CN110673293B

CN110673293B - Projection device and zoom lens thereof

Info

Publication number: CN110673293B
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: 2024-10-18
Anticipated expiration: 2039-10-10
Also published as: CN110673293A

Abstract

The invention provides a projection device and a zoom lens thereof. Wherein, zoom lens includes: the lens barrel is provided with a lens frame, a driving motor, a transmission mechanism and a guide mechanism; the cylinder wall of the lens cone is provided with an avoidance port and a first guide part of the guide mechanism; the second guiding part is movably arranged in the lens barrel and provided with a guiding mechanism; the driving motor is fixed on the outer side of the cylinder wall and is in transmission connection with the lens frame through a transmission mechanism penetrating through the avoidance port, the lens frame can move along the central axis of the lens barrel under the action of the driving motor and the guide mechanism, and an arc-shaped rack and a gear of the transmission mechanism are kept meshed in the focusing process. The projection device includes: the zoom lens includes a housing, a light source disposed within the housing, and the zoom lens as described above disposed on a transmission path of light emitted from 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 present invention relates to the field of projection display, and more particularly, to a projection device and a zoom lens thereof.

Background

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

The existing projection device often has the phenomenon that a projection picture becomes blurred. For example, when the projection device is used for a period of time, the lens therein may have a shape change or movement caused by expansion and contraction, which may cause optical distortion and analysis distortion, so that the projected image becomes blurred, and focusing is required again. For another example, using the projection device in a moving scene, refocusing is required each time the projection device is used, so that the picture projected onto the screen from the projection device is matched with the projection distance; especially for ultra-short focal projection devices, the requirement of focusing is more urgent because a large-format projection effect needs to be realized in a short distance. Therefore, some projection devices now use a zoom lens, so that when the image projected onto the screen by the projection device is blurred or the projection distance needs to be changed, the focus of the zoom lens can be adjusted to refocus, so that the image becomes clear or the projection distance after being changed is adapted.

However, the zoom lens used in the existing projection device needs to be provided with a complex transmission mechanism for manual zooming or automatic zooming, and force is transmitted to a lens frame of the zoom lens through a lengthy transmission path so as to realize zooming. For example, when the projection apparatus adopts a manual zoom method, an operation unit for performing a zoom operation by a user 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 a large number of transmission mechanisms are used to transmit the driving force of the driving motor to the lens frame of the zoom lens. Therefore, no matter what zooming mode is adopted in the existing projection device, a complex transmission mechanism is required to transmit the driving force of a user or a motor to the lens frame of the zoom lens through a lengthy path, which not only increases the weight of the projection device, but also makes the projection device bulky 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 huge volume and complex structure or other potential technical problems of the existing zoom type projection device.

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

the lens cone is provided with a central axis, and the 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 lenses 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 comprises: the gear is fixed on a motor shaft of the driving motor, and the arc-shaped 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-shaped rack are engaged in the lens barrel; or the gear is meshed with the arc-shaped rack outside the lens barrel.

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

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

The zoom lens, wherein 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; the fastener passes through the second threaded hole and the first threaded hole in sequence so as to tightly fix 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.

The zoom lens as described above, wherein the arc-shaped rack is formed with a stopper extending toward the central axis direction, the stopper is formed with a groove, and a part of the lens frame is accommodated in the groove.

The zoom lens as described above, wherein the first guide portion includes a guide chute provided on the lens barrel, the guide chute 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 extending into the guide chute.

The zoom lens as described above, wherein the guide chute penetrates through the cylinder 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 comprises a lens barrel, wherein the lens barrel is provided with a plurality of guide sliding grooves at intervals along the circumferential direction, and a guide post fixed with the lens frame is arranged in each guide sliding groove in a penetrating way; all the guide sliding grooves are arranged at intervals around the central axis.

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

According to some embodiments of the invention, there is provided a projection apparatus including: 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 barrel, the avoiding opening through which the transmission mechanism passes is formed in the cylinder wall, and the first guide part and the second guide part which are matched with each other are formed in the lens barrel and the lens frame, so that the lens frame can move along the central axis of the lens barrel under the driving action of the driving motor and the guiding 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 barrel, so that the transmission path is effectively shortened, the number of parts of the transmission mechanism can be reduced, and the miniaturization and the light weight of the projection device are facilitated; meanwhile, as the arc-shaped rack is fixed on the outer surface of the lens frame, at least one part of the arc-shaped rack is positioned inside the lens barrel, so that the space in the lens barrel is effectively utilized, and the compactness of the projection device is further improved.

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 embodiments of the present invention will become more readily apparent from 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 figures of the accompanying drawings, in which:

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

FIG. 2 is a schematic diagram showing a transmission path of a beam and a size change of a projection screen before and after zooming of the projection device 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 of fig. 4.

Reference numerals:

10-a partial structure of the projection device; 100-ray machine;

200-zoom lens;

201-a lens barrel; 2011-an avoidance port;

2012-guiding a chute; 202-a mirror frame;

203-a lens; 204-a guide post;

205-driving a motor; 206-a gear;

207-arc rack; 2071-stop;

2072-groove; 300-light source.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

In the description of the present invention, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means 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 present invention. In this specification, schematic representations of the above terms are not necessarily directed 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, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

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

The light source 300 is mounted within the housing, which provides light that forms an image. Taking a laser projection device as an example, the light source 300 includes a laser, for example, a trichromatic laser, or a monochromatic laser and a fluorescent color wheel, such as a blue laser and a fluorescent color wheel. Generally, when a laser with three primary colors is used as a light source, lasers with different primary colors can be driven to light so as to realize the output of laser with various colors; 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 realized by a time sequence output mode. It should be understood that when a fluorescent wheel is adopted, the light beam emitted by the laser needs to be condensed, homogenized and shaped, then is incident into the fluorescent wheel to perform fluorescence excitation, and the fluorescence generated after excitation and the laser are combined and then output in time sequence.

In some examples, to reduce the coherence of the laser light, a diffuser member may be provided in the optical path of the light source 300 for the purpose of homogenizing the speckle. The diffusion sheets may be fixedly arranged, or may be rotationally movable, or a plurality or groups of diffusion sheets may be arranged, one or some of which may be fixedly arranged, while the other or others of which are rotationally movable.

The main components of the light engine 100 are light valves, which may be configured in different types in different examples due to different projection architectures, for example LCOS (Liquid Crystal On Silicon, liquid crystal on silicon or Liquid crystal on chip), 3LCD (Liquid CRYSTAL DISPLAY), DMD (Digital Micromirror Device, digital micromirror), etc., and the number of light valves may be one or more in the present embodiment without limiting the number of light valves.

The zoom lens 200 may be, for example, an ultra-short focal projection lens, which typically has a refractive lens group, which may include a plurality of lens groups, and a mirror group, which may be a piece of curved mirror; the size of the imaging can be changed by moving one or more lens groups of the refractive lens group in the direction of the optical axis. It should be understood that a lens group that is movable in the direction of the optical axis is a particular lens group that is selected after a precise calculation under the guidance of optical principles.

Specifically, the zoom lens 200 is generally disposed in a housing and located on an optical transmission path, and its refractive lens group includes a lens barrel and a lens frame to which lenses are mounted. Wherein the lens barrel is fixed in the housing, for example, a mounting seat can be arranged in the housing, and the lens barrel is fixed on the mounting seat. The lens frame is disposed within 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, a light beam emitted from the optical engine 100 is sent to the zoom lens 200 to be imaged. When the image projected by the projection device becomes blurred or the projection distance needs to be changed, the lens frame is driven to move along the central axis, so that the focal length of the zoom lens 200 can be adjusted, the projected light rays emitted from the optical machine 100 to the zoom lens 200 re-image becomes clear again, and the size of the image is correspondingly changed.

Taking a laser projection device with a DLP architecture as an example, the imaging process is briefly described below, so as to better understand the technical scheme of the present embodiment.

After the laser beam emitted from the laser light source 300 (for example, a tricolor laser) is shaped by an illumination light path (the illumination light path may include a homogenizing component such as a light conductor or a fly's eye lens, and an optical component such as a light receiving lens group) of the optical engine 100, the laser beam is incident on a DMD having thousands of small mirrors on a surface thereof at a predetermined angle and shape, and an image signal generating circuit generates a driving signal to drive some of the small mirrors in the DMD to turn, so that the light beam is sent into the zoom lens 200 in a reflective manner for imaging. When the image on the screen is unclear or the projection distance needs to be adjusted, the lens in the zoom lens 200 is moved along the optical axis direction, so that the zoom of the lens can be realized, and the adjustment of the definition of the projection image or the matching of the projection size and the projection distance can be satisfied.

Fig. 2 illustrates a transmission path of the zoom lens 200 before and after zooming and a dimensional change of an image projected on a screen. As shown in fig. 2, when the frame 202 of the zoom lens 200 moves left and right with the lens 203, the focal length of the light beam irradiated from the zoom lens 200 changes accordingly, and as the projection principle shows, after the focal length changes, the size of the image projected at the focal length position changes accordingly. 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 slightly forward 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 correspondingly reduced, and the transmission path and the projection size h2 on the focal length are shown by the dashed line in fig. 2. It can be seen that by adjusting the position of the lens frame 202 in the zoom lens 200, the focal length of the zoom lens 200 can be adjusted, so as to change the transmission path of light and the projection size on the focal length, so as to adjust the focal length of the zoom lens 200 to the position of the screen, thereby projecting a clear picture on the screen, that is, implementing clear projection at any projection distance.

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 of 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 frame 202 to which a lens 203 is attached, a driving motor 205, a transmission mechanism, and a guide post 204. The lens barrel 201 is disposed on a light transmission path, a wall of the lens barrel forms a closed ring shape around a central axis l of the lens barrel 201, and both left and right ends of the lens barrel 201 are provided with openings so that light is emitted into the lens barrel 201 from an opening at one end and then emitted from an opening at the other end after passing through a lens 203 on the lens frame 202. The cylinder wall is also provided with a relief port 2011 extending along a central axis l of the lens barrel 201 and a guide chute 2012 inclined to the central axis l.

A mirror frame 202 is mounted in the barrel 201 and is movable along a central axis l, the mirror frame 202 and a lens 203 mounted thereon being disposed coaxially with the barrel 201. The guide posts 204 are secured to the frame 202 through guide slots 2012 on the barrel wall of the barrel 201, thereby enabling movement of the frame 202 along the guide slots 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 penetrating through an avoidance port of the cylinder wall so as to drive the lens frame 202 to move. The transmission mechanism comprises a gear 206 and an arc-shaped rack 207, the gear 206 is fixed on a motor shaft of the driving motor 205, the arc-shaped rack 207 is fixed on the outer surface of the lens frame 202, at least one of the gear 206 and the arc-shaped rack 207 penetrates through the avoidance port 2011 and is meshed with the other, so that after the driving motor 205 is started, the gear 206 fixed on the motor shaft of the driving motor 205 can drive the arc-shaped rack 207 meshed with the gear 206 to rotate, and then drive the lens frame 202 fixed with the arc-shaped rack 207 to rotate, and the lens frame 202 is fixed with the guide post 204 penetrating through the guide chute 2012 of the cylinder wall under the guide action of the guide post 204 and the guide chute 2012, so that the lens frame 202 moves along the central axis l of the lens barrel 201, and the focal length of the zoom lens 200 is changed.

For example, as shown in fig. 4, in some examples, an arcuate rack 207 secured to an outer surface of the frame 202 engages the gear 206 outside the barrel wall through a relief opening 2011 of the barrel wall. For another example, in other examples, a gear 206 fixed to the motor shaft of the drive motor 205 may engage the arcuate rack 207 within the cartridge wall through a relief port 2011 of the cartridge wall.

It should be appreciated that, based on the zoom requirement, there is a need to maintain engagement between the arcuate rack 207 and the gear 206 during focusing of the zoom lens 200. Specifically, for the purpose of maintaining engagement of the gear 206 and the arc-shaped rack 207 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 by moving the gear 206 along the motor shaft of the driving motor 205, and simultaneously, the front and rear sides of the arc-shaped rack may extend downward to form front and rear baffles, and a portion of the gear 206 is accommodated in a receiving cavity formed by the front and rear baffles.

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

Since the zoom lens 200 of the present embodiment fixes the driving motor 205 on the wall of the 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, the number of parts of the transmission mechanism is reduced and the transmission path is shortened, which is advantageous for miniaturization and weight saving of the projection apparatus; moreover, since 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 avoiding opening 2011 formed in the wall of the lens barrel 201, the inner space of the lens barrel 201 and the thickness of the wall of the lens barrel are fully utilized, so that the structure of the zoom lens 200 becomes more compact, and the miniaturization and the weight reduction 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 cylinder near the light exit direction and a large diameter cylinder near the light entrance direction, the large diameter cylinder and the small diameter cylinder being coaxial and forming a stepped surface at the junction of the small diameter cylinder and the large diameter cylinder. The bottom of the large-diameter cylinder is provided with the avoiding opening 2011, and a guide chute 2012 inclined to the central axis l of the large-diameter cylinder is arranged between the avoiding opening 2011 and the step surface.

The mirror frame 202 is disposed in a large diameter cylinder and is movable along a central axis l. The diameter of the lens 203 mounted on the frame 202 may be the same as, slightly smaller than, or slightly larger than the diameter of the small diameter barrel as shown in fig. 4. An arc-shaped rack 207 is fixed to the mirror frame 202, and a toothed portion of the arc-shaped rack 207 passes through a relief opening 2011 in the wall of the barrel and is engaged with a gear 206 fixed to a motor shaft of the driving motor 205. As can be seen from fig. 3, the length of the arc-shaped rack 207 along 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 along 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 facilitating 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 one skilled in the art may choose to set the length of the arc-shaped rack 207 along the circumferential direction of the lens frame 202 to one-eighth, one-half, or any other suitable value of the circumference of the lens frame 202 according to actual needs, and of course, in some specific examples, the arc-shaped rack 206 may form a closed loop around the lens frame 202.

Referring to fig. 4 and 5, the lens 203 may be mounted on a side of the frame 202 near the outgoing light (i.e. left side of fig. 4 and 5), and the arc-shaped rack 207 may be mounted on a side of the frame 202 near the incoming light (i.e. 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 hole may be provided in the frame 202 and a corresponding second threaded hole may be provided in the arcuate rack 207 for alignment with the first threaded hole in the frame 202, including but not limited to, a bolt or screw fastener passing through the first and second threaded holes 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 arcuate 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 arcuate rack 207 is formed with a stop 2071 extending toward the central axis l of the large diameter barrel, the stop 2071 being formed with a recess 2072 opening to the left, a portion of the frame 202 being received in the recess 2072.

Referring to fig. 5, the guide post 204 includes an expansion portion and a rod portion, the rod portion is fixed to the lens frame 202 after passing through the guide chute 2012, and the expansion portion is located outside the guide chute 2012, that is, outside the expansion portion of the lens barrel 201. In some examples, to improve stability of the guide, a plurality of guide slots 2012 (e.g., three) may be provided on the large diameter cylinder at intervals about the central axis l of the large diameter cylinder. In some specific examples, all of the guide slots 2012 may be evenly disposed about the central axis l of the large diameter cylinder. Taking three guide slots 2012 as an example, the included angle between the three guide slots 2012 is configured to be 120 degrees for the purpose of evenly arranging the three guide slots 2012 around the central axis l of the large diameter barrel. 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 post 204 and the guide chute 2012 must be provided in the structural form shown in fig. 3 to 6 without limitation. For example, in some examples, the guide chute 2012 may not extend through the wall of the barrel 201, and the free end of the guide column 204 need only extend into the guide chute 2012. As another example, even though the guide chute 2012 is disposed through the wall of the barrel 201, the guide post 204 need not pass through the guide chute 2012 in some examples, although in other examples the free end of the guide post 204 may not form an enlarged portion. In other words, in the present embodiment, the specific structure of the guide posts 204 and the guide runners 2012 and the mating manner thereof are not limited, and those skilled in the art can configure the guide posts according to actual needs while satisfying the guiding purpose of the guide mechanism.

In addition, it should be noted that, although the above description is made in detail with reference to fig. 2 to 6, the present embodiment guides the movement of the lens frame 202 by a guide mechanism composed of a guide post 204 fixed to the lens frame 202 and a guide chute 2012 provided on the 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 drive of the driving motor 205. In other examples, the guiding of the lens frame 202 may be performed by other guiding methods, for example, a threaded structure is formed on the outer surface of the lens frame 202 and the inner surface of the barrel wall of the lens barrel 201, which are matched with each other. That is, in the present embodiment, it is only necessary that the first guide portion provided for the lens barrel 201 and the second guide portion provided for the lens frame 202 be able to cooperate with the driving motor 205 to realize movement of the lens frame 202 along the central axis l when the zoom lens 200 is focused.

The working process of the zoom lens 200 shown in fig. 3 to 6 will be briefly described below, so that those skilled in the art can better understand the technical solution of the present embodiment.

When zooming is required, a driving motor 205 mounted on the barrel wall of the zoom lens 200 is controlled to be started by a control device such as a remote controller and the rotational direction, rotational speed, etc. of the driving motor 205 are controlled. For example, the driving motor 205 is controlled to rotate clockwise by a remote controller, so that the arc-shaped rack 207 is driven to rotate counterclockwise, and the corresponding lens frame 202 fixed to the arc-shaped rack 207 is rotated counterclockwise, and the lens frame 202 moves along the central axis l of the lens barrel 201 due to the guiding action of the guiding posts 204 and the guiding sliding grooves 2012 while rotating counterclockwise, so that the focal length of the zoom lens 200 is changed accordingly. For example, it is assumed that the mirror frame 202 can be moved to the left by the guide posts 204 and the guide runners 2012 when rotated counterclockwise, and the transmission path of the light and the projection size on the screen can correspond to the dashed line in fig. 2.

Similarly, when the remote controller controls the driving motor 205 to rotate anticlockwise, the arc rack 207 rotates clockwise, and accordingly, the mirror frame 202 fixed with the arc rack 207 rotates clockwise, and under the guiding action of the guiding post 204 and the guiding chute 2012, the mirror frame 202 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 movement direction of the mirror frame 202 when the mirror frame 202 rotates clockwise is opposite to the movement direction when the mirror frame 202 rotates counterclockwise. For example, when the mirror frame 202 moves left by the guide posts 204 and the guide runners 2012 when rotated counterclockwise, the mirror frame 202 moves right by the guide posts 204 and the guide runners 2012 when rotated clockwise.

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

Claims

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

The first guide part comprises a guide chute arranged on the lens barrel, the guide chute is inclined to the central axis, the second guide part comprises a guide column fixed on the lens frame, and the free end of the guide column extends into the guide chute;

The transmission mechanism comprises: the gear is fixed on a motor shaft of the driving motor, and the arc-shaped 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 length of the arc-shaped rack along the circumferential direction of the mirror frame is less than half of the circumference of the mirror frame;

The arc-shaped rack is provided with a stop block extending towards the central axis direction, a groove is formed in the stop block, and a part of the mirror frame is accommodated in the groove.

2. The zoom lens of 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. A zoom lens according to any one of claims 1 to 3, wherein the lens is mounted on a side of the frame adjacent to the outgoing light, and the curved rack is mounted on a side of the frame adjacent to the incoming light.

5. The zoom lens of claim 1, wherein the guide chute extends through the barrel wall; the free end of the guide post passes through the guide chute and forms an enlarged portion.

6. The zoom lens according to claim 5, wherein the lens barrel is provided with a plurality of guide sliding grooves at intervals along the circumferential direction, and a guide post fixed with the lens frame is penetrated in each guide sliding groove; all the guide sliding grooves are arranged at intervals around the central axis;

all the guide sliding grooves are uniformly distributed around the central axis.

7. A projection apparatus, comprising: a housing, a light source, and a zoom lens according to any one of claims 1 to 6; 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.