JP2006171158A - Toner concentration sensor and image forming apparatus provided with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which the control voltage is not updated even when a serviceman executes a replacement initial operation mode again. <P>SOLUTION: The control voltage for performing the control so that the output voltage when the toner concentration (5%) of a developer stored in an initial developer storage container is sensed by a standard toner concentration sensor becomes the reference output voltage (3 V) is stored in advance, as a reference control voltage. In the replacement initial operation mode, when the control voltage after performing the control so that the output voltage obtained from the toner concentration sensor by performing the toner concentration detection becomes the reference output voltage (3 V) stored in advance is within ±1 V of the reference control voltage, the control voltage is updated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner density sensor and an image forming apparatus including the toner density sensor.

  2. Description of the Related Art Conventionally, there has been known a device in which a developing device is provided with a magnetic sensor to detect a mixing ratio (toner concentration) of nonmagnetic toner to a magnetic carrier in the developing device (for example, Patent Document 1).

Since the magnetic sensor used for toner concentration detection has high detection sensitivity, the influence of manufacturing errors of components in the magnetic sensor is large, and the relationship between the toner concentration and the output voltage of the magnetic sensor differs for each magnetic sensor. Further, although the toner concentration in the developing device is 5%, the output voltage when the toner concentration is 5% may differ depending on the developer due to magnetic variation of the magnetic carrier. Therefore, the replacement initial operation mode is executed when the developing device is replaced, and the control voltage for controlling the output voltage is adjusted so that the relationship between the toner density and the output voltage becomes a preset relationship, and then the development is performed. The toner density in the apparatus is increased to a density capable of forming a good image.
Specifically, the toner concentration in the developing device of a new process cartridge provided with the developing device is set to a predetermined value (5%) in advance, and the replacement initial operation is performed when the serviceman replaces this new process cartridge. Run the mode. When the replacement initial operation mode is executed, the toner density is detected, and the output voltage obtained from the magnetic sensor at this time is set to a preset output voltage (for example, 3 V) when the toner density is 5%. Adjust the control voltage. The control voltage at this time is stored in the control voltage storage unit of the image forming apparatus. As described above, by adjusting the control voltage, the relationship between the toner density and the output voltage can be set to a preset relationship.
If the relationship between the toner density and the output voltage is set in advance, development is performed using the control voltage stored in the control voltage storage means so that the output voltage (target voltage) of the toner density (7%) is obtained. Add toner while stirring agent. As described above, when the toner density in the developing device is 7% that can form an image with a good toner density, the replacement initial operation mode is terminated.

JP 2000-131120 A

  However, after the serviceman replaces the developing device and executes the replacement initial operation mode, it forgets that the replacement initial operation mode was executed due to repair or replacement of other repaired parts, and the replacement initial operation was performed again. The operation mode may be executed. As described above, after execution of the replacement initial operation mode, the toner density in the developing device increases from 5% to 7%. For this reason, when the replacement initial operation mode is executed again, the output voltage at this time is set to the output voltage having the toner concentration of 5% even though the output voltage is actually 7%. The control voltage is adjusted so that Then, the control voltage stored in the control voltage storage means is rewritten to the control voltage adjusted to the reference output voltage when the 7% toner density is detected. Therefore, when toner density detection is performed using this control voltage, the output voltage output from the toner density sensor is 5% even though the toner density in the developing device is actually 7%. Output voltage. As a result, the toner is erroneously supplied into the developing device until the output voltage reaches the output voltage value indicated when the toner density is 7%. As a result, the toner density in the actual developing device becomes higher than 7%, resulting in excessive toner density and problems such as toner scattering.

  The memory of the image forming apparatus stores standard toner density sensor sensitivity information as characteristic information of the toner density sensor. The sensitivity information indicates the relationship between the toner density and the output voltage, and is the slope (toner density / output voltage) obtained when the toner density is on the vertical axis and the output voltage is on the horizontal axis. Using this standard sensitivity information, toner density control is performed so that the output voltage of the toner density sensor becomes the output voltage (target voltage) when the toner density is 7%. However, the characteristics of the toner density sensor vary from sensor to sensor as described above. For this reason, the sensitivity of the standard toner density sensor stored in the image forming apparatus may differ from the sensitivity of the toner density sensor actually attached to the developing device. Then, the output voltage (target voltage) when the toner density is 7% obtained based on the sensitivity of the standard toner density sensor stored in the image forming apparatus is not accurate. As a result, even if the toner density control is performed and the output voltage of the toner density sensor is set to the target voltage, there is a problem that the toner density in the actual developing device is not a 7% toner density that allows good image formation. To do. As a result, image deterioration such as carrier adhesion due to insufficient toner concentration and toner scattering due to excessive toner concentration may occur.

  Further, some conventional process cartridges are provided with storage means such as a non-volatile memory that stores process cartridge manufacturing information and the like. The process cartridge having the storage means includes a communication connector for performing communication between the storage means and the image forming apparatus, a circuit connector for connecting the toner density sensor circuit and the image forming apparatus circuit. Were provided separately. As described above, since the connectors are provided separately, there are the following problems when the process cartridge is attached to the image forming apparatus. That is, it is necessary to connect the communication connector and the circuit connector to the communication connector and the circuit connector of the image forming apparatus, respectively. In order to solve such a problem, it may be possible to eliminate the communication connector by performing non-contact communication between the storage unit and the image forming apparatus. However, since the non-contact communication means is expensive, the cost of the image forming apparatus is increased.

  The present invention has been made in view of the above problems, and a first object of the present invention is to perform image formation in which the control voltage is not updated even when the serviceman executes the replacement initial operation mode again. Is to provide a device.

  A second object of the present invention is to provide a toner concentration sensor capable of performing toner control based on characteristics corresponding to the toner concentration sensor used and capable of performing accurate toner concentration control. There is to do.

  A third object of the present invention is to provide an image forming apparatus capable of improving process cartridge mounting workability by inexpensive means.

In order to achieve the above object, the invention of claim 1 contains a developer containing a two-component developer comprising magnetic particles and toner, and a toner concentration sensor for detecting the toner concentration of the two-component developer. The image forming apparatus is detachably mounted, and when the developer container is mounted on the image forming apparatus, an output voltage obtained from the toner density sensor by detecting the toner density is stored in advance. The control voltage for controlling the obtained output voltage is adjusted so as to be the reference output voltage, the control voltage stored in the control voltage storage means is updated to the adjusted control voltage, and the updated control is performed. In the replacement initial operation mode in which the toner is replenished so that the toner density of the developer in the developer container becomes a desired toner density using voltage, the standard toner density sensor is used to place the toner in the initial developer container. Containment The adjusted output voltage when the toner density of the developer adjusted to a predetermined toner density is detected is adjusted within a predetermined range of a reference control voltage as a control voltage for controlling the output voltage to become the reference output voltage. When there is a control voltage, the control voltage stored in the control voltage storage means is updated to the adjusted control voltage.
According to a second aspect of the present invention, in the toner concentration sensor for detecting the toner concentration of the two-component developer in the developer accommodating portion for accommodating the two-component developer composed of toner and carrier, characteristic information of the toner concentration sensor is stored. The storage means is provided.
According to a third aspect of the present invention, in the toner concentration sensor of the second aspect, the characteristic information is the same as that of the developer having a predetermined toner concentration using the reference output voltage and the toner concentration sensor at the time of manufacture. The output voltage when measuring a reference device having characteristics is a control voltage when adjusted to the reference voltage.
According to a fourth aspect of the present invention, in the toner concentration sensor according to the second or third aspect, the characteristic information is calculated based on a value obtained by measuring a reference device as a measurement reference using the toner concentration sensor at the time of manufacture. The sensitivity information of the toner density sensor is used.
According to a fifth aspect of the present invention, in the toner density sensor according to the second, third, or fourth aspect, the driving power source for driving the toner density sensor is the same as the driving power source for driving the storage means. The voltage from the drive power source supplied to the storage means is supplied via the pressure reducing means.
According to a sixth aspect of the present invention, in the toner density sensor of the second, third, fourth, or fifth aspect, a control voltage signal for controlling the output voltage of the toner density sensor to be an output voltage stored in advance. The line and the signal line for controlling the writing / reading of the recording means are the same.
According to a seventh aspect of the present invention, in the toner density sensor according to the sixth aspect, the control voltage for controlling the output voltage of the toner density sensor to be an output voltage stored in advance is a voltage of HI / LOW. The signal that is generated using a PWM signal that switches at a predetermined interval, and the signal that controls the writing / reading of the recording means is only one of the values of either HI or LOW during writing / reading by the recording means. It is the signal which takes it.
The invention according to claim 8 is an image carrier that carries an electrostatic latent image, a developer container that contains a two-component developer composed of a carrier and a toner, and a developer that is contained in the developer container. And a developing device including a developer carrying member and a developing device having a toner concentration detecting device for detecting the toner concentration of the two-component developer in the developer containing portion are detachable from the main body of the image forming apparatus. In the image forming apparatus, the process cartridge includes a storage unit, a communication connection unit for connecting the communication unit of the storage unit and the communication unit of the image forming apparatus, and an electric circuit of the toner density sensor. And a circuit connection portion for connecting to an electric circuit on the main body side of the forming apparatus, and the communication connection portion is provided in the circuit connection portion.
According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, the storage means stores manufacturing information relating to the process cartridge.
According to a tenth aspect of the present invention, in the image forming apparatus according to the seventh, eighth, or ninth aspect, the use history of the process cartridge is stored in the storage unit.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the seventh, eighth, ninth, or tenth aspect, the storage means stores a history of use of parts mounted on the process cartridge. To do.
According to a twelfth aspect of the present invention, in the image forming apparatus of the first, eighth, ninth, tenth or eleventh aspect, the toner density sensor is the toner density sensor according to the second, third, fourth, fifth, sixth or seventh aspect. It is characterized by this.
The invention according to claim 13 is the image forming apparatus according to claim 12, further comprising request means for requesting writing / reading to the storage means in the image forming apparatus, and when the toner density is detected, The control of the request means is stopped.

According to the first, eleventh and twelfth aspects of the present invention, the toner voltage is detected and the control voltage is adjusted so that the output voltage obtained from the toner density sensor becomes the reference output voltage stored in advance. When the adjusted control voltage is within a predetermined range of the reference control voltage, the control voltage stored in the control voltage storage means is updated to the adjusted control voltage.
The reference control voltage refers to the output voltage when the toner concentration of a developer that has been adjusted to a predetermined toner concentration stored in the initial developer container by a standard toner concentration sensor is detected. This is a control voltage that is controlled to be an output voltage. The standard toner density sensor is a toner density sensor in which the relationship between toner density and output voltage has a standard relationship. Therefore, the reference control voltage is also a standard control voltage of the toner density sensor. Then, the predetermined range is set to a range that sufficiently takes into account variations in the toner density sensor with reference to the reference control voltage. As a result, the control voltage adjusted when the toner concentration of the developer contained in the initial developer container is detected by the toner concentration sensor provided in the developer container falls within a predetermined range. On the other hand, the output voltage when the toner concentration is detected for the developer in the developer container that has been changed to a toner density that can form an image satisfactorily is stored in the initial developer container. This is very different from the output voltage when the toner density of the developer is detected. As a result, the control voltage adjusted so that the output voltage when the toner density is detected for the developer in the developer container whose toner density is changed becomes the reference output voltage is also the initial developer container. The output voltage when the toner density is detected for the developer contained in the developer is greatly different from the control voltage adjusted to be the reference output voltage. Therefore, the control voltage adjusted when the toner density detection is performed for the developer in the developer container whose toner density has been changed shows a value greatly different from the reference control voltage and falls within the predetermined range. There is no. Therefore, whether the control voltage is within the predetermined range of the reference control voltage, the toner density in the initial developer container is detected, or in the developer container after the toner density is changed. It can be determined whether the toner density is detected. Therefore, if the control voltage is updated only when the control voltage is within the predetermined range of the reference control voltage, it is adjusted when the toner density is detected for the developer in the developer container whose toner density has been changed. The control voltage is not stored in the control voltage storage means. Therefore, even if the replacement initial operation mode is once executed and the replacement initial operation mode is executed again for the developer container whose toner density has been changed, the control voltage at this time is the same as the reference control voltage. Not within range. Therefore, the control voltage at this time is not updated. As a result, the toner density control is not performed using the control voltage adjusted when the replacement initial operation mode is executed again. Therefore, the toner concentration of the developer in the developer container does not become higher than the toner concentration at which an image is formed satisfactorily. As a result, the toner concentration of the developer in the developer container can be maintained at a toner concentration at which an image is formed satisfactorily, and an excellent image can be obtained.

  According to the second to sixth aspects of the present invention, the manufacturing information of the toner density sensor is stored in the storage means provided in the toner density sensor. Therefore, the following effects can be obtained by reading manufacturing information unique to the toner density sensor and executing toner density control based on the manufacturing information at the time of toner density control. That is, there is an effect that accurate toner density control can be performed as compared with a conventional toner density control based on characteristics of a general toner density sensor.

  According to the seventh to tenth aspects of the present invention, the communication means for communicating between the storage means and the image forming apparatus is a connection for connecting the electric circuit of the toner density sensor and the electric circuit on the image forming apparatus main body side. Provided in the department. Accordingly, the connection between the toner density sensor circuit and the image forming apparatus circuit and the communication between the image forming apparatus and the storage unit can be performed only by connecting the connecting portion of the toner density sensor. As a result, it is necessary to perform connection work for connection for communication between the image forming apparatus and the storage unit separately from the connection between the circuit of the toner density sensor and the circuit of the image forming apparatus as in the prior art. Absent. Therefore, the process cartridge mounting workability is improved. Also, the mounting workability can be improved without using expensive non-contact communication means as in the prior art.

Hereinafter, a tandem color laser printer (hereinafter referred to as “printer”) will be described as an embodiment of an image forming apparatus to which the present invention is applied.
First, the basic configuration of the printer will be described. FIG. 1 is a schematic configuration diagram illustrating a printer according to the present embodiment. This printer includes four sets of toner image forming portions 1Y, 1M, 1C, and 1K for forming images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K). . Also provided are an optical writing unit 2, paper feed cassettes 3 and 4, a pair of registration rollers 5, a transfer unit 6, a belt fixing type fixing unit 8, a paper discharge tray 9 and the like. Further, a manual feed tray, a toner supply container, a waste toner bottle, a power supply unit, and the like (not shown) are also provided. Hereinafter, the subscripts Y, M, C, and K of the respective symbols indicate members for yellow, magenta, cyan, and black, respectively.

  The toner image forming units 1Y, 1M, 1C, and 1K include drum-shaped photoreceptors 11Y, 11M, 11C, and 11K that are latent image carriers that carry latent images. These photoconductors 11Y, 11M, 11C, and 11K function as endless moving bodies that are rotationally driven clockwise in the drawing by driving means (not shown) to move the surface endlessly. Then, it is optically scanned in the dark by the optical writing unit that emits laser light L modulated based on image information sent from a personal computer (not shown) or the like, and electrostatic latent images for Y, M, C, and K are obtained. Carry an image.

  FIG. 2 is an enlarged configuration diagram showing the toner image forming unit 1Y for Y of the toner image forming units 1Y, 1M, 1C, and 1K together with a part of the transfer unit 6. As shown in FIG. The other toner image forming units (1M, C, K) have the same configuration as that for Y except that the colors of the toners to be used are different from each other. . In the figure, the toner image forming unit 1Y includes a process cartridge 10Y. In addition to the photoreceptor 11Y, the process cartridge 10Y includes a developing device 20Y, a brush roller 12Y that applies a lubricant to the surface of the photoreceptor, a swingable counter blade 13Y that performs a cleaning process, and a charge removal lamp 14Y that performs a charge removal process. Etc. Further, a charging roller 15Y for uniformly charging the photoconductor 11Y and a roller cleaning device 16Y for cleaning the surface of the charging roller 15Y are also provided.

  In the process cartridge 10Y, a charging roller 15Y to which an AC charging bias is applied by a power source (not shown) is disposed so as to contact the photoreceptor 11Y. Then, the surface of the photoconductor 11Y is uniformly charged while being rotated by the driving means (not shown) so that the surface thereof is moved in the direction opposite to the surface movement of the photoconductor 11Y. When the laser beam L modulated and deflected by the optical writing unit (FIG. 2) is scanned on the surface of the photoreceptor 11Y that is uniformly charged in this way, an electrostatic latent image is formed on the surface. The

  The developing device 20Y has a developing roll 22Y disposed so as to partially expose the opening of the developing case 21Y. Further, it also includes a first transport screw 23Y, a second transport screw 24Y, a developing doctor 25Y, a toner concentration sensor (hereinafter referred to as T sensor) 26Y, a powder pump 27Y, and the like.

  The developer case 21Y contains a developer containing a magnetic carrier and a negatively chargeable Y toner. The developer is frictionally charged while being agitated and conveyed by the first conveying screw 23Y and the second conveying screw 24Y, and is then carried on the surface of the developing roll 22Y as a developer carrying member. Then, after the layer thickness is regulated by the developing doctor 25Y, the layer is conveyed to a developing area facing the photoconductor 11Y, where Y toner is attached to the electrostatic latent image on the photoconductor 11Y. This adhesion forms a Y toner image on the photoreceptor 11Y. The developer that has consumed Y toner by development is returned to the developing case 21Y as the surface of the developing roll 22Y (developing sleeve) rotates. On the other hand, the developed Y toner image is transferred to a transfer paper P conveyed by a paper conveyance belt 60 described later. The developing roll 22Y includes a developing sleeve made of a non-magnetic pipe that is rotationally driven by a driving unit (not shown), and a magnet roller (not shown) that is included so as not to rotate. The developer is attracted and carried on the surface of the developing sleeve by the magnetic force generated by the magnet roller.

  The ST sensor 26Y composed of a magnetic permeability sensor is attached to the bottom plate of the developing case 21Y, and outputs a voltage having a value corresponding to the magnetic permeability of the developer conveyed by the first conveying screw 23Y. Since the magnetic permeability of the developer shows a good correlation with the toner concentration of the developer, the ST sensor 26Y outputs a voltage having a value corresponding to the Y toner concentration. This output voltage value is sent to a control unit (not shown). This control unit is provided with storage means such as a RAM, in which Y Vtref, which is a target value of the output voltage from the ST sensor 26Y, and output voltage from the ST sensor mounted in another developing device. Data on Vtref for M, C, and K, which are target values, is stored. For the developing device 20Y, the value of the output voltage from the ST sensor 26Y is compared with the Y Vtref, and the powder pump 27Y connected to a Y toner cartridge (not shown) is driven for a time corresponding to the comparison result. As a result, the Y toner in the Y toner cartridge is supplied into the developing device 20Y. By controlling the driving of the powder pump 27Y (toner replenishment control) in this way, an appropriate amount of Y toner is replenished to the developer whose Y toner density has decreased with development, and development in the developing device 20Y is performed. The Y toner concentration of the agent can be set within a predetermined range.

  As described above, the toner image forming portions 1Y, 1M, 1C, and 1K shown in FIG. 1 are visible to the photoconductors 11Y, 11M, 1C, and 1K in cooperation with the optical writing unit 2. A toner image as an image is formed. Therefore, in this printer, a toner image is formed on the surface of the photoreceptors 11Y, 11M, 11C, and 11K that moves endlessly by the combination of the toner image forming units 1Y, 1M, 1C, and 1K and the optical writing unit 2. Functions as a visible image forming means.

  Two paper feed cassettes 3 and 4 are disposed at the bottom of the printer body. These paper feed cassettes 3 and 4 accommodate a plurality of transfer papers P in a stack of transfer papers, and press the paper feed rollers 3a and 4a against the uppermost transfer paper P. Then, the sheet feeding rollers 3a and 4a are rotated at a predetermined timing to send the transfer sheet P to the sheet feeding path. A registration roller pair 5 is disposed at the end of the paper feed path, and the transferred transfer paper P is synchronized with the Y toner image formed on the photoreceptor 11Y of the Y toner image forming unit 1Y. At the timing to obtain, it sends out toward the transfer unit 6 described later.

  FIG. 3 is an enlarged configuration diagram illustrating a main configuration of the transfer unit 6 serving as a transfer unit. In the figure, the transfer unit 6 includes an endless paper transport belt 60, an entrance roller 61, an electrostatic adsorption roller 62, four transfer bias rollers 63Y, M, C, and K, and four transport support rollers 64Y, M, and C. , K, separation roller 65 and the like. Further, it also includes a drive roller 66, a belt cleaning device 67, a pressing roller 68, a tension roller 69, a lower roller 70, an inlet bracket 71, a swing bracket 72, an outlet bracket 73, a cam 74, and the like.

The paper transport belt 60 is a high resistance endless single layer belt having a volume resistivity of 10 ¹⁰ to 10 ¹² Ωcm and a surface resistivity of 10 ¹² to 10 ¹⁴ Ω / □, respectively. PVDF (polyvinylidene fluoride) is used. And it is made to endlessly move counterclockwise in the figure by the drive roller 66 rotated counterclockwise in the figure by a driving means (not shown) while being stretched by a plurality of rollers.

  The entrance roller 61, the transfer bias rollers 63Y to 63K, the conveyance support rollers 64Y to K, the separation roller 65, the driving roller 66, the tension roller 69, and the lower roller 70 are all in contact with the back surface (loop inner surface) of the paper conveyance belt 60. is doing. And it functions as a tension roller that tensions while supporting the paper transport belt 60 on the back surface. Among these stretching rollers, the entrance roller 61 disposed on the rightmost side in the drawing is configured to sandwich the paper transport belt 60 between the entrance roller 61 and the electrostatic attraction roller 62 disposed in the vicinity thereof. An electrostatic chucking bias is applied to the electrostatic chucking roller 62, and the transfer sheet P fed from the above-described registration roller pair 5 by applying an electric charge to the belt front surface (loop outer surface). Is electrostatically adsorbed.

  The four transfer bias rollers 63Y, 63M, 63C, and 63K are rollers in which an elastic body such as a sponge is coated on a metal core, and are pressed toward the photoreceptors 11Y, 11M, 11C, and 11K, respectively. The paper transport belt 60 is sandwiched. By this pressing, a transfer nip is formed in which the photoreceptors 11Y, 11M, 11C, and 11K and the paper transport belt 60 are in contact with each other with a predetermined length in the belt moving direction. Further, a transfer bias controlled at a constant current by a transfer bias power source is applied to the cores of the transfer bias rollers 63Y, 63M, 63C, and 63K, respectively. As a result, transfer charges are applied to the back surface of the paper transport belt 60 via the transfer bias rollers 63Y, 63M, 63C, and 63K, and the paper transport belt 60 and the photoreceptors 11Y, 11M, 11C, and 11K are transferred between the transfer nips. A transfer electric field is formed. In this printer, the transfer bias rollers 63Y, 63M, 63C, and 63K are provided as transfer bias members. However, a brush, a blade, or the like may be provided instead of the rollers.

  Of the four transfer bias rollers 63Y, M, C, and K, three for Y, M, and C are supported by the swing bracket 72 via bearing members (not shown). The swing bracket 72 is disposed inside the loop of the paper transport belt 60 and is configured to be swingable about a rotation shaft 72a. Of the four transport support rollers 64Y, 64M, 64C, and 64K, three for Y, M, and C are also supported by the swing bracket 72. Below the swinging bracket 72 in the figure, a cam 74 that is driven to rotate about a rotation shaft 74a by a driving means (not shown) is disposed. When this rotation is stopped at a position where the cam surface abuts against the swinging bracket 72, the swinging bracket 72 is swung counterclockwise around the rotation shaft 72a. Then, the transfer bias rollers 63Y, M, and C for Y, M, and C are brought into contact with the photoconductors 11Y, M, and C via the paper conveyance belt 60, and transfer nips for Y, M, and C are formed. The On the other hand, when the cam 74 is stopped at a position where the cam surface does not abut against the swing bracket 72, the swing bracket 72 is swung clockwise around the rotation shaft 72a. Then, the transfer bias rollers 63Y, M, and C for Y, M, and C move to a position where the paper transport belt 60 is not pressed against the photoreceptors 11Y, 11M, and 11C, and the transfer nip for Y, M, and C is transferred. Will not be formed. As described above, the transfer unit 6 forms a transfer nip for Y, M, and C by bringing the paper transport belt 60 into contact with the photoreceptors 11Y, M, and C by swinging the swing bracket 72, or transporting the paper. The belt 60 is separated from the photoconductors 11Y, 11M, and 11C.

  The entrance roller 61, the electrostatic adsorption roller 62, and the lower roller 70 are supported by the entrance bracket 71 via bearing members (not shown). The inlet bracket 71 is disposed inside the loop of the paper conveying belt 60 and is configured to be swingable about the axis of the lower roller 70. The above-mentioned swing bracket 72 has a guide hole 72b near the left end in the figure, and a pin 71a extending from the inlet bracket 71 is movably positioned inside the guide hole 72b. When the cam 74 swings counterclockwise in the figure, the pin 71 in the guide hole 72b is pushed up. Then, the inlet bracket 51 is linked to the swing of the swing bracket 72 and swung counterclockwise in the drawing around the axis of the lower roller 70, and the entrance roller 61, the electrostatic adsorption roller 62, and The lower roller 70 is pushed up. When the swing bracket 72 is swung clockwise in the figure, the inlet bracket 51 is linked to it and swings clockwise in the figure, and the inlet roller 61, the electrostatic adsorption roller 62 and the lower roller 70 are moved. Move down. By the movement of the entrance roller 61, the electrostatic attraction roller 62, and the lower roller 70 accompanying the swing of the swing bracket 72, the paper transport surface by the paper transport belt 60 is maintained in a straight line.

  When transferring the black monochrome toner image onto the transfer paper P, the transfer unit 6 swings the swing bracket 72 clockwise in the drawing to move the paper transport belt 60 to the Y, M, and C photoconductors. 11Y, M, C. When transferring a black monochrome toner image, the toner image is not transferred at the transfer nips for Y, M, and C. Therefore, the black monochrome toner image is transferred without forming these transfer nips. is there. As a result, it is possible to transfer a black monochromatic toner image without applying an extra load to the paper transport belt 60 and its drive system.

  Of the four transfer bias rollers 63Y, 63M, 63C, and 63K, the K transfer bias roller 63K is supported by the outlet bracket 73 via a bearing member (not shown). The outlet bracket 73 is disposed inside the loop of the paper conveyance belt 60 and is configured to be swingable about the axis of the outlet roller 65. Of the four conveyance support rollers 64Y, 64M, 64C, 64K, the conveyance support roller 64K for K is also supported by the outlet bracket 73. The transfer bias roller 63K for K moves to a position where the paper transport belt 60 is not pressed against the photoconductor 11K for K by the clockwise swing of the outlet bracket 73 in the drawing. In this state, when the swing bracket 72 described above swings clockwise in the drawing, the paper transport belt 60 is separated from all the photoreceptors 11Y, 11M, 11C, and 11K. The transfer unit 6 can be attached to and detached from the printer main body in such a state that the paper transport belt 60 is separated from all the photoconductors.

  When transferring a full color image, which will be described later, to the transfer paper P, the transfer unit 6 brings the paper transport belt 60 into contact with all the photoconductors 11Y, 11M, 11C, 11K, and is used for Y, M, C, K. Form a transfer nip. The transfer paper P sent out from the registration roller pair 5 is sandwiched between the electrostatic adsorption roller 62 and the paper transport belt 60. Then, the toner passes through the transfer nips for Y, M, C, and K sequentially while being attracted to the front surface of the paper transport belt 60. As a result, the Y, M, C, and K toner images on the photoconductors 11Y, 11M, 11C, and 11K are superimposed on the transfer paper P at the transfer nip, and the transfer paper is subjected to the effects of the transfer electric field and nip pressure. The image is superimposed on P and transferred. A full-color image is formed on the transfer paper P by this superposition transfer.

  The transfer paper P on which the full-color image is formed approaches the belt stretching position by the separation roller 65 as the paper conveying belt 60 moves endlessly. At this belt stretching position, the separation roller 65 stretches the paper transport belt 60 at a steep winding angle that reverses the endless movement direction of the paper transport belt 60. The transfer paper P adsorbed on the paper transport belt 60 cannot follow such a sudden change in the moving direction of the belt and is separated from the paper transport belt 60. Then, it is delivered to the fixing unit (8 in FIG. 1).

  The tension roller 69 is biased toward the paper transport belt 60 by a spring, thereby applying a predetermined tension to the paper transport belt 60. The pressing roller 68 is pressed against the front surface of the belt extension portion between the tension roller 69 and the driving roller 67. By this pressing, the paper transport belt 60 is greatly depressed and curved between the driving roller 67 and the tension roller 69 in the loop. Since the paper conveying belt 60 is greatly curved in this manner, a larger winding portion of the paper conveying belt 60 around the driving roller 67 is secured. The belt cleaning device 67 is in contact with the front surface of the winding portion. On the front surface of the paper conveying belt 60 that has transferred the transfer paper P to the fixing unit at the position where the separation roller 65 is stretched, the dirt toner transferred from the photoreceptors 11Y, 11M, 11C, and 11K is transferred. It is attached. The belt cleaning device 67 is for removing the dirty toner from the paper transport belt 60.

  In FIG. 1 described above, the fixing unit 8 includes a pressure roller 8a, an endless fixing belt 8b, a heating roller 8c, a driving roller 8d, and the like. The fixing belt 8b is endlessly moved clockwise in the drawing by a driving roller 8d that is rotated by a driving unit (not shown) while being stretched by a heating roller 8c and a driving roller 8d. The heating roller 8c includes a heat source such as a halogen lamp, and thereby heats the paper transport belt 8b from the back surface. On the other hand, the pressure roller 8a is rotated so as to move the surface in the same manner as the belt at the contact portion while contacting the fixing belt 8b that is moved endlessly to form a fixing nip. The transfer paper P transferred from the paper transport belt 60 of the transfer unit 6 to the fixing unit 8 is sandwiched between the fixing nips in such a posture that the image transfer surface is in contact with the fixing belt 8b. Then, it passes through the fixing unit 8 while the full color image is fixed on the image transfer surface by heating or pressing.

  The transfer paper P that has passed through the fixing unit 8 passes through a pair of conveyance rollers, a reversing guide plate, and the like, and is further discharged through a pair of conveyance rollers toward a stack portion provided on the upper surface of the printer housing.

  In FIG. 2 described above, the surface of the photoreceptor 11Y after passing through the transfer nip for Y is coated with a predetermined amount of lubricant by the brush roller 12Y and then cleaned by the counter blade 13Y. Then, the static electricity is removed by the light emitted from the static elimination lamp 14Y to prepare for the formation of the next electrostatic latent image.

  A small amount of toner that could not be completely removed remains on the surface of the photoreceptor 11Y cleaned by the counter blade 13Y. The cleaning residual toner remaining in this way is cleaned by the roller cleaning device 16Y.

  Next, the ST sensor 26Y will be described. FIG. 4 is a circuit configuration diagram of the ST sensor. As shown in FIG. 4, the ST sensor 26Y includes an oscillation circuit 100, a resonance circuit 110, a phase comparison circuit 120, a smoothing circuit 130, and an amplification circuit 140. A memory chip 150, which is a non-volatile memory, is provided on the same substrate as the ST sensor circuit board. FIG. 5 is a diagram illustrating a power supply circuit that supplies driving power to each circuit. As shown in FIG. 5, a voltage of about 12 V is supplied to the power supply circuit via the connector 28 from the drive power supply device 160 in the image forming apparatus. The power supply circuit is provided with a decompression circuit 170. The decompression circuit 170 decompresses the voltage of about 12V to about 5V and supplies the voltage to the oscillation circuit 100, the phase comparison circuit 120, and the memory chip 150, respectively. On the other hand, a 12V voltage is supplied to the OP amplifier provided in the smoothing circuit 130 and the OP amplifier provided in the amplifier circuit 140.

As shown in FIG. 4, the oscillation circuit 100 oscillates using an oscillator 101 such as crystal or ceramics, and oscillates at a frequency of about 4 [MHZ]. The oscillation circuit 100 is applied with a voltage reduced to about 5 [V] by the drive power supply circuit. The 5 [V] voltage is converted into a voltage V ₁ having a rectangular waveform of about 4 [MHZ] as shown in FIG. 6A and output to the resonance circuit 110.

The resonance circuit 110 includes a first resonance circuit composed of a resistor R3 and a first coil L1, and a second resonance circuit composed of a second coil L2 coupled to the first coil L1 with a magnetic coupling coefficient k. ing. Further, the first resonance circuit and the second resonance circuit are shared by three capacitors C1, C2, and C3. Thus, by sharing the capacitor between the first resonance circuit and the second resonance circuit, the first resonance circuit and the second resonance circuit can have equivalent resonance characteristics. The second coil L2 is provided facing the first coil L1, and forms a resonance point. Output V ₁ of the from the oscillation circuit 100 is input to the first coil L1 via the resistor R3. By inputting the output V ₁ of the from the oscillation circuit 100 to the first coil L1 via the resistor R3, it is possible to increase the input impedance at the resonance point. Further, the resistor R3 can prevent the oscillation circuit 100 from being affected by the resonance circuit 110 and becoming unstable in oscillation. The self-inductance of the first coil L1 and the second coil L2 is 8.15 [μH].

The second resonant circuit, the voltage V ₂ as the voltages V ₁ input to the first coil L1 cancel at the resonance point is output from the second coil L2. At this time, the mutual inductance between the first coil L1 and the second coil L2 is changed by the magnetic permeability of the developer 111 in the vicinity of the first coil L1 and the second coil L2, and the second coil L2 is changed. output value V ₂ outputted from the changes. The magnetic permeability of the developer 111 varies depending on the mixing ratio of the magnetic carrier and the nonmagnetic toner. When the toner concentration is low, the magnetic permeability of the developer is high. When the toner concentration is high, the magnetic permeability of the developer is high. Lower. The voltage V ₂ output from the second coil L ₂ of the second resonance circuit is a sine wave as shown in FIG. 6B, and the solid line in FIG. The broken line in FIG. 6B is the waveform when the toner density is lower than the appropriate value. In this manner, the toner density of the developer varies, the mutual impedance changes at the resonance point, it can be seen that the phase difference in the second waveform output from the coil L ₂ occurs.

The voltage V ₂ output from the second coil L ₂ of the second resonance circuit is a SIN wave as shown in B of FIG. 6, and this SIN wave is input to the phase comparison circuit 120. Phase comparing circuit 120, the inverting amplifier IC2-2 for inverting amplifying the inputted SIN wave, comparator for comparing the output value V ₃ outputted from the inverting amplifier and the output value V ₁ of the from the oscillation circuit 100 IC2-3. Inverting amplifier IC2-2 inputs the AC voltage V ₂ of the DC voltage and sine wave output from the second coil L2 from the power supply circuit, not shown, performs the XOR operation, as shown in C of FIG. 6 Outputs a rectangular waveform. The comparator IC2-3 performs an XOR operation to input and output V ₃ from the inverting amplifier IC2-2 as shown in C of the output V ₁ and FIG. 6 from the oscillation circuit 120 shown in A of FIG. 6 . Then, only the phase component as shown in FIG. 6D is output from the comparator IC2-3.

  As shown in FIG. 6D, the output from the comparator IC2-3 when the toner concentration indicated by the broken line is lower than the output waveform output from the comparator IC2-3 when the toner concentration indicated by the solid line is appropriate. It can be seen that the ON interval of the output waveform is long.

A waveform as shown in FIG. 6D is output V ₄ from the phase comparison circuit and input to the smoothing circuit 130. The smoothing circuit 130 includes an OP amplifier IC-1, and a flat waveform as shown in FIG. 6E is output from this OP amplifier. Output waveform V ₅ from OP amplifier shown in E of FIG. 6 is the average value of the waveform shown in FIG. 6D. The solid line is the output voltage V _5-1 when the toner density is appropriate, and the broken line is the output voltage V _5-2 when the toner density is lower than the appropriate value. As described above, the output voltage V _5-2 indicated by a broken line when the toner density is lower than the appropriate value has a longer output waveform ON interval as shown in FIG. 6D. It can be seen that it is higher than the output voltage _V5-1 .

The output value V ₅ from the smoothing circuit 130 is amplified by the amplifier circuit 140. Output value V ₅ output from the smoothing circuit 130, even if the toner density difference is a maximum, about 0.5 [V] of only difference appears. Therefore, the amplifier circuit 140 amplifies the difference between the control voltage V _cont and the output voltage V ₅ output from the smoothing circuit 130 by a factor of 4 to obtain the output voltage V _out of the ST sensor 26Y.

The ST sensor 26Y has a variation in the relationship between the toner concentration and the output voltage due to variations in characteristics among the sensors and variations in the magnetism of the magnetic carrier in the developing device. Therefore, it is necessary to adjust the control voltage V _cont when replacing the developing device 20Y so that the relationship between the toner density and the output voltage is a predetermined relationship. For this reason, when the developing device 20Y is replaced, the replacement initial operation mode is executed to adjust the control voltage V _cont . The initial setting mode will be described below. FIG. 7 is a control flow for adjusting the control voltage V _cont of the ST sensor 26Y. First, it is checked whether or not the user or service man has replaced the developing device 20Y and executed the replacement initial operation mode (S1). When the replacement initial operation mode is executed, the toner density is detected by the ST sensor (S2). As for the developer in the new (or regenerated) developing device to be replaced by the user or service person, the toner concentration is adjusted to a predetermined value (5%) in advance. Next, the output voltage V _out of the ST sensor 26Y is output with the control voltage V _cont stored in the memory (RAM) in the image forming apparatus. The image forming apparatus stores a reference output voltage (3 V) at a toner concentration of 5%, and checks whether the output voltage V _out of the ST sensor 26Y is the reference output voltage (3 V) (S3). When the output voltage _Vout of the ST sensor 26Y is not the reference output voltage (3V), the control voltage _Vcont is adjusted so that the output voltage _Vout of the ST sensor 26Y becomes the reference output voltage (3V). (S4). Various methods can be used to adjust the control voltage. For example, a method of obtaining an adjustment amount of the control voltage from a difference between the reference output voltage and the output voltage, a method of feeding back the output voltage, and adjusting the control voltage so as to gradually become the reference output voltage are used. it can. First, input a control voltage so that the output voltage deviates significantly from the reference voltage, then input a value half that of the first input control voltage, and then input another half of the control voltage value. To do. In this way, it is also possible to use a two-division method in which the value of the control voltage is gradually reduced to bring the output voltage closer to the reference output voltage.
When the output voltage V _out of the ST sensor 26Y becomes the reference output voltage (3V), the changed control voltage V _cont is within a predetermined range (± 1V) of the reference control voltage V _cont stored in the image forming apparatus. It is checked whether it exists (S5). This reference control voltage is a control voltage when the standard toner density sensor is adjusted so that the output voltage (3.0 V) when the toner density is 5% is obtained. When the changed control voltage V _cont is within the predetermined range of the reference control voltage (YES in S5), the control voltage value stored in the memory in the image forming apparatus is rewritten to the changed control voltage value (S6). When the changed control voltage value is rewritten, the developer is stirred to increase the charge amount of the toner in the developing device. Next, using the rewritten control voltage value, the toner is added to the developer and stirred so that the output voltage V _out becomes the target voltage V _tref (the output voltage is about 2.2 V when the toner concentration is 7%). (S7).
On the other hand, when the changed control voltage V _cont is outside the predetermined range (± 1 V or more) (NO in S5), a new / reproduced developing device having a toner concentration of 5% in the developing device is mounted. Rather, there is a possibility that the replacement initial operation mode was erroneously executed in a state where an old developing device having a toner density other than 5% is installed or in a state where the toner has already been added and the toner density is 7%. Is high, a warning to that effect is displayed (S9).

  The toner density in the new developing device is as low as 5% for the following reason. The toner in the initial developing device is not charged at all and is likely to cause toner scattering during stirring. When the toner concentration in the new developing device is increased, the toner amount in the developing device increases accordingly, and the amount of toner scattering increases accordingly. For this reason, the toner concentration of the developer in the new developing device is kept as low as 5% to suppress the toner scattering during the initial stirring. Then, after the charge amount of the toner is increased by agitation, toner scattering can be suppressed by adding the toner to a toner concentration of 7%.

Next, the memory chip 150 provided on the same substrate as the circuit of the ST sensor 26 will be described in detail. As described above, the memory chip 150 is supplied with power reduced to 5 V from the same power supply circuit as the ST sensor 26. As shown in FIG. 4, the control voltage V _cont for controlling the output voltage of the ST sensor 26 is used as the control voltage for controlling the memory chip 150.

  The memory chip 150 stores manufacturing lots and usage histories of parts mounted on a process cartridge such as a photoconductor, developer, and ST sensor 26. The memory chip 150 stores the sensitivity (toner concentration / output voltage) of the ST sensor 26, the reference control voltage, the reference output voltage (3V), and the like as the characteristic information of the ST sensor 26. Further, a use history of the process cartridge itself is also stored. The sensitivity of the ST sensor 26 is a value when measured using a magnetic material serving as a reference when the ST sensor is manufactured. Note that the magnetic force of the magnetic material is approximately the same as the magnetic force of the developer when the toner concentration of the developer is 5%. Thus, since the sensitivity is obtained from the value actually measured by the ST sensor 26, this sensitivity value is a value unique to the ST sensor 26. The reference control voltage is also a control voltage when the output voltage when the magnetic material is measured is adjusted to be the reference voltage 3V. Therefore, the value of the reference control voltage is also a unique value of the ST sensor 26.

  Information stored in the memory chip 150 is updated or the like by appropriately communicating with the image forming apparatus. As shown in FIG. 2, communication between the memory chip 150 and the image forming apparatus is performed via a connector 28 that connects the ST sensor 26 and the image forming apparatus.

  FIG. 8 is a control block diagram for performing communication between the ST sensor 26 and the image forming apparatus. As shown in FIG. 8, the CPU or ASIC of the image forming apparatus has a master device 200 that controls the memory chips of the respective colors. Communication is performed by connecting the master device 200 to the signal line of the memory chip 150 mounted on the ST sensor 26Y of each color. Specifically, each memory chip 150 mounted on the ST sensor 26 of each color has a unique address, and one-to-one communication can be performed by specifying an address from the master device 200. ing. Each color ST sensor is provided with a circuit (PWM 1 to 4) for generating a control voltage from the CPU or ASIC to the ST sensor for each color. In addition, circuits (ADC1 to ADC4) for outputting an output voltage output when the ST sensor 26 detects the toner density to the CPU or the ASIC are provided for each color. Further, the connection between the master device 200 and the signal line of the memory chip 150 is made via the connector 28 shown in FIG.

Next, the replacement initial operation mode when sensitivity information, reference control voltage, and reference output voltage as characteristic information of the toner density sensor are stored in the memory chip 150 of the ST sensor 26 will be described. First, communication with the memory chip 150 of the ST sensor 26 is performed, and sensitivity information (toner concentration / output voltage), a reference control voltage, and a reference output voltage (3 V) are read out. Next, as described above, the toner density in the developing device is detected, and the control voltage is adjusted to be the reference output voltage (3 V). And the adjusted control voltage,
When the adjusted control voltage is within ± 0.3 V compared with the reference control voltage, the value of the control voltage stored in the ST sensor is written in the nonvolatile memory of the image forming apparatus. After writing in the nonvolatile memory of the image forming apparatus, an output voltage (target voltage) at a toner concentration of 7% is obtained based on sensitivity information (toner concentration / output voltage) stored in the memory chip. Then, the toner is added to the developer and stirred so that the output voltage _Vout becomes the _calculated target voltage _Vtref (toner concentration 7%). On the other hand, when the control voltage is ± 0.3 V or more, a warning is displayed without adding toner.
As described above, by using the reference control voltage unique to the toner density sensor stored in the memory chip 150, the predetermined range can be narrowed from ± 1.0V to ± 0.3V. Since this is a control voltage adjusted using a standard toner density sensor stored in the image forming apparatus, it is necessary to take into account variations in the toner density sensor. It is necessary to set it to 0V. However, since the reference control voltage stored in the memory chip 150 is a reference control voltage unique to the toner density sensor, it is not necessary to take into account variations in the toner density sensor within a predetermined range. For this reason, when the reference control voltage stored in the memory chip 150 is used, only the magnetic variation of the magnetic carrier of the developer needs to be taken into consideration, so that the predetermined range can be narrowed to ± 0.3V. Therefore, determination with higher accuracy can be executed.

In the present embodiment, as shown in FIG. 4, a circuit that generates the control voltage V _cont of the ST sensor is shared with a signal that controls reading / writing of the memory chip 150. For this reason, if a signal for controlling reading / writing of the memory chip 150 is supplied in the same manner as a signal for generating the control voltage V _cont of the ST sensor 26, the memory chip 150 may malfunction. Therefore, in this embodiment, the control signal supplied to the ST sensor is controlled to prevent the malfunction of the memory chip so that the memory chip 150 does not malfunction. This control will be described below.

FIG. 9 is a check flow performed for the initial operation when the power is turned on. 10 to 12 are diagrams showing control signals between the image forming apparatus and the ST sensor 26. FIG. As shown in FIG. 9, first, when the image forming apparatus is powered on, detection control is performed to determine whether or not a process cartridge is set (S11). In the detection of the process cartridge, first, the control of the master device 200 (I ² C) is stopped, and the SCL and SDA are deactivated as shown in FIG. 10 (S12). Accordingly, communication is not performed between the memory chips 150 of the respective colors and the image forming apparatus, and writing / reading of the memory chips is not performed even when the control voltage V _cont is applied. Next, as shown in FIG. 10, control voltages V _{cont1 to} V _cont4 are respectively applied to the respective colors (S13), and the toner density of each color is detected (S14). At this time, the control voltage of each color does not need to be a control voltage corresponding to each sensor, and may be a voltage set arbitrarily. When the toner density of each color is detected, output voltages V _{out1 to} V _out4 of each color are output to the image forming apparatus. The image forming apparatus detects the output voltages V _{out1 to} V _out4 for each color and checks whether it is 2.5 V or more (S15). If the output voltage is 2.5 V or less (No in S15), there is a process cartridge that is not set in the image forming apparatus, so that a warning is displayed. When the output voltage is 2.5 V or more (YES in S15), the process cartridge is normally set in the image forming apparatus, and the following control is executed.

When the process cartridge is normally set in the image forming apparatus, control for checking whether or not the process cartridge set in the image forming apparatus is new is executed (S18). In the new process cartridge, a new flag is stored in the memory chip of the ST sensor. Then, communication is performed between the memory chip and the image forming apparatus, and whether or not the process cartridge in the image forming apparatus is a new process cartridge is checked based on whether or not a new product flag is stored in the memory chip. In the new process control flow of the process cartridge, all the control voltage signals output from the image forming apparatus to the ST sensor are set to 100% LOW (S19). Then, as shown in FIG. 11, the control voltage V _cont1 applied to the Y-color ST sensor is set to a state of 100% HI (S20). Next, communication control of the master device (I2C) is started (S21). Specifically, an address designation signal and a new flag read signal are transmitted from the master device of the image forming apparatus to the Y-color memory chip. At this time, since the control voltages V _{cont2 to} V _cont4 are not applied to the M, C, and K ST sensors, the memories of other colors do not malfunction with respect to the read signal for the Y color. The Y-color memory chip receives this signal and forms the image of the stored new flag information by using a serial clock (data transfer clock) of 100/400 [KHZ] as shown in FIG. 11 and serial data. The data is transmitted to the device (S22). The image forming apparatus checks whether there is a new flag from the data transmitted from the Y-color memory chip 150Y (S23). If there is (YES in S23), the image forming apparatus determines that it is new, and if not (NO in S23). ) Is determined to be a used process cartridge. If the Y color process cartridge is new (YES in S24), a signal for canceling the new flag is transmitted from the image forming apparatus to the Y color memory chip and stored in the Y color memory chip. A new article flag is canceled (S25). In addition, the process cartridge and the toner bottle are provided separately. When the product is new, the above-mentioned new flag is canceled in the case of an image forming apparatus in which a process cartridge in which no toner is loaded is installed in the developing device. In addition to the signal to be transmitted, a signal for writing the Y color code to the memory chip is transmitted.

  When the process cartridge new article detection control is finished, an erroneous set detection control is performed (S26). This flow of erroneous set detection can be performed with substantially the same control flow as that for detecting a new process cartridge. In other words, in the case of erroneous detection control, information read from the memory chip by performing communication between the image forming apparatus and the memory chip of the ST sensor is merely changed from the new flag information to the color information. That is, only the Y color control voltage is set to the 100% HI state, communication is performed with the memory chip of the process cartridge mounted at the Y color location, and the color information is read. If the color information in the memory is Y color information (YES in S27), it is determined that the process cartridge is mounted at the correct position. If the color information of the memory chip is not Y color information (NO in S27), it is determined that there is an abnormality. If it is determined that there is an abnormality due to erroneous set detection (YES in S28), an error message is displayed (S29).

If the color information in the memory is Y-color information (NO in S28), then communication with the image forming apparatus is performed, and the contents stored in the Y-color memory chip are read (S30). Specifically, as shown in FIG. 12, as in the case of new article detection or erroneous set detection, only the Y-color control voltage V _cont1 is set to the 100% HI state, and the control voltages V of other colors (M, C, B). _{cont2 to} V _cont4 are _set to a 100% LOW state. Then, the image forming apparatus transmits a signal to the Y color memory chip so as to transmit the information stored in the Y color memory chip to the image forming apparatus. The Y-color memory chip transmits a communication signal including a serial clock and serial data, and transmits information stored in the memory chip to the image forming apparatus. Information to be transmitted to the image forming apparatus includes the usage history of parts in the process cartridge, the usage history information of the process cartridge itself, and the like. Then, the usage history information is updated, and the updated information is transmitted to the memory chip and stored in the memory chip. (S31). These usage histories in the process cartridge stored in the memory chip are read out when the process cartridge is recycled, and only the parts that have reached the end of their life are replaced and reproduced as a reproduction process cartridge.

  In addition, when a manufacturing lot is stored in a memory chip and the contents of the memory chip are read out, this information is also read out to determine whether the process cartridge mounted in the image forming apparatus is a genuine product from the manufacturing lot. You may make it judge. If the production lot of the process cartridge installed in the image forming apparatus is not regular, the user can replace the process cartridge by disabling image formation or forming a deteriorated image by changing the image formation conditions. Prompt. Further, when a process cartridge fails, the manufacturing history can be traced back from the manufacturing lot, and the cause of the failure can be easily analyzed.

Further, when reading the contents of the memory chip, the life and deterioration state of the process cartridge may be grasped from the use history of the components stored in the memory chip and the use history of the process cartridge itself. In order to ascertain the lifetime, in addition to the parts and process cartridge usage history, the memory cartridge stores the process cartridge parts and the warranty period of the process cartridge, the limit copy number, and the like. Then, life information such as the warranty period and the limit copy number is read from the memory chip together with the component usage history. The CPU in the image forming apparatus compares the use history with the life information, and if the use history exceeds the life information, a warning is displayed indicating that the process cartridge has reached the end of its life. Such life detection of the process cartridge is not limited to the initial operation when the power is turned on, but can be performed at a predetermined timing, for example, when a predetermined number of copies are executed. Note that the above-described components indicate devices such as a developing device and a charging device in addition to the photosensitive member and the developing roller in the process cartridge.
In order to grasp the deterioration state, the deterioration state of the process cartridge is grasped from the read use history information. Then, the development conditions and the like are changed in accordance with the deterioration state.

  Further, when reading the contents of the memory chip, the sensitivity (toner concentration / output voltage) and detection level (control voltage / output voltage) specific to this ST sensor are read and this information is stored in the memory of the image forming apparatus. . Sensitivity information is used for toner density control, and detection level information is read from the image forming apparatus in the above-described replacement initial operation mode.

As described above, after communicating with the memory chip of the process cartridge mounted at the Y color position and detecting the new article detection, the erroneous set detection, and the writing of the use history to the memory chip, the M color position is mounted next. Control of new product detection, erroneous set detection, and information update of memory chips is performed for the process cartridges. This control flow is almost the same as the control flow performed with the process cartridge mounted at the Y color position. When communicating with the memory of the process cartridge mounted at the M color position, the control voltage V _cont2 at the M color position is set to the 100% HI state, and the other control voltages V _cont1 , V _cont3 , and V _cont4 are _set to 100%. Communication with the memory chip is performed in the LOW state. After detecting the new position of the M color position, detecting the wrong set, and updating the memory chip information in this way, the same communication control is performed for the process cartridges mounted at the C color position and the K color position. Perform new article detection, erroneous set detection, and update of memory chip information.

  In the above, new detection, erroneous set detection for a process cartridge mounted at a certain color position, and detection of a new cartridge, erroneous setting for a process cartridge mounted at a different color position after updating memory chip information Detection and update of memory chip information. However, the present invention is not limited to this. For example, after a new product is detected for a process cartridge mounted at a Y color position, a new product is detected for each of the process cartridges mounted at an M color, C color, and K color position. You may make it do. Then, when the detection of a new product for each process cartridge mounted at each color position is completed, an erroneous set detection is performed for each process cartridge mounted at each color position. When the erroneous setting detection of each process cartridge mounted at each color position is completed, the information of the memory chip of each process cartridge mounted at each color position is updated.

Next, voltage control at the time of toner density detection will be described. FIG. 13 is a flowchart of voltage control when toner density control is performed. As shown in FIG. 13, first, the control voltages V _{cont1 to} V _cont4 of each color are _set to a 100% LOW state (S41). Next, control of the master device (I ² C) in the image forming apparatus is stopped (S42). Thereby, even when a voltage for generating a control voltage is applied to the ST sensor, the memory chip in the ST sensor does not malfunction. Next, as shown in FIG. 14, in order to detect the toner density, a control voltage is generated and output with a predetermined PWM signal for each color stored in the image forming apparatus. When the stirring is completed (S44), the output voltages _Vout1 to _{Vout4 of} each color are read (S45), and the above-described toner density control is executed based on these output voltages (S46). The signal for generating the control voltage is a PWM signal, which is different from the signals for controlling the memory (100% HI, 100% LOW). Therefore, it is possible to prevent the memory from malfunctioning with a signal that generates the control voltage.

  In the present embodiment, the example in which the memory chip is provided on the same substrate as the ST sensor has been described. However, the present invention is not limited to this. For example, the memory chip may be provided on the same substrate as the P sensor.

(1)
As described above, according to the image forming apparatus of the present embodiment, in the replacement initial operation mode, the control voltage V _cont in which the output voltage _VOUT obtained when detecting the toner density in the developing device is adjusted to the reference output voltage (3V). Is within ± 1 V of the reference control voltage, the control voltage V _cont is updated to the adjusted control voltage. As a result, the replacement initial operation mode is once executed, and the replacement initial operation mode is executed again for the developing device that has already been changed from the initial 5% toner density to the 7% toner density that allows good image formation. However, the control voltage obtained at this time is outside the predetermined range of the reference control voltage. Therefore, since the control voltage at this time is not stored in the control voltage storage means, toner density control is not performed using the control voltage at this time. As a result, even when the replacement initial operation mode is executed again, the toner density in the developing device is suppressed from being 7% or more, and a good image can be maintained.
(2)
Further, the toner density sensor of the present embodiment includes a memory chip 150 as a storage unit that stores characteristic information of the toner density sensor. As described above, by providing a memory chip in the toner density sensor and storing characteristic information unique to the toner density sensor in the memory chip 150, toner density control can be performed based on the characteristic information unique to the toner density sensor. . Therefore, more accurate toner density control can be performed as compared with a conventional toner density control based on the characteristics of a general toner density sensor.
(3)
In addition, according to the toner density sensor of the present embodiment, the above characteristic information is measured using a reference output voltage and a reference device having the same characteristics as a developer having a predetermined toner density at the time of manufacture using this toner density sensor. The reference control voltage adjusted so that the output voltage at that time is the reference output voltage. Thereby, the predetermined range of the reference control voltage can be narrowed when the replacement initial operation mode is executed. This is because when a reference control voltage adjusted using a standard toner density sensor is used, it is necessary to take into account variations in the toner density sensor, so the predetermined range needs to be set wider as ± 1.0V. is there. However, if a reference control voltage unique to the toner density sensor is used, it is not necessary to take into account variations in the toner density sensor within a predetermined range. For this reason, when the reference control voltage stored in the memory chip 150 is used, only the magnetic variation of the magnetic carrier of the developer needs to be taken into consideration, so that the predetermined range can be narrowed to ± 0.3V. Therefore, determination with higher accuracy can be executed.
(4)
Further, according to the toner concentration sensor of the present embodiment, the characteristic information is sensitivity information obtained from measurement data obtained by measuring a reference device as a measurement reference using the toner concentration sensor at the time of manufacture. . Here, the sensitivity information indicates the relationship between the toner density and the output voltage, and is the slope (toner density / output voltage) obtained when the toner density is the vertical axis and the output voltage is the horizontal axis. As described above, the sensitivity information (toner concentration / output voltage) as the characteristic information stored in the memory chip 150 is obtained based on the value measured by the reference device that is the actual measurement reference at the time of manufacture. The value is specific to the toner density sensor.
On the other hand, the output voltage 2.2 V (target voltage) for achieving a toner density (7%) at which image formation can be satisfactorily performed is the sensitivity information (toner density / output voltage) and the reference output voltage at a toner density of 5%. It is calculated from 3V. In the present embodiment, sensitivity information unique to the toner density sensor is used, so that an accurate target voltage can be obtained as compared with a conventional method for obtaining a target voltage using general sensitivity information. For this reason, if the toner is added and the output voltage of the toner density sensor is set to the target voltage, the toner density in the developing device can be reduced to 7%. Therefore, scattering of toner due to excessive toner at the time of image formation, carrier adhesion due to lack of toner, and the like are suppressed, and a good image can be obtained.
(5)
In the toner concentration sensor of the present embodiment, the driving power source for driving the toner concentration sensor is the same as the driving power source for driving the storage unit, and the pressure from the driving power source supplied to the storage unit is reduced. Means are provided. As the driving voltage for driving the toner density sensor, a voltage of 12 V at the maximum is necessary, and the voltage of the driving power source is 12 V. On the other hand, the drive voltage for driving the storage means is 5V. Therefore, as described above, the driving power supply of the toner density sensor and the driving power supply of the storage means can be made the same by reducing the voltage of the driving power supply to 5 V by the pressure reducing means and then supplying it as the driving voltage of the storage means. it can. Thereby, the circuit to the drive power source of the toner density sensor and the circuit to the drive power source of the storage means can be made common, and the circuit board can be made small. Therefore, the ST sensor 26 can be reduced in size.
(6)
In the toner density sensor of the present embodiment, the control voltage signal line for controlling the output voltage of the toner density sensor is the same as the signal line for controlling the writing / reading of the recording means. Thereby, a circuit board can be made small and ST sensor can be reduced in size.
(7)
As shown in FIG. 13, the control voltage for detecting the toner density is generated by a so-called PWM signal that obtains a predetermined voltage value by changing the HI / LOW interval. As described above, when the signal line for controlling the writing / reading of the storage means and the signal line for the control voltage for toner density detection are the same, a control voltage for toner density detection is generated as a signal for controlling the writing / reading of the storage means. If the PWM signal is the same as the signal, there are the following problems. That is, there is a problem that a signal for generating a control voltage for toner density detection is mistaken for a signal for controlling writing / reading of the storage means and the storage means malfunctions. Therefore, in the toner density sensor of the present embodiment, the signal for controlling the writing / reading of the storage unit is a signal that takes only one value of HI or LOW during the writing / reading of the storage unit. As a result, the signal for generating the control voltage for toner density detection and the signal for writing / reading the storage means can be made different, and the malfunction of the storage means due to the signal for generating the control voltage for toner density detection is suppressed. can do.
(8)
The image forming apparatus according to the present embodiment includes a storage unit, a communication unit for connecting the communication unit of the storage unit and the communication unit of the image forming apparatus, and an electric circuit of the toner density sensor to the process cartridge. And a circuit connection unit for connecting to an electric circuit on the image forming apparatus main body side. And the said communication connection part is provided in the circuit connection part. This eliminates the need to separately connect the communication connection portion and the circuit connection portion when the process cartridge is mounted as in the prior art. That is, it is possible to connect the communication unit of the storage unit and the communication unit of the image forming apparatus only by connecting a circuit connecting unit for connecting the electric circuit of the toner density sensor and the electric circuit on the image forming apparatus main body side. it can. Therefore, one connection work can be reduced, and the mounting workability of the process cartridge can be improved.
(9)
In the image forming apparatus according to the present embodiment, the storage unit stores manufacturing information related to the process cartridge. From this manufacturing information, it is possible to determine whether or not the process cartridge attached to the image forming apparatus is a genuine product. Further, when a process cartridge fails, the manufacturing history can be investigated retrospectively from the manufacturing information, and cause analysis at the time of occurrence of the failure can be easily performed.
(10)
In the image forming apparatus according to the present embodiment, the use history of the process cartridge is recorded in the storage unit. By using the use history stored in the storage means, the deterioration state of the process cartridge can be grasped, and the image forming conditions such as the development conditions can be appropriately changed according to the deterioration state of the process cartridge. Thereby, a good image can be maintained. Further, the life of the process cartridge can be grasped from the use history of the process cartridge.
(11)
In the image forming apparatus according to the present embodiment, the storage history of the components mounted on the process cartridge is stored in the storage unit. Based on the usage history of this part, it is possible to replace the part in the process cartridge that has reached the end of its life and regenerate the process cartridge.
(12)
The image forming apparatus according to the present embodiment uses the toner density sensors (2) to (8) described above. Thus, accurate toner density detection, toner density control, and replacement initial operation mode can be executed.
(13)
In addition, the image forming apparatus according to the present embodiment includes a master device as a request unit that requests writing / reading to the storage unit in the image forming apparatus, and when the toner density is detected, Control has stopped. As a result, even if the memory chip malfunctions due to the control voltage of the toner density sensor during the toner density detection, communication with the image forming apparatus is performed and data in the storage unit is updated. Can do.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. FIG. 3 is an enlarged configuration diagram illustrating a Y toner image forming unit together with a part of a transfer unit among four toner image forming units in the printer. FIG. 3 is an enlarged configuration diagram illustrating a main configuration of the transfer unit. The circuit diagram of the ST sensor. The figure which showed the power supply circuit which supplies drive power to each circuit. The figure which showed the waveform output from each circuit. The figure which showed the control flow for adjusting the control voltage of ST sensor. FIG. 3 is a control block diagram for performing communication between an ST sensor and an image forming apparatus. The figure which showed the check flow performed for the initial operation at the time of power-on. The figure which showed the control signal in process cartridge set detection. The figure which showed the control signal in process cartridge new article detection / erroneous set detection. The figure which showed the control signal when performing writing / reading of a memory chip. 6 is a flowchart of voltage control when toner density control is performed. The figure which showed the control signal when performing toner density control.

Explanation of symbols

10Y, M, C, K Process cartridge 11Y, M, C, K Photosensitive body (endless moving body)
20Y, M, C, K Developing device 26Y, M, C, K ST sensor 60 Paper transport belt (intermediate member, endless belt)
63Y, M, C, K Transfer bias roller

Claims (13)

An image forming apparatus in which a two-component developer composed of magnetic particles and toner is accommodated, and a developer container equipped with a toner concentration sensor for detecting the toner concentration of the two-component developer is detachably mounted.
When the developer container is attached to the image forming apparatus, the output voltage obtained so that the output voltage obtained from the toner density sensor by detecting the toner density becomes the pre-stored reference output voltage. The control voltage stored in the control voltage storage means is updated to the adjusted control voltage, and the developer toner in the developer container is updated using the updated control voltage. In the replacement initial operation mode in which the toner is replenished so that the density becomes a desired toner density, the developer adjusted to a predetermined toner density stored in the initial developer container by a standard toner density sensor Control voltage storage means when the adjusted control voltage is within a predetermined range of the reference control voltage as a control voltage for controlling the output voltage when the toner density is detected to be the reference output voltage The control voltage is stored, the image forming apparatus is characterized in that so as to update the control voltage the adjustment. In a toner concentration sensor for detecting the toner concentration of a two-component developer in a developer container that contains a two-component developer composed of toner and a carrier,
A toner density sensor comprising storage means for storing characteristic information of the toner density sensor. The toner concentration sensor according to claim 2.
The characteristic information is adjusted to the reference voltage by measuring the reference output voltage and a reference device having the same characteristics as a developer having a predetermined toner density by using the toner density sensor at the time of manufacture. And a control voltage when the toner density sensor. The toner concentration sensor according to claim 2 or 3,
The toner density sensor, wherein the characteristic information is sensitivity information of the toner density sensor calculated based on a value obtained by measuring a reference device serving as a measurement reference using the toner density sensor at the time of manufacture. The toner concentration sensor according to claim 2, 3 or 4,
The driving power source for driving the toner density sensor is the same as the driving power source for driving the storage unit, and a decompression unit for reducing the voltage from the driving power source is provided, and the voltage from the driving power source supplied to the storage unit Is supplied through the pressure reducing means. The toner density sensor according to claim 2, 3, 4 or 5,
The control voltage signal line for controlling the output voltage of the toner density sensor to be an output voltage stored in advance is the same as the signal line for controlling writing / reading of the recording means. Toner density sensor. The toner concentration sensor according to claim 6.
The control voltage for controlling the output voltage of the toner density sensor to be an output voltage stored in advance is generated using a PWM signal that switches the voltage to HI / LOW at a predetermined interval, and the recording means The toner density sensor is characterized in that the signal for controlling the writing / reading is a signal whose voltage takes only one of HI and LOW during the writing / reading by the recording means. An image carrier that carries an electrostatic latent image, a developer container that contains a two-component developer composed of a carrier and a toner, a developer carrier that carries a developer in the developer container, and the development An image forming apparatus including a process cartridge that is integrated with a developing device including a toner concentration detecting device that detects the toner concentration of the two-component developer in the agent container, and is removable from the image forming apparatus main body.
The process cartridge includes a storage unit, a communication connection unit for connecting the communication unit of the storage unit and the communication unit of the image forming apparatus, and an electric circuit of the toner density sensor to an electric circuit on the image forming apparatus main body side. An image forming apparatus comprising: a circuit connection unit for connection; and the communication connection unit provided in the circuit connection unit. The image forming apparatus according to claim 8.
The image forming apparatus, wherein the storage means stores manufacturing information relating to the process cartridge. The image forming apparatus according to claim 7, 8 or 9.
An image forming apparatus, wherein the storage means stores a use history of the process cartridge. The image forming apparatus according to claim 7, 8, 9 or 10.
An image forming apparatus, wherein the storage means stores a use history of a component mounted on the process cartridge. The image forming apparatus according to claim 1, 8, 9, 10 or 11.
An image forming apparatus, wherein the toner density sensor is the toner density sensor according to claim 2, 3, 4, 5, 6 or 7. The image forming apparatus according to claim 12.
An image forming apparatus comprising request means for requesting writing / reading to the storage means in the image forming apparatus, and control of the request means is stopped when toner density detection is performed.

Images