# US 12,007,662 B1 · Liquid crystal grating and holographic display device

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- Number: US 12,007,662 B1
- Document ID: US12007662B1
- Status: Granted
- Kind: B1
- Application number: 18/204,640
- Filed: 2023-06-01
- Granted: 2024-06-11
- Earliest claimed: 2023-03-31
- Assignees: Shanghai Tianma Micro-Electronics Co., Ltd.
- Applicants: Shanghai Tianma Micro-electronics Co., Ltd.
- Inventors: Yang Zeng; Feng Lu
- Web page: https://patentgrep.com/patent/US12007662B1

## CPC

- G02F 1/29: for the control of the position or the direction of light beams, i.e. deflection
- G02B 30/33: involving directional light or back-light sources
- G02F 2201/30: grating
- G02F 2203/12: spatial light modulator
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A liquid crystal grating and a holographic display device are provided. The liquid crystal grating includes grating electrode groups. The grating electrode group includes grating electrodes. Operation states of the liquid crystal grating include a first mode and a second mode. In the first mode, a first voltage of a first polarity is provided to the grating electrode, and an average voltage value of the first voltage is |V1|. In the second mode, a second voltage of a second polarity is provided to the grating electrode, and an average voltage value of the second voltage is |V2|, with |V1|<|V2|. In an operation period, light is modulated by the liquid crystal grating to obtain deflected light, the liquid crystal grating is switched between the first mode and the second mode, a quantity of the first mode is N1, and a quantity of the second mode is N2, with N1>N2.

## Claims

### Claim 1

A liquid crystal grating, comprising a plurality of grating electrode groups, wherein:
a grating electrode group of the plurality of grating electrode groups includes a plurality of grating electrodes;
operation states of the liquid crystal grating include a first mode and a second mode;
in the first mode, a first voltage of a first polarity is provided to a grating electrode of the plurality of grating electrodes, and for one grating electrode group of the plurality of grating electrode groups, an average voltage value of the first voltage is |V1|;
in the second mode, a second voltage of a second polarity is provided to the grating electrode, and for one grating electrode group of the plurality of grating electrode groups, an average voltage value of the second voltage is |V2|, wherein the first polarity is different from the second polarity, and |V1|<|V2|; and
in an operation period of the liquid crystal grating, light is modulated by the liquid crystal grating to obtain deflected light, the liquid crystal grating is switched between the first mode and the second mode, a quantity of the first mode is N1, and a quantity of the second mode is N2, wherein, N1 and N2 are positive integers, and N1>N2.

### Claim 2 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
|V1|, |V2|, N1, and N2 satisfy:
❘
"\[LeftBracketingBar]"
V
⁢
1
⁢
N
⁢
1
V
⁢
2
⁢
N
⁢
2
❘
"\[RightBracketingBar]"
=
m
,
wherein m is a first deviation correction coefficient, and 0.8≤m≤1.2.

### Claim 3 (depends on 2)

The liquid crystal grating according to claim 2, wherein
the first deviation correction coefficient m=1.

### Claim 4 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
|V1|, |V2|, N1, and N2 satisfy:
❘
"\[LeftBracketingBar]"
V
⁢
1
V
⁢
2
-
N
⁢
2
N
⁢
1
❘
"\[RightBracketingBar]"
=
n
,
wherein n is a second deviation correction coefficient, and n≤0.5.

### Claim 5 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
along an arrangement direction of the grating electrodes, potential magnitudes of the plurality of grating electrodes in a same grating electrode group of the plurality of grating electrode groups increase sequentially; and
the average voltage of the grating electrode group is an arithmetic mean value of the potential magnitudes of the plurality of grating electrodes included in the grating electrode group.

### Claim 6 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
the operation state of the liquid crystal grating is that the first mode and the second mode are alternately arranged.

### Claim 7 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
the operation state of the liquid crystal grating is that a plurality of the first modes is adjacently arranged, and a plurality of the second modes is adjacently arranged.

### Claim 8 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
the operation period includes N display total frames, wherein N=N1+N2, and the display total frame includes at least a first color frame;
in the first color frame, a first type of light is modulated by the liquid crystal grating to obtain first deflected light; and
in one operation period of the liquid crystal grating, in at least one of the first color frame, the operation state of the liquid crystal grating is the first mode, and in at least one of the first color frame, the operation state of the liquid crystal grating is the second mode.

### Claim 9 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
the operation period includes N display total frames, wherein N=N1+N2, and one display total frame of the N display total frames includes a plurality of subframes; and
in one display total frame of the liquid crystal grating, in at least one subframe of the plurality of subframes, the operation state of the liquid crystal grating is the first mode, and in at least one subframe of the plurality of subframes, the operation state of the liquid crystal grating is the second mode.

### Claim 10 (depends on 9)

The liquid crystal grating according to claim 9, wherein:
the display total frame includes M subframes, wherein M is a positive integer; and
a quantity of the subframes in which the operation state of the liquid crystal grating is the first mode is M1, and a quantity of the subframes in which the operation state of the liquid crystal grating is the second mode is M2, wherein M1=M2.

### Claim 11 (depends on 9)

The liquid crystal grating according to claim 9, wherein:
the display total frame includes M subframes, wherein M is a positive integer; and
a quantity of the subframes in which the operation state of the liquid crystal grating is the first mode is M1, and a quantity of subframes in which the operation state of the liquid crystal grating is the second mode is M2, wherein M1>M2.

### Claim 12 (depends on 9)

The liquid crystal grating according to claim 9, wherein:
the subframe includes a first subframe and a second subframe;
the operation state of the liquid crystal grating in the first subframe is the first mode, and the operation state of the liquid crystal grating in the second subframe is the second mode; and
the first subframe is configured for modulating a first type of light, and the second subframe is configured for modulating a second type of light, wherein colors of the first type of light and the second type of light are different.

### Claim 13 (depends on 12)

The liquid crystal grating according to claim 12, wherein:
the first subframe is configured for modulating the first color light, and the second subframe is configured for modulating the second color light, wherein a wavelength of the first color light is smaller than a wavelength of the second color light.

### Claim 14 (depends on 9)

The liquid crystal grating according to claim 9, wherein:
the subframe includes a third subframe and a fourth subframe;
the operation state of the liquid crystal grating in the third subframe is the first mode, and the operation state of the liquid crystal grating in the fourth subframe is the second mode; and
the third subframe is configured for modulating a third type of light, and the fourth subframe is configured for modulating a fourth type of light, wherein the third type of light and the fourth type of light have a same color and different deflection angles.

### Claim 15 (depends on 9)

The liquid crystal grating according to claim 9, wherein:
the display total frame includes a first color frame, a second color frame and a third color frame that modulate light of different colors; and
the first color frame includes two subframes, the second color frame includes two subframes, and the third color frame includes two subframes.

### Claim 16 (depends on 15)

The liquid crystal grating according to claim 15, wherein:
in the two subframes included in the first color frame, the operation states of the liquid crystal grating are the first mode and the second mode respectively.

### Claim 17 (depends on 1)

The liquid crystal grating according to claim 1, wherein:
the first polarity is positive polarity, and the second polarity is negative polarity.

### Claim 18 (depends on 1)

The liquid crystal grating according to claim 1,
in the first mode, a first voltage of a first polarity is provided to a grating electrode of the plurality of grating electrodes, and for one grating electrode group of the plurality of grating electrode groups, a maximum voltage value of the first voltage is |V1max|; and
in the second mode, a second voltage of a second polarity is provided to the grating electrode, and for one grating electrode group of the plurality of grating electrode groups, a maximum voltage value of the second voltage is |V2max|, wherein the first polarity is different from the second polarity, and |V1max|<|V2max|.

### Claim 19

A holographic display device, comprising a liquid crystal grating, wherein the liquid crystal grating includes a plurality of grating electrode groups, wherein:
a grating electrode group of the plurality of grating electrode groups includes a plurality of grating electrodes;
operation states of the liquid crystal grating include a first mode and a second mode;
in an operation period of the liquid crystal grating, light is modulated by the liquid crystal grating to obtain deflected light, the liquid crystal grating is switched between the first mode and the second mode, a quantity of the first mode is N1, and a quantity of the second mode is N2, wherein, N1 and N2 are positive integers, and N1>N2; and
in the first mode, a first voltage of a first polarity is provided to a grating electrode of the plurality of grating electrodes, and for one grating electrode group of the plurality of grating electrode groups, an average voltage value of the first voltage is |V1|, and in the second mode, a second voltage of a second polarity is provided to the grating electrode, and for one grating electrode group of the plurality of grating electrode groups, an average voltage value of the second voltage is |V2|, wherein the first polarity is different from the second polarity, and |V1|<|V2|; or, in the first mode, a first voltage of a first polarity is provided to a grating electrode of the plurality of grating electrodes, and for one grating electrode group of the plurality of grating electrode groups, a maximum voltage value of the first voltage is |V1max|, and in the second mode, a second voltage of a second polarity is provided to the grating electrode, and for one grating electrode group of the plurality of grating electrode groups, a maximum voltage value of the second voltage is |V2max|, wherein the first polarity is different from the second polarity, and |V1max|<|V2max|.

### Claim 20 (depends on 19)

The holographic display device according to claim 19, further comprising:
a field lens, a spatial light modulator, and a backlight source, wherein the spatial light modulator, the field lens, and the liquid crystal grating are sequentially disposed on a side of a light exiting surface of the backlight source.