CN110058483B

CN110058483B - Automatic focusing system, projection equipment, automatic focusing method and storage medium

Info

Publication number: CN110058483B
Application number: CN201810049955.4A
Authority: CN
Inventors: 熊再祥; 李屹
Original assignee: Appotronics Corp Ltd
Current assignee: Shenzhen Appotronics Corp Ltd
Priority date: 2018-01-18
Filing date: 2018-01-18
Publication date: 2022-06-10
Anticipated expiration: 2038-01-18
Also published as: WO2019140782A1; CN110058483A

Abstract

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

Description

Automatic focusing system, projection equipment, automatic focusing method and storage medium

Technical Field

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

Background

At present, a distance measuring device is arranged on the outer ring of a lens of part of projection equipment, and the distance from the lens to a projection wall surface is measured by a distance measuring method. And an automatic focusing system inside the projection equipment adjusts the corresponding angle of the focusing 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 according to the distance.

However, when the projection wall surface is inclined or the distance of a partial area of the projection screen cannot be detected, some errors may be caused by the automatic focusing and image correction method of the projection apparatus, so that at least a partial area of the projection image is unclear or irregular in shape.

Disclosure of Invention

The invention provides an automatic focusing system and an automatic focusing method thereof, which can realize automatic focusing and projection image correction and improve focusing accuracy, and also provides projection equipment and a computer readable storage medium.

An autofocus system, comprising:

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

the light rays emitted from the modulation region pass through the lens device to form a projection image;

The at least three distance measuring devices are arranged at positions, which are not on the same straight line, of the edge of the modulation area, and each distance measuring device is used for measuring a first distance, wherein the first distance is the distance from the current position of the distance measuring device to the projection position corresponding to the current position on the projection image; and

and the control device is electrically connected with the at least three distance measuring devices and used for correspondingly controlling the lens device to adjust the projection focal length or correct the projection image according to the first distances measured by the at least three distance measuring devices and the corresponding preset rules.

A projection device comprising an autofocus system as described above.

An automatic focusing method is applied to an automatic focusing system, the automatic focusing system comprises a spatial light modulator and a lens device, the spatial light modulator is provided with a modulation area for carrying out light modulation, and light rays emitted from the modulation area penetrate through the lens device to form a projected image, and the automatic focusing method comprises the following steps:

obtaining at least three first distances, wherein the at least three first distances are distances from at least three positions, which are not on the same straight line, on the edge of the modulation region to projection positions corresponding to the positions on the projection image respectively;

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

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

A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the autofocus method as described above.

The automatic focusing system and the automatic focusing method provided by the invention have the advantages that the first distance obtained in the automatic focusing system and the automatic focusing method can take the whole projected image into consideration, the measurement of the projection distance of the projection equipment is more accurate, and the projection focal length of the lens device is modulated or the projected image is corrected according to the first distance, so that the automatic focusing accuracy and the image correction accuracy of the automatic focusing system are improved, the projected image emitted by the projection equipment using the automatic focusing system and the automatic focusing method is regular in shape, and the definition is more uniform.

Drawings

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

Fig. 2 is a schematic diagram of a main optical path of an auto-focusing system of the projection apparatus shown in fig. 1.

Fig. 3 is a schematic diagram of a main optical path of another embodiment of the auto-focusing system 230 shown in fig. 2.

Fig. 4 is a block diagram of an auto-focusing system of the projection apparatus shown in fig. 1.

Fig. 5 is a flowchart of an auto-focusing method of the projection apparatus shown in fig. 1.

Description of the main elements

Projection device	100
		Body	110
Lens device	120、220
		Modulation region	121
Corner	A'-D'
		Lens and its manufacturing method	122
Light-emitting lens	123
		Focusing ring	129
Automatic focusing system	130
		Distance measuring device	131
Control device	136
		Drive device	137
Driving chip	137a
		Electric motor	137b
Plane surface	x、y
		Corner	A-D

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a detailed description of the present invention will be given below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention, and the described embodiments are merely a subset of the embodiments of the present invention, rather than a complete embodiment. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Unless defined otherwise, 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. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Referring to fig. 1, fig. 2 and fig. 4, fig. 1 is a schematic projection diagram of a projection apparatus 100 according to a preferred embodiment of the present invention, fig. 2 is a schematic main light path diagram of an auto-focusing system 130 of the projection apparatus 100 shown in fig. 1, and fig. 4 is a block diagram of the auto-focusing system 130 of the projection apparatus 100 shown in fig. 1. The projection apparatus 100 includes a body 110 and an autofocus system 130.

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

Further, the spatial light modulator is disposed inside the body 110, and includes a modulation region 121 for performing light modulation, and light emitted from the modulation region 121 passes through the lens device 120 to form a projection image on the plane x. For clarity, only the modulation region 121 of the spatial light modulator is shown in the drawings, and other structures 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 region 121 according to the embodiment of the present invention may include: DMD (digital micro-reflector) chips and other light modulation chips known in the art, such as LCD (Liquid Crystal Display), LCOS (Liquid Crystal On silicon) chips, etc.

As shown in fig. 1-2, 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. Fig. 2 shows the lens 122 and the light exit lens 123 in the lens device 120. Wherein, the light-emitting lens 123 is closest to the projection image. The light is reflected by the modulation region 121 and then sequentially emitted through the lens 122 and the light-emitting lens 123. It is understood that in other embodiments, the lens device 120 may also include other lenses. The light emitted from the modulation region 121 sequentially passes through the lenses in the lens device 120, and finally exits through the light-emitting lens 123. The final lens unit 120 projects a magnified quadrangular image. Any point on the surface of the modulated area 121 corresponds to a location in the projected image.

At least three distance measuring devices 131 are respectively arranged at positions on the edge of the modulation region 121, which are not on the same straight line, each distance measuring device 131 is used for measuring a first distance, and the first distance measured by each distance measuring device 131 is the distance from the current position to the projection position corresponding to the current position on the projection image. Since three points that are not collinear can determine a plane, at least three distance measuring devices 131 determine the position of the plane x, and the distance of the modulation region 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 performs amplitude modulation on the emitted light, measures the phase delay generated when the emitted light goes back and forth once, and converts the distance represented by the phase delay according to the wavelength of the emitted light. In one embodiment, the distance measuring device 131 measures the first distance by using a pulse method, that is, the distance measuring device 131 reflects the emitted light beam on the plane x and then receives the light beam by the distance measuring device 131, and the distance measuring device 131 records the round trip time of the light beam. And converting the first distance according to the wavelength of the emergent ray. In addition, the distance measuring device 131 may include a distance measuring sensor and a processing unit, wherein the processing unit processes an output signal of the sensor to obtain the first distance. In another embodiment, the distance measuring device 131 comprises a distance measuring sensor, and the control device 136 processes an output signal of the distance measuring sensor to obtain the first distance.

The control device 136 may be disposed inside the lens device 120, and may be a single chip, a Central Processing Unit (CPU), another general-purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or another Programmable logic device, a discrete Gate or transistor logic device, a discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The control device 136 is configured to correspondingly control the lens device 120 to adjust the projection focal length or correct the projection image according to a plurality of first distances measured by the plurality of distance measuring devices 131 and corresponding preset rules.

When the projection distance is determined, the sharpness of the picture projected by moving the lens device 120 of the projection apparatus 100 to the projection focal length position is the highest.

In addition, the projection apparatus 100 projects light on the plane x for scattering light, and thus the position and angle of the projection apparatus 100 with respect to the projection plane x and the distortion of the lens device 120 affect the projection image, so that the projection image is displayed as an irregular quadrangle. The projection apparatus 100 sets at least three distance measuring devices 131 at positions on the edge of the modulation region 121 that are not on the same straight line, and can determine whether the projected image has geometric distortion according to the measured at least three first distances and corresponding preset rules, thereby further performing corresponding correction steps on different types of geometric distortion. The most common geometric distortion is keystone distortion, and projection device 100 may have its own vertical keystone correction capability, or may also have its own horizontal keystone correction capability. It is to be appreciated that projection device 100 may employ software correction or mechanical correction to perform the geometric correction.

In one embodiment, the control device 136 obtains the ideal distances in one-to-one correspondence with the at least three first distances. The ideal distance is a first distance when the projected image is not distorted. And obtaining the deviation of each first distance according to each first distance, the ideal distance corresponding to each first distance and the corresponding preset rule. Specifically, the corresponding preset rule is as follows: and obtaining the difference value between the first distance and the corresponding ideal distance to obtain the 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 at least one ideal distance exceeds the error range, adjusting the size of each pixel in the area corresponding to the at least one ideal distance on the projected image, and then judging whether the deviation is in the error range again; and if the deviation corresponding to each ideal distance is within the error range, finishing the correction, and if the deviation corresponding to at least one ideal distance exceeds the error range, further adjusting the size of the pixels in the display area corresponding to the at least one ideal distance.

Preferably, the ratio of each deviation to the corresponding ideal distance is set to be in the range of-0.05 to 0.05. In a preferred embodiment of the present invention, the ideal distance ratio of each deviation to its corresponding deviation is set to be in the range of-0.03 to 0.03. In a preferred embodiment of the present invention, a ratio of each deviation to its corresponding ideal distance is in a range of-0.01 to 0.01, within which range the projected image appears as a regular quadrangle within a range perceivable by the human eye. It will be appreciated that in the most ideal case, each deviation value is 0, making the projected image rectangular, but the actual error accuracy is difficult to do so, and only approaches to make each deviation close to 0.

It will be appreciated that in adjusting the pixel size, the pixel size in the corresponding region may be adjusted first according to a first trend, such as increasing the pixel size. And after adjustment according to the first trend, comparing the current deviation with the deviation obtained last time, and if the current deviation is greater than the deviation obtained last time, adjusting the size of the pixel of the corresponding area according to the trend opposite to the first trend. In one embodiment, the control device 136 adjusts the size of the pixels in the corresponding region according to the scaling factor. For example, the scaling factor for adjusting pixels near the edge of the image in the corresponding region is large, and the scaling factor for adjusting pixels far away from the edge of the image is small. It is understood that the relationship between the scaling factor and the pixel position may also satisfy a direct proportion or an exponential relation, and is not limited herein.

It is to be understood that the method for correcting the projection image provided by the present invention is not limited to the above-listed method, and may be a method for correcting the projection image that can be obtained according to the at least three first distances and other preset rules.

Further, the driving device 137 controls the lens device 120 to adjust the projection focal length according to the 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 distances from at least three positions on the edge of the surface of the modulation region 121 that are not on the same straight line to the corresponding positions of the projected image, and the three first distances determine the plane where the projected image is located and the distance from the modulation region 121 to the edge of the projected image, so that the projection distance obtained by the autofocus system 130 can take the whole projected image into consideration, and thus the measurement of the projection distance is more accurate, the autofocus accuracy of the autofocus system is improved, and the definition of the projected image emitted by the projection apparatus 100 using the autofocus system 130 is more uniform. In addition, since the autofocus system 130 measures the distances from at least three positions on the edge of the surface of the modulation region 121 that are not on the same straight line to the corresponding positions of the projected image, it is possible to determine whether the projected image is a regular pattern, and if the projected image is not a regular pattern, the autofocus system 130 further corrects the projected image based on the image edge information.

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

It is understood that in other embodiments, the distance measuring device 131 may be disposed at an edge region of the modulation region 121 other than the corners a '-D'. For example, a distance measuring device 131 is respectively disposed at the midpoint positions of at least three different edges of the modulation region 121, so as to measure the distances from three positions on the edge of the modulation region 121, which are not on the same straight line, to the corresponding edge positions of the projection image.

Further, the distance between the modulation region 121 and the light-emitting lens 123 is a second distance, and the preset rule corresponding to when the auto-focusing system 130 controls the lens device 120 to adjust the focal length is as follows: and taking the difference between each first distance and the second distance, and averaging a plurality of differences 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 is understood that, in one embodiment, the preset rule corresponding to the auto-focus system 130 controlling the lens device 120 to adjust the focal length is: and taking the average value of the at least three first distances, and taking the difference value of the average value and the second distance to obtain the projection distance.

Please refer to fig. 3, which is a schematic diagram of a main optical path of the auto-focusing system 230 according to another embodiment shown in fig. 2. In this embodiment, the light emitted from the autofocus system 230 is transmitted to the plane y to form a projected image. The main difference with the preferred embodiment of the present 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 autofocus system 130 and will not be described herein. In this case, the auto-focusing system 230 can also obtain the first distance from the modulation region to the edge of the projected image, and the projection distance can take into account the whole projected image, so that the measurement of the projection distance is more accurate, the auto-focusing accuracy of the lens device is improved, and the definition of the image frame is more uniform. In addition, the auto-focusing system 230 can determine whether the projected image is a regular image according to the plurality of first distances and the corresponding preset rules, and if the projected image is not a regular image, the auto-focusing system 230 further corrects the projected image according to the image edge information.

As shown in fig. 4, the control device 136 outputs a pulse signal corresponding to the projection distance after using the projection distance obtained by the distance measuring device 131, 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 drive the focus adjustment ring 129 of the lens device 120 to rotate by a corresponding angle. The focus adjusting ring 129 is disposed on the lens device 120 and is used for adjusting a projection focal length of the lens device 120.

Specifically, when the projection distance is h1, the focus adjustment ring 129 needs to be adjusted to rotate by a corresponding angle γ 1 to make the projected image clear, the motor 137b rotates by a corresponding angle γ 1, the duration of the driving signal provided by the driving chip 137a is t1, and the number of pulses sent by the control device 136 to the driving chip 137a is m 1. Wherein 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 focus adjustment ring 129 needs to be adjusted to rotate by a corresponding angle γ 2, the motor 137b rotates by a corresponding angle γ 2, the duration of the driving signal provided by the driving chip 137a is t2, and the number of pulses sent to the driving chip 137a by the corresponding control device 136 is m 2. Wherein hmin < h2< hmax.

When the projection distance is h3, the focus adjustment ring needs to be adjusted to rotate by a corresponding angle γ 3 for the projected image to be clear, the motor 137b rotates by the corresponding angle γ 3, the duration of the driving signal provided by the driving chip is t3, and the number of pulses sent to the driving chip by the control device 136 is m 3. Wherein hmin < h3< hmax.

The 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, the pulse number corresponding to the projection distance is obtained according to the projection distance, a pulse signal including the pulse number is output, and the driving chip 137a provides the duration corresponding to the driving signal to the motor 137b according to the pulse number, so that the motor 137b rotates by a corresponding angle, and the focusing ring 129 is controlled to rotate by a corresponding angle.

In one embodiment, the control device 136 obtains the number of pulses corresponding to the projection distance according to a table lookup method. The control device 136 establishes a correspondence between the projection distance and the number of pulses; when the projection apparatus 100 projects, the control device 136 obtains the number of pulses corresponding to the projection distance according to the projection distance, and outputs a corresponding pulse signal. It will be appreciated that the autofocus system 130 may also include a memory device operable to store a computer program and/or module and the correspondence between the projection distance and the number of pulses. The control device 136 implements the function of the autofocus system 130 by running or executing a computer program and/or module stored in the memory device, and reading the correspondence between the projection distance and the number of pulses. The storage device mainly comprises a storage program area and a storage data area, wherein the storage program area can store an operating system, an application program required by an automatic focusing function and the like; the storage data area may store a correspondence between the projection distance and the number of pulses, or the like. In addition, the storage device may include a high speed random access memory device, and may also include a non-volatile storage device, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one piece of magnetic disk storage, a Flash memory device, or other volatile solid state storage device.

Please refer to fig. 5, which is a flowchart illustrating an auto-focusing method of the projection apparatus 100 shown in fig. 1. The auto-focusing method is applied to an auto-focusing system 130, the auto-focusing system 130 includes a spatial light modulator, a lens device 120, at least three distance measuring devices 131, a control device 136 and a driving device 137, and the control device 136 is electrically connected with the distance measuring devices and the driving device 137. The spatial light modulator includes a modulation region 121 for performing light modulation, and light emitted from the modulation region 121 passes through the lens device 120 to form a projection image.

The automatic focusing method comprises the following steps:

s1: at least three first distances are obtained, and the at least three first distances are distances from at least three positions on the edge of the modulation region 121, which are not on the same straight line, to the corresponding projection positions on the projection image respectively.

In the embodiment of the present invention, at least three first distances are measured by at least three distance measuring devices 131. Specifically, at least three distance measuring devices 131 are respectively arranged at positions on the edge of the modulation region 121, which are not on the same straight line, each distance measuring device 131 is used for measuring a first distance, and the first distance measured by the distance measuring device 131 is the distance from the current position to the projection position corresponding to the current position on the projection image. Since three points that are not collinear can determine a plane, at least three distance measuring devices 131 determine the position of the plane x, and the distance of the modulation region 121 to the edge of the projected image.

In both embodiments shown in fig. 2 and fig. 3, the first distances measured by the distance measuring devices 131 are distances from the modulation region 121 to the edge of the projected image, and since three points that are not on the same straight line can determine a plane, at least three distance measuring devices 131 determine the position of the plane where the projected image is located and the distance from the modulation region 121 to the edge of the projected image.

S2: and adjusting the projection focal length or correcting the projection 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 the corresponding preset rules includes the following steps:

s211: and obtaining a projection distance between the lens device 120 and the projection image according to the plurality of first distances and corresponding preset rules.

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

The preset rule corresponding to the automatic focusing system 130 adjusting the projection focal length is: and taking the difference between each first distance and the second distance, and averaging a plurality of differences to obtain the projection distance. In another embodiment, the preset rule corresponding to the automatic focusing system 130 adjusting the projection focal length is: and taking the average value of the plurality of first distances, and taking the difference value between the average value and the second distance to obtain the projection distance.

Since the at least three first distances are distances from the modulation region 121 to the edge of the projected image, the projection distance obtained by the automatic focusing method can take the whole projected image into consideration, so that the measurement of the projection distance is more accurate, the automatic focusing accuracy of the automatic focusing method is improved, and the definition of the projected image emitted by the projection device 100 using the automatic focusing method is more uniform.

S212: and correspondingly controlling the lens device 120 to adjust the projection focal length according to the projection distance. Which comprises the following steps:

s2121: the control device 136 establishes a correspondence between the projection distance and the output pulse signal.

Specifically, when the projection distance is h1, the focus adjustment ring 129 needs to be adjusted to rotate by a corresponding angle γ 1 to make the projected image clear, the motor 137b rotates by a corresponding angle γ 1, the duration of the driving signal provided by the driving chip 137a is t1, and the number of pulses sent by the control device 136 to the driving chip 137a is m 1. Wherein hmin < h1< hmax, hmin being the minimum of the projection distance, hmax being the maximum of the projection distance.

The control device 136 establishes a relationship between the projection distance and the number of pulses based on the above data. In one embodiment, the control device 136 obtains the number of pulses corresponding to the projection distance according to a table lookup method.

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

S2123: the driving device 137 correspondingly 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 137 b. The driving chip 137a provides the motor 137b with the duration corresponding to the driving signal according to the number of pulses, so that the motor 137b rotates by a corresponding angle, and further controls the focus control ring 129 to rotate by a corresponding angle.

In one embodiment, the correcting the projection image according to the at least three first distances and corresponding preset rules includes:

S221: and obtaining ideal distances corresponding to the at least three first distances in a one-to-one mode. The ideal distance is a first distance at which the projected image is not distorted.

S222: and obtaining the deviation of each first distance according to each first distance, the ideal distance corresponding to each first distance and the corresponding preset rule.

The corresponding preset rule is as follows: and obtaining the difference between the first distance and the corresponding ideal distance to obtain the deviation corresponding to each ideal distance.

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

if the deviation corresponding to at least one of the ideal distances exceeds the error range, the size of each pixel in the area corresponding to the at least one ideal distance on the projection image is adjusted, and then the process returns to step S223.

And if the deviation corresponding to each ideal distance is within the error range, finishing the correction.

Preferably, the ratio of each deviation to the corresponding ideal distance is set to be in the range of-0.05 to 0.05. In a preferred embodiment of the present invention, the ideal distance ratio of each deviation to its corresponding deviation is set in the range of-0.03 to 0.03. In a preferred embodiment of the present invention, the ideal distance ratio of each deviation to its corresponding deviation is set in the range of-0.01 to 0.01. Within the range, the projected image appears as a regular quadrangle within a range perceivable by the human eye. It will be appreciated that in the most ideal case, each deviation value is 0, so that the projected image is rectangular, but the actual error accuracy is difficult to do so, and only approaches that each deviation approaches 0.

It will be appreciated that in adjusting the pixel size, the pixel size in the corresponding region may be adjusted first according to a first trend, such as increasing the pixel size. And returning to step S223 after the adjustment according to the first trend, comparing the current deviation with the deviation obtained last time, and if the current deviation is greater than the deviation obtained last time, adjusting the size of the pixel in the corresponding area according to a trend opposite to the first trend. In one embodiment, the control device 136 adjusts the size of the pixels in the corresponding region according to the scaling factor. For example, the scaling factor for the pixels near the edge in the corresponding region is large, and the scaling factor for the pixels far from the edge is small. It is understood that the relationship between the scaling factor and the distance pixel position may also satisfy a direct proportion or an exponential relationship, and is not limited herein.

In the auto-focusing method provided in the embodiment of the present invention, the three first distances are distances from at least three positions on the edge of the surface of the modulation region 121 that are not on the same straight line to corresponding positions of the projected image, and the three first distances determine a plane where the projected image is located and a distance from the modulation region 121 to the edge of the projected image, so that the projection distance obtained by the auto-focusing system 130 can take the whole projected image into consideration, thereby measuring the projection distance more accurately, improving the accuracy of auto-focusing of the lens apparatus, and making the definition of the image more uniform, and in addition, the auto-focusing system 130 can also correct the projected image according to the distances from at least three positions on the edge of the surface of the modulation region 121 that are not on the same straight line to corresponding positions of the projected image.

In one embodiment, the control device 136 executes the steps of the above-described auto-focusing method stored in the storage device. In another embodiment, the projection device 100 includes a processor and a memory, the processor being configured to execute the steps of the auto-focus 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 stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.

In the several embodiments/modes provided by the present invention, it should be understood that the method and apparatus may also be implemented in other modes, the above-described apparatus embodiments are only illustrative, the division of the module is only one logic function division, and there may be other division modes when implemented.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it will be obvious that the term "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. Several of the means recited in the apparatus claims may also be embodied by one and the same means or system in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

Finally, it should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the same, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An auto-focus system, comprising:

the light emitted by the modulation region passes through the lens device to form a projection image;

the distance measuring devices are arranged at positions, which are not on the same straight line, of the edge of the modulation area, and each distance measuring device is used for measuring a first distance, wherein the first distance is the distance from the current position of the distance measuring device to the projection position corresponding to the distance measuring device on the projection image; and

a control device electrically connected with the at least three distance measuring devices and used for correspondingly controlling the lens device to adjust the projection focal length or correct the projection image according to the first distance measured by the at least three distance measuring devices and the corresponding preset rule, wherein,

Any point on the surface of the modulation region corresponds to a position in the projected image;

wherein, the preset rule is as follows: obtaining a difference value between the first distance and the corresponding ideal distance to obtain a deviation corresponding to the first distance, wherein the step of correcting the projection image comprises the following steps: judging whether the deviation of the first distance corresponding to each ideal distance is within an error range; and if the deviation of the first distance corresponding to at least one ideal distance exceeds the error range, adjusting the size of each pixel in the area corresponding to the at least one ideal distance on the projection image.

2. The autofocus system of claim 1, wherein the modulated area comprises four corners, and wherein the autofocus system comprises four distance measuring devices, one distance measuring device disposed at each corner.

3. The auto-focusing system of 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 predetermined rule, and controls the lens device to adjust the projection focal length according to the projection distance.

4. The auto-focusing system of claim 3, wherein a lens of the lens device closest to the projected image is an exit lens, a distance between the modulation region and the exit lens is a second distance, and the corresponding predetermined rule is: and taking the difference between each first distance and the second distance, and averaging a plurality of differences to obtain the projection distance.

5. The autofocus system of claim 4 further comprising a driving device, wherein the driving device controls the lens device to adjust the projection focal length according to an output signal of the control device.

6. The auto-focusing system of claim 5, wherein the driving device comprises a driving chip and a motor, the control device outputs a pulse signal corresponding to the projection distance, the driving chip outputs a corresponding driving signal according to the pulse signal, and the motor receives the driving signal and drives the focus adjustment ring of the lens device to rotate by an angle corresponding to the projection distance.

7. The autofocus system of claim 1, wherein the at least three distance measuring devices comprise one or a combination of infrared distance measuring devices or laser distance measuring devices.

8. A projection device comprising the autofocus system of any of claims 1-7.

9. An automatic focusing method is applied to an automatic focusing system, the automatic focusing system comprises a spatial light modulator and a lens device, the spatial light modulator is provided with a modulation area for carrying out light modulation, light rays emitted from the modulation area penetrate through the lens device to form a projected image, any point on the surface of the modulation area corresponds to a position in the projected image, and the automatic focusing method is characterized by comprising the following steps of:

Obtaining at least three first distances, wherein the at least three first distances are distances from at least three positions on the edge of the modulation region, which are not on the same straight line, to projection positions corresponding to the positions on the projection image, respectively;

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

wherein the preset rule is as follows: obtaining a difference value between the first distance and the corresponding ideal distance to obtain a deviation corresponding to the first distance, wherein the step of correcting the projection image comprises the following steps: judging whether the deviation of the first distance corresponding to each ideal distance is within an error range; and if the deviation of the first distance corresponding to at least one ideal distance exceeds the error range, adjusting the size of each pixel in the area corresponding to the at least one ideal distance on the projection image.

10. The auto-focusing method of claim 9, wherein the controlling the lens device to adjust the projection focal length according to the at least three first distances and corresponding predetermined rules comprises:

obtaining a projection distance between the lens device and the projection image according to the at least three first distances and corresponding preset rules;

And correspondingly controlling the lens device to adjust the projection focal length according to the projection distance.

11. The auto-focusing method of claim 10, wherein a lens of the lens device closest to the projected image is an exit lens, a distance between the modulation region and the exit lens is a second distance, and the corresponding predetermined rule is: and taking the difference value between each first distance and each second distance, and averaging a plurality of difference values to obtain the projection distance.

12. A projection device, characterized in that the projection device comprises a processor for implementing the steps of the auto-focusing method as claimed in any one of claims 9-11 when executing a computer program stored in a memory.

13. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the autofocus method as claimed in any of claims 9 to 11.