JP2011253132A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing power consumption while maintaining high image quality.SOLUTION: The image forming apparatus includes: five photoreceptor drums (2030K, 2030M, 2030Y, 2030C, and 2030T) respectively corresponding to black, cyan, magenta, yellow and transparent colors; an optical scanner 2010A1 for forming each latent image of yellow and cyan; an optical scanner 2010A2 for forming each latent image of black and magenta; an optical scanner 2010T for forming a transparent latent image; and other components. A rotational speed of each polygon mirror in the optical scanner 2010A1 and in the optical scanner 2010A2 is set to be higher than a rotational speed of the polygon mirror in the optical scanner 2010T. The pixel density in a sub-scanning direction of a latent image formed on a photoreceptor drum corresponding to a fundamental color is set to be higher than the pixel density in the sub-scanning direction of a latent image formed on the photoreceptor drum 2030T corresponding to an auxiliary color.

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms a multicolor image.

  In recent years, with the advancement of image forming apparatuses, the demand for image quality has also increased, and electrophotographic image formation with an increased number of colors compared to image forming apparatuses using four basic colors of yellow, magenta, cyan, and black. An apparatus has been proposed (see, for example, Patent Document 1 and Patent Document 2).

  This is obtained by adding a light color toner (for example, light cyan or light yellow) or a highly transparent toner (for example, transparent toner) to four color toners of yellow, magenta, cyan, and black. The four colors of yellow, magenta, cyan, and black are called basic colors, and the other colors are called auxiliary colors.

  The light-colored toner is used to improve the image quality by reducing the graininess of the output image, and the toner with high transparency is used to improve the glossiness.

  In some cases, a color that is difficult to reproduce with a mixed color of yellow, magenta, and cyan is used as an auxiliary color.

  In recent years, from the viewpoint of environmental measures, there has been an increasing demand for low power consumption (energy saving) for image forming apparatuses.

  The image forming apparatuses disclosed in Patent Document 1 and Patent Document 2 have a configuration in which an image forming station corresponding to an auxiliary color is added, and power consumption is increased by the added apparatus.

  The present invention has been made under such circumstances, and an object thereof is to provide an image forming apparatus capable of reducing power consumption while maintaining high image quality.

  The present invention includes a plurality of image carriers corresponding to at least one auxiliary color other than the basic colors of yellow, magenta, cyan, and black and the four colors, and a plurality of light sources corresponding to the plurality of colors. An image forming apparatus including an optical scanning device that forms latent images on the plurality of image carriers, wherein the optical scanning device includes a first optical deflector and a second optical deflector that are driven individually. The first optical deflector deflects at least one of four light beams corresponding to the basic color by rotating a plurality of deflecting reflecting surfaces around a rotation axis, and the second optical deflector. Rotates a plurality of deflecting and reflecting surfaces around a rotation axis to deflect a light beam corresponding to the at least one auxiliary color, and the rotational speed of the deflecting and reflecting surface in the first optical deflector is the second light. Rotational speed of deflecting reflecting surface in deflector An image forming apparatus characterized by faster than.

  According to this, power consumption can be reduced while maintaining high image quality.

1 is a diagram illustrating a schematic configuration of a color printer according to an embodiment of the present invention. It is a figure for demonstrating a mark position detector. FIG. 6 is a diagram (part 1) for explaining an optical scanning device 2010A1. FIG. 6 is a second diagram illustrating the optical scanning device 2010A1. FIG. 10 is a third diagram illustrating the optical scanning device 2010A1. FIG. 6 is a fourth diagram illustrating the optical scanning device 2010A1. It is a figure for demonstrating the light source in optical scanning apparatus 2010A1. It is a figure for demonstrating the surface emitting laser element in FIG. FIG. 6 is a first diagram for explaining an optical scanning device 2010A2. FIG. 6 is a second diagram for explaining the optical scanning device 2010A2. FIG. 10 is a third diagram illustrating the optical scanning device 2010A2. FIG. 6 is a fourth diagram illustrating the optical scanning device 2010A2. FIG. 5 is a first diagram for explaining an optical scanning device 2010T. FIG. 6 is a second diagram illustrating the optical scanning device 2010T. It is a figure for demonstrating the light source in the optical scanning apparatus 2010T. It is a figure for demonstrating the edge-emitting laser element in FIG. It is a flowchart for demonstrating a main scanning position correction process. FIG. 6 is a diagram (part 1) for describing main scanning position correction processing; It is a figure for demonstrating adjustment of a write start timing. FIG. 6 is a (second) diagram for describing main scanning position correction processing; 21A and 21B are diagrams for explaining the exposure time per dot. It is a figure for demonstrating the modification of the optical scanning device 2010T. It is a figure for demonstrating the modification of a color printer.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multicolor printer that forms a full-color image by superimposing four basic colors (black, cyan, magenta, yellow) and a transparent color, and includes three optical scanning devices (2010A1). 2010A2, 2010T), five photosensitive drums (2030K, 2030M, 2030Y, 2030C, 2030T), five drum cleaning devices (2031K, 2031M, 2031C, 2031Y, 2031T), and five charging devices (2032K, 2032M, 2032C). , 2032Y, 2032T), five developing devices (2033K, 2033M, 2033C, 2033Y, 2033T), transfer belt 2040, fixing device 2050, registration roller pair 2056, paper discharge roller 2058, paper feed tray 2060, Paper tray 2070, a communication control unit 2080, a belt cleaning unit 2085, and a like mark position detector 2245 and the printer controller 2090 for totally controlling the above elements.

  The color printer 2000 includes a document reading device and also has a copy function.

  In this specification, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction of each photosensitive drum is described as the Y-axis direction, and the direction along the arrangement direction of the photosensitive drums is described as the X-axis direction.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  A charging device 2032K, a developing device 2033K, and a drum cleaning device 2031K are arranged in the vicinity of the surface of the photosensitive drum 2030K along the rotation direction of the photosensitive drum 2030K.

  The photosensitive drum 2030K, the charging device 2032K, the developing device 2033K, and the drum cleaning device 2031K are used as a set, and constitute an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image.

  Near the surface of the photosensitive drum 2030M, a charging device 2032M, a developing device 2033M, and a drum cleaning device 2031M are arranged along the rotation direction of the photosensitive drum 2030M.

  The photosensitive drum 2030M, the charging device 2032M, the developing device 2033M, and the drum cleaning device 2031M are used as a set, and constitute an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image.

  A charging device 2032Y, a developing device 2033Y, and a drum cleaning device 2031Y are arranged in the vicinity of the surface of the photosensitive drum 2030Y along the rotation direction of the photosensitive drum 2030Y.

  The photosensitive drum 2030Y, the charging device 2032Y, the developing device 2033Y, and the drum cleaning device 2031Y are used as a set, and constitute an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image.

  A charging device 2032C, a developing device 2033C, and a drum cleaning device 2031C are arranged in the vicinity of the surface of the photosensitive drum 2030C along the rotation direction of the photosensitive drum 2030C.

  The photosensitive drum 2030C, the charging device 2032C, the developing device 2033C, and the drum cleaning device 2031C are used as a set, and constitute an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image.

  A charging device 2032T, a developing device 2033T, and a drum cleaning device 2031T are arranged in the vicinity of the surface of the photosensitive drum 2030T along the rotation direction of the photosensitive drum 2030T.

  The photosensitive drum 2030T, the charging device 2032T, the developing device 2033T, and the drum cleaning device 2031T are used as a set, and constitute an image forming station (hereinafter also referred to as “T station” for convenience) that forms a transparent color image. .

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The optical scanning device 2010A1 irradiates the surface of the charged photosensitive drum 2030Y with a light beam modulated based on the yellow image information from the printer control device 2090, and charges the light beam modulated based on the cyan image information. The surface of the photoconductor drum 2030C is irradiated. As a result, on the surfaces of the photoconductor drum 2030Y and the photoconductor drum 2030C, the charge disappears only in the irradiated portions, and latent images corresponding to the image information are formed on the surfaces of the photoconductor drum 2030Y and the photoconductor drum 2030C, respectively. Is done. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum rotates.

  The optical scanning device 2010A2 irradiates the surface of the charged photosensitive drum 2030K with a light beam modulated based on the black image information from the printer control device 2090, and charges the light beam modulated based on the magenta image information. The surface of the photosensitive drum 2030M is irradiated. As a result, on the surfaces of the photosensitive drum 2030K and the photosensitive drum 2030M, the charge is lost only in the portions irradiated with light, and latent images corresponding to the image information are formed on the surfaces of the photosensitive drum 2030K and the photosensitive drum 2030M, respectively. Is done. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum rotates.

  The optical scanning device 2010T irradiates the surface of the charged photosensitive drum 2030T with a light beam modulated based on image information of a color to which a transparent color is added. As a result, on the surface of the photoconductive drum 2030T, the charge disappears only in the irradiated portion, and a latent image corresponding to the image information is formed on the surface of the photoconductive drum 2030T. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum 2030T rotates.

  The configuration of each optical scanning device will be described later.

  Each developing device causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum, and visualizes the latent image. Hereinafter, for the sake of convenience, an image to which toner is attached is referred to as a “toner image”.

  Each toner image moves in the direction of the transfer belt 2040 as the corresponding photosensitive drum rotates. The toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing and are superimposed.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller (not shown) is disposed in the vicinity of the paper feed tray 2060, and the paper feed roller takes out the recording paper one by one from the paper feed tray 2060 and conveys it to the registration roller pair 2056. The registration roller pair 2056 feeds the recording paper toward the gap between the transfer belt 2040 and the transfer roller 2041 at a predetermined timing.

  Then, the toner image superimposed on the transfer belt 2040 is transferred to the recording paper. The recording sheet transferred here is sent to the fixing device 2050.

  In the fixing device 2050, heat and pressure are applied to the recording paper, thereby fixing the toner on the recording paper. The recording paper fixed here is sent to a paper discharge tray 2070 via a paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each drum cleaning device removes and collects toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  The belt cleaning device 2085 removes the toner remaining on the transfer belt 2040 after the toner image is transferred to the recording paper.

  The mark position detector 2245 is disposed near the −X side end of the transfer belt 2040.

  The mark position detector 2245 has three optical sensors (2245a, 2245b, 2245c) as shown in FIG. 2 as an example. The optical sensor 2245a and the optical sensor 2245c are disposed at positions facing both ends in the width direction (Y-axis direction) of the transfer belt 2040. The optical sensor 2245b is disposed at a position facing the vicinity of the center of the transfer belt 2040 in the width direction.

  Each optical sensor has a light source that emits light toward the transfer belt 2040, a light receiving element that receives light reflected by the transfer belt 2040, and the like, and controls the position information of the marks transferred to the transfer belt 2040 by printer control. Notify the device 2090.

  Next, the configuration of the optical scanning device 2010A1 will be described.

  As shown in FIG. 3 to FIG. 6 as an example, the optical scanning device 2010A1 includes two light sources (2200a, 2200b), two coupling lenses (2201a, 2201b), two aperture plates (2202a, 2202b), 2 Two line image forming lenses (2204a, 2204b), polygon mirror 2104A1, two deflector side scanning lenses (2105a, 2105b), two image plane side scanning lenses (2107a, 2107b), four folding mirrors (2106a, 2106b) 2108a, 2108b), two light detection sensors (2205a, 2205b), two condenser lenses (2206a, 2206b), four light detection mirrors (2207a1, 2207a2, 2207b1, 2207b2), and scanning not shown. A control device is provided. These are assembled at predetermined positions of an optical housing (not shown).

  In the following, for convenience, the direction corresponding to the main scanning direction is abbreviated as “main scanning corresponding direction”, and the direction corresponding to the sub scanning direction is abbreviated as “sub scanning corresponding direction”.

  The light source 2200a and the light source 2200b are arranged at positions separated from each other in the X-axis direction when viewed from the Z-axis direction.

  As shown in FIG. 7 as an example, each light source includes a surface emitting laser chip 10, a package member 11 that holds the surface emitting laser chip 10, a cover glass 14 that protects the surface emitting laser chip 10, and a package member 11. A circuit board 12 mounted on the circuit board 12 and a driving chip 13 for driving the surface emitting laser chip 10. In FIG. 7, illustration of bonding wires for electrically connecting the surface emitting laser chip 10 and the package member 11 is omitted.

  As shown in FIG. 8 as an example, the surface emitting laser chip 10 is a surface emitting laser array in which 40 light emitting units arranged two-dimensionally are formed on one substrate. The oscillation wavelength of each light emitting unit is in the 780 nm band.

  The 40 light emitting units are arranged such that the intervals between the light emitting units are equal to d when all the light emitting units are orthogonally projected onto a virtual line extending in the sub-scanning corresponding direction. In this specification, the “light emitting portion interval” refers to the distance between the centers of two light emitting portions.

  The 40 light emitting units are electrically connected to the driving chip 13 via the wiring member of the circuit board 12.

  The coupling lens 2201a is disposed on the optical path of the light beam emitted from the light source 2200a, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201b is disposed on the optical path of the light beam emitted from the light source 2200b, and makes the light beam a substantially parallel light beam.

  Each coupling lens has a refractive index of about 1.5 with respect to a light beam emitted from each light source.

  The aperture plate 2202a has an aperture and shapes the light beam that has passed through the coupling lens 2201a.

  The aperture plate 2202b has an aperture and shapes the light beam that has passed through the coupling lens 2201b.

  Each opening has a rectangular shape with a width in the main scanning correspondence direction of about 5.5 mm and a width in the sub scanning correspondence direction of about 1.18 mm. Each aperture plate is arranged such that the center of the aperture is located at or near the focal position of the coupling lens.

  The line image forming lens 2204a forms an image of the light beam that has passed through the opening of the aperture plate 2202a in the vicinity of the deflection reflection surface of the polygon mirror 2104A1 in the Z-axis direction.

  The line image forming lens 2204b forms an image of the light beam that has passed through the opening of the aperture plate 2202b in the vicinity of the deflection reflection surface of the polygon mirror 2104A1 in the Z-axis direction.

  Each line image forming lens has an anamorphic lens in which the first surface (incident side surface) has refractive power in the sub-scanning corresponding direction and the second surface (exit side surface) has refractive power in the main scanning corresponding direction. It is.

  An optical system including the coupling lens 2201a, the aperture plate 2202a, and the line image forming lens 2204a is a pre-deflector optical system of the Y station.

  An optical system including the coupling lens 2201b, the aperture plate 2202b, and the line image forming lens 2204b is a pre-deflector optical system of the C station.

  The polygon mirror 2104A1 has a four-sided mirror that rotates around an axis parallel to the Z-axis, and each mirror serves as a deflecting / reflecting surface. Here, the radius of the circle inscribed in the tetrahedral mirror is about 7 mm.

  The light beam from the line image forming lens 2204a is deflected to the −X side of the polygon mirror 2104A1, and the light beam from the line image forming lens 2204b is deflected to the + X side of the polygon mirror 2104A1.

  The deflector-side scanning lens 2105a is disposed on the −X side of the polygon mirror 2104A1, and the deflector-side scanning lens 2105b is disposed on the + X side of the polygon mirror 2104A1.

  The folding mirror 2106a and the folding mirror 2108a fold the optical path of the light beam through the deflector-side scanning lens 2105a in the direction toward the photosensitive drum 2030Y.

  The folding mirror 2106b and the folding mirror 2108b fold the optical path of the light beam through the deflector-side scanning lens 2105b in a direction toward the photosensitive drum 2030C.

  The image-side scanning lens 2107a is disposed on the optical path of the light beam via the folding mirror 2108a.

  The image-side scanning lens 2107b is disposed on the optical path of the light beam via the folding mirror 2108b.

  Therefore, the light beam from the line image forming lens 2204a deflected by the polygon mirror 2104A1 is applied to the photosensitive drum 2030Y via the deflector side scanning lens 2105a, the folding mirror 2106a, the folding mirror 2108a, and the image plane side scanning lens 2107a. Irradiation forms a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 2030Y as the polygon mirror 2104A1 rotates. That is, the photoconductor drum 2030Y is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030Y, and the rotational direction of the photosensitive drum 2030Y is the “sub-scanning direction” on the photosensitive drum 2030Y.

  Further, the light beam from the line image forming lens 2204b deflected by the polygon mirror 2104A1 is applied to the photosensitive drum 2030C via the deflector side scanning lens 2105b, the folding mirror 2106b, the folding mirror 2108b, and the image plane side scanning lens 2107b. Irradiation forms a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 2030C as the polygon mirror 2104A1 rotates. That is, the photoconductor drum 2030C is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030C, and the rotational direction of the photosensitive drum 2030C is the “sub-scanning direction” on the photosensitive drum 2030C.

  The folding mirrors are arranged so that the optical path lengths from the polygon mirror 2104A1 to the photosensitive drums coincide with each other, and the incident positions and the incident angles of the light beams on the photosensitive drums are equal to each other. ing.

  The optical system arranged on the optical path between the polygon mirror 2104A1 and each photosensitive drum is also called a scanning optical system. Here, the Y-station scanning optical system is composed of the deflector-side scanning lens 2105a, the two folding mirrors (2106a, 2108a), and the image plane-side scanning lens 2107a. The C-station scanning optical system is composed of the deflector-side scanning lens 2105b, the two folding mirrors (2106b, 2108b), and the image plane-side scanning lens 2107b.

  In the light detection sensor 2205a, a part of the light beam which is deflected by the polygon mirror 2104A1 and passes through the deflector-side scanning lens 2105a before the start of writing is collected with the two light detection mirrors (2207a1, 2207a2). The light enters through the optical lens 2206a.

  In the light detection sensor 2205b, a part of the light beam that is deflected by the polygon mirror 2104A1 and passes through the deflector-side scanning lens 2105b before writing is collected with the two light detection mirrors (2207b1, 2207b2). The light enters through the optical lens 2206b.

  Each of the light detection sensors outputs a signal corresponding to the amount of received light. The scanning control device detects the writing start timing on the corresponding photosensitive drum based on the output signal (synchronization detection signal) of each light detection sensor.

  Next, the configuration of the optical scanning device 2010A2 will be described.

  As shown in FIG. 9 to FIG. 12 as an example, the optical scanning device 2010A2 includes two light sources (2200c and 2200d), two coupling lenses (2201c and 2201d), two aperture plates (2202c and 2202d), and 2 Two line image forming lenses (2204c, 2204d), polygon mirror 2104A2, two deflector side scanning lenses (2105c, 2105d), two image plane side scanning lenses (2107c, 2107d), four folding mirrors (2106c, 2106d) 2108c, 2108d), two light detection sensors (2205c, 2205d), two condenser lenses (2206c, 2206d), four light detection mirrors (2207c1, 2207c2, 2207d1, 2207d2), and scanning not shown. A control device is provided. These are assembled at predetermined positions of an optical housing (not shown).

  The light source 2200c and the light source 2200d are arranged at positions separated from each other in the X-axis direction when viewed from the Z-axis direction.

  Each light source is a light source similar to each light source in the optical scanning device 2010A1 described above.

  The coupling lens 2201c is disposed on the optical path of the light beam emitted from the light source 2200c, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201d is disposed on the optical path of the light beam emitted from the light source 2200d, and makes the light beam a substantially parallel light beam.

  Each coupling lens has a refractive index of about 1.5 with respect to a light beam emitted from each light source.

  The aperture plate 2202c has an aperture and shapes the light beam that has passed through the coupling lens 2201c.

  The aperture plate 2202d has an aperture and shapes the light beam that has passed through the coupling lens 2201d.

  Each opening has a rectangular shape with a width in the main scanning correspondence direction of about 5.5 mm and a width in the sub scanning correspondence direction of about 1.18 mm. Each aperture plate is arranged such that the center of the aperture is located at or near the focal position of the coupling lens.

  The line image forming lens 2204c forms an image of the light beam that has passed through the aperture of the aperture plate 2202c in the vicinity of the deflection reflection surface of the polygon mirror 2104A2 in the Z-axis direction.

  The line image forming lens 2204d forms an image of the light beam that has passed through the opening of the aperture plate 2202d in the vicinity of the deflection reflection surface of the polygon mirror 2104A2 in the Z-axis direction.

  Each line image forming lens has an anamorphic lens in which the first surface (incident side surface) has refractive power in the sub-scanning corresponding direction and the second surface (exit side surface) has refractive power in the main scanning corresponding direction. It is.

  An optical system including the coupling lens 2201c, the aperture plate 2202c, and the line image forming lens 2204c is a pre-deflector optical system of the K station.

  An optical system including the coupling lens 2201d, the aperture plate 2202d, and the line image forming lens 2204d is a pre-deflector optical system of the M station.

  The polygon mirror 2104A2 has a four-sided mirror that rotates around an axis parallel to the Z-axis, and each mirror serves as a deflecting / reflecting surface. Here, the radius of the circle inscribed in the tetrahedral mirror is about 7 mm.

  The light beam from the line image forming lens 2204c is deflected to the −X side of the polygon mirror 2104A2, and the light beam from the line image forming lens 2204d is deflected to the + X side of the polygon mirror 2104A2.

  The deflector-side scanning lens 2105c is disposed on the −X side of the polygon mirror 2104A2, and the deflector-side scanning lens 2105d is disposed on the + X side of the polygon mirror 2104A2.

  The folding mirror 2106c and the folding mirror 2108c fold the optical path of the light beam through the deflector side scanning lens 2105c in the direction toward the photosensitive drum 2030K.

  The folding mirror 2106d and the folding mirror 2108d fold the optical path of the light beam through the deflector-side scanning lens 2105d in a direction toward the photosensitive drum 2030M.

  The image-side scanning lens 2107c is disposed on the optical path of the light beam via the folding mirror 2108c.

  The image plane side scanning lens 2107d is disposed on the optical path of the light beam via the folding mirror 2108d.

  Therefore, the light beam from the line image forming lens 2204c deflected by the polygon mirror 2104A2 is applied to the photosensitive drum 2030K via the deflector side scanning lens 2105c, the folding mirror 2106c, the folding mirror 2108c, and the image plane side scanning lens 2107c. Irradiation forms a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 2030K as the polygon mirror 2104A2 rotates. That is, the photoconductor drum 2030K is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030K, and the rotational direction of the photosensitive drum 2030K is the “sub-scanning direction” on the photosensitive drum 2030K.

  Further, the light beam from the line image forming lens 2204d deflected by the polygon mirror 2104A2 is applied to the photosensitive drum 2030M via the deflector side scanning lens 2105d, the folding mirror 2106d, the folding mirror 2108d, and the image plane side scanning lens 2107d. Irradiation forms a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 2030M as the polygon mirror 2104A2 rotates. That is, the photoconductor drum 2030M is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030M, and the rotational direction of the photosensitive drum 2030M is the “sub-scanning direction” on the photosensitive drum 2030M.

  The folding mirrors are arranged so that the optical path lengths from the polygon mirror 2104A2 to the photosensitive drums coincide with each other, and the incident positions and the incident angles of the light beams on the photosensitive drums are equal to each other. ing.

  The optical system arranged on the optical path between the polygon mirror 2104A2 and each photosensitive drum is also called a scanning optical system. Here, a deflecting side scanning lens 2105c, two folding mirrors (2106c, 2108c), and an image plane side scanning lens 2107c constitute a K station scanning optical system. The M-station scanning optical system is composed of the deflector side scanning lens 2105d, the two folding mirrors (2106d, 2108d), and the image plane side scanning lens 2107d.

  In the light detection sensor 2205c, a part of the light beam which is deflected by the polygon mirror 2104A2 and passes through the deflector-side scanning lens 2105c before the start of writing is collected with the two light detection mirrors (2207c1, 2207c2). The light enters through the optical lens 2206c.

  In the light detection sensor 2205d, a part of the light beam that is deflected by the polygon mirror 2104A2 and passes through the deflector-side scanning lens 2105d before the start of writing is collected with the two light detection mirrors (2207d1, 2207d2). The light enters through the optical lens 2206d.

  Each of the light detection sensors outputs a signal corresponding to the amount of received light. The scanning control device detects the writing start timing on the corresponding photosensitive drum based on the output signal (synchronization detection signal) of each light detection sensor.

  Next, the configuration of the optical scanning device 2010T will be described.

  As shown in FIG. 13 and FIG. 14 as an example, the optical scanning device 2010T includes a light source 2200e, a coupling lens 2201e, an aperture plate 2202e, a line image forming lens 2204e, a polygon mirror 2104T, a deflector-side scanning lens 2105e, an image plane. A side scanning lens 2107e, two folding mirrors (2106e, 2108e), a light detection sensor 2205e, a light detection mirror 2207e, a scanning control device (not shown), and the like are provided. These are assembled at predetermined positions in an optical housing (not shown).

  As shown in FIG. 15 as an example, the light source 2200e includes an edge emitting laser chip 20, a holding member 21 that holds the edge emitting laser chip 20, a substrate 22 to which the holding member 21 is fixed, and an attachment to the substrate 22. And a cap member 23 that protects the edge emitting laser chip 20, a cover glass 24 that is attached to the cap member 23 and transmits a light beam emitted from the edge emitting laser chip 20, and is electrically connected to the edge emitting laser chip 20. A plurality of (herein, 12) lead terminals 25 extending from the substrate 22 are provided.

  The holding member 21 also holds a light receiving element (not shown) for back monitoring.

  The edge-emitting laser chip 20 has ten light emitting units as shown in FIG. 16 as an example. The ten light emitting units are monolithically arranged along a direction inclined with respect to both the main scanning corresponding direction and the sub scanning corresponding direction, and all the light emitting units are orthogonally projected on a virtual line extending in the sub scanning corresponding direction. Are arranged so that the intervals between the light emitting portions are equal.

  Returning to FIG. 13, the coupling lens 2201e is disposed on the optical path of the light beam emitted from the light source 2200e, and makes the light beam a substantially parallel light beam.

  The aperture plate 2202e has an aperture and shapes the light beam that has passed through the coupling lens 2201e. The opening has a rectangular shape with a width in the main scanning correspondence direction of about 5.5 mm and a width in the sub scanning correspondence direction of about 1.18 mm. The aperture plate 2202e is arranged so that the center of the aperture is located at or near the focal position of the coupling lens 2201e.

  The line image forming lens 2204e forms an image of the light flux that has passed through the aperture of the aperture plate 2202e in the vicinity of the deflection reflection surface of the polygon mirror 2104T in the Z-axis direction.

  An optical system including the coupling lens 2201e, the aperture plate 2202e, and the line image forming lens 2204e is a pre-deflector optical system of the T station.

  The polygon mirror 2104T has a four-sided mirror that rotates around an axis parallel to the Z-axis, and each mirror serves as a deflecting / reflecting surface.

  The deflector-side scanning lens 2105e is disposed on the optical path of the light beam deflected by the polygon mirror 2104T.

  The folding mirror 2106e and the folding mirror 2108e fold the optical path of the light beam through the deflector-side scanning lens 2105e in a direction toward the photosensitive drum 2030T.

  The image-side scanning lens 2107e is disposed on the optical path of the light beam via the folding mirror 2108e. The image plane side scanning lens 2107e is a lens having a positive refractive index in the sub-scanning corresponding direction.

  Therefore, the light beam from the line image forming lens 2204e deflected by the polygon mirror 2104T is applied to the photosensitive drum 2030T via the deflector side scanning lens 2105e, the folding mirror 2106e, the folding mirror 2108e, and the image surface side scanning lens 2107e. Irradiation forms a light spot. This light spot moves in the longitudinal direction of the photosensitive drum 2030T as the polygon mirror 2104T rotates. That is, the photosensitive drum 2030T is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030T. The rotation direction of the photosensitive drum 2030T is the “sub-scanning direction” on the photosensitive drum 2030T.

  The T-station scanning optical system is composed of the deflector-side scanning lens 2105e, the two folding mirrors (2106e, 2108e), and the image plane-side scanning lens 2107e.

  The light detection sensor 2205e is deflected by the polygon mirror 2104T, and a part of the light beam before the start of writing out of the light beam passing through the deflector-side scanning lens 2105e enters through the light detection mirror 2207e.

  The light detection sensor 2205e outputs a signal corresponding to the amount of received light. The scanning control device detects the writing start timing on the photosensitive drum 2030T based on the output signal (synchronization detection signal) of the light detection sensor 2205e.

  Hereinafter, when it is not necessary to distinguish between the optical scanning device 2010A1 and the optical scanning device 2010A2, they are collectively referred to as “optical scanning device 2010A” for convenience. When there is no need to distinguish between the polygon mirror 2104A1 and the polygon mirror 2104A2, they are collectively referred to as “polygon mirror 2104A” for convenience.

  In the present embodiment, the rotational speed of the polygon mirror 2104T is made smaller than the rotational speed of the polygon mirror 2104A, and the pixel density in the sub-scanning direction of the latent image drawn on the surface of the photosensitive drum 2030T is lowered.

  The pixel density in the sub-scanning direction of the latent images drawn on the surfaces of the four photosensitive drums corresponding to the basic colors is 4800 dpi.

  By the way, the rotation speed R [rpm] of the polygon mirror can be obtained by the following equation (1).

  Here, D is the pixel density [dpi] in the sub-scanning direction, Ppm is the A4 horizontal conversion printing speed [ppm], N is the number of deflection reflecting surfaces in the polygon mirror, and M is the number of light emitting portions.

  In the optical scanning device 2010A, since D = 4800, Ppm = 80, N = 4, and M = 40, the rotation speed (referred to as Ra) of the polygon mirror 2104A is 24566.9 [rpm].

  In the optical scanning device 2010T, since D = 1200, Ppm = 80, N = 4, and M = 10, the rotational speed (Rt) of the polygon mirror 2104T is 1535.4 [rpm].

  Thus, in the optical scanning device 2010T, the power consumption can be reduced by reducing the number of rotations of the polygon mirror 2104T.

  Here, the ratio between the rotational speed Rt and the rotational speed Ra is an integer ratio of 1:16. Thus, an image can be formed by combining a basic color and an auxiliary color having different pixel densities in the sub-scanning direction with a simple algorithm.

  By the way, if the rotation speed of the polygon mirror is different between the optical scanning device 2010A and the optical scanning device 2010T, the main scanning start position is shifted between the optical scanning device 2010A and the optical scanning device 2010T due to a change with time and variations in component characteristics. Therefore, it is conceivable that a color shift occurs between the basic color and the auxiliary color.

  Therefore, here, a main scanning position correction process is performed. This main scanning position correction processing is performed as (1) one of initialization processes when the color printer 2000 is turned on. (2) When a preset time elapses during image formation, (3) This process is executed when a preset number of images is formed during image formation.

  In the present embodiment, the main scanning position correction process is performed by the printer control device 2090. The flowchart in FIG. 17 corresponds to a series of processing algorithms executed by the printer control device 2090 during the main scanning position correction process.

  In the first step S301, the optical scanning device 2010T is instructed to form an auxiliary color mark (hereinafter referred to as “correction mark”) TPt. Here, correction marks TPt are formed in the vicinity of both end portions in the width direction of the transfer belt 2040 and in the vicinity of the center portion in the width direction of the transfer belt 2040.

  In the next step S303, the optical scanning device 2010A2 is instructed to form a black mark (hereinafter referred to as “reference mark”) TPk. Here, the reference marks TPk are formed in the vicinity of both end portions in the width direction of the transfer belt 2040 and in the vicinity of the center portion in the width direction of the transfer belt 2040.

  In the next step S305, the position of each correction mark and the position of each reference mark in the width direction of the transfer belt 2040 is obtained from the output signal of the mark position detector 2245.

  In the next step S307, the deviation d of the position of the corresponding correction mark with respect to the position of each reference mark is obtained.

  In the next step S309, it is determined whether or not the size (absolute value) of the largest d is equal to or smaller than a preset maximum allowable value D. If the magnitude (absolute value) of the largest d exceeds the maximum allowable value D (see FIG. 18), the determination here is denied and the process proceeds to step S311.

  In step S311, the writing start timing and the writing interval with respect to the photosensitive drum 2030T in the main scanning direction are adjusted according to the magnitude (absolute value) and sign of the deviation d.

  The adjustment of the write start timing is shown in FIG. 19 as an example. The relationship between the deviation d and the write start timing and the write interval adjustment amount is obtained in advance through experiments or the like, and is stored in a memory (not shown) of the printer control device 2090. Then, the main scanning position correction process ends.

  In step S309, if the largest magnitude d (absolute value) is less than or equal to the maximum allowable value D (see FIG. 20), the determination in step S309 is affirmed and the main scanning position correction process is terminated. To do.

  Therefore, it is possible to suppress the color misregistration between the basic color and the auxiliary color due to a change with time and variations in component characteristics.

  In addition, when a difference is made in the rotation speed of the polygon mirror between the optical scanning device 2010A and the optical scanning device 2010T and the light source is controlled with the same pixel clock, the exposure energy is transferred between the photosensitive drum 2030T and another photosensitive drum. Make a difference. As an example, as shown in FIGS. 21A and 21B, in the optical scanning device 2010T in which the polygon mirror rotates slowly, the exposure time per dot becomes longer than that in the optical scanning device 2010A.

  Assuming that the exposure time per dot in the optical scanning device 2010A is t, the exposure time per dot in the optical scanning device 2010T in which the rotation speed of the polygon mirror is ¼ is 4t. The optical energy for forming one dot is P · t in the optical scanning device 2010A, and P · 4t in the optical scanning device 2010T, resulting in a fourfold difference.

  Therefore, in this embodiment, the light output per light beam of the light source in the optical scanning device 2010T is set to ¼ of the light output per light beam of the light source in the optical scanning device 2010A, thereby forming one dot. Energy is almost the same.

  If the light output per beam in the optical scanning device 2010A is different from the light output per beam in the optical scanning device 2010T, the light amount of the light beam directed to the light detection sensor is also different from that in the optical scanning device 2010A. It differs from 2010T. This adversely affects the detection accuracy of the writing start timing and causes a reduction in image quality.

  Therefore, in the optical scanning device 2010T, the light beam received by the light detection sensor is set to the number of mirrors ("Mt") involved between the polygon mirror and the light detection sensor. The light flux received by the detection sensor is less than the number of mirrors (“Ma”) involved between the polygon mirror and the light detection sensor, and the light flux incident on the light detection sensor in the optical scanning device 2010T is reduced. The difference between the light amount and the light amount of the light beam incident on each light detection sensor in the optical scanning device 2010A is reduced. Here, Mt = 1 and Ma = 2.

  For example, assuming that the reflectivity of each mirror is 0.8, in the optical scanning device 2010T, the light beam deflected by the polygon mirror is incident on the light detection sensor with its light amount multiplied by 0.8. On the other hand, in the optical scanning device 2010A, the light beam deflected by the polygon mirror is incident on the light detection sensor after the amount of light is multiplied by 0.64 (= 0.8 × 0.8).

  As is clear from the above description, in the color printer 2000 according to the present embodiment, the polygon mirror 2104A constitutes the first optical deflector in the image forming apparatus of the present invention, and the polygon mirror 2104T constitutes the second optical deflection. The vessel is configured. Further, the three optical sensors (2245a, 2245b, 2245c) constitute a position detector in the image forming apparatus of the present invention.

  Further, the printer control device 2090 constitutes a correction device in the image forming apparatus of the present invention.

  As described above, according to the color printer 2000 according to the present embodiment, the five photosensitive drums (2030K, 2030M, 2030Y, 2030C, and 2030T) corresponding to black, cyan, magenta, yellow, and transparent colors, respectively. , An optical scanning device 2010A1 that forms yellow and cyan latent images, an optical scanning device 2010A2 that forms black and magenta latent images, and an optical scanning device 2010T that forms a transparent latent image. .

  The optical scanning device 2010A1 includes two light sources (2200a, 2200b), two pre-deflector optical systems, a polygon mirror 2104A, two scanning optical systems, two light detection sensors (2205a, 2205b), and the like.

  The optical scanning device 2010A2 includes two light sources (2200c, 2200d), two pre-deflector optical systems, a polygon mirror 2104A2, two scanning optical systems, two light detection sensors (2205c, 2205d), and the like.

  The optical scanning device 2010T includes a light source 2200e, a pre-deflector optical system, a polygon mirror 2104T, a scanning optical system, a light detection sensor 2205e, and the like.

  The rotation speeds of the polygon mirror 2104A1 and the polygon mirror 2104A2 are faster than the rotation speed of the polygon mirror 2104T, and the sub-scan of the latent image formed on the photosensitive drum (2030K, 2030M, 2030Y, 2030C) corresponding to the basic color is performed. The pixel density in the direction is set to be higher than the pixel density in the sub-scanning direction of the latent image formed on the photosensitive drum 2030T corresponding to the auxiliary color.

  In this case, power consumption can be reduced while maintaining high image quality.

  In the above embodiment, the case where the optical scanning device 2010A draws a latent image at a pixel density of 4800 dpi and the optical scanning device 2010T draws a latent image at a pixel density of 1200 dpi in the sub-scanning direction has been described. However, the present invention is not limited thereto. For example, the optical scanning device 2010T may draw a latent image with a pixel density of 600 dpi in the sub-scanning direction. In this case, power consumption can be further reduced. In short, regarding the sub-scanning direction, the pixel density of the latent image drawn by the optical scanning device 2010T only needs to be lower than the pixel density of the latent image drawn by the optical scanning device 2010A.

  In the above embodiment, the number of mirrors (in the above embodiment, only the light detection mirror) in which the light beam received by the light detection sensor is involved between the polygon mirror and the light detection sensor is equal to the optical scanning device. Although the case of two sheets with 2010A and one sheet with optical scanning device 2010T has been described, the present invention is not limited to this. For example, the number of light detection mirrors may be four for the optical scanning device 2010A and two for the optical scanning device 2010T. Alternatively, the number may be three for the optical scanning device 2010A and two for the optical scanning device 2010T. In short, when the reflectance of each light detection mirror is equal, the number of light detection mirrors in the optical scanning device 2010A only needs to be larger than the number of light detection mirrors in the optical scanning device 2010T. Thereby, the reflectance of the reflection optical system between the polygon mirror and the light detection sensor in the optical scanning device 2010A is smaller than the reflectance of the reflection optical system between the polygon mirror and the light detection sensor in the light scanning device 2010T. can do.

  Moreover, although the said embodiment demonstrated the case where the reflectance of each mirror for light detection was equal, it is not limited to this. In short, if the reflectance of the reflection optical system between the polygon mirror and the light detection sensor in the optical scanning device 2010A is smaller than the reflectance of the reflection optical system between the polygon mirror and the light detection sensor in the light scanning device 2010T. good. Thereby, the difference between the light amount of the light beam incident on the light detection sensor in the optical scanning device 2010T and the light amount of the light beam incident on each light detection sensor in the optical scanning device 2010A can be reduced.

  In the above embodiment, the case where the surface emitting laser chip 10 has 40 light emitting units and the end surface emitting laser chip 20 has 10 light emitting units has been described. However, the present invention is not limited to this. The number of light emitting portions of the surface emitting laser chip 10 may be larger than the number of light emitting portions of the edge emitting laser chip 20.

  In the above-described embodiment, a case where a surface emitting laser is used as each light source in the optical scanning device 2010A and an end surface emitting laser is used as a light source in the optical scanning device 2010T has been described, but the present invention is not limited to this. For example, an edge emitting laser may be used for each light source in the optical scanning device 2010A. A surface emitting laser may be used as a light source in the optical scanning device 2010T.

  If an LED array is used as a light source in the optical scanning device 2010T, it is necessary to newly generate a signal for the LED array from basic color image information, and the drive circuit of each light emitting unit becomes complicated and the cost increases. Inconvenience. When the edge emitting laser is used as the light source in the optical scanning device 2010T as in the above embodiment, at least one of the basic color image information can be used as it is, and the driving circuit of each light emitting unit is simplified. can do. For example, when a transparent color is added on black, the black image information can be used as it is.

  Furthermore, when an LED array is used as the light source in the optical scanning device 2010T, there is a disadvantage that it is difficult to adjust the timing of scanning start in the main scanning direction.

  The photosensitive drum on which the optical scanning device 2010A1 draws a latent image and the photosensitive drum on which the optical scanning device 2010A2 draws a latent image are set as appropriate according to the arrangement of the four photosensitive drums corresponding to the basic colors. Can do.

  In the above embodiment, the case where toner images are superimposed in the order of cyan → yellow → magenta → black → transparent color has been described, but the present invention is not limited to this. For example, the toner images may be superimposed in the order of black → yellow → magenta → cyan → transparent color.

  Moreover, although the said embodiment demonstrated the case where the number of the scanning lenses contained in each scanning optical system was two, it is not limited to this. For example, the number of scanning lenses included in each scanning optical system may be one, or three or more.

  In the above embodiment, the case where the mark position detector 2245 includes three optical sensors has been described. However, the present invention is not limited to this. It should be noted that the larger the number of optical sensors, the higher the accuracy of the main scanning position correction can be performed because the positional deviation can be obtained with higher accuracy. Furthermore, the magnification can be corrected.

  In the above embodiment, in order to make the optical energy for forming one dot in the optical scanning device 2010A and the optical scanning device 2010T substantially the same, the optical output per light beam of the optical scanning device 2010T is changed to the optical scanning device. Although the case where the light output per beam of the light source in 2010A is set to ¼ has been described, the present invention is not limited to this. For example, the light energy for forming one dot may be made substantially the same by controlling the light emission time by making the duty of the modulation pulse in the optical scanning device 2010T lower than that of the optical scanning device 2010A.

  As an example, as shown in FIG. 22, in the optical scanning device 2010T, an ND filter 2203e is arranged at the subsequent stage of the coupling lens to adjust the light use efficiency, and the optical energy for forming one dot is changed to the optical scanning device 2010A. And may be approximately equal. In this case, it is desirable that the ND filter is arranged to be inclined with respect to the light beam. This is to prevent return light to the light source and stabilize the light source.

  Moreover, although the said embodiment demonstrated the case where an auxiliary color was a transparent color, it is not limited to this. For example, a light color such as light cyan, light magenta, light yellow, or light black may be used.

  Moreover, although the said embodiment demonstrated the case where the auxiliary color was one color, it is not limited to this. For example, the auxiliary colors may be a plurality of colors including light colors in addition to the transparent color (see FIG. 23). In FIG. 23, as an example, a transparent toner image is formed on the photoreceptor drum 2030T1, and a light toner image is formed on the photoreceptor drum 2030T2.

  Moreover, although the said embodiment demonstrated the case where the light beam which passed the pre-deflector scanning lens injects into a photon detection sensor, it is not limited to this.

  As described above, the image forming apparatus of the present invention is suitable for reducing power consumption while maintaining high image quality.

  DESCRIPTION OF SYMBOLS 10 ... Surface emitting laser chip (surface emitting laser array), 2000 ... Color printer (image forming apparatus), 2010A1, 2010A2, 2010T ... Optical scanning device, 2030C, 2030K, 2030M, 2030T, 2030Y ... Photosensitive drum (image carrier) ), 2033C, 2033K, 2033M, 2033T, 2033Y ... developer, 2090 ... printer controller (corrector), 2104A1, 2104A2 ... polygon mirror (first optical deflector), 2104T ... polygon mirror (second optical deflection) 2200a, 2200b, 2200c, 2200d, 2200e ... light source, 2203e ... ND filter, 2205a, 2205b, 2205c, 2205d, 2205e ... light detection sensor, 2207a1, 2207a2 ... light detection mirror (first optical) ) 2207b1, 2207b2 ... Photodetection mirror (first optical system), 2207c1, 2207c2 ... Photodetection mirror (first optical system), 2207d1, 2207d2 ... Photodetection mirror (first optical system), 2207e... Optical detection mirror (second optical system), 2245a, 2245b, 2245c... Optical sensor (position detector).

JP 2007-171498 A JP 2007-316313 A

Claims (14)

A plurality of image carriers each including a basic color of yellow, magenta, cyan, and black and at least one auxiliary color other than the four colors; and a plurality of light sources corresponding to the plurality of colors. In an image forming apparatus comprising an optical scanning device that forms a latent image on a carrier,
The optical scanning device includes a first optical deflector and a second optical deflector that are individually driven,
The first optical deflector rotates at least one of the four light beams corresponding to the basic color by rotating a plurality of deflecting reflection surfaces around a rotation axis,
The second optical deflector rotates a plurality of deflection reflecting surfaces around a rotation axis to deflect a light beam corresponding to the at least one auxiliary color,
An image forming apparatus, wherein a rotation speed of a deflection reflection surface in the first optical deflector is higher than a rotation speed of a deflection reflection surface in the second optical deflector.   The pixel density in the sub-scanning direction of the image formed on the image carrier corresponding to the basic color is higher than the pixel density in the sub-scanning direction of the image formed on the image carrier corresponding to the auxiliary color. The image forming apparatus according to claim 1.   The ratio of the pixel density in the sub-scanning direction of the image formed on the image carrier corresponding to the basic color and the pixel density in the sub-scanning direction of the image formed on the image carrier corresponding to the auxiliary color is approximately The image forming apparatus according to claim 1, wherein the image forming apparatus is an integer. A developing device for developing each latent image formed on the plurality of image carriers;
At least one position detector for detecting a position in the main scanning direction of the image developed with the auxiliary color and a position in the main scanning direction of the image developed with the basic color;
The correction apparatus which correct | amends the drive condition of the light source corresponding to the said auxiliary | assistant color based on the detection result of the said at least 1 position detector. Image forming apparatus. A light detection sensor that outputs a synchronization detection signal for detecting a writing start timing in the main scanning direction to the image carrier corresponding to the auxiliary color;
The image forming apparatus according to claim 4, wherein the correction device corrects the writing start timing.   6. The image forming apparatus according to claim 4, wherein the at least one position detector is a plurality of position detectors arranged at different positions with respect to the main scanning direction. The plurality of image carriers are scanned with a luminous flux pulse-modulated using the same pixel clock according to the image information of the corresponding color,
7. The image according to claim 1, wherein a duty ratio of a modulation pulse of a light beam corresponding to the basic color is smaller than a duty ratio of a modulation pulse of a light beam corresponding to the auxiliary color. Forming equipment.   The light output of a light source that emits a light beam corresponding to the auxiliary color is smaller than the light output of a light source that emits a light beam corresponding to the basic color. Image forming apparatus.   The image forming apparatus according to claim 1, wherein light use efficiency of a light beam corresponding to the auxiliary color is smaller than light use efficiency of a light beam corresponding to the basic color.   The image forming apparatus according to claim 9, further comprising an ND filter provided on an optical path of a light beam corresponding to the auxiliary color. A plurality of light detection sensors provided corresponding to the plurality of image carriers, each of which outputs a synchronization detection signal for detecting writing start timing in the main scanning direction to the corresponding image carrier;
A first optical system for guiding a light beam polarized by the first optical deflector to a corresponding light detection sensor;
A second optical system for guiding the light beam polarized by the second optical deflector to a corresponding light detection sensor;
The image forming apparatus according to claim 1, wherein the light use efficiency of the first optical system is smaller than the light use efficiency of the second optical system. Each of the optical systems has a reflection optical system,
The image forming apparatus according to claim 11, wherein the number of reflecting surfaces in the first optical system is larger than the number of reflecting surfaces in the second optical system.   The image forming apparatus according to claim 12, wherein the reflectance of the reflective optical system in the first optical system is smaller than the reflectance of the reflective optical system in the second optical system.   Each light source which inject | emits the light beam corresponding to the said basic color is a surface emitting laser array by which the several light emission part is arranged on the same board | substrate, respectively, The Claim 1 characterized by the above-mentioned. The image forming apparatus described.

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