JPH0545566A - Lens driving controller for camera - Google Patents

Abstract

PURPOSE:To increase the speed for focusing by switching the waveform of a driving electric power signal to a focusing actuator according to the switching of a zoom speed by a zooming operation means. CONSTITUTION:A microcomputer 119 sends a control signal to a waveform selecting circuit 120 according to respective modes selected with a changeover switch 122. This control signal includes a waveform select signal corresponding to a zoom lens driving speed corresponding to each of the modes. Further, the waveform selecting circuit 120 sends driving pulses corresponding to the driving direction and speed of a zoom lens 102 corresponding to the control signal to a zooming actuator 107 through a zooming driver 110 to drive the zoom lens 102. Namely, the waveform of the driving electric power signal to the actuator 109 for the focus lens 105 is switched corresponding to switching to the high-speed zoom driving of the zoom lens 102 and the focus lens 105 is driven at a high speed while following up an in-focus position.

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 pulse drive controlling a zoom lens and a focus lens in a camera provided with a rear focus lens system. Is.

[0002]

2. Description of the Related Art Generally, in a conventional front focus lens system for a video camera, when a zooming operation of a variable power lens (hereinafter referred to as a zoom lens) is performed, there is only one focusing locus, and therefore, a manual operation is required. Alternatively, by either electric operation, zoom drive can be performed at high speed without the fear of defocusing the focus adjustment lens (hereinafter referred to as focus lens). On the other hand, in the rear focus lens system, When the zoom operation of the zoom lens is performed, since the focus locus varies depending on the subject distance, it is almost the case that the focus lens is 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 at the time of high-speed zoom in a video camera using a general rear focus lens system. .. In FIG. 4, in this case, it is assumed that the focus is at the point A, and in this state, by performing zoom drive of the zoom lens from the zoom position Az to the point Bz, the focus position is changed from the AF point to the focus locus. It is assumed that BF point is reached via the above.

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, since the driving sound is large, the motor is This is a case where the micro-step wave (similarly B waveform in FIG. 2) is input as the pulse voltage waveform to be input to, instead of the normal rectangular wave (A waveform in FIG. 2 described later).

[0005]

Generally, in the case of a video camera, the rate of change of the angle of view due to zooming is not necessarily limited to a relatively slow speed during shooting, and for example, during waiting for shooting. And
When you want to quickly drive the focus lens at high speed, for example, when you want to quickly achieve the desired angle of view, the focus actuator is also driven at high speed in response to this, so that the focus lens follows the focus path. Need to let.

In this case, when the focus motor is driven by the micro step wave input as described above, when the frequency of the micro step wave is increased in order to increase the driving speed of the focusing actuator, the rotational torque of the micro step wave is increased. Is relatively small and a sufficient driving speed cannot be obtained, so that the driving speed is limited, and
In the above, the focus lens, which originally has to reach the point B by the zooming operation, can only reach the point B ₂ via the locus 1 ₂ that greatly deviates from the regular driving locus, or because of unreasonable driving. If the focus lens moves to a position far from the in-focus point, the focus lens may move to a position far from the focal point. It takes a wasteful time to reach the normal point B from the point B ₂ and bring it into focus, and while the drive locus itself is out of the in-focus locus, an image is taken and a large blur occurs in the image. There is.

On the other hand, as the focus motor, D
When the C motor is used, even if the motor is pulse-controlled with a rectangular wave input, the driving sound is large as described above. A means for forming a rectangular wave (C waveform in FIG. 2 described later) with a limited crest value is adopted, and due to such a limitation, the rotational torque is also suppressed, and the same drawback is caused. ..

The present invention has been made in order to solve such a conventional problem, and an object thereof is to easily follow a focus lens at high speed in response to high-speed zoom driving of the zoom lens. A lens drive control device for a camera that is driven to increase the speed for focusing.
In particular, it is to provide a lens drive control device using a rear focus lens system of a video camera.

[0009]

In order to achieve the above-mentioned object, the present invention provides a zoom lens, a zoom actuator for driving the zoom lens, and a zoom actuator for supplying drive power to the zoom actuator. The driver, the focus adjustment lens, the focus actuator that drives the focus adjustment lens, the focus driver that supplies drive power to the focus actuator, and the zoom speed of the variable power lens are at least high and low. A zoom operation means for selecting from a speed higher than or equal to, a focus operation means for changing the drive speed of the focus adjustment lens according to the zoom speed of the variable power lens, a drive power supply to each driver, and a polarity control. In the lens drive control device for a camera, the zoom speed by the zoom operation means is provided. Depending on the switching, it is to provide a lens drive control device for a camera, characterized in that it comprises a means for switching the drive power signal waveform to the focus actuator.

[0010]

Therefore, in the lens drive control device of the present invention, the drive power signal waveform for the actuator of the focus lens is switched according to the switching of the zoom lens to the high-speed zoom drive. Corresponding to high-speed zoom driving, the focus lens can be easily made to follow and high-speed driving can be performed, and the focusing speed can be increased.

[0011]

Embodiments of the lens drive control device for a camera according to the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of a lens drive controller 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.

Reference numeral 107 denotes a zoom actuator (DC motor) for driving the zoom lens 102, and 1
Reference numeral 08 denotes a diaphragm actuator that drives the diaphragm 103, 109 denotes a focusing actuator that drives the focus lens 105, 110 denotes a zoom driver that supplies driving power to the zoom actuator 107, and 111 denotes the diaphragm actuator. A diaphragm driver that supplies drive power to 108, a focus driver 112 that supplies drive power to the focus actuator 109, and a zoom lens 10
2 is a zoom encoder that detects the drive position of the second diaphragm, 114 is a diaphragm encoder that detects the opening of the diaphragm 103, and 115 is a diaphragm encoder.
Is a focus encoder 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 controls the entire apparatus. Microcomputers 120 and 121 are the zoom actuator 107 and the focus actuator 109.
, A waveform selection circuit for switching and selecting the drive power signal waveform, 122 is TELE, WIDE in the zoom operation,
And a changeover switch for selecting each mode of high speed.

In the above-described configuration of this embodiment, the zoom driver 110 is used to drive the zoom actuator 10
When the drive control of the zoom lens 102 is performed via the focus lens 105, the focus lens 105 also functions as a compensator, so that it is necessary to drive the focus lens 105 on the locus for keeping the focus.

Therefore, in this embodiment, the microcomputer 119 sends a control signal to the waveform selection circuit 120 according to each mode selected by the changeover switch 122. The control signal includes a waveform selection signal component corresponding to the zoom lens driving speed corresponding to each mode. Waveform selection circuit 12
0 sends a drive pulse corresponding to the drive direction and speed of the zoom lens according to the control signal to the zoom actuator 107 via the zoom driver 110.
Drive 02. Further, the microcomputer 119 determines the focus lens 105 according to the drive position of the zoom lens 102 detected by the zoom encoder 113.
The focus drive locus is calculated and a control signal corresponding to the calculated locus is sent to the focus waveform selection circuit 121. The control signal includes a waveform selection signal component according to each mode selected by the changeover switch 122. The focus waveform selection circuit 121 outputs a pulse signal corresponding to the drive direction and speed of the focus lens having an appropriate waveform to the focus actuator 109 via the focus driver 112 according to a control signal from the microcomputer 119. The focus lens 10
5 is driven to enable the focus lens 105 to be driven to the in-focus point according to the locus which is close to the driving locus of the zoom lens 105.

That is, in the present embodiment, when the focusing actuator 109 is a stepping motor, the waveform of the input drive pulse of the stepping motor is changed to a microstep wave (waveform B in FIG. 2) or a rectangular wave (see FIG. 2). 2), and in the case of a DC motor, in addition to the duty of the input rectangular wave, the rectangular wave with a limited peak value (C in FIG. 2) and the peak value were increased. A square wave (D in FIG. 2) is used for switching. When the high speed mode is selected by the changeover switch 122, the waveform of the input drive pulse of the focusing actuator 109 is switched to the rectangular wave A or D of FIG. Higher zoom speed is achieved by increasing the focal speed.
When the focus actuator 109 is a DC motor, a DC voltage may be used as the drive power for the actuator 109 instead of the duty control of the drive pulse and the switching of the peak value of the rectangular wave. The height of the DC voltage is increased.

[0019] Thus, the driving trajectory of the focusing lens 105, for example, FIG. 4 through the track 1 ₁ is to reach the B ₁ point in close proximity as possible to the regular arrival point B in this way, As a result, it is possible to increase the focusing speed in a state in which the amount of blur is suppressed as small as possible without making the captured image large in blur.

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, the high speed mode is selected by the changeover switch 122 to start high speed zooming of the video camera.
It is confirmed whether or not it is in the recording pause state, and if the recording is not performed, in step S3, the zoom lens is switched to the high speed drive, and the focus lens is similarly driven at the high speed, and the recording is performed. In step S4, both the zoom lens and the focus lens are driven at the normal speed without shifting to the high-speed zoom state.

Therefore, in this operation example, during recording by the video camera, recording can be continued in a low noise state, and at the time of non-recording, the drive torque is increased as necessary to perform high-speed zooming, and a large image is displayed. It is possible to easily perform imaging while avoiding blurring as much as possible.

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

[0024]

As described above in detail with reference to the embodiments,
According to the present invention, the lens drive control device of the camera has means for switching the drive power signal waveform to the focusing actuator according to the switching of the zoom speed by the zoom operation means. Corresponding to, the focus lens can be driven extremely easily at high speed, and the focusing speed can be increased in accordance with the zoom drive. As a result, the focus lens with a trajectory close to the drive trajectory of the zoom lens can be used. High-speed driving to the in-focus point becomes possible, and it is possible to obtain an excellent effect of preventing blurring of a captured image during high-speed zooming.

[Brief description of drawings]

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

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

FIG. 3 is a focus 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 focus locus and an autofocus locus during high-speed zoom.

[Explanation of symbols]

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

Claims (1)

[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 high speed and a low speed of 2 speeds or higher, and a zoom lens of the variable power lens. A lens drive control device for a camera, comprising: a focus operation means for changing a drive speed of the focus adjustment lens according to a zoom speed; and a control means for supplying drive power to each driver and controlling polarity. Depending on the switching of the zoom speed by the zoom operation means, A lens drive control device for a camera, comprising a means for switching a drive power signal waveform.