Deformable micromirror device

• US 20080158442A1
• Filed: 12/26/2007
• Published: 07/03/2008
• 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
• Granted Patent: US 7,982,690 B2
• Time in Patent Office: Days
• US Class Current: 348/771
• 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 making an image display with digital image data, comprising:

pixel elements, each of which makes pulse width modulation (PWM) for incident light depending on a deflection state of light and which are arranged in a form of an array, wherein;

the array of said 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 said 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]; and

M_s, N_s, B, C_t, R, C, and 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 made with a color sequential display of C₀ colors.

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

pixel elements of 1920×

1080 [pixels] 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 () 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 () 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 (ε

_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:

each of said pixel elements has, as deflection states, an ON state for deflecting incident light to projection optics, an OFF state for deflecting incident light to a direction different from the projection optics, and an oscillation state where the mirror oscillates between the ON and the OFF states.

9. A micromirror device for making an image display with digital image data, comprising:

pixel elements, each of which makes pulse width modulation (PWM) for incident light depending on a deflection state of light and which are arranged in a form of an array, wherein;

the array of said 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 said 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]; and

M_s, N_s, B, C_t, R, C, C₀, and 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 made with a color sequential display of C₀ colors.

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

pixel elements of 1920×

1080 [pixels] 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 any of Al, Cu, Au, and Ag, or an alloy containing these substances.

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

an inter-layer dielectric film of the ROW line contains any 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 fluorine (F) or carbon (C).

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

each of said pixel elements has, as deflection states, an ON state for deflecting incident light to projection optics, an OFF state for deflecting incident light to a direction different from the projection optics, and an oscillation state where the mirror oscillates between the ON and the OFF states.

15. A micromirror device for making an image display with digital image data, comprising:

pixel elements, each of which makes pulse width modulation (PWM) for incident light depending on a deflection state of light and which are arranged in a form of an array, wherein;

the array of said 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 said 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]; and

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 corresponding to a least significant bit (LSB) in a gray scale of the micromirror device.

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

pixel elements of 1920×

1080 [pixels] 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 any of Al, Cu, Au, and Ag, or an alloy containing these substances.

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

an inter-layer dielectric film of the ROW line contains any of SiO₂, SiC, SiOC, and SiOF.

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

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

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

at least one ROW line decoder for arbitrarily selecting and driving a ROW line; and

at least one COLUMN line driver for loading the image data into each memory cell via a COLUMN line.

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

in the B subsets,

a first ROW line decoder and a first COLUMN line driver are connected to a first subset,

a second ROW line decoder and a second COLUMN line driver are connected to a second subset, and

the first and the second subsets are individually controlled so that the image data can be loaded at independent timings.

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

a data selector, wherein

said data selector distributes bit data of image data corresponding to each of the plurality of subsets in different order.

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

each of said pixel elements has, as deflection states, an ON state for deflecting incident light to projection optics, an OFF state for deflecting incident light to a direction different from the projection optics, and an oscillation state where the mirror oscillates between the ON and the OFF states.