CN119065187A - Projector focusing method based on linear Hall distance measurement - Google Patents
Projector focusing method based on linear Hall distance measurement Download PDFInfo
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- CN119065187A CN119065187A CN202411559247.7A CN202411559247A CN119065187A CN 119065187 A CN119065187 A CN 119065187A CN 202411559247 A CN202411559247 A CN 202411559247A CN 119065187 A CN119065187 A CN 119065187A
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/53—Means for automatic focusing, e.g. to compensate thermal effects
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/14—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring distance or clearance between spaced objects or spaced apertures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/142—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
- G01D5/145—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
- G02B7/287—Systems for automatic generation of focusing signals including a sight line detecting device
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- Optics & Photonics (AREA)
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Abstract
The invention provides a projector focusing method based on linear Hall ranging, which comprises the following steps of firstly installing a linear Hall at the fixed end of a projector lens and installing a permanent magnet at the movable end of the projector lens, secondly connecting the linear Hall with a motor control system, thirdly, generating linear voltage change along with the change of distance when the permanent magnet is close to or far from the linear Hall in the projector focusing process, and fourthly, establishing an algorithm model, and converting the linear voltage change of the linear Hall in the magnetic field range into the distance between a current Hall element and the permanent magnet, namely the specific position of the lens in the whole machine stroke. The invention completes the focal length adjustment of the projector through the cooperation of the linear Hall and the permanent magnet, and has lower cost compared with the traditional switch and optocoupler limit. The linear Hall output analog quantity is used for detecting the transverse moving distance, the transverse moving distance is consistent with the transverse stretching direction of the projection lens, and the motion data is fed back more truly.
Description
Technical Field
The invention relates to a focusing method, in particular to a projector focusing method based on linear Hall ranging, and belongs to the technical field of projector focusing.
Background
A projector is a commonly used multimedia presentation device, and is mainly used to project images or videos onto a screen or a wall surface so that viewers can clearly see the images or videos. The projector is widely applied to a plurality of fields such as education, business, entertainment and the like, and provides convenience for lectures, teaching, conferences and the like. Focusing is an important step in the projector using process, and the main function is to enable the projected image to reach the sharpest state by adjusting the focal length of the projector lens, so that the image is sharper and has layering sense, and the viewing experience is improved. Through adjusting the focal length, can make projection image accord with spectator's vision habit more, reduce visual fatigue, improve and view and admix experience, different projection distance and projection face size need different focal length setting, and the focusing can make the projecting apparatus adapt to different projection environment.
At present, limit detection is needed in motor control of a projection lens, and is used for providing signal indication that the lens reaches one end and the other end, and the motor control device is generally designed by 1-2 switches and optocouplers.
For example, an auto-focusing projector disclosed in CN206348581U in the prior art comprises an optical machine, a telescopic lens and an auto-focusing structure, wherein the telescopic lens comprises a deflector rod, the auto-focusing structure comprises a motor, a focusing ring and a bracket, and a photoelectric sensing switch only provides on or off digital quantity output, so that a master control only receives a signal when the last lens arrives, and thus, the master control lacks movement intermediate quantity, and can only attempt to extend and retract for many times to position the current lens in the whole stroke, and for this reason, a projector focusing method based on linear hall range finding is provided.
Disclosure of Invention
In view of the above, the present invention provides a projector focusing method based on linear hall ranging, so as to solve or alleviate one of the technical problems existing in the prior art, and under the premise of controlling the cost, the digital quantity of position detection is converted into an analog quantity, a determination dimension is added to the lens motion control of the master control, and the efficiency and experience of projection automatic focusing are improved, so that at least one beneficial choice is provided.
The technical scheme of the embodiment of the invention is realized by a projector focusing method based on linear Hall ranging, which comprises the following steps:
firstly, installing a linear Hall at the fixed end of a projector lens, installing a permanent magnet at the moving end of the projector lens, and moving the permanent magnet along with the precursor or shrinkage of the lens;
step two, connecting the linear Hall with a motor control system in a signal way, and transmitting the signal to the motor control system by the linear Hall;
In the focusing process of the projector, when the permanent magnet is close to or far from the linear Hall element, the voltage output of the linear Hall element generates linear voltage change along with the change of the distance, and when the permanent magnet is close to the linear Hall element, the magnetic field intensity B is increased to cause the increase of the output level V;
Step four, an algorithm model is established, and the voltage linear change of the linear Hall in the magnetic field range is utilized to convert the voltage linear change into the distance between the current Hall element and the permanent magnet, namely the specific position of the lens in the whole machine stroke;
Fifthly, calibrating and confirming ADC values a and b of the closest point and the farthest point of the permanent magnet in the focusing process of the lens, recording parameters, comparing the voltage ADC values acquired in actual operation with the voltage ADC values a and b in calibration, and ensuring that the lens is carried out in a range between the closest point and the farthest point;
And step six, the motor control system judges whether the lens further moves forward or moves backward according to the current position and the system blurring degree acquired by the camera.
It is further preferred that in the first step, the linear hall and the permanent magnet are horizontally arranged along the axial direction of the lens of the projector.
It is further preferred that in step two, the linear hall is used to output an analog signal, i.e. a continuous voltage signal.
It is further preferable that in the third step, the output level of the linear hall element is in a linear relationship with the intensity of the external magnetic field within a certain range, and the linearity triggers a stroke according to the intensity of the magnetic field, namely, the linear magnetic field range.
It is further preferred that in step four, the algorithm model is based on a lens imaging formula and a linear relationship of hall element voltage to object distance.
It is further preferred that in step four, according to the lens imaging formula:
1/u+1/v=1/f
Where u is the object distance, v is the image distance, f is the focal length, and the formula is changed to obtain:
u=fv/(v−f)
and then according to the linear relation between the object distance and the Hall element voltage:
u=k1×Vadc+k2
Wherein V adc is the Hall element voltage, and can be obtained by combining a lens imaging formula:
k1×Vadc+k2=fv/(v−f)
After finishing, the following steps are as follows:
Vadc=（fv-k2v+k2f）/（k1(v−f)))。
it is further preferred that in a projector scene, the difference between the image distance V and the focal length f is small relative to the image distance V itself, i.e. V-f≡v, the finishing formula can be derived:
Vadc=(fv-k2v+k2f)/(k1v)
Vadc=(f-k2)/k1+(k2f)/(k1v)
This can be achieved by:
Vadc=K1/v+K2
the hall element voltage V adc is inversely proportional to the image distance V according to the formula.
It is further preferred that the hall element voltage V adc and the image distance V are actually measured to obtain a plurality of sets of corresponding values, and the least square method is used to solve for K 1 and K 2.
It is further preferred that when solving for K 1 and K 2, the functions are noted as:
Vadc= K1×(1/v) + K2
Considering 1/V as an independent variable, V adc as a dependent variable, linear regression was used to solve for K 1 and K 2.
It is further preferable that in the sixth step, the image of the current position is compared with the image of the previous position, and the motor control system determines whether the next step is to proceed or to retreat according to the change of the definition.
By adopting the technical scheme, the embodiment of the invention has the following advantages:
1. The invention completes the focal length adjustment of the projector through the cooperation of the linear Hall and the permanent magnet, and has lower cost compared with the traditional switch and optocoupler limit.
2. The invention can increase the process quantity for the motor control system, and can lead the control system to be more accurate and direct.
3. According to the invention, the distance of transverse movement is detected through the linear Hall output analog quantity, and the distance is consistent with the transverse expansion direction of the projection lens, so that the motion data is fed back more truly.
The foregoing summary is for the purpose of the specification only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will become apparent by reference to the drawings and the following detailed description.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are necessary for the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a graph showing the output voltage versus magnetic induction density for the present invention;
FIG. 3 is a diagram of a projector lens according to the present invention;
Fig. 4 is a system configuration diagram of the present invention.
Reference numeral 1, a projection lens, 2, a permanent magnet, 3, a linear Hall sensor, 4, the furthest end of the lens and 6, the closest end of the lens.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
It should be appreciated that the following specific embodiments of the disclosure are described in order to provide a better understanding of the present disclosure, and that other advantages and effects will be apparent to those skilled in the art from the present disclosure. It will be apparent that the described embodiments are merely some, but not all embodiments of the present disclosure. The disclosure may be embodied or practiced in other different specific embodiments, and details within the subject specification may be modified or changed from various points of view and applications without departing from the spirit of the disclosure. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments in this disclosure are intended to be within the scope of this disclosure.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concepts of the disclosure by way of illustration, and only the components related to the disclosure are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
Example 1
As shown in fig. 1 and 2, an embodiment of the present invention provides a projector focusing method based on linear hall ranging, which includes the following steps:
Step one, installing a linear Hall at the fixed end of a projector lens, installing a permanent magnet at the moving end of the projector lens, wherein the linear Hall and the permanent magnet are horizontally arranged along the axial direction of the projector lens, and the permanent magnet moves along with the precursor or shrinkage of the lens;
Step two, connecting a linear Hall with a motor control system in a signal way, wherein the linear Hall is used for outputting an analog signal, namely a continuous voltage signal, the linear Hall sends the signal to the motor control system, a camera also sends the signal to the motor control system, and the motor control system sends a control signal to a motor to control a lens to move;
in the focusing process of the projector, when the permanent magnet is close to or far from the linear Hall element, the output level of the linear Hall element and the intensity of an external magnetic field form a linear relation in a certain range, as shown in figure 2, when the permanent magnet is close to the linear Hall element, the intensity of the magnetic field B is increased to cause the output level V to be increased, and when the permanent magnet is far from the linear Hall element, the intensity of the magnetic field B is reduced to cause the output level V to be reduced, and the linear range is triggered according to the intensity of the magnetic field, namely the linear magnetic field range;
Step four, an algorithm model is established, the voltage linear change of the linear Hall in the magnetic field range is utilized to be converted into the distance between the current Hall element and the permanent magnet, namely the specific position of the lens in the whole machine stroke, the algorithm model is based on a lens imaging formula and the linear relation between the Hall element voltage and the object distance, and the algorithm model is based on the lens imaging formula:
1/u+1/v=1/f
Where u is the object distance, v is the image distance, f is the focal length, and the formula is changed to obtain:
u=fv/(v−f)
and then according to the linear relation between the object distance and the Hall element voltage:
u=k1×Vadc+k2
Wherein V adc is the Hall element voltage, and can be obtained by combining a lens imaging formula:
k1×Vadc+k2=fv/(v−f)
After finishing, the following steps are as follows:
Vadc=（fv-k2v+k2f）/（k1(v−f)))
In a projector scene, the difference between the image distance V and the focal length f is small relative to the image distance V itself, i.e. V-f≡v, and the finishing formula can be obtained:
Vadc=(fv-k2v+k2f)/(k1v)
Vadc=(f-k2)/k1+(k2f)/(k1v)
This can be achieved by:
Vadc=K1/v+K2
the hall element voltage V adc is inversely proportional to the image distance V according to the formula.
The Hall element voltage V adc and the image distance V are actually measured to obtain a plurality of groups of corresponding values, and the least square method is used for solving K 1 and K 2. When solving for K 1 and K 2, the equations are written as:
Vadc= K1×(1/v) + K2
Considering 1/V as an independent variable, V adc as a dependent variable, linear regression was used to solve for K 1 and K 2.
Fifthly, calibrating ADC values a and b of the closest point and the farthest point of the permanent magnet in the focusing process of the lens, recording parameters, comparing the voltage ADC values acquired in actual operation with the voltage ADC values a and b in calibration, and ensuring that the lens is adjusted in the range between the closest point and the farthest point;
And step six, comparing the image of the current position with the image of the previous position by the motor control system according to the current position and the image blurring degree acquired by the camera, and judging whether the next step is continuous advancing or backward according to the change of definition.
Example two
As shown in fig. 1 and 2, an embodiment of the present invention provides a projector focusing method based on linear hall ranging, which includes the following steps:
Firstly, installing a linear Hall at the fixed end of a projector lens, installing a permanent magnet at the moving end of the projector lens, horizontally arranging the linear Hall and the permanent magnet along the axial direction of the projector lens, installing a linear Hall sensor at the fixed end of the projector lens to ensure that the linear Hall sensor can stably detect the magnetic field change of the permanent magnet in the moving process of the lens, installing the permanent magnet at the moving end of the projector lens, and aligning the magnetic pole direction of the permanent magnet with the sensitive axis direction of the linear Hall sensor to realize the maximum magnetic field change detection, wherein the linear Hall sensor and the permanent magnet are horizontally arranged along the axial direction of the projector lens to ensure that the relative position change between the linear Hall sensor and the permanent magnet can accurately reflect the displacement of the lens when the lens moves;
Step two, connecting a linear Hall with a motor control system signal, wherein the linear Hall is used for outputting an analog signal, namely a continuous voltage signal, and when the linear Hall is connected, an output signal line of the linear Hall is connected to an analog signal input interface of the motor control system by using a proper cable or connecting line;
In the focusing process of the projector, when the permanent magnet is close to or far from the linear Hall, the output level of the linear Hall element is in linear relation with the intensity of an external magnetic field in a certain range, the linearity can trigger a stroke according to the intensity of the magnetic field, namely the linear magnetic field range, when the permanent magnet is close to the linear Hall element, the magnetic field intensity B is increased to cause the output level V to be increased, and when the permanent magnet is far from the linear Hall element, the magnetic field intensity B is reduced to cause the output level V to be reduced, and the change process, namely the stroke, represents the magnetic field intensity range which the linear Hall element can respond to, namely the linear magnetic field range.
Step four, an algorithm model is established, the voltage linear change of the linear Hall in the magnetic field range is utilized to be converted into the distance between the current Hall element and the permanent magnet, namely the specific position of the lens in the whole machine stroke, the algorithm model is based on a lens imaging formula and the linear relation between the Hall element voltage and the object distance, and the algorithm model is based on the lens imaging formula:
1/u+1/v=1/f
Where u is the object distance, v is the image distance, f is the focal length, and the formula is changed to obtain:
u=fv/(v−f)
and then according to the linear relation between the object distance and the Hall element voltage:
u=k1×Vadc+k2
Wherein V adc is the Hall element voltage, and can be obtained by combining a lens imaging formula:
k1×Vadc+k2=fv/(v−f)
After finishing, the following steps are as follows:
Vadc=（fv-k2v+k2f）/（k1(v−f)))
In a projector scene, the difference between the image distance V and the focal length f is small relative to the image distance V itself, i.e. V-f≡v, and the finishing formula can be obtained:
Vadc=(fv-k2v+k2f)/(k1v)
Vadc=(f-k2)/k1+(k2f)/(k1v)
This can be achieved by:
Vadc=K1/v+K2
the hall element voltage V adc is inversely proportional to the image distance V according to the formula.
The Hall element voltage V adc and the image distance V are actually measured to obtain a plurality of groups of corresponding values, and the least square method is used for solving K 1 and K 2. When solving for K 1 and K 2, the equations are written as:
Vadc= K1×(1/v) + K2
Considering 1/V as an independent variable, V adc as a dependent variable, linear regression was used to solve for K 1 and K 2.
The following is a simple example of a c++ language program (examples for reference) using least squares to solve for K 1 and K 2:
It is assumed that there are 10 sets of measurement data
Double Vadc [10] = {/values of Vadc/;
the value of double v [10] = {/v;
void calculate_coefficients(double *K1, double *K2) {
double sum_inv_v = 0.0;
double sum_Vadc = 0.0;
double sum_inv_v_times_Vadc = 0.0;
double sum_inv_v_sq = 0.0;
calculating the necessary summation
for (int i = 0; i<n; i++) {
double inv_v = 1.0 / v[i];
sum_inv_v += inv_v;
sum_Vadc += Vadc[i];
sum_inv_v_times_Vadc += inv_v * Vadc[i];
sum_inv_v_sq += inv_v * inv_v;
}
double denominator = n * sum_inv_v_sq - sum_inv_v * sum_inv_v;
*K1 = (n * sum_inv_v_times_Vadc - sum_inv_v * sum_Vadc) / denominator;
*K2 = (sum_inv_v_sq * sum_Vadc - sum_inv_v * sum_inv_v_times_Vadc) / denominator;
}
Function of/(computation of image distance v)
double calculate_ image_distance (double voltage) {
return K1 / (voltage – K2);
}
Function of the calculated voltage V
double calculate_ voltage (double image_distance) {
return K1/ image_distance + K2;
}
Through the above procedure, K 1 and K 2 can be solved;
Fifthly, calibrating and confirming ADC values a and b of a closest point and a farthest point of a permanent magnet in a lens focusing process, recording parameters, comparing the voltage ADC values acquired in actual operation with the voltage ADC values a and b in calibration, ensuring that the lens focuses in a range between the closest point and the farthest point, moving the permanent magnet to the closest point of lens focusing when calibrating the closest point, reading the voltage ADC values output by a linear Hall element at the position through a circuit, recording the voltage ADC values as a, moving the permanent magnet to the farthest point of lens focusing when calibrating the farthest point, reading the voltage ADC values output by the linear Hall element at the position through the circuit again, recording the acquired two ADC values as b, recording the parameters as calibration parameters, comparing and judging the acquired two ADC values in the follow-up lens focusing process, reading the voltage ADC values output by the linear Hall element through the circuit in real time in the actual operation process of a projector, comparing the ADC values acquired in real time with the calibrated a and b, judging the current position of the permanent magnet (i.e. the lens) according to the comparison result of the real-time ADC values and the a and b, and judging the current position of the permanent magnet (i.e. the lens) if the ADC values are between the closest point and the closest point or the closest point of the final point of lens focusing operation or the final operation is reached, or the real-time operation point is reached;
And step six, comparing the image of the current position with the image of the previous position by the motor control system according to the current position and the image blurring degree acquired by the camera, judging that the next step is continuous advancing or retreating according to the change of definition, judging that the current direction is correct if the definition is improved (namely the image becomes clearer), and continuously advancing if the definition is reduced (namely the image becomes more blurring), judging that the current direction is wrong, and retreating to the previous position or performing fine adjustment, sending an instruction to a motor driver by the motor control system according to the judgment result, controlling the motor to advance, retreat or stop, repeating the steps to form a closed loop control system, and continuously adjusting the motor position until the optimal image definition position is found.
Example III
As shown in fig. 3, an embodiment of the present invention provides a lens structure of a projector, including a projection lens 1, a permanent magnet 2 and a linear hall sensor 3, wherein the projection lens 1 includes a moving end and a fixed end, the moving end of the projection lens 1 moves within a length range between a lens farthest end 4 and a lens nearest end 6, the permanent magnet 2 and the linear hall sensor 3 are respectively mounted on the moving end and the fixed end of the projection lens 1, and the permanent magnet 2 and the linear hall sensor 3 are on the same horizontal plane with a central axis of the lens, and the permanent magnet 2 and the linear hall sensor 3 are disposed along a direction of the central axis of the lens, at this time, a current distance from the permanent magnet to the hall can be calculated by a voltage linear change of the linear hall sensor 3 within a magnetic field range.
Example IV
As shown in fig. 4, the embodiment of the invention provides a focusing system of a projector, which comprises a motor control system, a camera, a motor, a hall sensor and a permanent magnet, wherein the camera and the hall sensor are in signal connection with the motor control system, a linear hall sends signals to the motor control system, the camera also sends image signals to the motor control system, the motor is electrically connected with the motor control system, and the motor control system sends control signals to the motor to control the movement of a lens, so that the focusing process is completed.
The voltage reading circuit, the motor driving circuit and the camera driving circuit are all in sequence schematic diagrams in the prior art, and the invention is not repeated on the premise that the person skilled in the art can search.
The invention completes the focal length adjustment of the projector through the cooperation of the linear Hall and the permanent magnet, and has lower cost compared with the traditional switch and optocoupler limit.
The invention can increase the process quantity for the motor control system, and can lead the control system to be more accurate and direct.
According to the invention, the distance of transverse movement is detected through the linear Hall output analog quantity, and the distance is consistent with the transverse expansion direction of the projection lens, so that the motion data is fed back more truly.
The basic principles of the present disclosure have been described above in connection with specific embodiments, but it should be noted that the advantages, benefits, effects, etc. mentioned in the present disclosure are merely examples and not limiting, and these advantages, benefits, effects, etc. are not to be considered as necessarily possessed by the various embodiments of the present disclosure. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, since the disclosure is not necessarily limited to practice with the specific details described.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.
In this disclosure, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions, and the block diagrams of devices, apparatuses, devices, systems involved in this disclosure are merely illustrative examples and are not intended to require or implicate that connections, arrangements, configurations must be made in the manner shown in the block diagrams. As will be appreciated by one of skill in the art, the devices, apparatuses, devices, systems may be connected, arranged, configured in any manner. Words such as "including," "comprising," "having," and the like are words of openness and mean "including but not limited to," and are used interchangeably therewith. The terms "or" and "as used herein refer to and are used interchangeably with the term" and/or "unless the context clearly indicates otherwise. The term "such as" as used herein refers to, and is used interchangeably with, the phrase "such as, but not limited to.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that various changes and substitutions are possible within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A projector focusing method based on linear Hall ranging is characterized by comprising the following steps:
Step one, installing a linear Hall at the fixed end of a projector lens, and installing a permanent magnet at the movable end of the projector lens;
Step two, connecting the linear Hall with a motor control system in a signal manner;
step three, in the focusing process of the projector, when the permanent magnet is close to or far from the linear Hall, the voltage output of the linear Hall generates linear change along with the change of the distance;
Step four, an algorithm model is established, and the voltage linear change of the linear Hall in the magnetic field range is utilized to convert the voltage linear change into the distance between the current Hall element and the permanent magnet, namely the specific position of the lens in the whole machine stroke;
fifthly, calibrating and confirming ADC values a and b of the closest point and the farthest point of the permanent magnet in the focusing process of the lens, recording parameters, comparing the voltage ADC values acquired in actual operation with the voltage ADC values a and b in calibration, and focusing the lens in a range between the closest point and the farthest point;
And step six, the motor control system judges whether the lens moves forwards or backwards according to the current position and the image blurring degree acquired by the camera.
2. The method for focusing a projector according to claim 1, wherein in the first step, the linear Hall and the permanent magnet are horizontally arranged along an axial direction of a lens of the projector.
3. The method of focusing a projector according to claim 1, wherein in the second step, the linear Hall is used for outputting an analog signal, i.e., a continuous voltage signal.
4. The method of focusing a projector according to claim 1, wherein in the third step, the output level of the linear Hall element is linearly related to the intensity of the externally applied magnetic field, and the linearity triggers a stroke according to the intensity of the magnetic field, i.e. the linear magnetic field range.
5. The method of claim 1, wherein in the fourth step, the algorithm model is based on a lens imaging formula and a linear relationship between Hall element voltage and object distance.
6. The method for focusing a projector based on linear Hall ranging according to claim 1, wherein in the fourth step, according to a lens imaging formula:
1/u+1/v=1/f;
Where u is the object distance, v is the image distance, f is the focal length, and the formula is changed to obtain:
u=fv/(v−f);
and then according to the linear relation between the object distance and the Hall element voltage:
u=k1×Vadc+k2;
Wherein V adc is the Hall element voltage, and can be obtained by combining a lens imaging formula:
k1×Vadc+k2=fv/(v−f);
After finishing, the following steps are as follows:
Vadc=（fv-k2v+k2f）/（k1(v−f)))。
7. The method for focusing a projector based on linear Hall ranging according to claim 6, wherein in a projector scene, the difference between the image distance v and the focal length f is small relative to the image distance v, and the finishing formula is obtained:
Vadc=(fv-k2v+k2f)/(k1v);
Vadc=(f-k2)/k1+(k2f)/(k1v);
This can be achieved by:
Vadc=K1/v+K2;
the hall element voltage V adc is inversely proportional to the image distance V according to the formula.
8. The projector focusing method based on linear Hall ranging as set forth in claim 7, wherein the Hall element voltage V adc and the image distance V are actually measured to obtain a plurality of groups of corresponding values, and the least square method is used for solving K 1 and K 2.
9. The projector focusing method based on linear Hall ranging of claim 8, wherein when solving for K 1 and K 2, the equation is written as:
Vadc = K1×(1/v) + K2;
Taking 1/V as an independent variable and V adc as a dependent variable, solving K 1 and K 2 by using linear regression to obtain an algorithm model.
10. The method of focusing a projector according to claim 1, wherein in step six, the current position image is compared with the previous position image, and the motor control system determines whether the next step is forward or backward according to the change of definition.
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