Image forming apparatus, image forming method and data control device

Abstract

The apparatus is adapted to deflect a light beam from a laser light source for each of the color components by means of a deflection mirror surface which oscillates, thereby making the light beam reciprocally scan in a main scanning direction. In this apparatus, however, only a light beam SL which scans in a first direction (+X) of the main scanning direction is irradiated in an effective image region on a photosensitive member, so as to form a latent image thereon. The resultant latent image is developed to form a toner image. Since image formation is performed using only the light beam SL which scans in the first direction (+X), the images may be formed at the consistent density irrespective of the image types. Furthermore, the scanning directions of the light beams SL for all the color components are uniformly defined to be the first direction (+X), so that the toner images of the respective colors may maintain the consistent density.

1 . An image forming apparatus comprising a plurality of image forming devices each of which forms a toner image of a color different from each other, wherein the toner images which are formed by said respective image forming devices are mutually superimposed on a transfer medium, thereby forming a color image, wherein 
 each of said plurality of image forming devices comprises: 
 a latent image carrier, on a surface of which is provided with an effective image region which has a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction; and  
 a latent image forming unit, which is structured to be capable of scanning a first scan region corresponding to the effective image region with a light beam from a light source in the main scanning direction by means of a deflection mirror surface which oscillates, and which irradiates the effective image region with only a light beam which scans in a first direction of the main scanning direction and the first scan region, thereby forming a latent image in the effective image region.  
   
   
   
       2 . The image forming apparatus of  claim 1 , further comprising a driver which is mechanically connected to one end of the latent image carrier in the main scanning direction and which drives the surface of said latent image carrier in the sub scanning direction, wherein 
 each of said plurality of latent image forming units is structured that the light beam is capable of scanning, in the main scanning direction, a second scan region which is broader than the first scan region,    each of said plurality of image forming devices comprises a detector which is disposed at a place on an opposite side from said driver in the main scanning direction and which detects a scanning light beam which is moving inside the second scan region and outside the first scan region and outputs a signal, and    each of said plurality of image forming devices controls a latent-image forming operation based on the detection signal outputted from said detector.    
   
   
       3 . The image forming apparatus of  claim 2 , wherein said driver is disposed on a downstream side in the first direction, whereas said detector is disposed on an upstream side in the first direction.  
   
   
       4 . An image forming method of forming a color image on a transfer medium by using a plurality of image forming devices each of which forms a latent image on a latent image carrier and forms a toner image by developing the latent image with toner of a color different from each other, the latent image carrier, on a surface of which is provided with an effective image region in a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction, said method comprising: 
 an image forming step, performed in each of the plurality of image forming devices, to form the latent image in the effective image region by irradiating the effective image region of the latent image carrier with a light beam from a light source scanning in a first direction of the main scanning direction by means of a deflection mirror surface which oscillates, and to form the toner image by developing the latent image; and    a transferring step to form a color image by superimposing the toner images which are formed in the plurality of image forming devices on the transfer medium.    
   
   
       5 . An image forming apparatus, comprising: 
 a latent image carrier, on a surface of which is provided with an effective image region which has a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction;    a latent image forming unit, which is structured to be capable of scanning a first scan region corresponding to the effective image region with a light beam from a light source in the main scanning direction by means of a deflection mirror surface which oscillates, and which irradiates the effective image region with a latent-image forming light beam, thereby forming a linear latent image in the effective image region; and    a direction controller which selectively switches a scanning direction of the latent-image forming light beam to a first direction in the main scanning direction or a second direction which is opposite to the first direction based on information related to latent-image forming position on said latent image carrier, wherein    said latent image forming unit irradiates the effective image region with a light beam which scans the first scan region in the scanning direction set by said direction controller as the latent-image forming light beam so as to form the linear latent image in the effective image region, thereby adjusting the forming position of the linear latent image on said latent image carrier.    
   
   
       6 . The image forming apparatus of  claim 5 , wherein said direction controller switches the scanning direction of the latent-image forming light beam by controlling a light emitting timing of the light source of said latent image forming unit.  
   
   
       7 . The image forming apparatus of  claim 5 , further comprising a storage section which stores, as the information, data indicating a relative positional relation between said latent image carrier and said latent image forming unit, wherein 
 said direction controller switches the scanning direction of the latent-image forming light beam based on the data stored in said storage section.    
   
   
       8 . The image forming apparatus of  claim 7 , wherein 
 a linear latent image formed on said latent image carrier when the relative positional relation between said latent image carrier and said latent image forming unit is a predetermined reference positional relation is defined as a reference line, and    the data indicates an amount of offset of the linear latent image relative to the reference line.    
   
   
       9 . The image forming apparatus of  claim 5 , further comprising an information detector which detects an adjustment toner image which is formed for the purpose of adjusting the latent-image forming position and determines, as the information, an amount of offset of the linear latent image relative to a predetermined reference line, wherein 
 said direction controller switches the scanning direction of the latent-image forming light beam based on the offset amount determined by the information detector.    
   
   
       10 . The image forming apparatus of  claim 5 , further comprising: 
 an input device which receives an input of the information; and    a storage section which stores the information inputted via said input device, wherein    said direction controller switches the scanning direction of the latent-image forming light beam based on the information stored in said storage section.    
   
   
       11 . The image forming apparatus of  claim 10 , wherein 
 an adjustment image for adjustment of the latent-image forming position is formed, and the adjustment image is transferred to a recording medium to permit the information to be visually examined.    
   
   
       12 . The image forming apparatus of  claim 5 , comprising a plurality of image forming devices each of which includes said latent image carrier and said latent image forming unit and forms a toner image of a color different from each other, wherein the toner images formed by said individual image forming devices are mutually superimposed on a transfer medium to form a color image, wherein 
 the information is set corresponding to each of said plurality of image forming devices, and    said direction controller switches the scanning direction of the latent-image forming light beam in each of said plurality of image forming devices based on the information.    
   
   
       13 . The image forming apparatus of  claim 12 , wherein 
 the respective scanning directions of the latent-image forming light beams in said individual latent image forming units are set so that the respective linear latent images are registered to a reference line which is common to said plurality of image forming devices or skewed in the same direction relative to the reference line.    
   
   
       14 . The image forming apparatus of  claim 12 , wherein a relative registration offset between the toner images formed by said plurality of image forming devices is defined as the information.  
   
   
       15 . The image forming apparatus of  claim 5 , further comprising a plurality of developing devices which form toner images by developing the latent images on said latent image carrier using toners of colors different from each other, wherein 
 a process to selectively position one of said plurality of developing devices at a development position according to the latent image formed on said latent image carrier and to transfer the toner image developed by the selected developing device onto the transfer medium, is repeated for the plural colors, thereby forming a color image with the plural toner images mutually superimposed on the transfer medium,    a relative registration offset between the plural toner images is defined as the information, and    said direction controller switches the scanning direction of the latent-image forming light beam for each color based on the information.    
   
   
       16 . The image forming apparatus of  claim 5 , wherein 
 an image which includes a line image region or a graphic image region is formed,    a position which the line image region is formed is defined as the information, and    said direction controller switches the scanning direction of the latent-image forming light beam for each linear latent image based on the information.    
   
   
       17 . The imager forming apparatus of  claim 5 , further comprising a driver which is mechanically connected to one end of the latent image carrier in the main scanning direction and which drives the surface of said latent image carrier in the sub scanning direction, wherein 
 said latent image forming unit is structured that the light beam is capable of scanning, in the main scanning direction, a second scan region which is broader than the first scan region,    a synchronization detector is disposed at a place on an opposite side from said driver in the main scanning direction, which detects a scanning light beam which is moving inside the second scan region and outside the first scan region and outputs a signal, and    an operation of forming the linear latent image is performed based on the detection signal outputted from the synchronization detector.    
   
   
       18 . The image forming apparatus of  claim 5 , wherein 
 said latent image forming unit is structured that the light beam is capable of scanning, in the main scanning direction, a second scan region which is broader than the first scan region,    synchronization detectors are disposed at places on both sides opposite in the main scanning direction, each of which detects a scanning light beam which is moving inside the second scan region and outside the first scan region and outputs a signal, and    an operation of forming the linear latent image is performed based on the detection signals outputted from the synchronization detectors.    
   
   
       19 . The image forming apparatus of  claim 18 , wherein the operation of forming the linear latent image is performed based on the detection signal outputted from the synchronization detector which is disposed on an upstream side in the scanning direction of the latent-image forming light beam.  
   
   
       20 . An image forming method wherein a linear latent image is formed on a latent image carrier, on a surface of which is provided with an effective image region in a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction, the linear latent image formed in the effective image region by irradiating the effective image region with a latent-image forming light beam, said method comprising: 
 an information acquisition step of acquiring information related to latent-image forming position on the latent image carrier;    a direction determination step of selectively determining a scanning direction of the latent-image forming light beam to be a first direction in the main scanning direction or to be a second direction opposite to the first direction, based on the information acquired in said information acquisition step; and    an image forming step of forming the latent image in the effective image region by irradiating the effective image region on the latent image carrier with a light beam from a light source by means of a deflection mirror surface which oscillates in the scanning direction determined in said direction determination step, thereby adjusting the latent-image forming position on the latent image carrier, and of forming a toner image by developing the latent image.    
   
   
       21 . A data control device for an image forming apparatus which causes a light source to emit a latent-image forming light beam while controlling the light source based on one line image data, and causes the latent-image forming light beam to scan the latent image carrier in a first direction or a second direction opposite to the first direction by means of a deflection mirror surface which oscillates, thereby forming a latent image corresponding to the one line image data on the latent image carrier, said data control device which controls the one line image data comprising: 
 a storage section which temporarily stores a plurality of image information items which constitutes the one line image data; and    a direction switching section which switches, based on information related to latent-image forming position on the latent image carrier, an order to read out the image information items from said storage section to control the light source based on the image information items.    
   
   
       22 . The data control device of  claim 21 , wherein 
 said storage section includes a forward line buffer which temporarily stores the one line image data and forwardly outputs the plurality of image information items which constitutes the one line image data from a head image information item, and a backward line buffer which temporarily stores the one line image data and backwardly outputs the plurality of image data items which constitutes the one line image data from the last image information item, and    said direction switching section controls the light source based on the image information items in a reading order which are read out from said forward line buffer when the latent image is formed with the latent-image forming light beam which scans in the first direction, whereas controls the light source based on the image information items in a reading order which are read out from said backward line buffer when the latent image is formed with the latent-image forming light beam which scans in the second direction.    
   
   
       23 . An image forming apparatus which performs printing by transferring a toner image, formed by developing a latent image, onto a recording medium, said apparatus comprising: 
 a latent image carrier, on a surface of which is provided with an effective image region which has a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction;    a latent image forming unit, which is structured to be capable of scanning a first scan region corresponding to the effective image region with a light beam from a light source in the main scanning direction by means of a deflection mirror surface which oscillates, and which irradiates the effective image region with a latent-image forming light beam, thereby forming a latent image in the effective image region; and    a direction controller which selectively switches, based on information related to print mode, between a reciprocal scan mode in which the latent-image forming light beam reciprocally scans in the main scanning direction and a one-way scan mode in which the latent-image forming light beam scans in one-way in either a first direction in the main scanning direction or a second direction opposite to the first direction.    
   
   
       24 . The image forming apparatus of  claim 23 , wherein said direction controller switches the scan mode by controlling a light emitting timing of the light source of said latent image forming unit.  
   
   
       25 . The image forming apparatus of  claim 23 , wherein high-resolution printing of printing at a predetermined first resolution, and low-resolution printing of printing at a second resolution lower than the first resolution are provided as the print modes, and 
 said direction controller sets the scan mode, based on the information, to the reciprocal scan mode when the high-resolution printing is performed, whereas to the one-way scan mode when the low-resolution printing is performed.    
   
   
       26 . The image forming apparatus of  claim 23 , wherein 
 normal toner amount printing of printing using a usual first toner amount and toner saving printing of printing using a second toner amount which is less than the first toner amount are provided as the print modes,    said direction controller sets the scan mode, based on the information, to the reciprocal scan mode when the normal toner amount printing is performed, whereas to the one-way scan mode when the toner saving printing is performed.    
   
   
       27 . The image forming apparatus of  claim 23 , wherein 
 thin paper printing of printing on a recording medium having a thickness of a predetermined value or less, and thick paper printing of printing on a recording medium having a thickness of more than the predetermined value are provided as the print modes, and    said direction controller sets the scan mode, based on the information, to the reciprocal scan mode when the thin paper printing is performed, whereas to the one-way scan mode when the thick paper printing is performed.    
   
   
       28 . The image forming apparatus of  claim 23 , wherein 
 normal quality printing in which printing is performed allowing for an occurrence of density difference in the main scanning direction, and high quality printing in which printing is performed suppressing the density difference in the main scanning direction, are provided as the print modes, and    said direction controller sets the scan mode, based on the information, to the reciprocal scan mode when the normal quality printing is performed, whereas to the one-way scan mode when the high quality printing is performed.    
   
   
       29 . The image forming apparatus of  claim 28 , wherein 
 during printing on a single recording medium in which a region to perform the normal quality printing and a region to perform the high quality printing are positioned juxtaposed along the sub scanning direction, said direction controller switches the scan mode according to the respective regions.    
   
   
       30 . The image forming apparatus of  claim 28 , wherein said direction controller switches the scanning direction of the latent-image forming light beam to either the first direction or the second direction according to the position of the region to perform the high quality printing in the main scanning direction.  
   
   
       31 . The imager forming apparatus of  claim 23 , further comprising a driver which is mechanically connected to one end of the latent image carrier in the main scanning direction and which drives the surface of said latent image carrier in the sub scanning direction, wherein 
 said latent image forming unit is structured that the light beam is capable of scanning, in the main scanning direction, a second scan region which is broader than the first scan region,    a synchronization detector is disposed at a place on an opposite side from said driver in the main scanning direction, which detects a scanning light beam which is moving inside the second scan region and outside the first scan region and outputs a signal, and    an operation of forming the linear latent image is performed based on the detection signal outputted from the synchronization detector.    
   
   
       32 . The image forming apparatus of  claim 23 , wherein 
 said latent image forming unit is structured that the light beam is capable of scanning, in the main scanning direction, a second scan region which is broader than the first scan region,    synchronization detectors are disposed at places on both sides opposite in the main scanning direction, each of which detects a scanning light beam which is moving inside the second scan region and outside the first scan region and outputs a signal, and    an operation of forming the linear latent image is performed based on the detection signals outputted from the synchronization detectors.    
   
   
       33 . The image forming apparatus of  claim 32 , wherein the operation of forming the linear latent image is performed based on the detection signal outputted from the synchronization detector which is disposed on an upstream side in the scanning direction of the latent-image forming light beam.  
   
   
       34 . An image forming method of performing a printing operation in which a latent image is formed on a latent image carrier, on a surface of which is provided with an effective image region in a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction, the latent image formed in the effective image region by irradiating the effective image region with a latent-image forming light beam, and a toner image, formed by developing the latent image, is transferred onto a recording medium thereafter, said method comprising: 
 an information acquisition step of acquiring information related to print mode;    a scan mode determination step of selectively switching, based on the information acquired in said information acquisition step, either to a reciprocal scan mode in which the latent-image forming light beam reciprocally scans in the main scanning direction or to a one-way scan mode in which the latent-image forming light beam scans in one-way either in a first direction in the main scanning direction or in a second direction opposite to the first direction; and    an image forming step of forming the latent image in the effective image region by irradiating the effective image region on the latent image carrier with a light beam from a light source, by means of a deflection mirror surface which oscillates, in the scanning direction determined in said scan mode determination step, and of forming the toner image by developing the latent image.    
   
   
       35 . A data control device for an image forming apparatus which performs a printing operation in which a light source is caused to emit a latent-image forming light beam while controlling the light source based on one line image data, and the latent-image forming light beam is caused to scan the latent image carrier in a first direction or a second direction opposite to the first direction by means of a deflection mirror surface which oscillates, thereby forming a latent image corresponding to the one line image data on the latent image carrier, and in which a toner image, formed by developing the latent image, is transferred onto a recording medium thereafter, said data control device which controls the one line image data comprising: 
 a storage section which temporarily stores a plurality of image information items which constitutes the one line image data; and    a direction switching section which switches, based on information related to print mode, an order to read out the image information items from said storage section to control the light source based on the image information items.    
   
   
       36 . The data control device of  claim 35 , wherein 
 said storage section includes a forward line buffer which temporarily stores the one line image data and forwardly outputs the plurality of image information items which constitutes the one line image data from a head image information item, and a backward line buffer which temporarily stores the one line image data and backwardly outputs the plurality of image data items which constitutes the one line image data from the last image information item, and    said direction switching section controls the light source based on the image information items in a reading order which are read out from said forward line buffer when the latent image is formed with the latent-image forming light beam which scans in the first direction, whereas controls the light source based on the image information items in a reading order which are read out from said backward line buffer when the latent image is formed with the latent-image forming light beam which scans in the second direction.    
   
   
       37 . An image forming apparatus which performs printing by transferring a toner image, formed by developing a latent image, onto a recording medium, said apparatus comprising: 
 a latent image carrier, on a surface of which is provided with an effective image region which has a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction;    a latent image forming unit, which is structured to be capable of scanning a scan region corresponding to the effective image region with a light beam from a light source in the main scanning direction by means of a deflection mirror surface which oscillates, and which irradiates the effective image region with a latent-image forming light beam, thereby forming a latent image in the effective image region; and    a direction controller which selectively switches, based on information related to print mode, between a reciprocal scan mode in which the latent-image forming light beam reciprocally scans in the main scanning direction and a one-way scan mode in which the latent-image forming light beam scans in one-way in either a first direction in the main scanning direction or a second direction opposite to the first direction, wherein    normal toner amount printing of printing using a usual first toner amount and toner saving printing of printing using a second toner amount which is less than the first toner amount are provided as the print modes,    said latent image forming unit sets a light quantity of the latent-image forming light beam to the same value in either print modes, and    said direction controller sets the scan mode, based on the information, to the reciprocal scan mode when the normal toner amount printing is performed, whereas to the one-way scan mode when the toner saving printing is performed.    
   
   
       38 . The image forming apparatus of  claim 37 , wherein said direction controller switches the scan mode by controlling a light emitting timing of the light source of said latent image forming unit.  
   
   
       39 . The image forming apparatus of  claim 37 , wherein 
 tonal printing of printing a toner image which includes half tone and binary printing of printing a toner image free from the half tone are further provided as the print modes, and    said direction controller sets the scan mode to the reciprocal scan mode in a case where the information indicates to perform the tonal printing and the toner saving printing.    
   
   
       40 . The image forming apparatus of  claim 39 , wherein 
 during the toner saving printing on a single recording medium in which a region to perform the tonal printing and a region to perform the binary printing are positioned juxtaposed along the sub scanning direction, said direction controller switches the scan mode according to the respective regions.    
   
   
       41 . An image forming method of performing a printing operation in which a latent image is formed on a latent image carrier, on a surface of which is provided with an effective image region in a predetermined width in a main scanning direction, and the surface of which is driven in a sub scanning direction which is approximately orthogonal to the main scanning direction, the latent image formed in the effective image region by irradiating the effective image region with a latent-image forming light beam, and a toner image, formed by developing the latent image, is transferred onto a recording medium thereafter, said method comprising: 
 an information acquisition step of acquiring information related to print modes which includes normal toner amount printing of printing using a usual first toner amount and toner saving printing of printing using a second toner amount which is less than the first toner amount;    a scan mode determination step of determining the scan mode, based on the information acquired in said information acquisition step, to a reciprocal scan mode in which the latent-image forming light beam reciprocally scans in the main scanning direction when the normal toner amount printing is performed, whereas to a one-way scan mode in which the latent-image forming light beam scans in one-way either in a first direction in the main scanning direction or in a second direction opposite to the first direction when the toner saving printing is performed; and    an image forming step of forming the latent image in the effective image region by irradiating the effective image region on the latent image carrier with a light beam from a light source, by means of a deflection mirror surface which oscillates, in the scanning direction determined in said scan mode determination step, and of forming the toner image by developing the latent image, wherein    a light quantity of the latent-image forming light beam is set to the same value in either print modes in said image forming step.