JPS6110396Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an image pickup tube device with improved magnetic shielding.

In recent years, dichroic prisms have been widely used as color separation optical systems used in color television camera devices. In a color television camera using such a color separation optical system, the spatial arrangement of the optical system and image pickup tube is as shown in FIG.

That is, 11 is an imaging lens, 12 is a dichroic prism, and 13, 14, and 15 are imaging tubes for red, green, and blue, respectively. Since the image pickup tubes 13, 14, and 15 are thus arranged radially and have different directions, the influence of the earth's magnetism on each of the image pickup tubes 13, 14, and 15 is different.

Therefore, when a television camera is panned or tilted, each image pickup tube receives a different amount of change in the geomagnetic field, resulting in a shift in the images taken from each image pickup tube, and a difference in the quality of the image being played back on the TV screen. This results in color shift and is very unsightly.

In order to solve these drawbacks, conventionally, each image pickup tube has been magnetically shielded.

Here, a structure for magnetically shielding the image pickup tube will be explained with reference to FIG.

21 is an image pickup tube made of, for example, a vidicon; 22
2 is a deflection coil, and 23, 24, and 25 are made of permalloy, and together they form a magnetic shielding container for the image pickup tube 21.

Reference numeral 26 denotes an opening formed in the container 23, through which the subject image is transmitted to the front surface of the imaging tube 21.
7 to the target 28.

Further, the object image formed on 28 is taken out to the outside as a corresponding electric signal.

According to the above configuration, the external magnetic field is bypassed by the shield containers 23, 24, and 25, and the external magnetic field reaching the inside of the imaging tube can be extremely reduced.

However, since the front surface of the shield container is provided with an opening 26, the external magnetic field enters through this opening, and the external magnetic field cannot be sufficiently attenuated in the vicinity of the target 28.

For example, near the target 28, the degree of attenuation was about 1/2 to 1/3 compared to the external magnetic field.

The deviation of the imaging screen due to the external magnetic field component remaining near the target is 0.1% to 0.2% of the screen height.
Although the difference is small, if high-performance image quality is required, even the above-mentioned deviation cannot be ignored.

In order to eliminate this deviation, it is conceivable to increase the distance d between the opening 26 of the container and the target electrode 28, but due to the back focus of the optical system, it is not possible to select an arbitrary length, and if the distance d is increased, , it will also increase in length.

The present invention provides an image pickup tube device that solves the above-mentioned drawbacks.

An embodiment of the present invention will be described with reference to FIG.

31 is an imaging tube; 32 is a deflection coil for deflecting the electron beam within the imaging tube; 33 is a cylindrical container; 34 is a dish-shaped container having an outer shape that gradually becomes smaller in diameter and has an opening 35 in the center; This is a dish-shaped container that seals the end of a cylindrical container 33.

The containers 33, 34, and 36 together form a shield container that houses the image pickup tube 31 and the deflection coil 32.

As shown in detail in FIG. 3b, 37 is a shield wall integrally formed with the container 34 so as to surround the opening 35 of the dish-shaped container 34, and whose tip protrudes forward. This shield wall 37 is dimensioned to extend to the side of the optical system 38 located in front of the image pickup tube 31.

Further, 39 is the target of the image pickup tube 31,
The object image formed here is extracted to the outside from the signal extraction electrode.

With the above-described configuration, the distance d between the tip of the shield wall 37 and the target 39 can be made large, and the amount of external magnetic field penetrating into the vicinity of the target 39 of the image pickup tube 31 can be made very small.

For example, when the length of the shield wall is set to 10 mm, the magnitude of the external magnetic field near the target will be attenuated to about 1/3 of that without the shield wall, and the screen deviation will be reduced to about 1/2. was.

In the above-mentioned embodiment, the case where the shield wall surrounds the opening in a rectangular shape has been explained, but when the shield wall has three sides as shown in figure a of FIG. A predetermined shape can be selected depending on the shape of the optical system, the magnitude of the external magnetic field, etc.

Further, when the end of the optical system is circular, it is more effective to form the shield wall in an arc shape along the outer periphery of the optical system.

As described above, according to the present invention, an image pickup tube device that is less affected by external magnetic fields can be realized.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the configuration of a color camera, FIG. 2 is a diagram showing a conventional image pickup tube device, FIG. 3 is a diagram showing an embodiment of the image pickup tube device of the present invention, and FIG. 4 is a diagram of the present invention. It is a figure showing other examples of the shield wall concerning this. 31... Image pickup tube, 32... Deflection coil, 33,
34, 36... Shield container, 37... Shield wall, 38... Optical system.

Claims (1)

[Scope of utility model claims] An image pickup tube that converts a subject image into an electrical signal, a deflection device located around the image pickup tube, and a dish-shaped device that houses the deflection device and the image pickup tube inside and gradually becomes smaller in diameter in front of the target of the image pickup tube. a shield container having an opening formed in the center for introducing a subject image, an optical system located in front of the opening of the container, one end mechanically connected to the dish-shaped portion of the shield container, and the other end and a magnetic shield wall extending to the side of the optical system.