JP2013130827A - Lens control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens control device that reduces occurrence of an image blur during zooming.SOLUTION: The lens control device that controls the drive of a second lens unit 105 in order to correct the movement of an image surface when a first lens unit 102 for varying power is moved comprises: storage means 120 storing data indicating the position of the second lens unit according to the position of the first lens unit, which data are created for a predetermined focal distance; control means 119 (116) configured to create information for controlling the drive of the second lens unit on the basis of the data, and to control the drive of the second lens unit on the basis of this information; distance detecting means 127 for detecting the distance of a focused object; and determination means for determining whether the limit of the range of the information is applied or not. According to photographing information and information about the operation state of the lens device, the determination means determines whether the limit of the range of the information is applied or not.

Description

  The present invention relates to a lens control device that controls a lens used in an optical apparatus such as a video camera.

  In Patent Document 1, an AF evaluation value signal (sharpness signal) obtained from a high-frequency component of a video signal by a contrast method is used to focus the focus lens from the in-focus position when the zoom lens is moved (magnification). A configuration for forcibly moving so as to shift is disclosed. Further, Patent Document 1 discloses a control method (zigzag operation) in which the focus lens is switched and moved so as to be in the in-focus direction (changes the tracking speed with respect to the trajectory). As a result, the tracking locus is corrected.

  However, since the AF evaluation value not only changes depending on the blurred state of the image, but also changes depending on the change in the pattern of the subject, the correction range of the tracking locus is set in a wide range. However, when a wide correction range is set, if the trajectory deviates from the original trajectory to follow, image blurring occurs before returning to the correct trajectory again.

  Therefore, Patent Document 2 discloses a zoom control method for limiting the movement range of the lens unit based on the detected distance to the in-focus object. In this zoom control method, the movement range of the lens unit is limited by setting the correction range of the tracking locus based on the detected distance to the in-focus object. For this reason, it is possible to avoid the generation of distance information that deviates from the original locus to be followed, and to reduce the occurrence of image blur during zooming.

Japanese Patent No. 2795439 JP 2010-164680 A

  However, in the zoom control method of Patent Document 2, the movement range is limited in all cases without taking the photographing conditions into consideration. For this reason, depending on the photographing conditions, there is a case where the restriction on the movement range of the lens unit is not appropriate. If the movement range is improperly limited in this way, image blur occurs during zooming.

  Therefore, the present invention provides a lens control device that reduces the occurrence of image blur during zooming.

  A lens control device according to one aspect of the present invention is a lens control device that controls movement of a first lens unit for zooming and a second lens unit for focus adjustment, and is created for each predetermined subject distance. , Storing means for storing data indicating the relationship between the position of the first lens unit and the position of the second lens unit, and generating information for controlling the movement of the second lens unit based on the data And control means for controlling movement of the second lens unit accompanying movement of the first lens unit, and detection means for detecting information corresponding to the subject distance, wherein the control means comprises the subject distance The movement range of the second lens unit is changed according to the information corresponding to the above and the shooting conditions.

  Other objects and features of the present invention are illustrated in the following examples.

  ADVANTAGE OF THE INVENTION According to this invention, the lens control apparatus which reduces generation | occurrence | production of the image blur during zooming can be provided.

1 is a configuration diagram of an imaging device (optical apparatus) equipped with a lens control device in Embodiment 1. FIG. It is a conceptual diagram which shows the correction range of the cam locus | trajectory in Example 1. FIG. 3 is a flowchart of zoom control of the lens control device in Embodiment 1. It is a flowchart of the zoom control in a present Example. It is a flowchart of the zoom control in a present Example. It is a flowchart of the zoom control in a present Example. It is a flowchart of the zoom control in a present Example. In this embodiment, it is a conceptual diagram showing a focus locus according to the subject distance. In this example, it is explanatory drawing of the locus | trajectory tracking method of the focus lens in the lens system of an inner focus type. In this example, it is explanatory drawing of the interpolation method in the moving direction of a zoom lens. In this embodiment, it is an example of table data of in-focus locus information stored in advance in a microcomputer. It is explanatory drawing of the locus | trajectory tracking method in a present Example. In this example, it is explanatory drawing of the calculation method of correction speed Vf + and Vf- according to correction amount parameter (delta). It is explanatory drawing of the distance measurement by the triangulation system in Example 1. FIG. It is explanatory drawing of the distance measurement by the phase difference detection system in Example 1. FIG. 5 is a flowchart for determining whether or not a correction range can be applied by the lens control device according to the first exemplary embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  First, schematic items in the present embodiment will be described. FIG. 9 is an explanatory diagram of a locus tracking method of the focus lens in the inner focus type lens system. 9, Z0, Z1, Z2,..., Z6 indicate zoom lens positions, and a0, a1, a2,..., A6 and b0, b1, b2,..., B6 are stored in advance in a microcomputer (not shown). The position of the focus lens according to the subject distance is shown. A set of focus lens positions (a0, a1, a2,..., A6 and b0, b1, b2,..., B6) is a focus locus (representative locus) that the focus lens should follow for each representative subject distance. )

  Further, p0, p1, p2,..., P6 are positions on the in-focus locus that should be followed by the focus lens, calculated based on the two representative loci. The position P (n + 1) on the in-focus locus is expressed by the following expression (1).

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, when the focus lens is at the position p0 in FIG. 9, the ratio at which the position p0 internally divides the line segment b0-a0 is obtained, and the line segment b1-a1 is internally divided according to this ratio. A point to be set is a position p1. From this position difference p1−p0 and the time required for the zoom lens to move from the position Z0 to Z1, the moving speed of the focus lens for maintaining focus can be obtained.

  Next, a case where there is no restriction that the stop position of the zoom lens is only on the boundary of the zoom area having the stored representative trajectory data will be described. FIG. 10 is an explanatory diagram of an interpolation method in the moving direction of the zoom lens, in which a part of FIG. 9 is extracted to arbitrarily set the position of the zoom lens.

  In FIG. 10, the vertical axis indicates the position of the focus lens, and the horizontal axis indicates the position of the zoom lens. When the zoom lens positions are Z0, Z1,..., Zk-1, Zk,..., Zn, the focus lens positions are a0, a1,. , B0, b1, ..., bk-1, bk, ..., bn. These relationships are stored in the microcomputer.

  Here, when the zoom lens is at a position Zx that is not on the boundary of the zoom area and the focus lens is at the position px, the positions ax and bx are expressed by the following equations (2) and (3), respectively.

ax = ak− (Zk−Zx) × (ak−ak−1) / (Zk−Zk−1) (2)
bx = bk− (Zk−Zx) × (bk−bk−1) / (Zk−Zk−1) (3)
That is, the positions ax and bx are obtained according to the internal ratio obtained from the current zoom lens position and two zoom area boundary positions (for example, Zk and Zk-1 in FIG. 10). More specifically, the positions ax and bx are those of the same subject distance among the four representative trajectory data (positions ak, ak-1, bk, bk-1 in FIG. 10) stored in the microcomputer. It is calculated | required by dividing internally with the above internal ratio. Then, according to the internal ratio obtained from the positions ax, px, bx, among the above four representative data stored in advance in the microcomputer, those having the same focal length are represented by the above-described internal ratio as shown in Equation (1). The positions pk and pk-1 can be obtained by dividing internally by.

  When zooming from wide to tele, in order to keep the focus from the difference between the focus position pk of the follow-up movement destination and the current focus position px and the time required for the zoom lens to move from the position Zx to the position Zk. It is possible to obtain the moving speed of the focus lens necessary for the operation. On the other hand, when zooming from tele to wide, the difference between the focus position pk-1 of the follow-up movement destination and the current focus position Px and the time required for the zoom lens to move from the position Zx to the position Zk-1 are combined. The moving speed of the focus lens for maintaining the focus can be obtained.

  FIG. 11 is an example of table data of in-focus locus information stored in advance in the microcomputer. FIG. 11 shows focus lens position data A (n, v) for each subject distance, which varies depending on the zoom lens position. The subject distance changes in the column direction of the variable n, and the zoom lens position (focal length) changes in the row direction of the variable v. Here, n = 0 represents a subject distance at infinity, and the subject distance changes to the closest distance side as n increases. n = m represents a subject distance of 1 cm. On the other hand, v = 0 represents the wide end. Furthermore, the focal length increases as v increases, and v = s represents the zoom lens position at the tele end. Therefore, one representative trajectory is drawn with one column of table data.

  Next, with reference to FIG. 12, a trajectory tracking method for solving the problem that the trajectory to be followed by the focus lens during zooming in the telephoto direction from wide can be solved. 12A and 12B, the horizontal axis indicates the position of the variable magnification lens (zoom lens). In FIG. 12A, the vertical axis indicates the AF evaluation signal obtained from the image pickup signal by the TV-AF method. This AF evaluation signal represents the level of the high-frequency component (sharpness signal) of the imaging signal. In FIG. 12B, the horizontal axis indicates the position of the focus lens. In FIG. 12B, reference numeral 1304 denotes a cam locus (collection of focus lens positions) that the focus lens should follow when performing zooming with respect to a subject located at a certain distance. Indicates the target trajectory.

  Here, the standard moving speed for tracking the in-focus locus on the wide side from the zoom lens position 1306 (position Z14) is positive (moves in the direction closer to the focus lens). Further, the standard moving speed for tracking the in-focus locus when the focus lens moves in the infinity direction on the telephoto side from the position 1306 is set to be negative. When the focus lens follows the target locus 1304 while maintaining the in-focus state, the magnitude of the AF evaluation signal becomes a level indicated as the maximum value 1301 in FIG. In general, in zooming with focus maintained, the AF evaluation signal level is a substantially constant value.

  In FIG. 12B, the standard moving speed of the focus lens that traces the target locus 1304 during zooming is Vf0. When zooming is performed while the actual moving speed of the focus lens is Vf and the moving speed Vf is made larger or smaller than the standard moving speed Vf0, the locus becomes a zigzag locus as indicated by 1305 (hereinafter referred to as such zooming operation). Is called “zigzag correction operation”). At this time, the AF evaluation signal level changes so as to generate peaks and valleys as indicated by reference numeral 1303 in FIG. At the position where the target locus 1304 and the actual zigzag locus 1305 intersect, the AF evaluation signal level 1303 has a maximum value 1301 (even points at positions Z0, Z1, Z2,..., Z16). Also, the AF evaluation signal level 1303 has a minimum value 1302 at odd points of positions Z0, Z1, Z2,..., Z16 at which the movement direction vector of the actual locus 1305 switches.

  On the other hand, a value TH1 that is the minimum value 1302 of the AF evaluation signal level 1303 is set in advance (that is, an in-focus allowable range with the AF evaluation signal at the minimum level TH1 that can be regarded as in-focus is set as a lower limit). Each time the AF evaluation signal level 1303 is equal to TH1, the moving direction vector of the locus 1305 is switched. Thereby, the moving direction of the focus lens after switching is set to a direction approaching the target locus 1304. That is, every time an image is blurred by the difference between the maximum value 1301 and the minimum value 1302 (TH1) of the AF evaluation signal, the driving direction and the driving speed, which are driving conditions of the focus lens, are controlled so as to reduce this blur. Zooming with reduced amount of generation becomes possible.

  By using such a method, the standard moving speed Vf0 for maintaining the focus is optimal with respect to the subject distance at that time in zooming from wide to tele where the focus locus for each subject distance diverges from convergence. Even if it is not, it is possible to respecify the in-focus locus. FIG. 8 is a conceptual diagram showing a focus locus according to the subject distance. Switching as shown by the locus 1305 according to the change in the AF evaluation signal level while controlling the moving speed Vf of the focus lens with respect to the standard moving speed calculated based on the position p (n + 1) obtained from the expression (1). Repeat the operation. Thereby, the refocusing (regeneration) of the in-focus locus can be performed without the AF evaluation signal level falling below the minimum value 1302 (TH1), that is, without causing a certain amount of blurring. Further, by appropriately setting TH1, it is possible to perform zooming so that image blur cannot be visually recognized.

  Here, the moving speed Vf of the focus lens is represented by the following expression (4) or expression (5), where Vf + is a correction speed in the positive direction applied to the standard movement speed and Vf− is a correction speed in the negative direction. It is expressed in

Vf = Vf0 + Vf + (4)
Vf = Vf0 + Vf− (5)
The correction speeds Vf + and Vf− are such that the internal angles of the two direction vectors of the movement speed Vf obtained by the equations (4) and (5) are standard movements so that no deviation occurs when the tracking locus is selected by the zooming method. It is determined to be divided into two equal parts by the direction vector of the velocity Vf0. Note that the above zooming control is generally performed in synchronization with the vertical synchronization signal of the video because focus detection is performed using the imaging signal from the imaging device.

  Next, zoom control in the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart of zoom control, which is executed based on a command from a microcomputer (control means). When zooming control is started in step S701, initial setting is performed in step S702. In the initial setting, the RAM and various ports in the microcomputer are initialized. In step S703, the microcomputer detects the state of the operation system of the camera body. The microcomputer receives information on the zoom switch unit operated by the photographer here, and displays on the display zooming operation information such as a zoom lens position for notifying the photographer that the zoom process is being executed.

  In step S704, the microcomputer performs AF processing. That is, the automatic focus adjustment process is performed according to the change of the AF evaluation signal. In step S705, the microcomputer performs zooming processing. That is, the compensator operation (correction operation) for maintaining the focus during zooming is performed. Specifically, the standard driving direction and standard driving speed of the focus lens are calculated in order to substantially trace the locus as shown in FIG.

  Subsequently, in S706, it is selected which of the driving direction and the driving speed of the zoom lens and the focus lens calculated during the AF process and the zoom process (in the processing routines of Step S704 and Step S705) is used. In these processing routines, the zoom lens and focus lens are softly provided so that they do not hit the mechanical end, respectively, between the telephoto end and wide end on control, or between the close end and infinite end on control It is a routine driven by. In step S707, the microcomputer outputs a control signal to the motor driver in accordance with the zoom and focus drive direction information and drive speed information selected in step S706, and controls driving / stopping of the lens. Then, after the processing of step S707 is completed, the flow returns to step S703. Note that the series of processing shown in FIG. 7 is executed in synchronization with the vertical synchronization signal (waiting until the next vertical synchronization signal is input in step S703).

  4 to 6 are flowcharts of control executed by the microcomputer once in one vertical synchronization time, and shows control related to zoom processing executed in step S705 of FIG. Hereinafter, the zoom process in the present embodiment will be described in detail with reference to FIGS. 4 to 7 and FIG. 9. The zoom process shown in FIGS. 4 to 7 is performed based on a command from the microcomputer. In step S400 in FIG. 4, the driving speed Zsp of the zoom motor is set so that a natural zooming operation can be performed according to the operation information of the zoom switch unit. In step S401, the distance (subject distance) from the current zoom lens and focus lens positions to the subject being photographed is specified (estimated). Then, the subject distance information is stored in a memory area such as a RAM as three trajectory parameters (data for obtaining target position information) α, β, and γ. In this embodiment, the process shown in FIG. 5 is performed. In order to simplify the following description, the processing shown in FIG. 5 will be described assuming that the in-focus state is maintained at the current lens position. In step S501 in FIG. 5, the current zoom lens position Zx is calculated in which zoom area v of the data table shown in FIG. To do. The calculation method will be described in detail below with reference to FIG.

  First, in step S601, the zoom area variable v is cleared. In step S602, the zoom lens position Z (v) on the boundary of the zoom area v is calculated according to the following equation (6). The zoom lens position Z (v) corresponds to the zoom lens positions Z0, Z1, Z2,... Shown in FIG.

Z (v) = (tele end zoom lens position−wide end zoom lens position) × v / s + wide end zoom lens position (6)
Subsequently, in step S603, it is determined whether or not the zoom lens position Z (v) obtained in step S602 is equal to the current zoom lens position Zx. If these positions are equal, the zoom lens position Zx is positioned on the boundary of the zoom area v, and 1 is set to the boundary flag in step S607. On the other hand, if these positions are not equal in step S603, it is determined in step S604 whether Zx <Z (v) is satisfied. When the inequality in step S604 is satisfied (Yes), the position Zx is between the position Z (v-1) and the position Z (v), and the boundary flag is set to 0 in step S606. On the other hand, if the inequality in step S604 is not satisfied (No), the zoom area v is incremented in step S605, and the process returns to step S602.

  By repeating the above processing, when exiting the flow of FIG. 6, the current zoom lens position Zx is present in the v = kth zoom area on the data table of FIG. 11, and the position Zx is on the zoom area boundary. It is possible to know whether or not. Since the current zoom area is determined by the process shown in FIG. 6 in step S501 in FIG. 5, the position where the focus lens is located on the data table in FIG. 11 is calculated.

  First, in step S502, the subject distance variable n is cleared. In step S503, it is determined whether the current zoom lens position is on the boundary of the zoom area. If the boundary flag is 0, it is determined not to be on the boundary, and the process proceeds to step S505. In step S505, Z (v) is set in Zk, and Z (v-1) is set in Zk-1. In step S506, four table data A (n, v-1), A (n, v), A (n + 1, v-1), and A (n + 1, v) are read out. In step S507, the positions ax and bx are calculated from the above equations (2) and (3), respectively. On the other hand, if the boundary flag is determined to be 1 in step S503, the process proceeds to step S504. In step S504, the focus position A (n, v) for the zoom lens position (here, v) at the subject distance n and the focus position A (n + 1, v) for the zoom lens position at the subject distance n + 1 are called. Are stored as positions ax and bx, respectively.

  In step S508, it is determined whether or not the current focus lens position px is greater than or equal to the position ax. If the current focus lens position px is greater than or equal to the position ax, it is determined in step S509 whether or not the current focus lens position px is greater than or equal to the position bx. If the current focus lens position px is not greater than or equal to the position bx in step S509, the focus lens position px is between the subject distances n and n + 1, and the trajectory parameters at this time are stored in the memory in steps S513, S514, and S515. Store. In step S513, α = px−ax, β = bx−ax in step S514, and γ = n in step S515.

  No in step S508 is a case where the focus lens position px is a super-infinity position. At this time, α = 0 is set in step S512, and the process proceeds to steps S514 and S515 to store a trajectory parameter at infinity. Yes in step S509 is when the focus lens position px is closer to the camera. At this time, the subject distance n is incremented in step S510, and it is determined in step S511 whether n is on the infinity side from the position m corresponding to the closest distance. When it is on the infinity side from the closest distance position m, the process returns to step S503. No is determined in step S511 when the focus lens position px is an extremely close position. At this time, the process proceeds to steps S512, S514, and S515, and the trajectory parameter for the closest distance is stored.

  As described above, in step S401 in FIG. 4, a trajectory parameter for knowing on which trajectory shown in FIG. 8 the current zoom lens position and focus lens position are stored. Subsequently, in S402, a zoom lens position (position of movement destination from the current position) Zx ′ reached by the zoom lens after one vertical synchronization time (1V) is calculated. Here, if the zoom speed determined in step S400 is Zsp (pps), the zoom lens position Zx 'after one vertical synchronization time is expressed by the following equation (7). pps is a unit representing the rotation speed of the stepping motor, and indicates a step amount (1 step = 1 pulse) to be rotated per second. Further, the sign of Expression (7) is + for the tele direction and-for the wide direction according to the moving direction of the zoom lens.

Zx ′ = Zx ± Zsp / vertical synchronization frequency (7)
Next, in which zoom area v ′ the zoom lens position Zx ′ exists is determined in step S403. In step S403, the same process as in FIG. 6 is performed, and the zoom lens position Zx in FIG. 6 is replaced with Zx ′ and the zoom area v is replaced with v ′, and the same process as in FIG. 6 is performed. Subsequently, in step S404, it is determined whether or not the zoom lens position Zx ′ after one vertical synchronization time exists on the boundary of the zoom area. Here, if the boundary flag = 0, it is not on the boundary and the process proceeds to step S405. In step S405, Zk ← Z (v ′) and Zk−1 ← Z (v′−1) are set. Next, in step S406, four table data A (γ, v′−1), A (γ, v ′), A (γ + 1, v′−1) in which the subject distance γ is specified by the processing of FIG. Read A (γ + 1, v ′). In step S407, the positions ax ′ and bx ′ are calculated from the above equations (2) and (3). On the other hand, when it is determined Yes in step S403, in step S408, the focus position A (γ, v ′) with respect to the zoom area v ′ at the subject distance γ and the focus with respect to the zoom area v ′ at the subject distance γ + 1. Call position A (γ + 1, v ′). And each is memorize | stored as position ax ', bx'.

  Subsequently, in step S409, the focus position (target position) px 'of the focus lens when the zoom lens position reaches Zx' is calculated. Using the equation (1), the follow target position after one vertical synchronization time can be expressed as the following equation (8).

px ′ = (bx′−ax ′) × α / β + ax ′ (8)
Therefore, the difference ΔF between the tracking target position and the current focus lens position is expressed by the following equation (8a).

ΔF = (bx′−ax ′) × α / β + ax′−px (8a)
Next, in step S410, the standard moving speed Vf0 of the focus lens is calculated. The standard moving speed Vf0 is obtained by dividing the position difference ΔF of the focus lens by the moving time of the zoom lens required for moving. Hereinafter, a correction speed calculation method for correcting the movement speed (zigzag operation) of the focus lens shown in FIG. 12B will be described.

  In step S411, various parameters are initialized and “inversion flag” used in the subsequent processing is cleared. In step S412, correction speeds Vf + and Vf− for zigzag operation are calculated from the standard movement speed Vf0 obtained in step S410. Here, the correction amount parameter δ and the correction speeds Vf + and Vf− are calculated as follows. FIG. 13 is an explanatory diagram of a method of calculating the correction speeds Vf + and Vf− according to the correction amount parameter δ. In FIG. 13, the horizontal axis represents the zoom lens position, and the vertical axis represents the focus lens position. Reference numeral 1304 denotes a target locus to be followed.

  When the zoom lens position changes by x, the focus speed at which the focus lens position changes by y (ie, reaches the target position) is a standard movement speed Vf0 indicated by a vector 1403. When the zoom lens position changes by x, the focus speeds at which the focus lens position changes by n or m with reference to the displacement y are correction speeds Vf + and Vf−, respectively. In FIG. 13, reference numeral 1401 denotes a direction vector of a speed (speed obtained by adding a correction speed Vf + in the positive direction to the standard movement speed Vf0) for driving closer to the displacement y. Reference numeral 1402 denotes a direction vector of a speed (speed obtained by adding a correction speed Vf− in the negative direction to the standard moving speed Vf0) for driving toward the infinity side from the displacement y. The values of n and m are determined so that the direction vectors 1401 and 1402 are direction vectors separated from each other by an equal angle δ with respect to the direction vector 1403.

  m and n are calculated | required using the following formula | equation (9a), (9b), (9c), (10) with reference to FIG.

tan θ = y / x (9a)
tan (θ−δ) = (ym) / x (9b)
tan (θ + δ) = (y + n) / x (9c)
tan (θ ± δ) = (tan θ ± tan δ) / {1 ± (−1) × tan θ × tan δ) (10)
Then, from the equations (9a), (9b), (9c), and (10), m and n are obtained as the following equations (11) and (12), respectively.

m = (x2 + y2) / (x / k + y) (11)
n = (x2 + y2) / (x / ky) (12)
(However, tan δ = k)
Here, the correction angle δ is a variable having parameters such as the depth of field and the focal length. Thereby, the increase / decrease period of the AF evaluation signal level that changes according to the driving state of the focus lens can be kept constant with respect to a predetermined focus lens position change amount. For this reason, it is possible to reduce the possibility of missing the in-focus locus that the focus lens should follow during zooming.

  According to the value of the correction angle δ, the value of k is stored as a data table in the memory of the microcomputer, and the calculations of the above formulas (11) and (12) are performed by reading out as necessary. Here, when the zoom lens position changes by x per unit time, the zoom speed Zsp = x, the standard speed Vf0 = y, the correction speed Vf + = n, and Vf− = m. Then, the correction speeds Vf + and Vf− (negative speed) are obtained from the equations (11) and (12).

  In step S413, it is determined whether zooming is in progress according to the information indicating the operation state of the zoom switch unit obtained in step S703 of FIG. If it is during zooming, the process proceeds to step S416. On the other hand, if zooming is not in progress, a value obtained by subtracting an arbitrary constant μ from the current value of the AF evaluation signal level is set to TH1 in step S414. This TH1, as described with reference to FIG. 12A, determines the AF evaluation signal level that becomes the vector switching reference (zigzag operation switching reference) in the correction direction. This TH1 is determined immediately before the start of zooming, and the value TH1 corresponds to the minimum value 1302 in FIG. In step S415, the correction flag is cleared and the process exits (step S705). Here, the correction flag is a flag indicating whether the tracking state is a state in which a positive correction is applied (correction flag = 1) or a negative correction state (correction flag = 0). .

  On the other hand, if it is determined in step S413 that zooming is in progress, it is determined in step S414 whether the zooming direction is from wide to tele. If the direction is tele to wide, Vf + = 0 and Vf− = 0 in step S419, and the process proceeds to step S420. On the other hand, if the direction is wide to tele, it is determined in step S417 whether or not the current AF evaluation signal level is smaller than the value TH1. If the AF evaluation signal level is greater than or equal to the value TH1, the process proceeds to step 420. On the other hand, when the AF evaluation signal level is smaller than the value TH1, the current AF evaluation signal level is lower than the level TH1 (1302) in FIG. Accordingly, in order to switch the correction direction, 1 is set to the inversion flag in step S418.

  In step S420, it is determined whether or not the inversion flag is 1. If the inversion flag = 1, it is determined in step S421 whether the correction flag is 1. On the other hand, if the correction flag is not 1 in step S421, the correction flag is set to 1 (correction state in the positive direction) in step S424. Then, the moving speed of the focus lens is set to Vf = Vf0 + Vf + (where Vf + ≧ 0) according to equation (4). On the other hand, if the correction flag = 1 in step S421, the correction flag = 0 (negative correction state) is set in step S423. Then, the moving speed of the focus lens is set to Vf = Vf0 + Vf− (where Vf− ≦ 0) according to Expression (5).

  If the reverse flag is not 1 in step S420, it is determined in step S422 whether the correction flag = 1. If the correction flag = 1, the process proceeds to step S424. On the other hand, if the correction flag is not 1, the process proceeds to step S423. After the completion of this process (step S705), in step S706 shown in FIG. 7, the driving direction and driving speed of the focus lens and zoom lens are selected according to the operation mode. In the zooming operation, the focus lens drive direction is set to the close direction or the infinity direction depending on whether the focus lens movement speed Vf obtained in step S423 or step S424 is positive or negative. The As described above, the zigzag driving of the focus lens is performed, and the locus to be traced is re-specified.

  Next, the lens control device in Embodiment 1 of the present invention will be described. FIG. 1 is a configuration diagram of a video camera as an imaging device (optical apparatus) equipped with the lens control device of this embodiment. As will be described later, the lens control device of the present embodiment controls the movement of the first lens unit for zooming and the second lens unit for focus adjustment. The present embodiment is intended for an imaging device integrated with a photographing lens, but is not limited to this, and an interchangeable lens (optical apparatus) of an imaging system having an interchangeable lens and a camera body attached to the interchangeable lens. It is also applicable to. In this case, the microcomputer in the lens performs a zooming operation described later in response to a signal transmitted from the camera body side. In addition, the present embodiment is not limited to a video camera, and can be applied to various imaging devices such as a digital still camera.

  In FIG. 1, in order from the object side, 101 is a fixed front lens unit, 102 is a zoom lens unit (first lens unit) that moves in the direction of the optical axis OA (optical axis direction) and performs zooming, and 103 A diaphragm 104 is a fixed lens unit. Reference numeral 105 denotes a focus lens unit (second lens unit) that has a focus adjustment function and a compensator function that corrects image plane movement due to zooming and moves in the optical axis direction. The front lens unit 101, the zoom lens unit 102, the diaphragm 103, the fixed lens unit 104, and the focus lens unit 105 are sequentially arranged from the object side to the image side. The photographing optical system constituted by these lens units is a rear focus optical system constituted by four lens units having positive, negative, positive, and positive optical powers in order from the object side (left side in the figure). In FIG. 1, each lens unit is described as being configured by a single lens. However, in actuality, it may be configured by a single lens or a plurality of lenses. You may be comprised with the lens.

  Reference numeral 106 denotes an image pickup element constituted by a CCD or a CMOS sensor. A light beam from an object that has passed through the imaging optical system forms an image on the image sensor 106. The imaging element 106 photoelectrically converts the formed object image and outputs an imaging signal. The imaging signal is amplified to an optimum level by an amplifier 107 (AGC) and input to the camera signal processing circuit 108. The camera signal processing circuit 108 converts the input imaging signal into a standard television signal, and then outputs it to the amplifier 110. The television signal amplified to the optimum level by the amplifier 110 is output to the magnetic recording / reproducing apparatus 111, and is recorded on a magnetic recording medium such as a magnetic tape by the magnetic recording / reproducing apparatus 111. The recording medium is not limited to a magnetic recording medium, and other types of recording media such as a semiconductor memory and an optical disk may be used.

  The television signal amplified by the amplifier 110 is also sent to the LCD display circuit 114 and displayed on the LCD 115 as a photographed image. The LCD 115 also displays an image that informs the photographer of the shooting mode, shooting state, warning, and the like. Such an image is displayed superimposed on the photographed image by the camera microcomputer 116 (control means) controlling the character generator 113 and mixing the output signal from this with the television signal by the LCD display circuit 114. The

  On the other hand, the image pickup signal input to the camera signal processing circuit 108 can be simultaneously compressed using an internal memory and then recorded on a still image recording medium 112 such as a card medium. The imaging signal input to the camera signal processing circuit 108 is also input to the AF signal processing circuit 109 serving as focus information generating means. The AF evaluation value signal (focus signal) generated by the AF signal processing circuit 109 is read as data by communication with the camera microcomputer 116. Further, the camera microcomputer 116 reads the states of the zoom switch 130 and the AF switch 131 and further detects the state of the photo switch 134.

  When the photo switch 134 is half-pressed, the focusing operation by AF is started and the focus is locked in the focused state. Further, in the fully-pressed (deep-pressed) state, the focus is locked regardless of the in-focus state, the image is taken into a memory (not shown) in the camera signal processing circuit 108, and is stored in the magnetic tape or the still image recording medium 112. Record still images. The camera microcomputer 116 determines whether the moving image shooting mode or the still image shooting mode is set according to the state of the mode switch 133, and the magnetic recording / reproducing apparatus 111 or the still image recording is performed via the camera signal processing circuit 108. The medium 112 is controlled. As a result, a television signal suitable for the recording medium is supplied thereto, and when the mode switch 133 is set to the reproduction mode, the television recorded on the magnetic recording / reproducing apparatus 111 and the still image recording medium 112 is recorded on these. Performs signal reproduction control.

  The computer zoom unit 119 (control means) in the camera microcomputer 116 outputs a predetermined drive signal to the zoom motor driver 122 according to an internal program when the AF switch 131 is off and the zoom switch 130 is operated. To do. The predetermined drive signal is a signal for driving the zoom lens unit 102 in the tele or wide direction corresponding to the direction in which the zoom switch 130 is operated. The zoom motor driver 122 receives this drive signal and drives the zoom lens unit 102 in the tele or wide direction via the zoom motor 121.

  Reference numeral 120 denotes a cam data memory (storage means) that stores data indicating the relationship between the position of the zoom lens unit 102 and the position of the focus lens unit 105, which is created for each predetermined subject distance. The computer zoom unit 119 is a focus motor driver based on lens cam data (representative trajectory data and trajectory parameter data corresponding to a plurality of subject distances as shown in FIG. 10) stored in advance in the cam data memory 120. 126 is controlled. The focus motor driver 126 drives the focus motor 125 and moves the focus lens unit 105 so as to correct the image plane movement caused by zooming. As described above, the computer zoom unit 119 generates information for controlling the movement of the focus lens unit 105 based on the data in the cam data memory 120, and moves the focus lens unit 105 in accordance with the movement of the zoom lens unit 102. Control.

  Further, the AF control unit 117 in the camera microcomputer 116 needs to perform a zooming operation while keeping the focused state when the AF switch 131 is on and the zoom switch 130 is operated. Therefore, the computer zoom unit 119 drives the zoom lens unit 102 and the focus lens unit 105 according to an internal program. This driving is performed not only on the lens cam data stored in the cam data memory 120 but also on the AF evaluation value signal sent from the AF signal processing circuit 109 and information corresponding to the subject distance detected by the subject distance detection circuit 127 (focusing). Based on distance information to the object). In this embodiment, the computer zoom unit 119 changes the movement range of the focus lens unit 105 according to information corresponding to the subject distance and shooting conditions. More specifically, the computer zoom unit 119 determines the correction range of the focus lens unit 105 based on information corresponding to the subject distance, and determines whether to apply the determined correction range based on shooting conditions. To do. This determination method will be described later with reference to FIG.

  Note that an output signal from the subject distance detection circuit 127 (detection circuit) is arithmetically processed by the distance information processing unit 128 in the camera microcomputer 116. The distance information processing unit 128 accumulates output signals for a predetermined time, calculates a distance variation range W ′, and calculates information representing reliability based on the result. Here, the information indicating reliability refers to information obtained along with the calculation of the distance to the subject, details of which will be described later.

The zoom lens unit 102, the focus lens unit 105, and the subject distance detection circuit 127 are parallax. For this reason, the distance measurement frame of the subject distance detection circuit 127 is not always the center on the image sensor 106. Since the position of the distance measurement frame varies depending on the subject distance and the focal distance, the distance measurement frame position S _Dist is calculated based on the above information. The output from the subject distance detection circuit 127 is output to the computer zoom unit 119 as subject distance information, information indicating reliability, a distance variation range, and a distance measurement frame position S _Dist .

  The output from the device motion detection circuit 127A is subjected to arithmetic processing by the device motion information processing unit 128A in the camera microcomputer 116, and is output to the computer zoom unit 119 as motion information. The apparatus motion information processing unit 128A can also use an angular velocity sensor, an acceleration sensor, and a method based on motion vector extraction by image processing. When the angular velocity sensor is used, the apparatus motion information processing unit 128A calculates the angular velocity ω obtained from the angular velocity sensor. The angular velocity ω is output to the computer zoom unit 119 as motion information.

  The output from the subject motion detection circuit 127B is processed by the subject motion information processing unit 128B in the camera microcomputer 116 and output to the computer zoom unit 119 as subject motion information. The subject motion information processing unit 128B can also use a method of motion detection by image processing or motion detection by subject distance change.

  In the case of a motion detection method based on image processing, a motion vector is extracted based on image information acquired by the image sensor 106. The image I acquired at time T and the image I ′ acquired at time T ′ are compared to determine the amount of change, and the motion vector V is calculated from the amount of change. For example, when the camera performs a panning operation or the subject moves, the images I and I ′ change, and the motion vector V increases. Therefore, by detecting the motion vector V, it can be used for panning operation and subject motion determination.

  When the AF switch 131 is on and the zoom switch 130 is not operated, the AF control unit 117 outputs a signal to the focus motor driver 126 so that the AF evaluation value signal from the AF signal processing circuit 109 is maximized. To do. Based on this signal, the focus motor driver 126 drives the focus motor 125 to move the focus lens unit 105. Thereby, an automatic focus adjustment operation is performed.

  Here, the subject distance detection circuit 127 measures the distance to the subject by a triangulation method using an active sensor, and outputs distance information that is the measurement result. As an active sensor in this case, an infrared sensor often used for a compact camera can be used. The distance detection means of the present embodiment is configured to detect distance by the triangulation method, but is not limited to this, and distance detection means other than the triangulation method can be used. . For example, distance detection by a TTL phase difference detection method may be performed. In this case, an element (half prism or half mirror) that divides the light that has passed through the exit pupil of the photographing lens is provided, and the light emitted from this element is guided to at least two line sensors via the sub-mirror and the imaging lens. Then, the correlation between the outputs of these line sensors is taken, the shift direction and shift amount of these outputs are detected, and the distance to the subject is obtained from these detection results.

  With reference to FIG. 14 and FIG. 15, the distance measurement by the triangulation and the phase difference detection method will be described. FIG. 14 is an explanatory diagram of distance measurement by the triangulation method. FIG. 15 is an explanatory diagram of distance measurement by the phase difference detection method. In FIG. 14, 201 is a subject, 202 is an imaging lens for the first optical path, 203 is a line sensor for the first optical path, 204 is an imaging lens for the second optical path, and 205 is for the second optical path. This is a line sensor. Both line sensors 203 and 205 are installed apart by a base line length B. Of the light from the subject 201, the light passing through the first optical path by the imaging lens 202 forms an image on the line sensor 203, and the light passing through the second optical path by the imaging lens 204 is applied to the line sensor 205. Form an image.

  FIG. 15 shows an example of signals read from the line sensors 203 and 205 that have received two subject images formed through the first optical path and the second optical path. Since the two line sensors 203 and 205 are separated by the base line length B, the subject image signal is shifted by the number of pixels X as can be seen from FIG. Thus, the number of pixels X can be calculated by calculating the correlation between the two signals while shifting the pixels and obtaining the pixel shift amount that maximizes the correlation. From the number of pixels X, the base line length B, and the focal length f of the imaging lenses 202 and 204, the distance L to the subject is determined by L = B × f / X based on the principle of triangulation.

  At the same time, the distance information processing unit 128 calculates information representing reliability. In the case of the phase difference detection method, it can be calculated from the correlation value of two signals. When calculating the distance L to the subject, the pixel shift amount that maximizes the correlation amount between the two signals is obtained. The maximum amount of the correlation value, that is, the peak value varies depending on the two input signals. Since the peak of the interphase value may be low for a signal with low contrast, the result of the case where the correlation value peak is high and low is mixed even in the same subject distance result. Therefore, the correlation value is used as information representing the reliability of the subject distance. When the peak of the interphase value is high, it is assumed that the distance detection result has high reliability. In the case of the phase difference detection method, measurement results with low reliability are not used.

  Further, as a distance detection means, a method of detecting the distance to the subject by measuring the propagation speed using an ultrasonic sensor can be employed. In this case, a reflectance, an attenuation factor, or the like is used as information representing reliability. Depending on the nature of the surface of the subject, the reflectance of the ultrasonic wave decreases, making measurement difficult. For this reason, it is possible to grasp the reliability of the detection result by obtaining the reflectance. The same applies to the attenuation rate associated with the subject distance of the ultrasonic signal.

  The distance information from the subject distance detection circuit 127 is sent to the distance information processing unit 128. The distance information processing unit 128 performs the following three processes. First, it calculates which distance on the cam locus in FIG. 8 corresponds to the current positions of the zoom lens unit 102 and the focus lens unit 105. For example, as described in step S401 in FIG. 4, the cam trajectory is calculated based on the current lens unit position by adding the cam trajectories in the γ row and γ + 1 row in the column direction in FIG. 11 to the ratio of α / β. It outputs how many meters the virtual cam trajectory corresponds to the subject distance. The trajectory parameters α, β, γ and subject distance are converted by predetermined correlation table data, and the actual distance of the main subject can be output.

  Second, the actual distance of the subject from the subject distance detection circuit 127 is inversely transformed in the above correlation table to obtain the cam locus in FIG. 8 expressed by the locus parameters α, β, γ. At this time, the inverse conversion processing of the correlation table is performed using data on the tele side as much as possible, with the locus being dispersed, without using the data on the wide side where the cam locus in FIG. 8 is converged. A trajectory parameter with high resolution is obtained.

  Third, an actual distance difference and a difference direction in the first process and the second process described above are calculated. Of these three processes, the second process can identify cam locus data corresponding to the detected distance detected by the subject distance detection circuit 127. On the other hand, the camera microcomputer 116 also performs exposure control. The camera microcomputer 116 refers to the luminance level of the television signal generated by the camera signal processing circuit 108, controls the iris driver 124 so that the luminance level is appropriate for exposure, drives the IG meter 123, and Control the opening. The opening amount of the diaphragm 103 is detected by an iris encoder 129, and feedback control of the diaphragm 103 is performed. In addition, when appropriate exposure control cannot be performed only with the aperture 103, the exposure time of the image sensor 106 is controlled by the timing generator 132 (TG), and it corresponds to a high-speed shutter to a long-time exposure called a so-called slow shutter. Further, when exposure is insufficient such as shooting under low illumination, the gain of the television signal is controlled through the amplifier 107. The photographer can manually operate the shooting mode and camera function switching suitable for the shooting conditions by operating the menu switch unit 135.

  Next, an algorithm during a zooming operation will be described with reference to FIG. In this embodiment, the computer zoom unit 119 in the camera microcomputer 116 executes the processing of the operation flow described below including the above-described operation flows (programs). In this embodiment, the cam locus to be followed is specified (generated) according to the distance information obtained from the subject distance detection circuit 127, and the zooming operation is performed. The operation flow in FIG. 3 is an example of a method for performing a zooming operation while specifying (generating) a zoom tracking curve that is a cam locus to be followed using distance information. This method is effective when the AF evaluation value detection cycle becomes rough, such as ultra-high-speed zoom, and the accuracy sufficient for specifying the zoom tracking curve cannot be increased only by the TV-AF reference signal (AF evaluation value signal). .

  The flow of FIG. 3 corresponds to step S705 of FIG. 7 described above in the present embodiment, and the same processing (step) as in FIG. First, in step S400, the zoom speed during the zoom operation is determined. Subsequently, in step S300, in accordance with the output signal from the subject distance detection circuit 127, it is determined which of the representative trajectories shown in FIG. The trajectory parameters α, β, γ are calculated. At the same time, the trajectory parameters αnow, βnow, and γnow corresponding to the current zoom lens position and focus lens position described in step S401 of FIG. 4 are calculated. Here, αnow, βnow, and γnow are values stored in the memory as αnow, βnow, and γnow, respectively, that are calculated in the processing from step S512 to step S515 in FIG.

  On the other hand, the trajectory parameters based on the distance information obtained by the subject distance detection circuit 127 are calculated as α, β, γ, for example, by the following method. First, in order to obtain the correlation between the output distance information and the representative trajectory (cam trajectory) shown in FIG. The correlation with the trajectory parameter is converted into table data. Thus, the trajectory parameter is calculated using the distance information as an input. For subject distances in which the cam trajectory shape changes, a lookup table representing another correlation is provided, and by having a plurality of these tables, trajectory parameters can be obtained for every subject distance.

  Regarding the focal length, the trajectory parameters on the long focal length side where the resolution of the trajectory parameters α, β, γ is the highest among the discrete cam trajectory information of FIG. 8 held as data in the memory can be output. Configure. As a result, as shown in FIG. 8, even if the current lens position exists at the position where the cam locus converges on the wide side, the point on the tele side where the cam locus diverges according to the distance information. It is possible to extract the trajectory parameters at. Accordingly, when the zoom lens unit 102 is positioned on the wide side, one cam locus that the focus lens unit 105 should follow is specified by performing (interpolation) calculation based on the locus parameter on the tele side. Is possible. Step S300 is executed every predetermined cycle (for example, one vertical synchronization cycle). For this reason, even if the subject distance changes during zooming, the latest cam trajectory to be followed is sequentially updated according to the output of the subject distance detection circuit 127.

  In step S301, the cam locus correction range is determined based on the output of the subject distance detection circuit 127 (that is, α, β, γ calculated in step S300). This correction range corresponds to the correction range in the tracking cam locus correction operation using the TV-AF signal (AF evaluation value). This correction range is, for example, a range sandwiched between a correction range upper limit 1201 and a correction range lower limit 1202 in the cam locus correction range shown in FIG. This correction range specifies a cam locus that should be roughly followed based on distance information and detection accuracy by the subject distance detection circuit 127, and then regenerates a precise following cam locus by a correction operation (zigzag operation) using a TV-AF signal. It is set to limit the re-specific range when specifying.

  For example, when the output from the subject distance detection circuit 127 corresponds to a subject distance 1203 of 5 m, the correction range is limited to a range of ± 50 cm of the subject distance. That is, the correction range upper limit 1201 corresponds to a cam locus corresponding to a subject distance of 4.5 m, and the correction range lower limit 1202 corresponds to a cam locus corresponding to a subject distance of 5.5 m. The correction range may be determined according to the detection accuracy of the subject distance detection circuit 127.

  However, if this limitation on the correction range is applied to all shooting conditions and all camera operating conditions, it may interfere with the limitation of the correction range that does not correspond to the subject distance and the identification of the cam locus to be followed. Therefore, the lens control device of the present embodiment determines whether or not to apply the limitation of the correction range according to the shooting conditions (shooting information and information regarding the operation state of the lens control device). Hereinafter, this determination method will be described with reference to FIG.

  FIG. 16 is a flowchart in which the lens control device determines whether or not the correction range can be applied. The movement range determination unit 128C determines whether or not the correction range can be applied based on information sent to the computer zoom unit 119 and information calculated by the microcomputer 118. First, in step S801, the correction range W is determined based on the detection accuracy. The correction range W is a predetermined range based on information corresponding to the subject distance, for example, a range of ± 50 cm with respect to the subject distance of 5 m.

Subsequently, in steps S802 to S805, whether or not the distance measurement target of the subject distance detection circuit 127 and the distance measurement target of the focus signal obtained from the image sensor 106 are the same, that is, whether or not the same subject is being measured. Determine. First, in step S802, the obtaining the measurement frame position _{S AF} of the focus signal from the AF signal processing circuit 109 (focus signal representing a focus state). In step S803, the distance measurement frame position S _Dist is acquired from the distance information processing unit 128 (subject distance detection circuit 127). In step S804, the coincidence rate E between these two frame positions is calculated based on the acquired distance measurement frame positions S _AF and S _Dist . In step S805, the coincidence rate E is compared with a threshold value Th1. When the coincidence rate E is less than the threshold value Th1, it is determined that the same subject has not been measured, and the correction range W is not applied (step S823). On the other hand, when the coincidence rate E is higher than the threshold value Th1, it is determined that the same subject is being measured, and the process proceeds to step S806.

  As described above, the camera microcomputer 116 has difference detection means (not shown) for detecting a difference between the distance measurement frame position SDist of the subject distance detection circuit 127 and the distance measurement frame position SAF of the focus signal representing the focus state. The computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the difference is equal to or greater than a predetermined threshold (the coincidence rate E is equal to or less than the threshold Th1). At this time, the photographing condition is a difference detected by the difference detecting means.

  Next, in steps S806 and S807, the camera panning operation is determined. First, in step S806, the device motion information processing unit 128A acquires the angular velocity ω detected by the device motion detection circuit 127A (angular velocity detection means). In step S807, the angular velocity ω (| ω |) is compared with the threshold value Th2. The threshold value Th2 is assumed to be a value sufficient to determine the panning operation. When the angular velocity ω is equal to or higher than the threshold Th2, it is determined that the subject is changed by the panning operation, and the correction range W is not applied (step S823). On the other hand, when the angular velocity ω is smaller than the threshold value Th2, it is determined that the subject is not changed rather than the panning operation, and the process proceeds to step S808. As described above, the computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the angular velocity ω is equal to or greater than a predetermined threshold (threshold Th2 or greater). At this time, the photographing condition is an angular velocity ω detected by the apparatus motion detection circuit 127A.

  Next, in steps S808 and S809, it is determined whether or not the subject has been changed. First, in step S808, the subject motion information processing unit 128B acquires the motion vector V detected by the subject motion detection circuit 127B (subject motion detection means). In step S809, the motion vector V (| V |) is compared with a threshold value Th3. Note that the threshold Th3 is set to a value sufficient to detect the movement of the subject. If the motion vector V is equal to or greater than the threshold value Th3 and it is determined that the motion of the subject has been detected, the subject to be focused may have moved and the subject distance may have changed, so the correction range W is not applied. (Step S823). By performing the above processes, it is possible to avoid the determination of the correction range that does not correspond to the distance to the subject that actually wants to be focused. On the other hand, if it is determined that the subject is the same, and it is determined that there is no change in the subject distance due to the panning operation of the lens-integrated camera and the subject moving, the process proceeds to step S810. Thus, the computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the motion vector V is greater than or equal to a predetermined threshold (threshold greater than or equal to threshold Th3). At this time, the photographing condition is a motion vector V detected by the subject motion detection circuit 127B.

  Subsequently, in steps S810 to S814, it is determined whether or not to apply the correction range W based on the output of the subject distance detection circuit 127 and information indicating the reliability. First, in steps S810 and S811, it is determined whether or not the correction range W is applied according to the variation distribution (variation range W ′) of information corresponding to the subject distance in a certain time detected from the subject distance detection circuit 127. In step S810, the distance information processing unit 128 acquires a variation distribution (variation range W ′). If the variation range W ′ is relatively larger than the correction range W determined based on the detection accuracy in step S801, it may be difficult to measure the distance to be measured. For example, when the subject distance detection circuit 127 is a phase difference method or when the luminance signal obtained from the measurement target is a repetition of the same waveform, the measurement result may vary due to erroneous correlation. At this time, the variation range W ′ becomes relatively large. In this case, when the correction range W based on the detection result is applied, the focus lens may exceed the depth of focus and cause image blur due to an error. For this reason, the correction range W is not applied when the variation range W ′ is relatively large. In this embodiment, in step S811, a value obtained by multiplying the correction range W by the coefficient K is compared with the variation range W ′. If this value is greater than or equal to the variation range W ′, the correction range W is not applied (step S823). On the other hand, if this value is smaller than the variation range W ′, the process proceeds to step S812. As described above, when the variation range W ′ is obtained by multiplying the correction range W by a predetermined constant, the computer zoom unit 119 does not apply the correction range W and applies the focus lens unit. The movement of 105 is controlled. At this time, the photographing condition is a variation range W ′ obtained by the distance information processing unit 128.

  The distance information processing unit 128 acquires the reliability of the information corresponding to the subject distance, but the same applies to the information representing the reliability. The restriction based on the result with low reliability may generate a correction range that does not correspond to the distance to the object that is actually desired to be focused. Therefore, first, in step S812, the distance information processing unit 128 acquires the reliability of information corresponding to the subject distance from the subject distance detection circuit 127. In step S813, if this information (reliability) is equal to or less than the predetermined threshold Th4, the correction range W is not applied because the detection result may include an error. As described above, the computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the reliability is equal to or lower than the predetermined threshold value (threshold value Th4 or lower). At this time, the imaging condition is the reliability obtained by the distance information processing unit 128.

  However, depending on the brightness, it may be better to apply the correction range W even if the reliability does not exceed the threshold Th4. In step S814, the reliability is compared with a threshold Th5 that is smaller than the threshold Th4. When the reliability is equal to or less than the threshold Th5, the correction range W is not applied at any brightness (step S823). On the other hand, if the reliability is greater than the threshold value Th5, the process proceeds to step S815 to determine brightness.

  Since the imaging element 106 has a illuminance that can be photographed, it is difficult to photograph at an illuminance lower than this illuminance. Also, the TVAF control method using a video signal is difficult to control. Therefore, when the lowest illuminance detectable by the subject distance detection circuit 127 is lower than the lowest illuminance that can be photographed by the image sensor 106, the detection result of the subject distance detection circuit 127 is trusted and the correction range W is applied. Therefore, in step S815, the brightness Y from the image sensor 106 (CCD) is acquired. In step S816, if the brightness Y is equal to or higher than the reference illuminance (threshold Th6), the correction range W is not applied (step S823). On the other hand, when the brightness Y is smaller than the threshold Th6, it is determined that the illuminance of the image sensor 106 is insufficient. In this case, even if the reliability is low, the restriction using the distance detection result is performed. As described above, when it is determined that the subject distance is reliable to some extent, the process proceeds to step S817.

  As described above, the image sensor 106 is illuminance detection means that detects an optical image formed by an optical system including the zoom lens unit 102 and the focus lens unit 105. The computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the brightness Y (illuminance) is equal to or greater than a predetermined threshold (threshold Th6 or greater). At this time, the photographing condition is brightness Y (illuminance) detected by the image sensor 106.

  Next, in steps S817 to S821, a determination is made according to the camera settings at the time of shooting. First, in step S817, the zoom lens speed Vz is acquired. In step S818, the shutter speed Vs is acquired. When the zoom lens is moving at a low speed, a sufficient time is required for the movement from wide to telephoto, and the number of acquisitions of the AF evaluation value signal inevitably increases. For this reason, it is possible to specify the locus to be followed without applying the correction range W. On the other hand, when the zoom lens is high-speed, it is difficult to specify the locus because the number of AF evaluation value signal acquisitions is small. For this reason, applying the correction range W using the distance detection result is more effective for specifying the trajectory. Thereby, an unnecessary correction range W in the case of low speed can be avoided. The same applies to the shutter speed Vs. When the shutter speed Vs is low, the number of acquisitions of the AF evaluation value signal during zooming is reduced, so that it is difficult to specify the locus. For this reason, applying the correction range W using the distance detection result is more effective for specifying the trajectory.

  Therefore, in step S819, determination is performed using the zoom lens speed Vz obtained from the information of the zoom switch 130 in step S817 and the shutter speed Vs calculated by the camera microcomputer 116 in step S818. Specifically, in step S819, the zoom lens speed Vz is compared with a predetermined threshold Th7, and the shutter speed Vs is compared with a predetermined threshold Th8. In this way, unnecessary correction range setting is avoided by performing application determination of the correction range W according to the zoom lens speed Vz and the shutter speed Vs. The threshold Th7 is set to a zoom lens speed that can be sufficiently focused by TVAF. As the threshold Th8, a sample period during normal shooting (60 Hz in the case of a general video camera) is set. In step S819, if the zoom lens speed Vz is equal to or lower than the threshold Th7 and the shutter speed Vs is equal to or higher than the threshold Th8, the correction range W is not applied (step S823). On the other hand, if the zoom lens speed Vz is larger than the threshold value Th7 or the shutter speed Vs is smaller than the threshold value Th8, the process proceeds to step S820.

  As described above, the lens control device includes speed detection means for detecting the speed of the zoom lens unit 102. The computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the speed is equal to or higher than a predetermined threshold (threshold Th7 or lower). At this time, the photographing condition is the speed of the zoom lens unit 102. The lens control device also includes a shutter (exposure time control means) that controls the exposure time of the optical image formed by the optical system including the zoom lens unit 102 and the focus lens unit 105 with respect to the image sensor 106. The computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W when the exposure time is equal to or less than a predetermined threshold (the shutter speed Vs is equal to or greater than the threshold Th8).

  Next, in steps S820 and S821, it is determined whether or not the correction range W can be applied according to the depth of focus determined from the light amount adjustment result of the diaphragm 103 (light amount adjusting unit). When the aperture 103 is small and open, the depth of focus becomes large, so that it is not necessary to make the correction range smaller than the depth of focus. On the other hand, when the depth of focus is small, the correction range W using the distance detection result is applied. Therefore, first, in step S820, the focal depth Wf is acquired from the value of the diaphragm 103 (aperture value). In step S821, the variation range W 'is compared with the focal depth Wf. When the variation range W ′ is larger than the focal depth Wf, the process proceeds to step S822, and the correction range W is applied. On the other hand, if the variation range W ′ is equal to or less than the focal depth Wf, the process proceeds to step S823, and the correction range W is not applied. As described above, when the depth of focus Wf exceeds the variation range W ′, the computer zoom unit 119 controls the movement of the focus lens unit 105 without applying the correction range W.

  As described above, by determining whether or not the correction range is applied based on the shooting information and information on the operation state of the lens apparatus, an unnecessary correction range that does not correspond to the distance to the target object that is actually desired to be focused is obtained. Application can be avoided. Moreover, it is not necessary to increase the detection resolution (detection accuracy) of the subject distance detection circuit 127 by applying the correction range. As a result, an inexpensive and small imaging device can be provided. Further, in this embodiment, the number of times of switching the direction of the zigzag operation when respecifying the tracking cam locus using the TV-AF signal is increased, and the frequency of continuing correction in the same correction direction is reduced. For this reason, it is possible to prevent the occurrence of blurring that repeats jaspin and slight image blur periodically according to the movement of the zigzag operation, which may have occurred when shooting a subject with a high frequency. . Furthermore, it is possible to reduce the occurrence of image blur when the following cam trajectory is mistaken or image blur when recovering to the correct cam trajectory.

  As an actual operation, the tracking cam locus correction operation (zigzag driving) using the TV-AF signal is performed only within a range between the correction range upper limit 1201 and the correction range lower limit 1202. When exceeding this range, the drive direction of the focus lens unit 105 is reversed so as to return to the correction range. As a result, re-specification of the cam locus outside the range between the correction range upper limit 1201 and the correction range lower limit 1202 is prohibited.

  In the present embodiment, a correction range is set in accordance with the detection resolution of the subject distance detection circuit 127, and the specification of the precise tracking cam locus by the TV-AF signal is permitted only within the range, whereby the TV-AF signal Reduce malfunction and image blur induced by the combined use. That is, the identification results of the two types of cam locus identification methods, the cam locus identification method based on the output from the subject distance detection circuit 127, and the cam locus identification method based on the in-focus state detection signal of the TV-AF signal match. Only when it is necessary to re-specify the tracking cam trajectory. As a result, it is possible to realize an extremely accurate cam trajectory tracking method that combines only the advantages of the specific methods.

  In particular, when specifying the tracking locus by the TV-AF signal, it is necessary to set the driving speed (correction speed) of the focus lens for the zigzag operation to a speed that can cover from the infinite cam locus to the closest cam locus. is there. On the other hand, in this embodiment, by limiting the correction range of the cam trajectory, for example, even if the correction speed of the focus lens is the same, the movement range becomes narrow, so the number of zigzag operations per unit time is increased to the first number. It becomes possible. Therefore, it is possible to improve the cam locus specifying accuracy by the TV-AF signal even in the case of high speed zoom.

  On the other hand, when the number of zigzag operations is not increased to the first number, the set value of the correction speed can be lowered accordingly. Therefore, it is possible to reduce the occurrence of blur that periodically repeats justin and slight image blur in the correction operation when shooting a high-frequency subject (details will be described in the second embodiment). Therefore, even with the same technique, it is possible to provide a zooming system having a high degree of freedom for realizing zoom performance by a zoom speed priority, a visual priority, and an optimal control method according to the product specifications of the provided imaging apparatus.

  Returning to the description of FIG. Hereinafter, lens control when the limited range is applied will be described. In step S302, it is determined whether or not the “AF correction flag” is set. If so, the process proceeds to step S303. In step S303, it is determined whether or not the trajectory parameters αAF, βAF, and γAF are included in the correction range shown in FIG. 2 (the range between the correction range upper limit 1201 and the correction range lower limit 1202). The trajectory parameters αAF, βAF, and γAF are updated each time it is detected that the AF evaluation value reaches the maximum value 1301 described with reference to FIG. If the trajectory parameters αAF, βAF, and γAF are within the correction range in step S303, the trajectory parameters αAF, βAF, and γAF are set to α, β, and γ, respectively, in step S304. Then, control is performed so that the focus lens unit 105 traces the cam locus re-specified by the correction operation.

  On the other hand, if the trajectory parameters αAF, βAF, and γAF are out of the correction range in step S303, or if the “AF correction flag” is cleared in step S302, the trajectory parameters α, β that have already been determined in step S300. , Hold γ. The trajectory parameters α, β, and γ are specified based on distance information from the subject distance detection circuit 127. Then, the focus lens unit 105 is controlled so as to trace the cam locus specified by the locus parameters α, β, and γ.

  Here, the “AF correction flag” is a flag indicating whether or not the following cam locus is re-specified by a TV-AF signal described later. When only identification based on distance information by the subject distance detection circuit 127 has been made (the cam locus that has not been re-specified or is being re-specified is outside the correction range of FIG. 2 and is likely to be erroneously specified) ), The “AF correction flag” is cleared in step S305. From the next time onward, until the cam trajectory is re-specified by the correction operation, the trajectory trace control is performed by giving priority to the specifying result based on the distance information.

  Thereafter, steps S402 to S410 are performed as in FIG. Thereafter, the present process is terminated, and the process proceeds to step S706 in FIG. When the zooming operation is being performed, the movement is performed in the sign direction of the focus speed (the close direction is positive and the infinity direction is negative) at the focus speed determined in step S410, and the compensator operation (correction operation) is performed. In step S411, various parameters are initialized. Here, the “inversion flag” used in the subsequent processing is cleared. In step S412, correction speeds Vf + and Vf− for zigzag operation are calculated from the standard focus movement speed Vf0 obtained in step S410. Here, the correction amount parameter δ and the correction speeds Vf + and Vf− are calculated using the equations (9) to (12) as described with reference to FIG.

  In step S413, whether or not zooming is in progress is determined according to the information indicating the operation state of the zoom switch 130 obtained in step S703 of FIG. If the determination result is Yes, the process proceeds to step S416. If the determination result is No, the “AF correction flag” is cleared in step S309, and the zooming operation in the tele direction from the next wide is prepared. In step S414, a value obtained by subtracting an arbitrary constant μ from the current value of the AF evaluation signal level is set to TH1 (minimum value 1302 in FIG. 12A). Then, an AF evaluation signal level that serves as a reference for switching vectors in the correction direction (switching reference for zigzag operation) is determined.

  Next, in step S415, the “correction flag” is cleared and the process is exited. Here, as described above, the “correction flag” is a state in which the tracking state of the cam locus is corrected in the positive direction (correction flag = 1) or a state in which the correction in the negative direction is applied (correction flag = 0). ).

  If it is determined in step S413 that zooming is being performed, it is determined in step S414 whether the zooming direction is from wide to tele. If the determination result is No, as in step S309, the “AF correction flag” is cleared, and preparation for a zooming operation in the tele direction from the next wide is performed (step S308). In step S419, Vf + = 0 and Vf− = 0 are set, and the process proceeds to step S420, where zigzag driving is not substantially performed.

  If the determination result in step S413 is Yes, it is determined in step S306 whether or not the focus lens position with respect to the current zoom lens position exceeds the correction range upper limit 1201 shown in FIG. If the correction range upper limit 1201 is exceeded, the process advances to step S423 to return the focus lens position to the correction range. In step S423, a negative correction speed Vf− is added to the calculated focus speed (standard movement speed) Vf0 (corrected toward infinity). As a result, the focus lens unit 105 is forcibly returned to the correction range lower limit 1202 rather than the correction range upper limit 1201.

  On the other hand, if the correction range upper limit 1201 is not exceeded in step S306, it is determined in step S307 whether the focus lens position with respect to the current zoom lens position exceeds the correction range lower limit 1202 in FIG. If the correction range lower limit 1202 is exceeded, the process advances to step S424 to return the focus lens position to the correction range. In step S424, a positive correction speed Vf + is added to the calculated focus speed (standard movement speed) Vf0 (corrected in the closest direction). As a result, the focus lens unit 105 is forcibly returned to the correction range upper limit 1201 rather than the correction range lower limit 1202. As described above, the movement range of the focus lens unit 105 is limited within the correction range. As a result, the cam trajectory re-specified by the zigzag operation is also limited within this correction range.

  If the focus lens position does not exceed the correction range in steps S306 and S307, it is determined in step S417 whether or not the current AF evaluation signal level is lower than TH1 in order to execute the zigzag operation. If the determination result is Yes, the current AF evaluation signal level is lower than the level of TH1 (1302) in FIG. 12A. Therefore, in order to switch the correction direction, an inversion flag is set in step S418.

  In step S420, it is determined whether or not the inversion flag = 1. If the determination result is Yes, the process proceeds to step S421 to determine whether or not the correction flag is 1. On the other hand, if the determination result is No in step S421, the process proceeds to step S424, and 1 (correction state in the positive direction) is set in the correction flag. Further, according to the above equation (4), the focus speed Vf is set to Vf = Vf0 + Vf + (where Vf + ≧ 0). On the other hand, if the determination result is Yes in step S421, the process proceeds to step S423, and 0 (correction state in the negative direction) is set in the correction flag. Further, the focus speed Vf is set to Vf = Vf0 + Vf− (where Vf− ≦ 0) by the above equation (5).

  When it is determined No in step S420, it is determined whether or not the correction flag is 1 in step S422. If the determination result is Yes, the process proceeds to step S424. On the other hand, if this determination is No, the process proceeds to step S423.

  After the completion of this process, in step S706 shown in FIG. 7, the driving direction and driving speed of the focus lens unit 105 and the zoom lens unit 102 are selected according to the operation mode. In the case of the zooming operation, here, the driving direction of the focus lens unit 105 is set to the closest direction or the infinite direction depending on whether the focus speed Vf obtained in step S423 or step S424 is positive or negative. In this way, the cam locus to be traced is re-specified while performing the zigzag driving of the focus lens unit 105.

  While performing zigzag driving, in steps S417 to S424, it is detected that the AF evaluation signal in the TV-AF has reached the maximum value 1301 shown in FIG. If it is determined No in step S417, it is determined in step S310 whether the maximum value 1301 has been detected. When the peak level is detected, in step S311, “AF correction flag = 1” and the current value of the trajectory parameter are set as αAF ← αnow, βAF ← βnow, γAF ← γnow as re-specific trajectory parameters by TV-AF. . Then, when the conditions in the next step S302 and step S303 are satisfied (when the determination results of both steps are both Yes), the specific cam trajectory is updated in step S304. The trajectory parameter updated and respecified in step S304 is specified based on the distance information by changing the correction range in step S301, stopping the zooming operation, or reversing the zooming direction due to the change in the detected distance information. Updated to the cam trajectory.

  If the condition at the next step S302 or S303 is not satisfied, an optimum cam during zooming operation is repeated while repeating the update of αAF, βAF, and γAF at step S311 each time a new peak level is detected (step S310). The trajectory is updated as needed. If it is not detected in step S310 that the AF evaluation value level has reached the peak level, the process directly proceeds to step S420. Then, the focus lens unit 105 is driven while correcting in the previously determined correction direction without switching the correction direction by the zigzag operation.

  With the above processing, the TV-AF signal is used by limiting the specific range (correction range) when specifying the cam locus to be followed using the TV-AF signal based on the distance information to the subject. The accuracy of specifying the cam trajectory can be greatly improved. Accordingly, erroneous determination of an erroneous cam track as a track to be traced is reduced. In addition, it is possible to reduce the occurrence of malfunction problems such as wrong timing for switching the zigzag operation. Therefore, occurrence of image blur can be reduced.

  In particular, by identifying a cam trajectory serving as a reference based on distance information and correcting (respecifying) the cam trajectory using a TV-AF signal while limiting the correction range, the tracking cam trajectory based on the TV-AF signal is determined. Correction accuracy can be improved. For this reason, the detection accuracy of the subject distance detection circuit 127 can be roughened to some extent, and a small and inexpensive type of the subject distance detection circuit 127 can be selected.

  Next, a lens control apparatus in Embodiment 2 of the present invention will be described. In the first embodiment, the case where the correction speed in the correction operation of the focus lens unit 105 based on the TV-AF signal is calculated as in FIG. 4 has been described. For this reason, in Example 1, the movement distance (movement range) of the focus lens unit 105 decreases due to the limitation of the correction range, and as a result, the frequency of the zigzag operation within the correction range increases. Therefore, the system has a high ability to specify the tracking cam locus even at high speed zoom or the like.

  On the other hand, in the present embodiment, by setting the correction speed slower than that in the case of the first embodiment, it is possible to reduce periodic image blur such as an image that is blurred or in focus due to the zigzag operation. . For example, when the correction speed is set to ½ that of the first embodiment, the driving direction inversion timing of the focus lens unit 105 shown in FIG. 12B (timing at which the AF evaluation value signal becomes equal to or less than the minimum value 1302). The amount of overshoot at is reduced. For this reason, it is possible to reduce a periodic change in which the image is visually blurred or in focus.

  In order to reduce the correction speed to 1/2, for example, a process for reducing the correction speeds Vf + and Vf− calculated in step S412 in FIG. 3 to 1/2 may be added. Moreover, what is necessary is just to calculate as the following formula | equation (4 ') and (5'), respectively, by providing a coefficient in Formula (4), (5).

Focus speed Vf = Vf0 + Vf + / 2 (where Vf + ≧ 0) (4 ′)
Focus speed Vf = Vf0 + Vf− / 2 (Vf− ≦ 0) (5 ′)
In each of the above embodiments, a case has been described in which the range for specifying (generating) the cam trajectory (α, β, γ) to be followed based on the distance information to the subject is limited. It is not what is done. Each embodiment can be applied to a case where the range is limited based on distance information to the subject when the target position of the focus lens is calculated (generated).

  According to each of the embodiments described above, information (trajectory information, etc.) generated to control the driving of the second lens unit according to the detected distance to the in-focus object, shooting information, and information on the operating state of the lens apparatus. ) To determine whether to limit the range. As a result, it is possible to avoid a movement range restriction that does not correspond to the distance to the object that is actually desired to be focused, and an unnecessary movement range restriction. Therefore, it is possible to provide a lens control device that reduces the occurrence of image blur during zooming.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

102 Zoom lens unit 105 Focus lens unit 119 Computer zoom unit 120 Cam data memory 127 Subject distance detection circuit

Claims (11)

A lens control device for controlling movement of a first lens unit for zooming and a second lens unit for focus adjustment,
Storage means for storing data indicating the relationship between the position of the first lens unit and the position of the second lens unit, created for each predetermined subject distance;
Control means for generating information for controlling movement of the second lens unit based on the data, and for controlling movement of the second lens unit accompanying movement of the first lens unit;
Detecting means for detecting information corresponding to the subject distance,
The lens control apparatus according to claim 1, wherein the control unit changes a moving range of the second lens unit in accordance with the information corresponding to the subject distance and a photographing condition. The control means includes
Determining a correction range of the second lens unit based on the information corresponding to the subject distance;
The lens control device according to claim 1, wherein it is determined whether to apply the correction range based on the photographing condition. A difference detection means for detecting a difference between the position of the distance measurement frame of the detection means and the position of the distance measurement frame of the focus signal representing the focus state;
The photographing condition is the difference detected by the difference detecting means,
The lens control device according to claim 2, wherein the control unit controls movement of the second lens unit without applying the correction range when the difference is equal to or greater than a predetermined threshold. Further comprising angular velocity detection means for detecting the angular velocity of the lens control device;
The photographing condition is the angular velocity detected by the angular velocity detecting means,
4. The lens control device according to claim 2, wherein the control unit controls the movement of the second lens unit so that the correction range is not applied when the angular velocity is equal to or greater than a predetermined threshold. 5. . It further includes subject motion detection means for detecting a subject motion vector,
The shooting condition is the motion vector detected by the subject motion detection means,
5. The control unit according to claim 2, wherein the control unit controls movement of the second lens unit without applying the correction range when the motion vector is equal to or greater than a predetermined threshold value. 6. The lens control device described in 1. A distance information processing means for acquiring a variation range of the information corresponding to the subject distance at a predetermined time by the detection means;
The photographing condition is the variation range obtained by the distance information processing means,
The control means controls the movement of the second lens unit without applying the correction range when the value obtained by multiplying the correction range by a predetermined constant exceeds the variation range. The lens control device according to claim 2, wherein the lens control device is a lens control device. Further comprising distance information processing means for acquiring reliability of the information corresponding to the subject distance by the detection means;
The photographing condition is the reliability obtained by the distance information processing means,
7. The control unit according to claim 2, wherein, when the reliability is equal to or less than a predetermined threshold value, the control unit controls movement of the second lens unit without applying the correction range. The lens control device described in 1. Illuminance detection means for detecting the illuminance of an optical image formed by an optical system including the first lens unit and the second lens unit;
The photographing condition is the illuminance detected by the illuminance detection means,
8. The control unit according to claim 2, wherein when the illuminance is equal to or greater than a predetermined threshold, the control unit controls movement of the second lens unit without applying the correction range. 9. The lens control device described. A speed detecting means for detecting the speed of the first lens unit;
The photographing condition is the speed detected by the speed detecting means,
9. The control unit according to claim 2, wherein the control unit controls the movement of the second lens unit without applying the correction range when the speed is equal to or lower than a predetermined threshold value. 10. The lens control device described. An exposure time control means for controlling an exposure time for an image sensor of an optical image formed by an optical system including the first lens unit and the second lens unit;
The photographing condition is the exposure time controlled by the exposure time control means,
10. The control unit according to claim 2, wherein when the exposure time is equal to or less than a predetermined threshold, the control unit controls the movement of the second lens unit without applying the correction range. The lens control device described in 1. A light amount adjusting means for adjusting the light amount obtained through the first lens unit;
Distance information processing means for acquiring a variation range of the information corresponding to the subject distance in a fixed time by the detection means;
The photographing condition is a depth of focus obtained by the light amount adjusting means,
The control unit according to any one of claims 2 to 10, wherein when the depth of focus exceeds the variation range, the control unit controls the movement of the second lens unit without applying the correction range. The lens control device according to Item.