Laser drive device and image forming apparatus incorporating the same
AssigneeCanon Kabushiki Kaisha
InventorMasaaki Moriya
Life of this patent
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Abstract
An inexpensive laser drive device which is capable of driving a laser for emission of an appropriate amount of light. Electric currents supplied from a supply current control device formed in an integrated circuit to a plurality of predetermined ports of the integrated circuit are turned on and off by switching devices in response to a signal from a signal output device of the supply current control device, and the on currents are supplied, as a driving current, from the supply current control device to a laser beam-emitting device through corresponding ones of the predetermined ports and resistors externally attached to these ports. A generator device formed in the integrated circuit generates a pulse signal for turning on and off a laser beam based on image data.
Claims12
A laser drive device comprising:
- an integrated circuit having formed therein a generator device that generates a pulse width modulation signal based on image data, and a supply current control device, said integrated circuit having plural ports;
- and
- a plurality of resistors externally attached to respective ones of said ports;
- wherein:
- said supply current control device is capable of supplying a driving current to a laser beam-emitting device via said ports and said resistors;
- and
- said supply current control device includes a plurality of switching devices which are attached to respective ones of said ports, and a signal output device that outputs signals to respective ones of said switching devices, to switch selectively said switching devices.
An image forming apparatus comprising:
- a laser drive device;
- a laser beam-emitting device that emits a laser beam based on image data by the laser drive device;
- and
- an image forming device that forms images using the laser beam emitted from said laser beam-emitting device,
- wherein said laser drive device comprises:
- an integrated circuit having formed therein a generator device that generates a pulse width modulation signal based on image data, and a supply current control device, said integrated circuit having plural ports;
- and
- a plurality of resistors externally attached to respective ones of said ports;
- wherein:
- said supply current control device is capable of supplying a driving current to a laser beam-emitting device via said ports and said resistors;
- and
- said supply current control device includes a plurality of switching devices which are attached to respective ones of said ports, and a signal output device that outputs signals to respective ones of said switching devices, to switch selectively said switching devices.
Dependencies are inferred from the claim text.