WO2019140782A1

WO2019140782A1 - Automatic focusing system, projection apparatus, automatic focusing method, and storage medium

Info

Publication number: WO2019140782A1
Application number: PCT/CN2018/080885
Authority: WO
Inventors: 熊再祥; 李屹
Original assignee: 深圳光峰科技股份有限公司
Priority date: 2018-01-18
Filing date: 2018-03-28
Publication date: 2019-07-25
Also published as: CN110058483A; CN110058483B

Abstract

The present invention provides an automatic focusing system, a projection apparatus, an automatic focusing method, and a storage medium. The automatic focusing system comprises: a spatial light modulator, a lens device, at least three distance measuring devices, and a control device; the spatial light modulator is provided with a modulation area for light modulation, and light rays emitted from the modulation area penetrate through the lens device to form a projection image; the distance measuring devices are provided at positions of the edge of the modulation area which are not on the same straight line; each distance measuring device is used for measuring a first distance, the first distance being the distance from a current position of the distance measuring device to a projection position corresponding to the distance measuring device on the projection image; the control device is electrically connected to the plurality of distance measuring devices, and is used for correspondingly controlling the lens device to adjust the projection focal length or correcting the projection image according to the plurality of first distances measured by the distance measuring devices and preset rules.

Description

Autofocus system, projection device, autofocus method, and storage medium

Technical field

The present invention relates to the field of projection technologies, and in particular, to an auto focus system, a projection device, an auto focus method, and a storage medium.

Background technique

At present, some projection devices are equipped with a distance measuring device on the outer ring of the lens, and the distance from the lens to the projection wall is measured by the distance measuring method. The auto-focusing system inside the projection device adjusts the corresponding angle of the focus ring outside the lens according to the distance, so that the projected image is clear. In addition, an image correction system inside the projection device corrects the projected image based on the distance.

However, when the projection wall is tilted, or because the distance of a part of the projected image cannot be detected, the autofocus and image correction methods of such a projection device may bring some errors, so that at least part of the projected image is not clear. Or the shape is irregular.

Summary of the invention

The present invention provides an autofocus system capable of realizing autofocus and projection image correction and improving focus accuracy, and an autofocus method thereof. The present invention also provides a projection device and a computer readable storage medium.

An autofocus system, the autofocus system comprising:

a spatial light modulator provided with a modulation area for performing light modulation;

a lens device, the light emitted from the modulation area passes through the lens device to form a projected image;

At least three ranging devices disposed at positions on the edge of the modulation region that are not on the same line, each ranging device for measuring a first distance, the first distance being the current position of the ranging device to the The distance from the projected position on the projected image; and

The control device is electrically connected to the at least three ranging devices, and is configured to adjust the projection focal length or the pair according to the first distance measured by the at least three ranging devices and the corresponding preset rule. The projected image is corrected.

A projection device comprising an autofocus system as described above.

An autofocus method is applied to an autofocus system, the autofocus system comprising a spatial light modulator and a lens device, the spatial light modulator being provided with a modulation region for performing light modulation, and the light emitted by the modulation region Forming a projected image through the lens device, the autofocus method comprising:

Obtaining at least three first distances, wherein the at least three first distances on the edge of the modulation area are not at a distance from at least three positions on the same straight line to the corresponding projected position on the projected image;

And correspondingly controlling the lens device to adjust a projection focal length or correct the projected image according to the at least three first distances and corresponding preset rules.

A projection apparatus comprising a processor for performing the steps of the autofocus method as described above when executing a computer program stored in a memory.

A computer readable storage medium having stored thereon a computer program that, when executed by a processor, implements the steps of the autofocus method as described above.

The first distance obtained in the autofocus system and the autofocus method provided by the present invention can take into account the entire projected image, the measurement of the projection distance of the projection device is more accurate, and the projection of the lens device is modulated according to the first distance. Focusing or correcting the projected image, thereby improving the accuracy of autofocus and image correction of the autofocus system, and the projected image emitted by the projection device applying the autofocus system and the autofocus method has a regular shape The definition is more uniform.

DRAWINGS

FIG. 1 is a schematic diagram of projection of a projection apparatus according to a preferred embodiment of the present invention.

2 is a schematic diagram of a main optical path of an autofocus system of the projection apparatus shown in FIG. 1.

3 is a schematic diagram of a main optical path in another embodiment of the autofocus system 230 shown in FIG. 2.

4 is a block diagram showing the structure of an autofocus system of the projection apparatus shown in FIG. 1.

FIG. 5 is a flow chart of an autofocus method of the projection apparatus shown in FIG. 1.

Main component symbol description

投影设备 Projection equipment	100100
本体 Ontology	110110
镜头装置 Lens device	120、220120, 220
调制区域 Modulation area	121121
角落corner	A'-D'A'-D'
透镜 lens	122122
出光透镜 Light exit lens	123123
调焦圈Focusing circle	129129
自动对焦系统 Autofocus system	130130
测距装置Distance measuring device	131131
控制装置 Control device	136136
驱动装置 Drive unit	137137
驱动芯片Driver chip	137a137a
电动机 electric motor	137b137b
平面flat	x、yx, y
角落corner	A-DA-D

The invention will be further illustrated by the following detailed description in conjunction with the accompanying drawings.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. The terminology used in the description of the present invention is for the purpose of describing particular embodiments and is not intended to limit the invention.

Please refer to FIG. 1 , FIG. 2 and FIG. 4 . FIG. 1 is a schematic diagram of projection of a projection apparatus 100 according to a preferred embodiment of the present invention. FIG. 2 is a schematic diagram of a main optical path of the autofocus system 130 of the projection apparatus 100 shown in FIG. 1 . 4 is a block diagram showing the structure of the autofocus system 130 of the projection apparatus 100 shown in FIG. 1. The projection device 100 includes a body 110 and an auto focus system 130.

Further, the autofocus system 130 includes a spatial light modulator, a lens device 120, at least three ranging devices 131, a control device 136, and a driving device 137. The control device 136 is electrically connected to the ranging device 131 and the driving device 137, respectively. The autofocus system 130 is configured to adjust the projection focal length or correct the projected image according to at least three first distances and corresponding preset rules measured by the at least three ranging devices 131.

Further, the spatial light modulator is disposed inside the body 110, and includes a modulation area 121 for performing light modulation. The light emitted by the modulation area 121 passes through the lens device 120 to form a projection image on the plane x. For clarity of presentation, only the modulation region 121 of the spatial light modulator is shown in the drawings, and other configurations of the spatial light modulator are omitted. In the present embodiment, the plane x is perpendicular to the optical axis of the lens device 120.

The modulation area 121 involved in the embodiment of the present invention may include a DMD (digital micro-mirror device) chip and other well-known light modulation chips in the art, such as LCD (Liquid Crystal Display), LCOS ( Single crystal liquid crystal projection, Liquid Crystal On Silico) chip.

As shown in FIG. 1 to FIG. 2, the lens device 120 is disposed at one end of the body 110, and at least one lens is disposed in the lens device 120. A lens 122 and a light exit lens 123 in the lens device 120 are shown in FIG. The light exit lens 123 is closest to the projected image. The light is reflected by the modulation area 121 and sequentially passes through the lens 122 and the light exit lens 123. It can be appreciated that in other embodiments, the lens device 120 can also include other lenses. The light emitted from the modulation area 121 sequentially passes through the lens in the lens device 120, and finally exits through the light exit lens 123. The final lens device 120 projects a magnified image of a quadrilateral. Any point on the surface of the modulation area 121 corresponds to a position in the projected image.

At least three ranging devices 131 are respectively disposed on positions on the edge of the modulation area 121 that are not on the same straight line, each ranging device 131 is configured to measure the first distance, and the first distance measured by each ranging device 131 is The distance from the current position to the projected position on the projected image. Since three planes not on the same line can determine a plane, at least three ranging devices 131 determine the position of the plane x and the distance of the modulation area 121 to the edge of the projected image.

The distance measuring device 131 includes one of an infrared distance device or a laser distance device. The distance measuring device 131 measures the first distance by using a phase method, that is, the distance measuring device 131 amplitude modulates the emitted light and measures the phase delay generated by the outgoing light rays once, and then converts the phase according to the wavelength of the emitted light. The distance represented by the delay. In one embodiment, the distance measuring device 131 measures the first distance by a pulse method, that is, the distance measuring device 131 reflects the emitted light through the plane x and is received by the distance measuring device 131, and the distance measuring device 131 records the light. Round trip time. The first distance is converted according to the wavelength of the emitted light. Additionally, the ranging device 131 can include a ranging sensor and a processing unit that processes the output signal of the sensor to obtain the first distance. In another embodiment, the ranging device 131 includes a ranging sensor, and the control device 136 processes the output signal of the ranging sensor to obtain the first distance.

The control device 136 can be disposed inside the lens device 120, and can be a single chip microcomputer, a central processing unit (CPU), or other general purpose processor, a digital signal processor (DSP), an application specific integrated circuit ( Application Specific Integrated Circuit (ASIC), Field-Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, etc. The general purpose processor may be a microprocessor or the processor or any conventional processor or the like.

The control device 136 is configured to adjust the projection focal length or correct the projection image according to the plurality of first distances and corresponding preset rules measured by the plurality of ranging devices 131.

In the case where the projection distance is determined, the resolution of the screen projected by the lens device 120 of the projection apparatus 100 moving to the projection focal length position is the highest.

In addition, the projection device 100 projects light onto a plane x for scattering light, so that the position and angle of the projection device 100 relative to the projection plane x and the distortion of the lens device 120 affect the projected image such that the projected image is displayed. For irregular quadrilaterals. The projection device 100 sets at least three ranging devices 131 on positions on the edge of the modulation region 121 that are not on the same straight line, and can determine whether the projected image occurs according to the measured at least three first distances and corresponding preset rules. Geometric distortions are performed to further perform corresponding correction steps for different types of geometric distortions. The most common geometric distortion is trapezoidal distortion, and the projection apparatus 100 can be self-contained with a vertical keystone correction function or a horizontal keystone correction function. It can be understood that the projection apparatus 100 can perform geometric correction by means of software correction or mechanical correction.

In one embodiment, control device 136 obtains an ideal distance that is one-to-one corresponding to the at least three first distances. The ideal distance is a first distance when the projected image is not distorted. And obtaining a deviation of each first distance according to each first distance, an ideal distance corresponding to each first distance, and a corresponding preset rule. Specifically, the corresponding preset rule is: taking a difference between the first distance and a corresponding ideal distance to obtain a deviation corresponding to the first distance. The control device 136 determines whether the deviation corresponding to each ideal distance is within the error range; if the deviation corresponding to the at least one ideal distance exceeds the error range, adjusting the region of the projected image corresponding to the at least one ideal distance After the size of each pixel, it is judged again whether the deviation is within the error range; if the deviation corresponding to each ideal distance is within the error range, the correction ends, if the deviation corresponding to at least one ideal distance exceeds the error The range is further adjusted to adjust the pixel size in the display area by the at least one ideal distance.

Preferably, it is assumed that each deviation and its corresponding ideal distance ratio are in the range of -0.05 to 0.05. In a preferred embodiment of the invention, the ratio of each deviation to its corresponding ideal distance is in the range of -0.03 to 0.03. In a preferred embodiment of the present invention, each deviation and its corresponding ideal distance ratio are in the range of -0.01 to 0.01, within which the projected image appears as a regular quadrilateral within the perceptible range of the human eye. . It can be understood that, in the most ideal case, each deviation value is 0, so that the projected image is rectangular, but the actual error precision is difficult to achieve, and can only be approximated so that each deviation is close to zero.

It can be understood that in the process of adjusting the pixel size, the first trend may be adjusted first, such as increasing the pixel size in the corresponding area. When the current trend is adjusted according to the first trend, the current deviation is compared with the previous deviation. If the current deviation is greater than the previous deviation, the size of the corresponding region pixel is adjusted according to the trend opposite to the first trend. In one embodiment, control device 136 adjusts the pixel size in the corresponding region based on the scale factor. For example, the pixel adjustment scale coefficient of the edge of the adjacent image in the corresponding area is large, and the pixel adjustment scale coefficient far from the edge of the image is small. It can be understood that the proportional coefficient and the pixel position can also satisfy the relationship of proportional or exponential, and no limitation is imposed herein.

It is to be understood that the method for correcting the projected image provided by the present invention is not limited to the above enumerated method, and may be a pair of the projected image that can be obtained according to the at least three first distances and other preset rules. The method of making corrections.

Further, the driving device 137 controls the lens device 120 to adjust the projection focal length according to an output signal of the control device 136.

The three first distances measured by the autofocus system 130 according to the embodiment of the present invention are the distances of at least three positions on the surface edge of the modulation area 121 that are not on the same straight line to the corresponding positions of the projected image, and the three first distances. The distance determines the plane in which the projected image is located, and the distance from the modulation area 121 to the edge of the projected image, so that the projection distance obtained by the autofocus system 130 can take into account the entire projected image, so that the measurement of the projection distance is more accurate. The autofocus accuracy of the autofocus system is improved, and the sharpness of the projected image emitted by the projection device 100 to which the autofocus system 130 is applied is more uniform. In addition, since the autofocus system 130 measures the distance from at least three positions on the surface edge of the modulation area 121 that are not on the same line to the corresponding position of the projected image, it can be determined whether the projected image is a regular graphic, if the projected image Instead of a regular graphic, the autofocus system 130 further corrects the projected image based on image edge information.

In this embodiment, the surface of the modulation area 121 has a rectangular shape and includes four corners A'-D'. A distance measuring device 131 is disposed at each corner of the modulation area 121. The projected image includes corners A-D that correspond one-to-one with the corners A'-D'. The first distances measured by the four distance measuring devices 131 are the distance from the corner A' to the corner A, the distance from the corner B' to the corner B, the distance from the corner C' to the corner C, and the distance from the corner D' to the corner D.

It can be understood that in other embodiments, the ranging device 131 can also be disposed in an edge region of the modulation region 121 other than the corners A'-D'. For example, the midpoint positions on at least three different edges of the modulation area 121 are respectively provided with a distance measuring device 131 to measure the distance from the three positions on the edge of the modulation area 121 that are not on the same straight line to the corresponding edge positions of the projected image.

Further, the distance between the modulation area 121 and the light exit lens 123 is a second distance, and the preset rule corresponding to the automatic focus system 130 controlling the lens device 120 to adjust the focal length is: taking each first distance and the second distance The difference between the two, and the multiple differences are averaged to obtain the projection distance. That is, the projection distance in the preferred embodiment of the present invention refers to the average distance from the lens device 120 to the edge of the projected image. It can be understood that, in an embodiment, the auto-focus system 130 controls the lens device 120 to adjust the focal length corresponding to the preset rule: taking an average of the at least three first distances, and taking the average value and The difference in the second distance results in the projected distance.

Please refer to FIG. 3 , which is a schematic diagram of a main optical path in another embodiment of the auto focus system 230 shown in FIG. 2 . In the present embodiment, the light emitted from the autofocus system 230 is transmitted to the plane y to form a projected image. The main difference from the preferred embodiment of the invention is that the plane y is not perpendicular to the optical axis of the lens device 220. The autofocus system 230 is the same as the auto focus system 130 and will not be described here. In this case, the auto-focus system 230 can also obtain a first distance from the modulation area to the edge of the projected image, the projection distance being able to take into account the entire projected image, so that the measurement of the projection distance is more accurate, and the The accuracy of the autofocus of the lens device is described, and the sharpness of the image is more uniform. In addition, the auto-focus system 230 can determine whether the projected image is a regular graphic according to a plurality of first distances and corresponding preset rules. If the projected image is not a regular graphic, the auto-focus system 230 further performs the The projected image is corrected.

As shown in FIG. 4, after the projection distance obtained by the distance measuring device 131 is used, the control device 136 outputs a pulse signal corresponding to the projection distance, and the number of pulses in the pulse signal corresponds to the projection distance. The driving device 137 includes a driving chip 137a and a motor 137b. The driving chip 137a outputs a corresponding driving signal according to the pulse signal, and the motor 137b receives the driving signal to rotate the focusing ring 129 of the lens device 120 by a corresponding angle. The focus ring 129 is disposed on the lens device 120 for adjusting the projection focal length of the lens device 120.

Specifically, when the projection distance is h1, the projection image needs to be adjusted to adjust the angle of rotation of the focus ring 129 to γ1, the motor 137b rotates by a corresponding angle γ1, and the driving signal provided by the driving chip 137a has a duration of t1. The number of pulses transmitted by the control device 136 to the driving chip 137a is m1. Where hmin<h1<hmax, hmin is the minimum value of the projection distance, and hmax is the maximum value of the projection distance.

When the projection distance is h2, the projection image needs to be adjusted to adjust the angle of rotation of the focus ring 129 to γ2, the motor 137b rotates by a corresponding angle γ2, and the driving signal provided by the driving chip 137a has a duration of t2, corresponding control The number of pulses transmitted by device 136 to drive chip 137a is m2. Where hmin<h2<hmax.

When the projection distance is h3, the projection image needs to be adjusted to adjust the angle of rotation of the focus ring to be γ3, the motor 137b rotates by a corresponding angle γ3, and the driving signal provided by the driving chip has a duration of t3, and the control device 136 The number of pulses sent by the driver chip is m3. Where hmin<h3<hmax.

Control device 136 establishes a relationship between the projection distance and the number of pulses based on the above data. When the control device 136 obtains the projection distance, acquires a pulse number corresponding to the projection distance according to the projection distance, outputs a pulse signal including the number of pulses, and the driving chip 137a supplies a driving signal to the motor 137b according to the number of pulses. The corresponding duration, so that the motor 137b rotates by a corresponding angle, thereby controlling the focus ring 129 to rotate by a corresponding angle.

In one embodiment, control device 136 obtains the number of pulses corresponding to the projected distance based on a look-up table. The control device 136 establishes a correspondence relationship between the projection distance and the number of pulses; when the projection device 100 projects, the control device 136 acquires the number of pulses corresponding to the projection distance according to the projection distance, and outputs a corresponding pulse signal. . It is to be understood that the autofocus system 130 can also include a storage device that can be used to store computer programs and/or modules and the correspondence between the projection distance and the number of pulses. The control device 136 implements the functions of the autofocus system 130 by operating or executing a computer program and/or module stored in the storage device, and reading a correspondence between the projection distance and the number of pulses. The storage device may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for an auto focus function, and the like; the storage data area may store the projection distance and the number of pulses Correspondence between the two. In addition, the storage device may include a high-speed random access storage device, and may also include a non-volatile storage device such as a hard disk, a memory, a plug-in hard disk, a smart memory card (SMC), and a secure digital (Secure Digital, SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid state storage device.

Please refer to FIG. 5, which is a flowchart of the autofocus method of the projection apparatus 100 shown in FIG. 1. The autofocus method is applied to an autofocus system 130. The autofocus system 130 includes a spatial light modulator, a lens device 120, at least three ranging devices 131, a control device 136, and a driving device 137, a control device 136 and a distance measuring device. The drive unit 137 is electrically connected. The spatial light modulator includes a modulation area 121 for performing light modulation, and the light emitted from the modulation area 121 passes through the lens device 120 to form a projected image.

The autofocus method includes:

S1: Obtaining at least three first distances, wherein the at least three positions on the edge of the modulation area 121 that are not on the same straight line respectively reach a distance from the corresponding projected position on the projected image.

In an embodiment of the invention, at least three first distances are measured by at least three ranging devices 131. Specifically, at least three ranging devices 131 are respectively disposed on positions on the edge of the modulation area 121 that are not on the same straight line. Each ranging device 131 is configured to measure the first distance, and the first distance measured by the ranging device 131 is Its current position is the distance from its projected position on the projected image. Since three planes not on the same line can determine a plane, at least three ranging devices 131 determine the position of the plane x and the distance of the modulation area 121 to the edge of the projected image.

In the two embodiments shown in FIG. 2 and FIG. 3, the first distance measured by the distance measuring device 131 is the distance from the modulation area 121 to the edge of the projected image, because three points that are not on the same line can Determining a plane, the at least three ranging devices 131 determine the position of the plane in which the projected image is located, and the distance from the modulation region 121 to the edge of the projected image.

S2: Adjust the projection focal length or correct the projected image according to the at least three first distances and corresponding preset rules.

The correspondingly controlling the lens device 120 to adjust the projection focal length according to the at least three first distances and corresponding preset rules includes the following steps:

S211: Obtain a projection distance between the lens device 120 and the projected image according to the plurality of first distances and corresponding preset rules.

In the process of adjusting the projection focal length of the autofocus system 130, the control device 136 is configured to obtain the projection distance according to the plurality of first distances and preset rules measured by the plurality of ranging devices 131. The lens device 120 may include a plurality of lenses, wherein the lens closest to the projected image is the light exit lens 123, and the distance between the modulation area 121 and the light exit lens 123 is a second distance.

The preset rule corresponding to the adjustment of the projection focal length by the autofocus system 130 is: taking a difference between each first distance and the second distance, and averaging the plurality of differences to obtain the projection distance. In another embodiment, the autofocus system 130 adjusts the preset rule corresponding to the projection focal length to: take an average of the plurality of first distances, and obtain a difference between the average value and the second distance. The projection distance.

Since the at least three first distances are the distances of the modulation region 121 to the edge of the projected image, the projection distance obtained by the autofocus method can take into account the entire projected image, so that the measurement of the projection distance is more accurate, and the The autofocus accuracy of the autofocus method is described, and the projection image emitted by the projection device 100 to which the autofocus method is applied is more uniform in definition.

S212: Control the lens device 120 to adjust the projection focal length according to the projection distance. These include:

S2121: The control device 136 establishes a correspondence relationship between the projection distance and the output pulse signal.

Control device 136 establishes a relationship between the projection distance and the number of pulses based on the above data. In one embodiment, control device 136 obtains the number of pulses corresponding to the projected distance based on a look-up table method.

S2122: The control device 136 outputs a corresponding pulse signal according to the projection distance.

S2123: The driving device 137 controls the lens device 120 to adjust the projection focal length according to the pulse signal.

The driving device 137 includes a driving chip 137a and a motor 137b. The driving chip 137a supplies the motor 137b with a duration corresponding to the driving signal according to the number of pulses, so that the motor 137b rotates by a corresponding angle, thereby controlling the focusing ring 129 to rotate by a corresponding angle.

In an embodiment, the correcting the projected image according to the at least three first distances and a corresponding preset rule comprises the following steps:

S221: Obtain an ideal distance corresponding to the at least three first distances one by one. The ideal distance is a first distance when the projected image is not distorted.

S222: Obtain a deviation of each first distance according to each first distance, an ideal distance corresponding to each first distance, and a corresponding preset rule.

The corresponding preset rule is: taking a difference between the first distance and its corresponding ideal distance to obtain a deviation corresponding to each ideal distance.

S223: determining whether the deviation corresponding to each ideal distance is within an error range;

If the deviation corresponding to the at least one ideal distance exceeds the error range, adjusting the size of each pixel in the region corresponding to the at least one ideal distance on the projected image, and then returning to step S223.

If the deviation corresponding to each ideal distance is within the error range, the correction ends.

Preferably, it is assumed that each deviation and its corresponding ideal distance ratio are in the range of -0.05 to 0.05. In a preferred embodiment of the invention, it is assumed that each deviation and its corresponding ideal distance ratio are in the range of -0.03 to 0.03. In a preferred embodiment of the present invention, it is assumed that each deviation and its corresponding ideal distance ratio are in the range of -0.01 to 0.01. Within the range, the projected image appears as a regular quadrilateral within the perceptible range of the human eye. It can be understood that, in the most ideal case, each deviation value is 0, so that the projected image is rectangular, but the actual error precision is difficult to achieve, and can only be approximated so that each deviation is close to zero.

It can be understood that in the process of adjusting the pixel size, the first trend may be adjusted first, such as increasing the pixel size in the corresponding area. After adjusting according to the first trend, returning to step S223, comparing the current deviation with the deviation obtained last time, if the current deviation is greater than the deviation obtained last time, adjusting the pixel of the corresponding region according to the trend opposite to the first trend size. In one embodiment, control device 136 adjusts the pixel size in the corresponding region based on the scale factor. For example, the pixel adjustment scale coefficient of the adjacent edge in the corresponding area is large, and the pixel adjustment scale coefficient far from the edge is small. It can be understood that the proportional coefficient and the distance pixel position can also satisfy the relationship of proportional or exponential, and no limitation is imposed here.

The three first distances in the autofocus method provided by the embodiment of the present invention are the distances of at least three positions on the surface edge of the modulation area 121 that are not on the same straight line to the corresponding positions of the projected image, and the three first distances are determined. The plane of the projection image and the distance from the modulation area 121 to the edge of the projection image enable the projection distance obtained by the autofocus system 130 to take into account the entire projection image, so that the measurement of the projection distance is more accurate and improved. The accuracy of the autofocus of the lens device, the sharpness of the image image is more uniform, and in addition, according to the distance from at least three positions on the surface edge of the modulation region 121 that are not on the same straight line to the corresponding position of the projected image, autofocus System 130 is also capable of correcting the projected image.

In one embodiment, the control device 136 performs the steps of the above-described autofocus method stored in the storage device. In another embodiment, projection device 100 includes a processor and a memory for performing the steps of the autofocus method stored in the memory. Projection device 100 may also include a light source system and other optical components known in the art.

The autofocus method, if implemented in the form of a software functional unit and sold or used as a standalone product, may be stored in a computer readable storage medium. Based on such understanding, the present invention implements all or part of the processes in the foregoing embodiments, and may also be completed by a computer program to instruct related hardware. The computer program may be stored in a computer readable storage medium. The steps of the various method embodiments described above may be implemented when the program is executed by the processor. Wherein, the computer program comprises computer program code, which may be in the form of source code, object code form, executable file or some intermediate form. The computer readable medium may include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a removable hard disk, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM). , random access memory (RAM, Random Access Memory), electrical carrier signals, telecommunications signals, and software distribution media. It should be noted that the content contained in the computer readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in a jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, computer readable media Does not include electrical carrier signals and telecommunication signals.

In the several embodiments/modes provided by the present invention, it should be understood that the method and apparatus may be implemented in other manners, and the apparatus embodiments described above are merely illustrative, The division of modules is just a division of logical functions, which can be implemented in another way.

It is apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the present embodiments are to be considered as illustrative and not restrictive, and the scope of the invention is defined by the appended claims instead All changes in the meaning and scope of equivalent elements are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim. In addition, it is to be understood that the word "comprising" does not exclude other elements or steps. The plurality of devices recited in the device claims can also be implemented by the same device or system in software or hardware. The first, second, etc. words are used to denote names and do not denote any particular order.

It should be noted that the above embodiments are only for explaining the technical solutions of the present invention and are not intended to be limiting, and the present invention will be described in detail with reference to the preferred embodiments. Modifications or equivalents are made without departing from the spirit and scope of the invention.

Claims

An autofocus system, characterized in that the autofocus system comprises:

a spatial light modulator provided with a modulation area for performing light modulation;

a lens device, the light emitted from the modulation area passes through the lens device to form a projected image;

At least three ranging devices disposed at positions on the edge of the modulation region that are not on the same line, each ranging device for measuring a first distance, the first distance being the current position of the ranging device to the The distance from the projected position on the projected image; and

a control device, electrically connected to the at least three ranging devices, for controlling the lens device to adjust a projection focal length according to the first distance measured by the at least three ranging devices and a corresponding preset rule The projected image is corrected.
The autofocus system according to claim 1, wherein said modulation area comprises four corners, said projection apparatus comprising four distance measuring means, each of which is provided with a distance measuring means.
The autofocus system according to claim 1, wherein the control device obtains a projection distance between the lens device and the projected image according to the first distance and a corresponding preset rule, and according to the The projection distance controls the lens device to adjust the projection focal length.
The autofocus system according to claim 3, wherein a lens closest to the projected image in the lens device is an exit lens, and a distance between the modulation region and the light exit lens is a second distance. The corresponding preset rule is: taking a difference between each first distance and the second distance, and averaging the plurality of differences to obtain the projection distance.
The autofocus system according to claim 1, wherein said autofocus system further comprises a driving device, said driving device controlling said lens device to adjust said projection focal length in accordance with an output signal of said control device.
The autofocus system according to claim 5, wherein said driving means comprises a driving chip and an electric motor, said control means outputs a pulse signal corresponding to said projection distance, said driving chip outputs according to said pulse signal And corresponding to the driving signal, the motor receives the driving signal and drives the focus ring of the lens device to rotate an angle corresponding to the projection distance.
The autofocus system of claim 1 wherein said at least three ranging devices comprise one or a combination of an infrared ranging device or a laser ranging device.
A projection apparatus comprising the autofocus system according to any one of claims 1-7.
An autofocus method is applied to an autofocus system, the autofocus system comprising a spatial light modulator and a lens device, the spatial light modulator being provided with a modulation region for performing light modulation, and the light emitted by the modulation region Forming a projected image through the lens device, wherein the autofocus method comprises:

Obtaining at least three first distances, wherein the at least three first distances on the edge of the modulation area are not at a distance from at least three positions on the same straight line to the corresponding projected position on the projected image;

And correspondingly controlling the lens device to adjust a projection focal length or correct the projected image according to the at least three first distances and corresponding preset rules.
The autofocus method according to claim 9, wherein the controlling the lens device to adjust the projection focal length according to the at least three first distances and the corresponding preset rule comprises:

Obtaining a projection distance between the lens device and the projected image according to the at least three first distances and a corresponding preset rule;

The projection device adjusts the projection focal length according to the projection distance.
The autofocus method according to claim 10, wherein a lens closest to the projected image in the lens device is an exit lens, and a distance between the modulation region and the light exit lens is a second distance. The corresponding preset rule is: taking a difference between each of the first distance and the second distance, and averaging the plurality of differences to obtain the projection distance.
A projection apparatus, characterized in that the projection apparatus comprises a processor for performing the steps of the autofocus method according to any one of claims 9-11 when the computer program stored in the memory is executed.
A computer readable storage medium having stored thereon a computer program, wherein the computer program is executed by a processor to implement the steps of the autofocus method of any of claims 9-11.