JPH08286092A - Television lens - Google Patents

Abstract

PURPOSE: To provide a load mechanism capable of being operated by a switch, etc., without imposing load such as mechanical frictional force on a lens driving system and being independent of the lens driving system by providing a gravitational movement preventive means for a lens whose rotation is magnetically regulated. CONSTITUTION: A moving screw 22 including a magnet 22a is screwed in a screw part 21c at the tip of the driving shaft 21 of a zoom driving part. An ER fluid 24c is sealed in a space interposed between electrodes 24a and 24b in the interior of a brake unit 24, and a magnetic oscillator 24d floats in the fluid 24c. By operating the switch SW and energizing the electrodes 24a and 24b, the component molecules of the fluid 24c are arranged to achieve chain- state strong coupling force. The rotation of the driving shaft 21 is changed to the straight advance of the screw 22 by the gravitational movement of the lens, and the fluid 24c becomes resistance and regulates the rotation of the driving shaft 21 through the screw 22 when the oscillator 24d tries to move.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus / zoom of a television lens, and more particularly to a television lens having a self-weight movement preventing mechanism for preventing movement of a moving lens group which occurs when the lens is tilted for use.

[0002]

2. Description of the Related Art A conventional self-movement prevention mechanism for a zoom drive unit of a television lens will be described with reference to FIG.

In the figure, reference numeral 1 is a housing that supports the entire zoom section (hereinafter referred to as a fixed frame), and includes a first moving lens group V and a second moving lens group V.
Linear groove 1a for moving the movable lens group C in the optical axis direction
On the inner diameter side, facing the linear groove 1a, the curved groove 5 _v ,
It has a curved cam 5 forming 5 _c . The moving lens groups V and C include a plurality of lenses G _V and G _C and a moving ring 2 respectively.
_v , 2 _c , a plurality of linear cam rollers 3 _v and 3 _c , and one curved cam roller 4 _v , 4 _c , and the linear cam rollers 3 _v , 3 _c are the same as those of the fixed frame 1 described above. In the straight groove 1a, the curved cam rollers _4v and _4c are formed in the curved groove 5 of the curved cam 5 described above.
_v and 5 _c are fitted together. The curved groove 5 _v , 5
_When the curved cam 5 rotates about the central axis, _c
The second moving lens units V and C are shaped like a cam so that the focal length can be changed by moving in the optical axis direction while changing their relative positional relationship.

Further, one end of the curved cam 5 is inserted into a bearing 6 held by the fixed frame 1, and the other end is also inserted into both the radial and thrust bearings 7a and 7b, and a pulley 8 is attached to the tip thereof. It is fixed by the pin 9. Further, a concave groove-shaped inner diameter portion 11 formed at the rear end portion of the drive shaft 11 whose both ends are supported by two bearings 10a and 10b held by the fixed frame 1
An output shaft 12a of a servo drive module 12 (illustrated by a chain double-dashed line in FIG. 5) is fitted in a so as to be able to transmit rotation, and a pulley 11b is integrally formed at the tip of the drive shaft 11. And is connected to the pulley 8 via the timing belt 13. On the other hand, the drive shaft 11 inserted in the fin portion 1b of the fixed frame 1 in parallel with the central axis of the curved cam 5
The friction washer 14 is inserted into the threaded portion 11c at the most distal end of the nut, and the friction washer 14 is inserted through the spring 15 into the nut 1
It is fastened and fixed to the fin portion 1b by 6a and 16b.

In the zoom driving section of the TV lens having such a structure, in order to operate the zoom, a command signal output from a remote control device (not shown) is transmitted to the servo driving module 12, and the servo driving module 12 is not shown. The motor rotates to transmit the rotation to the output shaft 12a. The output shaft 12a is fitted in the inner diameter portion 11a of the drive shaft 11 in a shape capable of transmitting rotation, for example, in the shape of corners or flat irregularities.
Pulley 11b at the tip-timing belt 13-pulley 8
~ The rotation is transmitted to the curved cam 5. The rotation of the curved cam 5 is transmitted to the movable lens groups V and C through the cam grooves 5 _v and 5 _c and the curved cam rollers 4 _v and 4 _c , but the movable rings 2 _v and 2 _{c of the} lens groups V and C are transmitted. Since the linear cam rollers 3 _v and 3 _c fixed to the guide frame are guided by the linear groove 1a of the fixed frame 1, the movable lens groups V and C move in the optical axis direction while changing their relative positions to focus. You can change the distance.

FIG. 6 shows a state in which the lens groups V and C are inclined from the horizontal by an angle θ. The weights W _v and W _{c of the} lens groups V and C, which normally work vertically downward, are different due to the inclination. The lens groups V and C are to be moved downward by a force obtained by multiplying by the sine of the tilt angle θ. When performing the zoom operation as described above, it is sufficient to give the motor a torque that overcomes this downward force. However, if the zoom position is not changed, for example, if the motor is not torqued, the lens groups V and C are arbitrarily selected. It moves downward, causing the problem of moving the focal length during shooting. This phenomenon is called lens self-weight movement. In order to prevent this self-weight movement, the nuts 16a, 16b
The tightening of the spring 15 compresses the spring 15 to generate a biasing force, which is converted into a frictional force between the friction washer 14 and the fin portion 1b of the fixed frame 1 to prevent the drive shaft 11 from rotating. .

[0007]

However, in the self-weight movement preventing mechanism as shown in the prior art, since the motion of the rotary system is forcibly stopped by the frictional force, the load of the motor as the actuator increases. However, there is a problem that the motor is damaged and the power consumption is increased. Also, the rotation of the rotary system changes the state of the friction generating surface to a direction in which it normally slides due to wear, so that the stopping frictional force decreases, and as the number of zoom operations increases, the weight movement tends to occur.

An object of the present invention is to provide a load mechanism independent of the lens drive system that can be operated by a switch or the like without applying a load such as mechanical frictional force to the lens drive system.

[0009]

According to a first aspect of the present invention, there is provided a photographing lens driving mechanism for driving force from a driving source via a power transmission means. In a television lens in which the photographing lens is moved along the optical axis by transmitting the power to the power transmission means, the power transmission means allows the power transmission from the drive source, and the rotation by the driving torque from the photographing lens drive mechanism side. A television lens is characterized in that it has means for magnetically restricting the lens from moving due to its own weight.

According to this structure, the self-weight movement preventing means is
Since it has an independent non-contact type load mechanism that can be turned on and off by a switch etc. without applying frictional load to the lens drive system, it suppresses damage to the lens driving motor and increases in power consumption when driving the lens. Therefore, it is possible to solve various problems associated with changes in the frictional contact surface when the lens is used as in the conventional case.

According to the second aspect of the present invention, in the self-weight movement preventing means having the above-described structure, in the first aspect, the self-weight movement preventing means includes a magnetic body that moves according to the rotation of the power transmission means, the magnetic body and the magnetic body. Magnetically coupled to the magnetic moving element, and the magnetic moving element is movably sealed in a viscous variable medium along the moving direction of the magnetic body, and a voltage is applied to the viscous variable medium so that the magnetic movable element is moved. It is characterized in that a fluid clutch is configured to generate a movement resistance with respect to.

According to this structure, the self-weight movement preventing means and the power transmission means of the drive source can be easily connected or disconnected by the independent operation of the magnetic fluid clutch.

According to the third aspect of the present invention, the self-movement preventing means having the above-mentioned structure is characterized in that, in the first or second aspect, the switch can be turned ON / OFF by the operation of the photographer.

With this configuration, the operating force of the manual lens drive system can be easily and quickly changed.

According to the fourth aspect of the present invention, the self-weight movement preventing means having the above structure is characterized in that the switch can be turned on / off by a remote operation of the photographer according to any one of the first to third aspects.

With this configuration, it is possible to improve the usability when the lens group is driven by a remote control device such as a demand.

According to the fifth aspect of the present invention, the self-weight movement preventing means is characterized in that, in any one of the first to fourth aspects, the contact type sensor is used for the switch operation of the photographer.

According to this structure, by incorporating a touch sensor in the remote operation unit of the demand, it is possible to reliably prevent the lens group from moving due to its own weight even when the demand is not operated.

According to a sixth aspect of the present invention, in the self-weight movement preventing means having the above-mentioned structure, the viscosity of the viscous variable medium can be continuously changed by the applied variable voltage according to any one of the first to fifth aspects. The feature is that the manual operation force can be changed by changing the load of the zoom drive system.

According to this structure, the load mechanism is always connected to the lens so that the magnitude of the load can be changed, which also serves as a mechanism for changing the lens operation force, and the operation according to the photographer's preference. It is possible to gain power.

[0021]

【Example】

[Embodiment (1)] FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is a sectional view of a main part of a focus / zoom portion of a television lens, and FIG. 2 is a circled portion in FIG. It is a principal part sectional view which expanded the part of. 2A shows a state in which the self-weight movement preventing mechanism is short-circuited, that is, a state in which the zoom operation of the lens group is possible, and FIG. 2B shows a state in which the self-weight movement preventing mechanism is connected. In FIGS. 1 and 2, the same components as those of the conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, a pulley 21b is integrally machined at the tip of the drive shaft 21, and the timing belt 13 is formed.
Is connected to the pulley 8 of the curved cam 5. Further, a magnet 22a is provided on the threaded portion 21c at the tip (illustrated by hatching in FIG. 2).
Since the moving screw 22 including the screw is screwed, and the tip end portion of the pin 23 screwed and fixed to the fin portion 1b of the fixed frame 1 is engaged with the linear groove 22b of the outer diameter of the moving screw 22. The rotation of the drive shaft 21 is converted into the linear movement of the moving screw 22. A brake unit 24 using ER fluid is fixed to the fin portion 1b of the fixed frame 1 with screws 25. The inside of the brake unit 24 has electrodes 24a, 24
The ER fluid 24c is sealed in the space sandwiched by b, and the magnetic oscillator 24d is suspended in the space.
4a and 24b are connected to the power source P and the switch SW. The magnetic oscillator 24d is magnetically connected to the magnet 22a of the moving screw 22 and advances in the ER fluid 24c as the moving screw 22 moves in the axial direction.

The operation of the self-weight movement preventing mechanism having such a structure will be described. When the photographer performs a zoom operation, the electric circuit of the self-weight movement preventing mechanism is cut off, and either the long focus position or the short focus position is set. If the zoom position is desired to be maintained, the switch SW is operated to energize the circuit. As a characteristic of the ER fluid, when sandwiched between energized electrodes 24a and 24b, the constituent molecules of the ER fluid are arranged so as to exert a strong chain-like binding force as shown in FIG. The rotation of the drive shaft 21 is moved by the self-weight movement of the moving screw 2
When the magnetic oscillating member 24d which is converted into a straight line of 2 moves to move, the ER fluid 24c becomes a resisting force and restricts the rotation of the drive shaft 21 via the moving screw 22, so that its own weight movement is prevented. Will be possible.

FIG. 3 is a graph showing the relationship between the strength of the electric field applied to the ER fluid and the apparent viscosity at that time. In order to prevent the movement of the lens group due to its own weight, a voltage at which the ER fluid exerts a viscosity sufficient to overcome it is used. It is obvious that it is better to do it, but for example, by changing the on / off switch to a volume not shown according to the characteristics of the ER fluid so that the load of the zoom drive system can be varied by always energizing it A variable mechanism of the driving force of the drive system can also be realized.

[Embodiment (2)] FIG. 4 shows a second embodiment of the present invention. Instead of the brake unit 24 using the ER fluid in the first embodiment, an electromagnetic clutch 34 using iron powder is used. The input shaft of the electromagnetic clutch 34 and the drive shaft 31.
The tip of is connected with a screw 35 and a coupling 36. The operation principle and the like in this embodiment are the same as those in the first embodiment, and therefore will be omitted.

The switch SW operated by the photographer may be mounted on the lens body, but since the lens group is usually driven by a remote control device (not shown) called a demand, the switch SW is arranged on demand. But the usability is improved. If a touch sensor (not shown) is incorporated in the demand operation unit instead of the mechanical switch, the position of the lens group can be held when the demand is not operated, and the self-weight movement can be reliably prevented.

[0027]

According to the first aspect of the present invention, the self-weight movement preventing means is an independent non-contact type load mechanism that can be turned on / off by a switch or the like without applying a frictional load to the lens drive system. As a result, damage to the motor that drives the lens and increase in power consumption when driving the lens can be suppressed, and various problems associated with changes in the frictional contact surface when the lens is used as before can be solved. it can.

According to the second aspect of the present invention, the self-weight movement preventing means and the power transmission means of the drive source can be easily connected or disconnected by the independent operation of the magnetic fluid clutch.

According to the third aspect of the present invention, the operating force of the manual lens drive system can be easily and quickly changed.

According to the fourth aspect of the invention, it is possible to improve the usability when the lens group is driven by a remote control device such as a demand.

According to the invention described in claim 5, for example, by incorporating a touch sensor in the demand remote control unit,
Even when the demand is not operated, it is possible to reliably prevent the lens group from moving due to its own weight.

According to the sixth aspect of the present invention, the load mechanism is always connected to the lens so that the magnitude of the load can be changed. It is also possible to obtain the operation force according to your taste.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a zoom drive unit and a self-weight movement prevention mechanism showing a first embodiment of the invention according to the present application.

FIG. 2 is an enlarged cross-sectional view of the self-weight movement prevention mechanism showing the first embodiment of the invention according to the present application, (a) showing a short-circuit state of the mechanism, and (b) showing a connection state of the mechanism. Indicates.

FIG. 3 is an ER showing a first embodiment of the invention according to the present application.
The graph figure which shows the viscosity characteristic of a fluid.

FIG. 4 is an enlarged cross-sectional view of a self-weight movement preventing mechanism showing a second embodiment of the invention according to the present application.

FIG. 5 is a cross-sectional view of a zoom drive unit and a self-weight movement prevention mechanism showing a conventional example.

FIG. 6 is a cross-sectional view of a zoom drive unit in a tilted state and a mechanism for preventing movement of its own weight, showing a conventional example.

[Explanation of symbols]

1 ... Fixed frame 5 ... Curved cam 8, 21b ... Pulley 9 ... Pins 11 and 21 ... Drive shaft 11a ... Inner diameter part 12 ... Servo drive module 12a ... Output shaft 13 ... Timing belt 22 ... Moving screw 22a ... Magnet 24 ... Brake unit 24a, 24b ... Electrode 24c ... ER fluid 24d ... Magnetic oscillator 25 ... Screw

Claims (6)

[Claims] 1. A television lens for moving a photographing lens along an optical axis by transmitting a driving force from a driving source to a photographing lens driving mechanism via a power transmitting means, wherein the driving source is provided in the power transmitting means. A television lens having means for preventing movement of its own weight by allowing the transmission of power from the lens and magnetically restricting rotation due to drive torque from the photographing lens driving mechanism side. 2. The self-weight movement preventing means according to claim 1, wherein the magnetic body moves in accordance with the rotation of the power transmission means, a magnetic moving element magnetically connected to the magnetic body, and a moving direction of the magnetic body. And a magnetic clutch that movably seals the magnetic moving element in a viscous variable medium, and applies a voltage to the viscous variable medium to generate a moving resistance with respect to the magnetic moving element. TV lens to do. 3. The weight movement prevention means according to claim 1 or 2, wherein the switch is turned on / off by a photographer's operation.
A TV lens characterized by being capable of 4. The television lens according to claim 1, wherein the own weight movement preventing means can be turned on and off by a remote operation of a photographer. 5. The television lens according to claim 1, wherein the self-weight movement preventing means uses a contact sensor for a switch operation of a photographer. 6. The self-weight movement preventing means according to claim 1, wherein the viscosity of the viscous variable medium is continuously changed by an applied variable voltage, and a manual operation is performed by changing a load of the zoom drive system. A TV lens featuring variable power.