JPH11102129A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the rising time of a device and to optimally distribute consumed power in the midst of the standby of the device and in the midst of forming an image. SOLUTION: This device is provided with at least two exothermic resistors 42a and 42b in the heater 31 of the fixing device 20, and a controller 101 controls to switch energizing so that the resistors 42a and 42b are energized when the device rises (at the time of warm-up) and only either resistor 42a is energized when the device stands by and when the image is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., which forms an image using an electrophotographic process, and more particularly, to a method of heating a toner image transferred to a transfer material to fix the toner image. The present invention relates to an image forming apparatus provided with a fixing device for performing the fixing.

[0002]

2. Description of the Related Art In an image forming apparatus utilizing an electrophotographic process, during image formation, the surface of an electrophotographic photosensitive member is uniformly charged by a charging device, and the charged surface of the electrophotographic photosensitive member is exposed by an exposing device. To form an electrostatic latent image. The electrostatic latent image is developed by a developing device to form a toner image, the toner image is transferred to a transfer material such as paper by a transfer device, and the toner image is permanently fixed on the transfer material by a fixing device. Is fixed and output.

Conventionally, a heat roller system has been generally used for fixing a toner image by the fixing device.
In order to save power and shorten the time from power-on to image output, a film heating and fixing device has been proposed (for example, Japanese Patent Application Laid-Open No. 63-313182, Japanese Patent Application Laid-Open No.
No. 1577878).

[0004] The film heating and fixing apparatus comprises a heating element provided with a heating resistor (heater, etc.), a heat-resistant fixing film that slides in contact with the heating element on one side, and a transfer material via the fixing film. A pressure roller that is in close contact with the heating element,
The toner image can be fixed as a permanently fixed image on the transfer material by heating the transfer material by nipping and transporting the fixing film and the transfer material together in the nip formed by the heating element and the pressure roller. .

[0005]

In a conventional image forming apparatus provided with the above fixing device, the temperature of a nip (fixing portion) formed by a heating element and a pressure roller of the fixing device quickly reaches a target temperature. Therefore, the resistance value is set so as to increase the output of the heating resistor (heater or the like) of the heating element.

However, of the total power consumption of the image forming apparatus, the power that can be allocated to the heating resistor (heater or the like) of the fixing device is the amount excluding the power of the drive system load such as a motor and a clutch. As the power of the drive system load increases, the power allocated to the heating resistor decreases, and the warm-up time (start-up time) of the image forming apparatus increases.

In the above-described conventional image forming apparatus, the power consumed at the time of warm-up (start-up) is equal to the power consumed at the time of image formation and at the time of standby of the apparatus. There is a problem that wasteful power is wasted.

Accordingly, an object of the present invention is to provide an image forming apparatus capable of shortening a warm-up time (start-up time) and reducing power during image formation and during standby of the apparatus.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a heating element provided with a heating resistor which generates heat by energization, and a sliding contact between the heating element and one surface. A rotatable endless heat-resistant fixing film that contacts the transfer material on which the toner image has been transferred on the other surface,
A rotatable pressure member for bringing the transfer material into close contact with the heating element via the fixing film, and a fixing nip portion formed by the heating element and the pressure member; In the image forming apparatus having a fixing device for heating the transfer material by being pinched and conveyed together, the heating element has at least two or more of the heating resistors, and Control means for controlling switching of energization according to the state of the image forming apparatus.

[0010] Further, the control means energizes the plurality of heating resistors when the image forming apparatus is started up,
At the time of standby and image formation of the image forming apparatus, power supply switching control is performed so as to supply power to a smaller number of the heating resistors than at the time of startup.

Further, the plurality of heating resistors have different resistance value ratios.

(Operation) According to the configuration of the present invention, when the apparatus is started up after the power is turned on, the plurality of heating resistors of the fixing apparatus are energized, and the standby state after the fixing temperature reaches the target temperature and the image forming operation. At the time of formation, by controlling the energization switching so as to energize a smaller number of heating resistors than at the time of startup, the startup time can be reduced, and the power consumed during standby and during image formation is reduced. be able to.

[0013]

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

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to the present embodiment (in the present embodiment, a copying machine of a transfer type electrophotographic type, a platen-optical system moving type).

In FIG. 1, reference numeral 1 denotes a fixed platen glass, and a document (not shown) is placed on the platen glass 1 with an image surface to be copied facing downward according to a predetermined placing reference. The original pressing plate 2 is set from above.

When a copy start button (not shown) is depressed after the original is set, a copy start signal is output. Based on the copy start signal, the original exposure lamp 3a is turned on, and the original exposure lamp 3a and the first mirror 3 are turned on.
b moves forward from the home position on the left side to the right side at a predetermined speed V along the lower surface of the platen glass 1, and the second mirror 3
c and the third mirror 3d reciprocate at the speed of V / 2 in the same direction as the original exposure lamp 3a and the first mirror 3b, so that the downward image surface of the original set on the original table glass 1 is shifted to the left side. Is scanned from the right side to the right side.

The original surface reflection light L of the illumination scanning light is transmitted through a drum lens 3e, a fourth mirror 3f, a fifth mirror 3g, and a sixth mirror 3h through a drum type electrophotographic photosensitive member (hereinafter, referred to as a drum type electrophotographic photosensitive member).
Irradiation is performed on the surface of a photosensitive drum 4), and slit image formation exposure is performed at a predetermined exposure position on this surface.

The photosensitive drum 4 is rotationally driven in a clockwise direction at a predetermined peripheral speed, and is uniformly charged to a predetermined polarity and potential by a primary charger 5 before receiving the exposure. Accordingly, by performing the above-described exposure on the charged surface of the photosensitive drum 4, an electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive drum 4, and the electrostatic latent image is developed as a toner image by the developing device 6. Is done.

On the other hand, the transfer material P is separated and fed one by one from a paper feed cassette 7 by a paper feed roller 8 and a separation claw 9, and is transferred along a path of a sheet path 10, transport rollers 11 and 12, and a registration roller 13. It is introduced at a predetermined timing into a transfer portion between the transfer device 14 and the transfer device 14. Alternatively, the transfer material P is inserted from the multi-manual paper feeding unit 15,
The toner is introduced into the transfer unit at a predetermined timing along the path of the conveying roller 12 and the registration roller 13.

The toner image formed on the surface of the photosensitive drum 4 is transferred to the transfer material P conveyed to the transfer section.
The transfer material P on which the toner image has been transferred is separated from the photosensitive drum 4 and placed on the belt of the transport device 19, introduced into a fixing device 20 to be described later, subjected to a heating and fixing process of the toner image by the heater 31, and discharged. The paper is discharged to the paper discharge tray 22 by the rollers 21.

After the transfer of the toner image onto the transfer material P, the surface of the photosensitive drum 4 is cleaned by a cleaning device 17 to remove remaining deposits such as untransferred toner and the like. The potential is removed, and the image is repeatedly provided for image formation.

In the above-described image forming apparatus, a paper feed unit, a transport unit, a photosensitive drum, a fixing unit, and the like are driven by a DC brushless motor M1 as a main drive source, and an optical system (a mechanism for reading an image) is used. The output of the phase excitation signal applied to each phase Aa, A *, B, B * of the stepping motor M2 is determined by the speed information set in the load for 2 times.
The two types of phase excitation method and 1-2 phase excitation method are switched.

As described above, the sheet feeding method can be selected from sheet feeding from the sheet feeding cassette 7 and sheet feeding from the multi-manual sheet feeding section 15.

In the case of paper feeding from the paper cassette 7, a switch group 23 for detecting the presence or absence of the paper cassette 7 and detecting the size of the transfer material P (paper) in the paper cassette 7.
The state of the transfer material P is managed by a switch 24 for detecting the presence or absence of the transfer material P in the paper feed cassette 7, and when an abnormality is detected by the switches 23 and 24, a display unit (not shown) Is displayed to that effect. In the case of multi-manual feed, the state is managed by a switch (not shown) for detecting the state of the multi-manual feed unit 15, and when an abnormality is detected, a display to that effect is displayed on a display unit (not shown).

Next, the fixing device 20 will be described in detail. The fixing device 20 of the present embodiment is a film heat fixing device. FIG. 2 is a sectional view showing a schematic configuration of the fixing device 20, FIG. 3 is a perspective view thereof, and FIG. 4 is a partially cutaway perspective view of a heating element.

In these figures, reference numeral 31 denotes a heating element (hereinafter, referred to as a heater), which is fixedly supported on the lower surface of a heat-resistant plastic supporter 32 with the heat-generating surface side facing downward. Reference numerals 33 and 34 denote a film drive roller and a film tension roller. The two rollers 33 and 34 and the plastic supporter 32 of the heater 31 are disposed substantially parallel to each other. An endless belt-like heat-resistant film (hereinafter, referred to as a fixing film) 35 is stretched and stretched therebetween.

Reference numeral 36 denotes a pressure roller which is pressed against the lower surface of the heater 31 with the fixing film 35 interposed therebetween, and has a pressure contact nip portion (fixing nip portion) between the heater 31 and the pressure roller 36 with the fixing film 35 interposed therebetween. , Heating nip portion) N is formed.

The fixing film 35 has a predetermined peripheral speed in the clockwise direction with the clockwise rotation of the driving roller 33, that is, substantially equal to the transport speed of the transfer material P introduced into the fixing device 20 by the transport device 10 from the transfer section. It is driven to rotate at the same peripheral speed, and is subjected to correction control so as to prevent wrinkles, meandering, and speed delay. For example, in the present embodiment, as shown in FIG. 3, a regulating member 37 that detects the movement of the film or restricts the movement of the film is provided, and the movement of the film is controlled based on a signal from the regulating member 37. A meandering of the fixing film 35 is prevented by a control mechanism (not shown).

The pressure roller 36 is a roller having a rubber elastic layer having good releasability such as silicone rubber.
The heater 31 is pressed against the lower surface of the heater 31 with a contact pressure of 4 to 10 kg in total. The pressure roller 36 is driven to rotate by the fixing film 35.

Then, when the fixing film 35 is driven to rotate and the heater 31 is in a heating state, the transfer material P is introduced into the press-contact nip N formed between the fixing film 35 and the pressure roller 36. Then, the transfer material P comes into close contact with the surface of the fixing film 35, is conveyed while being held together with the film 35, is heated by receiving the heat of the heater 31 via the fixing film 35, and is heated by the unfixed toner image on the transfer material P. T is transfer material P
The surface is heated and pressurized. The transfer material P that has passed through the pressure nip N is separated from the surface of the fixing film 35 by a curvature.

Since the fixing film 35 is repeatedly subjected to heat fixing of the toner image, it is excellent in heat resistance, releasability, durability and the like, and generally has a total thickness of 100 μm or less, preferably 4 μm or less.
Use a thin material of 0 μm or less.

As the fixing film 35, a single-layer film of a heat-resistant resin such as polyimide, polyetherimide, PES, PFA (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer resin) or a composite layer film, for example, 20 μm A release coating layer having a conductive material added to a fluororesin such as PTFE (tetrafluoroethylene resin) or PAF with a thickness of 10 μm was provided on at least the image contacting surface side of the transfer material P as the material to be heated of the layer film. What can be used.

The heater 31 as a heating element is shown in FIGS.
As shown in FIG. 3, an elongated heater substrate 41 having heat resistance, insulation, and good thermal conductivity whose longitudinal direction is perpendicular to the moving direction of the fixing film 35 or the transfer material P, and a surface side of the heater substrate 41 Heating resistors 42a and 42b (resistive values are Ra and Rb (Ra <Rb), respectively) formed at the center in the short side direction along the substrate longitudinal direction, and the longitudinal sides of the heating resistors 42a and 42b. Power supply electrodes 43 at both ends
a, 43b, and a heat-resistant overcoat layer 44 that protects the surface of the heater on which the heating resistors 42a, 42b are formed.

One surface of the heater substrate 41 in the longitudinal direction is
As shown in FIG. 4, it is polished so as to have a C-plane shape, and as shown in FIG. 2, the C-plane comes to the pressure contact nip N side. This serves to prevent the transfer material P from being rapidly heated and curled. The positions of the heating resistors 42a and 42b are
Are not located at the center with respect to the short side direction, but are closer to the C-plane side. That is, the heater 31 includes the heating resistor 42a,
The surface side of the heater substrate 41 provided with 42b is exposed downward (toward the pressure roller 36), and is fixedly disposed while being held by the plastic supporter 32.

Examples of the plastic supporter 32 include high heat-resistant resins such as PPS (polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyether ether kentone), liquid crystal polymer, etc. A composite material with metal, glass, or the like can be used.

The heater substrate 41 is made of, for example, alumina or aluminum nitride having a thickness of 1 mm, a width of 10 mm, and a length of 24 mm.
It is configured with 0 mm insulation and good thermal conductivity.

The heating resistors 42a and 42b are made of, for example, Ag.
/ Pb, RuO ₂ , Ta ₂ N or the like, and is composed of a screen printing pattern layer having a width of several mm and a thickness of several 10 μm. The power supply electrodes 43a and 43b are made of, for example, Ag, Cu,
It is composed of a conductive material pattern layer made of Au or the like.

The power supply electrodes 43a, 43a,
When a voltage is applied to 43b, the heating resistors 42a, 42
b, power is supplied to the heating resistors 42a, 42b,
42b generates heat, and the heater 31 including the heat generating resistors 42a and 42b is quickly brought into the heating state.

A metal stay (not shown) attached to reinforce the plastic supporter 32 includes:
First and second temperature detecting elements (thermistors) 45 and 46 for detecting the temperature of the heater 31 are attached, and are in direct contact with the back surface of the heater 31 (the back surface of the heater substrate 41).

As shown in FIG. 3, the first temperature detecting element 45 has a heater length area (large or small size transfer material P) corresponding to the width of the paper passing area of the transfer material P of the minimum size that can be used. (The area which also becomes the paper passing area) corresponding to the heater back surface. Further, the second temperature detecting element 46 is located at a position corresponding to the heater back surface portion of the heater length area corresponding to the non-sheet passing area when the small-sized transfer material P is passed.
That is, the heater 31 is disposed corresponding to the heater back surface from the end opposite to the paper passing reference side end.

Next, control of energization of the heating resistors 42a and 42b will be described with reference to FIG.

In FIG. 5, reference numeral 101 denotes a controller for controlling the temperature control and switching power control of the heater 31; 102, a commercial AC power source S as a power supply source; and an input voltage detection circuit for detecting an input voltage.
b is a switching circuit for switching the voltage applied to the heating resistors 42a and 42b of the heater 31, respectively.
Reference numeral 04 denotes an operation unit.

The controller 101 inputs the AC input voltage value from the input voltage detection circuit 102 to the input voltage A / D. This is the effective value Erms of the input voltage. Also,
The outputs of the first and second temperature detecting elements (thermistors) 45 and 46 are also input to the A / D of the controller 101. On the other hand, since the resistance values of the heating resistors 42 a and 42 b of the heater 31 are measured in advance in a normal temperature environment, the resistance values are determined by the controller 1 using the operation unit 104.
01 to a non-volatile memory (not shown).

The input voltage detecting circuit 102 generates a zero-cross signal from the AC input, and
The trigger signal is
This is a timing signal for controlling the phase of the power supply to the heating resistors 42a and 42b.

In the present invention, the controller 101
During the warm-up (start-up) immediately after the power supply (not shown) of the image forming apparatus is turned on, the heating resistors 42a, 42a of the heater 31 until the target temperature is reached.
b, the heating resistor 42a is turned on during standby of the apparatus after reaching the target temperature and during the image forming operation.
Power is supplied only to As a result, the power consumed by the image forming apparatus is as follows: (Warmup) = Wwarmup = (Vh) ² / Ra + (Vh) ² / Rb + α1 (1) (Waiting for the apparatus) Wstandby = (Vh) ² / Ra + α1 (2) (During image formation) Wcopy = (Vh) ² / Ra + α1 + α2 (3)

Here, Vh: applied voltage to the heater 31 Ra: resistance value of the heating resistor 42a Rb: resistance value of the heating resistor 42b α1: power consumption of a control system of the device α2: drive system of the device (motor , Clutch, solenoid, etc.) (α1 <α2) As described above, in the present embodiment, at the time of warm-up of the apparatus, the power allocated to the heater 31 of the fixing device 20 is transferred to the drive system (motor, clutch, etc.) of the apparatus. , Solenoids, etc.), the warm-up time can be reduced, and the power consumption of the heater 31 of the fixing device 20 during the standby and during the image formation can be optimally distributed. .

[0047]

As described above, according to the present invention,
A control unit that includes at least two or more heating resistors provided on a heating element of the fixing device and that controls switching of energization to the plurality of heating resistors according to a state of the image forming apparatus; Therefore, when the apparatus is started up, power is supplied to a plurality of heating resistors, and when the apparatus is on standby and an image is formed, power supply switching control is performed so that power is supplied to a smaller number of heating resistors than during startup. Power (at the time of warm-up) can be increased, so that the start-up time (warm-up time) can be shortened, and the power consumption during standby of the apparatus and during image formation can be optimized. It is possible to allocate.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a fixing device of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view of a fixing device of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a partially cutaway perspective view of a heating element of the fixing device.

FIG. 5 is a block diagram of a heater control system of the fixing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 platen glass 4 photosensitive drum 5 primary charger 6 developing device 14 transfer device 20 fixing device 31 heater (heating body) 35 fixing film 36 pressure roller (pressing member) 42a, 42b heating resistor 101 controller (control means)

Claims (3)

[Claims] 1. A heating element provided with a heating resistor that generates heat when energized, and a sliding contact with the heating element on one surface and a transfer material having a toner image transferred to the surface on the other surface. A rotatable endless heat-resistant fixing film, and a rotatable pressure member for bringing the transfer material into close contact with the heating member via the fixing film, formed by the heating member and the pressing member An image forming apparatus having a fixing device that heats the transfer material by sandwiching and transporting the fixing film and the transfer material together in a pressing nip portion to be pressed, wherein the heating element includes at least two or more of the plurality of heat sources. An image forming apparatus comprising: a resistor; and a control unit that controls switching of energization to the plurality of heating resistors according to a state of the image forming apparatus. 2. The control device according to claim 1, wherein the control unit supplies power to the plurality of heating resistors when the image forming apparatus is started up, and a smaller number of the heating resistors during standby and image formation of the image forming apparatus than at the time of startup. The image forming apparatus according to claim 1, wherein energization switching control is performed so as to energize the heating resistor. 3. The image forming apparatus according to claim 1, wherein the plurality of heating resistors have different resistance value ratios.