JP4910463B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a printer, a copying machine, a facsimile machine, and an image forming apparatus that is a multifunction machine having these functions.

Japanese Patent Laid-Open No. 10-186827 Japanese Patent Laid-Open No. 11-084764

  In recent years, in order to expand the color gamut and improve image quality, in addition to the conventional yellow, magenta, cyan, and black, dark and light toners such as light magenta and light cyan with different densities are used. A method for improving the gradation and color reproduction up to a part has been proposed.

  Regarding the image density detection apparatus, the following image density detection apparatus (which can be called “toner density sensor apparatus” in the sense of detecting toner patch density) is disclosed.

In a toner concentration sensor device that irradiates a predetermined region on a photoconductor from an infrared light emitting diode and detects the density of toner adhering to the photoconductor based on the amount of infrared light received by the infrared light receiving element. The current-voltage conversion circuit that converts the output of the infrared light receiving element into a voltage, and the output voltage of the current-voltage conversion circuit are input, and an output corresponding to each color toner density such as yellow, magenta, and cyan is obtained. The reference voltage and the circuit amplification factor are determined so that an output corresponding to the black toner density can be obtained by using the output voltage of the color amplification circuit and the current-voltage conversion circuit for which the reference voltage and the circuit amplification factor are determined as input. A toner density sensor device including the determined black amplifier circuit (see Patent Document 1).
According to this example, the toner density sensor device determines the reference voltage and circuit gain of the color amplifier circuit so that an output corresponding to each color toner density is obtained, and sets the reference voltage and circuit gain of the black amplifier circuit. Since the output corresponding to the black toner density is determined, the color toner density and the black toner density can be detected with high accuracy over a wide density range.

  The following image forming apparatus is disclosed as an image forming apparatus having dark toner and light color toner of similar colors.

A charging unit for charging the photoconductor around the photoconductor, an exposure unit for forming an electrostatic latent image composed of a plurality of vertical and horizontal latent image pixels, and a development for developing the electrostatic latent image In the image forming apparatus, the exposure unit forms each of the latent image pixels by changing the potential of the electrostatic latent image in accordance with the input image information indicating the degree of shading, and the developing unit Is an image forming apparatus that develops with a plurality of light and dark toners corresponding to the potential of the electrostatic latent image (see Patent Document 2).
According to this example, even in the xerographic process, an image can be formed with dark toner and light color toner without significantly increasing the scale of the apparatus, and the gradation and graininess of the halftone image are improved. There is an effect that can be.

In the above prior art, in the case of Patent Document 1, when the image density detection device detects a patch formed on the image carrier, the toner of the patch formed on the image carrier is a color toner. By optimizing the output gain, which is the density detection condition of the image density detection device, when the toner of the patch formed on the image carrier is black toner, it is formed on the image carrier by the image density detection device. Detection accuracy when detecting patches. However, since optimization of output gain is considered for color and black, and not for the case of dark toner and light color toner of similar colors, high-precision control of the dark color toner and light color toner is performed in the image forming apparatus. There is a problem that cannot be performed. Further, when the patch formed on the image carrier is detected by the image density detection device, the density detection condition of the image density detection device is simply optimized by the output gain which is the density detection condition of the image density detection device. Since the light emission intensity is not taken into consideration, there is a problem that the dark toner and light toner patches formed on the image carrier cannot be detected with high accuracy.
In the case of Patent Document 2, in order to maintain the gradation and graininess of the reproduced image, it is necessary to correct the image forming conditions corresponding to the environmental change and member deterioration of the image forming unit. By simply changing the potential of the electrostatic latent image in accordance with the input image information indicating the degree of light and dark and selecting the dark toner and light toner, the gradation and graininess of the image over time can be maintained. There is a problem that it is difficult. In addition, since it is premised that there is a difference in tribo charge amount between the dark toner and the light toner, the control for forming an image using the dark toner and the light toner is complicated and applicable. There is a problem that there is a high possibility that the species is limited and versatility is lost.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to increase the density of similar colors with different reflection intensities of light emitted from the light emitting elements even when the toner amount is the same. In an image forming apparatus having color toner and light color toner, an image forming apparatus capable of detecting the dark color toner and light color toner with high accuracy and performing image density and gradation control with high accuracy is provided. is there.

That is, the present invention includes an image density detection device including a light emitting element and a light receiving element, and a dark color toner and a light color toner of similar colors having the same amount of toner but different reflection intensity of light emitted from the light emitting element. In the image forming apparatus for detecting the density of the dark color toner and the light color toner patch formed on the carrier or the recording medium with an image density detecting device and correcting the image forming condition based on the detection result.
A density detection condition setting means for setting in response to the image light emission intensity is the concentration detection condition of the density sensing device and / or the output gain the dark color toner and light color toner,
A chromaticity detection device that detects chromaticity information of the dark color toner and light color toner patches formed on the image carrier or a recording medium;
The toner is determined based on the chromaticity information of the dark color toner and the light color toner patch detected by the chromaticity detection device, and the determination result is provided in the developing unit and the information of the dark color toner and the light color toner is stored. Toner determination means for storing in the toner information storage means for
The density detection condition setting unit sets the density detection condition based on the information on the dark color toner and the light color toner stored in the toner information storage unit stored in the toner determination unit. Device.
According to this, in the image forming apparatus having the dark toner and the light color toner of similar colors having the same amount of toner but different reflection intensity of the light emitted from the light emitting element, the dark color toner and the light color toner are detected with high accuracy. Thus, the density and gradation control of the reproduced image can be performed with high accuracy.

  In the present invention, there is also provided an output gain correction means for correcting the output gain of the image density detection device within the output range of the image density detection device set for each of the dark color toner and the light color toner.

  In the present invention, the dark toner and light toner patches are set in accordance with at least one of the input image image density, toner density, photoconductor film thickness, environment, developer usage status, and image carrier usage status. Output gain correction means for correcting the output gain of the image density detection device within the output range of the image density detection device.

  According to the present invention, in the image forming apparatus having the same color dark toner and light color toner having the same amount of toner but different reflection intensity of light emitted from the light emitting element, the dark toner and light color toner are detected with high accuracy. Thus, it is possible to provide an image forming apparatus capable of performing image density and gradation control with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment]
1 to 13 are diagrams showing an embodiment of an image forming apparatus according to the present invention.

  FIG. 1 is a diagram illustrating a tandem full-color printer 1 as an image forming apparatus according to the present embodiment. The full-color printer 1 includes an image reading device and functions as a full-color copying machine.

  An image reading device (IIT) 4 that reads an image of the document 2 is disposed at one upper end of the full-color printer 1. The image reading device 4 illuminates the original 2 placed on the platen glass 5 while being pressed by the platen cover 3 with a light source 6, and reflects a reflected light image from the original 2 into a full rate mirror 7 and a half rate mirror 8. , 9 and an image forming lens 10 are scanned and exposed onto an image reading element 11 made of a CCD or the like through a reduction optical system, and the image reading element 11 causes an image of the document 2 to have a predetermined dot density (for example, 1200 dpi or 2400 dpi). ).

  The image of the document 2 read by the image reading device 4 is sent to the image processing device 12 as image data of three colors of red, green, and blue (each 8 bits), for example. In the image processing device 12, predetermined image processing is performed on the image data of the document 2.

Image data that has been subjected to predetermined image processing by the image processing apparatus 12 is yellow (Y), magenta dark (M ₁ ), magenta light (M ₂ ), cyan (C), and black (K). Are converted into image data of five colors. The image data of five colors of yellow (Y), magenta dark (M ₁ ), magenta light (M ₂ ), cyan (C), and black (K) are yellow (Y) and magenta dark. (M ₁ ), magenta light color (M ₂ ), cyan color (C), and black color (K) image forming units 13 Y, 13 M ₁ , 13 M ₂ , 13 C, 13 K ROS 14 Y, 14 M ₁ , 14 M ₂ , 14C and 14K. In the ROSs 14Y, 14M ₁ , 14M ₂ , 14C, and 14K, image exposure with the laser beam LB is performed according to the image data of each color.

In the present exemplary embodiment, the image forming unit 13M ₁ includes a dark color (magenta dark color) toner and a light color (magenta light color) toner having the same toner amount but different reflection intensities of light emitted from the light emitting elements. 13M ₂ is provided.

In the present embodiment, the toner images formed by the image forming units 13Y, 13M ₁ , 13M ₂ , 13C, and 13K are once temporarily transferred onto the intermediate transfer member (image carrier) in a multiplexed manner, and then recorded. A color image is formed by batch transfer onto a medium.

The image forming units 13Y, 13M ₁ , 13M ₂ , 13C, and 13K are arranged in series at regular intervals in the horizontal direction. The image forming units 13M ₁ and 13M ₂ are arranged adjacent to each other.

The image forming unit 13M ₁ uses the same density (high density) of magenta toner as the conventional _one , and the image forming unit 13M ₂ uses the same magenta toner in the image forming unit 13M ₁ . A low density magenta toner is used as compared with the magenta toner.

  As the low density magenta toner, when the magenta toner is manufactured, the amount of the colorant such as a magenta pigment with respect to the resin constituting the toner is set to be small, or the magenta color toner to be used is used. The thing using the coloring agent with a low density | concentration is used as coloring agents, such as a pigment.

Each of the image forming units 13Y, 13M ₁ , 13M ₂ , 13C, and 13K is basically configured in the same manner except for the type of toner to be used. Each of the image forming units 13Y, 13M ₁ , 13M ₂ , 13C, and 13K has a uniform photosensitive drum (image carrier) 15 that rotates at a predetermined rotational speed in the direction of arrow A, and a circumferential surface of the photosensitive drum 15 uniformly. A primary scorotron 16 for charging, a ROS 14 for exposing an image corresponding to each color on the peripheral surface of the photosensitive drum 15 to form an electrostatic latent image, and an electrostatic latent image formed on the peripheral surface of the photosensitive drum 15 Is composed of a developing device 17 that develops toner with a corresponding color toner and a cleaning device 18.

  The ROS 14 modulates the semiconductor laser 19 according to the image data, and emits a laser beam LB from the semiconductor laser 19 according to the image data. The laser beam LB emitted from the semiconductor laser 19 is deflected and scanned by the rotary polygon mirror 22 via the reflecting mirrors 20 and 21, and the focal length is adjusted according to the scanning angle by an unillustrated f-θ lens. Then, the peripheral surface of the photosensitive drum 15 is scanned and exposed through a plurality of reflecting mirrors 23 and 24 and the like.

From the image processing apparatus 12, image forming units 13Y and 13M _{1 for} yellow (Y), magenta dark (M ₁ ), magenta light (M ₂ ), cyan (C), and black (K) are formed. , 13M ₂ , 13C, and 13K ROS 14Y, 14M ₁ , 14M ₂ , 14C, and 14K are sequentially output to each color image data, and output from these ROS 14Y, 14M ₁ , 14M ₂ , 14C, and 14K according to the image data. Laser beams LB are scanned and exposed on the peripheral surfaces of the respective photoconductive drums 15Y, 15M ₁ , 15M ₂ , 15C, and 15K to form electrostatic latent images. The electrostatic latent images formed on the peripheral surfaces of the photosensitive drums 15Y, 15M ₁ , 15M ₂ , 15C, and 15K are yellow (Y) and magenta by the developing devices 17Y, 17M ₁ , 17M ₂ , 17C, and 17K, respectively. It is developed as a toner image of each color of dark color (M ₁ ), magenta light color (M ₂ ), cyan color (C), and black color (K).

Since the ROS 14M ₁ and 14M ₂ perform image exposure based on image data corresponding to the same magenta color, the image processing apparatus 12 converts the image data corresponding to magenta color to the LUT according to the gradation. Etc., the image data is created separately for magenta dark color image data and magenta light color image data.

In the image forming units 13M ₁ and 13M ₂ , the density of the magenta toner used in the developing devices 17M ₁ and 17M ₂ is different. In the developing device 17M ₁ , a dark toner (dark toner) is used. In the developing device 17M ₂ , toner with a light density (light color toner) is used.

The developing devices 17Y, 17M ₁ , 17M ₂ , 17C, and 17K are supplied with toners of corresponding colors from toner cartridges that are developing units (not shown). Each toner cartridge is provided with a crumb (toner information storage means) for storing toner information.

Each image forming unit _{13Y, 13M 1, 13M 2,} 13C, 13K of the photosensitive drums _{15Y, 15M 1, 15M 2,} 15C, the circumferential surface of 15K, are sequentially formed yellow (Y), magenta dark (M ₁ ) The toner images of magenta light color (M ₂ ), cyan color (C), and black color (K) are arranged below the image forming units 13Y, 13M ₁ , 13M ₂ , 13C, and 13K. The toner image is transferred onto the peripheral surface of an intermediate transfer belt 25 as an intermediate transfer member in a state of being superposed by primary transfer rolls 26Y, 26M ₁ , 26M ₂ , 26C, and 26K.

The intermediate transfer belt 25 is wound around the drive roll 27, the tension roll 28, the steering roll 29, the idle roll 30, the backup roll 31, and the idle roll 32 with a constant tension, and has excellent constant speed (not shown). A drive roll 27 that is rotationally driven by a dedicated drive motor is circulated and driven in the direction of arrow B at a predetermined speed equal to the photosensitive drums 15Y, 15M ₁ , 15M ₂ , 15C, and 15K. As the intermediate transfer belt 25, for example, an endlessly formed synthetic resin film such as polyimide having flexibility is used.

Yellow (Y), magenta dark (M ₁ ), magenta light (M ₂ ), cyan (C), and black (K) toners transferred in multiple layers onto the peripheral surface of the intermediate transfer belt 25 The image is secondarily transferred onto a recording sheet 34 as a recording medium by a secondary transfer roll 33 that is in pressure contact with the backup roll 31 via the intermediate transfer belt 25, and toner images of these colors are formed. The transferred recording sheet 34 is conveyed to a fixing device 37 by conveying belts 35 and 36. The recording paper 34 onto which the toner image of each color has been transferred is subjected to a fixing process by heat and pressure by a fixing device 37, and is discharged onto the discharge tray 40 as it is in the case of single-sided printing. The fixing device 37 is generally composed of a heating roll 38 having a heat source therein, and a pressure roll 39 in pressure contact with the heating roll 38. Further, a cleaning device 50 is provided between the secondary transfer roll 33 and the drive roll in contact with the peripheral surface of the intermediate transfer belt 25.

  The recording paper 34 has a predetermined size or material from any of the plurality of paper trays 41 and 42 via a paper transport path 46 including a paper feed roll 43 and a pair of rolls 44 and 45 for paper transport. Then, it is once transported to the resist roll 47 and stopped. The recording paper 34 supplied from one of the paper trays 41 and 42 is sent to the secondary transfer position of the intermediate transfer belt 25 by a registration roll 47 that is rotationally driven at a predetermined timing.

  When images are formed on both sides of the recording paper 34, the recording paper 34, on which the image is fixed on one side by the fixing device 37, is not discharged onto the discharge tray 40 as it is, but is recorded by a switching gate (not shown). The transport path of the paper 34 is switched downward and is transported once to the reverse paper transport path 48. The recording paper 34 transported to the reversing paper transport path 48 is in a state where the front and back sides are reversed via the double-sided paper transport path 49 and the normal paper transport path 46 with the transport direction reversed. The sheet is conveyed again to the secondary transfer position of the intermediate transfer belt 25 and an image on the back side is formed. Then, the image is subjected to a fixing process with heat and pressure by the fixing device 37 and discharged onto the discharge tray 40.

  In the full-color printer 1, an image forming operation for forming an image on the recording paper 34 from the image information is controlled by the control unit 100.

  The image forming conditions for forming an image from the image information on the recording paper 34 by the full-color printer 1 are the result of detecting the density of the toner patch formed on the intermediate transfer belt 25 by the image density detecting device 102, the intermediate transfer. The chromaticity of the toner patch formed on the belt 25 is corrected based on the result detected by the chromaticity detection device 103.

FIG. 2 is a diagram illustrating the image density detection apparatus 102 according to the present embodiment. The image density detection device 102 includes a light emitting element 104 and a light receiving element 106. The issuing element 104 is a patch of color P (yellow (Y), magenta dark (M ₁ ), magenta light (M ₂ ), and cyan (C)) toner patches P formed on the intermediate transfer belt 25. It comprises a diffuse reflection LED 104a for detecting the density, and a regular reflection LED 104b for detecting the density of a black (K) toner patch P formed on the intermediate transfer belt 25. The density of the toner patch P formed on the intermediate transfer belt 25 is determined when the light irradiated from the light emitting element 104 is reflected by the toner patch P formed on the intermediate transfer belt 25 and received by the light receiving element 106. Detected by output.

  FIG. 3 is a diagram showing the relationship between the density (CIN) of the color toner patch P and the output (sensor output) of the image density detection apparatus 102. According to this figure, it can be seen that the density of the color toner patch P can be detected with high accuracy by the image density detection device 102 over the entire density range from low density to high density.

  FIG. 4 is a diagram illustrating the relationship between the wavelength of light and the reflectance when light is applied to the dark-color toner and light-color toner patch P in the present embodiment. According to this figure, it can be seen that the wavelength of light that becomes the maximum reflectance when light is irradiated differs between the dark color toner and the light color toner. This is because the reflectivity of the pigment and wax agent contained in each of the dark color toner and the light color toner is different, and / or the toner particle diameter and toner shape of the dark color toner and the light color toner are different.

  FIG. 5 is a diagram illustrating a relationship between the toner amount of the patch P and the output (sensor output) of the image density detection device 102 when the dark toner and the light toner patch P are irradiated with light in the present embodiment. According to this figure, when the dark toner and the light toner patch P are irradiated with light, even if the toner amount of the patch P is the same, the output of the image density detection device 102 differs for each of the dark toner and the light toner. I understand that. This is because, as shown in FIG. 4, the dark toner and the light toner have different wavelengths of light that give the maximum reflectance when light is irradiated. When the toner amounts of the dark color toner and the light color toner are both in the A region, the output of the image density detection device 102 is small, so that highly accurate density detection cannot be performed. For this reason, when the toner amounts of the dark color toner and the light color toner are both in the A region, control is performed so that the light emission intensity and / or the output gain of the image density detection device 102 is increased. As a result, when both the dark toner and the light toner are in the A region, the image density detector 102 can detect the density with high accuracy. When the toner amounts of the dark color toner and the light color toner are both in the B region, the output of the image density detection device 102 is large, but the output width of the image density detection device 102 with respect to the density difference is small, so high-precision density detection cannot be performed. . For this reason, when the toner amounts of the dark color toner and the light color toner are both in the B region, the light emission intensity and / or the output gain of the image density detection device 102 is controlled to be small. As a result, when both the dark toner and the light toner are in the B region, the image density detector 102 can detect the density with high accuracy. When the toner amounts of the dark color toner and the light color toner are both between the A region and the B region, the output of the image density detection device 102 with respect to the toner amount of the dark color toner is optimal, so that highly accurate density detection is possible. On the other hand, since the output of the image density detection device 102 with respect to the amount of light color toner is small, high-precision density detection cannot be performed. For this reason, when the toner amount of the light color toner is between the A region and the B region, control is performed so that the light emission intensity and / or the output gain of the image density detection device 102 is increased. As a result, when the toner amount of the light color toner is between the A area and the B area, the image density detecting device 102 can detect the density with high accuracy.

  FIG. 6 is a diagram showing the relationship between the input image density (CIN) of the dark toner and the light toner and the reflection intensity when the dark toner and the light toner are irradiated with light in the present embodiment. According to this figure, the reflection intensity varies depending on the input image density of the dark toner and the light toner, and the reflection intensity of the dark toner is higher than that of the light toner if the input image density is the same. I understand. Thereby, the density detection of the dark color toner and the light color toner can be performed without depending on the density of the patch P.

  FIG. 7 is a flowchart relating to dark toner and light toner type determination in the present embodiment. First, it is determined whether or not dark toner or light toner type is stored in the crumb (S100). If YES in S100, it is then determined whether or not the density detection condition of the image density detection device 102 is stored in the crumb (S102). If NO in S100, the chromaticity information of the dark toner or light toner patch P formed on the intermediate transfer belt 25 or the recording paper 34 is then used as the chromaticity detection device 103 (a chromaticity meter such as a CCD). ) To determine the toner color and store the determination result in the crumb (S104) (toner determination means). Here, the chromaticity detection device 103 may be arranged at a position facing the intermediate transfer belt 25 or may be arranged at the recording paper 34 discharge side (position where the chromaticity on the recording paper 34 can be detected). It may be arranged on the IIT side. Next, density detection condition creation / correction (FIG. 8) described later is executed (S106), and this routine is terminated. If YES in S102, this routine is terminated. If NO in S102, density detection condition creation / correction (FIG. 9) described later is executed (S108), and this routine is terminated. Note that the density detection conditions of the image density detection apparatus 102 are emission intensity and output gain.

  FIG. 8 is a flowchart regarding density detection condition creation / correction (light emission intensity determination means) in the present embodiment. When the type of dark color toner or light color toner to be used is not stored, the following routine is executed. First, an output gain that is a density detection condition of the image density detection apparatus 102 is set to a predetermined output gain (S200). Next, the light emission intensity [n], which is the density detection condition of the image density detection device 102, is set to a predetermined light emission intensity (the number of light emission intensity = n) (S202), and then the constant formed on the intermediate transfer belt 25 The density toner patch P is detected by the image density detector 102 (S204). Next, it is determined whether the light emission intensity [n] set in S202 is n or more (S206). If NO in S206, then n = n + 1 is executed (S208). Next, S202 is executed. If S202, S204, and S208 are repeatedly executed and YES is obtained in S206, then n = 1 is set (S210), the optimum light emission intensity is determined, and the optimum light emission intensity that is the determination result is determined. The program is stored in the crumb (S212), and this routine is terminated.

  FIG. 9 is a flowchart regarding density detection condition creation / correction (light emission intensity determination means) in the present embodiment. If the type of dark toner or light color toner to be used is stored, the following routine is executed. First, the output gain which is the density detection condition of the image density detection apparatus 102 is set to the stored output gain (S300). Next, the light emission intensity that is the density detection condition of the image density detection device 102 is set to the stored light emission intensity + α [n] (α number = n) (S302), and then formed on the intermediate transfer belt 25. The image density detecting device 102 detects a patch P having a certain density toner (S304). Next, it is determined whether α [n] set in S302 is greater than or equal to n (S306). If NO in S306, then n = n + 1 is executed (S308). Next, S302 is executed. If S302, S304, and S308 are repeatedly executed and YES is obtained in S306, then n = 1 is set (S310), the optimum light emission intensity is determined, and the optimum light emission intensity that is the determination result is determined. The program is stored in the crumb (S312), and this routine is terminated.

  FIG. 10 is a diagram showing the relationship between the input image density (CIN) and the optimum light emission intensity. In the present embodiment, the light emission intensity that is the density detection condition of the image density detection apparatus 102 is corrected to the optimum light emission intensity for each input image density.

  FIG. 11 is a diagram showing the relationship between the toner density (TC) and the optimum light emission intensity. In this embodiment, the light emission intensity, which is the density detection condition of the image density detection apparatus 102, is corrected to the optimum light emission intensity for each toner density.

  FIG. 12 is a diagram showing the relationship between the photoreceptor (PR) film thickness and the optimum light emission intensity. In the present embodiment, the light emission intensity, which is the density detection condition of the image density detection device 102, is corrected to the optimum light emission intensity for each photoconductor film thickness.

  FIG. 13 is a diagram showing the relationship between intermediate transfer member (IBT) degradation and optimum emission intensity. In the present embodiment, the light emission intensity, which is the density detection condition of the image density detection apparatus 102, is corrected to the optimum light emission intensity every time the intermediate transfer member is deteriorated.

As described above, in the present exemplary embodiment, the image density detection device 102 including the light emitting element 104 and the light receiving element 106, and the same color dark toner and light color toner having the same amount of toner but different reflection intensity of light emitted from the light emitting element The image density detecting device 102 detects the density of the dark toner and the light color toner patch P formed on the intermediate transfer belt 25 and corrects the image forming condition based on the detection result. The image forming apparatus includes density detection condition setting means for setting the light emission intensity and / or the output gain, which are density detection conditions of the image density detection apparatus 102, according to the dark color toner and the light color toner.
The dark toner and light toner patches P may be formed on the photosensitive drum 15 or the recording paper 34.

  Further, in the present embodiment, the toner cartridge has toner information storage means that is provided in the toner cartridge and stores information on the dark color toner and the light color toner, and the density detection condition setting means has the darkness information stored in the toner information storage means. The density detection condition is set based on the information on the color toner and the light color toner.

  In the present embodiment, the chromaticity information of the dark color toner and the light color toner patch P formed on the intermediate transfer belt 25 is detected by the chromaticity detection device 103 to determine the toner color, and the determination result is displayed. A toner determination unit provided in the toner cartridge for storing information on the dark color toner and the light color toner, and storing the information in the toner information storage unit stored in the toner determination unit; Density detection conditions are set based on the information on the dark color toner and the light color toner.

  In this embodiment, a toner information storage unit that is provided in a toner cartridge and stores information on the dark toner and the light toner, or a patch P of the dark toner and the light toner formed on the intermediate transfer belt 25. Toner detection by the chromaticity detection device 103 to determine the toner color, and the determination result stored in the toner information storage means provided in the toner cartridge for storing information on the dark color toner and the light color toner A density detection condition setting unit that forms a patch P of the dark color toner and the light color toner stored in the toner information storage unit on the intermediate transfer belt 25, and outputs an image density detection device with a predetermined output. In 102, the emission intensity is set in a plurality of stages, the patch P is detected, the optimum emission intensity is determined, and the emission intensity stored in the toner information storage means is stored. Has a determining means, for setting the density detection condition based on the dark-colored toner and the information light-colored toner stored in the toner information storing means for storing in the emission intensity determining unit.

  In the present embodiment, there is also provided an output gain correction means for correcting the output gain of the image density detecting device 102 within the output range of the image density detecting device set for each of the dark color toner and the light color toner.

  In this embodiment, the light emission intensity determination means is configured to input the input image image density, the toner density, the photosensitive film thickness, the environment, the developer usage status, and the intermediate transfer body usage status of the dark color toner and the light color toner patch P. The optimal emission intensity is stored.

  Further, in the present embodiment, the image density set for each of the input image image density, toner density, photoconductor film thickness, environment, developer usage status, and intermediate transfer body usage status of the dark color toner and light color toner patch P. Output gain correction means for correcting the output gain of the image density detection device 102 within the output range of the detection device 102 is provided.

Further, in the present embodiment, there is provided a patch fail determination threshold value calculation means for calculating a patch fail determination threshold value from the density detection condition for each of the dark color toner and the light color toner.
If the output of the image density detecting device 102 that detects the dark toner and the light toner patch P is the same or the difference is within an allowable range, the patch fail determination threshold (calculated value or fixed value) is set to the dark toner. And may be set in common for the light color toner.

  Further, in the present embodiment, the dark toner and the light toner patch P formed on the intermediate transfer belt 25 are detected based on the optimum density detection condition, and the image on the dark toner and the light toner patch P is detected. Patch file determination threshold value calculation means for calculating a patch file determination threshold value from the output of the density detection apparatus 102 is provided.

  As described above, according to the present exemplary embodiment, in the image forming apparatus having the same color dark toner and light color toner having the same toner amount but different reflection intensity of light emitted from the light emitting element, the dark color toner and the light color toner are increased. It is possible to accurately detect and control the density and gradation of an image.

  Further, according to the present embodiment, the density and gradation control of the image by detecting the dark color toner and the light color toner can be performed at a low cost by using one image density detection device 102.

  Further, according to the present embodiment, even with the dark color toner and the light color toner type that are not stored in the image forming apparatus, the dark color toner and the light color toner are detected, and the image density and gradation control are performed. it can. In addition, the color condition and physical properties of the toner may slightly change depending on the production time. As a result, it is necessary to reset the optimum density detection condition of the image density detection apparatus even if the same toner type is used due to the difference in manufacturing time. Therefore, even when there is a difference in the production time for all toner types, not only for dark and light toners, the image forming apparatus re-detects the toner patch, and resets the density detection conditions of the image forming apparatus, so that the image density and gradation are re-detected. The tone can be controlled with high accuracy.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

FIG. 1 is a diagram illustrating a tandem full-color printer as an image forming apparatus according to an embodiment. FIG. 2 is a diagram illustrating the image density detection device according to the embodiment. FIG. 3 is a diagram showing the relationship between the color toner patch density (CIN) and the output (sensor output) of the image density detector. FIG. 4 is a diagram illustrating the relationship between the wavelength of light and the reflectance when light is applied to the dark toner patch and the light toner patch in the embodiment. FIG. 5 is a diagram illustrating a relationship between the toner amount of the patch and the output (sensor output) of the image density detection apparatus when light is applied to the dark color toner and the light color toner patch in the embodiment. FIG. 6 is a diagram illustrating a relationship between the input image density (CIN) of the dark toner and the light toner and the reflection intensity when the dark toner and the light toner are irradiated with light in the embodiment. FIG. 7 is a flowchart relating to dark toner and light toner type determination in the embodiment. FIG. 8 is a flowchart regarding creation / correction of density detection conditions in the embodiment. FIG. 9 is a flowchart regarding density detection condition creation / correction according to the embodiment. FIG. 10 is a diagram showing the relationship between the input image density (CIN) and the optimum light emission intensity. FIG. 11 is a diagram showing the relationship between the toner density (TC) and the optimum light emission intensity. FIG. 12 is a diagram showing the relationship between the photoreceptor (PR) film thickness and the optimum light emission intensity. FIG. 13 is a diagram showing the relationship between intermediate transfer member (IBT) degradation and optimum emission intensity.

Explanation of symbols

1: full-color printer (image forming apparatus), 15: photosensitive drum (image carrier), 25: intermediate transfer belt (image carrier), 34: recording paper (recording medium), 102: image density detector, 103: Chromaticity detection device, 104: light emitting element, 106: light receiving element, P: patch

Claims (3)

Image density detection apparatus including light emitting element and light receiving element, and dark toner and light color toner of similar colors having different reflection intensity of light emitted from light emitting element even if toner amount is the same, on image carrier or recording medium In the image forming apparatus for detecting the density of the dark toner and the light color toner patch formed on the image density detecting device and correcting the image forming condition based on the detection result.
A density detection condition setting means for setting in response to the image light emission intensity is the concentration detection condition of the density sensing device and / or the output gain the dark color toner and light color toner,
A chromaticity detection device that detects chromaticity information of the dark color toner and light color toner patches formed on the image carrier or a recording medium;
The toner is determined based on the chromaticity information of the dark color toner and the light color toner patch detected by the chromaticity detection device, and the determination result is provided in the developing unit and the information of the dark color toner and the light color toner is stored. Toner determination means for storing in the toner information storage means for
The density detection condition setting unit sets the density detection condition based on the information on the dark color toner and the light color toner stored in the toner information storage unit stored in the toner determination unit. apparatus. The image forming apparatus according to claim 1 , further comprising an output gain correction unit configured to correct an output gain of the image density detection device within an output range of the image density detection device set for each of the dark color toner and the light color toner. An image density detecting device set according to at least one of the input image image density, toner density, photoconductor film thickness, environment, developer usage status, and image carrier usage status of the dark toner and light color toner patches. The image forming apparatus according to claim 2 , further comprising an output gain correction unit that corrects an output gain of the image density detection device within an output range.

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