Image Recording Apparatus Exposure Timing Control
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Solution Overview
Problem
Conventional image recording apparatuses face inefficiencies in starting the exposure process on a photosensitive drum due to delays in sheet alignment, leading to prolonged printing times as the exposure begins after skew correction, causing misalignment between the transfer and exposure start positions.
Innovation Solution
An image recording apparatus with an exposure control unit that synchronizes the start of the exposing unit with the conveying unit's operation, utilizing a medium detecting unit to adjust the conveying speed to ensure accurate alignment of the recording medium with the exposure start position, and includes mechanisms to adjust motor currents and pulse counting for precise timing and speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the exposure process is started after skew correction is completed, then the sheet alignment is improved, but the printing time is prolonged
Solution Approach 1:
The exposure process is initiated before the sheet reaches the transfer position by a predetermined time. The control unit calculates this advance time based on the sheet conveyance speed and distance, allowing the exposure to start in advance while maintaining proper alignment. This eliminates the sequential dependency where exposure must wait for skew correction to complete.
Solution Approach 2:
The system dynamically adjusts the exposure start timing based on real-time sheet conveyance conditions. The control unit continuously monitors sheet position and speed, calculating the optimal advance time to ensure the sheet reaches the transfer position at the correct moment. This dynamic timing adjustment allows high-speed printing while maintaining precision.
2Manufacturing precision
If the exposure start position is delayed until sheet detection, then the alignment accuracy is improved, but the transfer and exposure timing coordination is worsened
Solution Approach 1:
The exposure process is triggered in advance based on predicted sheet position rather than waiting for actual detection at the transfer position. The control unit uses the sheet conveyance speed and distance to calculate when the sheet will reach the transfer position, initiating exposure accordingly. This preliminary timing action simplifies coordination by eliminating the need for complex real-time detection and adjustment mechanisms.
3Productivity
If the sheet is conveyed at high speed, then the productivity is improved, but the alignment precision between transfer and exposure positions is worsened
Solution Approach 1:
The system dynamically calculates the exposure start timing based on the actual sheet conveyance speed. The control unit continuously monitors conveyance conditions and adjusts the advance time accordingly, ensuring that even at high speeds, the sheet reaches the transfer position at the correct moment. This dynamic adaptation maintains alignment precision without sacrificing conveyance speed.
Solution Approach 2:
The control unit monitors sheet position and conveyance speed in real-time, using this feedback to calculate and adjust the exposure start timing. By continuously comparing actual sheet position with expected position and adjusting timing accordingly, the system maintains precise alignment even at high conveyance speeds, resolving the trade-off between speed and precision.
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 allows for accurate alignment of the transfer and exposure start positions, reducing printing time and improving efficiency by enabling high-speed printing while preventing misalignment and potential jam issues.
Implementation Method 1
an exposing unit which exposes an image holding material to form an electrostatic latent image
Implementation Method 2
a conveying unit which is driven by a driving unit after a skew of a recording medium is corrected and conveys the recording medium toward a transfer position
Data Source
AI summary
After a skew of a sheet as a recording medium is corrected by correcting a sheet curve, exposure writing on a photosensitive drum is started synchronously with re-driving of resist rollers. When a sheet front edge is detected by a sensor, sheet conveyance is continued while adjusting a sheet conveying speed when an exposure start position reaches a transfer position at a pressure contact point between the drum and a transfer roller, thereby adjusting the time of arrival at the transfer position. A time/distance interval between the preceding and subsequent sheets are shortened, a conveying path is shortened, and the whole apparatus is miniaturized. Print processing efficiency is raised and stable printing without a variation is executed. A transfer start position of the sheet is made to accurately coincide with the exposure start position of the drum, thereby realizing a high print processing speed.