A light emitting device 401 includes a silicon substrate and a light emitting region including a lower electrode, a light emitting layer, and an upper electrode, and an exposure head is provided with a printed board on which light emitting devices 401 are arranged in a staggered form and a circuit portion 602 for controlling, on the basis of image data, a voltage of each of electrodes included in the lower electrode so that the light emitting device layer emits light and is for forming an image with a resolution corresponding to an arrangement interval of the lower electrode with respect to a crossing direction, and the circuit portion 602 is disposed together with the light emitting region on the silicon substrate. Costs on wire bonding and an area of a wiring board can be suppressed.

A light emitting device 401 includes a silicon substrate and a light emitting region including a lower electrode, a light emitting layer, and an upper electrode, and an exposure head is provided with a printed board on which light emitting devices 401 are arranged in a staggered form and a circuit portion 602 for controlling, on the basis of image data, a voltage of each of electrodes included in the lower electrode so that the light emitting device layer emits light and is for forming an image with a resolution corresponding to an arrangement interval of the lower electrode with respect to a crossing direction, and the circuit portion 602 is disposed together with the light emitting region on the silicon substrate. Costs on wire bonding and an area of a wiring board can be suppressed.

An image forming apparatus includes a scanning means provided with a light source, a polygon mirror and a driving means for driving rotation of the polygon mirror; a photosensitive member, a developing means, and a detecting means for detecting a laser light from the light source. A controller controls to execute a light emission operation so that an area including an image forming area of the photosensitive member is irradiated with the laser light. The controller controls to execute a switching operation in which a rotational speed of the polygon mirror is switched from a first speed to a second speed different from the first speed. The controller controls to execute the light emission operation in a state in which the photosensitive member and the developing means are in contact and are rotating, and to execute the switching operation based on a detecting result of the detecting means in the light emission operation.

An image forming apparatus includes a scanning means provided with a light source, a polygon mirror and a driving means for driving rotation of the polygon mirror; a photosensitive member, a developing means, and a detecting means for detecting a laser light from the light source. A controller controls to execute a light emission operation so that an area including an image forming area of the photosensitive member is irradiated with the laser light. The controller controls to execute a switching operation in which a rotational speed of the polygon mirror is switched from a first speed to a second speed different from the first speed. The controller controls to execute the light emission operation in a state in which the photosensitive member and the developing means are in contact and are rotating, and to execute the switching operation based on a detecting result of the detecting means in the light emission operation.

An image forming apparatus includes: an image carrier that carries an image developed by a developer; an exposure part that has plural light-emitting parts that are shifted from one another so as to face the image carrier and in each of which plural light-emitting elements are aligned and forms an electrostatic latent image on the image carrier by exposing the image carrier to light; and plural density detection parts that are disposed at positions corresponding to substantially central positions of the plural light-emitting parts and at positions corresponding to end portions closer to end portions of the image carrier among end portions of two light-emitting parts disposed close to the end portions of the image carrier among the plural light-emitting parts and detect a density of an image obtained by developing the electrostatic latent image on the image carrier.

An image forming apparatus includes: an image carrier that carries an image developed by a developer; an exposure part that has plural light-emitting parts that are shifted from one another so as to face the image carrier and in each of which plural light-emitting elements are aligned and forms an electrostatic latent image on the image carrier by exposing the image carrier to light; and plural density detection parts that are disposed at positions corresponding to substantially central positions of the plural light-emitting parts and at positions corresponding to end portions closer to end portions of the image carrier among end portions of two light-emitting parts disposed close to the end portions of the image carrier among the plural light-emitting parts and detect a density of an image obtained by developing the electrostatic latent image on the image carrier.

In an image forming apparatus, a CPU 73 can perform a normal mode and a low mode in which a photoconductive drum 1 rotates at a rate m/n times the rotational rate in the normal mode, lower than the rotational rate in the normal mode. In the low mode, the CPU 73 causes a synchronizing signal generation portion 74 to generate a line synchronizing signal at a cycle 1/m times the cycle of the line synchronizing signal generated in the normal mode, and causes a chip data conversion portion 72 to transmit, to an exposure head 6, the same image data signal m times and transmit, to the exposure head 6, an image data signal that brings a light-emitting portion 50 into no light emission n-m times, in synchronization with n number of line synchronizing signals.

In an image forming apparatus, a CPU 73 can perform a normal mode and a low mode in which a photoconductive drum 1 rotates at a rate m/n times the rotational rate in the normal mode, lower than the rotational rate in the normal mode. In the low mode, the CPU 73 causes a synchronizing signal generation portion 74 to generate a line synchronizing signal at a cycle 1/m times the cycle of the line synchronizing signal generated in the normal mode, and causes a chip data conversion portion 72 to transmit, to an exposure head 6, the same image data signal m times and transmit, to the exposure head 6, an image data signal that brings a light-emitting portion 50 into no light emission n-m times, in synchronization with n number of line synchronizing signals.

An optical scanning device includes: a light source; a light source driver that provides the light source with a drive current, on which a bias current that fluctuates according to temperature change is superimposed, for emitting light from the light source; and a bias current adjuster that provides the light source driver with a bias control signal for adjusting a magnitude of the bias current, wherein the bias current adjuster includes a current value adjusting member that is capable of changing the magnitude of the bias control signal according to temperature change, and wherein the bias control signal that has automatically changed according to temperature change of the current value adjusting member is provided to the light source driver, so that the light source driver makes the magnitude of the bias current to be superimposed fluctuate, based on the provided bias control signal.

An optical scanning device includes: a light source; a light source driver that provides the light source with a drive current, on which a bias current that fluctuates according to temperature change is superimposed, for emitting light from the light source; and a bias current adjuster that provides the light source driver with a bias control signal for adjusting a magnitude of the bias current, wherein the bias current adjuster includes a current value adjusting member that is capable of changing the magnitude of the bias control signal according to temperature change, and wherein the bias control signal that has automatically changed according to temperature change of the current value adjusting member is provided to the light source driver, so that the light source driver makes the magnitude of the bias current to be superimposed fluctuate, based on the provided bias control signal.