CN1614450A - Infrared-ray cut-off filter and its preparation - Google Patents

Abstract

A kind of infrared cut-off filter, it comprises a base layer and a film layer, and this film layer is formed on the surface of this base layer, and it comprises a first film layer and a second film layer, and this first film layer is formed on base body Any surface of the layer, the second film layer is formed in a certain area in the middle of the surface of the first film layer, and the filter wavelength range of the first film layer is greater than the filter wavelength range of the second film layer. The preparation method comprises the following steps: providing a substrate layer; placing the substrate layer in a film coating device to form a first film layer on any surface thereof; providing a baffle jig with a number of holes on its surface; The baffle fixture is placed on the first film layer, and a number of second film layers spaced apart from each other are plated on the first film layer; the base layer is cut into infrared cut-off filters with the same number of holes as the baffle fixture . The infrared cut-off filter of the invention can overcome digital camera image interpretation errors and make the image color uniform and clear.

Description

Infrared cut filter and preparation method thereof

【Technical field】

The invention relates to an infrared cut-off filter and a preparation method thereof, in particular to an infrared cut-off filter used in an imaging system and a preparation method thereof.

【Background technique】

With the development of multimedia technology, digital cameras, video cameras and other imaging equipment are more and more favored by consumers. While people are pursuing miniaturization of digital cameras and video cameras, they put forward higher requirements for the image quality of the objects they shoot. That is, it is hoped that the image of the object to be photographed is clear, and the image quality of the object depends to a large extent on the quality of the optical instruments in the digital camera.

Digital cameras generally include lenses or lens groups and image sensing elements (Charge Coupled Device, hereinafter referred to as CCD, or complementary metal oxide semiconductor Complementary Metal-Oxide Semiconductor, hereinafter referred to as CMOS), due to CCD or CMOS image sensing elements The wavelength sensing spectrum range of the sensor is about 350-1500nm, and the wavelength range of visible light is 400-700nm, so if the light energy with a wavelength range greater than 700nm is irradiated to the CCD or CMOS image sensing element, it will cause the image of this part of the sensing element to have three primary colors RGB (Red, Green, Blue) image energy interpretation error, resulting in color distortion of the captured image.

Please refer to Fig. 1 and Fig. 2, in order to solve the above-mentioned color distortion problem, the existing digital camera usually uses an infrared cut-off filter to filter out the infrared light energy irradiated to the CCD or CMOS image sensing element, which includes a lens or Lens group 11, an IR-cut filter (IR-cut Filter) 12, a CCD or CMOS image sensing element 13, the IR-cut filter 12 is used to prevent infrared rays from passing through, and avoid infrared rays from entering the image during normal shooting The sensing element 13 interferes to generate noise, so as to facilitate color reproduction.

Although existing digital cameras can overcome the problem of color distortion caused by infrared interference during normal shooting, the on-axis light beam A1 is vertically incident on the infrared cut-off filter 12, that is, incident at zero angle, and the light beams A2 and A3 respectively deviate from The axis is incident to the infrared cut-off filter 12 at a certain angle, because the optical path difference is ndcosθ (wherein d is the thickness of the filter, and θ is the angle of incidence), so the larger the incident angle of the light beam, the more the filter spectrum will shift towards the short wave, Compared with the light beam A1, the light beams A2 and A3 are incident at a large angle, causing their corresponding filter spectra to shift, which reduces the red light energy of the light beams A2 and A3 entering the CCD or CMOS image sensing element 13, thus resulting in In this part of the image, the energy of the red part of the RGB image is weakened, which also leads to wrong interpretation of the image and color distortion.

【Content of invention】

In order to overcome the shift of the filter spectrum in the large-angle incidence area of the existing infrared cut filter, reduce the energy of the red light entering the CCD or CMOS image sensing element and cause the energy of the red part of the image in RGB to weaken, so that the For the problems of wrong image interpretation and color distortion, the present invention provides an infrared cut-off filter that can overcome digital camera image interpretation errors and restore color.

The present invention also provides a method for preparing the above-mentioned infrared cut filter.

The technical solution adopted by the present invention to solve the above technical problems is: an infrared cut filter, which includes a base layer and a film layer, the film layer is formed on the surface of the base layer, and it includes a first film layer and a film layer The second film layer, the first film layer is formed on any surface of the base layer, the second film layer is formed on a certain area in the middle of the surface of the first film layer or a certain area in the middle of the other surface of the base layer, the first film layer The filtering wavelength range is greater than the filtering wavelength range of the second film layer.

A preparation method for manufacturing the above-mentioned infrared cut filter, comprising the following steps: providing a base layer; placing the base layer in a film coating device to form a first film layer on any surface thereof; providing a baffle jig , the surface of which is provided with a number of holes; the baffle jig is placed on the other surface of the first film layer or the base layer, and a number of second intervals are plated on the other surface of the first film layer or the base layer. Film layer; cutting the base layer into infrared cut-off filters with the same number of holes as the baffle jig.

The beneficial effect of the present invention is that the infrared cut filter of the present invention moves to the long-wave direction by first compensating the large-angle incidence area of the infrared cut filter, that is, the filter spectrum of the peripheral part of the first film layer, and then, in the middle Partly forms a second film layer with a filter spectrum range of short wavelength, and through the superposition of the two spectra, the filter spectrum of the small-angle incident area and the large-angle incident area are the same, so that when it is used in an imaging system, it can overcome the existing technology image The interpretation is wrong, and the image with uniform and clear color is obtained. The preparation method of the infrared cut-off filter of the invention is simple, and multiple infrared cut-off filters can be prepared at one time.

【Description of drawings】

Fig. 1 is the composition schematic diagram of existing digital camera module;

Fig. 2 is the filtering spectrogram of infrared cut-off filter in Fig. 1;

Fig. 3 is the schematic diagram of infrared cut-off filter of the present invention;

Fig. 4 is the filtering spectrogram of the first film layer and the second film layer of the infrared cut-off filter of the present invention;

Fig. 5 is the composition diagram of the first film layer of the infrared cut-off filter of the present invention;

Fig. 6 is a diagram of the composition of the second film layer of the infrared cut-off filter of the present invention;

7 is a schematic diagram of the application of the infrared cut filter of the present invention to an imaging system;

Fig. 8 is a filter spectrum diagram of an infrared cut-off filter of the present invention applied to an imaging system;

Fig. 9 is a diagram showing the preparation of the infrared cut filter of the present invention.

【Detailed ways】

Please refer to FIG. 3 , the infrared cut filter 20 of the present invention includes a base layer 21 and a film layer 22 , and the film layer 22 is attached to a surface of the base layer 21 .

Please refer to FIG. 4 , FIG. 5 and FIG. 6 at the same time, the base layer 21 is made of glass. Film layer 22 is formed on a surface of base layer 21, and it comprises first film layer 221 and second film layer 222, and first film layer 221 forms base layer 21 and covers a surface of base layer 21, by multilayer (such as N layer) thin film, and its filter wavelength range is set to be greater than 700nm _. O ₅ ), its optical thickness is λ/8 (λ is the wavelength of the incident beam), and the low-refractive index material film can be formed of silicon dioxide (SiO ₂ ), and its optical thickness is λ/4 (λ is the wavelength of the incident beam). The second film layer 222 is formed in a certain area in the middle of the surface of the first film layer 221, and is also made of a multilayer (such as M layer) thin film, and its filter wavelength range is set to 400-700nm. 1. Low refractive index material thin films are stacked at intervals. The high refractive index material can be tantalum pentoxide (Ta ₂ O ₅ ), and its optical thickness is λ/8 (λ is the wavelength of the incident beam). The low refractive index material can be It is silicon dioxide (SiO ₂ ), and its optical thickness is λ/4 (λ is the wavelength of the incident beam).

Referring to Fig. 7 and Fig. 8, when this infrared cut-off filter 20 is placed in imaging system, this imaging system comprises lens 31, infrared cut-off filter 20, image sensing unit 32, incident to this infrared cut-off filter The light beam B1 in the middle of the sheet 20 is usually incident at a small angle (generally zero angle), that is, it is directly incident on the second film layer 222, and the light beam B2 incident on the peripheral part of the infrared cut filter 20 is usually incident at a large angle, namely Directly incident on the first film layer 221, usually, the filter wavelength range of the first film layer 222 is greater than 700nm, and the filter wavelength range of the second film layer 222 is set to 400-700nm, because the optical path difference is ndcosθ( Where d is the thickness of the optical filter, θ is the incident angle), so the larger the incident angle of the light beam B2, the more the filter spectrum will be shifted to the short wave, so the filter spectrum of the light beam B2 incident to the first film layer 221 will shift to 700nm Because the filter spectrum of the N-layer thin film of the first film layer 221 is stacked with the filter spectrum of the M-layer thin film of the second film layer 222, the incident light beam B1 filter spectrum of the second film layer 222 is 400-700nm, so that The filtered spectrum of the small-angle incident beam B1 is the same as that of the large-angle incident beam B2.

Please refer to FIG. 9 , when preparing the infrared cut filter 20 of the present invention, a base layer 33 is firstly provided, and the base layer 33 can be made of glass, and placed in a coating device to form a first film layer 221 .

Secondly, provide a baffle jig 4, this baffle jig 4 can be a metal cover plate, its surface is provided with a number of holes 41 whose size is equivalent to that of the second film layer 222, and this baffle jig 4 is placed on the plated On the first film layer 221 of the upper N-layer thin film, the base layer 33 formed with the first film layer 221 and the bracket fixture 4 is placed in the coating device, and several mutual intervals are formed on the first film layer 221. The second film layer 222.

Finally, the baffle jig 4 is removed, and the base layer 33 formed with the first film layer 221 and the second film layer 222 is cut into a shape and size corresponding to the infrared cut filter 20 of the present invention.

The base layer 33 of the infrared cut filter and the preparation method thereof of the present invention can also be made of gelatin or plastic.

It can be understood that the first film layer 221 of the infrared cut-off filter of the present invention and its preparation method can be formed on one surface of the base layer 21, and the second film layer 222 can be formed on the middle of the other surface of the base layer 21. Make the film composition of the first film layer 221 and the second film layer 222 unchanged.

Claims (10)

1. cutoff filter, it comprises a base layer and a rete, this rete is formed at this base layer surface, it is characterized in that: this rete comprises one first rete and one second rete, this first rete is formed at arbitrary surface of base layer, this second rete is formed at certain zone, middle part, surface of first rete, and the first rete filter wavelength scope is greater than the second rete filter wavelength scope.

2. cutoff filter as claimed in claim 1 is characterized in that: this first rete is made of multilayer film, and its filter wavelength scope is set at greater than 700nm.

3. cutoff filter as claimed in claim 2 is characterized in that: this second rete is made of multilayer film, and its filter wavelength scope is set at 400～700nm.

4. cutoff filter as claimed in claim 3 is characterized in that: the multilayer film of the multilayer film of this first rete and second rete form by being piled up by two kinds of high and low refractive index material film spaces.

5. cutoff filter as claimed in claim 4 is characterized in that: this high-index material film is formed by tantalum pentoxide.

6. cutoff filter as claimed in claim 5 is characterized in that: this low-index material film is formed by silicon dioxide.

7. cutoff filter as claimed in claim 6 is characterized in that: this base layer can be made by in glass, gelatin or the plastics any one.

8. cutoff filter, it comprises a base layer, it is characterized in that: this cutoff filter also comprises first rete and second rete, this first rete is formed at the first surface of this base layer, this second rete is formed at another surface middle part certain zone relative with first surface of this base layer, and the first rete filter wavelength scope is greater than the second rete filter wavelength scope.

9. a method for preparing as claim 1 or 8 described cutoff filters is characterized in that: may further comprise the steps, a base layer is provided; This base layer is placed coating apparatus, form one first rete in its arbitrary surface; One catch tool is provided, and its surface offers plurality of holes; This catch tool is placed on another surface of this first rete or base layer, plate second rete at some mutual intervals in another surface of first rete or base layer; This base layer is cut into cutoff filter with catch tool hole similar number.

10. the method for preparing cutoff filter as claimed in claim 9 is characterized in that: this base layer can be made by in glass, gelatin or the plastics any one.

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