JPH09149299A - Television lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability of a television camera by a cameraman by providing a balance weight member moved forward/backward in parallel with an image pickup optical axis of the television lens system and moving the balance weight member so as to cancel the movement of gravity center of the television lens system due to movement of at least a focus lens or a zoom lens thereby preventing movement of the gravity center. SOLUTION: A balance weight 40 is arranged in parallel with an image pickup optical axis 30 of a television lens system 12 in forward/backward directions freely. A motor 42 is arranged to move the balance weight 40. The motor 42 is driven by a CPU so that the balance weight 40 is moved to cancel movement position of the gravity center. For example, when a focus lens 32 is moved forward and the gravity center of the television lens system 12 moves forward, the balance weight 40 is moved backward to cancel the movement of the gravity center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television lens device, and more particularly to a box-type television lens device used in field cameras and studio cameras.

[0002]

2. Description of the Related Art Conventionally, a TV lens device of this type has been used by being mounted on a pan head, and a focus lens is moved back and forth along a photographing optical axis for focusing, and a zoom lens is arranged on a photographing optical axis. Move back and forth along it to change the shooting magnification.

[0003]

However, in the conventional TV lens device, the center of gravity of the TV lens device moves when the focus lens or the zoom lens moves, so that the balance of the TV lens device on the platform is lost. Therefore, there is a drawback that the pan / tilt operability for the cameraman is deteriorated.

Especially, the focus lens is heavy (3 kg
Since the focus lens is usually arranged in the front part of the TV lens device, the center of gravity of the TV lens device largely moves even if the focus lens moves a little. For example, if you try to focus on a close-up subject from the state of focus at infinity, the focus lens located at the rear end position will move toward the front end position, and the load due to the movement of the center of gravity at this time will occur. However, there is a drawback in that camera work becomes very difficult because it is suddenly applied to the cameraman.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a television lens device capable of improving the operability of a television camera by a cameraman.

[0006]

In order to achieve the above-mentioned object, the present invention is a focus for panning and tilting operation on a pan head, and for moving the lens back and forth along a photographing optical axis for focusing. In a television lens device including a lens and a zoom lens that is moved back and forth along a shooting optical axis to change a shooting magnification, a balance weight member that moves back and forth in parallel with the shooting optical axis is provided, and the balance weight member is provided. It is characterized in that the weight member is moved so as to offset the movement of the center of gravity of the television lens device due to the movement of at least one of the focus lens and the zoom lens.

According to the present invention, the balance weight member is arranged in the television lens device, and the balance weight member is moved so as to cancel the movement of the center of gravity of the television lens device due to the movement of at least one of the focus lens and the zoom lens. . Accordingly, in the present invention, the center of gravity does not move even if the focus lens or the zoom lens moves, so that the operability of the television camera by the cameraman is improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a television lens device according to the present invention will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a side view of a television camera to which a television lens device according to an embodiment of the present invention is applied. The television camera 10 shown in the figure comprises a television lens device 12 and a camera 14 according to an embodiment of the present invention, and is fixed on a tripod head 18 fixed on a tripod 16 via a lens support 20. There is. A pan stick 22 is extended on the pan head 18, and a cameraman grips a grip 24 formed at the tip of the pan stick 22 to move the pan camera 22 in the left-right and up-down directions. A pan / tilt operation is performed by 18. Reference numeral 26 is a viewfinder of the camera 14, and reference numeral 28 is a zoom demand.

FIG. 2 is a side sectional view showing the internal structure of the television lens device 12. As shown in the figure, in the television lens device 12, a focus lens 32, a variator lens 34 and a compensator lens 36 forming a zoom lens are sequentially arranged from the front of the photographing optical axis 30 toward the rear. The focus lens 32 has a photographing optical axis 3
It is provided so as to be movable back and forth along 0, and is moved back and forth by a drive mechanism (not shown) to perform focusing. Similarly, the variator lens 34 and the compensator lens 36 are also provided so as to be movable back and forth along the photographing optical axis 30 and approach each other by a drive mechanism (not shown) driven by the operation of the zoom demand 28 shown in FIG. Alternatively, they are moved in directions away from each other to change the photographing magnification.

On the other hand, the TV lens device 12 has a built-in gravity center canceling mechanism 38 of the TV lens device 12. The center-of-gravity canceling mechanism 38 includes a balance weight 40.
And a motor 42 for moving the balance weight 40 and the like. As shown in FIGS. 2 and 3, the balance weight 40 has a through hole 4 parallel to the photographing optical axis 30.
4 is formed, and is supported so as to be movable back and forth in parallel with the photographing optical axis 30 along a guide shaft 46 inserted and arranged in the through hole 44. The guide shaft 46 has a front end 46A fixed to a front plate 48 and a rear end 46B fixed to and supported by a rear plate 50.

A screw hole 52 is formed through the balance weight 40 in parallel with the through hole 44. A screw rod 54 is screwed into the screw hole 52, and a front end 54 </ b> A of the screw rod 54 has the front plate 48.
The rear end 54B is connected to the spindle 58 of the motor 42 through a through hole 56 formed in the rear plate 50.

As a result, when the screw rod 54 is normally / reversely rotated by the driving force of the motor 42, the balance weight 40 is moved back and forth along the photographing optical axis 30 by the action of the screw hole 52 and the screw rod 54. Moving. FIG. 4 is a block diagram showing a drive control system of the center-of-gravity canceling mechanism 38. The TV lens device 12 has a built-in CPU 60,
U60 drives and controls the motor 42 based on signals from the focus position detector 62 and the zoom position detector 64. The balance weight 40 is moved by the driving force of the motor 42, and the balance weight 40 is positioned at a predetermined center-of-gravity offset position.

The focus position detector 62 detects the moving position of the focus lens 32 (see FIG. 2) and outputs the position information to the CPU 60, and the zoom position detector 64 moves the zoom lenses 34 and 36. The position is detected and the position information is output to the CPU 60. The CPU 60
Stored in advance is information indicating the basic center of gravity of the television lens device 12. The basic center of gravity is the center of gravity of the focus lens 32 and the zoom lenses 34, 36 at the most frequently used moving position.

Next, the operation of the center-of-gravity canceling mechanism 38 of the television lens device 12 constructed as described above will be described.
From at least one of the focus position detector 62 and the zoom position detector 64 shown in FIG. 4, the position information of the focus lens 32 and the position information of the zoom lenses 34 and 36 are stored in the CPU.
When output to the CPU 60, the CPU 60 calculates the center of gravity of the television lens device 12 based on the position information.

Then, the CPU 60 compares the calculated center of gravity with the previously stored basic center of gravity. When the calculated center of gravity moves with respect to the basic center of gravity, the CPU 60 drives and controls the motor 42 to offset the center of gravity shift, and moves the balance weight 40 to the center of gravity offset position. For example, the focus lens 32
When the center of gravity of the television lens device 12 moves forward with respect to the basic center of gravity, the balance weight 4 is interlocked with the movement of the focus lens 32.
By moving 0 to the rear, the television lens device 12
Offset the movement of the center of gravity of. When the focus lens 32 moves backward, the balance weight 40 is moved forward to cancel the movement of the center of gravity. In addition, the zoom lens 34,
The same applies to the case of 36. When the center of gravity of the television lens device 12 moves with respect to the basic center of gravity by the movement of the zoom lenses 34, 36, the balance weight 40 is interlocked with the movement of the zoom lenses 34, 36. It is sufficient to move the lens device 12 so as to offset the movement of the center of gravity.

Therefore, in the embodiment of the present invention, since the center of gravity of the television lens device 12 does not move even if the focus lens 32 and the zoom lenses 34 and 36 move, the operability of the television camera by the cameraman can be improved. it can.

[0017]

As described above, according to the television lens device of the present invention, the balance weight member is arranged,
The balance weight member is moved so as to offset the movement of the center of gravity of the television lens device due to the movement of at least one of the focus lens and the zoom lens. Therefore,
In the present invention, the center of gravity of the television lens device does not move even if the focus lens or the zoom lens moves, so that the operability of the television camera by the cameraman can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a television camera to which a television lens device according to the present invention is applied.

FIG. 2 is an internal structural diagram of the television lens device shown in FIG.

3 is a perspective view showing a structure of a center-of-gravity canceling mechanism of the television lens device shown in FIG.

FIG. 4 is a block diagram showing a control system of a center-of-gravity canceling mechanism of a TV lens device.

[Explanation of symbols]

 10 ... TV camera 12 ... TV lens device 14 ... Camera 18 ... Platform 32 ... Focus lens 34, 36 ... Zoom lens 38 ... Center of gravity cancellation mechanism 40 ... Balance weight 42 ... Motor 54 ... Screw rod 60 ... CPU 62 ... Focus position detection Device 64 ... Zoom position detector

Claims (1)

[Claims] 1. A focus lens which is mounted on a platform so as to be capable of pan / tilt operation, and which is moved back and forth along a shooting optical axis for focusing, and a focus lens which is moved back and forth along the shooting optical axis to adjust a shooting magnification. In a television lens device including a variable zoom lens, a balance weight member that moves back and forth in parallel with the photographing optical axis is provided, and the balance weight member is moved by at least one of the focus lens and the zoom lens. A television lens device, wherein the television lens device is moved so as to offset the movement of the center of gravity of the television lens device.