JPH01118101A - Spectroscope for video camera - Google Patents

Abstract

PURPOSE:To substantially obviate generation of distortion, etc., arising from a temp. change by forming prism bases of black ceramics having a specific coefft. of thermal expansion and mounting CCDs on the metallized surfaces provided on the prism bases, thereby constituting the title spectroscope. CONSTITUTION:The plural prisms 2a-2c are combined and both the end faces thereof are held by the plate prisms 1 consisting of the black ceramics having 6-10X10<-6>/ deg.C coefft. of thermal expansion. The CCDs are mounted on the prescribed positions of the prism bases 1. The metallized surfaces 1a-1c are formed by metallization of Ag-Pd, Mo-Mn, etc., on the prism bases 1 and the CCD packages 3a-3c are mounted thereto by soldering. Soldering at a low temp. is thereby enabled. Since the coefft. of thermal expansion of the prism bases 1 is approximate to the coefft. of thermal expansion of the glass forming the prisms 2a-2c, the generation of distortion of the prisms 2a-2c arising from the temp. change is substantially obviated because of the small sp. gr. thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spectroscope for separating incident light into three primary colors in a video camera.

[Conventional technology]

In video cameras, light entering through a lens is separated into three primary colors (red, green, and blue) by a spectroscope, and a dedicated CCO is used to receive images for each color.

As shown in Figs. 1 and 2, the structure of this spectrometer is to combine three prisms 2a, 2b, and 2C, fix both end faces with a prism base 1, and place the three prisms at predetermined positions on the prism base 1. It was equipped with three CCDs 3a, 3b, and 3c.

The prism base 1 has a thermal expansion coefficient of a prism 2a,
Glass used for 2b and 2c (7,8xlO-6/
'c), and a black material that absorbs light is also required, and titanium (thermal expansion coefficient 8.2
Xl0-'/'C).

[Problems with conventional technology]

However, the properties of titanium, which forms the conventional prism base 1, vary greatly depending on the gas it contains, so care must be taken during manufacturing, and it has a close-packed hexagonal crystal structure at temperatures below 885°C, making cold working difficult. Due to these problems, it has been difficult and expensive to form the prism base 1 with titanium.

In addition, the method of attaching the CCDs 3a, 3b, and 3c to the prism base 1 was by soldering or brazing, since adhesion was unreliable. I had to. At that time, if only the soldering parts are heated to a high temperature, distortion will occur between the prism base 1 and the prisms 2a, 2b, and 2c, which may cause misalignment during cooling.Also, if the entire soldering part is heated to a high temperature, the prisms 2a, 2b, and 2c will be heated. Distortion occurs;
There was a problem in that it adversely affected the image.

[Means for solving problems]

In view of the above, the present invention combines a plurality of prisms,
Both end faces have a coefficient of thermal expansion of 6 to 10 x 10-'/
It is held by a plate-shaped prism made of black ceramic at ℃,
A CCD is attached to a predetermined position on the prism base to constitute a spectrometer for a video camera.

〔Example〕

The present invention will be explained in detail below.

FIG. 1 shows a spectrometer for a video camera according to an embodiment of the present invention, and as the X-X cross section is shown in FIG.
CCDs 3a+, 3b+, and 3c are respectively attached to three metallized surfaces 1a+lb and lc formed on the prism base l by soldering. The prisms 2a, 2b, and 2C are combined as shown in Fig. 2, and the light incident from the left side of the drawing is separated into three primary colors, and the CCDs 3a, 3b, and 3c respectively
It is now being perceived as

The material of the prism base 1 is black ceramic as shown in Table 1, and the coefficient of thermal expansion is that of the prism 2a.
Glass forming 2b, 2c (7,8x 10-6/℃
) and has a low specific gravity, so it can be made lighter.

In addition, in Table 1, the blackish brown alumina is ^IgOs 91%
Dark brown steatite contains SiO □ 60% or less, Mg 0 20% or more, AlzOs 4% or less,
Also, black titania is 2MgQ-5in, 60χ, Ti
0z 40χ, and additional additives were added to make them black.

The prism base 1 made of black ceramic has A
Metalized surfaces 1a, 1b, and 1c are formed by g-Pd metallization or Mo-111 metallization, and CCD packages 3a, 3b, and 3c are attached by soldering. The solder used is Sn 60
χ, Pb40χ, with 2 to 5χ of Ag added, and soldering is carried out at 180 to 250°C. In addition, low-temperature melting solder is made by adding Bi, In, Cd, etc. to solder made of 5n-Pb. Soldering may be carried out at 45-170°C using the prism base l.
is formed from ceramic, and metallized surfaces 1a+lb,
Since it is equipped with an lc, low-temperature soldering is possible without adversely affecting the prisms 2a, 2b, and 2c.

Further, the metallized surfaces 1a and tb of the prism base 1.

If the portion 1c had a rough surface with a surface roughness (Ra) of 0.5 μm or more, the strength of metallization and soldering would be increased, which was excellent.

Next, prisms were made from the three types of black ceramics shown in Table 1, silicon carbide (thermal expansion coefficient 3.6 Xl0-'/'C), silicon nitride (thermal expansion coefficient 1.9 Xl0-'/'C), etc. We made a prototype of base 1 and conducted a usage experiment.As a result, we found that base 1 made of silicon nitride and silicon carbide was suitable for prism 2a.
, 2b, and 2c were too large, which caused distortion in the prisms 2a, 2b, and 2c, resulting in misaligned images. The ones used were excellent without any particular problems. Furthermore, as a result of various experiments, the ceramic forming the prism base l has a thermal expansion coefficient of 6 to l0XL.
There was no particular problem as long as it was O-'.

〔Effect of the invention〕

According to the present invention, the prism base of a spectrometer for a video camera is made of black ceramic having a coefficient of thermal expansion of 6 to 10 x 10-'', and a CCD is formed on the metallized surface of the prism base. Because the prism and prism base have similar thermal expansion coefficients, distortion due to temperature changes is less likely to occur, and by soldering to the metallized surface of the prism base, it is possible to mount the CCD at low temperatures. The ceramic that forms the prism base has many features such as being easy to manufacture at low cost, being lightweight, and having little deterioration over time, making it suitable for use in video cameras. A spectrometer can be provided.

As a result, it becomes possible to improve the performance of the video camera.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a spectrometer for a video camera according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line X--X in FIG. 1. 1 Niblism base 2a + 2b + 2c Nibrism la, lb, lc: Metallized surface 3a
, 3b, 3c: cc.

Claims (2)

[Claims] (1) Combine a plurality of prisms, hold both end faces with a plate-shaped prism base made of black ceramic with a coefficient of thermal expansion of 6 to 10 x 10^-^6/°C, and place a CCD at a predetermined position on the prism base. A spectrometer for a video camera characterized by being equipped with a. (2) The spectrometer for a video camera according to claim 1, characterized in that the end face of the prism base is provided with a metallized surface, and a CCD is mounted on the metallized surface by soldering.