Patent EP0431603A2 successfully refreshed from Google Patents.
EP0431603A2
Expired / Lapsed
EP
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Optical unit for use in laser beam printer or the like
Assignee: Toshiba Corp
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Filing: 1990-12-05
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Granted: —
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Expires: 2010-12-05
Abstract
Abstract In an optical unit (2) incorporated in a laser beam printer, a laser beam generated by a laser diode (l2) is converted by a group of conversion lenses (l0) into a laser beam having a predetermined-size cross section. The laser beam is directed toward a photosensitive body (90) by a scanner unit (50), so as to scan the photosensitive body. A focusing lens (72) allows the rotating angle of the reflecting faces of the scanner unit to correspond to a desirable point on the surface of the photosensitive body (90). In other words, the rotating angle is made to correspond to the distance between the optical axis center determined with respect to a main scanning direction and a point to which the laser beam is irradiated for scanning. The conversion lenses (l0) include at least one aspheric glass lens (l4). The conversion lenses further includes a pair of plastic lenses (l6, l8) which have substantially the same power and opposite polarities with respect to either the main scanning direction or a sub-scanning direction. Among the lenses (l4, l6, l8) mentioned above, that lens (l6) which is located closest to the glass lens (l4) is integral with the laser diode (l2). The focusing lens (72) is formed of a material having substantially equivalent characteristics to those of the paired plastic lenses.
Inventors
- 👤 Takashi C/O Intellectual Property Div. Shiraishi
- 👤 Masao C/O Intellectual Property Div. Yamaguchi
- 👤 Ken C/O Intellectual Property Div. Omura
- 👤 Naruhito C/O Intellectual Property Div. Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 23:06
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/04; H04N1/113; H04N1/1135; B; B41; B41J; B41J2/00; B41J2/435; B41J2/47; B41J2/471; G; G02; G02B; G02B26/00; G02B26/08; G02B26/10; G02B26/12; G02B26/127
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
195 words
An optical unit (2) characterized by comprising: means (l2) for generating a light beam; first converting means (30) for converting the generated light beam into a light beam which is collimated in a first plane expanding in one of main and sub-scanning directions and which is converged in a second plane expanding in the other of the main and sub-scanning directions; first holding means (26) for integrally holding said generating means and said first converting means, said first holding means being movable in a predetermined direction; second converting means (20) for converting the light beam emitted from said first converting means into a convergent light beam which is convergent in both the first and second planes; means (50) for reflecting the light beam emitted from said second converting means in a predetermined direction; means (70) for guiding the light beam reflected by the reflecting means to a predetermined portion on the surface of an object to be scanned, while simultaneously shaping the light beam to have a predetermined diameter; and second holding means (4a) for holding said first holding means (26), said second converting means (20), said reflecting means (50) and said guiding means (70).
Claim 2
Dependent Claim
120 words
An optical unit according to claim l, characterized in that: said first converting means (30) includes: at least one glass lens (l4) located close to the generating means and having an aspheric surface; and at least one plastic lens (l6) which is one of a pair of lenses having substantially the same power and opposite polarities with respect to one of the main and sub-scanning directions and which is closer to the glass lens than the other; said second converting means (20) includes at least one plastic lens (l8) which is paired with the plastic lens of the first converting means; and said guiding means includes (70) at least one plastic lens (72) functioning as a kind of fϑ lens.
Claim 3
Dependent Claim
48 words
An optical unit according to claim 2, characterized in that the plastic lens (l6) of the first converting means, the plastic lens (l8) of the second converting means, and the plastic lens (72) of the guiding means include lenses which contain materials having substantially the same optical characteristics.
Claim 4
Dependent Claim
35 words
An optical unit according to claim l, characterized in that said first holding means (26) includes a material having a coefficient of thermal expansion in the range of l.5 x l0⁻⁵ to 3 x l0⁻⁵.
Claim 5
Dependent Claim
186 words
An optical unit (2) characterized by comprising: means (l2) for generating a light beam; first converting means (30) for converting the generated light beam into a light beam which is collimated in a first plane expanding in one of main and subscanning directions and which is converged in a second plane expanding in the other of the main and sub-scanning directions; second converting means (20) for converting the light beam emitted from said first converting means into a convergent light beam which is converged in both the first and second planes; first holding means (28) for integrally holding said generating means (l2) and said first and second converting means (30, 20); means (50) for reflecting the light beam emitted from said second converting means in a predetermined direction; means (70) for guiding the light beam reflected by said scanning means to a predetermined portion on the surface of an object to be scanned, while simultaneously shaping the light beam to have a predetermined diameter; and second holding means (4a) for integrally holding said first holding means (28), said reflecting means (50) and said guiding means (70).
Claim 6
Dependent Claim
120 words
An optical unit according to claim 5, characterized in that: said first converting means (30) includes: at least one glass lens (l4) located close to the generating means and having an aspheric surface; and at least one plastic lens (l6) which is one of a pair of lenses having substantially the same power and opposite polarities with respect to one of the main and sub-scanning directions and which is closer to the glass lens than the other; said second converting means (20) includes at least one plastic lens (l8) which is paired with the plastic lens of the first converting means; and said guiding means (70) includes at least one plastic lens (72) functioning as a kind of fϑ lens.
Claim 7
Dependent Claim
45 words
An optical unit according to claim 6, characterized in that the plastic lens (l6) of said first converting means, the plastic lens (l8) of said second converting means, and the plastic lens (72) of said guiding means include materials having substantially the same optical characteristics.
Claim 8
Dependent Claim
35 words
An optical unit according to claim 6, characterized in that said first holding means (28) includes a material having a coefficient of thermal expansion in the range of l.5 x l0⁻⁵ to 3 x l0⁻⁵
References Cited (Backward Citations)
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