JP2007178577A - Optical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To comprehensively enhance focusing accuracy in various scenes that can be supposed, using function of a focus position. <P>SOLUTION: Optical equipment comprises a preset storing means for storing preset information; a preset operation control means for controlling the preset operation, by using preset information stored in the preset storing means; and a focus operation control means for controlling autofocus operation. The optical equipment is provided with a focus range restriction means for restricting the search range of the autofocus operation by the focus operation control means during the preset operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus such as a television camera and a video camera, and an optical apparatus such as a lens apparatus used therefor, and more particularly to an optical apparatus having a preset function for storing a focus lens position.

  In scenes photographed by a surveillance camera or a studio camera, the angle from the camera to the subject position and the size of the subject are often constant. Conventionally, in such a shooting scene, monitoring and shooting are performed at a plurality of locations by using a preset function that previously stores pan, tilt, and zoom positions. Furthermore, in a scene where the distance from the camera to the subject position is constant, performing the preset movement including the focus position is an effective means for capturing a stable and good image. The effect of this preset function is great especially in situations where it is difficult to focus with autofocus during dark weather, foggy weather, and other bad weather conditions.

However, there are cases where the manual focus method of the preset moving photographing method in which the focus position with respect to the preset position is fixed uniformly cannot be handled. For example, when the subject has moved from the preset focus position, or when a new subject has entered the front.
In order to cope with such a case, Patent Document 1 proposes the following configuration. That is, the optical device of Patent Document 1 includes a storage unit that stores preset information, and a preset operation control unit that controls a preset operation using the preset information stored in the storage unit. In addition, there is provided a focus operation control means for controlling the autofocus operation, and a control means for controlling the operation of the preset function by the preset operation control means and the autofocus operation by the focus operation control means. The focus operation control means includes a synchronization signal detection means, an autofocus processing means, and an autofocus drive means. Here, the synchronization signal detecting means generates a reference signal for processing the video signal output from the camera side. The autofocus processing means calculates a motor control signal for controlling the driving of the motor so that the reference signal and the video signal are in focus. The autofocus driving means drives the motor by the motor control signal calculated by the autofocus processing means. As described above, by performing the autofocus operation in combination with the preset operation, even when the subject moves from the preset focus position, the focus can be adjusted to a position adapted to the current subject position during the preset operation.
JP 2005-156849 A

However, the above-described shooting method in which the focus position used during the preset movement is fixed uniformly at the preset position cannot cope with the change in the focal length caused by the movement of the subject, the temperature change of the lens, the change of the subject light source, or the like. . Also, it cannot cope with a case where a new subject having a different focal length is interrupted before a fixed subject specified by a preset. Therefore, there is a problem that it is not always possible to obtain a good image that matches the focal length of the current subject.
In addition, the above-described photographing method disclosed in Patent Document 1 performs an autofocus operation at the time of presetting in order to improve a problem when the focus position is fixed uniformly at the preset position. However, with this photographing technique, it is difficult to obtain an appropriate focus position by autofocusing under a situation where the subject cannot be clearly photographed, such as when photographing in a dark place or during bad weather such as fog. Furthermore, in a camera system in which there is no photographer, such as a surveillance camera, the operator cannot manually refocus properly, and there is a problem that shooting and recording are performed for a long time in a non-focused state. is doing.
It is an object of the present invention to provide an optical device that solves the above-described problems caused by subject fluctuation factors and can improve the focusing accuracy even in various scenes assumed by the focus position preset function.

  An optical device for solving the above-described problems includes preset storage means for storing preset information, and preset operation control means for performing preset operation control using the preset information stored in the preset storage means. Further, a focus operation control means for controlling the autofocus operation is provided. In addition, a focus range limiting unit that limits a search range of the autofocus operation by the focus operation control unit during the preset operation is provided.

  According to the present invention, the range of the autofocus operation is limited during the preset operation. As a result, better focus is obtained than when the focus is fixed at the preset position, and the focus position does not deviate greatly from the focus position even when shooting in dark places or in bad weather such as fog. Can be increased.

  In a preferred embodiment of the present invention, the focus range limiting means sets at least one search range of the autofocus operation in a period from the start point to the end point of one preset operation. For example, three search ranges are set. The first search range corresponds to a change in focal length caused by movement of the subject, lens temperature change, subject light source change, etc., and is a relatively narrow range near or including the preset focus position. Set.

The second search range is set to be wider than the first search range. This is for a case where a new subject having a different focal length is inserted in front of a fixed subject designated by a preset. Preferably, a range closer to the preset focus position is set. In the present embodiment, it is used when an in-focus determination cannot be obtained even if an autofocus operation is performed within the first search range.
The third search range is a case where the focus determination is not obtained even if the autofocus operation is performed in the first and second ranges, and a range narrower than the first search range is set. This assumes a situation where the subject cannot be clearly photographed, such as when shooting in a dark place or during bad weather such as fog. The third search range may be limited to the preset focus position. In this case, the autofocus operation by the focus control means is not performed.

In one embodiment of the present invention, as a limited range of the autofocus operation at the time of preset movement, first, in the first stage, the autofocus operation is performed in the vicinity of the normal preset position and within a range narrower than the normal autofocus operation range. To do. Here, when the predetermined focus degree cannot be obtained, the autofocus operation is performed in the range closer to the preset position in the second stage. Further, here again, when the predetermined focus degree cannot be obtained, the focus preset position is returned to and stopped at the third stage.
In this way, by changing the limit range of the autofocus operation step by step, it is possible to deal with the various situations described above that affect the autofocus operation. That is, in the first stage, it corresponds to a change in the focal length in the vicinity of the preset focus position, which occurs due to a minute movement of the subject, a change in the temperature of the lens, a change in the subject light source represented by infrared illumination projection, and the like. Further, this corresponds to the case where a new subject having a different focal length is interrupted in the second stage. Furthermore, in the third stage, the camera returns to a preset focus position that is appropriate at the time of dark place photography or in bad weather such as fog. By realizing these simultaneously, it is possible to provide an optical apparatus capable of increasing the focusing accuracy in various scenes assumed by the focus position preset function.

Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is a block diagram showing a circuit configuration of an imaging apparatus (preset camera apparatus) according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the relationship between the imaging apparatus of FIG. 1 and the subject situation. FIG. 3 is a flowchart showing preset operation control in the subject situation shown in FIG. 2 of the imaging apparatus of FIG.
In this embodiment, auto-focusing is performed during preset movement in a configuration that combines a preset operation having a pan head control function and auto-focus.
The circuit shown in FIG. 1 is roughly divided into three functional units: a camera control unit 10, a pan head device 20, and a lens unit 30. The camera control unit 10 is connected to the external camera control means 50. Further, the part including the camera control unit 10 and the lens unit 30 is supported by the pan head device 20 via the support unit 60.

  The camera control unit 10 includes a microcomputer 11, a preset storage unit 12, a camera signal processing circuit 13, a video encoder 14, an external communication unit 15, an image sensor 16, and a timing generator 17. The preset storage means 12 is means for storing camera preset information mainly using a nonvolatile memory or the like, and the microcomputer 11 appropriately rewrites and reads the stored contents. The imaging element unit 16 is an imaging element such as a CCD sensor or a CMOS sensor that photoelectrically converts an object image formed on the imaging surface by the lens unit 30 into an imaging signal. The camera signal processing circuit 13 generates a luminance signal and a color signal based on the imaging signal output from the imaging element 16, and performs a series of video signal processing such as signal processing such as color correction and gamma correction, and effect processing. Do. The timing generator 17 is a timing generator that generates a pixel readout timing and drives the image sensor 16 to send a predetermined image to the camera processing circuit 13.

The external camera control means 50 is a control means in which an operation operator who performs camera operation issues a camera control remote instruction such as movement in the camera shooting direction and zoom operation from a place away from the camera system. The external camera control means 50 is composed of a personal computer, a dedicated controller, and the like.
The external communication unit 15 is a communication interface unit that transmits a camera control remote instruction from the external camera control unit 50 to the microcomputer 11. The external communication unit 15 and the external camera control unit 50 are connected using a communication line such as RS-232C, RS-485, EtherNET, or wireless. Thus, the camera system can be controlled by remote operation even when there is no operator near the camera.

The microcomputer 11 controls the entire camera system such as the pan head device 20, the camera signal processing circuit 13, the preset storage unit 12, and the external communication unit 15. The microcomputer 11 stores the preset storage information in the preset storage unit 12 when an instruction to store the camera preset information is generated outside or inside the camera as processing of the preset related information. The preset related information includes PAN information, TILT information, zoom information, focus information, exposure information, and the like. When the camera preset information is read or a movement request is generated, the preset storage information is read from the preset storage unit 12 and an operation start command is issued to each function of the preset operation component.
The microcomputer 11 also acquires movement request information in the camera photographing direction generated by the operation operator performing the PAN / TILT operation, and a motor necessary for rotating the camera platform 20 to the target position based on the request information. Control information is calculated. Then, the pan head rotation control is performed by driving the PAN motor driver 23 and the TILT motor driver 24 based on the calculated information.

The pan head unit 20 includes a PAN motor 21, a TILT motor 22, a PAN motor driver 23, and a TILT motor driver 24, and supports the camera control unit 10 and the lens unit 30 via a support unit 60. The PAN motor 21 and the PAN motor driver 23 rotate the camera photographing direction in the horizontal (left-right) direction by driving a PAN rotation mechanism (not shown) in accordance with a rotation instruction from the microcomputer 11. The horizontal position information is acquired by using a stepping motor as the PAN motor 21 and integrating the number of drive pulses by the microcomputer 11 to relatively calculate the rotational position. Similarly, the TILT motor 22 and the TILT motor driver 24 rotate the camera photographing direction in the vertical (up and down) direction by driving a TILT rotation mechanism (not shown) according to a rotation instruction from the microcomputer 11. In order to acquire the position information in the vertical direction, a stepping motor is used as the TILT motor 22 and the rotational position is calculated by integrating the number of drive pulses by the microcomputer 11.
Also, for example, the horizontal and vertical position information acquisition method is not limited to the stepping motor, but uses any driving means such as a DC motor, and the position information is detected by using an encoder or the like. It is also possible.

The lens unit 30 includes a zoom lens optical system 32, a diaphragm mechanism 33, a focus lens optical system 34, a zoom motor 37, an IG meter 38, and a focus motor 39. The zoom lens optical system 32 performs zooming adjustment of the lens device. The aperture mechanism 33 is for limiting the amount of incident light. The focus lens optical system 34 is for focusing the subject on the image sensor 16. The zoom motor 37 drives the zoom lens optical system 32. The IG meter 38 drives the aperture mechanism 33. The focus motor 39 drives the focus lens optical system 32. The lens unit 30 further includes drive circuits 41, 42, and 43 for driving the zoom motor 37, the iris IG meter 38, and the focus motor 39, respectively.
The drive circuits 41, 42, and 43 are configured to be directly controlled from the microcomputer 11. In the preset movement control, each drive control is performed by zoom drive, focus drive, and aperture drive signal issued from the microcomputer 11 based on the preset position information.

Next, the necessity of the focus preset function in the apparatus of FIG. 1 will be described using the relationship explanatory diagram showing the relationship between the preset camera apparatus of FIG. 2 and the subject situation.
First, in Case 1, a normal imaging environment is cited. In the figure, 70 is a camera system, 71 is a subject to be preset, 72 is an illumination device that emits auxiliary light to the subject at night and the like, and infrared illumination light is assumed here. Also, the thin line in the direction of the lens optical axis of the camera in the figure represents the focal length between the camera and the subject. The direction closer to the camera is the closest direction and the direction farther from the camera is the infinite (∞) direction. Here, as a focal length, symbol A is a preset focus position representing a focal length to be focused on the subject 71 to be preset, and this position information is stored in the preset storage means 12. Symbol B indicates a focus control limit range set in the vicinity of the preset focus position, and is an autofocus search range that is predetermined according to the zoom position of the lens.

In the normal shooting environment shown here, the focus lens is first moved to the focal length A when a movement to the preset target subject 71 is designated by an instruction from an operator or an automatic patrol program. Thereafter, auto focus processing is performed within the focus movable range B, the focus lens is stopped at the focus position with the highest degree of focus, and the preset operation is terminated.
Here, for example, when the preset target object 71 is illuminated by the illumination device 72 such as at night, the focal length changes due to the optical wavelength aberration of the optical system according to the difference between the light wavelength of the illumination device and the light wavelength of the normal light source. appear. This change in focal length is an element that leads to out-of-focus as it is, and it is impossible to deal with this problem only by a process of forcibly stopping at the preset focus position A as a preset movement function. Therefore, this problem can be dealt with by performing the autofocus process in the focus movable range B (first search range).

  Next, in Case 2, a case where a subject 73 having a focal length different from the preset focus position A appears in front of the preset target subject 71 will be described. In such a shooting environment, the preset focus processing forcibly stopping at the preset focus position A results in an out-of-focus image obstructed by the subject 73. That is, there arises a problem that an inappropriate photographed image in which any subject in the screen is not focused is generated. As a method of dealing with this problem, the focus range is extended in a range limited to the closest direction from the preset focus position A. By performing the autofocus process in this range (second search range), it is possible to obtain an appropriate in-focus image for the new subject 73. Further, by limiting the extension of the focus range to the closest direction, it is possible to simultaneously shorten the autofocus treatment time.

Next, Case 3 gives a situation in which a preset target subject cannot be clearly photographed in nighttime dark place photography or in bad weather such as fog.
In general, in autofocus processing, high-frequency components of an image capturing a subject image are detected. When the peak value exceeding the predetermined focus determination threshold level is obtained at the position where the high-frequency component is maximum, it is determined that the focus position has reached the focus position.
As described here, in the case of nighttime dark place shooting or bad weather such as fog, an appropriate high-frequency component cannot be detected even if the focus lens position is at the optimum focus position. Therefore, in the autofocus process, there is a problem that an erroneous focus operation is performed without being determined as being in focus, and the camera stops in an out-of-focus state. In such a case, the process of detecting the in-focus position by the autofocus process is inappropriate, and the determination to stop the focus in the preset focus position A or an extremely narrow range including the position (the third search range) is appropriate. It is.

Next, the operation of the focus preset function will be described using the flowchart representing the focus preset control of FIG.
First, in Step 1, the presence / absence of a preset movement request is confirmed. When there is no request, the focus preset process is not executed and the standby state is maintained.
Here, when a preset movement request is generated, preset information is acquired from a memory serving as preset information storage means in Step 2 that follows. Furthermore, the focus lens position is moved to the focus position A preset in the manual focus mode according to this information.

In subsequent Step 3, the current zoom lens position information is first acquired.
Next, in Step 4, an autofocus limit range B (first search range) is calculated based on focus limit range information for each zoom position stored in storage means such as a memory (not shown).
In the subsequent Step 5, autofocus processing is executed with the autofocus limit range B calculated in Step 4 as the control range, and the subject is focused.
In subsequent Step 6, whether to stop the preset focus process or continue to the next process is determined based on whether the subject is in focus or not. If the predetermined focus degree is obtained as a result of the autofocus process here, the focus process is terminated and the focus lens is stopped. On the other hand, if the predetermined focus degree is not obtained, the next autofocus limit range C (second search range) is calculated in Step 7.

Step 7 is a response process when a new subject having a different focal length appears in front of the preset subject.
In Step 7, the focus process is performed in a range wider than the autofocus limit range B calculated in Step 4 and limited to the closest direction from the preset focus position A.
Therefore, a new focus limit range C is calculated based on the focus limit range information for each zoom position stored in a storage unit such as a memory as in Step 4 processing.
In the following Step 8, autofocus processing is performed using the autofocus limit range C calculated in Step 7 as a control range, and focusing on the subject is performed.
In Step 9, whether to stop the preset focus process or continue to the next process is determined based on whether the subject is in focus or not. If the predetermined focus degree is obtained as a result of the autofocus process here, the focus process is terminated and the focus lens is stopped.
On the other hand, when the predetermined focus degree is not obtained, the focus lens position is moved to the focus preset position A and stopped at Step 10. In general, a better focused image can be obtained by performing this process during nighttime dark place shooting or in bad weather such as fog.

  As described above, with the configuration in which the focus position is stored in the preset movement function, as the preset focus processing for focusing on a determined subject, processing for changing the autofocus operation limit range step by step is performed. This corresponds to a change in the focal length in the vicinity of the preset focus position, which occurs due to a minute movement of the subject, a change in the temperature of the lens, a change in the subject light source that represents infrared illumination projection, and the like. At the same time, it is possible to simultaneously cope with a case where a new subject having a different focal length is interrupted and to return to a preset position suitable for shooting in a dark place or in bad weather such as fog. As a result, it is possible to provide an optical device and a camera system capable of increasing the focusing accuracy even in various scenes assumed by the focus position preset function.

  Note that the processing to deal with the situation where the preset target subject cannot be clearly photographed in the case of bad weather such as nighttime dark place photography or fog as listed in Case 3 is a process of uniformly moving to the preset focus position A and stopping. . However, the preset focus position A is corrected based on temperature information obtained by adding temperature detection means for detecting the lens temperature and light wavelength information obtained by attaching wavelength detection means for detecting the subject light wavelength. The stop position may be set.

It is a block diagram which shows the circuit structure of the imaging device (preset camera apparatus) which concerns on one Example of this invention. FIG. 2 is an explanatory diagram illustrating a relationship between a preset camera device of FIG. 1 and a subject situation. 3 is a flowchart showing preset operation control in the subject situation shown in FIG. 2 of the preset camera device of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Camera control part 11: Microcomputer 12: Preset memory | storage means 13: Camera signal processing circuit 14: Video encoder 15: External communication means 16: Image pick-up element 17: Timing generator 20: Pan head apparatus 21: PAN motor 22: TILT motor 23 : PAN motor driver 24: TILT motor driver 30: Lens unit 32: Zoom lens optical system 37: Zoom motor 38: IG meter 39: Focus motor 41: Zoom motor drive circuit 42: IG meter drive circuit 43: Focus motor drive circuit 50 : External camera control means 60: Pan head support part 70: Camera system 71: Preset target subject 72: Lighting equipment 73: Subject not subject to preset

Claims (8)

Preset storage means for storing preset information;
Preset operation control means for performing preset operation control using preset information stored in the preset storage means;
Focus operation control means for controlling autofocus operation;
In an optical device comprising:
An optical apparatus comprising: a focus range limiting unit that limits a search range of an autofocus operation by the focus operation control unit during a preset operation.   The optical apparatus according to claim 1, wherein the focus range limiting unit sets at least one search range of an autofocus operation in a period from a start time to an end time of a preset operation.   The optical apparatus according to claim 1, wherein the focus range restriction unit sets a range in the vicinity of the preset focus position or a range including the preset focus position as the first search range.   The optical apparatus according to claim 3, wherein the focus range limiting unit sets a range wider than the first search range as the second search range.   The optical apparatus according to claim 4, wherein the second search range is set closer to the preset focus position.   6. The optical apparatus according to claim 4, wherein the focus range limiting unit sets a range narrower than the first search range as a third search range.   The optical apparatus according to claim 6, wherein the focus range limiting unit sets the preset focus position as the third search range.   The focus operation control means performs an autofocus operation within the first search range after starting the preset movement, and when the focus determination is not obtained by the autofocus operation within the first search range, the second search is performed. The autofocus operation is performed within the range, and when the focus determination is not obtained by the autofocus operation within the second search range, the autofocus operation is further performed within the third search range. 8. The optical device according to 6 or 7.

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