JPH05173051A - Motor-driven zoom device - Google Patents

Abstract

PURPOSE:To provide a zoom device in which a motor is stopped before a cam pin collides with a cam groove end at a telephoto end and a wide end, and also zoom moving from the telephoto end or the wide end can be executed without a hindrance, parts damage and wasteful power consumption caused by collision can be prevented so that motor-driven zooming can be executed without anxiety. CONSTITUTION:A cam groove has a first cam groove part shifting lens supporting bodies 4, 5 in an optical axis direction and an extended cam groove part in a circumferential direction connected to the telephoto end and the wide end, the motor 13 is stopped before the cam pins 6, 7 collide with the cam groove end by the detected information from a detecting means detecting whether the cam pins 6, 7 of the lens supporting bodies 4, 5 move to the extended cam groove part from the groove ends of the first cams 6, 7 or not, so that when the cam pins 6, 7 move to the first cam groove part from the extended cam groove part, the motor 13 is not stopped by the detected information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric zoom device used in cine cameras, video cameras and the like.

[0002]

2. Description of the Related Art In a conventional electric zoom device used in a camera as described above, a zooming mechanism reaches an end position of zooming movement from a change in a subject image seen by a photographer using a TTL viewfinder or an electronic viewfinder. I had to judge whether or not. Therefore, even if a friction clutch is provided between the electric mechanism and the zooming mechanism to prevent the electric mechanism or the zooming mechanism from being excessively stressed, the motor at the tele end or the wide end of the zooming can be operated. Drive stop is delayed and power is wasted,
It may impair the durability of parts.

There is also known an electric zoom device in which an operating lever is provided on a zoom ring that rotates with zooming so that zooming can be performed manually. In this case, the position of the operating lever reaches a tele end or a wide end. It should be judged whether or not it is correct, but it is difficult for the photographer looking into the viewfinder to make a judgment. It is necessary to provide a friction clutch between the electric mechanism and the zooming mechanism in order to perform the manual operation as described above.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to facilitate zooming movement when electrically zooming using a motor. In order to prevent damage to parts in the electric zoom, prevent the cam pin from colliding with the groove at the zoom end, and perform zoom control so that it does not malfunction when moving the lens once it reaches the zoom end to the other. It is intended for.

[0005]

According to the present invention, there is provided a cam ring having a cam groove for moving a lens in an optical axis direction,
It has a lens support having a cam pin that supports the lens and engages with the cam groove, and a cam ring drive motor that rotates the cam ring, and the lens support moves in the optical axis direction as the cam ring rotates. In the electric zoom device configured to be moved to move the lens toward the tele end or the wide end, the cam groove is formed in a direction not orthogonal to the optical axis to move the lens in the optical axis direction. Of the first cam groove portion and an end portion corresponding to the tele end or the wide end of the first cam groove portion, which is formed continuously in the circumferential direction of the cam ring so as not to move the lens in the optical axis direction. And a detection means for detecting that the cam pin has reached the extension cam groove portion from the first cam groove portion in accordance with the rotation of the cam ring. Based on the detection of the step, control is performed so that the motor is stopped before the cam pin collides with the end of the extended cam groove portion, and the cam pin moves from the extended cam groove portion to the first cam groove portion. In this case, the electric zoom device is characterized in that the motor is controlled so as not to be stopped based on the detection information until it is deviated from the side of the tele end or the wide end, and the object is achieved by this configuration.

[0006]

That is, in the electric zoom apparatus of the present invention, the cam pin of the lens support is detected by the information of the detecting means for detecting that the cam pin has reached the extended cam groove portion from the first cam groove portion of the cam groove. When the cam pin moves from the extended cam groove portion to the first cam groove portion, the motor is not stopped until it enters the first cam groove portion by the information of the detecting means. It is possible to easily and easily perform the electric zoom without worrying about damage to parts due to collision with the end of the cam groove, prevent wasteful power consumption, and improve durability of parts.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view of a lens of a video camera having an electric zoom device, FIG. 2 is a motor drive circuit diagram of an electric mechanism, and FIGS. 3 to 6 are portions of FIG. 1 showing examples of installation of various detecting means. Schematic diagrams, FIGS. 7 to 11 are partial plan views or partial front views showing examples of various detecting means in addition to FIGS.
12 to 14 and FIGS. 16 and 17 are graphs showing output signals of various detection means, FIG. 15 is a circuit diagram of the detection means shown in FIGS. 5 and 10, and FIG. 18 is output signals of the detection means. FIG. 19 is a partially expanded plan view of FIG. 1 showing a cam groove and a guide groove of the zooming mechanism, based on a block circuit diagram for controlling driving of the motor and warning display.

The zoom lens shown in FIG. 1 includes a focus lens group F fitted in a focus ring 1 and a zoom front lens group V1 which is moved by the zoom ring 2 in the optical axis direction.
And a rear lens group V2, and an image forming front lens group M1 and a rear lens group M2 that are integrally fitted to the fixed barrel 3, and the focus lens group F is a focus ring 1.
Is rotated around the optical axis to move back and forth in the optical axis direction for focusing, and the zoom front lens group V1 and rear lens group V2 are supported by the respective lens supports 4 and 5, and the cam pin 6 and 7 are implanted in the lens supports 4 and 5.

The cam pins 6 and 7 engage with a cam groove provided in a cam ring 8 which rotates integrally with the zoom ring 2 around the optical axis, and further, a guide groove 3a provided in the fixed barrel 3 in the optical axis direction.
And the zoom ring 2 by engaging with 3b.
When the lens rotates about the optical axis, it moves in the range optical axis direction shown by the solid line and the chain double-dashed line in FIG. 1 according to a fixed relationship given by the cam groove of the cam ring 8 to perform zooming. The focus ring 1 is a helicoid ring 9 integrally connected to the fixed barrel 3.
And a helicoid screw, and the cam ring 8
The connecting pin 10 planted therein penetrates the circumferential groove of the fixed barrel 3 and engages with the zoom ring 2, so that focusing and zooming are performed as described above.

The structure of the zoom lens as described above is conventionally known. Further, a zoom gear 11 is rotatably fitted to the zoom ring 2, and a friction spring is provided between the zoom gear 11 and the zoom gear 11.
Twelve are engaged so as to transmit rotational power. A drive gear 14 provided on the output shaft of a forward / reverse rotation motor 13 with a speed reducer attached to the fixed barrel 3 meshes with the zoom gear 11. Therefore, as for the rotation of the zoom ring 2, the rotation of the motor 13 causes the drive gear 14 to engage with the zoom gear 11 and the friction spring 12.
It is performed by being transmitted to the zoom ring 2 by. It should be noted that the zoom ring 2 can be rotated by operating a manual operation lever 15 embedded in the zoom ring 2, and in that case, the friction spring 12 and the zoom ring 2 or the zoom gear 11 slips. , The rotation of the zoom ring 2 is controlled by the motor 13
I can't reach you. Further, even when it is rotated by the motor 13, at the tele end or wide end where the ends of the cam grooves of the cam ring 8 are in contact with the cam pins 6 and 7 of the lens supports 4 and 5, the distance between the friction spring 12 and the zoom gear 11 is increased. Alternatively, it is possible to prevent slippage between the zoom rings 2 and application of excessive force to the transmission system.

The rotation of the motor 13 is performed by the circuit shown in FIG. That is, when the changeover switch S is turned on to the side of the tele-terminal T, the transistors Tr1 and Tr1 'are brought into conduction, and a current flows from the right to the left in the motor 13, whereby the motor 13 drives the zoom ring via the drive gear 14 and the like. 2 is rotated to the tele side. When the changeover switch S is turned on to the wide terminal W side, the transistors Tr2 and Tr2 'are made conductive this time, and a current flows from the left to the right of the motor 13, whereby the motor 13 is turned on.
Rotates the zoom ring 2 to the wide side.

When performing zooming by using the motor in this way, the electric zoom apparatus of the present invention can stop the rotation of the motor as soon as the zooming reaches the tele end or the wide end. The detection means as shown in 17 is provided.

FIG. 3 shows an example in which the sliding changeover switch type detecting means shown in FIG. 7 or the potentiometer type detecting means shown in FIG. 8 is provided between the zoom ring 2 and the fixed barrel 3. When the ring 2 rotates to reach the tele end or the wide end, when the slider 16 attached to the ring 2 is of the changeover switch type shown in FIG. 7, the power is supplied from the ground terminal G of the changeover plate 17 attached to the fixed barrel 3. Tele end resistance R connected to terminal Vcc
1 or wide end resistance R2 is connected,
A voltage appears at the detection end V ₀ as shown in FIG. 12, and in the case of the potentiometer type shown in FIG.
In contact with the rubbing telephoto end or the conductor portion connected to the wide end side of the resistance Rs of the resistive plate 18 attached to, the changed voltage appears as shown in Figure 13 to the detection end V _0.

In the potentiometer type detection means of FIG. 8, since the voltage at the detection end V ₀ is different between the tele end side and the wide end side, it is easy to detect the tele end and the wide end separately, and zooming is also possible. Since the voltage of the detection end V ₀ continuously changes even during the movement, it can be used for displaying or setting the scaling factor. Even in the change-over switch type detecting means of FIG. 7, if the resistance value of the connection resistance for detecting the voltage of the detection terminal V ₀ is appropriately reduced by changing the resistance values of the resistors R1 and R2, it becomes the tele end side. Since the voltage value appearing on the wide end side can be changed, the tele end and the wide end can be easily distinguished in the same manner.

The detecting means shown in FIG.
9 is provided, and iron pieces 20, 20 'are provided on the zoom ring 2 so that they come to the position of the Hall element 19 in a state in which the zoom ring 2 is rotated to the tele end side and the wide end side, respectively, and the development plan view of FIG. Since the output Vh of the hall element 19 changes as shown in FIG. 14 as the zooming moves, it is detected that the zooming reaches the tele end or the wide end. obtain.

In the detecting means shown in FIG. 5, a light emitting element 21 such as an LED is attached to a fixing ring 3'which is integrally attached to the fixing body 3,
A light-receiving element 22 such as a photodiode or a phototransistor is attached to the fixed barrel 3 at a position facing the light-emitting element 21 across the wall of the zoom ring 2, and the light-emitting element 21 of the zoom ring 2 is attached.
On the wall that separates the light receiving element 22 from
23 and 23 'are provided as shown in the partial front view of FIG.

FIG. 16 shows a change in the collector side voltage Vc due to the zooming movement when the phototransistor as shown in FIG. 15 is used for the light receiving element 22, and the zoom ring 2 is moved to the tele end by this voltage Vc. Alternatively, it can be detected whether the wide end is reached. It is needless to say that the same can be detected when a photodiode is used for the light receiving element 22.

The detecting means shown in FIG. 6 has a switch 24 attached to the fixed barrel 3.
The zoom ring 2 is provided with projections 25, 25 'which act on the switch 24 when the zoom ring 2 is rotated toward the tele end side and the wide end side.
As shown in FIG. 11, when the zoom ring 2 reaches the tele end side and the wide end side, the base voltage Vb of the switch 24 is set to the value shown in FIG.
As shown in FIG. 7, the power supply voltage Vcc changes to the ground voltage.

The voltages as shown in FIGS. 12 to 14, 16 and 17 detected by the above detecting means are the motors of FIG. 1 when the zooming movement reaches the tele end or the wide end. It is used to automatically shut down 13 or give a warning indication, which is done by the circuit of FIG. That is, in FIG. 18, the changeover switch S of the drive circuit shown in FIG.
When any one of the terminals T or W is turned on and a current starts to flow from the power supply Vcc, the delay circuit activates the detection circuit of the above-mentioned detection means at a point in time when a predetermined time has elapsed, and the detection circuit Output the detection voltage. Here, the fixed time in which the delay circuit is delayed is the time until the zoom ring 2 comes off from the end side when the zoom ring 2 is first at the tele end side or the wide end side, whereby the zoom ring 2 Is driven by a motor from the tele end side or the wide end side. The detection voltage of the detection circuit is input to the determination circuit, and the determination circuit determines whether the zooming movement reaches the tele end or the wide end depending on whether the detection voltage is higher or lower than the constant reference voltages Vr, Vr '. If it is determined that the tele end or the wide end is reached, the motor 13 of the drive circuit is stopped, or the LED or the like is turned on to display a warning.

In this way, when the zooming movement reaches the tele end or the wide end, the motor 13 can be automatically stopped or immediately stopped based on the warning display. Therefore, as shown in FIG. In the zoom lens, the cam grooves 8a and 8b of the cam ring 8 are provided with a first cam for moving the lens in the optical axis direction as shown in FIG. 19 so that the zoom ring 2 can be rotated beyond the variable power range. It is composed of a groove portion and an extension cam groove portion in the circumferential direction, and the zoom ring rotation guide groove 3c of the fixed barrel 3 is also provided with an extension portion in the circumferential direction. Accordingly, in electric zooming, before the stopper pin 2a provided on the zoom ring 2 collides with the end of the zoom ring rotation guide groove 3c of the fixed barrel 3, the cam pins 6 and 7 are similarly guided by the guide groove 3b of the fixed barrel 3. Also, since the motor 13 can be stopped before it collides with the ends of the cam grooves 8a and 8b of the cam ring 8, the effect that the impact and vibration at the time of stopping at the tele end or the wide end is significantly reduced can be obtained. .

[0022]

As is apparent from the above, in the electric zoom apparatus of the present invention, the cam pin of the lens support and the stopper pin of the zoom ring are the end portions of the cam groove of the cam ring and the zoom ring rotation guide groove of the fixed barrel. The electric zoom is automatically stopped at the telephoto end or the wide-angle end before it collides with the vehicle, so it is possible to easily perform the electric zoom with peace of mind, preventing unnecessary driving of the motor and reducing power consumption. Is not only saved, the wear of parts is reduced, but also an excellent effect that shock and vibration can be prevented is obtained, and the lens located at the tele end or the wide end side is placed on the opposite side. The electric zoom to move can also be performed without any trouble.

[Brief description of drawings]

FIG. 1 is a lens partial cross-sectional view of a video camera including an electric zoom device.

FIG. 2 is a motor drive circuit diagram of the electric mechanism.

FIG. 3 is a partial schematic diagram of FIG. 1 showing an installation example of detection means.

FIG. 4 is a partial schematic diagram of FIG. 1 showing an example of installation of detection means.

FIG. 5 is a partial schematic diagram of FIG. 1 showing an example of installation of detection means.

FIG. 6 is a partial schematic diagram of FIG. 1 showing an example of installation of detection means.

FIG. 7 is a partial plan view of FIG. 2 showing an example of installation of detection means.

FIG. 8 is a partial plan view of FIG. 3 showing an example of installation of detection means.

9 is a partial plan view of FIG.

10 is a partial front view of FIG.

11 is a partial front view of FIG.

FIG. 12 is an output signal graph of the detection means of FIG.

13 is an output signal graph of the detection means of FIG.

14 is an output signal graph of the detecting means shown in FIGS. 4 and 9. FIG.

FIG. 15 is a circuit diagram of the detection means shown in FIGS. 5 and 10.

16 is an output signal graph of the detecting means shown in FIGS. 5 and 10. FIG.

17 is an output signal graph of the detecting means shown in FIGS. 6 and 11. FIG.

FIG. 18 is a block circuit diagram for controlling a motor drive circuit based on an output signal of a detection means.

FIG. 19 is a diagram showing a cam groove and a guide groove of the zooming mechanism.
FIG.

[Explanation of symbols]

1 Focus ring 2 Zoom ring 2a Stopper pin V1 Magnification front group lens V2 Magnification rear group lens 3 Fixed barrel 3a, 3b Guide groove 4,5 Lens support 6,7 Cam pin 8 Cam ring 8a, 8b Cam groove 11 Zoom Gear 12 Friction spring 13 Motor 14 Drive gear 15 Manual operation lever 16 Slider 17 Switching plate G Grounding terminal Vcc Power supply terminal R1 Tele end resistance R2 Wide end resistance V ₀ Detecting end 18 Resistance plate RS Sliding resistance 19 Hall element 20, 20 'Iron piece 21 Light emitting element 22 Light receiving element 23, 23' Hole 24 Switch 25, 25 'Protrusion

Claims (1)

[Claims] 1. A cam ring having a cam groove for moving the lens in the optical axis direction, and a lens support having a cam pin for supporting the lens and engaging with the cam groove.
And a cam ring drive motor for rotating the cam ring, wherein the lens support is moved in the optical axis direction as the cam ring rotates to move the lens toward the tele end or the wide end. In the electric zoom device, the cam groove is formed in a direction not orthogonal to the optical axis and is provided at a first cam groove portion for moving a lens in the optical axis direction, and at a tele end or a wide end of the first cam groove portion. An extension cam groove portion which is continuously provided at a corresponding end portion and is formed in a circumferential direction of the cam ring so as not to move the lens in the optical axis direction, and the cam pin rotates in accordance with the rotation of the cam ring. Before the cam pin collides with the end portion of the extension cam groove portion based on the detection of the detection means, the detection means is provided to detect that the extension cam groove portion has been reached from the first cam groove portion. The motor is controlled so as to be stopped, and when the cam pin moves from the extended cam groove portion to the first cam groove portion, the motor is stopped based on the detection information until it is disengaged from the tele end or the wide end side. An electric zoom device characterized by being controlled so as not to be performed.