JP4478238B2 - Zoom lens, zoom lens system and camera system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens used in a television camera or the like.
[0002]
[Prior art]
By controlling the zoom part of the zoom lens and moving the lens position, the shooting angle of view can be increased or decreased, but when the focus part is controlled, the angle of view also changes by moving the lens position. End up. That is, even if a desired angle of view is set by the zoom unit, the set angle of view varies due to control of the focus unit. For this reason, there has been proposed a zoom lens having a so-called angle-of-view variation correction function for controlling the zoom unit so that the angle-of-view variation does not occur when the focus unit is controlled.
[0003]
FIG. 3 shows a flowchart of a zoom operation including an angle of view correction operation in a zoom lens that controls the position of the lens. In this zoom lens, data is input from the zoom demand or focus demand (steps 53 and 54), and when there is data input from the focus demand, a zoom command position for correcting the angle of view is calculated (step). 58, 61). Based on the calculation result, a motor for driving the zoom unit is driven (step 62).
[0004]
Incidentally, some zoom lenses have a function (so-called tracking function) for limiting the drive range of the zoom unit. With zoom lenses that are becoming wider and higher in magnification year by year, when the zoom unit is set to the wide side, even people around the subject (the subject you want to shoot) that you do not want to shoot enter the screen, while the zoom unit When set to the end, the subject may be enlarged so as not to fit on the screen. In such a situation, the lens operator always needs to finely adjust the zoom stop positions on the wide side and the tele side according to the zoom demand.
[0005]
Therefore, by restricting the drive range of the zoom unit and shooting only the subject you want to shoot at the wide end without fine adjustments due to zoom demand, you can capture a video where the entire image of the subject is exactly within the screen at the tele end. A tracking function for enabling photographing is useful.
[0006]
[Problems to be solved by the invention]
When such a tracking function works and the angle of view fluctuation correction function is set to work, when the focus demand is operated when the zoom unit is near the end point of the driving range restricted by the tracking function, There are cases where the zoom position command calculated and corrected from the drive positions of the focus section and zoom section exceeds the limited drive range.
[0007]
In such a case, if zoom driving for field angle fluctuation correction is limited at the end point of the limited driving range, only control of the focus unit is continued thereafter, and the field angle suddenly changes. Become. Thus, in a zoom lens that has both a zoom drive range limiting function and an angle of view fluctuation correction function, when these two functions are working at the same time, the two functions cancel each other's effects, and the lens becomes an operator. May operate unintentionally.
[0008]
Accordingly, an object of the present invention is to provide a zoom lens that can maintain a constant angle of view even when focus control is performed in the vicinity of an end point of a limited driving range of a zoom unit.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, in a zoom lens including a setting unit that sets a drive allowable end of a zoom unit, and a control unit that performs drive control of the zoom unit and the focus unit, In a state in which the drive allowable end is set, the control means, when the drive position of the zoom unit for correcting the view angle variation accompanying the drive of the focus unit exceeds the drive allowable end, The zoom unit is driven to a position, and the setting means sets the drive allowable end in accordance with a user operation .
[0011]
The first aspect of the present invention, in a case where a so-called tracking and angle variation correction function of the zoom unit is working together, the focus unit is controlled in the vicinity of the driving allowable end by tracking, for angle variation correction Accordingly zoom portion when such has to be driven beyond the drive allowable end, since the driving of such a zoom unit is permitted, it is possible to keep the angle constant at.
[0012]
In consideration of the case where it is necessary to drive the zoom unit to correct the angle of view fluctuation within the drive allowable end for zooming, the second aspect of the present invention provides a correction for the angle of view variation of the zoom unit. It is possible to selectively operate in a first mode in which drive control is performed regardless of the drive allowable end, and a second mode in which the drive position for correcting the angle of view of the zoom unit is also limited to within the drive allowable end. Yes.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration of a zoom lens 101 according to an embodiment of the present invention. Reference numeral 4 denotes a CPU (control means), to which a zoom demand 1 and a focus demand 2 are connected. From the zoom demand 1, zoom speed data (zoom operation information) corresponding to the operation speed and zoom tracking limit data for limiting the drive allowable range for zooming of the zoom unit Z are input to the CPU 4. Further, focus control data (focus operation information) corresponding to the operation amount is input from the focus demand 2. In addition, an angle-of-view correction priority mode setting switch 3 is connected to the CPU 4. When this angle of view correction priority mode setting switch 3 is ON, priority is given to the angle of view fluctuation correction function over the tracking function (first mode), and when this is OFF, the tracking function is prioritized over the angle of view fluctuation correction function. (Second mode).
[0014]
One of the outputs of the CPU 4 is connected to a motor 7 that drives a lens constituting the zoom unit Z via an amplifier 5. The zoom unit Z is provided with a position detector 8 that detects the absolute position of the lens. The position detector 8 is connected to the CPU 4.
[0015]
The other output of the CPU 4 is connected to a motor 12 that drives a lens constituting the focus unit F via an amplifier 6. The focus unit F is provided with a position detector 13 that detects the absolute position of the lens. The position detector 13 is connected to the CPU 4.
[0016]
The other output of the CPU 4 is connected to the television camera 103 via the D / A converter 17. Accordingly, follow signals indicating various states of the zoom lens 101 such as zoom follow data indicating the lens position of the zoom unit Z and iris follow data indicating the aperture value of an aperture device (not shown) are communicated to the camera 103. .
[0017]
The CPU 4 is connected to a non-volatile memory 18 that stores data for angle-of-view correction calculation. Here, data for field angle correction calculation will be briefly described.
[0018]
The driving range of the lens of the zoom unit Z is divided into an arbitrary number n in advance, and the driving range of the lens of the focus unit F is also divided into an arbitrary number m in the same manner, and output pulses are generated in the position detectors 8 and 13. Each output data of the counter to be measured is calculated. In addition, the angle of view at the zoom i-th division point and the focus j-th division point is obtained by optical calculation. Similarly, the zoom i, the focus j + 1-th division point, the zoom i + 1, and the focus j. The angle of view at the i-th division point, the zoom i + 1, and the focus j + 1-th division point is obtained by optical calculation, and the lens position (hereinafter referred to as the zoom position) of the zoom unit Z in the area surrounded by these four points. ), The relationship between the lens position of the focus portion F (hereinafter referred to as the focus position) and the angle of view is approximated by a plane equation including three of the four points. By applying this approximate plane equation, the angle of view can be expressed by the function (1) using the zoom position and the focus position as variables.
[0019]
ω = Cz × Pz + Cf × Pf + D (1)
Here, ω represents the size of the angle of view, Cz is a coefficient for the zoom position of the approximate plane, Pz is the zoom position, Cf is a coefficient for the focus position of the approximate plane, Pf is the focus position, and D is a constant term of the approximate plane. Represents.
[0020]
The coefficients Cz, Cf, and D of the approximate plane equation for which the relationship between the zoom position, the focus position, and the angle of view is obtained in this way are mapped and stored in the memory 18.
[0021]
The flowchart in FIG. 2 shows a series of operations in the zoom lens. The CPU 4 proceeds to step 1 immediately after the power is turned on, and initializes the inside of the CPU 4. In addition, the lens constituting the zoom unit Z is initialized using the output from the position detector 8 and the lens constituting the focus unit F is initialized using the output from the position detector 13 .
[0022]
Next, in step 2, communication with the zoom demand 1 and the focus demand 2 is initialized. Here, the initialization operation is terminated, and a normal operation for controlling the zoom unit Z and the focus unit F in accordance with the outputs from the zoom demand 1 and the focus demand 2 is started.
[0023]
First, the normalized zoom speed data Zspeed is input from the zoom demand 1 in step 3, and the normalized focus control data Fdata is input from the focus demand 2 in step 4.
[0024]
Next, zoom tracking limit data is input from zoom demand 1 in step 5, zoom speed data input from zoom demand 1 is integrated in step 6 using equation (2), and normalized zoom position data Zdata is obtained. Calculate.
[0025]
Zdata = Zbuf + K × Zspeed (2)
Zbuf: Zoom position data at the time of pre-sampling K: Arbitrary integration constant Further, in step 7, the output from the view angle correction priority switch 3 is fetched, and in step 8, the state of the view angle correction priority mode setting switch 3 is determined. If the angle-of-view correction priority mode setting switch 3 is ON, the angle-of-view correction priority flag is set in step 9A, and the process proceeds to step 10. On the other hand, if the view angle correction priority mode setting switch 3 is OFF in step 8, the view angle correction priority flag is cleared in step 9B, and the process proceeds to step 10.
[0026]
In step 10, a field angle correction priority flag is determined. When the field angle correction priority flag is set, the mode in which the field angle variation correction function is prioritized over the tracking function is entered.
[0027]
In this angle of view correction priority mode, in step 11A, the angle of view correction calculation is performed using the zoom position data Zdata and the focus control data Fdata input from the focus demand 2, and the zoom position command is calculated.
[0028]
Here, the angle-of-view correction calculation will be briefly described. First, using the expression (3), the normalized focus position data Fdata is converted into a focus position command Focus corresponding to the output of the counter in the position detector 13.
[0029]
Focus = Far + Fdata / NOM × (Near−Far) (3)
Far: Infinite end focus command Near: Nearest end focus position command NOM: Maximum value of normalized focus position data Next, an approximate plane equation corresponding to a region including the value of the counter in the position detectors 8 and 13 Coefficients are input from the memory 18. Then, the input coefficient is substituted for Cz, Cf, D in the equation (1), the value of the counter in the position detector 8 is substituted for Pz, and the value of the counter in the position detector 13 is substituted for Pf. ωorg is calculated.
[0030]
Next, the value of the counter in the position detector 8 and the coefficient of the approximate plane equation corresponding to the area including the focus position command Focus are input from the memory 18. Then, the input coefficients Cz ′, Cf ′, D ′, the reference angle of view ωorg, and the focus position command Focus are substituted into the equation (4), and the zoom position command Zoom corresponding to the output of the counter in the position detector 8 is obtained. Calculate.
[0031]
Zoom = (ωorg−Cf ′ × Focus−D ′) / Cz ′ (4)
After performing the angle of view correction calculation in this way, the process proceeds to step 14, and the zoom position control calculation is performed using the zoom position command Zoom after the correction calculation and the counter value in the position detector 8, and the process proceeds to step 15. The calculation result of step 14 is output to the amplifier 5 to drive the motor 7.
[0032]
Thus, for example, even when the zoom position command for correcting the view angle fluctuation exceeds the tracking limit data, the zoom position command is not limited by the tracking limit data, and the zoom position is zoomed for correcting the view angle fluctuation. The zoom unit Z is driven until the position corresponding to the position command is reached, and the angle of view is kept constant. Therefore, it is possible to prevent the angle of view from being suddenly fluctuated because the angle of view correction function does not work at the tracking limit point.
[0033]
On the other hand, if the angle of view correction priority flag is cleared in step 10, the mode in which the tracking function is prioritized over the angle of view fluctuation correction function is entered.
[0034]
In this tracking limit priority mode, in step 11B, using the zoom position data Zdata and the focus control data Fdata input from the focus demand 2, a field angle correction calculation is performed, and a zoom position command is calculated. The angle-of-view correction calculation here is the same as the angle-of-view correction calculation in step 11A.
[0035]
Then, in step 12, the zoom position command after the correction calculation exceeds the limit data on the tele side in the tracking limit data and further on the tele side, exceeds the limit data on the wide side, and further on the wide side or the tele side limit. Judge whether it is within the range of data and wide side limit data.
[0036]
If the tele-side tracking limit data is exceeded, the process proceeds to step 13A, the zoom position command is limited by the tele-side tracking limit data, and the process proceeds to step 14. If the wide side tracking limit data is exceeded, the process proceeds to step 13B, the zoom position command is limited by the wide side tracking limit data, and the process proceeds to step 14. If it is within the range of the tele-side limit data and the wide-side limit data, the process proceeds to step 14 as it is.
[0037]
Then, the zoom position command limited in Steps 13A and 13B or the zoom position command that is valid as it is within the range of the tele limit data and the wide limit data and the counter value in the position detector 8 are obtained. Then, the zoom position control calculation is performed, the process proceeds to step 15, the calculation result of step 14 is output to the amplifier 5, and the motor 7 is driven.
[0038]
As described above, in the tracking priority mode, for example, when the zoom position command for correcting the view angle variation exceeds the tracking limit data, the zoom position command is limited by the tracking limit data, and the view angle variation correction is performed. The zoom drive range is limited within the tracking limit range. For this reason, for example, when it is desired to keep the photographing light amount constant, the zooming unit Z is prevented from being reduced further by being driven to the tele side beyond the tracking limit range to correct the angle of view variation on the tele side. be able to.
[0039]
After the motor drive in step 15, steps 3 to 15 are repeatedly executed until the power is turned off.
[0040]
In the above embodiment, the zoom position command is described as tracking limit data, i.e., whether or not the zoom section angle-of-view variation correction control is performed by determining whether or not the zoom section drive allowable end is exceeded. The present invention can also be applied to a case where it is determined whether or not the zoom position command is outside a predetermined drive allowable range and the angle of view fluctuation correction control of the zoom unit is performed.
[0041]
Further, both the tele-side tracking limit data and the wide-side tracking limit data in the above embodiment may be set at an intermediate position between the tele end and the wide end, or one of them may be the tele end or the wide end.
[0042]
In the above embodiment, the zoom lens attached to the television camera has been described. However, the present invention can also be applied to a zoom lens attached to various cameras such as a silver salt camera and a video camera.
[0043]
【The invention's effect】
As described above, according to the first aspect of the invention, when the function and the view angle variation correction function for limiting the driving position for zooming the zoom unit in a predetermined drive allowable end is working together, image since the zoom driving exceeding the driving allowable end for angular variation correction is permitted, by also keeping constant in a reliable manner the angle when the focus unit is controlled in a state where for example a zoom unit is near the drive permissible end can be suddenly angle zoom driving is limited due to the angle variation correction can be prevented a situation that varies.
[0044]
Further, according to the second invention of the present application, the first mode in which the drive control for correcting the angle of view of the zoom unit is performed regardless of the drive allowable end, and the drive position for the correction of the angle of view of the zoom unit are also provided. Since the operation can be selectively performed in the second mode that is limited to within the allowable driving end, it is possible to select an appropriate usage according to conditions such as photographing.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a zoom lens according to an embodiment of the present invention.
FIG. 2 is an operation flowchart of the zoom lens.
FIG. 3 is an operation flowchart of a conventional zoom lens.
[Explanation of symbols]
1 Zoom demand 2 Focus demand 3 Angle correction priority switch 4 CPU
5, 6 Amplifier 7, 15 Motor 8, 13 Position detector 17 D / A converter 18 Non-volatile memory Z Zoom unit F Focus unit

Claims (7)

In a zoom lens having a setting unit that sets a drive allowable end of the zoom unit, and a control unit that performs drive control of the zoom unit and the focus unit,
In the state where the drive allowable end is set, the control means, when the drive position of the zoom unit for correcting the angle of view fluctuation accompanying the drive of the focus unit exceeds the drive allowable end, The zoom unit is driven to the drive position ,
The zoom lens characterized in that the setting means sets the drive allowable end in accordance with a user operation .   The control means includes a first mode for driving the zoom unit beyond the drive allowable end in order to correct the view angle variation in a state where the drive allowable end is set, and the view angle variation. Even when the driving position of the zoom unit for correction exceeds the allowable driving end, the zoom unit selectively operates in the second mode in which the zoom unit is driven to the allowable driving end. The zoom lens according to claim 1.   The zoom lens according to claim 2, further comprising a switch for selectively operating the first and second modes with respect to the control unit. The control means includes
A zoom command information calculation unit for calculating zoom control command information for driving and controlling the zoom unit to a drive position for correcting the angle of view variation;
The drive control part which performs drive control of the said zoom part based on the said drive permissible end set by the said setting means and the said zoom control command information, The control part in any one of Claim 1 to 3 characterized by the above-mentioned. Zoom lens. The zoom command information calculation unit calculates the zoom control command information based on focus command information for driving and controlling the focus unit and information on positions of lenses that respectively constitute the focus unit and the zoom unit. The zoom lens according to claim 4 . Setting means for setting the drive allowable end of the zoom unit according to a user operation;
Control means for performing drive control of the zoom unit and the focus unit ;
An operation device that outputs focus operation information necessary to calculate focus control command information for driving and controlling the focus unit in accordance with a user operation;
An operation device that outputs zoom operation information necessary to calculate zoom control command information for driving and controlling the zoom unit for zooming according to a user operation ;
In the state where the drive allowable end is set, the control means, when the drive position of the zoom unit for correcting the angle of view fluctuation accompanying the drive of the focus unit exceeds the drive allowable end, A zoom lens system comprising driving the zoom unit to a driving position . 7. A camera system comprising: the zoom lens system according to claim 6; and a camera to which the zoom lens is attached.

Images