Advantages of S-cube sensor core technology
We introduce unique S-cube core technologies and extensive support system.
Tri-axis Magnetic Sensors
Magnetic Sensor Technology
The detail of magnetic sensor technology
This page explains magnetic sensor technology used in S-cube products.
Used in AK0991x / AK0997x series
A Hall element is a device that uses the Hall effect. “Hall” came from Dr. Hall's name for discovering Hall effect. It is based on the phenomenon that the electromotive force appears in the direction orthogonal to both the current and the magnetic field when applying a magnetic field perpendicular to the current to the object through which current is flowing.
When a current is applied to a thin film semiconductor, a voltage corresponding to the magnetic flux density and its direction is output by the Hall effect. The Hall effect is used to detect a magnetic field, (shown in Figure 1).
Hall elements can detect a magnetic field even in the case of a static magnetic field with no change in magnetic flux density. Therefore, Hall elements are used in various applications, such as non-contact switches used in combination with magnets, angle sensors, and current sensors. Geomagnetic sensors using Hall elements are widely used in smartphones and other applications.
An element that detects a magnetic field using a material, that resistance changes when magnetic force is applied, is called a magnetoresistive, (MR), element.
Other than semiconductor magnetoresistive element, (SMR), there are three kinds of sensors as representative examples of the magnetoresistive element using a ferromagnetic thin film material such as anisotropic magnetoresistive element, (AMR), giant magnetoresistive element, (GMR), and tunnel magnetoresistive element, (TMR).
Tunnel Magnetoresistive Element (TMR)
Used in AK0994x series
In the case of a laminated film of ferromagnetic material, (pinned layer), insulator and ferromagnetic material, (free layer), the proportion of electrons passing through the insulator changes due to the tunnel effect and the resistance value changes depending on if the direction of magnetization of the pinned layer and the free layer are antiparallel (a) or parallel (b).
Tri-axis magnetic sensor
Magnetic fields of various magnitudes exist in the world. There are no products that can comprehensively measure magnetic fields of all magnitudes with a single sensor. The type of sensor depends not only on the magnitude of magnetic field to be measured, but also on applications. AKM has a lineup of three S-cube products that fit the size of magnetic field to be measured.
The AK0997x series is the most suitable sensor for measuring the large magnetic fields in milli-tesla range, such as those produced by magnets.
They have a wide measurement range and is designed to be difficult to overflow even when the magnet is installed close to the sensor. therefore, it is suitable for applications (e.g., opening and closing detection applications) to be used together with the magnet.
The AK0991x series is the most suitable sensors for measuring small magnetic fields in the micro-tesla range, such as geomagnetism.
They are used as electronic compasses for heading-up applications in map application such as smartphones.
The AK0994x series is the most suitable sensor for measuring the minimum magnetic field in the nano-tesla range.
We believe that it can also detect very small magnetic fields, such as those generated by weak magnetic materials and the Villari phenomenon (reverse magnetostriction effect) and can therefore be used in application such as torque sensors and micro-metal strip detection.
The detail of S-cube's software technology
This page explains the Dynamic Offset Estimation used in combination with AK0991x series products.
Issue in electronic compass applications
The electronic compass is used to detect the direction that users are facing in a smartphone map application. However, the correct direction may not be obtained due to the magnetic parts used inside the phone. For example, parts using magnets, such as speakers, are subject to magnetic offsets, which can adversely affect the electronic compass (azimuth errors). In order to eliminate azimuth errors caused by the offset magnetic field, the effect of offset magnetic field must be removed from the data measured by sensors and adjusted. To solve this issue, a technique for accurately separating the offset magnetic field from the geomagnetism is required.
What is DOE?
AKM has developed a technology (DOER) that separates the offset magnetic field from the weak geomagnetism and automatically adjusts the effect of offset magnetic field. DOER focuses on the distribution of geomagnetic data on the surface of a sphere around an offset magnetic field as the terminal moves naturally (vertically, horizontally, tilting, etc.) when using a smartphone.
By estimating and adjusting the magnitude of the offset magnetic field (Center of distribution: O) from the magnetic field data (distribution data P1 to P5) when the smartphone is in various orientations, the azimuth angle with less error can be calculated. Even if the magnitude of offset magnetic field changes during use, DOER is a robust tuning algorithm because it can be tuned to follow the changes.
In addition to expanding sales of AK0991x series, DOER has been used in many mobile phones, smartphones, and tablets around the world. In recognition of these achievements, in 2012 AKM received the "ONSHI Invention Award" from the Institute of Invention, which is the highest award for inventions nationwide, sponsored by the Institute of Invention.
S-cube customer support
Customer Supports for Considering S-cube Sensors
Evaluation kits and control software are prepared so that various types of S-cube sensors can be easily evaluated and examined by customers. A probe type evaluation board with sensors mounted on a flexible substrate is also prepared. The product can be easily verified by mounting it on an existing product housing, so that development can be speeded up.
For a proper magnetic sensor operation of the customer's product, it is important to arrange the device, magnets, and magnetic parts. AKM provides optimal parts layout support to customers through its know-how accumulated through many years of experience.
AKM supports customers with magnetic simulations, such as the fact that we cannot verify the actual machine because of the lack of components at the product concept stage, the desire to verify the principle of the performance of the magnets that are scheduled to be used, and the desire to observe the effects of magnetic materials.
AKM develops drivers to use sensors on various platforms/OSs and also develops GUIs and software algorithms to maximize S-cube sensor capability on applications.
AKM has established a system that allows customers to continue to supply everything from niche applications, where shipments are low, to applications, such as smartphone components, where sudden and enormous quantities are required.