Bimodal Door Exit Device with Delayed Egress and Immediate Access
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Solution Overview
Problem
Existing door exit devices face challenges in efficiently integrating electric latch retraction with delayed egress functionality, often causing inconvenience and security vulnerabilities due to the security features associated with delayed egress mechanisms.
Innovation Solution
A bimodal door exit device system that includes a latch retraction assembly coupled with a push pad, a delayed egress device with a latch retraction lock, and an access enable device that allows non-delayed latch retraction upon receiving an authorized access signal, enabling efficient and secure access control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delayed egress mechanisms are implemented to prevent unauthorized exit, then security control is improved, but the convenience of authorized access deteriorates due to alarm obstacles and delay periods
Solution Approach 1:
The exit device is segmented into two distinct operational modes: delayed egress mode for unauthorized attempts and immediate egress mode for authorized users. The control system divides the latch retraction function into two pathways - one through the delayed egress mechanism with alarm activation, and another direct pathway for authorized access that bypasses the delay and alarm features, thus resolving the contradiction between security control and authorized access convenience
Solution Approach 2:
The system dynamically switches between two operational states based on authorization status. When an authorized user presents valid credentials, the system transitions from the delayed egress state to the immediate egress state, dynamically adjusting the latch retraction behavior and alarm activation characteristics to provide appropriate access control while maintaining convenience for authorized personnel
2Reliability
If electric latch retraction is integrated with delayed egress functionality, then access control is improved, but device complexity increases
Solution Approach 1:
The control system is designed with multi-functionality to handle both delayed egress and immediate egress operations through a single integrated装置. The same latch retraction assembly serves both the delayed egress pathway (with alarm activation) and the immediate egress pathway (for authorized users), reducing the need for separate mechanisms and thereby managing device complexity while maintaining reliable access control
Solution Approach 2:
The control system acts as an intermediary that manages the interaction between the electric latch retraction mechanism and the delayed egress functionality. It mediates between the two operational modes, determining whether to activate the alarm and delay period or to immediately retract the latch based on authorization status, thus simplifying the overall system integration by providing a centralized control logic
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
The system provides reliable and controlled access by integrating manual and signal-actuated latch retraction with delayed egress functionality, enhancing security while minimizing unauthorized access and reducing the impact of security features on authorized access.
Implementation Method 1
an access enable device operatively coupled to actuate the latch retraction assembly in response to an authorized access signal
Implementation Method 2
a delayed egress device having a latch retraction lock that is operatively coupled to the latch retraction assembly to prevent the latch retraction assembly from retracting the door latch
Data Source
AI summary
A door exit device, security system, and method for implementing a delayed egress operating mode and an authorized access operating mode to control access through a door. In one embodiment, the exit device includes an egress enable mechanism including a latch retraction assembly operatively coupled between a push pad and a door latch. The latch retraction assembly retracts the door latch responsive to manual actuation of the push pad. The exit device further includes a delayed egress device having a latch retraction lock that is operatively coupled to the latch retraction assembly to prevent the latch retraction assembly from retracting the door latch coincident with an attempted manual actuation of the push pad. The exit device further includes an access enable device operatively coupled to actuate the latch retraction assembly in response to an authorized access signal. The delayed egress device further includes a lock override that, responsive to receiving the authorized access signal, releases the latch retraction lock to enable non-delayed retraction of the door latch.