JP2001257055A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance heating device and an image forming device that can prevent lowering of throughput due to the difference of size of the sheet material and that enables to obtain good fixation. SOLUTION: The ceramic heater 10a comprises a main heat generation body 32 and a auxiliary heat generation body 32a, 32b on a straight line to the width direction nearly perpendicular to the passing direction of the sheet material, and a thermistor 10b is installed on the main heat generation body 32 portion provided in the area where the smallest width sheet material passes, and a MPU40 is installed which supplies electricity to the heat generation body provided in the area where the sheet material passes which is detected by the cassette sized sensor 4 according to the detection result of the thermistor.

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 having a function of forming an image on a sheet material (a material to be heated), such as a copying machine, a printer, or a facsimile machine. The present invention relates to a heating device for fusing and fixing the upper toner image.

[0002]

2. Description of the Related Art Conventionally, as a heating device applied to this type of image forming apparatus, for example, a heat fixing device using a ceramic heater is disclosed in Japanese Patent Application Laid-Open No. 63-313182.

The fixing nip portion is formed by sandwiching a heat-resistant film between a plate-shaped ceramic heater and a pressing roller as a pressing member. The recording paper on which the unfixed toner image is formed and carried is introduced between the pressure roller and the heat-resistant film, and the heat of the ceramic heater is transferred to the recording paper via the heat-resistant film. And heats the toner image to fix the toner image on recording paper.

[0004] The ceramic heater has a resistor (heating element) pattern formed on an insulating substrate such as alumina or aluminum nitride, and generates heat by passing an electric current through the resistor pattern.

Further, one resistor is formed on the insulating substrate so as to correspond to an area substantially equal to the maximum sheet passing width which the image recording apparatus can pass, or a plurality of kinds of sheet passing widths which can pass the sheet. Are formed in parallel in the paper passing direction.

[0006]

However, in the case of the above-described prior art, the following problems have occurred.

In the prior art, when the heating element of the ceramic heater is one having a length corresponding to the maximum sheet passing width,
If recording paper with a width narrower than that of the heating element is passed, the temperature of the heating area and the non-paper passing area may abnormally rise. This causes a decrease in performance.

Further, in the case of a ceramic heater corresponding to a plurality of paper passing widths and having heating elements arranged in parallel, a reduction in throughput is prevented by switching the heating elements to be energized according to the paper size.

However, since the position of the heating element corresponding to each size in the paper passing direction changes in the nip, there is a problem that the fixing performance changes for each size of recording paper.

There is another problem that the number of heating elements is limited by the nip width.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to prevent a decrease in throughput due to the size of a sheet material and obtain a good fixing property. Another object of the present invention is to provide a high-performance heating apparatus and an image forming apparatus.

[0012]

According to the present invention, there is provided a heating member having a heating means, a temperature detecting means for detecting a temperature of the heating means by a temperature detecting unit, and Size detection means for detecting the size of the heating material,
In the heating device that passes the material to be heated while being in contact with the heating member, and applies heat energy, the heat generating unit is arranged on a straight line in a width direction substantially orthogonal to a passing direction of the material to be heated. A plurality of heating elements, wherein the temperature detection unit of the temperature detection means is a first heating element disposed in an area through which the first material to be heated in the width direction passes among the plurality of heating elements. A power supply unit that is provided in the body part and supplies power to a heating element disposed in an area through which the material to be heated detected by the size detection unit passes according to a detection result of the temperature detection unit. It is characterized by.

The heating means includes a first heating element provided in a passage area of the first heated material and a second heated material having a width direction larger than that of the first heated material; A second heating element provided outside the passage area of the first heated material and in the passage area of the second heated material;
It is also preferable that when the size detecting means detects the second material to be heated, the power supply means supplies a predetermined ratio of power to the first and second heating elements.

It is preferable that at least one second heating element is provided according to the size of the material to be heated in the width direction.

The first heating element is provided at the center of the heating means, and the second heating element is provided on both sides of the first heating element. It is also preferred that the centers substantially coincide.

It is also preferable that at the boundary between the plurality of heating elements, adjacent heating elements overlap in the direction in which the material to be heated passes.

The material to be heated is a sheet material on which an unfixed image is formed and carried by the image forming unit. An image forming apparatus for heating and fixing the unfixed image of the sheet material is provided with the heating device described above. Features.

[0018]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, the shape, and the relative arrangement thereof should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions, and are not intended to limit the scope of the invention to the following embodiments.

(Embodiment 1) FIG. 1 is a cross-sectional view for explaining a configuration of an image forming apparatus according to an embodiment of the present invention, and shows, for example, a case of a laser printer. Hereinafter, the configuration and operation will be described.

A laser printer main body 1 (hereinafter referred to as main body 1) has a cassette 2 for storing recording paper S as a sheet material (a material to be heated), and a cassette for detecting the presence or absence of the recording paper S in the cassette 2. Paper presence / absence sensor 3, cassette size sensor 4 (comprising a plurality of microswitches) as size detection means for detecting the size of recording paper S in cassette 2, paper feed roller 5 for feeding out recording paper S from cassette 2
Etc. are provided.

The recording paper S is located downstream of the paper feed roller 5.
And a pair of paper feed transport rollers 6 for transporting the paper. A paper feed sensor 7 is provided downstream of the paper feed roller pair 6 to detect the conveyance state of the fed recording paper. The paper feed sensor 7 is provided on the recording paper S based on a laser beam from the laser scanner unit 8. Is provided with an image forming unit 9 for forming a toner image.

Further, a fixing device 10 as a heating device for thermally fixing the toner image formed on the recording paper S is provided downstream of the image forming unit 9, and a sheet discharging unit is provided downstream of the fixing device 10. A paper discharge sensor 11 for detecting the paper transport state, a paper discharge roller 12 for discharging the recording paper S, and a loading tray 13 for loading the recording paper S on which recording has been completed.

The laser scanner unit 8 is provided with an image signal (image signal VDO) sent from an external device 30 described later.
A laser unit 14 that emits a laser beam modulated on the basis of a laser beam, a polygon motor 15 for scanning the laser beam from the laser unit 14 onto a photosensitive drum 18, which will be described later, an imaging lens group 16, a folding mirror 17, and the like. It is configured.

The image forming section 9 includes a photosensitive drum 18 and a primary charging roller 1 which require a known electrophotographic process.
9, a developing unit 20, a transfer charging roller 21, a cleaner 22, and the like.

The fixing device 10 includes a ceramic heater 10a as a heating means, a thermistor 10b as a temperature detecting means for detecting the temperature, and a ceramic heater 10a.
And a polyimide film 10c (heating member) that includes the thermistor 10b and rotates together with the conveyance of the recording paper, a ceramic heater 10a, a stay 10d (heating member) that holds the thermistor 10b and the polyimide film 10c,
The pressure roller 10e is in pressure contact with the ceramic heater 10a via the polyimide film 10c.

The main motor 23 is connected to the paper feed roller 5.
Is supplied with a driving force via a paper feed roller clutch 24. Further, each unit of the image forming section 9 including the paper feed / conveyance roller pair 6, the photosensitive drum 18, the fixing device 10, and the paper discharge roller 12
It also gives the driving force.

Reference numeral 26 denotes a printer control device for controlling the main body 1, which comprises an MPU (microcomputer) having a timer, a ROM, a RAM, etc., and various input / output control circuits.

The printer controller 26 is connected to a video controller 28 via a video interface 27 which is an internal communication means. The video controller 28 is connected to an external device such as a personal computer via a general-purpose interface 29 such as a Centronics interface. 30.

The video controller 28 converts image information transmitted from the external device 30 via the general-purpose interface 29 into a video signal, and transmits the video signal to the printer controller 26 via the video interface 27.

FIG. 2 is a diagram showing the details of the ceramic heater 10a, and A is a diagram viewed from above from the stay 10d side.
B is a sectional view.

The ceramic heater 10a includes a main heating element 32 as a first heating element and a sub-heating element as a second heating element formed by paste printing on the surface of a ceramic insulating substrate 31 such as alumina or aluminum nitride. The main heating element 32 and the sub-heating element 33 are provided on the same line in a direction orthogonal to the sheet passing direction.

The main heating element 32 is disposed in a small-size sheet passing area at the center of the ceramic heater, and has a conductor pattern 32a,
32b are connected to the electrode portions 32c and 32d, respectively.

The sub-heating elements 33 are disposed in the maximum size sheet passing area excluding the main heating element areas at both ends of the main heating element 32.
3a and 33b, which are two heating elements,
a and 33b are connected by a conductor 33c, and the other of the sub-heating elements 33a is connected to the electrode portion 3 via a conductor pattern 33d.
2c, and the other of the sub-heating elements 33b is connected to the electrode section 33f via the conductor pattern 33e. The electrode portion 32c is connected to both the main heating element 32 and the sub-heating element 33 and serves as a common electrode.

The thermistor 35 (thermistor 1 described with reference to FIG. 1) as a temperature detecting means for detecting the temperature of the main heating element 32 of the ceramic heater 10a on the protective layer 34.
0b).

The driving circuit of the ceramic heater of FIG. 2 will be described below with reference to FIG.

Reference numeral 40 denotes a microprocessor (hereinafter referred to as MPU) (power supply means) in the printer control device 26, which includes a ROM, a RAM, a timer, and the like.

The MPU 40 has ports P0, P0 as output terminals.
A that converts P1 and an analog voltage into a digital value for detection
It has an analog input terminal AN0 having a / D function. 41 is a commercial AC power supply.

One end of the main heating element 32 and one end of the sub-heating element 33a are connected to a commercial power supply 41 via a common electrode 32c. The other end of the main heating element 32 is connected to a commercial power supply 41 through a heater driver circuit 42 via an electrode section 32d.

The heater driver circuit 42 includes a triac 42a, a phototriac coupler 42b having a built-in zero-cross function, a transistor 42c, and a resistor 42.
d, 42e and 42f.

The T1 terminal of the triac 42a is connected to the commercial power supply 41, the T2 terminal is connected to the main heating element 32 via the electrode portion 32d, and the base of the transistor 42c is connected to the port P0 of the MPU 40. .

When the MPU 40 sets PA0 to "H", the transistor 42c is turned on, the LED inside the phototriac coupler 42b is driven, the triac inside the phototriac is turned on, and then the triac 4 is turned on.
2a is turned on, the commercial power supply voltage is applied to the main heating element 32, and heat generation is started.

Similarly, one end of the sub-heating element 33b is connected to a commercial power supply 41 through a heater driver circuit 43 via an electrode section 33f. Heater driver circuit 43
Are a triac 43a, a phototriac coupler 43b having a built-in zero-cross function, a transistor 43c,
And resistors 43d, 43e and 43f.

The T1 terminal of the triac 43a is connected to the commercial power supply 41, the T2 terminal is connected to the auxiliary heating element 33b via the electrode portion 33f, and the transistor 43c
Is connected to the port P1 of the MPU 40.

When the MPU 40 sets PA1 to "H", the transistor 43c is turned on, the LED inside the phototriac coupler 43b is driven, the triac inside the phototriac is turned on, and then the triac 4 is turned on.
3a is turned on, the commercial power supply voltage is applied to the sub-heating elements 33a, 33b, and heat generation is started.

One of the thermistors 35 is connected to GND, and the other is connected to the pull-up resistor 44 and the analog input port AN0 of the MPU 40, whereby the MPU 40 detects the temperature of the ceramic heater.

In the above-described configuration, the MPU 40 causes only the main heating element 32 to generate heat during small-size sheet passing, and
Since the control is performed such that the temperature of the sheet 5 becomes a predetermined temperature, the temperature of the non-sheet passing portion does not rise excessively, and there is no need to lower the throughput of the sheet passing.

When a sheet of a size between the small size and the maximum size is passed, the main heating element 32 and the sub-heating elements 33a,
Control is performed so that the thermistor 35 is heated to a predetermined temperature by causing both of them to generate heat.

Here, the main heating element 32 and the sub-heating element 33
Since a and 33b generate heat at the same time or generate heat at a predetermined ratio, it is possible to control the temperature based on information of one thermistor 35 in the main heating element 32.

The main heating element 32 and the sub-heating elements 33a,
Since 33b exists on the same line in the direction perpendicular to the sheet passing direction, uniform fixing performance can be obtained regardless of whether the size is small or large.

(Embodiment 2) Embodiment 2 will be described below. The difference between the present embodiment and the first embodiment lies in the difference in the shape of the main heating element 32 and the sub-heating elements 33a and 33b.

FIG. 4 is a view of the ceramic heater 31 in the present embodiment as viewed from the stay 10d side. In the same figure, the boundary between the main heating element 32 and the sub-heating elements 33a and 33b (portions C and D in the figure) has a shape in which the respective heating elements overlap in the sheet passing direction. I have.

[0052] This overlap makes it possible to eliminate the non-heat-generating portion at the boundary portion, and to secure better fixability at the boundary portion.

Embodiment 3 Hereinafter, Embodiment 3 will be described. The difference between the present embodiment and the first embodiment is that the main heating element 32 and the sub-heating elements 33a and 33b
The second sub-heating elements 36a and 36b are provided.

FIG. 5 is a view of the ceramic heater 31 in the present embodiment as viewed from the stay 10d side.

As shown, in the present embodiment, the main heating element 3
2 and the second sub-heating element 3 between the sub-heating elements 33a and 33b.
6a and 36b are provided, and the second sub-heating element 36
a and 36b are connected by a conductor pattern 36c, and the other of the second sub-heating elements 36a is connected to the conductor pattern 36c.
d, the second sub-heating element 3
6b is connected to the electrode portion 36 via the conductor pattern 36e.
f. The area from end to end of the second sub-heating element is a medium-size sheet passing area.

FIG. 6 shows a driving circuit of the ceramic heater of FIG. The difference between FIG. 6 and FIG. 3 is that P2 is added to the heater driver circuit 46 and the output terminal of the MPU 40 for supplying power to the second sub-heating element. Hereinafter, the additional portion will be described.

One end of the second sub-heating element 36a is connected to the common electrode 3
It is connected to the commercial power supply 41 via 2c. And
One end of the second sub-heating element 36b is connected via an electrode portion 36f,
It is connected to the commercial power supply 41 through the heater driver circuit 46.

The heater driver circuit 46 includes a triac 46a, a phototriac coupler 46b having a built-in zero-cross function, a transistor 46c, and a resistor 46.
d, 46e, and 46f.

The T1 terminal of the triac 46a is connected to the commercial power supply 41, the T2 terminal is connected to the sub-heating element 36b via the electrode 36f, and the transistor 46c
Is connected to the port P2 of the MPU 40.

When the MPU 40 sets PA2 to "H", the transistor 46c is turned on, the LED inside the phototriac coupler 46b is driven, the triac inside the phototriac is turned on, and then the triac 4 is turned on.
6a is turned on, the commercial power supply voltage is applied to the sub-heating elements 36a, 36b, and heat generation is started.

In the above-described configuration, the MPU 40 causes only the main heating element 32 to generate heat during small-size sheet passing, and
Since the control is performed such that the temperature of the sheet 5 becomes a predetermined temperature, the temperature of the non-sheet passing portion does not rise excessively, and there is no need to lower the throughput of the sheet passing.

When passing a sheet between a small size and a medium size, the main heating element 32 and the second sub-heating element 36 are used.
Both a and b are heated so that the thermistor 35 is controlled to a predetermined temperature.

When the medium is passed through the medium size or larger, the main heating element 32 and the second sub heating element 36a,
36b and the sub-heating elements 33a, 33b are heated to control the thermistor 35 to a predetermined temperature.

Here, the main heating element 32 and the sub-heating element 33
Since the a and 33b and the second sub-heating elements 36a and 36b generate heat at the same time or generate heat at a predetermined ratio, temperature control based on information of one thermistor 35 in the main heating element 32 can be performed. It is possible.

The main heating element 32 and the sub-heating elements 33a, 3a
3b and the second sub-heating elements 36a, 36b are on the same line in a direction perpendicular to the sheet passing direction, so that they have a small size.
Uniform fixing performance can be obtained for both medium and large sizes.

[0066]

The present invention has the above-described structure and operation. Among the plurality of heating elements arranged in a straight line in the width direction substantially perpendicular to the passing direction of the material to be heated, the heating element is detected by the size detecting means. The power supply means for supplying power to the heating element disposed in the area where the material to be heated passes prevents a decrease in throughput due to the size of the material to be heated, and does not cause a difference in fixing performance. This makes it possible to provide a high-performance heating apparatus and an image forming apparatus with high reliability.

The first heating element is provided at the center of the heating means, and the second heating element is provided on both sides of the first heating element. Are substantially the same, so that it is possible to obtain an excellent fixing property in correspondence with an apparatus that performs conveyance with reference to the center of the material to be heated.

Further, at the boundary between the plurality of heating elements, the adjacent heating elements overlap in the direction in which the material to be heated passes, so that the fixing performance at the boundary between the heating elements can be improved.

Further, there is no longer any limitation on the number of heating elements due to the nip width as in the prior art, and a plurality of heating elements can be provided in a straight line in the width direction in accordance with the size of the material to be heated. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram of a ceramic heater according to Embodiment 1 of the present invention.

FIG. 3 is a circuit diagram illustrating a ceramic heater drive circuit according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a ceramic heater according to Embodiment 2 of the present invention.

FIG. 5 is a schematic diagram of a ceramic heater according to Embodiment 3 of the present invention.

FIG. 6 is a circuit diagram illustrating a drive circuit for a ceramic heater according to a third embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 laser printer main body 4 cassette size sensor 9 image forming unit 10 fixing device 10a, 31 ceramic heater 10b, 35 thermistor 10c polyimide film 10d stay 26 printer control device 31 insulating substrate 32 main heating element 32a, 32b, 33c, 33d, 33e conductive Body pattern 32c, 32d, 33f Electrode part 33 (33a, 33b) Sub-heating element 34 Protective layer 40 MPU

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 AA02 AA20 BA25 BA27 BA31 BA32 BE03 CA04 CA07 CA17 CA30 CA46 3K058 AA87 BA18 CA23 CA61 CA91 CB02 CE04 CE13 CE19 DA04 DA06 GA06 5H323 AA35 BB17 CA06 CB02 CB42 DB04 FF04 MM04 NN03

Claims (6)

[Claims] A heating member having a heating unit; a temperature detection unit for detecting a temperature of the heating unit with a temperature detection unit; and a size detection unit for detecting a size of a material to be heated. A heating device that passes a material to be heated while making contact with the material, and applies thermal energy, wherein the heating unit includes a plurality of heating elements arranged in a straight line in a width direction substantially orthogonal to a direction in which the material to be heated passes. The temperature detecting unit of the temperature detecting unit is provided in a first heating element disposed in an area through which the first material to be heated in the width direction passes, among the plurality of heating elements, A heating device, comprising: a power supply unit that supplies power to a heating element disposed in an area through which a material to be heated detected by the size detection unit passes according to a detection result of the temperature detection unit. . 2. The heat generating means includes: a first heating element provided in a passage area of the first heated material and a second heated material having a width direction larger than that of the first heated material; The first
And a second heating element provided outside the passage area of the material to be heated and in the passage area of the second material to be heated, and the size detecting means removes the second material to be heated. The power supply means supplies a predetermined ratio of power to the first and second heating elements when the power is detected.
A heating device according to claim 1. 3. The heating apparatus according to claim 2, wherein at least one second heating element is provided according to the size of the material to be heated in the width direction. 4. The first heating element is provided at a central portion of the heating means, and the second heating element is provided on both sides of the first heating element. The center of the wood is
The heating device according to claim 2, wherein the heating devices substantially coincide with each other. 5. The heating device according to claim 1, wherein adjacent heating elements overlap at a boundary between the plurality of heating elements in a direction in which the material to be heated passes. apparatus. 6. The image forming apparatus according to claim 1, wherein the material to be heated is a sheet material on which an unfixed image is formed and carried by an image forming unit, and wherein the unfixed image of the sheet material is heated and fixed. An image forming apparatus comprising the heating device according to claim 1.