JP3136848B2 - Color separation prism device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color separation prism device used in an optical system of a three-panel camera such as a video movie and a video camera.

[0002]

2. Description of the Related Art In recent years, with the spread of video movies and video cameras, demands for higher image quality have been increasing more and more. In order to achieve high image quality, a two-panel or three-panel camera is generally used. However, it is essential to use a color separation prism having disadvantageous conditions such as reduction in size and weight and generation of ghost flare. Therefore, there is a need for a color separation prism device that is small and lightweight and has little ghost flare.

A conventional color separation prism device will be described below with reference to the drawings. FIG. 2 shows the configuration of a conventional color separation prism device. In FIG. 2, three color separation prisms, a first prism 1, a second prism 2, and a third prism 3, are shown.
The first prism 1 and the second prism 2 are bonded together.
Denotes a joint surface between the second prism 2 and the third prism 3. The solid-state imaging devices 4, 5, and
6 is adhesively fixed. Here, 4a, 5a, and 6a are the imaging surface positions of the respective solid-state imaging devices. Also, 9
Reference numerals a and 9b denote light beam ranges effective for image formation.

The operation of the above-configured color separation prism apparatus will be described below.

[0005] In the color separation prism, it is necessary to correct the deviation of the optical path length due to the variation of the processing dimensional accuracy of each prism and the variation of the imaging surface position of the solid-state imaging device, and to adjust the three imaging surface positions 4a, 5a, and 6a. The relative adjustment of the optical path length is required based on the optical path length of the imaging position 4a of the first prism 1. The optical path length adjustment of the imaging surface 5a of the solid-state imaging device 5 bonded and fixed to the second prism 2 is performed by adjusting the second prism 2
Can be performed by sliding in the X direction along the joint surface 7 between the first prism 1 and the second prism 2.

Similarly, the adjustment of the optical path length of the image pickup surface 6a of the solid-state image pickup device 6 adhered and fixed to the third prism 3 is performed by changing the third prism 3 to the joint surface 8 between the second prism 2 and the third prism 3.
By sliding in the Y direction.

The optical path length adjustment range a of the second prism 2 depends on the variation in the processing dimensional accuracy of the first prism 1 and the second prism 2 and the imaging surface positions 4 a and 5 of the solid-state imaging devices 4 and 5.
In order to make the color separation prism the smallest and lightest, it is necessary to correct the variation of the color separation prism a. It is effective to set the position 8. Similarly, the optical path length adjustment range b of the third prism 3 is determined by the variation in the processing dimensional accuracy of the first prism 1, the second prism 2, and the third prism 3, and the imaging surface position 4a of the solid-state imaging devices 4, 5, and 6. , 5a, and 6a, which are the minimum necessary amounts that can be corrected, and b> a. The other optical path length adjustment range b 'of the third prism 3 may be set so that b'≥.

[0008]

However, in the above-mentioned conventional configuration, if the optical path length adjustment range b of the third prism 3 is secured, the adjustment range of the first prism 1 in the direction in which the optical path length of the third prism 3 is shortened is increased. Since it is limited by the outer shape, δ <b, and the optical path length of the third prism 3 cannot be adjusted. In order to satisfy δ ′ ≧ b, the position of the joint surface 8 between the second prism 2 and the third prism 3 may be set to 8 ′. However, unless the prism length L is increased by σ, the effective light range of the second prism 2 The optical path length adjustment amount "a" cannot be secured for the color separation prism 9b, resulting in a problem that the entire color separation prism device becomes large and heavy.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a color separation prism device which is small and light and has little ghost flare in a two-plate or three-plate camera.

[0010]

In order to achieve this object, the color separation prism device according to the present invention is designed to reduce the effective light range.
Having first, second and third prisms,
Adjust the relative optical path length of the prism to the prism joint surface
A color separation prism that slides along the prism along the direction in which the effective light beam is incident.
In this order, the first, second and third prisms are mutually effective rays.
The first pre-joined portion is joined and disposed on a side having an area.
Notch on the side of the prism, and joining the second prism
When the third prism is slid along the surface,
Part of the third prism can be moved to the space within the notch
The tip of the notch near the effective light range.
It has the feature of being located next to it.

[0011]

With this configuration, it is possible to reduce the size and weight and reduce ghost flare while securing a sufficient optical path length adjustment range in the color separation prism used in the two-plate or three-plate camera.

[0012]

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

In FIG. 1, the color separation prism is constituted by closely fixing three prisms of a first prism 21, a second prism 22, and a third prism 23, and 27 is a first prism and a second prism. Reference numeral 28 denotes a bonding surface of the prism 22, and reference numeral 28 denotes a bonding surface of the second prism 22 and the third prism 23. Solid-state image sensors 24, 25, and 26 are bonded and fixed to the emission surfaces of the individual prisms. Here, 24a, 25a, and 26a are the imaging surface positions of the respective solid-state imaging devices. Further, a notch 29 is provided on the third prism 23 side of the first prism 21. And 3
Numerals 0a and 30b indicate light ranges effective for image formation.

The operation of the color separation prism device configured as described above will be described below.

In the color separation prism, it is necessary to correct the deviation of the optical path length due to the variation of the processing dimensional accuracy of each prism and the variation of the imaging surface position of the solid-state imaging device, and to adjust the three imaging surface positions 24a, 25a, 26a. The relative adjustment of the optical path length is required based on the optical path length of the imaging position 24a of the first prism 21. The optical path length adjustment of the imaging surface 25a of the solid-state imaging device 25 bonded and fixed to the second prism 22
This can be performed by sliding the second prism 22 in the X direction along the joint surface 27 between the first prism 21 and the second prism 22. Similarly, the optical path length adjustment of the imaging surface 26 a of the solid-state imaging device 26 adhered and fixed to the third prism 23 is performed by moving the third prism 23 along the joint surface 28 between the second prism 22 and the third prism 23 in the Y direction. Can be performed by sliding the Second prism 22
The optical path length adjustment range a is the minimum necessary amount that can correct the variation in the processing dimensional accuracy of the first prism 21 and the second prism 22 and the variation in the imaging surface positions 24a and 25a of the solid-state imaging devices 24 and 25. In order to make the color separation prism the smallest and lightest, the effective light range 30a for image formation,
30b so that the joint surface 27 can be evenly removed on both sides.
It is effective to set 28 positions. Similarly, the third
The optical path length adjustment range b of the prism 23 is the first prism 2
1, the minimum required amount that can correct the variation in the processing dimensional accuracy of the second prism 22 and the third prism 23 and the variation of the imaging surface positions 24a, 25a, and 26a of the solid-state imaging devices 24, 25, and b> a. The other optical path length adjustment range b ′ of the third prism 23 may be set so that b ′ ≧ b.

Although the position of the third prism 23 changes in the range from the dotted line 23a to the dashed line 23b due to the adjustment of the optical path length, the notch 29 provided on the first prism 21 makes the notch 29 This makes it possible to secure a sufficient optical path length adjustment amount without increasing the prism length. Further, by locating the tip of the notch 29 near the effective light beam range 30b, it is possible to prevent stray light other than effective light beams from entering the solid-state imaging device 24, and to exert an effect of reducing ghost flare. . The notch 29 also contributes to the weight reduction of the color separation prism.

As described above, according to this embodiment, by providing the first prism 21 with the notch 29, it is possible to secure a sufficient optical path length adjustment range while maintaining the small size and light weight of the color separation prism, as well as the ghost. Flare can be reduced.

[0018]

As described above, the present invention relates to a color separation prism constituted by a plurality of prisms, wherein the color separation prism is fixed to the processing size variation of each prism and to the emission surface of the color separation prism. The optical axis length relative adjustment is performed by sliding the joint surfaces of the prisms to adjust the dimensional variation in the optical axis direction of the imaging surface position of the solid-state imaging device, thereby making unnecessary light incident on the solid-state imaging device. The color separation prism used in two-panel and three-panel cameras by making the notch provided in the prism to reduce ghost flare by including the position that the other prism can take in the optical path length relative adjustment In this case, the size and weight can be reduced while a sufficient optical path length adjustment range is secured, and ghost flare can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a color separation prism device according to an embodiment of the present invention.

FIG. 2 is a side view of a conventional color separation prism device.

[Explanation of symbols]

 21 first prism 22 second prism 23 third prism 29 notch

Claims (1)

(57) [Claims] 1. The method of claim 1, wherein each of the first, second, and
An optical path formed by a third prism;
Long relative adjustment along the prism joint surface along the prism
Is a color separation prism that is performed by sliding
2. Side surfaces where the third prisms have mutually effective ray ranges
The first prism is notched on the side surface of the first prism.
And the second prism along the joining surface of the second prism.
When the third prism is slid, the third prism
Part of the notch can move into the space inside the notch,
A color separation prism device , wherein a tip portion of the light source is located near the effective light beam range .