TWI762147B - Projection lens assembly - Google Patents

Abstract

A projection lens assembly includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. The first lens is with refractive power. The second lens is with refractive power. The third lens is with refractive power. The fourth lens is with refractive power. The fifth lens is with negative refractive power and includes a concave surface facing an image source side. The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in order from a projection side to the image source side along an optical axis. The second lens and the third lens are cemented together. A combination of the second lens and the third lens is with positive refractive power.

Description

Projection Lens(13)

The present invention relates to a projection lens.

The development trend of today's projection lens, in addition to the continuous development towards miniaturization and large field of view, in order to improve the brightness of the projector, the projection lens needs to have a larger aperture, and the conventional projection lens can no longer meet the current needs. The projection lens of the new architecture can meet the needs of miniaturization, large field of view and large aperture at the same time.

In view of this, the main purpose of the present invention is to provide a projection lens, which is small in size, large in field of view, and small in aperture value, but still has good optical performance.

The invention provides a projection lens including a first lens, a second lens, a third lens, a fourth lens and a fifth lens. The first lens has refractive power. The second lens has refractive power. The third lens has refractive power. The fourth lens has refractive power. The fifth lens has negative refractive power and includes a concave surface facing an image source side. The first lens, the second lens, the third lens, the fourth lens and the fifth lens are sequentially arranged along an optical axis from a projection side to an image source side. The second lens and the third lens are cemented together, and the combination of the second lens and the third lens has positive refractive power.

The projection lens of the present invention may further comprise an aperture, disposed between the projection side and the first lens. The first lens has positive refractive power, and includes a convex surface facing the image source side, and the first lens has a positive refractive power. The second lens has negative refractive power and includes a concave surface facing the projection side and the other concave surface facing the image source side. The third lens has positive refractive power and includes a convex surface facing the projection side and another convex surface facing the image source side. The fourth lens has a positive refractive power The refractive power includes a convex surface facing the projection side and another convex surface facing the image source side, and the fifth lens may further include a concave surface facing the projection side.

The first lens may further include a concave surface or a convex surface facing the projection side, wherein the fourth lens and the fifth lens are cemented lenses.

f₁/f

3.7；-1.1

f₂/f

-0.6；0.8

f₃/f

1.2；0.8

f₄/f

1.1；其中，f₁為第一透鏡之一有效焦距，f₂為第二透鏡之一有效焦距，f₃為第三透鏡之一有效焦距，f₄為第四透鏡之一有效焦距，f為投影鏡頭之有效焦距。 The projection lens satisfies any of the following conditions: 1.9

f ₁ /f

3.7;-1.1

f ₂ /f

-0.6; 0.8

f ₃ /f

1.2; 0.8

f ₄ /f

1.1; wherein, f ₁ is an effective focal length of the first lens, f ₂ is an effective focal length of the second lens, f ₃ is an effective focal length of the third lens, f ₄ is an effective focal length of the fourth lens, and f is The effective focal length of the projection lens.

f₂₃/f₅

30；-1.15

f₄/f₅

-0.75；-33

f₂₃/f

16；其中，f₄為第四透鏡之一有效焦距，f₅為第五透鏡之有效焦距，f₂₃為第二透鏡及第三透鏡之一組合有效焦距，f為投影鏡頭之有效焦距。 Where the projection lens satisfies any of the following conditions: -17

f ₂₃ /f ₅

30;-1.15

_f4 / _f5

-0.75; -33

f ₂₃ /f

16; wherein, _f4 is an effective focal length of the fourth lens, f5 is the effective focal length of the _fifth lens, _f23 is a combined effective focal length of the second lens and the third lens, and f is the effective focal length of the projection lens.

f/TTL

0.45；0.09

BFL/TTL

0.22；0.5

IH/f

0.65；其中，f為投影鏡頭之有效焦距，TTL為光圈至一影像源於光軸上之一間距，BFL為第五透鏡之一影像源側面至影像源於光軸上之一間距，IH為投影鏡頭之一半像高。 Where the projection lens satisfies any of the following conditions: 0.3

f/TTL

0.45; 0.09

BFL/TTL

0.22; 0.5

IH/f

0.65; where f is the effective focal length of the projection lens, TTL is the distance from the aperture to an image originating on the optical axis, BFL is the distance from the side of the image source of the fifth lens to the image originating on the optical axis, and IH is One half of the projection lens is high.

f₅/f

-0.9；其中，f₅為第五透鏡之一有效焦距，f為投影鏡頭之一有效焦距。 The projection lens satisfies the following conditions: -1.2

f ₅ /f

-0.9; wherein, f5 is the effective focal length of one of the _fifth lenses, and f is the effective focal length of one of the projection lenses.

In order to make the above objects, features, and advantages of the present invention more clearly understood, preferred embodiments are hereinafter described in detail with the accompanying drawings.

1, 2, 3, 4, 5: Projection lens

ST1, ST2, ST3, ST4, ST5: Aperture

L11, L21, L31, L41, L51: First lens

L12, L22, L32, L42, L52: Second lens

L13, L23, L33, L43, L53: Third lens

L14, L24, L34, L44, L54: Fourth lens

L15, L25, L35, L45, L55: Fifth lens

IS1, IS2, IS3, IS4, IS5: Image source

OA1, OA2, OA3, OA4, OA5: Optical axis

S11, S21, S31, S41, S51: Aperture surface

S12, S22, S32, S42, S52: the projection side of the first lens

S13, S23, S33, S43, S53: the side of the image source of the first lens

S14, S24, S34, S44, S54: The second lens projection side

S15, S25, S35, S45, S55: side of the image source of the second lens

S15, S25, S35, S45, S55: the projection side of the third lens

S16, S26, S36, S46, S56: the side of the image source of the third lens

S17, S27, S37, S47, S57: the projection side of the fourth lens

S18, S28, S38, S48, S58: the side of the image source of the fourth lens

S19, S29, S39, S49, S59: the projection side of the fifth lens

S110, S210, S310, S410, S510: the side of the image source of the fifth lens

FIG. 1 is a schematic diagram of the lens configuration and optical path of the first embodiment of the projection lens according to the present invention.

FIG. 2A is a field curvature diagram of the first embodiment of the projection lens according to the present invention.

FIG. 2B is a distortion diagram of the first embodiment of the projection lens according to the present invention.

FIG. 2C is a Modulation Transfer Function diagram of the first embodiment of the projection lens according to the present invention.

FIG. 3 is a schematic diagram of the lens configuration and optical path of the second embodiment of the projection lens according to the present invention.

FIG. 4A is a field curvature diagram of a second embodiment of the projection lens according to the present invention.

FIG. 4B is a distortion diagram of the second embodiment of the projection lens according to the present invention.

FIG. 4C is a diagram of the modulation transfer function of the second embodiment of the projection lens according to the present invention.

FIG. 5 is a schematic diagram of the lens configuration and optical path of the third embodiment of the projection lens according to the present invention.

FIG. 6A is a field curvature diagram of a third embodiment of the projection lens according to the present invention.

FIG. 6B is a distortion diagram of the third embodiment of the projection lens according to the present invention.

FIG. 6C is a diagram of the modulation transfer function of the third embodiment of the projection lens according to the present invention.

FIG. 7 is a schematic diagram of the lens configuration and optical path of the fourth embodiment of the projection lens according to the present invention.

FIG. 8A is a field curvature diagram of a fourth embodiment of the projection lens according to the present invention.

FIG. 8B is a distortion diagram of the fourth embodiment of the projection lens according to the present invention.

FIG. 8C is a diagram of the modulation transfer function of the fourth embodiment of the projection lens according to the present invention.

FIG. 9 is a schematic diagram of the lens configuration and optical path of the fifth embodiment of the projection lens according to the present invention.

FIG. 10A is a field curvature diagram of a fifth embodiment of the projection lens according to the present invention.

FIG. 10B is a distortion diagram of the fifth embodiment of the projection lens according to the present invention.

FIG. 10C is a diagram of the modulation transfer function of the fifth embodiment of the projection lens according to the present invention.

The present invention provides a projection lens, comprising: a first lens with refractive power; a second lens with refractive power; a third lens with refractive power; a fourth lens with refractive power; and a fifth lens with negative refractive power, the fifth lens It includes a concave surface facing an image source side; wherein the first lens, the second lens, the third lens, the fourth lens and the fifth lens are sequentially arranged along an optical axis from a projection side to the image source side; wherein the second lens There is no air space between the lens and the third lens, and the combination of the second lens and the third lens has positive refractive power.

Please refer to Table 1, Table 2, Table 4, Table 5, Table 7, Table 8, Table 10, Table 11, Table 13 and Table 14 below, among which Table 1, Table 4, Table 7, Table 10 and Table 14 Thirteen are the relevant parameter tables of each lens according to the first embodiment to the fifth embodiment of the projection lens according to the present invention, and Table 2, Table 5, Table 8, Table 11 and Table 14 are respectively Table 1 and Table 1 4. The relevant parameters of the aspheric surface of the aspheric lens in Table 7, Table 10 and Table 13.

Figures 1, 3, 5, 7, and 9 are schematic diagrams of lens configurations and optical paths of the first, second, third, fourth, and fifth embodiments of the projection lens of the present invention, respectively, wherein the first lenses L11, L21, L31, L41, L51 has positive refractive power, and has the effect of beaming at a large angle, and its image source side S13, S23, S33, S43, and S53 are convex surfaces, and the projection side surfaces S12, S22, S32, S42, S52 and the image source side surfaces S13, S23, S33, S43, and S53 are all aspheric surfaces.

The second lenses L12, L22, L32, L42 and L52 have negative refractive power and are made of glass material. Concave, the projection side S14, S24, S34, S44, S54 and the image source side S15, S25, S35, S45, S55 are all spherical surfaces.

The third lenses L13, L23, L33, L43, and L53 have positive refractive power, and have the effect of compensating for spherical aberration and chromatic aberration of the lens group. Convex, the image source sides S16, S26, S36, S46, S56 are convex, the projection sides S15, S25, S35, S45, S55 are spherical surfaces, and the image source sides S16, S26, S36, S46, S56 are aspheric surfaces.

The fourth lenses L14, L24, L34, L44, and L54 have positive refractive power and are made of glass. The projection sides S17, S27, S37, S47, and S57 are convex, and the image source sides S18, S28, S38, S48, and S58 are Convex, projection sides S17, S27, S37, S47, S57 and image source sides S18, S28, S38, S48, S58 are all aspherical surfaces.

The fifth lens L15, L25, L35, L45, and L55 have negative refractive power, the projection sides S19, S29, S39, S49, and S59 are concave, the image source sides S110, S210, S310, S410, and S510 are concave, and the projection sides S19, S29, S39, S49, S59 and the side surfaces of the image source S110, S210, S310, S410, and S510 are all aspherical surfaces.

The second lens L12, L22, L32, L42, L52 and the third lens L13, L23, L33, L43, L53 are bonded to each other, that is, there is no air space between them, and the combination of the two has positive refractive power, and It has the characteristics of relaying the front and rear mirror groups, so that the overall mirror group can reduce the size and The effect of increasing the field of view angle.

In addition, the projection lenses 1, 2, 3, 4, and 5 meet at least one of the following conditions:

Among them, f is an effective focal length of the projection lenses 1, 2, 3, 4, 5 in the first to fifth embodiments, and f ₁ is the first to fifth embodiments, the first lens L11, One of the effective focal lengths of L21, L31, L41, and L51, and f ₂ is one of the effective focal lengths of the second lenses L12, L22, L32, L42, and L52 in the first embodiment to the fifth embodiment, and f ₃ is the first embodiment. In the fifth embodiment, one of the effective focal lengths of the third lenses L13, L23, L33, L43, L53, _f4 is the fourth lens L14, L24, L34, L44, L54 in the first to fifth embodiments an effective focal length, f ₅ is an effective focal length of the fifth lens L15, L25, L35, L45, L55 in the first embodiment to the fourth embodiment, f ₂₃ is the first embodiment to the fifth embodiment, The second lens L12, L22, L32, L42, L52 and one of the third lenses L13, L23, L33, L43, L53 have a combined effective focal length, TTL is the first to fifth embodiments, the apertures ST1, ST2, ST3 , ST4, ST5 respectively to the image source IS1, IS2, IS3, IS4, IS5 on the optical axis OA1, OA2, OA3, OA4, OA5 on the distance, BFL is the first embodiment to the fifth embodiment, the fifth lens Image source side S111, S211, S311, S411, S511 of L15, L25, L35, L45, L55 to one of the image sources IS1, IS2, IS3, IS4, IS5 on the optical axis OA1, OA2, OA3, OA4, OA5 respectively The distance, IH, is a half-image height of the projection lenses 1, 2, 3, 4, and 5 in the first to fifth embodiments. The projection lenses 1, 2, 3, 4, and 5 can effectively reduce the volume, effectively reduce the aperture value, effectively improve the field of view, effectively correct the aberration, and effectively correct the chromatic aberration.

f₅/f

-0.9時，可有效縮小主光線角度(Chief Ray Angle)及增大視場；當滿足條件(2)：1.9

f₁/f

3.7時，可有效修正成像品質；當滿足條件(3)：-1.1

f₂/f

-0.6時，可有效增大視場；當滿足條件(4)：0.8

f₃/f

1.2時，可有效修正色差及場曲；當滿足條件(5)：0.8

f₄/f

1.1時，可有效修正成像品質；當滿足條件(6)：0.3

f/TTL

0.45時，可有效縮短鏡頭總長度；當滿足條件(7)：0.09

BFL/TTL

0.22，可有效控制後焦距長度；當滿足條件(8)：0.5

IH/f

0.65，可有效控制成像大小；當滿足條件(10)：-1.15

f₄/f₅

-0.75，可有效修正色差及場曲。 When condition (1) is satisfied: -1.2

f ₅ /f

When -0.9, it can effectively reduce the chief ray angle (Chief Ray Angle) and increase the field of view; when the condition (2) is satisfied: 1.9

f ₁ /f

3.7, the imaging quality can be effectively corrected; when the condition (3) is satisfied: -1.1

f ₂ /f

When -0.6, the field of view can be effectively increased; when condition (4) is satisfied: 0.8

f ₃ /f

1.2, chromatic aberration and field curvature can be effectively corrected; when condition (5) is satisfied: 0.8

f ₄ /f

1.1, the image quality can be effectively corrected; when condition (6) is satisfied: 0.3

f/TTL

When 0.45, the total length of the lens can be effectively shortened; when the condition (7) is satisfied: 0.09

BFL/TTL

0.22, can effectively control the back focal length; when condition (8) is satisfied: 0.5

IH/f

0.65, which can effectively control the imaging size; when the condition (10) is satisfied: -1.15

_f4 / _f5

-0.75, can effectively correct chromatic aberration and field curvature.

The first embodiment of the projection lens of the present invention will now be described in detail. Please refer to FIG. 1, the projection lens 1 includes an aperture ST1, a first lens L11, a second lens L12, a third lens L13, a A fourth lens L14 and a fifth lens L15. During projection, the light from an image source IS1 is finally projected on a projection side. According to paragraphs 1 to 8 of [Embodiment], wherein: the first lens L11 is a meniscus lens, made of glass material, and its projection side S12 is concave; the fifth lens L15 is made of glass material; Using the above-mentioned lens, aperture ST1 and the design that satisfies at least one of the conditions (1) to (11), the projection lens 1 can effectively reduce the volume, effectively reduce the aperture value, effectively improve the field of view, and effectively correct the image. Poor, effective correction of chromatic aberration. Table 1 is a table of relevant parameters of each lens of the projection lens 1 in Fig. 1 .

The aspheric surface concavity z of the aspheric lens in Table 1 is obtained by the following formula:

z=ch ² /{1+[1-(k+1)c ² h ² ] ^1/2 }+Ah ⁴ +Bh ⁶ +Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴

in:

c: curvature;

h: the vertical distance from any point on the lens surface to the optical axis;

k: Conic Constant;

A~F: Aspheric coefficients.

Table 2 is a table of relevant parameters of the aspheric surfaces of the aspheric lenses in Table 1.

Table 3 shows the relevant parameter values of the projection lens 1 of the first embodiment and the calculated values of the corresponding conditions (1) to (11). It can be seen from Table 3 that the projection lens 1 of the first embodiment can meet the conditions (1). ) to the requirements of condition (11).

In addition, the optical performance of the projection lens 1 of the first embodiment can also meet the requirements. It can be seen from FIG. 2A that the field curvature of the projection lens 1 of the first embodiment is between -20 μm and 20 μm. It can be seen from FIG. 2B that the distortion of the projection lens 1 of the first embodiment is between -10% and 0%. It can be seen from FIG. 2C that the modulation transfer function value of the projection lens 1 of the first embodiment is between 0.18 and 1.0. It is obvious that the field curvature and distortion of the projection lens 1 of the first embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIG. 3, the projection lens 2 includes an aperture ST2, a first lens L21, a second lens L22, a first Three lenses L23, a fourth lens L24 and a fifth lens L25. During projection, the light from an image source IS2 is finally projected on a projection side. According to paragraphs 1 to 8 of [Embodiment], wherein: the first lens L21 is a meniscus lens, made of glass material, and its projection side S22 is concave; the fifth lens L25 is made of plastic material; Aperture ST2 and the design that satisfies at least one of the conditions (1) to (11), so that the projection lens 2 can effectively reduce the volume, effectively reduce the aperture value, effectively improve the field of view, effectively correct aberrations, and effectively Correct chromatic aberration. Table 4 is a table of relevant parameters of each lens of projection lens 2 in Figure 3.

The definition of the aspherical surface concavity z of the aspherical lens in Table 4 is the same as the definition of the aspherical surface concavity z of the aspherical lens in Table 1 in the first embodiment, and will not be repeated here. Table 5 is a table of relevant parameters of the aspherical surface of the aspherical lens in Table 4, where k is the conic coefficient and A~F is the aspherical coefficient.

Table 6 shows the relevant parameter values of the projection lens 2 of the second embodiment and the calculated values of the corresponding conditions (1) to (11). It can be seen from Table 6 that the projection lens 2 of the second embodiment can meet the conditions (1). ) to the requirements of condition (11).

In addition, the optical performance of the projection lens 2 of the second embodiment can also meet the requirements. It can be seen from FIG. 4A that the field curvature of the projection lens 2 of the second embodiment is between -18 μm and 12 μm. It can be seen from FIG. 4B that the distortion of the projection lens 2 of the second embodiment is between -8% and 0%. It can be seen from FIG. 4C that the modulation transfer function value of the projection lens 2 of the second embodiment is between 0.19 and 1.0. It is obvious that the field curvature and distortion of the projection lens 2 of the second embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIG. 5, the projection lens 3 includes an aperture ST3, a first lens L31, a second lens L32, a third lens L33, a A fourth lens L34 and a fifth lens L35. During projection, light from an image source IS3 is finally projected on a projection side. According to the first to eighth paragraphs of [Embodiment], wherein: the first A lens L31 is made of glass material, and its projection side S32 is a convex surface; the fifth lens L35 is made of glass material; using the above-mentioned lens, aperture ST3 and a design that satisfies at least one of the conditions (1) to (11), the projection The lens 3 can effectively reduce the volume, effectively reduce the aperture value, effectively improve the field of view, effectively correct the aberration, and effectively correct the chromatic aberration. Table 7 is a table of relevant parameters of each lens of the projection lens 3 in Fig. 5 .

The definition of the aspherical surface concavity z of the aspherical lens in Table 7 is the same as the definition of the aspherical surface concavity z of the aspherical lens in Table 1 in the first embodiment, and will not be repeated here. Table 8 is a table of relevant parameters of the aspherical surface of the aspherical lens in Table 7, where k is the conic coefficient, and A~F are the aspherical coefficients.

Table 9 shows the relevant parameter values of the projection lens 3 of the third embodiment and the calculated values of the corresponding conditions (1) to (11). It can be seen from Table 9 that the projection lens 3 of the third embodiment can meet the conditions (1). ) to the requirements of condition (11).

In addition, the optical performance of the projection lens 3 of the third embodiment can also meet the requirements. It can be seen from FIG. 6A that the field curvature of the projection lens 3 of the third embodiment is between -0.035mm and 0.025mm. It can be seen from FIG. 6B that the distortion of the projection lens 3 of the third embodiment is between -10% and 0%. It can be seen from FIG. 6C that the modulation transfer function value of the projection lens 3 of the third embodiment is between 0.15 and 1.0. It is obvious that the field curvature and distortion of the projection lens 3 of the third embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIG. 7, the projection lens 4 includes an aperture ST4, a first lens L41, a second lens L42, a third lens L43, a A fourth lens L44 and a fifth lens L45. During projection, light from an image source IS4 is finally projected on a projection side. According to paragraphs 1 to 8 of [Embodiment], wherein: the first lens L41 is made of plastic material, and its projection side S42 is convex; the fifth lens L45 is made of glass material; using the above-mentioned lens, aperture ST4 and at least the conditions (1) to one of conditions (11) The design of the conditions enables the projection lens 4 to effectively reduce the volume, effectively reduce the aperture value, effectively improve the field of view, effectively correct the aberration, and effectively correct the chromatic aberration. Table 10 is a table of relevant parameters of each lens of the projection lens 4 in Fig. 7 .

The definition of the aspherical surface concavity z of the aspherical lens in Table 10 is the same as the definition of the aspherical surface concavity z of the aspherical lens in Table 1 in the first embodiment, and will not be repeated here. Table 11 is a table of relevant parameters of the aspherical surface of the aspherical lens in Table 10, where k is the conic coefficient and A~F is the aspherical coefficient.

Table 12 shows the relevant parameter values of the projection lens 4 of the fourth embodiment and the calculated values of the corresponding conditions (1) to (11). It can be seen from Table 12 that the projection lens 4 of the fourth embodiment can meet the conditions (1) to the requirements of condition (11).

In addition, the optical performance of the projection lens 4 of the fourth embodiment can also meet the requirements. It can be seen from FIG. 8A that the field curvature of the projection lens 4 of the fourth embodiment is between -0.04mm and 0.03mm. It can be seen from FIG. 8B that the distortion of the projection lens 4 of the fourth embodiment is between -10% and 0%. It can be seen from FIG. 8C that the modulation transfer function value of the projection lens 4 of the fourth embodiment is between 0.05 and 1.0. It is obvious that the field curvature and distortion of the projection lens 4 of the fourth embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIG. 9, the projection lens 5 includes an aperture ST5, a first lens L51, a second lens L52, a third lens L53, a A fourth lens L54 and a fifth lens L55. During projection, light from an image source IS5 is finally projected on a projection side. According to paragraphs 1 to 8 of [Embodiment], wherein: the first lens L51 is made of plastic material, and its projection surface S52 is a convex surface; the fifth lens L55 is made of plastic material; using the above-mentioned lens, aperture ST5 and at least the conditions The design of one of the conditions (1) to (11) enables the projection lens 5 to effectively reduce the volume, effectively reduce the aperture value, effectively improve the field of view, effectively correct aberrations, and effectively correct chromatic aberrations. Table 13 shows the projections in Figure 9 The relevant parameter table of each lens of lens 5.

The definition of the aspherical surface concavity z of the aspherical lens in Table 13 is the same as the definition of the aspherical surface concavity z of the aspherical lens in Table 1 in the first embodiment, and will not be repeated here. Table 14 is a table of relevant parameters of the aspherical surface of the aspherical lens in Table 13, where k is the conic coefficient, and A~F are the aspherical coefficients.

Table 15 shows the relevant parameter values of the projection lens 5 of the fifth embodiment and the calculated values of the corresponding conditions (1) to (11). It can be seen from Table 15 that the projection lens 5 of the fifth embodiment can meet the conditions (1) to the requirements of condition (11).

In addition, the optical performance of the projection lens 5 of the fifth embodiment can also meet the requirements. It can be seen from FIG. 10A that the field curvature of the projection lens 5 of the fifth embodiment is between -20 μm and 16 μm. It can be seen from FIG. 10C that the modulation transfer function value of the projection lens 5 of the fifth embodiment is between 0.32 and 1.0. It is obvious that the field curvature and distortion of the projection lens 5 of the fifth embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better optical performance.

In the above-mentioned embodiment, the fourth lens and the fifth lens are separated from each other and not cemented or cemented, and there is an air gap between them. However, it can be understood that the fourth lens and the fifth lens can also be cemented into a cemented lens. It belongs to the scope of the present invention.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone familiar with the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be determined by the scope of the appended patent application.

1: Projection lens

ST1: Aperture

L11: The first lens

L12: Second lens

L13: Third lens

L14: Fourth lens

L15: Fifth lens

IS1: Image source

OA1: Optical axis

S11: Aperture Surface

S12: Projection side of the first lens

S13: The side of the image source of the first lens

S14: The second lens projection side

S15: Side of the second lens image source

S15: The third lens projection side

S16: The side of the image source of the third lens

S17: Projection side of the fourth lens

S18: The fourth lens image source side

S19: The projection side of the fifth lens

S110: The side of the image source of the fifth lens

Claims (10)

A projection lens, comprising: a first lens with refractive power; a second lens with refractive power; a third lens with refractive power; a fourth lens with refractive power; and a fifth lens with negative refractive power, the fifth lens comprising a concave surface facing an image source side; wherein the first lens, the second lens, the third lens, the fourth lens and the fifth lens are sequentially arranged along an optical axis from a projection side to the image source side; wherein The second lens and the third lens are cemented lenses, and the combination of the second lens and the third lens has positive refractive power. The projection lens of claim 1, further comprising a diaphragm disposed between the projection side and the first lens, wherein: the first lens has positive refractive power and includes a convex surface facing the image source side The second lens has negative refractive power, and includes a concave surface facing the projection side and another concave surface facing the image source side; the third lens is a biconvex lens with positive refractive power, and includes a convex surface facing the projection side and another convex surface facing the image source side; and the fourth lens is a biconvex lens with positive refractive power, and includes a convex surface facing the projection side and another convex surface facing the image source side; and the fifth lens further includes a concave surface facing the projection side. The projection lens as described in item 2 of the scope of the patent application, wherein: The first lens further includes a concave surface facing the projection side; wherein, the fourth lens and the fifth lens are cemented lenses. The projection lens of claim 2, wherein: the first lens further comprises a convex surface facing the projection side; wherein the fourth lens and the fifth lens are cemented lenses. The projection lens according to any one of claims 1 to 4 of the scope of application, wherein the projection lens satisfies the following conditions: 0.5

IH/f

0.65; wherein, f is the effective focal length of the projection lens, and IH is the half image height of the projection lens. The projection lens according to any one of claims 1 to 4 of the scope of the application, wherein the projection lens satisfies the following conditions: 1.9

f ₁ /f

3.7; wherein, f ₁ is an effective focal length of the first lens, and f is the effective focal length of the projection lens. The projection lens according to any one of claims 1 to 4 of the scope of the application, wherein the projection lens satisfies the following conditions: 0.8

f ₃ /f

1.2; -1.2

f ₅ /f

-0.9; wherein, _f3 is an effective focal length of the third lens, f5 is an effective focal length of the _fifth lens, and f is the effective focal length of the projection lens. The projection lens according to any one of claims 1 to 4 of the scope of the application, wherein the projection lens satisfies the following conditions: 0.8

f ₄ /f

1.1; wherein, _f4 is an effective focal length of the fourth lens, and f is the effective focal length of the projection lens. The projection lens according to any one of claims 1 to 4 of the scope of the patent application, wherein the projection lens satisfies any one of the following conditions: -1.1

f ₂ /f

-0.6; -1.15

_f4 / _f5

-0.75; 0.3

f/TTL

0.45; 0.09

BFL/TTL

0.22; wherein, f is the effective focal length of the projection lens, TTL is the distance from the aperture to an image originating from the optical axis, and BFL is the side of an image source of the fifth lens to the image originating from the optical axis The above distance, f2 is an effective focal length of the _second lens, _f4 is an effective focal length of the fourth lens, and f5 is an effective focal length of the _fifth lens. The projection lens according to any one of claims 1 to 4 of the scope of the patent application, wherein the projection lens satisfies any one of the following conditions: -17

f ₂₃ /f ₅

30;-33

f ₂₃ /f

16; wherein, f5 is the effective focal length of the _fifth lens, _f23 is the combined effective focal length of the second lens and the third lens, and f is the effective focal length of the projection lens.

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