Liquid crystal display device comprising a capacitance insulating film with a refractive index of 1.7 to 2.0 with respect to a light having a wavelength of 632.8 nm
View Patent ↗There is provided a high-definition liquid crystal display device that can prevent flicker due to a reduction in the pixel potential in a low-frequency drive of about 10 Hz to reduce power consumption. The pixel has a TFT formed of Poly-Si as a switching element. In the pixel, a capacitance insulating film is formed on a planar first electrode on which a comb-shaped second electrode is fanned. When the film thickness of the insulating film is d and the dielectric constant at 10 Hz frequency is ∈, it is given that ∈d≥5×10 −6 m at 10 Hz frequency. The capacitance insulating film does not have a hysteresis characteristic. The refractive index of the capacitance insulating film with respect to a light of a wavelength of 632.8 nm is 1.7 to 2.0.
1. A liquid crystal display device comprising:
a first substrate including pixels formed between scanning lines extending in a first direction and arranged in a second direction, and video signal lines extending in the second direction and arranged in the first direction;
a second substrate; and
a liquid crystal interposed between the first substrate and the second substrate,
wherein the pixel has a TFT as a switching element,
wherein in the pixel, a capacitance insulating film is formed on a first electrode formed in a planar shape on which a comb-shaped second electrode formed,
wherein the refractive index of the capacitance insulating film with respect to a light of a wavelength of 632.8 nm is in the range from 1.7 to 2.0.
2. A liquid crystal display device according to claim 1 ,
wherein the capacitance insulating film does not have a hysteresis characteristic.
3. A liquid crystal display device according to claim 1 ,
wherein the first electrode is a common electrode and the second electrode is a pixel electrode.
4. A liquid crystal display device according to claim 1 ,
wherein the cycle in which a video signal is written in the first electrode or in the second electrode is 10 Hz or less.
5. A liquid crystal display device according to claim 1 ,
wherein when the period of rewriting the video signal to the pixel is one frame, the frame is configured with a scanning period and a break period,
wherein the cycle of the frame is 10 Hz or less.
6. A liquid crystal display device according to claim 1 ,
wherein when the film thickness of the capacitance insulating film is d and the dielectric constant at a frequency of 10 Hz is ∈ in an operating environment of 50 degrees Celsius, it is given that ∈d≥5×10 −6 m at 10 Hz frequency.
7. A liquid crystal display device according to claim 1 ,
wherein when the film thickness of the capacitance insulating film is d and the dielectric constant at a frequency of 10 Hz is ∈ in an operating environment of 25 degrees Celsius, it is given that ∈d≥2.1×10 −6 m at 10 Hz frequency.
8. A liquid crystal display device according to claim 7 ,
wherein the capacitance insulating film is formed of hafnium oxide (HfO 2 ).
9. A liquid crystal display device according to claim 1 ,
wherein the capacitance insulating film is formed by a first layer and a second layer,
wherein the first layer is formed of SiN and the second layer is formed by a high dielectric constant insulating film,
wherein when the film thickness of the high dielectric constant insulating film is d and the dielectric constant at a frequency of 10 Hz is ∈ in an operating environment of 50 degrees Celsius, it is given that ∈d≥2.1×10 −6 m at 10 Hz frequency.
10. A liquid crystal display device according to claim 9 ,
wherein the thickness of the first layer is equal to or less than the thickness of the second layer.
11. A liquid crystal display device according to claim 9 ,
wherein the first layer is formed on the lower side of the second layer.