EP0307980A2
Expired / Lapsed
EP
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A control circuit for a laser printer
Assignee: Canon Production Printing Netherlands BV
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Filing: 1988-08-02
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Granted: —
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Expires: 2008-08-02
Abstract
Abstract A control circuit for a laser printer comprising a laser switching amplifier (11) for supplying current to a laser diode (51), the laser diode being modulated by means of image signals, in which the control circuit comprises a correction circuit (10) with which the image signal is lengthened by a correction time corresponding or substantially corresponding to the time elapsing between current being supplied to the laser diode (51) and its delivering light.
Inventors
- 👤 Louis Gerardus Josephus Joosten
- 👤 Matheas Theodorus Maria Stemkens
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 19:22
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/04; H03F3/08; G; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1204; G06K15/1209; G06K15/1214; H01; H01S; H01S5/00; H01S5/04; H01S5/042; H01S5/06; H01S5/062; H01S5/06209; H01S5/0427; H01S5/0428; H01S5/06216; H01S5/068; H01S5/0683; H01S5/06835
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
74 words
A control circuit for a laser printer comprising a laser switching amplifier (11) for supplying current to a laser diode (51), the laser diode being modulated by means of image signals, characterised in that the control circuit comprises a correction circuit (10) with which the image signal is lengthened by a correction time corresponding or substantially corresponding to the time elapsing between current being supplied to the laser diode (51) and its delivering light.
Claim 2
Dependent Claim
74 words
A control circuit for a laser printer comprising a laser switching amplifier (11) for supplying current to a laser diode (51), the laser diode being modulated by means of image signals, characterised in that the control circuit comprises a correction circuit (10) with which the image signal is lengthened by a correction time corresponding or substantially corresponding to the time elapsing between current being supplied to the laser diode (51) and its delivering light.
Claim 3
Dependent Claim
37 words
A control circuit according to claim 1, characterised in that the correction circuit (10) comprises a delay circuit which delays the trailing flank of the image signal with respect to its leading flank by the correction time.
Claim 4
Dependent Claim
37 words
A control circuit according to claim 2, characterised in that the delay circuit comprises three NAND gates (61, 62, 63) in series, the image signal being fed to the first (61) and the last NAND gate (63).
Claim 5
Dependent Claim
17 words
A control circuit according to claim 2, characterised in that the delay circuit comprises a time circuit.
Claim 6
Dependent Claim
61 words
A control circuit according to claim 1, in which a photodiode (52) is disposed near the laser diode (51) and delivers a signal related to the light output of the laser diode (51), characterised in that the correction circuit (10) determines the time elapsing between reception of the image signal and the rise of the signal delivered by the photodiode (52).
Claim 7
Dependent Claim
76 words
A control circuit according to claim 5, characterised in that the correction circuit (10) comprises an HF clock signal generator and an up and down counter, the counter counting the HF clock signals during the specific time and, after expiry of the image signal, the counter being switched over to a down-counter and counting down to zero, in synchronism with the HF clock pulses, and the image signal being lengthened during the count down to zero.
Claim 8
Dependent Claim
138 words
A control circuit for a laser printer comprising a laser switching amplifier (11) for supplying current to a laser diode (51), the laser switching amplifier (11) comprising a differential amplifier with a common current source (32) and being made up of two chains, a first chain (31, 46, 45, 51) comprising a switching element (31) for switching the current through a laser diode (51) and the second chain (30, 42, 43, 44, 47, 48) also comprising a switching element (30), characterised in that correction elements (44, 47, 48) are disposed in the second chain (30, 42, 43, 44, 47, 48) and represent in the second chain a dynamic load for the switching element (30) which is identical or substantially identical to the load that the laser diode (51) represents for the switching element (31) in the first chain.
Claim 9
Dependent Claim
138 words
A control circuit for a laser printer comprising a laser switching amplifier (11) for supplying current to a laser diode (51), the laser switching amplifier (11) comprising a differential amplifier with a common current source (32) and being made up of two chains, a first chain (31, 46, 45, 51) comprising a switching element (31) for switching the current through a laser diode (51) and the second chain (30, 42, 43, 44, 47, 48) also comprising a switching element (30), characterised in that correction elements (44, 47, 48) are disposed in the second chain (30, 42, 43, 44, 47, 48) and represent in the second chain a dynamic load for the switching element (30) which is identical or substantially identical to the load that the laser diode (51) represents for the switching element (31) in the first chain.
Claim 10
Dependent Claim
67 words
A control circuit according to claim 7, characterised in that the correction elements (44, 47, 48) are formed by two diodes (47 and 48) connected in series to the switching element (30) and a capacitor (44) which is earthed at one connecting point while the other connecting point is connected to the junction of the electrical connection between the switching element (30) and the diodes (47, 48).
References Cited (Backward Citations)
No citation records indexed.
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