JP2006139015A - Lens system for stereo camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens system for a stereo camera where the positions of a focus lens group and a zoom lens group arranged in a plurality of optical systems are detected by an accurate encoder so as to control the lens groups, whereby a difference between the viewing angles of right and left videos taken through the respective optical systems and the difference of focusing accuracy are made small as a lens system applied to a stereo camera. <P>SOLUTION: The lens system for the stereo camera is constituted of a lens device 10A and a lens device 10B having the same specification, and the focus lens group FL and the zoom lens group ZL in the respective lens devices are driven by motors FM and ZM, and controlled by feedback control by a CPU 20. The positions of the focus lens group FL and the zoom lens group ZL are detected by the encoders FE and ZE and a counter 24, and a detection value is given to the CPU 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens system for a stereoscopic camera, and more particularly to a lens system for a stereoscopic camera used for a stereoscopic camera that captures right-eye and left-eye parallax images using two cameras to capture a stereoscopic image. .

  2. Description of the Related Art Conventionally, a stereoscopic camera that captures a stereoscopic image by, for example, arranging two television cameras in parallel and capturing parallax images for the right eye and the left eye is known. The two lens devices used in the stereoscopic camera are driven simultaneously so that optical conditions that change depending on the state (position) of the controlled object, such as focus, zoom (focal length), and diaphragm, always coincide. Yes.

Japanese Patent Application Laid-Open No. 2004-228867 considers that it is difficult to set the same condition due to a manufacturing error or a processing error even when a lens device having the same specification is used for such a stereoscopic camera. It has been proposed to correct their positions with correction data so that their focus and zoom coincide.
Japanese Patent No. 3117303

  As described above, the two lens devices used in the stereoscopic camera need to operate at the same time while matching the positions of the same control target such as the focus so that the optical conditions always match. However, the optical conditions do not completely match due to variations in parts and assembly of the two lens devices. For this reason, a difference occurs in the angle of view and the focus accuracy between the left and right images, resulting in a problem that the images are difficult to see during reproduction.

  According to Patent Document 1, it is possible to eliminate such a problem, but since it is necessary to create correction data for each product, the work requires time and labor. In particular, since it is difficult to measure errors related to focus and zoom between two lens apparatuses, it is not easy to create correction data for them.

  On the other hand, if the degree of variation between the left and right images is small, the human visual function corrects the image, so there is no sense of incongruity and there is little need for correction on the lens device side. Conventionally, a potentiometer is used for a position detector to be controlled such as focus and zoom of a lens device used in a stereoscopic camera, and an error in optical conditions generated between two lens devices is a linearity error of the potentiometer. The cause is great. If the accuracy of the position detector is high and mechanical errors are the main factors causing errors in the optical conditions, the variation in the left and right images caused by the error in the optical conditions is corrected by the human visual function. It will be as small as possible.

  The present invention has been made in view of such circumstances, and by using simple methods and means, errors in optical conditions of a plurality of optical systems in a stereoscopic camera are reduced to such an extent that a reproduced stereoscopic image does not feel uncomfortable. An object of the present invention is to provide a lens system for a stereoscopic camera that can be used.

  In order to achieve the object, a stereoscopic camera lens system according to claim 1 is for a stereoscopic camera including a plurality of optical systems of a stereoscopic camera that captures a stereoscopic image and a control unit that controls the plurality of optical systems. In the lens system, each optical system includes a lens group movable in an optical axis direction, and the control unit uses an encoder as a position detection unit that detects a position of the lens group. According to the present invention, since the position of the lens group such as the focus lens group and the zoom lens group is detected by an encoder with high accuracy and good linearity, the optical conditions of each optical system are set to such an extent that the reproduced stereoscopic video image does not feel uncomfortable. The error can be reduced.

  According to a second aspect of the present invention, in the lens system for a stereoscopic camera according to the first aspect, each of the optical systems includes a diaphragm, and the control unit corrects a position instructed by an operation signal given from the outside. Then, by setting the position of the diaphragm of each optical system at the corrected position, the conditions regarding the diaphragm of each optical system are matched. According to the present invention, since the mechanical variation is large with respect to the diaphragm, the conditions regarding the diaphragm in each optical system are matched by correcting the position to be set.

  The lens system for a stereoscopic camera according to claim 3 is the invention according to claim 1 or 2, wherein the control unit moves the lens group by a motor based on an operation signal given from the outside, and The responsiveness of the lens group with respect to the operation signal is changed according to the gradient of the direction of movement. According to the present invention, the movement of the lens group in each optical system is performed with stable operation regardless of the gradient in the movement direction, and the error of the position of the lens group in each optical system when the lens group is moved, etc. Can be reduced.

  According to a fourth aspect of the present invention, in the lens system for a stereoscopic camera according to the first, second, or third aspect of the invention, the lens group is a focus lens group and / or a zoom lens group.

  The stereoscopic camera lens system according to claim 5 is the invention according to any one of claims 1 to 4, wherein the control unit includes a plurality of control units for each of the optical systems. Yes. In the present invention, each optical system of the stereoscopic camera is controlled by a separate control unit.

  According to the three-dimensional camera lens system of the present invention, by using simple methods and means, the errors in the optical conditions of a plurality of optical systems in the three-dimensional camera are reduced to such an extent that the reproduced three-dimensional image does not feel uncomfortable. Can do.

  Hereinafter, preferred embodiments of a lens system for a stereoscopic camera according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a main configuration of a stereoscopic camera lens system according to the present invention. In this figure, this lens system is composed of two lens devices 10A and 10B having completely the same specifications, and these lens devices 10A and 10B capture a stereoscopic image (parallax image) (stereoscopic image). TV camera) is mounted in parallel to the camera body. For example, the lens device 10A is used for capturing a right eye image, and the lens device 10B is used for capturing a left eye image. Each of the lens devices 10A and 10B includes an optical system (photographing lens) and a control system (control unit), and the optical system and the control system are completely matched. In the figure, the same reference numerals are given to the same components of the lens device 10A and the lens device 10B, and only the configuration of the lens device 10A will be described below, and the configuration of the lens device 10B is the same as that of the lens device 10A. The description is omitted as it is the same.

  In the optical system (photographing lens) of the lens apparatus 10A, optical components such as a focus lens group FL, a zoom lens group ZL, a diaphragm I, and a master lens group (not shown) are arranged inside the lens barrel. The focus lens group FL and the zoom lens group ZL are arranged so as to be movable back and forth along the optical axis, and focus adjustment (adjustment of subject distance) is performed by adjusting the position of the focus lens group FL. Zoom adjustment (focal length adjustment) is performed by adjusting the position of ZL. Further, the light amount is adjusted by adjusting the position (aperture) of the diaphragm I. Subject light that has entered the photographic lens and passed through these lens groups and the like is imaged on an imaging surface of an imaging device arranged in a camera body of a stereoscopic camera (not shown).

  The control system of the lens apparatus 10A includes a CPU 20 that controls the entire control system, a focus motor FM, a zoom motor ZM, and an aperture motor IM connected to the focus lens group FL, the zoom lens group ZL, and the aperture I, respectively. A focus amplifier FA, a zoom amplifier ZA, and an aperture amplifier IA that supply driving power to the motors FM, ZM, IM, respectively, an encoder FE, an encoder ZE, and the like connected to the focus lens group FL and the zoom lens lens group FL are arranged. Yes.

  The lens device 10A is connected to a focus controller 26 for an operator to perform a focus operation using a predetermined manual operation member and a zoom controller 28 for an operator to perform a zoom operation using a predetermined manual operation member. . The focus controller 26 and the zoom controller 28 are also connected to the lens device 10B.

  The focus lens group FL, the zoom lens group ZL, and the aperture I are in a state in which the CPU 20 drives the motors FM, ZM, IM based on the operation signals given from the focus controller 26, the zoom controller 28, etc. To be controlled.

  The control of the focus lens group FL (focus control) will be described. In the focus controller 26, an output voltage indicating a target position where the focus lens group FL should be set is set based on the operation of the manual operation member by the operator, and the output thereof A voltage signal (focus operation signal) is output from the focus controller 26. The CPU 20 reads the focus operation signal via the A / D converter 30 and sets a target value indicating the target position of the focus lens group FL based on the voltage value of the focus operation signal.

  On the other hand, the current position of the focus lens group FL is detected by the encoder FE and the counter 24. The encoder FE is, for example, an incremental rotary encoder, and the detection shaft rotates in conjunction with the movement of the focus lens group FL, and the detection shaft rotates in accordance with the movement direction (movement direction) of the focus lens group FL. The direction is switched between forward rotation and reverse rotation. Each time the detection shaft of the encoder FE rotates by a predetermined amount, the encoder FE outputs two-phase pulses of A phase and B phase having a phase difference of 90 degrees, for example, and the counter 24 outputs these two-phase pulses. Each time it is detected, the count value is incremented or decremented by one. At this time, for example, when the phase A pulse is 90 degrees ahead of the phase B pulse, 1 is added to the count value, and when the phase is 90 degrees behind, 1 is subtracted from the count value. . As a result, the rotational position of the detection shaft of the encoder FE, that is, the current position of the focus lens group FL is detected as the count value of the counter 24. The count value of the counter 24 is reset in a state where the focus lens group FL is set to a specified position (for example, the closest end) when the power is turned on.

  The CPU 20 reads a count value indicating the current position of the focus lens group FL as a control amount in feedback control. A drive signal having a value obtained by multiplying the deviation between the target value set based on the focus operation signal as described above and the control amount indicating the current position of the focus lens group FL by a predetermined coefficient (error amplification factor) is D. The signal is supplied to the focus amplifier FA via the / A converter 22. The focus motor FM is driven at a speed proportional to the voltage of the drive signal applied to the focus amplifier FA. The larger the deviation between the target value and the control amount, the faster the focus motor FM rotates. The focus lens group FL moves at high speed. Conversely, as the deviation between the target value and the control amount is smaller, the focus motor FM rotates at a lower speed and the focus lens group FL moves at a lower speed. When the deviation becomes 0, the rotation of the focus motor FM stops and the movement of the focus lens group FL stops. In addition, the rotation direction of the focus motor FM varies depending on whether the deviation is positive or negative, and the focus motor FM rotates in a direction in which the deviation becomes smaller. Therefore, the focus lens group FL always moves in a direction in which the control amount approaches the target value. As a result, the focus lens group FL is set at a position that matches the target value set by the focus operation signal, and moves in accordance with the change in the target value.

  The control (focus control) of the focus lens group FL as described above is similarly performed for the control (zoom control) of the zoom lens group ZL. Although details are omitted, in the case of zoom control, the CPU 20 reads a zoom operation signal output from the zoom controller 28 and sets a target value indicating a target position where the zoom lens group ZL should be set based on the zoom operation signal. To do. The current position of the zoom lens group ZL is detected by the encoder ZE and the counter 24, and the CPU 20 reads the count value of the counter 24 indicating the current position of the zoom lens group ZL as a control amount in feedback control. Then, a drive signal having a value obtained by multiplying the deviation between the target value set based on the zoom operation signal and the control amount indicating the current position of the zoom lens group ZL by a predetermined coefficient (error amplification factor) is given to the zoom amplifier FA. The zoom motor ZM is driven so that the target value matches the control amount. As a result, the zoom lens group ZL is set to a position that matches the target value set by the zoom operation signal, and if the target value changes, it moves following it.

  In the above control, the focus controller 26 and the zoom controller 28 output the focus operation signal and the zoom operation signal indicating the target position. However, the controllers 26 and 28 perform the focus lens group FL and the zoom lens group ZL. In some cases, a focus operation signal or a zoom operation signal indicating the target moving speed (target speed) is output. In this case, the CPU 20 controls the rotation speed of the focus motor FM and the zoom motor ZM so that the focus lens group FL and the zoom lens group ZL have the given target speed, and the movement speed of the focus lens group FL and the zoom lens group ZL. To control.

  In this way, in focus control and zoom control, encoders FE and ZE that have high linearity and high-accuracy position detection are used for position detection of the focus lens group FL and the zoom lens group ZL. The error between the target position given by the operation signal and the position where the focus lens group FL or the zoom lens group ZL is actually set is mainly caused by a mechanical error. small. For this reason, the error in the optical conditions related to the focus and zoom between the lens apparatus 10A and the lens apparatus 10B is small, and the variation in the left and right images (difference in the angle of view and focus accuracy) due to the error is also small to the extent that a sense of incongruity does not occur.

  Next, responsiveness control of the focus lens group FL and the zoom lens group ZL will be described. As described above, the focus motor FM is driven to achieve the target value (target position) given by the focus operation signal, thereby the focus lens. When the group FL is moved, or when the zoom lens group ZL is moved by driving the zoom motor ZM so that the target value (target position) given by the zoom operation signal is obtained, the CPU 20 determines the gradient with respect to the moving direction. Accordingly, the responsiveness of the focus lens group FL and the zoom lens group ZL is changed.

  The responsiveness is changed by changing the error amplification factor described above. The error amplification factor is a coefficient value multiplied by the deviation between the target value and the control amount when the value of the drive signal given to the focus amplifier FA or the zoom amplifier ZA is obtained as described above. The larger the value, the more the focus motor FM. In addition, the response of the zoom motor ZM increases.

  On the other hand, the gradient in the moving direction of the focus lens group FL and the zoom lens group ZL is determined by the lens attitude selected by the lens attitude switch 32 that is switched by the operator (the attitude of the lens device 10A), the focus lens group FL, This is determined by the direction of movement of the zoom lens group ZL. In the present embodiment, the lens posture is divided into three modes of horizontal, upward, and downward depending on the direction when the front end side is viewed from the rear end side of the lens apparatus 10A, and any of the lens postures is selected by the lens posture switch 32. It is like that. When the lens attitude is selected to be horizontal by the lens attitude switch 32, it is determined that there is no gradient in the movement direction, that is, a horizontal state regardless of the movement direction of the focus lens group FL and the zoom lens group ZL. When the lens posture switch 32 selects the upward or downward lens posture, whether the gradient of the moving direction is upward or downward is determined according to the moving direction of the focus lens group FL or the zoom lens group ZL. For example, when the lens posture is upward, when the focus lens group FL is moved forward, the gradient in the movement direction is determined as upward, and when the focus lens group FL is moved backward, the gradient in the movement direction is determined. Is considered downward.

  When the CPU 20 determines that the gradient in the moving direction of the focus lens group FL or the zoom lens group ZL is upward as a result of such determination, the CPU 20 sets the error amplification factor to a larger value than in the horizontal state. The responsiveness of the motor FM and the zoom motor ZM is increased.

  On the other hand, when it is determined that the gradient in the moving direction of the focus lens group FL or the zoom lens group ZL is downward, the error amplification factor is set to a smaller value than in the horizontal state, so that the focus motor FM and the zoom motor ZM Reduce responsiveness. The error amplification factor for focus control and the error amplification factor for zoom control are individually set to appropriate values.

  Thus, by changing the responsiveness of the focus lens group FL and the zoom lens group ZL according to the gradient in the movement direction, stable operation can be ensured regardless of the gradient in the movement direction. During the movement of the zoom lens group ZL, a problem that an error occurs between the positions of the lens device 10A and the lens device 10B is prevented.

  The lens posture may be automatically detected by a sensor instead of being designated by an operator using a switch such as the lens posture switch 32 or a trimmer. Further, the responsiveness may be changed by a method other than the method of changing the error amplification factor. For example, the feedback amount such as the speed may be changed. The speed feedback may use a tachometer generator (not shown) or may be obtained by differentiating the output of the position detector (encoder). Furthermore, the responsiveness is not limited to the case where the gradient in the moving direction is changed in three modes: horizontal, upward, and downward, and the degree of gradient in the moving direction can be detected in more detail, and the responsiveness can be changed accordingly. It is also possible to make it possible to change the height.

  Next, the control of the aperture I (aperture control) will be described. Although not shown in the drawing, the lens device 10A (and the lens device 10B) is given an iris operation signal from the camera body, and the iris operation signal is A. It is read by the CPU 20 via the / D converter 30. The value of the iris operation signal indicates the value of the target position (aperture) at which the aperture I should be set.

  On the other hand, the control of the diaphragm I is performed by open loop control without detecting the position of the diaphragm I by the sensor, and the CPU 20 gives a drive signal to the diaphragm amplifier IA via the D / A converter 22. Accordingly, the aperture motor IM is driven, and the aperture I can be set to a desired position by controlling the drive amount of the aperture motor IM. It should be noted that the position of the diaphragm I may be detected by an encoder or the like as in the focus lens group FL and the position may be controlled by feedback control.

  Further, when the iris correction is enabled by the iris correction switch 34, the CPU 20 corrects the value of the target position given by the iris operation signal, and sets the aperture I to the target position of the corrected value. That is, in the case of a diaphragm, mechanical variation is large, and it is difficult to make a difference in manufacturing especially when the F number is high (when the aperture is small). Therefore, when the aperture I in the lens device 10A and the aperture I in the lens device 10B are set to the same target position given by the iris control signal, the aperture I actually set in each lens device 10A, 10B. There may be a difference in position, and the brightness of the left and right images may differ greatly.

  Therefore, the position of the aperture I is corrected by correcting the position of the aperture I by correcting the value of the target position given by the iris operation signal and setting the aperture I to the target position of the corrected value. Exactly matches the target position given by the iris operation signal. By performing such correction in both the lens apparatus 10A and the lens apparatus 10B, the position of the diaphragm I that is actually set in the lens apparatus 10A and the lens apparatus 10B completely coincides.

  The correction amount for the value of the target position given by the iris operation signal can be obtained by the following method. For example, without correcting the target position value of the iris operation signal, the position of the aperture I is set accordingly, and the brightness of the image when a subject having a predetermined brightness is photographed is detected by signal analysis of the image signal. To do. Then, the value of the target position of the iris operation signal is changed so that the brightness becomes the brightness that should be originally obtained with respect to the value of the target position at that time of the iris operation signal. At this time, the change amount of the value becomes the correction amount with respect to the value of the target position before the change. By performing such work by changing the value of the target position of the iris operation signal, the correction amount for the value is measured at all the target positions. In this way, the correction amount is measured in advance and stored as correction data in the EEPROM 36 that can be referred to by the CPU 20, whereby correction can be performed during actual control.

  The iris correction as described above can be enabled or disabled by switching on / off the iris correction switch 34, and the CPU 20 performs the above operation when the iris correction switch 34 is turned on. When the correction is performed and the lens is turned off, the above correction is not performed, and the aperture I is set to the target position given by the iris operation signal.

  Even if the value of the target position of the iris operation signal is different from the planned position, the position of the stop I of the lens apparatus 10B at the position of the stop I of the lens apparatus 10A In this case, the aperture I set in the other lens device with respect to the value of the target position of the iris operation signal in one of the lens devices 10A and 10B. You may make it correct | amend so that it may correspond with a position.

  The iris correction is not limited to correcting the target position value given by the iris operation signal, but can be performed by gain correction in the camera body, and the position of the iris I is detected by a sensor. When the position of the diaphragm I is feedback controlled, it can also be performed by correcting the signal of the current position detected by the sensor.

  Further, for the iris correction, a correction amount may be stored separately depending on the operation direction.

  Next, a processing procedure of a series of processes of the CPU 20 in the lens device 10A and the lens device 10B will be described with reference to a flowchart of FIG. First, the CPU 20 reads the state of the lens attitude switch 32 (step S10). First, it is determined whether the lens posture is horizontal based on the switch state (step S12). When it determines with YES, a response characteristic is set horizontally (step S14). That is, the gradient in the moving direction of the focus lens group FL and the zoom lens group ZL is horizontal regardless of the moving direction, and the responsiveness is set to a standard state by setting the error amplification factor to a standard constant value (standard value). Set.

  If NO is determined in step S12, it is subsequently determined whether or not the lens posture is downward based on the switch state of the lens posture switch 32 (step S16). When it determines with YES, a response characteristic is set downward (step S18). That is, when the movement direction of the focus lens group FL and the zoom lens group ZL is forward, the gradient of the movement direction is downward, and the error amplification factor is set to a value smaller than the standard value, resulting in low responsiveness. Thus, when the movement direction of the focus lens group FL or the zoom lens group ZL is backward, the gradient of the movement direction is upward, and the error amplification factor is set to a value larger than the standard value, and the responsiveness is increased. Try to be high.

  If NO is determined in step S16, that is, if the lens posture is upward, the response characteristic is set upward (step S20). That is, when the movement direction of the focus lens group FL or the zoom lens group ZL is forward, the gradient of the movement direction is upward, and the error amplification factor is set to a value larger than the standard value to increase responsiveness. Thus, when the movement direction of the focus lens group FL or the zoom lens group ZL is backward, the gradient of the movement direction is downward, and the error amplification factor is set to a value smaller than the standard value, so that the responsiveness is Try to lower.

  When the response characteristics are set in step S14, step S18, or step S20, the CPU 20 continues with the zoom operation signal output from the zoom controller 28, the focus operation signal output from the focus controller 26, and the camera body. The output iris operation signal is read in order (steps S22, S24, S26).

  Next, the CPU 20 reads the state of the iris correction switch 34 (step S28), and determines whether to enable the iris correction based on the switch state (step S30). If YES is determined, the correction data is read from the EEPROM 36 as described above, and the value of the iris operation signal read in step S28 is corrected (step S32). If NO is determined, the correction in step S32 is not performed.

  Subsequently, the CPU 20 controls the focus lens group FL, the zoom lens group ZL, and the aperture I based on each operation signal read in steps S22 to S26 or the value corrected in step S32 (step S34). . In the control of the focus lens group FL and the zoom lens group ZL, the error amplification factor is changed in consideration of the response characteristic set in step S14, S18, or S20. When the above process ends, the process returns to step S10.

  As described above, in the above-described embodiment, the encoder is used as the position detection unit of the focus lens group FL and the zoom lens group ZL. However, not only the focus lens group FL and the zoom lens group ZL but also a lens group that requires position detection. In some cases, it is preferable to use an encoder as the position detecting means.

  In the above embodiment, the lens system in the case where the lens device 10A and the lens device 10B independently control each optical system by the control unit has been described. However, one control unit controls each optical system. The present invention can be applied to such a lens system.

FIG. 1 is a block diagram showing a configuration of a stereoscopic camera lens system according to the present invention. FIG. 2 is a flowchart showing a processing procedure in the CPU in each lens apparatus.

Explanation of symbols

10A, 10B ... Lens device, 20 ... CPU, 24 ... Counter, 26 ... Focus controller, 28 ... Zoom controller, FL ... Focus lens group, ZL ... Zoom lens group, I ... Aperture, FM ... Focus motor, ZM ... Zoom motor , FE, ZE ... encoder

Claims (5)

In a stereoscopic camera lens system including a plurality of optical systems of a stereoscopic camera that captures a stereoscopic image and a control unit that controls the plurality of optical systems,
Each of the optical systems includes a lens group that is movable in the optical axis direction, and the control unit uses an encoder as a position detection unit that detects the position of the lens group.   Each optical system includes a diaphragm, and the control unit corrects a position designated by an operation signal given from the outside, and sets the position of the diaphragm of each optical system to the corrected position. 3. The stereoscopic camera lens system according to claim 1, wherein the conditions regarding the aperture of each optical system are matched.   The control unit moves the lens group by a motor based on an operation signal given from the outside, and changes the responsiveness of the lens group to the operation signal according to a gradient in the movement direction. The lens system for a stereoscopic camera according to claim 1 or 2.   4. The stereoscopic camera lens system according to claim 1, wherein the lens group is a focus lens group and / or a zoom lens group. The three-dimensional camera lens system according to claim 1, wherein the control unit includes a plurality of control units for each of the optical systems.

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