JPS6259957B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical device for a color television camera, and aims to reduce color shift.

Generally, in a color television camera, as shown in Fig. 1, photographic light passing through a photographing lens 1 is separated into three color signals by a three-color separation prism 2, and each color signal is sent to each imaging member (imaging tube). (coil assembly type) 3 to 5, which converts the signal into an electrical signal.

However, in the conventional optical device of this kind, a three-color separation prism 2 is glued inside a box 6 made of a sturdy cast alloy, and a prism base having a coefficient of thermal expansion similar to that of the prism material is screwed and housed. box 6
Imaging members 3 to 5 are attached to the outer wall of the building. Therefore, due to the expansion (or contraction) of the three-color separation prism 2 and the box 6 due to changes in ambient temperature, a mutual display shift occurs between the red channel and the blue channel, resulting in a color shift between red and blue. appears in

When the three-color separation prism 2 expands as shown by the two-dot chain line in FIG. On the blue channel side, it moves towards the head. Therefore, the shift amount is L _R
1 , L _B1 , then L _R1 +L _B1 is the color shift based on the expansion of the three-color separation prism 2.

When the box 6 expands as shown by the two-dot chain line in FIG. 3, the points Rp and Bp (the intersection of the designed optical axis and the outer wall of the box) are considered to move to the points Rp' and Bp'. The sum of the moving amounts L _R2 and L _B2 becomes the color shift based on the expansion of the box 6.

Generally, the box 6 is made of magnesium alloy or aluminum alloy to reduce weight and cost. Therefore, the optical axis shift amounts L _R2 and L _B2 due to changes in the ambient temperature are considerably larger than the optical axis shift amounts L _R1 and L _B1 of the three-color separation prism 2.

Therefore, the sum of the optical axis shifts due to the expansion of the three-color separation prism 2 and the box 6 is the total color shift,
The amount is (L _R2 -L _R1 )+(L _B2 -L _B1 ).

The present invention aims to reduce the above-mentioned color shift, and is a device in which each of the light beams emitted from each exit surface of a color separation prism is received by an imaging member, and each prism block constituting the color separation prism is are connected together on the common surface of the prism stand, while
An optical system for a color television camera, characterized in that an imaging member is supported by each independent support member connected to an outwardly extending portion of the prism base so that its light receiving surface faces each exit surface of a color separation prism. The gist is the device.

Figures 4 and 5 show an embodiment in which a three-color separation prism stand 8 (a member that connects three glass blocks constituting the prism 2 together) is extended to the exit surface side of the prism. Support walls 8a, 8b, 8c are provided at the portions so as to face the light exit surface of the prism 2.
is formed, and the imaging members 3 to 5 are independently attached to this support wall directly in close proximity to the prism exit surface.

Since the optical device of the present invention has the above structure, expansion (or contraction) of the box 6 has no effect on the optical axis shift. Therefore, the optical axis shift due to changes in ambient temperature is reduced, and the above-mentioned objective of reducing color shift is well achieved.

Further, according to the present invention, when a failure occurs in the imaging member, it is possible to replace only the failed imaging member, and there is no need to replace the entire prism. Furthermore, it is possible to increase the degree of freedom in adjusting the position, angle, etc. of the imaging member with respect to the light emitted from the trichromatic prism.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a conventional optical device for a color television camera, Fig. 2 is a plan view of a three-color separation prism,
FIG. 3 is a plan view of the box, FIG. 4 is a plan view of an embodiment of the optical device for a color television camera of the present invention, and FIG. 5 is a side view thereof. 1 is a photographic lens, 2 is a three-color separation prism, 3~
5 is an imaging member, 6 is a box, 7 is a subject image, 8
is a three-color separation prism stand.

Claims (1)

[Claims] 1 A device in which each of the light beams emitted from each exit surface of a color separation prism is received by an imaging member, in which each prism block constituting the color separation prism is integrally connected by a common surface of a prism stand, and the prism stand is 1. An optical device for a color television camera, characterized in that an imaging member is supported by independent supporting members connected to the outwardly extending portions so that the light-receiving surface faces each exit surface of a color separation prism.