Beam control device

An image forming apparatus which forms an image based on an electrostatic latent image, the apparatus comprising:

• a light source which emits light of a predetermined wavelength;
• polarizing means for polarizing the light from the light source so that the light travels along a first direction;
• horizontal synchronizing signal detecting means for detecting the light from the light source which has been polarized by the polarizing means and outputting a horizontal synchronizing signal on the basis of a result of the detection;
• a first processing device which causes the light source to emit the light of the predetermined wavelength in response to the horizontal synchronizing signal from the horizontal synchronizing signal generating means;
• and
• a second processing device which associates the light of the predetermined wavelength from the light source, with image data and causes the polarizing means to polarize the light using a predetermined timing.

A method of controlling a laser beam position in an image forming apparatus including an exposure device a light source which emits light of a predetermined wavelength, polarizing means for polarizing the light from the light source so that the light travels along a first direction, and a first processing device and a second processing device which control the light source and the polarizing means in order to expose an exposure position to light on the basis of image data read by an image reading section, the method comprising:

• if a predetermine current is supplied to the first processing device and the second processing device, using the first processing device to cause the light source to emit light having first information;
• causing the second processing device to operate synchronously with information indicating that the light having the first information has been detected;
• using the second processing device to cause the light source to second information corresponding to an object to be read;
• if that part of the light emitted by the light source and having the second information to which a predetermined area is exposed, causing the first processing device to detect that part of the light having the second information which is used to expose a next predetermined area;
• causing the first processing device to check whether or not the detected information is being provided to the second processing device;
• using the second processing device to allow emission of that part of the light having the second information which is used to expose the next predetermined area, the emission being synchronous with the detected information;
• and
• before the detected information is provided to the second processing device, causing the first processing device to check whether the detected information is being provided to the second processing device.