An auto-focusing method and an auto-focusing device

Abstract

The application discloses an automatic focusing method and an automatic focusing device. The automatic focusing device comprises a lens, a lens barrel, a controller and a driving device. The lens barrel is provided with a resistance strip, the lens is provided with a contact point in contact with the resistance strip, at least one end of the resistance strip is connected with the controller, and the contact point is connected with the controller. The controller is used for detecting a contact point voltage on the contact point, obtaining a current angle of the lens barrel according to the contact point voltage, and obtaining an angle difference required for the lens barrel to rotate according to an imaging angle and the current angle obtained in advance. The driving device is connected with the controller and is used for driving the lens barrel to rotate so as to reduce the angle difference. The contact point voltage detected by the controller changes along with the rotation of the lens barrel. In the above manner, the application can realize automatic focusing and reduce the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of projection technology, in particular to an automatic focusing method and an automatic focusing device. BACKGROUND

[0002] At present, most of the projection focusing can be realized by rotating the lens barrel, but the fast automatic focusing realized by measuring the projection distance needs to know the angle of the lens barrel rotation, and there is a problem of out-of-focus after the lens temperature rises, which needs to rotate the lens barrel again for adjustment; in addition, the projection distance can also be measured by using a distance sensor, and after knowing the angle position of the current lens, the direction and angle of rotation required at this time are calculated according to the lens focusing specifications, and then the motor drives the lens to quickly complete the automatic focusing, but the existing lens rotation angle is mostly realized by adjusting the motor step number, which needs to be sensed by the sensor the starting position of the motor, and has the problems of difficult elimination of structural gap, empty stroke of the motor and inaccurate calculation of the rotation angle, resulting in slow automatic focusing speed and poor experience, and the cost of externally installed angle sensor is high, and a new mechanism needs to be added to cooperate, which is easy to introduce new errors. SUMMARY

[0003] The present application provides an automatic focusing method and an automatic focusing device, which can realize automatic focusing and reduce cost.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is to provide an automatic focusing device, which comprises a lens, a lens barrel, a controller and a driving device, the lens barrel is provided with a resistance strip, the lens is provided with a contact point in contact with the resistance strip, at least one end of the resistance strip is connected with the controller, and the contact point is connected with the controller; the controller is used for detecting the contact voltage on the contact point, obtaining the current angle of the lens barrel according to the contact voltage, and obtaining the angle difference required for the rotation of the lens barrel according to the pre-acquired imaging angle and the current angle; the driving device is connected with the controller and is used for driving the lens barrel to rotate so as to reduce the angle difference; the contact voltage detected by the controller changes with the rotation of the lens barrel.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is to provide an automatic focusing method, which is applied to an automatic focusing device, the automatic focusing device comprises a lens, a lens barrel, a controller and a driving device, the lens barrel is provided with a resistance strip, the lens is provided with a contact point in contact with the resistance strip, at least one end of the resistance strip is connected with the controller, and the contact point is connected with the controller, the method comprises the following steps: detecting the contact voltage on the contact point by using the controller, and obtaining the current angle of the lens barrel according to the contact voltage; obtaining the angle difference required for the rotation of the lens barrel according to the pre-acquired imaging angle and the current angle by using the controller; controlling the driving device to drive the lens barrel to rotate by using the controller, so as to reduce the angle difference; wherein the contact voltage detected by the controller changes with the rotation of the lens barrel.

[0006] Through the above scheme, the beneficial effects of the present application are: the current angle of the lens barrel is detected through the resistance strip on the lens barrel and the contact on the lens, the contact and the resistance strip are in contact with each other, when the lens barrel rotates, the resistance strip moves with the contact, so that the contact position of the resistance strip changes, the controller can detect the voltage at the contact, and calculate the current angle corresponding to the current contact voltage by using the mapping relationship between the contact voltage and the current angle, and then calculate the angle difference required for the lens barrel to rotate by using the imaging angle and the current angle, the lens barrel rotates under the action of the driving device, so that the angle difference becomes smaller, so that the picture taken by the lens is clear, since the contact voltage changes with the rotation of the lens barrel, automatic focusing and clear imaging can be achieved, the structure is simple, no new mechanism is needed to cooperate with the contact or the resistance strip, no new error is introduced, and cost can be saved. BRIEF DESCRIPTION OF DRAWINGS

[0007] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0008] Figure 1 is a structural schematic diagram of an embodiment of the automatic focusing device provided by the present application;

[0009] Figure 2 is Figure 1 a schematic diagram of the contact and the resistance strip in the embodiment shown in FIG. 4;

[0010] Figure 3 is a structural schematic diagram of another embodiment of the automatic focusing device provided by the present application;

[0011] Figure 4 is Figure 3 a connection schematic diagram of the analog-to-digital converter, the power supply, the resistance strip and the temperature sensor in the embodiment shown in FIG. 5;

[0012] Figure 5 is a flow schematic diagram of an embodiment of the automatic focusing method provided by the present application. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0014] Please refer toFigure 1 , Figure 1 is a structural schematic diagram of an embodiment of the automatic focusing device provided in the present application, and the automatic focusing device comprises a lens 11, a lens barrel 12, a controller 13 and a driving device 14.

[0015] The lens 11 is of a telescopic structure, and a contact 111 is arranged on the lens 11, which can be a conductor and can be connected with the controller 13 through a wire.

[0016] The lens barrel 12 is connected with the lens 11, and an electric resistance strip 121 is arranged on the lens barrel 12 and in contact with the contact 111, at least one end of the electric resistance strip 121 is connected with the controller 13, and the contact 111 is connected with the controller 13; specifically, an inclined groove (not shown in the figure) is arranged on the lens barrel 12, the electric resistance strip 121 is attached to the side of the inclined groove, the contact 111 protruding from the lens 11 is embedded in the inclined groove and abuts against the electric resistance strip 121, the resistance value of the electric resistance strip 121 changes uniformly along with the length, which can be a carbon film or a resistance wire, and the opposite ends of the electric resistance strip 121 are respectively connected with wires, the electric resistance strip 121 moves along with the lens barrel 12 when the lens barrel 12 rotates, and the contact position of the contact 111 with the electric resistance strip 121 changes along with it; the controller 13 is used for detecting the contact voltage on the contact 111, and the contact voltage detected by the controller 13 changes along with the rotation of the lens barrel 12; for example, as shown in FIG. 1, at t1, the contact 111 is in contact with position A of the electric resistance strip 121, the resistance value corresponding to position A is R1, and the contact voltage detected by the controller 13 is recorded as U1; along with the rotation of the lens barrel 12, at t2, the contact 111 is in contact with position B of the electric resistance strip 121, the resistance value corresponding to position B is R2, and the contact voltage detected by the controller 13 is recorded as U2. Figure 2

[0017] The controller 13 is also used for obtaining the current angle of the lens barrel 12 according to the contact voltage, and obtaining the angle difference required for the rotation of the lens barrel 12 according to the imaging angle and the current angle of the lens barrel 12 obtained in advance; specifically, the angle difference is the angle that makes the imaging clear, there is a mapping relationship between the current angle of the lens barrel 12 and the contact voltage, the current angle can be calculated by the controller 13 according to the current contact voltage and the mapping relationship between the current angle and the contact voltage; and there is a mapping relationship between the current angle of the lens barrel 12, the imaging angle and the angle difference, the angle required for the current rotation of the lens barrel 12 can be calculated according to the mapping relationship among the three, the current angle and the angle difference, and the imaging of the lens 11 can be made clear after the lens barrel 12 is rotated.

[0018] ​The driving device 14 can be connected with the lens barrel 12, which is used to drive the lens barrel 12 to rotate so as to reduce the angle difference; in particular, the driving device 14 is connected with the controller 13, can receive the angle difference sent by the controller 13, and drive the lens barrel 12 to rotate, so that the lens barrel 12 rotates to drive the lens 11 to move forward and backward, realizes the automatic focusing, and clearly images.

[0019] In other embodiments, the angle difference can also be the angle position of the lens barrel 12, that is, the final angle of the lens barrel 12, and the implementation principle is similar to the above-mentioned embodiments, which will not be described here.

[0020] The embodiment provides an automatic focusing device, contacts 111 and resistance strips 121 are arranged on the lens 11 and the lens barrel 12 respectively, and the contacts 111 and the resistance strips 121 contact each other, when the lens barrel 12 rotates, the resistance strips 121 move together, so that the contact position of the contacts 111 and the resistance strips 121 changes, that is, the contact voltage changes, the controller 13 can detect the contact voltage, and calculate the current angle of the lens barrel 12 by using the contact voltage and the mapping relationship between the contact voltage and the current angle, and then calculate the angle required for the lens barrel 12 to rotate by using the imaging angle and the current angle, the lens barrel 12 rotates under the action of the driving device 14, so that the picture taken by the lens 11 is clear, since the contact voltage changes with the rotation of the lens barrel 12, automatic focusing can be realized, and clear imaging can be realized.

[0021] Please refer to Figure 3 , Figure 3 which is a structural schematic diagram of another embodiment of the automatic focusing device provided by the application, and the contact in the embodiment is a spring 222.

[0022] The spring 222 can press against the lens barrel 22 to prevent the clearance from appearing and generating positive and negative rotation idle stroke errors, and ensure the accurate mapping relationship between the contact voltage and the position of the contact 211; in particular, the spring 222 is arranged on the lens barrel 22, the spring 222 contacts the resistance strip 221 moving with the focusing, and the spring 222 can make the contact 211 and the resistance strip 221 in the inclined groove tightly cooperate; for example, as shown in Figure 4 The resistance value between the contact 211 and one end (B end) of the resistance strip 221 is denoted as R1, the contact voltage is denoted as U, and the angle of the lens barrel 22 is denoted as α, the resistance value R1 can continuously change, the contact voltage U can continuously change, and the angle α and the contact voltage U have a linear relationship, that is, α=AU, and A is a constant.

[0023] The controller 23 includes a detection circuit 231 and a processor 232 connected with each other, the detection circuit 231 is connected with the resistance strip 221, which is used to detect the contact voltage, and perform analog-to-digital conversion processing on the contact voltage to obtain a digital voltage.

[0024] In a specific embodiment, the detection circuit 231 comprises an analog-to-digital converter 2311 and a power supply 2312 connected to each other, the analog-to-digital converter 2311 is configured to convert the contact voltage into a first digital voltage and feed the first digital voltage back to the processor 232; specifically, the analog-to-digital converter 2311 can collect the contact voltage, and the angle of the lens barrel 22, i.e. the current angle, can be calculated by using the functional relationship between the angle of the lens barrel 22 and the contact voltage.

[0025] As shown in Figure 4 , the analog-to-digital converter 2311 comprises a first end, a second end and a third end, the first end of the analog-to-digital converter 2311 is connected to the power supply 2312, the second end of the analog-to-digital converter 2311 is connected to the contact 211, and the third end of the analog-to-digital converter 2311 is grounded; one end (B end) of the resistor strip 221 is grounded, the other end (C end) of the resistor strip 221 is connected to the power supply 2312, and the contact 211 is in contact with the position D on the resistor strip 221.

[0026] The processor 232 is connected to the detection circuit 231 and the driving device 24, and is configured to control the driving device 24 according to the digital voltage fed back by the detection circuit 231; specifically, the driving device 24 comprises a driver 241 and a motor 242 connected to each other, the driver 241 is configured to receive the angle difference sent by the processor 232 and drive the motor 242 according to the angle difference, so that the motor 242 drives the lens barrel 22 to rotate.

[0027] In another specific embodiment, as shown in Figure 3 , the lens 21 is further provided with a temperature sensor 212, the temperature sensor 212 can be used to detect the temperature of the lens 21, one end of the temperature sensor 212 is connected to the analog-to-digital converter 2311, and the other end of the temperature sensor 212 is grounded; specifically, as shown in Figure 4 , the temperature sensor 212 is connected to the fourth end of the analog-to-digital converter 2311, in order to prevent the current flowing through the temperature sensor 212 from being too large and causing damage to the temperature sensor 212, a current limiting resistor 2313 can be provided, one end of the current limiting resistor 2313 is connected to the power supply 2312, and the other end of the current limiting resistor 2313 is connected to the fourth end of the analog-to-digital converter 2311.

[0028] The analog-to-digital converter 2311 is further configured to convert the voltage on the temperature sensor 212 into a second digital voltage and feed the second digital voltage back to the processor 232, and the processor 232 is configured to calculate the compensation angle corresponding to the thermal decentering according to the second digital voltage.

[0029] Since the angle that needs to be compensated due to the thermal decentering of the lens 21 and the temperature change monotonically, the voltage of the lens 21 at different temperatures and the angle that needs to be compensated can be measured and stored.

[0030] With reference to Figure 3 The auto-focusing device further comprises a memory 25 connected with the processor 232, which is configured to store the voltage of the temperature sensor 212 at different temperatures and the corresponding compensation angle; specifically, the memory 25 can be an electrically erasable programmable read-only memory (EEPROM).

[0031] In a specific embodiment, the processor 232 is further configured to fit the data in the memory 25 to obtain a functional relationship between the voltage of the temperature sensor 212 and the compensation angle, and calculate the compensation angle corresponding to the voltage of the temperature sensor 212 by using the functional relationship; specifically, the temperature sensor 212 can be a thermistor, and the real-time temperature of the lens 21 can be determined according to the change of the voltage on the thermistor with temperature, and the angle that needs to be compensated at the current temperature can be calculated by cooperating with the fitted functional relationship.

[0032] In another specific embodiment, the processor 232 can establish a mapping table between the voltage of the temperature sensor 212 and the compensation angle by using the data in the memory 25, and find the corresponding compensation angle in the mapping table by using the voltage of the temperature sensor 212.

[0033] With reference to Figure 3 The auto-focusing device further comprises a distance measuring sensor 26 connected with the processor 232, which is configured to measure the projection distance between the lens 21 and the target object, and send the projection distance to the processor 232.

[0034] The processor 232 is further configured to obtain the imaging angle of the lens barrel 22 according to the projection distance and the design parameter of the lens 21, and calculate the angle difference by using the imaging angle, the current angle and the compensation angle; specifically, the design parameter can include the imaging angle, or the design parameter and the imaging angle have a mapping relationship, and the imaging angle corresponding to the design parameter can be obtained according to the mapping relationship between them.

[0035] In a specific embodiment, the processor 232 can calculate the angle difference by using the following formula:

[0036]

[0037] Wherein, is the angle difference, γ is the imaging angle, α is the current angle, and β is the compensation angle.

[0038] After the projection distance is acquired by the distance measuring sensor 26, the angle that the lens 21 can clearly image can be acquired according to the design parameters of the lens 21, the current angle of the lens barrel 22 can be calculated by the contact voltage, the compensation angle can be calculated by the voltage on the temperature sensor 212, then the motor 242 can be controlled to drive the lens barrel 22 to rotate, and the compensation angle can be adjusted again according to the real-time temperature of the lens 21 during subsequent work.

[0039] The automatic focusing device provided in the embodiment directly pastes the resistance strip 221 on the lens barrel 22, and assists the automatic focusing by detecting the rotation angle of the lens barrel 22, without adding new structures for cooperation, so that the structure is simple and the cost is low. The elastic sheet 222 can support the lens barrel 22 to prevent the gap from appearing to avoid the positive and negative rotation dead stroke error, reduce the influence of the structure cooperation gap, make the angle detection accurate, and can indicate the current angle of the lens barrel 22 in real time, and can detect the temperature of the lens 21 and cooperate with the projection distance, and can compensate the thermal defocus in real time.

[0040] Please refer to Figure 5 , Figure 5 is a flowchart of an embodiment of the automatic focusing device provided in the application. The method can be applied to the automatic focusing device shown in Figure 1 , the automatic focusing device includes a lens 11, a lens barrel 12, a controller 13 and a driving device 14, the lens barrel 12 is provided with a resistance strip 121, the lens 11 is provided with a contact 111 in contact with the resistance strip 121, at least one end of the resistance strip 121 is connected with the controller 13, the contact 111 is connected with the controller 13, and the method includes:

[0041] Step 51: detecting the contact voltage on the contact by the controller, and obtaining the current angle of the lens barrel according to the contact voltage.

[0042] The contact 111 is in contact with the resistance strip 121 on the lens barrel 12, since the controller 13 is connected with the contact 111, the voltage at the contact 111 (i.e. the contact voltage) can be detected by the controller 13, when the lens barrel 12 rotates, the resistance strip 121 rotates with the lens barrel 12, while the contact 111 is fixed in the rotation direction of the lens barrel 12, so that the contact position of the contact 111 and the resistance strip 121 changes with the rotation of the lens barrel 12, so that the contact voltage changes with the rotation of the lens barrel 12, since the contact voltage and the current angle of the lens barrel 12 have a mapping relationship, so that the controller 13 can obtain the current angle corresponding to the currently detected contact voltage by using the mapping relationship.

[0043] Step 52: obtaining the angle difference required for the lens barrel to rotate by the controller according to the imaging angle and the current angle.

[0044] After the current angle of the lens barrel 12 is calculated by the controller 13, the controller 13 can calculate the angle that the lens barrel 12 needs to rotate to make the image clear by using the current angle of the lens barrel 12 and the imaging angle of the lens barrel 12.

[0045] Step 53: The controller controls the driving device to drive the lens barrel to rotate to reduce the angle difference.

[0046] After the angle that the lens barrel 12 needs to rotate is calculated, the controller 13 can control the driving device 14, and the driving device 14 can receive the angle difference sent by the controller 13, so that the driving device 14 drives the lens barrel 12 to continue rotating. After the rotation of the lens barrel 12 reaches the angle difference, the driving device 14 stops working, thereby achieving focusing.

[0047] The embodiment provides a method for assisting automatic focusing by detecting the rotation angle of the lens barrel 12. The resistance strip 121 is attached to a specific position of the lens barrel 12, and the contact 111 is arranged at a specific position of the lens 11. When the lens barrel 12 rotates, the contact 111 continuously contacts different positions of the resistance strip 121. The controller 13 can detect the change of the voltage, thereby determining the current angle of the lens barrel 12. Then, the current angle and the imaging angle are used to calculate the angle that the lens barrel 12 needs to rotate, and the lens barrel 12 is driven to rotate, thereby achieving automatic focusing.

[0048] The above is only an embodiment of the application, and does not limit the patent scope of the application. Any equivalent structure or equivalent process transformation in the content of the specification and the drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. An auto-focusing device characterized by comprising: The automatic focusing device comprises a lens, a lens barrel, a controller and a driving device, the lens barrel is provided with a resistance strip, the lens is provided with a contact point in contact with the resistance strip, at least one end of the resistance strip is connected with the controller, and the contact point is connected with the controller; The controller is used for detecting a contact point voltage on the contact point, obtaining a current angle of the lens barrel according to the contact point voltage, and obtaining an angle difference required for rotation of the lens barrel according to a pre-acquired imaging angle and the current angle; The driving device is connected with the controller and is used for driving the lens barrel to rotate so as to reduce the angle difference; The contact point voltage detected by the controller changes with the rotation of the lens barrel.

2. The auto-focusing device according to claim 1, wherein The contact point is an elastic sheet which abuts against the lens barrel to prevent positive and negative rotation idle stroke errors.

3. The auto-focusing device according to claim 1, wherein The controller comprises: a detection circuit which is used for performing analog-digital conversion on the contact point voltage to obtain a digital voltage; a processor which is connected with the detection circuit and the driving device and is used for controlling the driving device according to the digital voltage fed back by the detection circuit.

4. The automatic focusing device according to claim 3, wherein the detection circuit comprises an analog-digital converter and a power supply which are connected with each other, the analog-digital converter is used for converting the contact point voltage into a first digital voltage and feeding back the first digital voltage to the processor; wherein the analog-digital converter comprises a first end, a second end and a third end, the first end of the analog-digital converter is connected with the power supply, the second end of the analog-digital converter is connected with the contact point, and the third end of the analog-digital converter is grounded; one end of the resistance strip is grounded, and the other end of the resistance strip is connected with the power supply.

5. The automatic focusing device according to claim 4, wherein the lens is further provided with a temperature sensor, one end of the temperature sensor is connected with the analog-digital converter, and the other end of the temperature sensor is grounded; the analog-digital converter is further used for converting a voltage on the temperature sensor into a second digital voltage and feeding back the second digital voltage to the processor; the processor is used for calculating a compensation angle corresponding to thermal defocus according to the second digital voltage.

6. The automatic focusing device according to claim 5, wherein the automatic focusing device further comprises a distance measuring sensor which is connected with the processor and is used for measuring a projection distance between the lens and a target object and sending the projection distance to the processor; the processor is further used for obtaining the imaging angle according to the projection distance and design parameters of the lens, and calculating the angle difference by using the imaging angle, the current angle and the compensation angle.

7. The automatic focusing device according to claim 6, wherein the processor calculates the angle difference by using the following formula: φ = γ - (α + β) wherein φ is the angle difference, γ is the imaging angle, α is the current angle, and β is the compensation angle.

8. The automatic focusing device according to claim 6, wherein The automatic focusing device further comprises a memory connected with the processor, used for storing the voltage of the temperature sensor at different temperatures and the corresponding compensation angle; The processor is further used for fitting the data in the memory to obtain a function relationship between the voltage of the temperature sensor and the compensation angle, and calculating the compensation angle corresponding to the voltage of the temperature sensor by using the function relationship; Or A mapping table between the voltage of the temperature sensor and the compensation angle is established by using the data in the memory, and the corresponding compensation angle is obtained by looking up the voltage of the temperature sensor in the mapping table.

9. The automatic focusing device according to claim 3, wherein The driving device further comprises a driver and a motor connected with each other, the driver is used for receiving the angle difference sent by the processor and driving the motor according to the angle difference, so that the motor drives the lens barrel to rotate.

10. An autofocusing method characterized by, The application is applied to an automatic focusing device, the automatic focusing device comprises a lens, a lens barrel, a controller and a driving device, the lens barrel is provided with a resistance strip, the lens is provided with a contact point in contact with the resistance strip, at least one end of the resistance strip is connected with the controller, and the contact point is connected with the controller, and the method comprises the following steps: The controller is used for detecting the contact point voltage on the contact point, and the current angle of the lens barrel is obtained according to the contact point voltage; The controller is used for obtaining the angle difference required for the rotation of the lens barrel according to the pre-acquired imaging angle and the current angle; The controller is used for controlling the driving device to drive the lens barrel to rotate, so that the angle difference is reduced; the contact point voltage detected by the controller changes with the rotation of the lens barrel.

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