TWI398667B - Optical zoom system and method thereof - Google Patents

Description

Optical zoom system and method

The present invention relates to an optical system, and more particularly to an optical zoom system and method.

Zoom refers to the adjustment of the equivalent focal length of the optical system between a shortest and longest focal length. The depth of field and imaging magnification can be changed by changing the equivalent focal length. Optical devices such as cameras, telescopes, and projectors are often equipped with an optical zoom system to capture scenes at different distances or to adjust the projected image magnification.

The optical imaging path is composed of optical elements such as lenses or mirrors. Generally, the equivalent focal length of the system can be adjusted by changing the curvature of the optical element, changing the refractive index of the optical element, and moving the optical element. Among them, optical components are most popular for moving zoom, and can be divided into two types: optical compensation type zoom and mechanical compensation type zoom.

The optically compensated zoom system is an early zoom technique proposed. Please refer to the first figure, which is a schematic diagram of the configuration of an optical compensation type zoom system of a prior art. As shown, the optically compensated zoom system 10 includes a plurality of lenses 111, 112, 113, 121, 122 disposed along an optical axis X, wherein the lenses 111, 112, 113 are fixed to the optical axis X, and the lenses 121, 122 They can move together along the optical axis X and are spaced apart from the fixed lenses 111, 112, 113. By driving the lenses 121, 122 to move the same distance in the same direction, the equivalent focal length of the optically compensated zoom system 10 can be changed.

However, in the zooming process of the optically compensated zoom system 10, the object image conjugate distance will be changed together, resulting in a positional shift of the image plane, resulting in poor image quality. A mechanically compensated zoom system provides better image quality. Please refer to the second figure, which is a schematic diagram of the configuration and operation of a mechanically compensated zoom system of the prior art. As shown, the mechanically compensated zoom system 20 includes a plurality of lenses 211, 212, 213 disposed along the optical axis X, wherein the lens 211 is fixed to the optical axis X, and the lenses 212, 213 are individually optical axes. X moves.

In the mechanically compensated zoom system 20, the equivalent focal length of the system is changed by adjusting the position of the lens 212, but when changing the position of the lens 212, the position of the lens 213 must be simultaneously adjusted to compensate for the variation of the object image conjugate distance, and control System imaging is maintained in the same location. During zooming, the lenses 212, 213 have individual movement directions and displacements. As shown in the second figure, the lens 211 is maintained at the position A1 during the change from the short focus to the medium focus and the tele focus of the mechanically compensated zoom system 20; the lens 212 is linearly displaced from the position B1 to the position along the optical axis X. B2 and position B3; and the lens 213 is displaced along the optical axis X from the position C1 to the position C2 and the position C3, and the movement trajectory is nonlinear.

In practice design, the optically compensated zoom system only needs to combine the preset displacement lens combinations and control the linear movement of these lenses; while the mechanically compensated zoom system requires the cam mechanism to move the lens simultaneously along the individual schedule. The track travels. Due to the improvement of cam machining accuracy, the mechanical compensation zoom system has become the mainstream type of optical zoom. However, complicated cam mechanisms have created a design burden on the miniaturization trend of optical devices.

In view of this, the inventor of the present invention has proposed the present invention to improve the complicated structure of the existing mechanically compensated zoom system and maintain good image quality.

Accordingly, it is an object of the present invention to provide an optical zoom system and method for modifying the mechanical position of an optical zoom system by controlling the variable optical element to change optical characteristics to correct imaging position variation caused by changes in focal length of the system. And maintain good image quality.

The invention discloses an optical zoom system comprising an optical mechanism module, a fixed lens group, a moving lens group and a control module. The optical mechanism module defines an optical axis and has a driving mechanism movable along the optical axis. The fixed lens group includes at least one lens and an adjustable optical element fixed to the optical mechanism module along the optical axis. The moving lens group includes at least two lenses fixed to the driving mechanism along the optical axis, and each lens of the moving lens group is spaced apart from the lens of the fixed lens group and the variable optical element. The control module controls the driving mechanism to move along the optical axis according to a zoom command to change the position of the lens of the moving lens group and control the optical characteristics of the variable optical element.

In one embodiment, the variably optical element is a liquid lens and has a curved surface, and the optical characteristics of the tunable optical element controlled by the control module are the curvature of the curved surface.

The invention further discloses an optical zoom system comprising an optical mechanism module, a fixed lens group, a moving lens group and a control module. The optical mechanism module defines an optical axis and has a driving mechanism movable along the optical axis. The fixed lens group includes at least two lenses fixed to the optical mechanism module along the optical axis. The moving lens group includes at least one lens and an adjustable optical element, and is fixed to the driving mechanism along the optical axis, and moves the lens of the lens group and the variable optical element to be spaced apart from the lens of the fixed lens group. The control module controls the driving mechanism to move along the optical axis according to a zoom command to change the position of the lens and the variable optical element of the moving lens group, and control the optical characteristics of the variable optical element.

In one embodiment, the variably optical element is a liquid lens and has a curved surface, and the optical characteristics of the tunable optical element controlled by the control module are the curvature of the curved surface.

The invention further discloses an optical zooming method, which is suitable for an optical zoom system, which comprises a fixed lens group, a moving lens group and a variable optical element arranged along an optical axis, a fixed lens group, and a moving lens. The arrangement of the lens group and the variable variability optical element forms at least three variable pitches. The optical zoom method includes the steps of: first receiving a zoom instruction; secondly, obtaining a magnification change value and a compensation modulation value according to the zoom instruction; and finally, generating a driving signal driving and driving mechanism according to the magnification change value. Moving along the optical axis to change the position of the moving lens group on the optical axis, with the change of the length of the variable pitch; and, according to the compensation modulation value, generating a modulation signal to control the variable optical element to change optical characteristics.

In one embodiment, the variably optical element is a liquid lens and has a curved surface, and the optical characteristics of the tunable optical element controlled by the control module are the curvature of the curved surface.

In one embodiment, the fixed lens group includes at least one lens and the variable optical element, and the moving lens group includes at least two lenses, and the lens system of the moving lens group is spaced apart from the lens of the fixed lens group and the variable optical element. Arrange to form the variable spacing.

In another embodiment, the fixed lens group includes at least one lens, the moving lens group includes at least one lens and the adjustable optical element, the lens system of the fixed lens group and the lens and the variable optical element of the moving lens group Arranged at intervals to form the variable spacing.

Therefore, the optical zoom system and method disclosed in the present invention divides the lens of the fixed lens group and the lens of the moving lens group, and controls the moving lens group to move along the optical axis to change the equivalent focal length of the system. Controlling the variable optical element to change the optical characteristics to correct the imaging position variation caused by the change in the focal length of the system. As a result, the mechanical structure of the optical zoom system can be simplified and good image quality can be maintained.

The above summary, the following detailed description and the annexed drawings are intended to further illustrate the manner, the Other objects and advantages of the present invention will be described in the following description and drawings.

The invention provides an optical zoom system and method, which can be applied to an optical device such as a projector, a camera, a telescope, etc., and uses lens movement to change the equivalent focal length of the system imaging. In order to simplify the complex structure formed by the existing mechanically compensated zoom cam mechanism, the present invention adopts an optically compensated zoom architecture and compensates for the object image conjugate distance variation caused by the change of the focal length magnification with the variable optical component. The system imaging position is maintained on a predetermined imaging surface, allowing the system to maintain good image quality.

First, please refer to the third figure, which is a schematic diagram of the system architecture of the optical zoom system disclosed in the present invention. As shown, the optical zoom system 30 is comprised of a control module 31 and an optical mechanism module 32. The control module 31 includes a controller 310, an input unit 311, a driving unit 312, and a modulation unit 313. The optical mechanism module 32 includes a driving mechanism 320, a fixed lens group 321, a moving lens group 322, and an adjustable optical element 323.

The optical mechanism module 32 is composed of an optical component and an auxiliary auxiliary mechanism. The function is to capture an image along an optical axis to a predetermined imaging surface and accept control of the control module 31 to change the equivalent focal length of the system. The optical mechanism module 32 typically has a body (not shown) that serves as a frame to secure the various components. The driving mechanism 320 is fixed on the body of the optical mechanism module 32 and coupled to the control module 31 to receive the control thereof, and is displaced along the optical axis within a limited range to change the focal length of the system.

The fixed lens group 321 is composed of a lens and is fixed to the body along the optical axis. The moving lens group 322 is composed of a lens and is fixed on the driving mechanism 320 along the optical axis to change the position on the optical axis along with the displacement of the driving mechanism 320. The curvature and thickness of the lens that the fixed lens group 321 and the moving lens group 322 individually have can be determined according to the optical design of the practice.

The variable optical element 323 is an electronically controlled optical element, and its optical characteristics can be changed by a predetermined control method, for example, adjusting an externally applied voltage value, a current value, or the like. In one embodiment, the variable optical element 323 is a liquid lens having a curved surface inside, and the curvature of the curved surface can be changed by the control module 31 by applying different voltage values or current values to adjust the adjustment. System equivalent focal length. The liquid lens system is a prior art and has various design and control modes, so it will not be repeated here.

The variable optical element 323 can be disposed on the fixed lens group 321 or on the moving lens group 322 according to actual needs. When the variable optical element 323 belongs to the fixed lens group 321 , it is fixed on the body to maintain the same position in the system; when the variable optical element 323 belongs to the moving lens group 322 , it is fixed to the driving mechanism At 320, along with the lens of the moving lens group 322, it is displaced along the optical axis.

In one embodiment, the fixed lens group 321 is formed by at least one lens and the variable optical element 323, and the moving lens group 322 includes at least two lenses. The fixed lens group 321 and the moving lens group 322 are configured according to the design mode of the optical compensation type zoom frame. Each lens of the fixed lens group 321 and the variable optical element 323 are coupled to each lens of the moving lens group 322. The shafts are spaced apart and together form at least three variable spacings.

In another embodiment, the fixed lens group 321 includes at least two lenses, and the moving lens 322 is formed by at least one lens and the variable optical element 323. Each lens of the moving lens group 322 and the variable optical element 323 are spaced apart from each of the lenses of the fixed lens group 321 along the optical axis, and collectively form at least three variable pitches.

In the optical compensation type zoom system, the moving lens and the fixed lens are arranged along the optical axis, and the adjacent moving lens and the fixed lens together form a variable pitch. In the optically compensated zoom system, the imaging position will vary with the zooming process and cannot be fixed on the intended imaging plane. However, during the imaging position change, one or several focal lengths will just fall on the intended imaging plane. This is just the amount of focal length that is expected to be the variable spacing of the intended imaging surface. Please refer to the fourth figure, which is a schematic diagram of the imaging position of an optically compensated zoom system, thereby illustrating the relationship between the variable pitch and the change of the imaging position.

In the fourth figure, an optically compensated zoom system 80 includes four lenses 811, 812, 821, 822, wherein the lenses 811, 812 are fixed lenses, and the lenses 821, 822 are moving lenses, and the arrangement of the fixed lens and the moving lens form three The variable pitches 831, 832, 833, the lengths of the variable pitches 831, 832, 833 vary with the displacement of the lenses 821, 822. The figure shows that during the movement of the lenses 821, 822, the imaging position also changes, and an imaging change trajectory J is formed. Since the system has three variable pitches 831, 832, and 833, the imaging variation trajectory J has three intersections with the predetermined imaging position O, which also means that during the displacement of the lenses 821 and 822, there are three positions for the focal length of the system to fall. The imaging surface is expected.

Since the variable optical element 323 has a limited correction range for the focal length of the system, and in the case where the system includes three or more variable pitches, the variable optical element 323 can be made to function to correct the imaging position.

In the control module 31, the controller 310 is a logic processing core, and is internally provided with components such as a processor and a memory, and operates according to a predetermined program logic according to the firmware stored therein. Briefly, the controller 310 can accept external control to generate signals based on control commands to control the operation of various peripheral units. The input unit 311 is an input interface that accepts external control and generates a zoom command to be transmitted to the controller 310.

The driving unit 312 is coupled between the controller 310 and the driving mechanism 320 for driving the driving mechanism 320 to move the moving lens group 322 along the optical axis. In a specific embodiment, the driving mechanism 320 is a movable body movable along the screw, and the moving lens group 322 is fixed, and the driving unit 312 includes a motor to indirectly or directly drive the screw to rotate, thereby driving the base. Moving along the screw, the components of the moving lens group 320 are displaced.

The modulation unit 313 is coupled between the controller 310 and the variable variable element 323, and changes the voltage value or current value applied to the variable optical element 323 according to the control of the controller 310 to control the optical characteristics of the variable. .

In the optical zoom system 30, the zoom function is achieved by changing the position of the moving lens group 322. At the same time as the focal length changes, the optical characteristics are changed by controlling the variable optical element 323 to compensate for variations in the imaging position. In general, the controller 310 is pre-established with a focal length magnification value and a corresponding displacement value of the moving lens group 322. When receiving the external zoom command, the controller 310 refers to the initial position of the moving lens group 322 according to the required focal length magnification value, generates a magnification change value, and further generates a driving signal, and controls the driving unit 312 to drive the driving mechanism 320 to move the lens. The group 322 is driven from the initial position to the position corresponding to the focus magnification value.

In addition, as the moving lens group 322 is displaced to various positions, it corresponds to the curvature of the surface of an optimal variable optical element 323. In a specific embodiment, the controller 310 stores a lookup table. The lookup table is pre-established with a compensation modulation value corresponding to each focus magnification value. The controller 310 searches the lookup table to obtain a focal length magnification value. The modulation value is compensated to generate a modulation signal, and the variable optical element 323 is controlled to change optical characteristics.

Next, please refer to the fifth figure, which is a schematic diagram of the configuration of the first embodiment of the optical zoom system disclosed in the present invention. In this embodiment, the optical zoom system 40 includes three lenses 441, 431, 442 arranged along the optical axis X, and an adjustable optical element 45. In this example, the lens 431 and the variable optical element 45 are attached to the fixed lens group, and the lenses 441, 442 are attached to the moving lens group. Each of the optical elements of the moving lens group is spaced from each of the optical elements of the fixed lens group and forms three variable pitches 461, 462, 463. During the zooming process, the control module 41 drives the lens 441, 442 to change the position by the driving mechanism 42 to change the equivalent focal length of the system, and simultaneously controls the variable optical element 45 to change the optical characteristics to compensate for the imaging position caused by the focal length change. variation.

Please refer to the sixth figure, which is a schematic diagram of the configuration of the second embodiment of the optical zoom system disclosed in the present invention. In this embodiment, the optical zoom system 50 includes four lenses 531, 532, 541, 542 and an adjustable optical element 55 arranged along the optical axis X. In this example, the lenses 531, 532 and the variable optical element 55 are attached to the fixed lens group, and the lenses 541, 542 are attached to the moving lens group. Each of the optical elements of the moving lens group is spaced apart from each of the optical elements of the fixed lens group and forms four variable pitches 561, 562, 563, 564. During the zooming process, the driving mechanism 52 is driven by the control module 51 to drive the lenses 541, 542 to change positions, and at the same time, the variable optical element 55 is controlled to change the optical characteristics.

In particular, in other embodiments, the variable optical element may also be disposed in the moving lens group, and the lens of the moving lens group is driven by the driving mechanism to be displaced along the optical axis X.

The optical zoom method of the present invention will be described below. Please refer to the seventh figure, which is a flow chart of the steps of the optical zooming method disclosed in the present invention. Please also refer to the third diagram and related diagram descriptions to refer to the system architecture and individual component features. As shown in the seventh figure, the optical zoom method includes the following steps: First, the controller 310 receives a zoom instruction from the input unit 311 (step S100); secondly, the controller 310 obtains a magnification change value according to the zoom instruction and A compensation modulation value is obtained (step S102); then, the controller 310 generates a driving signal according to the magnification change value, and drives the driving mechanism 320 to move along the optical axis via the driving unit 312 to drive the moving lens group 322 to change on the optical axis. Position (step S110); and, the controller 310 generates a modulation signal according to the compensation modulation value, and controls the variable optical element 323 to change the optical characteristic via the modulation unit 313 (step S120).

In step S102, the method further includes the following steps: First, the controller 310 converts the received zoom command to a focal length magnification value; subsequently, the controller 310 searches the lookup table according to the focal length magnification value to obtain the compensation corresponding to the focal length magnification value. The modulation value is obtained by the controller 310 according to the focal length magnification value and an initial magnification value corresponding to the lens position of the moving lens group 322 to obtain the magnification change value.

In one embodiment, the variably variable optical element 323 is a liquid lens having a curved structure inside, wherein in step S120, the optical property changed by the tunable optical element 323 is the curvature of the curved surface. .

As is apparent from the above examples, when the optical zoom system and method disclosed in the present invention are known, an optically compensated zoom frame is used to arrange the lenses of the fixed lens group and the lens of the moving lens group to control the common edge of the moving lens group. The optical axis moves to change the equivalent focal length of the system, and the optical position is changed by simultaneously controlling the variable optical element to compensate for the variation of the imaging position caused by the change of the focal length of the system. The optical zoom architecture of this case simplifies the mechanically compensated optical zoom architecture while maintaining good image quality.

However, the above description is only for the purpose of illustration and illustration of the embodiments of the present invention, and is not intended to limit the scope of the invention. Variations or modifications that may be readily conceived within the scope of the invention may be covered by the scope of the invention as defined in the following.

10, 80. . . Optically compensated zoom system

111, 112, 113, 121, 122, 211, 212, 213, 431, 441, 442, 531, 532, 541, 542, 811, 812, 821, 822. . . lens

20. . . Mechanically compensated zoom system

30, 40, 50. . . Optical zoom system

31, 41, 51. . . Control module

310. . . Controller

311. . . Input unit

312. . . Drive unit

313. . . Modulation unit

32. . . Optical mechanism module

320, 42, 52. . . Driving mechanism

321. . . Fixed lens group

322. . . Moving lens group

323, 45, 55. . . Adjustable optical component

461, 462, 463, 561, 562, 563, 564, 831, 832, 833. . . Variable spacing

A1, B1, B2, B3, C1, C2, C3. . . position

J. . . Imaging change trajectory

O. . . Predetermined imaging position

X. . . Optical axis

S100～S120. . . Step process

The first figure is a schematic diagram of the configuration of an optical compensation type zoom system of a prior art;

The second figure is a schematic diagram of the configuration and operation of a mechanically compensated zoom system of a prior art;

The third figure is a schematic diagram of the system architecture of the optical zoom system disclosed in the present invention;

The fourth figure is a schematic diagram of the imaging position of an optically compensated zoom system;

Figure 5 is a schematic view showing the configuration of the first embodiment of the optical zoom system disclosed in the present invention;

Figure 6 is a schematic view showing the configuration of a second embodiment of the optical zoom system disclosed in the present invention;

Figure 7 is a flow chart showing the steps of the optical zooming method disclosed in the present invention.

40. . . Optical zoom system

41. . . Control module

42. . . Driving mechanism

431, 441, 442. . . lens

45. . . Adjustable optical component

461, 462, 463. . . Variable spacing

X. . . Optical axis

Claims (10)

An optical zoom system comprising: an optical mechanism module defining an optical axis, the optical mechanism module having a driving mechanism movable along the optical axis; a fixed lens assembly including at least one lens An adjustable optical component is disposed on the optical mechanism module along the optical axis, wherein the adjustable optical component is a liquid lens, and the liquid lens has a curved surface, and the control module controls the The optical characteristic of the modulated optical element is the curvature of the curved surface; a moving lens group includes at least two lenses, and each lens of the moving lens group is fixed to the driving mechanism along the optical axis, and the fixed lens group The lens and the adjustable optical element are arranged at intervals; and a control module controls the driving mechanism to move along the optical axis according to a zooming instruction to change the position of the lens of the moving lens group, and control the Modulating the optical characteristics of the optical element; wherein each lens of the moving lens group and the adjustable optical element are arranged along the optical axis of each lens of the fixed lens group, Together they form at least three variable pitch, so that the zoom optical system during zooming, there will be one or several external falls exactly a focal length of the expected imaging plane, and a focal length of the number equal to the number of the variable pitch. The optical zoom system of claim 1, wherein the optical mechanism module further has a body, and the lens of the fixed lens group and the driving mechanism are fixed on the body. The optical zoom system of claim 1, wherein the control module comprises: a controller for receiving the zoom command, and generating a driving signal and a modulation signal according to the zooming command; a driving unit, Receiving the driving signal to drive the driving mechanism to move along the optical axis; and a modulation unit receiving the modulation signal to control optical characteristics of the variable optical element. The optical zoom system of claim 3, wherein the controller stores a lookup table, and a plurality of focal length magnification values and an individual corresponding plurality of compensation modulation values are pre-established, and the controller The zoom command is converted into a focus magnification value to search the lookup table to obtain a corresponding compensation modulation value, thereby generating the modulation signal. The optical zoom system of claim 4, wherein the controller is based on the focal length magnification value and a lens corresponding to the moving lens group The initial magnification value of the position is obtained by a magnification change value to generate the driving signal. An optical zoom system includes: an optical mechanism module defining an optical axis, the optical mechanism module having a driving mechanism, the driving mechanism is movable along the optical axis; and a fixed lens group including at least two lenses, The optical lens module is fixed along the optical axis; a moving lens group includes at least one lens and an adjustable optical component, and the lens of the moving lens group and the adjustable optical component are fixed along the optical axis The driving mechanism is spaced apart from the lens of the fixed lens group, wherein the adjustable optical component is a liquid lens, and the liquid lens has a curved surface, and the adjustable optical component controlled by the control module The optical characteristic is the curvature of the curved surface; and a control module controls the driving mechanism to move along the optical axis according to a zoom command to change the lens of the moving lens group and the variable optical element Positioning and controlling optical characteristics of the tunable optical element; wherein each lens of the moving lens group and the variably optical element and each lens edge of the fixed lens group The shafts are spaced apart and collectively form at least three variable pitches such that during the zooming process, one or more focal lengths fall just outside the intended imaging plane, and the number of focal lengths is equal to the variable pitch Quantity. The optical zoom system of claim 6, wherein the optical mechanism module further has a body, and the lens of the fixed lens group and the driving mechanism are fixed on the body. The optical zoom system of claim 6, wherein the control module comprises: a controller for receiving the zoom command, and generating a driving signal and a modulation signal according to the zooming instruction; a driving unit, Receiving the driving signal to drive the driving mechanism to move along the optical axis; and a modulation unit receiving the modulation signal to control optical characteristics of the variable optical element. The optical zoom system of claim 8, wherein the controller stores a lookup table, and a plurality of focal length magnification values and a plurality of corresponding compensation modulation values thereof are pre-established, and the controller The zoom command is converted into a focus magnification value to search the lookup table to obtain a corresponding compensation modulation value, thereby generating the modulation signal. The optical zoom system of claim 9, wherein the controller is based on the focal length magnification value and a corresponding one of the moving lens groups The initial magnification value of the mirror position is obtained by a magnification change value to generate the driving signal.