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Part 2 of a Series

Minoru Yoshida
Sales & Marketing Headquarters
Mechatronic Devices Sales Dept.
Senior Staff
"Resistive sensors" of Alps Electric who offers excellent products with long life and thermal resistances on our well established variable resistor technology as its foundation


Our resistive sensors have the longest history and an outstanding reputation in our sensor business. The usage has continuously extended to various areas such as car electronics (automotive applications), on a solid foundation of variable resistor (potentiometer) technologies, cultivated long time for consumer applications such as audio equipment.

The usage of the sensor expands further from consumer electronics to automotive applications
Our resistive sensors have evolved in response to severe market needs, on our solid technological foundations in resistors and contact technologies accumulated long time for our variable resistors (potentiometer) for audio equipment, and receive high reputations in terms of their long life, thermal resistance, and reliability. The application areas have been successfully enlarged from consumer electronics to car electronics uses.
In the vehicle sensor area, we had developed and started selling in 1977 resistor substrates for air flow meters used for an electronic fuel injection system, and in 1981 a "throttle valve position sensor" that detects an opening and closing valve position of the suction valve. Afterwards, we have continued to offer products for wide variety of applications, such as "EGR valve position sensor" for EGR (Exhaust Gas Recirculation) to reduce nitrogen oxide compounds in exhaustion gas, “Accelerator pedal sensor", "Steering angle sensor" and "Brake pedal sensor" for a detection of driver's intention, "Chassis height sensors" for detection of vehicle's height and tilt, and "Seat weight sensors" for advanced controls of an airbag. The resistance type sensor above all has gained outstanding reputations in the throttle valve position sensor and the EGR valve position sensor which closely relates to car engine controls.
Such an remarkable success of our automotive resistive sensors is supported by the following four core engineering technologies; "material technologies" capable of supporting from molecular designs to polymer macromolecule synthesis and material composite, "design engineering" utilizing simulations such as a mold flow analysis and a magnetic field analysis for molded parts, and "test and evaluation technologies" emulating real cars.

Realized highly accuracies, high sliding resistances, and high heat resistances
Among various core technologies which we have long cultivated, our EGR valve position sensor, especially, to use thick film technology based sliding resistance elements, is remarkable, in detecting a valve position of an EGR device. The EGR device is to recycle a part of exhaust gases to an inlet side, reduce the oxygen concentration during the inlet, and enable lowering the combustion temperature, achieving to reduce nitrogen oxides in the exhaust gases that cause photochemistry smog. The EGR valve position sensor play an important role in detecting a position of an exhaust valve, and feeding it back to the engine controller module. As a result, an optimum amount of exhaust gas circulation can be controlled, which helps reduce air pollutions.
Mainstream of the EGR valve position sensor is a linear type, telling a straight line movement of a valve to a movable contact - a brush, and having it slide on the resistor for an electrical signal conversion. Because the sensor requires a precise accuracy, high sliding resistance and high heat resistance, we selected heat resistance engineering plastics and ceramics, and made a fundamental review on molecular structures of materials for the resistor. Moreover for the structural designing, we adopted a unique eccentric structure, after analyzing the mold flow and thermal deformation, in order to minimize the thermal effects and prevent a direct transmission of the valve vibration to a brush. By separating parts with a brush retention function and a valve contact function, which used to be one body, and displacing a return spring fulcrum of a self return function from the center, contact stability between a brush and a resistor element during vibrations has been remarkably improved.

The Alps sensors to contribute to automobile safety, comfort, and environments
Car sensors such as the EGR valve position sensors will continue to require higher accuracy, heat resistance and durability. Especially, the high heat resistance range and longer life are noteworthy. When we look at variable resistor requirements for audio equipment for comparisons, the heat resistance range for audio equipment is assumed to be used in a house or in a car (i.e. a car audio), under an ambience comfortable for human in terms of the temperature and humidity. In such use cases, the temperature ranges are sufficient between minus 10 and plus 85 degree C. Since car sensor, however, is installed in an engine room etc., wider temperature ranges from a very low to a water boiling temperature need to be supported; minus 40 degree C and plus 125 degree C.
In addition, a product life of resistors for general uses is about 15,000 times. The reason is that they are used for volume controls. Let's suppose that volume controls are made 10 times a day, which corresponds to 3,650 times a year, or 14,600 per 4 years. This should be enough for a normal usage. However in case of automotive applications, over 10 years of long and error-free operations are expected, and an operation life of throttle valve position sensor requires 1 million to 10 million times. 10 million times of the life mean to support an error free product for an operation of accelerator pedal of 2,700 times a day over 10 years. Such severe specifications are required for cars which carry human life. We, therefore, developed a resistor element for a vehicle sensor, capable of 1 billion cycle life (# see below). It is equivalent to 500,000km of durability in terms of mileage.
"While our products have been used from consumer use to car use, I am really proud to have actively met customers' various demands which have helped us shape our products. Such a proven track record and reliability are our major strength.” says Mr. Minoru Yoshida, Mechatronic Device Sales Department, Sales & Marketing Headquarters.
The biggest task for a vehicle sensor is to help contribute to car specific requirements such as safety, comfort, and environment. We as a resistor sensor vendor are happy to play an important role in such an initiative.

# The figures are our performance test results, and not our guarantee specifications.
Alps sensors widely used for cars

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