Infrared cut filter, camera module having the filter, and electronic device having the module
An infrared (IR) cut filter includes an absorption type filter, a first coating layer, and a second coating layer. The absorption type filter absorbs IR light of a first wavelength band. The first coating layer is formed on a first side of the absorption type filter and passes visible light and reflects a part of the IR light. The second coating layer is formed on a second side of the absorption type filter and reflects a remaining part of the IR light that passes through the first coating layer and enters the absorption type filter. The absorption type filter further absorbs the IR light of a second wavelength band within the absorption type filter. In addition, a camera module having the IR cut filter is provided and an electronic device having the camera module also is provided.
1. An infrared (IR) cut filter comprising:
an absorption layer configured to absorb IR light of a first wavelength band and further absorb reflected IR light of a second wavelength band;
a first coating layer formed on a first side of the absorption layer and configured to pass visible light and reflect a part of the IR light; and
a second coating layer formed on a second side of the absorption layer and configured to reflect a remaining part of the IR light that passes through the first coating layer and enters the absorption layer,
wherein the absorption layer is formed to include a first absorbent for absorbing the IR light of the first wavelength band, and a second absorbent for absorbing the reflected IR light of the second wavelength band,
wherein the second wavelength band is in a range of about 800 nm to about 1000 nm.
2. The IR cut filter of claim 1 , wherein the absorption layer includes:
an absorbing film plate formed to include the first absorbent; and
a reflected light absorbing layer formed to include the second absorbent and formed between the absorbing film plate and one of the first and second coating layers.
3. The IR cut filter of claim 1 , wherein the first wavelength band is in a range of about 700 nm to about 1000 nm.
4. The IR cut filter of claim 1 , wherein the absorption layer has a transmittance of 90% or more with regard to the visible light and contains an absorbent having a higher absorptance for the IR light of the second wavelength band than for the IR light of the first wavelength band.
5. The IR cut filter of claim 1 , wherein the first coating layer and the second coating layer are formed to have a transmittance of 90% or more with regard to the visible light and to have a reflectance of 99% or more with regard to the reflected IR light having a wavelength of about 800 nm to about 1000 nm.
6. The IR cut filter of claim 5 , wherein the first coating layer and the second coating layer comprise a multilayer thin film in which a layer having a first refractive index and a layer having a second refractive index being different than the first refractive index are alternately deposited.
7. A camera module comprising:
a lens configured to refract light incident from an exterior of the camera module;
an image sensor configured to obtain an image formed by the refracted light; and
an infrared (IR) cut filter disposed between the lens and the image sensor, wherein the IR cut filter comprises:
an absorption layer configured to absorb IR light of a first wavelength band;
a first coating layer formed on a first side of the absorption layer and configured to pass visible light and reflect a part of the IR light; and
a second coating layer formed on a second side of the absorption layer and configured to reflect a remaining part of the IR light that passes through the first coating layer and enters the absorption layer, and
wherein the absorption layer is formed to include a first absorbent for absorbing the IR light of the first wavelength band, and a second absorbent for absorbing the reflected IR light of a second wavelength band, and
wherein the second wavelength band is in a range of about 800 nm to about 1000 nm.
8. The camera module of claim 7 , wherein the absorption layer comprises:
an absorbing film plate formed to include the first absorbent; and
a reflected light absorbing layer formed to include the second absorbent and formed between the absorbing film plate and one of the first and second coating layers.
9. The camera module of claim 7 , wherein the first wavelength band is in a range of about 700 nm to about 1200 nm.
10. The camera module of claim 7 , wherein the absorption layer has a transmittance of 90% or more with regard to the visible light and contains the second absorbent having a higher absorptance for the IR light of the second wavelength band than for the IR light of the first wavelength band.
11. The camera module of claim 7 , wherein the second wavelength band is determined to include a cross region in which reflective bands of the first and second coating layers overlap with each other or a wavelength shift region depending on variation in an incident angle of the IR light.
12. The camera module of claim 11 , wherein the absorption layer further comprises a reflected light absorbing layer that is configured to absorb the IR light in a band having a wavelength of about 850 nm to about 950 nm.
13. An electronic device comprising:
a camera module;
a processor; and
a memory,
wherein the camera module includes an infrared (IR) cut filter configured to absorb IR light of a first wavelength band and to absorb refracted IR light of a second wavelength band that is narrower than the first wavelength band within the infrared cut filter,
wherein, the infrared cut filter is formed to include a first absorbent for absorbing the IR light of the first wavelength band, and a second absorbent for absorbing the refracted IR light of the second wavelength ban, and
wherein the second wavelength band is in a range of about 800 nm to about 1000 nm.