CN116540390A - Projection optics and electronics - Google Patents

Abstract

The present application relates to a projection optical system and an electronic apparatus. The projection optical system sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens group with positive focal power and a fourth lens with positive focal power from an light emitting side to a light entering side. The light emergent surface of the first lens is a convex surface, the light incident surface of the first lens is a concave surface, the light emergent surface and the light incident surface of the second lens are concave surfaces, the third lens group comprises at least three lenses with optical power, the light emergent surface and the light incident surface of the fourth lens are convex surfaces, and the second lens and the third lens group are configured to move between the first lens and the fourth lens along the optical axis direction. According to the projection optical system, the distance between the second lens and the first lens on the optical axis is changed, so that the focal length of the projection optical system is adjusted, the distance between the third lens group and the second lens is adjusted, the zooming of the second lens is compensated, and the imaging quality is improved.

Description

Projection optics and electronics

technical field

The present application relates to the technical field of optical equipment, in particular to projection optical systems and electronic equipment.

Background technique

Projection equipment equipped with projection optical systems such as projectors, projection lamps, and advertising lamps are widely used in various scenes. The projection equipment collimates the light source onto patterns such as film, and then projects the pattern onto the target through the projection optical system. into a clear pattern.

When the projection optical system in the related art uses the zoom function, the imaging quality is poor.

Contents of the invention

Based on this, it is necessary to provide a projection optical system and an electronic device to solve the problem of poor imaging quality when the projection optical system in the related art uses the zoom function.

A projection optical system, the projection optical system sequentially includes from the light exit side to the light entry side:

A first lens with positive refractive power, the light exit surface of the first lens is convex, and the light entrance surface is concave;

A second lens with negative refractive power, the light exit surface and the light entrance surface of the second lens are both concave;

a third lens group having positive power, said third lens group comprising at least three lenses having power; and,

A fourth lens with positive refractive power, the light exit surface and the light entrance surface of the fourth lens are convex;

Both the second lens and the third lens group are configured to be movable between the first lens and the fourth lens in an optical axis direction.

The present application provides a projection optical system. The projection optical system has a first lens with positive refractive power and a second lens with negative refractive power, and enables the second lens to move relative to the first lens along the optical axis direction to change the first lens. The distance between the second lens and the first lens on the optical axis is used to adjust the focal length of the projection optical system. The projection optical system provided by the present application is also provided with a third lens group and a fourth lens. The first lens, the second lens, the third lens group and the fourth lens are arranged in sequence along the optical axis from the light exit side to the light entrance side. Pass through the fourth lens, the third lens group, the second lens and the first lens in sequence. And the third lens group can move relative to the first lens along the optical axis direction, so as to adjust the separation distance between the second lens and the third lens group on the optical axis, and then adjust the change of the focal position of the light beam caused by the movement of the second lens, That is, the zoom of the second lens is compensated to improve the imaging quality and imaging definition. Combined with the fourth lens, the light beam is still focused on the focus position before the second lens moves, thereby realizing zoom projection. It can be understood that the present application enables the projection optical system of the present application to change the focal length and form a clear image through the setting of the second lens and the third lens group, that is, adjust to change the size of the projected image and keep the projected image clear.

In one of the embodiments, the projection optical system includes a lens barrel element, and the second lens and the third lens group are coupled with the first lens and the fourth lens through the lens barrel element;

The lens barrel element is configured so that the amount of movement of one of the second lens and the third lens group along the direction of the optical axis has a linear relationship with the rotation angle of the lens barrel element, so that the The other one of the second lens and the third lens group has a non-linear relationship with the rotation angle of the lens barrel element.

In one of the embodiments, the third lens group includes a first positive lens, a first cemented lens, and a first negative lens sequentially arranged along the optical axis direction, and the first cemented lens includes a lens with a negative refractive power A first sub-lens and a second sub-lens with positive power.

In one of the embodiments, the light exit surface of the first positive lens is convex, and the light entrance surface is convex; and/or

The light exit surface of the first sub-lens is convex, and the light entrance surface is concave; and/or

The light exit surface of the second sub-lens is convex, and the light entrance surface is convex; and/or

The light emitting surface of the first negative lens is concave, and the light incident surface is concave.

In one of the embodiments, the total optical length of the projection optical system is TTL1, the distance between the first lens and the second lens is the first air gap d1, the second lens and the third lens The distance between the lens groups is the second air gap d2, and the distance between the third lens group and the fourth lens is the third air gap d3;

The first air interval d1, the second air interval d2 and the third air interval d3 satisfy the formula: 0.04≤d1/TTL1≤0.27; 0.03≤d2/TTL1≤0.38; 0.07≤d3/TTL1≤0.18 .

In one of the embodiments, the third lens group includes a second positive lens, a third positive lens and a second cemented lens sequentially arranged along the direction of the optical axis;

The second cemented lens includes a third sub-lens with negative power and a fourth sub-lens with positive power.

In one of the embodiments, the light exit surface of the second positive lens is convex, and the light entrance surface is convex; and/or

The light exit surface of the third positive lens is convex, and the light entrance surface is concave; and/or

The light exit surface of the third sub-lens is concave, and the light entrance surface is concave; and/or

The light emitting surface of the fourth sub-lens is convex, and the light incident surface is concave.

In one of the embodiments, the total optical length of the projection optical system is TTL2, the distance between the first lens and the second lens is the fourth air gap g4, and the second lens and the third lens The distance between the lens groups is the fifth air gap g5, and the distance between the third lens group and the fourth lens is the sixth air gap g6;

The fourth air interval g4, the fifth air interval g5 and the sixth air interval g6 satisfy the formula: 0.05≤g4/TTL2≤0.22; 0.04≤g5/TTL2≤0.34; 0.08≤g6/TTL2≤0.22 .

In one of the embodiments, the projection optical system further includes an aperture, and the aperture is arranged between the second lens and the third lens group.

According to another aspect of the present application, an electronic device is provided, including the above-mentioned projection optical system.

Description of drawings

FIG. 1 is a schematic structural diagram of a projection optical system of the present application;

FIG. 2 is a structural schematic diagram of the projection optical system shown in FIG. 1 at different focal lengths;

FIG. 3 is a schematic structural diagram of another projection optical system of the present application;

FIG. 4 is a schematic structural diagram of the projection optical system shown in FIG. 3 at different focal lengths.

Explanation of reference signs:

projection optical system 100;

The first lens 1; the second lens 2;

The third lens group 3; the first positive lens 31; the first sub-lens 32; the second sub-lens 33; the first negative lens 34; the second positive lens 35; the third positive lens 36; the third sub-lens 37; sub-lens 38;

Fourth lens 4; aperture 5; film 6; first air interval d1; second air interval d2; third air interval d3; fourth air interval g4; fifth air interval g5; sixth air interval g6.

Detailed ways

In order to make the above-mentioned purpose, features and advantages of the present application more obvious and understandable, the specific implementation manners of the present application will be described in detail below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the application. However, the present application can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without departing from the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial" , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, rather than indicating or implying the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and thus should not be construed as limiting the application.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In this application, terms such as "installation", "connection", "connection" and "fixation" should be interpreted in a broad sense, for example, it can be a fixed connection or a detachable connection, unless otherwise clearly specified and limited. , or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.

In the present application, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may mean that the first and second features are in direct contact, or that the first and second features are indirect through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions are for the purpose of illustration only and are not intended to represent the only embodiments.

Referring to FIG. 1 and FIG. 2 , FIG. 1 is a schematic structural diagram of a projection optical system 100 of the present application, and FIG. 2 is a schematic structural diagram of the projection optical system 100 shown in FIG. 1 at different focal lengths. The present application provides a projection optical system 100 . The projection optical system 100 includes a first lens 1 , a second lens 2 , a third lens group 3 and a fourth lens 4 sequentially from the light exit side to the light entrance side. The refractive power of the first lens 1 is positive, and the light emitting surface of the first lens 1 is convex, and the light incident surface is concave. The refractive power of the second lens 2 is negative, and both the light exit surface and the light entrance surface of the second lens 2 are concave. The refractive power of the third lens group 3 is positive, the third lens group 3 includes at least three lenses with refractive power, the refractive power of the fourth lens 4 is positive, the light exit surface and the light incident surface of the fourth lens 4 All are convex. And both the second lens 2 and the third lens group 3 are configured to be able to move between the first lens 1 and the fourth lens 4 along the optical axis direction.

It can be understood that, in the projection optical system 100 provided in the present application, the beam passes through the film 6 and the projection optical system 100 and is projected onto a target such as a screen to form a clear pattern. The projection optical system 100 moves relative to the first lens 1 through the second lens 2 along the optical axis direction, changes the effective focal length of the projection optical system 100, realizes the zoom function, or realizes the change of the projection angle of the beam, or realizes the formation of the beam projection. A change in the size of the spot or pattern. At the same time, the movement of the third lens group 3 along the optical axis is used to compensate, and combined with the fourth lens 4 to adjust the light beam to form a clear pattern, that is, the setting of the second lens 2 and the third lens group 3 can realize the zooming of the projected image. At the same time, ensure the clear effect of the projected image.

The projection optical system 100 includes a lens barrel element (not shown), the second lens 2 and the third lens group 3 are coupled with the first lens 1 and the fourth lens 4 through the lens barrel element, so that the second lens 2 and the third lens The group 3 is movable between the first lens 1 and the fourth lens 4 in the optical axis direction. And the lens barrel element is set so that the amount of movement of one of the second lens 2 and the third lens group 3 along the optical axis direction is in a linear relationship with the rotation angle of the lens barrel element, so that the second lens 2 and the third lens The other one of the groups 3 has a non-linear relationship with the rotation angle of the barrel element.

In some embodiments, the lens barrel element is set as a lens barrel with a CAM groove inside, the second lens 2 and the third lens group 3 are arranged in the lens barrel through the CAM groove, and then the second lens 2 is adjusted by rotating the lens barrel And the third lens group 3 moves along the optical axis direction.

In some embodiments, the relationship between the displacement distance of the second lens 2 and the third lens group 3 along the optical axis and the angular relationship between the rotating lens barrel can be accurately calculated by simulation software, so that the rotating angle of the lens barrel can be set according to the calculation results. It corresponds to accurately adjust the displacement distance of the second lens 2 and the third lens group 3 along the optical axis direction, and then realize the coupling of the second lens 2, the third lens group 3 with the first lens 1 and the fourth lens 4, so that the adjustment of the second lens While the second lens 2 changes the focal length, it can be compensated by the third lens group 3 to ensure that the projected pattern after zooming is clear.

In some embodiments, the first lens 1 and the fourth lens 4 are arranged at both ends of the lens barrel, and the first lens 1 and the fourth lens 4 are arranged to be able to move along the optical axis direction, thereby passing through the first lens 1 and the second lens. The four lenses 4 are finely adjusted along the direction of the optical axis to realize clear edges of projection patterns of the projection optical system 100 at different focal lengths.

It can be understood that the present application realizes the zoom function by setting the second lens 2 to move relative to the first lens 1, changing the distance between the two lenses, and flexibly adjusting the focus. For example, the zoom factor of the projection optical system 100 of the present application can reach 1.8X above. At the same time, the third lens group 3 is arranged on the light incident side of the second lens 2 to realize the compensation function. After the zoom adjustment of the second lens 2 is completed, the clarity and distortion of the imaging picture can be improved by moving the third lens group 3 along the optical axis direction. and other features to improve image quality. The imaging quality can also be further improved by fine-tuning the first lens 1 and the fourth lens 4 along the optical axis.

In some embodiments, as shown in FIG. 1 and FIG. 2 , the projection optical system 100 further includes an aperture 5 disposed between the second lens 2 and the third lens group 3 . The second lens 2 can move between the first lens 1 and the diaphragm 5 along the optical axis direction, and the third lens group 3 can move between the diaphragm 5 and the fourth lens 4 along the optical axis direction.

In some embodiments, as shown in FIG. 1 and FIG. 2, the third lens group 3 includes a first positive lens 31, a first cemented lens, and a first negative lens 34 arranged in sequence along the optical axis direction, and the first positive lens 31 Having a positive optical power, the first negative lens 34 has a negative optical power. The first cemented lens includes a first sub-lens 32 with negative power and a second sub-lens 33 with positive power.

In this embodiment, as shown in FIG. 1 , the light incident surface of the first positive lens 31 can be set as a convex surface, the light exit surface can also be set as a convex surface, the light incident surface of the first sub-lens 32 can be set as a concave surface, and the light exit surface can be set as a convex surface. The light incident surface of the second sub-lens 33 can be set as a convex surface, the light exit surface can be set as a convex surface, the light incident surface of the first negative lens 34 can be set as a concave surface, and the light exit surface can be set as a concave surface.

The following Table 1 is the parameter information of each lens of the projection optical system 100 in this embodiment. The serial numbers 1-16 in the table represent the surface serial numbers of the optical elements arranged sequentially from the light exit side to the light incident side of the projection optical system 100, and the surfaces with the surface serial numbers 9 and 10 are the surfaces of the first cemented lens of the third lens group 3 respectively. The cemented surface of the first sub-lens 32 and the second sub-lens 33 . Wherein, the thickness represents the distance along the optical axis from the corresponding surface to the next surface. Nd is the refractive index of the corresponding lens, and Vd is the Abbe number of the corresponding lens.

As shown in Table 1, the distance between the first lens 1 and the second lens 2 is the first air gap d1, that is, d1 is the distance from the second surface to the third surface from the light exit side to the light incident side along the optical axis direction air spacer. Similarly, D4 is the air gap between the second lens 2 and the diaphragm 5, D5 is the air gap between the diaphragm 5 and the third lens group 3, so that the distance between the second lens 2 and the third lens group 3 is the second air interval d2, then d2=D4+D5. The distance between the third lens group 3 and the fourth lens 4 is a third air gap d3. d1, D4, D5 and d3 can vary as the second lens 2 and the third lens group 3 move along the optical axis direction.

Table 1

Table 2 shows the corresponding first air gap d1, the air gap D4 between the second lens 2 and the diaphragm 5, the diaphragm 5 and the third The values of the air space D5 and the third air space d3 between the lens groups 3 . Table 2 also shows the projection angles of the projection optical system 100 at corresponding focal lengths.

Table 2

Referring to Fig. 1, Table 1 and Table 2, in this embodiment, the total optical length of the projection optical system 100 of the present application is TTL1=79.71mm, the focal length range is adjustable, and the film 6 with a diameter of 15mm is used. The magnification is 2.1. And the focal length f1 satisfies: 24mm≤f1≤50mm, and the projection angle is 16.77-35.4 degrees. The first air gap d1 satisfies the formula: 0.04≤d1/TTL1≤0.27, wherein when d1/TTL1=0.04, d1=3.5mm, the focal length of the projection optical system is 24mm, when d1/TTL1=0.27, d1=21.90, the projection The focal length of the optical system is 50mm. The second air gap d2 satisfies the formula: 0.03≤d2/TTL1≤0.38, where d2/TTL1=0.03, d2=D4+D5=2+0.38=2.38, the focal length of the projection optical system is 50mm, and d2/TTL1=0.38 , d2=D4+D5=20.40+9.56=29.96, the focal length of the projection optical system is 24mm. The third air gap d3 satisfies the formula: 0.07≤d3/TTL1≤0.18, wherein when d3/TTL1=0.07, d3=5.24, the focal length of the projection optical system is 24mm, when d3/TTL1=0.18, d3=16.77, the projection The focal length of the optical system is 50mm. That is, the projection optical system 100 is adjusted to different focal lengths by adjusting the sizes of the corresponding first air gap d1 , the second air gap d2 and the third air gap d3 to realize the zoom function.

In some embodiments, referring to FIG. 3 and FIG. 4 , FIG. 2 is a schematic structural diagram of another projection optical system 100 of the present application, and FIG. 4 is a structural schematic diagram of the projection optical system shown in FIG. 3 at different focal lengths. In this embodiment, the third lens group 3 includes a second positive lens 35 with positive refractive power, a third positive lens 36 with positive refractive power, and a second cemented lens arranged in sequence along the optical axis direction, and the second cemented lens includes A third sub-lens 37 having negative power and a fourth sub-lens 38 having positive power.

In this embodiment, as shown in FIG. 3 , the light exit surface of the second positive lens 35 can be set as a convex surface, the light incident surface can be set as a convex surface, the light exit surface of the third positive lens 36 can be set as a convex surface, and the light entrance surface can be set as a convex surface. The light surface can be set as a concave surface, the light exit surface of the third sub-lens 37 can be set as a concave surface, the light incident surface can be set as a concave surface, the light exit surface of the fourth sub-lens 38 can be set as a convex surface, and the light incident surface can be set as a convex surface. Set to concave.

The following Table 3 is the parameter information of each lens of the projection optical system 100 in this embodiment. The serial numbers 1-16 in the table represent the surface serial numbers of the optical elements arranged sequentially from the light exit side to the light incident side of the projection optical system 100, and the surfaces with the surface serial numbers 11 and 12 are the second cemented lenses of the third lens group 3. The cemented surfaces of the third sub-lens 37 and the fourth sub-lens 38 have the same corresponding data. Thickness represents the distance along the optical axis from the corresponding surface to the next surface. Nd is the refractive index of the corresponding lens, and Vd is the Abbe number of the corresponding lens.

As shown in Table 3, the distance between the first lens 1 and the second lens 2 is the fourth air gap g4, that is, g4 is the distance from the second surface to the third surface from the light exit side to the light incident side along the optical axis direction air spacer. G4 is the air gap between the second lens 2 and the diaphragm 5, G5 is the air gap between the diaphragm 5 and the third lens group 3, so that the distance between the second lens 2 and the third lens group 3 is the fifth Air interval g5, then g5=G4+G5. The distance between the third lens group 3 and the fourth lens 4 is the sixth air gap g6. g4, G4, G5 and g6 can be changed as the second lens 2 and the third lens group 3 move along the optical axis direction.

table 3

Table 4 shows that in this embodiment, when the focal lengths of the projection optical system 100 are 37.5mm, 60mm and 75mm, the corresponding fourth air gap g4, the air gap G4 between the second lens 2 and the diaphragm 5, the diaphragm 5 and the first The values of the air gap G5 and the sixth air gap g6 between the three lens groups 3 . Table 4 also shows the projection angles of the projection optical system 100 at corresponding focal lengths.

Table 4

Referring to Fig. 3, Table 3 and Table 4, in this embodiment, the total optical length of the projection optical system 100 of the present application is TTL2 = 105 mm, a film 6 with a diameter of 25 mm is used, and the change magnification is 2. The focal length range is adjustable, and the focal length f2 meets: 37.5mm≤f2≤75mm, and the projection angle is 18.59-37.59 degrees. In this embodiment, referring to the above Table 4, the fourth air gap g4 satisfies the formula: 0.05≤g4/TTL2≤0.22, when g4/TTL2=0.05, g4=5.50mm, the focal length of the projection optical system is 75mm, when g4 When /TTL2=0.22, g4=22.97mm, and the focal length of the projection optical system is 37.5mm. The fifth air gap g5 satisfies the formula: 0.04≤g5/TTL2≤0.34, when g5/TTL2=0.04, g5=G4+G5=2.50+1.50=4mm, the focal length of the projection optical system is 37.5mm, when g5/TTL2= When 0.34, g5=G4+G5=19.97+16.01=35.98mm, the focal length of the projection optical system is 75mm. The sixth air gap g6 satisfies the formula: 0.08≤g6/TTL2≤0.22, when g6/TTL2=0.08, g6=8.45mm, the focal length of the projection optical system is 75mm, when g6/TTL2=0.22, g6=22.96mm, The focal length of the projection optical system is 37.5mm. By adjusting the size of the corresponding fourth air gap g4, fifth air gap g5 and sixth air gap g6, zoom adjustment can be realized, and the projected pattern after zooming has a higher imaging quality due to the setting of the third lens group 3 , that is, the setting of the third lens group 3 can keep the patterns of different sizes formed by zooming clear.

The present application also provides an electronic device, including the above-mentioned projection optical system 100 . The electronic device also includes a light source. The light beam provided by the light source passes through the film 6, the fourth lens 4, the third lens group 3, the second lens 2 and the first lens 1 in sequence, and finally projects to the corresponding position to form a projection pattern. In this application, the second lens 2 is set to move relative to the first lens 1 along the optical axis to change the focal length, and then the third lens group 3 can be moved along the optical axis by setting, so that the third lens group 3 of the second lens 2 can be adjusted. The distance between them can achieve the effect of adjusting the imaging definition. It can be understood that according to the relationship between the focal length and the angle of view, the change of the focal length will cause the change of the angle of view, thereby realizing the change of the projection angle or the size of the spot formed by projection. The third lens group 3 of the present application is along the direction of the optical axis. Moving, when the size of the spot formed by projection changes, it can ensure that the edges of the images of different sizes are clear, that is, to achieve high definition while having a high zoom ratio.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only represent several implementation modes of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as limiting the scope of the patent for the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims (10)

1. A projection optical system, characterized in that, the projection optical system comprises successively from the light exit side to the light entrance side: A first lens with positive refractive power, the light exit surface of the first lens is convex, and the light entrance surface is concave; A second lens with negative refractive power, the light exit surface and the light entrance surface of the second lens are both concave; a third lens group having positive power, said third lens group comprising at least three lenses having power; and, A fourth lens with positive refractive power, the light exit surface and the light entrance surface of the fourth lens are convex; Both the second lens and the third lens group are configured to be movable between the first lens and the fourth lens in an optical axis direction. 2. The projection optical system according to claim 1, characterized in that, the projection optical system comprises a lens barrel element, and the second lens and the third lens group communicate with the first lens through the lens barrel element. a lens coupled to the fourth lens; The lens barrel element is configured so that the amount of movement of one of the second lens and the third lens group along the direction of the optical axis has a linear relationship with the rotation angle of the lens barrel element, so that the The other one of the second lens and the third lens group has a non-linear relationship with the rotation angle of the lens barrel element. 3. The projection optical system according to claim 1, wherein the third lens group comprises a first positive lens, a first cemented lens and a first negative lens arranged in sequence along the optical axis direction, the The first cemented lens includes a first sub-lens with negative power and a second sub-lens with positive power. 4. The projection optical system according to claim 3, wherein the light exit surface of the first positive lens is a convex surface, and the light entrance surface is a convex surface; and/or The light exit surface of the first sub-lens is convex, and the light entrance surface is concave; and/or The light exit surface of the second sub-lens is convex, and the light entrance surface is convex; and/or The light emitting surface of the first negative lens is concave, and the light incident surface is concave. 5. The projection optical system according to claim 3, wherein the total optical length of the projection optical system is TTL1, the distance between the first lens and the second lens is a first air gap d1, The distance between the second lens and the third lens group is the second air gap d2, and the distance between the third lens group and the fourth lens is the third air gap d3; The first air interval d1, the second air interval d2 and the third air interval d3 satisfy the formula: 0.04≤d1/TTL1≤0.27; 0.03≤d2/TTL1≤0.38; 0.07≤d3/TTL1≤0.18 . 6. The projection optical system according to claim 1, wherein the third lens group comprises a second positive lens, a third positive lens and a second cemented lens arranged in sequence along the direction of the optical axis; The second cemented lens includes a third sub-lens with negative power and a fourth sub-lens with positive power. 7. The projection optical system according to claim 6, wherein the light exit surface of the second positive lens is convex, and the light incident surface is convex; and/or The light exit surface of the third positive lens is convex, and the light entrance surface is concave; and/or The light exit surface of the third sub-lens is concave, and the light entrance surface is concave; and/or The light emitting surface of the fourth sub-lens is convex, and the light incident surface is concave. 8. The projection optical system according to claim 6, wherein the total optical length of the projection optical system is TTL2, the distance between the first lens and the second lens is the fourth air gap g4, The distance between the second lens group and the third lens group is the fifth air gap g5, and the distance between the third lens group and the fourth lens group is the sixth air gap g6; The fourth air interval g4, the fifth air interval g5 and the sixth air interval g6 satisfy the formula: 0.05≤g4/TTL2≤0.22; 0.04≤g5/TTL2≤0.34; 0.08≤g6/TTL2≤0.22 . 9. The projection optical system according to claim 1, characterized in that, the projection optical system further comprises an aperture, and the aperture is arranged between the second lens and the third lens group. 10. An electronic device, comprising the projection optical system according to any one of claims 1-9.