JPH01246515A - Zoom lens driver - Google Patents

Abstract

PURPOSE:To prevent the backlash between an encoder and a zoom lens and to stop the zoom lens always at a target position by moving the zoom lens to the prescribed position deviated by a prescribed quantity in the prescribed direction from the target position, then moving the zoom lens at a low speed to the target position. CONSTITUTION:A comparison/control part 4 is connected to a zoom switch 6, a telephoto/wide end data generating part 7 or target zoom calculating part 5 and supplies a control signal to a motor driving part 2 to control a motor 10 while referring the detection value of the zoom encoder 9. The full-speed driving of the motor is stopped when the zoom lens arrives at the position just before the final stop position in this zooming control. The zoom lens is thereafter zoomed at a low speed in the telephoto direction. The motor 10 is stopped when the change of the detection valve of the zoom encoder 9 by +1 is confirmed. The backlash of the mechanical system is thereby prevented and the zoom lens is stopped always at the target position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zoom lens driving device that moves a zoom lens using a motor or the like.

[Conventional technology]

Currently, as a driving method for zoom lenses, an electric driving method such as that used in video cameras and the like is generally used. This uses a motor to move the zoom lens.

When you press the "tele" switch, the motor rotates forward and the zoom lens moves toward the telephoto side; when you press the "wide" switch, the motor rotates in reverse and the zoom lens moves toward the wide side. and,
When you release the switch, the zoom lens stops moving. When the telephoto end or wide end is reached, it is generally detected with a switch or the like and the motor is stopped.

An example of such a zoom lens driving system is an autozoom described in Japanese Patent Application No. 62-53241 filed by the present applicant. This automatically sets the zooming target position according to the shooting distance so that the ratio of the main subject in the shooting frame is always constant, and the photographer can simply track the subject to that position. It zooms automatically.

[Problem to be solved by the invention]

However, the above-mentioned application does not specify a means for stopping the zoom lens at the 11 mark position.

Generally, the zoom position is determined by the zoom encoder, but if there is play in the zoom encoder or the zoom lens itself, depending on the direction of zooming, the encoder value and the position of the zoom lens when the lens stops may differ. Misalignment (backlash) occurred, which affected lens characteristics.

This invention was made to deal with the above-mentioned circumstances,
To provide a zoom lens driving device capable of accurately placing a zoom lens at a target position and always keeping the positional deviation between an encoder value and the zoom lens constant when the zoom lens is stopped. is its purpose.

[Means for Solving the Problems] In the auto mode, the zoom lens driving device according to the present invention moves the zoom lens to a predetermined position that is shifted by a predetermined amount in a predetermined direction from the target position, and then moves the zoom lens to the target position. It is provided with means for moving at a low speed, and in the case of manual mode, zooming up or zooming down until the end of operation of the zoom switch r, and then moving it at a low speed by the predetermined amount in the opposite direction to the predetermined direction.

[Effect]

According to this invention, when stopping the zoom lens, it is possible to prevent backlash between the encoder and the zoom lens by always stopping the zoom lens while zooming in a fixed direction, and when the zoom lens approaches the target position. By reducing the moving speed of the zoom lens and approaching the target position at low speed, it is possible to always stop the zoom lens at the target position.

〔Example〕

FIG. 1 is a block diagram of an embodiment of a zoom lens driving device according to the present invention. The CPU 1 in the camera has a target zoom position calculation section 5, a tele/wide end data generation section 7, and a comparison/control section 7.

A signal from the target zoom position calculation section 5 or the tele/wide end data generation section 7 is input to the comparison/control section 4 via the switch 11.

The output of the comparison/control section 4 is supplied via the motor drive section 2 to a motor 10 for zooming the lens. The zoom position of the lens is detected by the zoom encoder 9, and the detected value is input to the comparison/control section 4.

The output of the zoom switch (zoom up/zoom down switch) 6 is also manually input to the comparison/control section 4 via the switch 12. By operating this zoom switch 6, it is also possible to zoom up and zoom down.

Switching of switches 11,12 is controlled by a signal from auto/manual selector 8. When auto is selected by the auto/manual selector 8, the switch 12 is turned off and the zoom switch 6 is disconnected from the comparison/control unit 4. Further, the switch 11 is connected to the target zoom position calculation section 5 side. Therefore, the comparison/control section 4 controls the motor drive section 2 based on the signal from the target zoom position calculation section 5.

When manual is selected with the auto/manual selector 8, the switch 12 is turned on and the output of the zoom switch 6 is supplied to the comparison/control section 4.

Further, the switch 11 is connected to the tele/wide end data generating section 7 side. Therefore, the comparison/control section 4 controls the motor drive section 2 based on the signal from the zoom switch 6.

In this way, the comparison/control section 4 is controlled by the zoom switch 6, the tele/wide end data generation section 7, or the target zoom calculation section 5.
, and supplies a control signal to the motor drive section 2 while referring to the detection value of the zoom encoder 9, thereby controlling the motor 10.

With this zooming control, when stopping at the target position in auto mode, or at the end of zoom switch 6 operation in manual mode, or when stopping at the tele end or wide end, one position before the final stopping position. When the motor reaches the position of stop. After that, zooming (zooming up) in the tele direction at low speed is performed, and when it is confirmed that the detected value of the zoom encoder 9 has changed by +, the motor 10 is stopped. Also, when zooming is stopped, the lens must be moved in a certain direction (in this case, the zoom-up direction) to prevent backlash in the mechanical system and to check the detected value of the zoom encoder 9 before stopping. can. Here, intermittent pulse driving is used to drive the motor at low speed.

Next, this zooming control will be explained in detail with reference to the flowchart shown in FIG.

First, a case where auto zoom is selected with the auto/manual selector 8 will be described. During auto zoom, before entering the auto zoom routine shown in FIG. 2, the target zoom position calculation unit 5 calculates the target zoom position by 1 according to shooting distance information from a distance measuring unit (not shown), and determines the target position. information to CPUI
Write it to the built-in RAM.

First, in step 20, it is determined whether the current zoom position detected by the zoom encoder 9 is "target position - 1" (a position on the wide side that is smaller by 1 in the detection value of the zoom encoder 9 than the target position). "Target position -
If the motor is not 1, it is determined in step 22 whether the motor should be rotated forward (in the zoom-up direction) or in the opposite direction (in the zoom-down direction), based on the magnitude relationship between the current position and the target position -1. In step 24, the motor 10 is turned on,
Depending on the determination result in step 22, the motor 10 is rotated forward/reverse at full speed for zooming. Thereafter, the process returns to step 20, the current position is read from the output of the zoom encoder 9, and the zooming operation is repeated based on the comparison result with the target position.

When the "target position -1" is reached, the motor 10 is braked for a certain period of time in step 26, and a low-speed pulse drive routine is entered. The reason why the brake is applied for a certain period of time before starting pulse drive is to ensure that the effect of pulse drive, that is, to prevent overrun and stop at the target position by driving at low speed, is achieved. be. Further, if the auto zoom routine is at "target position -1" from the beginning, the pulse drive routine is entered without any movement.

In the pulse drive routine, first in step 28 it is determined whether the current position is the target position.

The zoom position before starting pulse drive is "Target position - 1"
'', but if it is already at the eye (vote) position, the brake is immediately applied for a certain period of time in step 32, and the auto zoom operation is terminated.

If the target position has not been reached, in step 30 the motor 10 starts to rotate forward by pulse drive, zooms up in the telephoto direction, and returns to step 28.

Then, the value of zoom encoder 9 increases by 1, and 1-
When the first target position is reached, the brake is applied for a certain period of time in step 32, and the auto zoom operation is ended.

In this way, the auto zoom operation always zooms at full speed to a position one wide side from the target position, regardless of whether the lens is on the telephoto side or wide side of the target position, and then zooms at full speed from there to the target position. Zooms up at low speed using pulse drive.

As a result, the lens always moves in the zoom-up direction at the end of zooming, making it possible to prevent backlash in the mechanical system and to accurately focus the lens on the target position.

Next, a case where manual zoom is selected with the auto/manual selector 8 will be described. zoom up switch,
Enter the manual zoom routine by operating the zoom down switch.

First, in steps 40 and 42, it is determined whether the zoom up or zoom down switch is turned on.

In the case of zooming up, it is determined in step 44 whether the switch is turned on, and only if it is immediately after, it is determined in step 46 whether the current position is at the telephoto end. If the camera is already at the telephoto end, the zoom process ends without doing anything.

If it is not the tele end, select "tele end 1" in step 48.
(a position on the wide side that is smaller than the telephoto end by 1 in the detection value of the zoom encoder 9). "
If it is not "Tele end 1", in step 50 the motor 10
Rotate at full speed and zoom up. Thereafter, the process returns to step 40, and the operating state of the zoom switch is checked.

When the telephoto end 1 is reached, or if it is at the telephoto end 1 from the beginning, the motor 1 is turned off in step 52.
0 for a certain period of time, in step 54 a position one telephoto side (i.e., telephoto end) from the current (E position) is set as the target position, and the pulse drive routine used in the auto zoom mode (step 28~Step 32)
to go into. Therefore, zooming is stopped after zooming up at a low speed from "telephoto end 1" to the telephoto end.

In the case of zooming down, as in the case of zooming up, it is determined in step 56 whether the switch is turned on, and only if it is immediately after, it is determined in step 58 whether the current position is at the wide end. If the camera is already at the wide end, zoom processing is performed without doing anything.

If it is not the wide end, in step 60
”. If it is not "wide end 1", the motor 10 is reversed in step 62 to zoom down. Thereafter, the process returns to step 40, and the operating state of the zoom switch is checked.

When it reaches "wide end 1", or if it is "wide end 1" from the beginning, the brakes are applied for a certain period of time in step 52, and then in step 54, the position is moved one telephoto side from the current position. (i.e., "wide end 2") as the target position, and the pulse drive routine used in auto zoom mode (steps 28 to 32)
to go into.

Therefore, after zooming up at a low speed from "wide end 1" to "wide end 2", zooming is stopped.

In addition, if the zoom switch is turned off at any position during zooming, the brake is immediately applied for a certain period of time in step 52, and then in step 54, the position obtained by adding 1 to the detection position of the zoom encoder at that time is set as the eyesight position. It enters a pulse drive subroutine, zooms up slowly until the zoom encoder increases by 1, and then stops zooming.

As mentioned above, in both auto zoom mode and manual zoom mode, at the end of zooming, the zoom encoder always moves in the zoom up direction at a low speed by one step.
It can eliminate mechanical backlash and stop accurately at the desired position.

Next, pulse driving will be explained in detail. Pulse driving means that the motor is repeatedly turned on and off in a pulse-like manner, but if the duty of the motor is on is long, there is little effect of reducing the drive speed, and conversely, if the duty of the motor is on is short, the speed will be reduced. However, the motor may stop working. Therefore, in this embodiment, intermittent pulse driving is performed.

That is, although the on duty of one cycle of motor on/off is relatively long, after several cycles of driving, a period is provided in which the drive is stopped for the same cycle.

FIG. 3 shows a flowchart for pulse driving the motor 1o in the zoom-up direction. When the zoom up direction pulse driving routine is entered, the hard timer in the cPU is checked, and in step 70 it is determined whether a certain period of time has elapsed since the last check. If the predetermined time t has elapsed, a RAM counter (5 bits) is counted up in step 72. That is, the RAM counter is counted up at fixed time intervals.

Next, in step 74, the MSB of the RAM counter is checked. If the MSB is "0", the motor 10 is turned off in step 76.

If the MSB is "1", the AND result of the RAM counter value and "0011" (binary) is checked in step 78. If the AND result is "0", the motor 10 is turned off in step 80.

If the AND result is '1'', motor 1 is
Turn on 0.

The relationship between the RAM counter value and motor on/off is the fourth
The result will be as shown in the figure.

The repetition of motor on and motor off by intermittent duty driving shown in the flowchart of FIG. 3 is as shown in FIG. That is, normally, one cycle is 4t, and the motor is turned on for a period of 3 and turned off for a period of .However, after 4 periods of pulse driving, the motor is continuously turned off for 4 periods (16t).

In the above-described embodiment, an example of duty drive was explained by combining motor-on and motor-off, but step 7
6. If either step 80 of turning off the motor is replaced with a step of applying brakes to the motor for a certain period of time,
The speed can be further reduced.

〔Effect of the invention〕

As explained above, according to the zoom lens driving device of the present invention, when finishing zooming, the user always reads the value of the zoom encoder and confirms the zoom position, then rotates the zoom at a low speed and stops at the target zoom position. By doing so, the zoom speed is reduced before the target position while removing the mechanical crash, so that it is possible to accurately zero the zoom position at any desired zoom position. Furthermore, since the stopping routine is shared between manual zoom and auto zoom, the number of programs 82 can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a zoom lens driving device according to the present invention, FIG. 2 is a flowchart showing the overall operation of the embodiment, and FIG. 3 is a flowchart showing the pulse drive operation in FIG. 2. , Figure 4 shows R in pulse drive.
FIG. 5 is a diagram showing the relationship between the AM counter and motor operation, and is a diagram showing an example of pulse driving. 1... CPU, 2... Motor drive section, 4... Comparison/control section, 5... Target zoom position calculation section, 6... Zoom switch, 7... Tele/wide end data generation Department,
8...Auto/manual selector, 9...Zoom encoder, 10...Motor. Applicant's representative Patent attorney Atsushi Tsuboi Figure 1 Figure 3 Figure 4 Figure 5 Figure 1, Display of the case Japanese Patent Application No. 1983-73105 2, Name of the invention Zoom lens drive device 3, Person making the amendment Related: Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent UBE Building 7, 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo.
Details of the amendment (1) "Comparison/control unit 7" written on page 4, line 18 of the specification is corrected to "comparison/control unit 4." (2) "Wide end 12" written on page 12, line 9 and line 12 of the specification is corrected to "wide end." (3) Figure 1 of the drawing is corrected as shown in the attached sheet. Figure 1

Claims (2)

[Claims] (1) A zoom lens driving device for moving a zoom lens to a target position, comprising: means for moving the zoom lens at a predetermined speed to a predetermined position shifted by a predetermined amount in a predetermined direction from the target position; and a means for moving the zoom lens from the predetermined position to the predetermined position. A zoom lens driving device comprising a low-speed moving means for moving to a target position at a speed lower than the predetermined speed in a direction opposite to the predetermined speed. (2) means for moving the zoom lens at a predetermined speed in a direction according to the operation of the operating member, and low-speed movement for moving the zoom lens in a predetermined direction by a predetermined amount at a speed lower than the predetermined speed after the operation of the operating member is completed; A zoom lens driving device comprising: means.