JP3261111B2 - Zoom lens, zoom lens system and camera system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a zoom lens used for a television camera or the like.

[0002]

2. Description of the Related Art In a zoom lens used for a television camera or the like, a zoom demand can be operated to drive and control a zoom unit to obtain a desired angle of view.

In addition, a desired subject can be focused by driving and controlling a focus unit by operating a focus demand.

FIG. 4 is a flowchart showing the operation of a zoom lens system that controls the position of the lens. In this zoom lens, data is input from a zoom demand or a focus demand (steps 103 and 104), and a focus position command and a zoom position command indicating a target driving state of the focus unit and the zoom unit are calculated based on the input data (steps 103 and 104). Steps 106 and 107). Then, a motor as a drive source is driven in accordance with the difference between these position commands and the current positions of the focus unit and the zoom unit, and a desired angle of view and focus state are obtained (steps 109 and 110).

[0005]

However, when the focus unit is driven, the angle of view changes to the angle of view. For this reason,
Depending on the driving state of the focus unit (lens position, etc.)
In some cases, even if the zoom unit is driven to the drive end, a desired angle of view cannot be obtained.

Further, even if the driving states of the zoom units are equal,
The angle of view varies depending on the driving state of the focus unit.
In particular, in a zoom region having a large depth of field such as a wide end,
Even if the driving state of the focus unit changes due to the focus operation, the image is less likely to be blurred, so that a phenomenon in which the angle of view changes significantly appears.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a zoom lens that can always obtain a desired angle of view without being affected by the driving state of the focus unit.

[0008]

In order to achieve the above object, the present invention has a control means for controlling an optical system including a zoom unit and a focus unit to change an angle of view to a target angle of view by driving the optical system. In the zoom lens, when the target angle of view exceeds a range of the angle of view obtained by driving the zoom unit, the control unit focuses on the zoom lens to obtain the target angle of view.
The drive of the unit is controlled .

Specifically, for example, when the target angle of view is
When the depth of field of the optical system is deeper than a predetermined value (depth of field for focusing from the shortest distance to infinity) or the optical field When the hyperfocal distance of the system is a short distance that is twice or less the closest distance , the focus unit is driven to obtain the target angle of view.
What is necessary is just to perform dynamic control .

That is, for example, in a case where blurring of an image is unlikely to occur even when the focus unit is driven, by driving the focus unit which is originally focused on a certain object distance and adjusting the angle of view (zooming), An angle of view exceeding an angle of view range obtained only by driving the zoom unit can be obtained without causing image blur.
As a result, a constant maximum angle of view and the like can be obtained regardless of the driving state (focus position) of the focus unit.

[0011]

(First Embodiment) FIG. 1 shows the configuration of a zoom lens according to a first embodiment of the present invention. The zoom lens 101 includes a zoom demand (operation device) 1 and a focus demand 2 to form a zoom lens system, and is communicably connected to the camera 103 to form a camera system.

Reference numeral 5 denotes a CPU (control means).
Zoom demand 1 and focus demand 2 are connected to U5. From the zoom demand 1, zoom speed data as zoom control information corresponding to the operation speed is input. Further, from the focus demand 2, focus position data as focus control information corresponding to the operation amount is input.

One output of the CPU 5 is connected via an amplifier 6 to a motor 8 for driving a lens constituting the zoom section Z. The zoom unit Z is provided with a position detector 9 that outputs a voltage corresponding to the absolute position of the lens. This position detector 9 is connected to the CPU 5.

Another output of the CPU 5 is a motor 1 for driving a lens constituting a focus unit F via an amplifier 13.
5 is connected. The focus unit F is provided with a position detector 16 that outputs a voltage corresponding to the absolute position of the lens. This position detector 16 is connected to the CPU 5.

The other output of the CPU 5 is connected to the television camera 103 via the D / A converter 20.
Accordingly, follow signals indicating various states of the zoom lens 101, such as zoom follow data indicating the lens position of the zoom unit Z and iris follow data indicating the state of the aperture (not shown), are communicated to the camera 103.

Further, the CPU 5 includes a zoom unit Z.
A non-volatile memory 18 that stores data for obtaining a relationship between a position of a lens constituting the focus unit F (hereinafter, referred to as a zoom position and a focus position) and an angle of view is connected. Here, the data stored in the memory 18 will be briefly described.

First, the variable range of the normalized zoom position data is divided into a plurality of parts, and the zoom position data and the angle-of-view data at each division point are stored in the memory 18.

Further, the variable range of the normalized focus position data is divided into a plurality of ranges, and a coefficient of a quadratic function that approximates the relationship between the focus position data and the object distance in each divided point area is also stored.

Further, the lens driving range from the wide-angle end point to the telephoto end point of the zoom unit Z is divided into an arbitrary number n, and the lens drive range from the infinity end point to the close end point of the focus unit F is increased. The range is similarly divided into an arbitrary number m, and the output data of the pulse measurement counters in the position detectors 9 and 16 are calculated in advance. Further, the angles of view at the i-th division point of the zoom and the j-th division point of the focus are obtained by optical calculation, and similarly, i of the zoom, j + 1-th division of the focus, and i +
1. The angle of view at the j-th division point of focus, i + 1 of zoom, and j + 1-th division point of focus are obtained by optical calculation, and the zoom position, focus position, and image position in the area surrounded by these four points are obtained. The relationship between the angles is approximated by a plane equation including three of the four points. By applying the equation of the approximate plane, the angle of view can be expressed by a function (1) using the zoom position and the focus position as variables.

Ω = Cz × Pz + Cf × Pf + D (1) where ω represents the size of the angle of view, Cz is a coefficient for the zoom position on the approximate plane, Pz is a zoom position, and Cf is a coefficient for the focus position on the approximate plane. , Pf are focus positions, and D is a constant term on an approximate plane. Data obtained by mapping the values of the coefficients Cz, Cf, and D obtained in this way are stored in the memory 18.

The flow chart of FIG. 2 shows a series of operations from immediately after the power is turned on to the motor output in the zoom lens.

Immediately after the power is turned on, the CPU 5 initializes the inside of the CPU 5 and proceeds to step 1 to initialize the zoom unit Z and the focus unit F.

Next, in step 2, communication with the zoom demand 1 and the focus demand 2 is initialized. Here, the initialization operation is completed, and the operation shifts to the normal operation of controlling the zoom unit Z and the focus unit F according to the outputs from the zoom demand 1 and the focus demand 1.

In step 3, normalized zoom speed data Zspeed is input from zoom demand 1, and in step 4, normalized focus position data Fdata is input from focus demand 2. Then, in step 5, the zoom speed data Zspeed is integrated using equation (2), and the normalized zoom position data Zda
Compute ta.

Zdata = Zbuf + K × Zspeed (2) Zdata: normalized zoom position data Zbuf: zoom position data at the time of previous sampling K: integration constant Zspeed: zoom speed data Next, at step 6, zoom position data Zdata But,
It is determined where the variable range of the zoom position data is included in a plurality of divided regions, and the zoom position data zdata [n−1], z of the division points located at both ends of the region are determined.
data [n] and the corresponding angle-of-view data ω [n−
1], ω [n] are input from the memory 18.

Further, in step 7, Zda is added to the equation (3).
ta and zdata [n-1], zdata [n],
The angle of view command (target angle of view) ωpos is calculated by substituting ω [n−1] and ω [n].

Ωpos = ω [n−1] × 10 ^L (3) where L = log (ω [n] / ω [n−1]) × (Zdata-zdata [n−1]) / (zdata
[n] -zdata [n-1]) ωpos: angle-of-view command ω [n]: angle-of-view data corresponding to the n-th division point Zdata: normalized zoom position data zdata [n]: n-th division Normalized zoom position data corresponding to the point Next, in step 8, the angle-of-view command ω obtained in step 7
Substituting pos into equation (4), the focal length FocusLen
gth is calculated.

Focus Length = y ′ / (2 × TAN ⁻¹ (ωpos / 2)) (4) ωpos: angle-of-view command y ′: image size Next, in step 9, the focal length data Foc is calculated by equation (5).
The hyperfocal distance H is calculated by substituting usLength.
Here, the hyperfocal distance is a distance from infinity to half of the hyperfocal distance within the depth of field when focus is adjusted to this distance, and focus adjustment is not required in this range. is there. It is known that the depth of field increases as the object distance (the distance to the subject) increases.

H = FoculLength ² / (δ × Fno) (5) H: hyperfocal length FoculLength: focal length δ: allowable confusion circle Fno: F number O. D data (closest distance data) Lmod is input from the memory 18 and step 1
1 and hyperfocal distances H and M. O. Compare with the D data Lmod. When the hyperfocal distance H is M.P. O. If the distance is longer than twice the value of the D data Lmod, the M.D.
O. Since the focus state of the subject near D changes, the mode shifts to a normal operation mode in which the drive of the focus unit F is controlled according to the focus position command.

In the normal operation mode, in step 12, the focus position data Fdata is converted into a focus position command Focus using Expression (6).

Focus = Far + Fdata / NOM × (Near−Far) (6) Focus: Focus position command Far: Infinite end focus position command Near: Nearest end focus position command Fdata: Normalized focus position data NOM: Normalized data Further, in step 13, the zoom position data Zdata
And the coefficients Cz, Cf, and D of the approximate first-order plane equation corresponding to the area including the focus position data Fdata are input from the memory 18, and in step 14, the zoom position command Zoom is calculated using equation (7). Jump to 20.

Zoom = − (Cf × Focus + ωpos + D) / Cz (7) Zoom: zoom position command Focus: focus position command ωpos: angle-of-view command Cz, Cf, D: coefficient of approximate primary plane equation , The hyperfocal distance H is M.P. O.
If the distance is shorter than twice the value of the D data Lmod, all the subjects from the closest distance to infinity are brought into focus.

In step 15, it is determined where the normalized focus position data Fdata is included in the area obtained by dividing the variable range of the focus position data into a plurality of parts, and the divided points located at both ends of the area are determined. Focus position data Fdata [n-1], Fdata [n] and corresponding maximum angle-of-view data ωlim [n-1], ωli
m [n] is input from the memory 18. Then, the focus position data Fdata and Fdata
[N-1], Fdata [n], ωlim [n-1],
ωlim [n] is substituted for the maximum angle of view data ωlimit
Is calculated.

Ωlimit = ωlim [n−1] + (ωlim [n] −ωlim [n−1]) × (Fdata−Fdata [n−1]) / (Fdata [n] −Fdata [n−1]) .. (8) ωlimit: maximum angle-of-view data ωlim [n]: angle-of-view data corresponding to the n-th division point Fdata: normalized focus position data Fdata [n]: normalization corresponding to the n-th division point Next, in step 16, the maximum angle-of-view data ωlimit is compared with the angle-of-view instruction ωpos. When the angle of view command ωpos is equal to or less than the maximum angle of view data ωlimit, the angle of view can be adjusted only by driving the zoom unit Z up to the angle of view corresponding to the angle of view command ωpos. The process jumps to step 12 in order to shift to the normal mode for driving and controlling F.

On the other hand, at step 16, the angle of view command ωpos
Is larger than the maximum angle-of-view data ωlimit, the driving of the zoom unit Z alone cannot adjust the angle of view to the angle of view corresponding to the angle-of-view command ωpos. However, when the hyperfocal distance H is M.P. O. Since the distance is shorter than twice the value of the D data Lmod, all the subjects from the closest distance to infinity are in focus, so that focusing is unnecessary. Therefore, if the angle of view command ωpos is larger than the maximum angle of view data ωlimit in step 16, the process proceeds to steps 17 to 19, in which the focus unit F is driven based on the angle of view command ωpos to adjust the angle of view.

Specifically, first, in step 17, the zoom position command Zoom is set to the wide end position data.

In step 18, it is determined where the angle of view command ωpos is included in an area obtained by dividing the variable range of the wide-angle angle of view by driving the focus unit F into a plurality of parts. Angle-of-view data ωw of the located division point
ide [n−1], ωwide [n], and the focus position command Pf [n−
1] and Pf [n] are input from the memory 18.

Further, in step 19, the angle-of-view command ωpos and the angle-of-view data ωwide [n-1], ωw are expressed by equation (9).
ide [n] and the focus position command Pf [n−
1], Pf [n] and focus position command Foc
Calculate us' and jump to step 20.

Focus ′ = Pf [n−1] + (Pf [n] −Pf [n−1]) × (ωpos−ωwide [n−1]) / (ωwide [n] −ωwide [n−1] ) (9) Focus': Focus position command Pf [n]: Focus position command corresponding to n-th division point ωpos: View angle command ωwide [n]: View-angle data corresponding to n-th division point In step 19, a zoom position command for preventing a change in the angle of view due to driving of the focus unit F is calculated, and in step 19, an angle of view (angle of view command) exceeding the maximum angle of view obtained by driving the zoom unit Z is obtained. Is calculated in step 20, the output of the counter in the position detector 9 is set in the counter buffer Zfol.
The output of the counter in the position detector 16 is set in the counter buffer Ffol.

In step 21, the position control calculation of the zoom section Z is performed using the zoom position command Zoom and the counter buffer Zfol, and the focus position command Focu is obtained.
focus section F using the counter buffer Ffol
Of the position control.

Subsequently, in step 22, the zoom position control calculation result in step 21 is output to the amplifier 6 and the focus position control calculation result is output to the amplifier 13, respectively, and the motors 8 and 15 are driven. Thereafter, steps 3 to 22 are repeatedly executed until the power is turned off.

As described above, according to the present embodiment, when the angle of view corresponding to the angle of view command exceeds the maximum angle of view obtained by driving the zoom unit Z, the hyperfocal distance is twice the closest distance. When the distance is shorter, the angle of view is adjusted using the driving of the focus unit F, so that the angle of view corresponding to the angle of view command can be obtained without causing image blurring. Therefore, for example, as shown in FIG. 3, even when the focused object distance is 0.6 m or 10 m (when the wide-angle angle of view obtained only by zoom driving is smaller than the wide-angle angle of view at infinity ∞). By performing zooming using the drive of the focus unit F within a range that satisfies the optical condition that the hyperfocal distance is shorter than twice the closest distance, zoom drive is performed only at infinity. Thus, the same wide-end angle of view as the wide-angle angle of view obtained can be obtained. That is, the wide-angle angle of view can be kept constant regardless of the focus position.

In addition, when the hyperfocal distance is shorter than twice the shortest distance, the focus position command is calculated based on the angle-of-view data set by the control data from the zoom demand 1 (step in FIG. 2). 17 to 19), even if the focus control data is changed by operating the focus demand 2, the focus position command does not change. Therefore,
Even if the focus operation is performed on the wide side, the focus position data from the focus demand 2 is substantially ignored, and the focus unit F is not driven. Therefore, it is possible to prevent a change in the angle of view due to focusing at the wide end.

In the present embodiment, the case has been described in which the maximum angle of view obtained by the zoom drive at infinity of focus is obtained at all the focus distances. Further, it may be used to enlarge the maximum angle of view obtained by this zoom lens by driving the focus unit for zooming.

In this embodiment, the zoom demand 1
The case where the angle of view command is calculated based on the zoom control information (zoom speed data) input from
The present invention can be applied to, for example, a case where angle-of-view command data is input from a control unit of a camera arranged in a control room of a television camera.

[0046]

As described above, according to the present invention, when the target angle of view exceeds the range of the angle of view obtained by driving the zoom unit , the focus unit is driven to obtain the target angle of view.
Since the control is performed, for example, when blurring of an image is unlikely to occur even when the focus unit is driven, the focus unit that is originally focused on a certain object distance is driven to adjust the angle of view (zooming). Accordingly, an angle of view exceeding the range of the angle of view obtained only by driving the zoom unit can be obtained without causing image blurring.
Therefore, a constant maximum angle of view or the like can be obtained regardless of the driving state of the focus unit (that is, the object distance). Further, it is possible to prevent the angle of view from fluctuating even when a focus operation is performed in the target angle of view setting state.

Further, since the present invention can be implemented without making optical and mechanical changes to the conventional lens, it is possible to avoid an increase in the size and cost of the zoom lens.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a zoom lens according to an embodiment of the present invention.

FIG. 2 is an operation flowchart of the zoom lens.

FIG. 3 is an operation conceptual diagram of the zoom lens.

FIG. 4 is an operation flowchart of a conventional zoom lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Zoom demand 2 Focus demand 3 Nonvolatile memory 4 Angle-of-view correction mode changeover switch 5 CPU 6,13 Amplifier 8,15 Motor 9,16 Position detector 20 D / A converter 21 A / D converter 101 Zoom lens 103 Camera Z Zoom part F Focus part

Claims (9)

(57) [Claims] 1. A zoom lens having control means for controlling an angle of view to a target angle of view by driving an optical system including a zoom unit and a focus unit, wherein the control unit determines that the target angle of view is the zoom unit. when it exceeds the angle range obtained by the drive of the target image
A zoom lens , wherein the focus unit is drive-controlled to obtain an angle . 2. The control unit drives the zoom unit to a driving end when the target angle of view exceeds a range of an angle of view obtained by driving the zoom unit, and controls the eye.
The zoom lens according to claim 1 , wherein the focus unit is drive-controlled to obtain a target angle of view. 3. The control unit, when the target angle of view is larger than a maximum angle of view obtained by driving the zoom unit, drives the zoom unit to a drive end on the maximum angle of view side, and controls the target image. Drive the focus section to get a corner
3. The zoom lens according to claim 2, wherein the zoom lens is dynamically controlled . 4. An optical system including a zoom unit and a focus unit.
Control to change the angle of view to the target angle of view by driving the system
In the zoom lens having a control means, the control means, the target angle is above the angle range obtained by driving of the zoom portion and the depth of field of the optical system is deep to or greater than the predetermined value Sometimes to get the target angle of view
A zoom lens that drives and controls the focus unit . 5. The zoom lens according to claim 4, wherein the predetermined value is a depth of field value for focusing from a closest distance to an infinity distance. 6. An optical system including a zoom unit and a focus unit.
Control to change the angle of view to the target angle of view by driving the system
In the zoom lens having a control unit, the control unit may be configured so that the target angle of view exceeds a range of an angle of view obtained by driving the zoom unit, and that a hyperfocal distance of the optical system is twice a minimum distance. when the following short distance, the eye
A zoom lens , wherein the focus unit is drive-controlled to obtain a target angle of view. 7. A claim zoom lens according to any one of 6, this is connected to a zoom lens, to enter the information for driving and controlling the zoom unit to said control means in response to the user operation A zoom lens system comprising an operation device. 8. A claim zoom lens according to any one of 6, this is connected to a zoom lens, to enter the information for driving and controlling the focus unit to said control means in response to the user operation A zoom lens system comprising an operation device. 9. A camera system comprising a zoom lens system according to claim 7 or 8, said zoom lens is configured to have a camera mounted.