TWI427353B - Projection zoom lens - Google Patents

Description

Zoom projection lens

The present invention relates to a zoom projection lens.

With the development of semiconductor technology, various projectors, such as digital light processing (DLP) projectors, liquid crystal display (LCD) projectors, and liquid crystal on silicon (LCoS) projectors, A spatial light modulator (SLM), such as a digital micro-mirror device (DMD), a liquid crystal display panel (LCD panel), and an LCoS chip, is used to enhance the primitives. In the direction of miniaturization, it meets the requirements of consumers for the quality of projection screens and portability. Therefore, corresponding to the primitive requirements and size requirements of the spatial light modulator, the zoom projection lens (generally disposed in front of the spatial light modulator) applied to the projector also needs to be downsized while ensuring good projected picture quality.

In view of this, it is necessary to provide a zoom projection lens with high projection quality and miniaturization.

A zoom projection lens includes a first lens group of negative refractive power and a second lens group of positive refractive power sequentially from an enlarged end to a reduced end along an optical axis direction thereof. The first lens group includes a first lens of negative power. The second lens group is placed along the optical axis direction The big end to the reduced end sequentially includes a second lens of positive power, a third lens of positive power, a fourth lens of negative power, and a fifth lens of positive power. During the zoom projection lens, the first lens group and the second lens group move along the optical axis during the wide-angle end to the telephoto end conversion. The zoom projection lens satisfies the following conditional formula: (1) 1.9 <|F1/Fw|<2.1

(2)0.5<|f4/Fw|<0.8

(3)0.95<|f5/Fw|<1.2

Wherein F1 is the effective focal length of the first lens group, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, and Fw is the effective focal length of the zoom projection lens at the wide-angle end.

The above three conditional expressions reasonably distribute the power of the first lens group and the second lens group, so that the astigmatism and spherical aberration of the zoom projection lens are effectively controlled to improve the projection quality, and the zoom projection lens is also smaller. Chemical.

10‧‧‧ zoom projection lens

100‧‧‧First lens group

200‧‧‧second lens group

300‧‧‧ imaging surface

102‧‧‧First lens

202‧‧‧second lens

204‧‧‧ third lens

206‧‧‧Fourth lens

208‧‧‧ fifth lens

20‧‧‧Light

400‧‧‧Stainless glass

S1~S12‧‧‧first surface to twelfth surface

1 is a schematic view showing the structure of a zoom projection lens of the present invention in a wide-angle end state.

2 is a schematic structural view of the zoom projection lens of the present invention in a telephoto end state.

3 is a spherical aberration diagram of the zoom projection lens of FIG. 1.

4 is a field curvature diagram of the zoom projection lens of FIG. 1.

FIG. 5 is a distortion diagram of the zoom projection lens of FIG. 1. FIG.

6 is a lateral chromatic aberration diagram of the zoom projection lens of FIG. 1.

FIG. 7 is a spherical aberration diagram of the zoom projection lens of FIG. 2. FIG.

FIG. 8 is a field curvature diagram of the zoom projection lens of FIG. 2. FIG.

9 is a distortion diagram of the zoom projection lens of FIG. 2.

FIG. 10 is a lateral chromatic aberration diagram of the zoom projection lens of FIG. 2. FIG.

The following preferred embodiments will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 , a zoom projection lens 10 according to a preferred embodiment of the present invention includes a first lens group 100 having a negative refractive power in a sequence from an enlarged end to a reduced end (near the SLM end) in the optical axis direction thereof. A second lens group 200 having positive power and an imaging surface 300.

The first lens group 100 includes a first lens 102 of negative power. The first lens 102 includes a first surface S1 near the enlarged end and a second surface S2 near the reduced end.

The second lens group 200 sequentially includes a second lens 202 of positive power, a third lens 204 of positive power, a fourth lens 206 of one negative power, and one from the enlarged end to the reduced end in the optical axis direction. A fifth lens 208 of positive power. The second lens 202 includes a third surface S3 adjacent to the enlarged end and a fourth surface S4 near the reduced end. The third lens 204 includes a fifth surface S5 adjacent to the enlarged end and a sixth surface S6 near the reduced end. The fourth lens 206 includes a seventh surface S7 near the enlarged end and an eighth surface S8 near the reduced end. The fifth lens 208 includes a ninth surface S9 near the enlarged end and a tenth surface S10 near the reduced end.

The zoom projection lens 10 can be applied to a DLP projector. During projection, the SLM-modulated projection signal light is projected from an SLM surface 93 to the zoom projection lens 10, and the light is sequentially passed through the second lens group 200 and the first lens group 10, and projected onto a screen (not shown) to be projected. Picture. In the zoom projection lens, the first lens group 100 and the second lens group 200 move along the optical axis during the wide-angle end to the telephoto end conversion. In the present embodiment, the zoom projection lens 10 achieves a zoom projection of 1.1 times, and the surfaces of all the lenses are spherical.

In order to achieve miniaturization, the zoom projection lens 10 satisfies the following conditional formula: (1) 1.9 <|F1/Fw|<2.1; (2) 0.5 <|f4/Fw|<0.8; (3) 0.95<|f5/ Fw|<1.2.

Wherein F1 is the effective focal length of the first lens group, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, and Fw is the effective focal length of the zoom projection lens at the wide-angle end. The conditional expression (1) limits the total optical length of the zoom projection lens 10. Conditional equations (2) and (3) correct field curvature and aberrations. In this way, the three conditional expressions properly distribute the optical power of the first lens group 100 and the second lens group 200, so that the astigmatism and spherical aberration of the zoom projection lens 10 are effectively controlled to improve the projection quality, and the zoom is performed. The projection lens 10 is also small in size.

Preferably, the zoom projection lens 100 further satisfies the following condition: (4) L*Φw<3.8.

Wherein, L is the total optical length when the zoom projection lens 10 is located at the wide-angle end, and Φw is the power when the zoom projection lens 100 is located at the wide-angle end. The conditional expression (4) further limits the optical total length and zoom ratio of the zoom projection lens 10 (i.e., the ratio of the effective focal length of the zoom projection lens 10 at the telephoto end to the effective focal length at the wide angle end).

Preferably, the zoom projection lens 100 also satisfies the following condition: (5) w ≧ 27°.

Where w is the zoom projection lens 100 at a wide angle end half angle of view.

Preferably, the zoom projection lens 100 further includes an aperture stop 20 disposed between the third lens 204 and the fourth lens 206 to limit the amount of light passing through the first lens group 100. The zoom projection lens 100 moves during the zooming process with the second lens group 200, and the pupil aperture remains unchanged.

Preferably, the zoom projection lens 100 further includes a glass piece 400 disposed between the second lens group 200 and the imaging surface 300 to protect the zoom projection lens 100. The glass piece 400 includes an eleventh surface S11 near the enlarged end and a twelfth surface S12 near the reduced end.

In the present embodiment, the optical elements of the zoom projection lens 100 satisfy the conditions of Tables 1 and 2, wherein F1=-44.5, f4=-14.675, f5=23.96, Fw=22.1, L=83 mm, Φw=0.045, w = 26.95 °.

In Tables 1 and 2, R is the radius of curvature of the corresponding surface, D is the on-axis distance from the corresponding surface to the latter surface (the length of the optical axis of the two surfaces, the same below), and Nd is the corresponding lens pair d The refractive index of light (wavelength is 587 nm, the same below), Vd is the Abbe number of the corresponding lens group (abbe number, the same below); f is the effective focal length of the zoom projection lens 100, and L is the zoom projection lens 100 The total optical length, F# is the number of apertures, D1 is the on-axis distance from the second surface S2 to the third surface S3, and D2 is the on-axis distance from the tenth surface S10 to the imaging surface 300.

Table 1

When the zoom projection lens 100 of the present embodiment is at the wide-angle end, aberrations, field curvatures, distortions, and lateral chromatic aberrations are as shown in FIGS. 3 to 6, respectively. In FIG. 3, according to the spherical aberration curve observed for light having wavelengths of 460 nm, 550 nm, and 610 nm, the zoom projection is performed. When the shadow lens 100 is at the wide-angle end, the aberration value generated for visible light (wavelength ranging from 400 nm to 700 nm) is controlled within the range of (-0.3 mm, 0.3 mm). In Fig. 4, the curves T and S are the tangential field curvature characteristic curve and the sagittal field curvature characteristic curve, respectively. It can be seen that the meridional curvature value and the sagittal curvature value are controlled within the range of (-0.3 mm, 0.3 mm). As can be seen from Fig. 5, the distortion variable is controlled within the range of (-2%, 0). According to FIG. 6, the lateral color difference value of the zoom projection lens 100 for visible light is controlled within a range of (-4 um, 4 um).

When the zoom projection lens 100 of the present embodiment is at the telephoto end, its aberration, curvature of field, distortion, and lateral chromatic aberration are as shown in FIGS. 7 to 10, respectively. In FIG. 7, according to the spherical aberration curve observed for light having wavelengths of 460 nm, 550 nm, and 610 nm, the aberration value of the visible light generated by the zoom projection lens 100 at the telephoto end is controlled at (-0.3 mm, 0.3 mm). Within the scope. In Fig. 8, the meridional field curvature value and the sagittal field curvature value are controlled within the range of (-0.3 mm, 0.3 mm). As can be seen from Fig. 9, the distortion variable is controlled within the range of (-2%, 0). According to FIG. 10, the lateral color difference value of the zoom projection lens 100 for visible light is controlled within a range of (-4 um, 4 um). It can be seen that the spherical aberration, field curvature, distortion, and lateral chromatic aberration of the zoom projection lens 100 at the wide-angle end and the photographic end can be controlled (corrected) in a small range.

It should be understood by those skilled in the art that the above embodiments are merely illustrative of the invention, and are not intended to limit the invention, as the scope of the spirit of the invention Changes and modifications are intended to fall within the scope of the invention.

10‧‧‧ zoom projection lens

100‧‧‧First lens group

200‧‧‧second lens group

300‧‧‧ imaging surface

102‧‧‧First lens

202‧‧‧second lens

204‧‧‧ third lens

206‧‧‧Fourth lens

208‧‧‧ fifth lens

20‧‧‧Light

400‧‧‧Stainless glass

S1~S12‧‧‧first surface to twelfth surface

Claims (7)

A zoom projection lens includes a first lens group of negative refractive power and a second lens group of positive refractive power sequentially from an enlarged end to a reduced end along an optical axis direction thereof; the first lens group includes a negative optical focus a first lens of the degree; the second lens group sequentially includes a second lens of positive power, a third lens of positive power, and a third of negative optical power from the enlarged end to the reduced end in the optical axis direction a fourth lens having a four-lens and a positive power; the zoom lens is moved along the optical axis during the wide-angle end to the telephoto end conversion; the zoom projection lens satisfies The following conditional expression: 1.9<|F1/Fw|<2.1; 0.5<|f4/Fw|<0.8; 0.95<|f5/Fw|<1.2; wherein F1 is the effective focal length of the first lens group, and f4 is the The effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, and Fw is the effective focal length of the zoom projection lens at the wide-angle end. The zoom projection lens according to claim 1, wherein the zoom projection lens further satisfies the following conditional formula: L*Φw=3.735; wherein L is the total optical length of the zoom projection lens at the wide-angle end, and Φw is The power of the zoom projection lens at the wide-angle end. The zoom projection lens of claim 1, wherein the zoom projection lens further satisfies the following condition: w=26.95°; wherein w is the half angle of view of the zoom projection lens at the wide angle end. The zoom projection lens of claim 1, wherein the zoom projection lens further comprises an aperture disposed between the third lens and the fourth lens. The zoom projection lens of claim 1, wherein the zoom projection lens further comprises a glass piece disposed between the second lens group and the imaging surface of the zoom projection lens. The zoom projection lens of claim 1, wherein the zoom projection lens achieves a zoom projection of 1.1 times. The zoom projection lens of claim 1, wherein the surfaces of all the lenses are spherical.