04,01,2026 12 views
The direction of improvement for Hall sensor technology
As the information source of automotive electronic control systems, automotive sensors are key components of automotive electronic control systems.
With the development of society, traditional contact sensors continue to show their limitations. To compensate for the shortcomings of contact sensors, Hall sensors have been vigorously developed and widely used in electronic control systems due to their advantages such as non-contact, low power consumption, sturdy structure, and long lifespan. Nowadays, replacing traditional contact sensors with automotive Hall sensors has become a trend.
At present, due to the late start of automotive sensor technology in China, the overall level of the industry is still relatively low, and there is no series or matching, and no independent industry has been formed. Hall sensors, especially automotive sensors, still rely on imports.
At present, experts in the automotive Hall sensor industry believe that improvements in this field can be focused on three aspects: Hall element structure, integrated circuits, and packaging processes, which require more attention from relevant Chinese enterprises.
Hall element structures can be mainly divided into the following three types:
1. One dimensional Hall sensor for automobiles, used to measure the magnetic field perpendicular to the surface of the component, with low noise and high stability;
2. A two-dimensional Hall sensor for automobiles, which integrates two one-dimensional Hall elements on the chip, can simultaneously measure two components of the magnetic field on the same plane. Its major advantage is that the measurement angle is almost not affected by the position of the permanent magnet, allowing for relatively large packaging errors and temperature fluctuations;
3. Automotive 3D Hall sensors deposit a layer of magnetic collecting material on the surface of traditional CMOS chips, which can sense both vertical and parallel magnetic field strengths on the chip surface, achieving 360 degree measurement and amplifying the magnetic field in the Hall element area to improve sensitivity.
Optimizing integrated circuits mainly improves the accuracy of automotive Hall sensors by eliminating zero position errors and temperature compensation.
1. For eliminating zero position errors, a typical technique is redundant design, which uses two relatively biased Hall elements in parallel to cancel out the unequal potential and effectively improve the accuracy of the Hall sensor. Similar to its principle, it is also possible to use four Hall elements in parallel or multiple Hall elements in parallel;
2. For temperature compensation, on the one hand, resistors and other components can be set up to form a temperature compensation circuit, and on the other hand, temperature monitoring Hall elements can be configured near the detection Hall elements to cancel out the temperature characteristics of the Hall voltage through an operation circuit.
In improving the packaging process of automotive Hall sensors, the main focus is on accurately positioning each component and reducing the position error of Hall elements; Add soft magnetic components to improve sensor accuracy, such as placing a soft magnetic component on one side of the magnet between the magnet and the magnetic field sensitive component to minimize the offset of the magnetic field.
Application of Hall sensors in electric rearview mirrors for automobiles
The rearview mirror can help the driver obtain external information from the rear, sides, and below during driving, improving the safety of the vehicle on the road.
Due to the position of the external rearview mirror, geese are prone to collision accidents when the road is congested or the traffic space is narrow.
On the other hand, manually adjusting the external rearview mirror while driving can be very inconvenient, and it is also easy to cause traffic accidents due to the shift of attention.
The electric rearview mirror is driven by a motor, allowing the driver to adjust and fold it inside the car, effectively avoiding the aforementioned adverse situations.
The electric rearview mirror is mainly composed of two independent motors, as well as position detection components and control circuits for adjustment
Two independent motors provide power for the longitudinal (up and down) and lateral (left and right) movements of the rearview mirror, while the position detection component is responsible for transmitting current position and angle information to the control circuit to determine whether the adjustment is in place.
As a sensing element that detects position through induction of magnetic field changes, Hall sensors can measure the angle changes during the adjustment process of the rearview mirror, so that the control system can cut off the power supply to the adjustment motor when the rearview mirror is folded or unfolded to the preset position, preventing damage.
The Honeywell high-sensitivity digital latch type Hall sensor VF360ST is compact in size and powerful in function, and can operate in the magnetic field of permanent magnets or electromagnets.
VF360ST belongs to a bipolar Hall sensor that can respond to magnetic fields of the South Pole (S) or North Pole (N). VF360ST will turn on under an S-pole magnetic field, while VF360NT of the same series will turn on under an N-pole magnetic field. Compared with similar high-sensitivity, bipolar latch type Hall sensors that use chopper stabilization technology, the VF360ST's chopper free design makes the sensor's output more pure and the latch response time shorter.
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