Laser Driver Circuit for Electro-Optical Distance Measuring Devices
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Solution Overview
Problem
Conventional laser safety systems for electro-optical distance measuring devices are complex and costly, requiring monitor diodes for power monitoring, which are prone to interference and increased circuit complexity, especially during pulsed operation, and often necessitate analog signal evaluation and multiple electrical connections.
Innovation Solution
A laser driver circuit that operates below the laser threshold voltage, using an inductive component and electronic switching to limit laser power without a monitor diode, allowing for pulsed emission with restricted energy and eliminating continuous-wave emission, thereby ensuring safety through a digital interface and reduced component complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monitor diode is used to monitor laser power for safety, then laser safety can be ensured, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the monitor diode component from the laser driver circuit. Instead of using a separate monitor diode to detect laser power, the invention uses the main laser diode itself in conjunction with an inductive component and switching element to inherently limit power output, thereby removing the need for additional monitoring hardware and reducing circuit complexity.
Solution Approach 2:
The laser diode circuit is designed to self-regulate its power output through the inductive component and switching element configuration. The circuit inherently limits the current and power delivered to the laser diode without requiring external monitoring or control, making the system self-regulating and eliminating the need for separate safety monitoring components.
2Reliability
If a monitor diode is used for laser power monitoring, then laser safety can be ensured, but manufacturing cost increases
Solution Approach 1:
The patent removes the monitor diode component from the circuit, eliminating the need to source, mount, and wire additional expensive components. This reduction in component count directly lowers manufacturing costs while maintaining safety through the inherent circuit design.
Solution Approach 2:
The invention replaces expensive monitor diode components with a configuration using standard inductive components and switching elements that are more cost-effective. The solution uses readily available, low-cost components to achieve the same safety function.
3Reliability
If monitor diode is used during pulsed operation, then laser safety can be monitored, but electromagnetic interference increases
Solution Approach 1:
By removing the monitor diode and its associated analog signal evaluation circuitry, the patent eliminates a significant source of electromagnetic interference. The high-frequency switching signals required for pulsed operation no longer interfere with sensitive monitoring circuits, as the monitoring function is replaced by the inherent circuit configuration.
Solution Approach 2:
The patent replaces the optical monitoring mechanism (monitor diode detecting laser light) with an electrical circuit configuration that inherently limits power. This substitution eliminates the optical detection path that is susceptible to electromagnetic interference during pulsed operation.
4Reliability
If monitor diode and analog signal evaluation are used, then laser power can be monitored, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the entire analog signal evaluation chain, including the monitor diode, analog-to-digital converter, and associated processing circuitry. Power monitoring is replaced by the inherent current-limiting behavior of the inductive component and switching element configuration.
Solution Approach 2:
The circuit is designed to self-regulate power output through the inductive component and switching element, eliminating the need for external monitoring and evaluation systems. The circuit inherently maintains safe operating parameters without requiring complex signal processing.
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
This solution simplifies laser safety management, reduces costs, and minimizes electromagnetic interference, ensuring compliance with safety standards by limiting laser power without the need for monitor diodes, while allowing for efficient pulsed operation and easy integration into compact designs.
Implementation Method 1
an inductive component (12) in a supply path of the laser diode, in particular electrically connected to the laser diode, and an electronic switching element (13). The switching element (13) is arranged interactively in such a way that, in a first steady-state switching position of the switching element, a current flow through the inductive component (12) can be produced and, in a second steady-state switching position of the switching element, the current flow can be conducted through the laser diode
Data Source
AI summary
An electro-optical distance measuring device includes a laser driver for a laser diode for emitting laser light pulses. The laser driver has a laser diode voltage supply for providing a voltage below a laser threshold voltage of the laser diode, an inductive component in a supply path of the laser diode, and an electronic switching element. The electronic switching element is arranged in an interacting manner such that a current flow through the inductive component can be generated in a first switching position of the switching element and the current flow can be conducted through the laser diode in a second switching position of the switching element. One of the laser light pulses can be emitted as the result of a switch from the first switching position to the second switching position, and laser light cannot be emitted in the static first switching position or the static second switching position.