JP2014202980A - Image forming unit and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve convenience.SOLUTION: An image carrier rotatably supported through an image carrier rotary shaft and carrying a latent image and a developer carrier rotatably supported through a developer carrier rotary shaft parallel to the image carrier rotary shaft, in a state of being pressed to the image carrier and carrying a developer for developing the latent image are provided so that one of the image carrier and the developer carrier can be displaced relative to the other in one direction parallel to the image carrier rotary shaft. Thus, at least one of the image carrier and the developer carrier is displaced according to the use state of the image carrier, so that the wear of the image carrier caused by contact with the developer carrier through the developer is totally suppressed, the service life of the image carrier can be extended, and the convenience can be improved.

Description

  The present invention relates to an image forming unit and an image forming apparatus, and is suitable for application to, for example, a color electrophotographic printer (hereinafter also referred to as a color printer) and an image forming unit provided in the color printer. is there.

  A conventional color printer includes, for example, a photosensitive drum as an image carrier formed by providing a photoconductive layer having a predetermined thickness on the outer peripheral surface of a drum-like conductive substrate, and a developing roller as a developer carrier. Are detachably provided.

  In an image forming unit of a color printer, a photosensitive drum is provided so as to be rotatable about its rotation axis (hereinafter also referred to as a drum rotation axis).

  Further, in the image forming unit of the color printer, the developing roller has a part of the surface pressed against a part of the surface of the photosensitive drum, and the rotating shaft of the developing roller (hereinafter also referred to as a roller rotating shaft). Is provided so as to be rotatable around the center.

  The color printer rotates the photosensitive drum when forming a print image, and rotates the developing roller in a direction opposite to the rotation direction of the photosensitive drum while pressing a part of the surface of the developing roller against a part of the surface of the photosensitive drum. Rotate in the direction.

  In this state, the color printer exposes the surface of the photosensitive drum (that is, the surface of the photoconductive layer) according to the printed image while charging, so that, for example, the exposed portion of the surface of the photosensitive drum is more exposed than the surrounding portion. An electrostatic latent image having a high potential is formed.

  Further, the color printer charges and carries toner as a developer on the surface of the developing roller, and presses the toner against the electrostatic latent image forming portion on the surface of the photosensitive drum.

  Accordingly, the color printer transfers (attaches) the toner on the surface of the developing roller to the electrostatic latent image on the surface of the photosensitive drum, and develops the electrostatic latent image (that is, visualizes with the toner).

  The color printer then transfers the toner image as a developer image obtained by developing the electrostatic latent image on the surface of the photosensitive drum to the surface of the recording paper as a transfer medium. A print image was formed on the image (for example, see Patent Document 1).

JP 2012-58364 A (second page, fourth page, FIG. 10, FIG. 11)

  However, in the conventional color printer, for example, when the surface of the developing roller is pressed against the surface of the photosensitive drum via the toner having a biased layer thickness, or when the developing roller is pressed against the photosensitive drum in a bent state, With the rotation of the photosensitive drum and the developing roller, the surface of the photosensitive drum may be gradually worn, and the photoconductive layer may be unevenly thinned.

  In such a case, in the color printer, the portion of the photoconductive layer of the photosensitive drum in which the amount of film reduction is extremely large is difficult to be charged (that is, it is difficult to hold the charge) and the potential is low.

  As a result, in a color printer, toner adheres to the photoconductive layer of the photosensitive drum where the amount of film loss is significantly large even if it is not exposed, and the toner appears as printing stains on the surface of the recording paper. become.

  In color printers, if the surface of the recording paper is stained due to a significant increase in the amount of photoconductive layer on the photosensitive drum, the life of the photosensitive drum is exhausted. Need to be exchanged as.

  Therefore, if the conventional color printer can extend the service life of the photosensitive drum by reducing the unevenness of the photoconductive layer, the convenience can be improved by reducing the number of times the photosensitive drum is replaced. .

  However, since the conventional color printer is not configured to extend the service life of the photosensitive drum, there is a problem that it is difficult to improve convenience.

  The present invention has been made in consideration of the above points, and intends to propose an image forming unit and an image forming apparatus that can improve convenience.

  In order to solve this problem, in the present invention, an image carrier that is rotatably supported via an image carrier rotation shaft and carries a latent image, and an image carrier rotation shaft that is pressed against the image carrier. A developer carrying member that is rotatably supported via a developer carrying member rotating shaft parallel to the developer carrying a developer for developing a latent image, and one of the image carrier and the developer carrying member is the other. In contrast, it is arranged so as to be relatively displaceable in one direction parallel to the rotation axis of the image carrier.

  Therefore, in the present invention, by displacing at least one of the image carrier and the developer carrier in accordance with the use state of the image carrier, the image carrier is brought into contact with the developer carrier through the developer. Abrasion can be suppressed as a whole, and the service life of the image carrier can be extended.

  According to the present invention, an image carrier that is rotatably supported through an image carrier rotation axis and carries a latent image, and a developer that is pressed against the image carrier and is parallel to the image carrier rotation axis. A developer carrier that is rotatably supported via a carrier rotating shaft and carries a developer for developing a latent image, and one of the image carrier and the developer carrier is image-bearing with respect to the other. By providing it so as to be relatively displaceable in one direction parallel to the body rotation axis, it is possible to displace at least one of the image carrier and the developer carrier according to the usage state of the image carrier. In addition, the image carrier can suppress wear due to contact with the developer carrier through the developer as a whole, thereby extending the service life of the image carrier and thus improving the convenience of image formation. Unit and image forming apparatus can be realized

1 is a schematic cross-sectional view showing an internal configuration of a color printer according to a first embodiment. 2 is a schematic cross-sectional view showing a configuration of an image forming unit (1). FIG. It is a rough-line top view which shows the structure of an image forming unit (2). 2 is a block diagram illustrating a circuit configuration of a color printer. FIG. FIG. 6 is a schematic top view for explaining the displacement of the photosensitive drum in the first continuous paper passing printing test. It is a basic diagram which shows the detection result of the film | membrane reduction amount of the photosensitive drum used for the 1st and 2nd continuous paper-pass printing test. It is a rough-line sectional view which shows the internal structure of the color printer by 2nd Embodiment. 2 is a schematic cross-sectional view showing a configuration of an image forming unit (1). FIG. It is a rough-line top view which shows the structure of an image forming unit (2).

The best mode for carrying out the invention (hereinafter, also referred to as an embodiment) will be described below with reference to the drawings. The description will be given in the following order.
(1) First embodiment (2) Second embodiment (3) Other embodiments

(1) First Embodiment (1-1) Internal Configuration of Color Printer In FIG. 1, reference numeral 1 denotes a color printer according to the first embodiment as a whole. The color printer 1 has, for example, a substantially box-shaped housing (hereinafter also referred to as a printer housing) 2 having an opening 2A formed at the upper end.

  Incidentally, in the following description, when the color printer 1 is viewed facing the front surface 2B of the printer housing 2, the upper direction of the color printer 1 indicated by the arrow a1 in the drawing is also referred to as the upward direction of the printer. The direction opposite to the upward direction of the printer is also referred to as the downward direction of the printer.

  In the following description, when it is not necessary to distinguish the upper direction of the printer and the lower direction of the printer, these are collectively referred to as a printer vertical direction.

  Further, in the following description, the direction in front of the color printer 1 indicated by the arrow b1 in the drawing when the color printer 1 is viewed facing the front surface 2B of the printer housing 2 is also referred to as the front direction of the printer. A direction opposite to the front direction of the printer is also referred to as a rear direction of the printer.

  In the following description, when there is no need to particularly distinguish the front direction of the printer and the rear direction of the printer, these are collectively referred to as the front-rear direction of the printer.

  Further, in the following description, the left direction of the color printer 1 indicated by the arrow c1 in the figure when the color printer 1 is viewed facing the front surface 2B of the printer housing 2 is also referred to as the printer left direction. The direction opposite to the printer left direction is also referred to as the printer right direction.

  In the following description, when there is no need to particularly distinguish the printer left direction and the printer right direction, these are also collectively referred to as the printer left-right direction.

  For example, the printer housing 2 is provided with an open / close cover 3 at its upper end through a hinge portion (not shown) provided on the rear surface 2C of the printer housing 2.

  That is, at the upper end of the printer housing 2, the opening / closing cover 3 is centered around a hinge axis (not shown) parallel to the printer left-right direction, and the one-rotation direction indicated by the arrow d1 in the drawing, The opening 2A can be opened and closed by rotating in the other reverse rotation direction.

  The open / close cover 3 has a concave portion (hereinafter also referred to as a recording paper delivery section) for placing the recording paper 5 as a transfer medium on which a print image is formed and delivering it to the user at the rear end of the upper surface 3A. ) 3AX is formed.

  The open / close cover 3 is provided at a predetermined position on the rear inner wall of the recording paper delivery unit 3AX at a predetermined position on the inner wall of the recording paper delivery unit 3AX. (Not shown) is formed.

  On the other hand, in the printer casing 2, a cassette (hereinafter also referred to as a recording sheet cassette) 6 for loading a plurality of recording sheets 5 in a stacked state at the lower end is pulled out to the front side of the printer casing 2. Thus, it is provided so that it can be removed and inserted from the front side.

  In the printer housing 2, an image forming unit 7 is provided on the recording paper cassette 6 to form a print image so as to print a color image to be printed on the surface of the recording paper 5. .

  The image forming unit 7 develops electrostatic latent images representing different color components of a printed image using toner as a developer to form a toner image as a developer image, for example, four image formations Units 10 to 13 are included.

  The image forming unit 7 also has a transfer unit 14 for transferring the toner images formed by the image forming units 10 to 13 to the surface of the recording paper 5.

  Further, the image forming unit 7 also has a fixing unit 15 for forming a print image so that the toner image transferred to the surface of the recording paper 5 by the transfer unit 14 is fixed on the surface of the recording paper 5. .

  In this case, the four image forming units 10 to 13 are similarly configured except that different color toners are used for developing the electrostatic latent image. It is detachably mounted so as to be arranged in order.

  Incidentally, in the following description, of the four image forming units 10 to 13 that are detachably mounted in the printer housing 2, the image forming unit 10 that is positioned at the forefront in the printer housing 2 will be described for convenience. Also called the first image forming unit 10.

  In the following description, among the four image forming units 10 to 13 that are detachably mounted in the printer housing 2, the image forming unit 11 that is positioned second in the printer housing 2 from the front is described. For convenience, it is also referred to as a second image forming unit 11.

  Further, in the following description, among the four image forming units 10 to 13 that are detachably mounted in the printer housing 2, the image forming unit 12 that is located third in the printer housing 2 from the front is described. For convenience, it is also referred to as a third image forming unit 12.

  Further, in the following description, among the four image forming units 10 to 13 that are detachably mounted in the printer housing 2, the image forming unit 10 to 13 is positioned fourth from the front in the printer housing 2 (that is, the rearmost position). The image forming unit 13 is also referred to as a fourth image forming unit 13 for convenience.

  The transfer unit 14 extends from the bottom of the first image forming unit 10 to the bottom of the fourth image forming unit 13 (that is, the first to fourth image forming units 10 to 13) in the center of the printer housing 2. Is located underneath).

  Further, the fixing unit 15 is disposed behind the transfer unit 14 that is closer to the rear end in the center of the printer housing 2.

  In the printer housing 2, a plurality of stacked recording sheets 5 are separated one by one from the recording sheet cassette 6 in order from the top at a predetermined position facing the upper front end of the stored recording sheet cassette 6. A pair of recording paper feeding rollers 16 and 17 for feeding out the paper are provided so as to be rotatable in one rotation direction about a rotation axis parallel to the horizontal direction of the printer.

  Also, a pair of recordings for transporting the recording paper 5 to a predetermined position obliquely in front of the pair of recording paper feeding rollers 16 and 17 while being sent out while being sandwiched between the surfaces. The paper transport rollers 18 and 19 are provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other around a rotation axis parallel to the horizontal direction of the printer.

  Further, the recording paper 5 is also transported into the printer housing 2 in front of the pair of recording paper transport rollers 18 and 19 which is obliquely above the rear of the transfer section 14 while being sandwiched between the surfaces. A pair of recording paper transport rollers 20 and 21 are provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other around a rotation axis parallel to the left-right direction of the printer.

  In the printer housing 2, a plurality of conveyance guides (not shown) for guiding the conveyance of the recording paper 5 between the pair of recording paper feeding rollers 16 and 17 and the pair of recording paper conveyance rollers 18 and 19. ) Is arranged.

  Thus, the recording paper 5 is formed in the printer casing 2 for forming a print image (that is, for printing) by a pair of recording paper feeding rollers 16 and 17 and a plurality of conveyance guides at the lower front end. A feeding conveyance path 22 for feeding out from the cassette 6 and conveying it is formed.

  In the printer housing 2, a plurality of conveyance guides (not shown) for guiding conveyance of the recording paper 5 between the pair of recording paper conveyance rollers 18 and 19 and the pair of recording paper conveyance rollers 20 and 21. And a posture correction guide (not shown) for correcting the conveyance posture of the recording paper 5 (that is, correcting skew).

  As a result, the recording paper 5 conveyed by the feeding conveyance path 22 is continuously transferred to the central front end portion of the printer casing 2 by the plurality of recording paper conveyance rollers 18 to 21, the plurality of conveyance guides, and the posture correction guide. A posture correction conveyance path 23 for conveyance to the unit 14 is formed.

  In addition to this, a pair of recording paper transport rollers 25 for transporting the recording paper 5 to a predetermined position behind the fixing unit 15 so as to be sent out while being sandwiched between the surfaces of each other. , 26 are provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other about a rotation axis parallel to the horizontal direction of the printer.

  Further, in the open / close cover 3, the recording paper 5 is sent out while being sandwiched between the surfaces of the recording paper discharge rollers in the vicinity of the recording paper discharge opening at the rear end portion above the pair of recording paper conveying rollers 25 and 26. A pair of recording paper discharge rollers 27 and 28 for discharging from the recording paper discharge port are provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other around a rotation axis parallel to the horizontal direction of the printer. It has been.

  In the printer casing 2, a plurality of conveyance guides (not shown) for guiding the conveyance of the recording paper 5 are arranged between the fixing unit 15 and the pair of recording paper conveyance rollers 25 and 26. Yes.

  In the printer housing 2 and the opening / closing cover 3, a plurality of recording papers 5 are guided between the pair of recording paper transport rollers 25, 26 and the pair of recording paper discharge rollers 27, 28. A conveyance guide (not shown) is arranged.

  As a result, in the printer casing 2 and in the open / close cover 3, the fixing unit 15 includes a pair of recording paper transport rollers 25 and 26, a pair of recording paper discharge rollers 27 and 28, and a plurality of transport guides at the rear end. Thus, a discharge conveyance path 29 is formed for conveying the recording paper 5 having the printed image formed on the surface thereof from the fixing unit 15 to the recording paper discharge port and discharging it.

  The first to fourth image forming units 10 to 13 each carry an electrostatic latent image, and a photosensitive drum as an image carrier that carries a toner image obtained by developing the electrostatic latent image with toner. 35 to 38 are rotatably provided in a state in which the conductive metal image bearing member rotation shaft (hereinafter also referred to as a drum rotation shaft) is parallel to the printer left-right direction.

  The printer housing 2 is provided with motors (hereinafter also referred to as unit drive motors) as image carrier rotation driving units for the first to fourth image forming units 10 to 13.

  In each of the first to fourth image forming units 10 to 13, the drum rotation shafts of the photosensitive drums 35 to 38 are connected to the output shafts of the corresponding unit drive motors via a plurality of gears (not shown), for example.

  In the following description, a plurality of gears for connecting the drum rotation shafts of the photosensitive drums 35 to 38 of the first to fourth image forming units 10 to 13 to the output shaft of the unit drive motor are connected to the unit motor. Also called a gear.

  As a result, the first to fourth image forming units 10 to 13 move the photosensitive drums 35 to 38 around the drum rotation axis, for example, in the other rotation direction according to the operation of the corresponding unit drive motor at the time of printing image formation. Can be rotated to.

  Further, the first to fourth image forming units 10 to 13 respectively expose the surfaces of the photosensitive drums 35 to 38 and LED (Light Emitting Diode) heads 40 to 43 as exposure units that form electrostatic latent images on the surfaces. Is also provided.

  As a result, the first image forming unit 10 exposes the surface of the photosensitive drum 35 by the LED head 40 while rotating the photosensitive drum 35 in the other rotation direction at the time of forming the print image, for example, black (K) of the print image. In addition, an electrostatic latent image representing the color components can be formed, and the electrostatic latent image can be developed using black (K) toner to form a toner image.

  Further, the second image forming unit 11 exposes the surface of the photosensitive drum 36 by the LED head 41 while rotating the photosensitive drum 36 in the other rotation direction at the time of forming the print image, for example, yellow (Y) of the print image. An electrostatic latent image representing a color component can be formed, and the electrostatic latent image can be developed using yellow (Y) toner to form a toner image.

  Further, the third image forming unit 12 exposes the surface of the photosensitive drum 37 by the LED head 42 while rotating the photosensitive drum 37 in the other rotation direction at the time of forming the print image, for example, magenta (M) of the print image. An electrostatic latent image representing a color component can be formed, and the electrostatic latent image can be developed using magenta (M) toner to form a toner image.

  Further, the fourth image forming unit 13 exposes the surface of the photosensitive drum 38 by the LED head 43 while rotating the photosensitive drum 38 in the other rotation direction at the time of forming the print image, for example, cyan (C) of the print image. An electrostatic latent image representing a color component can be formed, and the electrostatic latent image can be developed using cyan (C) toner to form a toner image.

  On the other hand, the transfer unit 14 is rotated obliquely below the fourth image forming unit 13 around a rotation axis (hereinafter also referred to as a drive roller rotation axis) in which the drive roller 45 is parallel to the horizontal direction of the printer. It is provided as possible.

  The transfer unit 14 is provided below the first image forming unit 10 so that the tension roller 46 can rotate around a rotation axis (hereinafter also referred to as a tension roller rotation axis) that is parallel to the printer left-right direction. It has been.

  Further, a transfer belt 47 is stretched across the transfer unit 14 from the drive roller 45 to the tension roller 46 to electrostatically attract the recording paper 5 for transferring the toner image.

  As a result, the transfer unit 14 includes the four photosensitive drums 35 to 35 with the surface of the upper flat part of the pair of flat parts between the drive roller 45 and the tension roller 46 in the transfer belt 47 parallel to the drum rotation axes. It is made to contact the lower part used as the opposing part of 38 surface.

  In the following description, the upper flat portion of the pair of flat portions between the drive roller 45 and the tension roller 46 in the transfer belt 47 is also referred to as an upper flat portion, and the lower flat portion is also referred to as a lower flat portion. .

  The transfer belt 47 is formed of a resin material such as polyamideimide or polyamide to which a conductive material such as carbon is added so as to have predetermined conductivity and mechanical strength.

  The transfer unit 14 has an output shaft of a motor (not shown) (hereinafter also referred to as a transfer unit drive motor) as a transfer drive unit in the printer housing 2 via a plurality of gears (not shown), for example. It is connected to.

  Thus, the transfer unit 14 rotates the drive roller 45 in the direction of, for example, one rotation around the drive roller rotation axis in accordance with the operation of the transfer unit drive motor when the print image is formed, and in conjunction with the rotation. The transfer belt 47 can be rotated in one rotation direction together with the tension roller 46.

  As a result, the transfer unit 14 causes the transfer belt 47 to statically place the recording paper 5 conveyed from the recording paper cassette 6 through the feeding conveyance path 22 and the posture correction conveyance path 23 onto the upper flat portion when the print image is formed. Receive it as if it was electroadsorbed.

  At this time, the transfer unit 14 causes the transfer belt 47 to transfer the recording paper 5 from the upstream side to the downstream side in the transport direction while keeping the surface thereof upward for transferring the toner image and in parallel with each drum rotation shaft. The recording sheet 5 can be conveyed and brought into contact with the lower portions of the surfaces of the four photosensitive drums 35 to 36 in order, and then delivered to the fixing unit 15.

  Incidentally, in the color printer 1 according to the first embodiment, the conveyance direction of the recording paper 5 by the transfer belt 47 of the transfer unit 14 is the backward direction of the printer.

  Therefore, in the color printer 1 according to the first embodiment, when the recording paper 5 is conveyed via the transfer belt 47 of the transfer unit 14, the upstream side in the conveyance direction is the front side, and the downstream side is the rear side. .

  In the transfer unit 14, four transfer rollers 48 to 51 corresponding to the four photosensitive drums 35 to 38 are arranged on the inner side of the transfer belt 47 in order from the front to the rear, and are parallel to the horizontal direction of the printer. It is provided so as to be rotatable about a rotating shaft (hereinafter also referred to as a transfer roller rotating shaft).

  As a result, the transfer unit 14 replaces the upper part, which is a part of the surface of each of the four transfer rollers 48 to 51, with the corresponding part of the surface of the corresponding photosensitive drum 35 to 38 through the upper flat part of the transfer belt 47. Is pressed against the lower part.

  Incidentally, in the following description, among the four transfer rollers 48 to 51 of the transfer unit 14, the transfer roller 48 positioned at the front is also referred to as a first transfer roller 48 for the sake of convenience, and is the transfer positioned second from the front. The roller 49 is also referred to as a second transfer roller 49 for convenience.

  In the following description, among the four transfer rollers 48 to 51 of the transfer unit 14, the transfer roller 50 positioned third from the front is also referred to as the third transfer roller 50 for convenience and is positioned fourth from the front. The transfer roller 51 that performs (that is, the rearmost position) is also referred to as a fourth transfer roller 51 for convenience.

  The first to fourth transfer rollers 48 to 51 are each electrically connected to a predetermined voltage source (hereinafter also referred to as a transfer roller voltage source) in the printer housing 2 to form a print image. A DC voltage having a predetermined voltage value is applied by the transfer roller voltage source.

  As a result, the transfer unit 14 causes the recording paper 5 conveyed by the transfer belt 47 to form the upper portion of the surface of the first to fourth transfer rollers 48 to 51 and the corresponding four photosensitive drums 35 to 35 when forming a print image. On the surfaces of the four photosensitive drums 35 to 38 by the action of the Coulomb force generated by the application of the DC voltage to the first to fourth transfer rollers 48 to 51 while being sandwiched in sequence with the lower portion of the surface of the surface 38. The toner image can be transferred onto the surface of the recording paper 5.

  In this way, the transfer unit 14 can transfer the toner images for four colors onto the surface of the recording paper 5 and deliver the recording paper 5 onto which the toner image has been transferred to the fixing unit 15.

  For example, the transfer unit 14 charges the surface of the photosensitive drums 35 to 38 when the toner images are continuously transferred to the surfaces of the plurality of recording papers 5 while sequentially transporting the plurality of recording papers 5. Defective toner may transfer and adhere to the surface of the transfer belt 47 in some cases.

  Therefore, the transfer unit 14 is a substantially flat box type waste toner tank as a waste developer container provided with a belt cleaning blade 52 as an attached developer removing unit for removing toner attached to the surface of the transfer belt 47. 53.

  The belt cleaning blade 52 is formed, for example, in a substantially strip shape from urethane rubber. The waste toner tank 53 has a toner intake opening at one end of the top plate.

  Further, in the waste toner tank 53, one edge portion of the belt cleaning blade 52 is joined to an edge on one end side at the toner intake port, and the other edge portion of the belt cleaning blade 52 protrudes obliquely above the toner intake port. I am letting.

  The waste toner tank 53 having such a configuration is arranged directly below the transfer belt 47 with the longitudinal direction of the belt cleaning blade 52 being parallel to the left-right direction of the printer.

  The waste toner tank 53 presses the other edge of the belt cleaning blade 52 that faces obliquely upward to the lower flat surface of the transfer belt 47.

  As a result, when the transfer belt 47 is rotated in one rotation direction, the transfer unit 14 removes the toner adhering to the surface of the transfer belt 47 by the belt cleaning blade 52 and passes the toner through the toner intake port. Can be dropped into the waste toner tank 53.

  In this way, the transfer unit 14 removes the toner attached to the surface of the transfer belt 47 so that the transfer belt 47 can be repeatedly used for transferring the toner image onto the recording paper 5.

  The fixing unit 15 has a substantially box-shaped fixing unit housing 55. The fixing unit housing 55 is formed with a recording paper path for passing the recording paper 5 in the center.

  The fixing unit housing 55 has the upper end facing the fourth image forming unit 13 with one opening of the recording paper path facing the front and the other opening facing the rear. It is arranged to face the transfer unit 14.

  Incidentally, in the following description, in the fixing unit housing 55, one opening portion facing the front side of the recording paper path is also called a recording paper intake port, and the other opening portion facing the rear side is called the recording paper discharge port. Also called.

  Further, the fixing unit housing 55 is provided with a heat generating roller 56 at the upper end portion thereof so as to be rotatable around a rotation axis 56A (hereinafter also referred to as a heat generating roller rotation axis) that is parallel to the left-right direction of the printer.

  For example, the heat roller 56 is formed by coating a heat-resistant elastic layer made of silicone rubber on a heat-generating roller rotating shaft 56A made of cylindrical aluminum, and the heat-resistant elastic layer is coated with PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether-copolymer) Combined) The tube is covered and formed.

  The fixing unit 15 includes a heating roller rotating shaft 56A of the heating roller 56, for example, a motor (not shown) serving as a fixing driving unit in the printer housing 2 via a plurality of gears (not shown) (hereinafter also referred to as a fixing unit driving motor). Connected to the output shaft.

  As a result, the fixing unit 15 can rotate the heat generating roller 56, for example, in the other rotation direction in accordance with the operation of the fixing unit driving motor when the print image is formed.

  The fixing unit housing 55 is provided with a pressure roller 57 at a lower end portion thereof so as to be rotatable about a rotation axis (hereinafter also referred to as a pressure roller rotation axis) parallel to the printer left-right direction. The upper part, which is a part of the surface of the pressure roller 57, is pressed against the lower part, which is the opposite part of the surface of the heating roller 56, with a predetermined pressure.

  The pressure roller 57 is formed by, for example, covering a pressure roller rotating shaft made of rod-shaped aluminum with a heat-resistant elastic layer made of silicone rubber, and covering the heat-resistant elastic layer with a PFA tube.

  In the fixing unit 15, for example, a gear is fixed to the pressure roller rotation shaft of the pressure roller 57, and the gear is engaged with a gear fixed to the heat roller rotation shaft 56 </ b> A.

  As a result, the fixing unit 15 presses the pressure roller 57 with the heating roller 56 while pressing the upper portion of the surface of the pressure roller 57 against the lower portion of the surface of the heating roller 56 at a predetermined pressure when forming the print image. It can be rotated in one reverse rotation direction in conjunction with the rotation in the other rotation direction.

  By the way, the heating roller 56 is provided with a heater 58 such as a halogen lamp in the heating roller rotating shaft 56A.

  The heater 58 is electrically connected to a predetermined voltage source (not shown) in the printer housing 2 (hereinafter also referred to as a heater voltage source), and a voltage is applied by the heater voltage source when a print image is formed. Is done.

  In the fixing unit housing 55, a thermistor 59 as a temperature detection unit that detects the surface temperature of the heat generating roller 56 is disposed in a non-contact manner in the vicinity of the surface of the heat generating roller 56 at a predetermined position on the upper end.

  The thermistor 59 is electrically connected to a predetermined temperature control unit (not shown) in the printer housing 2. The temperature controller maintains the surface temperature of the heat generating roller 56 at a predetermined temperature by appropriately turning on / off the heater voltage source based on the surface temperature detected by the thermistor 59 when the print image is formed.

  As a result, when the print image is formed, the fixing unit 15 takes in the recording paper 5 having the toner image transferred from the transfer unit 14 to the surface from the recording paper intake port into the recording paper path, and generates heat that is rotated in the opposite direction. It is sandwiched between the roller 56 and the pressure roller 57.

  The fixing unit 15 fixes the toner image on the surface of the recording paper 5 by applying pressure while heating the recording paper 5 between the heat generating roller 56 and the pressure roller 57 that are rotating in reverse to each other. Thereafter, the paper is delivered from the recording paper discharge port to a discharge conveyance path 29 located downstream in the conveyance direction.

  In this way, the fixing unit 15 fixes the toner images for four colors on the surface of the recording paper to form a print image, and the recording paper 5 on which the print image is formed is conveyed via the discharge conveyance path 29. Then, it can be discharged to the recording paper delivery unit 3AX.

(1-2) Configuration of Image Forming Unit Next, the configuration of the first to fourth image forming units 10 to 13 will be specifically described with reference to FIGS. 2 and 3.

  However, the first to fourth image forming units 10 to 13 are the same except that the color of the toner 64 used for developing the electrostatic latent image is different.

  Therefore, the configuration of the third image forming unit 12 that uses magenta (M) toner 64 for developing the electrostatic latent image, for example, among the first to fourth image forming units 10 to 13 will be described below. The description of the configuration of the first image forming unit 10, the second image forming unit 11, and the fourth image forming unit 13 will be omitted.

  As shown in FIGS. 2 and 3, the third image forming unit 12 includes a unit main body 65 serving as a developing unit and a toner cartridge 66 serving as a developer container.

  The unit main body 65 has, for example, a main body case 70 which is provided with a substantially L-shaped drum storage portion 70B at the tip of a substantially wedge-shaped roller storage portion 70A and is formed in a substantially J shape as a whole.

  The main body case 70 has a width from the left side surface 70D, which is one side surface, to the right side surface 70E, which is the other side surface (hereinafter also referred to as main body case width), when the recording paper 5 is conveyed. A predetermined length longer than the width of 5 (hereinafter also referred to as recording paper width) is selected.

  Incidentally, the horizontal width of the recording paper is the length of the side parallel to the direction orthogonal to the transport direction in the recording paper 5 (that is, the length of the side parallel to the printer horizontal direction in this embodiment).

  More specifically, the horizontal width of the recording paper is, for example, that the recording paper 5 of the A4 size in the color printer 1 is such that the longitudinal direction of the recording paper 5 is parallel to the transport direction and one short side is directed upstream in the transport direction. In the case of transporting in the transport posture with the other short side facing downstream in the transport direction, the length of the short side of the recording paper 5 is obtained.

  In the following description, in the main body case 70, the direction along the main body case width from the left side surface 70D to the right side surface 70E, and the opposite direction from the right side surface 70E to the left side surface 70D. Are collectively referred to as the main body width direction.

  The unit main body 65 is provided with a toner image forming section 71 as a developer image forming section in the drum storage section 70B of the main body case 70, and a toner supply section 72 as a developer supply section in the roller storage section 70A. Is provided.

  The toner image forming unit 71 includes the above-described photosensitive drum 37 and also includes a charging roller 75 as a charging unit that charges the surface of the photosensitive drum 37.

  The toner image forming unit 71 also includes a drum cleaning blade 76 as a residual developer removing unit that removes the toner 64 remaining on the surface of the photosensitive drum 37.

  The photosensitive drum 37 has, for example, a photoconductive layer having a predetermined thickness formed by sequentially laminating a charge generation layer and a charge transport layer on the outer peripheral surface of a conductive substrate such as drum-shaped aluminum having a relatively large diameter. It is formed as an organic photoreceptor provided.

  The photosensitive drum 37 is selected to have a length from the left end surface, which is one end surface, to the right end surface, which is the other end surface (hereinafter also referred to as drum length), which is longer than the recording paper width. .

  Further, the photosensitive drum 37 has a drum rotation shaft 37 </ b> A that coincides with the central axis of the photosensitive drum 37, and has a left end that is one end and a right end that is the other end from the left end and the right end of the photosensitive drum 37. Projected and fixed.

  Incidentally, the photosensitive drum 37 has a drum rotation shaft 37A attached to the left end portion and the right end portion of the photosensitive drum 37, for example, by E-rings 77 and 78, respectively. (Also referred to as a direction).

  The drum rotation shaft 37A is fixed so that, for example, a gear (not shown) (hereinafter also referred to as a photosensitive drum gear) that rotates from the right end surface of the photosensitive drum 37 rotates integrally with the drum rotation shaft 37A. It is installed.

  In addition, the drum housing portion 70B of the main body case 70 is provided with a head placement recess for placing the LED head 42 described above on the upper surface, which is the end surface on the base portion side of the roller housing portion 70A.

  In the drum housing portion 70B of the main body case 70, an exposure slit 70BX that is long in the main body width direction is formed at the bottom of the concave portion for head arrangement.

  Further, the drum storage portion 70B of the main body case 70 is arranged such that the toner image on the surface of the photosensitive drum 37 is applied to the surface of the recording paper 5 on the lower surface, which is the end surface of the roller storage portion 70A, facing the exposure slit 70BX. A substantially rectangular drum protruding hole 70BY that is long in the width direction of the main body for transferring is formed.

  As a result, the photosensitive drum 37 causes the upper portion, which is a part of the surface (that is, the surface of the photoconductive layer), to face the drum slit 70BX of the main body case 70 and the other portion of the surface. In a state where the lower part, which is a part, protrudes from the drum protrusion hole 70BY to the lower side of the main body case 70, it is provided to be rotatable about a drum rotation shaft 37A parallel to the main body width direction.

  That is, the photosensitive drum 37 can be rotated via the drum rotation shaft 37A in a state where the drum rotation shaft 37A (that is, the drum longitudinal direction) is parallel to the main body width direction by the drum storage portion 70B of the main body case 70. It is supported.

  When the third image forming unit 12 is attached to the color printer 1, the photosensitive drum gear is connected to the output shaft of the unit drive motor described above via a plurality of unit motor connecting gears.

  As a result, the toner image forming unit 71 can rotate the photosensitive drum 37 in the other rotation direction in accordance with the operation of the unit drive motor as described above when forming a print image.

  The toner image forming unit 71 rotates the photosensitive drum 37 in the other rotation direction in this way at the time of forming a print image, so that the exposure position (that is, exposure exposure) facing the exposure slit 70BX on the surface of the photosensitive drum 37 is performed. (Which is also the latent image formation position of the electrostatic latent image) can be sequentially changed.

  In addition, the toner image forming unit 71 rotates the photosensitive drum 37 in the other rotation direction at the time of forming a print image, thereby projecting the toner image from the drum projecting hole portion 70 BY on the surface of the photosensitive drum 37, so that the toner image is formed on the recording paper 5. The image transfer position for transferring to the surface can also be changed sequentially.

  The charging roller 75 is formed of, for example, semiconductive hydrin rubber so as to have a predetermined outer diameter that is smaller than the outer diameter of the photosensitive drum 37.

  The charging roller 75 is selected to have a predetermined length shorter than the drum length of the photosensitive drum 37 although the length from the left end surface, which is one end surface, to the right end surface, which is the other end surface, is longer than, for example, the horizontal width of the recording paper. Yes.

  The charging roller 75 has a conductive metal charging portion rotating shaft (hereinafter also referred to as a charging roller rotating shaft) 75A that is aligned with the central axis of the charging roller 75 and has a left end portion and an other end portion. The right end portion, which is a portion, is fixed so as to protrude from the left end surface and the right end surface of the charging roller 75.

  Further, the charging roller rotation shaft 75A is configured such that, for example, a gear (not shown) (hereinafter also referred to as a charging roller gear) rotates integrally with the charging roller rotation shaft 75A at the right end portion protruding from the right end surface of the charging roller 75. Is fixed.

  The charging roller 75 is disposed on the drum housing portion 70B of the main body case 70 with a part of the surface thereof with the longitudinal direction of the charging roller rotating shaft 75A (hereinafter also referred to as the charging roller longitudinal direction) parallel to the main body width direction. In a state where a certain front oblique lower portion is pressed against a rear oblique upper portion which is a part of the surface of the photosensitive drum 37, it is provided to be rotatable around the charging roller rotation shaft 75 </ b> A.

  In other words, the charging roller 75 has the charging roller rotating shaft 75A parallel to the main body width direction by the drum housing portion 70B of the main body case 70, and a part of the surface is on the surface of the photosensitive drum 37. In a state where it is pressed against a portion in front of the exposure position when rotating, it is rotatably supported via the charging roller rotating shaft 75A.

  The charging roller 75 meshes the charging roller gear with the photosensitive drum gear. As a result, when the photosensitive drum 37 rotates in the other rotation direction when the print image is formed, the charging roller 75 is transmitted through the photosensitive drum gear and the charging roller gear sequentially.

  Therefore, when the photosensitive drum 37 rotates in the other rotation direction, the charging roller 75 rotates in one rotation direction opposite to the rotation in conjunction with the rotation.

  When the third image forming unit 12 is mounted on the color printer 1, the charging roller 75 is electrically connected to a predetermined voltage source (hereinafter also referred to as a charging roller voltage source) in the printer housing 2. Connected.

  The toner image forming unit 71 applies a DC voltage having a predetermined voltage value to the charging roller 75 from the charging roller voltage source when the print image is formed.

  As a result, the toner image forming unit 71 can charge the surface of the photosensitive drum 37 via the charging roller 75 to a state where an electrostatic latent image can be formed prior to exposure when forming a print image.

  The drum cleaning blade 76 is formed in a substantially strip shape by, for example, urethane rubber. The drum cleaning blade 76 is selected to have a length substantially equal to the drum length, for example.

  The drum cleaning blade 76 has its longitudinal direction parallel to the main body width direction (that is, parallel to the drum longitudinal direction), and one edge thereof is positioned at a predetermined position on the rear inner wall of the drum storage portion 70B in the main body case 70. The support plate 79 is fixed.

  As a result, the drum cleaning blade 76 is brought into contact with the rear side portion, which is a part of the surface of the photosensitive drum 37, with the other edge portion being directed obliquely downward.

  That is, the drum cleaning blade 76 has the other edge at the image transfer position on the surface of the photosensitive drum 37 and the charging position by the charging roller 75 (that is, the position where the surface of the charging roller 75 contacts the surface of the photosensitive drum 37). It is made to contact the part between.

  The main body case 70 is provided with a residual toner storage portion 70BZ as a residual developer storage portion between the rear side of the rear edge of the drum protrusion hole portion 70BY and the other edge portion of the drum cleaning blade 76. Yes.

  As a result, when the photosensitive drum 37 rotates in the other rotation direction, the toner image forming unit 71 causes the drum cleaning blade 76 to transfer the toner 64 remaining on the surface without being transferred from the surface of the photosensitive drum 37 to the surface of the recording paper 5. Can be removed and dropped into the residual toner storage portion 70BZ.

  In this way, the toner image forming unit 71 removes the toner 64 remaining on the surface of the photosensitive drum 37 before charging the surface, so that the photosensitive drum 37 can be repeatedly used for toner image formation. .

  The toner supply unit 72 includes a developing roller 80 as a developer carrying member that supports magenta (M) toner 64 on the surface, and a supply roller 81 as a supply unit that supplies the toner 64 to the surface of the developing roller 80. doing.

  The toner supply unit 72 also includes a toner blade 82 as a developer layer thickness regulating unit that regulates the layer thickness of the toner 64 carried on the surface of the developing roller 80.

  Further, the toner supply unit 72 includes a pair of toner seals 83 and 84 as a developer carrying range regulating unit that regulates a carrying range of the toner 64 carried on the surface of the developing roller 80 (hereinafter also referred to as a toner carrying range). Also have.

  The developing roller 80 has a predetermined outer diameter smaller than the outer diameter of the photosensitive drum 37 by, for example, a semiconductive urethane rubber in which a conductive material such as carbon is added to a urethane rubber material and an electric resistance is appropriately adjusted. It is formed to have.

  The developing roller 80 is selected to have a length from the left end surface, which is one end surface, to the right end surface, which is the other end surface, for example, which is longer than the horizontal width of the recording paper but shorter than the drum length.

  Further, the developing roller 80 has, for example, a conductive metal developer carrier rotating shaft (hereinafter, also referred to as a developing roller rotating shaft) 80A made of stainless steel, which is aligned with the central axis of the developing roller 80 at one end. The left end portion and the right end portion as the other end portion are fixedly projected from the left end surface and the right end surface of the developing roller 80.

  Further, the developing roller rotating shaft 80A is configured such that, for example, a gear (not shown) (hereinafter also referred to as a developing roller gear) rotates integrally with the developing roller rotating shaft 80A at the right end protruding from the right end surface of the developing roller 80. Is fixed.

  The main body case 70 is provided with an overhanging portion on the inner side of the tip of the roller storage portion 70A, for example, and the inner space between the roller storage portion 70A and the drum storage portion 70B is a substantially rectangular boundary hole that is long in the main body width direction. It is connected via the part 70AX.

  Then, the developing roller 80 has a part of the surface of the roller housing portion 70A of the main body case 70 so that the longitudinal direction of the developing roller rotating shaft 80A (hereinafter also referred to as the developing roller longitudinal direction) is parallel to the width direction of the main body. A developing roller rotating shaft 80A in a state in which a rear oblique lower portion projects toward the drum housing portion 70B through the boundary hole 70AX and is pressed against a front oblique upper portion which is a part of the surface of the photosensitive drum 37. Is provided so as to be rotatable around the center.

  That is, the developing roller 80 has the developing roller rotating shaft 80A parallel to the width direction of the main body by the roller storage portion 70A of the main body case 70, and a part of the surface is between the exposure position and the image transfer position on the surface of the photosensitive drum 37. In a state of being pressed against this portion, it is rotatably supported via the developing roller rotating shaft 80A.

  When the third image forming unit 12 is mounted on the color printer 1, the developing roller 80 has the above-described unit driving via a plurality of gears (hereinafter also referred to as unit motor connecting gears) (not shown). Connected to the motor output shaft.

  Thus, the toner supply unit 72 rotates the developing roller 80 around the developing roller rotation shaft 80A, for example, in the direction opposite to the rotation direction of the photosensitive drum 37 in accordance with the operation of the unit drive motor when the print image is formed. Can be rotated in the direction.

  Further, when the third image forming unit 12 is mounted on the color printer 1, the developing roller 80 is electrically connected to a predetermined voltage source (hereinafter also referred to as a developing roller voltage source) in the printer housing 2. Connected.

  The toner supply unit 72 applies a DC voltage having a predetermined voltage value to the developing roller 80 from the developing roller voltage source when the print image is formed.

  Thus, the toner supply unit 72 can carry the toner 64 on the surface of the developing roller 80 during the formation of the print image, and develop the electrostatic latent image from the surface of the developing roller 80 to the surface of the photosensitive drum 37. The toner 64 can be transferred (attached) for use (that is, the toner 64 is transferred to the electrostatic latent image on the surface of the photosensitive drum 37).

  The developing roller 80 is rotated together with the photosensitive drum 37 by the same unit drive motor, but rotates at an outer peripheral speed different from that of the photosensitive drum 37 (for example, 1.26 compared to the outer peripheral speed of the photosensitive drum 37). The outer diameter, the gear ratio of the unit motor coupling gear, and the like are appropriately selected so that the outer peripheral speed rotates at a double outer peripheral speed.

  Therefore, when the developing roller 80 rotates in the opposite rotation direction together with the photosensitive drum 37, the toner supply unit 72 slides the surface of the developing roller 80 against the surface of the photosensitive drum 37, and enters the toner between the surfaces. 64 can be charged by friction for developing an electrostatic latent image.

  That is, when the developing roller 80 and the photosensitive drum 37 are rotated in opposite directions, the toner supply unit 72 is used for developing an electrostatic latent image in the toner 64 carried on the surface of the developing roller 80. Even when there is toner 64 that has not been charged to a specified potential, the toner 64 is charged for developing an electrostatic latent image by friction received from the surface of the photosensitive drum 37 and the surface of the developing roller 80. it can.

  Further, the toner supply unit 72 slides the surface of the developing roller 80 with respect to the surface of the photosensitive drum 37 when the developing roller 80 rotates in the opposite rotation direction together with the photosensitive drum 37 in this way. Control is performed so that an appropriate amount of toner 64 for developing an electrostatic latent image can be transferred from the surface of the photosensitive drum 37 to the surface of the photosensitive drum 37.

  The supply roller 81 is formed of, for example, a semiconductive foamed silicon sponge so as to have a predetermined outer diameter smaller than the outer diameter of the photosensitive drum 37.

  The length of the supply roller 81 from the left end surface, which is one end surface, to the right end surface, which is the other end surface, is selected to be a predetermined length that is substantially equal to, for example, the recording paper lateral width.

  Further, the supply roller 81 has a left end portion where a supply metal rotation shaft 81A (hereinafter also referred to as a supply roller rotation shaft) 81A made of stainless steel is aligned with the central axis of the supply roller 81 and is one end. The right end portion, which is the other end portion, is fixedly projected from the left end surface and the right end surface of the supply roller 81.

  Further, the supply roller rotation shaft 81A is configured such that, for example, a gear (not shown) (hereinafter also referred to as a supply roller gear) is integrally rotated with the supply roller rotation shaft 81A at the right end protruding from the right end surface of the supply roller 81. Is fixed.

  Then, the supply roller 81 has a part of the surface of the roller housing portion 70A of the main body case 70 so that the longitudinal direction of the supply roller rotation shaft 81A (hereinafter also referred to as the supply roller longitudinal direction) is parallel to the main body width direction. In a state where a certain oblique upper part is pressed against a front oblique lower part which is a part of the surface of the developing roller 80, it is provided to be rotatable around the supply roller rotating shaft 81A.

  That is, in the supply roller 81, the supply roller rotation shaft 81 </ b> A is parallel to the main body width direction by the drum storage portion 70 </ b> B of the main body case 70, and a part of the surface is on the surface of the developing roller 80. It can be rotated via its supply roller rotating shaft 81A in a state where it is pressed against the portion before the toner transfer position to be transferred (that is, the portion before the toner transfer position when the developing roller 80 rotates in one rotation direction). It is supported by.

  The supply roller 81 connects the supply roller gear to the developing roller gear through one intermediate gear (not shown).

  As a result, when the developing roller 80 rotates in one rotation direction when the print image is formed, the supply roller 81 is transmitted through the developing roller gear, the intermediate gear, and the supply roller gear sequentially.

  Therefore, when the developing roller 80 rotates in one rotation direction, the supply roller 81 rotates in the same one rotation direction in conjunction with the rotation.

  When the third image forming unit 12 is mounted on the color printer 1, the supply roller 81 is electrically connected to a predetermined voltage source (hereinafter also referred to as a supply roller voltage source) in the printer housing 2. Connected.

  The toner supply unit 72 applies a DC voltage having a predetermined voltage value to the supply roller 81 from a supply roller voltage source when a print image is formed.

  Thus, the toner supply unit 72 can charge the surface of the supply roller 81 so that the toner 64 can be supplied to the developing roller 80 when the print image is formed.

  The supply roller 81 rotates in the same rotation direction in conjunction with the rotation of the developing roller 80, but rotates at a different outer peripheral speed from the developing roller 80 (for example, compared with the outer peripheral speed of the developing roller 80). The outer diameter and the gear ratios of the developing roller gear, the intermediate gear, and the supply roller gear are appropriately selected so that the outer peripheral speed rotates at a peripheral speed of 0.66 times.

  As a result, even if the supply roller 81 rotates in the same rotation direction together with the developing roller 80, the toner supply unit 72 slides the surface of the developing roller 80 against the surface of the supply roller 81 and enters between the surfaces. The toner 64 can be charged for developing the electrostatic latent image by friction.

  The toner blade 82 is formed in a substantially strip shape from a metal such as stainless steel or phosphor bronze, or a rubber material such as silicone rubber. For example, the toner blade 82 is selected to have a predetermined length substantially equal to the recording paper width.

  The toner blade 82 has a longitudinal direction parallel to the width direction of the main body (that is, parallel to the longitudinal direction of the drum), and one edge portion is positioned at a predetermined position at the rear upper end of the roller storage portion 70A in the main body case 70. It is fixed to the provided support plate 85.

  As a result, the toner blade 82 is brought into pressure contact with the front oblique upper portion, which is a part of the surface of the developing roller 80, with the other edge portion facing the front oblique lower side.

  That is, the toner blade 82 has the other edge portion on the surface of the developing roller 80 between the toner transfer position and the toner supply position by the supply roller 81 (that is, the conveyance of the toner 64 on the surface of the developing roller 80). In the direction toward the downstream side of the toner supply position).

  Therefore, even when the toner supply unit 72 supplies toner 64 having a predetermined layer thickness or more to the surface of the developing roller 80 from the supply roller 81 when the print image is formed, the developing roller 80 rotates in one rotation direction. The toner blade 82 can remove excess toner 64 of a predetermined layer thickness or more from the surface.

  In this way, the toner supply unit 72 can regulate the layer thickness of the toner 64 carried on the surface of the developing roller 80 by the toner blade 82.

  At this time, the toner supply unit 72 causes the friction when the toner 64 carried in a thin layer on the surface of the developing roller 80 enters between the surface of the developing roller 80 and the other edge of the toner blade 82. Thus, the electrostatic latent image can be charged for development.

  That is, the toner supply unit 72 includes toner 64 that is not charged to a predetermined potential for developing an electrostatic latent image in the toner 64 that is carried in a thin layer on the surface of the developing roller 80. The toner 64 can be charged for developing the electrostatic latent image by friction received from the surface of the developing roller 80 and the other edge of the toner blade 82.

  The pair of toner seals 83 and 84 are formed in a predetermined shape according to the shape of the left inner surface and the right inner surface of the roller storage portion 70 </ b> A of the main body case 70 by, for example, a flat sponge.

  One toner seal 83 has a left end portion of the supply roller rotation shaft 81A inserted in a hole formed in the lower end portion of the one surface 83A, and the one surface 83A is in contact with the left end surface of the supply roller 81. The supply roller rotating shaft 81A is supported so as not to rotate (that is, not to receive the rotation of the supply roller rotating shaft 81A).

  As a result, one toner seal 83 is formed such that, for example, a predetermined range portion of the rear end surface is in the upper end portion of the left end portion of the surface of the developing roller 80 in a state where a predetermined position of one surface 83A is in contact with the left end of the toner blade 82. It is pressed to the range from the vicinity to the vicinity of the lower part through the front part.

  The other toner seal 84 is in a state in which the right end portion of the supply roller rotation shaft 81A is inserted into a hole formed in the lower end portion of the one surface 84A and the one surface 84A is in contact with the right end surface of the supply roller 81. Thus, the supply roller rotation shaft 81A is supported so as not to rotate (that is, not to receive the rotation of the supply roller rotation shaft 81A).

  As a result, the other toner seal 84 has a predetermined position on one surface 84A in contact with the right end of the toner blade 82, and a portion in a predetermined range on the rear end surface from the vicinity of the upper portion at the right end portion of the surface of the developing roller 80. It is pressed to the range up to the vicinity of the lower part through the front part.

  In this way, the pair of toner seals 83, 84 has a surface 83 </ b> A, 84 </ b> A facing each other in the roller storage portion 70 </ b> A of the main body case 70 that is substantially equal to the horizontal width of the recording paper (that is, the length of the supply roller 81 and the toner blade 82. The rear end surfaces of the developing rollers 80 are pressed against the surface of the developing roller 80 in a state of being substantially parallel to each other by a distance.

  In the following description, one toner seal 83 supported on the left end portion of the supply roller rotation shaft 81A is also referred to as a left toner seal 83, and the other toner seal supported on the right end portion of the supply roller rotation shaft 81A. 84 is also referred to as a right toner seal 84.

  In the following description, in the left toner seal 83 and the right toner seal 84, the surfaces 83A and 84A facing each other are also referred to as facing surfaces 83A and 84A, respectively.

  Thus, the toner supply unit 72 restricts the toner 64 from the supply roller 81 to the range from the facing surface 83A of the left toner seal 83 to the facing surface 84A of the right toner seal 84 during the formation of the print image. Can be supplied to the surface.

  Further, the toner supply unit 72 supplies the toner 64 supplied from the supply roller 81 to the surface of the developing roller 80 to the developing roller 80 from the facing surface 83A of the left toner seal 83 to the facing surface 84A of the right toner seal 84. Can be supported.

  In this way, the toner supply unit 72 can regulate the toner carrying range of the toner 64 on the surface of the developing roller 80 to a range that is substantially equal to the horizontal width of the recording paper by the left toner seal 83 and the right toner seal 84. .

  Incidentally, the width of the toner carrying range on the surface of the developing roller 80 is such that the rear surface edge of the facing surface 84 </ b> A of the right toner seal 84 from the position in contact with the rear edge of the facing surface 83 </ b> A of the left toner seal 83 on the surface of the developing roller 80. This is the length along the longitudinal direction of the developing roller up to the contact position.

  Incidentally, the third image forming unit 12 has the LED head 42 as described above. The LED head 42 has, for example, a head case having a predetermined length that is equal to or smaller than the recording paper width.

  In the LED head 42, a plurality of LED elements are arranged in the head case along the longitudinal direction of the LED head 42 (hereinafter also referred to as the head longitudinal direction).

  Further, the LED head 42 is arranged such that a lens array is disposed on the head case with its inner surface facing the light emitting surfaces of the plurality of LED elements and its outer surface exposed.

  In the main body case 70 of the unit main body 65, the LED head 42 is arranged in the head placement concave portion of the drum storage portion 70B described above, with the head longitudinal direction parallel to the main body width direction, and the lens array via the exposure slit 70BX. The photosensitive drum 37 is disposed to face the upper portion of the surface.

  Incidentally, the arrangement position of the LED head 42 is appropriately selected so that an electrostatic latent image can be formed on the upper portion of the surface of the photosensitive drum 37 by the irradiation light output from the light emitting surfaces of the plurality of LED elements, and the drum storage portion. 70B is disposed in the concave portion for head arrangement.

  On the other hand, in the toner cartridge 66, the width from the left side which is one side surface to the right side which is the other side surface (hereinafter also referred to as the cartridge width) is selected to be a predetermined width which is equal to or less than the main body case width. A rectangular parallelepiped cartridge case 87 is provided.

  Incidentally, in the following description, in the cartridge case 87, the direction along the cartridge width from the left side surface to the right side surface and the direction along the cartridge width from the right side surface to the left side surface opposite to this are collectively shown as the cartridge width. Also called direction.

  The cartridge case 87 is provided with a toner accommodating portion 88 as a developer accommodating portion, and the toner 64 is accommodated in the toner accommodating portion 88.

  The cartridge case 87 is provided with a stirring bar 89 that is long in the cartridge width direction in the toner accommodating portion 88 so as to be rotatable about an axis parallel to the cartridge width direction.

  Further, the cartridge case 87 is formed as a convex surface 87A having a lower end surface which is one end surface projecting in an arc shape, and is connected to the toner containing portion 88 at a predetermined position near the top of the convex surface 87A. A toner discharge port 87AY is formed.

  The cartridge case 87 is provided inside the convex surface 87A so that a shutter 90 for the toner discharge port 87AY can be opened and closed (that is, the toner discharge port 87AY can be opened and closed).

  Incidentally, the toner cartridge 66 is provided with an opening / closing operation lever (not shown) at a predetermined position of the cartridge case 87, and the shutter 90 can be opened / closed according to the operation of the opening / closing operation lever.

  The main body case 70 has an arc-shaped concave portion 70AY formed on the upper surface, which is the end surface of the base portion of the roller storage portion 70A, and a slit-like toner parallel to the main body width direction at a predetermined position on the bottom of the concave portion 70AY. An intake port 70AZ is formed.

  Thus, the toner cartridge 66 is attached to and detached from the upper surface of the roller housing portion 70A so that the cartridge width direction is parallel to the body width direction and the convex surface 87A of the cartridge case 87 is fitted to the concave portion 70AY on the upper surface. It is installed as possible.

  In the main body case 70, when the toner cartridge 66 is mounted, the toner intake port 70AZ is opposed to the toner discharge port 87AY of the cartridge case 87.

  With this configuration, the third image forming unit 12 has an electrostatic latent area on the surface of the photosensitive drum 37 that is opposed to the toner carrying range on the surface of the developing roller 80 (that is, a range that is substantially equal to the horizontal width of the recording paper). A toner image forming range for forming a toner image after forming an image (also an electrostatic latent image forming range for forming an electrostatic latent image) is formed.

  Incidentally, the width of the toner image forming area on the surface of the photosensitive drum 37 is opposed to the right edge of the toner carrying area from the position facing the left edge of the toner carrying area on the surface of the developing roller 80 on the surface of the photosensitive drum 37. This is the length along the longitudinal direction of the drum up to the position to be moved.

  Therefore, the third image forming unit 12 causes a part of the surface of the charging roller 75 (that is, a part along the longitudinal direction of the charging roller from the left end surface to the right end surface on the surface of the charging roller 75) on the surface of the photosensitive drum 37. It is pressed against a portion along the drum longitudinal direction from the left side to the right side of the toner image forming range (that is, including the toner image forming range).

  Further, in the third image forming unit 12, the LED head 42 with respect to the drum storage portion 70B of the main body case 70 is disposed on the surface of the photosensitive drum 37 along the drum longitudinal direction from the left edge to the right edge of the toner image forming range. It is arranged so that an electrostatic latent image can be formed in the toner image forming range by irradiating irradiation light.

  The third image forming unit 12 is mounted on the printer casing 2 such that the main body width direction (that is, the longitudinal direction of the drum) is parallel to the horizontal direction of the printer, and the roller storage portion 70A and the drum storage portion 70B are positioned forward and backward. It is attached so that it can be attached and detached in a posture.

  As a result, the third image forming unit 12 is in contact with the surface of the transfer belt 47 of the transfer unit 14 at the lower portion of the surface of the photosensitive drum 37 when the third image forming unit 12 is attached to the printer housing 2.

  Further, the third image forming unit 12 is mounted on the printer housing 2 in such a mounting posture, so that the toner cartridge 66 is positioned on the roller storage portion 70 </ b> A of the main body case 70.

  Accordingly, when the opening / closing operation lever of the toner cartridge 66 is operated and the shutter 90 is opened while the third image forming unit 12 is mounted on the printer housing 2, the third image forming unit 12 removes the toner 64 from the toner storage portion 88 and the toner discharge ports 87 </ b> AY and 87 </ b> AY. The toner can be supplied so as to drop into the roller accommodating portion 70A of the main body case 70 through the toner intake port 70AZ.

  As a result, the third image forming unit 12 can supply the toner 64 from the supply roller 81 to the developing roller 80 and form the printed image on the toner carrying range on the surface of the developing roller 80.

  The third image forming unit 12 can form an electrostatic latent image in the toner image forming area on the surface of the photosensitive drum 37 and at least a part of the toner 64 carried in the toner carrying area on the surface of the developing roller 80. The electrostatic latent image can be developed by transferring to the toner image forming range on the surface of the photosensitive drum 37.

  Then, the third image forming unit 12 transfers the toner image formed by developing the electrostatic latent image in the toner image forming range on the surface of the photosensitive drum 37 to the surface of the recording paper 5 conveyed by the transfer unit 14. be able to.

  Incidentally, in the third image forming unit 12, when the toner container 88 is empty in the toner cartridge 66, the toner cartridge 66 remains attached to the printer casing 2 while the unit main body 65 (that is, the main body case 70) is mounted. Can only be exchanged.

  In addition to such a configuration, the third image forming unit 12 (FIG. 3) supports the photosensitive drum 37 rotatably via the drum rotation shaft 37 </ b> A by the drum storage portion 70 </ b> B of the main body case 70, and the drum longitudinal direction thereof. For example, it is supported so as to be displaceable in the left direction, which is one direction along the longitudinal direction of the drum, while being parallel to the width direction of the main body.

  In the printer housing 2, a push-type solenoid 95 serving as a displacement drive unit is disposed, for example, at a position facing the right end surface of the drum rotation shaft 37 </ b> A when the third image forming unit 12 is mounted.

  The solenoid 95 is configured such that a plunger 95B can be pushed out by a predetermined length on the main body portion 95A, and the end surface of the plunger 95B is brought close to or in contact with the right end surface of the drum rotation shaft 37A of the third image forming unit 12. .

  As will be described later, the color printer 1 operates the solenoid 95 according to the frequency of use of the photosensitive drum 37 to push out the plunger 95B from the main body portion 95A for a predetermined length.

  Accordingly, the color printer 1 pushes the drum rotation shaft 37A in the third image forming unit 12 to the left side of the printer, which is parallel to the drum rotation shaft 37A, by the plunger 95B of the solenoid 95, and rotates the photosensitive drum 37. Along with the shaft 37A, it can be displaced by a predetermined distance in the left direction of the printer.

  Incidentally, in the third image forming unit 12, as described above, the length of the photosensitive drum 37 is appropriately selected to be a predetermined length longer than the horizontal width of the recording paper.

  In the third image forming unit 12, the arrangement position of the photosensitive drum 37 in the main body width direction in the drum housing portion 70 </ b> B of the main body case 70 is also appropriately selected.

  Therefore, even if the photosensitive drum 37 is displaced in the left direction of the printer, the third image forming unit 12 includes at least the developing roller from the left edge to the right edge of the toner carrying range on the surface of the developing roller 80. The state where the parts along the longitudinal direction are in contact with each other can be maintained.

  Therefore, when the photosensitive drum 37 is displaced in the left direction of the printer, the third image forming unit 12 sets the toner image forming range based on the position of the toner carrying range on the surface of the developing roller 80 on the surface of the photosensitive drum 37. The photosensitive drum 37 can be shifted to the right end face side without changing the width.

  In the third image forming unit 12, even if the photosensitive drum 37 is displaced in the left direction of the printer, the positional relationship among the components such as the developing roller 80, the charging roller 75, and the LED head 42 other than the photosensitive drum 37 is changed. Absent.

  Therefore, the third image forming unit 12 includes a toner image forming range whose position is changed on the surface of the photosensitive drum 37 even if the toner image forming range is shifted on the surface of the photosensitive drum 37 due to the displacement of the photosensitive drum 37. The surface of the charging roller 75 can be pressed against the surface.

  Further, even if the third image forming unit 12 shifts the toner image forming range on the surface of the photosensitive drum 37 due to the displacement of the photosensitive drum 37, the third image forming unit 12 displays the toner image forming range whose position has changed on the surface of the photosensitive drum 37 with the LED head 42. Can be opposed to each other.

  Further, in the third image forming unit 12, at least one of the photosensitive drum gear and the charging roller gear is formed relatively wide.

  Therefore, even if the photosensitive drum 37 is displaced in this manner, the third image forming unit 12 can maintain the state where the photosensitive drum gear is engaged with the charging roller gear.

  Further, in the color printer 1, at least one of the photosensitive drum gear and the unit motor connecting gear that is directly meshed with the photosensitive drum gear is also formed relatively wide.

  Therefore, the color printer 1 can maintain the state in which the photosensitive drum gear is connected to the output shaft of the unit driving motor via the plurality of unit motor connecting gears even when the photosensitive drum 37 is displaced in the third image forming unit 12. it can.

  Therefore, even if the photosensitive drum 37 is displaced in the third image forming unit 12, the color printer 1 can rotate the photosensitive drum 37 in the other rotation direction according to the operation of the unit driving motor, and in conjunction with this, the charging roller is linked. 75 can be rotated in one rotation direction.

  Therefore, if the color printer 1 displaces the photosensitive drum 37 in the third image forming unit 12 in this manner, the third image forming unit 12 operates while the photosensitive drum 37 is displaced during the subsequent print image formation. Let

  In this way, the color printer 1 displaces the photosensitive drum 37 in the third image forming unit 12 according to the frequency of use, and presses the surface of the developing roller 80 against the surface of the photosensitive drum 37 (that is, the contact position). Position) is shifted, and thereafter, the photosensitive drum 37 is used for forming a print image while being displaced.

  As a result, the color printer 1 can reduce film loss generated in the photoconductive layer of the photosensitive drum 37 in the third image forming unit 12.

  By the way, when the color printer 1 displaces the photosensitive drum 37 in the third image forming unit 12 via the solenoid 95, for example, charging or exposure of the surface of the photosensitive drum 37 with respect to the third image forming unit 12 or toner 64 The operation for forming a toner image such as supply (that is, printing) is stopped.

  However, in this case, the color printer 1 operates the unit drive motor to cause the photosensitive drum 37, the charging roller 75, the developing roller 80, and the supply roller 81 to idle in the third image forming unit 12 via the solenoid 95. Thus, the photosensitive drum 37 is displaced.

  That is, in the color printer 1, since the surface of the charging roller 75 and the surface of the developing roller 80 are pressed against the surface of the photosensitive drum 37 in the third image forming unit 12, the photosensitive drum 37 is not idly rotated. Is displaced.

  As a result, when the photosensitive drum 37 is displaced in the third image forming unit 12, the color printer 1 follows the longitudinal direction of the drum due to friction between the surface of the charging roller 75 and the surface of the developing roller 80 on the surface of the photosensitive drum 37. This prevents the formation of dents and scratches.

  The color printer 1 also has solenoids in the same manner on the mounting portions of the first image forming unit 10, the second image forming unit 11, and the fourth image forming unit 13 other than the third image forming unit 12 in the printer housing 2. It is arranged.

  Therefore, the color printer 1 also uses the photosensitive elements 35, 36, and 38 for the other first image forming unit 10, second image forming unit 11, and fourth image forming unit 13 via the solenoids according to the frequency of use. The drums 35, 36, and 38 can be displaced by a predetermined distance in the left direction of the printer together with the drum rotation shaft.

  Accordingly, the color printer 1 similarly presses the surface of the developing roller 80 against the surfaces of the photosensitive drums 35, 36, and 38 in the other first image forming unit 10, second image forming unit 11, and fourth image forming unit 13. By properly shifting the position (that is, the contact position), film loss that occurs in the photoconductive layers of the photosensitive drums 35, 36, and 38 can be reduced.

(1-3) Toner Configuration Next, black (K), yellow (Y), magenta (M), and cyan (C) used for developing electrostatic latent images in the first to fourth image forming units 10 to 13. The toner will be described.

  These color toners are basically formed in the same manner. That is, each color toner is formed by adding an external additive (hereinafter, also referred to as an external additive) such as an inorganic fine powder or an organic fine powder to toner base particles containing at least a binder resin.

  The binder resin has a role of maintaining the strength and glossiness of the printed image when the printed image is formed by being transferred and fixed as a toner image on the surface of the recording paper 5.

  The binder resin is not particularly limited, but is preferably a polyester resin, a styrene-acrylic resin, an epoxy resin, or a styrene-butadiene resin.

  In addition, a release agent, a colorant, and the like are added to the binder resin, but other additives such as a charge control agent, a conductivity modifier, a fluidity improver, or a cleaning property improver are appropriately added. Also good.

  Here, the release agent is for adjusting the peelability of the heat generation roller 56 with respect to the printed image when the printed image is formed on the surface of the recording paper 5 in the fixing unit 15 and the glossiness at the time of peeling. .

  Although it does not specifically limit as a mold release agent in binder resin, well-known waxes, such as paraffin wax and carnauba wax, are added.

  When a release agent is added to the binder resin, the content of the release agent with respect to the binder resin is 0.1 to 20 (parts by weight), preferably 0 with respect to 100 parts (parts by weight) of the binder resin. About 5 to 12 (parts by weight).

  Incidentally, either wax can be added alone to the binder resin as a release agent, but a plurality of types of waxes can be added in combination.

  The colorant determines the color of the toner and the color of the printed image. The binder resin is not particularly limited as a colorant, but dyes, pigments and the like conventionally used as colorants for black, yellow, magenta, and cyan toners are added singly or in combination. Yes.

  Incidentally, as a coloring agent, carbon black, iron oxide, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, pigment blue 15: 3, solvent blue 35 Quinacridone, carmine 6B, disazo yellow and the like.

  And when adding a coloring agent to binder resin, content of the coloring agent with respect to the binder resin is 2-25 (weight part) with respect to binder resin 100 (weight part), Preferably it is 2-15 (weight). Part) grade.

  Incidentally, the charge control agent is added to control the toner to a predetermined charge amount with respect to the binder resin, and a known one can be used.

  That is, examples of the charge control agent include an azo complex charge control agent, a salicylic acid complex charge control agent, a calixarene charge control agent, a quaternary ammonium salt charge control agent, and the like.

  When a charge control agent is added to the binder resin, the content of the charge control agent with respect to the binder resin is 0.05 to 15 (parts by weight), preferably 0 with respect to 100 (parts by weight) of the binder resin. About 1 to 10 (parts by weight).

  Any one of the charge control agents can be added to the binder resin alone, but a plurality of types of charge control agents can also be added in combination.

  The external additive is added to the toner base particles in order to improve the environmental stability, charging stability, developability, fluidity and storage stability of the toner, and known ones can be used. That is, as the external additive, silica, titania, alumina or the like can be used.

  When an external additive is added to the toner base particles, the content of the external additive with respect to the toner base particles is 0.01 to 10 (parts by weight), preferably 0 with respect to 100 (parts by weight) of the binder resin. About 0.05 to 8 (parts by weight).

  Any one of the external additives can be added to the toner base particles, but a plurality of types of external additives can also be added in combination.

   By the way, the magenta (M) toner 64 described above can be manufactured, for example, by the following manufacturing procedure.

  That is, in such a production procedure, a polyester resin as a binder resin (number average molecular weight Mn = 3700, glass transition temperature Tg = 62 [° C.], softening temperature T1 / 2 = 115 [° C.]) is first formed by a mother particle forming step. Is 100 (parts by weight), Bontron E84 (manufactured by Orient Chemical Co.) as a charge control agent is 0.5 (parts by weight), and carnauba wax (manufactured by Kato Yoko Co., carnauba wax No. 1) as a release agent. Powder) is 0.5 (parts by weight), quinacridone (Pigment Red 122) as a colorant is 5.0 (parts by weight), and these are mixed using a Henschel mixer.

  Next, in such a manufacturing procedure, the mixed binder resin, charge control agent, release agent and colorant are melt-kneaded by a twin screw extruder, and after cooling, roughened by a cutter mill having a screen having a diameter of 2 [mm]. The mixture is crushed and subsequently pulverized using a dispersion separator (manufactured by Nippon Pneumatic Industry Co., Ltd.) as a collision type pulverizer, and further classified using an air classifier to obtain an average particle size of 6.0 [μm]. Toner base particles are formed.

  Subsequently, in the production procedure, hydrophobic silica R972 (manufactured by Nippon Aerosil Co., Ltd., average particle size 16 [nm]) 3.0 (parts by weight) is added to the toner base particles 100 (parts by weight) by an external addition process. Then, the toner base particles 64 and the hydrophobic silica R972 are stirred for 3 minutes using a Henschel mixer, whereby the magenta (M) toner 64 can be produced.

  Incidentally, other black (K), yellow (Y), and cyan (C) toners can be manufactured by substantially the same manufacturing procedure as that for manufacturing the magenta (M) toner 64.

(1-4) Circuit Configuration of Color Printer 1 Next, the circuit configuration of the color printer 1 will be described with reference to FIG. FIG. 4 shows the first to fourth image forming units 10 to 13 which are the main parts of the present invention as part of the print image forming process (that is, the printing process) and the first to fourth image forming units of the transfer unit 14. A circuit configuration for executing toner image transfer processing for transferring a toner image onto the surface of the recording paper 5 using four transfer rollers 48 to 51 is shown.

  The color printer 1 has a control unit 100. The control unit 100 includes, for example, a microprocessor, a ROM (Read Only Memory) that stores various programs and various parameters in advance, a RAM (Random Access Memory) that is a work area of the microprocessor, an input / output port, a timer, a print It comprises a counting unit as an image carrier usage frequency detection unit for detecting the usage frequency of the photosensitive drums 35 to 38 for image formation.

  Then, the control unit 100 controls the entire color printer 1 based on print data and control commands given from the host device and executes a print image forming process (that is, a print process) including a toner image transfer process.

  Thereby, the control unit 100 separates and feeds the recording paper 5 from the recording paper cassette 6 one by one through the pair of recording paper feeding rollers 16 and 17 during the formation of the print image (that is, at the time of printing), and The fed recording paper 5 is conveyed to the downstream side in the conveying direction via the feeding conveyance path 22.

  Further, the control unit 100 conveys the recording paper 5 conveyed through the feeding conveyance path 22 to the transfer unit 14 further downstream in the conveyance direction while correcting the conveyance posture via the posture correction conveyance path 23. .

  For example, the control unit 100 detects the toner image in the first image forming unit 10 at a timing when the recording paper 5 conveyed via the posture correction conveyance path 23 reaches a predetermined first start position during the conveyance. The formation process is started.

  Further, the control unit 100 performs the second operation at the timing when the recording paper 5 being conveyed through the posture correction conveyance path 23 reaches the second start position on the downstream side in the conveyance direction from the first start position during the conveyance. The image forming unit 11 starts a toner image forming process.

  Further, the control unit 100 performs the third operation at the timing when the recording paper 5 being conveyed through the posture correction conveyance path 23 reaches the third start position downstream in the conveyance direction from the second start position during the conveyance. The image forming unit 12 starts a toner image forming process.

  Further, the control unit 100 performs the fourth operation at the timing when the recording paper 5 being conveyed through the posture correction conveyance path 23 reaches the fourth start position downstream in the conveyance direction from the third start position during the conveyance. The image forming unit 13 starts the toner image forming process.

  Here, in the first to fourth image forming units 10 to 13, the control unit 100 is charged to control the voltage applied to the charging roller 75 in order to charge the surfaces of the photosensitive drums 35 to 38 by the charging roller 75. A roller power control unit 101 is connected.

  Actually, the charging roller power controller 101 includes four charging voltage controllers (not shown) for individually controlling the voltages applied to the charging roller 75 for each of the first to fourth image forming units 10 to 13 (that is, the first charging voltage controller). Each of the first to fourth image forming units 10 to 13.

  Further, the control unit 100 controls the LED heads 40 to 43 of the first to fourth image forming units 10 to 13 based on the print data to output the irradiation light for forming the electrostatic latent image. The unit 102 is also connected.

  Actually, the LED head control unit 102 controls four LED heads 40 to 43 (not shown) for individually controlling the LED heads 40 to 43 based on the corresponding color data included in the print data for each of the first to fourth image forming units 10 to 13. A head controller (that is, a head controller for each of the first to fourth image forming units 10 to 13) is provided.

  Further, the control unit 100 includes the developing roller 80 in order to develop the electrostatic latent images on the surfaces of the photosensitive drums 35 to 38 by causing the developing roller 80 to carry toner in the first to fourth image forming units 10 to 13. A developing roller power control unit 103 for controlling the voltage applied to is also connected.

  Actually, the developing roller power controller 103 includes four developing voltage controllers (not shown) for individually controlling the voltages applied to the developing roller 80 for the first to fourth image forming units 10 to 13 (that is, the first image forming units 10 to 13). Development voltage control unit for each of the first to fourth image forming units 10 to 13.

  Further, the controller 100 supplies a supply roller power source for controlling the voltage applied to the supply roller 81 in order to supply the toner to the developing roller 80 by the supply roller 81 in the first to fourth image forming units 10 to 13. A control unit 104 is also connected.

  Actually, the supply roller power control unit 104 includes four supply voltage control units (not shown) for individually controlling the voltages applied to the supply roller 81 for each of the first to fourth image forming units 10 to 13 (that is, the first supply voltage control unit 104). Supply voltage control unit for each of the first to fourth image forming units 10 to 13.

  Further, the controller 100 transfers the toner images on the surfaces of the four photosensitive drums 35 to 38 to the surface of the recording paper 5 by the first to fourth transfer rollers 48 to 51 in the transfer unit 14. A transfer roller power control unit 105 for controlling the voltage applied to the first to fourth transfer rollers 48 to 51 is also connected.

  Actually, the transfer roller power control unit 105 individually controls the voltage applied to the first to fourth transfer rollers 48 to 51 for each of the first to fourth transfer rollers 48 to 51 of the transfer unit 14. There are four transfer voltage control units (that is, transfer voltage control units for the first to fourth transfer rollers 48 to 51).

  Further, a motor control unit 111 for controlling a unit drive motor 110 provided for each of the first to fourth image forming units 10 to 13 is also connected to the control unit 100.

  Actually, the motor control unit 111 individually controls the unit drive motor 110 for each of the first to fourth image forming units 10 to 13 to control the rotation of the photosensitive drums 35 to 38, the developing roller 80, etc. (not shown). Four rotation control units (that is, rotation control units for the first to fourth image forming units 10 to 13) are provided.

  With this configuration, when the first image forming unit 10 starts toner image forming processing, the control unit 100 controls the rotation control unit for the first image forming unit 10 in the motor control unit 111.

  Accordingly, the rotation control unit for the first image forming unit 10 in the motor control unit 111 operates the unit drive motor 110 for the first image forming unit 10 to rotate the photosensitive drum 35 in the other direction. Rotate in the direction at a constant peripheral speed.

  In addition, the rotation control unit for the first image forming unit 10 causes the charging roller 75 in the first image forming unit 10 to be part of the surface of the charging roller 75 in conjunction with the rotation of the photosensitive drum 35 in the other rotation direction. Is rotated at a constant outer peripheral speed in one rotation direction while being pressed against a part of the surface of the photosensitive drum 35.

  Further, the rotation control unit for the first image forming unit 10 slides the developing roller 80 in the first image forming unit 10 with respect to the surface of the photosensitive drum 35 by the operation of the unit drive motor 110. Rotate in one rotation direction.

  Further, the rotation control unit for the first image forming unit 10 causes the supply roller 81 in the first image forming unit 10 to move a part of the surface of the supply roller 81 in conjunction with the rotation of the developing roller 80. Rotate in one rotation direction while sliding against the surface.

  Further, at this time, the control unit 100 operates the transfer unit driving motor to transfer the transfer belt 47 through the drive roller 45 and the tension roller 46 in the transfer unit 14, and the surface of the upper flat portion of the photosensitive drum 35 to 38. Rotate in one rotation direction while pressing against a part of the surface.

  In this state, the charging voltage control unit for the first image forming unit 10 in the charging roller power source control unit 101 controls the charging roller 75 of the first image forming unit 10 by the charging roller voltage source 106 under the control of the control unit 100. A DC voltage having a predetermined voltage value (for example, about −1000 [V]) is applied.

  As a result, the charging voltage control unit for the first image forming unit 10 applies a predetermined potential (for example, −500) to the surface of the photosensitive drum 35 via the charging roller 75 in the image forming unit 10 for forming an electrostatic latent image. [V]) is uniformly charged.

  In this case, the head control unit for the first image forming unit 10 in the LED head control unit 102 is controlled by the control unit 100 at this time based on the corresponding color data included in the print data. The LED head 40 is controlled to cause the LED head 40 to output irradiation light corresponding to the color data.

  Therefore, the head control unit for the first image forming unit 10 irradiates the uniformly charged surface of the photosensitive drum 35 with the irradiation light output to the LED head 40 in the first image forming unit 10.

  As a result, the head control unit for the first image forming unit 10 attenuates the potential of the irradiated portion of the irradiated light on the surface of the photosensitive drum 35 to a predetermined potential (for example, about −50 [V]), and performs the photosensitive operation. An electrostatic latent image is formed on the surface of the drum 35 where the irradiated light is irradiated.

  In the supply roller power control unit 104, a supply voltage control unit for the first image forming unit 10 is controlled by a supply roller voltage source 107 to supply a predetermined roller to the supply roller 81 of the first image forming unit 10 under the control of the control unit 100. A DC voltage having a voltage value (for example, about −350 [V]) is applied.

  As a result, the supply voltage controller for the first image forming unit 10 supplies the toner to the developing roller 80 so that the toner is transported while being charged by the supply roller 81 in the first image forming unit 10.

  Further, a developing voltage control unit for the first image forming unit 10 in the developing roller power source control unit 103 applies a predetermined voltage to the developing roller 80 of the first image forming unit 10 by the developing roller voltage source 108 under the control of the control unit 100. A DC voltage having a voltage value (for example, about −250 [V]) is applied.

  Therefore, the developing voltage control unit for the first image forming unit 10 causes the toner supplied by the supply roller 81 to be carried on the surface of the developing roller 80 in the first image forming unit 10 so as to be adsorbed.

  Incidentally, at this time, in the first image forming unit 10, the layer thickness of the toner carried on the surface of the developing roller 80 is restricted by the toner blade 82 as described above, and the left toner seal 83 and the right toner seal 84 are used for this. The toner carrying range of the toner carried on the surface of the developing roller 80 is regulated.

  In the first image forming unit 10, the toner carried on the surface of the developing roller 80 at this time has a predetermined potential (for example, the friction received from the surface of the developing roller 80, the surface of the supply roller 81, or the toner blade 82). , About −60 [V]).

  As a result, the control unit 100 reversely develops the electrostatic latent image formed on the surface of the photosensitive drum 35 in the first image forming unit 10 with the toner carried on the surface of the developing roller 80.

  That is, in the first image forming unit 10, a bias voltage is applied between the surface of the photosensitive drum 35 and the surface of the developing roller 80 by the charging roller voltage source 106 and the developing roller voltage source 108.

  For this reason, in the first image forming unit 10, electric lines of force are generated between the surface of the photosensitive drum 35 and the surface of the developing roller 80 according to the potential of the electrostatic latent image formed on the surface of the photosensitive drum 35.

  Therefore, in the first image forming unit 10, the charged toner carried on the surface of the developing roller 80 adheres so as to be transferred to the electrostatic latent image on the surface of the photosensitive drum 35 by electrostatic force.

  Accordingly, the control unit 100 can develop the electrostatic latent image on the surface of the photosensitive drum 35 with the toner in the first image forming unit 10 and form a toner image on the surface of the photosensitive drum 35.

  At this time, the transfer voltage control unit for the first transfer roller 48 in the transfer roller power supply control unit 105 controls the first transfer roller 48 with a predetermined voltage value (by the transfer roller voltage source 109 under the control of the control unit 100. For example, a DC voltage of about +3000 [V] is applied.

  Thus, the control unit 100 continues to electrostatically attract and convey the recording paper 5 conveyed via the posture correction conveyance path 23 by the transfer belt 47 of the transfer unit 14, and the recording paper 5 is conveyed to the first image forming unit 10. When passing between the surface of the photosensitive drum 35 and the first transfer roller 48, the surface of the photosensitive drum 35 is caused by the action of Coulomb force generated by the application of a DC voltage to the first transfer roller 48. The toner image formed on the recording sheet 5 is transferred to the surface of the recording paper 5.

  In this way, the control unit 100 transports the recording paper 5 via the transfer belt 47 of the transfer unit 14 and forms toner with black (K) toner on the surface of the photosensitive drum 35 in the first image forming unit 10. The image can be transferred to the surface of the recording paper 5.

  At this time, the control unit 100 responds to the start of the toner image forming process in the second image forming unit 11 with a rotation control unit, a charging voltage control unit, a head control unit, and a supply for the second image forming unit 11. The voltage control unit and the development voltage control unit are operated in the same manner as described above.

  The control unit 100 also includes a rotation control unit, a charging voltage control unit, a head control unit, and a supply voltage control unit for the third image forming unit 12 in response to the start of the toner image forming process in the third image forming unit 12. The developing voltage controller is also operated in the same manner as described above.

  Furthermore, the control unit 100 responds to the start of the toner image forming process in the fourth image forming unit 13 with a rotation control unit, a charging voltage control unit, a head control unit, and a supply voltage control unit for the fourth image forming unit 13. The developing voltage controller is also operated in the same manner as described above.

  Accordingly, the controller 100 also applies toner to the surfaces of the photosensitive drums 36, 37, and 38 in the second image forming unit 11, the third image forming unit 12, and the fourth image forming unit 11 as in the second image forming unit 11. An image can be formed.

  The control unit 100 sequentially operates the transfer voltage control units for the second to fourth transfer rollers 49 to 51 in the same manner as described above in accordance with the operations of the second to fourth image forming units 11 to 13.

  Therefore, when the recording paper 5 being conveyed via the transfer belt 47 of the transfer unit 14 passes between the surface of the photosensitive drum 36 of the second image forming unit 11 and the second transfer roller 49, the control unit 100 The toner image formed on the surface of the photosensitive drum 36 is transferred to the surface of the recording paper 5.

  When the recording paper 5 being conveyed via the transfer belt 47 of the transfer unit 14 passes between the surface of the photosensitive drum 37 of the third image forming unit 12 and the third transfer roller 50, the control unit 100 The toner image formed on the surface of the photosensitive drum 37 is transferred to the surface of the recording paper 5.

  Further, when the recording paper 5 being conveyed via the transfer belt 47 of the transfer unit 14 passes between the surface of the photosensitive drum 38 of the fourth image forming unit 13 and the fourth transfer roller 51, the control unit 100 The toner image formed on the surface of the photosensitive drum 38 is transferred to the surface of the recording paper 5.

  In this way, the control unit 100 conveys the recording paper 5 via the transfer belt 47 of the transfer unit 14, and in addition to the toner image formed with the black (K) toner on the surface of the recording paper 5, A toner image formed with yellow (Y) toner, a toner image formed with magenta (M) toner, and a toner image formed with cyan (C) toner can also be transferred in order.

  Then, when the transfer unit 14 transfers the four color toner images onto the surface of the recording paper 5 in this way, the control unit 100 delivers the recording paper 5 to the fixing unit 15 at the subsequent stage.

  At this time, the control unit 100 operates the fixing unit driving motor to rotate the heat generating roller 56 in the other rotation direction, and in conjunction with the rotation of the heat generating roller 56, the control roller 100 moves the pressure roller 57 over a part of its surface. The heat roller 56 is rotated in one rotation direction while being pressed against a part of the surface of the heat roller 56 with a predetermined pressure.

  In addition, the temperature control unit applies a voltage to the heater 58 in the heat roller 56 by a heater voltage source under the control of the control unit 100 to heat the heater 58.

  The temperature control unit detects the surface temperature of the heat generating roller 56 via the thermistor 59 and controls the heater voltage source according to the detection result, thereby maintaining the surface temperature of the heat generating roller 56 at a predetermined temperature. Yes.

  Therefore, the control unit 100 heats and presses the recording paper 5 delivered from the transfer unit 14 to the fixing unit 15 while being sandwiched between the heating roller 56 and the pressure roller 57 that are rotating in the reverse direction in the fixing unit 15. Thus, the toner image is once fixed on the surface of the recording paper 5 so as to be melted.

  In this way, the control unit 100 can form a print image on the surface of the recording paper in the fixing unit 15 based on the four color toner images.

  Then, the control unit 100 continuously conveys the recording paper 5 on which the print image has been formed by the fixing unit 15 through the subsequent discharge conveyance path 29 and discharges the recording paper 5 from the recording paper discharge port to the recording paper delivery unit 3AX.

  In this way, the control unit 100 can form a print image on the surface of the recording paper 5 (that is, print it), and pass the recording paper 5 from the recording paper delivery unit 3AX to the user.

  In addition, the control unit 100 controls the solenoid 95 provided for each of the first to fourth image forming units 10 to 13 as an image carrier displacement control unit for displacing the photosensitive drums 35 to 38. A drum displacement control unit 112 is connected.

  Actually, the drum displacement controller 112 includes four solenoid controllers (not shown) for individually controlling the solenoids 95 for the first to fourth image forming units 10 to 13 (that is, the first to fourth image forming units). 10 to 13 solenoid control units).

  With this configuration, the control unit 100 detects the usage frequency of the photosensitive drums 35 to 38 via the counting unit.

  That is, every time the control unit 100 forms (prints) a print image on the surface of the recording paper 5, the control unit 100 displays the print image representing the number of times the photosensitive drums 35 to 38 have been used to form the print image by the counting unit. The number of recording sheets 5 formed (hereinafter also referred to as the number of printed sheets) is counted.

  Then, when the number of printed sheets counted by the counting unit reaches a predetermined number (for example, about 20000), the control unit 100 causes the drum displacement control unit 112 to perform the first to fourth image forming units 10 to 13. Each solenoid control unit is controlled.

  At this time, the solenoid control unit for the first image forming unit 10 in the drum displacement control unit 112 operates the solenoid 95 for the first image forming unit 10 under the control of the control unit 100, and The plunger 95B is pushed out from the main body 95A by a predetermined extrusion length (for example, about 20 [mm]).

  Therefore, the solenoid control unit for the first image forming unit 10 pushes the drum rotation shaft of the photosensitive drum 35 of the first image forming unit 10 leftward by the plunger 95B of the corresponding solenoid 95.

  As a result, the solenoid control unit for the first image forming unit 10 moves the position of the photosensitive drum 35 in the first image forming unit 10 integrally with the drum rotation shaft to the left of the printer along the drum longitudinal direction. It is displaced by a predetermined displacement amount (for example, about 20 [mm]) according to the extrusion length.

  That is, the solenoid control unit for the first image forming unit 10 determines the position of the photosensitive drum 35 in the first image forming unit 10, a part of the surface of the photosensitive drum 35, a part of the surface of the charging roller 75, and the development. While being pressed against a part of the surface of the roller 80, it is displaced by a predetermined displacement amount in the left direction of the printer along the drum longitudinal direction.

  In the drum displacement control unit 112, the solenoid control units for the second to fourth image forming units 11 to 13 also correspond to the second to fourth image forming units 11 to 11 under the control of the control unit 100, respectively. The solenoid 95 for 13 is operated, and the plunger 95B is pushed out from the main body 95A of the solenoid 95 by the same length.

  Therefore, the solenoid control unit for the second to fourth image forming units 11 to 13 also uses the plunger 95B of the corresponding solenoid 95 to set the drum rotation shafts of the photosensitive drums 36 to 38 of the second to fourth image forming units 11 to 13 to the printer. Push left.

  As a result, the solenoid control unit for the second to fourth image forming units 11 to 13 positions the photosensitive drums 36 to 38 integrally with the drum rotation shaft in the second to fourth image forming units 11 to 13 in the drum longitudinal direction. The printer is displaced by the same amount of displacement along the direction to the left of the printer.

  That is, the solenoid control unit for the second to fourth image forming units 11 to 13 also positions the photosensitive drums 36 to 38 in the second to fourth image forming units 11 to 13 on the surface of the photosensitive drums 36 to 38. A part of the surface of the charging roller 75 and a part of the surface of the developing roller 80 are pressed to the left of the printer along the drum longitudinal direction by a predetermined displacement amount.

  In this way, the control unit 100 displaces the photosensitive drums 35 to 38 simultaneously in the left direction of the printer in the first to fourth image forming units 10 to 13.

  Accordingly, the control unit 100 sets the toner image forming range on the surface of the photosensitive drums 35 to 38 facing the toner carrying range on the surface of the developing roller 80 in the first to fourth image forming units 10 to 13 to the photosensitive drums 35 to 38. Shift to the right on the surface.

  When the control unit 100 displaces the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 13 in this manner, the control unit 100 then disposes of the recording paper 5 with the photosensitive drums 35 to 38 being displaced. Used to form a printed image on the surface.

  Therefore, the control unit 100 repeatedly forms the print image on the surface of the recording paper 5 by pressing the surface of the developing roller 80 against the surface of the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 13. Although the surface of each of the photosensitive drums 35 to 38 is worn every time, the film loss generated in the photoconductive layer of the photosensitive drums 35 to 38 can be reduced.

(1-5) Continuous Paper Passing Printing Test Next, the first and second continuous paper passing printing tests for continuously printing test print patterns on a plurality of recording papers 5 performed to confirm the effect of the present invention will be described. .

  The first and second continuous paper-pass printing tests were performed using the third image forming unit 12 that uses magenta (M) toner 64 for forming a toner image in the color printer 1 described above.

  First, in the first continuous paper-pass printing test, a new photosensitive drum 37 is prepared prior to the start of the test, and an electric current is detected in the photosensitive drum 37 by using an overcurrent measuring device (Kett Science Laboratory, LH-330J). The film thickness of the photoconductive layer was measured based on the outer diameter of the substrate. As a result, the film thickness of the photoconductive layer of the photosensitive drum 37 was 21.0 [μm].

  In the first continuous paper-pass printing test, the initial outer diameter of the photosensitive drum 37 was measured using a laser measuring machine (Apollo Seiko, RM202), and then the photosensitive drum 37 was assembled to the third image forming unit 12.

  Further, in the first continuous paper-pass printing test, 130 [g] of magenta (M) toner was put in the toner accommodating portion 88 of the toner cartridge 66 in the third image forming unit 12.

In the first continuous paper-pass printing test, A4 size standard paper (for example, OKI excellent white paper, basis weight = 80 [g / m ² ], ISO whiteness is used as the recording paper 5 for printing the test print pattern. = 98 [%], short side 210 [mm] × long side 297 [mm]).

  In addition, in the first continuous paper-pass printing test, as a printing condition for the color printer 1, the recording paper 5 that is the A4 size standard paper is transported in the transport orientation in which the A4 vertical direction is parallel to the transport direction (that is, in the transport direction). It is assumed that the recording paper 5 is transported in a transport posture in which one short side of the recording paper 5 faces upstream and the other short side of the recording paper 5 faces downstream in the transport direction, and the paper passing speed is 275 [mm / sec]. Set.

  In the first continuous paper-pass printing test, the printing condition for the color printer 1 is the interval between continuous papers (that is, the recording paper 5 before the plurality of recording papers 5 are continuously conveyed for printing). The distance between the short side on the rear side and the short side on the front side of the next recording paper 5) was set to 50 [mm].

  Furthermore, in the first continuous paper-pass printing test, the printing rate for the color printer 1 is set as the printing duty of the test printing pattern (printing rate when the entire printing area that can be printed on the surface of the recording paper 5 is 100%). ) Was set to 100 [%].

  In the first continuous paper printing test, the color printer 1 performed continuous paper printing of a test print pattern on the 40000 recording papers 5 while appropriately supplementing magenta (M) toner.

  However, in the first continuous paper-pass printing test, for example, the print duty is set to 40 [%] (printing on the surface of the recording paper 5 for every 1000 recording papers 5 out of 40000 recording papers 5 by the color printer 1. A test print pattern was printed with a halftone that was uniform over the entire surface at a printing rate of 100 [%], and the print quality of the print image of the test print pattern was confirmed.

  In the first continuous paper-pass printing test, when the test print pattern has been printed on the surface of the 20000th recording paper 5 by the color printer 1, printing is temporarily stopped and the operation of the LED head 42 is stopped. The solenoid 95 was operated while the photosensitive drum 37 and the developing roller 80 were idled in the third image forming unit 12 in a state where no paper was passed.

  As a result, as shown in FIG. 5, in the first continuous sheet-pass printing test, the photosensitive drum 37 in the third image forming unit 12 is displaced together with the drum rotation shaft 37A by a displacement amount of 20 [mm] in the left direction of the printer. The contact position of the surface of the photosensitive drum 37 with respect to the surface of the roller 80 was shifted along the drum longitudinal direction.

  In the first continuous paper-pass printing test, the remaining 20000 sheets of recording paper 5 by the color printer 1 are left displaced in the third image forming unit 12 (that is, in the third image forming unit 12). The test print pattern was continuously printed by operating the photosensitive drum 37 (with the position after the displacement).

  In this way, in the first continuous paper-pass printing test, the color printer 1 printed the test print pattern with the print duty set to 40 [%] on the 40000th recording paper 5, but the 40000th recording was performed. Even in the print image of the test print pattern on the paper 5, there was no print stain due to dot crushing or the like, and the print quality was good.

  In the first continuous paper-pass printing test, the photosensitive drum 37 is removed from the third image forming unit 12 at the time point when the printing of the test print pattern on the 40000 sheets of recording paper 5 by the color printer 1 is completed. Similarly, the outer diameter of the photosensitive drum 37 (that is, the outer diameter after completion of the test) was measured using a laser measuring machine (Apollo Seiko, RM202).

  Further, in the first continuous paper-pass printing test, the amount of film reduction in the photoconductive layer of the photosensitive drum 37 was detected based on the initial outer diameter of the photosensitive drum 37 and the outer diameter after the test.

  Here, in FIG. 6, the horizontal axis represents the length in the drum longitudinal direction of the photosensitive drum 37 (that is, the length of the photoconductive layer in the drum longitudinal direction), and the vertical axis represents the film reduction in the photoconductive layer of the photosensitive drum 37. The results of detecting the amount of film reduction along the longitudinal direction of the drum in the photoconductive layer of the photosensitive drum 37 after the first continuous paper-pass printing test is shown.

  The photosensitive drum 37 after the completion of the first continuous paper-pass printing test is apparent from the positional relationship between the developing roller 80 and the photosensitive drum 37 shown in FIG. 5 and the first film reduction amount detection result curve MD1 shown in FIG. In addition, the central portion of the surface had relatively little wear.

  In addition, the photosensitive drum 37 after the first continuous sheet-pass printing test is completed on the surface, the location PL1 before displacement and the location PL2 after displacement corresponding to the facing surface 83A of the left toner seal 83, and the facing surface 84A of the right toner seal 84. The wear of the pre-displacement location PR1 and the post-displacement location PR2 corresponding to is larger than that of the central portion.

  That is, with respect to the photosensitive drum 37 after the first continuous paper-pass printing test, although the photoconductive layer has an uneven film thickness reduction, the displacement of the photosensitive drum 37 causes a significant increase in the film thickness of the photoconductive layer. Was not seen.

  The amount of film loss of the photoconductive layer on the photosensitive drum 37 after the end of the first continuous paper-pass printing test is 12.5 [μm, which is the largest at the position PR1 before displacement corresponding to the facing surface 84A of the right toner seal 84 on the surface. The residual film thickness of the photoconductive layer at the location PR1 was 8.5 [μm].

  Next, in the second continuous paper passing printing test, a new photosensitive drum 37 is prepared again for comparison with the first continuous paper passing printing test, and the photosensitive drum 37 is coated with the film of the photoconductive layer in the same manner as described above. The thickness was measured and the initial outer diameter was measured, and then assembled to the third image forming unit 12.

  In the second continuous paper printing test, the color printer 1 performed continuous paper printing of a test print pattern on 40000 recording papers 5 in the same manner as described above.

  By the way, in the second continuous paper-pass printing test, when the color printer 1 has finished printing the test print pattern on the surface of the 20000th recording paper 5, the printing is temporarily stopped as in the first continuous paper-pass printing test. I let you.

  However, at this time, in the second continuous paper passing print test, when the operation of the LED head 42 is stopped and no paper is passed, the printing of the 20,000th recording paper 5 is completed in the first continuous paper passing print test. The photosensitive drum 37 was not displaced at all by merely rotating the photosensitive drum 37 and the developing roller 80 in the third image forming unit 12 by the same number of rotations as the number of rotations of the photosensitive drum 37 and the developing roller 80 being idle. .

  That is, in the second continuous paper-pass printing test, the use conditions of the photosensitive drum 37 are matched as much as possible in the case of the first continuous paper-pass printing test. A test print pattern was continuously printed on 20000 recording papers 5.

  In the second continuous paper-pass printing test, the color printer 1 confirmed the print image of the test print pattern on the 40000th recording paper 5 (that is, the test print pattern with a print duty of 40%). The dots were crushed and darkened on the left end side and the right end side of the recording paper 5, printing stains were observed, and the print quality was deteriorated.

  In the second continuous paper-pass printing test, the photosensitive drum 37 is removed from the third image forming unit 12 when printing of the test print pattern on the 40,000 recording sheets 5 by the color printer 1 is completed. Similarly, the outer diameter of the photosensitive drum 37 (that is, the outer diameter after completion of the test) was measured.

  As a result, as is apparent from the second film reduction amount detection result curve MD2 of the photosensitive drum 37 after the end of the second continuous paper-passing printing test, the central portion of the surface is relatively small in wear.

  However, the photosensitive drum 37 after the end of the second continuous paper-pass printing test has wear on the surface at a location PL3 corresponding to the facing surface 83A of the left toner seal 83 and a location PR3 corresponding to the facing surface 84A of the right toner seal 84. It was significantly larger than the part.

  That is, the photosensitive drum 37 after completion of the second continuous sheet-pass printing test is filmed at a location PL3 corresponding to the facing surface 83A of the left toner seal 83 and a location PR3 corresponding to the facing surface 84A of the right toner seal 84 in the photoconductive layer. The amount of reduction was significantly increased.

  Then, the amount of film loss of the photoconductive layer on the photosensitive drum 37 after the end of the second continuous paper-pass printing test is the largest value of 15.1 [μm] at the position PR3 corresponding to the facing surface 84A of the right toner seal 84 on the surface. Thus, the remaining film thickness of the photoconductive layer at the location PR3 was 5.9 [μm].

  Here, according to the first and second continuous paper-pass printing tests, the surface of the photosensitive drum 37 is worn by continuing to use the photosensitive drum 37 for forming a print image (that is, printing). It was found that the wear progressed.

  Further, according to the first and second continuous paper passing printing tests, the surface of the photosensitive drum 37 is a portion facing the central portion of the toner carrying range on the surface of the developing roller 80 due to continuous use for the formation of the printed image. Wear (that is, the amount of film reduction) gradually increases from the facing portion 83A to PL3 corresponding to the facing surface 83A of the left toner seal 83 and from the facing portion to the portions PR1 to PR3 corresponding to the facing surface 84A of the right toner seal 84. It turned out to be largest at these points.

  That is, the photoconductive layer of the photosensitive drum 37 extends from the portion facing the central portion of the toner carrying range on the surface of the developing roller 80 to the portions PL1 to PL3 corresponding to the facing surface 83A of the left toner seal 83, and the facing portion. It was found that the amount of film reduction increased from the location PR1 to PR3 corresponding to the facing surface 84A of the right toner seal 84.

  In the photosensitive drum 37, for example, when the layer thickness of the toner 64 carried in the toner carrying range on the surface of the developing roller 80 in the third image forming unit 12 becomes uneven, the photoconductive layer tends to be thinned. Is considered to occur.

  That is, in the third image forming unit 12, when the toner 64 supplied to the surface of the developing roller 80 enters between the surface and the edge of the toner blade 82, the toner blade 82 is pressed from the center of the surface. Although it moves to both ends (that is, left and right), the movement is limited by the left toner seal 83 and the right toner seal 84, so that both ends of the surface are thicker than the central portion of the toner carrying range. It is thought that it may be carried.

  In such a case, in the third image forming unit 12, in a state where the surface of the developing roller 80 is pressed against the surface of the photosensitive drum 37 via the toner 64, the toner 64 has both ends than the center portion of the toner carrying range. Since the amount of the external additive contained in the toner 64 at both end portions is also large, the external additive acts like an abrasive, so that the central portion of the toner carrying range on the surface of the photosensitive drum 37 is increased. It is thought that the wear of the facing part with both end portions increases more than the facing part.

  In addition, in the photosensitive drum 37, for example, when the developing roller 80 is bent to press the surface of the developing roller 80 against the surface of the photosensitive drum 37 in the third image forming unit 12, the film thickness of the photoconductive layer is reduced. It is thought that there is a bias in

  That is, in order to press the surface of the developing roller 80 against the surface of the photosensitive drum 37, the third image forming unit 12 causes the main body case 70 to move the developing roller 80, and the left end and the right end of the developing roller rotating shaft 80 </ b> A to the photosensitive drum 37. It is supported so that it can rotate in a state of being biased to the side.

  For this reason, in the third image forming unit 12, the developing roller 80 is biased by the developing roller rotating shaft 80 </ b> A so that both end portions (that is, the left end portion and the right end portion) are positioned on the surface of the photosensitive drum 37 rather than the center portion. It is thought that there is a case where it bends so as to press strongly.

  In such a case, in the third image forming unit 12, in a state where the surface of the developing roller 80 is pressed against the surface of the photosensitive drum 37 via the toner 64, the surface of the developing roller 80 is brought into contact with the surface of the photosensitive drum 37. Both end portions rub the toner 64 more strongly than the central portion.

  Therefore, in the third image forming unit 12, the external additive contained in the toner 64 also acts like an abrasive in such a case, so that the surface of the photosensitive drum 37 is in contact with the central portion of the toner carrying range of the developing roller 80. It is considered that the wear of the facing portion with both end portions increases more than the facing portion.

  In the photosensitive drum 37 after the end of the second continuous paper-pass printing test, the amount of film reduction of the photoconductive layer is larger than the amount of film reduction of the photoconductive layer of the photosensitive drum 37 after the end of the first continuous paper-pass printing test. It is thought that the increase in the amount of film reduction (that is, the significant decrease in the remaining film thickness) caused printing stains and also caused deterioration in print quality.

  That is, in the third image forming unit 12, when the film thickness is biased in the photoconductive layer of the photosensitive drum 37 and the remaining film thickness is remarkably reduced, the portion where the remaining film thickness is significantly reduced is affected by the conductive substrate. It is considered that it becomes difficult to hold electric charge and it is difficult to charge to a specified potential.

  For this reason, in the third image forming unit 12, when developing the electrostatic latent image on the surface of the photosensitive drum 37, the toner 64 adheres to the portion of the photoconductive layer where the remaining film thickness is significantly reduced even if it is not exposed. The toner 64 is transferred to the surface of the recording paper 5, and the toner 64 appears as printing stains on the surface of the recording paper 5. As a result, the print quality is considered to be deteriorated.

  On the other hand, in the first continuous paper-pass printing test, the photosensitive drum 37 is displaced in the drum longitudinal direction during the test, so that the toner carrying range on the surface of the developing roller 80 is compared with the surface of the photosensitive drum 37. It is considered that the portion where the wear progresses locally (that is, the portion facing both ends of the toner carrying range) can be shifted, and as a result, the surface wear of the photosensitive drum 37 can be suppressed.

  Actually, the photosensitive drum 37 after completion of the first continuous paper-pass printing test can reduce the amount of film loss of the photoconductive layer as a whole, and the photoconductivity of the photosensitive drum 37 after completion of the second continuous paper-pass printing test. Compared with the amount of film reduction of the layer, the maximum value of the film reduction amount could be suppressed by about 17%.

  Therefore, according to the color printer 1 according to the first embodiment, the photosensitive drums 35 to 38 are displaced in the longitudinal direction of the drum during use, and the contact positions of the surfaces of the photosensitive drums 35 to 38 with respect to the surface of the developing roller 80 are changed. Since they are shifted, similarly to the test result of the first continuous paper-pass printing test, it is possible to change the portion where the wear progresses locally on the surface of the photosensitive drums 35 to 38 and to suppress the wear as a whole.

  Therefore, in the color printer 1 according to the first embodiment, the photosensitive drums 35 to 38 do not cause print stains and the print quality is higher than when the photosensitive drums 35 to 38 are not displaced in the drum longitudinal direction. The service life of the photosensitive drums 35 to 38 can be extended.

  In the color printer 1 according to the first embodiment, the photosensitive drums 35 to 38 are provided in the first to fourth image forming units 10 to 13 that are detachably attached to the printer housing 2, so By extending the service life of the drums 35 to 38, the service life of the first to fourth image forming units 10 to 13 can be extended as a result.

(1-6) Operation and Effect of First Embodiment In the above configuration, the color printer 1 is a developing roller in the first to fourth image forming units 10 to 13 that are detachably attached to the printer housing 2. The photosensitive drums 35 to 38 to which 80 is pressed are supported so as to be rotatable via a drum rotation shaft and to be displaceable in the drum longitudinal direction.

  Further, in the color printer 1, solenoids 95 are respectively arranged at positions facing the right end surfaces of the drum rotation shafts of the photosensitive drums 35 to 38 supported by the first to fourth image forming units 10 to 13 in the printer housing 2. I did it.

  Then, the color printer 1 operates the solenoid 95 for each of the first to fourth image forming units 10 to 13 according to the frequency of use of the photosensitive drums 35 to 38, and moves the corresponding photosensitive drums 35 to 38 to the left of the printer. It was made to displace by a predetermined displacement amount.

  Therefore, in the color printer 1, due to the displacement of the photosensitive drums 35 to 38, the portion of the surface of the photosensitive drums 35 to 38 where the wear progresses locally due to the contact with the developing roller 80 via the toner (that is, the toner carrying range). It is possible to suppress the wear of the surface as a whole by changing the facing portion.

  Therefore, the color printer 1 can extend the service life of the photosensitive drums 35 to 38 provided in the first to fourth image forming units 10 to 13, and as a result, the first to fourth image forming units 10 to 13. The service life can be extended.

  According to the above configuration, the color printer 1 rotates the photosensitive drums 35 to 38 whose developing rollers 80 are pressed against the first to fourth image forming units 10 to 13 that are detachably attached to the printer housing 2. The drum 95 is supported so as to be displaceable in the longitudinal direction of the drum through a shaft, and a solenoid 95 is attached to each of the mounting portions of the first to fourth image forming units 10 to 13 in the printer housing 2 as the drum rotation shafts of the photosensitive drums 35 to 38. The solenoids 95 are arranged so as to face the right end surface, and the respective solenoids 95 are operated according to the frequency of use of the photosensitive drums 35 to 38 to displace the photosensitive drums 35 to 38 by a predetermined displacement amount in the left direction of the printer.

  As a result, during use, the color printer 1 changes the part of the surface of the photosensitive drums 35 to 38 where the wear progresses locally due to contact with the developing roller 80 via the toner, thereby removing the entire surface wear. The service life of the photosensitive drums 35 to 38 can be extended.

  Therefore, the color printer 1 can improve the convenience by reducing the number of times the photosensitive drums 35 to 38 are replaced.

  By the way, if it is merely to avoid that the amount of film loss significantly increases in the toner image forming range having a width substantially equal to the lateral width of the recording paper on the surface of the photosensitive drums 35 to 38, for example, the photosensitive drums 35 to 38 are displaced at all. Instead, a method is conceivable in which the width of the toner carrying area on the surface of the developing roller 80 is significantly wider than the horizontal width of the recording paper together with the arrangement interval of the left toner seal 83 and the right toner seal 84.

  However, according to such a method, in order not to displace the photosensitive drums 35 to 38, the photoconductive layers of the photosensitive drums 35 to 38 are biased to reduce the film similarly to the test result of the second continuous paper-pass printing test described above. It cannot be avoided that the amount of film loss is significantly increased at both ends.

  According to such a technique, when the residual film thickness is significantly reduced at both ends of the photoconductive layers of the photosensitive drums 35 to 38, the surface of the developing roller 80 is developed on the surface of the photosensitive drums 35 to 38 when developing the electrostatic latent image. It is considered that the current leaks from the central portion to both ends due to the bias voltage applied between and the toner, and accordingly, the toner moves from the central portion to both ends.

  Therefore, according to such a method, the toner image cannot be accurately formed on the surface of the photosensitive drums 35 to 38 because a prescribed amount of toner is difficult to adhere to the central portion of the toner image formation range. The print image formed so as to be transferred to the surface of 5 is considered to be remarkably deteriorated in print quality due to fading of colors and blurring of edges.

  In contrast, in the color printer 1, since the photosensitive drums 35 to 38 are displaceable, the photosensitive drums 35 to 38 are arranged together with the interval between the left toner seal 83 and the right toner seal 84 and the width of the toner carrying range on the surface of the developing roller 80. It is possible to suppress the wear of the surfaces of the photosensitive drums 35 to 38 without unnecessarily widening the width of the 38 toner image forming range.

  Therefore, when the color printer 1 develops the electrostatic latent images on the surfaces of the photosensitive drums 35 to 38, the toner moves on the surfaces and the toner image cannot be formed accurately, and the print quality of the print image is low. It is possible to reliably prevent a significant decrease due to color fading or edge blurring.

  Further, the color printer 1 detects the displacement of the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 13 and the charging rollers 75 and 38 together with the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 13. The process is performed while the developing roller 80 is idling.

  Accordingly, when the color printer 1 displaces the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 14, the surface of the photosensitive drums 35 to 38 has the surface of the charging roller 75 and the surface of the developing roller 80. It is possible to prevent linear dents and scratches along the longitudinal direction of the drum due to the friction.

  That is, the color printer 1 almost certainly ensures that when the photosensitive drums 35 to 38 are displaced in the first to fourth image forming units 10 to 14, the surfaces of the photosensitive drums 35 to 38 are damaged by the displacement. Can be prevented.

(2) Second Embodiment (2-1) Internal Configuration of Color Printer FIG. 7, in which the same reference numerals are assigned to corresponding parts to FIG. 1, shows a color printer 120 according to the second embodiment. The color printer 120 is configured in the same manner as the color printer 1 according to the first embodiment described above, except for the configuration of the detachable first to fourth image forming units 122 to 125 included in the image forming unit 121. ing.

(2-2) Configuration of Image Forming Unit Accordingly, in the following, the first to fourth image forming units 122 to 122 will be described with reference to FIGS. The configuration of 125 will be described.

  However, the first to fourth image forming units 122 to 125 have the same configuration except that the color of the toner 64 used for developing the electrostatic latent image is different.

  Therefore, the configuration of the third image forming unit 124 that uses magenta (M) toner 64 for developing the electrostatic latent image, for example, among the first to fourth image forming units 122 to 125 will be described below. Description of the configuration of the first image forming unit 122, the second image forming unit 123, and the fourth image forming unit 125 will be omitted.

  As shown in FIGS. 8 and 9, the third image forming unit 124 includes a configuration of the unit main body 130 as a developing unit, a configuration of the charging roller 132 of the toner image forming unit 131, and a configuration of the LED head 133. Except for this, it is configured in the same manner as the first to fourth image forming units 10 to 13 according to the first embodiment described above.

  In this case, the unit main body 130 includes, for example, a substantially wedge-shaped roller storage case 135 having a width equal to the main body case width and a substantially L-shaped drum storage case 136 having a width equal to the main body case width. Yes.

  The roller storage case 135 is basically the same external shape, internal shape and size as the roller storage portion 70A of the main body case 70 of the first to fourth image forming units 10 to 13 according to the first embodiment described above. have.

  The drum storage case 136 is basically the same external shape, internal shape and size as the drum storage portion 70B of the main body case 70 of the first to fourth image forming units 10 to 13 according to the first embodiment. Have

  The roller storage case 135 has a drum storage case 136 at the front end thereof, which has a predetermined leftward direction from the state in which the right side surfaces 135A and 136A are flush with each other and the left side surfaces 135B and 136B are flush with each other. It is attached so that it can be displaced by the amount of displacement.

  As a result, the roller storage case 135 has the drum storage case 136 described above together with the drum storage case 136 when the right side surfaces 135A and 136A are flush with each other and the left side surfaces 135B and 136B are flush with each other. An external appearance shape substantially the same as that of the main body case 70 is formed.

  In the roller storage case 135, the developing roller 80, the supply roller 81, the toner blade 82, the left toner seal 83, and the right toner seal 84 as the toner supply unit 72 are in the same positions as in the first embodiment described above. Provided in relation.

  On the other hand, in the drum storage case 136, the photosensitive drum 37 as the toner image forming unit 131 and the drum cleaning blade 76 are provided in the same positional relationship as in the above-described first embodiment.

  However, although the charging roller 132 is basically configured in the same manner as in the first embodiment described above, the length from the left end surface to the right end surface is, for example, the first embodiment described above. In this case, the length is selected to be slightly longer than that of the case.

  The charging roller 132 is fixedly provided with a charging roller rotating shaft 132A that is aligned with the central axis of the charging roller 132 so that the left end portion and the right end portion protrude from the left end surface and the right end surface of the charging roller 132. In the charging roller rotating shaft 132A, the protruding length of the left end portion is selected to be a predetermined length longer than the protruding length of the right end portion.

  Then, the charging roller 132 is placed on the drum storage case 136 so that the longitudinal direction of the charging roller is parallel to the width direction of the main body and the center of the surface is slightly shifted to the right side of the center of the surface of the photosensitive drum 37. In a state where the front oblique lower part which is a part is pressed against the rear oblique upper part which is a part of the surface of the photosensitive drum 37, the part is provided to be rotatable around the charging roller rotation shaft 132 </ b> A.

  In other words, the charging roller 132 causes the charging roller rotating shaft 132A to be parallel to the width direction of the main body (that is, the drum longitudinal direction) by the drum storage case 136, and a part of the surface is a portion of the surface of the photosensitive drum 37 before the exposure position. In a state where it is pressed toward the right end surface, it is rotatably supported via the charging roller rotating shaft 132A.

  Thus, the surface of the charging roller 132 can be opposed to the toner carrying range on the surface of the developing roller 80 either before or after the drum storage case 136 is displaced.

  In other words, when the drum storage case 136 is displaced, the photosensitive drum 37 has its surface toner image forming range shifted to the right end surface side with respect to the toner carrying range of the developing roller 80.

  However, since the charging roller 132 presses a part of its surface toward the right end surface of the surface of the photosensitive drum 37, the drum storage case 136 is displaced and the toner image forming range on the surface of the photosensitive drum 37 is moved to the right end surface side. Even if they are displaced, the state where the surface of the charging roller 132 is pressed against the toner image forming range can be maintained.

  In addition to this, the LED head 133 is basically formed in the same manner as in the first embodiment, but the positional relationship with respect to the surface of the photosensitive drum 37 is the same as that in the first embodiment. The roller storage case 135 is attached in the same manner as in the case.

  Thereby, even if the drum storage case 136 is displaced, the LED head 133 can accurately irradiate the irradiation light for exposure to the toner image forming range on the surface of the photosensitive drum 37 based on the toner carrying range of the developing roller 80. I am doing so.

  With this configuration, the third image forming unit 124 moves the roller storage case 135 and the drum storage case 136 forward and backward with respect to the color printer 120 with the main body width direction (that is, the drum longitudinal direction) parallel to the printer left-right direction. It is mounted so as to be detachable with a mounting posture positioned at the position.

  Therefore, when the third image forming unit 124 is mounted on the color printer 120, the lower part of the surface of the photosensitive drum 37 is brought into contact with the surface of the transfer belt 47 of the transfer unit 14.

  Further, the third image forming unit 124 is mounted on the color printer 120 in such a mounting posture, so that the toner cartridge 66 is positioned on the roller storage case 135.

  Accordingly, when the open / close operation lever of the toner cartridge 66 is operated and the shutter 90 is opened while the third image forming unit 124 is mounted on the color printer 120, the third image forming unit 124 removes the toner 64 from the toner storage portion 88 and the toner discharge port 87 </ b> AY and the toner. It can be supplied so as to drop into the roller storage case 135 via the intake port 70AZ in sequence.

  As a result, the third image forming unit 124 can form an electrostatic latent image on the surface of the photosensitive drum 37 during the formation of the print image, as in the case of the first embodiment described above. A toner image can be formed based on the image and transferred to the surface of the recording paper 5.

  By the way, when the third image forming unit 124 is mounted, the printer housing 2 brings the end surface of the plunger 95B of the solenoid 95 close to or in contact with the right side surface 136B of the drum storage case 136 of the third image forming unit 124. ing.

  Then, as in the case of the first embodiment described above, the control unit 100 operates the solenoid 95 according to the frequency of use of the photosensitive drum 37, so that the third image forming unit 124 is operated by the plunger 95 </ b> B of the solenoid 95. The drum storage case 136 can be displaced by a predetermined amount in the left direction of the printer.

  That is, the control unit 100 operates the solenoid 95 according to the usage frequency of the photosensitive drum 37, thereby integrating the photosensitive drum 37, the charging roller 132, and the drum cleaning blade 76 as the drum storage case 136 in the third image forming unit 124. Can be displaced to the left of the printer along the longitudinal direction of the drum.

  Thus, the control unit 100 can shift the pressing position (that is, the contact position) of the surface of the developing roller 80 against the surface of the photosensitive drum 37 in the third image forming unit 124 along the longitudinal direction of the drum.

  By the way, in the color printer 120, at least one of the photosensitive drum gear of the third image forming unit 124 and the unit motor connecting gear directly meshed with the photosensitive drum gear is formed to be relatively wide.

  Therefore, the color printer 120 can maintain the state in which the photosensitive drum gear is connected to the output shaft of the unit drive motor via the plurality of unit motor connecting gears even when the drum storage case 136 is displaced in the third image forming unit 124. it can.

  Accordingly, even if the drum storage case 136 is displaced in the third image forming unit 124, the color printer 120 rotates the photosensitive drum 37 in the same manner as before the displacement according to the operation of the unit drive motor during the subsequent print image formation. The charging roller 132 can be rotated in one rotation direction in conjunction with the rotation of the charging roller 132 to form an electrostatic latent image and a toner image.

  In this manner, the color printer 120 appropriately shifts the pressing position of the surface of the developing roller 80 with respect to the surface of the photosensitive drum 37 in the third image forming unit 124, and thereafter operates the photosensitive drum 37 at a displaced position. As in the case of the first embodiment described above, film loss that occurs in the photoconductive layer of the photosensitive drum 37 can be reduced.

  Similarly, the color printer 120 also includes the drum storage case 136 and the photosensitive drum 35, the first image forming unit 122, the second image forming unit 123, and the fourth image forming unit 125 other than the third image forming unit 124. By displacing 36 and 38 in the longitudinal direction of the drum, film loss generated in the photoconductive layer of the photosensitive drums 35, 36 and 38 can be reduced.

(2-3) Continuous Paper Passing Printing Test Next, a third continuous paper passing printing test conducted to confirm the effect of the present invention will be described. Note that the third continuous paper passing printing test was also performed using the third image forming unit 124 in the same manner as the first and second continuous paper passing printing tests described above.

  In the third continuous paper-pass printing test, a new photosensitive drum 37 is prepared, and the photosensitive drum 37 is measured for the film thickness of the photoconductive layer as in the case of the first continuous paper-pass printing test described above. After measuring the outer diameter, the third image forming unit 124 was assembled.

  In the third continuous paper printing test, the continuous printing of the test print pattern on 40000 recording papers 5 was performed by the color printer 120 as in the case of the first continuous paper printing test described above.

  In the third continuous paper-pass printing test, when the color printer 120 has finished printing the test print pattern on the surface of the 20000th recording paper 5, printing is temporarily stopped as in the first continuous paper-pass printing test. It was.

  In the third continuous paper printing test, at this time, the operation of the LED head 133 is stopped and no paper is passed, and the printing of the 20,000th recording paper 5 is completed in the first continuous paper printing test. The solenoid 95 was operated while the photosensitive drum 37 and the developing roller 80 were idled in the third image forming unit 124 by the same number of revolutions as the photosensitive drum 37 and the developing roller 80 and others were idly rotated.

  As a result, in the third continuous paper printing test, the photosensitive drum 37 and the charging roller are used as the drum storage case 136 in the third image forming unit 124 while matching the usage conditions of the photosensitive drum 37 and the case of the first continuous paper printing test as much as possible. 132 and the drum cleaning blade 76 are integrally moved by a displacement of 20 [mm] in the left direction of the printer, and the contact position of the surface of the photosensitive drum 37 with respect to the surface of the developing roller 80 is shifted along the longitudinal direction of the drum. .

  In the third continuous paper-pass printing test, the remaining 20000 sheets of recording paper 5 by the color printer 120 are provided with the photosensitive drum 37, the charging roller 132, and the drum cleaning blade 76 as the drum storage case 136 in the third image forming unit 124. The test print pattern was continuously printed while being displaced integrally.

  In this way, in the third continuous paper-pass printing test, a test print pattern (that is, a test print pattern in which the print duty is set to 40 [%]) printed on the 40000th recording paper 5 by the color printer 120 is printed. The print quality of the image was confirmed and was good as in the case of the first continuous paper-pass printing test.

  In the third continuous paper-pass printing test, the photosensitive drum 37 is removed from the third image forming unit 124 when the printing of the test print pattern on the 40,000 recording sheets 5 by the color printer 120 is completed. The amount of film loss of the photoconductive layer was detected in the same manner as in the continuous paper printing test.

  As a result, even in the photosensitive drum 37 after completion of the third continuous paper-pass printing test, the film reduction amount and film reduction amount in the photoconductive layer are substantially the same as those in the case of the photosensitive drum 37 after completion of the first continuous paper-pass printing test. there were.

  Therefore, it is confirmed by the third continuous paper-pass printing test that the third image forming unit 124 can suppress the surface wear of the photosensitive drum 37 as in the third image forming unit 12 according to the first embodiment. We were able to.

  By the way, in the first continuous paper-pass printing test described above, the print quality was good even when printing of the test print pattern on 40000 sheets of recording paper 5 was completed. When the surface of the charging roller 75 was observed in the third image forming unit 12 according to the form, it was confirmed that the external additive of the toner 64 adhered to the surface of the charging roller 75 in the form of a film.

  Therefore, in the present invention, the third image formation according to the first embodiment described above is performed in order to confirm what kind of influence is exerted on the print quality when the external additive of the toner 64 adheres to the surface of the charging roller 75. Although the printing conditions were the same as those of the first continuous paper passing printing test using the unit 12, a fourth continuous paper passing printing test in which the number of prints of the recording paper 5 was increased was additionally performed.

  As a result, in the fourth continuous paper-pass printing test, when a test print pattern (that is, a test print pattern with a print duty of 40%) is printed on the 42,000th recording paper 5, the test print It was confirmed that the vertical streak pattern appeared in the print image of the print pattern and the print quality was deteriorated.

  Such deterioration in print quality is caused by, for example, the third image forming unit 12 according to the first embodiment displacing only the photosensitive drum 37, and the displacement causes the contact between the surface of the photosensitive drum 37 and the drum cleaning blade 76. This is thought to be due to the change in state.

  That is, in the third image forming unit 12 according to the first embodiment, the contact state between the surface of the photosensitive drum 37 and the drum cleaning blade 76 is changed by the displacement of the photosensitive drum 37, so that the surface of the photosensitive drum 37 is changed. It is considered that the external additive of the toner 64 remaining in the transferred portion of the toner image is not completely removed by the drum cleaning blade 76 but is transported to the charging roller 75 and adhered to the surface of the charging roller 75.

  In the third image forming unit 12 according to the first embodiment, the external additive adhering to the surface of the charging roller 75 gradually increases every time the printing of the test print pattern on the recording paper 5 is repeated. Therefore, it is difficult to accurately charge the surface of the photosensitive drum 37 by the charging roller 75, and therefore, excess toner adhered to the surface of the photosensitive drum 37 in the transfer of the toner 64 to the electrostatic latent image (development of the electrostatic latent image). It is considered that 64 appeared as vertical stripes in the printed image.

  On the other hand, in the third continuous paper-pass printing test, the adhesion of the external additive of the toner 64 to the surface of the charging roller 132 is observed even when printing of the test print pattern on 40000 recording papers 5 is completed. I couldn't.

  For this reason, in the present invention, for comparison with the fourth continuous paper-pass printing test, although the printing conditions are the same as those in the third continuous paper-pass printing test, the fifth continuous paper number is increased to 42,000. An additional paper-pass printing test was conducted.

  That is, in the present invention, the third image forming unit 124 according to the second embodiment also performs the third continuous sheet passing in order to check whether the external additive of the toner 64 adheres to the surface of the charging roller 132 by continuous printing. A fifth continuous paper printing test was performed in which the number of printed sheets of recording paper 5 was increased under the same printing conditions as in the printing test.

  As a result, in the fifth continuous paper-pass printing test, the charging roller 132 is printed even when a test print pattern (that is, a test print pattern with a print duty of 40 [%]) is printed on the 42,000th recording paper 5. The external additive did not adhere to the surface, and the print quality of the printed image was good.

  This is different from the third image forming unit 12 according to the first embodiment in the case of the third image forming unit 124 according to the second embodiment, in which the photosensitive drum 37 is used as the drum storage case 136 and the charging roller 132 and the drum. This is considered to be because the contact state between the surface of the photosensitive drum 37 and the drum cleaning blade 76 did not change due to the displacement integrally with the cleaning blade 76.

  That is, in the third image forming unit 124 according to the second embodiment, even if the photosensitive drum 37 is displaced, the positional relationship between the photosensitive drum 37 and the drum cleaning blade 76 (or the charging roller 132) does not change at all. Even if the external additive of the toner 64 remains on the surface of the photosensitive drum 37 after the transfer of the toner image, it is considered that the drum cleaning blade 76 could remove the external additive accurately.

  In the third image forming unit 124 according to the second embodiment, the external additive does not adhere to the surface of the charging roller 75 even if the test print pattern is repeatedly printed on the recording paper 5 after the photosensitive drum 37 is displaced. For this reason, the surface of the photosensitive drum 37 can be accurately charged by the charging roller 75, and thus excellent toner 64 can be prevented from adhering to the surface of the photosensitive drum 37 during the development of the electrostatic latent image. It is thought that quality could be maintained.

  Therefore, according to the third and fifth continuous paper passing printing tests, in the third image forming unit 124 according to the second embodiment, the surfaces of the photosensitive drums 35 to 38 as in the case of the first embodiment described above. It was confirmed that the wear of the resin can be suppressed.

  Further, according to the third and fifth continuous paper passing printing tests, it is confirmed that the third image forming unit 124 according to the second embodiment can prevent the external additive from adhering to the surface of the charging roller 132. I was able to.

  For this reason, according to the color printer 120 of the second embodiment, the photosensitive drums 35 to 38 are displaced together with the charging roller 132 and the drum cleaning blade 76 during the use thereof, and therefore the first embodiment described above. As in the case of this embodiment, local wear can be suppressed by changing the portion of the surface of the photosensitive drums 35 to 38 where wear progresses locally.

  Further, according to the color printer 120 according to the second embodiment, the photosensitive drums 35 to 38 are displaced integrally with the charging roller 132 and the drum cleaning blade 76 during the use thereof, and thus the first embodiment described above. Compared to the case of the embodiment, the charging roller 132 can be continuously operated without attaching an external additive to the surface.

  That is, according to the color printer 120 according to the second embodiment, the photosensitive drums 35 to 38 can be formed without attaching external additives to the surface of the charging roller 132 as compared with the case of the first embodiment described above. The period in which the surface of the charging roller 132 can be used to be accurately charged, that is, the service life of the charging roller 132 can be extended.

  Therefore, in the color printer 120 according to the second embodiment, the service life of the first to fourth image forming units 122 to 125 can be extended as compared with the case of the first embodiment described above.

(2-4) Operation and Effect of Second Embodiment In the above configuration, the color printer 120 is sensitive to the first to fourth image forming units 122 to 125 that are detachably attached to the printer housing 2. The drums 35 to 38, the charging roller 132, and the drum cleaning blade 76 are provided so as to be integrally displaceable.

  Then, the color printer 120 operates the solenoid 95 for each of the first to fourth image forming units 122 to 125 according to the frequency of use of the photosensitive drums 35 to 38, and the photosensitive drums 35 to 38, the charging roller 132, and the drum cleaning. The blade 76 is integrally displaced by a predetermined amount in the left direction of the printer.

  Therefore, the color printer 120 can keep the surface of the photosensitive drums 35 to 38 from being worn as a whole, and can keep the charging roller 132 operated without attaching an external additive to the surface.

  Therefore, the color printer 120 can extend the service life of the charging roller 132 together with the photosensitive drums 35 to 38 provided in the first to fourth image forming units 122 to 125. As a result, compared with the first embodiment. Thus, the service life of the first to fourth image forming units 122 to 125 can be further extended.

  According to the above configuration, the color printer 120 includes the photosensitive drums 35 to 38, the charging roller 132, and the drum cleaning blade 76 in the first to fourth image forming units 122 to 125 that are detachably attached to the printer housing 2. The solenoids 95 are operated in accordance with the frequency of use of the photosensitive drums 35 to 38, and the photosensitive drums 35 to 38, the charging roller 132, and the drum cleaning blade 76 are integrated in the left direction of the printer. It was made to displace by the amount of displacement.

  Therefore, the color printer 120 can obtain the same effect as that obtained by the first embodiment described above, and in addition, can extend the service life of the charging roller 132 together with the photosensitive drums 35 to 38. .

  Therefore, the color printer 120 can further improve convenience by reducing the number of times the charging roller 132 is replaced together with the photosensitive drums 35 to 38.

(3) Other embodiments (3-1) Other embodiments 1
In the first and second embodiments described above, the photosensitive drums 35 to 38 are installed in the first to fourth image forming units 10 to 13 and 122 to 125 according to the frequency of use of the photosensitive drums 35 to 38. The case has been described in which it is displaced once in the left direction of the printer, which is one direction parallel to the drum rotation axis.

  However, the present invention is not limited to this, and the photosensitive drums 35 to 38 are parallel to the drum rotation axis in the first to fourth image forming units 10 to 13 and 122 to 125 according to the frequency of use of the photosensitive drums 35 to 38. It may be displaced once in the right direction of the printer, which is another direction.

  Further, according to the present invention, in the first to fourth image forming units 10 to 13 and 122 to 125, the photosensitive drums 35 to 38 are moved stepwise in the printer left direction or the printer right direction in accordance with the frequency of use of the photosensitive drums 35 to 38. It may be displaced twice or more.

  Incidentally, the present invention is the same as the first continuous paper-pass printing test described above except that, for example, the third image forming unit 12 according to the first embodiment is used and the photosensitive drum 37 is displaced twice. The sixth continuous paper passing printing test was conducted under various printing conditions.

  In the sixth continuous paper passing print test, for example, when the test print pattern is printed on the 13,000th recording paper 5 out of 40000 recording papers 5, the photosensitive drum 37 is moved to the left of the printer as the first displacement. For example, it was displaced by a displacement amount of 10 [mm].

  In the sixth continuous paper-pass printing test, for example, when a test print pattern is printed on the 26000th recording paper 5 out of 40000 recording papers 5, the photosensitive drum 37 is moved to the left of the printer as a second displacement. Further, it was displaced by a displacement amount of 10 [mm].

  As a result, in the sixth continuous paper-pass printing test, when the test print pattern was printed on the 40000th recording paper 5, the print quality of the print image of the test print pattern was confirmed, but it was good.

  In the sixth continuous sheet-pass printing test, when the printing of the test print pattern on 40000 recording sheets 5 is completed, the amount of film reduction of the photoconductive layer of the photosensitive drum 37 is detected. The maximum value of the amount is 12.1 [μm], and it is possible to suppress the surface wear more than the photosensitive drum 37 after the first continuous paper-pass printing test (that is, the amount of film reduction can be suppressed). It could be confirmed.

  As described above, according to the present invention, in the first to fourth image forming units 10 to 13 and 122 to 125, the photosensitive drums 35 to 38 are moved in the printer left direction or the printer right direction in accordance with the use frequency of the photosensitive drums 35 to 38. Even if it is displaced stepwise twice or more by a predetermined amount, it is possible to suppress the wear of the surface of the photosensitive drums 35 to 38 and extend the service life of the photosensitive drums 35 to 38.

  By the way, according to the present invention, in the first to fourth image forming units 10 to 13 and 122 to 125, the photosensitive drums 35 to 38 are moved in the printer left direction or the printer right direction depending on the frequency of use of the photosensitive drums 35 to 38. When the displacement is performed twice or more, the displacement amount may be always constant, such as 1 [mm] or 5 [mm].

  Further, according to the present invention, in the first to fourth image forming units 10 to 13 and 122 to 125, the photosensitive drums 35 to 38 are moved stepwise in the printer left direction or the printer right direction in accordance with the frequency of use of the photosensitive drums 35 to 38. In the case of two or more displacements, the amount of displacement may be varied as appropriate.

  Further, in the present invention, for example, when the individual displacement amount of the stepwise two or more displacements is relatively small such as 5 mm or less, the first to fourth image forming units 10 to 13 and 122 to 125 are used. The photosensitive drums 35 to 38 may be displaced leftward or rightward with the rotation of the photosensitive drums 35 to 38, the charging rollers 75 and 132, the developing roller 80, and the supply roller 81 stopped.

  According to the present invention, the wear of the surfaces of the photosensitive drums 35 to 38 can also be suppressed by these configurations, and the service life of the photosensitive drums 35 to 38 can be extended.

(3-2) Other Embodiment 2
In the first and second embodiments described above, the photosensitive drums 35 to 38 are individually used in the first to fourth image forming units 10 to 13 and 122 to 125 according to the frequency of use of the photosensitive drums 35 to 38. The case where the photosensitive drums 35 to 38 are displaced together with the charging roller 132 and the drum cleaning blade 76 in the left direction of the printer has been described.

  However, the present invention is not limited to this, and the photosensitive drums 35 to 38 are replaced with the charging roller 132 and the drum in the first to fourth image forming units 10 to 13 and 122 to 125 according to the usage frequency of the photosensitive drums 35 to 38. It may be displaced together with one of the cleaning blades 76 once in the left direction or right direction of the printer, or stepwise twice or more.

  The present invention can also obtain the same effect as that obtained by the first or second embodiment described above even with such a configuration.

  Further, according to the present invention, for example, the arrangement of the left toner seal 83 and the right toner seal 84 in the first to fourth image forming units 10 to 13 and 122 to 125 is compared with the first and second embodiments described above. While widening the interval, the lengths of the supply roller 81 and the toner blade 82 are lengthened, so that the width of the toner carrying area on the surface of the developing roller 80 is made wider than the horizontal width of the recording paper.

  In addition, according to the present invention, the developing roller 80 is replaced with the supply roller 81 in place of the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 13 and 122 to 125 according to the frequency of use of the photosensitive drums 35 to 38. The toner blade 82, the left toner seal 83, and the right toner seal 84 may be integrally displaced in the left direction of the printer or the right direction of the printer once or more than twice in stages.

  According to the present invention, it is possible to obtain the same effect as that obtained by the first or second embodiment described above by suppressing the surface wear of the photosensitive drums 35 to 38 as a whole. .

  Further, according to the present invention, although the width of the toner carrying range on the surface of the developing roller 80 is increased, the developing roller 80 is appropriately displaced, so that the operation and effect of the first embodiment are described. As described above, the toner moves during development of the latent image, and as a result, it is possible to reliably prevent the print quality from being significantly deteriorated due to the color fading and the edge blurring in the printed image.

  By the way, according to the present invention, the unevenness of the film reduction generated in the photoconductive layers of the photosensitive drums 35 to 38 is not caused by the non-uniform layer thickness of the toner carried on the surface of the developing roller 80, but the developing roller 80. In the first to fourth image forming units 10 to 13 and 122 to 125, the width of the toner carrying range for the displacement of the developing roller 80 is made wider than the horizontal width of the recording paper, and the development is performed. Only the roller 80 may be displaced once in the left direction or right direction of the printer, or two or more times stepwise.

  Further, in the present invention, when the width of the toner carrying range is widened for the displacement of the developing roller 80 in this way, the toner image forming units 71 and 131 side in the first to fourth image forming units 10 to 13 and 122 to 125 are arranged. At least the photosensitive drums 35 to 38 and at least the developing roller 80 on the toner supply unit 72 side may be simultaneously displaced in the left direction and the right direction of the printer opposite to each other once or stepwise twice or more.

  Further, in the present invention, when the width of the toner carrying range is widened for the displacement of the developing roller 80 in this way, the toner image forming units 71 and 131 side in the first to fourth image forming units 10 to 13 and 122 to 125 are arranged. At least the photosensitive drums 35 to 38 and at least the developing roller 80 on the toner supply unit 72 side may be displaced alternately in the left direction and the right direction of the printer alternately one time or two times or more.

  In the present invention, at least one of the photosensitive drums 35 to 38 and the developing roller 80 is relatively moved in one direction (that is, the printer left direction or the printer right direction) in parallel with the drum rotation shaft and the development roller rotation shaft 80A. Effects similar to those obtained by the first or second embodiment described above can also be obtained by various configurations to be displaced.

  By the way, in the photosensitive drums 35 to 38, for example, even when minute irregularities exist on the surface of the developing roller 80 due to low formation accuracy of the developing roller 80, a film is formed on the photoconductive layer due to the irregularities. It is considered that a decrease in bias occurs and the amount of film decrease locally increases.

  That is, according to the present invention, even when minute irregularities are present on the surface of the developing roller 80 as described above, the amount of film reduction locally increases in the photoconductive layers of the photosensitive drums 35 to 38, so that the same as described above. The print quality of the printed image is considered to deteriorate.

  In such a case, according to the present invention, in the first to fourth image forming units 10 to 13 and 122 to 125, the width of the toner carrying range for the displacement of the developing roller 80 is made wider than the horizontal width of the recording paper. Only the developing roller 80 may be displaced once in the left direction or right direction of the printer, or two or more times stepwise.

  In the first to fourth image forming units 10 to 13 and 122 to 125, as described above, the developing roller 80 is integrated with the supply roller 81, the toner blade 82, the left toner seal 83, and the right toner seal 84. It may be displaced once in the left direction or in the right direction of the printer, or two or more times stepwise.

  According to the present invention, even when minute irregularities are present on the surface of the developing roller 80, the surface of the photosensitive drums 35 to 38 is suppressed from being worn by the irregularities, and the photosensitive drums 35 to 38 are used. Life can be extended.

(3-3) Other Embodiment 3
Further, in the first and second embodiments described above, the first to fourth image forming units 10 to 13 and 122 to 125 are controlled by the control unit 100 according to the number of printed sheets representing the usage frequency of the photosensitive drums 35 to 38. In the above description, the photosensitive drums 35 to 38 are displaced all at once.

  However, the present invention is not limited to this, and the control unit 100 detects the number of rotations of the photosensitive drums 35 to 38 representing the usage frequency of the photosensitive drums 35 to 38 via, for example, a rotary encoder, and uses the detected number of rotations. Accordingly, the photosensitive drums 35 to 38 are displaced at the same time in the first to fourth image forming units 10 to 13 and 122 to 125 in response (that is, when the detected number of rotations reaches a predetermined number of rotations). Also good.

  By the way, some of the print images formed by the color printers 1 and 120 are expressed only by a specific color toner such as black (K) depending on the content.

  Therefore, according to the present invention, for example, when the print image is formed, the control unit 100 selectively forms the first to fourth image forming units 10 to 13 and 122 to 125 used for forming the print image. To work for.

  Incidentally, at this time, according to the present invention, the control unit 100 completely stops the operation of the first to fourth image forming units 10 to 13 and 122 to 125 that are not used for forming a print image, for example, or the photosensitive drum. Although 35 to 38 are rotated or stopped, they are separated from the transfer belt 47 and the developing roller 80 of the transfer unit 14 by a predetermined moving mechanism.

  In this way, according to the present invention, only when the control unit 100 operates the first to fourth image forming units 10 to 13 and 122 to 125 for forming a print image, the print image is transmitted via the rotary encoder. The number of rotations of the photosensitive drums 35 to 38 rotated for formation is detected.

  In the present invention, the control unit 100 determines the rotation speed of the photosensitive drums 35 to 38 detected through the rotary encoder for each of the first to fourth image forming units 10 to 13 and 122 to 125 (that is, the detection is performed). The photosensitive drums 35 to 38 may be displaced when the rotational speed reaches a preselected rotational speed.

  That is, in the present invention, the photosensitive drums 35 to 38 of the first to fourth image forming units 10 to 13 and 122 to 125 may be individually displaced.

  In the present invention, for example, the first to fourth image forming units 10 to 13 and 122 to 125 are provided with attachment / detachment detection sensors for detecting whether or not the toner cartridge 66 is attached / detached.

  Further, according to the present invention, the control unit 100 uses the counting unit and the attachment / detachment detection sensor for each of the first to fourth image forming units 10 to 13 and 122 to 125, so that the first to fourth image forming units 10 to 13 are used. , 122 to 125, the number of replacements of the toner cartridge 66 representing the usage frequency of the photosensitive drums 35 to 38 is detected.

  In the present invention, the control unit 100 corresponds to the number of replacements of the toner cartridge 66 for each of the first to fourth image forming units 10 to 13 and 122 to 125 (that is, the detected number of replacements is a predetermined replacement number). In this case, the photosensitive drums 35 to 38 may be individually displaced in the first to fourth image forming units 10 to 13 and 122 to 125.

  In the present invention, when the photosensitive drums 35 to 38 are individually displaced in the first to fourth image forming units 10 to 13 and 122 to 125 in this way, the photosensitive drums 35 to 38 whose service life has not been exhausted. (In addition, it is possible to avoid unnecessary replacement of the first to fourth image forming units 10 to 13 and 122 to 125 provided with the photosensitive drums 35 to 38).

  Further, according to the present invention, for example, an operator who maintains the color printers 1 and 120 regularly or at an arbitrary timing can use the photosensitive drums 35 to 38 according to the usage status (that is, the number of printed sheets, the number of rotations, and the number of replacements). The photosensitive drums 35 to 38 may be displaced simultaneously or individually in the first to fourth image forming units 10 to 13 and 122 to 125 by performing a predetermined operation for displacement.

  Incidentally, according to the present invention, in the first to fourth image forming units 10 to 13 and 122 to 125, the operator performs an operation for operating the solenoid 95 simultaneously or individually as a predetermined operation for displacement. The photosensitive drums 35 to 38 may be displaced simultaneously or individually.

  In the present invention, for example, the photosensitive drums 35 to 38 in the first to fourth image forming units 10 to 13 and 122 to 125 are collectively or individually pushed to the color printers 1 and 120 leftward or rightward. A displacement lever is provided for displacement.

  In the present invention, the photosensitive drums 35 to 38 are moved all at once or individually in the first to fourth image forming units 10 to 13 and 122 to 125 by operating the displacement lever as a predetermined operation for displacement. You may make it displace to.

  Further, according to the present invention, for example, the first to fourth image forming units 10 to 13 and 122 to 125 are provided with displacement levers for individually displacing the photosensitive drums 35 to 38 in the printer left direction or the printer right direction. .

  According to the present invention, the photosensitive drums 35 to 38 are individually displaced in the first to fourth image forming units 10 to 13 and 122 to 125 by causing the operator to operate the displacement lever as a predetermined operation for displacement. You may make it let it.

  In the present invention, the various configurations described in the other embodiments 1 and 2 can be combined with the various configurations described in the third embodiment.

(3-4) Other Embodiment 4
Further, in the first and second embodiments described above, the case where the first to fourth image forming units 10 to 13 and 122 to 125 are provided with the belt cleaning blade 52 made of urethane rubber has been described.

  However, the present invention is not limited to this, and the first to fourth image forming units 10 to 13 and 122 to 125 include epoxy rubber, acrylic rubber, fluororesin rubber, nitrile butadiene rubber (NBR), and styrene butadiene rubber (SBR). Other belt cleaning blades made of various elastic bodies may be provided, such as a belt cleaning blade made of an elastic body such as isoprene rubber (IR) or polybutadiene rubber.

(3-5) Other Embodiment 5
Further, in the first and second embodiments described above, the first to fourth image forming units 10 to 13, 122 to 125 are provided with the supply roller 81 made of semiconductive foamed silicon sponge. Stated.

  However, the present invention is not limited to this, and the first to fourth image forming units 10 to 13 and 122 to 125 are provided with supply rollers made of various other elastic bodies such as a semiconductive foamed urethane sponge. Anyway.

(3-6) Other Embodiment 6
Further, in the first and second embodiments described above, the first to fourth image forming units in which the image forming unit according to the present invention is detachably attached to the color printers 1 and 120 described above with reference to FIGS. The case of applying to the units 10 to 13 and 122 to 125 has been described.

  However, the present invention is not limited to this, such as a monochrome electrophotographic printer, an image forming unit that is detachably mounted on an image forming apparatus that forms a print image, such as a multi-function printer, a facsimile machine, or a multifunction peripheral. In addition, the present invention can be widely applied to image forming units having various other configurations.

(3-7) Other Embodiment 7
Further, in the first and second embodiments described above, the case where the image forming apparatus according to the present invention is applied to the color printers 1 and 120 described above with reference to FIGS. 1 to 9 has been described.

  However, the present invention is not limited to this, and an image carrier such as a monochrome electrophotographic printer, a multifunction printer, a facsimile machine, or a multi-function machine can be individually replaced, or the image carrier can be exchanged as an image forming unit. The present invention can be widely applied to image forming apparatuses having various configurations other than the image forming apparatus provided as possible.

(3-8) Other Embodiment 8
Furthermore, in the first and second embodiments described above, the conductive substrate described above with reference to FIGS. 1 to 9 is used as an image carrier that is rotatably supported through an image carrier rotation shaft and carries a latent image. The case where the photosensitive drum 37 formed by providing the photoconductive layer on the outer peripheral surface is applied is described.

  However, the present invention is not limited to this, and an inorganic photosensitive film formed by providing a photosensitive layer having a predetermined thickness such as selenium or amorphous silicon on the outer peripheral surface of a conductive substrate such as drum-shaped aluminum. An organic photosensitive layer having a predetermined thickness formed by dispersing a charge generating agent and a charge transporting agent in a binder resin is formed on the outer peripheral surface of a conductive substrate such as a drum or drum-like aluminum. An organic photosensitive drum can be applied.

  Further, in the present invention, a photoconductor formed by providing a photoconductive layer on the outer peripheral surface of a cylindrical conductive substrate as an image carrier, and supported rotatably via an image carrier rotation shaft. Various other image carriers such as a photoreceptor belt stretched around a plurality of rollers can be widely applied.

(3-9) Other Embodiment 9
Furthermore, in the first and second embodiments described above, the latent image is supported in a state of being pressed against the image carrier and rotatably via a developer carrier rotation axis parallel to the image carrier rotation axis. The case where the developing roller 80 formed of the semiconductive urethane rubber described above with reference to FIGS. 1 to 9 is applied as the developer carrying member for carrying the developer for developing the toner has been described.

  However, the present invention is not limited to this, and a developing roller formed of a semiconductive elastic body other than the semiconductive urethane rubber, or a plurality of rollers rotatably supported via an image carrier rotating shaft, respectively. Various other developer carriers, such as a stretched semiconductive belt, can be widely applied.

(3-10) Other Embodiment 10
Furthermore, in the first and second embodiments described above, the residual developer removing unit that is arranged to be pressed against the image carrier and removes the developer remaining on the image carrier is shown in FIGS. The case where the drum cleaning blade 76 made of urethane rubber described above is applied has been described.

  However, the present invention is not limited to this, and is formed by an elastic body such as epoxy rubber, acrylic rubber, fluororesin rubber, nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), or polybutadiene rubber. Other drum cleaning blades made of various elastic bodies such as a drum cleaning blade can be widely applied.

(3-11) Other Embodiment 11
Further, in the first and second embodiments described above, the charging roller 75 formed of the semiconductive hydrin rubber described above with reference to FIGS. 1 to 9 is used as a charging unit that charges the image carrier for forming a latent image. , 132 has been described.

  However, the present invention is not limited to this, a charging roller formed of a semiconductive elastic body other than a semiconductive hydrin rubber, a semiconductive belt stretched around a plurality of rollers each rotatably supported, etc. As described above, various other configurations of the charging unit can be widely applied.

(3-12) Other Embodiment 12
Furthermore, in the first and second embodiments described above, the toner blade 82 described above with reference to FIGS. 1 to 9 is used as the developer layer thickness regulating portion that regulates the layer thickness of the developer carried on the developer carrying member. The case where it was made to apply was described.

  However, the present invention is not limited to this, and various other configurations such as a toner blade formed of a semiconductive elastic body to which a DC voltage having a predetermined voltage value can be applied for charging the toner 64. The developer layer thickness regulating part can be widely applied.

(3-13) Other Embodiment 13
Further, in the first and second embodiments described above, the developer carrying range regulating portion that regulates the carrying range of the developer carried on the developer carrying body is made of the sponge described above with reference to FIGS. The case where the left toner seal 83 and the right toner seal 84 are applied has been described.

  However, the present invention is not limited to this, and a wide variety of other developer carrying range restricting portions having various configurations, such as a pair of toner seals made of an elastic body, can be applied.

(3-14) Other Embodiment 14
Furthermore, in the first and second embodiments described above, the displacement driving unit for displacing one of the image carrier and the developer carrier relative to the other in one direction is shown in FIGS. The case where the above-described solenoid 95 is applied has been described.

  However, the present invention is not limited to this, and the displacement levers provided in the first to fourth image forming units 10 to 13 and 122 to 125 so as to be manually operable and the photosensitive drums 35 to 38 are biased for displacement. Various other types of displacement drive units such as a coil drive and a displacement drive unit including an insertable / removable spacer for regulating displacement due to the bias of the coil spring can be widely applied.

(3-15) Other Embodiment 15
Further, in the first and second embodiments described above, one of the image carrier and the developer carrier is unidirectional with respect to the other by operating the displacement driving unit according to the use frequency of the image carrier. The case where the control unit 100 described above with reference to FIG. 1 to FIG.

  However, the present invention is not limited to this, and various other configurations of control units such as a DSP (Digital Signal Processor) and a sequencer can be widely applied.

(3-16) Other Embodiment 16
Furthermore, in the first and second embodiments described above, the unit described above with reference to FIGS. 1 to 9 is used as the image carrier rotation driving unit for rotating the image carrier about the rotation axis of the image carrier. The case where the drive motor 110 and the plurality of unit motor coupling gears are applied has been described.

  However, the present invention is not limited to this, and various other image carrier rotation driving units such as a driving unit including a motor, a pulley, and a belt can be widely applied.

(3-17) Other Embodiment 17
Further, in the first and second embodiments described above, the developer carrier rotating drive unit for rotating the developer carrier around the rotation axis of the developer carrier is shown in FIGS. 1 to 9. The case where the above-described unit drive motor 110 and a plurality of unit motor coupling gears are applied has been described.

  However, the present invention is not limited to this, and a driving unit including a motor dedicated to the developing roller 80 and a plurality of unit motor coupling gears provided separately from the unit driving motor 110, a motor dedicated to the developing roller 80, a pulley, and a belt. As described above, the developer carrying member rotation driving unit having various configurations can be widely applied.

  The present invention relates to an image forming unit that is detachably mounted on an image forming apparatus such as a color electrophotographic printer, monochrome electrophotographic printer, multifunction printer, facsimile machine, and multifunction machine, and the color electrophotographic printer. Or an image forming apparatus such as a monochrome electrophotographic printer, a multifunction printer, a facsimile machine, or a multifunction machine.

  DESCRIPTION OF SYMBOLS 1,120 ... Color printer, 10, 122 ... First image forming unit, 11, 123 ... Second image forming unit, 12, 124 ... Third image forming unit, 13, 125 ... Fourth image forming Units 35 to 38... Photosensitive drum, 37A... Drum rotation shaft, 64. Toner, 65, 130... Unit main body, 70. Toner supply unit, 75, 132... Charging roller, 75A, 132A... Charging roller rotation shaft, 76 .. drum cleaning blade, 80... Development roller, 80A. ...... Supply roller rotating shaft, 82... Toner blade, 83... Left toner seal, 84... Right toner seal, 95. 35 ...... roller storage case, 136 ...... drum storage case.

Claims (9)

An image carrier that is rotatably supported via an image carrier rotation shaft and carries a latent image;
A developer that supports the developer for developing the latent image that is rotatably supported via a developer carrier rotating shaft parallel to the image carrier rotating shaft while being pressed against the image carrier. Comprising a carrier and
The image carrier and the developer carrier are:
An image forming unit provided such that one of the image carrier and the developer carrier is relatively displaceable in one direction parallel to the image carrier rotation axis with respect to the other. A residual developer removing unit arranged to be pressed against the image carrier and removing the developer remaining on the image carrier;
The image carrier and the developer carrier are:
While the image carrier is integrated with the residual developer removing portion, one of the image carrier and the developer carrier is provided so as to be relatively displaceable in the one direction with respect to the other. The image forming unit according to claim 1. A charging unit for charging the image carrier for forming the latent image;
The image carrier and the developer carrier are:
2. The image carrier is provided so that one of the image carrier and the developer carrier can be displaced relative to the other in the one direction while being integrated with the charging unit. Alternatively, the image forming unit according to claim 2. A developer layer thickness regulating part for regulating the layer thickness of the developer carried on the developer carrying body;
The image carrier and the developer carrier are:
While the developer carrier is integrated with the developer layer thickness regulating portion, one of the image carrier and the developer carrier is provided so as to be relatively displaceable in the one direction with respect to the other. The image forming unit according to claim 1, claim 2, or claim 3. A developer carrying range regulating section for regulating the carrying range of the developer carried on the developer carrying body;
The image carrier and the developer carrier are:
While the developer carrying body is integrated with the developer carrying range regulating portion, one of the image carrying body and the developer carrying body is provided so as to be relatively displaceable in the one direction with respect to the other. The image forming unit according to claim 1, claim 2, claim 3, or claim 4. An image forming apparatus comprising the image forming unit according to claim 1, claim 2, claim 3, claim 4, or claim 5. The image forming apparatus according to claim 6, further comprising a displacement driving unit configured to displace one of the image carrier and the developer carrier relative to the other in the one direction. A controller that moves one of the image carrier and the developer carrier relative to the other in the one direction by operating the displacement driving unit according to the frequency of use of the image carrier; An image forming apparatus according to claim 7. An image carrier rotation driving unit for rotating the image carrier about the rotation axis of the image carrier;
A developer carrying member rotation drive unit for rotating the developer carrying member around the developer carrying member rotation axis;
The controller is
The image carrier rotation driving unit is operated to rotate the image carrier about the image carrier rotation axis, and the developer carrier rotation driving unit is operated to operate the developer carrier. One of the image carrier and the developer carrier is moved to the other by operating the displacement drive unit according to the use frequency of the image carrier while rotating around the rotation axis of the developer carrier. The image forming apparatus according to claim 8, wherein the image forming apparatus is relatively displaced in the one direction.

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