JP7095125B2 - Heater used for image heating device and image heating device - Google Patents

Description

The present invention is a fuser mounted on an electrophotographic recording type image forming apparatus such as a copying machine or a printer, or a gloss imparting device for improving the glossiness of a toner image by reheating a fixed toner image on a recording material. , Etc. relating to the image heating device. Further, the present invention relates to a heater used in this image heating device.

As the image heating device, there is a device having an endless belt (also referred to as an endless film), a heater in contact with the inner surface of the endless belt, and a roller forming a nip portion together with the heater via the endless belt. When small-sized paper is continuously printed by an image forming apparatus equipped with this image heating device, a phenomenon occurs in which the temperature of a region where the paper does not pass in the longitudinal direction of the nip portion gradually rises (heat rise in the non-passing portion). If the temperature of the non-passing part becomes too high, each part in the device will be damaged, or if printing is performed on large-sized paper with the non-passing part warming up, the non-passing part of the small-sized paper will be printed. The toner may be offset to the endless belt at high temperature in the area corresponding to.

As one of the methods for suppressing the temperature rise of the non-passing portion, the heating element (hereinafter referred to as a heating element) on the heater substrate is formed of a material having positive resistance temperature characteristics. Then, two conductors are arranged at both ends of the substrate in the lateral direction so that a current flows in the lateral direction of the heater (hereinafter referred to as transport direction feeding) with respect to the heating element (hereinafter referred to as transfer direction feeding). (Patent Document 1). The idea is that when the temperature rises in the non-passing section, the resistance value of the heating element in the non-passing section rises, and the current flowing through the heating element in the non-passing section is suppressed, thereby suppressing the heat generation in the non-passing section. Is. The positive resistance temperature characteristic is a characteristic in which the resistance value increases as the temperature rises, and is hereinafter referred to as PTC (Positive Temperature Coefficient).

Japanese Unexamined Patent Publication No. 2011-151003

However, even with such a heater, a current also flows through a heating element located in the non-paper-passing portion.

It is an object of the present invention to provide a heater and an image heating device that can further suppress the temperature rise of the non-paper-carrying portion while suppressing the increase in size of the heater.

The present invention for solving the above-mentioned problems includes an endless belt, a substrate, a first conductor provided on the substrate along the longitudinal direction of the substrate, and the first conductor on the substrate. A second conductor provided along the longitudinal direction at different positions in the lateral direction of the substrate, and the first conductor provided between the first conductor and the second conductor. In order to have a heater that generates heat by electric power supplied through the second conductor, a heater that contacts the inner surface of the endless belt, and a heater that contacts the electrodes of the heater to supply electric power to the heating element. In an image heating device that has an electric contact and heats an image formed on a recording material, the heater can be independently controlled by a pair of the first conductor, the second conductor, and the heating element. At least one of the electrodes for the second conductor, which is an electrode corresponding to each of the heat generating blocks and is directly connected to the second conductor, has a plurality of heat generating blocks in the longitudinal direction. The electric contact is provided in the region where the heating element is provided and is opposite to the surface of the heater in contact with the endless belt, and the electrical contact is in contact with the electrode for the second conductor. The first conductors of the plurality of heat generating blocks are connected to each other and are arranged so as to face the opposite surfaces of the heater, and are common to the plurality of heat generating blocks. , Two electrodes for the first conductor that are directly connected to the common first conductor are provided, and one of the electrodes for the first conductor is provided with the heating element in the longitudinal direction. It is provided outside one end of the region, and the other electrode for the first conductor is provided outside the other end of the region where the heating element is provided in the longitudinal direction. It is characterized by.

Further, in the present invention, the substrate, the first conductor provided on the substrate along the longitudinal direction of the substrate, and the first conductor on the substrate at different positions in the lateral direction of the substrate. A second conductor provided along the longitudinal direction, a second conductor provided between the first conductor and the second conductor, and supplied via the first conductor and the second conductor. In a heater having a heating element that generates heat by a power source, the heater has a plurality of independently controllable heat generating blocks composed of a pair of the first conductor, the second conductor, and the heating element in the longitudinal direction. However, at least one of the electrodes for the second conductor, which is the electrode corresponding to each of the heat generating blocks and is directly connected to the second conductor, is located in the region where the heat generating element is provided in the longitudinal direction. The first conductors of the plurality of heat generating blocks are connected to each other to be a common first conductor of the plurality of heat generating blocks, and are directly connected to the common first conductor. Two electrodes for the first conductor are provided, and one of the electrodes for the first conductor is provided outside the one end of the region where the heating element is provided in the longitudinal direction. The other electrode for the first conductor is provided outside the other end of the region where the heating element is provided in the longitudinal direction .

Sectional drawing of image forming apparatus. Sectional drawing of the image heating apparatus of Example 1. FIG. The heater block diagram of Example 1. The heater control circuit diagram of Example 1. The heater control flowchart of Example 1. The explanatory view of the effect of suppressing the temperature rise of the non-paper-passing portion of the heater of Example 1. The heater block diagram of Example 2. The heater control circuit diagram of Example 2. The heater control flowchart of Example 2. The heater block diagram of Example 3. The heater block diagram of Example 4. The heater block diagram of Example 5. The heater block diagram of Example 6. The figure for demonstrating the effect of Example 7. The heater block diagram of Example 7. FIG. 6 is a heater configuration diagram of a modified example of the seventh embodiment. The heater block diagram of Example 8. The heater block diagram of Example 9. The heater block diagram of Example 10. 11th embodiment is a heater configuration diagram.

(Example 1)
FIG. 1 is a cross-sectional view of a laser printer (image forming apparatus) 100 using an electrophotographic recording technique. When the print signal is generated, the scanner unit 21 emits a laser beam modulated according to the image information, and scans the photoconductor 19 charged with a predetermined polarity by the charging roller 16. As a result, an electrostatic latent image is formed on the photoconductor 19. Toner is supplied from the developer 17 to the electrostatic latent image, and a toner image corresponding to the image information is formed on the photoconductor 19. On the other hand, the recording material (recording paper) P loaded on the paper feed cassette 11 is fed one by one by the pickup roller 12 and conveyed toward the resist roller 14 by the roller 13. Further, the recording material P is conveyed from the resist roller 14 to the transfer position at the timing when the toner image on the photoconductor 19 reaches the transfer position formed by the photoconductor 19 and the transfer roller 20. The toner image on the photoconductor 19 is transferred to the recording material P in the process of passing the recording material P through the transfer position. After that, the recording material P is heated by the image heating device 200, and the toner image is heated and fixed on the recording material P. The recording material P carrying the fixed toner image is discharged to the tray above the laser printer 100 by the rollers 26 and 27. Reference numeral 18 is a cleaner for cleaning the photoconductor 19, and 28 is a paper feed tray (manual feed tray) having a pair of recording material restriction plates whose width can be adjusted according to the size of the recording material P. The paper feed tray 28 is provided to accommodate recording materials P having a size other than the standard size. Reference numeral 29 is a pickup roller for feeding the recording material P from the paper feed tray 28, and reference numeral 30 is a motor for driving the image heating device 200 and the like. Power is supplied to the image heating device 200 from the control circuit 400 connected to the commercial AC power supply 401. The photoconductor 19, the charging roller 16, the scanner unit 21, the developing device 17, and the transfer roller 20 as described above constitute an image forming portion for forming an unfixed image on the recording material P.

The laser printer 100 of this embodiment corresponds to a plurality of recording material sizes. Letter paper (about 216 mm × 279 mm), Legal paper (about 216 mm × 356 mm), A4 paper (210 mm × 297 mm), and Executive paper (about 184 mm × 267 mm) can be set in the paper feed cassette 11. Further, JIS B5 paper (182 mm × 257 mm) and A5 paper (148 mm × 210 mm) can be set.

In addition, irregular paper patterns including DL envelopes (110 mm × 220 mm) and COM10 envelopes (about 105 mm × 241 mm) can be fed and printed from the paper feed tray 28. The printer of this example is basically a laser printer that feeds paper vertically (conveys the paper so that the long side is parallel to the transport direction). The recording materials having the largest (larger width) width among the widths of the standard recording materials (widths of the recording materials on the catalog) supported by the apparatus are Letter paper and Legal paper, and these widths. Is about 216 mm. A recording material P having a paper width smaller than the maximum size supported by the apparatus is defined as a small size paper in this embodiment.

FIG. 2 is a cross-sectional view of the image heating device 200. The image heating device 200 is a pressure roller (nip portion forming) that forms a fixing nip portion N together with a tubular film (endless belt) 202, a heater 300 that contacts the inner surface of the film 202, and a heater 300 via the film 202. Member) 208 and. The material of the base layer of the film 202 is a heat-resistant resin such as polyimide or a metal such as stainless steel. Further, an elastic layer such as heat-resistant rubber may be provided on the surface layer of the film 202. The pressure roller 208 has a core metal 209 made of a material such as iron or aluminum, and an elastic layer 210 made of a material such as silicone rubber. The heater 300 is held by a holding member 201 made of heat-resistant resin. The holding member 201 also has a guide function for guiding the rotation of the film 202. The pressurizing roller 208 receives power from the motor 30 and rotates in the direction of the arrow. As the pressure roller 208 rotates, the film 202 is driven and rotated. The recording material P carrying the unfixed toner image is heated and fixed by being sandwiched and conveyed by the fixing nip portion N.

As shown in FIG. 3A, the heater 300 is heated by a heating element provided on the ceramic substrate 305. Thermistors TH1, TH2, TH3, and TH4 as temperature detecting elements are in contact with the paper passing region of the laser printer 100 on the back surface side of the substrate 305. A safety element 212 such as a thermo switch or a thermal fuse that operates due to abnormal heat generation of the heater 300 to cut off the electric power supplied to the heater 300 is also in contact with the back surface side of the substrate 305. No. 204 is a metal stay for applying the pressure of a spring (not shown) to the holding member 201.

FIG. 3 shows a configuration diagram of the heater 300 of the first embodiment. With reference to FIGS. 3 and 6, the configuration of the heater 300 and the effect of suppressing the temperature rise of the non-paper-passing portion will be described.

FIG. 3A shows a cross-sectional view of the heater 300 in the lateral direction. Layer 1 on the back surface of the heater 300 (the surface opposite to the surface in contact with the endless belt) is provided with a first conductor 301 provided on the substrate 305 along the longitudinal direction of the heater 300. .. Further, a second conductor 303 is provided on the substrate 305 at a position different from that of the first conductor 301 in the lateral direction of the heater 300 along the longitudinal direction of the heater 300. The first conductor 301 is separated into a conductor 301a arranged on the upstream side in the transport direction of the recording material P and a conductor 301b arranged on the downstream side.

Further, the heater 300 is provided between the first conductor 301 and the second conductor 303, and has a heating element 302 that generates heat by electric power supplied via the first conductor 301 and the second conductor 303. .. The heating element 302 is separated into a heating element 302a arranged on the upstream side in the transport direction of the recording material P and a heating element 302b arranged on the downstream side.

When the heat generation distribution in the lateral direction of the heater 300 (the transport direction of the recording material) becomes asymmetric, the stress generated in the substrate 305 when the heater 300 generates heat increases. When the stress generated on the substrate 305 becomes large, the substrate 305 may be cracked. Therefore, the heating element 302 is separated into a heating element 302a arranged on the upstream side in the transport direction and a heating element 302b arranged on the downstream side so that the heating element distribution in the lateral direction of the heater 300 is symmetrical. ..

Further, the layer 2 on the back surface of the heater 300 is provided with an insulating (glass in this embodiment) surface protective layer 307 that covers the heating element 302, the conductor 301, and the conductor 303. Further, the layer 1 of the sliding surface (the surface in contact with the endless belt) of the heater 300 has a surface protective layer 308 coated with slidable glass or polyimide.

FIG. 3B shows a plan view of each layer of the heater 300. The heater 300 has a plurality of heat generation blocks composed of a pair of a first conductor 301, a second conductor 303, and a heating element 302 in the layer 1 on the back surface in the longitudinal direction of the heater 300. As an example, the heater 300 of the present embodiment has a total of three heat generation blocks at the central portion and both ends in the longitudinal direction of the heater 300. The first heating block 302-1 is composed of heating elements 302a-1 and 302b-1 formed symmetrically in the lateral direction of the heater 300. Similarly, the second heat generation block 302-2 is composed of heating elements 302a-2 and 302b-2, and the third heat generation block 302-3 is composed of heating elements 302a-3 and 302b-3. ing.

The first conductor 301 is provided along the longitudinal direction of the heater 300. The first conductor 301 is a conductor 301a connected to a heating element (302a-1, 302a-2, 302a-3) and a conductor connected to a heating element (302b-1, 302b-2, 302b-3). It is composed of 301b.

The second conductor 303 provided along the longitudinal direction of the heater 300 is divided into three conductors 303-1, 303-2, and 303-3.

The electrodes E1, E2, E3, E4-1 and E4-2 are connected to electric contacts for supplying electric power from the control circuit 400 of the heater 300 described later. The electrode E1 is an electrode for supplying power to the heat generation block 302-1 via the conductor 303-1. Similarly, the electrode E2 is an electrode used to supply power to the heat generation block 302-2 via the conductor 303-2. The electrode E3 is an electrode for supplying power to the heat generating block 302-3 via the conductor 303-3. The electrodes E4-1 and E4-2 are electrodes connected to a common electric contact for supplying power to the three heat generating blocks 302-1 to 303-3 via the conductors 301a and 301b.

By the way, since the resistance value of the conductor is not zero, it affects the heat generation distribution in the longitudinal direction of the heater 300. Therefore, even under the influence of the electric resistance of the conductors 303-1, 303-2, 303-3, 301a and 301b, the electrodes E4-1 and the electrode E4-1 and the electrode E4-1 and so as to obtain a heat generation distribution symmetrical in the longitudinal direction of the heater 300. E4-2 is provided at both ends of the heater 300 in the longitudinal direction.

Further, the surface protective layer 307 of the layer 2 on the back surface of the heater 300 is formed except for the portions of the electrodes E1, E2, E3, E4-1 and E4-2, and is formed on each electrode from the back surface side of the heater 300. It is configured so that electrical contacts can be connected. In this embodiment, electrodes E1, E2, E3, E4-1 and E4-2 are provided on the back surface of the heater 300 so that power can be supplied from the back surface side of the heater 300. Further, the ratio of the electric power supplied to at least one heat generating block among the plurality of heat generating blocks to the electric power supplied to the other heat generating blocks can be changed. By providing the electrodes on the back surface of the heater 300, it is not necessary to perform wiring by the conductive pattern on the substrate 305, so that the width in the lateral direction of the substrate 305 can be shortened. Therefore, it is possible to obtain the effect of reducing the material cost of the substrate 305 and shortening the start-up time required for the temperature rise of the heater 300 by reducing the heat capacity of the substrate 305. The electrodes E1, E2, and E3 are provided in the region where the heating element is provided in the longitudinal direction of the substrate. Further, the surface protection layer 308 of the layer 1 of the sliding surface of the heater 300 is provided in the region where the film 202 slides.

As shown in FIG. 3C, the holding member 201 of the heater 300 includes thermistors (temperature detection elements) TH1 to TH4, safety elements 212, and electrodes E1, E2, E3, E4-1 and E4-2. There are holes for the contacts. HTH1 to HTH4, H212, HE1 to HE3, HE4-1, and HE4-2 are holes.

Between the stay 204 and the holding member 201, the above-mentioned thermistors (temperature detecting elements) TH1 to TH4, the safety element 212, and the electric contacts in contact with the electrodes E1, E2, E3, E4-1, and E4-2 are provided. Is provided. C1 to C3, C4-1, and C4-2 are electric contacts. In FIG. 3C, the broken line connected to the electric contacts C1 to C3, C4-1, and C4-2 and the broken line connected to the safety element 212 all indicate a power feeding cable (AC line). ing. Further, the broken line connected to the temperature detection elements TH1 to TH4 indicates a signal line (DC line). These elements and electric contacts are arranged facing the back surface of the heater 300. The electric contacts in contact with the electrodes E1, E2, E3, E4-1 and E4-2 are electrically connected to the electrode portion of the heater by a method such as urging with a spring or welding. Each electric contact is connected to a control circuit 400 of a heater 300, which will be described later, via a conductive material such as a cable (dashed line described above) or a thin metal plate provided between the stay 204 and the holding member 201.

The power control to the heater 300 is performed based on the output of the thermistor TH1 provided near the center of the paper passing portion (near the transport reference position X described later). The thermistor TH4 detects the end temperature of the heat generation region of the heat generation block 302-2 (the end temperature of the heat generation region in the state of FIG. 6B). Further, the thermistor TH2 detects the end temperature of the heat generation region of the heat generation block 302-1 (the end temperature of the heat generation region in the state of FIG. 6A). The thermistor TH3 detects the end temperature of the heat generation region of the heat generation block 302-3 (the end temperature of the heat generation region in the state of FIG. 6A).

Further, the apparatus of this embodiment is provided with one or more thermistors in each of the three heat generation blocks so that it can detect a state in which power is supplied only to a single heat generation block due to a failure or the like, and the safety of the equipment is provided. Is increasing. When considering only the failure of the triac 416 and the triac 426, at least one or more thermistors (for example, only thermistors TH1 and TH2 are provided in FIG. 3) are provided for each of a plurality of independently controllable heat generation blocks. It may be provided. In this embodiment, in consideration of the failure of the triac 416 and the triac 426 and the defect of the electric contact to each electrode, one or more thermistors are provided in each of the three heat generation blocks. For example, when the electrical contact to the electrode E1 is poorly connected, power may not be supplied to the heat generation block 302-1 and power may be supplied to the heat generation block 302-3. Therefore, both the heat generation block 302-1 and the heat generation block 302-3 are provided with thermistors TH2 and TH3.

The safety element 212 is a portion of the paper passing region of the smallest available size paper set in the laser printer 100, which is less affected by the temperature rise of the non-passing portion in order to prevent malfunction due to the temperature rise of the non-passing portion. It is in contact with the heat generation block 302-2 (near the center). As a result, the temperature of the safety element 212 during normal operation is lowered, so that the operating temperature of the safety element 212 can be set low, and the safety of the image heating device 200 can be enhanced.

Next, the effect of suppressing the temperature rise of the non-passing portion of the heater 300 will be described with reference to FIG. FIG. 6A is a diagram illustrating a temperature rise of a non-passing paper portion when power is supplied to all three heat generation blocks. An example is shown in which B5 paper is conveyed in the vertical direction with respect to the central portion of the heat generation region. The reference position for transporting the recording material P is defined as the recording material P transport reference position X.

The paper cassette 11 has a position regulating plate that regulates the position of the recording material P, feeds the recording material P from a predetermined position for each size of the loaded recording material P, and feeds the recording material P from a predetermined position. The recording material P is conveyed so as to pass through the position of. Similarly, the paper feed tray 28 has a position regulating plate that regulates the position of the recording material P, and conveys the recording material P so as to pass through a predetermined position of the image heating device 200.

The heater 300 has a heat generation region length of 220 mm with respect to a paper width of about 216 mm in order to cope with the case where the Letter paper is conveyed in the vertical direction. When B5 paper having a paper width of 182 mm is vertically conveyed to the heater 300 having a heat generation region length of 220 mm, 19 mm non-passing paper regions are generated at both ends of the heat generation region. The power control to the heater 300 is performed so that the detection temperature of the thermistor TH1 provided near the center of the paper passing portion maintains the target temperature, but the non-passing portion does not take heat from the paper, so that the paper is not passed. The temperature of the paper section rises compared to the paper thread section. As shown in FIG. 6A, in the case of B5 size paper, the ends of the recording material P pass through a part of the heat generating blocks 302-1 and 302-3 at both ends, and each end is 19 mm non-passing. A paper part is generated. However, since the heating element 302 is a PTC, the resistance value of the heating element in the non-paper-passing portion is higher than that in the heating element in the paper-passing portion, and it becomes difficult for current to flow. By this principle, it is possible to suppress the temperature rise of the non-passing paper portion.

FIG. 6B is a diagram illustrating a temperature rise in the non-paper section when power is supplied only to the heat generation block 302-2 in the central portion of the heater 300. An example is shown in which a DL size envelope having a width of 110 mm is transported in the vertical direction with respect to the central portion of the heat generation region. The heat generation block 302-2 of the heater 300 has a heat generation region length of 157 mm with respect to a paper width of 148 mm in order to cope with the case where A5 paper is conveyed in the vertical direction. When a DL-sized envelope with a width of 110 mm is vertically transported to a heater 300 in which the central heat generation block 302-2 has a length of 157 mm, 23.5 mm non-passage is performed at both ends in the central heat generation block 302-2. A paper area is created. The control of the heater 300 is performed based on the output of the thermistor TH1 provided near the center of the paper-passing portion, and since heat is not taken by the paper in the non-paper-passing portion, the temperature of the non-paper-passing portion is controlled by the paper-passing portion. It rises compared to the part. In the state of FIG. 6B, the influence of the non-paper-passing region can be reduced by first supplying power only to the heat generation block 302-2. Generally, the longer the non-passing portion region is, the worse the temperature rise of the non-passing portion is. Therefore, the effect of feeding power to the heating element 302 of the PTC in the transport direction alone cannot sufficiently suppress the temperature rise of the non-passing portion. There is. Therefore, as shown in FIG. 6B, a method of shortening the length of the non-passing paper region as much as possible is effective. Further, the non-passing area of 23.5 mm at both ends in the central heat generating block 302-2 can suppress the temperature rise by the same principle as in FIG. 6A.

As shown in FIG. 6B, the heating element 302 has a positive resistance to suppress the temperature rise of the non-paper-passing portion when power is supplied only to the heat generating block 302-2 in the central portion of the heater 300. The effect can be obtained even when it is not the temperature characteristic (PTC). Therefore, this embodiment is not limited to the case where PTC is used for the heating element 302. Further, the configuration of this embodiment can be applied even when there is no temperature coefficient of resistance of the heating element 302 or when it has a negative resistance temperature characteristic (NTC).

FIG. 4 shows a circuit diagram of the control circuit 400 of the heater 300 of the first embodiment. 401 is a commercial AC power source connected to the laser printer 100. The power control of the heater 300 is performed by energizing / shutting off the triac 416 and the triac 426. By controlling the triac 416 and the triac 426, the heat generation blocks 302a-1 and 302a-3 and the heat generation block 302a-2 can be independently controlled. The power supply to the heater 300 is performed via the electrodes E1 to E3, E4-1, and E4-2. In this embodiment, the resistance values of the heat generation blocks 302a-1 and 302b-1 are 140Ω, the resistance values of the heat generation blocks 302a-2 and 302b-2 are 28Ω, and the resistance values of the heat generation blocks 302a-3 and 302b-3 are 140Ω. explain.

The zero-cross detection unit 430 is a circuit that detects the zero-cross of the AC power supply 401, and outputs a ZEROX signal to the CPU 420. The ZEROX signal is used to control the heater 300. The relay 440 is used as a power cutoff means to the heater 300, which operates by the output from the thermistors TH1 to TH4 (cuts off the power supply to the heater 300) when the heater 300 is overheated due to a failure or the like.

When the RLON440 signal is in the High state, the transistor 443 is turned on, the power supply voltage Vcc2 is energized to the secondary coil of the relay 440, and the primary contact of the RLON440 is turned ON. When the RLON440 signal is in the Low state, the transistor 443 is turned OFF, the current flowing from the power supply voltage Vcc2 to the secondary coil of the relay 440 is cut off, and the primary contact of the RLON440 is turned OFF.

Next, the operation of the safety circuit using the relay 440 will be described. When any one of the detection temperatures by thermistors TH1 to TH4 exceeds a predetermined value set respectively, the comparison unit 441 operates the latch unit 442, and the latch unit 442 latches the RLOFF signal in the Low state. When the RLOFF signal is in the Low state, even if the CPU 420 puts the RLON440 signal in the High state, the transistor 443 is kept in the OFF state, so that the relay 440 can be kept in the OFF state (safe state).

When the detection temperature by the thermistors TH1 to TH4 does not exceed the predetermined values set respectively, the RLOFF signal of the latch portion 442 is in the open state. Therefore, when the CPU 420 sets the RLON440 signal to the High state, the relay 440 can be turned to the ON state, and power can be supplied to the heater 300.

Next, the operation of the triac 416 will be described. The resistors 413 and 417 are bias resistors for the triac 416, and the phototriac coupler 415 is a device for ensuring the creepage distance between the primary and secondary. Then, the triac 416 is turned on by energizing the light emitting diode of the photo triac coupler 415. The resistor 418 is a resistor for limiting the current flowing from the power supply voltage Vcc to the light emitting diode of the phototriac coupler 415, and the transistor 419 turns on / off the phototriac coupler 415. The transistor 419 operates according to the FUSER1 signal from the CPU 420.

When the triac 416 is energized, electric power is supplied to the heating elements 302a-2 and 302b-2, and electric power is supplied to the resistor having a combined resistance value of 14Ω. When power is supplied only to the heating elements 302a-2 and 302b-2 by controlling the power control by the triac 416 and the triac 426 at an energization ratio of 1: 0, the state described in FIG. 6B is obtained. ..

Since the circuit operation of the TRIAC 426 is the same as that of the TRIAC 416, the description thereof will be omitted. The triac 426 operates according to the FUSER2 signal from the CPU 420. When the triac 426 is energized, electric power is supplied to the heating elements 302a-1, 302b-1, 302a-3, and 302b-3. Since these four heating elements 302a-1, 302b-1, 302a-3, and 302b-3 are connected in parallel, power is supplied to a resistor having a combined resistance value of 35Ω.

In the state of FIG. 6A, power is supplied by using the triac 416 and the triac 426. That is, when the triac 416 and the triac 426 are energized, electric power is supplied to the heating elements 302a-1, 302b-1, 302a-2, 302b-2, 302a-3, and 302b-3. Since these six heating elements 302a-1, 302b-1, 302a-2, 302b-2, 302a-3, and 302b-3 are connected in parallel, power is supplied to a resistor having a combined resistance value of 10Ω. By controlling the power control by the triac 416 and the triac 426 at an energization ratio of 1: 1, the state described in FIG. 6A is obtained.

By the way, in many cases, the total resistance value of the heater 300 is designed so that the width of the corresponding maximum recording material P (Letter paper and Legal paper in this embodiment) can handle the required electric power. In the configuration of this embodiment, the total resistance value in the state of FIG. 6B is 14Ω, which is higher than the total resistance value of 10Ω in the state of FIG. 6A. It is advantageous for the safety protection of the heater 300 (generally, the lower the resistance value, the worse). For example, consider a heater adjusted to 10Ω in a state where three heat generation blocks (302-1, 302-2, 302-3) are connected in series. With this configuration, when power is supplied only to the heat generating block 302-2 in the center of the heater, the total resistance value of the heater is lowered, which is disadvantageous to the harmonic standard, the flicker, and the safety protection of the heater 300. The configuration of this embodiment is advantageous in suppressing harmonics, flicker, etc. because a plurality of heat generating blocks (three heat generating blocks in this embodiment) divided in the longitudinal direction of the heater are connected in parallel.

Next, the temperature control method of the heater 300 will be described. As for the temperature detected by the thermistor TH1, the partial pressure with the resistor (not shown) is detected by the CPU 420 as a TH1 signal (thermistors TH2 to TH4 are also detected by the CPU 420 in the same manner). In the internal processing of the CPU (control unit) 420, the electric power to be supplied is calculated based on the detection temperature of the thermistor TH1 and the set temperature of the heater 300, for example, by PI control. Further, it is converted into a control level of a phase angle (phase control) and a wave number (wave number control) corresponding to the supplied electric power, and the triac 416 and the triac 426 are controlled according to the control conditions. In this embodiment, the temperature of the heater 300 is controlled based on the heater temperature detected by the thirmister TH1. However, the temperature of the film 202 may be detected by a thermistor or a thermopile, and the temperature of the heater 300 may be controlled based on the detected temperature.

FIG. 5 is a flowchart illustrating a control sequence of the image heating device 200 by the CPU 420. When a print request is generated in S501, the relay 440 is turned on in S502. Subsequently, in S503, it is determined whether the width of the recording material is 157 mm or more. In the laser printer 100 of this embodiment, the process shifts to S504 in the case of Letter paper, Legal paper, A4 paper, Executive paper, B5 paper, and indefinite paper pattern having a width of 157 mm or more fed from the paper feed tray 28. Then, the energization ratio of the triac 416 and the triac 426 is set to 1: 1 (state of FIG. 6A).

When the width of the recording material is narrower than 157 mm (in this embodiment, A5 paper, DL envelope, COM10 envelope, and irregular paper pattern narrower than 157 mm), the process proceeds to S505. Then, the energization ratio of the triac 416 and the triac 426 is set to 1: 0 (state of FIG. 6B).

As a method for determining the width of the recording material in S503, a method using a paper width sensor provided on the paper cassette 11 or the paper tray 28, a method using a sensor such as a flag provided on the recording material P transport path, or the like, etc. Any method will do. As another method, there are a method based on the width information of the recording material P set by the user, a method based on the image information for forming an image on the recording material P, and the like.

In S506, the image formation process speed is set to full speed using the set energization ratio, and the fixing process is performed at the target set temperature of 200 ° C. of the thermistor TH1.

In S507, it is determined whether or not the maximum temperature TH2Max of the thermistor TH2, the maximum temperature TH3Max of the thermistor TH3, and the maximum temperature TH4Max of the thermistor TH4, which are set in the CPU 420, are exceeded. Based on the thermistor signals TH2 to TH4, when it is detected that the temperature rise of the non-passing paper portion deteriorates and the temperature at the end of the heat generation region exceeds a predetermined upper limit value, the process shifts to S509 and the image formation process speed is reduced to half speed. Is set to, and the fixing process is performed at the target set temperature of 170 ° C. of the thermistor TH1. The process proceeds to S509 until the end of the print JOB is detected in S510, and the fixing process is continued. When the image forming process speed is set to half speed, the fixing property can be obtained even at a temperature lower than the full speed, so that the fixing target temperature can be reduced and the temperature of the non-paper-passing portion can also be suppressed. If the temperature of each thermistor does not exceed the maximum temperature in S507, the temperature shifts to S508. In S508, the process proceeds to S506 until the print JOB is completed, and the fixing process is continued.

When the above processing is repeated and the end of the print JOB is detected in S508 and S510, the relay 440 is turned off in S511 and the image formation control sequence is terminated in S512.

In the control of this embodiment, the energization ratio of the triac 416 and the triac 426 is set based on the width information of the recording material P, and the heat generation distribution in the longitudinal direction of the heater 300 is controlled. In addition, a method of controlling the heat generation distribution in the longitudinal direction of the heater 300 based on the temperature detection result of the thermistor corresponding to each heat generation block can be considered. As a specific example, the heat generation block 302-2 is controlled by PI control or the like using the triac 416 based on the temperature detection result of the thermistor TH1. Further, for the control of the heat generation block 302-1 and the heat generation block 302-3, a method of performing power control by PI control or the like using the triac 426 based on the temperature detection result of the thermistor TH2 or thermistor TH3 can be considered. The optimum control method may be used according to the configuration of the image heating device 200 (the number of divisions of the heating block of the heater 300, the position of the thermistor, etc.) and the specifications of the image forming device 200 (the type of corresponding recording material, etc.). can.

As described above, by using the heater 300 and the image heating device 200 of the first embodiment, it is possible to suppress the temperature rise of the non-passing sheet portion when printing a size smaller than the maximum size supported by the device. Further, the symmetry of the heat generation distribution in the lateral direction of the heater 300 is improved, and the thermal stress of the substrate 305 can be reduced. Further, the symmetry of the heat generation distribution in the longitudinal direction of the heater 300 is improved, and the unevenness of the heat generation distribution in the longitudinal direction of the heater 300 can be reduced. Further, in the heater 300 of the present embodiment, by providing the electrodes on the back surface of the heater 300, it is not necessary to perform wiring by the conductive pattern on the substrate 305. Therefore, it is possible to increase the number of heat generation blocks in the longitudinal direction of the heater 300, the number of electrodes, and the number of triacs for controlling the heat generation distribution in the longitudinal direction of the heater 300 without widening the width in the lateral direction of the heater 300. Further, the number of steps for switching the heat generation distribution in the longitudinal direction of the heater can be increased, and the heat generation distribution in the longitudinal direction of the heater optimized for the width of a larger recording material P can be obtained. Therefore, in the heater 300, the width in the lateral direction of the substrate 305 can be shortened, and the effect of reducing the material cost of the substrate 305 and the heat capacity of the substrate 305 to shorten the start-up time of the image heating device 200 can be obtained. Can be done. Further, by providing one or more thermistors in each of the plurality of heat generating blocks, it is possible to enhance the safety of the image heating device 200 in a faulty state.

(Example 2)
Next, the heater 300 described in the first embodiment mounted on the image heating device 200 of the laser printer 100, the holding member 201 of the heater 300, and the second embodiment in which the heater control circuit 400 is modified will be described. The same symbols as those of the first embodiment will be used and the description thereof will be omitted. The heater 700 of the second embodiment has a configuration in which the heat generation distribution in the longitudinal direction of the heater 700 can be switched in four stages. FIG. 7 shows a configuration diagram of the heater 700 of the second embodiment. FIG. 7A shows one cross-sectional view of the heater 700 in the lateral direction.

The heater 700 has a first conductor 701 provided on the substrate 305 along the longitudinal direction of the heater 700, and the heater 700 at different positions on the substrate 305 in the lateral direction of the first conductor 701 and the heater 700. It has a second conductor 703 provided along the longitudinal direction. The first conductor 701 is separated into a conductor 701a arranged on the upstream side in the transport direction of the recording material P and a conductor 701b arranged on the downstream side.

Further, the heater 700 is provided between the first conductor 701 and the second conductor 703, and has a heating element 702 that generates heat by electric power supplied through the first conductor 701 and the second conductor 703. .. The heating element 702 is separated into a heating element 702a arranged on the upstream side in the transport direction of the recording material P and a heating element 702b arranged on the downstream side.

FIG. 7B shows a plan view of each layer of the heater 700. On the layer 1 on the back surface of the heater 700, a plurality of heat generating blocks including a pair of the first conductor 701, the second conductor 703, and the heating element 702 are provided in the longitudinal direction of the heater 700. The heater 700 of this embodiment has a total of seven heat generation blocks 702-1 to 702-7 at the central portion and both ends in the longitudinal direction of the heater 700. BL1 to BL7 in the figure indicate each block.

The heating blocks 702-1 to 702-7 are composed of heating elements 702a-1 to 702a-7 and heating elements 702b-1 to 702b-7, which are symmetrically formed in the lateral direction of the heater 700, respectively. .. The first conductor 701 is composed of a conductor 701a connected to a heating element (702a-1 to 702a-7) and a conductor 701b connected to a heating element (702b-1 to 702b-7). Similarly, the second conductor 703 is divided into seven conductors 703-1 to 703-7.

The electrodes E1 to E7, E8-1 and E8-2 are used to connect to an electric contact used for supplying electric power from the control circuit 800 of the heater 700 described later. The electrodes E1 to E7 are electrodes used to supply electric power to the heat generating blocks 702-1 to 702-7 via the conductors 703-1 to 703-7, respectively. The electrodes E8-1 and E8-2 are connected to the common electric contacts used for supplying power to the seven heat generation blocks 702-1 to 702-7 via the conductors 701a and 701b. This is the electrode to be used.

Further, the surface protective layer 707 of the layer 2 on the back surface of the heater 700 is formed except for the electrodes E1, E2, E3, E4, E5, E6, E7, E8-1 and E8-2. From the back surface side of the 700, electrical contacts can be connected to each electrode.

In this embodiment, electrodes E1, E2, E3, E4, E5, E6, E7, E8-1 and E8-2 are provided on the back surface of the heater 700, and power can be supplied from the back surface side of the heater 700. Further, the ratio of the electric power supplied to at least one heat generating block of the heat generating blocks to the electric power supplied to the other heat generating blocks can be controlled.

As shown in FIG. 7C, the holding member 712 of the heater 700 includes a thermistor (temperature detection element) TH1, a safety element 212, electrodes E1, E2, E3, E4, E5, E6, E7, and E8-1. And a hole is provided for the electrical contact of E8-2.

Between the stay 204 and the holding member 712, the above-mentioned thermistor (temperature detection element) TH1, safety element 212, electrodes E1, E2, E3, E4, E5, E6, E7, E8-1 and E8-2 The electric contact is provided and is in contact with the back surface of the heater 700. Since the configurations of the electric contacts that come into contact with the electrodes E1, E2, E3, E4, E5, E6, E7, E8-1 and E8-2 are the same as those in the first embodiment, the description thereof will be omitted.

FIG. 8 shows a circuit diagram of the control circuit 800 of the heater 700 of the second embodiment. In FIG. 4 of the first embodiment, a method of controlling the electric power and controlling the heat generation distribution in the longitudinal direction of the heater 300 by using two triacs has been described. In the second embodiment, a method of controlling the electric power with one triac and controlling the heat generation distribution in the longitudinal direction of the heater 700 by using three relays 851 to 853 will be described. In this example, the relays 851 to 853 are controlled, and a heat generation block that supplies power is selected from a plurality of heat generation blocks, that is, a heat generation block that supplies power and a heat generation block that does not supply power are formed, so that independent control is possible. It is expressed as.

The relays 851 to 853 operate according to the RLON851 to 853 signals from the CPU 420. When the RLON851 to 853 signals are in the High state, the transistors 861 to 863 are turned on, the power supply voltage Vcc2 is energized to the secondary coil of the relays 851 to 853, and the primary contact of the relays 851 to 853 is turned ON. Become. When the RLON851 to 853 signals are in the Low state, the transistors 861 to 863 are turned off, the current flowing from the power supply voltage Vcc2 to the secondary coil of the relays 851 to 853 is cut off, and the primary contact of the relays 851 to 853 is closed. It goes into the OFF state.

Next, the relationship between the states of the relays 851 to 853 and the heat generation distribution in the longitudinal direction of the heater 700 will be described. When all the relays 851 to 853 are in the OFF state, power is supplied to the heat generation block 702-4, and as shown in FIG. 7B, the 115 mm width of the heater 700 generates heat, and the heat distribution for DL envelopes and COM10 envelopes is generated. Become. When the relay 851 is in the ON state and the relays 852 to 853 are in the OFF state, power is supplied to the heat generation blocks 702-3 to 702-5, and as shown in FIG. 7B, the 157 mm width of the heater 700 generates heat and A5 paper is used. It becomes the heat generation distribution for. When the relays 851 to 852 are in the ON state and the relay 853 is in the OFF state, electric power is supplied to the heat generation blocks 702-2 to 702-6, and as shown in FIG. 7B, the 190 mm width of the heater 700 generates heat and the exhaustive. And the heat generation distribution for B5 paper. When all the relays 851 to 853 are in the ON state, power is supplied to the heat generation blocks 702-1 to 702-7, and as shown in FIG. 7B, the 220 mm width of the heater 700 generates heat, and the Letter paper, Legal paper, and the like. The heat generation distribution is for A4 paper. As described above, the control circuit 800 of this embodiment can control the heat generation distribution in the longitudinal direction of the heater 700 in four stages by using three relays 851 to 853.

The power control to the heater 700 is performed by energizing / shutting off the triac 816. Since the circuit operation of the triac 816 is the same as that of the triac 416 described in the first embodiment, the description thereof will be omitted. The triac 816 is provided in a common energization path for currents flowing through all heat generation blocks 702-1 to 702-7. Therefore, in any case where the heat generation distribution of the heater 700 is controlled in four stages, the power supplied to the heater 700 can be controlled by energizing / shutting off the triac 816.

Next, the temperature control method of the heater 700 will be described. As for the temperature detected by the th-mista TH1, the partial pressure with the resistance (not shown) is detected by the CPU 420 as a TH1 signal. In the internal processing of the CPU (control unit) 420, the electric power to be supplied is calculated based on the detection temperature of the thermistor TH1 and the set temperature of the heater 700, for example, by PI control. Further, it is converted into a control level of a phase angle (phase control) and a wave number (wave number control) corresponding to the power to be supplied, and the thyrac 816 is controlled according to the control conditions.

Further, since the temperature detection element is provided at the location of the heat generation block 702-4 connected to the power supply without going through the relays 851 to 853, the temperature of the heater 700 is detected regardless of the operating state of the relays 851 to 853. can do. As in the first embodiment, the control may be performed according to the film temperature instead of the heater temperature.

In the configuration described in the second embodiment, the heat generation blocks 702-1 to 702-3 and 702-5 at both ends of the heater 700 are not affected by the operating state of the relays 851 to 853 (assuming a short failure state and an open failure state). It is possible to prevent a state in which power is supplied only to ~ 702-7. When power is supplied to the heat generation blocks 702-1 to 702-3 and 702-5 to 702-7 at both ends of the heater 700, heat is generated in the central part of the heater 700 regardless of the operating state of the relays 851 to 853. Power is also supplied to block 702-2. Therefore, in this embodiment, the thermostat TH1 and the safety element 212 are brought into contact with the heat generation block 702-4, so that the safety circuit (safety of the relay 440) does not depend on the operating state of the relays 851 to 853. The circuit and the safety element 212) are made to function.

FIG. 9 is a flowchart illustrating a control sequence of the image heating device 200 by the CPU 420. When a print supply request is generated in S901, the relay 440 is turned on in S902.

In S903, it is determined whether the width of the recording material P is 115 mm or more. When the width of the recording material P is 115 mm or more, the process proceeds to S904 and the relay 851 is held in the ON state. If the width of the recording material P is less than 115 mm, the process proceeds to S905 and the relay 851 is held in the OFF state. In S906, it is determined whether the width of the recording material P is 157 mm or more.

When the width of the recording material P is 157 mm or more, the process proceeds to S907 and the relay 852 is held in the ON state. If the width of the recording material P is less than 157 mm, the process proceeds to S908 and the relay 852 is held in the OFF state.

In S909, it is determined whether the width of the recording material P is 190 mm or more. When the width of the recording material P is 190 mm or more, the process proceeds to S910 and the relay 853 is held in the ON state. If the width of the recording material P is less than 190 mm, the process proceeds to S911 and the relay 853 is held in the OFF state.

In S912, the image forming process speed is set to full speed while maintaining the set states of the relays 851 to 853, and the image is formed at the target set temperature of 200 ° C. of the thermistor TH1. In S913, the process proceeds to S912 until the print JOB is completed, and the fixing process is continued. When the above processing is repeated and the end of the print JOB is detected in S913, the relay 440 is turned off in S914, and the image formation control sequence is terminated in S915.

The heater 700 of this embodiment can also increase the number of steps for switching the heat generation distribution in the longitudinal direction of the heater 700 without widening the width in the lateral direction of the heater 700.

In the control circuit 800 described in the second embodiment, the number of relays for controlling the heat generation distribution is adjusted to the heater 300 (the heat generation distribution in the longitudinal direction of the heater is switched in two stages by using one relay). It is applicable to 300. Similarly, in the control circuit 400 described in the first embodiment, the number of triacs that control the heat generation distribution in the longitudinal direction of the heater is adjusted to the heater 700 (the heat generation distribution in the longitudinal direction of the heater is switched in four stages by using four triacs). Therefore, it can be applied to the heater 700. For the heaters of FIGS. 10 to 13 described in the following examples, either the control method of the control circuit 400 or the control circuit 800 may be used.

(Example 3)
FIG. 10 is a diagram for explaining the configuration of the heater 1000 applicable to the third embodiment. The same symbols as those of the first embodiment will be used and the description thereof will be omitted. The heater 1000 shown in FIG. 10 is characterized in a method of supplying power from an electrode on the back surface of the heater 1000 to a heating element 302 arranged on the sliding surface side of the substrate 305 via a through hole T.

FIG. 10A shows a cross-sectional view of the heater 1000 in the lateral direction. As shown in FIG. 10A, the heater 1000 has a first conductor 301 and a second conductor 303 heating element 302 in the layer 1 on the sliding surface side of the substrate 305.

FIG. 10B shows a plan view of each layer of the heater 1000. The electrode E1 formed on the back surface of the heater 1000 and the conductor 303-1 are connected to each other via the conductor 1004-1 and the through hole T1. Similarly, the electrode E2 and the conductor 303-2 are connected via the conductor 1004-2 and the through holes T2-1 and T2-2. The electrode E3 and the conductor 303-3 are connected via the conductor 1004-3 and the through hole T3. The electrodes E4-1 and the conductors 301a and 301b are connected to each other via the conductors 1004-4-1 and through holes T4-1a and T4-1b. The electrodes E4-2 and the conductors 301a and 301b are connected to each other via the conductors 1004-4-2 and the through holes T4-2a and T4-2b.

Further, the surface protective layer 1008 of the layer 2 of the sliding surface of the heater 1000 protects the first conductor 301 and the second conductor 303 heating element 302, and is used to improve the slidability with the film 202. It is glass.

As shown in the heater 1000, the effect of the present proposal can be obtained even in a configuration in which the heating element 302 is formed on the sliding surface side of the substrate 305.

(Example 4)
FIG. 11 is a diagram for explaining the configuration of the heater 1100 applicable to the fourth embodiment. The same symbols are used for the same configurations as those of Examples 1 and 3, and the description thereof will be omitted.

In the heater 1100 shown in FIG. 11, the heat generating blocks 1102-1 to 1102-3 are not divided in the lateral direction of the heater 1100, and similarly, the first conductor 1101 is not divided in the lateral direction of the heater 1101. It is characterized by points. Further, as compared with the heater 300 and the heater 1000, the number of electrodes was reduced by connecting the electrodes E1 and E3 on the substrate 305 and connecting the electrodes E4-1 and E4-2 on the substrate 305. It is characterized by points.

FIG. 11A shows a cross-sectional view of the heater 1100 in the lateral direction. FIG. 11B shows a plan view of each layer of the heater 1100.

The electrode E1 formed on the back surface of the heater 1100 and the conductor 1103-1 are connected to each other via the conductor 1104-1 and the through hole T1. Similarly, the electrode E2 and the conductor 1103-2 are connected via the conductor 1104-2 and the through holes T2-1 and T2-2. The electrode E4 and the conductor 1101 are connected to each other via the conductor 1104-4 and the through hole T4. The conductor 1103-3 is connected to the electrode E1 via the conductor 1104-1 and the through hole T3. In contrast to the configuration in which the electrodes E1 and E3 shown in the control circuit 400 of FIG. 4 need to be connected outside the heater 300, the electrodes E1 and E3 do not need to be connected outside the heater 300. There is. Similarly, the electrode E4-1 and the electrode E4-2 do not need to be connected to the outside of the heater 400. Therefore, the layer 2 on the back surface of the heater 1100 is provided with the protective layer 1107 except for the electrodes E1, E2, and E4.

In the heater 1100 of this embodiment, the electrode E3 is omitted by connecting the second conductor connected to the heat generation block (heat generation blocks 1102-1 and 1102-3) that do not need to be independently controlled on the substrate 305. ing. Further, one of the electrodes (E4-1 and E4-2 in FIG. 3) provided on the left and right on the substrate 305 connected to the first conductor is omitted. As a result, the number of required electrodes can be reduced. Further, as shown in the heater 1100, the effect of the present proposal can be obtained even in a configuration in which the heating element 1102 is not divided in the lateral direction of the heater 1100.

(Example 5)
FIG. 12 is a diagram for explaining the configuration of the heater 600 applicable to the fifth embodiment. The same symbols as those of the first embodiment will be used and the description thereof will be omitted.

In the heater 600 shown in FIG. 12, the heating elements 602a-1, 602b-1, 602a-2, 602b-2, 602a-3, and 602b-3 are further divided into a plurality of heating elements connected in parallel. It has characteristics.

FIG. 12A shows a cross-sectional view of the heater 600 in the lateral direction. FIG. 12B shows a plan view of each layer of the heater 600.

The heating element 602a-1 divided into a plurality of parts is connected between the conductor 603-1 and the conductor 601a to supply electric power. Since the heating element 602b-1, the heating element 602a-2, the heating element 602b-2, the heating element 602a-3, and the heating element 602b-3 have the same configuration as the heating element 602a-1, description thereof will be omitted.

The plurality of heating elements connected in parallel with the heating element 602a-1 are arranged at an angle with respect to the longitudinal direction and the lateral direction of the heater 600, and the plurality of heating elements connected in parallel with the heating element 602a-1 are arranged in the longitudinal direction. It overlaps with. As a result, the influence of the gaps between the plurality of heating elements can be reduced, and the uniformity of the heat generation distribution in the longitudinal direction of the heater 600 can be improved. Further, in the heater 600 of the present embodiment, the heating elements at the ends of the adjacent heating blocks overlap each other in the longitudinal direction even in the gaps between the heating blocks, so that the heating distribution can be made more uniform. The heating elements at the extreme ends of the adjacent heating blocks are the heating element at the right end of the heating element 602a-1, the heating element at the left end of the heating element 602a-2, and the heating element at the right end of the heating element 602a-2. , The heating element at the left end of the heating element 602a-3.

Further, by adjusting the resistance values of a plurality of heating elements connected in parallel of the heating elements 602a-1 to 602a-3 and 602b-1 to 602b-3, the temperature distribution in one heating block becomes uniform. You may adjust to. Similarly, the resistance values of the plurality of heating elements connected in parallel of the heating elements 602a-1 to 602a-3 and 602b-1 to 602b-3 are adjusted, respectively. Thereby, the heat generation block in the longitudinal direction of the heater 600 may be adjusted to be uniform across a plurality of heat generation blocks (heat generation blocks 602-1 to 602-3).

As a method of adjusting the resistance value of a plurality of heating elements connected in parallel of the heating elements 602a-1 to 602a-3 and 602b-1 to 602b-3, the width, length, spacing, inclination, etc. of each heating element are used. It can be done by adjusting. By using the heater 600 of this embodiment, it is possible to suppress temperature unevenness in the gap between a plurality of heat generating blocks.

(Example 6)
FIG. 13 is a diagram for explaining the configuration of the heater 1300 applicable to the sixth embodiment. The same symbols are used for the same configurations as those of Examples 1 and 3, and the description thereof will be omitted.

The heater 1300 shown in FIG. 13 is characterized in a method of supplying power to the heat generating block via the electrodes on the back surface of the heater 1300 only for a part of the electrodes.

FIG. 13A shows a cross-sectional view of the heater 1300 in the lateral direction. As shown in FIG. 13A, the heater 1300 has a first conductor 1301, a second conductor 1303, and a heating element 302 in the layer 1 on the sliding surface side of the substrate 305.

FIG. 13B shows a plan view of each layer of the heater 1300. The electrode E2 formed in the layer 1 on the back surface of the substrate 305 and the conductor 1303-2 formed in the layer 1 on the sliding surface side are connected via the conductor 1304 and the through holes T2-1 and T2-2. Has been done. The electrode E1 and the conductor 1303-1 are connected, the electrode E3 and the conductor 1303-3 are connected, and the electrode E4-1 and the electrode E4-2 and the conductors 1301a and 1301b are connected. The electrodes E1, the electrodes E3, the electrodes E4-1, and the electrodes E4-2 are provided outside the portions sliding with the films 202 at both ends in the longitudinal direction of the heater 1300. Therefore, electric contacts can be provided on the sliding surface sides at both ends of the heater 1300 in the longitudinal direction to connect to the electrodes E1, the electrodes E3, the electrodes E4-1, and the electrodes E4-2. Therefore, the holding member 1312 used for the heater 1300 is not provided with holes for the electrodes E1, the electrode E3, the electrode E4-1, and the electrode E4-2.

In the heater 1300, power is supplied only to a part of the heat generating blocks (302-2) via the electrodes on the back surface. In order to supply power to the heat generation block that is not in contact with both ends of the heater 1300 in the longitudinal direction from both ends in the longitudinal direction of the heater 1300, it is necessary to widen the width of the heater 1300 in the lateral direction and add a conductor on the substrate 305. There is. The heat generation blocks that are not in contact with both ends in the longitudinal direction of the heater are the heat generation blocks 302-2 in the heater 1300 of this embodiment and the heat generation blocks 702-2 to 702-6 in the heater 700 described in the second embodiment. Therefore, at least for one or more heat generation blocks that are not in contact with both ends in the longitudinal direction of the heater 1300, an electrode is provided on the second conductor, or an electrode connected via a through hole T is used. The configuration may be such that power can be supplied.

(Example 7)
FIG. 15 is a diagram for explaining the configuration of the heater 1500, which is applicable to the seventh embodiment. The heater 1500 shown in FIG. 15A has a configuration in which the positions of the electrodes E1, E2, E4, and E5 are aligned in the center (broken line X in FIG. 15) in the longitudinal direction of the heater in each heat generating block. It has become. With this configuration, uneven heat generation of the heater can be suppressed. The effect will be described below.

First, the heat generation unevenness generated in the heater in which the current flows parallel to the transport direction of the recording material will be described using the heater 1400 for explaining the heat generation unevenness shown in FIG. FIG. 14A is a plan view of the back surface layer 1 of the heater 1400, and the cross-sectional configuration of the heater, that is, the configuration of the back surface layer, the sliding surface layer, and the substrate is the same as that of the first embodiment. For easy understanding, the heater 1400 is not divided into the first conductor (1401, 1402), the second conductor 1403, and the heating element resistor (1404, 1405) in the longitudinal direction of the heater. Further, the first and second conductors and the heating element have uniform resistance values. The electrodes E1, E2a, E2b are connected to electrical contacts for supplying electric power. The electrode E1 is located at the center in the longitudinal direction, and the heating element (1404, 1405) generates heat by applying a voltage between the electrodes E1 and E2.

FIG. 14B shows the potential distribution of the conductors 1401 and 1403 in the longitudinal direction of the heater when a voltage of + 100 V is applied to the electrode E1 and a voltage of 0 V is applied to the electrode E2. Further, since the conductor 1402 has the same potential distribution as 1401, the illustration is omitted. The potential of the conductor 1403 is at the maximum in the central portion in the longitudinal direction and decreases toward both ends. This is a voltage drop due to the electrical resistance of the conductor itself. Further, the magnitude of this voltage drop changes depending on the ratio of the resistance values of the conductor 1403 and the heating element 1404. Similarly, the potential distribution of the conductor 1401 also causes a voltage drop from the center toward the end. This also depends on the ratio of the resistance values of the conductor 1401 and the heating element 1405.

The conductor and the heating element of the heater 1400 are formed on a ceramic substrate by screen printing, and their thicknesses are both within the range of 4 to 10 μm. The material of the conductor (1401, 1402, 1403) is Ag, and the specific resistance is 2 × ^10-8 Ωm. The material of the heating element (1404, 1405) was RuO ₂ , and the specific resistance was 3 × 10 ⁻² Ωm.

Here, since the voltage applied to the heating element 1404 is the potential difference between the conductor 1403 and the conductor 1401, the distribution is as shown by the broken line in FIG. 14 (B). That is, since the voltage applied to the heating element 1404 becomes non-uniform in the longitudinal direction, the heat generation distribution of the heating element 1404 also becomes non-uniform. Similarly, the heat generation distribution of the heating element 1405 becomes non-uniform. Therefore, uneven heat generation of the heater occurs.

Next, the configuration of the heater 1500 of the seventh embodiment will be described. FIG. 15A is a plan view of the back surface layer 1 of the heater 1500, and the cross-sectional configuration of the heater, that is, the configuration of the back surface layer 2, the sliding surface layer, and the substrate is the same as that of the first embodiment. Since only the configurations of the back surface layer 1 and the electrodes are different from the eighth and subsequent embodiments described later, the description of the layers other than the back surface layer 1 will be omitted.

The conductor 1503 and the heating element (1504, 1505) are divided into five in the longitudinal direction of the heater, and electric power is supplied to each block via the electrodes E1, E2, E3, E4, and E5. Further, the electrodes E1, E2, E4, and E5 are provided at positions closer to the center (broken line X) of the heater than the center of each block in the longitudinal direction of the heater.

FIG. 15B shows the potential distributions of the conductors 1501 and 1503 when a voltage of + 100 V is applied to the electrodes E1, E2, E3, E4 and E5 of the heater 1500 and a voltage of 0 V is applied to the electrodes E6a and E6b. Since the potential distribution of the conductor 1502 is the same as that of the conductor 1501, the illustration is omitted. The potential of the conductor decreases from each electrode position toward the longitudinal end of the block. This is a phenomenon similar to the voltage drop described with respect to the heater 1400 in FIG. The distribution of the potential difference between the conductor 1503 and the conductor 1501 is a broken line in FIG. 15B, and the maximum value of the potential difference is 97V and the minimum value is 92V. That is, the voltage unevenness (range) applied to the heating element (1504, 1505) is 5V.

Next, an example in which the position of the electrode is different from that of the heater 1500 is shown in FIG. The heater 1600 has a structure in which the electrodes E1, E2, E4, and E5 are arranged closer to the end side of the heater than the center of each block.

FIG. 16B shows the potential distributions of the conductors 1601 and 1603 when a voltage of + 100 V is applied to the electrodes E1, E2, E3, E4 and E5 of the heater 1600 and a voltage of 0 V is applied to the electrodes E6a and E6b. Since the potential distribution of the conductor 1602 is the same as that of the conductor 1601, the illustration is omitted. The distribution of the potential difference between the conductor 1603 and the conductor 1601 is a broken line in FIG. 16B, and the maximum value of the potential difference is 99V and the minimum value is 90V. That is, the unevenness of the voltage applied to the heating element (1604, 1605) is 9V.

Table 1 shows the maximum value, the minimum value, and the range of the potential difference between the conductors of the heater 1500 and the heater 1600.

Therefore, in order to suppress the heat generation unevenness of the heater in the longitudinal direction of the heater, the position of the electrode of each block is moved closer to the center of the heater (broken line X) than the center of each block in the longitudinal direction of the heater, as in the heater 1500. Is preferable.

(Example 8)
FIG. 17 is a diagram for explaining the configuration of the heater 1700 applicable to the eighth embodiment. The heater 1700 has a plurality of electrodes arranged in each heat generating block.

FIG. 17A is a plan view of the back surface layer 1 of the heater 1700. The conductor 1703 and the heating element (1704, 1705) are divided into three in the longitudinal direction of the heater. Electric power is supplied from the electrodes E1 and E2 to the heating elements 1704a and 1705a, from the electrodes E3 and E4 to the heating elements 1704b and 1705b, and from the electrodes E5 and E6 to the heating elements 1704c and 1705c.

The electrodes E1, E2, E3, E4, E5, and E6 are all at the same potential, and the electrodes E11, E12, E13, E14, E21, E22, E23, and E24 are all at the same potential. The potential distribution of the conductors 1701 and 1703 when a voltage of + 100V is applied to the electrodes E1, E2, E3, E4, E5 and E6 and a voltage of 0V is applied to the electrodes E11, E12, E13, E14, E21, E22, E23 and E24 is shown. It is shown in 17 (B). Since the potential distribution of the conductor 1702 is the same as that of the conductor 1701, the illustration is omitted. The potential distribution of the conductor 1703 is such that the positions of the six electrodes E1 to E6 are maximum, and the potentials are low between the electrodes. However, the amount of decrease in potential is smaller than that of the heater shown in FIG. 16 (A). This is because, for example, when considering the path of the current flowing from the electrodes E1 to E11, the distance between the electrodes E1 and E11 is shortened by arranging the two electrodes E1 and E2 in the block of the conductor 1703a. That is, the apparent resistance value of the conductor 1703a is reduced in the current paths of the electrodes E1 and E11, so that the amount of decrease in the potential of the conductor 1703a is reduced. Similarly, by arranging a plurality of electrodes (E11, E12, E13, E14) on the conductor 1701, the unevenness of the potential of the conductor 1701 is reduced.

Therefore, the potential difference between the conductors 1703 and 1701 shown by the broken line in FIG. 17B is 99 V at the maximum and 98 V at the minimum, and the range of the potential difference is also small. As described above, if a plurality of electrodes having the same potential are provided in one heat generation block, unevenness of the potential difference in the longitudinal direction of the heater can be suppressed. As a result, the voltage applied to the heating elements 1704 and 1705 is made uniform in the longitudinal direction of the heater, so that uneven heat generation of the heater is suppressed.

(Example 9)
FIG. 18 is a diagram for explaining the configuration of the heater 1800 applicable to the ninth embodiment. The heating elements 1804 and 1805 of the heater 1800 are continuous (not divided) in the longitudinal direction of the heater.

FIG. 18A is a plan view of the back surface layer 1 of the heater 1800. The conductor 1803 is divided into three in the longitudinal direction, and power is supplied to the conductor 1803a from the electrode E1, the conductor 1803b from the electrode E2, and the conductor 1803c from the electrode E3.

FIG. 18B shows the potential distributions of the heating elements 1804, 1805, and the conductors 1801, 1802 when a voltage of + 100 V was applied to the electrodes E1, E2, E3 of the heater 1800 and a voltage of 0 V was applied to the electrodes E4a, E4b. The potential distributions of the heating elements 1804 and 1805 are the potential distributions at the positions of the broken lines A and B in FIG. 18 (A). In this embodiment, since the heating elements 1804 and 1805 are not divided, the potential at the positions of the heating elements 1804 and 1805 corresponding to the divided positions of the conductor 1803 does not become 0V. Therefore, the heating elements 1804 and 1805 continuously generate heat in the longitudinal direction, and there is no region where the heat generation amount becomes 0, so that the heat generation distribution of the heater becomes more uniform.

(Example 10)
FIG. 19 is a diagram illustrating a configuration of a heater 1900A and a heater 1900B applicable to the tenth embodiment. FIG. 19A shows the back surface layer 1 of the heater 1900A, and the conductor 1903A is divided in the longitudinal direction of the heater. The boundary between the conductor 1903Aa and the conductor 1903Ab is slanted with respect to the longitudinal direction of the heater and the transport direction of the recording material. Further, the boundary between the conductor 1903Ab and the conductor 1903Ac is also slanted with respect to the longitudinal direction of the heater and the transport direction of the recording material.

Here, the heating element 1904A and the heating element 1905A are not divided in the longitudinal direction. However, as described in Example 9, the amount of heat generated is reduced in the portion where the heating element and the divided gap region of the conductor 1903A come into contact with each other. However, the positions of the heating element 1904A and the heating element 1905A where the amount of heat generated is reduced are offset in the longitudinal direction of the heater. This is because the dividing line of the conductor 1903A is slanted.

Therefore, the portion where the heating amount of the heating element 1904A and the heating element 1905A is reduced is displaced in the longitudinal direction, so that the heat generation distribution of the entire heater can be made more uniform.

As shown in FIG. 19B, the conductor 1903B may be divided into hook shapes. Since the configuration other than the shape of the conductor 1903B is the same as that shown in FIG. 19A, detailed description thereof will be omitted.

(Example 11)
FIG. 20 is a diagram for explaining the configuration of the heater 2000 applicable to the eleventh embodiment. The heater 2000 shown in FIG. 20 is the same as the tenth embodiment in that the heating element is not divided and each block is formed by dividing the conductor. However, the difference is that the electrodes are provided outside the region where the heating element is provided (the maximum size paper passing region) in the longitudinal direction of the heater.

FIG. 20A is a cross-sectional view of the heater 2000. As shown in FIG. 20A, the heater 2000 has a first conductor 2001, a second conductor 2003, and a heating element 2004 in the layer 1 on the sliding surface side of the substrate 2010.

FIG. 20B shows a plan view of the sliding surface layer 1. As shown in this figure, the heating elements 2004 and 2005 are not divided in the longitudinal direction of the heater. Further, the conductors 2001 and 2002 are divided into three in the longitudinal direction of the heater. The electrodes E1, E2, E3, and E4 connected to the conductors 2001, 2002, and 2003 are arranged outside the recording material passing region. In this heater as well, the direction of the current flowing through the heating element is parallel to the recording material transport direction. The sliding surface layer 2 (surface protective layer 2012) is an insulating glass layer for protecting the conductor and the heating element and improving the slidability with the film 202. The split positions of the conductors 2001a and 2001b and the split positions of the conductors 2002a and 2002b may be different in the longitudinal direction of the heater. The relationship between the split positions of the conductors 2001b and 2001c and the split positions of the conductors 2002b and 2002c is the same.

300 Heater 301 (301a, 301b) First conductor 302 Heating element 302-1 (302a-1, 302b-1) First heating block 302-2 (302a-2, 302b-2) Second heating block 302 -3 (302a-3, 302b-3) Third heating block 303 (303-1, 303-2, 303-3) Second conductor E4-1, E4-2 Electrodes E1, E2, first conductor E3 Electrode of 2nd conductor 200 Image heating device 400 Control circuit

Claims (19)

With an endless belt,
The substrate, the first conductor provided on the substrate along the longitudinal direction of the substrate, and the first conductor on the substrate at different positions in the lateral direction of the substrate along the longitudinal direction. A second conductor provided, and heat generated by the electric power provided between the first conductor and the second conductor and supplied via the first conductor and the second conductor. A heater that has a body and is in contact with the inner surface of the endless belt.
An electric contact for contacting the electrode of the heater and supplying electric power to the heating element, and
In an image heating device that heats an image formed on a recording material.
The heater is an electrode having a plurality of independently controllable heat-generating blocks composed of a pair of the first conductor, the second conductor, and the heating element in the longitudinal direction, and corresponding to each of the heat-generating blocks. What is the surface of the heater in contact with the endless belt in the region where the heating element is provided in the longitudinal direction at least one of the electrodes for the second conductor that is directly connected to the second conductor ? It is provided on the opposite side and
The electric contact that contacts the electrode for the second conductor is arranged so as to face the opposite surface of the heater .
The first conductors of the plurality of heat generation blocks are connected to each other and are common to the plurality of heat generation blocks.
Two electrodes for the first conductor that are directly connected to the common first conductor are provided, and one of the electrodes for the first conductor is a region where the heating element is provided in the longitudinal direction. It is provided that the electrode is provided outside one end and the other electrode for the first conductor is provided outside the other end of the region where the heating element is provided in the longitudinal direction. Characteristic image heating device. The image heating device according to claim 1, wherein the heating element has a positive resistance temperature characteristic. A plurality of the heating elements are electrically connected in parallel to the first conductor and the second conductor in at least one heating block, and the plurality of heating elements connected in parallel are the same. The image heating device according to claim 1 or 2, wherein the heating elements are arranged at an angle with respect to the longitudinal direction and the lateral direction of the heater, and the heating elements overlap in the longitudinal direction. The image heating device according to any one of claims 1 to 3, wherein the heat generation block is provided on the opposite surface of the heater. The heat generation block is provided on the side of the surface of the heater in contact with the endless belt, and the electrode for the second conductor in contact with the electric contact is provided through a through hole provided in the substrate. The image heating device according to any one of claims 1 to 3, wherein the image heating device is electrically connected to the second conductor in the heat generating block. Each of the heat generating blocks has two heating elements in the transport direction of the recording material, and a second conductor common to the two heating elements is provided between the two heating elements. The image heating device according to any one of claims 1 to 5. Claim 1 is characterized in that it has a plurality of temperature detection elements corresponding to the plurality of heat generation blocks, and the power supplied to the plurality of heat generation blocks is controlled according to the detection temperatures of the plurality of temperature detection elements. 6. The image heating device according to any one of 6 . The electrode for the second conductor corresponding to each heat generation block is provided at a position closer to the center of the heater than the center of the heat generation block corresponding to the electrode for each second conductor in the longitudinal direction. The image heating device according to any one of claims 1 to 7, wherein the image heating device is characterized by the above. The image heating device according to any one of claims 1 to 8, wherein the second conductor in each heat generating block is provided with electrodes for a plurality of second conductors . The image heating device according to any one of claims 1 to 9, wherein the heating elements of adjacent heating blocks are connected to each other. The sixth aspect of the present invention is characterized in that the common second conductor is divided between adjacent heat generating blocks, and the boundary line of the division is inclined with respect to the longitudinal direction and the transport direction of the recording material. The image heating device described. With the board
A first conductor provided on the substrate along the longitudinal direction of the substrate , and
A second conductor provided on the substrate along the longitudinal direction at a position different from that of the first conductor in the lateral direction of the substrate.
A heating element provided between the first conductor and the second conductor and generating heat by electric power supplied via the first conductor and the second conductor.
In a heater with
The heater is an electrode having a plurality of independently controllable heat-generating blocks composed of a pair of the first conductor, the second conductor, and the heating element in the longitudinal direction, and corresponding to each of the heat-generating blocks. At least one of the electrodes for the second conductor, which is directly connected to the second conductor , is provided in the region where the heating element is provided in the longitudinal direction .
The first conductors of the plurality of heat generation blocks are connected to each other and are common to the plurality of heat generation blocks.
Two electrodes for the first conductor that are directly connected to the common first conductor are provided, and one of the electrodes for the first conductor is a region where the heating element is provided in the longitudinal direction. It is provided that the electrode is provided outside one end and the other electrode for the first conductor is provided outside the other end of the region where the heating element is provided in the longitudinal direction. Characterized heater. The heater according to claim 12, wherein the heating element has a positive resistance temperature characteristic. A plurality of the heating elements are electrically connected in parallel to the first conductor and the second conductor in at least one heating block, and the plurality of heating elements connected in parallel are the same. The heater according to claim 12 or 13, wherein the heating elements are arranged at an angle with respect to the longitudinal direction and the lateral direction of the heater, and the heating elements overlap in the longitudinal direction. Each of the heat generating blocks has two heating elements in the transport direction of the recording material, and a second conductor common to the two heating elements is provided between the two heating elements. The heater according to any one of claims 12 to 14. The electrode for the second conductor corresponding to each heat generation block is provided at a position closer to the center of the heater than the center of the heat generation block corresponding to the electrode for each second conductor in the longitudinal direction. The heater according to any one of claims 12 to 15, wherein the heater is provided. The heater according to any one of claims 12 to 16, wherein the second conductor in each heat generating block is provided with electrodes for a plurality of second conductors . The heater according to any one of claims 12 to 17, wherein the heating elements of adjacent heating blocks are connected to each other. 15 . The heater described.

Images