CN110673293A

CN110673293A - Projection device and zoom lens thereof

Info

Publication number: CN110673293A
Application number: CN201910957646.1A
Authority: CN
Inventors: 陈友才; 杨长明
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2019-10-10
Filing date: 2019-10-10
Publication date: 2020-01-10

Abstract

The invention provides a projection device and a zoom lens thereof. Wherein, zoom lens includes: the lens comprises a lens barrel, a lens frame provided with lenses, a driving motor, a transmission mechanism and a guide mechanism; the wall of the lens cone is provided with an avoidance port and a first guide part of a guide mechanism; the lens frame is movably arranged in the lens cone and is provided with a second guide part of the guide mechanism; the driving motor is fixed in the outside of section of thick bamboo wall and is connected with the picture frame transmission through passing the drive mechanism who dodges the mouth, and the picture frame can be along the central axis motion of lens cone under driving motor and guiding mechanism's effect to drive mechanism's arc rack and gear keep meshing at the in-process of focusing. The projection device includes: the zoom lens comprises a shell, a light source arranged in the shell and the zoom lens arranged on a transmission path of light emitted by the light source. The projection device and the zoom lens thereof are beneficial to miniaturization and light weight.

Description

Projection device and zoom lens thereof

Technical Field

The invention relates to the field of projection display, in particular to a projection device and a zoom lens thereof.

Background

A projection apparatus is an apparatus capable of projecting an image onto a screen, and is generally used in the business or life fields. For example, some homes now use home projectors to view video images instead of traditional televisions.

The existing projection device often has the phenomenon that the projection picture becomes fuzzy. For example, when the projection apparatus is used for a period of time, the shape of the internal lens of the projection apparatus changes or moves due to thermal expansion and contraction, which causes optical distortion and analytical change, so that the projected image becomes blurred, and then focusing needs to be performed again. For another example, when the projection device is used in a moving scene, refocusing is required each time the projection device is used, so that the picture projected from the projection device onto the screen matches with the projection distance; especially for ultra-short focus projection devices, it is necessary to achieve a large projection effect at a short distance, and the requirement for focusing is more urgent. Therefore, some projection apparatuses now employ a zoom lens, so that when the image projected by the projection apparatus on the screen is blurred or the projection distance needs to be changed, the focus of the zoom lens can be adjusted to refocus, so as to make the image clear or adapt to the changed projection distance.

However, in both manual zooming and automatic zooming, a zoom lens used in a conventional projection apparatus needs to be provided with a complicated transmission mechanism, and a force is transmitted to a lens frame of the zoom lens through a lengthy transmission path so as to achieve zooming. For example, when the projection apparatus adopts a manual zoom method, an operation unit for a user to perform a zoom operation is often required to be provided outside the projection apparatus, and a large number of transmission mechanisms are required between the operation unit and a frame of the zoom lens to transmit a driving force of the user to the frame. For another example, when the projection apparatus adopts an automatic zooming mode, a driving motor is usually installed at the bottom of the housing, and then the driving force of the driving motor is transmitted to the lens frame of the zoom lens through a large number of transmission mechanisms. Therefore, no matter what zooming mode is adopted by the existing projection device, a complex transmission mechanism is needed to transmit the driving force of a user or a motor to the lens frame of the zoom lens through a long path, so that the weight of the projection device is increased, and the projection device is large in size and complex in structure.

Disclosure of Invention

The invention provides a projection device and a zoom lens thereof, which at least partially solve the problems of large volume and complex structure of the existing zoom type projection device or other potential technical problems.

According to some embodiments of the present invention, there is provided a zoom lens including: the lens comprises a lens barrel, a lens frame provided with lenses, a driving motor, a transmission mechanism and a guide mechanism;

the lens cone is provided with a central axis, and the cylinder wall of the lens cone is provided with an avoidance port;

the lens frame is arranged in the lens barrel, and the lens frame and the lens arranged on the lens frame are coaxial with the lens barrel;

the guide mechanism comprises a first guide part arranged on the lens barrel and a second guide part arranged on the lens frame;

the driving motor is fixed on the outer side of the cylinder wall and is in transmission connection with the mirror frame through the transmission mechanism penetrating through the avoidance port; the driving motor is used for being matched with the guide mechanism to drive the mirror frame to move along the central axis;

the transmission mechanism includes: the gear is fixed on a motor shaft of the driving motor, and the arc rack is fixed on the outer surface of the mirror frame; the arc-shaped rack and the gear are kept meshed in the focusing process of the zoom lens.

The zoom lens as described above, wherein one of the gear and the arc-shaped rack has a thickness greater than that of the other.

The zoom lens as described above, wherein the gear and the arc rack are engaged in the lens barrel; or the gear and the arc-shaped rack are meshed outside the lens barrel.

The zoom lens as described above, wherein the length of the arc-shaped rack along the circumferential direction of the lens frame is less than half of the circumference of the lens frame.

The zoom lens as described above, wherein the length of the arc-shaped rack along the circumferential direction of the lens frame is less than a quarter of the circumference of the lens frame.

The zoom lens is characterized in that the lens frame is provided with a first threaded hole, and the arc-shaped rack is provided with a second threaded hole aligned with the first threaded hole; and the fastener sequentially penetrates through the second threaded hole and the first threaded hole to fasten the arc-shaped rack and the mirror frame.

The zoom lens as described above, wherein the lens is mounted on a side of the lens frame near the outgoing light, and the arc-shaped rack is mounted on a side of the lens frame near the incoming light.

In the zoom lens described above, the arc-shaped rack may have a stopper extending in the direction of the central axis, the stopper may have a groove, and a part of the lens frame may be accommodated in the groove.

The zoom lens as described above, wherein the first guide portion includes a guide sliding groove provided on the lens barrel, the guide sliding groove being provided obliquely to the central axis, the second guide portion includes a guide post fixed to the lens frame, and a free end of the guide post extends into the guide sliding groove.

The zoom lens as described above, wherein the guide chute penetrates the barrel wall.

The zoom lens as described above, wherein the free end of the guide post passes through the guide chute and forms an enlarged portion.

The zoom lens as described above, wherein the lens barrel is provided with a plurality of guide chutes at intervals along the circumferential direction, and each guide chute is internally provided with a guide post fixed with the lens frame in a penetrating manner; all of the guide runners are spaced about the central axis.

The zoom lens as described above, wherein all of the guide chutes are uniformly arranged around the central axis.

According to some embodiments of the invention, there is provided a projection apparatus comprising: a housing, a light source, and a zoom lens as described above; the light source is arranged in the shell, and the zoom lens is arranged on a transmission path of light rays emitted by the light source.

According to the projection device and the zoom lens thereof, the driving motor is fixed on the cylinder wall of the lens cone, then the avoidance port through which the transmission mechanism passes is arranged on the cylinder wall, and the first guide part and the second guide part which are matched with each other are arranged on the lens cone and the lens frame, so that the lens frame can move along the central axis of the lens cone under the driving action of the driving motor and the guide action of the guide mechanism, and the focal length of the zoom lens is adjusted. The driving motor is fixed on the wall of the lens cone, so that the transmission path is effectively shortened, the number of components of a transmission mechanism can be reduced, and the miniaturization and the light weight of the projection device are facilitated; meanwhile, the arc-shaped rack is fixed on the outer surface of the lens frame, and at least one part of the arc-shaped rack is positioned in the lens barrel, so that the space in the lens barrel is effectively utilized, and the compactness of the projection device is further improved.

Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and other objects, features and advantages of the embodiments of the present invention will become more readily understood by the following detailed description with reference to the accompanying drawings. Embodiments of the invention will now be described, by way of example and not limitation, in the accompanying drawings, in which:

fig. 1 is a schematic partial structural diagram of a projection apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating a transmission path of a light beam and a size change of a projection screen before and after zooming of the projection apparatus in FIG. 1;

FIG. 3 is a side view of the zoom lens of FIG. 1;

FIG. 4 is a partial cross-sectional view of the projection device of FIG. 1;

FIG. 5 is an exploded view of the projection device of FIG. 4;

fig. 6 is a schematic structural view of the lens barrel in fig. 4.

Reference numerals:

10-partial structure of the projection device; 100-an optical machine;

200-a zoom lens;

201-lens barrel; 2011-dodge mouth;

2012-guide chute; 202-mirror frame;

203-a lens; 204-a guide post;

205-a drive motor; 206-gear;

207-arc rack; 2071-a block;

2072-grooves; 300-light source.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and simplicity in description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Fig. 1 shows a partial structure 10 of a projection apparatus provided in the present embodiment. As shown in fig. 1, the projection apparatus of the present embodiment is mainly composed of a housing, an optical engine 100, a zoom lens 200, and a light source 300.

A light source 300 is mounted within the housing that provides light for forming an image. For example, the light source 300 may include a laser, such as a three-primary color laser, or a monochromatic laser and a fluorescent color wheel, such as a blue laser and a fluorescent color wheel. Generally speaking, when a three-primary-color laser is used as a light source, the lasers with different primary colors can be driven and lightened to realize the output of lasers with different colors; and when the monochromatic laser and the fluorescent wheel are adopted to jointly form three primary colors of light, the three primary colors of light can be output in a time sequence mode. It should be understood that when a fluorescent wheel is used, a light beam emitted by a laser generally needs to be subjected to beam contraction, homogenization and shaping, then enters the fluorescent wheel for fluorescent excitation, and the fluorescence generated after excitation and the laser are subjected to light combination and then are output in time sequence.

In some examples, to reduce the coherence of the laser light, a diffuser member may be disposed in the optical path of the light source 300 for the purpose of homogenizing and eliminating the speckle. The diffuser can be fixed or rotating, or there can be several or several groups of diffusers, one or some of which can be fixed and others of which can be rotating.

The main components of the optical engine 100 are light valves, which can be configured to be of different types in different examples due to different projection architectures, such as LCOS (Liquid Crystal On Silicon), 3LCD (Liquid Crystal Display), DMD (Digital Micromirror Device), etc., and the number of light valves is not limited in this embodiment, and may be one or more pieces.

The zoom lens 200 may be, for example, an ultra-short-focus projection lens, and generally includes a refractive lens group and a reflective lens group, where the refractive lens group may include a plurality of lens groups, and the reflective lens group may be a curved mirror; by moving one or more lens groups in the refractive lens group along the direction of the optical axis, the size of the image can be changed. It should be understood that the group of lenses that can be moved in the direction of the optical axis is a specific set of lenses that is selected after being subjected to precise calculations under the guidance of optical principles.

Specifically, the zoom lens 200 is generally disposed in a housing and located on a light transmission path, and a refractive lens group thereof includes a lens barrel and a lens barrel mounted with lenses. The lens barrel is fixed in the housing, for example, a mounting seat may be provided in the housing, and the lens barrel is fixed on the mounting seat. The lens barrel is disposed inside the lens barrel and is movable along a central axis of the lens barrel, thereby changing a focal length of the zoom lens 200. In operation, the light beam emitted from the optical engine 100 is sent to the zoom lens 200 for imaging. When the image projected by the projection device becomes blurred or the projection distance needs to be changed, the focal length of the zoom lens 200 can be adjusted by driving the lens frame to move along the central axis, so that the projection light beam from the optical engine 100 to the zoom lens 200 is re-imaged to be clear again, and the size of the image is also changed correspondingly.

In the following, a laser projection apparatus with DLP architecture is taken as an example, and an imaging process thereof is briefly described to better understand the technical solution of the present embodiment.

After a laser beam emitted by a laser light source 300 (for example, a three-primary-color laser) passes through an illumination light path of the optical engine 100 (the illumination light path may include a homogenizing component such as a light guide or a fly-eye lens, and necessary optical components such as a light collecting lens group), the laser beam is shaped, and then enters a DMD with thousands of small mirrors on the surface at a preset angle and shape, and an image signal generating circuit generates a driving signal to drive some small mirrors in the DMD to turn over, so that the laser beam is sent to the zoom lens 200 in a reflective manner to be imaged. When the image on the screen is unclear or the projection distance needs to be adjusted, the lens can be zoomed by moving the lens in the zoom lens 200 along the optical axis direction, so that the requirement of adjusting the definition of the projection image or matching the projection size with the projection distance is met.

Fig. 2 illustrates a transmission path of the zoom lens 200 before and after zooming and a size change of an image projected on a screen. As shown in fig. 2, the direction of the optical axis is along the left-right direction in the figure, when the lens frame 202 of the zoom lens 200 moves left and right with the lens 203, the focal length of the light beam emitted from the zoom lens 200 changes accordingly, and it can be seen from the principle of projection that the size of the image projected at the focal position changes accordingly after the focal length changes. For example, assuming that the solid line in fig. 2 is the current light transmission path and the projection size h1 of the zoom lens 200 on the focal length, when the lens frame 202 in the zoom lens 200 moves forward a little bit with the lens 203, the focal length of the light beam irradiated from the zoom lens 200 moves forward, and the projection size of the zoom lens 200 on the focal length is also reduced accordingly, and the transmission path and the projection size h2 on the focal length are shown as the dotted lines in fig. 2. Therefore, the focal length of the zoom lens 200 can be adjusted by adjusting the position of the lens frame 202 in the zoom lens 200, so that the transmission path of light and the projection size on the focal length are changed, the focal length of the zoom lens 200 is adjusted to the position of the screen, and a clear picture is projected on the screen, that is, clear projection at any projection distance is realized.

FIG. 3 is a side view of the zoom lens of FIG. 1; FIG. 4 is a partial cross-sectional view of the projection device of FIG. 1; FIG. 5 is an exploded view of FIG. 4; fig. 6 is a schematic structural view of the lens barrel in fig. 4. As shown in fig. 3 to 6, the zoom lens 200 of the present embodiment is mainly composed of a lens barrel 201, a lens frame 202 on which a lens 203 is mounted, a driving motor 205, a transmission mechanism, and a guide column 204. The lens barrel 201 is arranged on a transmission path of light, a cylinder wall of the lens barrel 201 forms a closed ring shape around a central axis l of the lens barrel 201, and the left end and the right end of the lens barrel 201 are provided with openings so that the light can be emitted into the lens barrel 201 from the opening at one end, then passes through the lens 203 on the lens frame 202 and then is emitted from the opening at the other end. The cylinder wall is further provided with an avoidance opening 2011 extending along the central axis l of the lens barrel 201 and a guide chute 2012 inclined to the central axis l.

The lens frame 202 is mounted in the lens barrel 201 to be movable along the central axis l, and the lens frame 202 and the lens 203 mounted thereon are disposed coaxially with the lens barrel 201. The guiding column 204 passes through the guiding chute 2012 on the barrel wall of the lens barrel 201 and is fixed with the lens frame 202, so that the lens frame 202 can move along the guiding chute 2012.

The driving motor 205 is fixed on the cylinder wall of the lens barrel 201 and is in transmission connection with the lens frame 202 through a transmission mechanism passing through an avoidance port of the cylinder wall so as to drive the lens frame 202 to move. The transmission mechanism includes a gear 206 and an arc rack 207, the gear 206 is fixed on a motor shaft of the driving motor 205, the arc rack 207 is fixed on an outer surface of the lens frame 202, at least one of the gear 206 and the arc rack 207 passes through the avoiding opening 2011 and is engaged with the other, so that when the driving motor 205 is started, the gear 206 fixed on the motor shaft of the driving motor 205 can drive the arc rack 207 engaged therewith to rotate, and then drive the lens frame 202 fixed with the arc rack 207 to rotate, and as the lens frame 202 is fixed with the guide post 204 penetrating through the guide chute 2012 of the cylinder wall, the lens frame 202 moves along the central axis l of the lens barrel 201 under the guiding action of the guide post 204 and the guide chute 2012, thereby changing the focal length of the zoom lens 200.

For example, as shown in fig. 4, in some examples, an arc-shaped rack 207 fixed on the outer surface of the frame 202 passes through an escape opening 2011 of the cylinder wall to engage with the gear 206 outside the cylinder wall. For another example, in other examples, the gear 206 fixed on the motor shaft of the driving motor 205 may pass through the escape opening 2011 of the cylinder wall to engage with the arc-shaped rack 207 in the cylinder wall.

It should be understood that, based on the need for zooming, the arc-shaped rack 207 and the gear 206 need to be kept engaged during the focusing process of the zoom lens 200. Specifically, for the purpose of keeping the gear 206 and the arc-shaped rack 207 engaged during focusing of the zoom lens 200, in some examples, the width of one of the gear 206 and the arc-shaped rack 207 may be configured to be larger than the width of the other; in other examples, the gear 206 may be sleeved on the motor shaft in such a manner that the gear 206 can move along the motor shaft of the driving motor 205, and front and rear blocking pieces are formed by extending downward from front and rear sides of the arc-shaped rack, and a portion of the gear 206 is accommodated in an accommodating cavity formed by the front and rear blocking pieces.

Further, it should be understood that, although the present embodiment defines that the arc-shaped rack 207 and the gear 206 need to be kept engaged during zooming, the engaged state of the two before and after zooming is not limited. Meanwhile, when the arc-shaped rack 207 passes through the wall of the barrel 201 to engage with the gear 206, the width of the escape opening 2011 provided on the barrel 201 needs to be adapted to the movement of the arc-shaped rack 207.

In the zoom lens 200 of the present embodiment, the driving motor 205 is fixed on the cylinder wall of the lens barrel 201, and the driving motor 205 transmits the driving force to the lens frame 202 through the transmission mechanism composed of the gear 206 and the arc-shaped rack 207, so that the number of parts of the transmission mechanism is reduced, the transmission path is shortened, and the miniaturization and the light weight of the projection apparatus are facilitated; moreover, the arc-shaped rack 207 meshed with the gear 206 is fixed on the outer surface of the lens frame 202, and the transmission mechanism also passes through the avoidance port 2011 arranged on the cylinder wall of the lens barrel 201, so that the inner space of the lens barrel 201 and the thickness of the cylinder wall of the lens barrel are fully utilized, the structure of the zoom lens 200 becomes more compact, and the miniaturization and the light weight of the zoom lens 200 are further facilitated.

With continued reference to fig. 3 to 6, in the present embodiment, the lens barrel 201 may include a small-diameter barrel near the light exit direction and a large-diameter barrel near the light entrance direction, the large-diameter barrel and the small-diameter barrel being coaxial and forming a stepped surface at a junction of the small-diameter barrel and the large-diameter barrel. The avoidance port 2011 is arranged at the bottom of the large-diameter cylinder, and a guide chute 2012 inclined to the central axis l of the large-diameter cylinder is arranged between the avoidance port 2011 and the step surface.

The lens frame 202 is disposed in a large-diameter cylinder and is movable along the central axis l. The lens 203 mounted on the frame 202 may have a diameter that is the same as, slightly smaller than, or slightly larger than the small diameter cylinder as shown in fig. 4. An arc-shaped rack 207 is fixed to the frame 202, and a tooth-shaped portion of the arc-shaped rack 207 passes through an escape opening 2011 in the cylinder wall and engages with a gear 206 fixed to a motor shaft of the drive motor 205. As can be seen from fig. 3, the length of the arc-shaped rack 207 in the circumferential direction of the lens frame 202 is less than one-half of the circumference of the lens frame 202, or, more specifically, the length of the arc-shaped rack 207 in the circumferential direction of the lens frame 202 shown in fig. 3 is less than one-fourth of the circumference of the lens frame 202, so as to reduce the weight of the transmission mechanism and the space occupied thereby, thereby contributing to the miniaturization and weight saving of the zoom lens 200. Of course, in the present embodiment, the length of the arc-shaped rack 207 along the circumferential direction of the lens frame 202 is not limited, and the skilled person can choose to set the length of the arc-shaped rack 207 along the circumferential direction of the lens frame 202 to be one-eighth, one-half or any other suitable value according to actual needs, and of course, in some specific examples, the arc-shaped rack 206 can form a closed ring around the lens frame 202.

Referring to fig. 4 and 5, the lens 203 may be mounted on the side of the frame 202 adjacent to the outgoing light (i.e., the left side of fig. 4 and 5), and the arc-shaped rack 207 may be mounted on the side of the frame 202 adjacent to the incoming light (i.e., the right side of fig. 4 and 5). The arcuate rack 207 may be secured to the frame 202 by any suitable means, such as bolts, screws, welding, integral molding, and the like. For example, in some examples, a first threaded aperture may be provided in the frame 202 and a corresponding second threaded aperture may be provided in the arcuate rack 207 for alignment with the first threaded aperture in the frame 202, including but not limited to a bolt or screw fastener passing through the first and second threaded apertures to secure the arcuate rack 207 to the frame 202. In other examples, two first threaded holes may be provided at intervals along the circumferential direction of the frame 202, and the corresponding arc-shaped rack 207 may also be provided with two second threaded holes aligned with the first threaded holes on the frame 202.

With continued reference to fig. 5, in some examples, the arc-shaped rack 207 is formed with a stopper 2071 extending in the direction of the central axis l of the large-diameter barrel, and a groove 2072 having an opening on the left side is formed on the stopper 2071, and a part of the frame 202 is accommodated in the groove 2072.

Referring to fig. 5, the guiding column 204 includes a swelling portion and a rod portion, the rod portion is fixed to the lens frame 202 after passing through the guiding chute 2012, and the swelling portion is located outside the guiding chute 2012, that is, the swelling portion is located outside the lens barrel 201. In some examples, to improve the stability of the guidance, a plurality of guide runners 2012 (e.g., three) may be provided on the large diameter barrel at intervals around the central axis l of the large diameter barrel. In some specific examples, all of the guide runners 2012 may be uniformly arranged around the central axis l of the large diameter barrel. Taking three guide runners 2012 as an example, the included angles between the three guide runners 2012 are configured to be 120 degrees for the purpose of uniformly arranging the three guide runners 2012 around the central axis l of the large-diameter cylinder. It should be understood that in other examples, the number of the guide runners 2012 arranged in the circumferential direction of the large-diameter cylinder may be set according to actual needs, and the present embodiment is not limited to a specific number thereof.

It should be understood that, in the present embodiment, the guide column 204 and the guide chute 2012 are not limited to be provided in the structural form shown in fig. 3 to 6. For example, in some examples, the guiding chute 2012 may not extend through the wall of the barrel 201, and the free end of the guiding column 204 only needs to extend into the guiding chute 2012. As another example, even if the guide slot 2012 is disposed to penetrate the wall of the barrel 201, the guide column 204 need not penetrate the guide slot 2012 in some examples, and the free end of the guide column 204 may not form an enlarged portion in other examples. In other words, in the present embodiment, the specific structures of the guiding column 204 and the guiding chute 2012 and the matching manner thereof are not limited, and those skilled in the art can configure the guiding column and the guiding chute according to the actual needs while satisfying the guiding purpose of the guiding mechanism.

In addition, it should be noted that, although the above describes in detail with reference to fig. 2 to 6 that the present embodiment guides the movement of the lens frame 202 through the guiding mechanism composed of the guiding column 204 fixed on the lens frame 202 and the guiding chute 2012 arranged on the cylinder wall of the lens barrel 201, so that the lens frame 202 can move along the central axis l of the lens barrel 201 under the driving of the driving motor 205. However, in other examples, the guiding may be performed by other guiding manners, for example, a thread structure is formed on the outer surface of the lens frame 202 and the inner surface of the cylinder wall of the lens barrel 201 to match with each other to guide the lens frame 202. That is, in the present embodiment, it is only necessary that the first guide portion provided by the lens barrel 201 and the second guide portion provided by the lens frame 202 can cooperate with the driving motor 205 to realize the movement of the lens frame 202 along the central axis l when the zoom lens 200 focuses.

The zoom lens 200 shown in fig. 3 to 6 is taken as an example, and the working process thereof is briefly described so that those skilled in the art can better understand the technical solution of the present embodiment.

When zooming is required, the driving motor 205 mounted on the cylinder wall of the zoom lens 200 is controlled by a control device such as a remote controller to start and control the rotation direction, rotation speed, etc. of the driving motor 205. For example, the driving motor 205 is controlled by a remote controller to rotate clockwise, so as to drive the arc-shaped rack 207 to rotate counterclockwise, and accordingly the lens frame 202 fixed to the arc-shaped rack 207 also rotates counterclockwise, and the lens frame 202 moves along the central axis l of the lens barrel 201 while rotating counterclockwise due to the guiding action of the guiding columns 204 and the guiding chutes 2012, so that the focal length of the zoom lens 200 changes accordingly. For example, if the frame 202 can move to the left under the action of the guiding posts 204 and the guiding chutes 2012 when rotating counterclockwise, the transmission path of the light and the projection size on the screen can correspond to the dotted line in fig. 2.

Similarly, when the driving motor 205 is controlled by the remote controller to rotate counterclockwise, the arc-shaped rack 207 rotates clockwise, accordingly, the frame 202 fixed with the arc-shaped rack 207 is driven to rotate clockwise, and under the guiding action of the guiding column 204 and the guiding chute 2012, the frame 202 also moves along the central axis l of the lens barrel 201, so that the focal length of the zoom lens 200 is changed. Of course, the moving direction of the frame 202 when the frame 202 rotates clockwise is opposite to the moving direction when the frame 202 rotates counterclockwise. For example, when the frame 202 rotates counterclockwise and moves left under the action of the guide posts 204 and the guide runners 2012, the frame 202 rotates clockwise and moves right under the action of the guide posts 204 and the guide runners 2012.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zoom lens, comprising: the lens comprises a lens barrel, a lens frame provided with lenses, a driving motor, a transmission mechanism and a guide mechanism;

2. The zoom lens according to claim 1, wherein one of the gear and the arc-shaped rack has a thickness greater than that of the other.

3. The zoom lens according to claim 2, wherein the gear and the arc-shaped rack are engaged outside the lens barrel.

4. The zoom lens according to claim 1, wherein a length of the arc-shaped rack along a circumferential direction of the lens frame is less than half of a circumference of the lens frame.

5. A zoom lens according to any one of claims 1 to 4, wherein the lens is mounted on the frame on the side closer to the outgoing ray, and the arc-shaped rack is mounted on the frame on the side closer to the incoming ray.

6. The zoom lens according to claim 5, wherein the arc-shaped rack is formed with a stopper extending in the direction of the central axis, the stopper being formed with a groove, and a part of the lens frame being accommodated in the groove.

7. A zoom lens according to any one of claims 1 to 4, wherein the first guide portion includes a guide slide groove provided on the lens barrel, the guide slide groove being provided obliquely to the central axis, and the second guide portion includes a guide post fixed to the lens frame, a free end of the guide post projecting into the guide slide groove.

8. The zoom lens according to claim 7, wherein the guide chute penetrates the cylinder wall; the free end of the guide post passes through the guide chute and forms an enlarged portion.

9. The zoom lens according to claim 8, wherein the lens barrel is provided with a plurality of guide chutes at intervals in a circumferential direction, and each guide chute is provided with a guide post fixed to the lens frame; all the guide chutes are arranged around the central axis at intervals;

all the guide runners are arranged uniformly around the central axis.

10. A projection device, comprising: a housing, a light source, and the zoom lens of any one of claims 1-9; the light source is arranged in the shell, and the zoom lens is arranged on a transmission path of light rays emitted by the light source.