JP3513167B2 - Lens control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to an inner focus type
And a lens control device for the lens system. [0002] 2. Description of the Related Art FIG.
FIG. 2 is a configuration diagram of a focus type lens system. In FIG.
As shown, the inner focus type lens system
Reference numeral 1 denotes a light sequentially from the left subject side to the right side in FIG.
A first fixed lens 2 disposed along the axis, parallel to the optical axis
A variable power lens 3 for moving to a variable power, a diaphragm 4, and a second
Focus adjustment is performed by moving the fixed lens 5 in parallel with the optical axis.
Along with this, correction is performed when the focal plane moves due to zooming.
Focus competition with so-called competition function
Lens 6. And this lens system
The image of the optical subject 1 is placed on the imaging surface 7a of the imaging device 7.
An image is formed, photoelectrically converted, and output as a video signal. [0003] Such an inner focus type lens
In the system 1, the focus competition lens
6 has both a competition function and a focus adjustment function
Therefore, even if the focal lengths are the same, the focus is on the imaging surface 7a.
The position of the focus compensating lens 6 depends on the subject distance.
Is different. That is, the subject distance at each focal length
Is changed, the focus for focusing on the imaging surface 7a is changed.
Plot the position of the focus competition lens 6 continuously
Is as shown in FIG. Therefore, zooming without blur
To zoom in during zooming, depending on the subject distance.
Select the focusing lens locus shown in FIG. 8 and select the focusing
Move the focus competition lens 6 along the lens path.
Need to be done. [0005] A front focus type lens system
Now, an independent competition lens is provided for the zoom lens.
The zoom lens and the compensating lens are mechanical
Are connected by a simple cam ring. Therefore, for example, for a cam ring
A knob for manual zoom is provided to manually adjust the focal length.
If you try to change it, no matter how fast you move the knob,
The cam ring rotates following this, and the zoom lens
The lens moves along the cam groove of the cam ring,
If the lens is in focus, the above operation will
It does not cause quenching. On the other hand, an inner focus type lens system
In system 1, zooming without blur is performed as described above.
In order to achieve this, the focus controller follows the locus shown in FIG.
It is necessary to move the lens 6. For this reason, FIG.
Information of multiple focusing lenses corresponding to such subject distances
To some form (even the locus itself, the lens position is a variable
Function can be stored in the microcomputer for lens control.
The focus compensating lens 6 and the variable power lens 3
Select the focus lens trajectory by position and select this selected
Trajectory tracking for zooming while tracing the focus lens trajectory
A slave system is generally employed. The trajectory tracking method
Details will be described later. At this time, the focus compensating lens 6
In order to make the focus control accurate and eliminate blur completely,
Position of the lens 3 and the focus compensating lens 6
It needs to be detected to a degree that is accurate. In particular, it is clear from FIG.
As shown, the variable power lens 3 is at a constant speed or a speed close to it.
When moving in degrees, the focal length changes
Of the focusing lens trajectory to be followed by the focusing lens 6
Is changing. This is the focus competition lens 6
Show that the speed and direction of movement change every moment.
In other words, the actuation for the focus competition lens 6
Accurate speed from 1Hz to several 100Hz
You will have to respond. In order to satisfy such demands, focus
As an actuator for the compensating lens 6, a stepper
It is becoming common to use a motor. Step
The ping motor is output from a microcomputer for lens control, etc.
Rotation in full synchronization with the stepping pulse
High speed responsiveness and stop because the running angle per hit is constant
This is because accuracy and position accuracy can be obtained. In addition,
When using a ping motor, the step angle relative to the step pulse
Since the degree is constant, the increment pulse is
Can be used as a point type position encoder.
Another advantage is that there is no need to add
You. Next, an inner focus type lens system is described.
In order to perform the zooming operation while maintaining the focus in the system 1
A conventional example of the trajectory tracking method will be described with reference to FIG.
You. [0010] In FIG. 9, the vertical axis is the focus comple- er.
The position of the lens 6 and the horizontal axis indicate the position of the variable power lens 3.
You. Also, z0, z1, z2,..., Z11 are positions of the variable power lens 3.
A0, a1, a2,... A11, b0, b
1, b2, ... b11 correspond to two different subject distances
The focus controller follows the movement of the zoom lens 3.
Show the typical focus lens trajectory that Perens 6 should follow
I have. The in-focus lens locus information is
Stored in the control microcomputer. [0011] As shown in FIG.
Blur has a typical focus corresponding to discrete subject distance
Since only the lens trajectory is stored, it is not stored.
If the subject distance is too long,
If you follow it as it is, you will change the magnification while keeping the focus.
Can no longer do so. So, the unremembered subject
In the case of body distance, based on the stored focus lens trajectory
Focus lens corresponding to the subject distance that is not stored
The trajectory is calculated. P0, p1, p2,... P11 in FIG.
Is the calculated focusing lens locus. This p0, p1,
The focus lens locus such as p2,. [0012] (Equation 1)   p (n + 1) = b (n + 1) -a (n + 1) ×             p (n) -a (n) / b (n) -a (n) + a (n + 1) Is calculated by According to equation 1, for example, in FIG.
When the focus compensation lens 6 is at the position of p0, p0 is
A ratio for internally dividing the line segment “b0−a0” is determined, and the ratio is determined according to the internal ratio.
Therefore, a point that internally divides "b1-a1" is defined as p1. this
The position difference between the points p1 and p0 and the zoom lens 3 is moved from z0 to z1
From the time it takes to move
The moving speed of the focusing lens 6 is determined. By the way, when zooming at high speed or the like,
When the movement speed of the lens 3 is fast,
The moving speed of the focus competition lens 6 becomes faster near the telephoto end.
Of the motor for moving the focus competition lens
May exceed speed. In this way, exceeding the step-out limit speed
If the camera is in focus, the camera will not be able to maintain
I will. Therefore, the moving speed of the zoom lens 3 is set at the telephoto end.
Focus Compensation Lens by decelerating near
Method to prevent the moving speed of Step 6 from exceeding the step-out limit speed
Has been realized. This method generally uses a variable power lens.
DC motors are used as moving actuators.
I have. [0016] However, with a DC motor,
In order to decelerate the moving speed of the variable power lens 3, DC
The motor needs to be servo-controlled and the control
The problem is that the road scale becomes large and the control becomes complicated.
There was a title. Further, the moving speed of the variable power lens 3 is controlled to be reduced.
If this is the case, the deceleration control
Stops deceleration when the moving speed of Step 6 becomes below the step-out limit speed.
As a result, the moving speed of the focus comp
As the step-out limit speed has been exceeded, decelerate again
The zoom speed is repeatedly accelerated and decelerated,
It will give a sense of harmony. Also, deceleration itself is uncomfortable for the photographer.
It is desirable that the deceleration time be as short as possible,
In addition, the deceleration speed can be adjusted smoothly while maintaining focus.
Is desired. The present invention has been made under such circumstances.
The purpose is to change the magnification by simple configuration and control.
The focus movement speed can be controlled smoothly to always maintain focus.
It is to do. [0020] Means for Solving the Problems To achieve the above object,
Therefore, the present invention provides a first lens for performing a zooming operation,
To correct the movement of the focal plane during the movement of the first lens
Moving the second lens and the first lens in parallel with the optical axis.
Moving the zoom motor and the second lens with respect to the optical axis.
A focus motor for moving to a row, and the first lens
The focus position of the second lens with respect to the discrete position of
Focusing position storage pre-stored according to discrete subject distance
Means, said first lensZooAnd the current position of the second lens
Based on the position and the information stored in the focus position storage means.
The second lens with respect to the movement position of the first lens.
Focus position calculating means for calculating a focus position of the camera;
Lens movementCalculated based on speedThe second record
Movement speed of the lensIf it is determined to exceed
The moving speed of the first lensDecelerationSo that the
Control the motorAlong with the subject distance
Change the specified valueControl means. [0021] [0022] [0023] [0024] [0025] Next, an embodiment of the present invention will be described with reference to the drawings.
I will tell. FIG. 1 shows a lens control according to an embodiment of the present invention.
Block diagram showing an outline of a video camera equipped with a device
It is. In FIG. 1, reference numeral 10 denotes an inner focus.
Type lens system, similar to the conventional example described above,
In the figure, the optical axis sequentially from the left subject side to the right side
Fixed lens 11 disposed along the optical axis, parallel to the optical axis
The variable power lens 12, the aperture 13, and the second fixed
When the focus adjustment is performed by moving the constant lens 14 in parallel with the optical axis,
In both cases, correction is performed when the focal plane moves due to zooming.
Focus Competition with Competition Function
15. The light from the lens system 10
The image of the biological subject is captured by an image sensor 1 composed of a CCD or the like.
6, an image is formed on the imaging surface 16a, and is photoelectrically converted into a video signal.
Is output as This video signal (electric signal)
Amplified by amplifier (or impedance converter) 17
The output is changed by an AGC (automatic gain control) circuit 18.
The width is kept constant, and the filter 19
Only extracted. Then, the signal processing circuit 20
AF (auto focus)
S) For processing, find the intensity of high frequency components, etc.
And outputs the result to the lens control microcomputer 21.
You. Variable power lens 12, focus competition lens
15 is moved by lens moving means 22 and 23, respectively.
Is done. The lens moving means 22 and 23 are
Data 22a, 23a and drivers 22b, 23b.
(Hereinafter referred to as stepping pink for moving the zoom lens 12)
Zoom motor, focus competition lens 15)
A stepping motor for movement is called a focus motor.
U). These zoom motor 22a and focus motor 2
The output shafts 22c and 23c directly connected to 3a, respectively,
The racks 22d and 23d are engaged with each other,
2d and 23d are respectively a variable power lens 12 and a focus
It is fixed to the competition lens 15. Then, the output from the lens control microcomputer 21 is performed.
Movement command signal (direction signal s1, s2, speed signal s
(3, s4), the driving energy from the drivers 22b, 23b
Luggy is zoom motor 22a, focus motor 23a
And the output shafts 22c and 23c rotate.
This allows the variable power lens to be integrated with the racks 22d and 23d.
12. The focus compensating lens 15 is parallel to the optical axis.
(In the direction of arrows A and B). Variable magnification lens 12, focus competition lens
The positions of 15 are lens position detecting means 24 and 25, respectively.
Is detected by The lens position detecting means 24, 25
Photo sensors 24a, 25a and light shielding plates 24b, 25b
And the photo sensors 24a and 25a emit light.
And a light receiving unit (not shown), and a light shielding plate 24b,
25b is a variable power lens 12 and a focus competition, respectively.
It is fixed to the lens 15. Then, the variable power lens 12, the focus control
When the lens 15 moves parallel to the optical axis,
The light shielding plates 24b and 25b move, and the photo sensors 24a and
When the optical path between the light-emitting unit and the light-receiving unit 25a is blocked,
The output signal of the optical unit goes to a low level and is not blocked.
When it is not, it becomes a high level. Therefore, the position where the output signal of the light receiving section changes
With the zoom lens 12 and the focus competition
Detecting whether the lens 15 is at the reference position
Can be. Then, the microcomputer 21 for lens control
Depends on the reference position, lens moving speed, lens moving direction, etc.
Thus, the position of each lens can be recognized. The aperture 13 is adjusted so as to maintain an appropriate exposure amount.
Driven by the driver 26. That is, the aperture control cycle
The path 27 detects the level of the output signal of the AGC circuit 18
And this level is not a certain level (appropriate exposure)
Generates an aperture control signal to maintain a constant level.
You. The aperture control signal is amplified by the second amplifier 28.
Output to the driver 26, and
The aperture 13 is driven so as to obtain a neutral exposure amount. The aperture state of the aperture 13 is transmitted to the encoder 29.
Is detected by the third amplifier 30.
Amplified by the signal conversion circuit 31
After the lens 21 is converted into a readable signal, the lens control
Output to the microcomputer 21 for use. The lens control microcomputer 21 includes a variable power lens.
The lens 12 in the wide direction and the tele direction, respectively.
Wide switch 32, tele switch 33, focus
Move the Scompe lens 15 toward infinity and close
Infinite switch 34 for moving, close switch 3
5. The AF switch 36 for setting the AF mode is connected
ing. These switches and the lens control microcomputer 21
Is connected to a power supply via a pull-up resistor 37.
38 are connected. Note that the wide switch 32 and the
The switch 33 controls the lens control via a voltage control circuit 36.
The voltage control circuit 36 is connected to the
Is pressed by the wide switch 32 or the tele switch 33.
When pressure is applied, microcomputer for lens control according to the pressing force
The voltage to be output to 21 is changed. And lens control
Microcomputer 21 according to the voltage from voltage control circuit 36.
Zoom lens 12 at what speed of variable speed zoom
Decide what to move. For example, if the voltage is lower than 2V
Low speed zoom if not, medium speed zoom if 2V or more and less than 4V
Zoom zoom lens with high-speed zoom when 4V or more and less than 5V
Is moved. The lens control microcomputer 21 has the configuration shown in FIG.
Focusing lens as shown in Fig.
The lens locus table T is preset. Sand
The focusing lens trajectory table T in FIG.
Focus Compensation Lens 1 corresponding to 2 discrete positions
5 is a table in which the in-focus positions are recorded for each subject distance.
, N (0, 1,..., K,.
m) indicates a discrete subject distance, and is in the row direction (vertical direction in the figure).
Z) (0, 1,..., K,... L) are discrete scaling lenses.
The position of the intersection of a column and a row is discrete
Corresponding to the position of the variable magnification lens 12 and the subject distance
The focus position of the focus compensating lens 15 is recorded.
You. Note that the subject distance increases in the right direction in the figure.
"0" indicates infinity and "m" is the closest
1 cm is shown. The position of the zoom lens is
The angle of view increases as one moves in the direction.
Indicates the end, and “l” indicates the wide end. Sand
That is, the data group of each column is
Yes, it is. And the focus competition lens 15
An in-focus position, for example, A0k is a variable magnification lens at a subject distance of "0".
Compensation lens when the position of the lens 12 is "k"
15 shows the in-focus position. The lens control microcomputer 21 performs zooming.
When performing control, follow the focusing lens locus
The cas compensator lens 15 follows the movement of the variable power lens 12.
By doing so, zooming while maintaining focus is performed
So that At this time, the lens control microcomputer 21
When the moving speed of the focus compensating lens 15 is equal to or less than a predetermined value.
When it is up, it responds to the inclination of the focus lens locus.
Then, the moving speed of the variable power lens 12 is reduced. Next, the lens control operation will be described with reference to FIGS.
Explanation will be made based on the chart. 3 and 4.
Low zooms when the AF mode is off.
FIG. 3 to 5
Is a subroutine, and this flow is executed
Automatic focus adjustment according to focus voltage (sharpness of video signal) before
Contrast method (climbing method) that controls nodes
AF mode processing and the like are performed. First, the lens control microcomputer 21
ON / OFF of switch 32 and tele switch 33
To determine whether zooming is in progress.
(Step S1). As a result, the wide switch 32 and the
None of the switch 33 is turned on,
If not, reset the deceleration flag (step
S2), driving the focus motor 23a (step S2)
S21). On the other hand, the wide switch 32 and the tele switch
If any of 33 are turned on and zooming,
Of the zooming lens position zk of the
Remembered zoom lens position (this position is called the boundary position)
It is determined whether or not it is above (step S3). The result
As a result, if the current zoom lens position zk is on the boundary position,
Tele switch 33 is turned on, and from wide to tele
To determine whether zooming is in progress (step
S4). As a result, zooming from wide to tele direction
If it is medium, one telephoto side from the current zoom lens position zk
Between the boundary position zk + 1 and the current zoom lens position zk
The absolute value of the minute (position difference) is stored as a variable △ z (step
Step S5). On the other hand, zooming from tele to wide direction
If it is medium, it is one wider than the current zoom lens position zk
Between the side boundary position zk-1 and the current zoom lens position zk
The absolute value of the difference (position difference) is stored as a variable △ z
Step S6). Processing in step S5 or step S6
Is completed, the process proceeds to step S7, in which the variable power lens 12
The variable magnification lens position zk + 1 or zk-1 at the movement destination
Focus position of the focus compensating lens 15 corresponding to
The position to be moved following for focus) y
Calculated based on Next, referring to the deceleration flag,
To determine if the system speed is already decelerating
(Step S8). As a result, the deceleration flag is reset
If the zoom speed has not been reduced,
The deceleration flag is reset (step S9). And
The wide switch 32 supplied from the voltage control circuit 36,
Alternatively, the voltage level corresponding to the pressing force of the teleswitch 33 is
By judging, it is possible to select one of the standard
Determine whether the photographer specifies the zoom speed (step
Step S10). As a result, low voltage zoom and low voltage level
Is indicated, the zoom speed Vz is set to a low speed.
The speed value α is stored (step S11). Also, the voltage level
When the bell is medium and medium speed zoom is
The medium speed value β is stored as the
Step S12). Voltage level is high and high speed zoom is instructed
Is high, a high speed value γ is written as the zoom speed Vz.
Remember (step S13). Thus, the zoom speed Vz is determined.
Then, the zoom follows the movement of the variable power lens 12 during zooming.
The speed at which the focus compensating lens 15 moves (hereinafter referred to as “the speed”).
Calculate Vf (referred to as focus speed) (Step S1)
4). This focus speed Vf depends on the focus
Assuming that the current position of the lens 15 is f, it is given by the following equation. [0044] Vf = (y−f) × Vz /） z Next, the calculated focus speed Vf is changed to the focus mode.
Maximum focus speed considering the step-out limit speed of the motor 23a
It is determined whether the temperature is equal to or higher than Vfmax (step S
15). As a result, the focus speed Vf is
If it is smaller than the high speed Vfmax, step S1 described later
Go to 9. On the other hand, the focus speed Vf is the highest focus
If the speed is higher than Vfmax, set the deceleration flag.
(Step S16), the focus speed Vf
The maximum scum speed Vfmax is stored (step S1).
7). Then, the zoom speed (in this case, the deceleration speed) Vz
Is calculated (step S18). This calculation formula is
It is given by the following equation obtained by modifying equation 2. [0045] Vz = ３z × Vf / (y−f) Next, the variable power lens 12 is moved at the speed of the zoom speed Vz.
The zoom motor 22a is driven to rotate (step S1).
9) Set the focus compensating lens 15 to the focus speed V
drive the focus motor 23a to move the
Then (step S20), the process returns to the main flow.
At this time, as is apparent from the above description, the variable power lens 1
2 is the focus speed V calculated in step S14
f is the maximum focus speed Vfmax in step S15
If it is determined that this is the case, in step S18
The focus speed Vf is moved at the calculated deceleration speed.
It is determined that the maximum focus speed is lower than Vfmax
In the case, any one of steps S11, S12, and S13 is described.
It is moved at the remembered standard zoom speed. Also, focus
The competition lens 15 calculates the focus speed Vf
Is determined to be equal to or higher than the maximum focus speed Vfmax.
If it is determined that the focus is
Moved at the maximum speed Vfmax, and the focus maximum speed V
If it is determined to be smaller than fmax, the calculated
It is moved at the focus speed Vf. Here, the processing is performed in steps S19 and S20.
Drive of the zoom motor 22a and the focus motor 23a
The operation method will be described. Zoom motor 22a, focus motor 2
Drivers 22b and 23b for driving 3a are
(H) / low output from the microcomputer 21
(L) Direction signals S1 and S2 and rotation of clock waveform
Controlled by speed signals S3 and S4 as wave number signals
You. The direction signal S1 to the zoom motor 22a is
Switch 32 or tele switch 33 is turned on.
H / L is determined depending on whether the operation is performed. Also, focus
The direction signal to the motor 23a is the focus speed V
H / L is determined depending on whether f is positive or negative.
You. The drivers 22b and 23b output the direction signal S
1, the phases of the four motor excitation phases are rotated forward in accordance with S2,
Or set to reverse rotation and respond to the speed signals S3 and S4
The applied voltage (or current) of the four-phase motor excitation phase
Output while rotating the motor,
Conversion frequency, i.e., zoom lens 12, focus competition
The moving direction and moving speed of the lens 15 are controlled. That is, the variable power lens 12, the focus
Actuator for moving the impeller lens 15 (zoom
Motor 22a and focus motor 23a)
Uses a stepping motor instead of a DC motor
Therefore, when controlling the deceleration of the variable power lens 12 as described above,
It is not necessary to servo control the driver 22b (dry
The circuit size of the lens 23b is also reduced to allow for lens control.
The program capacity of the microcomputer 21 can be reduced,
Control is also simplified. In step S8, the vehicle has already been decelerated.
If it is determined that the zoom
It is determined whether or not the mobile phone is running (step S21). So
As a result, if zooming from wide to tele
Proceeding to step S16, zooming from the telephoto to the wide direction
If it is during the tuning, the process proceeds to step S9. This is Zoomin
Once in a deceleration state during a run, continue deceleration as it is
Means that. This reduces the speed of the zoom
The zoom speed is limited to near the edge, and the zoom speed is
A rattling zoom that is alternately switched to the quasi-zoom speed
This is to prohibit the user from becoming a problem. By performing the above lens control,
The zoom speed Vz and the focus speed Vf are as shown in FIG.
Change like so. FIG. 5A shows the position of the variable power lens on the horizontal axis.
FIG. 5 is a diagram in which the vertical axis represents the focus speed Vf.
(B) shows the zoom lens position on the horizontal axis and zoom on the vertical axis.
It is the figure which took speed Vz. In other words, the sum for each subject distance shown in FIG.
As can be estimated from the locus of the focal lens, the zoom speed Vz
How the focus speed Vf changes with respect to the subject distance
The zoom speed Vz varies depending on the speed, as shown in FIG.
As described above, in the case of a constant medium speed β, the focus speed Vf
Is, for example, shown in FIG.
To change. P shown in FIG. 5B indicates the start of zoom deceleration.
Position. That is, from the zoom deceleration start position P,
On the side, the focus speed Vf is
Exceeding the maximum speed Vfmax considering the step-out limit speed of a
The focus cannot be maintained. So, zoom down
On the tele side from the speed start position P, as shown in FIG.
In FIG. 5, the focus speed Vf is set to the maximum speed Vfmax.
The zoom speed Vz is reduced as shown in FIG. this
As is clear from the above description, the deceleration speed
Calculated in such a way as to keep the focus in consideration of the inclination of the trajectory
And slowly change, so the zoom speed is smoothly reduced
It is possible to do. Also, the focus speed Vf is
When exceeding the high speed Vfmax, the focus speed Vf
The maximum speed Vfmax without being lower than the maximum speed Vfmax
x, the deceleration period of the zoom speed Vz is shortened.
can do. [Application Modification] In the above-described embodiment, the
The maximum speed Vfmax of the scum speed Vf is fixed at a constant value.
The subject distance n and the selected standard zoom
In FIG. 5, depending on the program speed Vz (low speed, medium speed, high speed)
Zoom deceleration start position P is different. Because of this,
Zooming section with constant speed and zooming section with deceleration
Time between zooming at normal speed
The ratio of the zooming time in the fast state to the subject distance
n or the selected standard zoom speed Vz (low speed, medium
Speed, high speed), which makes the photographer feel uncomfortable
I will give it. Therefore, as shown in FIG.
Depending on the body distance n, the maximum speed Vfmax is changed,
As shown in FIG. 6B, the magnitude of the standard zoom speed Vz
(Α, β, γ), the maximum speed Vfmax is changed.
It is good to let it. The maximum speed Vfmax is appropriately changed.
When zooming at a constant zoom speed
A feeling of zooming that seems to be suddenly faster near
Conversion rate) can be made uniform. [0058] As described in detail above, the present invention
Simplifies the moving speed of the zoom lens with simple configuration and control.
, It is possible to always maintain focus. That is, the actuator for moving the zoom lens
Since a stepping motor is used as the
Simple control method without increasing the scale of the control circuit
Zoom lens while maintaining focus by focusing lens
Movement speed of the vehicle can be reduced. Also, zoom lens
The moving speed of the lens according to the inclination of the locus of the focusing lens.
Maintains smoothness and focus by performing at the rate of change in speed
Zooming is possible. Further, conditions for reducing the moving speed of the variable power lens
Is set in various modes, for example, focusing
Do not exceed the step-out limit of the actuator for the competition lens.
The deceleration time of the moving speed of the zoom lens
Or the speed of change of the image magnification, which usually increases rapidly near the telephoto end.
The degree can be made uniform.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an outline of a video camera provided with a lens control device according to one embodiment of the present invention. FIG. 2 is a diagram showing data contents of a focusing lens trajectory table. FIG. 3 is a flowchart illustrating a lens control operation. FIG. 4 is a flowchart continued from FIG. 3; FIG. 5 is a diagram illustrating an example of control of a focus speed and a zoom speed in the lens control illustrated in the flowcharts of FIGS. 3 and 4; FIG. 6 is a diagram illustrating an example in which a deceleration condition of a zoom speed is changed. FIG. 7 is a diagram showing an inner focus type lens system. FIG. 8 is a diagram showing the relationship between the position of a variable power lens for maintaining focus and the position of a focusing lens for each subject distance. FIG. 9 is a diagram for explaining a focusing lens trajectory tracking method. [Description of Signs] 12 Variable Lens 15 Focus Compensation Lens 21 Lens Control Microcomputer 22 Lens Moving Means 23 Lens Moving Means 22a Zoom Motor (Stepping Motor) 23a Focus Motor (Stepping Motor) 22b Driver 23b Driver 32 Wide Switch 33 Tele Switch 34 infinity switch 35 close switch 36 voltage control circuit T focusing lens trajectory table S1, S2 direction signal S3, S4 speed signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/232 G02B 7/08 G02B 7/28

Claims (1)

(57) [Claim 1] A first lens for performing a zooming operation,
A second lens for correcting the movement of the focal plane when the first lens moves, a zoom motor for moving the first lens in parallel with the optical axis, and a second lens for moving the second lens to the optical axis. A focus motor for moving in parallel, a focus position storage means for storing in advance a focus position of the second lens with respect to a discrete position of the first lens in accordance with a discrete subject distance; if for calculating the focus position of the second lens with respect to the movement position of said first lens on the basis of the current position and the information stored in the in-focus position memory means lens Contact and second lens A focus position calculating means;
The zoom so slows the moving speed of <br/> the first lens when the moving speed of the lens the second lens which is calculated based on the moving speed of is determined to exceed the predetermined value Control the motor and adjust the front
A lens control device comprising: control means for changing the predetermined value .