JPS6038683B2 - trimming filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a trimming filter having comb-shaped transmission characteristics in the visible range.

Conventionally, in single-tube color TV cameras using the frequency separation method, the dye used in the stripe filter is blue (B).
, green (G), and red (R) have characteristics that overlap each other in their respective peripheral wavelength regions.
It is not possible to strictly separate the incident light into blue, green, and red. That is, since even the light that has passed through the green area of the stripe filter contains a slight light component in the blue or red area, the color reproducibility cannot necessarily be said to be good. Conventionally, an attempt was made to improve color reproducibility by layering a trimming filter with a color separation stripe filter, such as "Optical System for a Single-Tube Color Film Camera" Television, No. 2 Mirror Cover, No. 1, 1972 King. .

This relates to the color reproducibility of color films, and in particular, a trimming filter has been disclosed that makes light in the green region have characteristics close to a line spectrum. The shape of this trimming filter is as follows, assuming that the input o is the design wavelength.
It is formed by sandwiching both sides of a layer having the same thickness as a school cap between school caps.

As described above, the trimming filters shown in the past are ideally close to the line spectrum, and the transmitting region is also in the green wavelength band. On the contrary,
A trimming filter for normal color photography needs to have a sufficiently wide transmission band in order to transmit a sufficient amount of light in each wavelength band (R, G, B).

Also, a filter is required that can efficiently separate the light beams of each wavelength band using a single filter. An object of the present invention is to provide a trimming filter having characteristics suitable for such requirements.

In the trimming filter according to the present invention, there is provided a first thin film group in which at least one optical film layer is arranged;
The second layer has an optical thickness consisting of alternating layers of thin film layers of poisonous and thick layers.
The above purpose is achieved by stacking thin film groups alternately, and by configuring a total of four or more thin film groups.

FIG. 1 is a diagram showing the film structure of a trimming filter according to the present invention.From the substrate S side, the film thickness of the jl group is 1, and the film thickness of the optical 8 is n. d is the current 3rd layer, Tsuyoshi, n2d2 is tonight's 2nd layer 2, ~ d3 is the 3rd layer 3 of Ashiiri, n4d4 is the 4th layer 4 of Kiiri, Hirohiro is the 5th layer 5 of Ashiiri, n6d6 is the current layer 6th layer 6. Misaki is now the 7th
Layer 7, n8d8 is the current 8th layer 8, Himogaashiri's 9th layer 9
・n・.

d... is the 10th layer 1o of capture, Cape d. ．． The 11th layer 11. is sequentially laminated. However, ^ is the reference wavelength ni is the refractive index of the i-th layer, di' is the geometrical thickness of the i-th layer, ns
is the refractive index of the substrate, and no is the refractive index of the external medium. In this way, the first thin film group is applied to the first layer and the second layer to the third thin film group.
the second thin film group in the fourth and fifth layers, the first thin film group in the sixth, seventh and eighth layers, and the ninth and tenth layers.
The second thin film group is formed by the second thin film group and the eleventh layer. Second
This figure is a diagram showing a transmittance characteristic curve of an example of a trimming filter having the configuration shown in FIG. 1.

Note that the vertical axis is the transmittance T (%) and the horizontal axis is the wavelength (nm), and the axes of the transmittance characteristic curves shown below are all the same. Table 1 shows data on the film configuration for the characteristic curve shown in FIG. Table 1 Reference wavelength S = 510 nm As shown in Table 1, the odd-numbered layers from the substrate are high refractive index layers made of Z2, and the even-numbered layers are low refractive index layers mainly composed of Si02. is provided.

As shown in Figure 2, the characteristic curve has valleys near 47 and 56 where the transmittance is approximately 25%, and shows good transmittance in other visible wavelength bands, and in the red band. , green and blue bands are well separated. In addition, in this application, the refractive index is 1.5.
If the refractive index is less than 0, it is a low refractive index layer, and if the refractive index is 1.50 or more, it is 1.
．． Those with a refractive index of less than 80 are treated as intermediate refractive index layers, and those with a refractive index of 1.8 or more are treated as high refractive index layers. Fig. 3 is a diagram showing the film structure of another example of the trimming filter according to the present invention. From the substrate S side to the inner top, the optical film thickness n.d is the current Nada layer 21, the second layer 22 that is struggling stiffly, and the third layer that is hard to climb.
Layer 23, 4th layer 24 with mountain 4, 5th layer 25 where n5d5 is poisonous, 6th layer 26 with ~mogazen, n7d7 is now 7th layer
Layer 27, mountain & is now the 8th layer 28, n9d9 is Kiiri's 9th
Layer 29.n.

d.0 consists of the 11th layer 31, where the meeting^ is the ○th layer 30, and n...d... is the poison^. From the substrate side, the first thin film group is applied to the first and second layers, and the second thin film group is applied to the third, fourth, and fifth layers from the substrate side.
The first thin film group is formed by a sixth layer, a seventh layer, and an eighth layer, and the second thin film group is formed by a ninth layer, a tenth layer, and an eleventh layer. FIG. 4 is a diagram showing a transmittance characteristic curve of an example of a trimming filter having the membrane configuration shown in FIG. 3, and data for this characteristic curve are shown in Table 2.

Table 2, Reference wavelength = 520 nm As shown in Table 2, the odd-numbered layer counting from the substrate has Z
A high refractive index layer of r02 and a low refractive index layer mainly composed of Si02 are arranged as even-numbered layers.

As shown in Figure 4, the characteristic curve has valleys with a transmittance of about 35% near the 48- and 57-valent skins, and has good transmittance in other visible wavelength bands. A trimming filter that satisfactorily separates red, green, and blue bands can be obtained. FIGS. 5, 6, and 7 are diagrams showing transmittance characteristic curves of the trimming filter having the antinode configuration shown in FIG. 3.

Since the film formation data shown in FIGS. 5, 6, and 7 differ only in the refractive index, the data in each figure is summarized in Table 3. Table 3 Reference wavelength = 520 nm The characteristic curve shown in Figure 5 shows that the odd-numbered layers counting from the substrate side are made of a material with a high refractive index. Basically, a layer containing Si02 as a main component is arranged.

However, the fourth layer is N20, which is a material with an intermediate refractive index.
3 layer is placed in place of the low refractive index layer. The characteristic curve shown in Figure 6 basically shows that, viewed from the substrate side, the odd-numbered layers are made of Zr02, a material with a high refractive index, and the even-numbered layers are made of Si02, a material with a low refractive index. layers are arranged.

However, in place of the low refractive index layer, layers made of AI 3, which is a material with an intermediate refractive index, are arranged in the fourth layer and the tenth layer. The characteristic curve shown in Fig. 7 also basically shows that the odd-numbered layers from the substrate side are made of Zr0, which is a material with a high refractive index.
A layer of M2, which is a material with a low refractive index, is arranged on even-numbered eyebrows.

However, in the first layer and the seventh layer, a layer made of AI203, which is a material with an intermediate refractive index, is arranged in place of the high refractive index layer. In other words, the film structure for FIG. 5 includes the first thin film group consisting of alternating layers of high refractive index layers and low refractive index layers, and alternating layers of high refractive index layers and low refractive index layers and high refractive index layers. and the second thin film group consisting of alternating layers of intermediate refractive index layers.

The film structure corresponding to FIG. 6 includes the first thin film group consisting of alternating layers of high refractive index layers and low refractive index layers, and the second thin film group consisting of alternating layers of high refractive index layers and intermediate refractive index layers. It is composed of a group of thin films. The pocket structure corresponding to FIG. 7 has the first thin film group consisting of alternating layers of intermediate refractive index layers and low refractive index layers, and the second thin film group consisting of alternating layers of high refractive index layers and low refractive index layers. It consists of a group. FIG. 8 is a diagram showing another film configuration of the trimming filter according to the present invention, in order from the substrate S side:
Optical film thickness n. d. is the grave's third layer 41, n2d2 is the poisonous second layer 42, ~ d3 is the third layer 43 of Kiiri, mountain d4 is the current fourth layer 44, and Takumi is the fifth layer of Ashiiri 45. n6d6 is the wife^'s 6th layer 46, n7d7 is the 7th layer with reeds 47, np8 is the current 8th layer 48, ~ struggles is the 9th layer 49, n's d.
0 consists of the current first o layer 50. FIG. 9 is a diagram showing a transmittance characteristic curve of one embodiment of the trimming filter having the waist configuration shown in FIG. 8.

Table 4 shows data on the antinode configuration for the characteristic curve of FIG. 9. Table 4 Reference wavelength = 520 nm As shown in Table 4, the first, second and third layers cover the second thin film group, the fourth layer covers the first thin film group, the fifth layer and the third layer cover the first thin film group. 6
The second thin film group is formed by the second thin film group and the seventh layer, and the first thin film group is formed by the eighth layer, the ninth layer, and the tenth layer.

Then, as viewed from the substrate side, the odd-numbered layers are provided with a layer of Zr02, which is a material with a high refractive index, and the even-numbered layers are provided with a layer of M2, which is a material with a low refractive index. This characteristic curve is
There is a valley with a transmittance of approximately 65% near the 47-plate and 57-plate areas, and in the other visible regions, a filter that transmits light well and separates the red, green, and blue bands well can be obtained. It will be done. FIG. 10 is a diagram showing another film formation of the trimming filter according to the present invention, in which the optical film thickness is n. d. Ga Tsuma^'s first layer 61, Yamamogaashi^'s second layer 62, n3d3 is Kiiri's third layer 63, ~4 is the current fourth layer 64, n5d5 is the current fifth layer 65, Stop. is the current 6th layer 66, n, and 7 is Kiiri's 7th layer 67, Buddha Mote^'s 8th layer
The ninth layer 69.n. in which the layer 68.n9dg is ≧.

d. 0 is the current o-th layer 7o, n. ．． d. ．． is now the 11th
It consists of layer 71. FIG. 11 is a diagram showing a transmittance characteristic curve of an example of a trimming filter having the membrane structure shown in FIG. 10.

Table 5 shows the data of the film structure for the characteristic curve of FIG. 11. Table 5 Standard wavelength path = 520 nm As shown in Table 5, the second thin film group is used in the first layer, the second layer phase and the third layer, and the first thin film group is used in the fourth layer, fifth layer and sixth layer. The thin film group is made up of the seventh layer, the eighth layer and the ninth layer, and the second thin film group is
The 10th layer and the 11th layer form the first thin film group.

Then, as viewed from the substrate side, odd-numbered layers are layers of Zr02, which is a material with a high refractive index, and layers of MgF2, which is a material with a low refractive index, are arranged in even-numbered layers. As shown in Figure 11, there are valleys with transmittance of approximately 25% near Kagawa 48 and Kagawa 57, and good transmittance at the main wavelengths of red, green, and blue. A trimming filter that satisfactorily separates the green and blue wavelength bands can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the membrane structure of one embodiment of the trimming filter according to the present invention, FIG. 2 is a diagram showing the transmittance characteristic curve of one embodiment of the trimming filter shown in FIG. Figures 4, 5, 6 and 7 showing membrane configurations of other embodiments of the trimming filter according to the invention are each an example of the trimming filter having the membrane configuration shown in Figure 3. FIG. 8 is a diagram showing the membrane structure of another embodiment of the trimming filter according to the present invention, and FIG. 9 is an embodiment of the trimming filter having the membrane structure shown in FIG. 8. Figure 1 shows the transmittance characteristic curve of
FIG. 11 is a diagram showing a transmittance characteristic curve of an example of the trimming filter having the membrane configuration shown in FIG. 10. FIG. 1-11, 21-31, 41-50, 61-71...
・Thin film layer, ni...Refractive index of the i-th layer, di...
...Geometric thickness of the i-th layer, S...Substrate, ns
・・・・・・Refractive index of substrate, General ・・・Refractive index of external substance, T：Transmittance, Input・・・・・・Wavelength. Shigeru figure Raku Z figure Back figure Hair figure 4 figure Cutting figure

Claims (1)

[Claims] 1 When the reference wavelength is λ, a first thin film group including at least one thin film layer with an optical thickness of λ/4, and alternating layers of thin film layers with an optical thickness of 2/4λ and 4/4λ. A trimming filter characterized in that a second thin film group consisting of the following thin film groups are alternately laminated, and the trimming filter is composed of four or more thin film groups as a whole.