JPH0545567A - Lens driving controler for camera - Google Patents

Abstract

PURPOSE:To increase the speed for focusing by stopping driving a focus adjusting lens while a power varying lens is put in high-speed zooming operation and driving the focus adjusting lens to an in-focus position from a zooming end point of time. CONSTITUTION:A microcomputer 119 sends control signals corresponding to respective modes selected with a changeover switch 122 to a zooming waveform selecting circuit 120. The zooming waveform selecting circuit 120 sends driving pulses of the driving direction and speed of a zoom lens 102 corresponding to the control signals from the microcomputer 119 to a zooming actuator 107 through a zooming driver 110 to drive the zoom lens 102. Namely, a focus lens 105 is driven to an in-focus position from the high-speed lens end point of time of the focus lens 102 by a focusing actuator 109 in response to switching to the high-speed zooming of a zoom power varying lens 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens drive control device for a camera such as a video camera, and more particularly to a drive control device for a focus adjustment lens when zooming a variable power lens in a camera provided with a rear focus lens system. It is related to.

[0002]

2. Description of the Related Art Generally, in a conventional front focus lens system for a video camera, when performing a zoom operation of a variable power lens (hereinafter referred to as a zoom lens), there is only one focusing locus, The zoom drive can be performed at high speed without any fear of defocusing the focus adjustment lens (hereinafter referred to as the focus lens) by either manual or electric operation. On the other hand, in the rear focus lens system, Similarly, when the zoom operation of the zoom lens is performed, since the focus locus differs depending on the subject distance, the focus lens is mostly driven only by the electric operation.

FIG. 4 shows a relationship between a focus position and a zoom position with respect to a certain object distance, and a relationship between a focus locus and an autofocus locus during high-speed zoom in a video camera using a general rear focus lens system. Show. In FIG. 4, in this case, it is assumed that the focus is at the point A, and in this state, the zoom position is changed from the AZ point to the BZ point.
By performing zoom drive of the zoom lens up to the point, the focus position is reached from the AF point to the BF point on the focusing locus.

As the actuator for driving the focus lens, a stepping motor capable of pulse drive control is often used in addition to the DC motor. In this stepping motor, the driving sound is large, so that the motor is driven. As the pulse voltage waveform input to
In some cases, a microstep wave (similarly, waveform B in FIG. 2) is input instead of a normal rectangular wave (waveform A in FIG. 2 described later).

In the case of a video camera using this conventional rear focus lens system, when high-speed zoom driving of the zoom lens is performed, the focus motor is simultaneously driven at high speed in response to this, and the focus lens is brought into focus on the focus locus. I am trying to follow the focal position.

[0006]

However, when the focus actuator is driven by the micro step wave input as described above when the focus lens is driven to follow the high-speed zoom of the zoom lens, the focus actuator is Even if the frequency of the micro step wave is increased in order to increase the driving speed, the rotational torque is relatively small and a sufficient driving speed cannot be obtained.
In the above, the focus lens, which originally has to reach the point B due to the zooming operation, can only reach the point B _{2 due} to the drive locus 1 ₂ which greatly deviates from the normal focusing locus, or the drive is impossible. As a result, step out occurs, and accurate tracking becomes impossible, and as a result, the focus lens moves to a position far from the focal point. Furthermore, after that, in order to make the focus lens reach the correct point B from this moving position B ₂ point and focus,
There is an inconvenience that a wasteful time is required, and an image is taken while the drive locus itself is out of the focus locus, resulting in a large blur in the image.

[0007] Thisゝa, when the high-speed zooming, when to drive the zoom lens from one end to the other (corresponding to the locus 1 ₁ of FIG. 3), when the focus position of the focus lens is virtually unchanged However, even in this case, if the focus lens is driven to follow the in-focus locus as described above, the focus lens deviates from the in-focus point at the time when the zoom lens is stopped, and the image is captured. The image may be blurred.

The present invention has been made in order to solve such a conventional problem, and an object thereof is to drive a focus lens to a focal point corresponding to a high speed zoom of the zoom lens. It is an object of the present invention to provide a lens drive control device for a camera, which is capable of quickly performing an image without causing a large blur, and particularly a lens drive control device for a camera using a rear focus lens system of a video camera.

[0009]

In order to achieve the above object, the invention of claim 1 provides a variable power lens, a zoom actuator for driving the variable power lens, and a drive power supply to the zoom actuator. A zoom driver, a focus adjustment lens, a focus actuator that drives the focus adjustment lens, a focus driver that supplies drive power to the focus actuator, and a zoom speed of the variable power lens that is at least the normal zoom speed. , A zoom operation means for selecting from two quick zoom speeds,
Lens drive of camera provided with focus operating means for changing drive speed of the focus adjusting lens according to zoom speed of the variable power lens, and control means for supplying drive power to each driver and controlling polarity In the control device,
A means for stopping the drive of the focus adjusting lens by the focus lens operating means when the zoom lens is performing high speed zooming, and driving the focus adjusting lens to the in-focus position from the end of the high speed zoom of the zoom lens. And a lens drive control device for a camera.

Further, the invention of claim 2 is characterized in that the focusing lens is driven at a high speed to the in-focus position from the end of the high speed zooming of the zoom lens.

[0011]

Therefore, in the lens drive control device of the camera of the present invention, when the zoom lens is being zoomed at high speed, the driving of the focus adjusting lens is stopped by the focusing operation means to drive the zoom lens at high speed. From the end point, the focus adjustment lens is driven to the in-focus position. Therefore, the focus adjustment lens is appropriately driven to correspond to the high-speed zoom of the variable power lens.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a lens drive control device for a camera according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of a lens drive control device for a camera using a rear focus lens system according to an embodiment of the present invention.

In the apparatus configuration shown in FIG. 1, 101
Is a first group fixed lens, 102 is a zoom lens, 103 is an aperture, 104 is a third group fixed lens, 105 is a focus lens that serves both as a focus and a compensator,
Reference numeral 106 is an image pickup device such as a CCD.

Further, 107 is a zoom actuator (DC motor) for driving the zoom lens 102, 108 is a diaphragm actuator for driving the diaphragm 103, 109 is a focusing actuator for driving the focus lens 105, and 110 is for zooming. Actuator 10
7, a zoom driver for supplying drive power to 7, a diaphragm driver 111 for supplying drive power to the diaphragm actuator 108, and 112 for the focus actuator 1
09 is a focus driver that supplies drive power to 09, 113 is a zoom encoder that detects the drive position and zoom state of the zoom lens 102, and 114 is the diaphragm 10.
A diaphragm encoder that detects the opening degree of 3 and a focus encoder 115 that detects the drive position of the focus lens 105.

Further, 116 is an amplifier of the image pickup device 106, 117 is an image signal processing circuit of the same as above, 118 is a comparator (aperture difference detector) for the aperture driver 111, and 119 is a microcomputer for controlling the entire apparatus. Reference numerals 120 and 121 denote zoom and focus waveform selection circuits for switching and selecting drive power signal waveforms for the zoom actuator 107 and the focus actuator 109, and 122 denotes T in the zoom operation.
These are changeover switches for selecting the ELE, WIDE, and high speed modes.

In the structure of the present embodiment described above, the zoom driver 110 is used to drive the zoom actuator 10
When the zoom lens 102 is driven and controlled via the focus lens 105, the focus lens 105 also functions as a compensator. Therefore, the focus driver 110 needs to drive the focus lens 105 via the actuator 107 on a locus for keeping focus. is there.

Therefore, in the case of this embodiment, the microcomputer 119 sends a control signal corresponding to each mode selected by the changeover switch 122 to the zoom waveform selection circuit 120. The control signal includes a waveform selection signal component according to the driving speed of the zoom lens 102 in each mode. The zoom waveform selection circuit 120 sends to the zoom actuator 107 via the zoom driver 110
The zoom lens 102 is driven by sending drive pulses of the driving direction and speed of the zoom lens 102 according to the control signal from the microcomputer 119.

Further, the microcomputer 119 calculates the focus drive locus of the focus lens 105 according to the driving position of the zoom lens 102 detected by the zoom encoder 113, and focuses the control signal according to the calculated locus. To the dedicated waveform selection circuit 121. The control signal includes a waveform selection signal component corresponding to each mode selected by the changeover switch 122. The focus waveform selection circuit 121 sends a pulse signal of a waveform having an appropriate drive direction and speed of the focus lens 105 according to a control signal from the microcomputer 119 to the focus actuator 109 via the focus driver 112. , By this, the focus lens 10
5 is driven to enable the focus lens 105 to be driven to the in-focus point by a locus that is close to the driving locus of the zoom lens 102.

That is, in this embodiment, when the focusing actuator 109 is a stepping motor, the waveform of the input drive pulse is changed to a microstep wave (waveform B in FIG. 2) or a rectangular wave (see FIG. 2) depending on the drive speed. 2 A waveform), and in the case of a DC motor, in addition to the duty of the input rectangular wave, a rectangular wave with a limited peak value (C waveform in FIG. 2) and the peak value It is arranged to switch to the raised rectangular wave (D waveform in FIG. 2). Then, when the high speed mode is selected by the changeover switch 122, the waveform of the input drive pulse to the focusing actuator 109 is changed to A or D in FIG.
By switching to a rectangular wave, the rotational torque of the focusing actuator 109 is increased, the focusing speed is increased, and high-speed zooming is performed. When the focusing actuator 109 is a DC motor, a DC voltage may be used as the driving power of the focusing actuator 109 instead of the duty control of the driving pulse and the switching of the peak value of the rectangular wave. In this case, the voltage value of the DC voltage is increased during high-speed zoom.

On the other hand, as described above, when the zoom lens 102 is driven at high speed from one end to the other end by the zoom actuator 107, the focus lens 105 does not necessarily have to be driven at high speed. There are cases (corresponding to the trajectory 1 ₁ in FIG. 4).

Therefore, in this embodiment, first, when the high speed mode is selected by the changeover switch 122,
The zoom lens 10 is driven by the zoom actuator 107.
Microcomputer 1 while zooming 2 at high speed
The drive of the focus lens 105 is once stopped under the control of the zoom lens 19 and then the zoom lens 10
From the time when the zoom encoder 113 detects the end of the high-speed zoom of 2, the focus actuator 1 is controlled by the microcomputer 119.
The input drive pulse waveform for 09 is switched to drive the focus lens 105 at a high speed to bring the focus into focus. In this way, the amount of blur is minimized without causing the resulting image to be greatly blurred. The focusing speed can be increased in the suppressed state.

Next, an operation example of this embodiment will be described with reference to the flowchart of FIG. Note that this operation example is a case where the high-speed zoom operation is performed only when the recording state is not set.

In step S1, when the high speed mode is selected by the changeover switch 122 and the high speed zoom of the video camera is started, in step S2,
It is confirmed whether or not it is in the recording pause state, and if the recording is not performed, only the zoom lens 102 is shifted to the high speed zoom drive in step S3, and after confirmation of the end of the high speed drive in step S4. In step S5, it is confirmed whether or not focus is achieved at the end of the high-speed drive. At this time, if focus is achieved, the focus is ended as it is. If not, in step S6, the blur amount is determined. The focus lens 105 is driven at a high speed in accordance with the above, and the focusing speed is increased to end the processing. If the recording is being performed in step S2, the zoom lens 102 and the focus lens 105 are both driven at the normal speed without shifting to the high-speed zoom state in step S7.

Therefore, in this operation example, during the recording of the video camera, the recording can be continued in the low noise state, and at the time of non-recording, the driving torque is increased to increase the zoom speed of the zoom lens as necessary. Then, by driving the focus lens at a high speed thereafter, it is possible to easily perform image pickup while avoiding large blurring of the image as much as possible.

In the above-mentioned embodiment, the example in which the video camera is applied as the camera has been described, but the present invention can also be applied to a camera for a photographing device using film.

[0027]

As described above in detail with reference to the embodiments,
According to the present invention, when the zoom lens is performing high-speed zooming, the driving of the focus adjusting lens is stopped by the focusing operation means, and the focus adjusting lens is brought into focus from the end of the high-speed zooming of the zoom lens. Since the means for driving to the position is provided, it is necessary to stop the drive of the focus adjustment lens at the time of high speed zooming of the variable power lens, and to drive the focus adjustment lens to the in-focus position at the end of the high speed zoom of this variable power lens. Focusing can be performed quickly and easily regardless of the position where the zoom lens is driven at high speed. In addition, since only the high-speed zoom drive of the variable-magnification lens drives the focus adjustment lens to the in-focus point according to the amount of blur, the focusing speed can be increased and the blur of the captured image during high-speed zoom etc. The excellent effect of being able to prevent

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of a lens drive control device for a camera using a rear focus lens system according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing drive pulses output to a focusing actuator.

FIG. 3 is a flowchart showing an operation example of the above embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a focus position and a zoom position with respect to a general subject distance in a rear focus lens system of a video camera, and a relationship between a focus locus and an autofocus locus during high-speed zoom. is there.

[Explanation of symbols]

 102 Zoom Lens 105 Focus Lens 106 Image Sensor 107 Zoom Actuator 109 Focus Actuator 110 Zoom Driver 112 Focus Driver 113 Zoom Encoder 119 Microcomputer 120 Zoom Waveform Selection Circuit 121 Focus Waveform Selection Circuit 122 Changeover Switch

Claims (2)

[Claims] 1. A variable power lens, a zoom actuator for driving the variable power lens, a zoom driver for supplying driving power to the zoom actuator, a focus adjustment lens, and a focus for driving the focus adjustment lens. Actuator, a focusing driver that supplies driving power to the focusing actuator, a zoom operation unit that selects the zoom speed of the variable power lens from at least a normal zoom speed and a rapid zoom speed, and the zoom ratio. A lens drive control device for a camera, comprising: a focus operation means for changing the drive speed of the focus adjustment lens according to the zoom speed of the lens; and a control means for supplying drive power to each driver and controlling the polarity. When the high-speed zoom of the variable power lens is being performed, the focus lens operator's hand A lens drive control device for a camera, comprising means for stopping the drive of the focus adjustment lens according to the number of steps and driving the focus adjustment lens to the in-focus position from the end of high-speed zooming of the zoom lens. 2. The lens drive control device for a camera according to claim 1, wherein the focus adjusting lens is driven to a focusing position at a high speed from the end of the high speed zooming of the zoom lens.