Display device

1. A display device, comprising:

a reflective display panel;

a plurality of electrical or optical element layers, stacked above the reflective display panel, wherein one of the electrical or optical element layers is a light guide plate; and

at least one light-emitting element, disposed beside the light guide plate and configured to emit a light beam, and the light beam entering inside the light guiding plate through a lateral side of the light guide plate, wherein a plurality of transparent medium layers are respectively located between every two adjacent ones of the reflective display panel and the electrical or optical element layers and above the electrical or optical element layer most away from the reflective display panel among the electrical or optical element layers, at least one of the transparent medium layers above the light guide plate is a gas layer, the transparent medium layer located above the electrical or optical element layer most away from the reflective display panel among the electrical or optical element layers is formed by an environmental medium of a place where the display device is located, and the gas layer is located between the electrical or optical element layer most away from the reflective display panel and the reflective display panel when the light guide plate is not the electrical or optical element layer most away from the reflective display panel,

wherein the electrical or optical element layer most away from the reflective display panel is a cover lens, the gas layer is located between the cover lens and the light guide plate, and a printed layer is provided at an edge of the cover lens,

wherein the electrical or optical element layers comprise a first electrical or optical element layer, a second electrical or optical element layer and a third electrical or optical element layer which are sequentially stacked up from the reflective display device, and the transparent medium layers comprise a first transparent medium layer located between the reflective display panel and the first electrical or optical element layer, a second transparent medium layer located between the first electrical or optical element layer and the second electrical or optical element layer, and a third transparent medium layer located between the second electrical or optical element layer and the third electrical or optical element layer, wherein the first electrical or optical element layer is the light guide plate, a refractive index of the second transparent medium layer is less than or equal to a refractive index of the third transparent medium layer, and the refractive index of the second transparent medium layer is less than or equal to a refractive index of the first transparent medium layer, and

wherein the first transparent medium layer is gas, air, liquid, an optically-clear adhesive or a combination thereof, and the third transparent medium layer is gas, air, liquid, an optically-clear adhesive or a combination thereof.

2. The display device of claim 1 , wherein the gas layer is located between two adjacent ones of the electrical or optical element layers, and a refractive index of the gas layer is less than refractive indexes of the two adjacent ones of the electrical or optical element layers.

3. The display device of claim 2 , wherein a refractive index of the transparent medium layer located above the electrical or optical element layer most away from the reflective display panel is less than the refractive indexes of the two adjacent ones of the electrical or optical element layers sandwiching the gas layer.

4. The display device of claim 1 , wherein the gas layer is located between two adjacent ones of the electrical or optical element layers, and a refractive index of the gas layer is less than or equal to a refractive index of the transparent medium layer located above the electrical or optical element layer most away from the reflective display panel.

5. The display device of claim 1 , wherein the electrical or optical element layers comprise the light guide plate and at least one of a touch panel, a cover lens and an anti-glare film.

6. A display device, comprising:

a reflective display panel;

a plurality of electrical or optical element layers, stacked above the reflective display panel, wherein one of the electrical or optical element layers is a light guide plate; and

at least one light-emitting element, disposed beside the light guide plate and configured to emit a light beam, and the light beam entering inside the light guiding plate through a lateral side of the light guide plate, wherein a plurality of transparent medium layers are respectively located between every two adjacent ones of the reflective display panel and the electrical or optical element layers and above the electrical or optical element layers, a value of a refractive index of at least one of the transparent medium layers above the light guide plate is a minimum value among values of refractive indexes of the electrical or optical element layers and the transparent medium layers, the transparent medium layer located above the electrical or optical element layer most away from the reflective display panel among the electrical or optical element layers is formed by an environmental medium of a place where the display device is located, and the transparent medium layer having a smallest refractive index is located between the electrical or optical element layer most away from the reflective display panel and the reflective display panel when the light guide plate is not the electrical or optical element layer most away from the reflective display panel,

wherein the electrical or optical element layer most away from the reflective display panel is a cover lens, the gas layer is located between the cover lens and the light guide plate, and a printed layer is provided at an edge of the cover lens,

wherein the electrical or optical element layers comprise a first electrical or optical element layer, a second electrical or optical element layer and a third electrical or optical element layer which are sequentially stacked up from the reflective display device, and the transparent medium layers comprise a first transparent medium layer located between the reflective display panel and the first electrical or optical element layer, a second transparent medium layer located between the first electrical or optical element layer and the second electrical or optical element layer, and a third transparent medium layer located between the second electrical or optical element layer and the third electrical or optical element layer, wherein the first electrical or optical element layer is the light guide plate, a refractive index of the second transparent medium layer is less than or equal to a refractive index of the third transparent medium layer, and the refractive index of the second transparent medium layer is less than or equal to a refractive index of the first transparent medium layer, and

wherein the first transparent medium layer is gas, air, liquid, an optically-clear adhesive or a combination thereof, and the third transparent medium layer is gas, air, liquid, an optically-clear adhesive or a combination thereof.

7. The display device of claim 6 , wherein the transparent medium layer having the smallest refractive index is located between two adjacent ones of the electrical or optical element layers, and a refractive index of the transparent medium layer having the smallest refractive index is less than refractive indexes of the two adjacent ones of the electrical or optical element layers.

8. The display device of claim 7 , wherein a refractive index of the transparent medium layer located above the electrical or optical element layer most away from the reflective display panel is less than the refractive indexes of the two adjacent ones of the electrical or optical element layers sandwiching the one having the smallest refractive index among the transparent medium layers.

9. The display device of claim 6 , wherein the transparent medium layer having the smallest refractive index is located between two adjacent ones of the electrical or optical element layers, and a refractive index of the transparent medium layer having the smallest refractive index is less than or equal to the refractive index of the transparent medium layer located above the electrical or optical element layer most away from the reflective display panel.

10. The display device of claim 6 , wherein the electrical or optical element layers comprise the light guide plate and at least one of a touch panel, a cover lens and an anti-glare film.