Electrostatic latent image forming apparatus using semiconductor laser
AssigneeMinolta Camera Kabushiki Kaisha
InventorNaoto Ohmori
Life of this patent
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Abstract
An electrostatic latent image forming apparatus using a semiconductor laser 11 forms an image on a surface of a photoreceptor drum 15 by a laser beam modulated by an image signal while intensity of the laser beam is lowered by a reflection mirror 16 having a reflectance as low as 30%. The semiconductor laser 11 is driven by current obtained by adding bias current Iba to switching current Isw and a bias component out of an optical output level thereof is decreased by the reflection mirror 16 having the low reflectance. Therefore, an off-level optical output correponding to the bias current becomes lower than that in the case in which lowering of the intensity of the beam is not caused, and as a result, a "fogging" phenomenon or the like can be effectively prevented.
Claims14
An electrostatic latent image forming apparatus comprising:
- a semiconductor laser,
- drive means for adding bias current to switching current modulated by an image signal and applying the current obtained of the addition to said semiconductor laser, thereby to excite said semiconductor laser to emit a laser beam,
- a photoreceptor having a surface on which an electrostatic latent image is to be formed by said laser beam,
- a scanning optical system for scanning said surface of said photoreceptor by said laser beam emitted from said semiconductor laser and forming an image by said laser beam on said surface of said photoreceptor, and
- optical means disposed in a path of transmission of said laser beam extending from said semiconductor laser to said photoreceptor for lowering intensity of said laser beam, thereby to decrease a component corresponding to said bias current out of said laser beam.
An improved electrostatic latent image forming apparatus comprising:
- laser means for providing a laser beam;
- drive means for exciting the laser means to emit a laser beam capable of forming a latent image;
- means for compensating for the effect of any temperature variations on the output of the laser beam;
- a photoreceptor for forming the latent image from the impact of the laser beam, and
- means for lowering the intensity of the laser beam to decrese at least that portion of the laser beam intensity output that was emitted relative to any increase in the laser output resulting from the means for temperature compensation.
An improved electrostatic latent image forming apparatus comprising:
- means for providing a laser beam;
- means for providing an image signal;
- drive means for adding bias current to a switching current modulated by the image signal and applying the current obtained by the addition to the laser means, thereby to excite the laser to emit the laser beam;
- a photoreceptor having a surface on which an electrostatic latent image is to be formed by the laser beam;
- an optical system for impacting the surface of the photoreceptor by the laser beam emitted from the laser means and forming an image by the laser beam on the surface of the photoreceptor, and
- optical means disposed in a path of transmission of the laser beam extending from the laser means to the photoreceptor for lowering the intensity of the laser beam, thereby to decrease a component of laser energy corresponding to the laser energy produced by the bias current.
Dependencies are inferred from the claim text.