1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image by being exposed by light, and more particularly to, an image forming apparatus in which light emitted by an exposing light source is conducted by an optical waveguide.
2. Description of Related Art
In Japanese Unexamined Patent Laid-open Publication No. H9(1997)-277588, an image forming apparatus in which an optical signal is transmitted by an optical fiber is proposed.
This image forming apparatus is provided with an optical fiber for transmitting light emitted from an exposing light source such as a semiconductor laser. The image forming apparatus is further provided with a laser driver for driving the light source. The light emitted from the light source driven by the laser driver reaches a polygon mirror via the optical fiber.
An optical sensor is provided to control the light amount reaching the polygon mirror so as to be stabilized. The optical sensor monitors the light reflected by the polygon mirror to feed back to the laser driver. A light amount stabilizing controller (APC) in the laser driver 4 controls the light source so as to output a constant optical signal based on the feedback signal from the sensor.
However, the aforementioned image forming apparatus has the following drawbacks. Firstly, since the monitored result of the light output from the optical fiber is fed back to the driver of the light source, the light amount stabilizing control is complicated, causing an unstable control system. Secondly, since the light emitted by the light source is transmitted as it is to the photosensitive member for exposing it, the light having the most suitable wavelength is not always transmitted from the view points of a transmission efficiency by the optical fiber and the exposure to the photosensitive member.