Encoder Pulse Period Storage for Image Formation
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Solution Overview
Problem
Existing image forming apparatuses face issues with maintaining recording precision when the encoder signal for detecting the transportation position of the transportation unit has discontinuous portions, leading to image deterioration due to factors like non-integral multiples of print pitch, ink mist, or sensor damage.
Innovation Solution
An image forming apparatus that measures the pulse period of the encoder signal, stores this value, and generates recording timing pulses based on the stored period when pulse omission is detected, ensuring constant interval generation even with changed transportation speed, and switches sensors if multiple encoder signals are used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the encoder signal is used continuously at regular pitch for generating recording timing pulses, then high-quality printing with controlled striking position can be realized, but the system becomes vulnerable to image deterioration when pulse omission occurs due to ink mist, paper dust, or encoder damage
Solution Approach 1:
The system measures and stores the pulse period of the encoder signal in advance before pulse omission occurs. When pulse omission is detected, the pre-stored pulse period is used to generate recording timing pulses, avoiding image deterioration without requiring complex real-time interpolation processing.
Solution Approach 2:
A pulse period storage unit acts as an intermediary between the encoder signal and the recording timing pulse generation. It holds the measured pulse period and provides it to the pulse generation unit when the encoder signal experiences discontinuities, ensuring continuous and stable operation.
2Adaptability or versatility
If the circumferential length of the transportation unit is not an integral multiple of print pitch, then the encoder can cover the full transportation range, but a discontinuous portion is generated in the encoder signal output causing image deterioration
Solution Approach 1:
The system continuously measures and updates the pulse period of the encoder signal in advance. When the transportation unit completes a full cycle and the encoder signal becomes discontinuous, the pre-measured pulse period ensures that recording timing pulses continue to be generated at correct intervals, preventing image deterioration at the discontinuous portion.
3Manufacturing precision
If motor speed control is implemented to maintain constant encoder signal period, then recording precision is improved, but the control system becomes complicated and susceptible to divergence requiring gain adjustment
Solution Approach 1:
Instead of controlling motor speed to maintain constant encoder period (traditional approach), this system inverts the approach by using the measured encoder pulse period to generate recording timing pulses directly. This eliminates the need for complex motor control while achieving the same recording precision.
Solution Approach 2:
The system extracts the pulse period information from the encoder signal and uses it directly for generating recording timing pulses, separating the timing generation function from the motor control function. This simplifies the overall system by removing the complex feedback control loop.
Data Source
AI summary
An image forming apparatus records an image on a transported recording medium. The apparatus includes a transportation unit that transports the recording medium and a recording unit that records the image on the recording medium. An encoder outputs an encoder signal including pulses according to a position of the transportation unit. A measurement unit measures a pulse period of the encoder signal, and the measured pulse period is stored by a storage unit. A detection unit detects pulse omission of the encoder signal on the basis of the value measured by the measurement unit. A pulse generation unit generates a recording timing pulse on the basis of the pulse period when the pulse omission is not detected and generates the recording timing pulse on the basis of the pulse period stored in the storage unit and measured before the pulse omission when the pulse omission is detected.