Image forming apparatus having rotational phase controller

Claim 2

An image forming apparatus, comprising: at least one image forming means having an image carrier for forming images in different colors; one of an endless carrier and a transfer material held on the endless carrier onto which an image is directly transferred in different colors; rotational phase control means for individually controlling a phase of rotation of at least one of the image carrier and the endless carrier; and phase detection means for calculating a mean value of rotational variation data on the phase of rotation, an address of at least a minimum and a maximum rotational variation of each color and an address of at least a rising edge and a falling edge of the rotational variations of each color based on the mean value of the variation data on the rotational phases, for averaging all the rotational phases of at least one of the image carrier and the endless carrier of the image forming means based on the addresses and determining the phase of rotational variations of at least one of the image carrier and the endless carrier based on the mean value of the rotational variation data.

Claim 3

An image forming apparatus, comprising: at least one image forming means having an image carrier for forming images in different colors; one of an endless carrier member and a transfer material held on the endless carrier onto which an image is directly transferred in different colors; phase detection means for detecting a phase of rotation of at least one of the image carrier and the endless carrier, for calculating a mean value of rotational variation data on the rotational phase, an address of at least a minimum and a maximum rotational variation of each color and an address of at least a rising edge and a falling edge of the rotational variations of each color based on the mean value of the variation data on the rotational phases, for averaging all the rotational phases of at least one of the image carrier and the endless carrier of the image forming means based on the addresses and for determining the phase of rotational variation of at least one of the image carrier and the endless carrier of the image forming means based on the mean value of the rotational variation data; and rotational phase control means for individually controlling the phase of rotation of at least one of the image carrier and the endless carrier based on the phase information detected by the phase detection means.

Claim 4

An image forming apparatus, comprising: at least one image forming means having an image carrier for forming images in different colors; one of an endless carrier member and a transfer material held on the endless carrier onto which an image is directly transferred in different colors; phase detection means for detecting a phase of rotation of at least one of the image carrier and the endless carrier, for calculating a mean value of rotational variation data on the rotational phase, an address of at least a minimum and a maximum rotational variation of each color and an address of at least a rising edge and a falling edge of the rotational variations of each color based on the mean value of the variation data on the rotational phases, for averaging all the rotational phases of at least one of the image carrier and the endless carrier of the image forming means based on the addresses and for determining the phase of rotational variation of at least one of the image carrier and the endless carrier of the image forming means based on the mean value of the rotational variation data; and rotational phase control means for individually controlling the phase of rotation of at least one of the image carrier and the endless carrier based on the phase information detected by the phase detection means.

Claim 5

An image forming apparatus that is configured so as to: (i) form images in different colors by means of at least one of image forming means having image carriers; (ii) form an image by directly transferring the images onto transfer material placed on an endless carrier, the endless carrier being rotated; (iii) form a color difference detection pattern on the endless carrier; (iv) sample the color difference detection pattern; and (v) control the difference between a plurality of toner images which are directly formed in different colors on the transfer material, the image forming apparatus comprising: color difference detection pattern output means for outputting an image signal, the image signal producing a color difference detection pattern for detecting periodic rotational variations arising in the image forming apparatus to the image forming means; pattern detection means for detecting the color difference detection pattern formed on the endless carrier; phase detection means for detecting the phase of rotation of at least one of the image carriers of the image forming means on the basis of a detection signal received from the pattern detection means, for calculating a mean value of rotational variation data on the rotational phases, an address of at least a minimum and a maximum rotational variation of each color and an address of at least a rising edge and a falling edge of the rotational variations of each color based on the mean value of the variation data on the rotational phases, for averaging all the rotational phases of at least one of the image carrier and the endless carrier of the image forming means based on the addresses and for determining the phase of rotational variations of at least one of the image carrier and the endless carrier of the image forming means based on the mean value of the rotational variation data; and rotational phase control means for individually controlling the phase of rotation of at least one of the image carrier of the image forming means and the endless carrier based on the phase information detected by the phase detection means.

Claim 6

An image forming apparatus that is configured so as to: (i) form images in different colors by means of at least one of image forming means having image carriers; (ii) form an image by directly transferring the images onto transfer material placed on an endless carrier, the endless carrier being rotated; (iii) form a color difference detection pattern on the endless carrier; (iv) sample the color difference detection pattern; and (v) control the difference between a plurality of toner images which are directly formed in different colors on the transfer material, the image forming apparatus comprising: color difference detection pattern output means for outputting an image signal, the image signal producing a color difference detection pattern for detecting periodic rotational variations arising in the image forming apparatus to the image forming means; pattern detection means for detecting the color difference detection pattern formed on the endless carrier; phase detection means for detecting the phase of rotation of at least one of the image carriers of the image forming means on the basis of a detection signal received from the pattern detection means, for calculating a mean value of rotational variation data on the rotational phases, an address of at least a minimum and a maximum rotational variation of each color and an address of at least a rising edge and a falling edge of the rotational variations of each color based on the mean value of the variation data on the rotational phases, for averaging all the rotational phases of at least one of the image carrier and the endless carrier of the image forming means based on the addresses and for determining the phase of rotational variations of at least one of the image carrier and the endless carrier of the image forming means based on the mean value of the rotational variation data; and rotational phase control means for individually controlling the phase of rotation of at least one of the image carrier of the image forming means and the endless carrier based on the phase information detected by the phase detection means.

Claim 7

The image forming apparatus according to any one of claims 1 through 3, wherein the rotational phase control means individually controls the phase of rotation of at least one of the image carrier and the endless carrier of the image forming means such that the images to be transferred at a same transfer point on the endless carrier become in phase with each other.

Claim 8

The image forming apparatus according to any one of claims 1 through 3 further comprising: a plurality of image forming means having image carriers; and a control reference clock that is shared between the plurality of image forming means and controls the rotation of the image carrier of each image forming means.

Claim 9

The image forming apparatus according to any one of claims 1 through 3, wherein the rotational phase control means individually controls the phase of rotation of at least one of the image carrier and the endless carrier of the image forming means by idling it.

Claim 10

The image forming apparatus according to any one of claims 1 through 3, wherein the rotational phase control means individually controls the phase of rotation of at least one of the image carriers and the endless carrier of the image forming means by changing the rotating speed thereof.

Claim 11

The image forming apparatus according to any one of claims 1 through 3, wherein the rotational phase control means comprises detaching means for detaching the image carriers from the endless carrier of the image forming means when the rotational phase control means controls the phase of rotation of at least one of the image carrier and the endless carrier of the image forming means by changing the rotating speed thereof.

Claim 12

The image forming apparatus according to any one of claims 1 through 3, wherein that the rotational phase control means is arranged to carry out phase control operations at the timing during which no image is formed.

Claim 13

The image forming apparatus according to any one of claims 1 through 3, further comprising a plurality of image forming means having image carriers, wherein all the image carriers that possess the same mechanical characteristics from a manufacturing viewpoint are used as the image carriers of the plurality of image forming means.

Claim 14

The image forming apparatus according to claim 3, wherein the pattern detection means detects the phase of periodic rotational variations arising in at least one cycle of one of the image carrier and the endless carrier of the image forming means by detecting a color difference detection pattern that is N times (N: a natural number) the circumference of one rotation of the image carrier or the endless carrier of the image forming means, and the phase detection means detects the phase of rotation of at least one of the image carrier and the endless carrier of the image forming means on the basis of a detection signal of the color difference detection pattern.

Claim 15

The image forming apparatus according to claim 3, wherein the phase detection means detects a phase from the information, from which the color difference detection pattern corresponding to N rotations of the image carrier or the endless carrier of the image forming means have been detected, every one rotation of the image carrier or the endless carrier of the image forming means, and then detects the mean value of the phases corresponding to N rotations as the phase of rotation of the image carrier or the endless carrier of the image forming means.

Claim 16

The image forming apparatus according to claim 3, wherein the pattern detection means detects a pattern corresponding to about one rotation of the endless carrier for each color difference detection pattern of each color formed on the endless carrier.

Claim 17

The image forming apparatus according to claim 3, wherein the color difference detection pattern is sampled after completion of rough or fine adjustment of DC color registration correction cycle immediately after the power of the image forming apparatus has been turned on.

Claim 18

An image forming apparatus comprising: at least one image forming means having an image carrier for forming images in different colors; one of an endless carrier member and a transfer material held on the endless carrier onto which an image is directly transferred in different colors; rotational phase control means for individually controlling a phase rotation of at least one of the image carrier and the endless carrier; and phase detection means for (i) detecting the phase of rotation of at least one of the image carrier and the endless carrier of the image forming means every one rotation thereof; (ii) calculating the mean value of data on variations in the rotational phases; (iii) calculating an address of at least a minimum and a maximum rotational variation of each color, an address of at least a rising and falling edge of the rotational variations of each color, based on the mean value of the variation data on the rotational phases, the phase detection means further averaging the rotational phases of at least one of the image carrier and the endless carrier of the image forming means detected based on the addresses and determining the phase of variations in the rotation of at least one of the image carrier and the endless carrier of the image forming means based on the mean value of the variation data on the rotational phases.

Claim 19

An image forming apparatus comprising: at least one image forming means having an image carrier for forming images in different colors; one of an endless carrier member and a transfer material held on the endless carrier onto which an image is directly transferred in different colors; rotational phase control means for individually controlling a phase rotation of at least one of the image carrier and the endless carrier; and phase detection means for (i) detecting the phase of rotation of at least one of the image carrier and the endless carrier of the image forming means every one rotation thereof; (ii) calculating the mean value of data on variations in the rotational phases; (iii) calculating an address of at least a minimum and a maximum rotational variation of each color, an address of at least a rising and falling edge of the rotational variations of each color, based on the mean value of the variation data on the rotational phases, the phase detection means further averaging the rotational phases of at least one of the image carrier and the endless carrier of the image forming means detected based on the addresses and determining the phase of variations in the rotation of at least one of the image carrier and the endless carrier of the image forming means based on the mean value of the variation data on the rotational phases.