JP2528966Y2 - Spectral prism block - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] This invention relates to a spectral prism block in which a spectral prism configured by combining a plurality of prisms is adhered and fixed to a support base, for example, using a plurality of image sensors. Used in a color image pickup apparatus that performs color image pickup.

[Outline of the invention]

The spectroscopic prism block according to the present invention has a first and a second support base made of the same material adhered and fixed to both sides of a spectroscopic prism configured by combining a plurality of prisms, so that a registration error due to a temperature change, While reducing the fluctuation of the spectral characteristics, at least the first and second
By selecting the black side surface of the support base in contact with the spectral prism, irregular reflection of light in the prism is prevented, and deterioration of image quality does not occur.

[Conventional technology]

In general, in a color imaging apparatus, imaging light from a lens is separated into a plurality of color components, that is, three colors of a red component, a green component, and a blue component by a color separation system, and a subject image of each color component is separated into a respective imaging tube and Charge Coupled Device (CCD)
An ED Device) forms an NTSC standard color television signal from each image pickup output obtained by image pickup and outputs the signal.

As described above, as a color separation system that separates the imaging light from the lens into each color component, a spectral prism configured by combining a plurality of prisms, a so-called color separation prism is used. The color separation prism is adhered and fixed to one side surface of a support base made of, for example, aluminum die cast to form a spectral prism block.

Further, in a color imaging device using a plurality of image sensors, each image sensor is adjusted with high positional accuracy, for example, on the order of 1 μm, with respect to each emission surface of light of each color component obtained by a color separation prism. It is mounted in a state where the subject images of the respective color components to be captured are superimposed, that is, the registration adjustment is accurately performed.

FIG. 3 is a plan view showing a part of a video camera using such a conventional spectral prism block, and FIG. 4 is a side view showing the spectral prism. The support base and the mounting base in FIG. 4 are shown by two-dot chain lines.

In these figures, reference numeral 1 denotes a spectral prism block, which includes a spectral prism 2 and a support base 4 for adhering and fixing one side surface of the spectral prism 2.

The spectral prism 2 includes a red prism 3R, a green prism 3G, and a blue prism 3B. A gap of, for example, 0.03 mm is provided between the prisms 3R and 3B to totally reflect red and blue, and gaps other than one side adhered to the support base 4 are sealed with an adhesive or the like. At the same time, the other side is coated to prevent irregular reflection of light.

The support base 4 is made of, for example, aluminum, stainless steel, titanium, or the like, having a coefficient of thermal expansion near the coefficient of thermal expansion of the prisms 3R, 3G, 3B.

Reference numerals 5R, 5G, 5B denote holding components attached to the respective exit surfaces of the prisms 3R, 3G, 3B, 6R, 6G, 6B denote fixed image pickup devices formed by CCDs, and registration with the holding components 5R, 5G, 5B. It is fixed after adjustment.

Reference numeral 8 denotes a mounting base on which the spectral prism 2 is fixed with mounting screws 7, 9 denotes a housing to which the mounting base 8 is mounted, 10 denotes a lens mount fixed in front of the housing 9, and a lens ( (Not shown) is attached.

The conventional spectral prism block 1 configured as described above disperses the imaging light from a lens (not shown) by the spectral prism 2 and converts the imaging output obtained by each of the solid-state imaging devices 6R, 6G, and 6B into an NSTC system. To obtain a standard color television signal.

[Problems to be solved by the invention]

However, in the conventional spectral prism block 1, one side of the spectral prism 2 is bonded and fixed to a metal support base 4, but the other side is sealed with an adhesive, so that both side surfaces of the spectral prism 2. Are made of different materials. Therefore, when such a spectral prism block 1 is used with a temperature difference of about −20 to 60 ° C., the gap provided between the prisms 3R and 3G is uniform between the support base 4 side and the opposite side. However, there is a problem that a registration error due to a temperature change occurs and a spectral characteristic changes.

Further, when the light taken into the spectral prism is reflected on the boundary surface of the prism and the scattered light is reflected on the side surface of the prism, even if the reflected light is slight, the fixed imaging device 6 (RG
There is a problem that image quality is impaired by being incident on B).

The present invention provides a spectral prism block that solves the above-mentioned problems.

[Means for solving the problem]

The spectral prism block of the present invention includes a spectral prism configured by combining a plurality of prisms, a first support base adhered and fixed to one side of the spectral prism, and an adhesive fixed to the other side of the spectral prism. A second support base, wherein only the first support base and the second support base are made of the same material, and at least the first support base and the second support base are formed of the same material. Is selected such that the surface of the support base facing the spectral prism is black.

[Action]

Since both side surfaces of the spectral prism are adhered and fixed by the support base made of the same material, the gap at the boundary surface formed in the spectral prism is prevented from changing due to temperature fluctuation and the like. The resulting irregular reflection can be reduced.

〔Example〕

FIG. 1 is an exploded perspective view showing an embodiment of the spectral prism block of the present invention, and FIG. 2 is an enlarged sectional view showing an attached state of the spectral prism block. The same parts as in FIGS. 3 and 4 are the same. The code is attached.

In these figures, reference numeral 11 denotes a spectral prism block, which includes a spectral prism 2, a first support base 12, and a female screw 16.
, A seal 18, and a second support base 19.

The first support base 12 is made of a ceramic having a coefficient of thermal expansion substantially the same as the coefficient of thermal expansion of the prisms 3R, 3G, 3B constituting the spectral prism 2, and is provided on one side to which the spectral prism 2 is bonded. A hexagonal recess 13 and a step 14 having a shape slightly larger than the recess 13 are provided.
Is provided with a through-hole 15 that communicates with.

The female screw 16 has a hexagonal shape and is provided with a protrusion 17 that is inserted into the through hole 15, and a screw thread is formed inside the protrusion 17. Therefore, when it is inserted into the recess 13, it is prevented from rotating, and it is easy to connect with the mounting screw 7 inserted from the through hole 15.

The seal 18 is adhered to the step portion 14 of the first support base 12 with the female screw 16 mounted thereon, and positions the female screw 16 in the concave portion 13, and has a black surface.

The second support base 19 bonded to the other side of the spectral prism 2 is made of the same ceramic as the first support base 12.

According to the present invention, the female screw 16 is inserted into the recess 13 of the first support base 12, and
The seal 18 is attached to the step portion 14 while being positioned at 15, and the splitting prism 2 is adhered and fixed to one side of the first support base 12, and the second support is also provided on the other side of the spectral prism 2. Base
The spectral prism block 11 is configured by bonding and fixing 19.

The spectral prism block of the present invention thus configured
11 is to mechanically connect the spectral prism block 11 to the mounting base 8 by screwing the mounting screw 7 having passed through the mounting base 8 to the female screw 16 mounted on the first support base 12. Can be attached.

In addition, since the first and second support bases 12 and 19 are made of ceramic, the first and second support bases 12 and 19 are inexpensive, and their thermal expansion coefficients are reduced by the prisms 3R and 3G. , 3B can be made substantially the same as that of the first and second support bases 12, 1 even when subjected to temperature stress.
Deterioration of adhesive strength with 9 is prevented.

In particular, by using a hard type adhesive, the adhesive strength between the spectral prism 2 and the first and second support bases 12 and 19 can be improved, and a registration error due to a temperature change and a reduction in spectral characteristics. Fluctuations can be kept small.

In the spectral prism block of the present invention, the surfaces of the first and second support bases 12 and 19 are black, and the female screw 16 is covered with the seal 18. In addition to preventing irregular reflection, dust and the like can be prevented from entering through the screw holes and adhering to the side surfaces of the spectral prism 2.

Further, since the female screw 16 is provided with the protruding portion 17 and the protruding portion 17 is provided with a thread, the effective screw portion of the female screw 16 to be screwed with the screw 7 can be increased, so that the female screw 16 does not have the protruding portion 17. The first support base 12 can be made thinner than in the case.

In the above-described embodiment, the first and second support bases 12 and 19 that are bonded and fixed to both sides of the spectral prism 2 are made of ceramic, but the first and second support bases 12 and 19 are different from each other. A similar effect can be obtained if it is made of a material.

Further, although the female screw 16 provided with the protruding portion 17 is used, it goes without saying that a normal female screw without the protruding portion 17 may be used.

[Effect of the invention]

As described above, the spectroscopic prism block of the present invention is configured such that the first and second support bases made of the same material are adhered and fixed to both side surfaces of the spectroscopic prism configured by combining a plurality of prisms, and at least the spectroscopic prism is used. Since the surface facing the prism is selected to be black, the gap provided in the spectral prism changes between the first support base side and the second support base side in the same manner, and the temperature changes. Registration errors and fluctuations in spectral characteristics due to this can be suppressed.

In addition, since the support base has a black surface opposite to the spectral prism, irregular reflection of stray light in the spectral prism and occurrence of color mixing can be prevented, and one of the support bases protrudes from the camera housing. Since it is configured to be fixed to the mounting board with screws, expansion and contraction due to temperature fluctuation of the mounting board is absorbed to some extent by the mounting screws,
This expansion and contraction does not apply stress to the spectral prism, and the prism registration can be properly maintained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the spectral prism block of the present invention, FIG. 2 is an enlarged sectional view showing an attached state of the spectral prism block, and FIG. 3 is a video camera using a conventional spectral prism block. Plan view showing a part of
The figure is a side view showing the spectral prism. In the figure, 2 is a spectral prism, 3R, 3G, and 3B are prisms, 11 is a spectral prism block, 12 is a first support base, and 19 is a second support base.

Claims (1)

(57) [Scope of request for utility model registration] 1. A spectral prism formed by combining a plurality of prisms, a first support base adhered and fixed to one side surface of the spectral prism, and a second support adhered and fixed to the other side surface of the spectral prism. A mounting base protruding from the video camera housing, and mounting screws for fixing only the first supporting base to the mounting base. The second support base is made of the same material as each other, is made of a material having a coefficient of thermal expansion substantially equal to the coefficient of thermal expansion of the spectral prism, and includes at least the first support base and the second support base. A spectral prism block, wherein a surface of the support base facing the spectral prism is selected to be black.