and further, the maximum value of the difference between the curves LPb and LTa is required. Therefore, the above-mentioned actual value tracking curve is used as the lens 56 to be inspected (see FIG. 2) of each product, namely, the first lens group 1, the zoom lens 2, the third lens group 3, the focus lens 4, and the CCD 5 which is the image sensor. It becomes necessary to measure the photographic optical system of.

Next, one of the image pickup device mounting position correction methods for measuring the actual value tracking curve of the photographing optical system for each individual product will be described. To explain from the outline of the correction method, first, the best focus position of the focus lens at each zoom position is measured by a collimator device or the like as a measuring means as shown in FIG. That is, the image pickup device C
The lens 56 to be inspected is attached to the collimator in a state where the mirror surface of the collimator is arranged at the position equivalent to the image plane of the CCD 5 without mounting the CD 5, and the zoom position (W end, focal length f (s) The focus lens 4 is moved back and forth at the position, T end) to move the focus lens to the best focus position XA, X
C and XB (see the figure showing the measurement line LX at the best focus position with respect to the zoom magnification in FIG. 23) are measured. In addition,
The zoom position of the focal length f (s) is the zoom standard position that shows the maximum actual value deviation amount. On the other hand, in reality CCD
There is a variation in the position of the image plane of No. 5 (about 0.2 to 0.3 mm), and it is necessary to correct the influence. Therefore,
The best focus position X of the focus lens at the zoom position at the W end after the CCD 5 is attached to the lens 56 to be inspected.
Measure A ′ (see FIG. 23). This measurement is performed by measuring contrast information indicating the degree of focusing in the video signal.

The positions XC and XB are corrected by the difference between the positions XA and XA ', and the best focus positions XA', XC ', XB' when the CCD 5 is mounted, or
Find XC ", XB". Line connecting these positions LX
′ Or LX ″ is the lens 56 to be inspected and the CCD 5
The actual value tracking curve of the combination state of will be given.

The above measuring device and measuring method will be described in detail. FIG. 22 is a layout view of the collimator device. The device is mainly composed of a light projecting portion, a light receiving portion, and an image forming portion, and a lens 56 to be inspected is arranged in front of the light receiving portion. In the light projecting section, the light source section 51 and the detection chart 52 are arranged at the position corresponding to ∞ on the front surface section thereof, and the light emitted from the light source section 51 passes through the collimator lens section 55 and the test lens 56. Is emitted as parallel light. The light from the lens 56 to be inspected is reflected by the mirror surface 57 of the mirror unit 57.
Form an image on a. The reflected light passes through the collimator lens through the lens under test 56 and is reflected by the half mirror 58,
It is incident on the light receiving unit. The incident light passes through the vibration chart 53 arranged at the position corresponding to infinity of the light receiving portion and passes through the CD.
It is irradiated to S54. The output of the CDS 54 shows the maximum value when the best focus image is formed on the mirror surface 57a.

After the best focus position of the focus lens is measured by the collimator device, the CCD 5
Is attached to a predetermined assembly position of the lens 56 to be inspected, and the best focus position at the zoom W end is measured. The operation thereof will be described in detail with reference to the measurement value diagram of FIG. 23 and the flowchart of the measurement process of FIG. .

First, in steps S101 and S102, the lens to be inspected 56 with the CCD 5 not attached is attached to the collimator device, and the zoom lens 2 is moved to the W end position. In step S103, the focus lens 4 is moved back and forth to obtain the best focus position XA of the focus lens. In steps S104 and S105, the zoom lens 2 is moved to the T end position, the focus lens 4 is moved back and forth, and the best focus position XB of the focus lens where the image formation on the image formation surface 57a is best focused is obtained. Further, in steps S106 and S107, the zoom lens 2 is moved to the focal length f (s) position, the focus lens 4 is moved back and forth, and the best focus position XC of the focus lens is set.
Ask for. By the above processing, the best focus position curve LX in collimator measurement shown in FIG. 23 is obtained. Further, in this case, the position of the image plane 57a is unchanged, and
In FIG. 3, the line Y indicates the image plane position.

Succeedingly, in a step S108, the CCD 5 is attached to the lens 56 to be inspected. In step S109, the charts 52 and 53 are attached to the infinity corresponding positions. Then, in steps S110 and 111, the zoom lens 2 is moved to the W end position. Then, the focus lens is moved back and forth, and the best focus position XA 'is obtained based on the contrast information of the image pickup signal of the CCD 5. As shown in FIG. 23, this best focus position XA
'And the difference between the best focus position XA due to the image plane 57a is defined as the correction value x. Line Y'indicating a change in image plane position
Will show a line indicating the position where the CCD 5 is actually mounted.

In step S112, the correction value x
Based on the above, as a curve giving the corrected best focus position at other zoom positions, the position XB 'and the position XC' translated by the difference value x are given, and LX 'passing through these points is obtained. Here, the curve LX 'can be converted into a more accurate curve. A more accurate relational expression between the best focus correction amount x and the image plane deviation amount y is given by the following equation. That is, x = y / αn (3) Here, the value αn is a coefficient corresponding to each zoom lens position, and αW is given at the W end, αT is given at the T end, and αS is given at the focal length f (s) position. It should be noted that this value may be considered to be constant between taking lenses of the same type.

At the W end, the best focus correction amount x is given by the position difference XA-XA 'by actual measurement, and the best focus correction amount at the T end is given by y / αT. The value is calculated from the equation (3) as y / αT = (αW / αT) × x (4). On the other hand, the best focus correction amount at the position of the focal length f (s) is given by y / αS, and the value is expressed by the formula (3) as follows: y / αS = (αW / αS) × x ...... ... (5)

Then, the best focus correction positions XA ', XB ", XC" at the W end, the T end and the focal length f (s).
(See FIG. 23) are respectively XA '= XA + x ...... (6) XB ″ = XB + (αW / αT) × x ………… (7) XC ″ = XC + ( αW / αS) × x ……………… (8) These calculations are performed in step S1.
This routine is finished at step S12. Then, the correction data for the design value of the tracking curve obtained by the above measurement and calculation is written in the memory 15 shown in the block diagram of FIG. The curve indicating the best focus correction position is shown by the curve LX ″ in FIG. 23. Further, the curve Y ″ shown in FIG. 23 is the best focus when the best focus position curve LX is translated by the value x. The curve of the image formation position to give is shown.

As described above, according to the image pickup element mounting position correction method for actually measuring the actual value tracking curves LX 'and LX "of the present embodiment, first, the collimator device detects the W end,
The best focus position of the focus lens 4 at the T end and the focal length f (s) is measured, and then the best focus position of at least one point at the W end is measured with the CCD 5 mounted, and the other T end and the focus are measured. Since the best focus position at the distance f (s) is calculated based on the above-mentioned actual measurement result, the number of measurements with the CCD 5 attached is reduced,
It is possible to reduce the measurement man-hours. Also, as described above, CC
Since the number of measurements with the D5 attached is small, it is possible to reduce the chance of dust and the like adhering to the CCD image forming surface.
Further, it is advantageous in protecting the CCD 5 from static electricity.

[0075]

As described above, according to the camera of the present invention, it is possible to obtain the distance information corresponding to the actual value of the proper position of the focus lens by the zoom tracking calculation, and obtain the accurate object distance information as needed. .

[Brief description of drawings]

FIG. 1 is a diagram showing a main configuration of a video camera according to an embodiment of the present invention.

FIG. 2 is a block diagram of a camera section of the video camera shown in FIG.

3 is an AF control block configuration diagram of the video camera of FIG.

FIG. 4 is a diagram showing divided areas of a shooting screen of the video camera shown in FIG.

5 is a diagram showing an example of a zoom tracking curve used to describe the video camera shown in FIG.

6 is a flowchart of distance information calculation processing of the video camera of FIG.

7 is a flowchart of a calculation process of a calculation reference value called in the distance information calculation process of FIG.

8 is a flowchart of zoom tracking calculation called in the distance information calculation process of FIG.

9 is a flowchart showing a modified example of the calculation processing of the calculation reference value in FIG.

10 is a flowchart showing a modified example of the zoom tracking calculation process of FIG.

11 is a flowchart showing another modified example of the calculation processing of the calculation reference value in FIG.

FIG. 12 is a flowchart showing another modification of the zoom tracking calculation process of FIG.

FIG. 13 is a flowchart of a shooting main routine of the camera of this embodiment.

14 is a flowchart of a subroutine "F mode processing" called in the main routine shown in FIG.

15 is a flowchart of a subroutine "MF processing" called in the main routine shown in FIG.

16 is a flowchart of a subroutine "AF processing" called in the subroutine "F mode processing" shown in FIG.

17 is a flowchart of a subroutine "focus area determination" called in the subroutine "MF processing" shown in FIG.

18 is a flowchart of a subroutine "automatic tracking" called in the subroutine "AF processing" shown in FIG.

FIG. 19 is a characteristic diagram of an AF evaluation value used in the hill-climbing AF processing operation in the subroutine “AF processing” in FIG. 16 described above.

FIG. 20 is a diagram showing a change state of a target photographing area in the subroutine “focus area determination” processing of FIG.

FIG. 21 is a diagram showing a change state of the target photographing area in the subroutine “automatic tracking” process of FIG.
FIG. 6A is a diagram showing a divided area of a shooting screen in a tele state and FIG.

FIG. 22 is a layout diagram of a collimator device for actually measuring an actual value tracking curve of the video camera of the present embodiment.

23 is a tracking curve measured by the collimator device of FIG. 22.

24 is a flowchart of a process of actually measuring a tracking curve by the collimator device of FIG. 22.

FIG. 25 is an example of a tracking curve used for zoom tracking control of a conventional video camera.

FIG. 26 is a diagram showing a part of the tracking curve shown in FIG. 25.

27 is a diagram showing a range of the design value tracking curve in FIG. 25.

FIG. 28 is a diagram showing a design value tracking curve and an actual value tracking curve used for zoom tracking control of a conventional video camera.

FIG. 29 is a diagram showing an actual value tracking curve in which a wide end and a tele end are matched with a design value tracking curve used for zoom tracking control of a conventional video camera.

FIG. 30 is a diagram showing a set of a design value tracking curve used for zoom tracking control of a conventional video camera and an actual value tracking curve in which the wide end and the tele end are matched.

[Explanation of symbols]

15 ………………………… Zoom tracking data holding means 7 ………………………… Zoom tracking control block (correction means for correcting zoom tracking data,
Arithmetic means for calculating the distance corresponding to the actual value) Steps S1 to S7 ......... Correction means for correcting the zoom tracking data Step S8 ……………… Calculation means LT for calculating the distance corresponding to the actual value LT, LTa, LTb, LT1, LT2, LT∞ ...
………… Design value tracking curve (tracking data as design value) FS0 …………………… Actual value Focus lens position on the tracking curve (actual value of proper focus lens position)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location G02B 7/28 (72) Inventor Atsujiro Ishii 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Inside Optical Industry Co., Ltd. (72) Inventor Masao Sato 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industry Co., Ltd.

Claims (1)

[Claims] 1. A zoom tracking data holding means for holding zoom tracking data as a design value of an appropriate position of the focusing lens for maintaining a focused state when the magnification of the zoom lens changes under a constant object distance. Based on the zoom tracking data held by the zoom tracking data holding means, the actual value of the proper position of the focusing lens for maintaining the in-focus state when the magnification of the zoom lens changes when the subject distance is constant. A camera comprising: a correction unit that calculates by a predetermined correction calculation, and a calculation unit that calculates a subject distance corresponding to the actual value of the proper position of the focusing lens calculated by the correction unit.