JP2000172107A - Electronic photographic device and fixing unit energization control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic photographic device where the heating part of a fixing unit is energized at the zero cross point of an AC waveform and noise and a flicker are reduced. SOLUTION: A delay pulse output part 4 detecting the delay of input/output between a zero cross signal inputted to a control part 3 and a energization-on signal outputted to a switch part 21 and outputting a delay pulse signal is installed. A delay time operation means 312 operates the delay time of input/ output between the zero cross signal and the energization-on signal from the pulse width of the delay pulse signal. A fixed temperature control means 311 outputs the energization-on signal to the switch part 21 at output timing time decided based on the period of the zero cross signal and operated delay time. Thus, the conduction of the fixing unit 1 to the heater 12 can be executed at the zero cross point of an AC waveform and noise and a flicker can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more particularly to an on / off control of energization of a heating unit of a fixing device.

[0002]

2. Description of the Related Art Conventionally, a fixing device used in an electrophotographic apparatus comprises a fixing roller and a pressure roller which come into contact with each other and rotate, and a heating device for heating one or both of the rollers. Is provided. The heating unit is directly connected to an AC circuit on the primary side, and the AC circuit controls on / off of the heating unit by a semiconductor switch such as a triac.

[0003] It is a well-known technique that turning on at the AC zero-crossing point when controlling the energization of the AC causes less noise and flicker, and is usually provided with a zero-crossing detection circuit. However, in the means for controlling the temperature of the fixing device, there is a delay of a hardware signal or a delay of a software processing time from the input of a zero-cross signal to the output of an ON signal to a heating unit. The point at which the heating unit is turned on does not coincide with the zero cross point of the AC waveform.

FIG. 7 is a block diagram showing a configuration of a conventional control system for controlling the temperature of the fixing unit. The ON control of the heater 12 provided in the fixing device 1 is performed by the CPU based on information from the temperature sensor 11 and the zero-cross signal output unit 22.
A heater-on signal is output from the fixing temperature control unit 511 in the switch 51 to the switch unit 21 for turning on / off the heater 12.

The switch section 21 turns on the power to the heater 12 based on the input heater-on signal. Since a triac is generally used as an AC switch element of the switch unit 21, the timing of turning off the power can be cut off only at the AC zero crossing point due to the characteristics of the element, so that there is no particular problem.

The CPU 51 controls the sequence of the entire electrophotographic apparatus.
Corresponds to a subroutine-like part, so that a delay in software processing time occurs.

The basic operation of temperature control is to output a heater-on signal when the signal from the temperature sensor 11 falls below a control point set in the fixing temperature control means 511, and to output a heater-off signal when the signal exceeds the control point. Is output. The timing at which the heater-on signal is output is generated by the zero-cross signal output means 22.

FIG. 8 shows the relationship between the AC waveform and the signal in the conventional control.
This will be described with reference to FIG. A delay time td including a hard delay and a soft processing time is generated between the zero cross signal input to the fixing temperature control unit 511 and the heater ON signal output. Accordingly, the energization of the heater 12 starts from the middle of the sine wave. If the heater 12 is controlled to be turned on by a pulse as indicated by a dotted line, the above-described delay time occurs at each peak of the sine wave.

[0009]

As described above, in the conventional electrophotographic apparatus, the delay time in the control system is not considered, and the heater-on signal is output after the zero-cross signal is input to the fixing temperature control means. The heater, which is the heating unit, is turned on while including the delay time of hardware and software until it is performed.

Therefore, since the heating section is actually turned on at a point beyond the zero-cross point, the degree of noise and flicker increases. About flicker,
It will be regulated in the near future. Electrophotographic equipment is also A3
It is necessary to increase the capacity of the heating unit in order to cope with paper and further increase in speed. From such a point, it is important in the future that the on / off control of the AC is basically performed at the zero-cross point.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic apparatus and a fixing unit energization control method in which energization of a heating unit of a fixing unit is performed at a zero cross point of an AC waveform to reduce noise and flicker.

[0012]

In order to achieve the above-mentioned object, an electrophotographic apparatus according to the present invention is characterized in that a heating unit is supplied after a zero-cross signal for controlling energization to a heating unit of a fixing unit is inputted. Calculates the delay time between input and output until the energization ON signal is output, determines the output timing time of the energization ON signal based on the calculated delay time, and sets the energization ON signal at the determined output timing time. To output.

Specifically, the present invention provides the following apparatus and method.

According to the present invention, there is provided a heating unit for heating a roller for fusing and fixing a toner image on a recording medium, a fixing device having a temperature detecting unit for detecting a surface temperature of the roller, and energizing the heating unit. A power supply unit having a switch unit for turning on / off, and a zero-cross signal output unit for detecting a zero-cross point of an AC input input to the switch unit and outputting a zero-cross signal, based on the detected temperature and the output zero-cross signal, An electrophotographic apparatus including a control unit for controlling on / off of energization of the heating unit, wherein the zero-cross signal input to the control unit and the detected temperature fall below a preset control point. A delay pulse output unit for detecting a delay between input and output with an energization ON signal output to the switch unit and outputting a delay pulse signal. The control unit calculates a delay time between input and output of the zero-cross signal and the energization ON signal from a pulse width of the output delay pulse signal, and a delay time calculating unit that calculates the cycle of the zero-cross signal. A fixing temperature control unit that determines an output timing time of the energization ON signal based on the determined delay time and outputs the energization ON signal to the switch unit at the determined output timing time. Provide equipment.

Preferably, the control unit has a delay time storage unit for storing the delay time calculated every time the delay pulse signal is output, and the fixing temperature control unit is calculated and stored last time. When the calculated delay time does not match the currently calculated delay time, the stored previous delay time is replaced with the currently calculated delay time,
The output timing time is corrected.

Further, the present invention provides a heating unit for heating a roller for fusing and fixing a toner image on a recording medium, a fixing device having a temperature detecting unit for detecting a surface temperature of the roller, and energizing the heating unit. Switch for turning on / off,
And a power supply unit having a zero-cross signal output unit that detects a zero-cross point of an AC input to be input to the switch unit and outputs a zero-cross signal, based on the detected temperature and the output zero-cross signal, In an electrophotographic apparatus including a control unit for controlling energization on / off, the control unit determines whether the zero-cross signal input to the control unit and the detected temperature fall below a preset control point. A timing time storage means for preliminarily storing an output timing time for correcting a delay time between input and output with an energization ON signal output to the switch unit; and the energization ON signal to the switch unit at the output timing time. And a fixing temperature control unit for outputting the output.

The present invention also relates to a fixing device energization control method for controlling the energization on / off of a heating unit of a fixing unit for fusing and fixing a toner image on a recording medium. A delay time between input and output from when a signal is input to when an energization ON signal to the heating unit is output is calculated, and an output timing time of the energization ON signal is determined based on the calculated delay time. The present invention provides a fixing device energization control method, wherein the energization ON signal is output at the determined output timing time.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electrophotographic apparatus and a fixing device energization control method according to an embodiment of the present invention will be described with reference to the drawings.

First, the overall configuration of an electrophotographic apparatus according to one embodiment of the present invention will be described with reference to FIG. Although the example of FIG. 6 is a color electrophotographic apparatus, the present invention is not particularly limited to a color apparatus.

The photoreceptor belt 14 having an organic photoconductive material (OPC) coated on its surface is driven to rotate in the direction of the arrow in FIG. The belt cleaner 51 removes the toner remaining on the photoreceptor belt 14 after completing the image formation for each color. The charger 50 charges electric charges necessary for forming an electrostatic latent image on the surface of the photoreceptor belt 14.

The laser light emitted from the optical unit 19 exposes the surface of the charged photosensitive belt 14 to form an electrostatic latent image. The developing units 15 to 18 are provided with the photosensitive belt 1
The electrostatic latent image formed on the surface of No. 4 is developed with each toner in the order of first black, second cyan, third magenta, and fourth yellow.

The intermediate transfer drum 52 is connected to the photosensitive belt 14
The toner image formed on the surface of the photoreceptor belt 14 is transferred (first transfer) in the order of black, cyan, magenta, and yellow (first transfer) and superposed to form a color toner image. Form.

The transfer roller 53 transfers (second transfer) the color toner image formed on the intermediate transfer drum 52 onto the recording medium 13 by applying an electric field of reverse polarity from the back side of the recording medium 13.

The fixing device 1 fuses the toner transferred onto the recording medium 13 by heat. The drum cleaner 55 is
The color toner image on the intermediate transfer drum 52 is
After the transfer to the drum 3, the toner remaining on the drum surface is removed.

Next, the structure of the fixing device 1 will be described with reference to the schematic diagram of FIG.

The fixing roller 5 is formed by forming a layer of silicon rubber 7 on an aluminum tube 9, and has a heater 12 a as a heating unit at the core of the aluminum tube 9. Similarly, the pressure roller 6 is also formed by forming a single layer of silicon rubber 8 on an aluminum tube 10.
2b. Note that a sensor 11 serving as a temperature detecting unit is provided on the surface of the fixing roller 5. In this embodiment, the heating unit is also provided on the pressure roller 6 side, but it is needless to say that the heating unit may be provided only on the fixing roller 5 side.

In the fixing device having the above configuration, the fixing temperature is controlled by turning on / off the heaters 12a and 12b. The present invention particularly relates to the control of turning on AC that energizes the heaters 12a and 12b.

FIG. 1 is a block diagram showing a functional configuration of the entire temperature control system for controlling the temperature of the fixing device 1 of FIG.

As shown in FIG. 1, the temperature control system
A temperature sensor 11 which is a temperature detecting unit for detecting a surface temperature of the fixing roller 5 of the fixing device 1, a heater 12 which is a heating unit for heating the fixing roller 5, and a power supply to the heater 12 is turned on / off.
The switch unit 21 to be turned off and the AC input to the switch unit
A zero-cross signal output unit 22 that detects a zero-cross point of an input and outputs a zero-cross signal, a control unit 3 that controls on / off of energization of the heater 12, and a switch unit 21 after the zero-cross signal is input to the control unit 3. A delay pulse output unit 4 detects a hardware and software delay between the input and output until the energization ON signal is output, and outputs a delay pulse signal.

The control unit 3 includes a delay time calculation unit 312 executed in the CPU 31 and a fixing temperature control unit 311.
Delay time storage means 321 executed in the memory 32
It is composed of

The delay time calculating means 312 calculates the delay time between the input and output of the zero cross signal and the energization ON signal from the pulse width of the output delay pulse signal. In other words, the delay time of the entire temperature control system is calculated.

The fixing temperature control means 311 controls the heater 12 based on the cycle of the zero-cross signal and the calculated delay time.
The output timing time of the energization ON signal is determined so that energization to the power supply is performed at the zero crossing point, and the energization ON signal is output to the switch unit 21 at the determined output timing time.

The delay time storage means 321 stores the delay time calculated by the delay time calculation means 312 via the fixing temperature control means 311.

The fixing temperature control means 311, delay time calculation means 312, and delay time storage means 321 are shown in FIG.
The timing of the C waveform and the signal is shown. As shown in FIG.
A timing time for outputting the heater-on signal at the next zero-cross point of the sine wave is calculated from the cycle time of the zero-cross signal and the delay time stored in the delay time storage means 321. That is, the output timing time tx for turning on the heater at the next zero-cross point from the current zero-cross signal.
make.

The output timing time tx needs to be corrected because the delay time may change depending on the characteristics of the equipment used in the electrophotographic apparatus and the power supply situation of the use environment. The correction of the output timing time is performed by the control unit 3
Can be executed by performing control as shown in the flowchart of FIG.

In FIG. 3, the fixing temperature control means 311
Generates an energization ON signal based on a signal from the temperature sensor 11 (step 101), and outputs the zero-cross signal output unit 2
Wait for a zero-cross signal from 2 (step 102).

Next, when the zero cross signal is input, the previous delay time stored in the delay time storage means 321 is read (step 103), and the output timing determined based on the previous delay time and the cycle of the zero cross signal. An energization ON signal is output in time (step 104).

Next, the current delay time between the output energization ON signal and the input zero cross signal is calculated (step 105), and it is checked whether or not the current delay time matches the previous delay time (step 106). If they do not match, the previous delay time is replaced with the currently calculated delay time and corrected (step 107).

As described above, the output timing time can be corrected by substituting and correcting the delay time stored in the delay time storage means 321.

FIG. 4 shows another embodiment of the temperature control system of FIG. A temperature control system which can obtain the same effect as that of the temperature control system of FIG. 1 only by changing the software control method is different from the temperature control system of FIG. After the signal is input to the fixing temperature control unit 311, the switch unit 21
A timing time storage means 322 for preliminarily storing an output timing time for correcting a delay time between input and output until a power-on signal is output is provided, and the delay pulse output means 4 and the delay time calculation means 312 are not provided. Is a point.

The fixing temperature control means 311 includes the temperature sensor 1
By outputting an energization ON signal to the switch unit 21 at an output timing time stored in advance in the timing time storage means 322 when the signal from the control unit 1 falls below a preset control point, the energization of the heater 12 is performed. Is performed at the zero crossing point of the AC input.

Also in this embodiment, it is necessary to correct the output timing time as in the temperature control system of FIG. The correction of the output timing time in the present embodiment
This can be achieved by providing a device adjustment function in a service mode for performing maintenance and changing characteristics of the electrophotographic apparatus.

As described in the above embodiment, since the AC power supply to the heater 12 can be made to exactly coincide with the zero cross point, noise and flicker can be reduced.

[0044]

According to the present invention, the heating section of the fixing device is energized at the zero-cross point of the AC waveform to reduce noise and flicker, thereby improving the reliability of the electrophotographic apparatus.

Further, since the output timing time of the ON signal to the heating unit can be automatically corrected, the heating unit according to the characteristics of the equipment constituting the electrophotographic apparatus and the power supply condition of the use environment of the electrophotographic apparatus can be corrected. The power-on control can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a functional configuration of an entire temperature control system according to the present invention.

FIG. 2 is a diagram illustrating control timing of the temperature control system of FIG.

FIG. 3 is a flowchart illustrating a control method of FIG. 1;

FIG. 4 is a block diagram of a functional configuration of the entire other temperature control system of the present invention.

FIG. 5 is a schematic diagram illustrating the structure of a fixing device.

FIG. 6 is a schematic diagram illustrating an overall configuration of an electrophotographic apparatus according to one embodiment of the present invention.

FIG. 7 is a block diagram of a functional configuration of a conventional temperature control system.

FIG. 8 is a diagram illustrating control timing of the temperature control system of FIG. 7;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing device, 2 ... Power supply unit, 3 ... Control part, 4 ... Delay pulse output part, 11 ... Temperature sensor, 12 ... Heater,
21: switch section, 22: zero-cross signal output section, 31
.. CPU, 311 fixing temperature control means, 312 delay time calculation means, 32 memory, 321 delay time storage means, 322 timing time storage means

Claims (4)

[Claims] A fixing unit having a heating unit for heating a roller for fusing and fixing a toner image on a recording medium; and a temperature detecting unit for detecting a surface temperature of the roller, and energizing the heating unit on / off. And a power supply unit having a zero-cross signal output unit for detecting a zero-cross point of an AC input to be input to the switch unit and outputting a zero-cross signal, and performing the heating based on the detected temperature and the output zero-cross signal. An electrophotographic apparatus including a control unit for controlling on / off of energization of the unit, wherein the zero-cross signal input to the control unit and the detected temperature fall below a preset control point. A delay pulse output unit that detects a delay between input and output with the energization on signal output to the switch unit and outputs a delay pulse signal; A delay time calculating means for calculating a delay time between input and output of the zero cross signal and the energization ON signal from a pulse width of the output delay pulse signal; a cycle of the zero cross signal and the calculated delay; An electrophotographic apparatus comprising: a fixing temperature control unit that determines an output timing of an energization ON signal based on the time, and outputs the energization ON signal to the switch unit at the determined output timing. 2. The fixing device according to claim 1, wherein the control unit includes a delay time storage unit configured to store the delay time calculated each time the delay pulse signal is output. When the calculated and stored delay time does not match the currently calculated delay time, the output timing time is corrected by replacing the stored previous delay time with the currently calculated delay time. Electrophotographic apparatus. 3. A fixing device having a heating unit for heating a roller for fusing and fixing a toner image on a recording medium, and a temperature detecting unit for detecting a surface temperature of the roller, and turning on / off power supply to the heating unit. And a power supply unit having a zero-cross signal output unit that detects a zero-cross point of an AC input input to the switch unit and outputs a zero-cross signal, based on the detected temperature and the output zero-cross signal. An electrophotographic apparatus comprising: a control unit that controls on / off of energization of a heating unit; wherein the control unit is configured to control the zero-cross signal input to the control unit and a control point in which the detected temperature is set in advance. The output timing time for correcting the delay time between input and output with the energization ON signal output to the switch unit when the output timing falls below An electrophotographic apparatus comprising: a storage time storage unit; and a fixing temperature control unit that outputs the energization ON signal to the switch unit at the output timing time. 4. A fixing unit energization control method for controlling on / off of energization to a heating unit of a fixing unit for fusing and fixing a toner image on a recording medium, wherein a zero cross signal for controlling energization to the heating unit is input. Calculates a delay time between input and output from when the power-on signal is output to the heating unit until the output time of the power-on signal is determined based on the calculated delay time. A method for controlling the energization of the fixing device, wherein the energization ON signal is output in time.