JP2007322450A - Image forming apparatus - Google Patents

Abstract

Provided is an image forming apparatus that provides information on whether or not sensors can be reused and minimizes deterioration of density detection error without causing machine down immediately even when sensor contamination occurs. .
An image forming apparatus for controlling image density by detecting reflected light with an optical detection unit combining a light emitting unit and a light receiving unit with respect to an adhesion amount pattern formed on a detection target surface. The target detection unit 310 is the image forming apparatus 100 including the storage unit 310-3.
[Selection] Figure 10

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus using an electrophotographic system such as a copying machine or a laser beam printer, and more particularly to an image forming apparatus that detects image density by optical detection means and controls image density. .

Until now, new products have been released or lease contracts have expired, ranging from daily necessities and household appliances used in ordinary households to OA equipment such as personal computers, motorcycles, automobiles, copiers, and printers. It was destroyed before reaching the end of its useful life. And among those that have been discarded in this way, for example, household electrical appliances discharged from ordinary households are about 600,000 tons per year, and most of them have been reclaimed so far.
Therefore, in recent years, various recycling laws have been enacted from the viewpoint of global environmental conservation such as (1) reduction of resource and energy consumption, (2) reduction of final waste, and (3) prevention of harmful substances emission. .
Prior to the enactment of these laws and regulations, we have been working on a recycling-friendly design that makes it easy to disassemble / separate the collected products, and have established certain conditions for the quality status and production / operation history of the collected products. If it meets the requirements, reusable items are incorporated into the product again, and other items are separated and recycled as recycled materials.
If the operation history, which is a judgment material for determining whether or not to recycle, is a product itself, information such as the number of sheets passed and the operation time stored in the memory of the machine can be obtained. Since each part does not have a memory, there is no history information when it is removed from the product. Therefore, from the viewpoint of recycling / reuse, it is desired that every part incorporated in a product has its own history information. In addition, it is not possible to clearly determine whether or not reuse is possible until now, and even parts that have been sent to material recycling can be reused, and the environmental load can be greatly reduced.
Therefore, electronic parts such as sensors have been cited as parts that can be incorporated in products and have their own operation history.

There are various sensors built into copiers, ranging from inexpensive ones to very sophisticated ones, but the optical sensors that combine light emitting elements and light receiving elements are original paper size detection sensors and drums in the scanner system. There are density sensors and misregistration detection sensors that detect misregistration in the rotation system, feedback sensors that detect the speed of the intermediate transfer belt, and paper conveyance systems that are provided throughout the paper conveyance path, such as a paper feed sensor and a registration sensor. ing. Recently, there is a paper type detection sensor for determining the type of paper.
Among these many types of optical sensors, particularly expensive ones are a density sensor used for image density control and a position alignment sensor used for position alignment.
In addition, it has been required to store the sensor in the sensor and to store the information on whether or not reuse is possible (lighting time of the light emitting element, lifespan, number of times of recycling).

In addition, in conventional image forming apparatuses such as copying machines and laser beam printers using an electrophotographic system, in order to obtain a stable image density at all times, a toner patch for density detection is created on an image carrier such as a photoconductor, The patch density is detected by an optical detection means, and the development potential is changed based on the detection result. Specifically, the LD power, charging bias, and developing bias have been changed. In the case of the two-component development method, image density control is performed such that the maximum target adhesion amount becomes a target value by changing the toner density control target value in the developing device.
As a concentration sensor used for such control, a reflection type sensor in which “LED as a light emitting element” and “PD (photodiode) or PTr (phototransistor) as a light receiving element” are combined is generally known. The sensor configuration includes (1) a type that detects only specularly reflected light (FIG. 3, Patent Document 1, etc.), and (2) a type that detects only diffusely reflected light (FIG. 14, Patent Documents 2, 3). Others), (3) Types that detect both (FIG. 4, Patent Document 4, etc.), (4) Types in which a beam splitter is provided in the light emitting path / light receiving path (FIG. 15, Patent Documents 5 to 7) There is.
In any of these sensors that measure the patch density on the detection target surface, the detection target is a powder of static electricity such as toner, so that the sensor detection window may be contaminated with toner floating around. It was always exposed.

Therefore, regarding the sensor contamination problem, Patent Document 8 discloses that if the output voltage Vp of the sensor that receives the reflected light from the surface of the intermediate transfer belt is within a predetermined range, it is determined that the sensor is normal. A method for determining that the image is present is disclosed. In this disclosed example, the determination threshold value for dirt is provided on the output voltage side of the light receiving element. As described above, since the threshold value for contamination determination is provided at the light receiving element side output, there is a reference voltage (predetermined by control) in the light receiving element output voltage that is a comparison determination target for determining contamination. When the difference from the reference voltage exceeds a certain value (measurement S / N ratio) is NG, there is a merit that it is easy to perform the dirt determination.
However, if the device is made unusable when it falls below this threshold, the machine will be unusable until a service person is called to perform maintenance work. It was.
In addition, if the machine is not downed and only a warning is issued to the operation unit, etc., and the system can be used as it is, the density detection error is outside the allowable range, so the image density is different from the original target. There is a problem that there is a high possibility that the concentration will be controlled.

JP 2001-324840 A JP-A-5-249787 Japanese Patent No. 3155555 JP 2001-194443 A Japanese Patent No. 2729976 JP-A-10-221902 JP 2002-72612 A JP 2004-341142 A JP 2004-341230 A JP 2004-341231 A

  Therefore, the present invention has been made in view of the above problems, and its problem is to provide information on whether or not sensors can be reused, and even if sensor contamination occurs, the machine is not immediately brought down. An object of the present invention is to provide an image forming apparatus in which deterioration of density detection error is minimized.

The features of the present invention, which is a means for solving the above problems, are listed below.
The present invention provides an image forming apparatus that performs image density control by detecting reflected light with respect to an adhesion amount pattern formed on a surface to be detected by an optical detection unit that combines a light emitting unit and a light receiving unit. The target detection means is an image forming apparatus having a storage means. Note that there are means such as a sensor as the optical detection means.
The present invention is characterized in that the storage means stores history information and lifetime determination information.
The present invention is characterized in that the optical detection means has ID information for identifying itself.
According to the present invention, the characteristic value stored in the optical detection unit includes an initial characteristic value in a new use start state of the optical detection unit, a characteristic value obtained at the start of use after cleaning the optical detection unit, and the It is the remaining usable time calculated from the use time or lifetime of the optical detection means and the use time.
The present invention provides an image forming apparatus that performs image density control by detecting reflected light with respect to an adhesion amount pattern formed on a surface to be detected by an optical detection unit that combines a light emitting unit and a light receiving unit. The target detection means is characterized by having non-rewritable ID information for identifying itself.
According to the present invention, the characteristic value stored in the image forming apparatus includes the ID information of the optical detection unit, the initial characteristic value of the optical detection unit in a new use start state, and the start of use after cleaning the optical detection unit. It is characterized in that it is the remaining usable time calculated from the characteristic value sometimes obtained and the use time or lifetime of the optical detection means and the use time.
The present invention is characterized in that the characteristic value is a current value when the received light output is adjusted to a constant voltage, or a value corresponding thereto, or a dependent characteristic value obtained by arithmetic processing after adjusting the light emission output. To do.
The present invention is characterized in that the timing for determining whether the characteristic value needs to be updated (rewritten) is when the power of the image forming apparatus is turned on or when the cover of the image forming apparatus is opened or closed.
In the present invention, the condition for updating (rewriting) the initial characteristic value of the optical detection means is that the initial characteristic value of the optical detection means is an initial characteristic value in a new use start state of the optical detection means. Or the ID information stored in the image forming apparatus is different from the ID information held by the sensor.
In the present invention, the condition for updating (rewriting) the characteristic value after cleaning stored in the optical detection means is the current value when the light reception output is adjusted to a constant voltage, or a value corresponding thereto. In this case, in the comparison determination between the value stored in the sensor and the value obtained when the necessity determination of characteristic value update is performed, the value stored in the sensor> the necessity determination of characteristic value update is determined. If the characteristic value is a subordinate characteristic value obtained by calculation processing after the light emission output adjustment, the characteristic value is first updated after the characteristic value is updated. It is the timing of the arithmetic processing performed.
The present invention is characterized in that the use time update (rewrite) condition stored in the optical detection means is a timing at which a light emitting means that is lit is extinguished.
The present invention is characterized in that a sensor state check is performed based on a predetermined condition, and if the sensor is determined to be dirty, the sensor state is reported.
According to the present invention, when the image forming apparatus has a cleaning member that can be operated by the user, the image is displayed on the operation unit and displayed on a screen on a PC such as a printer driver or a driver utility tool. When the image forming apparatus includes a cleaning member control device, a cleaning operation is executed. Further, when the image forming apparatus is not connected to the network, it notifies the call center (contacts a service person).

  The present invention provides information for determining whether or not sensors can be reused by the means for solving the problem, and even if sensor contamination occurs, the deterioration of the density detection error is minimized without causing the machine to go down immediately. Thus, it is possible to provide an image forming apparatus that is pressed down.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

  The present embodiment is an application example to a tandem type full-color electrophotographic copying machine (hereinafter simply referred to as “copying machine”) as an image forming apparatus. FIG. 1 is a schematic configuration diagram showing the entire copying machine of the present embodiment. The copying machine includes a copying machine main body 100 that forms an image, a paper feeding device 200 on which the copying machine main body 100 is mounted and that supplies transfer paper 5 as a recording material to the copying machine main body 100, and a copying machine main body. A scanner 300 that is mounted on 100 and reads a document image, and an automatic document feeder (ADF) 400 that is mounted on the scanner 300 are provided. The copying machine main body 100 is provided with a manual feed tray 6 for manually feeding the transfer paper 5 and a paper discharge tray 7 for discharging the transfer paper 5 on which an image has been formed.

FIG. 2 is an enlarged view showing the configuration of the copying machine main body 100. The copying machine main body 100 is provided with an endless belt-like intermediate transfer belt 10 which is an intermediate transfer member. The intermediate transfer belt 10 is made of polyimide, which is a material having excellent mechanical characteristics in order to prevent misalignment due to belt elongation, and has high image quality and high stability, that is, a temperature and humidity environment. Carbon is dispersed as a resistance adjusting agent in order to always obtain stable transfer performance regardless of the resistance. Therefore, the belt color is black.
The intermediate transfer belt 10 is rotated in the clockwise direction in FIG. 2 while being stretched around the three support rollers 14, 15, and 16.

As shown in FIG. 2, four images of yellow, cyan, magenta, and black are formed on the belt stretch portion between the first support roller 14 and the second support roller 15 of the support rollers 14, 15, and 16. The forming units 18Y, 18C, 18M, and 18K are arranged side by side. A density detection sensor 310 for detecting density patches formed on the intermediate transfer belt is attached to the belt stretch portion between the second support roller 15 and the third support roller 16.
As shown in FIG. 1, two density sensors are provided in the longitudinal direction of the photosensitive member. The front side sensor is provided for detecting a color toner pattern, and the back side sensor is provided for detecting a black toner pattern. Yes. This black toner pattern detection sensor is a regular reflection type sensor shown in FIG. 3, and the color toner pattern detection sensor is a regular reflection + diffuse reflection type sensor shown in FIG. Both of these sensors use a GaAs infrared light emitting diode having a peak light emission wavelength: λp = 950 nm for an LED as a light emitting element, and a Si phototransistor having a peak light receiving sensitivity: 800 nm for a light receiving element.
The distance between the sensor and the belt that is the detection target surface (detection distance) is 5 mm.
Furthermore, in addition to the density sensor, the sensor board is provided with three misregistration sensors 310-2 for measuring the misregistration amount of each color of CMYK at the front, center and back, and further relates to the present invention. Memory: 310-3 is provided.
In this memory, data shown in Table 1 can be stored as stored information.

  An exposure device 21 is provided above the image forming units 18Y, 18C, 18M, and 18K as shown in FIG. The exposure apparatus 21 emits writing light by driving a semiconductor laser (not shown) by a laser control unit (not shown) based on the image information of the document read by the scanner 300, and each image forming unit. This is for forming an electrostatic latent image on the photoconductive drums 20Y, 20C, 20M, and 20K as image carriers provided on 18Y, 18C, 18M, and 18K. Here, the emission of the writing light is not limited to the laser, but may be an LED, for example.

The configuration of the image forming units 18Y, 18C, 18M, and 18K will be described. In the following description, the image forming unit 18K that forms a black toner image will be described as an example, but the other image forming units 18Y, 18C, and 18M have the same configuration. Here, FIG. 5 is an enlarged view showing a configuration of two adjacent image forming units. In addition, in the code | symbol in a figure, the symbol of "M" and "K" which shows distinction of a color is abbreviate | omitted, and a symbol is abbreviate | omitted suitably also in the following description.
In the image forming unit 18, a charging device 60, a developing device 61, a photoconductor cleaning device 63, and a charge removal device 64 are provided around the photoconductor drum 20. Further, a primary transfer device 62 is provided at a position facing the photosensitive drum 20 via the intermediate transfer belt 10.
The charging device 60 is of a non-contact charging type employing a charging roller, and uniformly charges the surface of the photosensitive drum 20 by applying a voltage with a predetermined gap in the photosensitive drum 20. As the charging device 60, a non-contact charging type using a non-contact scorotron charger or the like can be used.

  The developing device 61 uses a two-component developer composed of a magnetic carrier and a non-magnetic toner. The developing device 61 can be broadly divided into a stirring unit 66 and a developing unit 67 provided in the developing case 70. In the agitating unit 66, a two-component developer (hereinafter simply referred to as “developer”) is conveyed while being agitated and supplied onto a developing sleeve 65, which will be described later, as a developer carrying member. The stirring unit 66 is provided with two parallel screws 68, and a partition plate is provided between the two screws 68 for partitioning so that both ends communicate with each other. Further, a toner concentration sensor 71 for detecting the toner concentration of the developer in the developing device 61 is attached to the developing case 70. On the other hand, in the developing unit 67, the toner of the developer attached to the developing sleeve 65 is transferred to the photosensitive drum 20. The developing portion 67 is provided with a developing sleeve 65 that faces the photosensitive drum 20 through the opening of the developing case 70, and a magnet (not shown) is fixedly disposed in the developing sleeve 65. Further, a doctor blade 73 is provided so that the tip approaches the developing sleeve 65.

  In the developing device 61, the developer is conveyed and circulated while being stirred by two screws 68, and is supplied to the developing sleeve 65. The developer supplied to the developing sleeve 65 is pumped and held by a magnet. The developer pumped up by the developing sleeve 65 is conveyed along with the rotation of the developing sleeve 65 and is regulated to an appropriate amount by the doctor blade 73. The regulated developer is returned to the stirring unit 66. Thus, the developer transported to the developing area facing the photosensitive drum 20 is brought into a spiked state by the magnet and forms a magnetic brush. In the developing region, a developing electric field for moving the toner in the developer to the electrostatic latent image portion on the photosensitive drum 20 is formed by the developing bias applied to the developing sleeve 65. As a result, the toner in the developer is transferred to the electrostatic latent image portion on the photosensitive drum 20, and the electrostatic latent image on the photosensitive drum 20 is visualized to form a toner image. The developer that has passed through the developing region is transported to a portion where the magnetic force of the magnet is weak, and thus is separated from the developing sleeve 65 and returned to the stirring unit 66. When the toner concentration in the stirring unit 66 becomes light by repeating such an operation, the toner concentration sensor 71 detects this, and the toner is supplied to the stirring unit 66 based on the detection result.

The primary transfer device 62 employs a transfer roller and is installed so as to be pressed against the photosensitive drum 20 with the intermediate transfer belt 10 interposed therebetween. The primary transfer device 62 may not be a roller shape, but may be a conductive brush shape, a non-contact corona charger, or the like.
The photoconductor cleaning device 63 includes a cleaning blade 75 made of, for example, polyurethane rubber, which is disposed so that the front end is pressed against the photoconductor drum 20. In the present embodiment, a conductive fur brush 76 that contacts the photosensitive drum 20 is used in combination to improve the cleaning performance. The toner removed from the photoconductor drum 20 by the cleaning blade 75 and the fur brush 76 is accommodated in the photoconductor cleaning device 63.
The static eliminator 64 is composed of a static elimination lamp, and irradiates light to initialize the surface potential of the photosensitive drum 20.
The image forming unit 18 is provided with a potential sensor 320 corresponding to each photosensitive drum 20. The potential sensor 320 is provided so as to face the photosensitive drum 20 and detects the potential of the surface of the photosensitive drum 20.

  Specific settings of the image forming unit 18 will be described. The diameter of the photosensitive drum 20 is 60 mm, and the photosensitive drum 20 is driven at a linear speed of 282 mm / s. The developing sleeve 65 has a diameter of 25 mm, and the developing sleeve 65 is driven at a linear speed of 564 mm / s. The charge amount of the toner in the developer supplied to the development area is preferably in the range of about −10 to −30 μC / g. The development gap, which is the gap between the photosensitive drum 20 and the development sleeve 65, can be set in the range of 0.5 to 0.3 mm, and the development efficiency can be improved by reducing the value. Further, the photosensitive layer of the photosensitive drum 20 has a thickness of 30 μm, the beam spot diameter of the optical system of the exposure device 21 is 50 × 60 μm, and the light quantity is about 0.47 mW. As an example, the surface of the photosensitive drum 20 is uniformly charged to −700 V by the charging device 60, and the potential of the electrostatic latent image portion irradiated with the laser by the exposure device 21 is −120 V. On the other hand, the developing bias voltage is set to -470V, and a developing potential of 350V is secured. Such process conditions are appropriately changed according to the result of the potential control.

In the image forming unit 18 having the above configuration, first, the surface of the photosensitive drum 20 is uniformly charged by the charging device 60 as the photosensitive drum 20 rotates. Next, based on the image information read by the scanner 300, the exposure light is irradiated from the exposure device 21 to form an electrostatic latent image on the photosensitive drum 20. Thereafter, the electrostatic latent image is visualized by the developing device 61 to form a toner image. This toner image is primarily transferred onto the intermediate transfer belt 10 by the primary transfer device 62. The transfer residual toner remaining on the surface of the photosensitive drum 20 after the primary transfer is removed by the photosensitive member cleaning device 63, and thereafter, the surface of the photosensitive drum 20 is discharged by the static eliminating device 64, and the next image formation is performed. Provided.
Next, as shown in FIG. 2, a secondary transfer roller 24 as a secondary transfer device is provided at a position facing the third support roller 16 among the support rollers. When the toner image on the intermediate transfer belt 10 is secondarily transferred onto the transfer paper 5, the secondary transfer roller 24 is pressed against the portion of the intermediate transfer belt 10 wound around the third support roller 16. Next transfer is performed. The secondary transfer device may not be configured using the secondary transfer roller 24 but may be configured using, for example, a transfer belt or a non-contact transfer charger. The secondary transfer roller 24 is in contact with a roller cleaning unit 91 that cleans toner adhering to the secondary transfer roller 24.

Further, an endless belt-like transport belt 22 is stretched between the two rollers 23a and 23b on the downstream side of the secondary transfer roller 24 in the transport direction of the transfer paper 5. Further, a fixing device 25 for fixing the toner image transferred onto the transfer paper 5 is provided further downstream in the transport direction. The fixing device 25 has a configuration in which a pressure roller 27 is pressed against a heating roller 26. Further, a belt cleaning device 17 is provided at a position facing the second support roller 15 among the support rollers of the intermediate transfer belt 10. The belt cleaning device 17 is for removing residual toner remaining on the intermediate transfer belt 10 after the toner image on the intermediate transfer belt 10 is transferred to the transfer paper 5.
Further, as shown in FIG. 1, the copying machine main body 100 is provided with a conveyance path 48 that guides the transfer paper 5 fed from the paper feeding device 200 to the paper discharge tray 7 via the secondary transfer roller 24. Along the conveyance path 48, a conveyance roller 49a, a registration roller 49b, a discharge roller 56, and the like are provided. A switching claw 55 is provided on the downstream side of the transport path 48 to switch the transport direction of the transfer paper 5 after transfer to the paper discharge tray 7 or the paper reversing device 93. The paper reversing device 93 reverses the transfer paper 5 and sends it again toward the secondary transfer roller 24. Further, the copying machine main body 100 is provided with a manual feed path 53 that joins from the manual feed tray 6 to the transport path 48, and the transfer paper 5 set in the manual feed tray 6 is located upstream of the manual feed path 53. A sheet feeding roller 50 and a separation roller 51 are provided for feeding sheets one by one.

The paper feeding device 200 includes a plurality of paper feeding cassettes 44 that store the transfer paper 5, a paper feeding roller 42 and a separation roller 45 that feed the transfer papers stored in these paper feeding cassettes 44 one by one, and the fed transfer paper Is composed of a transport roller 47 that transports the paper along the paper feed path 46. The paper feed path 46 is connected to the conveyance path 48 of the copying machine main body 100.
The scanner 300 will be described with reference to FIG. In the scanner 300, first and second traveling bodies 33 and 34 mounted with a document illumination light source and a mirror reciprocate in order to read and scan a document (not shown) placed on the contact glass 31. To do. The image information scanned by the traveling bodies 33 and 34 is collected by the imaging lens 35 on the imaging surface of the reading sensor 36 installed behind the imaging lens 35 and read by the reading sensor 36 as an image signal.

FIG. 6 is a block diagram showing an electrical connection of each unit provided in the copying machine of the present embodiment. As shown in FIG. 6, the copying machine of the present embodiment is provided with a main control unit 500 having a computer configuration, and the main control unit 500 drives and controls each unit. The main control unit 500 includes a ROM (Read Only Memory) 503 that stores in advance fixed data such as a computer program via a bus line 502 in a CPU (Central Processing Unit) 501 that executes various calculations and drive control of each unit. A RAM (Random Access Memory) 504 that functions as a work area for storing various data in a rewritable manner is connected.
The ROM 503 stores a conversion table (not shown) that stores information related to conversion of the output value of the toner density sensor 310 into the toner adhesion amount per unit area.
Connected to the main controller 500 are each part of the copying machine main body 100, a paper feeding device 200, a scanner 300, and an automatic document feeder 400. Here, the toner density sensor 310 and the potential sensor 320 of the copying machine main body 100 send the detected information to the main control unit 500.

Next, the operation of the copier of this embodiment will be described. When copying a document using the copying machine having the above configuration, first, the document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 31 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it. Thereafter, when the user presses a start switch (not shown), when the document is set on the automatic document feeder 400, the document is conveyed onto the contact glass 31. Then, the scanner 300 is driven and the first traveling body 33 and the second traveling body 34 start traveling. Thereby, the light from the first traveling body 33 is reflected by the document on the contact glass 31, and the reflected light is reflected by the mirror of the second traveling body 34 and guided to the reading sensor 36 through the imaging lens 35. . In this way, the image information of the original is read.
When the start switch is pressed by the user, a drive motor (not shown) is driven, and one of the support rollers 14, 15, 16 is rotationally driven to rotate the intermediate transfer belt 10. At the same time, the photosensitive drums 20Y, 20C, 20M, and 20K of the image forming units 18Y, 18C, 18M, and 18K are also rotationally driven. Thereafter, based on the image information read by the reading sensor 36 of the scanner 300, writing light is emitted from the exposure device 21 onto the photosensitive drums 20Y, 20C, 20M, and 20K of the image forming units 18Y, 18C, 18M, and 18K. Each is irradiated. As a result, electrostatic latent images are formed on the respective photosensitive drums 20Y, 20C, 20M, and 20K, and are visualized by the developing devices 61Y, 61C, 61M, and 61K. Then, yellow, cyan, magenta, and black toner images are formed on the photosensitive drums 20Y, 20C, 20M, and 20K, respectively.

Each color toner image formed in this way is primarily transferred by the primary transfer devices 62Y, 62C, 62M, and 62K so as to sequentially overlap each other on the intermediate transfer belt 10. As a result, a composite toner image in which the toner images of the respective colors overlap is formed on the intermediate transfer belt 10. The transfer residual toner remaining on the intermediate transfer belt 10 after the secondary transfer is removed by the belt cleaning device 17.
When the user presses the start switch, the paper feed roller 42 of the paper feed device 200 corresponding to the transfer paper 5 selected by the user rotates, and the transfer paper 5 is sent out from one of the paper feed cassettes 44. The transferred transfer paper 5 is separated into one sheet by the separation roller 45 and enters the paper feed path 46, and is conveyed by the conveyance roller 47 to the conveyance path 48 in the copying machine main body 100. The transfer sheet 5 thus transported is stopped when it abuts against the registration roller 49b.

  The registration roller 49 b starts to rotate in accordance with the timing at which the composite toner image formed on the intermediate transfer belt 10 as described above is conveyed to the secondary transfer unit facing the secondary transfer roller 24. The transfer paper 5 sent out by the registration roller 49b is sent between the intermediate transfer belt 10 and the secondary transfer roller 24, and the secondary transfer roller 24 causes the composite toner image on the intermediate transfer belt 10 to be transferred onto the transfer paper 5. Secondary transfer is performed. Thereafter, the transfer paper 5 is conveyed to the fixing device 25 while being attracted to the secondary transfer roller 24, and heat and pressure are applied by the fixing device 25 to perform a toner image fixing process. The transfer paper 5 that has passed through the fixing device 25 is discharged to the paper discharge tray 7 by the discharge roller 56 and stacked. When image formation is performed also on the back surface of the surface on which the toner image is fixed, the transfer paper 5 that has passed through the fixing device 25 is switched by the switching claw 55 and sent to the paper reversing device 93. The transfer paper 5 is then reversed and guided to the secondary transfer roller 24 again.

  The density sensor that has been used in conventional monochrome machines has only one sensor as shown in FIG. 3 mounted on a single substrate. However, in recent years, full-color copying and full-color printers have become mainstream. In particular, in the case of a density sensor mounted on a quadruple tandem system device, as shown in FIG. 7, two types of alignment detection sensors and one density sensor are mounted on one substrate. In order to further shorten the color adjustment time and to process the density adjustment of each color in parallel, a sensor shown in FIG. 8 in which four density sensors are arranged in parallel is manufactured. As the sensor module assembled on the sensor substrate becomes highly functional in this way, the environmental load in manufacturing the sensor is proportionally higher. Therefore, by making this reusable, a high environmental load reduction effect can be obtained.

These concentration sensors generally use LEDs as light-emitting elements and PD (photodiodes) and PTr (phototransistors) as light-receiving elements. The LEDs as light-emitting elements have increased lattice defects due to energization, resulting in increased luminous intensity. Has the property of gradually decreasing. The amount of decrease in luminous intensity varies depending on the material, but in many cases, the amount of decrease in luminous intensity increases as the current value increases, depending on the current flowing through the LED, that is, the forward current. FIG. 9 shows data of the luminous intensity remaining rate with respect to the LED operation time (= light emission time). Thus, the LED light quantity decrease rate increases as the current value increases, and the deterioration proceeds more rapidly as the ambient temperature increases.
Therefore, the sensor life of a concentration sensor that uses LEDs as light emitting elements is determined by the current flowing through the LEDs and the total lighting time. If this is stored in the sensor itself, a reasonable judgment can be made when determining reuse. Is possible.
Therefore, it is necessary to store the total lighting time of the sensor light emitting element somewhere, but if it is stored in the main body of the apparatus, there is no problem if the number of recycling is limited to one time. If it is desired to recycle three times, the sensor life on a time basis cannot be known unless the total lighting time of the light emitting element is stored in the sensor itself.
Even if the total lighting time of the LED exceeds the lifetime, the LED is lit as it is and there is a possibility that it can be used as a sensor. However, since the operation guarantee as a part of the sensor module is defined by the lighting time of the LED, it is a sufficiently reasonable judgment basis to determine whether recycling is possible based on the total LED lighting time of the sensor.

Next, an explanation will be given of an improvement with respect to performance degradation when the optical sensor is contaminated.
If the output voltage decreases due to contamination (when the S / N ratio of the measurement decreases), the light intensity can be adjusted immediately without stopping the machine to ensure the measured S / N as originally intended. A decrease in detection error can be prevented.
In this case, since the light emission output side adjustment is performed so that the light reception output of the sensor is always constant, the dirt determination is performed on the characteristic value on the light emission output side, that is, the current value of the LED, or a value corresponding thereto (such as a PWM value). ).
However, when the determination is made based on the output on the light emission side in this way, there is a problem as to which value should be used as the comparison determination target for the dirt determination.
When performing dirt detection on the light receiving output side, the “measured current value is compared with the“ output voltage when adjusted to a predetermined output voltage by adjusting the light amount, or the output threshold value obtained from the output voltage ”. The contamination was determined by comparing how much the “output voltage” was.
However, when the determination is made on the light emission output side, the light emission output is an output value (subordinate value) obtained as a result of adjusting the amount of light so that the light reception output becomes a certain constant value. There can be no such reference value. Therefore, in order to perform the determination, it is necessary to remember the past light emission output to be compared with the determination.

Therefore, “light emission output when the sensor is new” is used as a comparison target of the dirt determination.
When sensor contamination occurs, light entering the light receiving element is reduced by the contamination, so that the light emission output is adjusted to a high value to compensate for this.
Using this relationship, if the dirt determination is “light emission output (current value) −light emission output (initial value)> light emission output threshold value”, it may seem that the dirt determination is possible, but the LED light emission to be adjusted is adjusted. Factors such as sensor window contamination and light-emitting element (LED) deterioration over time can be considered as factors that increase the output. If the “light emission output when the sensor is new” is used, there is a possibility of making an erroneous determination that the sensor is dirty over time.
In order to prevent the erroneous determination that the light emitting element is deteriorated with time, the comparison target of the dirt determination may be “light emission output immediately after cleaning the sensor” instead of “light emission output when the sensor is new”.
In order to specify that the light emission output acquired here is the light emission output immediately after cleaning the sensor, it is necessary to know that the cleaning has been performed. In any case, the light output is an increasing function with respect to time, and if the adjustment is performed immediately after cleaning, the light output decreases (becomes the only decreasing function). It can be identified. Therefore, it seems that all the problems are solved if the stain determination is “light emission output (current value) −light emission output (minimum value)> light emission output threshold value”.

However, this comparison determination is valid only when the past light emission output value to be compared is always the light emission output of the same sensor, and in the event that the sensor has to be replaced for some reason This relationship does not hold. This is because both the light emitting element and the light receiving element constituting the density sensor have output variations of the elements.
Here, in order to clarify the output variation of the elements, several lots (1 lot = 197 pieces) of LEDs (light emitting elements) and PTr (light receiving elements) are evaluated by output measurement according to the following method. The result of having performed is shown.

[Light emitting element side]
Using the sensor head shown in FIG. 3, Vcc = 5V, LED current: If = 14.2 mA, and the light receiving element fixed, the light emitting elements are sequentially replaced, and the light receiving element is irradiated with light on a certain reference plate Photocurrent: Measure IL and determine the magnitude of the light output.
[Light receiving element side]
Using the sensor head shown in FIG. 3, Vcc = 5V, LED current: If = 14.2 mA, light emitting element is fixed, and the light receiving elements are sequentially replaced, and the light receiving element is irradiated with light on a certain reference plate. Photocurrent: Measure IL and determine the magnitude of light reception sensitivity.
The measurement results are shown in Table 2.

From Table 2, the output variation is slightly less than twice on the light emitting element side and slightly less than four times on the light receiving element side. That is, in order to perform the dirt determination based on the light emission output, information that the sensor has been replaced, information on the light emission output of the sensor (immediately after cleaning), and information on the light emission output (current value) of the sensor are required.
As described above, in order not to deteriorate the density detection error even when the sensor is contaminated (in order not to reduce the S / N ratio of the measurement), the sensor light receiving output side is controlled so as to be always constant (that is, When the dirt is generated and the output is reduced, the light emission side output is increased), and the dirt judgment is performed based on the light emission side output characteristic value. In addition, the necessary information is the above item.

Next, potential control called self-check, which is image density control performed by the CPU 501 of the present embodiment based on a computer program, will be described.
This self-check processing routine is performed under conditions of a certain number of sheets and every certain time when the density sensor is replaced and the power is turned on.
FIG. 10 is a plan view showing the positional relationship between the gradation pattern transferred onto the intermediate transfer belt 10 and the density sensor attached facing the gradation pattern, and FIG. 11 shows the toner adhesion amount with respect to the developing potential during potential control. FIG. 12 is a schematic diagram showing a potential control table.

Here, the procedure when the power is turned on is shown.
First, when the power is turned on, the ID information stored in Address 1 of the concentration sensor internal memory 310-3 is compared with the sensor ID information stored in the main unit internal memory (RAM) 504.
Here, if the in-body ID information does not match the sensor ID information, it is determined that the sensor has been replaced, a sensor replacement flag is set, and potential control is executed.
If the ID information matches, the lifetime is determined by checking the LED lighting time stored in the sensor memory 310-3. If the LED lighting time exceeds the lifetime, the sensor lifetime is determined. The sensor is notified to the call center via the network.
In addition, this LED lighting time does not use the exact life time as a threshold value, but considers the time lag from when the information is notified to the call center until the time when the service person actually replaces the sensor. It is desirable to set a time that is several hours shorter than the lifetime.
In consideration of the abnormal termination of the process for some reason during the potential control, the ID information stored in the internal memory is not rewritten (updated) at this point.
If the in-body ID information matches the sensor ID information, the fixing temperature of the fixing device 25 is detected as a potential control execution condition when the power is turned on. Based on the input signal from the fixing temperature sensor, it is determined whether or not the fixing temperature of the fixing device 25 exceeds 100 ° C., and the potential control is executed when the fixing temperature of the fixing device 25 is 100 ° C. or lower.
When the temperature exceeds 100 ° C., the potential control is not executed.

In the potential control, the offset voltages (Voffset_reg, Voffset_dif) of the two density sensors are first measured before starting the plotter, and the plotter is started up after the measurement is completed. In this plotter start-up operation, as shown in FIG. 13, activation of motor loads such as each photosensitive drum motor, intermediate transfer belt motor, secondary transfer motor, etc., and charging, development, and transfer bias are performed in accordance with a predetermined image forming timing. Control load startup operation processing necessary for image forming operation such as startup operation is performed.
Further, as shown in FIG. 13, in this start-up operation process, the P sensor LED is turned on in synchronization with the start timing of the intermediate transfer motor, and at this time, a timer value for measuring the lighting time of the P sensor LED. To get.

  Next, about 3 seconds after the LED light output is stabilized, the regular reflection light (Vsg_reg) from the background portion (surface) of the intermediate transfer belt 10 is within a predetermined range (4.0 ± 0.2 V). Thus, the LED light emission amount is adjusted (referred to as Vsg adjustment). After adjusting the amount of light, the belt background output (Vsg_reg, Vsg_dif) is stored in the main body RAM.

Sensor dirt judgment After adjusting the light quantity, the LED current (current value) stored in the sensor memory is compared with the LED current (minimum value), and the following formula “LED current (current value)-LED current (minimum) If “value)> 5 mA” is satisfied, it is determined that the sensor is dirty, and a sensor dirty notification is sent to the call center via the network. As soon as the notification is given, the service person is contacted and the cleaning work is performed by the service person.
Although the threshold value is set to 5 mA in the above formula, what is important in the above formula is that it defines the magnitude relationship between both sides, and how much the threshold value is set depends on the image forming apparatus. What is necessary is just to set suitably according to the tolerance with respect to the stain | pollution | contamination of.
The above equation can also be rewritten as follows.
{LED current (current value) −LED current (minimum value)} / LED current (minimum value) × 100> 20
Here, the unit is%, and 20 indicates a stain determination threshold value: 20%.
In this case, for example, when the LED current (minimum value) is 10 mA and the LED current (current value) is 11 mA, (11−10) / 10 × 100 = 10% <stain determination threshold: 20% Therefore, although it is not determined that it is still dirty, if the LED current (current value) increases to 13 mA, (13−10) / 10 × 100 = 30> stain determination threshold: 20% Therefore, it is determined that the sensor is dirty.
Since the image forming apparatus according to the present embodiment does not have a user-operable cleaning mechanism, the notification is made via the network. However, if the sensor can be cleaned by the user himself / herself, the image forming process is performed. There may be a method of displaying on the operation unit of the apparatus or displaying it on a screen (printer driver or driver utility screen) on an external apparatus terminal such as a PC connected thereto to promote cleaning.

Sensor life determination After the sensor contamination is determined, the LED current (upper limit value) stored in the sensor memory is compared with the LED current (current value), and the following formula “LED current (current value)> LED current (upper limit) Value) ”, the LED current upper limit abnormality counter in the sensor memory is incremented by one. If the above equation does not hold, reset the LED current upper limit error counter (write zero).
If the count value after the count-up exceeds three times, that is, if a continuous LED current upper limit abnormality occurs three times, it is determined that the sensor life is reached, and a sensor replacement notification is sent to the call center via the network.

After this Vsg adjustment is completed, an electrostatic latent image having a gradation pattern is formed on each photosensitive drum 20. The formation positions of the gradation patterns of the respective colors are positions corresponding to the longitudinal positions of the two P sensors shown in FIG. 10 (for C, M, and Y, 40 mm in front of the image center, and for K, the image center. Image on the back side 40mm position). In the present embodiment, 10 gradation patterns (each patch size is 15 × 20 mm) are formed at a predetermined interval of 10 mm.
In the next step, the output value of the potential sensor 320 for these gradation pattern portion potentials on the photosensitive drum 20 is read and stored in the RAM 504. Further, the development potential is calculated from this potential output and the development bias at the time of pattern image formation. The electrostatic latent images formed on the photosensitive drum 20 are developed and visualized by the black developing device 61K, the cyan developing device 61C, the magenta developing device 61M, and the yellow developing device 61Y, respectively. It is an image.
Next, the CPU 501 performs toner adhesion amount detection by the P sensor 310 for the gradation pattern formed on the intermediate transfer belt 10. In this toner adhesion amount detection, the specular reflection light output (Vsp_reg) and diffuse reflection light output (Vsp_dif) of the P sensor 310 for the patch pattern which is a toner image of each color are all stored in the RAM 504 (10 patches × 4 colors). .

Next, the toner adhesion amount is calculated.
This adhesion amount calculation algorithm is different because the black toner detection sensor and the color toner detection sensor have different sensor configurations.
First, the black toner patch adhesion amount conversion process will be described.
The black toner adhesion amount calculation calculates the output ratio (Vsp / Vsg) of the belt background portion output (Vsg) and the pattern portion output (Vsp) shown in the prior art, and this is stored in the ROM (not shown). The adhesion amount is calculated by referring to the adhesion amount conversion table.
Next, color toner patch adhesion amount conversion processing will be described.
The meanings of symbols (abbreviations) in the following explanation are as follows. Vsg is an output voltage of the transfer belt background portion, Vsp is an output voltage of each pattern portion, Voffset is an offset voltage (output voltage at the time of LED_OFF), _reg. Is a specular reflection light output (abbreviation of Regular Reflection), _dif. Is a diffuse reflected light output (abbreviation of Diffuse Reflection), and [n] is an array variable having n elements. The terminology relating to the color of JIS Z8105 is referred to.

STEP 1 ΔVsp and ΔVsg are calculated by data sampling.
First, the difference from the offset voltage is calculated for all points [n] for both the regular reflection light output and the diffuse light output.
<Processing formula>
Regular reflection light output increment: ΔVsp_reg. [N] = Vsp_reg. [N] -Voffset_reg.
Diffuse reflected light output increment: ΔVsp_dif. [N] = Vsp_dif. [N] -Voffset_dif.

STEP2 Calculate α which is a sensitivity correction coefficient.
ΔVsp_reg. Determined in STEP 1 [N], ΔVsp_dif. [N], ΔVsp_reg. [N] / ΔVsp_dif. [N] is calculated, and the coefficient α multiplied by the diffused light output (ΔVsp_dif [n]) is calculated when performing the component decomposition of the regular reflection light output in STEP3.
<Processing formula>
α = min (ΔVsp_reg [n] / Vsp_Dif. [n])

STEP3 Component decomposition of specular reflection light.
The component decomposition of the regular reflection light output is performed by the following equation.
<Processing formula>
Diffuse light component of regular reflection light output: ΔVsp_reg. _Dif. [N] = ΔVsp_dif. [N] × α
Regular reflection component of regular reflection light output: ΔVsp_reg. _Reg. [N] = ΔVsp_reg. [N] -ΔVsp_reg. _Dif. [N]

STEP4 Normal reflection light output_regular reflection component normalization.
Next, the ratio of each pattern portion output to the belt background portion output is taken and converted into a normalized value from 0 to 1.
<Processing formula>
Normalized value: β [n] = ΔVsp_reg. _Reg. / ΔVsg_reg. _Reg (= transfer belt background exposure rate)

(Step 5) Correction of background fluctuation of diffused light output.
Next, a process of removing [diffused light output component from the belt background portion] from [diffused light output voltage] is performed.
<Processing formula>
Diffused light output after correction: ΔVsp_dif ′ = [diffused light output voltage] − [belt background output] × [normalized value of specular reflection component]
= ΔVsp_dif (n) −ΔVsg_dif × β (n)

STEP6 Sensitivity correction of diffused light output.
Plot the diffused light output after correcting the fluctuation of the background against the normalized value of the specularly reflected light (regular reflection component), and obtain the sensitivity of the diffused light output from the linear relationship in the low adhesion amount area. Correction is made so as to achieve a predetermined target sensitivity.
Here, the sensitivity of the diffused light output is the slope of the straight line calculated by the following equation, and the diffused light output after correcting the background fluctuation of a certain normalized value (here, when 0.3) 1.2), a correction coefficient for multiplying the current inclination is calculated and corrected.
1. The slope of the straight line is obtained by the method of least squares.
Straight line slope = Σ (x [i] −X) (y [i] −Y) / Σ (x [i] −X) ²
y-intercept: = Y−straight line × X
x [i]: regular reflection light_normalization value of regular reflection component, X: regular reflection light_average value of normalization value of regular reflection component y [i]: diffused light output after background portion fluctuation correction, Y: background Average value of diffused light output after partial fluctuation correction However, the range of x used for calculation is 0.06 ≦ x ≦ 1
In the present embodiment, the lower limit value of the range of x used for the calculation is 0.06, but this lower limit value is a value that can be arbitrarily determined within a range where x and y are in a linear relationship.
The upper limit value is set to 1 because the normalized value is a value from 0 to 1.

2. A sensitivity correction coefficient γ is obtained such that a certain normalized value a calculated from the sensitivity thus obtained becomes a certain value b.
Sensitivity correction coefficient: γ = b / (straight line × a + y intercept)
Sensor life determination The sensitivity correction coefficient γ (current value) calculated here is compared with the sensitivity correction coefficient γ upper limit in the sensor memory, and if the following equation holds, the sensitivity correction coefficient in the sensor memory Increase the γ abnormality counter by one.
Sensitivity correction coefficient: γ (current value)> Sensitivity correction coefficient: γ (upper limit)
If the above equation does not hold, the sensitivity correction coefficient γ upper limit abnormality counter is reset. Write zero.
If the count value after the count-up exceeds 3, that is, if a three-time continuous sensitivity correction coefficient γ upper limit abnormality has occurred, it is determined that the sensor has reached the end of life, and a sensor replacement notification is sent to the call center via the network.

3. The diffused light output after the background portion fluctuation correction obtained in STEP 5 is corrected by multiplying by this sensitivity correction coefficient γ.
Diffuse light output after sensitivity correction: ΔVsp_dif ″ = [Diffused light output after background fluctuation correction] × [Sensitivity correction coefficient: γ]
= ΔVsp_dif (n) ′ × γ

STEP7 Conversion of adhesion amount.
With the above calculation processing, all the correction processing for the temporal variation of the diffuse reflection output caused by the LED light amount reduction or the like has been performed. Finally, conversion to the adhesion amount is performed by referring to the adhesion amount conversion table.

When the processing so far is completed normally, the following processing is performed.
Update of current value Regardless of the sensor replacement flag, the LED current value (current value) and sensitivity correction coefficient γ (current value) information are written in the in-sensor memory 310-3.
Update of minimum value Next, the LED current adjustment value (minimum value) stored in the memory 310-3 of the sensor board is compared with the adjusted LED current value (current value). The LED current adjustment value (minimum value) is stored in the in-sensor memory 310-3 only when the following relationship is satisfied.
LED current value (minimum value)> LED current value (current value)
The minimum value of the LED current adjustment value is stored in this way when the LED adjustment is performed so that the received light output is within a predetermined range. Since it has an increasing function characteristic that increases due to deterioration and also has a characteristic that the output decreases immediately after cleaning the sensor, it is possible to determine the contamination without the influence of the LED aging deterioration by updating the minimum value.

Similarly to the LED current value, the sensitivity correction coefficient γ is compared with (minimum value) and (current value), and the sensitivity correction coefficient (minimum value) in the sensor memory is determined only when the following relational expression is satisfied. Update.
Sensitivity correction coefficient (minimum value)> Sensitivity correction coefficient (current value)
As described above, the reason why the sensitivity correction coefficient γ can be handled in the same manner as the LED current is that, as with the LED current value, the calculated value increases when sensor contamination occurs.
In this embodiment, the LED current value (minimum value) is the LED current output rating upper limit of 50 mA, but the minimum value when the sensor is new is set to a value higher than the upper limit of the actual control range. In this case, it is not necessary to check whether or not the sensor has been replaced during the minimum value update process. The same applies to the minimum value of the sensitivity correction coefficient γ.

Update of initial value The sensor replacement flag is checked, and if it is determined that the sensor has been replaced, the following information is rewritten (updated).
? Acquire sensor ID information stored in the sensor memory, and update the sensor ID information in the main body memory 504.
The LED current (initial value) in the sensor memory 310-3 is stored as the LED current (current value), and the sensitivity correction coefficient γ (initial value) is stored as the sensitivity correction coefficient (current value).

As described above, since the adhesion amount calculation for both the black toner and the color toner has been completed, the development γ is calculated next.
FIG. 11 shows the adhesion amount data (toner per unit area) with respect to the development potential (difference between the development bias potential VB and the surface potential of the photosensitive drum 20, unit: [−Kv]) at the time of toner patch image formation. The amount of adhesion (mg / cm ² )) is plotted.
In order to determine the image forming conditions, the linear approximation formula shown in FIG. 11 (the slope is called development γ and the x intercept is called development start voltage) is calculated, and the potential necessary to obtain the target adhesion amount is calculated. Then, Vd, Vb, and VL that match this potential are obtained by referring to a potential table as shown in FIG.

Next, the residual potential of the photosensitive drum 20 is detected, and the target potentials VB, VD, and VL are corrected for the residual potential to obtain the target potential.
Thereafter, the charging DC bias adjustment and the LD power adjustment are performed so as to obtain this target potential, the image forming conditions are stored in the image forming apparatus internal memory RAM 504, and the processing is ended.

After the above series of operations is completed, the plotter is lowered, and the process is terminated.
In the plotter lowering operation, as shown in FIG. 13, the motor load of each photosensitive drum motor, intermediate transfer belt motor, secondary transfer motor, etc. is started, and charging, development, and transfer bias are performed according to the determined image forming timing. The control load lowering operation process necessary for the image forming operation such as the starting operation is performed.
The P sensor LED is also turned off in the fall operation process. When the LED is OFF, the LED lighting time is calculated from the difference between the timer value when the LED is ON and the timer value when the LED is OFF, and is stored in the in-sensor memory 310-3.

Next, sensor check processing when the sensor is cleaned will be described.
In this embodiment, since the sensor is not provided with a cleaning mechanism, the determination as to whether or not the sensor has been cleaned is triggered by the operation of closing the front door.
Updating the current value When the front door is closed, the Vsg adjustment operation is performed, and the LED current value (current value) is updated.
Update of minimum value As a result of comparison judgment of LED current (current value) and LED current (minimum value), the following formula LED current value (minimum value)> LED current value (current value)
Is satisfied, the sensor determines that the sensor has been cleaned, and writes the LED current value (current value) to the LED current value (minimum value).
Even in the case of this sensor check operation, the LED lighting time from LEDON is calculated at the LEDOFF timing and stored in the sensor memory 310-3.
In the present embodiment, the energization time stored in the sensor memory 310-3 is the energization time stored in the memory in the main body storage device, and the addition value is written to the sensor memory every 1 hr. This timing does not have to be this way, and may be another method.

If the machine with the sensor according to the embodiment described above expires and is collected for recycling, reading the sensor memory 310-3 will show the operation history of the sensor. It is possible to determine whether or not to recycle resources.
In addition, when it is determined that reuse is possible and the reuse is performed, the reuse count can be used as a reuse determination condition by incrementing the counter value of the reuse count by one in the assembly process.

In the present invention, an example of application to a density sensor, which is one form of a reflection type photosensor, has been described. However, this is an optical sensor that combines a light emitting element and a light receiving element, and is also used in a dirty environment. Even when applied to a sensor that is replaced or recycled, for example, a paper type detection sensor that is a form of a transmissive sensor, or a feedback sensor that is a form of a reflective optical sensor, the same effects as the present invention can be obtained. be able to.
In the present invention, the ID information of the sensor is stored in the sensor memory 310-3. However, storing the information in the memory is not a necessary requirement, and the ID information is received from the image forming apparatus to which the sensor is attached. If it can be acquired, it may be in another form.
FIG. 16 illustrates a rotary developing type image forming apparatus. The present invention can also be applied to a so-called rotary development type image forming apparatus in which a latent image is formed on a photoconductor for each color and developed, and color images are sequentially superimposed on a transfer material to form a multicolor image.

1 is a schematic configuration diagram illustrating an entire copying machine according to an exemplary embodiment. 2 is an enlarged view showing a configuration of the copying machine main body 100. FIG. It is a regular reflection type sensor. It is a regular reflection + diffuse reflection type sensor. 2 is an enlarged view showing a configuration of two adjacent image forming units. FIG. FIG. 2 is a block diagram showing electrical connection of each unit provided in the copier of the present embodiment. It is a figure which shows the type by which two sensors for position alignment detection and one density sensor are mounted on one board | substrate. It is the figure which arranged four density sensors in parallel. It is a figure which shows the data of the luminous intensity remaining rate with respect to LED operation time. FIG. 6 is a plan view showing a positional relationship between a gradation pattern transferred onto an intermediate transfer belt and a density sensor attached facing the gradation pattern. 6 is a graph showing a linear approximation of toner adhesion amount with respect to development potential during potential control. It is a schematic diagram which shows an electric potential control table. FIG. 6 is a diagram illustrating control load start-up operation processing necessary for image forming operations such as charging, development, transfer bias start-up operation, and the like. This type detects only diffusely reflected light. This is a type in which a beam splitter is provided in the light emitting path / light receiving path. This is a rotary development type image forming apparatus.

Explanation of symbols

5 Transfer Paper 6 Bypass Tray 7 Discharge Tray 10 Intermediate Transfer Belt 14 Support Roller 15 Support Roller 16 Support Roller 17 Belt Cleaning Devices 18Y, 18C, 18M, 18K Image Forming Units 20Y, 20C, 20M, 20K Photosensitive Drum 21 Exposure Device 22 Conveying belts 23a, 23b Roller 24 Secondary transfer roller 25 Fixing device 26 Heating roller 27 Pressure roller 31 Contact glass 33 First traveling body 34 Second traveling body 35 Imaging lens 36 Reading sensor 42 Paper feeding roller 44 Supply Paper cassette 45 Separator roller 46 Feed path 47 Transport roller 48 Transport path 49a Transport roller 49b Registration roller 50 Paper feed roller 51 Separation roller 53 Manual feed path 55 Switching claw 56 Discharge roller 60 Charging device 61 Development device 62 Primary transfer device 63 Photoconductor cleaning device 4 Static elimination device 65 Developing sleeve 66 Stirrer 67 Developing unit 68 Screw 70 Developing case 71 Toner density sensor 73 Doctor blade 75 Cleaning blade 76 Fur brush 91 Roller cleaning unit 93 Paper reversing device 100 Copying machine main body 200 Paper feeding device 300 Scanner 310 Density Detection sensor 310-2 Position shift sensor 310-3 Memory 320 Potential sensor 400 Automatic document feeder (ADF)
500 Main control unit 501 CPU (Central Processing Unit)
502 Bus line 503 ROM (Read Only Memory)
504 RAM (Random Access Memory)

Claims (12)

In an image forming apparatus that performs image density control by detecting reflected light with an optical detection unit that combines a light emitting unit and a light receiving unit with respect to an adhesion amount pattern formed on a detection target surface.
The image forming apparatus, wherein the optical detection unit includes a storage unit. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the storage unit stores history information and life determination information. The image forming apparatus according to claim 1, wherein
The image forming apparatus, wherein the optical detection means has ID information for identifying itself. The image forming apparatus according to any one of claims 1 to 3,
The characteristic values to be stored in the optical detection means are initial characteristic values in a new use start state of the optical detection means, characteristic values obtained at the start of use after cleaning the optical detection means,
And an remaining usable time calculated from the use time or lifetime of the optical detection means and the use time. In an image forming apparatus that performs image density control by detecting reflected light with an optical detection unit that combines a light emitting unit and a light receiving unit with respect to an adhesion amount pattern formed on a detection target surface.
2. The image forming apparatus according to claim 1, wherein the optical detection unit has non-rewritable ID information for identifying itself. The image forming apparatus according to claim 5.
The characteristic values to be stored in the image forming apparatus are the ID information of the optical detection means, the initial characteristic values of the optical detection means in a new use start state, and the characteristics obtained at the start of use after cleaning the optical detection means. value,
And an remaining usable time calculated from the use time or lifetime of the optical detection means and the use time. The image forming apparatus according to claim 4 or 6,
The characteristic value is a current value when the light receiving output is adjusted to a constant voltage, or a value corresponding thereto, or a dependent characteristic value obtained by arithmetic processing after adjusting the light emission output. . The image forming apparatus according to claim 7.
The image forming apparatus characterized in that the timing for determining the necessity of updating the characteristic value is when the image forming apparatus is powered on or when the cover of the image forming apparatus is opened or closed. The image forming apparatus according to any one of claims 4 and 6 to 8,
The condition for updating the initial characteristic value of the optical detection means is
When the initial characteristic value of the optical detection means is an initial characteristic value in a new use start state of the optical detection means,
Alternatively, when the ID information stored in the image forming apparatus is different from the ID information held by the sensor,
An image forming apparatus characterized by being limited to the above. The image forming apparatus according to claim 4, wherein:
The condition for updating the post-cleaning characteristic value stored in the optical detection means is:
If the characteristic value is the current value when the received light output is adjusted to a constant voltage or a value corresponding thereto, the value stored in the sensor and the necessity of updating the characteristic value are determined. In comparison with the given value,
The value stored in the sensor> the value obtained when the necessity of characteristic value update is determined.
Alternatively, when the characteristic value is a dependent characteristic value obtained by calculation processing after the light emission output adjustment, the calculation processing timing is first performed after the characteristic value is updated. An image forming apparatus. The image forming apparatus according to claim 4, wherein:
The condition for updating the usage time stored in the optical detection means is a timing at which a light emitting means that is lit is turned off. The image forming apparatus according to claim 1,
An image forming apparatus characterized by performing a sensor state check based on a predetermined condition and notifying the sensor state when it is determined that the sensor is dirty.

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