JP2003098863A - Fixing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In addition to achieving further energy saving, a fixing member or a member to be fixed such as paper is not distorted or wrinkled, and the meandering of the fixing object due to this can be prevented. To provide an image fixing device capable of preventing offset, offset and the like. The heating device includes a plurality of divided linear heating elements, means for applying a pulse current to each of the heating elements, and a pressing element which cooperates with an endless belt to hold a fixing object having an image thereon. A fixing device that heats an image in the object to be fixed via the endless belt by the heating element, and thereafter separates the object to be fixed having the image from the endless belt through a cooling process, wherein the image in the object to be fixed is Is formed using a toner in which the main component of the binder is a resin. The toner has a softening point or melting point of 50 to 160 ° C. and a viscosity of 10 to 10 at a temperature higher than the softening point or melting point. ¹³ (centipoise).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming technique using electrophotography used for copying, facsimile, printer and the like, and more particularly to an image fixing device useful for saving energy.

[0002]

2. Description of the Related Art Conventionally, demands for resource saving and energy saving have been increased to protect the global environment, and this is no exception in the field of electrophotography. On the other hand, looking at the actual usage patterns in copying, facsimile, printers, etc., the actual area of the image actually printed is about 2 to 10% per sheet to be fixed, and the remaining 90 to 90%. Although 98% has no image, it wastes heating even this non-image part,
There was a big problem from the viewpoint of energy saving. Therefore, it is preferable to heat only the image part without heating the non-image part, but the toner that uses resin as a binder that has been used conventionally has a high softening point or melting point of the toner. If you set the temperature of the heating element to a high temperature and heat only the image part, the fixing member and the fixing target such as paper will partially expand and cause distortion, causing the meandering and wrinkling. Therefore, practical application is difficult, and a technology capable of solving these problems is indispensable.

In order to solve these problems, it is conceivable to select a toner having a low softening point or a melting point as the toner to be used and realize low temperature fixing. However, the thermoplastic resin used in the toner is selected. As a characteristic of the above, when the softening point or the melting point is lowered, the melt viscosity is inevitably lowered. This property is such that the softening point or melting point of a thermoplastic resin is determined by the molecular weight, molecular weight distribution, crystallinity, crosslinking degree, intermolecular force of the resin, etc. Of these, the molecular weight and degree of crosslinking must be reduced or the molecular weight distribution must be narrowed. Of these, the lower limit of the molecular weight distribution is determined from the limit of the storability of the resin. Therefore, lowering the molecular weight itself inevitably narrows. Generally, when the molecular weight is lowered, the molecular chain becomes shorter, so that the entanglement becomes loose and the melt viscosity lowers. Further, even if the molecular weight distribution is narrowed, the entanglement of the molecular chains is loosened and the melt viscosity is lowered. Furthermore, when the degree of crosslinking between molecules is reduced, the respective molecules become easier to move, so the melt viscosity decreases. There is a serious problem that offset occurs when a toner having such a lowered melt viscosity is used.

On the other hand, as a technique for preventing offset, there is a method as shown in Japanese Patent Publication No. 51-29825, and the application of these methods is disclosed in Japanese Patent No. 2516886. is there. this is,
By making the heating element in JP-B-51-29825 a linear heating element and energizing the heating element in a pulsed manner, it is possible to shorten the standby time without needing residual heat and to suppress the release of excess heat into the machine. This is intended to reduce the temperature rise in the drier, and although it saves energy to some extent, the extent is not yet sufficient.

Further, in the uniform pulse-like electric heating,
The temperature at the leading edge of the image becomes low because the heating element and its support or the platen roller is cold, and conversely at the trailing edge of the image it becomes high because the heating element and support or the platen roller accumulate heat. However, there is a difference in the fixing temperature between the front end and the rear end. In that case,
The temperature setting at the leading edge of the image is set high to prevent defective fixing, and the rise in the temperature at the trailing edge is dealt with by expanding the so-called rubber region width of the toner.

However, if the melting point of the toner is lowered to save energy, it is very difficult to obtain a sufficient rubber band width.
Hot offset is likely to occur, or even if hot offset does not occur, the melt viscosity of the toner is too low, so that gloss is likely to occur in the image. Moreover, if the temperature is set to be high from the beginning in order to prevent fixing failure, the energy saving means will lose its effectiveness, and a further energy saving technique has been earnestly desired.

[0007]

SUMMARY OF THE INVENTION Therefore, in view of the above-mentioned prior art, it is an object of the present invention to achieve further energy saving and to prevent the fixing member or the member to be fixed such as paper from being distorted or wrinkled. An object of the present invention is to provide an image fixing device capable of preventing meandering or the like of an object to be fixed due to this and also preventing offset and the like.

[0008]

Means for Solving the Problems The above-mentioned problems are (1) "a linear heating element divided into a plurality, a means for energizing each of the heating elements with a pulse, and an object to be fixed having an image. An endless belt having a pressurizing member that cooperates with the endless belt to heat the image in the object to be fixed by the heating element through the endless belt, and then undergoes a cooling process to fix the object to be fixed having the image. The image is formed in the fixing target by using a toner whose main component is a resin, and the softening point or melting point of the toner is 50 to 160 ° C. And the viscosity is 10 to 10 ¹³ (cpoise) at a temperature equal to or higher than the softening point or the melting point, (2) "the linear heating element is divided into two or more. (1) Fixing device described in (1), (3) "Divided And wherein the changing the energizing pulse width in the one image of the fixation object in for each heating element image fixing apparatus according to (1) or (2) ",
(4) "The image fixing device according to (1) or (2), characterized in that the energization pulse density per unit time for each of the divided heating elements is changed within an image in one sheet to be fixed. (5) "In the image in one sheet to be fixed, the energizing pulse width and the pulse density per unit time for each divided heating element are changed in combination (1) or ( Image fixing device according to 2) ", (6)
"Any one of (1) to (5) is characterized in that, in an image in one sheet to be fixed, the energization pulse width or the number of energization pulses for each heating element divided from the start of fixing to the end of fixing is reduced. Or the image fixing device described in 1.
(7) “When the ratio of the change in the amount of electricity to the divided heating elements at the start of heating and at the end of heating is such that the object to be fixed has a length of 420 mm in MD (paper passing direction) Any of (2) to (5), which is 10: 9.5 to 10: 1 in terms of conversion of a fixed material when it is fed and discharged in the long side direction of A3 size according to JIS P 0138). Image fixing device according to item 1), (8) "At the timing of starting energization,
The fixing system according to any one of (1) to (6), characterized in that one pulse or more is applied before the leading edge of the image reaches each divided heating element portion. Each heating element generates heat only at a portion corresponding to an image portion, and the fixing system according to any one of (1) to (8), and (10) "each divided heating element is non- The fixing system according to any one of (1) to (9) is characterized in that the energization of the head is cut by 10% or more in the image portion.

The present invention will be described in detail below. The fixing device of the present invention includes a plurality of linear heating elements, a means for energizing each of the heating elements in a pulsed manner, and a pressurizing body for sandwiching an object to be fixed having an image in cooperation with an endless belt. A fixing device for heating an image in an object to be fixed through the endless belt by the heating element, and thereafter separating the object to be fixed having the image from the endless belt through a cooling step, wherein the object to be fixed is The image inside is formed using a toner in which the main component of the binder is a resin, and the toner has a softening point or melting point of 50 to 160 ° C. and a viscosity at a temperature of the softening point or higher. An image fixing device characterized by having a size of 10 to 10 ¹³ (centipoise), and in particular, a large energy saving is achieved by dividing a linear heating element into a plurality of parts. Combined with the fixing member The object to be fixed such as ruby or paper is not distorted and wrinkled, and the meandering of the object to be fixed due to this is prevented, and fixing failure and offset can be prevented, which enables stable image fixing. It is what has become.

The fixing of the toner image is generally carried out by heating the molten component of the toner, especially the binder resin, under pressure to fuse the toner image to the support. It is preferable to pressurize the toner image more strongly for good fusing to the support. For that purpose, the object to be fixed having the toner image on the support has a ridge-like pole in MD (paper passing direction). It is desirable to be continuously pressed one after another by a thin and heated pressurizing body. The "linear heating element" in the present specification is
Such a ridge-line extremely thin heated pressurizing body is meant, and does not mean a heating body such as a nichrome wire. Such a heating element can be heated by a known appropriate means such as resistance heating, induction heating, high frequency vibration heating, and laser heating. Specifically, for example, a thermal head is suitable. The linear heating element of the present invention is, for example, as shown in FIG. 1, dividedly arranged so as to traverse (TD) the traveling direction (MD) of the object to be fixed, and each divided heating element as a whole, Responsible for fixing the image of the entire fixed object. Each heating element is not heated unless an image is detected in its own area in the object to be fixed, and when an image is detected, only this image portion is heated by pulse energization to fix the image. For example, when a thermal head is used, the heating area of the thermal head can be divided into an extremely large number, so that image fixing can be performed by finer heating control. Further, the arrangement of the divided heating elements may be linear, but since each heating element of the present invention controls the heating timing individually based on the output of the image position detection sensor corresponding to each heating element. , May be displaced in the transverse direction.

The energizing pulse to be applied may have any shape such as a square wave, a triangular wave or a sine wave, and it is not necessary to completely turn it off between the pulses. In the pulse energization in the present invention, the energization pulse width or the number of energization pulses is reduced from the start to the end of fixing of the image area in one sheet to be fixed to fix the image area in one sheet to be fixed. By gradually lowering the energization energy from the start to the end of fixing, further energy saving is achieved, and by keeping the temperature of the heating element from rising too much, the temperature applied to the toner is made almost constant. It is possible to prevent occurrence of hot offset and abnormal gloss.

In practice, the ratio of the energization amount at the start of fixing and the end of fixing in the image area of one sheet of the fixing material is MD.
10: 9.5 to 10: 1 when converted to a length of 420 mm in the (sheet passing direction) (when the object to be fixed is fed and discharged in the long side direction of A3 size according to JIS P 0138) In that case, it is found that stable fixing is carried out. Considering the fluctuation of the use conditions, it is preferably 10: 8 to 10: 2, more preferably 10: 8 to 10: 3, and even more preferably 10: 7. It may be 10: 4, and it can be said that much energy saving is realized as compared with the conventional method. It should be noted that the energization amount (electric power amount) may be lowered continuously or stepwise, and may be gradually lowered. However, even with respect to these settings, there are some variations and variations due to use conditions, so that a cooling step after heating as in the present invention is also required.

Generally, the toner is fixed in a so-called "resin rubber state". As the temperature applied to the toner rises, the softening of the toner resin begins and the viscosity of the resin decreases. However, "rubber area condition" here
Is not the elastic restoring force when the force is released after the force is applied due to the deformation of the polymer material, but is rather a stress reduction factor (creep factor) exhibited by the material. The toner in the conventional fixing roller system has a high self-cohesive force because the viscosity of the resin is extremely high in the so-called rubber range from the softening state to the complete melting state, and the offset occurs in which a part of the toner adheres to the fixing roller. Rarely happens. However, in the completely melted state, the viscosity of the resin is remarkably reduced, and the self-aggregation force is reduced, and a phenomenon occurs in which some toner adheres to the fixing roller.

Generally, when a thermoplastic resin is heated, it is solid up to the softening point, and when it exceeds the softening point, it becomes soft and becomes viscous. When it is further heated, and when it exceeds the melting point, it becomes softer and becomes a viscous liquid state. However, the width of the temperature from the softening point to the melting point, the viscosity from the softening point to the melting point, and the viscosity above the melting point are different depending on the molecular weight of the resin, the molecular weight distribution, the crystallinity, the degree of crosslinking, the intermolecular force, and the like. . In the present invention, as long as the toner actually exhibits a melt viscosity of 10 to 10 ¹³ centipoise between the softening point and the melting point, it can be used even at a temperature equal to or higher than the softening point, and of course, the above melting at a temperature equal to or higher than the melting point. Any viscosity type can be used. Therefore, the "rubber region state" referred to here is not the elastic restoring force when the force is released after the force is applied due to the deformation of the polymer material, but rather the cause of the stress reduction (creep factor) indicated by the material. Is.

The low melt viscosity of the toner means that the inclination of the viscosity decrease in the rubber region is obviously remarkable, and in such a toner system, silicone oil or the like is applied to the roller surface in the conventional conventional heat roller fixing method. It cannot be used by any method other than coating due to the problem of hot offset. It should be noted that the method of applying oil or the like is ineffective if the viscosity is too low, and the method of applying oil is costly and disadvantageous to the user.

Therefore, in actual heat roller type fixing, fixing is performed within the viscosity range within the rubber range of the toner, but as described in JP-B-51-29825, the fixing member is pulled immediately after heat is applied. If the method of peeling from the member after cooling the toner without peeling off is used, the toner does not adhere to the fixing member even if the viscosity of the toner decreases when melted because the toner is peeled off after cooling and solidifying. It can be said that the margin is much higher than in the past. In the present invention, a heating element,
An endless belt suspended on this is provided with a pressurizing body that cooperates with the endless belt, and the image on the fixing object is heated by the heating element via the endless belt, and then a cooling step is performed to form an object having an image. By adopting a means for separating the fixed material from the endless belt, the softening point or melting point is 50 to 16
A toner having a viscosity of 0 ° C. and a melt viscosity of 10 to 10 ¹³ centipoise at a temperature equal to or higher than the softening point or the melting point can be used, and particularly, a toner having a low softening point or a low melting point, which is a low viscosity toner. Even if there is, it is possible to perform stable image fixing without causing offset or the like.
As a result, the fixing temperature can be lowered, and even if only the image portion in one sheet to be fixed is heated and fixed by each of the plurality of divided linear heating elements, the fixing member, paper, etc. Partial thermal expansion is suppressed to a minimum, distortion is hardly generated, and wrinkles and meandering can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an image fixing device having a heating and cooling structure according to the present invention. In the apparatus example of FIG. 1, a linear heating element, for example, a thermal head (H1), which is arranged so as to cross the running direction of the object to be fixed, is divided into a plurality of parts, and is individually controlled, and a guide. An endless belt (B) suspended on rollers (G1, G2, G3), energization control means (A1) for energizing each heating element (H1) with a pulse, and an image (P1) on a support (P2)
And a pressurizing body (P4) for sandwiching the object to be fixed (P3) provided above in cooperation with the endless belt (B). The pressure body (P4) in this example is composed of a conveyor belt (Cv) suspended between a pressure roller (G4) and a guide roller (G5).

Guide roller (G1) and guide roller (G
Any of 2) may be a driving roller and the other may be a roller, and either may be a roller for cooling. In this example, the endless belt (B ), The guide roller (G2) is a roller for cooling the image (P1) in the object to be fixed (P3) at the normal clockwise hand rotation direction, that is, the object to be fixed (P3) is conveyed from left to right. Has become. In the apparatus of FIG. 1, the guide roller (G2) also serving as the cooling means has a guide roller (G3) also serving as the fixing roller in order to obtain a sufficient cooling surface area.
In addition, the diameter is larger than that of the guide roller (G1) which also serves as a drive roller. In the present invention, this fixing device may be provided with other cooling means other than the guide roller (G2) or in place of the guide roller (G2). The image (P1) in the object to be fixed (P3) is heated by each heating element (H1) through the endless belt (B), and then, the image (P1) is subjected to a cooling process by a guide roller (G2) as a cooling unit. The object to be fixed (P3) having P2) is separated from the endless belt (B).

The control system in the fixing device of this example includes an energization control means (A1) for heating each of the divided heating elements (H1) including an energization switch means (not shown), and a guide roller (also serving as a drive roller). G1) has a control means (A2) for controlling the rotation of a pulse motor (M) for driving, and these control means (A1) and (A2) are used for the image (P1) in the fixing object (P3). ) Receives the image signal from the image position detection sensor (S) for monitoring the position of (1), and is controlled by the controller (B1) connected to the RAM (B2) and ROM (B3), and from the power supply (A3). Adjust the pulse energization amount of. In this case, the control system including the image position detection sensor and the like is provided corresponding to each of the divided heating elements, and one control system is provided for one heating element. Only when an image is detected in the area of the heat-fixing object which the heating element is responsible for, the heating element is heated by pulsed power supply to only this image portion, and the image is fixed. Further, the controller (B1) may be individually provided so as to correspond to each heating element, but only one controller may control the control system of each heating element. In addition, each heating element (H1)
A temperature sensor, for example, a thermistor (SM) is arranged in the device, and an output signal from the thermistor (SM) is transmitted to the control means (A1) for switching operation of an energization switch means (not shown) therein. Used for. In the case of the prior art, the energization heating for fixing the toner image does not necessarily have to be the pulse energization. For example, even if the voltage and / or current amount as the controlled amount is an analog amount, such an analog heating Although it is not impossible to use a digital signal as a control signal for controlling the controlled variable, not only the controlled variable but also the energized amount itself as the controlled variable is used as the pulse energized amount here. The advantages of such a control system are obvious to those skilled in the art, not to mention exhaustive talk.

FIG. 2 shows such energization control means (A1).
Energizing pulse for each heating element (H1) and each heating element (H1)
An example of the temperature change of 1) will be shown. First, the image portion (P1) in the object to be fixed (P3) among the heating elements (H1) is adjusted in accordance with the energization timing for fixing based on the output signal of the image position detection sensor (S). Before reaching one, the energizing period (C) of the energizing pulse or / and the energizing time per pulse (P) is increased to energize in the high energizing mode, as shown by the solid line graph in the figure. The heating elements (H1) are rapidly heated up. Each heating element (H1)
Is applied for one pulse or more. Since each heater (H1) is at a temperature at which the toner image can be melted and fixed when the image (P1) in the object to be fixed (P3) arrives, as shown by the one-dot chain line graph in the figure, Energizes the heating element (H1) with continuous and constant energizing pulse timing and energizing pulse width, and then the output signal of the position detection sensor (S) stops monitoring the image on the support (P2) and the output signal is The power supply control means (A1) stops the power supply to the heating element (H1) in accordance with the power supply disconnection timing based on the time when the low level is reached. Even if the energization is stopped, the temperature of the heating element (H1) is sufficiently high for a while, so that the fixing of a slight residual image is still executed. In this example, the low energization mode after the high energization mode is set to a constant pulse width and pulse density. However, as will be described later, it is possible to reduce the pulse width and / or the pulse density in the low energization mode. You may energize.

FIG. 3 shows the energization control means (A1) for applying an energization pulse to each heating element (H1) as a controller (B).
It is a block diagram showing an example of a control system for controlling by 1). In FIG. 3, one heating element is controlled by one controller, but it is also possible to control a plurality of heating elements by one controller, as described above. RAM (random access memory)
In (B2), a sequence program for sequence controlling the sensor (S), ROM (read only memory) (B3), control means (A1) and (A2) connected to the controller (B1) can be called and updated. Store and
Further, the level signal of the temperature sensor (SM) as the output of the inverter circuit (A12) and the cue driver unit (A1)
The program for interface with the pulse signal of 1) is stored so that it can be called and updated.

When the number of pulses of a series of energizing pulses is Nn, the energizing period is Cn, and the energizing time is Pn, these data (Nn, Cn, Pn) can be recalled to a ROM (read only memory) (B3) in advance. Stored and ROM
Data (Nn, Cn, Pn) is read by applying an address signal from the controller (B1) to (B3), and the register section (B4) and data latch section (B
Sequentially sent to 5). The register unit (B4) and the data latch unit (B5) are controlled by the controller (B1), the data Nn is sent to the N pulse counter unit (B6), and the data (Cn, Pn) is the energization time generation counter unit. It is sent to (B7).

The energization time generation counter section (B7) is
The energization time for one pulse is determined by the data (Cj, Pk), and the output data is input to the queue driver section (A11) of the energization control means (A1). The cue driver unit (A11) outputs a required energizing pulse in the order according to the energizing time data to drive each heating element (H1). At the same time, the N pulse counter section (B7) counts the number of outputs of energizing pulses, and sends a signal to the controller (B1) at the time when only the data Ni is counted.

As a result, the controller (B1) outputs the address signal of the next cycle and controls the register unit (B4) and the data latch unit (B5).
For example, in the present invention, Cn = 10 ms is constant,
When the temperature is raised, P ₀ = 9 ms and N ₀ = 30 can be set, and during constant temperature control, P ₁ = 2 ms and N ₁ = 213 to 215 can be set. The energization time and the number of pulses in each mode are set based on the data collected in advance.

Therefore, such energization control means (A
1) can be changed during the fixing process of each image (B1) in one sheet (B3) to be fixed. Also, in the figure,
The energization control means (A1) of each heat generating element (H1) represents the energization mode in which the energization period (C) of the energization pulse is high and the energization time per pulse (P) is large, and the following steady energization mode. However, when the heater (H1) as a heating element is excellent in heat insulating property with respect to the entire image in one sheet (B3) to be fixed, the heating temperature gradually rises with time. Therefore, it is desirable to reduce the energization pulse width and / or energization pulse density per unit time to each heating element (H1) from the start of heating to the end of heating in the fixing process.

The energization control means (A
1) does not energize each heating element (H1) until the leading edge of the image (P1) portion in the fixed object (P3) reaches the position of each heating element (H1), and also energizes Control means (A
1) shows the image (P1) even before the rear end of the support (2) having the image (P1) has finished passing through the heating element position.
It is also possible to finish the passage of the heating element position and stop the energization.

FIG. 4 relates to the example of the fixing device of the present invention described above, and shows the means for starting, stopping and switching the energization of each heating element (H1) controlled by the energization fine adjustment means in the apparatus. An example of a control circuit is shown. In this example, the transistor (TR11) and the transistor (TR12) form a self-propelled multivibrator for each heating element (H1).
2) are alternately conducted, and the primary coil of the transformer (L
11) A high voltage secondary induction output corresponding to the alternating input to 11) is obtained in the secondary coil (L21), and this is used as a power source for each heating element (H1) having resistors (R1) and (R11) as a load. By doing so, the energization start, stop and switching means at the time of pulse energization heating are performed, and the control of this self-propelled multivibrator circuit is performed by the transistor (TR).
1), a resistor (Rx), and the thermistor (SM) of the temperature sensor shown in FIG. 1, which is a feedback circuit that has a negative input / output relationship with respect to the load fluctuation of the self-propelled multivibrator circuit.

In this self-propelled multivibrator, when one transistor, for example (TR11), is turned on, the primary coil (L11) of the transformer is energized, and as a result, the secondary coil (L21) is slightly delayed. The secondary induction output is obtained, and this is used as the heater source.
The coil (L11) also obtains a third-order inductive output that is generated after some time, and the third-order output obtained after this time is fed back to the other transistor (TR12) to make it conductive. Thus, in the case of the transistor (TR12), the same operation as in the case of the transistor (TR11) is performed, and thereafter, this operation is alternately repeated to form a multivibrator. The capacitor (C1) is for cooperating with the coil (L11) in the circuit to determine the conduction time constant of both transistors (that is, pulse energization frequency), and of course the power supply of this circuit is a rectifier (D). ) From the DC component.

Therefore, this self-propelled multi-vibrator determines the upper limit temperature and the lower limit temperature of the heater (H1) in the fixing device of the present invention. As a result, the control means (A1) in FIG. It determines the temperature control range. The push-pull type switch (SW) is
The heater (H1) can be switched between a high heating value (R1 + R2) and a low heating value (R2 only).

Furthermore, it is possible to combine the known means for protecting the circuit elements from surge voltage, for example, the resistor (R3) part for the rectifier (D) from the sudden overvoltage flow to the rectifier ( In order to protect D), an overcurrent bypass path can be provided by arranging a Zener diode that conducts when the Zener breakdown voltage is reached in parallel with the resistor (R3) + rectifier (D). In the case of this circuit device, there is not only the advantage of being a pulse output, but also the advantage of not including a general counter electromotive force absorption circuit having a high time constant such as a diode and a resistor.

As shown in FIG. 5, it goes without saying that each heating element (H1) is heated to a high temperature (R11 + R22) and a medium temperature (R1).
11 + R32) and low temperature (only R11) can be switched to three stages of temperature, and further, for example, five stages of temperature can be switched.

FIG. 6 shows another example of the control circuit as a means for starting, stopping and switching energization for each heating element (H1) in relation to the fixing device of the present invention. Also in this case, the load (R1) of each heating element (H1) is only (R11) in the case of low temperature heating and (R11 + R) in the case of high temperature heating.
12) and the temperature switching means (7) is shown as an electrical switch (SW). In the example of this figure, the energization amount opening / closing and switching means of the line of each heating element (H1) is composed of an energizing circuit controller (CR) and a transistor (T).
R) and the energizing circuit controller (CR) is composed of an electromagnetic switch (X) capable of opening and closing the relay by operating the electromagnetic coil (MC) of the relay, and the transistor (TR).
Amplifies the output from a temperature sensor such as a thermistor (SM) to drive the electromagnetic switch (X). The output signal goes through the temperature sensor (SM) and the transistor (T
When it enters the base electrode of R), the transistor (TR) becomes conductive and excites the electromagnetic switch (X). The circuit composed of the diode (D) and the resistor (Rx2) in this example protects the circuit by absorbing the counter electromotive force generated when the electromagnetic switch (X) is cut off. Further, the rectifier (D) is a power source of the energization amount adjusting means including the energizing circuit controller (CR) and the transistor (TR). There is.

FIG. 7 shows another form of the fixing device of the present invention. In the apparatus of FIG. 1, the endless belt (B) is suspended and driven by each guide roller,
As shown in FIG. 7, the endless belt (B) is connected to the linear heating element (H
1) and the pressure roller (G4) may be nipped, and the object to be fixed (P3) may be conveyed by being driven by friction of the roller.

[0034]

The present invention will be described in more detail with reference to the following examples. Note that the integrated waveforms shown in the following examples are as shown in FIG.
The output of the pulse is integrated and treated as one waveform.

(Embodiment 1) FIG. 9 shows a fixing device using a thermal head in which the thermal head is divided into four parts.
Based on the output of the corresponding image position detection sensor, how much energy can be saved by actually passing the image when pulsed electricity is applied to each divided thermal head so as to heat only the image part that it owns It is the figure which showed. In FIG. 9-represents the image on the paper,
In the figure, (A), (B), (C), and (D) show the states of the pulse integral waveform when the paper passes through the thermal heads (A), (B), (C), and (D). It represents. According to this, when the thermal head is divided into four, for example,
In the case of the image of, the energization amount for the D part is sufficient, but when not divided, (A), (B), (C)
An energizing amount corresponding to the part is required. According to the invention,
It is clear that the thermal head in the non-image part cuts the energization by 10% or more, and further energy saving is achieved.

(Embodiment 2) FIG. 10 is a diagram showing how much energy can be saved by actually passing an image through the paper when the energizing pulse width and pulse density by the heating element are reduced in fixing. is there. In FIG. 10, symbols (-) represent images on paper, and (I), (II), (III), (IV) in the figure.
Shows the pulse integration value and the temperature change of the heating element when the paper passes through the thermal head. (I),
In (II), the pulse width density is a constant value, and the temperature of the heating element rises with time. On the other hand, (III),
(IV) When the pulse width or pulse density is variable,
The integrated value of the pulse decreases with time, but the temperature shows an almost constant temperature because there is heat accumulation although there is an overshoot at the beginning. Also, in this example, the pulse is turned off until the first image arrives, and the pulse is turned off when the image disappears completely,
All the thermal heads continue to be energized between the first image and the rearmost image. Since the energy consumption corresponds to the integrated value of the pulse, energy saving can be achieved by the amount of the symbol Q in the figure, and the energy saving effect of the present invention is clear.

[0037]

As is apparent from the detailed and specific description above, according to the present invention, in addition to achieving significant energy saving, the fixing member or the member to be fixed such as paper is not distorted or wrinkled. There is an extremely excellent effect that an image fixing device can be provided which can prevent meandering of the object to be fixed and the like and can realize stable fixing without causing offset or the like.

[Brief description of drawings]

FIG. 1 shows an example of an image fixing device having a heating and cooling structure according to the present invention.

FIG. 2 shows an example of an energization pulse for the heating element of the heating energization control means and a temperature change of the heating element in the present invention.

FIG. 3 is a block diagram showing an example of a control system for controlling heating energization control means in the present invention by a controller.

FIG. 4 shows an example of a control circuit as an energization start, stop and switching means for a heating element controlled by a heating energization control means in the present invention.

[Fig. 5] High temperature, medium temperature, and low temperature of the heating element in the present invention
It is a figure which shows switching to the temperature of a step.

FIG. 6 shows another example of the control circuit as the energization start, stop and switching means for the heating element in the present invention.

FIG. 7 shows another example of the image fixing device according to the present invention.

FIG. 8 is a diagram showing the relationship between the pulse output applied by the heater (H1) and the heat distribution of the guide roller (G1) in the present invention.

FIG. 9 is a diagram showing a relationship of heat distribution of an integrated waveform of a guide roller (G1).

FIG. 10 shows the influence of each image (I), (II), (III), and (IV) on the heat distribution of the integrated waveform of the guide roller (G1) when the heating element (heater) in the present invention is rod-shaped. FIG. 4 is a diagram showing how the present invention can save energy by passing an image.

[Explanation of symbols]

A1 energization control means A11 Cue driver section A12 inverter circuit A2 Motor control means A3 power supply B endless belt B1 controller B1 controller B1 controller B2 RAM B3 ROM B4 register section B5 Data latch section B6 N pulse counter B7 Energization time creation counter section C energization cycle C1 capacitor CR energizing circuit controller Cv conveyor belt D full wave rectifier G1 guide roller (drive roller) G2 guide roller G3 guide roller (fixing roller) G4 pressure roller G5 guide roller H1 heating element L11 primary coil L21 secondary coil M drive motor MC electromagnetic coil N energizing pulse number P energizing time P1 image P2 support P3 Fixed object P4 Pressurized body Q Energy saving R1 resistance R11 resistance R3 resistance Rx resistance Rx2 resistance S image position sensor SM thermistor SW power switch TR transistor TR1 transistor TR11 transistor TR12 transistor X electromagnetic switch

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 3/00 335 H05B 3/00 335 F term (reference) 2H005 EA03 FB01 2H033 AA09 AA14 AA15 AA32 BA25 BA27 BA58 BE03 CA01 CA22 CA30 CA44 CA45 CA48 3K058 AA65 AA88 BA18 CA12 CA15 CA22 CB07 CB18 CB19 DA06

Claims (10)

[Claims] 1. A linear heating element divided into a plurality of parts, means for energizing each of the heating elements in a pulsed manner, and a pressure element for sandwiching an object to be fixed having an image in cooperation with an endless belt. A heating device heats an image in an object to be fixed through an endless belt, and then a cooling device separates the object to be fixed having an image from the endless belt. The image is formed using a toner whose main component of the binder is a resin, the toner has a softening point or melting point of 50 to 160 ° C., and a viscosity of 10 to 10 at a temperature equal to or higher than the softening point or the melting point. An image fixing device characterized in that it is 10 ¹³ (centipoise). 2. The fixing device according to claim 1, wherein the linear heating element is divided into two or more parts. 3. The image fixing device according to claim 1, wherein an energization pulse width for each of the divided heating elements is changed within an image in one sheet of the fixing object. 4. The image fixing apparatus according to claim 1, wherein the energization pulse density per unit time for each of the divided heating elements is changed within an image in one sheet of the fixing object. 5. The method according to claim 1, wherein an energizing pulse width for each divided heating element and a pulse density per unit time are changed in combination within an image in one sheet of the fixing material. The image fixing device described. 6. The energization pulse width or the number of energization pulses for each of the divided heating elements is decreased from the start of fixing to the end of fixing in an image in one sheet of the object to be fixed. 5. The image fixing device according to any one of 5. 7. The ratio of the change in the energization amount at the start of heating and the end of heating for each of the divided heating elements is M
10: 9.5 to 10: in terms of D (sheet passing direction) having a length of 420 mm (when the object to be fixed is fed and discharged in the long side direction of A3 size according to JIS P 0138). 6. The image fixing device according to claim 2, wherein the image fixing device is 1. 8. The fixing device according to claim 1, wherein one pulse or more is applied before the leading edge of the image reaches the heating element portion at the timing of starting energization. 9. The divided heating element generates heat only at a portion corresponding to an image portion.
9. The fixing device according to any one of 1 to 8. 10. The fixing device according to claim 1, wherein each of the divided heating elements cuts the energization of the head by 10% or more in the non-image portion.