JP2001093653A - Heater device and image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heater device and image-forming device capable of preventing the delay of sensing the temperature of the heater and reducing the lowering in the measured temperature by insulating a heat generator of a ceramic heater and a temperature sensing element abutting against a non- heating side of the ceramic heater. SOLUTION: This heating device has a heating means, consisting of a ceramic heater for heating an article to be heated by way of a ceramic board material 102, having a heat generator 103 driven by a primary circuit on the non-heating side opposite to the heating side of the ceramic board material 102, facing the article to be heated and temperature sensing element constituting a part of a secondary circuit detecting the temperature of the ceramic heater. As an insulating means for insulating the primary circuit and the secondary circuit, a superior heat conductive insulating material layer 104 is mounted only in the part in contact with the temperature sensing element on the non-heating side of the ceramic heater, making the temperature sensing element abut against the insulating material layer 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus and an image forming apparatus, and more particularly, to an insulating means between a ceramic heater of a primary circuit and a temperature detecting element of a secondary circuit in the apparatus.

[0002]

2. Description of the Related Art A heating method in a fixing device (heating device) of an image forming apparatus for forming a toner image on a recording material and fixing the toner image by heating and pressurizing includes a method of heating with a halogen heater. And a method of heating with a ceramic heater. The ceramic heater method has a feature that the time required for the heater to reach the fixing temperature is earlier than that of the halogen heater.

FIG. 14 is a sectional view of a fixing unit 9 of the ceramic heater type provided in such an image forming apparatus. In FIG. 14, reference numeral 32 denotes a ceramic heater. The ceramic heater 32 includes a ceramic substrate 33 and a heating element 34.
And the thermistor 35. The heating element 34 is configured to be located on the fixing surface. Reference numeral 36 denotes a film for preventing the toner images 42 and 43 from reaching the ceramic heater 32. The film 36 has a cylindrical shape. The ceramic heater 32 indirectly heats the toner 42 before fixing via the film 36. 37 is a ceramic heater 32
The film guide plays a role of supporting the film and supporting the film in a cylindrical shape. Reference numeral 38 denotes a stay for supporting the film in a cylindrical shape. The pressure roller 10 includes a shaft 39, rubber 40, and a tube 41.

In the fixing device 9 immediately before the recording paper 28 on which the transfer toner image 42 is placed is conveyed, the temperature of the ceramic heater 32 is adjusted. At this time, the pressure roller 10 and the film 36 are rotating in the directions of the arrows.

The transfer toner image 42 conveyed together with the recording paper 28 is heated and pressed by the film 36 and the pressure roller 10 to become a fixed toner image 43.

Next, FIG. 15 shows a fixing surface and a non-fixing surface of the ceramic heater 32. FIG. FIG. 15A is a diagram of a fixing surface of the ceramic heater 32. The fixing surface is formed on a ceramic substrate 33 on a heating element 34 and conductors 44 and 4.
5, 46, a glass 47, a through hole 48 and the like are formed. The conductor 45 is a contact portion with the AC connector. The conductor 44 is an AC wiring pattern that connects the AC connector contact portion 45 and the heating element 34. The conductor 46 is D
This is a contact portion with the C connector. DC connector contact section 46
Is connected to the back surface through the through hole 48. Glass 4
Reference numeral 7 serves to insulate the heating element 34.

FIG. 5B is a view of the non-fixed surface of the ceramic heater 32. On the non-fixing surface, a thermistor 35, a DC conductive pattern 49, a through hole 48, and the like are formed on a ceramic substrate 31.

[0008]

A conventional ceramic heater using alumina as a ceramic substrate has a heating element 34 on a fixing surface (heating surface) as shown in FIG. 15, and a temperature detecting element as a secondary circuit. Has detected the temperature via a ceramic substrate (0.6 mm thick) which is an insulator. Therefore, the insulation between the ceramic heater as the primary circuit and the temperature detection circuit as the secondary circuit was sufficient.

The present invention relates to a problem that occurs in a configuration in which a heating element is arranged on a non-fixing surface (a back surface of a fixing surface) of a ceramic heater.

A conventional ceramic heater has a configuration in which heat generated by a heating element is transmitted to recording paper via a glass protective layer.

However, the thermal conductivity of ceramic is smaller than that of glass. When a material having a large difference is selected, the thermal resistance of the ceramic substrate becomes smaller than the thermal resistance of the glass protective layer. As a method of efficiently utilizing the heat generated by the heating element for fixing by utilizing this characteristic, there is a method of disposing the heating element on the back surface of the fixing surface. In this method, both the ceramic heater as the primary circuit and the temperature detection circuit as the secondary circuit are provided on the non-fixing surface, so that there is a problem of insulation between the primary and the secondary. Further, it is necessary to transmit the temperature of the ceramic heater to the temperature detecting element as correctly and quickly as possible.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the temperature of a heater by insulating a heating element of a ceramic heater and a temperature detecting element in contact with a non-heating surface of the ceramic heater. An object of the present invention is to provide a heating device and an image forming apparatus in which a delay in detection and a decrease in measurement temperature are reduced.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a heating apparatus and an image forming apparatus having the above-mentioned construction.

[1] A heating element driven by a primary circuit is provided on a non-heating surface of the ceramic plate opposite to a heating surface facing the object to be heated, and the object to be heated is interposed through the ceramic plate. In a heating apparatus having a heating means comprising a ceramic heater for heating the heater and a temperature detecting element constituting a part of a secondary circuit for detecting the temperature of the ceramic heater, an insulating means for insulating the primary circuit from the secondary circuit An insulating layer (insulating layer having excellent thermal conductivity) is provided only on a portion of the ceramic heater on the non-heating surface side where the temperature detecting element is in contact, and the insulating layer is brought into contact with the insulating layer so that the temperature is reduced. A heating device comprising a detection element.

[2] A heating element driven by a primary circuit is provided on the non-heating surface side of the ceramic plate opposite to the heating surface facing the object to be heated. A ceramic heater for heating the ceramic heater, a temperature detecting element forming a part of a secondary circuit for detecting the temperature of the ceramic heater, and a heating unit including a support for supporting the ceramic heater. An insulating layer (insulating layer excellent in heat insulation) provided on the non-heating surface side to cover a portion in contact with the support, and an insulating layer provided on a portion contacting the temperature sensing element ( A heating device comprising an insulating layer having excellent thermal conductivity).

[3]: The insulating layer (insulating layer having excellent heat insulating properties) provided at a portion of the ceramic heater that contacts the heater support is provided at a portion of the ceramic heater that contacts the temperature detecting element. The heating device according to [2], wherein the heating device is glass or polyimide having a lower thermal conductivity than the insulating layer (insulating layer having excellent thermal conductivity).

[4] The above [1], [2], wherein the insulating layer provided at a portion in contact with the temperature detecting element of the ceramic heater is made of glass or polyimide.
Or the heating device according to [3].

[5] The above [1], [2], or [2], wherein an insulating layer provided at a portion of the ceramic heater which is in contact with the temperature detecting element covers the heating element.
The heating device according to [3] or [4].

[6]: Any one of the above [1] to [5], wherein the insulating layer provided at a portion in contact with the temperature detecting element of the ceramic heater is an insulating layer having good surface flatness. The heating device according to claim 1.

[7]: An insulator is interposed between the ceramic heater having the insulator layer and the temperature detecting element,
The heating device according to any one of [1] to [6], wherein the heating element and the temperature detecting element are at least doubly insulated.

[8]: The heating element and the temperature detecting element are double- insulated by interposing two insulators between the ceramic heater having the insulating layer and the temperature detecting element. The heating device according to any one of [1] to [6].

[0022]

[9]: The insulating layer according to any one of [1] to [6], wherein the insulating layer is formed of two layers, and the heating element and the temperature detecting element are doubly insulated. Heating equipment.

[10]: The method according to [1], wherein the resistance of the heating element below the insulator layer with which the temperature detecting element contacts is increased.

The heating device according to any one of [9].

[11]: In an image forming apparatus having an image forming means for forming an image on a recording material and an image heating means for heating the image on the recording material, the image heating means may be changed from [1] to [10] An image forming apparatus comprising the heating device according to any one of [10] and [10].

[12]: In an image forming apparatus having an image forming means for forming an unfixed image on a recording material and a fixing means for thermally fixing the unfixed image on the recording material, [1] is used as the fixing means. ] An image forming apparatus comprising the heating device according to any one of [10] to [10].

<Operation> In the configuration [1], the insulating layer having excellent heat conduction provided on the non-heating surface of the ceramic heater functions as an insulating means for the primary circuit and the secondary circuit. Further, since the insulating layer is provided only in a portion where the secondary circuit contacts, the heat capacity of the insulating layer is as small as possible.

Thus, the primary circuit and the secondary circuit are insulated from each other, and a delay in detecting the heater temperature and a decrease in the measured temperature are reduced.

In the configuration [2], the insulator having excellent heat conduction provided at a portion in contact with the temperature detecting element of the ceramic heater transmits the temperature of the heater to the temperature detecting element quickly and accurately, and the heater support of the ceramic heater is provided. An insulator having excellent heat insulation provided at a portion in contact with the substrate prevents heat conduction from the ceramic heater to the ceramic heater support to improve heating efficiency.

In the configuration [3], the insulator having excellent heat insulation provided at the portion in contact with the heater support of the ceramic heater reduces heat transmitted from the ceramic heater to the heater support, thereby improving the heating efficiency. Is being planned.

In the configuration [4], the insulating layer having excellent heat conduction provided at the portion in contact with the temperature detecting element of the ceramic heater quickly and accurately transmits the temperature of the heater, and the insulating layer is provided. The delay in temperature detection and the decrease in measured temperature are reduced.

In the configuration [5], the temperature difference between the insulating layer and the ceramic heater is small because the insulating layer covers and closely adheres to the heating element. Also, the difference in response speed between the temperature change of the insulator and the temperature change of the ceramic heater is small.

In the configuration [6], the insulating layer having excellent heat conduction provided only at the portion of the ceramic heater in contact with the temperature detecting element can be in close contact with the temperature detecting element because the surface is flat. . For this reason, the loss of heat conduction at the contact surface can be reduced.

In the configuration [7], the insulating layer of the ceramic heater and the insulating layer interposed between the ceramic heater and the thermistor are at least doubly insulated. Therefore, insulation can be ensured.

In the configuration [8], the insulator layer of the ceramic heater is used only as a relay medium for transmitting heat, and two insulators are interposed between the ceramic heater and the thermistor to ensure insulation. Can be.

[0035]

In the configuration of [9], the heating element and the temperature detection element can be reliably insulated by forming two insulating layers at the portion where the temperature detection element of the ceramic heater contacts.

In the configuration [10], the heat of the ceramic heater is transmitted to the temperature detecting element brought into contact with the ceramic heater, and the temperature of the heater at the contact portion is detected to be lower than the heater temperature at the adjacent portion. In order to avoid this, the heater temperature uniformity is maintained by increasing the resistance value of the heating element at the corresponding contact portion.

Thus, the insulation between the ceramic heater having the heating element operating on the primary circuit on the non-fixing surface and the temperature detecting element operating on the secondary circuit for detecting the temperature of the ceramic heater, We are satisfied with both conduction.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> First Embodiment of the Present Invention
FIG. 1 shows a configuration diagram of a ceramic heater 101 used in the embodiment. FIG. 1 shows a heating surface 105 of a ceramic heater.
6 is a diagram of the back surface (non-fixed surface). In the image heating device (fixing device) of the present example, the same configuration as that of the device shown in FIG. 14 is not described again.

In FIG. 1, reference numeral 102 denotes a ceramic substrate.
You. Ceramic material is AlN, Al _TwoO_ThreeAnd so on. Soshi
A heating element 103 is provided on the ceramic substrate 102.
Is provided. When electricity is supplied to the material of the heating element 103,
A heat-generating resistance material, for example, Ag / Pd (silver-palladium)
) Is used. The present invention has such a configuration,
The heating element is provided on the fixing surface.

Reference numeral 104 shown in FIG. 1 is an insulating layer (an insulating layer having excellent thermal conductivity). The insulator layer 104 is made of glass in which a filler such as alumina is added to increase heat conductivity. The thermistor, which will be described later, contacts the insulator layer 104. As shown in FIG. 2, the size of the insulator layer 104 in the non-fixing surface direction is such that the distances d1 to d6 from the thermistor 112 to the heat generation break satisfy the creepage distance specified by the insulation standard. The creepage distance of this embodiment is 5 mm or more. Further, it is desirable that the thickness of the insulator layer be as thin as possible within a range that satisfies the withstand voltage standard. The thickness of the insulator layer 104 in this example is 50 μm.

In this embodiment, the heat capacity of the insulator layer 104 is reduced by providing the insulator layer 104 with a minimum thickness only at the portion where the thermistor 112 contacts. The insulator layer 104 is in close contact with the ceramic substrate 102 and the heating element 103 to form an integral structure, as shown in the cross-sectional view taken along the line aa ′ in FIG. In this way, the insulator layer 104 increases heat conduction from the heating element 103 and the ceramic substrate 102 to the thermistor 112. Such an insulator layer 104 is a feature of the first embodiment.

FIG. 3 shows a thermistor 11 used in this embodiment.
FIG. 2 is a schematic view of a thermistor unit 111 in which the second element 2 is incorporated. Hereinafter, the thermistor unit 111 will be described with reference to FIG. In FIG. 3, reference numeral 113 denotes an electric wire from which both electrodes of the thermistor 112 are drawn.

Reference numeral 114 denotes a sponge. Sponge 11
Reference numeral 4 serves to press the thermistor 112 against the contact surface. In addition, the sponge 114 is a thermistor 112
It also plays a role of insulating the space between the thermistor unit 111 and the frame 116. The material of the sponge is Si
Type or fluorine type can be used. Also, ceramic paper can be used instead of the sponge.

Reference numeral 115 denotes a polyimide tube. The polyimide tube 115 also includes the heating element 103 and the thermistor 1
12 and serves to insulate them. In this example, the insulator layer 104 provided on the ceramic heater and the polyimide tube 11
5 for double insulation. The polyimide tube 115 preferably has high heat conductivity. Therefore, it is preferable to use a polyimide tube in which a filler is inserted to increase the heat conduction. Further, in the present embodiment, a tube-shaped polyimide film is used, but a sheet-shaped polyimide film may be wound. As the insulating material, a material that satisfies insulation, heat resistance, and heat conduction other than polyimide may be used. Grease may be used between the polyimide tube 115 and the thermistor 112 so as to increase the heat conduction between the polyimide tube 115 and the thermistor 112.

Reference numeral 116 denotes a frame of the thermistor unit 111. Thermistor unit 111 has mounting hole 1
17 is vacant. The ceramic heater support (not shown) has a hole through which the heat-sensitive portion of the thermistor unit 111 passes,
There is a boss for attaching the thermistor unit. The mounting hole 117 of the thermistor unit 111 is fitted to the boss of the ceramic heater support, and the thermistor unit 111 is pressed against the ceramic heater support by a push nut. Thus, the thermistor unit 111 is fixed. Therefore, the positional accuracy of the thermistor with respect to the ceramic heater 101 depends on the positional accuracy of the mounting hole 117,
It is determined by the positional accuracy of the boss of the ceramic heater support and the positional accuracy when the ceramic heater is fixed to the ceramic heater support.

FIG. 4 shows a drive circuit diagram of the ceramic heater 101. In FIG. 4, the temperature of the ceramic heater 101 depends on the low-voltage DC power supply Vdc, the resistor 133 and the thermistor 11.
2 converts it into a voltage. The heater temperature converted into the voltage is input to the CPU 131. When the heater temperature is lower than the target temperature, the CPU 131 sends a heater ON signal. Then, the transistor 129 is driven, and the phototriac coupler 127 is driven. The photo triac coupler 127 drives the triac 124. The triac 124 drives the ceramic heater 101. Thus, the temperature of the ceramic heater 101 is controlled.

Reference numeral 121 denotes a commercial power supply (100 V in Japan). Noise filter 122, ceramic heater 10
1, the triac 124, the resistors 125 and 126, and the receiving side of the phototriac coupler 127 are driven by a commercial power supply, and thus belong to a primary circuit. Send side of phototriac coupler 127, transistor 129, CPU1
31, thermistor 112, resistors 128, 130, 133
Is driven by a low-voltage power supply Vdc = 3.3 V (may be 5 V) and belongs to a secondary circuit. Therefore, the ceramic heater 101 and the thermistor 112 need to be insulated.

As shown in FIG. 5, the thermistor unit 11
1 contacts the ceramic heater 101. At this time, the sponge 114 is compressed and the thermistor 112 is pressed against the polyimide tube 115.

The polyimide tube 115 is also in close contact with the ceramic heater 101. Further, by applying grease between the thermistor unit 111 and the ceramic heater 101, it is possible to increase heat conduction.

In this way, the disadvantages of insulating the heating element belonging to the primary circuit and the temperature detecting element belonging to the secondary circuit, that is, the delay of temperature detection and the error of temperature detection can be reduced. it can.

<Second Embodiment> FIG. 6 shows a configuration diagram of a ceramic heater 201 used in a second embodiment of the present invention. FIG. 6 is a diagram of the back surface (non-fixing surface) with respect to the heating surface 205 of the ceramic heater.

In FIG. 6, reference numeral 202 denotes a ceramic substrate.
You. Ceramic material is AlN, Al _TwoO_ThreeAnd so on. Soshi
A heating element 203 is formed on the ceramic substrate 202.
Is provided. When electricity is supplied to the material of the heating element 203,
A heat-generating resistance material, for example, Ag / Pd (silver-palladium)
) Is used. This embodiment has such a configuration,
Ceramic heater with a heating element on the non-fixing surface.
Is what you do.

Reference numeral 204 shown in FIG. 6 is an insulator layer having high heat conductivity. The insulator layer 204 is made of glass in which a filler such as alumina is added to increase heat conductivity. The thermistor unit 111 shown in FIG.
Is abutted. The size of the insulator layer 204 in the non-fixing surface direction is the same as in the first embodiment. As shown in FIG. 2, the distances d1 to d6 between the thermistor 112 and the heat generation break have a size that satisfies the creepage distance specified by the insulation standard or more. The creepage distance of this example is 5 mm or more. Further, it is desirable that the thickness of the insulator layer be as thin as possible within a range that satisfies the withstand voltage specification. The thickness of the insulator layer 204 in this example is 50 μm.

As shown in the sectional view taken along the line aa 'of FIG. 6, such an insulator layer 204 is in close contact with the ceramic substrate 202 and the heating element 203 to form an integral structure, and is in contact with the support of the ceramic heater. The feature of the present embodiment is that an insulating layer 206 having excellent heat insulating properties is provided in a portion where the heat treatment is performed.

The thermistor unit used in this embodiment is the same as the thermistor unit 111 used in the first embodiment. Therefore, description of the thermistor unit 111 is omitted. In the second embodiment, the thermistor unit 111 comes into contact with the insulator layer 204 of the ceramic heater 201 having excellent heat conduction as shown in FIG. At this time, the sponge 114 is pressed and contracted, and the thermistor 1
12 is pressed against the polyimide tube 115. The polyimide tube 115 is also a ceramic heater 20.
Adhere to 1.

Further, by applying grease between the thermistor unit 111 and the ceramic heater 201, it is possible to increase heat conduction.

Next, a method of fixing the ceramic heater 201 to the ceramic heater support 241 will be described. As shown in FIG. 8, the ceramic heater support 241
Has a structure in which the ceramic heater 201 is received at several points of the boss 244. Thus, the heat of the ceramic heater 201 is devised so as not to be easily transmitted to the ceramic heater support. In fixing the ceramic heater support 241 and the ceramic heater 201, the boss 244 of the ceramic heater support and the insulating layer 206 of the ceramic heater 201 having excellent heat insulating properties are fixed using an adhesive 245.

FIG. 8 shows the thermistor unit 111.
As shown in the above, it is fitted into a column of the ceramic heater support 241 and fixed with a push nut 243.

According to the present embodiment, the adverse effect caused by insulating the heating element belonging to the primary circuit and the temperature detecting element belonging to the secondary circuit, that is, the delay in temperature detection and the error in temperature detection are reduced. be able to. Further, the heat generated by the ceramic heater can be hardly transmitted to the heater support, and the heat generated by the heater can be used effectively.

<Third Embodiment> FIG. 9 shows a configuration diagram of a ceramic heater 301 used in a third embodiment of the present invention. FIG. 9 is a diagram of the back surface (non-fixing surface) with respect to the heating surface 105 of the ceramic heater.

In FIG. 9, reference numeral 302 denotes a ceramic substrate.
You. Ceramic material is AlN, Al _TwoO_ThreeAnd so on. Soshi
A heating element 303 is formed on the ceramic substrate 302.
Is provided. When the material of the heating element 303 is energized,
A heat-generating resistance material, for example, Ag / Pd (silver-palladium)
) Is used. The present invention has such a configuration,
Related to a ceramic heater provided with a heating element on the fixing surface
Things.

Reference numeral 304 shown in FIG. 9 is an insulator layer. The insulator layer 304 is made of glass in which a filler such as alumina is added to increase heat conductivity. The thermistor described below is in contact with the insulator layer 304. In the present embodiment, the size of the insulator layer 304 in the direction of the non-fixing surface only needs to be large enough to make contact with the thermistor unit regardless of the specification of the creepage distance. The thickness of the insulator layer may be such a thickness that the thermistor unit can be brought into close contact with and brought into contact therewith. As described above, regardless of the insulation standard, the heat capacity of the insulator layer 304 can be further reduced by providing the insulator layer 304 only at the portion where the thermistor 312 contacts.

As shown in the cross-sectional view taken along the line aa ′ of FIG. 9, the insulating layer 304 has a ceramic substrate 302 and a heating element 303.
It is close to and has an integral structure. Here, the insulator layer 30
4 does not function sufficiently as insulating means, but the heating element 303
Further, heat conduction between the ceramic substrate 302 and the thermistor 312 is increased.

Such an insulator layer 304 is a feature of this embodiment.

FIG. 10 shows a thermistor 31 used in this embodiment.
2 is a thermistor unit 311 incorporating the same. Hereinafter, the thermistor unit 311 will be described with reference to FIG. The thermistor unit 311 is obtained by covering the thermistor unit 111 used in the first embodiment with another polyimide tube. That is, the thermistor unit 311 alone is doubly insulated. The polyimide tube is better if it has good thermal conductivity. In addition, thermal conductive grease may be inserted between the polyimide tube 315 and the polyimide tube 318.

The thermistor unit 311 contacts the ceramic heater 301 as shown in FIG. At this time, the sponge 314 is compressed and the thermistor 312 is pressed against the polyimide tube 315.

The polyimide tube 315 is also pushed by the sponge 314, and presses the polyimide tube 318. Then, the polyimide tube 318 comes into close contact with the ceramic heater 101. Further, by applying grease between the thermistor unit 111 and the ceramic heater 101, it is possible to increase heat conduction.

As described above, also in the present embodiment, the adverse effects of insulating the heating element belonging to the primary circuit and the temperature detecting element belonging to the secondary circuit, that is, delay in temperature detection and error in temperature detection Can be reduced.

<Example of Image Forming Apparatus> FIG. 12 shows an example of an image forming apparatus using the ceramic heater. FIG.
FIG. 2 is a diagram of a laser beam printer using a ceramic heater. The laser beam printer 1 is connected to an external device 31 such as a computer, and prints on the recording paper 28 under the control of the external device 31.

First, the external device 31 supplies various control signals and image information to the video controller 27. The video controller 27 generates and outputs various control signals and video signals based on the image information sent from the external device 31. The print control unit 26 is a control circuit for controlling each unit in the apparatus.

FIG. 13 shows the operation timing of the laser beam printer of FIG. Video controller 27
As shown in FIG. 13A, R
When the DY signal becomes TRUE, as shown in FIG.
The RINT signal is set to TRUE. When the PRINT signal becomes TRUE, the print control unit 26, FIG.
As shown in (g), the main motor 23 and the polygon motor 1
4 is started. The main motor 23 drives the photosensitive drum 17 and the pressure roller 1 of the fixing device 9.
1. The discharge roller 12 starts rotating. Thereafter, the print control unit 26 starts controlling the light amount of the semiconductor laser 13, generating a high voltage of the primary charger 19, the developing device 20, and the transfer charger 21 and controlling the temperature of the heater unit 111.

As shown in FIG. 13 (g), when the time T1 has elapsed since the start of driving of the polygon motor 14 and the rotation of the polygon motor 14 is in a steady state, as shown in FIG. The paper clutch 24 is turned on to drive the paper feed roller 5 to feed the recording paper 28 in the paper feed cassette 2 toward the registration roller 6. Then, the print control unit 26 outputs a VSREQ signal to the video controller 27 as shown in FIG. 13C at the timing when the recording paper 28 reaches the registration roller 6, and the paper feed clutch 24 as shown in FIG. Is turned off, and the driving of the paper feed roller 5 is stopped. On the other hand, the video controller 27 finishes developing the image information from the external device 31 into a dot image, and
When the signal output preparation is completed, the VSR shown in FIG.
After confirming that the EQ signal is TRUE, FIG.
As shown in (d), the VSYNC signal is set to TRUE.
Then, in synchronization with this, as shown in FIG.
Thereafter, the output of the VDO signal is started as image data for one page.

At this time, the print control unit 26
Time T from the rising of the VSYNC signal as shown in (i).
After three, the registration roller clutch 25 is turned on, and the registration roller 6 is driven. The driving of the registration roller 6 is performed during T4 until the rear end of the recording paper 28 passes through the registration roller 6 as shown in FIG. During this time, the print control unit 26 drives the semiconductor laser 13 according to the VDO signal from the video controller 27.

The laser light emitted from the semiconductor laser 13 is converted into a linear scan by the rotation of the polygon mirror 15 of the scanner unit 7. After that, the laser light is reflected by the mirror 16 and irradiated on the photosensitive drum 17. A latent image is formed on the photosensitive drum 17 by simultaneously scanning the laser beam modulated in accordance with the VDO signal on the photosensitive drum 17 in this manner. A latent image of the minute is formed.

The latent image formed on the photosensitive drum 17 is developed by the developing device 20, and then the toner image is transferred to the recording paper 28 by the transfer charger 21. When the transfer is completed, the recording paper 28 is conveyed to the fixing device 9 shown in the first to third embodiments.

The recording paper 28 on which the toner image has been fixed is discharged out of the apparatus by the discharge rollers 12. When printing the next page continuously, the print control unit 26
As shown in FIG. 13B, after the time T5, the PRINT signal is set to TRUE again, and the same control as that for printing the first page is performed.

[0077]

As described above, according to the present invention,
It is possible to provide a heating device and an image forming apparatus in which a delay in temperature detection and an error in temperature detection are reduced by insulating a heating element belonging to the primary circuit and a temperature detection element belonging to the secondary circuit.

[Brief description of the drawings]

FIG. 1 is a diagram of a ceramic heater according to a first embodiment.

FIG. 2 is a diagram illustrating a creepage distance of a heating unit according to the first embodiment.

FIG. 3 is a diagram of a thermistor unit according to the first embodiment.

FIG. 4 is a diagram of a driving circuit of the ceramic heater according to the first embodiment.

FIG. 5 is a diagram in which a thermistor unit is in contact with a ceramic heater in the first embodiment.

FIG. 6 is a diagram of a ceramic heater according to a second embodiment.

FIG. 7 is a view in which a thermistor unit is in contact with a ceramic heater in the second embodiment.

FIG. 8 is a diagram in which a ceramic heater and a thermistor unit are assembled on a ceramic heater support in the second embodiment.

FIG. 9 is a diagram of a ceramic heater according to a third embodiment.

FIG. 10 is a diagram of a ceramic heater of a thermistor unit according to a third embodiment.

FIG. 11 is a diagram in which a thermistor unit is in contact with a ceramic heater in the third embodiment.

FIG. 12 is a schematic configuration diagram of a laser beam printer including a ceramic heater.

13 is a time chart for explaining the operation of the laser beam printer of FIG.

FIG. 14 is a cross-sectional view of a conventional fixing device.

FIG. 15 is a diagram of a conventional ceramic heater.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser beam printer 2 paper feed cassette 5 paper feed roller 6 registration roller 7 scanner unit 9 fixing device 10 pressure roller 12 paper discharge roller 13 semiconductor laser 14 polygon motor 15 polygon mirror 16 mirror 17 photosensitive drum 19 primary charger 20 developing device Reference Signs List 21 transfer charger 23 main motor 24 paper feed clutch 25 registration roller clutch 26 print controller 27 video controller 28 recording paper 31 external device 32 ceramic heater 33 ceramic substrate 34 heating element 35 thermistor 36 film 39 shaft 40 rubber 41 tube 42 toner ( (Transfer toner image) 43 Fixed toner image 44, 45, 46 Conductor (connector contact part) 47 Glass 48 Through hole 49 Conductive pattern 101 Ceramic heater 102 Ceramic substrate 1 02 The ceramic substrate 103 Heating element 104 Insulator layer 105 Heating surface 111 Thermistor unit 112 Thermistor 114 Sponge 115 Polyimide tube 116 Frame 117 hole 122 Noise filter 124 Triac 125, 126 Resistance 127 Phototriac coupler 128, 130, 133 Resistance 129 transistor 201 Ceramic heater 202 ceramic substrate 203 heating element 204 insulating layer 205 heating surface 206 insulating layer 241 ceramic heater support 243 push nut 244 boss 245 adhesive 301 ceramic heater 302 ceramic substrate 303 heating element 304 insulating layer 311 thermistor unit 312 thermistor 314 Sponge 315,318 Polyimide tube

Claims (12)

[Claims] 1. A heating element driven by a primary circuit is provided on a non-heating surface of a ceramic plate opposite to a heating surface facing the object to be heated, and the object to be heated is heated via the ceramic plate. A heating device comprising a ceramic heater to be heated and a temperature detecting element constituting a part of a secondary circuit for detecting the temperature of the ceramic heater, wherein the insulating means for insulating the primary circuit from the secondary circuit includes: A heating device, wherein an insulating layer is provided only on a portion of the ceramic heater on the non-heating surface side where the temperature detecting element is in contact, and the temperature detecting element is disposed in contact with the insulating layer. . 2. A heating element driven by a primary circuit is provided on a non-heating surface of the ceramic plate opposite to a heating surface facing the object to be heated, and the object to be heated is heated via the ceramic plate. A ceramic heater, and a temperature detecting element forming a part of a secondary circuit for detecting a temperature of the ceramic heater;
In a heating device having a heating means comprising a support for supporting the ceramic heater, an insulating layer provided on a non-heating surface side of the ceramic heater so as to cover a portion in contact with the support, and the temperature detection element A heating device comprising an insulating layer provided at a portion where the heater contacts. 3. An insulating layer provided on a portion of the ceramic heater in contact with a heater support, wherein the insulating layer is made of glass or glass having a lower thermal conductivity than an insulating layer provided on a portion of the ceramic heater in contact with a temperature detecting element. The heating device according to claim 2, wherein the heating device is a polyimide. 4. The heating device according to claim 1, wherein the insulating layer provided at a portion of the ceramic heater that contacts the temperature detecting element is made of glass or polyimide. 5. The heating device according to claim 1, wherein an insulating layer provided at a portion of the ceramic heater in contact with the temperature detecting element covers the heating element. apparatus. 6. The ceramic heater according to claim 1, wherein the insulator layer provided at a portion in contact with the temperature detecting element of the ceramic heater is an insulator layer having good surface flatness. A heating device as described. 7. The heating element and the temperature sensing element are at least doubly insulated by interposing an insulator between the ceramic heater having the insulator layer and the temperature sensing element. 7. The heating device according to any one of 1 to 6. 8. The heating element and the temperature sensing element are doubly insulated by interposing two insulators between the ceramic heater having the insulator layer and the temperature sensing element. Item 7. The heating device according to any one of Items 1 to 6. 9. The method according to claim 1, wherein the insulating layer is formed of two layers, and the heating element and the temperature detecting element are doubly insulated. Heating equipment. 10. The heating device according to claim 1, wherein a resistance value of a heating element below the insulator layer with which the temperature detection element contacts is increased. 11. An image forming apparatus comprising: an image forming means for forming an image on a recording material; and an image heating means for heating the image on the recording material. An image forming apparatus comprising the heating device according to claim 1. 12. An image forming apparatus comprising: an image forming means for forming an unfixed image on a recording material; and a fixing means for thermally fixing the unfixed image on the recording material. An image forming apparatus, comprising: the heating device according to claim 10.