JP2620937B2 - Automatic focus adjustment device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic focusing device, and more particularly, to an automatic focusing device.
The driving of the focusing lens of the photographing lens is started based on the focus direction detection result in the shift direction and the focus state, and the image formation position of the object to be focused has reached a predetermined focus area around the expected focus position ( The present invention relates to an automatic focus adjustment device that stops driving of a focusing lens when (in-focus) is determined.

(B) Conventional technology In the above-described automatic focus adjustment device, the focusing lens is driven based on the detected deviation direction, and the driving position is set to, for example, the shortest shooting distance (closest distance) in the shooting distance range of the shooting lens. If focusing is not determined even when the lens reaches the corresponding end position on the closest side (that is, if the object to be focused is located at a position closer than the shortest shooting distance), movement of the focusing lens at this end position is mechanical. Therefore, the driving means such as a motor continues to be overloaded, which is not preferable. Therefore, for example, a normally open switch is provided at the terminal position, and the focus lens reaches the terminal position and closes the normally open switch to detect the arrival of the terminal, or connect a rotary encoder or the like to the focus lens,
In general, it is generally detected that the output of the rotary encoder does not change within a predetermined period of time, thereby detecting the arrival at the end, and thereafter electrically stopping the driving of the focusing lens.

However, the detection output of the focus detection means varies, and the focus target is focused at a position outside the photographing distance range despite being near the shortest photographing distance within the photographing distance range or at a position at infinity distance. Erroneous information as if there is an object may be output temporarily. For example, when the object to be focused is in the vicinity of the position of the shortest shooting distance, the driving position of the focusing lens reaches the nearest end position due to the temporary error information, and the focus lens is detected by the end detection. No further driving is performed. In other words, there has been a problem that the proper focus adjustment cannot be performed even though the focus target object is within the focus range in which the focus can be adjusted. this is,
If the focus detection device is configured to stop driving the focusing lens even at the end position at infinity, the same inconvenience as in the above case occurs.

In order to solve these drawbacks, when the end detection is performed, the driving of the focusing lens is temporarily stopped, and the focusing lens is driven in accordance with the comparison result of the deviation direction data from the focus detecting means before and after that. An automatic focus adjustment device that determines the final drive mode is disclosed in
No. 59-204813.

However, in a photographing lens having a macro function, when an object to be focused can be focused within a macro area,
In the above-mentioned conventional example, if the photographing lens is not located in the macro area, the drive control for the focusing lens after the end detection is not performed at all by the end detection. In other words, there is a disadvantage that the proper focus adjustment cannot be performed even though the focusing target object is within the focus adjusting range.

Japanese Patent Application Laid-Open No. 58-105113 discloses that, during driving of a lens, the end of the lens is detected when there is no change in a signal related to the movement of the lens for a predetermined time, and further movement of the lens in the same direction is performed. Although a lens control device that inhibits driving has been proposed, the latter conventional device suffers from the same disadvantages as the former conventional device.

(C) Objective The present invention has been made in view of the above circumstances, and has as its object the object of the present invention when the driving position of the focusing lens of the photographing lens reaches the end of the driving range in the variable magnification area and stops. Successive driving in the same direction can be prohibited to suppress overloading of the driving means and wasteful power consumption, and driving in the opposite direction is allowed to achieve high-precision matching even if there is a variation in the output of the focus detecting means. Focus adjustment is possible, and when the object to be focused is located at a distance shorter than the closest distance in the variable magnification area, an automatic focus adjustment device that can give appropriate information to the user as to whether or not macro shooting is possible is provided. To provide.

(D) Configuration In order to achieve the above object, the present invention provides a photographing lens having a variable magnification region and a macro photographable macro region, and focuses upon receiving light from a focusing object transmitted through the photographing lens. Focus detection means for detecting the direction and focus state of the deviation of the imaging position of the object from the expected focus position, and if the focus detection means determines out of focus, the focus lens of the photographing lens is oriented in the focus direction And a driving means for stopping the movement when the focus is determined, the driving position of the focusing lens of the photographing lens has reached the end of the driving range in the variable magnification area. End detecting means for detecting whether the end is detected, prohibiting means for prohibiting operation of the driving means when the end detecting is performed by the end detecting means, and responding to the end detecting by the end detecting means. By comparing the deviation direction data from the focus detection means immediately before and immediately after, the release means for releasing the prohibition operation of the prohibition means when the two do not match, and it is determined whether or not the taking lens is located in the macro area. When the area determining means determines that the taking lens is not located in the macro area, the area determining means responds to the end detection from the end detecting means and obtains the focus detection means immediately before and after the focus detection means. The driving direction of the focusing lens is compared, and when the driving directions coincide with each other and the driving direction is the close-up direction, macro information for outputting promotion information indicating that the photographing lens should be moved into the macro area. And providing means.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration. First
In FIG. 1, reference numeral 1 denotes an optical axis of a variable power optical system, and 2 denotes a movable lens group, a focusing lens group, and a macro lens group which are disposed on the optical axis 1 so as to be movable along the optical axis 1. In a variable power optical system as a taking lens, 2a, 2b, 2c, 2d, 2e is a first group lens composed of a single lens or a plurality of lenses,
Second lens group, third lens group, fourth lens group, and fifth lens group
It is a group lens. The first lens group 2a and the second lens group 2b constitute a focus lens group 3 as a focus lens. Here, Fm is the film surface. Reference numeral 4 denotes the focal length on the telephoto side (hereinafter simply referred to as “tele side”) as the longest focal length, and the focal length on the wide angle side (hereinafter simply “wide side”) as the shortest focal length.
Abbreviated to the focal length)
Alternatively, a variable power motor Mz that drives the variable power optical system 2 to set a predetermined focal length in a macro area where macro photography is possible.
And a variable power drive unit 5 including a mechanism unit (not shown), which moves from an infinity position (∞ position) on the optical axis 1 corresponding to a subject distance as an in-focus object distance from infinity to a close position to a close position. the focus position of Henbaigoase area or focus motor M _F and a mechanism not shown for driving the focus lens group 3 to the focal position of the macro-focus area provided on the opposite side of said ∞ position from the close position A focus driving unit as a driving unit, and a termination detection unit as a termination detection unit including, for example, a rotary encoder that generates a pulse proportional to the number of rotations from a photo interrupter when a slit disk is rotationally driven. When the amount of movement of the focus lens group 3 driven by the focus driving unit 5 is detected and the pulse does not change within a predetermined time, Kasurenzu group 3 is configured to output a stop signal it is determined that reaches the end (LST). Reference numeral 7 denotes the optical axis 1 of the focus lens group 3.
A focusing lens group position detector (hereinafter abbreviated as “FPM”) 8 that outputs a voltage as focus position information Sx in proportion to the upper position, 8 is driven by a variable power driving unit 4 together with a variable power optical system 2. A focal length detector (hereinafter abbreviated as “ZPM”) that outputs a voltage having a predetermined relationship with the overall system focal length f (for example, when focal length information is Zp, f∝1 / Zp), and 9 is the focal length. Upon receiving the distance information Zp and the focus position information Sx and performing A / D conversion, it is determined whether the variable power optical system 2 is in the variable power area or in the macro area. Denotes an area determination unit as an area determination unit that outputs a negative signal (NG2), and 10 forms an image of a subject by receiving a light beam from a subject (not shown) as a focusing target transmitted through the variable power optical system 2 Defocus as the direction of deviation of the position from the expected focal position A focus detection unit as focus detection means for detecting a direction and a defocus amount as a focus state. The focus lens 3 moves to the closest position side when MDR = 1 as the defocus direction, and to the ∞ position side when MDR = −1 as the defocus direction. Outputs a focus direction signal (MDR) and a defocus amount (Dfx) indicating driving, and furthermore, when there is an error in processing inside the detector, the focus detection means 10 or the like for some reason (for example, noise or the like). In this case, Fe = 1 is set, and if it is normal, a pass / fail signal (Fe) indicating data reliability is output as Fe = 0. Note that these (Dfx), (MDR), and (Fe) may be collectively referred to as “ranging data” below. Further, the defocus amount Dfx is configured so that Dfx = 0 in the focused state, and the maximum defocus amount that can be measured and is reliable is Dfx = 2048. 11a receives the distance measurement data (Dfx), (MDR), (Fe) output from the focus detection unit 10 and the stop signal (LST) output from the end detection unit 6, and receives this stop signal (LST). The focusing direction signal (MDR) immediately before and immediately after is input to the memory MR1.
And when they do not match, release signal (ENA)
Is a release unit as a release unit that outputs a. 11b receives the release signal (ENA) and the stop signal (LST), and when the stop signal (LST) is received, prohibits the operation of the focus drive unit 5 (that is, the focus motor
M _F The stopping) outputs the contents of the motor control signal (MS), a prohibition unit that outputs a motor control signal of the content for releasing the prohibition (MS) upon receiving the release signal (ENA). Hereinafter, the release unit 11a and the prohibition unit 11b may be collectively referred to as a focus control unit 11. The focus control unit 11 drives the focus lens group 3 at the time of receiving the focusing direction signal (MDR), and outputs an output pulse Dfc (not shown) of the rotary encoder of the end detection unit 6 during driving. defocus amount (Dfx) is configured to have a time of the match to stop the focus motor M _F and in-focus state. 12 is the focal length information (Z
p) and the defocus amount (D
fx), a focus limit value Dfm indicating a range in which focusing (photographing) is possible for the focal length information Zp in the macro focus area is determined, and the defocus amount (Dfx) is determined by the focus limit value Dfm.
Judgment instructing unit that outputs a negative signal (NG1) when the value exceeds
Reference numeral 3 denotes a macro information providing means, which comprises a macro display control unit 13a and a display 13b constituted by, for example, a liquid crystal or the like, of which the macro display control unit 13a outputs the negative signals (NG1) and (NG).
2) When received, a display signal (DSP) as promotion information is output to the display 13b, a symbol or a character indicating that focusing is impossible is displayed on the display 13b, and a stop signal (LST) is received. The immediately preceding focus direction signal (MDR) is stored in the internal memory MR2, and compared with the content of the focus direction signal (MDR) immediately after receiving the stop signal (LST). MDR = 1, and the negative signals (NG1), (NG
2) When the display signal (DSP) is not received, the display 13a is given to the display 13a to display, for example, the character "MACRO" indicating that macro photography is possible (state shown). still,
When the variable power optical system 2 is in the zoom area and other than the above, a sign or character indicating that the variable power optical system 2 is in the variable power area, for example, “ZOOM” or a numerical value indicating the focal length is displayed. Is configured. Numeral 14 denotes drive control of the variable magnification optical system 2 via the variable magnification drive unit 4 so as to set the variable magnification optical system 2 at an arbitrary focal length of the variable magnification area or at a predetermined focal length of the macro area. This is a variable magnification control unit. The operation of the magnification control unit 14 is not shown, but is activated by an operator (user) of the camera operating an operation switch such as a magnification up / down switch or a magnification / macro switch. It is configured to be. In addition, + V indicates a power supply, and the input / output relationship of each unit indicates only a main signal. Although not shown, it is assumed that the variable magnification optical system 2 includes a lens determination unit as a photographing lens determination unit that determines whether or not the variable magnification optical system 2 has a macro function.

FIG. 2 is a graph showing characteristics in the above-mentioned variable power range of the embodiment according to the present invention shown in FIG. 1, and shows the total system focal length f to be set and the focus lens group 3 (first group lens 2a). And the extension amount (movement amount) corresponding to the subject distance D of the second group lens 2b) is shown for each representative subject distance D, the vertical axis represents the change in the focal length f of the entire system, and the horizontal axis represents infinity. 3 shows the amount of extension of the focus lens group 3 with reference to the in-focus position with respect to. In this example, the tele position is f = 135 mm, and the wide position is f = 35 mm. In FIG.
Reference numerals 15 to 20 denote focusing curves represented by hyperbolas with Zp as a variable. The object distance D is ∞, 6.0 m, 3.0 m, 2.0 m, 1.5 m,
It shows a change in the amount of extension of the focus lens group 3 from the infinity position to the in-focus position with respect to a change in the focal length information Zp when the distance is 1.2 m. Therefore, the focusing curve 20 is the closest focusing curve that provides the maximum amount of extension in the above-mentioned variable magnification area. In particular, this closest focusing curve 22 is referred to as a close end value Fpc.

FIG. 3 is a diagram showing characteristics in the macro area of the embodiment shown in FIG. 1 as in FIG. 2, and particularly for explaining a photographable range, that is, a focusable range in the macro area. is there.

In FIG. 3, the vertical axis is the same as the vertical axis in FIG.
0 is the value of Zp corresponding to the tele side, Zp = 154 and Zp = 170
Is the value of Zp that defines the limit of the focusable range described later, Zp =
255 is the value of Zp corresponding to the wide side. The horizontal axis indicates the subject distance D corresponding to the focus position information Sx based on the subject distance D = 1.2 m corresponding to the closest position. twenty one
Is a reference line which is indicated by a straight line of D = 1.2 m and serves as the above reference, 22 is a straight line of D = 0.4 m (broken line in the drawing) and indicates a closest object distance to the camera, and 23 is a film surface Fm. A maximum defocus curve indicating the maximum defocus amount that is measurable and reliable above, a limit curve 24 given by giving a predetermined margin (margin) to remove the influence of an actual error and the like, 25 27 are the straight line of Zp = 0 and the reference line 21, respectively.
Each fulcrum with the maximum defocus curve 23 and the limit curve 24,
28 is the intersection of the maximum defocus curve 23 and the limit curve 24, which corresponds to Zp = 154 described above. 29 is the intersection of the maximum defocus curve 23 and the nearest tangent line 22 and corresponds to Zp = 170, 30 is the intersection of the limit curve 24 corresponding to Zp = 170, and 31 indicated by a dashed line is Zp = 154 of the limit curve 24. An approximation limit line obtained by linear approximation of the section of ~ Zp = 255, 32 to 37 are all intersections on the straight line indicated by Zp = 255, of which 32 is the intersection with the focusing curve 15 at the ∞ position, and 33 is the reference line 33 , 34 is the intersection with the limit curve 24 and the approximate limit line 31, 35 and 36 are the intersections with the perpendiculars from the intersections 30 and 28, and 37 is the intersection with the nearest tangent 22. Incidentally, the intersections 32 and 33 are the same as the ∞ position and the closest position in FIG. 2, and the intersection 37 may be called “the closest position”. 38 is the macro shooting (focusing) range, Zp
= 0 and Zp = 255, a range surrounded by the maximum defocus curve 23 between the reference line 21 and the intersections 26 and 28, and the approximate limit line 31.

Note that the range from the focusing curve 15 at the ∞ position to the reference line 21 is the variable magnification focusing area, and the range from the reference line 21 to the closest tangent line 22 is the macro focusing area.

FIG. 4 is a flowchart showing the operation sequence of the embodiment shown in FIG. Note that the configuration of this flowchart is also described in the following description of the operation, and will not be repeated here.

Now, the operation of the present embodiment thus configured will be described with reference to the flowchart of FIG. Now, zoom optical system 2
Is in the zooming range, and the focus lens group 3
Is in the variable magnification focusing area. In correspondence with FIG. 2, for example, the focal length is f = 50 mm (Zp = 217), and the focus lens group 3 is a focusing curve 16 corresponding to the subject distance D = 6.0 m.
Let it be above. The subject is, for example, D = 0 in FIG.
Assume that it is located at 8m. In other words, macro shooting range
Assume that it is within 38. Then, it is assumed that a release switch (not shown) for starting a photographing operation or a distance measuring operation forming a part of the photographing operation is operated. First, the focus detection unit 10
Starts ranging operation, and the ranging data (Dfx), (Fe), (M
DR) is output. That is, a defocus amount (Dfx) corresponding to the subject distance D = 0.8 m, for example, Dfx = 980 is output, and Fe = 0 is output as a pass / fail signal (Fe) assuming that there is no mistake in the distance measurement operation. Since the driving is to the close side, MDR = 1 is output as the focusing direction signal (MDR). This MDR
= Focus control unit when 1 received 11 rotates the focus motor M _F, starts to drive the focus lens group 3 to the near side through the focus driver 5. Accordingly, an output (Dfc) indicating the amount of movement of the focus lens group 3 (not shown) is output from the rotary encoder in the end detection unit 6. The focus control unit 11 monitors whether Dfc = Dfx is satisfied. In FIG. 2, the focus lens group 3 located on the intersection of the focusing curve 16 and f = 50 mm
Moves on a straight line of f = 50 mm, sequentially passes over intersections with the focusing curves 17, 18, and 19, and reaches an intersection with the closest focusing curve 20. That is, the focus lens group 3 reaches the closest end of the variable power focusing area, abuts against the cam wall (not shown) at the closest position, and stops. Along with this, the slit disk (not shown) of the rotary encoder also stops, and the termination detection unit 6 detects that the output (Dfc) has not changed for a predetermined time, and outputs a stop signal (LST). On the other hand, the canceling unit 11a and the macro display control unit 13a sequentially store the focusing direction signal (MDR) among the distance measurement data (Dfx), (Fe), and (MDR) output from the focus detecting unit 10 in the internal memory MR1. And MR2 to store the latest information and stop signal (LST)
We are preparing so that the data immediately before and immediately after input can be compared.

The flowchart in FIG. 4 starts from “START” when the stop signal (LST) is output.

First, the prohibition unit 11b is used for the "stop signal?"
Since already the stop signal, as described above (LST) is outputted from the end detection unit 6 stops the focus motor M _F outputs a motor control signal for stopping the focus motor M _F (MS) , Hold this prohibited state. In the next conditional branch of “focus direction match?”, The release unit 11a
And the macro display control unit 13a transmits the stop signal (LS
The focus direction signals (MDR) immediately before and immediately after T) are input are compared. In this case, the position of the focus lens group 3 before the start of driving is a position corresponding to D = 6.0 m, and the subject is located at a position of D = 0.8 m closer to the camera than D = 1.2 m which is close. Therefore, MDR = 1 immediately before the stop signal (LST) is output, and MDR = 1 immediately after that because the direction in which the drive is required is the same direction. That is, since the focusing directions match, the process branches to YES.
In addition, since the detection output of the focus detection unit 10 varies, for example, even if the subject is close to the shortest shooting distance (closest distance) or infinity distance within the focusing distance range of the variable magnification area, the focusing distance Erroneous distance measurement information (in this example, defocus amount Dfx) as if there is a subject at a position outside the range is temporarily output, and based on it, the focus lens group 3 is driven to reach the end position. In some cases, the driving is stopped by a stop signal (LST). In such a case, since the focusing direction signal (MDR) immediately before and immediately after the input of the stop signal (LST) does not match, the release unit 11a determines this and inhibits the release signal (ENA). Output to the unit 11b. Prohibition section 11b which receives the so providing a motor control signal of the content for releasing the prohibited (MS) to the focus motor M _F, the focus motor M _F is focused immediately after the stop signal (LST) is input Direction signal (MDR)
Moves the focus lens group 3 on the basis of the defocus amount (Dfx) immediately after the stop signal (LST) is input.
But the focus state with the time of the match with the output pulses of the rotary encoder of the termination detecting portion 6 (Dfc), stops the focus motor M _F. That is, in this case, the flow branches to NO in the "focusing direction match?" In the flowchart, and the next "normal display" indicates that the zooming optical system 2 is in the zooming area, or a numerical value indicating the focal length or the like. The above-mentioned focusing operation is completed in a state where the character is displayed on the display 13b, and all the operations are completed.

By the way, in the next conditional branch “Is the focusing direction closest?”, The focusing direction signal (MDR) is checked, and M
Since DR = 1, the flow branches to YES, and in the next conditional branch “reliable?”, The pass / fail signal (Fe) is checked in the same manner, and since Fe = 0 as described above, the flow branches to YES.

In the following “is a macro lens?”, The lens discriminating unit (not shown) has a macro function by a discriminating means such as a notch or an electric contact provided in advance in the photographing lens comprising the variable power optical system 2. It is determined whether or not. In this case, it is determined that the macro function is provided, and the process branches to YES. Therefore, if the macro function is not provided, the operation branches to NO and ends with END.

Next, in “Zp read”, the area determination unit 9 reads the focal length information Zp output from the ZPM 8 and performs A / D conversion, and in the next “closest end value calculation”, the closest terminal value in the focal length information Zp. Calculate Fpc. In the next conditional branch “is the lens in the closest position?”, The area determination unit 9 reads the focus position information Sx output from the FPM 7 in order to know the current position of the focus lens group 3 and performs A / D conversion. The difference between the close end value Fpc and the Sx is obtained. If the difference is within a predetermined amount, the focus lens group 3 is located at the closest position, that is, on the focusing curve 20 shown in FIG. And the process branches to YES without outputting a negative signal (NG2). In other words, in this conditional branch, it is confirmed that the variable power optical system 2 is in the variable power area and that the focus lens group 3 has reached the closest end of the variable power focusing area.

By the way, in this way, preparations (preconditions) for macro judgment for judging whether or not macro shooting is possible are completed, but from the above three conditional branches not mentioned in the above description, The case where the process branches to NO and reaches the “in-focus inability display” will be described.

First, the reason for branching to NO when "Is the focusing direction closest?"
MDR = −1, that is, when the movement of the focus lens group 3 in the ∞ position direction is indicated. At this time, since the subject is naturally moving in the direction opposite to the macro focus area, It is not necessary to execute the above-mentioned macro judgment, and the display is rejected to the "in-focus disabled display". The branch to NO in the next “reliability?” Is similar to the above. If the pass / fail signal Fe = 1, the defocus amount (Dfx) and the focusing direction signal (MDR) output from the focus detection unit 10 are reliable. Since it cannot be performed, it is not necessary to execute the macro judgment. The branch to NO in the next “Lens is closest position?” Occurs when the focus lens group 3 stops in the middle of the variable magnification focusing area due to, for example, an obstacle, that is, the focus lens group 3 is close. Since the pre-conditions for the macro judgment are not satisfied because the end of the side has not been reached, the area judgment unit 9 outputs a negative signal (NG2), and the macro display control unit 13a receives the negative signal (NG2). A display signal (DSP) to the effect that macro shooting is not possible is output to the display unit 13b when "in-focus display is not possible", and the display unit 13b displays the content to that effect. And END
The operation ends with.

Now, the operation of the macro judgment will be described. First, in “focus limit value determination”, the determination instruction unit 12 determines which of the maximum defocus curve 23 and the approximate limit line 31 determines the limit of the macro photographable range 38. That is, if Zp is in the range of (i) where 0 ≦ Zp <154, the limit is determined by the maximum defocus curve 23,
If Zp is in the range of (ii) where 154 ≦ Zp ≦ 255, the limit is determined by the approximate limit line 31. In this case, since the focal length f of the variable power optical system 2 is 50 mm (Zp = 217), it is within the range of the above (ii). If the approximation limit line 31 is expressed by, for example, L (Zp) = 13 × Zp−1350, then L
(Zp) = 1147, and the focusing limit value Dfm = 1147 is determined.
In the next conditional branch “Focusable?”, The above focus limit value
Dfm = 1147 is compared with the defocus amount Dfx = 930 output from the focus detection unit 10, and the process branches to YES because the defocus amount Dfx does not exceed the focusing limit value Dfm. That is, the determination instructing unit 12 determines that if the focus lens group 3 is moved to the macro focus area, the in-focus state can be reliably obtained, and does not output the negative signal (NG1). Therefore, in the next “MACRO display”, the macro display control unit 13a outputs the negative signal (NG1)
Has not been input, it is determined that macro shooting is possible, and a display signal (DSP) indicating that fact is output to the display 13b.
13b displays the characters "MACRO" shown in FIG. At END, the operation of the macro judgment ends.

Next, a case where the above-described overall focal length f = 50 mm is, for example, f = 90 mm (Zp = 115) will be described. Since the focal length information Zp = 115 is within the range of the above (i), if it is made to correspond to FIG. 3, the limit of the macro photographable range 38 in the range of the above (i) is the maximum defocus curve.
Determined by 23. In other words, the focus limit value Dfm is uniformly D
It is determined that fm = 2048. It should be noted that the number 2048 means the maximum defocusable amount Dfx output from the focus detection unit 10 as described above. And
If the subject distance D = 0.8 m in the next “focusing possible”, the defocus amount Dfx = 930 as described above, so that Df
Since x is smaller than 2048, the flow branches to YES, and after "MACRO display", the operation of the macro judgment is terminated by END.

By the way, in the above-mentioned conditional branch “focusing possible?”, Even if the same object distance D = 0.8 m, the entire system focal length f is set to the telephoto side (Zp
= 0), for example, at the position indicated by the mark x in FIG. 3, since it is out of the macro photographable range 38, the process branches to NO and proceeds to the “in-focus incapable display”. That is, the determination instructing unit 12 determines that focusing is impossible, and outputs a negative signal (NG1). Upon receiving the signal, the macro display control unit 13a outputs a display signal (DSP) instructing that focusing is impossible. Display 1 received
3b displays a symbol or a character indicating that focusing is impossible (macro shooting is impossible), and the macro determination operation is terminated when END is reached.

The operation of the macro determination is completed as described above. However, if the macro determination determines that the macro shooting is possible, that is, if the character “MACRO” is displayed on the display 13a, the operator performs the zoom / macro operation. By operating a changeover switch (not shown), the variable power optical system 2 switches from the variable power area to a predetermined focal length in the macro area, and the focus lens group 3 sets the subject distance D = 0.8 m in the macro in-focus area. Corresponding optical axis 1
It moves to the upper position to obtain a focused state.

As described above, according to the present embodiment, the variable power optical system 2 is in the variable power area, the focus lens group 39 is at the close end of the variable power in-focus area, and the subject is closer to the camera than close. When the camera is at the position, the focus limit value Df is obtained from the focal length information Zp.
m is determined to form the macro photographable range 38, and the macro determination is made based on whether the defocus amount Dfx from the focus detection unit 10 corresponding to the distance to the subject is within the macro photographable range 38. Since the result is displayed and the result is displayed, when the focus lens group 3 reaches the above-mentioned closest end and still does not reach the focused state, the operator should switch the variable power optical system 2 to the macro area. It is easy to judge whether or not it is possible. Therefore, there is no danger of missing the shutter chance during the above-mentioned switching in the dark cloud, and after doing the above switching, it is unpleasant to know that macro shooting can not be done. There is an advantage that there is no. In addition, since optimal measures can be taken, no time is wasted.

When the focal length information Zp is in the range of (ii), there is an advantage that the limit curve 24 is linearly approximated, so that the calculation can be simplified. Since the macro determination is performed using the approximate limit line 24 obtained in this manner, There is an advantage that the calculation speed in Zp is increased.

Further, since a margin (margin) is expected in forming the macro photographable range 38, there is an advantage that the accuracy and reliability of the macro determination are high.

Further, the range is divided into the range (i) and the range (ii) according to the focal length information Zp. Within the range (ii), the approximation limit line 31 is used, and within the range (i), the maximum defocus curve. Since the macro photographable range 38 is determined by 23, as shown in FIG. 2, it depends on the difference in the extension amount for focusing of the focus lens group 3 on the telephoto side (Zp = 0) and the wide side (Zp = 255). There is an advantage that there is no variation in accuracy and the accuracy can be made uniform.

Further, in the present embodiment, when the terminal end is detected in the variable magnification area, the data in the deviation direction (focusing direction) output from the focus detection means immediately before and immediately after the end detection is compared, and if the two directions do not match. In this case, the release signal (ENA) is output and the drive of the focus lens group 3 is restarted. Therefore, the end position (∞
Position or the closest position), even if erroneous distance measurement information (defocus amount Dfx) as if the subject is out of the range temporarily occurs, the distance measurement information immediately after the end detection is performed. , The focus adjustment is performed, so that the focusing accuracy can be improved. If this the shift direction of the immediately preceding and immediately following the end detection Conversely match, release signal (ENA) is not outputted, the motor control signal of the content to prohibit the rotation of the focus motor M _F from prohibiting unit 11b (MS) is output, the focus motor M _F can be prevented because the stop, wasteful power consumption it is possible to prevent an excessive load to the focus motor M _F from being applied. In this case, if the defocus amount Dfx obtained from the focus detection unit 10 falls within the macro photographable range 38 as described above, "MACRO" is displayed.
The user can operate the zooming / macro switch to switch to the macro area to take a picture, thereby obtaining a close-up photograph with good focus.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, the closest position is not limited to 0.4 m, and may be increased or decreased as long as it is within a range appropriate for camera specifications.

Further, the macro photographable range 38 may be determined by using the limit curve 24 without using the approximation limit line 31 in the range of (ii) of the focal length information Zp and using the limit curve 24 if there is no problem in the calculation speed.

Further, the boundary between the range (i) and the range (ii) is not limited to Zp = 154, and may be appropriately increased or decreased as long as it is a range in which macro judgment can be optimally performed.

Further, the promotion information is not limited to the display 13b that is visually displayed, but may be a sound, a voice, or the like. In short, any means that can be recognized by the user may be used.

The focus lens group 3 is not limited to the two-group configuration, and the type and the number of lens groups may be increased or decreased if necessary in designing the variable power optical system 2.

The end detection unit 6 is not limited to the one using the rotary encoder.
The output Sx of M7 may be configured to be read by the focus control unit 11, and the determination may be made based on the value of Sx.

(E) Effect As described in detail above, according to the present invention, when the driving position of the focusing lens of the photographing lens reaches the end of the driving range in the variable power range, the operation of the driving unit is immediately prohibited. Therefore, it is possible to prevent both an excessive load on the driving means and wasteful consumption of electric power, and it is also possible to prevent the object to be focused from being close to a close distance within a focusing distance range of the variable magnification area. Erroneous distance measurement information as if it is at a distance (position) closer than the closest distance despite the above is temporarily output from the focus detection unit due to variation in detection output, and based on the information, the driving unit performs focusing. When the lens is driven to the nearest end position and stopped, the operation prohibition of the driving means is released and the focusing lens is driven to the infinity position side. Focusing is performed on the object to be focused at the position of .Therefore, even if there is a variation in the output of the focus detection means, highly accurate focusing can be adjusted. When the camera is located at a position closer than the distance corresponding to the closest position, it is configured to give appropriate information to the user as to whether or not macro shooting is possible. It is possible to eliminate unnecessary operations and wasted time of the operator such as noticing that focusing is impossible after performing a shift operation to the macro area in a dark cloud, and conversely, a macro area If the mode shifts to, despite the fact that proper macro shooting is possible, it is impossible to focus in the variable magnification area, so it is necessary to give up shooting or perform a shift operation to the macro area They waste time before they realize It is possible to provide an automatic focus adjustment device capable of reliably avoiding a situation such as losing a valuable shutter chance by spending a valuable time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of an automatic focus adjusting apparatus according to the present invention. FIG. 2 is a diagram showing characteristics in a variable magnification region of the embodiment shown in FIG. FIG. 4 is a diagram showing characteristics in a macro area of the embodiment shown in FIG. 1, particularly a macro photographable range, and FIG. 4 is a flowchart showing an operation sequence of the embodiment shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Optical axis, 2 ... Magnification optical system, 2a-2c ... 1st-5th group, 3 ... Focus lens group, 4 ... Magnification drive part, 5 ... Focus drive part, 6 …… End detection unit 7… Focus lens group position detector (FPM) 8… Focal length detector (ZPM) 9… Area judgment unit 10… Focus detection unit 11… Focus control Unit, 11a release unit, 11b inhibition unit, 12 determination instruction unit, 13 macro information providing means, 13a macro display control unit, 13b display unit, 14 scaling control unit , Fm: Film surface, + V: Power supply, 23: Maximum defocus curve, 24: Limit curve, 31: Approximate limit line, 38: Macro photographable range.

Continuation of the front page (56) References JP-A-63-85709 (JP, A) JP-A-60-10215 (JP, A) JP-A-62-79408 (JP, A) JP-A-59-204813 (JP, A) JP-A-60-218613 (JP, A) JP-A-62-9234 (JP, U) JP-A-58-103004 (JP, U)

Claims (1)

(57) [Claims] 1. A photographing lens having a variable magnification region and a macro region capable of macro photographing, and receiving a light from a focusing object transmitted through the photographing lens and setting an imaging position of the focusing object with respect to a predetermined focal position. Focus detection means for detecting the direction of the shift and the focus state; and when the focus detection means determines out of focus, the focus lens of the photographing lens is started to move in the focusing direction, and the focus is determined. And a drive means for stopping the movement, and an end point detecting means for detecting whether the drive position of the focusing lens of the photographing lens has reached the end of the drive range in the variable magnification area, Prohibition means for prohibiting operation of the driving means when the end detection is performed by the end detection means, and deviation from the focus detection means immediately before and immediately after the end detection in response to the end detection by the end detection means. Comparing the direction data, and releasing means both cancels the prohibition operation of the inhibiting means in the case of disagreement,
Area determining means for determining whether or not the taking lens is located in the macro area; and, when the area determining means determines that the taking lens is not located in the macro area, end detection from the end detecting means. The driving directions of the focusing lens obtained from the focus detecting means immediately before and after the focus detecting means are compared, and when both coincide with each other and the driving direction is the close-up direction, the photographing lens is set in the macro area. And a macro information providing means for outputting promotion information indicating that the camera should be moved to the automatic focus adjustment device.