JPS58108889A - Frequency separating type single bulb color camera - Google Patents

Abstract

PURPOSE:To obtain a frequency separating single-bulb color camera which has improved balance between an R signal and a B signal output after color separation, by combining an image pickup tube with a focusing coil which generates a focusing magnetic field directed from an electron gun side to a target side. CONSTITUTION:The focusing magnetic field 6' is applied at right angle to a scanning surface, so an electron beam running in the orthogonal field of this electric field is applied with vertical force. Namely, the electron beam is applied with force to right when the magnetic field faces as shown by 6 in a figure, or to left when the magnetic field faces as shown by 6'. Consequently, the beam lands at a target in a right declining ellipse ink the former case or in a left decliing ellipse in the latter case. Therefore, the R signal output and B signal output are held at nearly the same level. Thus, an error in color separation is reduced and the color S/N ratio is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency-separated single-tube color camera incorporating a cross-type stripe filter, and in particular to a frequency-separated single-tube color camera that improves the balance between R signal output and B signal output after color separation. The purpose is to provide a tube color camera.

In a frequency-separated single-tube color camera, if the spectral sensitivity characteristics are equal, the levels of the R output signal and B output signal are equal and high when red light and blue light of the same brightness are applied. /N is desirable. However, the beam shape changes from a perfect circle to a distorted shape due to self-sharpening effects and beam bending effects. Therefore, a frequency-separated single-tube color camera using crossed stripe filters has a drawback in that the levels of the R output signal and the B output signal are different.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks and provide a frequency-separated single-tube color camera that improves the balance between R signal output and B signal output. MM type image pickup tube) and electromagnetic focusing
It can be applied to both electrostatic deflection type image pickup tubes (hereinafter referred to as MS type image pickup tubes). The feature is that the MM type image pickup tube or MS type image pickup tube of the present invention is combined with a focusing coil that generates a focused magnetic field directed from the electron gun side to the target side. By adopting such a configuration, it is possible to improve the balance between the R signal output and the B signal output of a frequency-separated single-tube color camera with a built-in cross-type stripe filter. The present invention will be explained in detail below using an example of an MS type image pickup tube.

As a result of investigating the beam shape of the MS type image pickup tube, the following facts were found. That is, it has been found that the beam shape is different when the direction of the focused magnetic field is changed from the target side to the electron gun side in the MS type image pickup tube, and when the direction is changed from the electron gun side to the target side. Of course, when the focusing magnetic field is reversed, the deflection direction is reversed, so the deflection electric field is also reversed. Fig. 1 shows a schematic diagram of the MS type image pickup tube and the focusing coil, and Fig. 2 shows the measurement results of the beam shape when changing the direction of the focusing magnetic field.

In addition, RCA p3o is used to measure the beam shape.

I used a chart. In Figure 1, 1 is an electron gun section consisting of a cathode electrode, a G1 electrode, and a G2 electrode, 2 is a deflection electrode that generates an electrostatic deflection electric field, 3 is a mesocye electrode, and 4 is a photoelectric film, a transparent electrode, a stripe filter, etc. 6 is a focusing coil, and 6 and 6' are focusing magnetic fields. In Figure 2, the direction of the focused magnetic field is the first
The beam shape in the case of FIG. 6 is the beam shape when the direction of the focusing magnetic field is e' in the figure. The reason why the beam shape changes as shown in FIG. 2 depending on the direction of the focused magnetic field is considered to be as follows.

When there is no beam bending in the beam on the target, current flows only at the leading edge due to the self-sharpening effect. If we consider the case where the beam scans from the upper left to the lower right, it is known that the beam shape will appear to be crescent-shaped, descending to the left. Next, consider the beam hentir effect. If there is no self-sharpening effect, the surface potential after scanning of the beam and the surface potential before scanning are different, and an electric field is generated in the vertical direction due to the potential difference. In the absence of a magnetic field, the electric field bends the shimiko beam downward and causes it to land. Therefore, the beam shape is deformed into an ellipse extending in the vertical direction. In the case of an MS type image pickup tube (or MM type image pickup tube), since a focusing magnetic field is applied perpendicularly to the scanning plane, electron beams passing through a field perpendicular to this electric field are subjected to forces in directions perpendicular to each other. That is, when the magnetic field is oriented as 6 in FIG. 1, the force is applied to the right side, and when the magnetic field is oriented 6' in FIG. 1, the force is applied to the left side.

As a result, in the case of a magnetic field of 6, it lands on the target in an elliptical shape descending to the right, and in the case of a magnetic field of 6', it lands in an elliptical shape descending to the left. Therefore, when the self-sharpening effect and the beam bending effect are combined, beam shapes as shown in FIG. 2 are obtained.

In the third part, we tried to find the level of the output signal obtained by the stripe filter in the case of such a beam shape.
It is a diagram. The horizontal axis represents the angle from the y-axis, and the vertical axis represents the degree of modulation. 3(a) is the case where the beam shape is as shown in FIG. 2(-), and FIG. 3(b) is the case where the beam shape is as shown in FIG. 2(b). In the figure, A is the actual angle of the stripe filter on the lower right, and B is the angle of the stripe filter on the lower left. It can be seen from this figure that the beam shape shown in FIG. 2 (-) provides R and B signal outputs of the same level. The beam shape shown in FIG. 2 (-) is obtained when the focusing magnetic field is directed from the electron gun side to the target side.

As described above, the present invention provides a frequency-separated single-tube color camera using a crossed stripe filter.
It is characterized by using a focusing coil that generates a focusing magnetic field from the electron gun side to the target side in the type image pickup tube or MS type image pickup tube, and as a result, the level of the R signal output and the B signal output is This has the effect of making it possible to maintain the same level. As a result, it is possible to reduce color separation errors and improve color S/N.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the principle of a frequency-separated single-tube color camera according to an embodiment of the present invention, Figure 2 is a diagram showing an example of beam shape measurement, and Figure 3 is the angle of the stripe filter from the y-axis and the signal output. FIG. 1... Electron gun section, 2... Deflection electrode, 3
...Metshi electrode, 5...Focusing coil,
6,6'...Focusing magnetic field.

Claims (1)

[Claims] Equipped with a frequency-separated image pickup tube that incorporates a cross-type stripe filter, this image pickup tube is configured as an electromagnetic focusing-electromagnetic deflection type or an electromagnetic focusing/electrostatic deflection type, and the direction of the focused magnetic field is directed from the electron gun side to the target side. A frequency-separated single-tube color camera characterized by the use of a focusing coil that generates a focusing magnetic field.