Thermal Printer Lid Biasing Mechanism for Reliable Head Platen Contact
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Solution Overview
Problem
Conventional thermal printers often experience printing failures due to inadequate pressing force between the thermal head and the platen, which can occur when the lid is not properly locked, leading to incorrect sensor detection and inappropriate pressing force detection.
Innovation Solution
A thermal printer design that includes a biasing member, such as a coil spring, to ensure the sensor does not detect the rib when the lid is not locked, and sensors on both sides of the platen to verify the pressing force, preventing printing until the correct force is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor is provided to detect the locked state of the opening and closing lid, then printing failures can be prevented by detecting when the thermal head and platen have predetermined pressing force, but the sensor may detect the rib even when the lid is not properly locked due to dimensional or mounting accuracy issues, leading to false detection and printing failures
Solution Approach 1:
A rib is introduced as an intermediary element that provides a detectable feature for the sensor. The rib is positioned on the opening and closing lid such that when the lid is properly closed, the rib engages with the sensor to indicate the locked state. This intermediary structure helps the sensor accurately detect the locking state despite variations in dimensional or mounting accuracy.
Solution Approach 2:
The system performs preliminary detection of the locked state before allowing printing to occur. The sensor detects the rib's position in advance to verify that the thermal head and platen have the predetermined pressing force, and only permits printing when the detection result confirms proper locking. This preliminary check prevents printing failures by ensuring correct setup before the printing operation begins.
2Ease of operation
If the opening and closing lid is made lightweight for ease of operation, then user convenience is improved, but the pressing force between the thermal head and platen may be insufficient when the lid is closed, causing printing failures
Solution Approach 1:
The system replaces reliance on manual lid weight for pressing force with a mechanical detection and control system. The sensor detects the rib's position to determine when the lid is properly locked, and the control unit uses this detection result to control the pressing force application. This substitution allows lightweight lids to maintain adequate pressing force through controlled mechanical engagement rather than relying on lid mass.
Solution Approach 2:
The sensor provides feedback about the lid's locked state by detecting the rib's position. This feedback information is used by the control unit to verify that sufficient pressing force is applied between the thermal head and platen. The feedback mechanism ensures that even lightweight lids achieve the necessary pressing force for reliable printing by confirming proper engagement before printing begins.
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 configuration effectively prevents printing failures by ensuring the thermal head is pressed against the platen with the appropriate force, enhancing printing reliability and reducing operational errors.
Implementation Method 1
a coil spring that biases the opening and closing lid and the main body away from each other
Data Source
AI summary
A thermal printer of an embodiment includes: a main body; an opening and closing lid; a printing portion that includes a platen and a thermal head; a locking portion locks the opening and closing lid; a detection unit that detects a predetermined pressing state between the thermal head and the platen when a sensor detects a detection target portion; a controller that prohibits printing by the printing portion when the detection unit does not detect the predetermined pressing state; and a biasing member that biases the main body and the opening and closing lid in a direction in which the main body and the opening and closing lid are separated from each other so that the sensor does not detect the detection target portion in a state where the opening and closing lid is not locked to the locking portion.