TWI412813B - Zoom projection lens - Google Patents

Abstract

The present invention relates to a zoom projection lens. The zoom projection lens includes, in an order from a magnification side to a minification side thereof, a first lens group with negative refraction power, a second lens group with positive refraction power, a third lens group with positive refraction power, a fourth lens group with negative refraction power, and a fifth lens group with positive refraction power. The fifth lens group is unmovable along the optic axis of the zoom projection lens. The first lens group, second lens group, and the fourth lens group are moveable along the optic axis of the zoom projection lens. The zoom projection lens satisfies the following formulas: 1.0 < |F1/Fw| < 1.3; 2.5 < |F3/Fw| < 2.7; 2.81 < |F5/Fw| < 2.83; 0.21 < |F2/F4| < 0.24. Where F1, F2, F3, F4, F5 are the respective effective focal lengths of the first lens group, second lens group, the third lens group, the fourth lens group and the fifth lens group, Fw is the shortest effective focal length of the zoom projection lens.

Description

Zoom projection lens

The present invention relates to a zoom projection lens.

Many projectors now have a zoom function to accommodate different projection locations, such as open commercial spaces or small family entertainment venues. Such a zoom lens projector lens generally includes a plurality of lens groups, and the zoom function is realized by changing the relative position between the lens groups to change the effective focal length of the zoom projection lens. However, if the power distribution of each lens group is unreasonable, it may result in: (1) unable to effectively correct aberrations and distortions; (2) unable to meet the zoom projection lens (near DMD end) does not satisfy telecentricity (Telecentric) Imaging requirements.

In view of this, it is necessary to provide a zoom projection lens that can maintain high resolution during zooming.

A zoom projection lens includes, in order from the amplification end to the reduction end, a first lens group having a negative power, a second lens group having a positive power, a third lens group having a positive power, and a A fourth lens group having a negative power and a fifth lens group having a positive power. The fifth lens group is fixedly disposed, and the first lens group, the second lens group, the third lens group, and the fourth lens group are moved and disposed. The zoom projection lens satisfies the following conditional expression: 1.0<|F1/Fw|<1.3; 2.5<|F3/Fw|<2.7; 2.81<|F5/Fw|<2.83; 0.21<|F2/F4|<0.24; Wherein, F1, F2, F3, F4, and F5 are effective focal lengths of the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group, respectively, and Fw is effective for the zoom projection lens at the wide-angle end. focal length.

The power of the zoom projection lens is reasonably distributed in the above conditional expression to ensure that the zoom projection lens maintains a high resolution requirement during zooming.

The invention will be further described in detail below with reference to the accompanying drawings.

Please refer to FIG. 1 and FIG. 2 , which are schematic diagrams of a zoom projection lens 100 according to an embodiment of the present invention. The wide angle end angle ω of the zoom projection lens 100 is greater than or equal to 29 degrees. In this embodiment, the zoom projection lens 100 includes, in order from the amplification end to the reduction end (near DMD end), a first lens group 10 having a negative refractive power, a second lens group 20 having a positive power, and a A third lens group 30 having positive power, a fourth lens group 40 having negative power, and a fifth lens group 50 having positive power. The first lens group 10, the second lens group 20, the third lens group 30, and the fourth lens group 40 are disposed along the optical axis for changing the effective focal length of the zoom projection lens 100 to realize the zoom function. The fifth lens group 50 is fixedly disposed to prevent the DMD from being collided during zooming. In addition, the movement of the four lens groups by the first lens group 10, the second lens group 20, the third lens group 30, and the fourth lens group 40 can ensure the uniformity of the image quality over the entire focal length range. The first lens group 10 is a focus lens group.

In the embodiment, the zoom projection lens 100 is applied to a DMD projector. During projection, the DMD modulated projection signal light passes through the fifth lens group 50, the fourth lens group 40, and the third lens group 30 from the imaging surface 99. The second lens group 20 and the first lens group 10 are projected on a screen (not shown) to obtain a projected image. Specifically, when the DMD projector is projected, the projection signal light projected by the imaging surface 99 sequentially passes through the protective glass 98, the fifth flat glass 97, the fourth flat glass 96, the third flat glass 95, the second flat glass 94, and the first The flat glass 93 enters the zoom projection lens 100. The fifth flat glass 97, the fourth flat glass 96, the third flat glass 95, the second flat glass 94, and the first flat glass 93 may be plated with different functions, such as a filter film, depending on the use.

Specifically, the zoom projection lens 100 satisfies the conditional expression:

(1) 1.0<|F1/Fw|<1.2;

(2) 2.5<|F3/Fw|<2.7;

(3) 2.81<|F5/Fw|<2.83;

(4) 0.21<|F2/F4|<0.24.

Wherein F1, F2, F3, F4 and F5 are the effective focal lengths of the first lens group 10, the second lens group 20, the third lens group 30, the fourth lens group 40 and the fifth lens group 50, respectively, and Fw is a zoom projection. The effective focal length of the wide angle end of the lens 100.

The refractive power of the zoom projection lens 100 is appropriately distributed in the conditional expressions (1) to (4) (the relationship between the power of each lens group and the power of the zoom projection lens 100 is limited). On the one hand, it is ensured that the zoom projection lens 100 has a higher resolution in the zoom range (high resolution can be maintained during zooming); on the other hand, it is ensured that the reduced end of the zoom projection lens 100 satisfies the requirements of telecentric imaging.

Preferably, in order to control the chromatic aberration generated by the zoom projection lens 100, the zoom projection lens 100 also satisfies the conditional expression:

(5) 1.6 < (Nd4 + Nd5) / 2;

(6) 40<(Vd4-Vd5)<46,

Wherein Nd4 is the refractive index of the fourth lens pair d light (wavelength is 587.6 nm, the same below), Vd4 is the Abbe number of the fourth lens pair d light, and Nd5 is the fifth lens pair d The refractive index of light, Vd5, is the Abbe number of the fifth lens pair d light.

Specifically, the first lens group 10 includes, in order from the enlarged end to the reduced end, a first lens 11 having a negative refractive power and a second lens 12 having a negative refractive power to properly distribute the first lens group 10 The power of the light. The first lens 11 is an aspherical plastic lens. Since the first lens 11 is away from the heat source of the projector, and is in direct contact with the air, the temperature is lower than other lenses of the zoom projection lens 100, and the heat deformation is small, so that a plastic lens is considered.

The second lens group 20 includes, in order from the amplification end to the reduction end, a third lens 21 having a positive power, a fourth lens 22 having a positive power, and a fifth lens 23 having a negative power for a reasonable distribution. The power of the two lens group 20. The fourth lens 22 and the fifth lens 23 are glued into a cemented lens.

The third lens group 30 includes a sixth lens having positive power.

The fourth lens group 40 includes, in order from the amplification end to the reduction end, a seventh lens 41 having a negative refractive power, an eighth lens 42 having a negative refractive power, a ninth lens 43 having a positive refractive power, and having a positive optical focus. The tenth lens 44 of the degree is used to reasonably distribute the power of the fourth lens group 40.

The fifth lens group 50 includes an eleventh lens having positive power.

More specifically, the zoom projection lens 100 further includes a fixed aperture aperture 91 disposed between the fifth lens 23 and the third lens group 30 (ie, between the second lens group 20 and the third lens group 30). (Aperture stop), to limit the off-axis light from the third lens group 30 into the fifth lens 23 to produce more severe distortion and curvature of field. In addition, the aperture 91 makes the light passing through the third lens group 30 more symmetrical, which is advantageous for correcting the coma.

In order to reduce the influence of the temperature change on the back focus, other lenses than the first lens 11 are made of a glass material.

In order to have a loose tolerance, the lenses other than the first lens 11 are spherical glass lenses.

Taking the center of the lens surface as the origin and the optical axis as the x-axis, the aspherical surface of the lens surface is:

Where c is the curvature of the center of the mirror surface, For the height from the optical axis to the lens surface, the k-type quadric coefficient, Is the aspherical surface coefficient of the i-th order.

The optical elements of the zoom projection lens 100 satisfy the conditions of Table 1, Table 2, and Table 3.

The zoom projection lens 100 will be further described in detail with reference to FIGS. 3 through 10 in conjunction with FIGS. The meanings of the parameters in Tables 1 to 3 are as follows:

F: an effective focal length of the zoom projection lens 100;

D4: a surface distance between the first lens group 10 and the second lens group 20, that is, a distance between the image side surface of the second lens 12 and the object side surface of the third lens 21;

D10: a surface distance between the second lens group 20 and the third lens group 30, that is, a distance between the image side surface of the fifth lens 23 and the object side surface of the third lens group 30;

D12: a surface distance between the third lens group 30 and the fourth lens group 40, that is, a distance between the image side surface of the third lens group 30 and the object side surface of the seventh lens 41;

D19: a surface distance between the fourth lens group 40 and the fifth lens group 50, that is, a distance between the image side surface of the tenth lens 44 and the object side surface of the fifth lens group 50;

F _No : F number number;

Nd: the refractive index of the corresponding lens to d light;

Vd: corresponds to the Abbe number of the lens to d light.

The zoom projection lens 100 in the present embodiment satisfies the conditions listed in Table 1, Table 2, and Table 3.

Table 1

The spherical aberration characteristic curve, the field curvature characteristic curve, the distortion characteristic curve, and the lateral chromatic aberration characteristic curve of the zoom projection lens 100 of the present embodiment are respectively shown in FIGS. 3 to 10 (FIG. 3-6 corresponds to the wide-angle magnification zoom projection lens 100, Figure 7-10 corresponds to the zoom projection lens 100). In Figures 3 and 7, the curves F, d, and C are the spherical aberration of the F-projection lens 100 (F: 486.1 nm, the same below), d-light, and C-light (wavelength is 656.3 nm, the same below). Characteristic curve (the same below). It can be seen that the spherical aberration generated by the zoom projection lens 100 of the embodiment on visible light (400-700 nm) is controlled to be between -0.1 mm and 0.1 mm. In Figs. 4 and 8, the curves T and S are the Tangential field curvature characteristic curve and the Sagittal field curvature characteristic curve (the same applies hereinafter). It can be seen that the meridional curvature value and the sagittal curvature value are controlled between -0.2 mm and 0.2 mm. In Figs. 5 and 9, the curve is a distortion characteristic curve (the same applies hereinafter). It can be seen that the distortion variable is controlled between -1.5% and 1.5%. In FIGS. 6 and 10, the two curves are the lateral chromatic aberration characteristic curves of the F-light and the C-light passing through the zoom projection lens 100 (the same applies hereinafter), and the lateral chromatic aberration characteristic curve of the d-light passing through the zoom projection lens 100 coincides with the vertical axis ( The same below). It can be seen that the lateral chromatic aberration generated by the zoom projection lens 100 of the embodiment on visible light is controlled to be between -10 micrometers (micron, um) and 10 micrometers. In advance, under the premise of ensuring sufficient back focus and reduced end telecentric imaging, the zoom projection lens 100 is within the zoom range, and the spherical aberration, curvature of field, distortion and lateral chromatic aberration generated are controlled (corrected) in a small range. Inside.

The power of the zoom projection lens is reasonably distributed in the above conditional expression to ensure that the zoom projection lens maintains a high resolution requirement during zooming.

In addition, those skilled in the art can make other changes in the spirit of the invention, and all changes that are made according to the spirit of the invention should be included in the scope of the invention.

100‧‧‧ zoom projection lens

10‧‧‧First lens group

11‧‧‧First lens

12‧‧‧second lens

20‧‧‧second lens group

21‧‧‧ third lens

22‧‧‧Fourth lens

23‧‧‧ fifth lens

30‧‧‧third lens group

40‧‧‧Fourth lens group

41‧‧‧ seventh lens

42‧‧‧ eighth lens

43‧‧‧ ninth lens

44‧‧‧11th lens

50‧‧‧ fifth lens group

91‧‧‧Light

92‧‧ ‧ Prism

93‧‧‧ first flat glass

94‧‧‧Second flat glass

95‧‧‧ Third flat glass

96‧‧‧Four flat glass

97‧‧‧ Fifth flat glass

98‧‧‧protective glass

99‧‧‧ imaging surface

1 is a schematic view showing the system configuration of a zoom projection lens of the present invention when a wide-angle magnification is used;

2 is a schematic diagram of a system configuration when the zoom projection lens of the present invention adopts a telephoto magnification;

3 is a graph showing a spherical aberration characteristic of the zoom projection lens of FIG. 1 when a wide-angle magnification is used;

4 is a graph showing a field curvature characteristic when the zoom projection lens of FIG. 1 adopts a wide angle magnification;

FIG. 5 is a distortion diagram of the zoom projection lens of FIG. 1 when a wide-angle magnification is used; FIG.

6 is a graph showing a lateral chromatic aberration characteristic when the zoom projection lens of FIG. 1 adopts a wide-angle magnification;

7 is a graph showing spherical aberration characteristics when the zoom projection lens of FIG. 2 adopts a telephoto magnification;

8 is a graph showing a field curvature characteristic when the zoom projection lens of FIG. 2 adopts a telephoto magnification;

FIG. 9 is a graph showing a distortion characteristic when the zoom projection lens of FIG. 2 adopts a telephoto magnification; FIG.

FIG. 10 is a graph showing lateral chromatic aberration characteristics when the zoom projection lens of FIG. 2 adopts a telephoto magnification.

100‧‧‧ zoom projection lens

10‧‧‧First lens group

11‧‧‧First lens

12‧‧‧second lens

20‧‧‧second lens group

21‧‧‧ third lens

22‧‧‧Fourth lens

23‧‧‧ fifth lens

30‧‧‧third lens group

40‧‧‧Fourth lens group

41‧‧‧ seventh lens

42‧‧‧ eighth lens

43‧‧‧ ninth lens

44‧‧‧11th lens

50‧‧‧ fifth lens group

91‧‧‧Light

92‧‧ ‧ Prism

93‧‧‧ first flat glass

94‧‧‧Second flat glass

95‧‧‧ Third flat glass

96‧‧‧Four flat glass

97‧‧‧ Fifth flat glass

98‧‧‧protective glass

99‧‧‧ imaging surface

Claims (9)

A zoom projection lens includes, in order from the amplification end to the reduction end, a first lens group having a negative power, a second lens group having a positive power, a third lens group having a positive power, and a a fourth lens group having negative power and a fifth lens group having positive power, the fifth lens group being fixedly disposed, the first lens group, the second lens group, and the third lens The group and the fourth lens group movement setting are improved in that the zoom projection lens satisfies the following conditional expression: 1.0<|F1/Fw|<1.3; 2.5<|F3/Fw|<2.7; 2.81<|F5/ Fw|<2.83; 0.21<|F2/F4|<0.24; wherein F1, F2, F3, F4, and F5 are the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth, respectively The effective focal length of the lens group, Fw is the effective focal length of the zoom projection lens at the wide-angle end. The zoom projection lens of claim 1, wherein the first lens group includes a first lens and a second lens of a glue synthetic cement lens in order from an enlarged end to a reduced end, the first lens and the first lens The second lens has a negative refractive power, and the second lens group includes a third lens and a fourth lens and a fifth lens of the glue synthetic cement lens in order from the amplification end to the reduction end, the third lens having positive power, The fourth lens has a positive power and the fifth lens has a negative power. The zoom projection lens of claim 1, wherein the third lens group includes a sixth lens, the sixth lens has a positive power, and the fourth lens group is sequentially from an enlarged end to a reduced end The eighth lens and the ninth lens, and the tenth lens, wherein the seventh lens and the eighth lens each have a negative power, the ninth lens and the tenth lens Each has a positive power, and the fifth lens group includes an eleventh lens, and the eleventh lens has positive power. The zoom projection lens of claim 2, wherein the zoom projection lens further satisfies the following conditional expression:
1.6<(Nd4+Nd5)/2;
40<(Vd4-Vd5)<46,
Wherein, Nd4 is a refractive index of the fourth lens for a wavelength of 587 nm, Vd4 is an Abbe number of the fourth lens for a wavelength of 587 nm, and Nd5 is a refractive index of the fifth lens for a wavelength of 587 nm. Vd5 is the Abbe number of the fifth lens with a wavelength of 587 nm. The zoom projection lens of claim 1, wherein the zoom projection lens has a wide angle end angle of view of 29 degrees or more. The zoom projection lens of claim 2, wherein the first lens is an aspherical plastic lens, and the remaining lenses are spherical glass lenses. The zoom projection lens of claim 2, wherein the zoom projection lens further comprises an aperture between the second lens group and the third lens group. The zoom projection lens of claim 7, wherein the aperture is disposed on the fifth lens near the reduced end surface, and the aperture size of the aperture remains unchanged during zooming. The zoom projection lens of claim 1, wherein the first lens group is a focus lens group.