Image forming device

Abstract

The present invention provides an image forming apparatus. The image forming apparatus includes a detection unit that optically detects the density of a reference toner image for density measurement formed on an image holder. The image forming apparatus selects one of a first detection method and a second detection method based on toner color information pre-stored in a storage unit to optically detect the density of the reference toner image. The first detection method primarily detects the density of the reference toner image by receiving specularly reflected light from the image holder and the reference toner image for density measurement formed on the image holder, while the second detection method primarily detects the density of the reference toner image by receiving diffusely reflected light from the image holder and the reference toner image.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus. Background Art

[0002] An image forming device is known, which includes: an image carrier that forms an electrostatic latent image on its surface; a plurality of developing units that develop the electrostatic latent image using a developer containing colorant to form a colorant image on the image carrier; a transfer unit that transfers the colorant image formed on the image carrier to a recording material; and a concentration detection unit that detects the image concentration of the colorant image, the image forming device controls image forming conditions based on the detection result of the image concentration of the colorant image by the concentration detection unit, wherein the plurality of developing units include the following developing unit, which stores a colorant with the same hue but different concentration as the colorant stored in one developing unit, and the concentration detection unit has: a mirror reflection light detection unit that detects the amount of mirror reflection light of light irradiated on the colorant image; and a diffuse reflection light detection unit that detects the amount of diffuse reflection light (Japanese Patent Gazette No. 2005-189704). Summary of the Invention

[0003] An object of the present invention is to control the toner amount to a predetermined amount regardless of the type of toner and the arrangement position of the imaging engine.

[0004] According to a first aspect of the present invention, there is provided an image forming apparatus characterized in that:

[0005] The image forming device includes a detection unit, which optically detects the concentration of a reference colorant image for concentration measurement formed on an image retaining body. The image forming device selects any one of a first detection method and a second detection method to optically detect the concentration of the reference colorant image based on color information of the colorant pre-stored in a storage unit. In the first detection method, the concentration of the reference colorant image is mainly detected by mainly receiving mirror reflected light reflected from the image retaining body and the reference colorant image for concentration measurement formed on the image retaining body, and in the second detection method, the concentration of the reference colorant image is mainly detected by mainly receiving diffuse reflected light reflected from the image retaining body and the reference colorant image.

[0006] According to the second aspect of the present invention, a plurality of imaging engines for forming toner images are arranged, and even if the arrangement positions of the imaging engines are adjusted, the density of the reference toner image can be optically detected based on the toner color information pre-stored in the storage unit.

[0007] According to the third aspect of the present invention, when the imaging engine is installed, a setup operation of driving the imaging engine is performed to select one of the first detection method and the second detection method.

[0008] According to the fourth aspect of the present invention, the setting operation is performed when a user or a maintenance worker of the image forming apparatus performs adjustment work via an operation information unit that receives an operator's operation on the image forming apparatus.

[0009] According to the fifth aspect of the present invention, when the imaging engine is installed, the setting operation is performed based on the toner color information stored in advance in the storage unit.

[0010] According to the sixth scheme of the present invention, when the color information of the colorant is not pre-stored in the storage unit, a setting action of driving the imaging engine is implemented when the imaging engine is installed, and the concentration of the reference colorant image of multiple gray levels is optically detected by the first detection method and the second detection method, and the detection method with a larger rate of change of the detection value obtained is selected to optically detect the concentration of the reference colorant image.

[0011] According to the seventh aspect of the present invention, the image forming apparatus stores the selected first detection method or the second detection method in association with toner color information.

[0012] According to the 8th embodiment of the present invention, the detection unit comprises: a light-emitting element that irradiates light onto a reference colorant image for concentration measurement formed on the image retaining body; a light-receiving element that mainly receives mirror-reflected light reflected from the image retaining body and the reference colorant image; and another light-receiving element that mainly receives diffusely reflected light reflected from the image retaining body and the reference colorant image, thereby the detection unit optically detects the concentration of the reference colorant image.

[0013] According to the 9th embodiment of the present invention, the detection unit comprises: a light-emitting element which mainly irradiates the reference colorant image for concentration measurement formed on the image retaining body with mirror reflected light; another light-emitting element which mainly irradiates the reference colorant image for concentration measurement formed on the image retaining body with diffuse reflected light; and a light-receiving element which receives light reflected from the image retaining body and the reference colorant image, thereby the detection unit optically detects the concentration of the reference colorant image.

[0014] According to the tenth aspect of the present invention, the color information of the toner includes a special color toner, and the special color toner has a metallic luster.

[0015] (Effect)

[0016] According to the first aspect, the toner amount can be controlled to a predetermined amount regardless of the type of toner.

[0017] According to the second aspect, the toner amount can be controlled to a predetermined amount regardless of the type of toner and the placement position of the imaging engine.

[0018] According to the third aspect, during the setup operation, it is possible to select an appropriate detection method for the toner type of the installed imaging engine.

[0019] According to the fourth aspect, during the setup operation, the user or maintenance worker of the image forming apparatus can select an appropriate detection method for the toner type of the installed imaging engine.

[0020] According to the fifth aspect, during the setup operation, it is possible to select an appropriate detection method for the type of toner of the installed imaging engine based on the toner color information.

[0021] According to the sixth aspect, even when a detection method for toner color information is not specified or when a new toner type does not have toner color information, an appropriate detection method can be selected for the toner type.

[0022] According to the seventh aspect, when the same type of toner is installed next time or later, the toner amount can be controlled using the detection method stored in the image forming apparatus.

[0023] According to the eighth and ninth aspects, both specularly reflected light and diffusely reflected light can be detected.

[0024] According to the tenth aspect, the toner amount of the special color toner can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic cross-sectional view showing the internal structure of the image forming apparatus.

[0026] Figure 2 It is a schematic cross-sectional view showing a photoreceptor unit, a developing device, and a toner supply device.

[0027] Figure 3 This is a diagram showing an example of an ADC sensor.

[0028] Figure 4 (a) is a schematic cross-sectional view schematically showing the brilliant toner particles S along the thickness direction, and (b) is a schematic cross-sectional view illustrating light reflection of the brilliant toner after fixing.

[0029] Figure 5(a) is a diagram illustrating a toner patch formed on an intermediate transfer belt, and (b) is a diagram illustrating reading of the toner patch.

[0030] Figure 6 This is a diagram showing an example of the detection sensitivity of the ADC sensor.

[0031] Figure 7 This is a functional block diagram showing the functional structure of the image forming apparatus.

[0032] Figure 8 This is a block diagram of the storage area of ​​an IC tag.

[0033] Figure 9 This is a flowchart showing the flow of a process for selecting a detection method performed by the system control device when a toner cartridge or an imaging engine is installed.

[0034] Figure 10 This is a flowchart showing the flow of a process for selecting a detection method performed by the system control device when a toner cartridge or an imaging engine is installed.

[0035] Figure 11 Schematically shows the rate of change of ADC sensor output values.

[0036] Figure 12 This figure shows an example of dividing the rate of change of the ADC sensor output value into each grayscale area of ​​the highlight area, the halftone area, and the high-density area, and calculating the rate of change for each detection method. DETAILED DESCRIPTION

[0037] Next, the present invention will be described in further detail with reference to the accompanying drawings by way of embodiments and specific examples, but the present invention is not limited to these embodiments and specific examples.

[0038] In the description using the following drawings, it should be noted that the drawings are schematic and that the ratios of dimensions and the like differ from actual ones. For ease of understanding, illustration of components other than those necessary for the description is omitted as appropriate.

[0039] (1) Overall structure and operation of image forming apparatus

[0040] (1.1) Overall Structure of Image Forming Apparatus

[0041] Figure 1 is a schematic cross-sectional view showing a schematic structure of the image forming apparatus 1 according to the present embodiment. Figure 2 1 is a schematic cross-sectional view showing the photoconductor unit 13 , the developing device 14 , and the toner supply device 18 .

[0042] The image forming apparatus 1 is configured to include: an image forming unit 10; a paper feeding device 20 installed below the image forming unit 10; a paper discharge unit 30 provided at one end of the image forming unit 10 for discharging printed paper; an operation information unit 40; and an image processing unit 50 for generating image information based on print information sent from a higher-level device.

[0043] The image forming unit 10 includes a system control device 11, an exposure device 12, a photosensitive body unit 13, a developing device 14, a transfer device 15, paper conveying devices 16a and 16b, a fixing device 17, and a toner supply device 18 (see FIG. Figure 2 ), a toner image is formed on the recording medium fed from the paper feeding device 20.

[0044] The paper feeding device 20 supplies recording media to the image forming unit 10. Specifically, the paper feeding device 20 includes a plurality of paper loading sections 21 and 22 for storing recording media of different types (e.g., material, thickness, paper size, and paper texture), and supplies the recording medium fed from any of the plurality of paper loading sections 21 and 22 to the image forming unit 10.

[0045] The paper discharge unit 30 discharges paper sheets that have been image-output by the image forming unit 10 and fixed by the fixing device 17. To this end, the paper discharge unit 30 includes a conveyance path 30a for conveying fixed paper sheets and a paper storage unit T1 for discharging fixed paper sheets. Furthermore, the paper discharge unit 30 includes a paper reversing unit 16c, which reverses the front and back sides of the paper sheets when outputting images on both sides and delivers them to the paper conveying device 16b. Furthermore, the paper discharge unit 30 may also perform post-processing such as cutting or stapling (binding) the stack of paper sheets output from the image forming unit 10.

[0046] The operation information unit 40 is used to input various settings and instructions and display information. Specifically, it corresponds to a so-called user interface and is specifically constituted by combining a liquid crystal display panel, various operation buttons, a touch panel, and the like.

[0047] (1.2) Structure and Operation of Image Forming Unit

[0048] In an image forming device 1 having such a structure, the recording medium fed out from the paper loading sections 21, 22 is fed into the image forming section 10 in correspondence with the timing of image formation. The paper loading sections 21, 22 refer to the paper loading sections 21, 22 designated for each sheet of paper to be printed in a print job.

[0049] The photoconductor unit 13 includes a photoconductor drum 31 as a driven latent image holder, and the photoconductor drum 31 is arranged below the exposure device 12. Along the rotation direction of the photoconductor drum 31, a charger 32, the exposure device 12, the developing device 14, the primary transfer roller 52, and the cleaning device 33 are arranged.

[0050] The photosensitive drum 31 , charger 32 , and cleaning device 33 of the photosensitive unit 13 are integrated into a cartridge, so that only the cartridge can be removed from or attached to the main body of the image forming apparatus 1 .

[0051] The developing device 14 includes a developing housing 41 that stores a developer containing toner and a carrier, a developing roller 42 disposed opposite the photosensitive drum 31, a stirring auger 43 that stirs and conveys the developer, and a supply auger 44 that supplies the developer to the developing roller 42. Each developing device 14 has substantially the same configuration, except for the developer. Each developing roller 42 forms a toner image on the photosensitive drum 31 using not only the general colors of yellow (Y), magenta (M), cyan (C), and black (K), but also special colors such as gold and silver containing a luminous pigment, and white and transparent containing a metallic pigment.

[0052] The developing device 14 is provided with an ATC (Auto Toner Control) sensor SR1 that measures the ratio of toner to carrier in the developer circulating in the developing housing 41 (hereinafter sometimes referred to as toner concentration (TC)).

[0053] Above the developing device 14, a replaceable toner cartridge TC storing toner and a toner supply device 18 for supplying toner and carrier from each toner cartridge TC to the developing device 14 are arranged (see FIG. Figure 2 The toner cartridge TC is equipped with an IC tag 140 ( Figure 1 Not shown in the figure, refer to Figure 9 、 Figure 10 ), for example, stores identification information including toner color information and usage history information.

[0054] The developing device 14, the toner cartridge TC, and the toner supply device 18 may be used as an imaging engine for each color and alternately used for the photoreceptor unit 13. In addition, the photoreceptor units 13 may be used alternately with each other.

[0055] The surface of the rotating photosensitive drum 31 is charged by the charger 32, and an electrostatic latent image is formed by latent image forming light emitted from the exposure device 12. The electrostatic latent image formed on the photosensitive drum 31 is developed into a toner image by the developing roller 42.

[0056] The transfer device 15 is constructed to include an intermediate transfer belt 51 as an example of an image holder to which the colorant images of each color formed by the photosensitive drum 31 of each photosensitive unit 13 are transferred multiple times, a primary transfer roller 52 that sequentially transfers (primary transfer) the colorant images of each color formed by each photosensitive unit 13 onto the intermediate transfer belt 51, and a secondary transfer roller 53 that transfers (secondary transfer) the colorant images of each color transferred and overlapped on the intermediate transfer belt 51 together onto a sheet of paper as a recording medium.

[0057] An ADC sensor (Auto Density Control) SR2 is arranged downstream of the black (K) imaging engine and upstream of the secondary transfer unit TR, facing the intermediate transfer belt 51, as an example of a detection unit for detecting the density of a reference toner image for density measurement transferred onto the intermediate transfer belt 51.

[0058] The color toner images of each color formed on the photosensitive drum 31 of each photosensitive unit 13 are electrostatically transferred (primary transfer) in sequence to the intermediate transfer belt 51 by the primary transfer roller 52 to which a prescribed transfer voltage is applied, thereby forming an overlapping colorant image formed by overlapping color toners of each color. The prescribed transfer voltage is applied from a power supply device (not shown) controlled by the system control device 11.

[0059] The superimposed toner images on the intermediate transfer belt 51 are conveyed to the secondary transfer section TR as the intermediate transfer belt 51 moves. In this secondary transfer section TR, the secondary transfer roller 53 is positioned in pressure contact with the backup roller 65 across the intermediate transfer belt 51. When the superimposed toner images are conveyed to the secondary transfer section TR, paper is supplied from the paper feed device 20 to the secondary transfer section TR at that moment. A predetermined secondary transfer voltage is then applied from a power supply (not shown) controlled by the system control unit 11 to the backup roller 65, which faces the secondary transfer roller 53 across the intermediate transfer belt 51. This transfers the multiple toner images on the intermediate transfer belt 51 onto the paper.

[0060] The residual toner on the surface of the photosensitive drum 31 is removed by the cleaning device 33 and collected in a waste toner storage unit (not shown). The surface of the photosensitive drum 31 is charged again by the charger 32 .

[0061] The fixing device 17 includes: an endless fixing belt 17a that rotates in one direction; and a pressure roller 17b that contacts the peripheral surface of the fixing belt 17a and rotates in one direction, and a pressing portion (fixing area) is formed by the pressing area between the fixing belt 17a and the pressure roller 17b.

[0062] The paper to which the toner image has been transferred in the transfer device 15 is conveyed to the fixing device 17 via the paper conveying device 16a without the toner image being fixed. The toner image on the paper conveyed to the fixing device 17 is fixed by the heat and pressure of a pair of fixing belts 17a and a pressure roller 17b.

[0063] After the fixing process, the paper is loaded into the paper discharge storage section T1. Furthermore, when outputting images on both sides of the paper, the front and back sides of the paper are reversed by the paper reversing section 16c and fed again to the secondary transfer section TR in the image forming section 10 via the paper conveying device 16b. After the toner image is transferred and the transferred image is fixed, the paper is fed to the paper discharge section 30. The paper fed to the paper discharge section 30 undergoes subsequent processing, such as cutting or stapling, as needed.

[0064] (2) Density detection of reference toner image

[0065] Figure 3 1 is a diagram showing an example of the ADC sensor SR2. Figure 4 (a) is a schematic cross-sectional view schematically showing the brilliant toner particles S in the thickness direction, and (b) is a schematic cross-sectional view schematically showing the reflection of light by the brilliant toner after fixing. Figure 5 (a) is a diagram illustrating a toner patch formed on the intermediate transfer belt 51, and (b) is a diagram illustrating reading of the toner patch. Figure 6 This is a diagram showing an example of the detection sensitivity of the ADC sensor.

[0066] Hereinafter, the density detection of the reference toner image will be described with reference to the drawings.

[0067] The ADC sensor SR2 optically reads the Figure 3 A sensor for measuring the density of a toner patch P transported in the transport direction of the intermediate transfer belt 51 indicated by an arrow R.

[0068] like Figure 3 As shown, the ADC sensor SR2 includes: a light-emitting unit SR2-1 that irradiates light; a first light-receiving unit SR2-2 that receives specularly reflected light reflected by the colorant color mark P in the light irradiated from the light-emitting unit SR2-1; a second light-receiving unit SR2-3 that mainly receives diffusely reflected light reflected by the colorant color mark P; and an optical system SR2-4.

[0069] The light emitting unit SR2 - 1 irradiates light toward the intermediate transfer belt 51. At this time, the incident angle of the irradiated light on the intermediate transfer belt 51 is θ. The light emitting unit SR2 - 1 is, for example, an LED (Light Emitting Diode).

[0070] The optical system SR2 - 4 is provided between the light emitting section SR2 - 1 and the intermediate transfer belt 51 , receives the irradiation light, and adjusts the traveling direction of light included in the irradiation light.

[0071] The first light receiving unit SR2-2 receives the specularly reflected light that is specularly reflected on the intermediate transfer belt 51 via the optical system SR2-4, and detects the density of the image formed by the black toner and the special color toner containing bright pigments such as gold and silver in the toner color patch P formed on the intermediate transfer belt 51. Since the specularly reflected light is specularly reflected light, Figure 3 As shown, the mirror reflection angle on the intermediate transfer belt 51 is θ, which is the same as the incident angle.

[0072] The first light receiving unit SR2-3 receives the diffusely reflected light diffusely reflected by the intermediate transfer belt 51 via the optical system SR2-4, and detects the density of the image formed by the toners of the general colors (Y, M, C) other than black and the white toner in the toner patch P formed on the intermediate transfer belt 51. The reflection angle of the diffusely reflected light on the intermediate transfer belt 51 is different from the incident angle θ. For example, Figure 3 As shown, it is Φ.

[0073] Each of the first light receiving unit SR2 - 2 and the second light receiving unit SR2 - 3 is an optical element that generates a signal corresponding to received light, and is, for example, a photodiode (PD).

[0074] Furthermore, the ADC sensor SR2 determines the color of the colorant patch P based on the wavelength of the reflected light received by the first light receiving unit SR2-2 and the second light receiving unit SR2-3, and outputs a value (sensor value) corresponding to the concentration of the colorant patch P based on the intensity of the received reflected light to the system control device 11.

[0075] In the printing market, glossy toners containing metallic pigments are used to create glossy metallic prints. Metallic prints are used for a variety of applications, including greeting cards, book covers, labels, and packaging, due to their impressive and colorful expression.

[0076] like Figure 4As schematically shown in (a), the bright toner is a flat bright toner particle S with an equivalent circle diameter longer than its thickness L, and contains a scaly metallic pigment G, a type of bright pigment. Bright toners such as gold and silver are flattened so that the bright pigment inside the toner is oriented parallel to the long axis of the toner. As a result, the bright pigment of the toner transferred to a medium MD such as paper or film is parallel to the medium, as shown in FIG. Figure 4 As shown in (b), in the image after fixing, the reflection of light from the pigment is enhanced, thereby exhibiting high brilliance and producing a metallic feel.

[0077] The reference toner of such a toner type is as shown in Figure 5 As shown in (a) of FIG. 1 , a plurality of toner patches (pattern P[i]: i=1 to 9) with different area grayscale ratios Cin are formed on the intermediate transfer belt 51. Figure 5 As shown in (b) of FIG. 5 , the density of the toner patch moving together with the intermediate transfer belt 51 is read by the ADC sensor SR2 arranged opposite to the intermediate transfer belt 51. The toner patch may be formed continuously for each toner color, or may be formed individually for each toner color.

[0078] Figure 6 An example of the normalized ADC sensor output value with respect to the input area grayscale ratio Cin (%) of the toner color patch P of various toners is shown.

[0079] like Figure 6 As shown, when the diffusely reflected light of the general color toner (Y, M, C) is detected by the second light receiving portion SR2-3 of the ADC sensor SR2, the ADC sensor output value can obtain a larger sensitivity R1 relative to the input area grayscale rate Cin (%) of the colorant color patch P.

[0080] In contrast, in the case of a special color A (silver toner) as an example of a bright toner, when this color is detected by diffuse reflected light, the ADC sensor output value can only obtain a small sensitivity R2 relative to the input area grayscale ratio Cin (%) of the toner color patch P. This is presumably because Figure 4 As shown in (a), the bright toner contains flaky metallic pigments G, so the specular reflection component is large. Even if the toner amount is increased, the output value corresponding to diffuse reflection light does not change like the toner of a general color.

[0081] When a special color A (silver toner) as an example of such a bright toner is detected using specular reflected light, as shown in FIG. Figure 6As shown by the sensitivity R3 in FIG. 1 , the sensitivity R3 of the ADC sensor output value increases with respect to the input area grayscale ratio Cin (%) of the toner patch P.

[0082] Furthermore, for black toner, since the specularly reflected light decreases as the toner amount increases, higher detection sensitivity can be obtained by performing detection using the specularly reflected light.

[0083] In this way, black toner and glossy toner are detected using mirror reflected light according to the type of colorant, and general color toners (Y, M, C) and white toner are detected using diffuse reflected light, thereby ensuring a high detection sensitivity of the ADC sensor SR2 according to the type of colorant.

[0084] In the image forming device 1 in this embodiment, any one of the first detection method and the second detection method is selected to optically detect the concentration of the reference colorant image, wherein the first detection method mainly receives the mirror reflection light reflected from the reference colorant image for concentration measurement formed on the intermediate transfer belt 51 to detect the concentration of the reference colorant image (hereinafter referred to as the "mirror reflection detection method"), and the second detection method mainly receives the diffuse reflection light reflected from the intermediate transfer belt 51 and the reference colorant image to detect the concentration of the reference colorant image (hereinafter referred to as the "diffuse reflection detection method").

[0085] (3) Density detection of reference toner image during setup operation

[0086] Figure 7 1 is a functional block diagram showing the functional configuration of the image processing device 1 according to the present embodiment.

[0087] like Figure 7 As shown, the system control device 11 includes a print control unit 110 , a toner density detection unit 111 , an image density detection unit 112 , a detection method selection unit 113 , and a toner replenishment control unit 114 , and executes a control program stored in a memory to control the operation of the image forming unit 10 .

[0088] When the toner cartridge TC is mounted on the main body of the image forming apparatus 1, the system control device 11 connects the interface 160 of the toner cartridge TC to the interface 115, thereby enabling communication. Figure 7 , although the communication between the system control device 11 and the IC tag 140 is shown as wired communication, wireless communication may also be used.

[0089] An IC tag 140 as an example of a storage unit is attached to the toner cartridge TC. The IC tag 140 includes a nonvolatile memory 150 such as an EEPROM (Electrically Erasable and Programmable Read Only Memory) and an interface 160 .

[0090] When the toner cartridge TC is mounted on the main body of the image forming apparatus 1, the interface 160 of the toner cartridge TC is connected to the interface 115 of the system control device 11, and a communication state is established. Figure 7 , although the communication between the system control device 11 and the IC tag 140 is shown as wired communication, wireless communication may also be used.

[0091] The information in the IC tag 140 can then be read and rewritten by the CPU of the system control device 11. Furthermore, the CPU is connected to the RAM, ROM, non-volatile memory (NVM), and interface 115, and reads the operation control program for the image forming apparatus 1 from the ROM, and reads and rewrites information from the RAM and non-volatile memory (NVM).

[0092] The nonvolatile memory (NVM) of the system control device 11 has a first area 114c for storing information corresponding to the unique information of the IC tag 140, in addition to an area 114a for storing various setting information for image formation and an area 114b for storing the main body serial ID of the image forming device 1.

[0093] The nonvolatile memory 150 in the IC tag 140 includes a read area for storing unique information read from the system control device 11 and a read / write area for storing management information read from / written to the system control device 11 .

[0094] As the readout area, such as Figure 8 As shown functionally, as examples, there are an area 151 for storing the serial ID of the toner cartridge TC unique to the toner cartridge TC, an area 152 for storing toner color information, and an area 153 for storing mode information of the image forming apparatus 1 .

[0095] The print control unit 110 controls information transmission and reception between the paper feed device 20, the paper discharge unit 30, the operation information unit 40, and the image processing unit 50, and also controls the exposure device 12, the photosensitive body unit 13, the developing device 14, the transfer device 15, and the paper conveying devices 16a, 16b, and 16c ( Figure 7 Not shown in the figure, refer to Figure 1), the fixing device 17, the toner supply device 18, etc. issue action control instructions.

[0096] The toner concentration detection unit 111 obtains toner concentration information in the developing device 14 based on the detection result of the ATC sensor SR1 .

[0097] In order to stabilize the image density and grayscale, the image density detection unit 112 reads the reference colorant image (color patch pattern: P[i]) for density measurement formed on the intermediate transfer belt 51 via the ADC sensor SR2 during setting operations such as when the power is turned on, when a job starts, during a job, and when a job ends, and obtains the density information of the reference colorant image.

[0098] When the toner cartridge TC or the imaging engine is installed, the detection mode selection unit 113 drives the developing device 14 to perform a setup operation for confirming the image density detection mode. The unit then selects either the "specular reflection detection mode" or the "diffuse reflection detection mode" as the image density detection mode, corresponding to the toner color information pre-stored in the IC tag 140 carried in the toner cartridge TC. Specifically, the "diffuse reflection detection mode" is selected for toner color information such as Y, M, and C, or white, while the "specular reflection detection mode" is selected for black or brightly colored toners such as gold and silver (hereinafter sometimes referred to as special color toners).

[0099] In addition, when the color information of the colorant is not pre-stored in the IC tag 140, the detection mode selection unit 113 selects either the "mirror reflection detection mode" or the "diffuse reflection detection mode" based on the rate of change of the output signal of the ADC sensor SR2 obtained by the setting action of driving the imaging engine when the colorant cartridge TC or the imaging engine is installed.

[0100] The toner replenishment control unit 114 adjusts the toner concentration of the developer in the developing device 14 by controlling the rotation time and speed of the dispensing motor M of the toner supply device 18 according to the toner concentration detection value of the ATC sensor SR1 .

[0101] Figure 9 1 is a flowchart showing the flow of a process for selecting a detection method performed by the system control device 11 when the toner cartridge TC or the imaging engine is mounted.

[0102] When the power of the image forming apparatus 1 is turned off / on (S101), the identification information and usage history information of the colorant stored in the IC tag 140 of the colorant cartridge TC are read (S102). In step S103, it is determined whether a detection method of the ADC sensor SR2 corresponding to the color information of the colorant is specified (S103).

[0103] If a detection method corresponding to the toner color information is specified in the system control device 11 (S103: Yes), the detection method corresponding to the toner color information ("specular reflection detection method" or "diffuse reflection detection method") is selected (S104), and the grayscale target value of the ADC sensor SR2 corresponding to the toner color information is set (S105). Furthermore, if a detection method ("specular reflection detection method" or "diffuse reflection detection method") is specified in the toner identification information stored in the IC tag 140 in step 103, the read detection method may also be selected.

[0104] Then, the density of the toner patches formed with respect to a plurality of Cin having different area grayscale ratios is read using the selected detection method, and image density adjustment is performed ( S106 ).

[0105] If the detection method of the ADC sensor SR2 corresponding to the toner color information is not specified in step S103 ( S103 : No), it is determined whether the detection method is input from the operation information unit 40 ( S107 ).

[0106] In this embodiment, a user or maintenance worker of the image forming apparatus 1 can select a detection method corresponding to the toner type via the operation information portion 40 , which is an example of an operation information unit that accepts operator operations on the image forming apparatus, and start a setting operation.

[0107] When a detection method is input from the operation information unit 40 and selected (S107: "Yes"), a grayscale color patch target value of the ADC sensor SR2 corresponding to the color information of the colorant is set (S105), and the concentration of the colorant color patch formed by multiple Cin with different area grayscale rates is read using the selected detection method, and image concentration adjustment is performed (S106).

[0108] In step S107 , when it is determined that the detection mode has not been input from the operation information portion 40 ( S107 : No), it is determined whether the toner cartridge TC is mounted ( S108 ).

[0109] When the toner color of the toner cartridge TC is installed for the first time (S108: "No"), the imaging engine is driven to form a plurality of toner patches (patch patterns: P[i]) of grayscale (for example, grayscales of Cin0% to Cin100%) on the intermediate transfer belt 51 (S109).

[0110] Next, the image density of the toner patches of multiple grayscales is measured using the two detection methods, "specular reflection detection method" and "diffuse reflection detection method" (S110), and the change rate (sensitivity) of the ADC sensor output value under each detection method is calculated (S111).

[0111] Figure 11 The rate of change of the ADC sensor output value at this time is schematically shown. Figure 11 For example, the rate of change of the ADC sensor output value when detecting with the "diffuse reflection detection method" is ΔB, and the rate of change of the ADC sensor output value when detecting with the "mirror reflection detection method" is ΔA, and the rate of change ΔA is larger than the rate of change ΔB.

[0112] Then, compare the rate of change of the ADC sensor output value when detecting in the "mirror reflection detection method" and the rate of change of the ADC sensor output value when detecting in the "diffuse reflection detection method" (S112). When the rate of change ΔA of the ADC sensor output value when detecting in the "mirror reflection detection method" is larger (S112: "Yes"), select the "mirror reflection detection method" as the detection method (S113). When the rate of change ΔB of the ADC sensor output value is larger (S112: "No"), select the "diffuse reflection detection method" as the detection method (S114).

[0113] Thus, even when a detection method for detecting toner color information is not specified or when a new toner type does not have toner color information, an appropriate detection method can be selected for the toner type.

[0114] Figure 12 The example shows that the rate of change of the ADC sensor output value is divided into each grayscale area of ​​the highlight area, halftone area, and high density area and set as Cin, and the rate of change of each detection method is calculated. Figure 12 The rates of change in the highlight area are ΔA1 and ΔB1, the rates of change in the halftone area are ΔA2 and ΔB2, and the rates of change in the high-density area are ΔA3 and ΔB3.

[0115] For such a difference in the rate of change, we can Figure 11 As shown in the figure, the change rate of the input area grayscale rate in the entire area of ​​Cin0% to Cin100% can be obtained as Figure 12 As shown, for example, the rate of change in the most important grayscale region of the toner color is selected and determined.

[0116] The detection method selected in this manner is associated with the toner color information and stored in the non-volatile memory (NVM) of the system control device 11 (S115). This allows the image density detection method and grayscale target value to be set when a new toner cartridge TC is installed, and allows predetermined image density adjustments to be made.

[0117] In such an image density detection method, the processing of selecting either the "mirror reflection detection method" or the "diffuse reflection detection method" corresponding to the color information of the colorant is not limited to special color colorants such as gold and silver, but can also be applied to the situation where the engine installation position of an imaging engine including general color Y, M, C, and K colorants is changed.

[0118] The image forming apparatus 1 of this embodiment is equipped with two image density detection methods, a "specular reflection detection method" and a "diffuse reflection detection method," for different toner characteristics. Either the "specular reflection detection method" or the "diffuse reflection detection method" is selected based on the color information of the toner pre-stored in the installed toner cartridge. With this image density detection method, even if the position of the imaging engine is adjusted, the detection method can be selected based on the toner color information.

[0119] Even if no detection method corresponding to toner information is specified, a setup operation can be performed when the toner cartridge TC is installed, and a detection method suitable for the toner type can be selected based on the difference in the rate of change of the ADC sensor output value. In this way, the image forming apparatus 1 according to this embodiment can perform highly accurate image density adjustment regardless of the toner type or the installation position of the imaging engine.

Claims

1. An image forming apparatus comprising a detection unit for optically detecting the density of a reference toner image for density measurement formed on an image holder, wherein the image forming apparatus optically detects the density of the reference toner image by selecting one of a first detection method and a second detection method based on toner color information pre-stored in a storage unit, wherein: In the first detection method, the concentration of the reference toner image is detected by mainly receiving specular reflected light reflected from the image holder and the reference toner image for density measurement formed on the image holder. In the second detection method, the concentration of the reference toner image is detected by mainly receiving diffuse reflected light reflected from the image holder and the reference toner image. In a case where the color information of the toner is not pre-stored in the storage unit, a setup operation of driving the imaging engine is performed when the imaging engine is installed, optically detecting the density of a reference toner image of a plurality of grayscales using the first detection method and the second detection method, and optically detecting the density of the reference toner image using the detection method that results in a greater rate of change in the detected value. The detection unit has: a light emitting element for irradiating light onto a reference toner image for density measurement formed on the image holding member; a light receiving element that mainly receives specularly reflected light reflected from the image holding member and the reference toner image; as well as another light receiving element that mainly receives diffusely reflected light reflected from the image holding member and the reference toner image, Thus, the detection unit optically detects the density of the reference toner image.

2. An image forming apparatus comprising a detection unit for optically detecting the density of a reference toner image for density measurement formed on an image holding member, The image forming apparatus selects one of a first detection method and a second detection method based on color information of the toner pre-stored in a storage unit to optically detect the density of the reference toner image by the detection unit, wherein: In the first detection method, the concentration of the reference toner image is detected by mainly receiving specular reflected light reflected from the image holder and the reference toner image for density measurement formed on the image holder. In the second detection method, the concentration of the reference toner image is detected by mainly receiving diffuse reflected light reflected from the image holder and the reference toner image. In a case where the color information of the toner is not pre-stored in the storage unit, a setup operation of driving the imaging engine is performed when the imaging engine is installed, optically detecting the density of a reference toner image of a plurality of grayscales using the first detection method and the second detection method, and optically detecting the density of the reference toner image using the detection method that results in a greater rate of change in the detected value. The detection unit has: a light emitting element for irradiating a reference toner image for density measurement formed on the image holding member with mainly specularly reflected light; another light emitting element for irradiating mainly diffuse reflected light onto a reference toner image for density measurement formed on the image holding member; and a light receiving element for receiving light reflected from the image holding member and the reference toner image, Thus, the detection unit optically detects the density of the reference toner image.

3. The image forming apparatus according to claim 1 or 2, wherein: The setting operation is performed when a user or a maintenance worker of the image forming apparatus performs adjustment work via an operation information unit that receives an operation of the image forming apparatus by the operator.

4. The image forming apparatus according to claim 1 or 2, wherein: The color information of the toner includes a special color toner, and the special color toner has a metallic luster.

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