Print head and image forming apparatus including the same
Provided are a print head and an image forming apparatus. The print head, which selectively irradiates light to each pixel of an image on a photoconductor, the print head includes an illumination unit, which emits light, a liquid crystal layer, which transmits or intercepts the light incident from the illumination unit on a unit pixel basis according to an applied voltage, and a microlens array formed of liquid crystal polymer, which either focuses or does not focus the light passed through the liquid crystal layer onto the photoconductor.
1. A print head for forming a latent image on a photoconductor, comprising:
an illumination unit including at least one light source configured to emit a light;
a liquid crystal layer configured to selectively transmit the light received from the illumination unit to selected ones of pixels corresponding to the latent image according to an applied voltage;
a microlens array formed of liquid crystal polymer, which has a birefringence index to condense or disperse light by using a refractive index difference according to a polarization of the light, the microlens array being configured to selectively focus the light passed through the liquid crystal layer onto the photoconductor;
a first alignment layer formed in a lens shape on a first side of the microlens array, wherein the microlens array is formed between the first alignment layer and a side of the liquid crystal layer farthest from the illumination unit; and
a second alignment layer formed adjacent a side of the liquid crystal layer closest to the illumination unit such that the liquid crystal arrangement is uniform and the liquid crystal arrangement deviation between the pixels decrease.
2. The print head of claim 1 , wherein the microlens array comprises a plurality of convex lens cells arranged to extend along a width direction of the photoconductor.
3. The print head of claim 1 , further comprising:
a first surface adjacent to the liquid crystal layer, the first surface forming a plane; and
a second surface facing the first surface, the second surface forming a plurality of convex lens cells.
4. The print head of claim 1 , further comprising: an ultraviolet (UV) curable polymer layer formed in a lens shape, adjacent the microlens array.
5. The print head of claim 1 , wherein the illumination unit further comprises:
a collimating lens, which collimates the light irradiated from the at least one light source.
6. The print head of claim 1 , wherein the at least one light source comprises:
a first light source, which irradiates first color light;
a second light source, which irradiates second color light; and
a third light source, which irradiates third color light, and
wherein the illumination unit further comprises:
a first dichroic filter and a second dichroic filter,
wherein the first dichroic filter and second dichroic filter are positioned unparallel to one another such that the first color light passes through the first and second dichroic filters, the second color light is reflected by the first dichroic filter and passed through the second dichroic filter, and the third color light is reflected by the second dichroic filter,
and the first, second, and third color lights are emitted on a common optical path to form the latent image on the photoconductor.
7. The print head of claim 6 , wherein the first dichroic filter and the second dichroic filter are disposed so as to form an angle with respect to each other along a path of the first color light.
8. The print head of claim 1 , wherein the illumination unit comprises any one selected from a light emitting diode (LED), an organic light emitting diode (OLED), inorganic electroluminescence (EL), organic EL, a fluorescent lamp and a xenon lamp.
9. The print head of claim 1 , wherein the liquid crystal layer is formed of one of a ferroelectric liquid crystal and a paraelectric liquid crystal.
10. An image forming apparatus, comprising:
a photoconductor having a photoconductive surface on which a latent image is formed;
a print head including an illumination unit having at least one light source configured to emit a light, a liquid crystal layer configured to selectively transmit the light received from the illumination unit to selected ones of pixels corresponding to the latent image according to an applied voltage, a microlens array formed of liquid crystal polymer, which has a birefringence index to condense or disperse light by using a refractive index difference according to a polarization of the light, the microlens array being configured to selectively focus the light passed through the liquid crystal layer onto the photoconductor, a first alignment layer formed in a lens shape on a first side of the microlens array wherein the microlens array is formed between the first alignment layer and a side of the liquid crystal layer farthest from the illumination unit, and a second alignment layer formed adjacent a side of the liquid crystal layer closest to the illumination unit such that the liquid crystal arrangement is uniform and the liquid crystal arrangement deviation between the pixels decrease;
a developing unit configured to supply a developer to the latent image on the photoconductor to form a developer image;
a transferring unit configured to transfer the developer image formed on the photoconductor to a printing medium; and
a fixing unit configured to fixes the transferred developer image to the printing medium.
11. The image forming apparatus of claim 10 , wherein the microlens array comprises a plurality of convex lens cells arranged to extend along a width direction of the photoconductor.
12. The image forming apparatus of claim 10 , further comprising:
a first surface adjacent to the liquid crystal layer, the first surface forming a plane; and
a second surface facing the first surface, the second surface forming a plurality of convex lens cells.
13. The image forming apparatus of claim 10 , further comprising: an ultraviolet (UV) curable polymer layer formed in a lens shape, adjacent the microlens array.
14. The image forming apparatus of claim 10 , wherein the illumination unit further comprises:
a collimating lens, which collimates the light irradiated from the at least one light source.
15. The image forming apparatus of claim 10 , wherein the at least one light source comprises:
a first light source, which irradiates first color light;
a second light source, which irradiates second color light; and
a third light source, which irradiates third color light, and
wherein the illumination unit further comprises:
a first dichroic filter and a second dichroic filter,
wherein the first dichroic filter and second dichroic filter are positioned unparallel to one another such that the first color light passes through the first and second dichroic filters, the second color light is reflected by the first dichroic filter and passed through the second dichroic filter, and the third color light is reflected by the second dichroic filter, and the first, second, and third color lights are emitted on a common optical path to form the latent image on the photoconductor.
16. The image forming apparatus of claim 15 , wherein the first dichroic filter and the second dichroic filter are disposed so as to form an angle with respect to each other along a path of the first color light.
17. The image forming apparatus of claim 10 , wherein the illumination unit comprises any one selected from a light emitting diode (LED), an organic light emitting diode (OLED), inorganic electroluminescence (EL), organic EL, a fluorescent lamp and a xenon lamp.
18. The image forming apparatus of claim 10 , wherein the liquid crystal layer is formed of one of a ferroelectric liquid crystal and a paraelectric liquid crystal.