JPS6198310A - Lens driver - Google Patents

Abstract

PURPOSE:To execute focusing and power variation by the same motor and to improve the using efficiency of the motor by forming a control means for controlling a focusing means so as to drive it by the motor only when a manual variable power state is selected by a selecting means. CONSTITUTION:When a zoom switch 45 is turned to the T side (telescopic side) at the time of zooming operation, current is supplied to a solenoid 46 by a control circuit 44 and the motor 33 is rotated in a prescribed direction. In accordance with the current supply to the solenoid 46, the solenoid 46 is sucked against the exciting force of a tension spring 40 and a clatch switching lever 37 is rotated. In accordance with the rotation of the lever 37, a roller 36 pushes a recessed part 29c of a clatch pulley 29 in the arrow 50 direction and the side 29b of the pulley 29 pushes a felt ring 31 fitted to the side of a zoom ring driving gear 27. Since the rotation of the motor 33 can be transmitted to the clatch pulley 29 and the gear 27 can be rotated unitedly with the pulley 29, a zooming ring 25 is rotated to execute zooming operation on the telescopic side.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lens driving device that can be used in a zoom lens of a video camera or the like.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, with the spread of video cameras, there has been a demand for zoom lenses with autofocus and electric zoom functions.

A conventional lens driving device will be described below with reference to the drawings. FIG. 1 is a diagram showing the main parts of a conventional lens driving device. A focus ring 2 for holding a focusing lens is provided at the front of a lens unit 1, and the outer circumference of the focus ring 2 is It has a spur gear 3.

Since the spur gear 3 meshes with the spur gear 5 press-fitted into the focus motor 4, the focus ring 2 can be driven by the focus motor 4. Additionally, a distance sensor 6 is provided outside the lens unit 1 and is composed of an infrared LED (light emitting diode) and a light receiving element for measuring the distance to the subject, and is connected to the distance circuit 7. ing. The motor 4 drive circuit 8 compares the distance signal obtained by the distance measuring circuit 7 at the object position and the focus position signal of the focus ring 2, and drives the focus motor 4 in a direction that reduces the difference between these two signals. This is to supply a constant voltage to the door so that it rotates. Furthermore, the intermediate portion of the lens unit 1 has a zoom ring 9 for driving the variable magnification lens, which meshes with a spur gear 1o provided on the outer periphery of the zoom ring 9 and a spur gear 12 press-fitted into the zoom motor 11. ing. Therefore, zooming can be performed by moving the variable magnification lens in forward and reverse directions according to the polarity of the voltage supplied to the zoom motor 11.

However, in the above configuration, dedicated motors are required for focusing and zooming, which increases the weight and increases the cost.

Objective of the invention A The objective of the invention is to autofocus,
It has electric zoom 1',, ) function, o-
C cheap 7, stable. The purpose of the present invention is to provide an apricot driving device.

Composition of the Invention The lens driving device of the present invention includes a magnification changing means for changing the magnification of an optical image of a subject, an electric magnification changing state in which the magnification changing means is driven by a motor, and a manual state in which the magnification changing means is driven by a motor. a selection means for selecting a variable magnification state, a focusing means for focusing an optical image of a subject, and a rotating section for driving the focusing means by a motor only when the manual variable magnification state is selected by the selection means. The lens drive device is configured to include a control means for controlling the lens in the following manner, and as a result, it is possible to perform focusing and variable magnification with the same motor, and it is possible to provide a lens driving device that improves the utilization rate of the motor. .

Furthermore, the focusing means includes an automatic focusing circuit, and when the electric zoom state is selected by the selection means, the focusing means includes a current cutoff means for cutting off the current supplied to the automatic focusing circuit. Because of this structure, no unnecessary current is consumed.

Explanation of the embodiment T4. -ga,, (1yotsuia1.□□, ) and explain.

FIG. 2 is a block diagram of a main part of a lens driving device according to an embodiment of the present invention, and shows a manual zooming state.

The front part of the lens unit 21 has a focus ring 22 that holds a focusing lens and moves in the optical axis direction by rotating it, and a gear 23 provided on the outer periphery of the focus ring 22 is a focus ring drive gear 24. Occlusal. Similarly, the rear part of the lens unit 21 has a zoom ring 26 for operating the variable magnification lens.
The outer periphery of 6 is rotatably held by @28,
A clutch pulley 29 is provided between the focus ring drive gear 24 and the zoom ring drive gear 27 and is slidable on the shaft 28 and rotatably held.

One side 29a of the Claso tip 29 is a felt ring 3 bonded to the side of the focus ring drive gear 24.
The other side surface 29b of the clutch pulley 29 can come into contact with a felt ring 31 bonded to the side surface of the zoom ring drive gear 27, and has a gear 32 on the outer periphery of the side surface 29b. There is. The gear 32 is a gear 35 that is press-fitted into the rotating shaft 34 of a motor 33 that has a reduction mechanism built into it.
and occlusion.

Still, the clutch pulley 29 has a recess 29c in the middle thereof to engage with a roller 36, and the roller 36 is rotatably held with respect to a shaft 38 installed at the end of the clutch switching lever 37. . The clutch switching lever 37 is rotatably provided by a support shaft 39, and is biased to one side by a tension spring 4o. Outside the lens unit 21, there is an infrared LED (
The distance measuring sensor 41 includes a light emitting diode), a light receiving element, etc., and is connected to a distance measuring circuit 42.

Further, the focus ring 22 has an encoder (not shown) built in it for detecting the focusing distance of the focusing lens, and the out-of-focus detection circuit 43 detects the signal from the encoder and the distance measurement circuit 42. Compare the signals and -11 distance circuit 4
If there is a predetermined difference between the measured distance to the subject in step 2 and the current focusing distance of the focusing lens, the motor is controlled via the control circuit 44 in a direction that reduces the difference in distance between the two. 33 is configured to rotate.

Furthermore, a zoom switch 45 is connected to the control circuit 44, and the control circuit 44 controls the solenoid 46 engaged with the clutch switching lever 37 and the motor 33 to operate in conjunction with the operation of the zoom switch 45. However, the direction of rotation of the motor 33 can be changed depending on the operating direction of the zoom switch 46, and the direction of zooming can be changed.

Therefore, the control circuit 44 controls the focus ring 22 by the motor 33 only when the zoom switch 46 is not operated.
It has a control function that allows it to drive. Further, an AF power switch 47 that operates in conjunction with the zoom switch 45 is provided.
7, the current of the power supply 48 is supplied to the distance measuring circuit 42 and the out-of-focus detection circuit 43.

il... Good job, □□tech. , 7□ The operation of the device will be explained below. First, driving of the focus ring 22 will be explained.

When the current focusing distance of the focusing lens is ■, when photographing a nearby subject (for example, the distance to the subject is 3 m), the distance measuring sensor 41 measures this distance, and the distance sensor 41 built in the focusing ring 22 measures this distance. The out-of-focus detection circuit 43 detects that the in-focus distance is different from the in-focus distance of the in-focus lens based on the signal from an encoder (not shown), and the control circuit 44 causes the motor 33 to
Rotate. At this time, since the clutch switching lever 37 is biased by the tension spring 4o, the roller 36 provided at the tip of the clutch switching lever 37 moves the concave portion 29c of the clutch pulley 29 in the direction of the arrow 49, as shown in FIG. The side surface 29a of the clutch pulley 29 presses the felt ring 3o on the side surface of the focus ring drive gear 24.

Therefore, the clutch pulley 29 can rotate integrally with the drive gear 24, and when the gear 35 of the motor 33 rotates in a predetermined direction, the clutch pulley 29 is rotated in a predetermined direction. The gear 32 of the gear 29 rotates, and the focus ring 23 is rotated via the focus ring drive gear 24. The focusing distance of the focusing lens changes as the focus ring 22 rotates, and when the focusing lens moves until it matches the distance to the subject measured by the distance measurement sensor 41, the control circuit 44 stops the rotation of the motor 33. Stop. Also, when the focusing lens focuses on a short distance and the subject is far away, it is the same as above.

The motor 33 rotates in the opposite direction to that in the above case, and the focus ring 23 is rotated in the opposite direction.

Next, driving of the zoom ring will be explained.

As shown in the configuration diagram during zoom operation in FIG. 3, when the zoom switch 45 is operated to the T side (telephoto side), the control circuit 44
energizes the solenoid 46 and rotates the motor 33 in a predetermined direction.

When the solenoid 46 is energized, the solenoid 46 is attracted against the biasing force of the tension spring 4o, and the clutch switching lever 37 is rotated as shown in FIG.

As the clutch switching lever 37 rotates, the roller 36 presses the recess 29c of the clutch pulley 29 in the direction of arrow 5o, and the side surface 29b of the clutch pulley 29 moves toward the zoom ring F.
The felt ring 31 on the side surface of the Xil gear 27 is pressed. Therefore, the rotation of the motor 33 is controlled by the gear 35. The power is transmitted to the clutch pulley 29 by the gear 32, and the zoom ring drive gear 27 can rotate integrally with the clutch pulley 29, so the motor 33 can rotate the zoom ring 26 and perform zooming toward the telephoto side. .

On the other hand, when the zoom switch 45 is operated to the W side (wide-angle side), the motor 33 rotates in the opposite direction to that in the above case, so that a zooming operation can be performed to the wide-angle side. Further, when zooming, if zooming is performed to the end of the zooming range and the zoom switch 45 is operated, a large load is applied to the motor 33 due to slipping between the felt ring 31 and the side surface 29b of the clutch pulley 29. This is prevented.

Furthermore, when the zoom switch 46 is operated to the T side or the W side, the AF power switch 47 linked to the zoom switch 45 is turned off, cutting off the current supplied to the survey circuit 42 and the out-of-focus detection circuit 43, and dissipating the current. Power can be reduced.

As described above, according to this embodiment, it is possible to perform focusing and zooming with the same motor, which is lightweight and inexpensive.
Moreover, it is possible to provide a lens driving device that operates stably.

Effects of the Invention As is clear from the above explanation, the present invention has a motor,
A zooming means (such as a zoom ring) for changing the magnification of an optical image of a subject, and a selection means (zoom switch) for selecting between an electric zooming state in which the zooming means is driven by a motor and a manual zooming state that does not use a motor. ) and a focusing means (focus ring, etc.) for focusing the optical image of the subject, and control so that the focusing means can be driven by a motor only when manual magnification is selected by the selection means. Since the lens drive device includes a control means for controlling the lens, it is possible to perform focusing and zooming with the same motor, thereby providing a lens drive device that is lightweight, inexpensive, and operates stably.
I can do that.

In addition, the focusing means has an automatic focusing circuit (a distance measuring circuit, an out-of-focus detection circuit), and when the electrically variable magnification state is selected by the selection means, the current supplied to the automatic focusing circuit is Since the configuration includes a current interrupting means (AF power switch) for interrupting current, power consumption can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a conventional lens drive device, FIG. 2 is a block diagram of the main parts of a lens drive device according to an embodiment of the present invention, and FIG. 3 is a block diagram of the main part of the lens drive device in an embodiment of the present invention. 22...Focus ring, 25...
Zoom ring, 29...Clutch pulley, 33
...Motor, 37...Clutch switching lever, 42...Distance measurement circuit, 43...Out-of-focus detection circuit, 44... Control circuit, 46...
...Zoom switch, 47...AF power switch. Name of agent Patent attorney Toshio Nakao and 1 other person Figure 1 Figure 2 41 4Z 43

Claims (2)

[Claims] (1) a magnification changer for changing the magnification of an optical image of a subject; a selection means for selecting between an electric magnification change state in which the magnification change means is driven by a motor and a manual magnification change state in which the motor is not used; and a control means for controlling the focusing means so that it can be driven by the motor only when a manual magnification change state is selected by the selection means. A lens drive device. (2) The focusing means has an automatic focusing circuit, and includes a current cutoff means for cutting off the current supplied to the automatic focusing circuit when the electric variable magnification state is selected by the selection means. A lens driving device according to claim 1, which comprises: