JPH0239113A - Zoom lens driving device - Google Patents

Abstract

PURPOSE:To reduce the voltage variation of a battery, to prevent a CPU from generating runaway and to extend the life of the battery by intermittently driving a zoom lens, and at the time of stopping the operation of the zoom lens, driving a focus lens. CONSTITUTION:Since the load of a zoom motor 2 is changed in accordance with its driving position, the motor 2 is intermittently driven to execute zooming at a fixed speed. Thereby, the CPU 1 drives the motor 2 intermittently, and during the suspending time of the motor 2, drives the focus motor. Since respective motors are not simultaneously driven and a large current is not allowed to flow at a time, the consumption of the battery is reduced. Consequently, the CPU can be prevented from generating runaway due to the drop of voltage and the life of the battery can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zoom lens driving device that electrically drives a zoom lens used in still cameras, video cameras, and the like.

[Prior Art] As is well known, when a zoom lens zooms,
There are methods that drive the front group lens, methods that drive the raw liver lens, and methods that drive the T& group lens.The method that drives the front group lens causes less change in the focus position due to zooming, but it moves more than the other methods. This increases the amount of time required to move the lens. In order to solve this problem, it is possible to adopt a method of driving the raw liver lens or a method of driving the rear group lens.However, with this method, there is a large shift in the focus position due to zooming, so
I have to make that correction.

In recent years, it has been proposed that this is done electrically.

For example, as disclosed in Japanese Patent Application Laid-Open No. 62-262014, the focus lens position corresponding to the zoom lens position is stored in a memory, and when the zoom lens is moved, the data in the memory corresponding to the lens position is stored. Read from memory and adjust the focus lens based on the read data! 5. Something that drives. The second control is performed by a microcomputer.

[The invention attempts to solve the problem.] Problem S1] However, such conventional devices consume a lot of current because they drive both the zoom lens drive motor and the focus lens drive motor at the same time, and the battery voltage fluctuations are large, so the circuit There are 1fff problems, such as causing the CPU to run out of control, and shortening the battery life.

[Means for Solving the Problems 1] In order to solve these problems, the present invention provides means for intermittently driving the zoom lens and means for driving the focus lens when the zoom lens stops operating. It is.

[Operation] The zoom lens and focus lens are driven independently, and the maximum current consumption is suppressed to a low value.

[Implementation PA] FIG. 2 is a block diagram showing an example of a device constructed by applying the present invention. In the figure, 1 is the CPU, 2 is its C
A zoom motor is supplied with control signals output from the PUI via a driver 3, and a focus motor 4 is supplied with 't and xstn signals output from CP (Jl) via a dry parameter. The zoom lens and focus lens are moved by rotation.Although each lens is not shown, a photointerrupter is provided that generates a number of pulses corresponding to the amount of movement of the lens.

Since the load on the zoom motor varies depending on its drive position, it is driven intermittently to zoom at a constant speed. For this reason, the cput is configured to drive the zoom motor intermittently, and the focus motor 11 is driven when the zoom motor 2 is at rest. As shown in FIG. 3, the amount of movement of the focus motor 4 is determined with respect to the zoom rotation angle. In Figure 3, the solid line is the original design value for the focus lens extension of the lens, and the dotted line is the focus lens extension amount when using a zoom lens. It is set to be the closest side. With this configuration, when the zoom motor 4 needs to be driven, for example, when a zooming operation is performed in the device, cput is a signal generated at predetermined intervals, as shown in FIG. 4(d). As a result, a signal for driving the zoom motor 1 is output as shown in FIG. 4(e). This state is step 100 in FIG. The zoom motor 2 sends out pulses after the zoom motor 2 has been driven by a predetermined amount, as shown in FIG. 4(c). This is the state in which "YJ" is determined in step 101 of FIG. 1, and as a result, the zoom motor 2 is turned off and a timer is set as shown in step 102.

Next, in step 103, it is determined whether the focus motor 4 needs to be driven or not, and "Y" and #IU
When T is reached, the focus motor 4 is turned on as shown in step 104, so the focus motor 4 is driven as shown in FIG. 4(b). Whether or not it is necessary to drive the focus motor 4 is determined by whether or not the focus lens is located near the dotted line position in FIG. By driving the focus motor 4, pulses corresponding to the amount of movement of the focus lens are sent out as shown in FIG. 4(a). This is step 10 in Figure 1.
1 is determined to be "N", step 105 is determined to be "N", and step 106 is determined to be "Y".

At this point, as shown in step 107, IIIUr is performed to determine whether it is necessary to continue driving the focus motor 4. This judgment is made in step 108 when the number of pulses from the focus lens reaches a predetermined value within the predetermined time T shown in FIG. 4(e). Even if the focus motor 4 is not used, the focus motor 4 is turned off in step 100 when the specified time has elapsed. Returning to step 100, the zoom motor 2 is driven again and the same control as described above is performed.
By repeating this control, both the zoom motor 4 and the focus motor 2 are controlled to an even position, and the CPU
Since the pulse shown in FIG. 4(e), which has been periodically sent out since time t, stops, the operation of this device ends.

The difference in pulse width in FIG. 4(e) is due to the difference in the load on the lens. Further, although FIG. 1 shows one sequence, each operation may be processed by an interrupt. In this embodiment, the focus lens is adjusted to the position shown by the dotted line in FIG. 3, but it may be adjusted to the position shown by the solid line.

[Effects of the Invention] As explained above, in the present invention, the zoom motor is driven intermittently and the focus motor is driven during the period when the zoom motor is not operating, so that the respective motors are not driven simultaneously. Since a large current does not flow at the same time, battery consumption is reduced, preventing the CPU from running out of control due to low voltage f, and has the effect of extending battery life.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an embodiment of the present invention, FIG. 2 is a block diagram of the apparatus, and FIG. 3 is a graph showing the relationship between the zoom rotation angle and the amount of lens extension, and FIG. 4 is a waveform diagram of each part. ■...C)) U, 2...Zoom motor, 35.
...-driver, 4 focus motors.

Claims (1)

[Claims] A zoom lens driving device that drives a zoom lens in which the focus position changes in response to changes in the position of the zoom lens, comprising: a zoom lens driving section that intermittently drives the zoom lens; 1. A zoom lens drive device comprising: a focus lens drive section that sometimes drives a focus lens.