JPH0678187A - Rotation braking device for view finder in television camera - Google Patents

Abstract

PURPOSE:To generate strong braking force and to always maintain the braking force at a set state by converting torque obtained from an operation lever into the pressing force of a brake shoe to a brake disc through a cam mechanism. CONSTITUTION:A fixed pin 5 is calked by a sleeve 6 so as to properly set up the torque of the operation lever 10. When the lever 10 is rotated in the (a) direction, a cam drive 11 is rotated in the (c) direction, the tapered face 10a of the cam drive 11 is engaged with the tapered part 13a of a cam 13 and the cam 13 is displaced in the axial direction of the fixed pin 5. Since down force is applied to the brake shoe 2, 3 in accordance with the rotational frequency of the lever 10 through the drive 11 and the cam 13, proper frictional force is generated between the brake and a rotary disc 1 by properly adjusting the rotational frequency of the lever 10. Thereby appropriate braking force is properly applied to a view finder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary brake device for a viewfinder of a television camera.

[0002]

2. Description of the Related Art A television camera for a broadcasting station has a camera head and a viewfinder for displaying a subject image, and the viewfinder is rotatably connected to the camera head through a rotating mechanism. In this television camera for broadcasting stations, it is necessary to apply an appropriate braking force to the rotating mechanism of the viewfinder so that the viewfinder does not easily rotate and move due to a slight external force.

As a rotary brake device of a viewfinder, for example, a brake mechanism described in Japanese Patent Publication No. 2-19791 is known. With this known braking mechanism,
A shaft is attached to the rotating part fixed to the viewfinder side, a brake piece is screwed onto this shaft, and the brake lever 15 is vertically displaced by rotating the operation lever connected to the shaft. There is. Then, the brake piece is brought into contact with the flange portion of the fixed base, and the braking force is generated by utilizing the frictional force generated between the brake piece and the flange portion of the fixed base.

[0004]

In the known brake mechanism described above, the brake piece is screwed onto the shaft, and the brake piece is moved up and down by the rotation of the shaft, so that the braking force generated in the rotating mechanism is small. , It was not possible to generate a sufficiently large braking force. In particular, since the brake piece is in contact with only one surface of the flange of the fixed base, the contact area for generating the frictional force is small, and the sufficient braking force cannot be generated. Further, since the brake piece is screw-connected to the shaft and moves up and down, the brake piece also rotates about the shaft due to the rotational displacement of the rotating portion, and as a result, the braking force changes as the photographing work progresses. There was also a defect.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, to generate a sufficiently strong braking force, and at the same time, to maintain the braking force in a preset state without changing the braking force. An object of the present invention is to provide a rotary brake device for a viewfinder of a John camera.

[0006]

According to the present invention, there is provided a rotary brake device for a viewfinder of a television camera, a brake disc fixedly connected to a rotary base of the viewfinder, a base member fixedly connected to a camera head, and the base. A first brake shoe fixed on the member, a support fixed to the base member, an operation lever rotatably connected to the support, a cam driver connected to the operation lever, and the support for the base member. A cam that is movably connected in the axial direction and that constitutes a cam mechanism that cooperates with the cam driver, a second brake shoe that is fixed to the cam and that faces the first brake shoe, and the brake disc. And a stopper member that prevents the brake disc from being displaced in the rotation direction of the brake disc caused by the rotation of the brake disc. To.

[0007]

The rotating force of the operating lever is converted into downward pressing force via the cam mechanism and acts on the brake shoes. During the conversion by the cam mechanism, the turning force of the operating lever is converted into a stronger downward force, so that a strong braking force can be generated. Further, since the cam that constitutes the cam mechanism is prevented from moving in the rotation direction of the rotating disc by the stopper, no matter which direction the rotating disc rotates due to the rotation of the viewfinder, the braking force is always constant. Can be maintained.

[0008]

1 to 6 show the structure of an example of a viewfinder rotary brake device for a television camera according to the present invention. FIG. 1 is a plan view and FIG. 2 is a sectional view taken along the line II of FIG. 3 is a sectional view taken along line II-II of FIG. 1, FIG. 4 is a front view,
FIG. 5 is a plan view showing the operation lever main body without showing it, and FIG. 6 is a partially exploded perspective view. First and second brake shoes 2 in which the peripheral edge of a brake disc 1 fixedly connected to a viewfinder side turntable is mounted on the camera head side.
And 3 are gripped from both sides, and an appropriate braking force is generated for the viewfinder by the frictional force generated between the brake disc 1 and the brake shoes 2 and 3.
The braking device comprises a base member 4 fixedly connected to the camera head. As shown in FIG. 2, the fixing pin 5 is fixed to the base member 4, and the sleeve 6 is joined to the fixing pin by caulking. An operation lever body 9 is rotatably connected to the sleeve 6 via spacers 7 and 8 made of Duracon. This operation lever body 9 is an operation lever 10
And the cam do live 11 are integrally connected. Therefore, as shown in FIG.
Alternatively, when the cam drive 11 is rotated in the b direction, the cam drive 11 is also rotationally displaced in the arrow c or d direction. At this time, the fixing pin 5 is crimped onto the sleeve 6 so that the turning force of the operating lever 10 becomes appropriate. That is, by crimping, an appropriate braking force is applied to the operation lever to prevent the operation lever from being rotationally displaced during the image pickup operation. As shown in FIGS. 2, 3 and 6, another fixing pin 12 is fixed to the base member 4, and a cam 13 is vertically movably connected to this fixing pin. A spring 14 is interposed between the fixed pin 12 and the cam 13 to constantly push the cam 13 upward. As shown in FIG. 4, the cam drive 10 and the cam 13 have tapered surfaces 10a and 13a, respectively, and these tapered surfaces engage with each other to form a cam mechanism. That is, as the operation lever 10 rotates in the a direction, the cam drive rotates in the direction of the cam drive 10 to c, the tapered surface 10a of the cam drive engages with the taper 13a of the cam 13, and the cam 13 moves in the axial direction of the fixing pin. That is, it is displaced downward. That is, the rotational force of the operating lever is
The cam mechanism composed of 10 and the cam 13 converts it into a downward force. On the other hand, when the operation lever is rotated in the direction of arrow b, the cam drive rotates in the direction of arrow d, and the engagement between the tapered surfaces 11a and 13a is released. Cam 13
The second brake shoe 3 is fixed to the opposite side of the tapered surface 13a of the above, and the rotary disc 1 is held between the first brake shoe 2 and the second brake shoe 3. Therefore, a downward force acts on the second brake shoe 3 via the cam driver 11 and the cam 13 in accordance with the amount of rotation of the operation lever 10, so that by appropriately adjusting the amount of rotation of the operation lever, Appropriate frictional force is generated between the rotating disc 1 and the first and second brakes, and as a result, an appropriate braking force can be applied to the viewfinder. The gap between the brake shoe 2 and the brake disc 1 is set to be almost zero. Even in such a state, since no force is applied from the brake shoe 3, even if the brake shoe 2 and the brake disc 1 rub against each other, braking is hardly applied.

Since the brake disc 1 fixedly connected to the viewfinder side rotates in accordance with the movement of the brake of the viewfinder, it is necessary to set the cam 13 so that it cannot be displaced even if the brake disc 1 rotates. That is, the cam 13 moves in the direction of the arrow c as the brake disc rotates.
Alternatively, when the brake disc is displaced in the d direction, the braking force generated on the brake disc changes. Therefore, in the present invention, as shown in FIG.
As shown in FIG. 6, a concave portion is formed in the base member 4, and a U-shaped stopper member 15 is fitted into the concave portion and then fixed by screws, and two posts 15a of the stopper member 15 and
The cam 13 is configured so as not to be displaced in the direction of arrow c or d by 15b. Therefore, the cam 13 can be displaced only in the vertical direction.

Next, the relationship between the stroke amount of the operating lever and the braking force will be described. FIG. 7 is a schematic diagram for explaining the force generated in the brake shoe. A horizontal force is applied to the cam drive 11 by rotating the operation lever 10.

[Outer 1] Occurs, and this [outer 1] causes the cam 13 to

[Outside 2] If the vertical force of is to be applied, the following equation holds.

[Equation 1] If the force pushing the lever is F, then H = (l ₁ / l ₂ ) ×
It becomes F. Here, α is the taper angle of the tapered surface of the cam drive and the cam. Also, the distance from the fulcrum of the operating lever 10 to the working point is l ₁ , the distance from the fulcrum to the working point of the cam is l ₂ , the stroke of the operating lever is S _r , the stroke of the cam driver is S _k , and the cam brake brake If the stroke of pressing is S _b , the following equation holds.

## EQU00002 ## S _k = (l ₂ / l ₁ ) × S _r S _b = S _k × tan α Here, if the taper angle is set to 6 ° and l ₂ / l ₁ = 1/2, for example,

[Equation 3] Becomes Therefore, if the operating lever is operated with a force of 500 g, a pressing force of 9.5 kg acts on the brake shoe, and as a result, a large braking force can be obtained with a slight operating force. If the stroke length of the operating lever is set to 3.0 cm, the stroke length of the brake shoe will be about 1.6 mm. Therefore, according to the present invention, it is possible to achieve an extremely beneficial action and effect that is small and can generate a large braking force. On the other hand, as described above, since the appropriate braking force is applied to the operation lever, it is possible to avoid the disadvantage that the operation lever is rotationally displaced and the braking force is changed.

The present invention is not limited to the above-described embodiments, but various changes and modifications can be made. For example, in the above-described embodiment, the cam mechanism is configured by forming the cam drive and the tapered surface that engages with the cam, but the cam mechanism having various configurations can be applied. The cam mechanism can also be configured by a combination with a matching tapered surface.

[0012]

As described above, according to the present invention, the turning force from the operating lever is converted into the pressing force against the brake disc of the brake shoe via the cam mechanism, so that even a relatively weak operating force is used. A strong braking force can be generated. Also, set the cam that generates pressing force against the brake shoe so that it can be displaced only in the vertical direction,
Since it is set so as not to move in the rotating direction of the brake disc, a constant braking force can be continuously applied even if the viewfinder and therefore the brake disc rotate.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of an example of a brake device of a viewfinder of a television camera according to the present invention.

FIG. 2 is a sectional view taken along line I-I of FIG.

3 is a sectional view taken along line II-II in FIG.

FIG. 4 is a front view.

FIG. 5 is a plan view showing the operation lever body with the body removed.

FIG. 6 is a partially exploded perspective view showing a stopper member and members related thereto.

FIG. 7 is a schematic diagram illustrating a relationship between a stroke amount of an operation lever and a braking force.

[Explanation of symbols]

 1 Brake Disc 2, 3 Brake Shoe 4 Base Member 5 Fixing Pin 6 Sleeve 7, 8 Spacer 10 Control Lever 11 Cam Drive 13 Cam 14 Spring 15a, 15b Stopper

Claims (2)

[Claims] 1. A brake disc fixedly connected to a turntable of a viewfinder, a base member fixedly connected to a camera head, a first brake shoe fixed on the base member, and a support fixed to the base member. An operating lever rotatably connected to the column, a cam driver coupled to the operating lever, and a cam mechanism that is arranged movably in the axial direction of the column with respect to the base member and cooperates with the cam driver. A constituent cam, a second brake shoe that is fixed to the cam and faces the first brake shoe, and displacement of the brake disc in the rotational direction of the cam that accompanies the rotation of the brake disc is prevented. A rotary brake device for a viewfinder of a television camera, which is provided with a stopper member. 2. The television camera according to claim 1, wherein the cam driver and the cam each have a tapered surface that engages with each other and is inclined with respect to a plane orthogonal to the axis of the column. Viewfinder rotary brake device.