JP2008268903A - Image forming apparatus and unit removably installed in the image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which the accuracy, with which the type of printing medium is determined, is capable of being maintained, even in a case where the image forming apparatus is used over a long period of time. <P>SOLUTION: The image forming apparatus comprises a sensor which senses a type of printing medium; an image forming unit which forms an image on an image carrier; an intermediate transfer member to which the image that has been formed on the image carrier is transferred by primary transfer; a secondary transfer member which transfers the image that has been formed on the intermediate transfer member to the printing medium by secondary transfer; a fixing unit which fixes the image to the printing medium, by applying heat and pressure to the printing medium to which the image has been transferred by secondary transfer; and a controller which sets the fixing conditions in the fixing unit in accordance with the type of printing medium sensed by the sensor. The intermediate transfer member and the sensor are configured as an intermediate transfer member unit. The intermediate transfer member unit is detachably installed to the body of the image forming apparatus. The intermediate transfer member unit has a storage unit which stores information used to distinguish the printing medium by the sensor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a unit that can be attached to and detached from the image forming apparatus.

  In image forming apparatuses such as copying machines and laser printers, it is desirable to change image forming conditions in accordance with the type of recording paper. There are various types of recording paper such as plain paper, glossy paper, rough paper, thick paper, thin paper, OHT (Overhead Transparency), and the like. It is desirable to stabilize the quality of the image formed on the recording paper by setting image forming conditions according to these types. For example, the size and type of recording paper (hereinafter also referred to as paper type) is set by a user from an operation panel or the like provided in the image forming apparatus main body, and fixing processing conditions (for example, fixing temperature and fixing device) are set according to the setting. Is controlled).

  In order to save the user from inputting the type of recording paper, it has also been proposed to provide a sensor for discriminating the recording paper inside the image forming apparatus (Patent Document 1). According to this, the type of recording paper is determined by taking a surface image of the recording paper with a CMOS sensor, and image forming conditions (for example, development conditions, transfer conditions or fixing conditions) are variably controlled.

Furthermore, an apparatus has also been proposed in which a light emitting source is provided at a position facing a sensor for discriminating recording paper, and the thickness of the recording paper is discriminated by detecting transmitted light from the recording paper (Patent Document 2).
JP 2002-182518 A JP 2001-139189 A

  The above-described technique also has a problem in that, when image formation is repeated, paper powder, toner, or the like adheres to the surface of the LED or sensor, resulting in erroneous determination of type and thickness. In order to solve this problem, a method of mitigating the influence of adhering paper dust or toner by performing output correction (also referred to as calibration) of the reflective optical sensor using a correction plate is also conceivable.

  However, when the image forming apparatus is used for a long period of time or when a large amount of printing (image formation) is performed, paper dust or toner adheres to the LED of the reflective optical sensor or the surface of the sensor, and the level of contamination is reduced. There is a high possibility that it will be exceeded. That is, it is assumed that the discrimination accuracy deteriorates even when the sensor output is corrected. For example, a high-speed apparatus with a high image formation speed (a large number of image formations per unit time) is highly likely to form a large amount of images over a long period of time. In addition, a large number of recording sheets are conveyed in a high-speed apparatus. Therefore, there is a high possibility that the paper dust will adhere to the surface of the LED or sensor.

  It is also conceivable that the user can remove (clean) paper dust and toner on the surface of the reflective optical sensor. In this case, however, the user has to remove paper dust and toner. Further, it is necessary to make the reflective optical sensor accessible to the user, which may lead to an increase in the size of the apparatus.

  Therefore, an object of the present invention is to solve at least one of such problems and other problems. For example, an object of the present invention is to provide an image forming apparatus capable of maintaining recording sheet discrimination accuracy even when the image forming apparatus is used for a long period of time. Other issues can be understood throughout the specification.

  An image forming apparatus according to the present invention includes a sensor for detecting the type of a recording medium, an image forming unit that forms an image on an image carrier, and an intermediate transfer member on which an image formed on the image carrier is primarily transferred. A secondary transfer unit that secondarily transfers the image formed on the intermediate transfer member to the recording medium, and a fixing unit that heats and pressurizes the recording medium on which the image is secondarily transferred to fix the image on the recording medium. And a controller for setting fixing conditions in the fixing unit in accordance with the type of recording medium detected by the sensor. The intermediate transfer member and the sensor are configured as an intermediate transfer member unit. The intermediate transfer body unit is detachable from the main body of the image forming apparatus. The intermediate transfer body unit has a storage unit that stores information used for discriminating a recording medium by a sensor.

  The unit according to the present invention is a unit that can be attached to and detached from the image forming apparatus. The unit includes an intermediate transfer body on which an image formed on the image carrier is primarily transferred, a sensor for detecting the type of the recording medium, and a storage unit for storing information for determining the recording medium by the sensor. Have.

  According to the present invention, recording paper discrimination accuracy can be maintained even when the image forming apparatus is used over a long period of time or when a large amount of image is formed.

  An embodiment of the present invention is shown below. The individual embodiments described below will help to understand various concepts, such as the superordinate concept, intermediate concept and subordinate concept of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

[Embodiment 1]
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment. This image forming apparatus is a color laser beam printer that employs an intermediate transfer member. A color laser beam printer of the type shown in FIG. 1 is also called a tandem type printer. Note that the image forming apparatus may be realized as, for example, a printing apparatus, a printer, a copier, a multifunction peripheral, or a facsimile. The image forming method may be, for example, an electrophotographic method, an electrostatic recording method, a magnetic recording method, an ink jet method, a sublimation method, or an offset printing method.

  As shown in FIG. 1, the image forming apparatus main body 100 feeds a recording sheet 101 by a feeding roller 102 and conveys the recording sheet 101 toward an intermediate transfer member 103. The photosensitive drum 104, which is an image carrier, is rotationally driven in the direction of the arrow in the figure at a predetermined speed by the power of a drive motor (not shown), and is uniformly charged by the primary charger 105 during the rotation process.

  The laser beam scanner 106, which is a part of the image forming unit, outputs while controlling the light amount of the laser according to the video signal modulated corresponding to the image signal, and irradiates the photosensitive drum with the laser. As a result, an electrostatic latent image is formed on the photosensitive drum 104. The developing device 107 forms a toner image (developer image) by adhering powder toner as a developer to the electrostatic latent image. The toner image formed on the photosensitive drum 104 is primarily transferred onto the intermediate transfer member 103 that rotates in contact with the photosensitive drum 104. After that, the secondary transfer roller 108 to which a transfer bias is applied presses the recording paper 101 conveyed at an appropriate timing in synchronization with the rotation of the intermediate transfer member 103. The secondary transfer roller 108 is a main mechanism of the secondary transfer unit. As a result, the toner image is secondarily transferred onto the recording paper 101.

  The waste toner cleaning unit 109 removes the toner remaining on the photosensitive drum. The waste toner container 110 stores the waste toner collected by the waste toner cleaning unit 109.

  The photosensitive drum 104, the primary charger 105, the laser beam scanner 106, the developing device 107, the waste toner cleaning unit 109, and the waste toner container 110 are prepared for the number of colors of toner to be used. For example, when four color toners of black, yellow, magenta, and cyan are used, these are prepared for four colors. In FIG. 1, Bk is a photosensitive drum for black, Y for yellow, M for magenta, and C for cyan. Each color photosensitive drum, primary charger, laser beam scanner, developing unit, waste toner cleaning unit, and waste toner container have the same configuration. The waste toner container is an example of a collecting unit that collects toner.

  A fixing device 111, which is an example of a fixing unit, includes a fixing roller 113 including a fixing heater 112, and a pressure roller 114 for pressing against the fixing roller 113. The fixing device 111 heats and presses the recording paper 101 so that the toner image is fixed, and is discharged out of the apparatus as an image formed product. The recording paper may be called, for example, a recording material, a recording medium, a paper, a sheet, a transfer material, or a transfer paper.

  The power supply device 116 connected to the commercial power supply 115 has a rectifying action from alternating current to direct current, and supplies electric power consumed in the image forming process to each unit.

  The recording paper discrimination sensor 117 is an example of an electric element used to discriminate the type of recording paper. The present invention is characterized in that the recording sheet discrimination sensor 117 is attached to a consumable unit having the intermediate transfer member 103 as a main component. The consumable unit is a unit including a consumable member that deteriorates due to use of the apparatus, and is detachable from the image forming apparatus main body 100 and needs to be replaced while the image forming apparatus main body is used. is there. Since the recording paper discrimination sensor 117 is attached to the consumable unit, the consumable unit is replaced.

  Then, with the consumable unit mounted in the image forming apparatus main body, the recording paper discrimination sensor 117 is disposed in the vicinity of the conveyance path 120 that conveys the recording paper. That is, the position at which the recording paper discrimination sensor 117 is provided in the consumable unit is determined based on the positional relationship between the fixed position of the consumable unit with respect to the main body and the recording paper conveyance path 120.

  The transmitted light LED 118 is used to measure the thickness and basis weight of the recording paper. That is, the LED 118 for transmitted light is provided on the opposite side of the electrical component (for example, the recording paper discrimination sensor 117) with the recording paper and the diffusion plate (described later) interposed therebetween, and detects the thickness or basis weight of the recording paper. It is an example of the light emission means used in order to do. The LED 118 for transmitted light may be considered as a part of the recording paper discrimination sensor 117. An operation panel 119 allows the user to make various settings.

  FIG. 2 is a diagram illustrating an example of a recording sheet discrimination sensor according to the embodiment. As shown in FIG. 2, the recording paper discrimination sensor 117 is an LED 201 for reflected light that is an example of a first light emitting unit, a phototransistor 203 that is an example of a first light receiving unit, and an example of a second light receiving unit. A phototransistor 202 is included. Furthermore, it is good also as a structure which has LED118 for transmitted light which is an example of a 2nd light emission means. In this embodiment, at least the LED 201 for reflected light and the phototransistors 202 and 203 are provided. The LED 118 for transmitted light is provided on the main body side of the image forming apparatus. According to FIG. 2, the LED 118 for transmitted light is provided on the opposite side of the recording sheet discrimination sensor 117 with the conveyance path 120 (FIG. 1) of the recording medium interposed therebetween. Note that the LED 201 for reflected light and the LED 118 for transmitted light are examples of light emitting elements for irradiating light to a recording sheet. Phototransistors 202 and 203 are examples of light receiving elements that receive light from recording paper.

  Light using the LED 201 for reflected light as a light source is applied to the surface of the recording paper 101 on the recording paper conveyance guide 206 through the irradiation slit 205. The recording paper transport guide 206 is provided with a window for irradiating light from the back side of the recording paper 101. A diffusion plate 211 for diffusing light is provided in the window portion. The diffusion plate 211 can reflect a part of the light from the LED 201 for reflected light, and can transmit a part of the light from the LED 118 for transmitted light. As the diffusion plate 211, for example, a white plastic plate can be used.

  The reflected light from the recording paper 101 is collected through the first slit 207 and the second slit 208 for light reception, and is received by the phototransistors 202 and 203, respectively. By detecting the output of the irregular reflection component of the phototransistor 202 and the output of the regular reflection component of the phototransistor 203, the glossiness of the recording paper 101 is determined.

  Light using the LED 118 for transmitted light as a light source is applied to the back surface of the recording paper 101 through a condensing guide 210 for condensing the light. The transmitted light from the recording paper 101 is received by the phototransistors 202 and 203 through the first slit 207 and the second slit 208. Thereby, the amount of light transmitted from the recording paper 101 is detected.

  In this embodiment, the LED 201 for reflected light irradiates light at a predetermined angle with respect to the surface of the recording paper 101 as shown in FIG. 2 (that is, irradiates light from an oblique direction to the recording paper). It is arranged as follows. In the present embodiment, the LED 118 for transmitted light is arranged at a position directly below the phototransistor 202 as shown in FIG.

  FIG. 3 is a block diagram illustrating an example of an internal configuration of the sensor control unit. The parts already described are given the same reference numerals. The intermediate transfer member unit 300 is a consumable unit centering on the intermediate transfer member 103 described above. The engine controller 301 is a control unit mounted on the image forming apparatus main body 100. In particular, the engine controller 301 sets a fixing condition in the fixing unit according to the type of the recording medium detected by the sensor.

  The engine controller 301 includes the following control unit. The light emitting element driving unit 304 drives the LED 201 for reflected light and the LED 118 for transmitted light. The main control unit 305 controls, for example, the light emitting element driving unit. The main control unit 305 includes, for example, a CPU, a ROM, a RAM, and the like for executing various controls. The engine controller 301 and the main control unit 305 are examples of a controller that sets image forming conditions according to the type of a recording medium that is a detection result of a sensor.

  The signal processing unit 306 performs processing on the output value (output signal) such as A / D conversion of each output value from the phototransistors 202 and 203 with a resolution of 16 bits. For example, the signal processing unit 306 indicates the glossiness of the recording paper from the output value (regular reflection output / diffuse reflection output), and indicates the light transmittance of the recording paper (diffuse transmission output in the presence of paper / in the absence of paper state). (Diffuse transmission output). The diffuse transmission output is a value that is output when the phototransistor 202 receives light transmitted from the LED 118 through the diffusion plate and the recording paper. The comparison unit 307 is an arithmetic unit that performs a comparison operation with a set value that is stored in advance in a storage element such as the memory 308 based on the result performed by the signal processing unit 306.

  The memory 308 is a nonvolatile memory such as an EEPROM, for example. The memory 308 stores setting values used for discriminating recording sheets. For example, the memory 308 sets, as the setting value, a light emission amount value LSR calculated from a regular reflection light amount acquired using a reference plate (or reference paper) at the time of factory shipment or the like, and a light emission amount value LDR calculated from an irregular reflection light amount. Is stored. Based on the values of LSR and LDR, the light emitting element driving unit 304 adjusts the voltage for driving the LED 201 as the light emitting unit to adjust the amount of emitted light. That is, the LSR and LDR are used to adjust the variation in the light receiving sensitivity of the phototransistors 202 and 203 that are the light receiving portions and the variation in the light emission amount of the LED 201 as the light emitting portion.

  The intermediate transfer body unit 300 includes a fuse resistor 309 for detecting a new intermediate transfer body unit, in addition to a recording sheet discrimination sensor including a light emitting element and a light receiving element. If the fuse resistor 309 is not blown, the main control unit 305 determines that a new intermediate transfer body unit 300 is attached to the main body. On the other hand, if the fuse resistor 309 is blown, it is determined that the unit is a unit that has been once installed in the image forming apparatus and has started to be used (used unit). If the fuse resistor 309 is not blown, a fuse resistor blow circuit (not shown) provided in the engine controller 301 blows the fuse resistor 309. As a result, the intermediate transfer body unit 300 is changed from the new state to the use start state.

  FIG. 4 is a flowchart illustrating an example of a recording sheet determination method according to the embodiment. Here, the type of recording paper is set to OHT, plain paper, glossy paper / gloss film based on the value (regular reflection output (light quantity) / diffuse reflection output (light quantity)) indicating the glossiness acquired by the recording paper discrimination sensor 117. It is determined whether it is either. These are only examples of types. In the present embodiment, the amount of light emitted from the LED 201 for reflected light is switched between two levels.

  In step S401, the light emitting element driving unit 304 causes the LED 201 for reflected light to emit light with the light amount A1. At that time, the transmitted light LED 118 is turned off. In step S402, the phototransistor 203 receives regular reflection light, and the phototransistor 202 receives irregular reflection light. In step S403, the signal processing unit 306 performs signal processing on the output value from each phototransistor, and calculates a value Pa1 (regular reflection output (light amount) / diffuse reflection output (light amount)) indicating the glossiness of the recording paper.

  In step S404, the comparison unit 307 acquires the glossiness determination threshold value Ta1 stored in advance in the memory 308 through the main control unit 305, and compares it with the value Pa1 indicating the glossiness. If Ta1 <Pa1, the process proceeds to step S405. In step S405, the main control unit 305 determines that the type of recording paper is OHT, and sets image forming conditions for OHT.

  On the other hand, if Ta1> Pa1, the process proceeds to step S406, and the main control unit 305 sends an instruction to the light emitting element driving unit 304 so that the reflected light LED 201 emits light with the light amount A2 (> A1). In response to this instruction, the light emitting element driving unit 304 drives the LED 201 for reflected light to emit light with the light amount A2 (> A1).

  In step S407, the phototransistor 203 receives specularly reflected light, and the phototransistor 202 receives irregularly reflected light. In step S408, the signal processing unit 306 performs signal processing on the output value from each phototransistor, and calculates a value Pa2 (regular reflection light amount / diffuse reflection light amount) indicating the glossiness of the recording paper.

  In step S409, the comparison unit 307 compares the glossiness determination threshold value Ta2 as the set value read from the memory 308 with the value Pa2 indicating the glossiness. If Ta2 ≧ Pa2, the process proceeds to step S410. In step S410, the main control unit 305 determines that the type of recording paper is plain paper, and sets image forming conditions for plain paper.

  On the other hand, if Ta2 ≧ Pa2 is not satisfied, the process proceeds to step S411. In step S411, the main control unit 305 determines that the type of recording paper is glossy paper or glossy film paper, and sets image forming conditions.

  Here, the two types of threshold values Ta1 and Ta2 are set in order to determine whether Ta1 is OHT or not and then use Ta2 to determine whether plain paper, glossy paper or gloss film is used. is there.

  Next, a method for correcting output deterioration (calibration) of the recording paper discrimination sensor due to paper dust or toner contamination will be described. The reason why the output of the recording paper discrimination sensor deteriorates due to paper dust or toner is that paper dust or toner enters the sensor through the slits 205, 207, and 208 in FIG. It is.

  First, when the intermediate transfer unit is new, the phototransistor 203 receives specularly reflected light emitted from the LED toward a correction member (for example, a reference plate), and the phototransistor 202 receives irregularly reflected light. Here, the output value received by the phototransistor 203 is CIA, and the output value received by the phototransistor 202 is CIB.

  Note that this operation is executed at the time of factory shipment when the intermediate transfer member unit is incorporated into the apparatus main body from the factory shipment.

  The output value CIA of the regular reflection light amount and the output value CIB of the irregular reflection light amount at this time are stored in advance in the memory 308 as initial output values. This step is performed when the user uses the image forming apparatus for the first time because the LED and the phototransistor need only be executed in a state where the LED or phototransistor is not soiled by paper dust or toner (or the initial state of use of the image forming apparatus). May be. When the image forming apparatus is used for the first time, for example, it is possible to use the output values of regular reflection light and irregular reflection light by irradiating the diffusion plate 211 with light.

  Here, an example will be described. Before the image forming apparatus receives the print job and the recording paper is fed to the recording paper discrimination sensor 117, the main control unit 305 causes each LED to emit light according to the same procedure as described above and diffuses as a correction member. Reflected light from 211 is received by phototransistors 203 and 202. In the case where no diffusion plate is provided, a diffusion plate or a reference plate as a correction member may be temporarily arranged at a position that closes a hole provided in the recording paper conveyance guide 206 in FIG.

  Here, the output value for the regular reflection light received from the diffusion plate as the correction member is CPA, and the output value for the irregular reflection light is CPB. These values of CPA and CPB, which are current output values from the diffusion plate, are temporarily stored in the memory 308. The main control unit 305 obtains correction coefficients a and b from the CIA and CIB stored in the initial stage and the CPA / CPB values measured at the start of printing.

  Note that CPA and CPB measurement may be performed every time printing is started, or may be performed every time a predetermined number of sheets are printed (for example, every 100 sheets are printed) without being performed each time.

a = CPA / CIA (a <0)
b = CPB / CIB (b <0)
Next, when the recording paper passes the recording paper discrimination sensor 117 during printing, the main control unit 305 causes the LED 201 for reflected light to emit light. The phototransistor 203 receives regular reflection light from the recording paper, and the phototransistor 202 receives diffuse reflection light. The output values at this time are PSA and PSB, respectively. The signal processing unit 306 reads the correction coefficients a and b from the memory 308 and corrects the output values PSA and PSB with the correction coefficients as follows to obtain PCA and PCB.

PCA = PSA / a
PCB = PSB / b
In this way, the output value of the recording paper discrimination sensor 117 is corrected. However, even when such correction is performed, when the image forming apparatus is used over a long period of time or when a large amount of image is formed, paper dust or toner adheres to the surface of the light emitting element or light receiving element, and the amount of light is reduced. May be significantly reduced. In other words, there may be a case where the recording paper discrimination accuracy cannot be maintained even with the above correction.

  FIG. 5 is a perspective view showing an example of the intermediate transfer body unit. The intermediate transfer unit includes an intermediate transfer member 103 such as an intermediate transfer belt, a residual toner cleaner 501, a residual toner box 502, a belt driving roller 503, a driven roller 504, and a secondary transfer roller 108. The secondary transfer roller 108 is paired with the secondary transfer roller 108.

  The intermediate transfer member 103 is stretched around a belt driving roller 503, a driven roller 504, and a secondary transfer roller 108, and is driven to rotate in the direction of the arrow shown. The toner image primarily transferred from the photosensitive drum 104 to the intermediate transfer member 103 is secondarily transferred to the recording paper 101 by the secondary transfer roller 108. The secondary transfer roller 108 is paired with the secondary transfer roller 108 described above. A residual toner cleaner 501 for scraping residual toner remaining on the intermediate transfer member 103 is provided between the secondary transfer roller 108 and the downstream primary transfer unit on the periphery of the intermediate transfer member 103. . The residual toner scraped off by the residual toner cleaner 501 is collected in the residual toner box 502. Note that the toner collection mechanism from the residual toner cleaner 501 to the residual toner box 502 has a well-known configuration, and thus description thereof is omitted.

  The intermediate transfer member 103 is a consumable member, and the belt surface may deteriorate due to long-term use, and an image defect may occur in the toner image to be formed. Further, when the image forming apparatus is used for a long period of time or when a large amount of images are formed, the residual toner box 502 may be filled with the collected toner. Therefore, it is necessary to replace the intermediate transfer body unit 300.

As shown in FIG. 5, the recording paper discrimination sensor 117 is provided in the intermediate transfer body unit 300. Since the intermediate transfer member unit 300 that is a consumable unit is replaced with a new unit, the recording sheet discrimination sensor 117 is also replaced with it. That is, the recording paper discriminating sensor 117 whose discriminating accuracy may be degraded by paper dust or toner is replaced with a new one. Therefore, paper dust or toner adheres to the surface of the light emitting element or the light receiving element, and the amount of light is greatly reduced, and the occurrence of a case where the recording paper discrimination accuracy cannot be maintained even after correction is suppressed. That is, the discrimination accuracy of the recording paper discrimination sensor 117 can be sufficiently maintained from the start of use of the main body to the product life.
Further, as described above, the recording sheet discrimination sensor 117 is positioned in the vicinity of the conveyance path 120 of the image forming apparatus in a state where the intermediate transfer body unit 300 as a consumable unit is mounted on the apparatus main body. In this example, the distance between the recording sheet discrimination sensor 117 and the recording sheet conveyed to the conveying path 120 is set to be about 5 mm. This distance may be appropriately determined depending on the sensitivity and performance of the sensor.

  When the intermediate transfer body unit 300 is replaced, the main control unit 305 detects whether the intermediate transfer body unit 300 is new or not by using a fuse resistor 309 for detecting a new article provided in the intermediate transfer body unit 300. When a new intermediate transfer body unit 300 is detected or set to be new from the operation panel 119, the main control unit 305 acquires the initial output values CIA and CIB again and stores them in the memory 308. I will do it again.

  According to the present embodiment, an electric element used to determine the type of recording paper is provided in a consumable unit that needs to be replaced in a cycle shorter than the product life of the image forming apparatus main body. This electrical element is replaced with the consumable unit by being attached to the consumable unit. Therefore, even in an image forming apparatus having a long product life, the recording paper discrimination accuracy can be maintained from the start of use to the product life.

  In particular, when the electric element or the electronic component is composed of a light emitting element or a light receiving element, this embodiment is particularly effective because it is easily affected by paper dust or toner.

[Embodiment 2]
In the present embodiment, the description of the same parts as those in the first embodiment will be omitted, and different parts will be mainly described. In the present embodiment, a configuration in which a storage element that stores information used to determine the type of recording paper is also provided in the consumable unit will be described.

  FIG. 6 is a block diagram illustrating an example of an internal configuration of the sensor control unit. The parts already described are given the same reference numerals. Compared with FIG. 3, a memory 608 is employed instead of the memory 308 which is an example of a storage unit. In addition, the memory 608 is mounted on the intermediate transfer body unit 300. The memory 608 can be configured by a nonvolatile memory such as an EEPROM. Similar to the memory 308, the memory 608 stores setting values used for output correction from the recording sheet discrimination sensor. As described above, the set values are, for example, the light emission light quantity values LSR and LDR, initial output values CIA and CIB, and glossiness determination threshold values Ta1 and Ta2 acquired at the time of factory shipment.

  In general, the reflection light LED 201 used by the recording paper discrimination sensor 117 has a variation in the mounting position. In addition, the position where the recording sheet discrimination sensor 117 is attached to the intermediate transfer body unit 300 also varies. When such a variation exists, the values Pa1 and Pa2 indicating the glossiness also vary for each intermediate transfer unit. Therefore, if the glossiness determination thresholds Ta1 and Ta2 for determining the recording paper are constant values regardless of the solid, the recording paper determination accuracy may be lowered depending on the unit having a large variation.

  Accordingly, the threshold values Ta1 and Ta2 for determining glossiness, which are set values, are adjusted according to the variation of each intermediate transfer body unit at the time of shipment from the factory, and the nonvolatile memory 608 mounted on the intermediate transfer body unit 300 is preliminarily stored. Remember. Thereby, the recording paper discrimination accuracy can be improved.

  If the correction coefficients a and b described above are also stored in the memory 608, output deterioration of the recording paper discrimination sensor can be accurately corrected even if the intermediate transfer body unit 300 is replaced. As a result, the discrimination accuracy of the recording paper can be suitably maintained.

  FIG. 7 is a diagram showing an example of a memory map of the memory 608 mounted on the intermediate transfer body unit. The memory 608 stores emission light quantity values LSR and LDR, initial output values CIA and CIB, glossiness determination threshold values Ta1 and Ta2, and the like. These values are read from the memory 608 instead of the memory 308 by the main control unit 305 and used for recording sheet discrimination. The specific adjustment method and determination method are as described in the first embodiment.

  According to the present embodiment, by providing the consumable unit with a storage element that stores information used to determine the type of recording paper, the recording paper determination accuracy can be maintained as in the first embodiment. In particular, by storing information for each solid in the memory 608 such as the light emission amount values LSR and LDR, the initial output values CIA and CIB, and the gloss determination thresholds Ta1 and Ta2, the recording paper discrimination sensor varies from one solid to another. This is taken into account for recording paper discrimination. Therefore, the second embodiment may be able to improve the recording paper discrimination accuracy than the first embodiment.

  In the present embodiment, the example in which the memory 608 is mounted on the intermediate transfer body unit has been described, but it is needless to say that the memory 608 may be mounted on another consumable unit that is replaced in a cycle shorter than the product life of the main body. The memory 608 may be a storage element that can erase and write stored contents electrically, such as a flash memory, as well as an EEPROM.

[Embodiment 3]
The third embodiment is a modification of the second embodiment. That is, instead of the memory 608, a variable resistor that functions as a storage element is employed. That is, there is a feature in that information used to determine the type of recording paper is expressed by the resistance value of the variable resistor. Hereinafter, descriptions common to the above-described embodiment will be omitted, and different portions will be mainly described.

  FIG. 8 is a block diagram illustrating an example of an internal configuration of the sensor control unit. The parts already described are given the same reference numerals. Compared to FIG. 6, three variable resistors 808, 809, and 809 are employed instead of the memory 608.

  These variable resistors hold various information (values stored in the memories 308 and 608 described in the first and second embodiments) as resistance values acquired at the time of factory shipment or the like. For example, the main control unit 305 reads the resistance value (actually the voltage value) by A / D conversion, and passes (outputs) the read value to the comparison unit 307, the signal processing unit 306, the light emitting element driving unit 304, or the like. ).

  In the present embodiment, a configuration in which a threshold for determining the type of recording paper, for example, can be set with a variable resistor will be described.

  Specifically, four patterns can be set by changing the resistance value of one variable resistor 808. The set values (threshold values) of the four patterns set using the variable resistor will be described with reference to FIGS. 10 and 11.

  FIG. 10 shows threshold values (Ta2 in the first and second embodiments) for discriminating plain paper, thick paper, and glossy paper (gloss film). This threshold value is set by the ratio between the regular reflection output and the irregular reflection output, which is a value indicating the glossiness. In this embodiment, the resistance value of the rotary resistor is set to a value from 0V to 1.5V.

  FIG. 11 shows an example of setting four pattern setting values (threshold values: 1, 2, 3, and 4 in FIG. 10) according to the resistance value of the variable resistor 808 (setting the resistance value of one variable resistor). Show. The resistance value is set from 0 V to 1.5 V, and four set values (threshold values) are set which are combinations of a value indicating glossiness and a value indicating transparency. This set value is, for example, a set value corresponding to variations in light reception sensitivity of the phototransistors 202 and 203 as the light receiving unit. At the time of shipment from the factory, the resistance value of one variable resistor is adjusted and set to an appropriate value from 0V to 1.5V.

  Note that the variable resistor 809 in FIG. 10 is for setting a threshold value for determining whether or not it is OHT (corresponding to Ta1 in the first and second embodiments).

  Also, the variable resistor 810 in FIG. 10 is for setting the light amount of the LED 201 as the light emitting unit (corresponding to the light emission light amount value LSR or LDR in the first and second embodiments).

  FIG. 9 is a flowchart illustrating an example of a recording sheet determination method according to the embodiment. Parts already described are given the same reference numerals to simplify the description.

  In step S901, the main control unit 305 performs A / D conversion and reads a voltage value corresponding to a resistance value from a variable resistor in which a threshold value for glossiness determination is set. In step S902, the main control unit 305 refers to a table stored in a non-illustrated non-volatile memory, determines glossiness determination thresholds Ta1 and Ta2 corresponding to the read voltage values, and sets them in the comparison unit. To do.

  Note that the threshold values 1 to 4 shown in FIG. 11 indicate the threshold value Ta2. Similarly to the threshold value Ta2, Ta1 is set according to the resistance value of the variable resistor.

  The subsequent steps are as described in the first embodiment. Similarly, the light emission quantity values LSR and LDR and the initial output values CIA and CIB can be set by providing corresponding variable resistors. The main control unit 305 may determine the voltage value read from the variable resistor with reference to a table. Similarly, the correction coefficients a and b may be stored in advance as resistance values in the corresponding variable resistors.

  As described above, the storage element may be realized not only by the memory but also by a variable resistor. Of course, in the third embodiment, the same effect as in the second embodiment is achieved.

  Although the example using three variable resistors has been described in the present embodiment, the number of variable resistors may be other than three according to the number of parameters to be set.

  As described above, according to the present embodiment, the set value is stored using a variable resistor instead of a storage element such as an EEPROM, and the discrimination accuracy of the recording paper is maintained as in the first and second embodiments with a simple configuration. it can.

[Embodiment 4]
The fourth embodiment is a modification of the third embodiment. In the present embodiment, similarly to the third embodiment, a variable resistor that functions as a memory element is employed. A further feature is that the sensitivity of the light receiving portion of the recording paper discrimination sensor can be adjusted using a variable resistor. Hereinafter, descriptions common to the above-described embodiment will be omitted, and different portions will be mainly described.

  FIG. 12 is a block diagram illustrating an example of an internal configuration of the sensor control unit. The parts already described are given the same reference numerals. Compared with FIG. 8, the three variable resistors 808, 809 and 809 are common, but the sensitivity of the light receiving unit is adjusted based on the resistance values of the two variable resistors 809, 810. Is different.

  In FIG. 12, the light receiving sensitivity of the light receiving unit (phototransistor 202) is set by the resistance value of the variable resistor 809, and the light receiving sensitivity of the light receiving unit (phototransistor 203) is set by the resistance value of the variable resistor 810. The light receiving sensitivity is set by receiving (outputting) a light amount value of a predetermined amount or more by the phototransistors 202 and 203 as the light receiving portion when the light emitting portion emits light with a certain amount of light from the LED 201 (or LED 118). It is to set the resistance value as possible.

FIG. 13 is a circuit diagram for adjusting the light receiving sensitivity of the phototransistors 202 and 203 which are light receiving portions. A variable resistor 809 is connected to the phototransistor 202, and a variable resistor 810 is connected to the phototransistor 203. The light receiving sensitivity can be adjusted by changing the resistance value of each variable resistor. The resistor 811 is a resistor for limiting the drive current of the LED 201.
At the time of factory shipment or the like, the resistance values of the variable resistors 809 and 810 are adjusted to adjust the sensitivities of the phototransistors 202 and 203 which are light receiving portions. Note that the resistance value of the variable resistor 808 is used to set a threshold value as in the third embodiment.

  Further, the output voltage obtained by reading the variable resistors 809 and 810 by the main control unit 305 of the image forming apparatus is used to determine the recording paper glossiness value for determining the recording paper, and the light transmittance of the recording paper. Can be used to calculate the value shown. Then, the recording paper is discriminated based on the calculated value.

  In the above description, as shown in FIG. 11, the ratio between the regular transmission output and the diffuse transmission output, which is a value (threshold value) indicating the transparency of the recording paper, is fixed, but the value indicating the transparency is variable. It can also be set according to the resistance value of the resistor. In this case, the threshold value can be set by several combinations of a value indicating the gloss level (threshold value) and a value indicating the transparency (threshold value).

  For example, as shown in FIG. 14, two kinds of values (5 and 6 in the figure) are set as values indicating transparency, and the threshold values of a plurality of patterns can be set in combination with values indicating glossiness. In this case, the resistance value of the variable resistor is set to 0 V to 3.0 V, for example, and the voltage value to be set is widened to increase the number of combinations.

  Further, the presence / absence of the intermediate transfer unit can be determined based on the resistance value of the variable resistor 808. In the first embodiment, the presence or absence of the intermediate transfer body unit is detected (determined) using a new article detection fuse. However, such a fuse need not be used. For example, if the resistance value of the variable resistor is outside the threshold setting range, that is, if the resistance value is larger than the maximum resistance value (1.5 V or 3.0 V in the above case), if there is no intermediate transfer body unit I can judge. Conversely, if it is within the threshold setting range, it can be determined that there is an intermediate transfer body unit. The timing for determining the presence or absence of the intermediate transfer unit is set to a timing at which the intermediate transfer unit may be replaced, such as when the power is turned on or when the door of the image forming apparatus is closed.

[Other Embodiments]
In the embodiment described above, output correction for the LED 118 for transmitted light (the calibration operation has not been described), but output correction can be performed in the same manner as in the embodiment described above, that is, the LED 118 at a predetermined timing. And the output values from the phototransistors 202 and 203 can be stored in the memory 308 and the memory 608. For example, the image forming apparatus receives a predetermined process or print job at a predetermined timing. This is the timing before the recording paper is fed to the recording paper discrimination sensor 117.

  Further, in the above-described embodiment, the LED 118 for transmitted light has been described as being provided in the image forming apparatus main body 100. However, the present invention is not limited to this. In other words, in the image forming apparatus in which the transmitted light LED 118 is also soiled with paper dust or toner, it may be mounted on the intermediate transfer body unit 300 or another consumable unit different from the intermediate transfer body unit 300. As a result, regarding the thickness and basis weight of the types of recording paper, it will be possible to maintain different accuracy from the start of use to the product life.

  The recording sheet discrimination sensor 117 of the above-described embodiment includes one light emitting element and two light receiving elements, but the present invention is not limited to this. That is, the recording paper discrimination sensor 117 may be constituted by a CMOS sensor, a CCD sensor, or the like. When a CMOS sensor or a CCD sensor is used, the surface property of the recording paper can be determined by reading a two-dimensional image and processing the data.

In the above-described embodiment, the example in which the recording sheet discrimination sensor 117 is mounted on the intermediate transfer body unit 300 has been described. However, the present invention is not limited to this. That is, the recording paper discrimination sensor 117 or the like may be mounted on another consumable unit that is replaced in a cycle shorter than the product life of the image forming apparatus main body.
Consumable units to which the present invention can be applied include, in addition to the above-described intermediate transfer unit, a cartridge having a photosensitive member or a developing device, an electrostatic adsorption belt unit that conveys recording paper while adsorbing it, and the like. In a state where these units are mounted on the apparatus main body, they are arranged so that the position of the recording paper discrimination sensor provided in the unit is close to the recording paper conveyance path. In other words, the present invention can be applied to units other than the above as long as the position of the recording paper discrimination sensor can be arranged at a position close to the conveyance path of the recording paper.

  In the embodiment described above, the reflected light LED 201 and the phototransistors 202 and 203 are both attached to the intermediate transfer body unit 300. However, both are not necessarily attached to the intermediate transfer body unit 300. That is, if at least one of a light emitting element for irradiating light on recording paper and a light receiving element for receiving light from the recording paper is attached to the consumable unit, the discrimination accuracy can be maintained as compared with the prior art. Because it becomes.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment. It is a figure which shows an example of the recording paper discrimination sensor which concerns on embodiment. It is a block diagram which shows an example of an internal structure of a sensor control part. 6 is a flowchart illustrating an example of a recording sheet determination method according to the embodiment. It is a perspective view showing an example of an intermediate transfer body unit. It is a block diagram which shows an example of an internal structure of a sensor control part. FIG. 6 is a diagram showing an example of a memory map of a memory 608 mounted on an intermediate transfer body unit. It is a block diagram which shows an example of an internal structure of a sensor control part. 6 is a flowchart illustrating an example of a recording sheet determination method according to the embodiment. It is a figure which shows the threshold value for recording paper discrimination | determination concerning embodiment. It is a figure which shows the relationship between the threshold value and resistance value for recording paper discrimination | determination concerning embodiment. It is a block diagram which shows an example of an internal structure of a sensor control part. It is a circuit diagram of sensitivity adjustment of the light receiving part of the recording paper discrimination sensor. It is a figure which shows the threshold value for recording paper discrimination | determination concerning embodiment.

Explanation of symbols

100 image forming apparatus 101 recording paper 102 feeding roller 103 intermediate transfer member 104 photosensitive drum 105 primary charger 106 laser beam scanner 107 developing unit 108 secondary transfer roller 109 waste toner cleaning unit 110 waste toner container 111 fixing unit 112 fixing heater 113 Fixing roller 114 Pressure roller 115 Commercial power supply 116 Power supply device 117 Recording paper discrimination sensor 118 Transmitted light LED
119 Operation panel 201 LED for reflected light
202 Phototransistor 203 Phototransistor 204 Transmitted light LED
304 light emitting element driving unit 305 main control unit 306 signal processing unit 307 comparison unit 308 memory 309 new article detection fuse 608 memory 808 variable resistor 809 variable resistor 810 variable resistor 811 LED current limiting resistor

Claims (17)

An image forming apparatus,
A sensor for detecting the type of recording medium;
An image forming unit that forms an image on an image carrier;
An intermediate transfer member to which an image formed on the image carrier is primarily transferred;
A secondary transfer portion that secondary-transfers the image primarily transferred to the intermediate transfer member to the recording medium;
A fixing unit that heats and pressurizes the recording medium onto which the image is secondarily transferred to fix the image on the recording medium;
A controller for setting fixing conditions in the fixing unit according to the type of recording medium detected by the sensor;
The intermediate transfer body and the sensor are configured as an intermediate transfer body unit, and can be attached to and detached from the main body of the image forming apparatus,
The image forming apparatus, wherein the intermediate transfer body unit includes a storage unit that stores information used for determining a recording medium by the sensor. The sensor is
A light emitting unit for irradiating the recording medium with light;
The image forming apparatus according to claim 1, further comprising a light receiving unit that receives light from the recording medium.   The image forming apparatus according to claim 1, wherein the controller uses the information stored in the storage unit to set a threshold for determining a recording medium by the sensor. The storage unit includes a resistor that holds the information as a resistance value,
The image forming apparatus according to claim 1, wherein the controller sets a threshold value for determining a recording medium by the sensor according to the resistance value. The sensor is
A light emitting unit for irradiating the recording medium with light;
A light receiving portion for receiving light from the recording medium,
The storage unit includes a resistor capable of setting a resistance value,
The image forming apparatus according to claim 1, wherein the light receiving sensitivity of the light receiving unit or the light emission amount of the light emitting unit is set according to the resistance value. A light-emitting unit provided on the opposite side of the recording medium with respect to the sensor, and used to detect the thickness or basis weight of the recording medium;
The image forming apparatus according to claim 1, wherein the light emitting unit is provided in a main body of the image forming apparatus. A unit detachable from the image forming apparatus,
An intermediate transfer body on which an image formed on the image carrier is primarily transferred;
A sensor for detecting the type of recording medium on which the image is to be secondarily transferred from the intermediate transfer member;
And a storage unit for storing information for determining the recording medium by the sensor. The sensor is
A light emitting unit for irradiating the recording medium with light;
The unit according to claim 7, further comprising a light receiving unit that receives light from the recording medium. The storage unit includes a memory that stores information related to a threshold for determining a recording medium by the sensor,
The unit according to claim 7, wherein a threshold for the controller of the image forming apparatus to determine a recording medium is set using the information stored in the memory. The storage unit includes a resistor that holds the information as a resistance value,
The unit according to claim 7, wherein a threshold for the controller of the image forming apparatus to determine a recording medium is set according to the resistance value. The sensor is
A light emitting unit for irradiating the recording medium with light;
A light receiving portion for receiving light from the recording medium,
The storage unit includes a resistor capable of setting a resistance value,
The unit according to claim 7, wherein the light reception sensitivity of the light receiving unit or the light emission amount of the light emitting unit is set according to the resistance value.   The unit according to claim 7, further comprising a recovery unit that recovers the developer remaining on the intermediate transfer member. An image forming apparatus for forming an image;
A sensor for detecting the type of recording medium;
A controller for setting an image forming condition of the image forming unit according to a detection result of the sensor;
Have
A unit having a consumable member for forming an image on the recording medium, the sensor, and a storage unit for storing information used for determining the recording medium by the sensor is detachable from the image forming apparatus. An image forming apparatus, comprising: Furthermore, it has a transport path for transporting the recording medium,
The image forming apparatus according to claim 13, wherein the sensor is disposed in the vicinity of the conveyance path in a state where the unit is mounted on the image forming apparatus.   The image forming apparatus according to claim 13, wherein the consumable member includes an intermediate transfer member for transferring an image to the recording medium. A unit detachable from the image forming apparatus,
A consumable member for forming an image on a recording medium;
A sensor,
And a storage unit that stores information used to determine a recording medium by the sensor.   The unit according to claim 16, wherein the consumable member includes an intermediate transfer member for transferring an image to the recording medium.

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