Deformable micromirror device

• US 7,982,690 B2
• Filed: 12/26/2007
• Issued: 07/19/2011
• Est. Priority Date: 12/27/2006
• Status: Active Grant

• Current Assignee: Ignite USA (Ignite), Olympus Corporation
• Original Assignee: Olympus Corporation, Silicon Quest Kabushiki-Kaisha
• Inventors: Maeda, Yoshihiro, Arai, Kazuma, Ishii, Fusao
• Primary Examiner(s): OSORIO, RICARDO
• Application Number:
  US12/005,501
• Publication Number:
  US 20080158442A1
• Time in Patent Office: 1,301 Days
• Field of Search: 345/32, 345/55, 345 87- 89, 345 98-100, 345/103, 345/690, 345/84
• US Class Current: 345/32
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: H04N 9/3123 using pulse width modulation

Abstract

A micromirror device, which makes an image display with digital image data, comprises pixel elements each of which makes pulse width modulation for incident light depending on the deflection state of light and which are arranged in the form of an array. The array of the pixel elements is composed of B subsets each including pixel elements of M_s (COLUMNs)×N_s (ROWs) (M_s, N_s, and B are natural numbers). Each of the pixel elements has a mirror, and at least one memory cell. The memory cell has a transistor of an input gate capacity C_t[F]. Each memory cell is connected by a ROW line having a wiring resistance R[Ω], and a wiring capacity C[F]. When a gray scale display of 10 [bits] or more for each color is made with a color sequential display of C₀ colors, M_s, N_s, B, C_t, R, C, and C₀ have a relationship of R*(C_t+C)<(1.63*10⁻⁵*B)/[C_o*M_s*N_s*(M_s+1)].

Claims

1. A micromirror device for applying a digital image data to display an image comprising:

a plurality of pixel elements arranged in a form of an array and grouped into B subsets each including pixel elements configured as M_s columns and N_s rows represented by M_s (COLUMNs)×

N_s (ROWs) wherein-M_s, N_s and B are positive integers;

each of said pixel elements has a mirror, and at least one memory cell to pulse width modulate (PWM) an incident light;

the memory cell has a transistor of an input gate capacity C_t[F];

each memory cell is connected by a ROW line having a wiring resistance R[106 ], and a wiring capacity C[F]; and

wherein the parameters represented by

M_s, N_s, B, C_t, R, C, and a number of colors represented by C₀ have a relationship of R*(C_t+C)<

(1.63*10<sup>−

5</sup>*B)/[C_o*M_s*N_s*(M_s+1)], when a gray scale display of 10 bits or more for each color is presented with a color sequential display of C₀ colors.

2. The micromirror device according to claim 1, comprising:

said array of said pixel elements of comprising an array of 1920×

1080 pixel elements or more wherein a pitch of the mirror is equal to or larger than 4 um, and equal to or smaller than 10 um.

3. The micromirror device according to claim 2, wherein:

a cross-sectional area of the ROW line is equal to or larger than 6.1*10<sup>−

15</sup> m².

4. The micromirror device according to claim 2, wherein:

an electrical resistivity (ρ

) of a material of the ROW line is equal to or smaller than 2.65*10<sup>−

8</sup> Ω

m.

5. The micromirror device according to claim 2, wherein

a cross-sectional area of the ROW line is equal to or larger than 3.9*10⁻

15 m².

6. The micromirror device according to claim 2, wherein:

an electrical resistivity (ρ

) of a material of the ROW line is equal to or smaller than 1.68*10<sup>−

8</sup> Ω

m.

7. The micromirror device according to claim 1, wherein:

a relative permittivity (∈

_r) of an inter-layer dielectric film of the ROW line is equal to or smaller than 3.8 F/m.

8. The micromirror device according to claim 1, wherein:

the mirror of each of said pixel elements is controllable to deflect to an ON deflection angle for reflecting an incident light to projection optics, an OFF deflection angle for reflecting the incident light to a direction away from the projection optics, and an oscillation state with the mirror oscillates between the ON and the OFF deflection angles.

9. A micromirror device for applying a digital image data to display an image, comprising:

a plurality of pixel elements arranged in a form of an array and grouped into B subsets each including pixel elements configured as M_s columns and N_s rows represented by M_s (COLUMNs)×

N_s (ROWs) wherein-M_s, N_s and B are positive integers);

each of said pixel elements has a mirror, and at least one memory cell to pulse width modulate (PWM) an incident light;

the memory cell has a transistor of an input gate capacity C_t[F];

each memory cell is connected by a ROW line having a wiring resistance R[Ω

], and a wiring capacity C[F]; and

wherein the parameters represented by

M_s, N_s, B, C_t, R, C, and a number of colors represented by C₀, and a number of gray scales represented by a bit number G_s have a relationship of R*(C_t+C)<

B*[60*C_o*(2^Gs−

1)*M_s*N_s*(M_s+1)]<sup>−

1</sup>, when a gray scale display of G_s [bits] for each color is presented with a color sequential display of C₀ colors.

10. The micromirror device according to claim 9, comprising:

said array of said pixel elements comprising an array of 1920×

1080 pixel elements or more wherein a pitch of the mirror is equal to or larger than 4 um, and equal to or smaller than 10 um.

11. The micromirror device according to claim 9, wherein:

a wiring material of the ROW line is composed of a material selected from a group of materials consisted of Al, Cu, Au, and Ag, or an alloy containing one of the materials.

12. The micromirror device according to claim 9, wherein:

an inter-layer dielectric film of the ROW line contains one of a materials selected from a group of materials consisted of SiO₂, SiC, SiOC, and SiOF.

13. The micromirror device according to claim 9, wherein:

an inter-layer dielectric film of the ROW line is doped with a dopant selected from fluorine (F) or carbon (C).

14. The micromirror device according to claim 9, wherein:

the mirror of each of said pixel elements is controllable to deflect to an ON deflection angle for reflecting an incident light to projection optics, an OFF deflection angle for reflecting the incident light to a direction away from the projection optics, and an oscillation state with the mirror oscillates between the ON and the OFF deflection angles.

15. A micromirror device for applying a digital image data to display an image comprising:

a plurality of pixel elements arranged in a form of an array and grouped into B subsets each including pixel elements configured as M_s columns and N_s rows represented by M_s (COLUMNs)×

N_s (ROWs) wherein-M_s, N_s and B are positive integers;

each of said pixel elements has a mirror, and at least one memory cell to pulse width modulate (PWM) an incident light;

the memory cell has a transistor of an input gate capacity C_t[F];

the memory cell has a transistor of an input gate capacity C_t[F];

each memory cell is connected by a ROW line having a wiring resistance R[Ω

], and a wiring capacity C[F]; and

wherein the parameters represented by

M_s, N_s, C_t, R, and C have a relationship of τ

>

[R*(C_t+C)*M_s*(M_s+1)*N_s], for a minimum display duration τ

(sec) of each of said pixel elements for the digital image data.

16. The micromirror device according to claim 15, wherein:

the minimum display duration is a duration modulated by applying a least significant bit (LSB) of the digital image data to control the micromirror device.

17. The micromirror device according to claim 15, comprising:

said array of said pixel elements comprising an array of 1920×

1080 pixel elements or more wherein a pitch of the mirror is equal to or larger than 4 um, and equal to or smaller than 10 um.

18. The micromirror device according to claim 15, wherein:

a wiring material of the ROW line is composed of a material selected from a group of materials consisted of Al, Cu, Au, and Ag, or an alloy containing one of the materials.

19. The micromirror device according to claim 15, wherein:

an inter-layer dielectric film of the ROW line contains one of a materials selected from a group of materials consisted of SiO₂, SiC, SiOC, and SiOF.

20. The micromirror device according to claim 15, wherein:

an inter-layer dielectric film of the ROW line is doped with a dopant selected from fluorine (F) or carbon (C).

21. The micromirror device according to claim 15, further comprising:

at least one ROW line decoder for non-sequentially selecting and driving a ROW line; and

at least one COLUMN line driver for loading the image data into the memory cell in the pixel element on the selected ROW line via a COLUMN line.

22. The micromirror device according to claim 15, wherein:

a first ROW line decoder and a first COLUMN line driver are connected to a first subset as one of said B subsets of pixel elements,

a second ROW line decoder and a second COLUMN line driver are connected to a second subset as another of said B subsets of pixel elements, and

the first and the second subsets are individually controlled for independently loading the image data.

23. The micromirror device according to claim 15, comprising:

a data selector for distributing bits of the image data in different order for each of the plurality of subsets.

24. The micromirror device according to claim 15, wherein:

the mirror of each of said pixel elements is controllable to deflect to an ON deflection angle for reflecting an incident light to projection optics, an OFF deflection angle for reflecting the incident light to a direction away from the projection optics, and an oscillation state with the mirror oscillates between the ON and the OFF deflection angles.