KR-102962245-B1 - TEMPERATURE CONTROL FOR HALL BAR SENSOR CORRECTION

Abstract

A system and method for eliminating or mitigating T-effects on a Hall sensor are disclosed. The system comprises a magnet-coil device for providing relative movement between them to obtain a relative position, a Hall sensor for detecting relative movement, a temperature sensor located near the Hall sensor for providing temperature detection, and a controller configured to provide a temperature correction input to the Hall sensor to compensate for a temperature effect on the Hall sensor detection based on the temperature detection, and having two or more channels coupled to the Hall sensor and the temperature sensor.

Inventors

• 코왈, 이프타
• 쉐러, 미카엘

Assignees

• 코어포토닉스 리미티드

Dates

Publication Date

20260508

Application Date

20210404

Priority Date

20200426

Claims (20)

1. As a camera actuator, Magnets and coils that operate to be movable relative to each other through relative movement and to provide a relative position between them; A Hall sensor located inside the coil to detect the relative movement of the magnet and the coil; A temperature sensor located inside the coil to provide temperature detection; and A camera actuator controller coupled to the above-mentioned Hall sensor and having a plurality of sensor channels, wherein each sensor channel includes a voltage sensing module and a current module, and the camera actuator controller and the temperature sensor are operatively coupled through an unused sensor channel; Includes, Here, the camera actuator controller is configured to control the relative movement by controlling the current flow through the coil and to provide a temperature correction input to the Hall sensor based on the temperature detection to compensate for the temperature effect on the Hall sensor detection. Here, the voltage sensing module and the current module of the unused sensor channel are electrically coupled to each other, and Here, the camera actuator is a camera actuator that operates to actuate movement for focusing or optical image stabilization.
2. In paragraph 1, the above-mentioned actuated movement is a camera actuator in which the movement of the lens is a movement.
3. In paragraph 1, the actuated movement is a camera actuator in which the movement of a reflective element is a movement.
4. In claim 1, the temperature sensor is a camera actuator that is a semiconductor diode.
5. In claim 1, the temperature sensor is a thermistor camera actuator.
6. In claim 1, the magnet and the coil are a camera actuator included in a voice coil motor.
7. In claim 1, the magnet and the coil are a camera actuator included in a stepper motor.
8. A camera actuator according to claim 1, further comprising at least one additional temperature sensor to form a plurality of temperature sensors.
9. In claim 8, the temperature correction is a camera actuator based on temperature detection of at least two of the plurality of temperature sensors.
10. In claim 1, the camera actuator controller is a camera actuator having three channels.
11. In claim 1, the camera actuator controller is a camera actuator having four or more channels.
12. In claim 1, the camera actuator controller is a camera actuator having a built-in Hall signal processing circuit.
13. In claim 1, the camera actuator controller is a camera actuator having an area smaller than 25 mm² .
14. In claim 1, the camera actuator controller is a camera actuator having an area smaller than 15 mm² .
15. In claim 1, the camera actuator controller is a camera actuator having a length in the range of 1 mm to 5 mm, a width in the range of 1 mm to 5 mm, and a height in the range of 0.3 mm to 1 mm.
16. In claim 1, the Hall sensor and the temperature sensor are thermally coupled to a camera actuator.
17. In claim 1, the camera actuator controller is a camera actuator that is an independent component.
18. In claim 1, the camera actuator controller is a camera actuator integrated into another electronic component.
19. In any one of claims 1 to 17, the camera actuator is a camera actuator included in a mobile device.
20. In paragraph 19, the mobile device is a camera actuator that is a smartphone.

Description

Temperature Control for Hall Bar Sensor Correction Cross-reference regarding related applications This application claims the benefit of priority of U.S. provisional application No. 63/015,576 filed on April 26, 2020, which is incorporated herein by reference in its entirety. The embodiments disclosed in this specification relate to a voice coil motor (VCM) in a small portable electronic device such as a smartphone, tablet computer, or laptop, and in particular to compensating for the effect of heat (temperature) on a sensor that measures motion or movement operated by such VCM. Cameras embedded in various mobile electronic devices, such as smartphones, tablet computers, and laptops, use small, compact actuators for various movements (e.g., rotation, tilting, movement, etc.) of various elements, such as lenses and reflective elements. These actuators are often composed of voice coil motors (VCMs) or stepper motors. In particular, VCMs are used for moving lenses and moving reflective elements ("folded" cameras) for focusing and/or lenses for optical image stabilization (OIS). A VCM comprises at least one magnet-coil pair. FIG. 1 schematically illustrates (a) a top view and (b) a side view (cross-sectional view) of an exemplary VCM numbered 100, which comprises a magnet (102), a coil (104), and a Hall bar sensor (or simply "Hall sensor" or "Hall bar") (106). During operation controlled by a controller (not shown herein), the magnet and the coil perform relative movement between them (e.g., in the X direction in the illustrated XY plane), which is driven by a current passing through the coil. The position of the magnet relative to the coil is measured by a Hall sensor and read by the controller. In some embodiments, the Hall sensor is located within the coil as in FIG. 1. Measurements by the Hall sensor are affected by changes in temperature ("T"). An increase in T is caused by the current driven through the coil and the heat generated around the various parts of the camera and/or the VCM. In a VCM such as 100, a typical increase in T at a location within the coil, such as the location of the Hall sensor (106), can be 10-75 degrees or more. For a typical Hall sensor, an increase in T of 100 degrees can cause the output voltage to decrease by 3-10%. For example, assuming (1) a T increase of 50 degrees, (2) a Hall sensor that experiences a 6% output voltage decrease over 100 degrees, and (3) linear behavior of this decrease over a 100-degree range, a 3% output voltage decrease can be expected. This 3% decrease can be a significant obstacle for applications such as OIS or autofocus (AF) cameras that typically require a travel range of 0.3-1 mm or an accuracy of a few micrometers (μm) in a "stroke." The T-effect on Hall sensor position measurement is an undesirable and harmful effect, particularly affecting the repeatability of the Hall sensor output with respect to magnetic flux. If the T-effect on Hall sensor position measurement is eliminated or at least mitigated, the positioning accuracy of camera components (e.g., lenses) operated by the VCM can be improved. It is necessary to eliminate or at least mitigate the T-effect on the Hall sensor in the VCM, and this would also be advantageous. Non-limiting examples of the embodiments disclosed herein are described below with reference to the drawings attached herein, which are listed following this paragraph. Identical structures, elements, or parts appearing in one or more drawings are generally indicated by the same number in all drawings in which they appear. The drawings and descriptions are intended to illuminate and clarify the embodiments. FIG. 1 schematically illustrates an exemplary VCM in (a) a plan view and (b) a cross-sectional view. FIG. 2 illustrates an embodiment of the system disclosed herein, comprising a Hall sensor, a temperature sensor, and a controller. FIG. 3 schematically illustrates an embodiment of a VCM having T-compensation for Hall sensor detection drift disclosed in this specification in (a) a plan view and (b) a cross-sectional view. Figure 4 illustrates the internal layout of the controller in the system of Figure 2. FIG. 5 illustrates an example of the method disclosed in this specification as a flowchart. The camera actuator controller has analog circuitry for connecting to Hall sensors. As described above, the Hall sensor channel includes an input voltage sense and an output constant current source. Some camera actuator controllers have spare channels ("unused channels") for additional Hall sensors that are not in use. Now, referring to FIG. 2, FIG. 2 illustrates an embodiment of a system (200) comprising a Hall sensor (202), a temperature sensor (204) ("T-sensor"), and a controller (also referred to as a "microcontroller" or "MCU") (206). The controller (206) is, for example, a Hall sensor controller or a VCM controller used in a digital camera. The controller (206) includes a plurality of sensor channels (206a, 206b...206n). Each