JP4695894B2 - Lens control device and imaging device - Google Patents

Description

  The present invention relates to a lens control device that controls an inner focus type lens system and an imaging device such as a video camera equipped with the lens control device.

  In recent autofocus (hereinafter referred to as AF) devices of video cameras, an imaging element is not used because of a request for miniaturization or the like, but using a distance measuring sensor that directly measures a subject distance as seen in a so-called film camera. For example, a method of detecting the sharpness of an image from a video signal obtained by photoelectrically converting a subject image by the method and determining the focus lens position so as to maximize the AF evaluation value is the mainstream.

  The AF control algorithm will be described in detail with reference to FIGS. 13, 14, and 15. FIG. This algorithm is generally called a TV-AF system. The main AF process will be described with reference to the flowchart of FIG.

  The AF process is started from step S301 in FIG. 13, and first, in step S302, a minute driving operation is performed. Details of this will be described later with reference to the flowchart of FIG. In the next step S303, if the in-focus state is determined in step S302, the process proceeds to step S309 to perform a focus / restart determination process. If the in-focus state is not determined in step S302, the process proceeds to step S304. move on. In step S304, if the in-focus direction can be determined, the process proceeds to step S305, hill-climbing processing is performed. If the in-focus direction cannot be determined, the process returns to step S302, and the minute driving operation is continued.

  In step S305, the focus lens is hill-climbed and driven at a high speed in the direction in which the evaluation value increases. Details will be described later with reference to the flowchart of FIG. In the next step S306, if it is determined in step S305 that the evaluation value has exceeded the peak, the process proceeds to step S307. If it is not determined in step S305 that the evaluation value has exceeded the peak, the process returns to step S305. Continue climbing. In the next step S307, an operation of returning the focus lens to the focus lens position having the peak evaluation value during hill-climbing driving is performed. Then, in the next step S308, it is determined whether or not the peak focus lens position has been reached. If the peak lens position has been reached, the process returns to step S302, and the minute driving operation is performed again. If the peak has not been reached in step S307, the process returns to step S307 and the operation of returning to the peak is continued.

  Next, the focus / restart determination process from step S309 will be described. In step S309, the AF evaluation value at the focal point is held. In the next step S310, the latest AF evaluation value is captured. In the subsequent step S311, the AF evaluation value held in step S309 is compared with the latest AF evaluation value, and it is determined whether the AF evaluation value varies greatly. If the AF evaluation value has greatly fluctuated, the process returns to step S302 to resume the minute driving operation, and if the AF evaluation value has not fluctuated, the process proceeds to step S312. In step S312, the focus lens is stopped and the process returns to step S310, and the focus / restart determination process is continued.

  Next, the minute driving operation executed in step S302 of FIG. 13 will be described using the flowchart of FIG. The process starts from step S401. First, in step S402, an AF evaluation value is taken from the AF evaluation value processing circuit. In the next step S403, if the evaluation value fetched in step S402 is smaller than the previous evaluation value, the process proceeds to step S404. If the evaluation value is larger than the previous evaluation value, the process proceeds to step S405. In step S404, the focus lens is driven by a predetermined amount in the reverse direction of the previous time. On the other hand, in step S405, the focus lens is driven by a predetermined amount in the previous forward direction.

  In the next step S406, it is checked whether or not the direction determined to be the in-focus direction is the same continuously for a predetermined number of times, and if it is the same, the process proceeds to step S410. . In step S407, if the focus lens repeats reciprocation in the same area a predetermined number of times, the process proceeds to step S409. If the focus lens does not repeat reciprocation in the same area, the process proceeds to step S408, and the current process ends. In step S410, it is determined that the direction can be determined, the process proceeds to step S408, the process is terminated, and the hill-climbing drive is performed. In step S409, it is determined that the in-focus state has been determined, and the process proceeds to step S408, where the process ends and the process proceeds to restart determination.

  Next, the hill-climbing driving operation will be described using the flowchart of FIG. The process starts from step S501. First, in step S502, an AF evaluation value is fetched from the AF evaluation value processing circuit. Then, in the next step S503, it is determined whether or not the evaluation value fetched in S502 is larger than the previous evaluation value. If larger, the process proceeds to step S504, and the evaluation value fetched in step S502 is smaller than the previous evaluation value. If so, the process proceeds to step S506. In step S504, the focus lens is driven at a predetermined speed in the previous forward direction, and the process proceeds to the next step S505 to end the current process. On the other hand, if the evaluation value has decreased beyond the peak in step S506, the process proceeds to S505, the process is terminated, and the process proceeds to micro driving. If the evaluation value does not decrease beyond the peak, the process proceeds to step S507, the focus lens is driven at a predetermined speed in the direction opposite to the previous time, the process proceeds to step S505, and the current process ends.

  As described above, focusing is performed by moving the focus lens while repeating restart determination → micro drive → mountain climbing → micro drive → restart determination, and AF control is performed so that the AF evaluation value is always maximized. To maintain.

  Here, when shooting a subject whose AF evaluation value fluctuates from moment to moment, for example, a firework that shines intensely in the night sky for a short time, the subject distance is infinite in a normal shooting situation, Since the evaluation value fluctuates, there is a problem that it is difficult to keep the focus lens position equivalent to infinity. As a demerit of the TV-AF method, since an image signal is used, the AF evaluation value may vary depending on the subject itself and photographing conditions even if the subject distance does not change. In the TV-AF method, as described above, when the AF evaluation value fluctuates from the state where the focus lens is in focus and stopped, the focus lens starts to move to detect the peak of the AF evaluation value. This is a method for determining a focus lens position to be focused on the imaging surface by detecting. That is, if the AF evaluation value fluctuates, the peak of the AF evaluation value cannot be detected unless the focus lens is actually moved. Therefore, even if the subject distance does not change, there is a drawback that the focus lens is moved depending on the subject itself and the change of the photographing condition.

  As shown in the TV-AF algorithm shown in FIGS. 13 to 15 described above, in-focus determination can be made, and when the AF evaluation value fluctuates greatly in a state where the focus lens is stopped (step S312 in FIG. 13), minute driving is performed. The mode (step S302) is entered. Furthermore, when the AF evaluation value changes in the same direction for a predetermined number of times in step S406 in FIG. 14, the hill-climbing drive mode (step S305) is entered. In other words, the TV-AF algorithm acts as if the subject distance has changed when the AF evaluation value fluctuates, and actively searches for the changed subject distance. However, since the AF evaluation value is generated from the video signal, the AF evaluation value fluctuates even when the subject itself changes without changing the subject distance. Further, the AF algorithm itself has a variation in the AF evaluation value. It is not possible to distinguish whether the distance has changed or the subject itself has changed.

  Therefore, when shooting a subject like the above-mentioned fireworks, the movement of the focus lens position is changed positively due to the fluctuation of the AF evaluation value. As a result, the focus lens position, that is, the out-of-focus blur condition is hunted. May end up. Furthermore, although the AF operation of the video camera is performed with reference to a standard television signal, the AF control period is 1/60 seconds for an NTSC television signal and 1/50 seconds for a PAL television signal. Usually, since the AF algorithm shown in FIGS. 13 to 15 is focused by repeating a plurality of cycles, it takes some time to focus on the subject. For this reason, the focus lens position control may not follow the fireworks where the subject changes remarkably in a very short time, and the hunting of the blur condition may become more remarkable. Similarly, in the case of shooting a night sky or a mountain, it may be difficult to keep a focus lens position control state equivalent to infinity, although it is desired to shoot a subject at an infinite distance.

  As a method proposed for the above-mentioned problem, a forced infinity function is generally put into practical use, in which a photographer operates a specific switch, for example, an infinity switch to force the subject distance to infinity. Yes. Furthermore, when the lens has been moved to a position corresponding to infinity, a configuration is generally used in which the movement completion state is indicated on the monitor device, the photographer is notified that the movement is completed, and operability is improved.

  In addition to the infinity, a function for forcibly reproducing the subject distance arbitrarily set by the photographer has been widely put into practical use and is generally called a focus preset. Furthermore, during the focus preset operation, the speed of movement to the preset position is increased compared to that during normal AF control, so that the lens position can be adjusted more quickly to match the desired subject distance. A method for preventing missed opportunities has also been proposed (see, for example, Patent Document 1).

  By the way, in a consumer integrated camera, the correction lens and the variable power lens are not mechanically linked by a cam in response to a request for downsizing and the like, but the movement locus of the correction lens is stored in advance in the microcomputer as lens cam data. An inner focus type lens that drives a correction lens in accordance with the lens cam data and also adjusts the focus by the correction lens has become mainstream.

  FIG. 6 shows a simple configuration of a conventional inner focus type lens system. In the figure, 101 is a fixed first lens group, 102 is a second lens group for zooming (hereinafter referred to as a zoom lens), 103 is a stop, and 104 is a fixed third lens group. A lens group 105, a fourth lens group (hereinafter referred to as a focus lens) having a focus adjustment function and a function of correcting the movement of the focal plane due to zooming (so-called competition function), and 106 an imaging surface (CCD ).

  As is well known, in the lens system configured as shown in FIG. 6, since the focus lens 105 has both a competition function and a focus adjustment function, the focus lens for focusing on the imaging surface 106 even if the focal lengths are equal. The position 105 varies depending on the subject distance. When the subject distance is changed at each focal length, the position of the focus lens 105 for focusing on the imaging surface is continuously plotted as shown in FIG.

  In the control of the inner focus type lens system, it is impossible to store the focus lens position corresponding to the desired subject distance by simply storing the lens position itself. The plural pieces of locus information shown in FIG. 7 are stored in some form (the locus itself or a function with the lens position as a variable), and the locus is selected according to the lens position corresponding to the subject distance to be reproduced, In general, the focus lens position is determined based on the position of the zoom lens.

Next, a method for specifying a cam locus corresponding to the subject distance to be reproduced from a plurality of pieces of locus information shown in FIG. 7 required for the focus preset function or the like will be described. 8, Z ₀ , Z ₁ , Z ₂ ,..., Z ₆ indicate zoom lens positions, and a ₀ , a ₁ , a ₂ ,... A ₆ and b ₀ , b ₁ , b ₂ ,. ... b ₆ is a representative trace stored in advance in the microcomputer. Further, p ₀ , p ₁ , p ₂ ,... P ₆ are trajectories calculated based on the two trajectories. The calculation formula of this locus is shown below.

p _{(n + 1)} = | p _(n) -a _(n) | / | b _(n) -a _(n) |
* | B _{(n + 1)} -a _{(n + 1)} | + a _{(n + 1)} (1)
According to the above equation (1), for example, in FIG. 8, when the focus lens is at p ₀ , a ratio by which p ₀ internally divides line segment b ₀ -a ₀ is obtained, and line segment b _1- By setting p _{1 as} the point that internally divides a ₁ , the focus lens position p ₁ at which the subject distance does not change even when the zoom lens position, that is, the focal length changes from Z ₀ to Z ₁ can be found. At this time, | p _(n) −a _(n) | and | b _(n) −a _(n) | constituting the internal ratio are set as subject distance information α and β, respectively.

Next, a case where the stop position of the zoom lens is not limited only on the boundary having the stored representative trajectory data will be described. FIG. 9 is a diagram for explaining an interpolation method in the zoom lens position direction, in which a part of FIG. 8 is extracted and the position of the zoom lens is arbitrary. In FIG. 9, the vertical axis indicates the focus lens position, and the horizontal axis indicates the zoom lens position. The representative locus position (the focus lens position with respect to the zoom lens position) stored in the lens control microcomputer is represented by the zoom lens position Z ₀ , When Z ₁ ,... Z _k−1 , Z _k .
_{a 0, a 1, ...... a} k-1, a k ...... a n
b ₀ , b ₁ ,... b _k−1 , b _k ...... b _n
It is said.

Now, when the zoom lens position is at Z _x not on the zoom boundary and the focus lens position is P _x , a _x and b _x are obtained as follows:
_{a x = a k - (Z} k -Z x) * (a k -a k-1) / (Z k -Z k-1) ...... (2)
b _x = b _k − (Z _k −Z _x ) * (b _k −b _k−1 ) / (Z _k −Z _k−1 ) (3)
It becomes. That is, according to the internal ratio obtained from the current zoom lens position and the two zoom boundary positions (Z _k and Z _k-1 in FIG. 9) sandwiching it, the stored four representative trajectory data (in FIG. 9, ax, bx can be obtained by internally dividing the same subject distance among a _k , a _k−1 , b _k , b _k−1 ) by the above internal ratio.

At this time, an example of a data table of trajectory information stored in advance in the microcomputer is shown in FIG. FIG. 10 shows focus lens position data A (n, v) that varies depending on the zoom lens position for each subject distance. The subject distance is in the column direction of the variable n, and the zoom lens position (focal length) is in the row direction of the variable v. Has changed. Here, n = 0 represents a subject distance at infinity, the subject distance changes to a close distance as n increases, and n = m represents a subject distance of 1 cm. On the other hand, v = 0 indicates the wide end, the focal length increases as v increases, and v = s indicates the zoom lens position at the tele end. Therefore, one cam locus is drawn by one column of table data. At this time, corresponding to the representative trajectory a ₀ ...... a _n described above in FIGS. 8 and 9, the value of the variable n in FIG. 10 and object distance information gamma.

  By using the subject distance information α, β, and γ, the cam locus corresponding to the subject distance to be reproduced can be specified from the plurality of pieces of locus information shown in FIG. Then, α, β, and γ calculated from the current focus lens position are stored, and the focus lens position that can be focused at the same subject distance even if the focal length changes by following the reverse procedure described above Can be played.

  Next, the algorithm of the forced infinity function in the control of the inner focus type lens system will be described with reference to the flowcharts of FIGS. FIG. 11 shows a subroutine of the forced infinity function, and this subroutine is called from the algorithm of the entire microcomputer process.

The operation is started from step S901. First, in step S902, values corresponding to infinity are set in predetermined subject distance information α _P and γ _P applied when the forced infinity function is activated. In the next step S903, the current zoom lens position Z _x is on the table of FIG. 10, calculates whether present in ordinal number of the zoom area v in which the s aliquoted from the wide-angle end to the telephoto end. The calculation method will be described with reference to the flowchart of FIG.

The process starts from step S1001 of FIG. 12, and first, in step S1002, the zoom area variable v is cleared. In the next step S1003, the following expression (5) Z (v) = (zoom position at tele end−zoom position at wide end)
* V / s + wide end zoom position (5)
Accordingly, the zoom lens position Z (v) on the boundary of the area v is calculated. This Z (v) corresponds to the zoom lens positions Z ₀ , Z ₁ , Z ₂ ... Shown in FIG. In step S1004, Z obtained in step S1003 (v) is determined whether or equal to the current zoom lens position _{Z x,} equal, the zoom lens position _{Z x} is to step S1008 as are on the boundary of the zone v Then, the boundary flag = 1 is set, and the process returns to step S904 in FIG. 11 via step S1009. On the other hand, if it is not equal in step S1004 proceeds to step _S1005, and determines whether the Z x <Z (v), if wherein a _{Z x <Z (v),} Z x is Z (v-1 ) And Z (v). At this time, the process proceeds to step S1007, where the boundary flag = 0 is set, and the process returns to step S904 in FIG. 11 via step S1009. If it is determined in step S1005 that Z _x <Z (v) is not satisfied, the process proceeds to step S1006, the zoom zone v is incremented, and the process returns to step S1003.

By repeatedly performing the above processing, when exiting FIG. 12, the current zoom lens position Z _x is present in the v = kth (k is a variable) zoom area on the table of FIG. You can know if it exists.

Returning to Figure 11, at step S904, the steps S905 as the zoom lens position Z _x is determined whether present on the boundary of the zoom area (boundary flag = 1), not in the boundary flag = 0 boundary Proceed to the process. In step S905, Z _k ← Z (v), Z _k−1 ← Z (v−1). In the subsequent step S906, four table data A (γ _P , v−1), A (γ _P , v), A (γ _P + 1, v−1), using the predetermined subject distance γ _P described above, A (γ _P +1, v) is read, and a _x and b _x are calculated from the above-described equations (2) and (3) in the next step S908. On the other hand, if it is determined in step S904 that the boundary flag = 1, the process proceeds to step S907, and the predetermined subject distance γ _P , the focused focus position A (γ _P , v) of the zoom area v, and A (γ _P +1). , V) and store them as a _x and b _x , respectively.

In the next step S909, it determines the state of infinite switch, if it is on the flow proceeds to step S910, focusing the focus position at the zoom position Zx (target lens position) _{P Y} a _{P Y = (b x -a x} ) * α / β + a _x (6)
Calculate with the following formula. In this example, α = 0 and γ = 0, that is, the infinite end is set, so that P _Y = a _x is substantially obtained. Then, in the next step S911, the lens moving speed is set. This moving speed is a constant value. In step S912, the lens is moved. In the subsequent step S913, it is checked whether or not the focus lens position has reached the infinite end. If it is determined that the focus lens position has not arrived, the process proceeds to step S912 to continue the lens movement. If it is determined that it has reached the infinite end, the process proceeds to step S914 to stop the movement of the lens, and in step S915, an infinite mark is displayed on the monitor device.
JP-A 63-177117

  As described in the above conventional example, when the subject distance is forced to infinity with the inner focus type lens, the moving speed is constant (step S911 in FIG. 11). However, as shown in FIG. 7, if the focal length is different, the distance difference between the infinite end and the closest end of the focus lens position is different. In particular, the distance difference is the shortest when the focal length is the wide end, and the distance difference is the longest when the focal length is the tele end. Furthermore, the focus lens position is different if the subject distance is different, for example, when the subject is focused on a subject 80 cm ahead and when the subject is focused on a subject 3 m ahead. Therefore, when moving from the current focus lens position to the focus lens position equivalent to infinity with the forced infinity function as shown in the above-mentioned conventional technology, or with the focus preset function arbitrarily from the current focus lens position When moving to the focus lens position corresponding to the set subject distance, the focus lens moving distance varies depending on the focal length and the subject distance. As a result, the travel time was different.

  There are the following problems when the travel time is different as described above. When the infinite switch was pressed at the close end at the wide end, it took about a few seconds for the movement time. On the other hand, when the infinite switch is pressed at the close end at the tele end, the travel time required several seconds. The operation time of the forced infinity function recognized by the photographer is the time from when the infinity switch is operated until the end of the lens movement is determined and the infinity mark is displayed on the monitor screen, which is almost the same as the above movement time It is. Here, from the experience of operating the forced infinity function at the wide end, the photographer predicted that the operation time was about a few seconds of commas, but when pressing the infinite switch, it was at the tele end. Actually, it took several seconds, and it took about several seconds longer than expected until the infinite mark was displayed, and the operation was uncomfortable. Similarly, the operation time becomes non-uniform depending on the focal length and the subject distance, and the photographer's sense does not match the camera operation, resulting in stress. Due to the nature of the camera product, there is a demand for quickly responding to sudden shooting opportunities, and there is a growing demand for improving responsiveness in seconds. As multifunctional functions of various home appliances including cameras have progressed in recent years, there has been a demand for a comfortable operation that is stress-free and sensuous, and the need to solve the above problems has also increased.

(Object of invention)
The object of the present invention is to provide a comfortable operability to the user by making the time for moving the focusing lens group to a desired position constant regardless of the focal length and the distance to the measuring object. A lens control device and an imaging device are to be provided.

In order to achieve the above object, according to the first aspect of the present invention, the position of the second lens group that obtains the in-focus position is set at the zoom position of the first lens group that performs the zooming operation that varies the focal length. Storage means for storing in accordance with the measurement target distance; target position determination means for determining a target position of the second lens group corresponding to a predetermined measurement target distance with reference to data stored in the storage means; , Speed determining means for determining a driving speed for moving the second lens group, operating means for moving the first lens group, and the first position to the target position determined by the target position determining means. An instruction means for instructing movement of the second lens group , wherein the speed determining means, when instructed by the instruction means, starts the operation from the position of the second lens group. Moved by means Serial to the target position determined by the target position determination means according to the position of the first lens group, the driving time for moving the second lens group, the second lens group position placed et the The lens control device is made constant regardless of the moving distance to the target position.

Similarly, in order to achieve the above object, according to a second aspect of the present invention, the position of the second lens group that obtains focus at the magnification position of the first lens group that performs the magnification operation that varies the focal length. And a target position determining means for determining a target position of the second lens group corresponding to a predetermined measurement target distance with reference to data stored in the storage means. Speed determining means for determining a driving speed for moving the second lens group, operating means for moving the first lens group, and the target position determined by the target position determining means. An instruction means for instructing the movement of the second lens group , wherein the speed determining means, when instructed by the instruction means, from the position of the second lens group , Transfer by operating means The said first to the target position determined by the target position determination means according to the position of the lens group, said second driving time when moving the lens group, the second lens group in position placed al The lens control device determines the speed so as to be constant regardless of the moving distance to the target position.

  Similarly, in order to achieve the above object, a fourth aspect of the present invention is an imaging apparatus including the lens control device according to any one of the first to fourth aspects.

  According to the present invention, the time for moving the focusing lens group to a desired position can be made constant without depending on the focal length and the distance to the measurement target, and comfortable operability can be given to the user. A lens control device or an imaging device can be provided.

  The best mode for carrying out the present invention is as shown in Example 1 and Example 2 described below.

  FIG. 1 is a block diagram illustrating a circuit configuration of the imaging apparatus according to the first embodiment of the present invention. In the figure, reference numeral 1101 denotes a fixed first lens group, 1102 denotes a second lens group for zooming (hereinafter referred to as a zoom lens), 1103 denotes a stop, 1104 denotes a fixed third lens group, and 1105 denotes zooming. This is a fourth group lens (hereinafter referred to as a focus lens) that has both a function of correcting the movement of the focal plane and a function of focusing. Reference numeral 1106 denotes a CCD, which is an image sensor, and 1107 denotes a CDS / AGC (a circuit that performs double correlation sampling / automatic gain control) that samples the output of the CCD 1106 and adjusts the gain. A camera signal processing circuit 1108 processes an output signal from the CDS / AGC 1107 into a signal corresponding to the recording device 1109 and sends the signal to the recording device 1109. At the same time, the signal is also sent to the LCD display circuit 1116 to display the photographed image on the LCD 1117. To do. The LCD 1117 is displayed to notify the photographer of the shooting mode, shooting state, warning, etc., but the microcomputer 1121 controls the character generator 1115 and the output signal of the character generator 1115 is mixed by the LCD display circuit 1116. By doing so, it is superimposed on the captured image.

  Reference numeral 1110 denotes a motor that is an actuator for moving the zoom lens 1102, and reference numeral 1111 denotes a driver that drives the motor 1110 with a signal from a motor control unit 1122 described later. Reference numeral 1112 denotes a motor that is an actuator for moving the focus lens 1105, and reference numeral 1113 denotes a driver that drives the motor 1112 by a signal from a motor control unit 1122 described later. Reference numeral 1114 denotes an AF evaluation value processing circuit for extracting a high frequency component (that is, an AF evaluation value) used for focus detection from the output signal of the CDS / AGC 1107.

  Reference numeral 1118 denotes a zoom switch that detects the zoom operation state of the photographer. Reference numeral 1119 denotes an MF (manual focus) switch, which is a so-called push switch, and alternately selects AF and MF every time it detects ON. A focus switch 1120 detects a focus lens position operation state of the photographer when MF is selected by the MF switch 1119. Reference numeral 1126 denotes an infinite switch. A cam data storage unit 1125 stores a zoom lens position and a focus lens position corresponding to the subject distance. Reference numeral 1124 denotes a zoom control unit, which determines the zoom lens position and the focus lens position with reference to the data stored in the cam data storage unit 1125 according to the zoom operation state and AF evaluation value detected by the zoom switch 1118 in normal times. When the MF is selected by the MF switch 1119, the focus lens position is determined according to the operation of the focus switch 1120. When it is detected that the infinite switch 1126 is turned on, the focus lens position is determined with the subject distance set to forced infinity. Reference numeral 1123 denotes an AF control unit that adjusts the focus lens position, that is, the focus position, based on the output signal of the AF evaluation value processing circuit 1114. A motor control unit 1122 controls the drivers 1111 and 1113 to drive the zoom lens 1102 and the focus lens 1105.

  Next, the forced infinity operation in the imaging apparatus having the above configuration will be described with reference to the flowchart of FIG. In addition, the same step number is attached | subjected to the part which performs the same operation | movement as FIG. 11 of the said prior art example. The difference from FIG. 11 is that the processing in step S911 in FIG. 11 is changed to the processing in steps S1201 and S1202.

  In FIG. 2, the processing in steps S901 to S908 is the same as that in FIG. In step S909, the state of the infinite switch 1126 is determined. If it is off, the process proceeds to step S916, and the infinite mark is not displayed on the monitor screen.

On the other hand, infinite switch 1126 if it is on, the process proceeds from step S909 to step S910, and calculates the focus position focus the zoom position _{Z x} (target lens position) _{P Y} in the above formula (6). In this example, α = 0 and γ = 0, that is, the infinite end is set, so that P _Y = a _x is substantially obtained. In the next step S1201, the lens movement distance is ΔP, the current lens position is P _X , and the target lens position is P _Y.
ΔP = P _Y −P _X (7)
It is calculated by the following formula.

In the subsequent step S1202, the lens moving speed is set to T as the target arrival time.
V _P = ΔP / T (8)
It is calculated by the following formula. Then, in the next step S912, the lens is moved. In subsequent step S913, it is checked whether or not the focus lens position has reached the infinite end. If it is determined that the focus lens position has not reached the infinite end, the process returns to step S912 to continue the lens movement. If it is determined that the vehicle has arrived at the infinite end, the process proceeds to step S914, the movement of the focus lens 1105 is stopped, and an infinite mark is displayed on the monitor device in the subsequent step S915.

  According to the first embodiment, when the focus lens 1105 is driven from the current focus lens position to the focus lens position corresponding to infinity by the forced infinity function, the current position of the focus lens 1105 is different. Even if the distances are different, processing (steps S1201 and S1202) is performed so that the time from the current focus lens position to the target position corresponding to infinity is always constant. Therefore, regardless of the focal length and subject distance at the start of forced infinity operation, the time until the infinity mark is displayed is constant, and the photographer can operate sensibly and stress-free, high-quality forced infinity Functions can be realized. That is, the time for moving the focus lens 1105 to a desired position can be made constant without being influenced by the focal length or the subject distance, and comfortable operability can be given to the user.

  In particular, when moving from the close-up end to the infinite end, there is the largest difference between the focus lens position at the close end and the infinite end when the zoom position is at the wide end and at the tele end. The difference in distance becomes large, but even in this case, the waiting time can be made constant because the speed is set according to the moving distance. For example, when operating the subject distance from the closest end to forced infinity, regardless of whether the focal length is at the wide end or the tele end, there will always be a uniform operation completion waiting time. Can be operated comfortably, and higher operability can be realized.

  FIG. 3 is a block diagram illustrating a circuit configuration of the imaging apparatus according to the second embodiment of the present invention. 1 differs from the first embodiment shown in FIG. 1 in that a preset position storage unit 1127 for storing an arbitrary subject distance, a preset distance storage switch 1128 for storing the subject distance in the preset position storage unit 1127, and a preset position storage unit. A preset position reproduction switch 1129 for detecting an operation of adjusting the focus lens position to the subject distance stored in 1127 is added.

  Next, a focus preset operation in the imaging apparatus having the above configuration will be described with reference to the flowchart of FIG. Parts that perform the same operation as in FIG. 2 are given the same step numbers. The difference from FIG. 2 is that the processing in steps S902, S909, S913, S915, and S916 in FIG. 2 is changed to the processing in steps S1401 to S1405.

  In FIG. 4, a step S1401 specifies the shooting distance of the subject being shot from the current positions of the zoom lens 1102 and the focus lens 1105, and the subject distance information is used as three trajectory parameters α, β, and γ in a RAM or the like. This processing routine is stored in the memory area, and when the preset distance storage switch 1128 is turned on, these trajectory parameters are stored as preset distances in the preset position storage unit 1127, and the details will be described with reference to the flowchart of FIG. Here, for the sake of simplicity, description will be made assuming that the in-focus state is maintained at the current lens position.

Starts the process from step S1501 in FIG. 5, first, in step S1502, the current zoom lens position Z _x is on the table of FIG. 10, present in the ordinal number of the zoom area v in which the s aliquoted from the wide-angle end to the telephoto end Is calculated. The calculation method is as described above with reference to FIG. 12, and details thereof are omitted here. When the zoom area v is determined in step S1502, the following processing calculates where the focus position is on the table of FIG. First, in step S1503, the subject distance variable n is cleared, and in the next step S1504, it is determined whether or not the current zoom lens position exists on the boundary of the zoom area (boundary flag = 1). If flag = 0, it is determined that it is not on the boundary, and the process proceeds to step S1505. Here, Z _k ← Z (v), Z _k−1 ← Z (v−1). Then, in the next step S1506, the four table data A (n, v−1), A (n, v), A (n + 1, v−1), A (n + 1, v) are read, and the following step S1508 is performed. Then, a _x and b _x are calculated from the above equations (2) and (3).

If it is determined in step S1504 that the boundary flag = 1, the process proceeds to step S1507, and the subject distance n, the focus position A (n, v) of the zoom lens position v, and A (n + 1, v). Are stored as a _x and b _x respectively.

In the next step S1509, the current focus position _{P x} is determined whether there are more _{a x,} the process proceeds to step S1510 if more _{a x, P x} is the one of the determination or _{b x.} Here, if P _x is not greater than or equal to b _x , P _x is between the subject distances n and n + 1, and thus the process proceeds to step S1514, α = P _x −a _x is set, and in the next step S1515, β = b _x −a _x, and in subsequent step S1516, γ = n. That is, the trajectory parameters at this time are stored in the memory in steps S1514 to S1516.

In step S1509, it is determined that the current focus position P _x is less than a _x when the focus position P _x is infinite. In this case, α = 0 in step S1513, and then step S1515. , S1516, and infinite trajectory parameters are stored.

In step S1510, P _x is determined to be greater than or equal to b _x because P _x is closer to the closest side, so the process proceeds to step S1511. Here, the subject distance n is incremented, and the next step S1512 is performed. In step S1504, it is determined whether n is the closest subject distance m or less.

Further, the n in the step S1512 is determined to exceed the closest object distance m are the case _{where P x} is in very short, at step S1515,1516 this time from the step S1513, the closest Memorize the trajectory parameters of the distance.

In the next step S1517, the state of the preset distance storage switch 1128 is determined. If it is OFF, the process proceeds to step S1519 as it is, and the process is terminated. On the other hand, if the preset distance storage switch 1128 is on, the process proceeds to step S1518, where α determined in step S1513 or S1504, β determined in step S1515, and γ determined in step S1516 are preset subject distance α _P = The preset position storage unit 1127 stores α, β _P = β, and γ _P = γ. Then, the process proceeds to step S1519, and the process ends.

  Thereafter, the process returns to step S903 in FIG. Since Steps S903 to S908 are the same as those in FIG. 11, the description thereof is omitted.

  In the next step S1402, the state of the preset position reproduction switch 1129 is determined. If it is off, the process proceeds to step S1405, and the preset mark is not displayed on the monitor screen.

When it is determined that the preset position reproduction switch 1129 in step S1402 is ON processing proceeds to step S910, calculates focus focus position at the zoom position Zx (target lens position) _{P x} in the above formula (6) To do. In the next step S1201, the lens movement distance is ΔP, the current lens position is P _X , and the target lens position is P _Y, and calculation is performed using the above-described equation (7). In the subsequent step S1202, the lens moving speed _{V P,} the target arrival time as T, is calculated by the aforementioned equation (8). In the next step S912, the lens is moved. In step S1403, it is checked whether the focus lens position has arrived at the preset position. If it is determined that the focus lens position has not arrived at the preset position, the process returns to step S912 to continue the lens movement. If it is determined that the camera has arrived at the preset position, the process proceeds to step S914, and the movement of the lens is stopped. In the next step S1404, a preset mark is displayed on the monitor screen.

  According to the second embodiment, when the focus lens 1105 is driven from the current focus lens position to the focus lens position at a preset position (an arbitrary subject distance equivalent position) by the focus preset function, the current position of the focus lens 1105 is determined. Therefore, even if the moving distance is different, processing is performed so that the time from the current focus lens position to the preset position that is the target position is always constant (steps S1401, S1201, and S1202). ing. Therefore, regardless of the focal length and subject distance at the start of the focus preset operation, the time until the focus preset mark is displayed is constant, and the photographer can operate sensibly and stress-free, high-quality focus preset function Can be realized. That is, the time for moving the focus lens 1105 to a desired position can be made constant without being influenced by the focal length or the subject distance, and comfortable operability can be given to the user.

1 is a block diagram illustrating a circuit configuration of an imaging apparatus according to Embodiment 1 of the present invention. It is a flowchart which shows the forced infinity operation | movement in the imaging device concerning Example 1 of this invention. It is a block diagram which shows the circuit structure of the imaging device concerning Example 2 of this invention. It is a flowchart which shows the focus preset operation | movement in the imaging device concerning Example 2 of this invention. It is a flowchart which shows the detailed operation | movement of step S1401 of FIG. It is a block diagram which shows the conventional inner focus type lens system. It is a figure which shows the relationship between the focus lens position used in a focus preset function etc., and a zoom lens position. It is a figure which shows the example of the representative locus | trajectory of the focus lens position previously stored in the microcomputer etc., and a zoom lens position. It is a figure for demonstrating the interpolation method of a zoom lens position direction. It is a figure which shows the data table which is the relationship of the focus lens position which changes with zoom lens positions for every object distance. It is a flowchart which shows the infinity operation | movement in the conventional imaging device. 14 is a flowchart illustrating main AF processing in a general imaging apparatus. It is a flowchart which shows the detail of the micro drive operation | movement in FIG. It is a flowchart which shows the detail of the mountain climbing operation | movement in FIG.

Explanation of symbols

1102 Zoom lens (first lens group)
1105 Focus lens (second lens group) that has both a function to correct focal plane movement due to zooming and a focusing function
DESCRIPTION OF SYMBOLS 1108 Camera signal processing circuit 1110 Motor 1111 Driver 1112 Motor 1113 Driver 1114 AF evaluation value processing circuit 1121 Microcomputer (Storage medium, target position determination means, speed determination means)
1122 Motor control unit 1123 AF control unit 1124 Zoom control unit 1126 Infinite switch 1127 Preset position storage unit 1128 Preset distance storage switch 1129 Preset position reproduction switch

Claims (4)

Storage means for storing the position of the second lens group for obtaining focus at the magnification position of the first lens group that performs a magnification operation that varies the focal length according to the distance to be measured;
Target position determining means for determining a target position of the second lens group corresponding to a predetermined measurement target distance with reference to data stored in the storage means;
Speed determining means for determining a driving speed for moving the second lens group;
Operating means for moving the first lens group;
Instruction means for instructing movement of the second lens group to the target position determined by the target position determination means;
A lens control device comprising:
The speed determination means is determined by the target position determination means according to the position of the first lens group moved by the operation means from the position of the second lens group when the instruction means instructs. has been to the target position, the driving time for moving the second lens group, regardless of the moving distance to the position placed et the target position of the second lens group, characterized by a constant Lens control device. Storage means for storing the position of the second lens group for obtaining focus at the magnification position of the first lens group that performs a magnification operation that varies the focal length according to the distance to be measured;
Target position determining means for determining a target position of the second lens group corresponding to a predetermined measurement target distance with reference to data stored in the storage means;
Speed determining means for determining a driving speed for moving the second lens group;
Operating means for moving the first lens group;
Instruction means for instructing movement of the second lens group to the target position determined by the target position determination means;
A lens control device comprising:
The speed determination means is determined by the target position determination means according to the position of the first lens group moved by the operation means from the position of the second lens group when the instruction means instructs. has been to the target position, the driving time for moving the second lens group, regardless of the moving distance to the position placed et the target position of the second lens group, determining the rate to be constant A lens control device.   The lens control device according to claim 1, wherein the target position of the second lens group is set by an external operation as a position corresponding to an arbitrary measurement target distance.   An imaging apparatus comprising the lens control device according to claim 1.

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