JP2006171053A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a trailing image produced by variations in components, environmental variations and differences in recording materials. <P>SOLUTION: The image forming device comprises a bias-applying means for applying a bias to a fixing film, a current detecting means for detecting the current value flowing in the fixing film, an impedance-detecting means for detecting the impedance of the fixing film based on a value detected by the current detecting means, and a bias-setting means for setting the bias to be applied to the fixing film, based on the value detected by the impedance-detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heating device that fixes a toner image on a recording material, and an image forming apparatus including the same.

  Of the image forming apparatuses, a printer will be described as an example.

  A conventional printer has a mechanism as shown in FIG. In FIG. 10, 101 is a photosensitive drum which is an electrostatic carrier, 102 is a semiconductor laser as a light source, 103 is a rotating polygon mirror which is rotated by a scanner motor 104, and 105 is emitted from the semiconductor laser 102, on the photosensitive drum 101. Is a laser beam.

  Reference numeral 106 denotes a charging roller for uniformly charging the surface of the photosensitive drum 101, and reference numeral 107 denotes a developing machine for developing the electrostatic latent image formed on the photosensitive drum 101 with toner. Reference numeral 108 denotes a transfer roller for transferring the toner image developed by the developing device 107 to a predetermined recording paper, and 109 denotes a fixing roller for fusing the toner transferred to the recording paper by heat.

  110 is a cassette feed roller that feeds paper from a cassette having a function of identifying the size of the recording paper by one rotation, and sends it to the conveyance path, and 111 is a manual paper feed that does not have a function of identifying the size of the recording paper This is a manual feed roller that feeds a sheet from the opening to the conveyance path. 112 is an optional cassette paper feed roller that is detachable and has a function of identifying the size of the recording paper, and feeds the paper from the cassette to the transport path. This is an envelope feeder feeding roller to be fed. Reference numerals 114 and 115 denote transport rollers for transporting paper fed from the cassette.

  116 is a pre-feed sensor for detecting the leading and trailing edges of sheets fed from other than the envelope feeder, 117 is a pre-transfer roller that feeds the conveyed sheets to the photosensitive drum 101, and 118 is a sheet that is fed. However, this is a top sensor for synchronizing the writing (recording / printing) of the image on the photosensitive drum 101 and the conveyance of the paper and measuring the length of the fed paper in the conveyance direction. Reference numeral 119 denotes a paper discharge sensor for detecting the presence or absence of paper after fixing, and 120 denotes a discharge roller for discharging the paper after fixing to the outside of the apparatus.

  121 is a flapper for switching the transport destination of the printed paper (external discharge or removable duplex unit), 122 is a transport roller for transporting the paper transported to the duplex unit to the reversing unit, and 123 is the reversing unit. A reversing sensor 124 for detecting the leading edge / rear edge of the conveyed paper, a reversing roller 125 for reversing the paper by sequentially operating normal rotation / reverse rotation, and conveying the paper to the refeeding unit, 125 Re-feed sensor 126 detects the presence or absence of paper in the re-feed unit, and a re-feed roller for sending the paper in the re-feed unit back to the transport path.

  FIG. 11 shows a block diagram of a circuit configuration of a control system for controlling such a mechanism unit.

  In FIG. 11, reference numeral 201 denotes a printer controller for developing image code data sent from an external device such as a host computer (not shown) into bit data necessary for printing by the printer, reading internal printer information, and displaying it. .

  A printer engine control unit 202 controls the operation of each unit of the printer engine in accordance with an instruction from the printer controller 201 and notifies the printer controller 201 of printer internal information. A sheet conveyance control unit 203 drives / stops a motor, a roller, and the like for conveying a recording sheet in accordance with an instruction from the printer engine control unit 202, and 204 controls a high-voltage output control in each process such as charging, development, and transfer. This is a high pressure control unit that is performed in accordance with an instruction from the engine control unit 202.

  An optical system control unit 205 controls driving / stopping of the scanner motor 104 and lighting of the laser beam in accordance with instructions from the engine control unit 202. Reference numeral 207 denotes a fixing temperature control unit for adjusting the temperature of the fixing device to a temperature designated by the printer engine control unit 202.

  A detachable option cassette control unit 208 drives / stops the drive system according to an instruction from the printer engine control 202, and notifies the printer engine control unit 202 of the paper presence / absence status and paper size information.

  Reference numeral 209 denotes a detachable duplex unit control unit that performs a paper reversal and refeed operation in accordance with an instruction from the printer engine control unit 202 and simultaneously notifies the engine control unit 202 of the operation state.

  Reference numeral 210 denotes a detachable envelope feeder control unit that drives / stops the drive system according to an instruction from the printer engine control unit 202 and notifies the printer engine control unit 202 of the paper presence / absence state.

  FIG. 12 shows a schematic configuration of the fixing bias application configuration.

  Reference numeral 401 denotes a heat fixing device, which includes a fixing film 402, a ceramic heater 403 as a heating body, and a pressure roller 404. Reference numeral 406 denotes a fixing bias device, and a circuit is formed inside the electrical device.

This fixing bias device is connected to a fixing film when a ceramic heater is used as a heating element, and applies a negative voltage when negative polarity toner is used. By applying this bias, the toner is attracted to the paper and the scattering of the toner is suppressed.
Japanese Patent Laid-Open No. 2003-330297

  Conventionally, the fixing bias has been implemented in a configuration in which a constant negative voltage is applied and only in a fixing film. With this configuration, with the increase in printing speed, it is impossible to cover all the conditions such as printing means, environmental temperature, and image density setting, and it becomes impossible to suppress toner scattering.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that improves a tail image caused by component variations, environmental variations, and recording materials.

  An image forming apparatus including an image forming unit that forms a toner image on a recording material and a fixing device that heats and fixes the toner image to the recording material can solve the above-described problems by including the following configuration.

  (1) In the fixing device, a ceramic heater is used as a heating body, a pressure member disposed opposite to the ceramic heater, and a fixing film sandwiched and conveyed between the ceramic heater and the pressure member A bias applying means for applying a bias to the fixing film before sandwiching and conveying the recording material between the pressure member and the fixing film, and a current detection for detecting a current value flowing through the fixing film when the bias is applied. Means for detecting the impedance of the fixing film based on the detection value of the current detecting means, and detecting the impedance detecting means when the recording material is nipped and conveyed between the pressure member and the fixing film. An image forming apparatus comprising bias setting means for setting a bias to be applied to the fixing film based on the value Subjected to.

  (2) The bias applying means sets a bias so that the detected value of the current detecting means becomes constant, and detects the impedance of the fixing film based on the set value. The described image forming apparatus is provided.

  (3) The image forming apparatus according to (1), wherein a constant voltage is applied by the bias setting unit, and an impedance of the fixing film is detected by a detection value of the current detection unit. .

  (4) The image forming apparatus according to (1), wherein the bias applying unit sets a bias to be applied according to an ambient temperature.

  (5) The image forming apparatus according to (1), wherein the bias application unit sets a bias to be applied according to the recording material.

  As described above, in an image forming apparatus including an image forming unit that forms a toner image on a recording material and a fixing device that heats and fixes the toner image to the recording material, the present invention of claim 1 Bias applying means for applying a bias to the fixing film before sandwiching and conveying the recording material between the pressure member and the fixing film, current detecting means for detecting a current value flowing through the fixing film when the bias is applied, Based on the detection value of the current detection means, impedance detection means for detecting the impedance of the fixing film, and when the recording material is nipped and conveyed between the pressure member and the fixing film, the detection value of the impedance detection means is used. And an image forming apparatus having bias setting means for setting a bias to be applied to the fixing film. It is possible to realize a high-quality image with less scattering fine.

  The present invention of claim 2 is characterized in that the bias application means sets a bias so that the detection value of the current detection means becomes constant, and detects the impedance of the fixing film based on the set value. By providing the image forming apparatus according to claim 1, it is possible to realize a high-quality image with less toner scattering.

  3. The image forming apparatus according to claim 1, wherein the bias setting unit applies a constant voltage and the impedance of the fixing film is detected by a detection value of the current detection unit. By providing the apparatus, it is possible to realize a high-quality image with less toner scattering.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus according to the first aspect, wherein the bias applying unit sets a bias to be applied according to the ambient temperature, thereby affecting the ambient temperature. It is possible to realize a high-quality image with little toner scattering.

  According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the bias applying unit sets a bias to be applied according to the recording material. It is possible to realize a high-quality image with little toner scattering that is not affected by the type.

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

  In this embodiment, an image forming apparatus including an image forming unit that forms a toner image on a recording material and a fixing device that heats and fixes the toner image to the recording material has a fixing film in the fixing device. A fixed high voltage bias that is not influenced by the impedance of the fixing film is applied to the fixing film to prevent the toner formed on the conveying member from scattering.

  FIG. 1 is a conceptual diagram of the fixing bias effect.

  Reference numeral 501 denotes a fixing film, 502 a fixing bias circuit, 503 a static elimination needle, 504 a recording material, 505 a pressure roller, and 506 a current limiting resistor.

  Toner scattering is caused by the influence of water vapor generated during fixing. In order to suppress this, since the toner is negatively charged, the fixing film has a negative potential. As a result, the toner is attracted to the recording material, and the scattering of the toner due to water vapor is suppressed. In order to prevent stable toner scattering, it is necessary to set the potential on the fixing film to a constant voltage that is not affected by the impedance of the fixing film.

  In the configuration of FIG. 1, it is necessary to connect 506 current limiting resistors in consideration of safety to the human body. For this reason, the voltage of the resistance ratio between the impedance of the fixing film and the resistance ratio of the 506 current limiting resistor becomes the potential of the fixing film. That is, the negative voltage on the fixing film varies depending on the impedance of the fixing film. The present embodiment aims to suppress variations in negative voltage due to differences in the impedance of the fixing film.

  FIG. 2 shows an example of the fixing bias connection method in the first embodiment of the present invention.

  In FIG. 2, reference numeral 601 denotes a fixing device, which includes a fixing film 602, a ceramic heater as a heating body 603, a pressure roller as a pressure member 604, and a static elimination needle 605. A fixing film bias circuit 606 is connected to the fixing film 602, and a negative high voltage bias is applied.

  FIG. 3 shows an example of the configuration of the fixing bias circuit in the first embodiment of the present invention.

  In FIG. 3, reference numeral 701 denotes a fixing film bias circuit unit, which includes an amplification circuit unit 702, a smoothing circuit unit 703, a drive circuit unit 704, and a feedback circuit unit 705.

  When outputting the fixing film bias, the 706 PWM signal is input to the 703 smoothing circuit unit, and is converted into a voltage by a transistor 707. Thereafter, the voltage Vch is charged to the capacitor 710 through the filter circuit 708 and the buffer circuit 709. This voltage Vch is input to the transformer 711 of the 702 amplifier circuit unit. The 711 transformer operates when a 712 drive signal is input, and amplifies the voltage V1. The amplified voltage is smoothed by a high-voltage filter circuit 713, smoothed, and then applied to the fixing film. Reference numeral 705 denotes a detection circuit that detects a current flowing through the fixing film, and detects a current value flowing through the current route of FIG.

  A flowchart of this embodiment is shown in FIG.

  First, after the power is turned on (S601), a constant PWM value α is applied in the pre-multi revolution (S602, S603). A high voltage bias V1 based on the PWM value α is applied to the fixing film. At that time, the same current I1 flowing through the fixing film flows through the resistor R1 of the 705 feedback circuit unit, is detected by a voltage drop ΔV (= I1 × R1), and is fed back to the control circuit unit 715 (S605).

  Since the high voltage bias is output according to the PWM value α, the control circuit unit can grasp the output value of the high voltage bias by providing a conversion formula or table in the control circuit unit. Further, the current flowing through the fixing film can be calculated by calculation of the control circuit unit from the resistance R1 and the voltage drop ΔV. Therefore, the impedance of the fixing film can be calculated by the control circuit unit from the output value and current value of the high-voltage bias (S606).

  Next, in order to make the voltage drop in the fixing film layer constant, a PWM value β suitable for the calculated impedance value is calculated by the control circuit unit (S607). When printing is started, the calculated PWM value β is set (S609), and a high voltage bias corresponding to the impedance of the fixing film is applied (S610).

  By performing such control, it is possible to apply a constant voltage that does not depend on the impedance of the fixing film to the fixing film, and it is possible to form a high-quality image without toner scattering.

  In this embodiment, as in the first embodiment, an image forming apparatus including an image forming unit that forms a toner image on a recording material and a fixing device that heats and fixes the toner image to the recording material. A fixing film is included therein, and a constant high-voltage bias that is not affected by the impedance of the fixing film is applied to the fixing film to prevent toner formed on the conveying member from scattering.

  Since the conceptual diagram of the fixing bias effect, the fixing bias connection method, and the fixing bias circuit configuration are the same as those in the first embodiment, description thereof will be omitted.

  A flowchart of the present embodiment is shown in FIG. First, after the power is turned on (S701), the PWM value is gradually increased by pre-multiple rotation (S703). As a result, the current I1 flowing through the fixing film gradually increases (S704). The current I1 flows through the resistor R1 of the 705 feedback circuit unit, is detected by the voltage drop Vt (= I1 × R1), and is fed back to the control circuit unit 715 (S705).

  When the voltage fed back in the control circuit unit reaches Vt, the PWM value stops increasing and the PWM value γ is recorded (S706). Since the high voltage bias is output according to the PWM value γ, the control circuit unit can grasp the output value of the high voltage bias by providing a conversion formula or table in the control circuit unit.

  Further, the current flowing through the fixing film can be calculated by calculation of the control circuit unit from the resistance R1 and the voltage drop Vt. Therefore, the impedance of the fixing film can be calculated by the control circuit unit from the output value and current value of the high-voltage bias (S707).

  Next, in order to make the voltage drop in the fixing film layer constant, a PWM value η suitable for the calculated impedance value is calculated by the control circuit unit (S708). When printing is started, the calculated PWM value η is set (S710), and a high voltage bias corresponding to the impedance of the fixing film is applied (S711).

  By performing such control, it is possible to apply a constant voltage that does not depend on the impedance of the fixing film to the fixing film, and it is possible to form a high-quality image without toner scattering.

  In this embodiment, as in the first embodiment, an image forming apparatus including an image forming unit that forms a toner image on a recording material and a fixing device that heats and fixes the toner image to the recording material. A fixed high voltage bias that is not affected by the impedance of the fixing film is applied to the fixing film, and the set value of the high voltage bias to be applied is changed according to the ambient temperature. It is characterized in that it is possible to prevent toner scattering without being affected by humidity.

  Since the conceptual diagram of the fixing bias effect, the fixing bias connection method, and the fixing bias circuit configuration are the same as those in the first embodiment, description thereof will be omitted. In the present embodiment, in the fixing bias circuit configuration, a temperature / humidity sensor is connected to detect the ambient temperature and humidity (FIG. 6).

  As described in the conceptual diagram of the fixing bias effect in the first exemplary embodiment, toner scattering is caused by the influence of water vapor generated during fixing. Therefore, it is affected by ambient temperature / humidity. When the temperature / humidity is high, since the moisture absorbed in the recording material is high, the high-voltage bias needs to be set higher. On the other hand, when the temperature / humidity is low, the moisture absorbed in the recording material is low, so the high-voltage bias needs to be set low. As described above, since a high-voltage bias corresponding to the ambient temperature / humidity state can be applied, it is possible to suppress toner scattering due to water vapor.

  A flowchart of this embodiment is shown in FIG.

  First, after the power is turned on (S801), a constant PWM value α is applied in the pre-multiple rotation (S802, S803). A high voltage bias V1 based on the PWM value α is applied to the fixing film. At that time, the same current I1 flowing through the fixing film flows through the resistor R1 of the 705 feedback circuit unit, is detected by the voltage drop ΔV (= I1 × R1), and is fed back to the control circuit unit 715 (S805). Since the high voltage bias is output according to the PWM value α, the control circuit unit can grasp the output value of the high voltage bias by providing a conversion formula or table in the control circuit unit.

  Further, the current flowing through the fixing film can be calculated by calculation of the control circuit unit from the resistance R1 and the voltage drop ΔV. Therefore, the impedance of the fixing film can be calculated by the control circuit unit from the output value and current value of the high-voltage bias (S806). In addition, the ambient temperature and humidity are detected from the detection values obtained from the temperature sensor and humidity sensor provided in the main body (S807). Then, a PWM value β taking into account the ambient temperature / humidity and the impedance of the fixing film is calculated from a table provided in the control circuit unit (S808). When printing is started, the calculated PWM value β is set (S810), and a high voltage bias according to the ambient temperature / humidity and the impedance of the fixing film is applied (S811).

  By performing such control, it becomes possible to apply a constant voltage that does not depend on the ambient temperature / humidity and the impedance of the fixing film to the fixing film, and a high-quality image without toner scattering can be formed. It becomes possible.

  In this embodiment, as in the first embodiment, an image forming apparatus including an image forming unit that forms a toner image on a recording material and a fixing device that heats and fixes the toner image to the recording material. A fixed high voltage bias that is not affected by the impedance of the fixing film is applied to the fixing film, and the set value of the high voltage bias to be applied is changed according to the type of recording material. It is characterized in that it is possible to prevent toner scattering without being affected by the type of material.

  Since the conceptual diagram of the fixing bias effect, the fixing bias connection method, and the fixing bias circuit configuration are the same as those in the first embodiment, description thereof will be omitted. In this embodiment, in the fixing bias circuit configuration, a recording material detection sensor is connected to detect the type of the recording material (FIG. 8).

  As described in the conceptual diagram of the fixing bias effect in the first exemplary embodiment, toner scattering is caused by the influence of water vapor generated during fixing. Therefore, the recording material is affected by the difference in water absorption. Further, the adhesion force of the toner differs in the surface property of the recording material. For this reason, in the case of a recording material having a high water absorption amount and a low toner adhesion, it is necessary to set the high-voltage bias high.

  On the contrary, in the case of a recording material having a high water absorption amount and a low toner adhesion, it is necessary to set the high-pressure bias low. As described above, since a high voltage bias according to the type of the recording material can be applied, it is possible to suppress toner scattering due to water vapor.

  A flowchart of the present embodiment is shown in FIG.

  First, after the power is turned on (S901), a constant PWM value α is applied in the pre-multiple rotation (S902, S903). A high voltage bias V1 based on the PWM value α is applied to the fixing film. At that time, the same current I1 flowing through the fixing film flows through the resistor R1 of the 705 feedback circuit unit, is detected by a voltage drop ΔV (= I1 × R1), and is fed back to the control circuit unit 715 (S905). Since the high voltage bias is output according to the PWM value α, the control circuit unit can grasp the output value of the high voltage bias by providing a conversion formula or table in the control circuit unit.

  Further, the current flowing through the fixing film can be calculated by calculation of the control circuit unit from the resistance R1 and the voltage drop ΔV. Therefore, the impedance of the fixing film can be calculated by the control circuit unit from the output value and current value of the high-voltage bias (S906).

  Also, the type of the recording material is detected from the detection value obtained from the recording material detection sensor provided in the main body (S907). Then, a PWM value β in consideration of the type of the recording material and the impedance of the fixing film is calculated from a table provided in the control circuit unit (S908). When printing is started, the calculated PWM value β is set (S910), and a high voltage bias according to the type of recording material and the impedance of the fixing film is applied (S911).

  By performing such control, it becomes possible to apply a constant voltage to the fixing film regardless of the type of recording material and the impedance of the fixing film, and a high-quality image without toner scattering can be formed. It becomes possible.

Conceptual diagram of the fixing bias effect of Example 1 of the present invention. Schematic diagram of fixing bias connection method of embodiment 1 of the present invention Fixing Bias Circuit Configuration of Embodiment 1 of the Invention Flowchart schematic diagram of Embodiment 1 of the present invention Flowchart schematic diagram of Embodiment 2 of the present invention Fixing Bias Circuit Configuration of Embodiment 3 of the Invention Flowchart schematic diagram of Embodiment 3 of the present invention Fixing Bias Circuit Configuration of Embodiment 4 of the Invention Flowchart schematic diagram of Embodiment 4 of the present invention Schematic of image recording apparatus main body configuration in the present invention Schematic diagram of an image recording apparatus controller in the present invention Schematic diagram of conventional fixing bias connection method

Explanation of symbols

501 Fixing film 502 Fixing bias circuit 503 Static elimination needle 504 Recording material 505 Pressure roller 506 Current limiting resistance

Claims (5)

An image forming apparatus comprising: an image forming unit that forms a toner image on a recording material; and a fixing device that heats and fixes the toner image to the recording material.
While using a ceramic heater as a heating element in the fixing device,
A pressure member disposed opposite to the ceramic heater;
A fixing film that is nipped and conveyed between the ceramic heater and the pressure member,
Before nipping and conveying the recording material between the pressure member and the fixing film,
Bias applying means for applying a bias to the fixing film;
Current detection means for detecting a current value flowing through the fixing film when the bias is applied;
Impedance detection means for detecting the impedance of the fixing film based on the detection value of the current detection means,
When the recording material is nipped and conveyed between the pressure member and the fixing film,
Bias setting means for setting a bias to be applied to the fixing film based on a detection value of the impedance detection means;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein the bias is set by the bias applying unit so that the detection value of the current detection unit becomes constant, and the impedance of the fixing film is detected by the set value. apparatus.   2. The image forming apparatus according to claim 1, wherein a constant voltage is applied by the bias setting unit, and an impedance of the fixing film is detected by a detection value of the current detection unit. The image forming apparatus according to claim 1, wherein the bias applying unit sets a bias to be applied according to an ambient temperature. 2. The image forming apparatus according to claim 1, wherein the bias applying unit sets a bias to be applied according to the recording material.

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