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US 6,603,500 B2Granted
Scanning optical apparatus with aspherically-shaped surface in main scanning direction
AssigneeCanon Kabushiki Kaisha
InventorManabu Kato
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AssigneeCanon Kabushiki Kaisha
InventorManabu Kato
Estimating the term…
A scanning optical apparatus includes a light source, a deflecting element for deflecting and reflecting a beam emitted from the light source, and a scanning optical element for focusing the beam deflected by the deflecting element, on a surface to be scanned. The scanning optical element includes a plurality of optical elements. A shape in a main scanning direction of at least one surface out of optical surfaces of the plurality of optical elements is an aspheric shape. An optical element having a largest power in a sub scanning direction on the optical axis out of the plurality of optical elements is located on the deflecting element side with respect to a middle point in an optical-axis direction between the deflecting element and the surface to be scanned. The optical element having the largest power in the sub scanning direction has two optical surfaces. Where φS1 represents a power in the sub scanning direction of the optical element having the largest power in the sub scanning direction and φS1X a power of an optical surface having a smaller power in the sub scanning direction out of the two optical surfaces of the optical element having the largest power in the sub scanning direction, the powers φS1 and φS1X satisfy φS1X<0.2×φS1.
A scanning optical apparatus comprising:
A scanning optical apparatus comprising:
Dependencies are inferred from the claim text.
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Using multifaceted mirrors: details of the optical system between the polygonal mirror and the image plane
Using the combination of scanning and modulation of light: using dot sequential main scanning by means of a light deflector, e.g. a rotating…
Optical elements, systems or apparatus
Typewriters
Term ended 5 Sep 2021 (estimated)
1. Field of the Invention
The present invention relates to a scanning optical apparatus and color image-forming apparatus using it and, particularly, is suitably applicable to apparatuses, for example, such as laser beam printers, digital copying machines, multi-function printers, and so on involving the electrophotographic process, which are constructed to deflect a beam emitted from a light source means, by a deflecting element consisting of a rotary polygon mirror and then guide the beam through a scanning lens system having the f-θ characteristic, to optically scan an area on a surface to be scanned, thereby recording image information thereon.
2. Related Background Art
FIG. 1 is a schematic view showing the major part of the scanning optical apparatus in Embodiment 1 of the present invention;
FIG. 2 is a main scanning sectional view of the scanning optical apparatus in Embodiment 1 of the present invention;
FIG. 3 is a sub scanning sectional view of the scanning optical apparatus in Embodiment 1 of the present invention;
(Embodiment 1)
FIG. 1 is a schematic view showing the major part of Embodiment 1 of the scanning optical apparatus according to the present invention, FIG. 2 a cross-sectional view of the major part in the main scanning direction of Embodiment 1 of the present invention (a main scanning sectional view), and FIG. 3 a cross-sectional view of the major part in the sub scanning direction of Embodiment 1 according to the present invention (a sub scanning sectional view). The main scanning direction herein refers to a direction in which the beam is deflected to scan by the deflective facet of the optical deflector. The main scanning section refers to a beam plane that the beam deflected by the deflective facet of the optical deflector forms with a lapse of time.
In the figures, reference numeral 1 designates a light source means, which consists of a multi-beam light source (multi-beam semiconductor laser) having a plurality of light emitting regions (a and b) capable of being optically modulated independently of each other. Numeral 2 denotes a collimator lens as a first optical element, which converts a plurality of beams (light beams) emitted from the light source means 1, into nearly parallel beams. Numeral 3 indicates an aperture stop, which limits passing beams (light amounts). Numeral 4 represents a cylindrical lens as a second optical element, which has a predetermined refracting power only in the sub scanning direction and which focuses the plurality of beams having passed through the aperture stop 3, to form nearly linear images on a deflective facet 5a of optical deflector 5 described hereinafter, in the sub scanning section.