# US 12,181,646 B2 · Optical system and projection device

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- Number: US 12,181,646 B2
- Document ID: US12181646B2
- Status: Granted
- Kind: B2
- Application number: 17/518,812
- Filed: 2021-11-04
- Published: 2022-07-14
- Granted: 2024-12-31
- Earliest claimed: 2021-01-13
- Assignees: Union Optech Co., Ltd.
- Applicants: Union Optech Co., Ltd.
- Inventors: Liwei Quan; Shoulin Li; Hao Wang; Junqiang Gong
- Web page: https://patentgrep.com/patent/US12181646B2

## CPC

- G02B 13/16: for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV}
- G02B 3/04: with continuous faces that are rotationally symmetrical but deviate from a true sphere {, e.g. so called "aspheric" lenses}
- G02B 9/64: having more than six components
- G02B 13/0045: {having five or more lenses}
- G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)}
- G02B 27/0012: {Optical design, e.g. procedures, algorithms, optimisation routines}
- G03B 21/142: {Adjusting of projection optics}
- G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)

## Abstract

The present application provides an optical system and a projection device. The optical system includes a display unit, a first lens group, a second lens group and a reflector which are sequentially arranged along a light transmission direction. The first lens group has a positive focal power, the second lens group has a negative focal power, a total of focal powers of the second lens group and the reflector is positive. A distance from a side of the first lens group close to the display unit to another side of the second lens group far away from the display unit is T0, a distance from the side of the second lens group far away from the display unit to the reflector is T, and T0/T is greater than or equal to 0.8 and less than or equal to 1.1. The optical system provided by the present application is small in size and portable.

## Claims

### Claim 1

An optical system comprising a display unit, a first lens group, a second lens group, and a reflector which are sequentially arranged along a light transmission direction; wherein:
the first lens group has a positive focal power;
the second lens group has a negative focal power;
a total of focal powers of the second lens group and the reflector is positive; and
a distance from a side of the first lens group close to the display unit to a side of the second lens group far away from the display unit is T0, and a distance from the side of the second lens group far away from the display unit to the reflector is T, T0/T is greater than or equal to 0.8 and less than or equal to 1.1.

### Claim 2 (depends on 1)

The optical system of claim 1, wherein:
the focal power of the first lens group is greater than or equal to 0.1 and less than or equal to 0.2;
an absolute value of the focal power of the second lens group is greater than or equal to 0.01 and less than or equal to 0.03; and
the total of the focal powers of the second lens group and the reflector is greater than or equal to 0.15 and less than or equal to 0.3.

### Claim 3 (depends on 2)

The optical system of claim 2, wherein:
the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged along the light transmission direction;
the second lens group includes an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens and a fourteenth lens arranged along the light transmission direction; and
the optical system further comprises a diaphragm arranged between the first lens group and the second lens group.

### Claim 4 (depends on 3)

The optical system of claim 3, wherein:
the first lens, the second lens, the third lens, the fifth lens, the seventh lens, the ninth lens, the tenth lens and the twelfth lens have positive focal powers; and
the fourth lens, the sixth lens, the eighth lens, the eleventh lens, the thirteenth lens, and the fourteenth lens have negative focal powers.

### Claim 5 (depends on 3)

The optical system of claim 3, wherein:
the second lens is a biconvex glass aspherical lens having a positive focal power ϕ2, and 0.05≤|ϕ2|≤0.09; and
the fourteenth lens includes a side close to the display unit and curved toward the display unit, and another side away from the display unit and curved toward the reflector, and the fourteenth lens has a positive focal power ϕ14, and 0.015≤|ϕ14|≤0.025.

### Claim 6 (depends on 3)

The optical system of claim 3, wherein:
the fourteenth lens is a plastic aspherical lens having a negative focal power ϕ14′, and 0.01≤|ϕ14′|≤0.05; and
the fourteenth lens has an outer diameter D14, and D14/T0≥0.2.

### Claim 7 (depends on 3)

The optical system of claim 3, wherein:
the third lens, the fourth lens and the fifth lens are cemented together to form a cemented lens;
the sixth lens and the seventh lens are cemented together to form another cemented lens; and
the twelfth lens and the thirteenth lens are cemented together to form still another cemented lens.

### Claim 8 (depends on 1)

The optical system of claim 1, wherein:
a distance between the first lens group and the second lens group is greater than or equal to 5.9 mm and less than or equal to 6.4 mm; and
a distance between the second lens group and the reflector is greater than or equal to 29.25 mm and less than or equal to 29.75 mm.

### Claim 9 (depends on 1)

The optical system of claim 1, wherein:
the display unit includes a digital micromirror device (DMD) chip, wherein:
the DMD chip is offset from an optical axis for more than 130%; and
the DMD chip has a size greater than or equal to 0.23 inches and less than or equal to 0.33 inches.

### Claim 10 (depends on 1)

A projection device comprising the optical system of claim 1.

### Claim 11 (depends on 10)

The projection device of claim 10, wherein:
the focal power of the first lens group is greater than or equal to 0.1 and less than or equal to 0.2;
an absolute value of the focal power of the second lens group is greater than or equal to 0.01 and less than or equal to 0.03; and
a total of focal powers of the second lens group and the reflector is greater than or equal to 0.15 and less than or equal to 0.3.

### Claim 12 (depends on 11)

The projection device of claim 11, wherein:
the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged along the light transmission direction;
the second lens group includes an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens and a fourteenth lens arranged along the light transmission direction; and
the optical lens group further comprises a diaphragm arranged between the first lens group and the second lens group.

### Claim 13 (depends on 12)

The projection device of claim 12, wherein:
the first lens, the second lens, the third lens, the fifth lens, the seventh lens, the ninth lens, the tenth lens and the twelfth lens have positive focal powers; and
the fourth lens, the sixth lens, the eighth lens, the eleventh lens, the thirteenth lens, and the fourteenth lens have negative focal powers.

### Claim 14 (depends on 12)

The projection device of claim 12, wherein:
the second lens is a biconvex glass aspherical lens having a positive focal power ϕ2, and 0.05≤|ϕ2|≤0.09; and
the fourteenth lens comprises a side close to the display unit and curved toward the display unit, and another side away from the display unit and curved toward the reflector, and the fourteenth lens has a positive focal power ϕ14, and 0.015≤|ϕ14|≤0.025.

### Claim 15 (depends on 12)

The projection device of claim 12, wherein:
the fourteenth lens is a plastic aspherical lens having a negative focal power ϕ14′, and 0.01≤|ϕ14′|≤0.05; and
the fourteenth lens has an outer diameter D14, and D14/T0≥0.2.

### Claim 16 (depends on 12)

The projection device of claim 12, wherein:
the third lens, the fourth lens and the fifth lens are cemented together to form a cemented lens;
the sixth lens and the seventh lens are cemented together to form another cemented lens; and
the twelfth lens and the thirteenth lens are cemented together to form still another cemented lens.

### Claim 17 (depends on 10)

The projection device of claim 10, wherein:
a distance between the first lens group and the second lens group is greater than or equal to 5.9 mm and less than or equal to 6.4 mm; and
a distance between the second lens group and the reflector is greater than or equal to 29.25 mm and less than or equal to 29.75 mm.

### Claim 18 (depends on 10)

The projection device of claim 10, wherein the display unit comprises a DMD chip, wherein:
the DMD chip is offset from an optical axis for more than 130%; and
the DMD chip has a size greater than or equal to 0.23 inches and less than or equal to 0.33 inches.