JP7033883B2 - Heater and image forming device - Google Patents

Description

The present invention relates to a heater and an image forming apparatus.

A first electrode used in the anchoring part of an electrode image forming apparatus, which includes a plurality of divided heating elements and is commonly connected between the plurality of heating elements and a power source, and a part of each of these electrodes. A heater containing each of the resistors including the second electrode connected to the power supply is known. In such a heater, a relatively high voltage power is applied to the heating element. Therefore, when the portion of the fixing belt that comes into contact with the heater has conductivity, it is necessary to surely insulate between the fixing belt and the electrode of the heater.

Japanese Unexamined Patent Publication No. 2016-6501

The embodiment is made from the above-mentioned request, and an object of the present invention is to provide a heater capable of reliably insulating between a fixing belt and a heater electrode, and an image forming apparatus using the heater. do.

In order to solve the above-mentioned problems, the heater according to the embodiment includes one or more heat generating resistors that are selectively supplied with electric power from a power source to generate heat and heat a member that comes into contact with the recording medium. An insulating substrate formed with one of the one or more heat-generating resistors and a first electrode connecting a terminal on the high-voltage side of a power source, an insulating holder for holding the insulating substrate, and a holder of the holder. It has the heat generation resistor housed inside and an insulating protective layer that protects the first electrode and comes into contact with the member. The first electrode is formed at a position separated from the edge of the insulating substrate by a predetermined distance. A groove is formed between the edge of the insulating substrate and the inner side surface of the holder. The heater has a groove formed on the boundary surface between the edge of the insulating substrate and the protective layer, and the inner surface of the groove and the protective layer formed between the edge of the insulating substrate and the inner side surface of the holder. It has a path of a predetermined creepage distance from the first electrode through which electricity is transmitted along the boundary surface with the member to the member.

It is a figure which shows the structure of the image forming apparatus which concerns on embodiment. It is a figure which shows the structure of the image forming part for black shown in FIG. It is a figure which shows the structure of the fixing device shown in FIG. FIG. 3 is a cross-sectional view taken along the line XY of the heater shown in FIG. It is a YY plan view of the heater shown in FIG. It is a figure which shows the connection between the terminal of the heater shown in FIG. 5 and the switch circuit which selectively connects these to a power source. It is a figure which shows the structure of the control device shown in FIG. It is a YY plan view of the 2nd heater. FIG. 8 is a cross-sectional view taken along the line XX of the second heater including the straight lines A to A shown in FIG. It is a YY plan view of the 3rd heater. FIG. 10 is a cross-sectional view taken along the line XY of the second heater including the straight lines A to A shown in FIG.

[First Embodiment]
Hereinafter, this first embodiment will be described in detail with reference to the drawings. In embodiments, the same components are designated by the same reference numerals. Further, in each figure, the size of each component and its ratio may be different from those at the time of implementation, and the size of each component and its ratio are not constant between each figure. Further, in each of the following figures, some of the components may be omitted as appropriate in order to avoid complication of the drawings and clarify them.

[MFP10]
FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment. In FIG. 1, the image forming apparatus is a multifunction device (MFP; Multi-Function Peripherals), a printer, a copying machine, or the like, and the MFP 10 is a specific example in the following description. The main body 11 of the MFP 10 is provided with an operation panel 14 at the upper portion, and the operation panel 14 is provided with various keys and a touch panel type display unit.

[Printer unit 17]
The main body 11 of the MFP 10 is provided with a control device 36 at the upper part and a printer unit 17 at the central part, and is provided with a plurality of paper feed cassettes 18 at the lower part, each of which accommodates any one of a plurality of types of paper P. The printer unit 17 is a tandem color laser printer, and has a photoconductor drum and a scanning head 19 including an LED as an exposure device. The printer unit 17 processes image data read by a scanner, image data created by a personal computer, and the like, scans a photoconductor drum with a light beam from a scanning head 19, and obtains an image obtained by processing the image data. Is formed on the paper P.

The printer unit 17 has an image forming unit 20Y of each color of yellow (Y), magenta (M), cyan (C), and black (K) in parallel on the lower side of the intermediate transfer belt 21 along the upstream side to the downstream side. , 20M, 20C, 20K. Further, the printer unit 17 includes a plurality of scanning heads 19 corresponding to the image forming units 20Y, 20M, 20C, and 20K. The image forming units 20Y, 20M, 20C, and 20K have the same configuration.

FIG. 2 is a diagram showing the configuration of the image forming unit 20K for black shown in FIG. The image forming unit 20K has a photoconductor drum 22K of an image carrier. The image forming unit 20K includes a charger 23K, a developing device 24K, a primary transfer roller 25K, a cleaner 26K, and a blade 27K around the photoconductor drum 22K along the rotation direction t. Light is irradiated from the scanning head 19K to the exposed position of the photoconductor drum 22K, and an electrostatic latent image is formed.

The charger 23K of the image forming unit 20K uniformly charges the surface of the photoconductor drum 22K. The developer 24K supplies a two-component developer containing black toner and carriers to the photoconductor drum 22K by a developing roller 24a to which a developing bias is applied to develop an electrostatic latent image. The cleaner 26K uses a blade 27K to remove residual toner on the surface of the photoconductor drum 22K.

Further, as shown in FIG. 1, the intermediate transfer belt 21 is stretched by the drive roller 31 and the driven roller 32 and moves cyclically. Further, the intermediate transfer belt 21 faces and contacts the photoconductor drums 22Y, 22M, 22C, and 22K. The primary transfer voltage is applied by the primary transfer rollers 25Y, 25M, 25C, 25K to the positions of the intermediate transfer belt 21 facing the photoconductor drums 22Y, 22M, 22C, 22K, and the photoconductor drums 22Y, 22M, 22C, 22K. The upper toner image is primaryly transferred to the intermediate transfer belt 21. However, in FIG. 1, for convenience of illustration, reference numerals 25Y, 25M, and 25C are not shown, and reference numeral 25K is attached only to the temporary transfer roller on the photoconductor drum 22K.

The secondary transfer roller 33 is arranged so as to face the drive roller 31 that stretches the intermediate transfer belt 21. While the paper P passes between the drive roller 31 and the secondary transfer roller 33, the secondary transfer voltage is applied to the paper P by the secondary transfer roller 33, and the toner image on the intermediate transfer belt 21 is transferred to the paper P. Next is transcribed. Further, a fixing device 4 is provided downstream of the secondary transfer roller 33.

[Fixing device 4]
FIG. 3 is a diagram showing the configuration of the fixing device 4 shown in FIG. As shown in FIG. 3, the fixing device 4 includes a heating device 400 that is orbitally driven in the S direction and a pressure roller 440 that rotates according to the orbit of the heating device 400. The pressure roller 440 includes a protective layer 442 made of PFA (copolymer of ethylene tetrafluoroethylene (C ₂ F ₄ )) and perfluoroalkoxy ethylene), a silicon sponge layer 444 having a thickness of about 5 mm, and a diameter of 10 mm. It is equipped with a degree iron core 446.

An endless fixing belt 402 of the heating device 400 is provided, and the fixing belt 402 has a front surface 404 and a back surface 406. The back surface 406 of the fixing belt 402 includes a conductive base layer such as polyimide (PI) having a thickness of 70 μm, Ni having a thickness of about 70 μm, and SUS (stainless steel) having a thickness of 70 μm. The surface 404 includes an insulating silicone rubber layer having a thickness of about 200 μm formed on the base layer. That is, the fixing belt 402 has a multilayer structure of a base layer and silicone rubber. Further, the heating device 400 further includes a heater 5 that is pressed toward the pressurizing roller 440 side together with the fixing belt 402 to form a fixing nip portion that heats the paper P. With such a configuration, the thermal responsiveness of the fixing nip portion in the fixing device 4 is higher than that of the fixing nip portion heated by the halogen lamp.

[Heater 5]
FIG. 4 is a cross-sectional view taken along the line XY of the first heater 5 shown in FIG. FIG. 5 is a YY plan view of the first heater 5 shown in FIG. FIG. 6 shows the terminals T502, T504, T506, T508-1, 508-2, T510, T512 of the first heater 1 shown in FIG. 5, and the switch circuit 56 for selectively connecting these to the power supply. It is a figure which shows the connection.

As shown in FIGS. 4 to 6, the first heater 5 covers the electrode group 50, the resistance heating layer 52, the electrode group 50, and the resistance heating layer 52 formed on the insulating ceramic substrate 516. It includes an insulating surface protective layer 514 and a holder 518 made of an insulating heat resistant resin that holds these components. In the actual MFP 10, the heater 5 is formed in an elongated rectangular shape of about 360 mm in the longitudinal direction (Z-axis direction) and about 10 mm in the lateral direction (Y direction).

The electrode group 50 includes six silver electrodes 500, 504, 506, 508, 510, 512 formed of aluminum on the surface protective layer 514. A convex portion 502 is provided at a portion corresponding to the central axis of the silver electrode 500 on the common side at a distance of 1.2 mm from the edge of the ceramic substrate 516. The high-voltage side terminal of the power supply is connected to the silver electrode 500, and the ground potential terminal of the power supply is connected to the silver electrodes 504,506,508,510,512 on the individual side.

The resistance heating layer 52 is made of silver having a thickness of about 10 μm on a part of the electrode group 50 and the ceramic substrate 516, and is manufactured by the same manufacturing method as the screen (thick film) printing process (printing, drying and firing). It is formed by repeating it multiple times in order). The resistance heating layer 52 selectively receives the supply of alternating current flowing in the transport direction (Y-axis direction) of the paper P from the alternating current power supply 54 having a voltage of about 200 V at maximum, and generates heat. , 528.

As shown in FIGS. 4 and 5, a space having a width of 1 mm is provided between the silver electrode 500 side of the ceramic substrate 516 and the side surface of the holder 518, and this space is filled with the surface protective layer 514. To. Therefore, the creepage distance (insulator creepage distance) L of the surface protective layer 514 between the convex portion 502 and the conductive back surface 406 can be 3.2 mm or more that can secure insulation with respect to the maximum power supply voltage of 200 V. ..

The insulator creeping distance L of 3.2 mm is defined by the width of the groove (gap) between the silver electrode 500 side of the ceramic substrate 516 and the side surface of the holder 518 (gap) of 1 mm, the thickness of the ceramic substrate 516 of 1 mm, and the silver electrode. It is a value to which the distance 1.2 mm from the edge of the convex portion 502 of 500 to the edge of the ceramic substrate 516 is added. Therefore, the insulation between the convex portion 502 and the back surface 406 is surely maintained. Further, since the silver electrodes 504,506,508,510,512 are connected to the terminals of the ground potential of the power supply, the edges of the ceramic substrate 516 on the silver electrodes 504,506,508,510,512 side and the side surface of the holder 518 It is not necessary to provide a groove between the two and fill the surface protective layer 514.

Each of the silver electrodes 504 and 506 is connected to each of the terminals T504 and T506 drawn from one short side of the heater 5. The silver electrode 508 is connected to terminals T508-1 and T508-2 drawn from both short sides of the heater 5. Each of the silver electrodes 510 and 512 is connected to terminals T510 and T512 drawn from the other short side of the heater 5. The convex portion 502 of the silver electrode 500 is connected to the terminal T502 drawn from one short side of the heater 5.

The resistors 520, 522, 524, 526, 528 are connected to the AC power supply 54 via the silver electrode 500 and the terminal T502. Further, the resistors 520, 522, 524, 526, 528 are via the switch circuit 56, the silver electrodes 504,506,508,510,512 and the terminals T504, T506, T508-1, T508-2, T510, T512. It is selectively connected to the AC power supply 54.

The resistors 528 on the central axes A to -A of the paper P are formed so as to have a uniform thickness in a target shape with respect to the central axes A to -A and the resistance values are evenly distributed over the entire surface. To. Further, the resistors 522 and 528 located in the target portion with respect to the central axes A to −A are formed to have the same thickness and a shape symmetrical to the central axis so that the same resistance value is evenly distributed over the entire surface. To.

Similarly, the resistors 524 and 526 located in the target portion with respect to the central axes A to −A are formed to have the same thickness and a shape symmetrical to the central axis so that the same resistance value is evenly distributed over the entire surface. Will be done. Therefore, the heat generation distribution of the resistors 520, 522, 524, 526, 528 of the resistance heating layer 52 is symmetrical with respect to the central axes A to −A.

The silver electrode 500 has an elongated rectangular shape symmetrical with respect to the central axis and long in the longitudinal direction, and has a resistance of about 0.5 mm in the entire range of the upstream side of the resistors 520, 522, 524, 526, 528 in the transport direction. It is formed so as to overlap. The length at which the other electrodes and the resistor overlap is also about 0.5 mm. Therefore, in the silver electrode 500, the resistance values between the convex portion 502 and the resistors 520 and 528 located at the portions symmetrical with respect to the central axis are equal, and the convex portion 502 and the portion symmetrical with respect to the central axis. The resistance values between the resistors 522 and 526 located at are also equal.

The silver electrode 504 and the silver electrode 512 located at a portion symmetrical with respect to the central axis are formed to have the same thickness and have a shape symmetrical with respect to the central axis. Therefore, the resistance value between the resistor 520 and the terminal T504 at the silver electrode 504 is equal to the resistance value between the resistor 528 and the terminal T512 at the silver electrode 512.

Similarly, the silver electrode 506 and the silver electrode 510 located at a portion symmetrical with respect to the central axis are formed to have the same thickness and have a shape symmetrical with respect to the central axis. Therefore, the resistance value between the resistor 522 and the terminal T506 at the silver electrode 506 is equal to the resistance value between the resistor 526 and the terminal T510 at the silver electrode 510.

The width of the silver electrode 500 including the convex portion 502 in the lateral direction is about 3.2 mm. Further, the width between the silver electrodes 504 and 512 in the lateral direction is about 0.6 mm. Further, in the silver electrodes 506 and 510, the width of the portion connected to the terminals T506 and T512 in the lateral direction is about 1 and 2 mm. Further, in the silver electrode 508, the width of the portion connected to the terminals T508-1 and T508-2 in the lateral direction is about 2.4 mm. In this way, by adjusting the width of the portion connected to each terminal in each electrode, the resistance value between each resistor and each terminal in each electrode can be adjusted to be equal.

As shown in FIG. 6, the switch circuit 56 has terminals T506 and T510 of silver electrodes 506 and 510 drawn from the heater 5 shown in FIG. 5 according to a switch control signal SC from the outside, and an AC power supply 54. It includes a switch 564 that connects or disconnects between them. Further, the switch circuit 56 connects or disconnects between the terminals T504 and T512 of the silver electrodes 504 and 512 drawn from the heater 5 shown in FIG. 5 and the AC power supply 54 according to the switch control signal SC from the outside. A switch 566 is provided.

Further, the switch circuit 56 connects or connects between the terminals T508-1 and T508-2 of the silver electrodes 508 drawn from the heater 5 shown in FIG. 5 and the AC power supply 54 according to the switch control signal SC from the outside. A switch 562 for disconnecting is provided. The terminal T502 of the silver electrode 500 is connected to the AC power supply 54 without going through the switch circuit 56.

[Control device 36]
FIG. 7 is a diagram showing the configuration of the control device 36 shown in FIG. As shown in FIG. 7, the control device 36 includes a CPU 360 including a CPU and its peripheral circuits, a memory 362 including a ROM, RAM, a flash memory, and the like, and an operation panel interface (IF) 364 to which the operation panel 14 is connected. And prepare.

Further, the control device 36 is a paper feed / transport control circuit that controls the components between the paper feed cassette 18 shown in FIG. 1 and the paper output tray of the main body 11 to perform paper feed and paper transport. Further equipped with 368. Further, the control device 36 further includes an image formation control circuit 370 that controls the printer unit 17, and a fixing control circuit 372 that controls the operation of the fixing device 4. The components of the control device 36 are connected to each other via the bus 374.

Further, the control device 36 generates the switch control signal SC shown in FIG. 6 to connect or open the switches 562,564,566 included in the AC power supply 54 so as to match the width of the paper to be conveyed. Control so that the entire surface of the paper to be conveyed is heated sufficiently. With these components, the operation of each component of the MFP 10 is controlled according to the user's operation on the operation panel, and the image formation on the paper P by the MFP 10 is realized.

[Second Embodiment]
Hereinafter, the second embodiment will be described. FIG. 8 is a YY plan view of the second heater 6. FIG. 9 is an XZ cross-sectional view of the second heater 6 including the straight lines A to A shown in FIG. As shown in FIGS. 8 and 9, in the second heater 6, in addition to the grooves shown in FIGS. 4 and 5, two short sides of the ceramic substrate 516 and two short sides inside the holder 518 are used. A groove having a width of 1 mm is also formed between them.

In this way, by further forming a groove having a width of 1 mm and filling it with the surface protective layer 514, the creepage insulation distance L between the two short sides of the ceramic substrate 516 and the two short sides of the holder 518 is also 3. It can be 2 mm. Therefore, the second heater 6 can further ensure the insulation between the back surface 406 of the fixing belt 402 and the silver electrode 500 shown in FIG. 3 as compared with the first heater 5.

[Third Embodiment]
Hereinafter, the third embodiment will be described. FIG. 10 is a YY plan view of the third heater 7. FIG. 11 is a cross-sectional view taken along the line XY of the second heater 7 including the straight lines A to A shown in FIG. The XZ cross-sectional view of the third heater 7 is the same as the XZ cross-sectional view of the second heater 6 shown in FIG. As shown in FIGS. 10 and 11, in the third heater 7, in addition to the grooves shown in FIGS. 8 and 9, the long side along the silver electrode 508 of the ceramic substrate 516 and facing the long side. A groove having a width of 1 mm is also formed between the holder and the long side of the holder 518.

In this way, by further forming a groove having a width of 1 mm and filling it with the surface protective layer 514, the entire creepage insulation distance L between the four sides of the ceramic substrate 516 and the inner four sides of the holder 518 is set to 3.2 mm. can do. Therefore, according to the third heater 7, the back surface 406 of the fixing belt 402 shown in FIG. 3 and the back surface 406 of the fixing belt 402 shown in FIG. 3 even when high voltage power is supplied from the power source to the silver electrodes 504,506,508,510,512. The insulation between the silver electrode 500 and the silver electrode 500 can be further ensured.

[Technical effect]
Even if the distance between the edges of the silver electrodes 500, 504, 506, 508, 510, 512 and the convex portion 502 and the edge of the ceramic substrate 516 is 3 mm, a groove is provided between the ceramic substrate 516 and the holder 518. The same technical effect as in the case can be obtained. However, when the heaters 5 to 7 are configured in this way, unless the size of the ceramic substrate 516 is increased, the resistors 520, 522, 524, 526, 528 have to be shortened in the Y-axis direction, and the fixing belt 402 has to be shortened. The area to be heated is reduced. Therefore, when the heaters 5 to 7 are configured in this way, the fixing characteristics of the toner on the paper P are significantly deteriorated.

On the other hand, according to the heaters 5 to 7 according to the embodiment, such a problem is avoided. Further, as shown in the embodiment, according to the method of providing the groove filled by the surface protective layer 514 between the ceramic substrate and the holder, the structure of the heaters 5 to 7 is significantly changed from the conventional structure. There is no need.

[Modification example]
The back surface 406 of the fixing belt 402 shown in FIG. 4 or the like may be coated with a highly durable coating in order to improve the slidability between the fixing belt 402 and the heaters 5 to 7. Further, oil or grease may be applied to the back surface 406 of the fixing belt 402. Further, in FIG. 5 and the like, one resistor 524 is arranged on the central axis of the heater 5, and two sets of resistors 520, 528 and 522, 526 are arranged in a portion symmetrical to the central axis. However, the heater 5 may have a configuration without a resistor on the central axis.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

10 MFP (multifunction device)
11 Main unit 14 Operation panel 17 Printer unit 18 Paper feed cassette 19 Scan head 20 Image forming unit 21 Intermediate transfer belt 22 Photoreceptor drum 23K Charger 24K Developer 25K Primary transfer roller 26K Cleaner 27K Blade 31 Drive roller 33 Secondary transfer roller 4 Fixing device 400 Heating device 402 Fixing belt 404 Front surface 406 Back surface 440 Pressurized roller 442 Protective layer 444 Silicon sponge layer 446 Iron core 5 Heater 50 Electrode group 500, 504 to 512 Silver electrodes T502, T504 to T512 Terminal 502 Convex part 514 Surface protective layer 516 Ceramic substrate 518 Holder 52 Resistance heating layer 520 to 528 Resistor 56 Switch circuit 562 to 566 Switch

Claims (4)

One or more heat-generating resistors that are selectively supplied with power from a power source to generate heat and heat a member that comes into contact with the recording medium.
An insulating substrate formed with one of the one or more heat-generating resistors and a first electrode connecting a terminal on the high-voltage side of the power supply.
An insulating holder that houses the insulating substrate inside,
An insulating protective layer that protects the heat generation resistor housed inside the holder and the first electrode and abuts on the member.
Have,
The first electrode is formed at a position separated from the edge of the insulating substrate by a predetermined distance.
A groove is formed between the edge of the insulating substrate and the inner side surface of the holder.
By forming the groove, the boundary surface between the edge of the insulating substrate and the protective layer, and the inner surface of the groove formed between the edge of the insulating substrate and the inner side surface of the holder. A heater having a path of a predetermined creepage distance from the first electrode to the member, through which electricity is transmitted along a boundary surface between the and the protective layer. The insulating substrate has
A second electrode connecting the other of the one or more heat generation resistors to the power supply is further formed.
The heater according to claim 1, wherein a terminal on the ground side of the power supply is connected to the second electrode. The insulating substrate has
A second electrode connecting the other of the one or more heat generation resistors to the power supply is further formed.
In the insulating substrate, a gap further filled with the protective layer is provided between the edge along the second electrode and the inner side surface of the holder.
The heater according to claim 1, wherein high voltage power is supplied from the power source to the first electrode and the second electrode. Photoreceptor drum and
A latent image forming portion that forms a latent image on the photoconductor drum,
The latent image developer and
A transfer device that transfers the toner image visualized by this developer to a recording medium, and
An image forming apparatus including the fixing device including the heater according to any one of claims 1 to 3.

Images