JP5488090B2 - Image forming apparatus - Google Patents

Description

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

  In an image forming apparatus such as a copying machine or a laser printer using an electrophotographic system, image density control is performed in order to always obtain a stable image density. An example of this image density control will be briefly described.

(1) A density detection gradation pattern comprising a plurality of toner patches formed under different image forming conditions (for example, development potential) on an image carrier such as a photoconductor so that the amount of toner adhesion is different from each other. Create

(2) The reflected light from each toner patch is detected using an optical device, and the toner adhesion amount of each toner patch is calculated using the detected value and a predetermined adhesion amount calculation algorithm.

(3) After obtaining the linear equation y = ax + b from the relationship between the toner adhesion amount of each toner patch and the image forming conditions (for example, development potential), development γ (development potential across the development potential) is obtained as an index value indicating development capability. The inclination a) when the axis and the toner adhesion amount are taken as the vertical axis, and the development start voltage Vk (the x intercept b when the development potential is taken as the horizontal axis and the toner adhesion amount is taken as the vertical axis) are obtained.

(4) Based on the obtained development γ and development start voltage Vk, LD power, charging bias, development bias (see, for example, Patent Document 1), etc., so that a development potential corresponding to an appropriate toner adhesion amount is obtained. Adjust the process conditions.

  An optical device that irradiates a toner patch with light and receives reflected light is called a reflective optical sensor. A conventional reflective optical sensor includes one or two light emitting units and one or two light receiving units for receiving reflected light (see, for example, Patent Document 2).

  The spot size of light (detection light) irradiated on the toner patch is usually about 2 mm to 3 mm in diameter.

  The size of the toner patch should ideally be equal to or larger than the size of the detection light spot. However, mechanical fluctuations in the optical scanning area in the electrostatic latent image forming unit, meandering of the transfer belt, displacement of the attachment position of the reflective optical sensor in the main direction, and change over time of the attachment position in the main direction For example, the positional relationship between the toner patch and the reflective optical sensor in the main direction is not necessarily an ideal state.

  Therefore, conventionally, the width of the toner patch in the main direction so that the spot of the detection light is located in the toner pattern in the main direction even if there is a deviation in the positional relationship between the toner patch and the reflective optical sensor in the main direction. Was set to about 15 mm to 25 mm.

  For this reason, there is a disadvantage that a large amount of toner is consumed.

  Further, since the toner density is detected separately from the output of the image to be formed, the original image formation cannot be performed while the toner density is being detected.

  When an electrostatic latent image serving as a toner patch is written by optical scanning, the optical scanning time for writing becomes longer in proportion to the length in the sub-direction of the toner patch row, thereby reducing the work efficiency for original image formation. It was the cause.

  In order to avoid this, a system has been devised in which a plurality of reflective optical sensors and toner patches are arranged in the main direction and the densities of the plurality of toner patches are detected simultaneously (see, for example, Patent Document 3).

  Further, as a new reflective optical sensor capable of reducing the size of the toner patch in the main direction, a sensor in which a light emitting portion and a light receiving portion are arranged in an array has been proposed (for example, see Patent Document 4).

  However, in the image forming apparatus disclosed in Patent Document 3, if density unevenness occurs in the main direction due to the eccentricity of the photosensitive drum or the like, it is difficult to reproduce the ideal color by aligning the density of each color. was there.

  By the way, in order to prevent a reduction in work efficiency for original image formation, a method of arranging a plurality of reflective optical sensors and toner patches disclosed in Patent Document 4 in the main direction is conceivable.

  In this case, although the size of the main direction of the toner patch can be reduced, the size of the main direction of the reflective optical sensor is determined by the difference in the positional relationship between the toner patch and the reflective optical sensor in the main direction. It becomes large so as not to protrude from the reflective optical sensor. Further, the reflection type optical sensor cannot be placed in the main direction so close that the variation in the density in the main direction is negligible, and it is difficult to reproduce the ideal color by adjusting the density of each color.

  The present invention has been made under such circumstances, and an object thereof is to provide an image forming apparatus capable of maintaining high image quality without deteriorating workability.

According to the present invention, in an image forming apparatus that forms an image on a moving body using toner, a test pattern including a plurality of patches having different colors or densities of the toner is arranged in a first direction in which the moving body moves. A test pattern creation device for creating at least one patch on the movable body so that at least two patches are arranged in a second direction perpendicular to each other; and at least one of the second patterns in the second direction with respect to the second direction. An irradiation system including at least three light emitting units arranged at a distance Le smaller than the distance between the centers of the two patches, and at least three light receiving units that receive light emitted from the irradiation system and reflected by the test pattern And the test pattern is located between two light emitting portions at both ends of the at least three light emitting portions with respect to the second direction. At least one of the reflective optical sensor and; a said at least one reflective based on the output signal of the light receiving system of the optical sensor determining the toner concentration information of the plurality of patches individually processing apparatus, the processing apparatus, the In the image forming apparatus, a part or all of the at least three light emitting units are sequentially turned on and off at least once within a time when one patch passes through an irradiation region of light emitted from the irradiation system .

  According to this, high image quality can be maintained without reducing workability.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. It is FIG. (1) for demonstrating schematic structure of an optical scanning device. FIG. 3 is a second diagram for explaining a schematic configuration of the optical scanning device; FIG. 3 is a third diagram for explaining a schematic configuration of the optical scanning device; FIG. 4 is a diagram (part 4) for explaining a schematic configuration of the optical scanning device; It is a figure for demonstrating a toner detector. It is a figure for demonstrating the arrangement position of a reflection type optical sensor. It is FIG. (1) for demonstrating a reflection type optical sensor. It is FIG. (2) for demonstrating a reflection type optical sensor. It is FIG. (3) for demonstrating a reflection type optical sensor. It is FIG. (4) for demonstrating a reflection type optical sensor. It is a figure for demonstrating the light for a detection. FIG. 6 is a diagram for explaining a toner pattern. It is a figure for demonstrating the pattern for density detection. It is a figure for demonstrating a rectangular pattern. It is a figure for demonstrating the light reflected by the transfer belt. It is a figure for demonstrating the light reflected with the rectangular pattern. It is a flowchart for demonstrating the reference | standard light reception amount acquisition process performed by a printer control apparatus. It is a flowchart for demonstrating the detection received light amount acquisition process performed by a printer control apparatus. It is a figure for demonstrating the positional relationship of a reflection type optical sensor and a density | concentration detection pattern. It is a figure for demonstrating the modification 1 of the density | concentration detection pattern. It is a figure for demonstrating the modification 2 of the density | concentration detection pattern. It is a figure for demonstrating the modification 3 of the density | concentration detection pattern. It is a figure for demonstrating the modification 4 of the density | concentration detection pattern. It is a figure for demonstrating the modification 5 of the density | concentration detection pattern. It is a figure for demonstrating the modification 6 of the density | concentration detection pattern. It is a figure for demonstrating the modification 7 of the density | concentration detection pattern. It is a figure for demonstrating the modification 8 of the density | concentration detection pattern. FIG. 6 is a diagram for explaining a toner pattern PL capable of density detection and position detection. FIG. 6 is a diagram for explaining a positional relationship between a reflective optical sensor and a toner pattern PL. It is FIG. (1) for demonstrating a position detection process. It is FIG. (2) for demonstrating a position detection process. FIG. 33A and FIG. 33B are diagrams (No. 3) for explaining the position detection process, respectively. FIG. 9 is a diagram for explaining a first modification of the toner pattern PL. FIG. 10 is a diagram for explaining a second modification of the toner pattern PL. It is a figure for demonstrating schematic structure of the laser printer which forms a monochrome image.

  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 as an image forming apparatus according to an embodiment.

  The color printer 2000 is a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes an optical scanning device 2010, four photosensitive drums (2030a, 2030b, 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), four charging devices (2032a, 2032b, 2032c, 2032d), four developing rollers (2033a, 2033b, 2033c, 2033d), 4 Toner cartridges (2034a, 2034b, 2034c, 2034d), transfer belt 2040, transfer roller 2042, fixing roller 2050, paper feed roller 2054, registration roller pair 2056, paper discharge roller 2058, paper feed tray 060, paper ejection tray 2070, a communication control device 2080, and a like toner detector 2245 and the printer controller 2090 for totally controlling the above elements.

  Here, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction of each photoconductor drum is described as the Y-axis direction, and the direction along the arrangement direction of the four photoconductor 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 and an information device (for example, a facsimile device) via a public line. Then, the communication control device 2080 notifies the received information to the printer control device 2090.

  The printer control device 2090 controls each unit in response to requests from the host device and the information device, and sends image information from the host device and the information device to the optical scanning device 2010.

  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 2032a, a developing roller 2033a, and a cleaning unit 2031a are disposed in the vicinity of the surface of the photosensitive drum 2030a along the rotation direction of the photosensitive drum 2030a.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, and the cleaning unit 2031a are used as a set and form an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image. Configure.

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

  The photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, the toner cartridge 2034b, and the cleaning unit 2031b are used as a set and form an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image. Configure.

  A charging device 2032c, a developing roller 2033c, and a cleaning unit 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 roller 2033c, the toner cartridge 2034c, and the cleaning unit 2031c are used as a set, and form an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image. Configure.

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

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, the toner cartridge 2034d, and the cleaning unit 2031d are used as a set, and form an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image. Configure.

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

  Based on the multicolor image information (black image information, cyan image information, magenta image information, yellow image information) from the higher-level device, the optical scanning device 2010 charges the light flux modulated for each color correspondingly. Irradiate each surface of the photosensitive drum. As a result, on the surface of each photoconductive drum, the charge disappears only in the portion irradiated with light, and a latent image corresponding to the image information is formed on the surface of each photoconductive drum. The latent image formed here moves in the direction of the corresponding developing roller as the photosensitive drum rotates. The configuration of the optical scanning device 2010 will be described later.

  The toner cartridge 2034a stores black toner, and the toner is supplied to the developing roller 2033a. The toner cartridge 2034b stores cyan toner, and the toner is supplied to the developing roller 2033b. The toner cartridge 2034c stores magenta toner, and the toner is supplied to the developing roller 2033c. The toner cartridge 2034d stores yellow toner, and the toner is supplied to the developing roller 2033d.

  As each developing roller rotates, the toner from the corresponding toner cartridge is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (toner image) moves in the direction of the transfer belt 2040 as the photosensitive drum rotates.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing, and are superimposed to form a color image. By the way, the direction in which the toner image moves on the transfer belt 2040 is called a “sub-direction”, and the direction orthogonal to the sub-direction (here, the Y-axis direction) is called a “main direction”.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060, and the paper feed roller 2054 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 2042 at a predetermined timing. As a result, the color image on the transfer belt 2040 is transferred to the recording paper. The recording sheet transferred here is sent to the fixing roller 2050.

  In the fixing roller 2050, heat and pressure are applied to the recording paper, whereby the toner is fixed 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 cleaning unit removes 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 toner detector 2245 is disposed on the + Z side of the transfer belt 2040 and in the vicinity of the + X side end of the transfer belt 2040. The toner detector 2245 will be described later.

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

  2 to 5 as an example, the optical scanning device 2010 includes four light sources (2200a, 2200b, 2200c, 2200d), four coupling lenses (2201a, 2201b, 2201c, 2201d), four openings. Plate (2202a, 2202b, 2202c, 2202d), four cylindrical lenses (2204a, 2204b, 2204c, 2204d), polygon mirror 2104, four fθ lenses (2105a, 2105b, 2105c, 2105d), eight folding mirrors (2106a, 2106b, 2106c, 2106d, 2108a, 2108b, 2108c, 2108d), 4 toroidal lenses (2107a, 2107b, 2107c, 2107d), 4 light detection sensors (2205a, 2205b) 2205c, 2205d), 4 single light detection mirror (2207a, includes 2207b, 2207c, 2207d), and the like scanning control device (not shown). These are assembled at predetermined positions of the optical housing 2300 (not shown in FIGS. 2 to 4, see FIG. 5).

  Further, the direction along the optical axis of the coupling lens 2201a and the coupling lens 2201b is referred to as “w1 direction”, and the direction along the optical axis of the coupling lens 2201c and the coupling lens 2201d is referred to as “w2 direction”. Furthermore, a direction orthogonal to both the Z-axis direction and the w1 direction is referred to as “m1 direction”, and a direction orthogonal to both the Z-axis direction and the w2 direction is referred to as “m2 direction”.

  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”.

  Here, the main scanning corresponding direction in the light sources 2200a and 2200b is the m1 direction, and the main scanning corresponding direction in the light sources 2200c and 2200d is the “m2 direction”. The sub-scanning corresponding direction in the light sources 2200a and 2200b and the sub-scanning corresponding direction in the light sources 2200c and 2200d are both the same direction as the Z-axis direction.

  The light source 2200b and the light source 2200c are disposed at positions separated from each other in the X-axis direction. The light source 2200a is disposed on the −Z side of the light source 2200b. The light source 2200d is arranged on the −Z side of the light source 2200c.

  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.

  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.

  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.

  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.

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

  The cylindrical 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 2104 in the Z-axis direction.

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

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

  The polygon mirror 2104 has a four-stage mirror having a two-stage structure, and each mirror serves as a deflection reflection surface. The light beam from the cylindrical lens 2204a and the light beam from the cylindrical lens 2204d are deflected by the first-stage (lower) tetrahedral mirror, respectively, and the light beam from the cylindrical lens 2204b and the cylindrical light are deflected by the second-stage (upper) tetrahedral mirror. It arrange | positions so that the light beam from the lens 2204c may be deflected, respectively. Note that the first-stage tetrahedral mirror and the second-stage tetrahedral mirror rotate with a phase shift of 45 °, and writing scanning is alternately performed in the first and second stages.

  Here, the light beams from the cylindrical lens 2204 a and the cylindrical lens 2204 b are deflected to the −X side of the polygon mirror 2104, and the light beams from the cylindrical lens 2204 c and the cylindrical lens 2204 d are deflected to the + X side of the polygon mirror 2104.

  Each fθ lens has a non-arc surface shape having such a power that the light spot moves at a constant speed in the main scanning direction on the surface of the corresponding photosensitive drum as the polygon mirror 2104 rotates.

  The fθ lens 2105a and the fθ lens 2105b are disposed on the −X side of the polygon mirror 2104, and the fθ lens 2105c and the fθ lens 2105d are disposed on the + X side of the polygon mirror 2104.

  The fθ lens 2105a and the fθ lens 2105b are stacked in the Z-axis direction, the fθ lens 2105a is opposed to the first-stage tetrahedral mirror, and the fθ lens 2105b is opposed to the second-stage tetrahedral mirror. Further, the fθ lens 2105c and the fθ lens 2105d are stacked in the Z-axis direction, the fθ lens 2105c is opposed to the second-stage tetrahedral mirror, and the fθ lens 2105d is opposed to the first-stage tetrahedral mirror.

  Therefore, the light beam from the cylindrical lens 2204a deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030a through the fθ lens 2105a, the folding mirror 2106a, the toroidal lens 2107a, and the folding mirror 2108a, thereby forming a light spot. The This light spot moves in the longitudinal direction of the photosensitive drum 2030a as the polygon mirror 2104 rotates. That is, the photosensitive drum 2030a is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030a, and the rotational direction of the photosensitive drum 2030a is the “sub-scanning direction” on the photosensitive drum 2030a.

  The light beam from the cylindrical lens 2204b deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030b through the fθ lens 2105b, the folding mirror 2106b, the toroidal lens 2107b, and the folding mirror 2108b, and a light spot is formed. The This light spot moves in the longitudinal direction of the photosensitive drum 2030b as the polygon mirror 2104 rotates. That is, the photosensitive drum 2030b is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030b, and the rotational direction of the photosensitive drum 2030b is the “sub-scanning direction” on the photosensitive drum 2030b.

  The light beam from the cylindrical lens 2204c deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030c through the fθ lens 2105c, the folding mirror 2106c, the toroidal lens 2107c, and the folding mirror 2108c, and a light spot is formed. The This light spot moves in the longitudinal direction of the photosensitive drum 2030c as the polygon mirror 2104 rotates. That is, the photosensitive 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 light beam from the cylindrical lens 2204d deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030d through the fθ lens 2105d, the folding mirror 2106d, the toroidal lens 2107d, and the folding mirror 2108d, and a light spot is formed. The This light spot moves in the longitudinal direction of the photosensitive drum 2030d as the polygon mirror 2104 rotates. That is, the photosensitive drum 2030d is scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030d, and the rotational direction of the photosensitive drum 2030d is the “sub-scanning direction” on the photosensitive drum 2030d.

  Incidentally, a scanning area in the main scanning direction in which image information is written on each photosensitive drum is called an “effective scanning area”, an “image forming area”, or an “effective image area”.

  Each folding mirror is arranged so that the optical path lengths from the polygon mirror 2104 to each photosensitive drum coincide with each other, and the incident position and the incident angle of the light flux on each photosensitive drum are equal to each other. ing.

  Further, the cylindrical lens and the corresponding toroidal lens constitute a surface tilt correction optical system in which the deflection point and the corresponding photosensitive drum surface are conjugated in the sub-scanning direction.

  An optical system disposed on the optical path between the polygon mirror 2104 and each photosensitive drum is also called a scanning optical system. In this embodiment, a scanning optical system of the K station is configured by the fθ lens 2105a, the toroidal lens 2107a, and the folding mirrors (2106a and 2108a). Further, the scanning optical system of the C station is composed of the fθ lens 2105b, the toroidal lens 2107b, and the folding mirrors (2106b, 2108b). The f-theta lens 2105c, the toroidal lens 2107c, and the folding mirrors (2106c, 2108c) constitute the M station scanning optical system. Further, a scanning optical system of the Y station is configured by the fθ lens 2105d, the toroidal lens 2107d, and the folding mirrors (2106d and 2108d).

  A part of the light beam before the start of writing out of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the K station enters the light detection sensor 2205a via the light detection mirror 2207a.

  The light detection sensor 2205b is deflected by the polygon mirror 2104, and a part of the light beam before starting writing out of the light beam via the scanning optical system of the C station enters through the light detection mirror 2207b.

  The light detection sensor 2205c is deflected by the polygon mirror 2104, and a part of the light beam before starting writing out of the light beam via the scanning optical system of the M station enters through the light detection mirror 2207c.

  A part of the light beam before the start of writing out of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the Y station enters the light detection sensor 2205d via the light detection mirror 2207d.

  Each of the light detection sensors outputs a signal (photoelectric conversion signal) corresponding to the amount of received light.

  The scanning control device detects the scanning start timing on the corresponding photosensitive drum based on the output signal of each light detection sensor.

  Next, the toner detector 2245 will be described.

  As shown in FIG. 6 as an example, the toner detector 2245 includes three reflective optical sensors (2245a, 2245b, 2245c).

  As an example, as shown in FIG. 7, the reflective optical sensor 2245 a is disposed in the vicinity of the + Y side end of the transfer belt 2040, and the reflective optical sensor 2245 c is the −Y side end of the transfer belt 2040. It is arranged in the vicinity. The reflective optical sensor 2245c is disposed at an intermediate position between the reflective optical sensor 2245a and the reflective optical sensor 2245c with respect to the main direction.

  Here, regarding the main direction (Y-axis direction), the center position of the reflective optical sensor 2245a is Y1, the center position of the reflective optical sensor 2245b is Y2, and the center position of the reflective optical sensor 2245c is Y3.

  A toner pattern as a test pattern is formed at a position corresponding to each reflective optical sensor.

  The three reflective optical sensors (2245a, 2245b, 2245c) all have the same configuration and the same structure. Therefore, hereinafter, the configuration and structure of the reflective optical sensor will be described using the reflective optical sensor 2245a as a representative.

  As shown in FIGS. 8 to 11, the reflective optical sensor 2245a is an illumination system including 12 light emitting units (E1 to E12) and illumination including 12 illumination microlenses (LE1 to LE12). An optical system, a light receiving optical system including twelve light receiving microlenses (LD1 to LD12), a light receiving system including twelve light receiving units (D1 to D12), a processing device (not shown), and the like are provided.

  Here, L3 in FIG. 8 is 1.5 mm, and L4 is 5 mm.

  The twelve light emitting units (E1 to E12) are arranged at equal intervals Le along the main direction. Each light emitting portion has a square shape with a side of 40 μm. For each light emitting unit, an LED (Light Emitting Diode) can be used. Here, as an example, Le = 0.4 mm. In this case, with respect to the main direction, the distance between E1 and E12 is 4.4 mm (Le × 11). In the following, for convenience, the lit light emitting unit is abbreviated as “lit light emitting unit”.

  The twelve illumination microlenses (LE1 to LE12) individually correspond to the twelve light emitting units (E1 to E12).

  Each illumination microlens condenses and guides the light beam emitted from the corresponding light emitting unit toward the surface of the transfer belt 2040. In each illumination microlens, the lens diameter, the radius of curvature of the lens, and the lens thickness are the same. The optical axis of each illumination microlens is parallel to the direction orthogonal to the light emitting surface of the corresponding light emitting unit.

  Here, for ease of explanation, it is assumed that only the light beam emitted from each light emitting unit and passing through the corresponding illumination microlens irradiates the transfer belt 2040 as detection light (S1 to S12) (FIG. 12). reference). Then, the center of the light spot (hereinafter abbreviated as “detection light spot” for convenience) formed on the surface of the transfer belt 2040 by each detection light is the center of the corresponding light emitting unit and light receiving unit with respect to the sub-direction. Near the middle.

  As an example, the size of each detection light spot is 0.4 mm in diameter. This value is equal to the arrangement pitch Le of the 12 light emitting units. The size of the conventional detection light spot is usually about 2 to 3 mm in diameter.

  Here, the surface of the transfer belt 2040 is smooth, and most of the detection light irradiated on the surface of the transfer belt 2040 is regularly reflected.

  The twelve light receiving portions (D1 to D12) individually correspond to the light emitting portions (E1 to E12), respectively. Each light receiving portion has a circular shape with a diameter of 300 μm.

  Each light receiving portion is disposed on the optical path of a light beam emitted from the corresponding light emitting portion and regularly reflected by the surface of the transfer belt 2040. The arrangement pitch of the twelve light receiving parts is equal to the arrangement pitch Le of the twelve light emitting parts.

  A PD (photodiode) can be used for each light receiving portion. Each light receiving unit outputs a signal corresponding to the amount of received light.

  The twelve light receiving microlenses (LD1 to LD12) are individually provided for the twelve light receiving portions (D1 to D12), and collect the detection light reflected by the transfer belt 2040 or the toner pattern. In this case, the amount of light received by each light receiving unit can be increased. That is, detection sensitivity can be improved. In each light receiving microlens, the lens diameter, the radius of curvature of the lens, and the lens thickness are the same.

  For each microlens, a spherical lens having a condensing function in the main direction and the sub direction, a cylindrical lens having a positive power in the sub direction, an anamorphic lens in which the power in the main direction and the power in the sub direction are different from each other are used. be able to.

  Here, as an example, each microlens is a spherical lens. In each illumination microlens, the incident-side optical surface has condensing power, and the exit-side optical surface does not have condensing power. In each light receiving microlens, the exit-side optical surface has a condensing power, and the incident-side optical surface does not have a condensing power.

  The twelve illumination microlenses (LE1 to LE12) and the twelve light receiving microlenses (LD1 to LD12) are integrated to form a microlens array. Thereby, workability | operativity at the time of assembling | attaching each microlens to a reflection type optical sensor can be improved. Moreover, the positional accuracy between the lens surfaces in a plurality of microlenses can be increased. Each lens surface can be formed on a glass substrate or a resin substrate by using a processing method such as photolithography or molding.

  Hereinafter, when it is not necessary to specify the light emitting unit, the light emitting unit Ei is displayed. And the illumination microlens corresponding to the light emission part Ei is displayed as the illumination microlens LEi. The light beam emitted from the light emitting unit Ei and passing through the illumination microlens LEi is displayed as detection light Si. The light receiving unit corresponding to the light emitting unit Ei is displayed as the light receiving unit Di. Further, the light receiving microlens corresponding to the light receiving portion Di is displayed as a light receiving microlens LDi.

  Next, a toner pattern as the test pattern will be described.

  Here, as an example, as shown in FIG. 13, the toner pattern formed in the vicinity of the + Y side end portion of the transfer belt 2040 is formed at Patt A and the central portion of the transfer belt 2040 in the main direction (Y-axis direction). The toner pattern is PattB, and the toner pattern formed near the −Y side end of the transfer belt 2040 is PattC.

  Each toner pattern is a density detection pattern. As shown in FIG. 14 as an example, each toner pattern has four types of patterns (DP1, DP2, DP3, DP4).

  The density detection pattern DP1 is formed of yellow toner, and the density detection pattern DP2 is formed of magenta toner. The density detection pattern DP3 is formed of cyan toner, and the density detection pattern DP4 is formed of black toner.

  Here, the density detection pattern DP2 is arranged on the −Y side of the density detection pattern DP1, the density detection pattern DP3 is arranged on the −Y side of the density detection pattern DP2, and the −Y side of the density detection pattern DP3. The density detection pattern DP4 is disposed in the area. Hereinafter, when it is not necessary to distinguish between the density detection patterns DP1 to DP4, they are also collectively referred to as “density detection patterns DP”.

  As shown in FIG. 15 as an example, each density detection pattern has four square patterns (p1 to p4, hereinafter referred to as “rectangular pattern” for convenience). Each rectangular pattern is arranged in a line along the sub-direction, and the gradation of the toner density differs when viewed as a whole. Here, p1, p2, p3, and p4 are set from a rectangular pattern having a low toner density. That is, the rectangular pattern p1 has the lowest toner density, and the rectangular pattern p4 has the highest toner density.

  Each rectangular pattern has the same shape, and the length L1 in the Y-axis direction is 450 μm. That is, L1 is set to be larger than the interval Le. Further, with respect to the Y-axis direction, the center-to-center distance L2 between two rectangular patterns adjacent to each other is 800 μm.

  In this case, with respect to the main direction, the distance between the light emitting part E1 and the light emitting part E12 is 4.4 mm (Le × 11), and is 2.85 mm (L2) which is the length of the region including the four rectangular patterns. Longer than x3 + L1). Thereby, it can prevent that the light for a detection is not irradiated to a rectangular pattern. In addition, regarding the main direction, the length of the region including a plurality of light emitting portions is determined by taking into account the margin of misalignment in the main direction of the transfer belt and the misalignment in the main direction when the rectangular pattern is formed. You may make it longer than the length of the area | region containing several rectangular patterns arranged in the main direction. Thereby, the magnitude | size of the main direction of a reflection type optical sensor can be set without excess and deficiency.

  Conventionally, the rectangular patterns are arranged in a line along the sub direction, and the size thereof is about 10 mm in the main direction and about 15 mm in the sub direction. Therefore, in the present embodiment, the overall size of the toner pattern can be made smaller than before. As a result, it is possible to reduce the influence on the rectangular pattern (particularly uneven density in the sub direction) when the characteristics of the members related to development and transfer change.

  The gradation of the toner density can be changed by adjusting the power of the light beam emitted from the light source, adjusting the duty of the driving pulse supplied to the light source, and adjusting the charging bias and the developing bias. In addition, the gradation of the toner density can be changed by changing the area ratio of the halftone dots.

  By the way, the surface of the transfer belt 2040 is smooth, and most of the detection light irradiated on the surface of the transfer belt 2040 is specularly reflected (see FIG. 16), but the detection light irradiated on the surface of the rectangular pattern is Regular reflection and diffuse reflection are performed (see FIG. 17). Hereinafter, for the sake of convenience, the specularly reflected light is also referred to as “regularly reflected light” and the diffusely reflected light is also referred to as “diffuse reflected light”.

  Next, density detection processing performed using the toner detector 2245 will be described. This density detection process is performed at every predetermined timing and at the request of the operator.

  For example, (1) immediately after turning on the power, (2) when the photosensitive drum stop time is 6 hours or more, (3) when the temperature in the apparatus changes by 10 ° C. or more, and (4) relative in the apparatus. The concentration detection process is executed when the use environment changes, such as when the humidity changes by 50% or more.

  During printing, (A) when the number of prints reaches a predetermined number, (B) when the number of rotations of the developing roller reaches a predetermined number, (C) the traveling distance of the transfer belt becomes a predetermined distance. Density detection processing is executed when it is expected that the characteristics of the members related to development and transfer have changed, such as when it has been reached.

  In the present embodiment, the density detection process is performed by the printer control device 2090. Hereinafter, density detection processing performed by the printer control apparatus 2090 will be described.

1. First, the printer control device 2090 instructs the scanning control device to form a density detection pattern.

  Then, the scanning control device controls the Y station so that the density detection pattern DP1 is formed at the position Y1, the position Y2, and the position Y3 on the photosensitive drum 2030d.

  Further, the scanning control device controls the M station so that the density detection pattern DP2 is formed at the position Y1, the position Y2, and the position Y3 on the photosensitive drum 2030c.

  Further, the scanning control device controls the C station so that the density detection pattern DP3 is formed at the position Y1, the position Y2, and the position Y3 on the photosensitive drum 2030b.

  Further, the scanning control device controls the K station so that the density detection pattern DP4 is formed at the position Y1, the position Y2, and the position Y3 on the photosensitive drum 2030a.

  The density detection pattern formed by each station is transferred to the transfer belt 2040 at a predetermined timing.

  As a result, PattA is formed at the position Y1 on the transfer belt 2040, PattB is formed at the position Y2, and PattC is formed at the position Y3.

2. Next, the printer control device 2090 irradiates the transfer belt 2040 with detection light and acquires the “reference received light amount”. The process of acquiring the reference received light amount (hereinafter referred to as “reference received light amount acquisition process”) will be described with reference to the flowchart of FIG. This flowchart corresponds to a series of processing algorithms executed by the printer control apparatus 2090. This reference received light amount acquisition process is performed before the first rectangular pattern is conveyed in front of the reflective optical sensor.

  In the first step S401, an initial value 1 is set to a variable i for specifying a light emitting unit.

  In the next step S403, the light emitting unit Ei is turned on.

  In the next step S405, the output signal of each light receiving unit is acquired.

  In the next step S407, for each light receiving unit, the received light amount is obtained from the acquired output signal and is set as a “reference received light amount”, which is stored in a memory (not shown) in association with the light emitting unit Ei.

  In the next step S409, the light emitting unit Ei is turned off.

  In the next step S411, the value of the variable i is incremented by one.

  In the next step S413, it is determined whether or not the value of the variable i exceeds the number of light emitting units (11 in the present embodiment). Here, since i = 1, the determination here is denied and the process returns to step S403.

  Thereafter, the processes in steps S403 to S413 are repeated until the determination in step S413 is affirmed.

  When the value of the variable i exceeds the number of light emitting units, the determination in step S413 is affirmed, and the process for obtaining the reference light reception amount is terminated.

3. Next, the printer control apparatus 2090 irradiates each rectangular pattern with detection light to obtain “detected light reception amount”. The process for acquiring the detected light reception amount (hereinafter referred to as “detected light reception amount acquisition process”) will be described with reference to the flowchart of FIG. This flowchart corresponds to a series of processing algorithms executed by the printer control apparatus 2090. An example of the positional relationship between the reflective optical sensor and the toner pattern is shown in FIG.

  In the first step S501, a counter k indicating the number of times the received light amount of the light receiving unit is stored during one cycle of turning on / off, a variable j indicating the number of times the received light amount of the light receiving unit is stored in the previous cycle, and detection The initial value “0” is set in the counter c indicating the number of rectangular patterns in the sub direction.

  In the next step S503, an initial value 1 is set to a variable i for specifying a light emitting unit.

  In the next step S505, the light emitting unit Ei is turned on.

  In the next step S507, the output signal of each light receiving unit is acquired.

  In the next step S509, the output signal of the light receiving unit Di is referred to and it is determined whether or not the signal level is equal to or lower than a preset threshold level. The threshold level is slightly lower than the signal level output from the light receiving unit Di that has received the regular reflection light when the detection light Si illuminates the transfer belt 2040. At this time, if the signal level of the light receiving unit Di is not less than or equal to the threshold level, the determination here is denied and the process proceeds to step S515. On the other hand, if the signal level of the light receiving unit Di is equal to or lower than the threshold level, the determination here is affirmed and the process proceeds to step S511.

  In step S511, the output of each light receiving unit acquired in step S507 is stored.

  In the next step S513, the value of the counter k is incremented by one.

  In the next step S515, the light emitting unit Ei is turned off.

  In the next step S517, the value of the variable i is incremented by one.

  In the next step S519, it is determined whether or not the value of the variable i exceeds the number of light emitting units (11 in the present embodiment). Here, since i = 1, the determination here is denied and the process returns to step S505.

  If the value of the variable i exceeds the number of light emitting units, it is determined that light emission has been completed and the determination in step S519 is affirmed, and the process proceeds to step S521.

  In this step S521, it is determined whether or not j = 0 and k> j by referring to the values of the variable j and the counter k. If j = 0 and k> j is not satisfied, it is determined that the group of rectangular patterns arranged in the main direction has not yet been passed, and the process proceeds to step S525. On the other hand, if j = 0 and k> j, it is determined that the group of rectangular patterns arranged in the main direction has passed, and the determination here is affirmed, and the process proceeds to step S523.

  In step S523, the counter c is incremented by one.

  In the next step S525, the value of the counter k is substituted into the variable j.

  In the next step S527, "0" is set to the counter k.

  In the next step S529, the values of the variable j, the counter k, and the counter c are referred to, and it is determined whether j = 0, k = 0, and c is larger than the number of rectangular patterns in the sub direction. If the determination is negative, it is determined that an undetected rectangular pattern remains, and the process returns to step S503. On the other hand, if the determination here is affirmed, it is determined that the detection of all rectangular patterns has been completed, and the detected received light amount acquisition process is terminated.

  The received light amount information obtained as described above is classified into information for each rectangular pattern, and an average is obtained for each, and the toner density for each rectangular pattern can be calculated from these. The separation of the information for each rectangular pattern can be easily performed from the arrangement information of the rectangular pattern determined in advance and the distribution information of the acquired light reception amount. In addition, after sorting into information for each rectangular pattern, a process for removing a value that seems to be an abnormal value may be added. Thereby, detection accuracy can be further improved.

4). Next, the printer control device 2090 refers to the reference light reception amount, converts the detected light reception amount of each light receiving unit into a light reception amount by diffuse reflection light and a light reception amount by regular reflection light for each rectangular pattern and for each rectangular pattern. To separate.

5. Next, the printer controller 2090 obtains the total value of the amount of light received by the specularly reflected light and the total value of the amount of received light by the diffusely reflected light for each color of the toner and for each rectangular pattern.

6). Next, the printer controller 2090 determines the toner density based on at least one of the total value of the received light amount by the specularly reflected light and the total value of the received light amount by the diffusely reflected light for each toner color and for each rectangular pattern. Ask.

7). Finally, the printer control device 2090 corrects the image forming conditions based on the obtained toner density.

  For example, depending on the toner density deviation amount, the power of the light beam emitted from the light source, the duty in the drive pulse supplied to the light source, the charging bias, and the developing bias in the corresponding image forming station (see, for example, Patent Document 1) , And / or image data (dither pattern).

  As is clear from the above description, in the color printer 2000 according to the present embodiment, the reflective optical sensor 2245a, the reflective optical sensor 2245b, and the reflective optical sensor 2245c provide the reflective optical sensor in the image forming apparatus of the present invention. It is configured.

  The printer control device 2090 constitutes a processing device, an adjustment device, and a monitoring 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 four photosensitive drums (2030a, 2030b, 2030c, 2030d) and the luminous flux modulated according to the image information with respect to each photosensitive drum. An optical scanning device that scans in the main scanning direction to form a latent image, four developing rollers (2033a, 2033b, 2033c, and 2033d) that attach toner to the latent image to generate a toner image, and transfer the toner image to the transfer belt 2040 A transfer roller 2042 for transferring the toner image, a toner detector 2245 for detecting the density of the toner pattern transferred to the transfer belt 2040, and a printer control device 2090 for overall control.

  The toner detector 2245 has three reflective optical sensors (2245a, 2245b, 2245c).

  Each reflective optical sensor includes an irradiation system including 12 light emitting units (E1 to E12) arranged at equal intervals (Le) along the main direction, and 12 illumination microlenses (LE1 to LE12). An illumination optical system, a light receiving optical system including 12 light receiving microlenses (LD1 to LD12), a light receiving system including 12 light receiving units (D1 to D12), and the like.

  In addition, three toner patterns (PattA, PattB, and PattC) corresponding to the three reflective optical sensors are formed as test patterns, and each toner pattern has four rectangles having different toner concentrations for each toner color. The pattern has density detection patterns arranged in four rows, that is, in a 4 × 4 matrix. With respect to the main direction, the length L1 of each rectangular pattern is 450 μm, and is set to be larger than the interval Le between two adjacent light emitting portions. Further, with respect to the main direction, the distance L2 between the centers of two rectangular patterns adjacent to each other is 800 μm.

  In the main direction, the toner pattern is located between the two light emitting portions (E1 and E12) at both ends.

  In this case, four rectangular patterns adjacent in the main direction can be irradiated with detection light almost simultaneously. In addition, it is easy to separate the amount of light received by each light emitting unit into the amount of light received by regular reflected light and the amount of light received by diffusely reflected light. From this, it is possible to detect the toner density of four rectangular patterns adjacent in the main direction almost simultaneously with one reflective optical sensor.

  Further, since the light emitting portion is very small, the spot of the detection light can be reduced, and as a result, the size of the rectangular pattern can be reduced. This also has the advantage of reducing the consumption of non-contributing toner that is not used for image formation.

  Furthermore, since the light emitting unit and the light receiving unit are close to each other, the incident angle and the reflection angle of the detection light to the irradiation target can be reduced. As a result, it is possible to reduce detection errors due to a fado factor that causes the transfer belt to become a shadow of toner and fluctuations in the transfer belt (variation in the distance between the reflective optical sensor and the transfer belt).

  In addition, since the density detection pattern includes four rectangular patterns having different toner densities for each toner color arranged in four rows, the length of the toner pattern in the sub direction is about 1/4 of the conventional one. can do. Thereby, the influence of density unevenness in the sub direction can be reduced.

  In this case, the toner density can be set to a desired toner density almost in real time without causing an increase in size, and as a result, a stable image density can always be obtained even when the environment changes. That is, it is possible to maintain high image quality without increasing the size and workability.

  In the above-described embodiment, the case where the light emitting unit E1 to the light emitting unit E12 are sequentially repeatedly turned on / off in the detected received light amount acquisition process has been described. However, the present invention is not limited to this. Only the corresponding light emitting units may be repeatedly turned on and off sequentially. Specifically, the light emission unit E4 corresponding to the density detection pattern DP1, the light emission unit E6 corresponding to the density detection pattern DP2, the light emission unit E8 corresponding to the density detection pattern DP3, and the density detection pattern DP4. The corresponding light emitting unit E10 may be repeatedly turned on / off sequentially. In this case, the repetition frequency can be increased. In addition, power consumption can be reduced.

  In the above embodiment, the case has been described in which the respective density detection patterns are arranged in four rows when viewed from the sub-direction. However, the present invention is not limited to this. For example, as shown in FIG. 21, the respective density detection patterns may be arranged in four rows when viewed from the main direction.

  Further, the arrangement order of the rectangular patterns is not limited to the arrangement of the above embodiment (see FIG. 22).

  Moreover, in the said embodiment, as FIG. 23 shows as an example, each rectangular pattern may be formed so that it may correspond to two light emission parts. As an example, as shown in FIG. 24, each rectangular pattern may be formed so as to correspond to three light emitting units.

  In this case, in the detected light reception amount acquisition process, at least two light emitting units can be individually turned on / off for one rectangular pattern. Then, the toner density of the rectangular pattern is obtained for each light emitting unit, and the average value may be used as the detection result. At that time, the maximum value and the minimum value or the abnormal value may be excluded. In this case, the toner concentration may be obtained from the average value of the amount of received light obtained for each light emitting unit, and the toner concentration may be used as the detection result. Thereby, detection accuracy can be improved.

  Moreover, in the said embodiment, as shown in FIGS. 25-28 as an example, the four density detection patterns may be arranged in two rows when viewed from the sub direction.

  Further, in the above embodiment, instead of the toner pattern, as shown in FIG. 29 as an example, four line patterns (LPY1, LPM1, LPC1, LPK1) parallel to the main direction (Y-axis direction) and Alternatively, a toner pattern PL including four linear patterns (LPY2, LPM2, LPC2, LPK2) inclined with respect to the main direction may be used.

  The line patterns LPY1 and LPY2 are paired and formed with yellow toner, and the line patterns LPM1 and LPM2 are paired and formed with magenta toner. The line patterns LPC1 and LPC2 are paired and formed with cyan toner, and the line patterns LPK1 and LPK2 are paired and formed with black toner.

  Each pair of line patterns is set such that the interval between the two line patterns forms a predetermined interval in the sub direction.

  The four line patterns (LPY1, LPM1, LPC1, LPK1) are divided into four partial areas in the main direction. Each partial region has a different toner density.

  Further, regarding the main direction, the length LT of each linear pattern satisfies the relationship of LT ≧ Le × NT using the number NT (in this case, 4) of partial regions.

  Further, regarding the main direction, the length LP of each partial region satisfies the relationship of LP ≧ Le + S using the spot diameter S (here, diameter 0.4 mm) of the detection light spot.

  In this case, it is possible to detect the positional deviation of the toner image together with the toner density. FIG. 30 shows an example of the positional relationship between the reflective optical sensor and the toner pattern PL.

  As shown in FIG. 31 as an example, the printer control apparatus 2090 includes a light emitting unit so that four detection lights (here, S3, S5, S7, and S9) sequentially irradiate the line patterns LPY1 to LPK2. Turns on and off.

  The printer control device 2090 obtains the toner density of each partial area in the same manner as in the above embodiment, and also detects the time Tym from when the detection light irradiates the line pattern LPY1 until the line pattern LPM1 is irradiated, and for detection. The time Tmc from when the light irradiates the line pattern LPC1 to the irradiation of the line pattern LPC1, and the time Tck from when the detection light irradiates the line pattern LPC1 to the irradiation of the line pattern LPK1 are detected. (See FIG. 32). Here, for the sake of easy understanding, it is assumed that the output signal of each light receiving unit is amplified and inverted and passes through a comparison circuit that compares with a predetermined reference value.

  The printer control device 2090 also displays the time Ty from when the detection light irradiates the line pattern LPY1 to when the detection light irradiates the line pattern LPY2, and the line pattern LPM2 after the detection light irradiates the line pattern LPM1. The time Tm until the irradiation of the line pattern LPC1, the time Tc from when the detection light irradiates the line pattern LPC2, and the line pattern LPK2 after the detection light irradiates the line pattern LPK1. The time Tk until irradiation is detected is detected (see FIG. 32).

  Then, for example, the positional deviation amount ΔS in the main direction of the yellow toner image is obtained using the following equation (1) (see FIGS. 33A and 33B). Here, V is the moving speed of the transfer belt 2040 in the sub direction, ΔT is the difference between the time Ty and the reference time, and θ is the inclination angle of the line pattern LPY2 with respect to the main direction.

  ΔS = V · ΔT · cot θ (1)

  Then, the printer control device 2090 adjusts the writing start timing, for example, according to the detected misregistration amount.

  In this case, as an example, as shown in FIGS. 34 and 35, four line patterns (LPY2, LPM2, LPC2, LPK2) may be divided into four partial regions in the main direction. .

  Moreover, although the said embodiment demonstrated the case where each reflective optical sensor had 12 light emission parts, it is not limited to this.

  In the above-described embodiment, the case where four rectangular patterns having different toner densities are formed for each toner color is described. However, the present invention is not limited to this. For example, eight rectangular patterns having different toner concentrations may be formed for each toner color.

  In the above embodiment, the case where the surface of the transfer belt is smooth has been described. However, the present invention is not limited to this, and the surface of the transfer belt may not be smooth. Further, a part of the surface of the transfer belt may be smooth.

  Moreover, although the said embodiment demonstrated the case where 12 micro lenses for illumination and 12 micro lenses for light reception were integrated, it is not limited to this.

  In the above-described embodiment, a processing device may be provided in the reflective optical sensor, and the processing device may perform at least a part of the processing in the printer control device 2090.

  In the above embodiment, the scanning control device may perform at least a part of the processing in the printer control device 2090.

  In the above-described embodiment, the toner detector 2245 has three reflective optical sensors. However, the present invention is not limited to this. At this time, the number of toner patterns corresponding to the number of reflective optical sensors is created.

  In the above embodiment, the toner detector 2245 detects the toner pattern on the transfer belt 2040. However, the present invention is not limited to this, and the toner pattern on the surface of the photosensitive drum may be detected. good.

  In the above embodiment, the case where four color toners are used has been described. However, the present invention is not limited to this.

  In the above embodiment, the toner detector 2245 detects the toner pattern on the transfer belt 2040. However, the present invention is not limited to this, and the toner pattern on the surface of the photosensitive drum may be detected. good.

  In the above embodiment, the toner pattern may be transferred to a recording sheet, and the toner detector 2245 may detect the toner pattern on the recording sheet.

  In the above-described embodiment, the case of the color printer 2000 including a plurality of photosensitive drums has been described as the image forming apparatus. However, the present invention is not limited to this. For example, as shown in FIG. And can be applied to a laser printer 1000 that forms a monochrome image.

  The laser printer 1000 includes an optical scanning device 1010, a photosensitive drum 1030, a charging charger 1031, a developing roller 1032, a transfer charger 1033, a charge eliminating unit 1034, a cleaning unit 1035, a toner cartridge 1036, a paper feeding roller 1037, a paper feeding tray 1038, A registration roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, a toner detector 1045, a communication control device 1050, and a printer control device 1060 that comprehensively controls the above-described units are provided.

  The toner detector 1045 includes a reflective optical sensor similar to the reflective optical sensor of the toner detector 2245, and detects a toner pattern on the surface of the photosensitive drum 1030.

  Further, it may be an image forming apparatus other than a printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated.

  As described above, the image forming apparatus of the present invention is suitable for maintaining high image quality without deteriorating workability.

  1000 ... Laser printer (image forming apparatus), 1030 ... Photosensitive drum (image carrier), 2000 ... Color printer (image forming apparatus), 2010 ... Optical scanning device (test pattern creating apparatus), 2030a to 2030d ... Photosensitive drum (Image carrier), 2040 ... transfer belt (intermediate transfer belt), 2090 ... printer control device (processing device, adjustment device, monitoring device), 2245a ... reflective optical sensor, 2245b ... reflective optical sensor, 2245c ... reflective type Optical sensor, D1 to D12 ... light receiving unit, E1 to E12 ... light emitting unit, LD1 to LD12 ... light receiving microlens, LE1 to LE12 ... lighting microlens, PattA ... toner pattern (test pattern), PattB ... toner pattern (test) Pattern), PattC ... Toner pattern (test pattern) , P1~p4 ... rectangular patterns (patches).

JP 2009-93007 A JP 2008-40441 A JP 2006-220846 A JP 2009-258601 A

Claims (16)

In an image forming apparatus that forms an image on a moving body using toner,
The test pattern including a plurality of patches having different colors or densities of the toner is moved so that at least two patches are arranged side by side in a second direction orthogonal to the first direction in which the moving body moves. A test pattern creation device for creating at least one on the body;
With respect to the second direction, an irradiation system consisting of at least three light emitting units arranged at a distance Le smaller than the distance between the centers of at least two patches arranged in the second direction, and the test emitted from the irradiation system and the test A light receiving system configured to receive at least three light receiving portions that receive light reflected by the pattern, and the test pattern is positioned between two light emitting portions at both ends of the at least three light emitting portions with respect to the second direction. At least one reflective optical sensor;
A processing device that individually obtains toner density information of the plurality of patches based on an output signal of a light receiving system of the at least one reflective optical sensor,
The processing unit, within the time the irradiation region of light emitted from the illumination system is one patch through a portion or all of said at least three light-emitting portions, at least once, Ru are sequentially turned on and off images forming device.   The image forming apparatus according to claim 1, wherein the interval Le is smaller than an arrangement pitch of the plurality of patches in the second direction. Has a plurality of pre Kihan morphism optical sensor,
The plurality of reflective optical sensors are arranged at different positions with respect to the second direction ,
Said test pattern generating apparatus, a plurality of test patterns corresponding to the plurality of reflective optical sensor, to claim 1 or 2, characterized in that formed at different positions in the second direction on the movable body The image forming apparatus described. The moving body, the image forming apparatus according to any one of claims 1 to 3, characterized in that an image bearing member having a photosensitive property. The moving body, the image forming apparatus according to any one of claims 1 to 3, characterized in that an intermediate transfer belt. The processing based on the toner density information from the device, an image forming apparatus according to any one of claims 1 to 5, characterized in that it comprises an adjustment device for adjusting the conditions for creating the image. At a predetermined timing, the image formation and inhibition state, the image forming apparatus according to any one of claims 1 to 6, characterized in that it comprises a monitoring device for instructing the creation of the test pattern to the test pattern generating apparatus . The image forming apparatus according to claim 7 , wherein the monitoring apparatus determines the timing based on information related to at least one of a use environment and a use history of a member involved in image formation. Wherein the plurality of patches, the image forming apparatus according to any one of claims 1-8, characterized in that it is arranged in a row along the second direction. The plurality of patches are arranged in a line along a third direction different from both the first direction and the second direction in the surface of the movable body. the image forming apparatus according to any one of 8. The image forming apparatus according to claim 9 , wherein in the plurality of patches, two adjacent patches are in contact with each other. The length LT of the plurality of patches with respect to the second direction is such that a relationship of LT ≧ Le × NT is satisfied using the number of patches NT in the plurality of patches. The image forming apparatus according to any one of 9 to 11 . Regarding the second direction, the length LP of each patch in the plurality of patches satisfies the relationship of LP ≧ Le + S using the spot diameter S of illumination light emitted from the irradiation system and illuminating the patch. The image forming apparatus according to claim 9 , wherein the image forming apparatus is an image forming apparatus. The said processing apparatus calculates | requires the positional information on these patches further based on the output signal of the light-receiving system of the said at least 1 reflection type optical sensor, It is characterized by the above-mentioned. Image forming apparatus. It said test pattern generating apparatus, a dither pattern, the writing light quantity, and the image forming apparatus according to any one of claims 1 to 14, characterized in that by changing the toner density by either of the developing bias. Wherein with respect to the second direction, the at least two patches are located in different positions, an image forming apparatus according to any one of claims 1 to 15, wherein the color toner are different from each other.