JP3270493B2 - Lens control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera lens control device.

[0002]

2. Description of the Related Art In recent years, the use of a camera-integrated video tape recorder (VTR) has been remarkable, and the space and weight occupied by a lens unit and an automatic focusing device have been rapidly reduced due to their smaller size and lighter weight. I am doing it.

[0003] In such a background, an automatic focus adjusting device is a so-called active type having an infrared light projecting / receiving device, and a focus is detected from a video signal via an image pickup device without using the aforementioned light projecting / receiving device. It is shifting to a passive system.

On the other hand, in the lens section, there are many so-called inner focus type lenses which are provided with a function of adjusting the focus of a lens which corrects the movement of the focal plane due to zooming, and which is intended to be fixed by fixing the front lens. It came to be introduced.

FIG. 4 shows an example of the above-mentioned inner focus lens type. Reference numeral 101 denotes a fixed first lens group, 102 denotes a second lens group (zoom lens) for changing magnification, and 103 denotes an aperture. Reference numeral 104 denotes a fixed third lens group, and reference numeral 105 denotes a fourth lens group (a focus lens or a compensator lens) having both a function of correcting movement of a focal plane due to zooming and a function of focusing.
Also, reference numeral 106 denotes an image sensor, and the figure shows its image sensing surface.

FIG. 5 shows the change of the focal length, that is, the position of the focus lens 105 for focusing on each object distance with respect to the position of the zoom lens 102. When there is no change in the focal length, that is, when the zoom lens 102 is stopped, the focus lens 10
5 can be adjusted by moving the lens 5 in parallel with the vertical axis on the corresponding focal length (horizontal axis) in FIG.
During the zoom operation, the trajectory of the focus lens 105 is selected from FIG. 5 in accordance with each subject distance, and drive control corresponding to a change in the focal length is performed on the focus lens 105 according to the trajectory. For example, a zoom operation can be performed while providing a focal plane correction and a focus adjustment function by zooming, and a video signal without blurring can be obtained even during the zoom operation.

FIG. 6 is a diagram for explaining an example of a drive control method during the zoom operation of the focus lens 105. The method of obtaining coordinates is the same as that of FIG.
Are divided into a plurality of areas according to the position of the zoom lens (focal length) and the position of the focus lens (object distance), and the representative velocity of the focus lens is given to each area. Arrows in FIG. 6 whose angles are changing every moment indicate changes in the speed of the focus lens 105.

In the example of FIG. 1, the moving area (horizontal axis) of the zoom lens 102 is divided into 16 equal parts, and the focus lens driving speed is set for each area. Here, each area after 16 equal divisions is referred to as a zoom zone. By dividing the curve in FIG. 5 for each zoom zone, it is possible to divide the curve into portions having substantially the same inclination in each zoom zone. When the driving speed of the zoom lens, that is, the zoom speed is constant, if the speed, that is, the inclination of the focus lens in each zoom zone is equal, the moving speed of the focus lens 105 can be equalized even if the subject distance is different. it can. Therefore, as shown in FIG. 6, the vertical axis is divided into portions having the same inclination for each zoom zone, and one representative speed is given to each region.

In this way, if focusing is performed at the start of zooming, the positions of the zoom lens and the focusing lens are detected to determine the reference driving speed of the focusing lens, and for example, the AF device is driven by the AF device. The zoom operation can be performed while correcting this based on the front-focus and post-focus information, and it is possible to always follow the locus of FIG. 5 at an appropriate moving speed of the focus lens 105.

[0010]

By the way, the zoom lens 102 is located at the wide end as shown in FIG. 5, and the focus lens 105 is focused on an object at an infinite distance, that is, near the point A. And As is clear from FIG. 5, at the wide end, the cam trajectory for each subject distance is concentrated near point A, and depending on the F-number of the lens or the aperture, for example, the focusing lens position of infinity and 3 m is within the depth. When you enter, things happen. In the case of the above-mentioned passive type automatic focusing device, especially when the position of the focus lens enters the depth, even if an infinite subject is photographed, the subject distance is 3 mm.
In many cases, the focus lens stops at the in-focus position of m. As described above, when the focus is determined at the lens position different from the actual object distance and the lens is stopped, zooming from the wide side to the tele side as shown in the conventional example, the cam locus at a different position. There is a disadvantage that the cam trajectories corresponding to the respective object distances are dispersed, and the blur is enlarged at a different depth. In particular, if the control of the automatic focusing device is interrupted and zooming is performed in a so-called manual focus state, the trajectory cannot be corrected during zooming, so that blurring almost certainly occurs during zooming. .

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is characterized by a first lens group for performing zooming and a first lens group. The displacement of the focal plane due to the movement of the lens is corrected according to the movement trajectory information stored in advance, and the second lens group for maintaining the in-focus state, and the first lens group moves from the tele side to the wide side. passing of during zooming operation, the first lens group
Of the second lens group corresponding to the plurality of moved positions
Storage means for storing movement position information; and a first lens group when the first lens group moves from a wide side to a tele side .
Each passing through respectively, the moving position <br/> location information of the second lens group stored in said storage means, the current second lens group movement position information but a plurality of movement positions Control means for calculating a shift amount of the second lens group by comparing with the above, and correcting a driving speed based on the movement trajectory information of the second lens group based on the information of the shift amount. Lens control device. The control means operates, for example, during manual focusing.

[0012]

According to this, during a zoom operation from the tele side to the wide side where blur is relatively unlikely to occur, a focus lens (second lens) corresponding to a plurality of moving positions passed by the zoom lens (first lens group) is provided. stores the moving position information of the group), when performing the zooming operation to the telephoto side from the wide side, particularly in the manual focus mode,'s
Lens passes through each of the plurality of moving positions
Each time, the stored moving position information of the focus lens is compared with the current moving position information to calculate a shift amount of the focus lens, and a driving speed based on the movement locus information of the focus lens is calculated based on the information of the shift amount. Is corrected, a zoom operation with less blur can be performed even in the manual focus mode.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lens control device according to an embodiment of the present invention.

FIG. 1 is a block diagram showing the configuration of an embodiment in which the lens control device of the present invention is applied to a video camera.
Reference numerals 1, 102, 103, 104, 105, and 106 are the same as the various optical system elements such as the lens and the aperture shown in FIG. Reference numerals 107, 108, and 109 denote actuators for moving the zoom lens 102, the diaphragm 103, and the focus lens 105, respectively. Reference numerals 110, 111, and 112 denote actuators 107, 108, and 109, respectively, based on signals from a system control circuit 119 described later. Drivers 113, 114, and 115 are position encoders for detecting the movement states of the zoom lens 102, the aperture 103, and the focus lens 105 and converting the signals into electric signals, 113 is a zoom encoder,
114 is an iris encoder, and 115 is a focus encoder. 116, an amplifier for amplifying the output of the image sensor 106 to a predetermined level; 117, a bandpass filter for extracting a high-frequency component used for focus detection from the output signal of the image sensor 116; 118, an output signal level of the image sensor 116 An aperture control circuit 119 for controlling the state of the aperture using the zoom lens 113 and the iris encoder 1
14, an actuator 10 based on output signals from the focus encoder 115 and the bandpass filter 117.
A system control circuit for controlling the microcomputers 7 and 109. The system control circuit is constituted by a micro computer.

Reference numeral 120 denotes a focus switch for moving the focus lens 105 during manual focusing, 121 denotes a zoom switch, and 122 denotes an auto / manual switching switch for switching between automatic and manual focus adjustment.

In the video camera system configured as shown in FIG. 1, the tracing operation of the cam locus drawn by the zoom lens and the focus lens shown in FIG. 5 is controlled by the system control circuit 119. The speed information is stored as a table in the system control circuit 119, and the trajectory to be traced is determined by referring to the table from the positions of the focus lens and the zoom lens, and the focus lens driving speed for following this is determined. I do.

In the system control circuit 119, focus lens control for automatic focus adjustment is also performed. For example, the level of a high-frequency component of a video signal is detected from the output signal of the band-pass filter 117, and this level is detected. The focus lens 105 is driven and controlled via the driver 112 and the actuator 109 so as to be maximized. Therefore, by using this automatic focus adjustment algorithm, it is possible to determine the in-focus state and the out-of-focus state even during zooming, and to determine the focus before and after the focus.

FIG. 2 is a flowchart showing a processing procedure in the lens microcomputer 119.

In FIG. 1, when the process is started at 201, it is determined at 202 whether or not the zoom switch 121 is operated. If the zoom switch has not been operated, the process proceeds to step 203, and the AF operation or manual focus adjustment is performed according to the state of the switch 122.

When the focus adjustment is completed in 203 and the in-focus state is reached, and the discrimination processing of 202 is performed,
If the zoom switch 121 is operated and it is determined that the zoom operation is being performed in any direction, it is determined whether the zoom operation is from tele to wide or from wide to tele. Is done.

If the zoom operation is from tele to wide, the following operation is performed. That is, the process proceeds to 204, where it is determined whether or not the zoom lens position is at the boundary of each zoom zone shown in FIG. If the zoom lens is located on the boundary of the zoom zone, the process proceeds to step 205 where the number assigned to the boundary is captured and confirmed. At 206, the focus lens position at that time is captured. And 205
The focus lens position information is stored in the memory corresponding to the boundary number fetched in step (1).

When the zoom operation is performed from the telephoto to the wide, the stored data is a portion indicated by a circle in FIG. In the figure, m and m + 1 are zoom zone numbers, and Pm and Pm + 1 are focus lens position information stored with addresses m and m + 1, respectively.

Thereafter, the flow advances to step 208 to read out the focus lens driving speed during the zoom operation corresponding to the current zoom zone and focus lens position from the table shown in FIG. The zoom operation is performed while correcting the trajectory by also referring to the front focus and rear focus information from the AF control program.

If it is determined in step 204 that the zoom lens is not at the boundary of the zoom zone,
05, 206, and 207 are not executed, and 20
8, the focus lens driving speed during the zoom operation corresponding to the current zoom zone and focus lens position is read from the table shown in FIG. 6, and the front focus and rear focus information from the AF control program are used. Thus, the zoom operation is performed while correcting the trajectory.

Here, although briefly mentioned in the above description, in the inner focus type lens system as in the present invention, it is easy to identify the cam locus with respect to the object distance on the tele side, and on the wide side, Since each locus converges, identification is difficult. This is clear from FIG. Therefore, when performing a zoom operation from the tele side to the wide side in a focused state, even if the automatic focus adjustment is not performed, the cam locus corresponding to the object distance is uniquely selected and the zoom without blur is performed . The operation can be performed.

Therefore, by the above-described processing, the zoom operation from telephoto to wide can be performed with good blur and good operation, and the trajectory of the focus lens by the good zoom operation is stored in the memory. be able to.

Next, a case where the zoom lens is moved from wide to tele will be described.

If it is determined in step 202 that the zoom lens has been moved from the wide-angle side to the telephoto side, the process proceeds to step 20.
In step 9, it is determined whether the mode is the manual focus mode or the auto focus mode. In the case of the auto focus mode, the front focus from the automatic focusing device used in 203,
Since the cam locus can be accurately corrected by using the rear focus determination information, referring to the above-described table storing the focus lens driving speed corresponding to the zoom lens position and the focus lens position at 218, A corresponding cam locus is selected, and a zoom operation is performed from wide to tele along the locus.

If it is determined in the determination process at 209 that the mode is the manual focus mode, the process proceeds to 210 to determine whether or not the zoom lens is positioned at the boundary of the zoom zone. Otherwise, 2
Then, the process shifts from wide to tele of the zoom lens using the corrected focus lens speed information determined in the process 216 (described later) in the immediately preceding process (execution of the previous control flow). The focus lens is made to follow the zoom operation.

If it is determined in step 210 that the zoom lens is located at the boundary of the zoom zone, the process proceeds to step 211 to fetch the number m of the zoom zone. Is stored based on the output of the focus lens position encoder 115, and the focus lens position storage data Pm stored in the process of 207, that is, the circle mark in FIG. Read the position data marked with. The read data indicates a cam locus position for performing the zoom operation with less blur when the data is stored by performing the zoom operation from telephoto to wide and when the subject distance is not changed.

Then, at 214, the current focus lens position information captured at 212 is compared with the position storage data Pm read from the memory at 213, and in what direction and how much, It is detected whether the current focus lens position is shifted.

Next, at 215, referring to the table of FIG. 6 in the same manner as the process at 218, the focus lens moving speed during zooming is obtained from the zoom lens position information at the process 211 and the focus lens position information at the process 212. Is selected, and only the data of that locus is extracted. In step 216, it is determined whether the front focus side shift or the rear focus side shift occurs based on the shift amount and the direction of the movement position of the focus lens obtained by the process in step 214. Then, processing for correcting the focus lens drive speed information selected from the table is performed. For example, the speed data extracted in the process of 215 drives the focus lens to the closest side,
If the result of the comparison processing indicates that the front lens is shifted to the front focus side, the speed drawn out of the table is reduced at 215 to correct the position of the focus lens in the rear focus direction. Then, the process proceeds to 217, where the zoom operation is performed from wide to tele, and the focus lens is made to follow the speed corrected at 216. If the result of the comparison process at 214 indicates that the focus is shifted to the rear focus side, the speed at which the focus lens is pulled out from the table is increased at 215 to correct the position of the focus lens in the front focus direction. I do.

If the speed data extracted in the process of 215 is for driving the focus lens to the infinity side, the correction can be performed in the same manner only by reversing the position correction direction of the focus lens.

According to the above operation, when zooming from telephoto to wide even during manual focusing, focus lens control faithful to the cam locus is performed.
When zooming from wide to tele, only during manual focusing, zoom is performed faithfully on the cam trajectory when zooming from tele to wide. As a result, not only when performing the automatic focusing operation but also during manual focusing, if the subject distance does not change, a zoom operation without blur can be performed.

In the above-described inner focus type lens system, since the focus lens is disposed closer to the image pickup device than the variable power lens, the change in the focus lens position sensitivity with respect to the change in the focal length. Almost no. Therefore, when performing the zoom operation, if the focus is within the depth at the starting point, then if the speed following the fixed cam trajectory is given, the defocus amount at the start is maintained, that is, almost no blur It is possible to follow a fixed cam trajectory without generating the following. This has already been confirmed by experiments by the inventor.

In the above-described problem to be solved by the present invention, when zooming from wide to tele, starting from a focus position with respect to another object distance within the depth causes blurring. I explained,
This is a phenomenon that occurs when an incorrect trajectory is selected when an appropriate trajectory is selected from a plurality of cam trajectories stored in a table as shown in FIG. And there is no conflict.

[0037]

As described above, according to the lens control device of the present invention, during the zoom operation from the tele side to the wide side where blur is less likely to occur, it is possible to cope with a plurality of moving positions passed by the zoom lens. stores the moving position information of the focus lens, especially when performing a zoom operation to the telephoto side from the wide side in the manual focus mode, it zoom lens of the plurality of movement positions
Each passing through, respectively, and the storage of the focus lens
By comparing the moving position information with the current moving position information to calculate a shift amount of the focus lens, and correcting the driving speed based on the movement trajectory information of the focus lens based on the information of the shift amount, the subject distance can be reduced. If it does n’t change,
It is possible to perform a blur-free zoom operation from any direction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a lens control device according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the lens control device of the present invention.

FIG. 3 is a diagram for explaining a configuration in a table in which a focus lens driving speed with respect to a zoom lens position is stored.

FIG. 4 is a diagram showing a configuration of a general inner focus lens system.

FIG. 5 is a characteristic diagram showing a trajectory of a focus lens for following a change in focal length by a zoom lens while maintaining a focused state.

FIG. 6 is a diagram showing a state in which a moving range of a zoom lens is divided into a plurality of zones, and a focusing lens moving speed represented by each of the zones is assigned.

[Explanation of symbols]

 105 Zoom lens 106 Image sensor 107-109 Actuator 110-112 Driver 113 Zoom encoder 114 Iris encoder 115 Focus encoder 117 Band pass filter 118 Aperture control circuit 119 System control circuit 120 Manual focus switch 121 Zoom switch 122 Auto / manual switch

Claims (2)

(57) [Claims] 1. A first lens group for performing magnification change, and a displacement of a focal plane caused by movement of the first lens group is corrected in accordance with movement locus information stored in advance to maintain a focused state. And a second lens group corresponding to a plurality of moving positions of the first lens group during the zooming operation from the tele side to the wide side by the first lens group. Storage means for storing the movement position information of the first lens group;
The first lens group passes through each of the plurality of movement positions.
Each that spend a moving position information of the second lens group stored in said storage means, the current second lens groups move
Control means for comparing the moving amount information with the moving position information to calculate a shift amount of the second lens group, and correcting a driving speed based on the movement trajectory information of the second lens group based on the shift amount information; A lens control device, comprising: 2. The lens control device according to claim 1, wherein said control means operates during manual focusing.