KR20080024698A - Image forming device and method of the driving - Google Patents

Abstract

An image-forming apparatus and a method for driving the same are provided to control a fixing device stably, by shutting off the supply of an AC power to the fixing device when a controller of the fixing device is broken down or damaged. A power supply unit(120) supplies AC power to a fixing device. A temperature controller(130) controls the timing of the supply of the AC power in response to a first control signal. A switching unit(150) shuts off the supply of the AC power in response to a second control signal when a temperature of the fixing device is above a predetermined overheat temperature by the AC power. A phase-sensing unit(140) senses the phase change of the AC power to output a phase sense signal. A controller(162) compares the output frequency of the phase sense signal with an output expectation value of the phase sense signal, and outputs one of the first control signal and the second control signal according to the compared result.

Description

Image forming apparatus and driving method thereof IMAGE FORMING DEVICE AND METHOD OF THE DRIVING

1 is a block diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention.

2 is a block diagram specifically illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a circuit diagram specifically illustrating a part of the image forming apparatus shown in FIG. 2.

FIG. 4 is a waveform diagram illustrating the image forming apparatus shown in FIG. 2.

* Description of the symbols for the main parts of the drawings *

100: image forming apparatus 110: fuser

112: heating lamp 114: overheat protection

116: temperature sensing unit 120: power supply unit

130: temperature control unit 140: phase detection unit

150: switching unit 160: control unit

162: controller 164: H / W protection unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus and a driving method thereof capable of stably controlling the temperature of a fixing unit even in a defective or abnormal operation of an internal element.

The image forming apparatus means an apparatus which prints an image corresponding to the input image data onto a recording medium such as printing paper. Examples of such an image forming apparatus include a printer, a copier, a facsimile, and a multifunction printer incorporating these functions into one.

In general, the image forming apparatus needs a heat generating device for allowing a normal printing operation and a device for maintaining the heat generating device at a constant temperature. In particular, in the case of a fuser for fusing the formed toner image onto the printing paper using heat and pressure, the fixing lamp of the heating lamp inside the fixing unit, which is a heating device, is maintained so that its surface is maintained at a target temperature suitable for fixing in order to fix the toner image on the paper. There is a need for a fuser controller for controlling temperature.

The fuser control device senses the temperature of the fuser using a voltage value corresponding to the temperature of the fuser provided through a temperature sensor such as a thermistor attached to the fuser, thereby generating heat and Control to maintain.

Specifically, when the thermistor is provided with a resistance element having a negative characteristic according to a temperature change, for example, the voltage value output from the thermistor is output as a voltage value of a potential level that decreases in proportion to the rise of the surface temperature of the fixing unit. It is output at the voltage value of the potential level which increases in proportion to the fall of the surface temperature of the fixing unit.

The voltage value output from the thermistor is applied to the controller of the image forming apparatus, and the controller provides AC power applied from the outside to the heating lamp based on the applied voltage value through pulse width modulation (PWM). The surface temperature of the fixing unit is controlled in such a manner as to control the timing of the fixing.

In the case of a fuser control device using such a method, the photo coupler activated under the control of the controller and the photo coupler driven to control the timing at which the AC power is applied to the heating lamp are activated in conjunction with the trigger. Triac is provided.

In addition, when the controller malfunctions due to noise or the like, the heating lamp may be heated such that the surface temperature of the fixing unit is formed at a temperature exceeding a preset overheating temperature. In this case, since the controller cannot control the timing at which the AC power is applied to the heating lamp, the controller further includes hardware protection means for blocking the heating lamp from being heated.

Generally, such hardware protection means includes a comparator for comparing a voltage value output from the thermistor with a voltage value corresponding to a preset overheating temperature, and a switching element for blocking AC power from being applied to the heating lamp according to the output signal of the comparator. Include.

Also, in general, the image forming apparatus further includes a temperature control device such as a thermostat to prevent fire and damage to the fuser due to deterioration of the fuser as part of the safety device.

In the case of a fuser control device having such a configuration and control method, the application of AC power is controlled by turning on / off the photo coupler or triac under the control of the controller, or the application of AC power is blocked by the hardware protection means. Control the lamp temperature so that it does not exceed the preset overheat temperature.

However, when the photo coupler or the triac is damaged due to a defective element or a transient current during driving, the temperature of the fixing unit must be controlled by hardware protection means even if the controller operates normally.

However, since the hardware protection means turns on / off the switching element in hardware depending on the temperature of the fuser as described above, when the temperature of the fuser becomes lower than the overheating temperature, AC power is supplied to the heating lamp again.

The operation of the hardware protection means is carried out continuously in accordance with the surface temperature change of the fixing unit, the internal latent heat of the fixing unit is raised by the operation of the continuous hardware protection means.

Therefore, in the case of a general image forming apparatus, a temperature control device such as a thermostat is increased by raising an internal latent heat of the fuser when an internal element of the fuser controller, for example, a photo coupler or a triac is defective or breaks during operation. There is a problem to break, and there is a problem of shortening the life of the image forming apparatus by deteriorating the internal accessories such as the fixing unit, for example, bushing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus capable of stably controlling the temperature of the fixing unit even when a component defect or abnormal operation of an internal element of the fixing unit control device is performed. .

Another object of the present invention is to provide a method of driving the image forming apparatus.

In order to achieve the above object of the present invention, the image forming apparatus having a fuser according to an embodiment of the present invention, the power supply for providing AC power, the first control the timing that the AC power is applied to the fuser A temperature controller for controlling in response to a signal, a switching unit for interrupting the application of the AC power in response to a second control signal when the temperature of the fixing unit exceeds a preset overheating temperature by the AC power; A phase detection unit for detecting a phase change and outputting a phase detection signal, and comparing the output frequency of the phase detection signal with an output expected value of a preset phase detection signal, and comparing one of the first and second control signals according to the comparison result. It includes a control unit for output.

Here, the control unit may output the first control signal if it is the same, and output the second control signal if different, as a result of comparing the output expected value with the number of outputs of the phase detection signal output for a predetermined time.

The controller may compare the output count of the phase detection signal output from the phase detector with the expected output value before the temperature controller and the switching unit are activated.

The phase detection unit may be connected between the temperature control unit and the switching unit, and output the phase detection signal in a section between zero-crossing time points of the AC power.

In order to achieve another object of the present invention, a method of driving an image forming apparatus having a fixing apparatus according to an embodiment of the present invention comprises the steps of: outputting a phase detection signal by detecting a phase change of an AC power applied from the outside; Comparing the output expected value of the preset phase detection signal with the output frequency of the output phase detection signal according to the driving state of the fuser; and applying the AC power so that the fuser has at least one surface temperature according to the comparison result. And outputting one of a first control signal for controlling the second control signal and a second control signal for blocking the application of the AC power to lower the surface temperature of the fixing unit.

Here, the first control signal may be output in the same case as a result of comparing the output expected value with the output frequency of the phase detection signal output for a predetermined time, and the second control signal may be output for the predetermined time with the output expected value. When the output frequency of the output phase detection signal is compared, it may be output when it is different.

According to such an image forming apparatus, when an internal element of the fixing unit control device is defective or damaged and is abnormally operated during driving, the image forming apparatus detects this and blocks AC power from being applied to the fixing unit, thereby enabling stable temperature control of the fixing unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention. In particular, FIG. 1 is shown centering on the fixing unit and the fixing unit temperature control device among the components of the image forming apparatus.

Referring to FIG. 1, the image forming apparatus 100 according to an exemplary embodiment of the present invention may include a fixing unit 110, a power supply unit 120, a temperature control unit 130, a phase detection unit 140, a switching unit 150, and the like. The controller 160 is included.

Specifically, the fixing unit 110 includes a heating lamp. The heating lamp of the fixing unit 150 may be formed of a direct current heating lamp. The heating lamp is heated by receiving an AC power whose input timing is controlled according to the driving of the temperature controller 130 and the switching unit 150 so that the surface temperature of the fixing unit is formed at a predetermined surface temperature for each driving mode of the fixing unit. .

In addition, the fixing unit 110 measures the surface temperature of the formed fixing unit and outputs a temperature sensing signal for controlling heating of the heating lamp of the fixing unit 110 to the control unit 160.

The power supply unit 120 is configured as a switching mode power supply (SMPS), for example, to change the potential level of an AC power applied from the outside to change the potential for driving each part of the image forming apparatus 100. Provide level AC power.

In this case, the power supply unit 120 may further include a power converter to rectify and smooth the AC power applied from the outside to provide the DC power to the image forming apparatus 100.

The temperature controller 130 controls the timing at which the AC power output from the power supply unit 120 is supplied to the fixing unit 110 in response to the control signal output from the controller 160. That is, the temperature controller 130 controls the application timing of AC power for heating the heating lamp of the fuser 110 so that the surface temperature of the fuser 110 is formed in each driving mode of the fuser 110. Here, each driving mode of the fixing unit 110 is, for example, a setup mode for raising the surface temperature of the initial fixing unit, and a preset fixing temperature for fixing the toner on the paper in the printing operation of the image forming apparatus 100. It may include a print mode in which the surface temperature of the fuser is formed and a standby mode for forming and maintaining at a surface temperature lower than the surface temperature in the print mode to improve the printing speed.

In addition, the temperature controller 130 may cut off the AC power applied to the fuser 110 such that the surface temperature of the fuser 110 is not formed at a temperature exceeding a preset overheating temperature under the control of the controller 160.

The phase detector 140 detects a phase change of the AC power output from the power supply unit 120 and provided to the fixing unit 110 under the control of the temperature controller 130. The phase detector 140 detects a zero-crossing point in time of the AC power applied to the fixing unit 110, and outputs a phase detection signal during a section between the zero-crossing point in time.

The output phase detection signal is applied to the controller 160 and used as a synchronization signal for outputting a control signal for controlling the temperature controller 130. In particular, the phase detection signal in the present invention is used as a detection signal for detecting the presence or absence of abnormality of the internal element included in the temperature control unit 130. This will be described in detail with reference to FIGS. 2 to 4.

Under the control of the control unit 160, the switching unit 150, when the surface temperature of the fixing unit 110 is formed to a temperature exceeding a preset overheating temperature AC is applied to the temperature control unit 130 itself from the power supply unit 120 Shut off the power.

The control unit 160 outputs a first control signal for controlling the temperature control unit 130 using the phase detection signal output from the phase detection unit 140 as a synchronization signal, and the surface temperature of the fixing unit 110 has a preset overheat temperature. When formed at a temperature exceeding, the second control signal for controlling the switching unit 150 is output.

In particular, the control unit 160 according to the present invention compares the output expected value of the preset phase detection signal based on the number of times the output of the phase detection signal is applied and the first control signal, and whether the temperature control unit 130 is abnormal according to the comparison result. If the temperature controller 130 operates abnormally, and outputs the second control signal to deactivate the switching unit.

The image forming apparatus will be described in more detail as follows.

FIG. 2 is a block diagram specifically illustrating an image forming apparatus according to an embodiment of the present invention, FIG. 3 is a circuit diagram specifically showing a part of the image forming apparatus illustrated in FIG. 2, and FIG. 4 is illustrated in FIG. 2. It is a waveform diagram shown for explaining the illustrated image forming apparatus.

1 to 4, the image forming apparatus 100 according to an embodiment of the present invention includes a fixing unit 110 including a heating lamp 112, an overheat prevention unit 114, and a temperature sensing unit 116. The control unit 160 includes a power supply unit 120, a temperature control unit 130, a phase detection unit 140, a switching unit 150, and a controller 162 and an H / W protection unit 164.

Here, the heating lamp 112 and the power supply unit 120 will be described in detail with reference to FIG. 1, and detailed description thereof will be omitted.

The overheat protection unit 114 is formed as a thermostat such as a thermostat to prevent fire and damage to the fuser due to deterioration of the fuser as part of the safety device, and when the heating lamp is overheated, the power supply unit ( AC power supplied from 120 is cut off by mechanical operation.

The temperature sensing unit 116 may include a temperature sensor such as a thermistor. In the present invention, the temperature sensing unit 116 constitutes an example of a thermistor having a negative characteristic, that is, a resistance value decreases as the temperature rises, thereby outputting a thermistor voltage Vth of high potential. In this case, as the surface temperature of the fixing unit 110 is formed at a high temperature, the potential level of the thermistor voltage Vth decreases, and as the surface temperature of the fixing unit 110 is formed at a low temperature, the potential level of the thermistor voltage Vth increases. Here, the temperature sensing signal used in the description of FIG. 1 means the thermistor voltage Vth.

The thermistor voltage Vth output from the temperature sensing unit 116 is provided to the controller 162 and the hardware protection unit 164 of the controller 160.

The controller 160 outputs first and second control signals CS1 and CS2 for controlling the temperature controller 130 and the switching unit 150 based on the thermistor voltage Vth output from the temperature sensing unit 116. do.

For example, the controller 162 controls the temperature controller 130 using a pulse width control method (PWM method) or a phase control method according to the thermistor voltage Vth output from the temperature sensing unit 116. 1 Output a control signal CS1.

When using the PWM method, the first control signal CS1 is output as a pulse signal having a predetermined duty ratio. According to the duty ratio of the first control signal CS1, the time for which the AC power applied from the power supply unit 120 is applied to the heating lamp 112 is formed differently. As the duty ratio approaches 100%, the heating lamp 11 In this case, the surface temperature of the fuser is increased by increasing the time that the AC power is applied, and vice versa, so that the surface temperature of the fuser can be controlled according to each driving mode.

In addition, the controller 162 may switch over the overheat temperature set by the thermistor voltage Vth output from the temperature sensing unit 116 or exceed the heat resistance temperature by over shooting in the setup mode. Outputs a second control signal CS2 to turn off. In this case, unlike the first control signal CS1, the second control signal CS2 may be output as a switching on / off signal having a logic value of 0 or 1, for example, which turns on / off the switching unit 150.

The H / W protection unit 164 blocks the driving of the temperature controller 130 in preference to the control of the controller 162 when the thermistor voltage Vth output from the temperature sensing unit 116 is greater than a preset potential level. The first control signal CS1 is output.

When the switching unit 150 is in the on state, the temperature controller 130 provides the heating lamp 112 with AC power output from the power supply unit 120 in response to the first control signal CS1.

For example, as illustrated in FIG. 3, the temperature controller 130 is coupled to the light emitting device D1 and the light emitting device D1 activated by the first control signal CS1 applied from the controller 160. Is generated when the internal pressure of the triac (TA) and the triac (TA), which is activated in conjunction with the activation of the phototriac (PTA) and the phototriac (PTA), is suddenly changed from 0 V to the turn-on voltage. Internal elements such as a first resistor R1, a first capacitor C1, and a second resistor R2 for reducing the amount of current applied to the port triac PTA are formed to prevent noise such as sparks. can do.

Therefore, the AC power source AC_IN applied from the power supply unit 120 interworks with the activation of the photo couplers PTA and D1 and the photo couplers PTA and D1 that are activated based on the duty ratio of the first control signal CS1. It is applied to the fixing unit 110 via the triac (TA) to be driven.

The phase detection unit 140 is connected to the first node N1 between the temperature control unit 130 and the switching unit 150 and at a zero-crossing time point of the AC power supply via the temperature control unit 130. The phase detection signal DS_ph is output.

For example, when the AC power is applied at 60 Hz as shown in FIG. 4, the phase detector 140 outputs 120 phase detection signals by outputting a phase detection signal whenever the AC power passes the zero-crossing time point. Done. This is, for example, when the duty ratio of the first control signal CS1 is 100%, and when the duty ratio of the first control signal CS1 is 100% or less, the phase detection signal is output in proportion to the number of times. .

The switching unit 150 is connected between the fixing unit 110 and the temperature control unit 130 and is switched on / off by the second control signal to control the application of AC power AC_IN to the fixing unit 110. The switching unit 150 is, for example, composed of a switch such as a relay switch (relay switch), the contact is formed by the electromagnetic force formed according to the second control signal CS2 output from the controller 162, the power supply unit 120 Provides a moving path of the AC power applied from).

Referring to the controller 162 according to an embodiment of the present invention in more detail, the controller 162 uses the phase detection signal DS_ph output from the phase detection unit 140 as a synchronization signal to control the first control signal CS1. Control the output timing.

In addition, the controller 162 may further include a counter unit (not shown) that counts the number of times of outputting the phase detection signal DS_ph, and the controller 162 may include a duty ratio of the first control signal CS1. An output expectation value of the phase detection signal detected by the first node N1 may be stored.

The controller 162 compares the actual output count of the phase detection signal DS_ph counted by the counter unit with the expected output value of the phase detection signal, and when the result of the comparison does not match, an abnormal operation of the temperature control unit 130 In response to determining that the internal device is in a bad state, the control unit CS2 is outputted and the switching unit 150 is forcibly turned off.

For example, in the case where the fixing unit 110 is in an on state (the switching unit 150 is in an on state), the controller 162 may have a duty ratio of the first control signal CS1 of 100% and an output expected value of 60 Hz. 120 cycles can be set for 100% of power and duty ratio. If the phase detection signal DS_ph detected by the first node N1 does not match when the first control signal CS1 is output, the controller 162 may operate abnormally, that is, the temperature controller. Recognizing that an internal element of the device 130, in particular, a triac TA driven by receiving a large signal is a defective or damaged component, and notifies the occurrence of an error through a user interface unit (not shown) of the image forming apparatus 100. The second control signal CS2 is output.

If the fixing unit 110 is in the off state (the switching unit 150 is in the on state), the controller 162 may set the duty ratio of the first control signal CS1 to 0% and the output expected value to 0. have. The controller 162 is supplied with AC power AC_IN to the first node N1 before the fixing unit 110 is turned on, that is, before the first control signal CS1 is output, so that the phase detection signal ( It is determined whether or not DS_ph) is output. In this case, when the phase change of the AC power is generated at the first node N1 and the phase detection signal DS_ph is output, the triac TA may be driven by receiving an internal element of the temperature controller 130, in particular, a large signal. ) Is a case where a component is defective or damaged, an error occurrence is notified through a user interface unit (not shown) of the image forming apparatus, and the second control signal CS2 is output.

In this case, when the fixing unit 110 is in the off state, the switching unit 150 has been described as being in an on state. However, the temperature control unit 130 is damaged and is switched through the H / W protection unit 164 depending on the temperature of the fixing unit. Even when the unit 150 is in an OFF state, the unit 150 may be driven in the same manner.

In summary, the image forming apparatus 100 according to an embodiment of the present invention may have an abnormality of the temperature control unit 130 before the control unit 160 outputs the first control signal CS1 for applying the AC power to the fixing unit. It is determined whether the driving is performed, and in abnormal driving, the second control signal CS2 is output to deactivate the switching unit 150, thereby preventing the AC power from being applied to the fixing unit 110.

In the exemplary embodiment of the present invention, the counter unit is configured in the controller 162 and the switch unit 150 is forcibly turned off under the control of the controller 162. For example, the counter outside the controller 162 is described. The present invention can be applied substantially the same to the case where the controller 162 abnormally operates through a method of forming a memory unit for storing the negative unit and the output expected value and a comparison means for comparing the two.

As described above, according to the present invention, it is possible to stably control the temperature of the fuser by detecting that an internal element of the fuser control device is defective or damaged while driving and abnormally operates to block AC power from being applied to the fuser.

In addition, when abnormal operation of the fixing apparatus control device is performed, the application of the AC power source is blocked, so that the internal latent heat can be prevented from increasing.

In addition, it is possible to prevent an increase in internal latent heat to prevent damage to a thermostat such as a thermostat, and to prevent deterioration of accessories such as bushings, thereby improving the life of the image forming apparatus. have.

While the foregoing has been described with reference to preferred embodiments of the invention, those skilled in the art will be able to make various modifications and changes to the invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (6)

An image forming apparatus having a fixing unit, A power supply for providing AC power; A temperature control unit controlling a timing at which the AC power is applied to the fixing unit in response to a first control signal; A switching unit to block the application of the AC power in response to a second control signal when the temperature of the fixing unit exceeds a preset overheat temperature by the AC power; A phase detector for detecting a phase change of the AC power and outputting a phase detection signal; And And a controller configured to compare the output frequency of the phase detection signal with an output expected value of a preset phase detection signal and output one of the first and second control signals according to the comparison result. . The method of claim 1, wherein the control unit, And comparing the output expected value with the number of outputs of the phase detection signal output for a predetermined time, and outputting the first control signal if it is the same and outputting the second control signal if it is different. The method of claim 1, wherein the control unit, And comparing an output frequency of the phase detection signal output from the phase detection unit with the expected output value before the temperature control unit and the switching unit are activated. The method of claim 1, wherein the phase detection unit, And the phase detection signal is connected between the temperature controller and the switching unit and outputs the phase detection signal in a section between zero-crossing time points of the AC power. In a driving method of an image forming apparatus having a fixing unit, Outputting a phase detection signal by detecting a phase change of an AC power applied from the outside; Comparing an output expected value of a phase detection signal preset with an output frequency of the output phase detection signal according to a driving state of the fuser unit; And According to the comparison result, the first control signal for controlling the application of the AC power supply so that the fuser has at least one surface temperature, and the second control signal for blocking the application of the AC power supply so that the surface temperature of the fuser is lowered And outputting one of the methods of driving the image forming apparatus. The method of claim 5, wherein the first control signal is output when the output control value and the output frequency of the phase detection signal output for a predetermined time are compared with each other and are the same. And the second control signal is output when the output control value for the predetermined time is compared with the output frequency of the phase detection signal output for the predetermined time and is different.

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