CN113301314A

CN113301314A - Focusing method, projector, imaging apparatus, and storage medium

Info

Publication number: CN113301314A
Application number: CN202010538338.8A
Authority: CN
Inventors: 李干; 任万喜
Original assignee: Alibaba Group Holding Ltd
Current assignee: Alibaba Group Holding Ltd
Priority date: 2020-06-12
Filing date: 2020-06-12
Publication date: 2021-08-24
Anticipated expiration: 2040-06-12
Also published as: CN113301314B

Abstract

The embodiment of the invention provides a focusing method, a projector, imaging equipment and a storage medium. The focusing method is applied to a projector, and the method comprises the following steps: determining a target object distance interval which is in accordance with the measurement distance between the target and the projection target in the plurality of lens object distance intervals; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and focusing the projection target based on the target image distance interval. The target image distance interval is determined according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals, so that the focusing precision of the projection target is ensured based on the target image distance interval.

Description

Focusing method, projector, imaging apparatus, and storage medium

Technical Field

The embodiment of the invention relates to the technical field of communication, in particular to a focusing method, a projector, imaging equipment and a storage medium.

Background

Generally, the sharpest point of the image is also the point of greatest contrast. For a camera or a projector, a motor drives a lens, the focal points are changed along an axis pointing to a shot object, an image is obtained at each focal point, similarly to point-by-point scanning, the image obtained at each focal point is digitized, the digitized image is actually an integer matrix and is transmitted to an image processor, then the contrast value is calculated, the lens is driven, the focal point is placed at the focal point with the maximum contrast value, the correct focal point is obtained, whether the focal point is focused or not is determined according to the maximum contrast value, and focusing is finished.

Also, with the auto-focus technique of the projector in the related art, the sharpness of a series of key points is collected by the image sensor, the clearest point is found, and then the motor is driven to that position. However, the image sensor collects images and calculates definition, which results in slower focusing speed and poorer experience.

Disclosure of Invention

In view of the above, embodiments of the present invention provide a focusing method, a projector, an imaging apparatus, and a storage medium to solve or alleviate the above problems.

According to a first aspect of the embodiments of the present invention, there is provided a focusing method applied to a projector, including: determining a target object distance interval which is in accordance with the measurement distance between the target and the projection target in the plurality of lens object distance intervals; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and focusing the projection target based on the target image distance interval.

According to a second aspect of the embodiments of the present invention, applied to an image forming apparatus, including: determining a target object distance interval which is in accordance with the measurement distance between the target and an imaging target in a plurality of lens object distance intervals; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and focusing the imaging target based on the target image distance interval.

According to a third aspect of embodiments of the present invention, there is provided a projector including: a projection optical system; a distance sensor sensing a measured distance to the projection target; a controller, comprising: an image distance control unit which determines a target object distance section corresponding to a measurement distance between the projection target and the distance sensor, among the plurality of lens object distance sections; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and a focus control unit configured to control the projection optical system to focus the projection target based on the target image distance section.

According to a fourth aspect of the embodiments of the present invention, there is provided an image forming apparatus including: an imaging optical system; a distance sensor sensing a measured distance to an imaging target; a controller, comprising: an image distance control unit that determines a target object distance section corresponding to a measurement distance between the imaging target and the distance sensor, among the plurality of lens object distance sections; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and a focus control unit configured to control the imaging optical system to focus the imaging target based on the target image distance section.

According to a fifth aspect of embodiments of the present invention, there is provided a computer-readable medium on which a computer program is stored, the program, when executed by a processor, implementing a focusing method as described in the first or second aspect.

The target image distance interval is determined according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals, so that the focusing precision of the projection target is ensured based on the target image distance interval.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present invention, and it is also possible for a person skilled in the art to obtain other drawings based on the drawings.

FIG. 1A is a schematic flowchart of an exemplary focusing method according to a first embodiment of the present invention;

FIG. 1B is a schematic flowchart of a focusing method according to another example of the first embodiment of the present invention;

fig. 2A is a schematic flowchart of a high-imaging-definition range determining method according to an example of the second embodiment of the present invention;

fig. 2B is a schematic flowchart of a high-imaging-definition range determining method according to another example of the second embodiment of the present invention;

FIG. 2C is a schematic view of a focusing method according to a second embodiment of the present invention;

FIG. 2D is a schematic diagram illustrating a focusing method according to a second embodiment of the invention;

FIG. 3 is a schematic flowchart of a focusing method according to a third embodiment of the present invention;

fig. 4 is a schematic block diagram of a projector according to an example of the fourth embodiment of the present invention;

FIG. 5 is a schematic block diagram of a projector light engine according to another example of the fourth embodiment of the present invention;

fig. 6 is a schematic block diagram of an imaging apparatus of an example of the fourth embodiment of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments obtained by a person skilled in the art based on the embodiments of the present invention shall fall within the scope of the protection of the embodiments of the present invention.

The following further describes specific implementation of the embodiments of the present invention with reference to the drawings.

Fig. 1A is a schematic flowchart of an exemplary focusing method according to a first embodiment of the present invention. The focusing method of fig. 1A, applied to a projector, includes:

110: and determining a target object distance interval which is in accordance with the measured distance between the projection targets in the plurality of lens object distance intervals.

It should be understood that the projector of the present embodiment may be any suitable electronic device having a projection function, including, but not limited to, projectors using CRT (Cathode Ray Tube) projection technology, LCD (Liquid Crystal Display) projection technology, DLP (Digital Light Processing) projection technology, and LCOS (Liquid Crystal on Silicon) projection technology. The lens object distance interval may be a high imaging definition object distance interval. Sharpness in this context may refer to a relative value that characterizes whether an image captured by a sensor is sharp when the image is evaluated by an algorithm. For example, the sensor may be a sensor such as an image sensor. The object distance in this context may refer to the distance of the projection plane from the center of the opto-mechanical lens, e.g. in the direction of the optical axis of the opto-mechanical lens. The object distance may also refer to the distance of the target position of the opto-mechanical lens relative to a reference object at a fixed relative distance from the projection plane. For example, in the moving direction of the optical engine lens (or the direction parallel to the optical axis), the distance between the target position and the optical engine lens is a fixed value.

In addition, when the lens moves, the distance between the lens and the projection surface changes. The object distance interval in this context means the interval in which the numerical value of the distance is located, and the interval may be continuous or discrete. It should also be understood that the image distance in this context may refer to the distance of the projection target from the center of the optical engine lens, or to the distance of the projection target from the target position at a fixed distance from the center. The image distance interval in this document is an interval in which the numerical value of the image distance is located, and the interval may be continuous or discrete. In addition, the object distance in the embodiment of the invention is arranged on one side of the lens, and the image distance is arranged on the other side of the lens. For example, for the electronic device of the present invention, the object distance is one side of the projection using the lens, and the image distance is the other side of the lens.

It is also understood that object distances included in the object distance intervals herein may be indicative of object distance positions. Similarly, an image distance included in the image distance interval may indicate an image distance position. For example, when the projection surface is taken as a reference object, the image distance position may indicate a position of the optical engine lens (or the projector lens) in the optical axis direction, for example, a position of a center of the optical engine lens in the optical axis direction. For example, when a projection target is taken as a reference object, the object distance position may indicate a position of the projection target from an optical machine lens (e.g., an optical machine lens center) in the optical axis direction. Ideally, the number of object distance indicating object distance positions included in the object distance interval may be arbitrary, e.g., limited or unlimited. The number of image distance positions included in the image distance interval may be arbitrary, e.g., limited or unlimited. The object distance interval in the text may be a continuous interval or a discontinuous interval. Similarly, the high-imaging-resolution image-distance sections may be continuous sections or discontinuous sections. The object distance interval may be an open interval or a closed interval. Similarly, the high imaging resolution image distance interval may be an open interval or a closed interval. The embodiment of the present invention is not limited thereto. For example, the plurality of lens object distance intervals and the plurality of high imaging definition image distance intervals have at least one of a one-to-one mapping relationship, a one-to-many mapping relationship, a many-to-one mapping relationship, or a many-to-many mapping relationship therebetween. For example, the above correspondence may be determined by testing, and ideally, the above correspondence may be determined by an optical parameter of the lens, for example, an optical parameter relationship based on a focal length of the lens. For example, by testing and determined jointly by the optical parameters of the lens. The embodiment of the present invention is not limited thereto.

It is also understood that a high imaging definition region may indicate an image distance with high imaging definition for a given object distance. For example, a high imaging sharpness may be a high contrast of the imaging. For example, a sharpness of imaging that meets the user's needs. For example, imaging sharpness that meets industry standards. For example, the imaging sharpness meeting the preset conditions of the user or the manufacturer, which is not limited by the present invention.

For example, in the pre-factory stage of the projector, each projector (or projector optical engine) is measured, for example, a motor driving a control lens runs (moves to different positions on a rail), and a correspondence table between an object distance interval and a high-definition image distance interval (high-definition lens position interval) is calculated. When focusing is carried out, the lens position interval corresponding to the clear image in the object distance interval is found out according to the object distance interval with the distance.

It is to be understood that the projected target may be a sensing target of a sensor, for example, a sensing target of a distance sensor. The measured distance herein may be a distance (i.e., may also be referred to as a projected distance) between a sensing target and an acoustic wave detector or an electromagnetic wave (e.g., light wave) detector mounted on the sensor. The projection distance may also be the distance between the sensing target and a reference object having a fixed distance to the detector.

The projection distance to the projection target may be determined in any manner. For example, the projection distance to the projection target is measured by a distance sensor. For example, the distance sensor may be a visible light distance sensor, a non-visible light distance sensor such as an infrared distance sensor, a laser sensor, or the like. For example, the distance sensor may measure a distance based on a flight distance measurement principle using ultrasonic waves, laser light, infrared light, radar, or the like. The target object distance interval can be one object distance interval or a plurality of lens object distance intervals. For the target object distance interval of the projection distance from the projection target, the projection distance may be within the target object distance interval, may be at an end point of the target object distance interval, and may be within a preset range from a point in the target object distance interval. The embodiment of the present invention is not limited thereto. For example, the distance between the current optical machine and the projection wall surface is measured by a distance sensor, and according to an object distance interval corresponding to the distance, a corresponding definition interval including a start value and an end value is inquired.

120: and determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals.

It should be understood that the lens image distance interval may be a high imaging resolution image distance interval. The target high imaging definition image distance interval can be one high imaging definition image distance interval or a plurality of high imaging definition image distance intervals. For example, for a one-to-one mapping, one target object distance interval corresponds to one target image distance interval. For example, for a one-to-many mapping relationship, one target object distance interval corresponds to multiple target image distance intervals. For example, for many-to-one mapping, a plurality of target object distance intervals corresponds to one target image distance interval. For example, for a many-to-many mapping relationship, the plurality of target object distance intervals correspond to the plurality of target image distance intervals. For the one-to-many mapping relationship or the many-to-many mapping relationship, the optimal image distance interval in the same plurality of target image distance intervals can be determined as a target high imaging definition image distance interval, or the minimum image distance interval can be determined as a target high imaging definition image distance interval.

It should also be understood that the plurality of lens object distance intervals may or may not form a continuous interval, and any two object distance intervals may also overlap each other. In the case of one-to-one mapping, two high-resolution image distance sections corresponding to two adjacent object distance sections of the plurality of lens object distance sections may or may not overlap each other.

130: and focusing the projection target based on the target image distance interval.

It should be understood that the lens movement can be controlled to focus the projection target. For example, the lens motor controls the lens movement to focus the projection target. Specifically, the lens can be controlled to move in the target image distance interval, and the projection target is focused.

In addition, in the solution of the embodiment of the present invention, the lens image distance section may be a high imaging definition image distance section, and the lens object distance section may be a high imaging definition object distance section, so that the target image distance section may be a target high imaging definition image distance section, and since the projection target can be focused based on the target high imaging definition image distance section, the focusing speed is further improved for the specific imaging definition.

In other words, for the sharpness evaluation algorithm based on the image sensor, the motor drives the lens to run through the whole process first, find out the approximate range of the sharp points, and then fine-tune in the range, thereby finding out the clearest points. For a projector, especially a projector with a long focal stroke, if more points are adopted, the focusing success rate is high, but the focusing is slow; if fewer points are taken, focusing will be faster, but the success rate will be lower. Because the algorithm cannot give consideration to the focusing success rate and the focusing speed at the same time, compared with the prior art, the embodiment of the invention not only ensures the imaging definition, but also improves the focusing speed.

For the scheme of directly calculating the position of the clearest point by focusing based on the distance sensor, the embodiment of the invention ensures the focusing uniformity of each position, has lower requirements on structure and consistency and greatly realizes the advantage of low cost.

Fig. 1B is a schematic flowchart of another exemplary focusing method according to a first embodiment of the invention. The focusing method of fig. 1B is applied to an imaging apparatus, including:

170: determining a target object distance interval which is in accordance with the measurement distance between the target and an imaging target in a plurality of lens object distance intervals;

180: determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals;

190: and focusing the imaging target based on the target image distance interval.

In one example, the imaging device may be a device having an imaging function, for example, a mobile terminal with a camera such as a mobile phone. The following description is given with reference to a scenario in which a mobile phone, which may include a lens, a distance sensor, and an image sensor, is taken as an example (the same may be applied to other examples). The lens may be configured with a lens motor, wherein the controller is specifically configured to: and controlling a lens motor to drive the lens to move for multiple times in the target image distance interval, so that the lens passes through multiple adjusting positions in the target image distance interval to reach the focusing image distance position. The image sensor may be configured to determine a plurality of imaging resolutions based on the plurality of adjustment positions, respectively; the controller is specifically configured to: and determining a focusing image distance position from the plurality of adjusting positions, wherein the imaging definition corresponding to the focusing image distance position is higher than the imaging definition corresponding to other adjusting positions in the plurality of imaging definitions.

The distance sensor can be arranged around the lens, so that accurate measurement distance can be obtained for different imaging targets, and adverse influence on measurement accuracy caused by movement of the mobile phone is avoided. The controller can be an independent mobile phone imaging controller or a part of functions of a mobile phone processor. At least two of the lens, the distance sensor, and the image sensor may be integrated into one module, for example, the lens, the distance sensor, and the image sensor may be integrated into a camera module so as to be mounted in a cellular phone. In addition, the camera module may correspond to an application program in the cellular phone. The corresponding relation can be downloaded from the camera service terminal or stored in a memory of the mobile phone through an external device, and the corresponding relation can be updated from the local or the camera service terminal. The mobile phone camera of the example has the functions, so that rapid imaging can be realized, and the anti-shake effect is improved. Further, the correspondence relationship may be determined according to a setting by a user. For example, the original corresponding relationship with the first object distance range may be downloaded through a peripheral transmission or a camera server, and the corresponding relationship with the second object distance range may be determined from the original corresponding relationship according to the setting of the user. The second object distance range is smaller than the first object distance range, and the second object distance range can set the selected preference object distance range for the user. Since the correspondence has a preferred object distance range, rapid imaging is further achieved.

For example, a cell phone camera measures an imaging target at a first location resulting in a first measured distance, and measures the imaging target at a second location resulting in a second measured distance. And determining a first target object distance interval which is in accordance with the first measurement distance in the plurality of lens object distance intervals. According to the corresponding relation, determining a first target image distance interval corresponding to a first target object distance interval in the plurality of lens image distance intervals; focusing the imaging target based on the first target image distance interval to obtain a first image. Similarly, a second image corresponding to the first location is obtained. And judging the elapsed time of the mobile phone camera moving from the first position to the second position, and if the elapsed time is less than a preset threshold value, determining the second image as the image of the imaging target. If the elapsed time is greater than the predetermined threshold, the first image is determined to be an image of the imaging target.

In another example, the imaging device may be a monitoring device such as a traffic monitoring device, an indoor monitoring device. In one scenario, the traffic monitoring device may include an overspeed monitoring device or a traffic event monitoring device. For example, a traffic monitoring device measures an imaging target (e.g., a moving or stationary vehicle, a pedestrian, etc.) at a first location resulting in a first measured distance, and measures an imaging target at a second location resulting in a second measured distance. And determining a first target object distance interval which is in accordance with the first measurement distance in the plurality of lens object distance intervals. According to the corresponding relation, determining a first target image distance interval corresponding to a first target object distance interval in the plurality of lens image distance intervals; focusing the imaging target based on the first target image distance interval to obtain a first image frame. Similarly, a second image frame corresponding to the first position is obtained. A surveillance video is generated based on the first image frame and the second image frame. By adopting the focusing method of the embodiment of the invention, the imaging time of the first image frame and the second image frame is reduced under the condition of ensuring the imaging definition, so the image quality of the monitoring video generated based on the image frames is improved.

In another scenario, an indoor monitoring device measures an imaging target (e.g., a moving or stationary person in a room such as a supermarket) at a first location, resulting in a first measured distance, and measures an imaging target at a second location, resulting in a second measured distance. And determining a first target object distance interval which is in accordance with the first measurement distance in the plurality of lens object distance intervals. According to the corresponding relation, determining a first target image distance interval corresponding to a first target object distance interval in the plurality of lens image distance intervals; focusing the imaging target based on the first target image distance interval to obtain a first image frame. Similarly, a second image frame corresponding to the first position is obtained. A surveillance video is generated based on the first image frame and the second image frame. By adopting the focusing method of the embodiment of the invention, the imaging time of the first image frame and the second image frame is reduced under the condition of ensuring the imaging definition, so the image quality of the monitoring video generated based on the image frames is improved even if people move indoors.

As an example, the correspondence relationship is a one-to-one correspondence relationship between a plurality of lens object distance sections and a plurality of lens image distance sections. As another example, the plurality of lens object distance sections form a continuous section, and as another example, two image distance sections respectively corresponding to two adjacent object distance sections of the plurality of lens object distance sections overlap.

In another implementation of the present invention, the correspondence is obtained by: driving the test lens to move through a test lens motor to obtain a plurality of lens object distance intervals; and determining a plurality of lens image distance intervals corresponding to the plurality of lens object distance intervals based on the lens optical parameters to obtain a corresponding relation.

In another implementation manner of the present invention, driving a test lens to move by a test lens motor to obtain a plurality of lens object distance intervals includes: driving the test lens to move through a test lens motor, and determining a plurality of groups of lens moving steps relative to a preset reference image distance position; a plurality of lens object distance intervals are determined based on the plurality of groups of lens movement steps, wherein each group of lens movement steps represents a group of interval endpoints of the corresponding lens object distance interval. For example, each pair of lens movement steps represents a pair of interval endpoints of the corresponding lens object distance interval. For example, a test lens motor drives a test lens to move, and a plurality of groups of lens moving steps relative to a preset reference image distance position are determined; and determining a plurality of lens object distance intervals based on the plurality of groups of lens moving steps, so that the plurality of lens object distance intervals form a continuous interval, and two image distance intervals respectively corresponding to two adjacent object distance intervals in the plurality of lens object distance intervals are overlapped. The reference image distance position may be a reference position of an image distance, and is used for marking an image distance interval by using a moving step number of the lens. For example, the reference image distance position may be an arbitrary image distance position marked in advance. Preferably, in the projection object or the imaging object in the object distance range, the imaging resolution corresponding to the reference image distance position is higher than the imaging resolution corresponding to the other image distance positions.

It is to be understood that the target high imaging resolution may be a superior resolution, for example, the target high imaging resolution is higher than other high imaging resolutions of the plurality of high imaging resolutions.

For example, in the pre-shipment stage of the projectors, the lens position intervals at which the screens corresponding to the respective object distances are clear are calculated for each projector. Under the better projection distance and better light environment of the projection module, the position of the lens when the picture is clearest under the environment is tested and obtained and is called as the better image distance position or the standard point. And then testing the object distance change reflected by the image distance change corresponding to the position of the lens driven by the driving motor in one step, and calculating a corresponding table of the motor position and the object distance by taking the optimal image distance position as the center by combining the standard points. Wherein std represents the position of the standard point at an object distance of 160cm, and the unit of the object distance is (cm) and the unit of the image distance is (number of steps)

[48,53][std-14,std-8]

(53,58][std-13,std-7]

(58,63][std-12,std-6]

(63,68][std-11,std-5]

(68,75][std-10,std-4]

(75,85][std-9,std-3]

(85,95][std-8,std-2]

(95,105][std-7,std-1]

(105,115][std-6,std]

(115,135][std-5,std+1]

(135,155][std-4,std+2]

(155,205][std-3,std+3]

(205,250][std-2,std+4]

(250,450][std,std+5]

For example, for determining the high-imaging-resolution image-distance interval, fig. 2A is a schematic flowchart of a high-imaging-resolution image-distance interval determining method according to an example of the second embodiment of the present invention. As shown in figure 2A of the drawings,

210: the reference image distance position is recorded.

220: and for one object distance position, driving the test lens to move from the reference image distance position to a high-imaging definition image distance position through the test driving motor.

230: the relative position of the high-imaging-definition image distance position and the reference image distance position is recorded as the high-imaging-definition image distance position.

240: accordingly, a plurality of high imaging definition image distance positions are recorded.

And 250, driving the test lens to move a specific step length from each high imaging definition image distance position through the test driving motor, and determining a plurality of high imaging definition image distance intervals.

Fig. 2B is a schematic flowchart of another exemplary high-imaging-definition range determining method according to the second embodiment of the present invention. It should be understood that steps in the method of fig. 2B that are the same as steps in the method of fig. 2A are given the same reference numerals and different parts are given different numbers for distinction.

210: the reference image distance position is recorded.

260: and driving the test lens to move from the high-imaging definition image distance position through the test driving motor, and determining the high-imaging definition image distance section where the high-imaging definition image distance position is located.

270: and recording the relative position of the high-imaging-definition image distance position and the end point of the high-imaging-definition image distance section as the position of the high-imaging-definition image distance section.

280: correspondingly, the high-imaging-definition image distance interval is moved by taking the step length as a unit, and a plurality of high-imaging-definition image distance intervals are obtained.

290: and recording end points of a plurality of high-imaging-definition image distance intervals.

Fig. 2C is a schematic view of a focusing method according to a second embodiment of the invention. As shown, the distance sensor of the projector measures the distance between the distance projection screen (one example of a projection target). The projector performs table lookup (an example of correspondence) based on the measurement distance, and obtains a fine adjustment section (an example of a target image distance section). Based on the fine adjustment interval, the projector controls the lens to move so as to adjust (e.g., fine-tune) the image distance, and obtain a final image distance position (i.e., a focus position) with better definition (the definition of the image distance position is higher than that of other image distance positions). The process of determining the in-focus position based on the fine adjustment section may be performed using an image sensor. The image sensor may determine a plurality of adjustment positions (a plurality of image distance positions) in the fine adjustment section, and among the plurality of adjustment positions, an in-focus position is determined. The focused position may not be in the plurality of adjusted positions, for example, a plurality of candidate focused positions may be obtained by performing interpolation processing or processing for deleting a part of the adjusted positions, and a focused position may be selected from the plurality of candidate focused positions. For example, the focus position is determined based on a plurality of adjustment positions, and whether to perform subsequent adjustment or adjustments may be determined based on the definition corresponding to the current adjustment position or positions. All of the multiple adjustment positions may also be determined. It should be understood that the above-described focusing method is also applicable to the imaging apparatus.

In another implementation of the present invention, focusing a projection target based on a target image distance interval includes: the lens is driven by the lens motor to move for multiple times in the target image distance interval, so that the lens passes through multiple adjusting positions in the target image distance interval to reach the focusing image distance position.

In one example, the lens motor rotation step number is calculated based on the lens movement step number from the next adjustment position before each movement. In this movement, the rotational direction of the lens motor is unchanged, wherein the lens motor rotational step count is calculated based on the lens movement step count from the next adjustment position, including: and determining the number of lens moving steps between the next adjusting position and the next adjusting position as the number of lens motor rotating steps. Or, in the moving, the rotation direction of the lens motor is changed, wherein the calculating the number of lens motor rotation steps based on the number of lens moving steps from the next adjustment position includes: and calculating the rotation step number of the lens motor based on the lens moving step number and the predetermined idle stroke step number.

In another example, in making each movement, if the path to the next adjustment position indicates that the direction of movement is not changed, the number of lens movement steps from the next adjustment position is determined as the number of lens motor rotation steps. Alternatively, at each movement, if a path to a next adjustment position indicates a change in the direction of movement, the lens motor rotation step number is calculated based on the lens movement step number from the next adjustment position and a predetermined idle stroke step number.

In another embodiment of the invention, the number of idle stroke steps is determined by: and determining the number of idle stroke steps based on the rotation step difference of the testing lens motor which drives the testing lens to pass through the same image distance position in the forward direction and the reverse direction respectively and the total stroke step number of the testing lens motor. It should be appreciated that in this example, the number of idle stroke steps for reverse running of the drive motor is tested during the production phase or pre-factory phase. The driving motor drives the focusing mechanism, and the focusing mechanism is combined with the optical-mechanical module to finally drive the position change of the optical lens in the optical-mechanical module. In the middle, due to the influence of the gear gap, when the rotation direction of the driving motor changes, a section of idle stroke exists, so that the driving motor moves forwards for N steps and then moves backwards for N steps, and the lens position before moving cannot be returned. Therefore, the number of steps of the idle stroke is calculated, and when the device moves in the reverse direction, the number of steps of the idle stroke is moved first, and then the required number of steps is moved, so that the problems are solved, and the focusing time is further reduced.

For example, it is calculated as follows: assuming that the total stroke of the motor is M, the motor runs from 0 to the clearest point, the position is A1, the motor continues to run to M, then runs to the clearest point again in the reverse direction, and the recording position is A2, and the number of idle stroke steps is A1-A2.

In another embodiment of the invention, the number of idle stroke steps is determined by: and determining the step number difference of the forward and reverse driving test lenses of the test driving motor passing through the same image distance position as the idle stroke step number. The optical lens is moved by the driving motor, the step number of the reverse idle stroke is measured in the production stage, the step number of the idle stroke is moved firstly when the optical lens needs to be moved reversely during focusing, the idle stroke is offset, and therefore the driving motor supports bidirectional running and does not need to return to the original point once when the direction is changed every time.

In another implementation manner of the present invention, the driving a motor to control a lens to move for multiple times in a high image definition range of a target, so as to focus a projection target, includes: the lens is controlled to move for multiple times in the target high imaging definition image distance interval by driving the motor, so that the lens passes through multiple image distance positions in the target high imaging definition image distance interval to reach the focusing image distance position. For example, the difference between the current position of the optical lens and the starting position of the clear interval is calculated, the driving motor moves the lens to the starting position of the clear interval, the lens passes through a plurality of image distance positions to reach the ending position of the interval, and then the lens reaches the focusing image distance position. For example, the difference between the current position of the optical lens and the end position of the clear interval is calculated, the driving motor moves the lens to the end position of the clear interval, the initial position of the interval is reached through a plurality of image distance positions, and then the focusing image distance position is reached.

For example, with an image sensor, a plurality of imaging resolutions are determined based on a plurality of image distance positions, respectively, such that the plurality of image distance positions correspond to a plurality of imaging resolutions of a projection target, respectively, wherein, of the plurality of image distance positions, an image distance position corresponding to a target imaging resolution of the plurality of imaging resolutions is a focus image distance position. For example, of the plurality of imaging resolutions, the target imaging resolution is higher than the other imaging resolutions.

For example, the motor drives the lens to complete the run from the start point of the section to the end point of the section. For example, alternatively, the motor drives the lens to complete the running from the section end point to the section start point. For example, comparing the current resolution (corresponding to the current image distance position) with the previous resolution (corresponding to the previous image distance position), and if the current resolution is clearer than the previous resolution, marking the current image distance position instead of the previous image distance position; and if the previous definition is not clear, directly determining the previous image distance position as the focusing position and returning to the previous image distance position. For example, the number of steps is calculated based on the number of steps of the empty trip at the time of return. The focusing position is a local maximum value in the high imaging definition interval, so that the focusing position can be determined without running the whole process, and the focusing time is reduced.

In another implementation manner of the present invention, driving a lens to move multiple times in a target image distance interval by a lens motor so that the lens passes through multiple adjustment positions in the target image distance interval to reach a focusing image distance position includes: determining, with the image sensor, a plurality of imaging resolutions based on the plurality of adjustment positions, respectively; and determining a focusing image distance position from the plurality of adjusting positions, wherein the imaging definition corresponding to the focusing image distance position is higher than the imaging definition corresponding to other adjusting positions in the plurality of imaging definitions. For example, in a lens position interval of a corresponding distance, the lens is moved to each position, the image sensor is adopted to evaluate the definition of the image, the position of the clearest point in the interval is calculated, and the clearest point is moved. In other words, at each position of the clear interval, the corresponding definition is calculated through the image sensor, the corresponding position with the highest definition is found, and the optical lens is moved to the position to complete focusing. For example, the position with the highest resolution is set as the focused image distance position. For example, an arbitrary position among a plurality of positions with the highest sharpness is optionally set as the in-focus image distance position.

For example, when multiple image distance positions are traversed, the sharpness of each position may be calculated for each position. For example, comparing the current resolution (corresponding to the current image distance position) with the previous resolution (corresponding to the previous image distance position), and if the current resolution is clearer than the previous resolution, marking the current image distance position instead of the previous image distance position; if the last resolution is not clear, the position of an image distance on the mark is kept. For example, the motor drives the lens to complete the run from the start point to the end point of the section, and directly returns to the image distance position of the mark. For example, the number of steps is calculated based on the number of steps of the empty trip at the time of return. For example, alternatively, the motor drives the lens to complete the run from the section end point to the section start point, returning directly to the image distance position of the mark. For example, the number of steps is calculated based on the number of steps of the empty trip at the time of return. Therefore, the number of running positions is reduced, and the focusing time is reduced. In addition, the focusing time is further reduced due to the consideration of the number of idle stroke steps. Specifically, fig. 2D is a schematic flowchart of a focusing method according to a second embodiment of the present invention. The detailed flow and scenario of one example of an embodiment of the present invention can be appreciated as shown in FIG. 2D.

Fig. 3 is a schematic flowchart of a focusing method according to a third embodiment of the invention. It should be understood that the focusing method of FIG. 3 includes both the steps of the test method and the steps of the use method. Specifically, the method comprises the following steps:

301: and calculating high imaging definition intervals corresponding to different object distances.

302: and calculating the number of idle stroke steps.

303: the number of differential steps between the motor position (or lens position) and the start of the high imaging resolution region is determined.

304: judging whether the motor driving direction is the same as the last time, and if so, executing the step 305; if not, step 306 is performed.

305: and the running position difference step number of the motor.

306: the number of steps of the reverse idle stroke of the motor running position and the number of steps of the running position difference.

307: the driving motor runs from the starting point of the interval to the ending point of the interval, the definition of each image distance position is calculated, and the focusing position with the maximum definition is calculated.

308: and the motor runs to a focusing position to finish focusing.

Fig. 4 is a schematic block diagram of a projector according to a fourth embodiment of the present invention; the projector of fig. 4 includes:

a projection optical system 410;

a distance sensor 420 sensing a measured distance to the projection target;

a controller 430, comprising: an image distance control unit 431 for determining a target object distance section corresponding to the measurement distance to the projection target sensed by the distance sensor 420 among the plurality of lens object distance sections; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; the focus control unit 432 controls the projection optical system 410 to focus the projection target based on the target image distance interval.

It should be understood that the controller may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; but may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

In another implementation of the present invention, the plurality of lens object distance intervals form a continuous interval.

In another implementation manner of the present invention, two image distance intervals corresponding to two adjacent object distance intervals of the plurality of object distance intervals of the lens are partially overlapped.

In another implementation manner of the present invention, the projection optical system includes a lens configured with a lens motor, wherein the focus control part is specifically configured to: and controlling a lens motor to drive the lens to move for multiple times in the target image distance interval, so that the lens passes through multiple adjusting positions in the target image distance interval to reach the focusing image distance position.

In another implementation of the invention, the number of lens movement steps from the next adjustment position is determined as the number of lens motor rotation steps if the path to the next adjustment position indicates no change in direction of movement at each movement.

In another implementation of the present invention, the lens motor rotation step number is calculated based on a lens movement step number from a next adjustment position and a predetermined idle stroke step number if a path to the next adjustment position indicates a change in movement direction at each movement.

In another implementation of the invention, the number of idle stroke steps is determined by: and determining the idle stroke step number based on the rotation step number difference of the lens motor which drives the lens in the forward direction and the reverse direction respectively through the same image distance position and the total stroke step number of the lens motor.

In another aspect of the present invention, a focus control unit includes: an image sensor that determines a plurality of imaging resolutions based on the plurality of adjustment positions, respectively, the focus control section being specifically configured to: and determining a focusing image distance position from the plurality of adjusting positions, wherein the imaging definition corresponding to the focusing image distance position is higher than the imaging definition corresponding to other adjusting positions in the plurality of imaging definitions determined by the image sensor.

The projector of the embodiment is used for implementing the corresponding method in the foregoing method embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described herein again. In addition, the functional implementation of each module in the projector of the present embodiment can refer to the description of the corresponding part in the foregoing method embodiment, and is not repeated herein.

Fig. 5 is a schematic block diagram of a projector optical engine according to another example of the fourth embodiment of the present invention. For example, the driving motor drives the focusing mechanism, and the focusing mechanism is combined with the optical-mechanical module, so that the position change of an optical lens in the optical-mechanical module is finally driven. For example, when the position of the optical lens is changed, the distance sensed by the distance sensor may be changed, and accordingly, the result of the image sensor may be changed while the lens is running. For example, the distance sensor and the image sensor input the results to the main control chip for processing, and the main control chip controls the driving motor to move to the next running position based on the processing results. It should be understood that the above-described schematic block diagram configuration is only one example of the embodiment of the present invention, and the embodiment of the present invention may be implemented in other ways.

Fig. 6 is a schematic block diagram of an image forming apparatus of a fourth embodiment of the present invention; the image forming apparatus of fig. 6 includes:

an imaging optical system 610;

a distance sensor 620 sensing a measured distance to the imaging target;

a controller 630, comprising: an image distance control unit 631 which determines a target object distance section corresponding to a measurement distance to the imaging target measured by the distance sensor 620, among the plurality of lens object distance sections; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; the focus control unit 632 controls the imaging optical system 610 to focus on the imaging target based on the target image distance section.

The target image distance interval is determined according to the corresponding relation between the lens object distance intervals and the lens image distance intervals, so that the focusing precision of the imaging target is ensured based on the target image distance interval.

In another implementation manner of the present invention, the imaging optical system includes a lens configured with a lens motor, wherein the focus control section is specifically configured to: and controlling a lens motor to drive the lens to move for multiple times in the target image distance interval, so that the lens passes through multiple adjusting positions in the target image distance interval to reach the focusing image distance position.

The imaging device of this embodiment is used to implement the corresponding method in the foregoing method embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described herein again. In addition, the functional implementation of each module in the imaging device of this embodiment can refer to the description of the corresponding part in the foregoing method embodiment, and is not repeated here.

In particular, according to an embodiment of the present disclosure, the processes described above with reference to the flowcharts may be implemented as computer software programs. For example, embodiments of the present disclosure include a computer program product comprising a computer program embodied on a computer readable medium, the computer program comprising program code configured to perform the method illustrated by the flow chart. In such an embodiment, the computer program may be downloaded and installed from a network via the communication section, and/or installed from a removable medium. The computer program, when executed by a Central Processing Unit (CPU), performs the above-described functions defined in the method of the present application. It should be noted that the computer readable medium described herein can be a computer readable signal medium or a computer readable storage medium or any combination of the two. The computer readable medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples of the computer readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access storage media (RAM), a read-only storage media (ROM), an erasable programmable read-only storage media (EPROM or flash memory), an optical fiber, a portable compact disc read-only storage media (CD-ROM), an optical storage media piece, a magnetic storage media piece, or any suitable combination of the foregoing. In the present application, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In this application, however, a computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, fiber optic cable, RF, etc., or any suitable combination of the foregoing.

Computer program code configured to carry out operations for the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + +, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may operate over any of a variety of networks: including a Local Area Network (LAN) or a Wide Area Network (WAN) -to the user's computer, or alternatively, to an external computer (e.g., through the internet using an internet service provider).

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions configured to implement the specified logical function(s). In the above embodiments, specific precedence relationships are provided, but these precedence relationships are only exemplary, and in particular implementations, the steps may be fewer, more, or the execution order may be modified. That is, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The modules described in the embodiments of the present application may be implemented by software or hardware. The names of these modules do not in some cases constitute a limitation of the module itself.

As another aspect, the present application further provides a computer-readable medium, on which a computer program is stored, which when executed by a processor implements the focusing method as described in the first embodiment.

As another aspect, the present application also provides a computer-readable medium, which may be contained in the apparatus described in the above embodiments; or may be present separately and not assembled into the device. The computer readable medium carries one or more programs which, when executed by the apparatus, cause the apparatus to: determining a target object distance interval which is in accordance with the measurement distance between the target and the projection target in the plurality of lens object distance intervals; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; focusing the projection target based on the target image distance interval;

or, in a plurality of lens object distance intervals, determining a target object distance interval which is in accordance with the measurement distance between the lens object distance interval and the imaging target; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and focusing the imaging target based on the target image distance interval.

The computer-readable medium may be, but is not limited to, a Random Access Memory (RAM), a Read-Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Read-Only Memory (EPROM), an electrically Erasable Read-Only Memory (EEPROM), and the like.

The expressions "first", "second", "said first" or "said second" used in various embodiments of the present disclosure may modify various components regardless of order and/or importance, but these expressions do not limit the respective components. The above description is only configured for the purpose of distinguishing elements from other elements. For example, the first user equipment and the second user equipment represent different user equipment, although both are user equipment. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure.

When an element (e.g., a first element) is referred to as being "operably or communicatively coupled" or "connected" (operably or communicatively) to "another element (e.g., a second element) or" connected "to another element (e.g., a second element), it is understood that the element is directly connected to the other element or the element is indirectly connected to the other element via yet another element (e.g., a third element). In contrast, it is understood that when an element (e.g., a first element) is referred to as being "directly connected" or "directly coupled" to another element (a second element), no element (e.g., a third element) is interposed therebetween.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the invention herein disclosed is not limited to the particular combination of features described above, but also encompasses other arrangements formed by any combination of the above features or their equivalents without departing from the spirit of the invention. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. A focusing method applied to a projector comprises the following steps:

determining a target object distance interval which is in accordance with the measurement distance between the target and the projection target in the plurality of lens object distance intervals;

determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals;

and focusing the projection target based on the target image distance interval.

2. The focusing method of claim 1, wherein the plurality of lens object distance intervals form a continuum.

3. The focusing method according to claim 1, wherein two image distance intervals corresponding to two adjacent object distance intervals of the plurality of lens object distance intervals partially overlap.

4. The focusing method of claim 1, wherein the focusing the projection target based on the target image distance interval comprises:

and driving the lens to move for multiple times in the target image distance interval through a lens motor, so that the lens passes through multiple adjusting positions in the target image distance interval to reach the focusing image distance position.

5. The focusing method according to claim 4, wherein in making each movement, if a path to a next adjustment position indicates that the direction of movement is not changed, the number of lens movement steps from the next adjustment position is determined as the number of lens motor rotation steps.

6. The focusing method according to claim 4, wherein, in making each movement, if a path to a next adjustment position indicates a change in the direction of movement, the lens motor rotation step number is calculated based on a lens movement step number from the next adjustment position and a predetermined idle stroke step number.

7. The focusing method according to claim 6, wherein the number of idle stroke steps is determined by:

and determining the idle stroke step number based on the rotation step number difference of the lens motor which drives the lens in the forward direction and the reverse direction respectively through the same image distance position and the total stroke step number of the lens motor.

8. The focusing method according to claim 4, wherein the driving the lens through the lens motor to move the lens within the target image distance interval for multiple times so that the lens passes through multiple adjustment positions within the target image distance interval to reach the focusing image distance position comprises:

determining, with an image sensor, a plurality of imaging resolutions based on the plurality of adjustment positions, respectively;

determining the focusing image distance position from the plurality of adjusting positions, wherein the imaging definition corresponding to the focusing image distance position is higher than the imaging definition corresponding to other adjusting positions in the plurality of imaging definitions.

9. A focusing method is applied to an imaging device and comprises the following steps:

determining a target object distance interval which is in accordance with the measurement distance between the target and an imaging target in a plurality of lens object distance intervals;

and focusing the imaging target based on the target image distance interval.

10. A projector, comprising:

a projection optical system;

a distance sensor sensing a measured distance to the projection target;

a controller, comprising: an image distance control unit which determines a target object distance section corresponding to a measurement distance between the projection target and the distance sensor, among the plurality of lens object distance sections; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and a focus control unit configured to control the projection optical system to focus the projection target based on the target image distance section.

11. The projector according to claim 10, wherein the projection optical system includes a lens provided with a lens motor, wherein the focus control section is specifically configured to: and controlling the lens motor to drive the lens to move for multiple times in the target image distance interval, so that the lens passes through multiple adjusting positions in the target image distance interval to reach the focusing image distance position.

12. The projector according to claim 11, wherein the focus control section includes: an image sensor that determines a plurality of imaging resolutions based on the plurality of adjustment positions, respectively,

the focus control section is specifically configured to: and determining the focusing image distance position from the plurality of adjusting positions, wherein the imaging definition corresponding to the focusing image distance position is higher than the imaging definition corresponding to other adjusting positions in the plurality of imaging definitions determined by the image sensor.

13. An image forming apparatus comprising:

an imaging optical system;

a distance sensor sensing a measured distance to an imaging target;

a controller, comprising: an image distance control unit that determines a target object distance section corresponding to a measurement distance between the imaging target and the distance sensor, among the plurality of lens object distance sections; determining a target image distance interval corresponding to the target object distance interval in the plurality of lens image distance intervals according to the corresponding relation between the plurality of lens object distance intervals and the plurality of lens image distance intervals; and a focus control unit configured to control the imaging optical system to focus the imaging target based on the target image distance section.

14. A computer-readable medium, on which a computer program is stored which, when being executed by a processor, carries out a focusing method as set forth in any one of claims 1 to 9.