Lens fast return method and optical zoom system with lens fast return

Abstract

This invention discloses a method for rapid lens reset and an optical zoom system for rapid lens reset. The reset method includes: installing a photoelectric detection module at the zero-point position of the lens group; acquiring the stepping value of the stepper motor when the lens group last stopped moving as the initial stepping value; determining whether the lens group needs to perform high-speed stepping based on the offset of the initial stepping value relative to the zero-point stepping value; if so, determining the first stepping direction and the first stepping value of the lens group in the high-speed stepping phase, and driving the stepper motor to drive the lens group to step at high speed along the first stepping direction until the first stepping value is reached; otherwise, driving the stepper motor to drive the lens group to step towards the zero-point position at low speed until the photoelectric detection module detects the lens group and stops moving. In this invention, by adding a long-distance high-speed cruising phase during the lens group reset process, time wasted on low-speed detection over long distances is avoided, thereby significantly improving overall efficiency.

Description

Technical Field

[0001] This invention belongs to the field of optical zoom systems, and in particular relates to a method for rapid lens reset and an optical zoom system for rapid lens reset. Background Technology

[0002] Currently, in consumer electronic devices equipped with optical zoom lenses, there are two interconnected deep-seated design contradictions in the design and algorithm strategies of their reset systems: one is the inherent defect in the mechanical layout of the reset zero point, and the other is the difficult trade-off between accuracy and efficiency in the zero-finding algorithm. Specifically, existing solutions generally set the mechanical zero point of the optical system at the physical endpoint of the lens group's movement stroke. This seemingly straightforward layout has a fundamental drawback. For example, if the lens group happens to be at an end far from the zero point before reset, in this worst-case scenario, the reset time will be rigidly limited by the entire mechanical travel length that the lens group needs to traverse.

[0003] Meanwhile, to ensure accurate capture of the zero-point signal from an unknown starting position, traditional reset algorithms, concerned about stepper motor inertial overshoot, are forced to adopt an extremely conservative "low-speed blind scanning" strategy. This strategy requires the motor to pause after each step to wait for the photoelectric sensor to complete signal detection and decision, creating an inefficient "one step, one stop" loop. When the initial position of the lens group is far from the zero point, the cumulative delay of this serial operation is drastically amplified, which, combined with the limitations of mechanical travel, results in an unacceptably long reset wait. In products such as smartphones and drones that demand instantaneous response, this delay directly translates into perceptible operational stickiness and a disconnect in the user experience. In a highly competitive market, this can severely impact a product's core competitiveness and user satisfaction. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a lens fast reset method and an optical zoom system for lens fast reset.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for quickly resetting a lens includes the following steps: S100. Install a photoelectric detection module at the zero point of the lens group; S200: Obtain the step value of the stepper motor when the lens group stopped moving last time as the initial step value; S300: Define the step value corresponding to the zero position of the lens group as the zero step value. Determine whether the lens group needs to perform high-speed stepping based on the offset of the initial step value relative to the zero step value. If so, execute step S400; otherwise, directly execute the next step after step S400. S400: Determine the first step direction and the first step value of the lens group in the high-speed stepping stage, and make the stepper motor drive the lens group to step at high speed along the first step direction until the first step value is reached. S600: The stepper motor drives the lens group to move at a low speed towards the zero position until the photoelectric detection module detects the lens group and stops moving.

[0006] Furthermore, the photoelectric detection module includes a photodiode and a matching grating structure fixedly installed at the zero point position of the lens group. When a jump in the level of the photodiode is detected, it is determined that the photoelectric detection module has detected the lens group.

[0007] Furthermore, in step S600, the level of the photodiode is detected once every time the stepper motor moves one step.

[0008] Furthermore, when the stepper motor drives the lens group using high-speed stepping, the stepping speed is 1500-2000pps; when the stepper motor drives the lens group using low-speed stepping, the stepping speed is 200-300pps.

[0009] Furthermore, the zero point of the lens group is set in the middle area of ​​the lens group's movement stroke.

[0010] Furthermore, the offset of the initial step value relative to the zero-point step value is defined as N, and a safety buffer step number B is preset. In step S300, the method for determining whether the lens group needs to perform high-speed stepping is as follows: When |N|>B, determine whether the lens group needs to perform high-speed stepping; when |N|≤B, determine that the lens group does not need to perform high-speed stepping.

[0011] Furthermore, in step S400, the method for determining the first step direction is as follows: When N is greater than 0, the first stepping direction corresponds to the reverse direction of the stepper motor; when N is less than 0, the first stepping direction corresponds to the forward direction of the stepper motor. The formula for calculating the first step value, step1, is: step1 = |N| - B.

[0012] Furthermore, the following steps should be performed before executing step S600: S500: The stepper motor drives the lens group to step towards the zero position at a medium speed along the second direction until the photoelectric detection module detects the lens group and stops moving; the second direction is the same as the first direction. The direction of movement of the lens group in step S600 is defined as the third direction, which is opposite to the second direction.

[0013] Furthermore, when the stepper motor drives the lens group using medium-speed stepping, the stepping speed is 600-1000pps.

[0014] An optical zoom system with fast lens reset, comprising Lens group; Stepper motors are used to drive the movement of the lens group; The photoelectric detection module is used to detect whether the lens group has moved into place; The memory is used to store the step value of the stepper motor when the lens group last stopped moving; and A control unit is used to move the lens group to the zero position using the lens quick reset method as described in any of the above.

[0015] This invention decouples and reconstructs the traditional continuous uniform speed scanning reset mode scheme, dividing the entire reset journey into three independent optimized sub-processes: long-distance high-speed cruise, short-distance medium-speed acquisition, and extremely short-distance low-speed fine calibration. These three sub-processes are logically independent and precisely matched in terms of control parameters. Through this three-stage optimization, most of the reset journey is completed at high speed, while the low-speed, time-consuming precision detection and calibration processes are strictly compressed into a final, extremely short physical distance. This significantly shortens the total reset time without sacrificing final positioning accuracy and system robustness, thereby significantly improving the device's perceived response speed and user experience. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of an embodiment of the lens quick reset method of the present invention.

[0017] Figure 2 This is a flowchart of another embodiment of the lens quick reset method of the present invention.

[0018] Figure 3 This is a structural block diagram of the optical zoom system for rapid lens reset according to the present invention. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0020] Please see Figure 1 , Figure 1This is a flowchart of an embodiment of the lens quick reset method of the present invention. The lens quick reset method of this embodiment includes the following steps: S100. Install a photoelectric detection module at the zero-point position of the lens group. The lens group is a combination of optical lenses that move as a whole, and is the optical core of the lens. The zero-point position refers to the absolute reference position defined for the movement of the lens group, used for position calibration and movement initiation. In this embodiment, the zero-point position of the lens group is set in the middle region of the lens group's movement stroke (i.e., the region outside the beginning and end of the lens group's movement stroke). Preferably, the zero point of the lens group is set at the midpoint of the lens group's movement stroke. For example, if the total stroke of the stepper motor is S steps, the zero point of the lens group can be set at the position of S / 2 steps.

[0021] In current mainstream engineering practices, this critical zero point is generally set at the physical endpoint of the sliding guide rail of the lens group, i.e., the beginning or end of the stroke. This "endpoint zero point" layout is the simplest in mechanical design, and the physical boundary can be directly defined through the limiting structure. However, this setting also has a fundamental drawback: it strongly binds the worst-case reset time to the total length of the mechanical stroke. When the system starts up or needs recalibration, if the lens group happens to be at the end far from the zero point, the drive mechanism will be forced to drive the lens group across the entire stroke, resulting in an inherent delay determined by the mechanical dimensions that cannot be optimized by algorithms. Therefore, in this embodiment, by optimizing the zero point position, the reset efficiency can be freed from mechanical constraints.

[0022] The photoelectric detection module is used to detect the lens group to determine whether the lens group has moved to the zero position. In this embodiment, the photoelectric detection module includes a photodiode and a matching grating structure fixedly installed at the zero position of the lens group. When a jump in the level of the photodiode is detected, it is determined that the photoelectric detection module has detected the lens group.

[0023] The photoelectric detection module can be triggered by either light transmission or light blocking. This is achieved by creating a specially shaped light-transmitting hole or light-blocking block on the grating structure at a location corresponding to the zero-point position. For example, when using light transmission triggering, if the lens group is outside the zero-point position, the opaque part of the grating structure blocks the photodiode, resulting in a low-level output. The lens group moves related components, and the grating structure slides relative to the sensor. When the lens group reaches the zero-point position, the special light-transmitting hole on the grating structure rotates or slides directly above the photodiode. At this point, light passes through the hole and illuminates the photodiode, causing a steep voltage level transition.

[0024] S200: Obtain the step value of the stepper motor when the lens group last stopped moving (i.e., the step value corresponding to the position of the lens group before reset) as the initial step value. In this embodiment, a key preliminary step before the system executes the reset process is to obtain and record the step value corresponding to the stepper motor when the lens group last stopped moving, using this as the initial step value for reset. Essentially, this is a digital mapping of the lens group's spatial position. The optical zoom system can save the current step count of the stepper motor at the end of the last normal working cycle using its internal non-volatile memory. When a reset is started or triggered, the optical zoom system first reads the stored step value to accurately determine the previous known position of the lens group in its mechanical travel. This step transforms the original completely unknown position search into a positioning problem with a known approximate starting point, laying a crucial data foundation for subsequent adoption of more efficient reset strategies (such as segmented speed change and predictive approximation). This eliminates the need for the system to start a low-speed blind scan from the theoretically farthest point, significantly reducing the invalid travel and time overhead of the reset process.

[0025] S300: Define the step value corresponding to the zero-point position of the lens group as the zero-point step value. Based on the offset of the initial step value relative to the zero-point step value, determine whether the lens group needs to perform high-speed stepping. If so, execute step S400; otherwise, directly execute the next step after S400. Generally, when the offset of the initial step value relative to the zero-point step value is large, it is determined that the lens group needs to execute step S400 for high-speed stepping; when the offset of the initial step value relative to the zero-point step value is small, it is determined that the lens group does not need to execute step S400, i.e., high-speed stepping is not required.

[0026] Because stepper motors have a step loss problem, the step value of a stepper motor is not a completely reliable value and can only be used as a reference. To prevent the lens group from crossing the zero point during high-speed movement when moving directly based on the offset of the initial step value relative to the zero-point step value, a safety buffer step number B can be preset. The value of the safety buffer step number B should generally not be too small, otherwise, the step loss due to impacts, weightlessness, etc., may be too large, causing the zero-point algorithm to fail; for example, B=100 can be set. In this step, the method for determining whether the lens group needs to perform high-speed stepping can be: When |N|>B, it indicates that the initial step value is significantly offset from the zero-point step value. Therefore, it is possible to move the lens group at high speed first and then to a position closer to the zero point to save reset time. Thus, it is necessary to determine whether the lens group needs to perform high-speed stepping.

[0027] When |N|≤B, it indicates that the offset of the initial step value relative to the zero-point step value is small. If high-speed movement is used, the zero point may be missed. Therefore, it is determined that the lens group does not need to perform high-speed stepping.

[0028] The high-speed phase in this embodiment aims to move the lens group to a region very close to the zero point in the shortest possible time. Since the stepper motor cannot accurately obtain the step value at high speed, after setting the safety buffer step number B, there is no need to worry about missing the zero point during high-speed movement, because the lens group will inevitably not have entered the detection area of ​​the photoelectric detection module by the end of the high-speed movement.

[0029] S400: Determine the first stepping direction and the first stepping value of the lens group during the high-speed stepping phase, and drive the lens group with the stepper motor to step at high speed along the first stepping direction until the first stepping value is reached. In this step, "high speed" refers to a stepping speed much greater than the stepping speed during lens group reset in existing technologies. For example, when the stepper motor drives the lens group to step at high speed, the stepping speed can be 1500–2000 pps; preferably, the fastest speed supported by the stepper motor in the actual project is used, for example, 2000 pps.

[0030] In this step, the first step direction can be determined using the following method: Define the offset of the initial step value relative to the zero step value (i.e., the initial step value - the zero step value) as N, where the step value corresponding to the beginning of the movement of the lens group is 0, and the step value corresponding to the end of the movement of the lens group is S.

[0031] When N is greater than 0, it means that the lens group is located between the zero point position and the end of the lens group's movement stroke. When the lens group is reset, it needs to move to the beginning of the movement stroke, which means that the stepper motor needs to rotate in the opposite direction. At this time, the first step direction corresponds to the reverse direction of the stepper motor.

[0032] When N is less than 0, it means that the lens group is located between the zero point position and the beginning of the movement stroke of the lens group. When the lens group is reset, it needs to move to the end of the movement stroke, that is, the stepper motor needs to rotate in the forward direction. At this time, the first step direction corresponds to the forward direction of the stepper motor.

[0033] The formula for calculating the first step value, step1, can be: step1 = |N| - B Since this step is only executed when |N|>B, it can be ensured that step1>0.

[0034] This step is equivalent to coarsely adjusting the position of the lens group. By rapidly moving the lens group towards the zero point, it can quickly move the lens group to the vicinity of the zero point, thus achieving rapid pre-positioning of the lens group.

[0035] Please see Figure 2 Before executing step S600, you can first perform the following steps: S500: The stepper motor drives the lens group to step towards the zero position at a medium speed along the second direction until the photoelectric detection module detects the lens group and stops moving. Since a safety buffer step number B is set, the lens group will not cross the zero point during high-speed movement; therefore, the second direction is the same as the first direction. If step S400 is not executed, the first direction will not be determined. In this case, the second direction can be determined using the same method as determining the first direction. The medium speed in this step refers to a stepping speed that is significantly lower than high speed but greater than low speed. When the stepper motor drives the lens group at a medium speed, the stepping speed can be 600–1000 pps; preferably 800 pps, meaning that a level change detection is performed approximately every 10 steps.

[0036] After the rapid pre-positioning in the previous step, the lens group is within step B of the zero point. At this point, the movement speed of the lens group is reduced, and it continues to move in the same direction while the photodiode level is monitored in real time. Once a level change is detected, it means the lens group has crossed the zero point; at this point, the stepper motor immediately stops. Since the movement speed of the lens group is moderate at this time, the overshoot is controllable, and the stopping position of the lens group can be recorded as the "suspected zero point" P. Through this method, the zero point position can be captured, laying the foundation for subsequent position fine-tuning.

[0037] S600: The stepper motor drives the lens group to move at a low speed towards the zero position until the photoelectric detection module detects the lens group and stops moving. When the stepper motor drives the lens group at a low speed, the stepping speed can be 200-300 pps; preferably, the lowest speed supported by the stepper motor in the actual project, such as 200 pps, is used. During this process, the photodiode level is detected after each step, similar to the movement method used when the lens group is reset in existing technology, thereby precisely calibrating the position of the lens group. When the level changes again, this position is the precise zero position Z0. The low-speed movement in this step completely eliminates the risk of overshoot, ensuring a reset accuracy of ±1 step.

[0038] The direction of movement of the lens group in step S600 can be defined as the third direction; when step S600 is executed after step S500 is executed, the third direction is opposite to the second direction.

[0039] Of course, if step S500 is not performed before step S600, that is, if the capture process is skipped after high-speed coarse adjustment and the fine-tuning stage is entered directly, the third direction is the same as the first direction since the lens group has not yet crossed the zero point. That is, during fine-tuning, the lens group still moves towards the zero point along the direction of high-speed movement until the zero point is detected. In this case, the reset time can still be greatly reduced by the high-speed movement, but the movement time in the low-speed stage will be longer than that of the scheme that increases the capture stage.

[0040] This embodiment decouples and reconstructs the traditional continuous uniform speed scanning reset mode scheme. The originally simple and conservative "low-speed blind scan" process is broken down into three independent, dynamically adapted control stages based on the different displacement ranges and target accuracy, thus achieving a qualitative leap in efficiency. Specifically, the algorithm divides the entire reset stroke into three logically independent and precisely adapted optimization sub-processes: long-distance high-speed cruising, short-distance medium-speed acquisition, and extremely short-distance low-speed fine-tuning.

[0041] During the long-distance, high-speed cruising phase, the approximate direction and distance from the initial position to the target zero point are calculated based on the historical step values ​​read and recorded in non-volatile memory. Subsequently, the stepper motor drives the lens array to move rapidly at high speed. The core objective of this phase is to maximize the consumption of unnecessary travel while ensuring mechanical safety, avoiding any wasted time in non-critical sections. The algorithm's control logic focuses on speed and displacement, completely shielding the detection of the zero-point signal, thereby achieving near-blind high-speed traversal.

[0042] During the close-range, medium-speed acquisition phase, the lens array has entered a preset warning zone near the zero point. At this point, the stepper motor smoothly reduces the speed of the lens array from high speed to medium speed, and the zero-point signal detection function is reactivated. The goal of this phase is to begin acquiring the zero-point position while maintaining a relatively fast movement speed, preparing for final precise positioning. It effectively balances positioning speed and acquisition reliability, avoiding the risk of exceeding the zero point at high speed.

[0043] During the extremely short-distance, low-speed fine-calibration phase, since the zero-point position has already been captured, the stepper motor switches to an extremely low speed setting to move the last few steps precisely at low speed. The core task of this phase is to eliminate inertial overshoot, overcome mechanical hysteresis, and, based on the high-resolution signal characteristics, finally lock the lens group at the sub-micron absolute zero-point position, ensuring that the reset accuracy meets the design requirements of the optical system.

[0044] Through the above three-stage optimization, this embodiment fundamentally changes the control paradigm of the reset process. Most of the reset stroke is completed at high speed, while the low-speed, time-consuming precision detection and calibration processes are strictly compressed into a final, extremely short physical distance. This "division of labor and cooperation, step-by-step convergence" strategy, without sacrificing final positioning accuracy and system robustness, achieves an extreme reduction in total reset time compared to the traditional "low-speed throughout, stop-and-go" approach, significantly improving the device's perceived response speed and user experience.

[0045] Please see Figure 3 , Figure 3This is a structural block diagram of the optical zoom system for rapid lens reset according to the present invention. A preferred embodiment of the optical zoom system for rapid lens reset of the present invention includes a lens group, a stepper motor, a photoelectric detection module, a memory, and a control unit. The stepper motor is used to drive the lens group to move; for example, the stepper motor can drive the lens group to move via a precision threaded rod.

[0046] The photoelectric detection module is used to detect whether the lens group has moved into place. In this embodiment, the photoelectric detection module includes a photodiode and a matching grating structure fixedly installed at the zero point position of the lens group. When a jump in the level of the photodiode is detected, it is determined that the photoelectric detection module has detected the lens group. In this embodiment, the zero point position of the lens group is set in the middle region of the lens group's movement stroke, preferably at the midpoint of the lens group's movement stroke.

[0047] The memory is used to store the step value of the stepper motor when the lens group last stopped moving. The memory can be a non-volatile memory, which can save the current step count of the stepper motor at the end of the last normal working cycle. When started or triggered for reset, the optical zoom system first reads the stored step value to accurately determine the previous known position of the lens group in the mechanical travel.

[0048] The control unit is used to move the lens group to the zero position using the lens rapid reset method described in any of the above embodiments. Specifically, it first retrieves the stepping value of the stepper motor when the lens group last stopped moving from the memory as the initial stepping value. Then, it determines whether the lens group needs to perform high-speed stepping based on the offset of the initial stepping value relative to the zero-point stepping value. If so, it determines the first stepping direction and the first stepping value of the lens group in the high-speed stepping phase, and drives the stepper motor to drive the lens group to step at high speed along the first stepping direction until the first stepping value is reached. If high-speed stepping is not required, the above steps are skipped.

[0049] Next, the stepper motor drives the lens group to step at a medium speed along a second direction (the same as the first direction) towards the zero position until the photoelectric detection module detects the lens group and stops moving. Finally, the stepper motor drives the lens group to step at a low speed along a third direction (opposite to the second direction) towards the zero position until the photoelectric detection module detects the lens group and stops moving. Alternatively, the medium-speed stepping step can be omitted, and the stepper motor can directly drive the lens group to step at a low speed along a third direction (the same as the first direction) towards the zero position until the photoelectric detection module detects the lens group and stops.

[0050] In this embodiment, the lens group reset process is decoupled into three independent optimized sub-processes: long-distance high-speed cruise, short-distance medium-speed acquisition, and extremely short-distance low-speed fine calibration. This avoids wasting time on low-speed detection over long distances, thereby significantly improving overall efficiency.

[0051] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A method for rapid lens reset, characterized in that: Includes the following steps: S100. Install a photoelectric detection module at the zero point of the lens group; S200: Obtain the step value of the stepper motor when the lens group stopped moving last time as the initial step value; S300: Define the step value corresponding to the zero position of the lens group as the zero step value. Determine whether the lens group needs to perform high-speed stepping based on the offset of the initial step value relative to the zero step value. If so, execute step S400; otherwise, directly execute the next step after step S400. S400: Determine the first step direction and the first step value of the lens group in the high-speed stepping stage, and make the stepper motor drive the lens group to step at high speed along the first step direction until the first step value is reached. S600: The stepper motor drives the lens group to move at a low speed towards the zero position until the photoelectric detection module detects the lens group and stops moving.

2. The lens quick reset method as described in claim 1, characterized in that: The photoelectric detection module includes a photodiode and a matching grating structure fixedly installed at the zero point position of the lens group. When a jump in the level of the photodiode is detected, it is determined that the photoelectric detection module has detected the lens group.

3. The lens quick reset method as described in claim 2, characterized in that: In step S600, the level of the photodiode is detected once every time the stepper motor moves one step.

4. The lens quick reset method as described in claim 1, characterized in that: When the stepper motor drives the lens group using high-speed stepping, the stepping speed is 1500-2000pps; when the stepper motor drives the lens group using low-speed stepping, the stepping speed is 200-300pps.

5. The lens quick reset method according to any one of claims 1 to 4, characterized in that: The zero point of the lens group is set in the middle area of ​​the lens group's movement stroke.

6. The lens quick reset method as described in claim 5, characterized in that, The initial step value is defined as the offset of the zero-point step value as N, and a safety buffer step number B is preset. In step S300, the method for determining whether the lens group needs to perform high-speed stepping is as follows: When |N|>B, determine whether the lens group needs to perform high-speed stepping; when |N|≤B, determine that the lens group does not need to perform high-speed stepping.

7. The lens quick reset method as described in claim 6, characterized in that, In step S400, the method for determining the first step direction is as follows: When N is greater than 0, the first stepping direction corresponds to the reverse direction of the stepper motor; when N is less than 0, the first stepping direction corresponds to the forward direction of the stepper motor. The formula for calculating the first step value, step1, is: step1 = |N| - B.

8. The lens quick reset method as described in claim 7, characterized in that: Before performing step S600, perform the following steps: S500: The stepper motor drives the lens group to step towards the zero position at a medium speed along the second direction until the photoelectric detection module detects the lens group and stops moving; the second direction is the same as the first direction. The direction of movement of the lens group in step S600 is defined as the third direction, which is opposite to the second direction.

9. The lens quick reset method as described in claim 8, characterized in that: When the stepper motor drives the lens group, the stepping speed is 600-1000pps when using medium-speed stepping.

10. An optical zoom system for rapid lens reset, characterized in that: include Lens group; Stepper motors are used to drive the movement of the lens group; The photoelectric detection module is used to detect whether the lens group has moved into place; The memory is used to store the step value of the stepper motor when the lens group last stopped moving; as well as A control unit is used to move the lens group to the zero position using the lens rapid reset method as described in any one of claims 1 to 9.

Images