Magnetic Head Bidirectional Diode Signal Security
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In magnetic head devices, the writing coil is connected to a write circuit outside the magnetic head, causing an analogue signal from the reading coil to be output unencrypted to the write circuit, potentially allowing unauthorized reading of signals between the magnetic head and the write circuit during reading operations.
Innovation Solution
Incorporating a bidirectional diode in the magnetic head's head case to prevent analogue signals from the reading coil from being output to the write coil, while allowing encrypted write signals to be input via the diode, ensuring that only encrypted signals are transmitted between the magnetic head and the write circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the writing coil is connected to an external write circuit, then the magnetic head can perform writing operations, but the analogue signal from the reading coil can be output unencrypted to the write circuit, compromising security
Solution Approach 1:
A bidirectional diode is introduced as an intermediary component between the writing coil and the external write circuit. This diode allows write signals to pass from the external circuit to the coil while blocking analogue signals from the reading coil from reaching the external circuit, thus preventing unauthorized signal reading while maintaining writing capability
Solution Approach 2:
The bidirectional diode extracts and isolates the writing coil connection from the external write circuit, separating the writing function from the reading signal output path. This extraction prevents the analogue reading signals from being inadvertently output to the external circuit through the writing coil connection
2Object-affected harmful factors
If a bidirectional diode is added to the magnetic head, then signal security is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
A bidirectional diode, a simple and inexpensive semiconductor component, is used to provide security functionality. This low-cost component effectively blocks analogue signals while allowing write signals to pass, achieving security enhancement without significant cost or complexity increase
3Object-affected harmful factors
If the bidirectional diode has high forward voltage, then analogue signals are blocked effectively, but write signals with low voltage cannot be input to the writing coil
Solution Approach 1:
The forward voltage parameter of the bidirectional diode is specifically selected and optimized to be approximately 0.7V, creating a parameter window that effectively blocks low-voltage analogue reading signals (around 10mV) while allowing higher-voltage write signals to pass through to the writing coil, thus resolving the contradiction between blocking effectiveness and signal input capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents unauthorized reading of signals between the magnetic head and the write circuit during reading operations, enhancing security without requiring circuit switching, and allows for downsizing and cost reduction of the magnetic head.
Implementation Method 1
a bidirectional diode connected to the writing coil. The bidirectional diode is arranged in the head case, and a write signal is input via the bidirectional diode to the writing coil
Implementation Method 2
The magnetic head detects variations of a magnetic field when a magnetic card (magnetic recording medium) passes the gap, and outputs a signal
Data Source
AI summary
This magnetic head, which reads and writes magnetic information, prevents a signal from being read between the magnetic head and the write circuit during reading of magnetic information. A card reader 1 is provided with a magnetic head 6 which reads and writes magnetic information. Bidirectional diodes 54A, 54B are arranged inside of a head case 21 of the magnetic head 6. A write signal from a write circuit 72 is inputted via the bidirectional diodes 54A, 54B to a writing coil 34 wound around a core 32 of the magnetic head 6. The bidirectional diodes 54A, 54B and a demodulation IC 61 are mounted on a first board surface 62A of a control circuit board 62, and the control circuit board 62 is fixed to the head case 21 so that the bidirectional diodes 54A, 54B and the demodulation IC 61 are covered by the head case 21.