Abstract: In an image forming apparatus (1) utilizing electrophotographic technology, position and posture of a laser scan unit (5) with respect top a frame (13) is adjusted easily without cost rise and upsizing of the apparatus. Semicircular recesses (53) and an elongate hole (54) are formed at each of three fixing portions (52a, 52b and 52c) in the vicinities of side faces (51b) and a rear face (51c) of a housing (51) of the laser scan unit (5), and an adjuster 30 serving as a spacer is attached to each of the fixing portions (52a, 52b and 52c). Each adjuster (30) is elected among a plurality of kinds of adjustors respectively having different thicknesses manufactured by press working of metal plates commercially produced and having different thicknesses with using the same dies. The adjustor has a pair of semicircular engaging portions 30b and a coupling portion 30a perpendicular to and coupling the engaging portions (30b).

Abstract: In a laser beam printer, even when an inexpensive CPU having low throughput capacity is used, stable power can be obtained by following a sudden change in temperature of a laser chip. A control unit sets a scanning cycle for performing the automatic power control based on ambient temperature of a photoconductive drum and the number of continuously-printed sheets. Then, the control unit output a horizontal synchronizing signal to a laser driving circuit and causes a laser scan unit to output a scanning laser beam. Substantially, when scanning corresponds the scanning cycle, the automatic power control is performed based on an output signal of a photodiode. When scanning does not correspond to the scanning cycle, a horizontal synchronizing signal of the next line is output. Whereby, the scanning cycle for performing the automatic power control according to a change in temperature of the laser chip, thereby reducing loads applied to the control unit.

Abstract: In an image forming apparatus (1) utilizing electrophotographic technology, position and posture of a laser scan unit (5) with respect top a frame (13) is adjusted easily without cost rise and upsizing of the apparatus. Semicircular recesses (53) and an elongate hole (54) are formed at each of three fixing portions (52a, 52b and 52c) in the vicinities of side faces (51b) and a rear face (51c) of a housing (51) of the laser scan unit (5), and an adjuster 30 serving as a spacer is attached to each of the fixing portions (52a, 52b and 52c). Each adjuster (30) is elected among a plurality of kinds of adjustors respectively having different thicknesses manufactured by press working of metal plates commercially produced and having different thicknesses with using the same dies. The adjustor has a pair of semicircular engaging portions 30b and a coupling portion 30a perpendicular to and coupling the engaging portions (30b).

Abstract: In a laser beam printer, even when an inexpensive CPU having low throughput capacity is used, stable power can be obtained by following a sudden change in temperature of a laser chip. A control unit sets a scanning cycle for performing the automatic power control based on ambient temperature of a photoconductive drum and the number of continuously-printed sheets. Then, the control unit output a horizontal synchronizing signal to a laser driving circuit and causes a laser scan unit to output a scanning laser beam. Substantially, when scanning corresponds the scanning cycle, the automatic power control is performed based on an output signal of a photodiode. When scanning does not correspond to the scanning cycle, a horizontal synchronizing signal of the next line is output. Whereby, the scanning cycle for performing the automatic power control according to a change in temperature of the laser chip, thereby reducing loads applied to the control unit.

Abstract: An image forming apparatus capable of detecting a toner image density well by shifting a developing bias. In adjusting a fog density or a solid density, the developing bias is shifted by a specified width so as to form an image of a gray density. This enables detection of the fog density and the solid density to be replaced with detection of a density in a gray density region where a reflection type photosensor can detect a density with high sensitivity. Thus, densities in a fog or solid density region where usually an output from the reflection type photosensor is saturated can be detected with high accuracy.

Abstract: The present invention is directed to an image density control device in an image formation apparatus where a pattern of reference density on a sample original is exposed to light from an exposing light source to image the pattern on photoconductor, density of the resultant toner image is detected by a reflection-type photosensor, and parameters on image density are adjusted based upon results of detection by the reflection-type photosensor. In the image density control device in the image formation apparatus, the sample original is mounted on a cabinet of the image formation apparatus so that a distance from the exposing light source in illuminating the pattern of the reference density to the pattern of the reference density can be adjusted.

Abstract: A method of controlling image density includes imaging a pattern of reference density as a toner image on a photoconductor. The density of the toner image is detected by a reflection-type photosensor, and parameters on the image density are adjusted based upon the results of this detection. In this invention, prior to measuring the reference density toner image, the drive current for the reflection-type photosensor is varied, and output from the reflection-type photosensor is measured while no toner is present on the photoconductor. A reference value of the drive current for the reflection-type photosensor which permits output from the reflection-type photosensor to be a predetermined value is determined. Then, the drive current for the reflection-type photosensor for measuring the reference density toner image is set based on the reference drive current value.

Abstract: An image forming apparatus has a functional redundancy system by which an inherent function normally performed by a certain portion is performed as a potential function by another portion, when such certain portion no longer can be perform its inherent function. In a first operative sequence, portions in the image forming apparatus perform their respective inherent functions. However, where a function of a certain portion in the apparatus is lost, for example, where a fault occurs and a particular element has failed, operation of other portions in the apparatus are controlled according to a second sequence. In the second sequence, the inherent function of the portion which has failed is replaced by the potential function of another portion in the apparatus.

Abstract: An image forming apparatus is provided with a rotatable photosensitive member; an imaging assembly for exposing the surface of the photosensitive member to light so as to form an electrostatic latent image thereon and developing the electrostatic latent image; and a sensor arranged in the vicinity of and opposed to the surface of the photosensitive member, and adapted for detecting an imaging performance in a specific region on the surface of the photosensitive member. With the image forming apparatus thus constructed, measurement values vary only within a reduced range since an imaging performance of the photosensitive member is detected in a specific region on the photosensitive member.

Abstract: A composite image forming apparatus including an analog or a digital image forming apparatus of the type in which an optical system moves relative to a document placed on a document table, the image on the document is scanned by the optical system and the image is transferred to a sheet of image transferring paper and a belt like recording medium on which additional or optional images from which additional or optional images other than the document image can be transferred to the sheet of image transferring paper.

Abstract: A device for detecting the life of a process unit which is detachably mounted in an image forming apparatus includes a sensor for detecting the density of the toner in the developing device and a signal detector receiving an output from the sensor and operable to determine whether the output exceeds or is less than a predetermined value during a predetermined time period which starts after a developing roller of the process unit starts rotating. A control is connected to the signal detector and is operable to effect different operating conditions depending on whether the output exceeds or is below the predetermined value, one of the operating conditions being an indication that the life of the process unit has expired and another of the operating conditions being an indication that the life of the process unit is unexpired.