Diffractive Sync Optics for Temperature-Stable Light Scanning
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Solution Overview
Problem
Existing light scanning apparatuses face challenges in maintaining synchronization detection accuracy due to temperature changes, particularly in compact synchronous detection optical systems with short total lengths, where shifts in light flux condensation positions occur, affecting writing start timing precision.
Innovation Solution
The apparatus incorporates a synchronous detection optical element with a diffractive power equal to or greater than the refractive power in the main scanning cross section, using a plastic mold lens for optical elements and a light shielding member to stabilize light flux condensation, thereby reducing temperature-induced shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a synchronous detection optical system is made compact with short total length, then the device size is reduced, but temperature-induced shifts in light flux condensation position increase, degrading synchronization detection accuracy
Solution Approach 1:
The patent changes the optical parameters by introducing a diffracting surface with specific diffractive power into the synchronous detection optical system. This diffracting surface modifies the optical path and condensation characteristics of the light flux, enabling the system to maintain accurate synchronization detection despite temperature variations and compact dimensions. The diffractive power is specifically designed to compensate for thermal expansion effects in the shortened optical path.
2Temperature
If environmental temperature changes, then the optical performance of the synchronous detection system changes, but the light receiving position shifts, degrading writing start timing precision
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a diffracting surface that pre-compensates for temperature-induced optical performance changes. The diffracting surface is designed to counteract the thermal expansion and refraction index changes that would otherwise cause light flux condensation position shifts, thereby maintaining writing start timing precision across varying environmental temperatures.
3Reliability
If a diffracting surface is added to the synchronous detection optical system, then temperature-induced optical performance changes are suppressed, but the device complexity increases
Solution Approach 1:
The patent merges the diffracting surface functionality into the existing synchronous detection optical system components. Rather than adding a completely separate element, the diffracting surface is integrated with the optical path components, combining multiple functions (diffraction, condensation, and temperature compensation) into a unified optical assembly, thereby minimizing the increase in device complexity.
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 enhances synchronization detection accuracy by minimizing variations in the synchronization detection angle and improving precision, even under temperature fluctuations.
Implementation Method 1
a first optical element which has a diffracting surface and is configured to condense the light flux deflected by the deflecting unit at the second timing in a main scanning cross section
Implementation Method 2
when environmental temperature changes in such synchronization detection, an optical performance of a synchronous detection optical system for guiding the light flux to the synchronous detection unit changes, thereby, a light receiving position of the light flux in the synchronous detection unit may change
Data Source
AI summary
A light scanning apparatus according to the present disclosure includes a deflecting unit deflecting a light flux from a light source to scan a surface in a main scanning direction, a first optical system guiding the light flux deflected by the deflecting unit to the surface to be scanned at a first timing, and a second optical system guiding the light flux deflected by the deflecting unit to a light receiving element at a second timing different from the first timing, in which the second optical system includes a first optical element which has a diffracting surface and condenses the light flux deflected by the deflecting unit at the second timing in a main scanning cross section, and a value of a diffractive power of the first optical element is equal to or larger than a value of a refractive power thereof in the main scanning cross section.