Patent Application
20200301329
The present invention relates to an image heating device such as a fixing device installed in an image forming apparatus such as a copying machine or a printer using an electrophotographic method or an electrostatic recording method, a gloss-imparting device that increases the gloss of a toner image by reheating the fixed toner image on a recording material, and the like.
A conventional image heating device provided in an image forming apparatus includes a tubular film called an endless belt or an endless film, a flat heater in contact with an inner surface of the film, and a roller for forming, together with the heater, a nip portion through the film. The heater of this image heating device is configured of an insulating ceramic substrate, a heating resistor formed by printing on the substrate, and a temperature detecting element. A configuration in which power supply to a heating resistor is controlled so that a nip portion assumes a predetermined temperature (appropriate toner image heating temperature) based on temperature information detected by the temperature detecting element has been proposed (Japanese Patent Application Publication No. 2002-373767). Here, where small-size paper is continuously printed in the image forming apparatus equipped with such image heating device, a phenomenon that the temperature of a region where the paper does not pass in the longitudinal direction of the nip portion gradually rises (non-paper passing portion temperature rise) may occur. Where the temperature of the non-paper passing portion becomes too high, components in the apparatus may be damaged.
A method in which a plurality of temperature detecting elements is provided on a heater, and separate elements are used for temperature control and for temperature detection of a non-paper passing portion is used as a means for solving the above problem. However, as the number of temperature detecting elements formed on a ceramic substrate increases, the number of conductors connected to the temperature detecting element increases, and the space between the conductors becomes smaller in the ceramic substrate of a limited size. Furthermore, when connecting a conductor to an element or metal such as a temperature detecting element or an electrode, the conductor material to be used needs to be changed depending on the compatibility of the conductor material of the conductor and the element or metal to be connected thereto (abnormal change in element characteristics, poor contact, and the like). When the conductor material to be used is expensive, a conductor pattern is formed of two or more types of conductor materials, and a distance between adjacent conductors cannot be ensured due to a displacement occurring when forming each conductor. Where an appropriate distance cannot be ensured between adjacent conductors, there is a concern that problems such as short-circuiting, migration, and poor voltage resistance between adjacent conductors may occur.
An object of the present invention is to provide a technique capable of reducing the size of a heater while suppressing short-circuiting, migration, and poor voltage resistance between adjacent conductors.
To achieve the above object, the heater of the present invention includes:
a substrate;
a heating resistor provided on the substrate, and
a plurality of electric conductors provided on the substrate,
wherein the plurality of electric conductors include a conductor group A including a plurality of first electric conductors and a conductor group B including a plurality of second electric conductors;
wherein the plurality of first electric conductors each have a first portion having a width W1 and a second portion having a width W2 smaller than the width W1 and are provided on the substrate to be arranged side by side in a width direction of the substrate; and
wherein the plurality of second electric conductors each have a width W3 larger than the width W2 and are provided on the substrate to be arranged side by side in the width direction so as to partially overlap the second portion.
To achieve the above object, the image heating device of the present invention includes:
a heating unit having a heater for heating an image formed on a recording material, wherein the heater has a substrate, a heating resistor provided on the substrate, and a plurality of electric conductors provided on the substrate,
wherein the plurality of first electric conductors each have a first portion having a width W1 and a second portion having a width W2 smaller than the width W1 and are provided on the substrate to be arranged side by side in a width direction of the substrate; and
wherein the plurality of second electric conductors each have a width W3 larger than the width W2 and are provided on the substrate to be arranged side by side in the width direction so as to partially overlap the second portion.
To achieve the above object, the image forming apparatus of the present invention includes:
an image forming unit that forms an image on a recording material; and
a fixing unit for heating the image to fix the image on the recording material,
wherein the fixing unit is an image heating device that has a heating unit having a heater for heating an image formed on a recording material, the heater has a substrate, a heating resistor provided on the substrate, and a plurality of electric conductors provided on the substrate, and heats an image formed on a recording material using heat of the heater;
wherein the plurality of electric conductors include a conductor group A including a plurality of first electric conductors and a conductor group B including a plurality of second electric conductors;
wherein the plurality of first electric conductors each have a first portion having a width W1 and a second portion having a width W2 smaller than the width W1, are provided on the substrate to be arranged side by side in a width direction; and wherein the plurality of second electric conductors each have a width W3 larger than the width W2, are provided on the substrate to be arranged side by side in a width direction so as to partially overlap the second portion.
According to the present invention, it is possible to reduce the size of the heater while suppressing short-circuiting, migration, and poor voltage resistance between adjacent conductors.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, a description will be given, with reference to the drawings, of embodiments (examples) of the present invention. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments.
An image forming apparatus 10 includes a video controller 120 and a control unit 113. The video controller 120 serves as an acquisition unit for acquiring information on an image formed on a recording material and receives and processes image information and a print instruction transmitted from an external device such as a personal computer. The control unit 113 is connected to the video controller 120, and controls each unit constituting the image forming apparatus 10 according to an instruction from the video controller 120. Where the video controller 120 receives a print instruction from the external device, image formation is performed by the following operations.
Where a print signal is generated, a scanner unit 21 emits a laser beam modulated according to image information, and scans the surface of a photosensitive drum 19 charged to a predetermined polarity by a charging roller 16. As a result, an electrostatic latent image is formed on the photosensitive drum 19. By supplying toner from a developing roller 17 to the electrostatic latent image, the electrostatic latent image on the photosensitive drum 19 is developed as a toner image (toner image). Meanwhile, the recording material (recording paper) P loaded on a paper feed cassette 11 is fed one by one by a pickup roller 12 and is conveyed toward a registration roller pair 14 by a conveyance roller pair 13. Further, the recording material P is conveyed from the registration roller pair 14 to a transfer position at a timing when the toner image on the photosensitive drum 19 reaches a transfer position formed by the photosensitive drum 19 and a transfer roller 20. As the recording material P passes through the transfer position, the toner image on the photosensitive drum 19 is transferred to the recording material P. Thereafter, the recording material P is heated by a fixing device (image heating device) 100 as a fixing unit (image heating unit), 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 a tray above the image forming apparatus 10 by a pair of conveying rollers 26, 27. A drum cleaner 18 cleans toner remaining on the photosensitive drum 19. A paper feed tray 28 (manual tray) having a pair of recording material regulating plates adjustable in width according to the size of the recording material P is provided to accommodate recording materials P of sizes other than the standard size. The pickup roller 29 feeds the recording material P from the paper feed tray 28. The image forming apparatus 10 includes a motor 30 that drives the fixing device 100 and the like. A CPU 309 serving as a heater driving unit and a power supply control unit connected to a commercial AC power supply 300 controls power supply to the fixing device 100. The above-described photosensitive drum 19, charging roller 16, scanner unit 21, developing roller 17, and transfer roller 20 constitute an image forming unit that forms an unfixed image on the recording material P.
The film 102 is a heat-resistant film that is formed in a tubular shape and called an endless belt or an endless film, and the material of a base layer is a heat-resistant resin such as a polyimide or a metal such as stainless steel. Further, an elastic layer such as heat-resistant rubber may be provided on the surface of the film 102. The pressure roller 108 has a metal core 109 made of a material such as iron or aluminum, and an elastic layer 110 made of a material such as silicone rubber. The heater 200 is held by a holding member 101 made of a heat-resistant resin. The holding member 101 also has a guide function for guiding the rotation of the film 102. The metal stay 104 is configured to apply a pressure of a spring (not shown) to the holding member 101. The pressure roller 108 receives power from a drive source (not shown) and rotates in the direction of the arrow. The film 102 rotates following the rotation of the pressure roller 108. The recording paper P carrying the unfixed toner image is heated and fixed while being nipped and conveyed at the fixing nip portion N. A heating unit 220 being in contact with an inner surface of the film 102 includes the heater 200, the holding member 101, and the metal stay 104.
Here, since the conductors of the conductor groups A, B are simultaneously formed by printing for each of the conductor groups, where a shift occurs during the printing, the conductors of each of the conductor groups A and B are shifted in the same direction.
The dimensional relationship in the connection portion where the thermistor conductors A1, A2 and the conductors B1, B2 in the heater 200 shown in
The conductor groups A, B are arranged in the longitudinal direction of the substrate 201, and the conductors of the conductor groups A, B extend in the longitudinal direction of the substrate 201 at least at the connection portions. The width in the lateral direction orthogonal to the longitudinal direction of the substrate 201 is set so as to ensure a width that guarantees at least the minimum molding accuracy.
Further, the conductors of the conductor groups A, B are arranged in parallel in the respective conductor groups with an interval in the lateral direction of the substrate 201, and the conductors are arranged as densely as possible within a range where there is no influence of migration or the like with an adjacent conductor.
In the configuration of the present embodiment, the wiring direction for connection and extension of different conductors matches the longitudinal direction of the substrate 201, but such a configuration is not limiting. That is, in the configuration of the present embodiment, the conductor width of each conductor of the conductor groups A, B (the width in the direction orthogonal to the direction in which the conductors extend) matches the width of each conductor in the lateral direction of the substrate 201 at least at the connection portion, but this is not limiting for substrates of other configurations.
As shown in
Meanwhile, the conductors B1, B2 as the second electric conductors in the conductor group B which are simultaneously formed by printing at a timing different from that of the conductor group A have a conductor width of W3.
The timing of formation by printing may be such that the conductor group A is printed before the conductor group B, or the order of printing may be reversed.
In the configuration in which the conductor portion having the width W2 in the conductor group A and the conductor portion having the width W3 in the conductor group B overlap, the dimensional relationships between the widths W1, W2, and W3 are represented by the following Formulas 1 and 2.
W1>W2 (Formula 1)
W3>W2 (Formula 2)
The conductor configuration in the present example shown in
An arrangement example of the conductor group A and the conductor group B when a printing shift has occurred between the conductor group A and the conductor group B is shown in
As shown in
As shown in
Here, as shown in
ZW=(W3+W4)−(W2+W5+(W1−W2)/2)=W4−W5+(W1−W2)/2
Meanwhile, as shown in
ZWa=(W3+W4)−(W5+W1)=W4−W5
Since it follows from Formula 1 that W1>W2, the allowable printing shift ZW in the present embodiment is larger than the allowable printing shift ZWa in the configuration of the comparative example Therefore, as compared with the configuration of the comparative example, the configuration of the present embodiment can ensure the inter-conductor distance between of the conductor A1 and the adjacent conductor B2 even when a printing shift has occurred, and short-circuiting, migration, and poor voltage resistance between adjacent conductors can be prevented. That is, it is possible to reduce the size of the heater while suppressing short-circuiting, migration, and poor voltage resistance between adjacent conductors.
Here,
The effect of expanding the printing shift ZW according to the present embodiment can be effectively obtained in a configuration that satisfies the relationship of W1+W5>W4.
In addition, by setting the reference in the width direction of the portion having the width W1 portion and the portion having the width W2 in the conductors A1, A2 to be the same center reference, the distance between the adjacent conductor patterns can be ensured even when a printing shift in the width direction of the conductor groups A and B occurs in both directions.
Further, as shown in
The conductor group A may be formed of a material that is different from a material of the conductor group B, and such materials may be silver (Ag) and silver/palladium alloy (Ag/Pd). In this case, the materials to be used can be selected depending on the compatibility with electronic elements and metals such as thermistors and electrodes to be connected to the conductor groups A and B, and the occurrence of abnormal changes in element characteristics and poor contact can be suppressed.
Embodiment 2 of the present invention will be described with reference to
Embodiment 2 is configured, similarly to Embodiment 1, so that a portion of the conductor A having the width W2 in the overlapped portion of the conductor group A and the conductor group B is smaller than the portions of the conductor groups A, B having the width W1, W3. In the configuration of Embodiment 2, by contrast with Embodiment 1, each conductor in the conductor group A has a tapered portion that extends continuously and gradually narrows from the end part of the portion having the width W1 in the conductor, which faces the terminal of the conductor group B, toward the terminal of the conductor group B. The tapered portion has a portion having a width W2 in the middle thereof, and is configured to overlap with each conductor of the conductor group B on the tip side from the portion having the width W2.
Here, when a small width W2 of the conductor group A shown in
Meanwhile, with the configuration of Embodiment 2 shown in
Embodiment 3 of the present invention will be described with reference to
Embodiment 3 is configured, similarly to Embodiments 1 and 2, so that the width W2 of the conductor A in the overlapped portion of the conductor A and the conductor B is smaller than the widths W1, W3 in the conductors A, B. Further, the conductor group B is formed by printing at a conductor interval of a distance W4. The configuration of Embodiment 3 differs from those of Embodiments 1 and 2 in that the conductor group B is overlapped (covered) with glass 700 as an insulating protective layer.
The configuration of Embodiment 3 will be described with reference to
Here, when a printing shift occurs in the width direction between the conductor group A and the conductor group B, the inter-conductor distance between the conductor A1 overlapping with the conductor B1 and the adjacent conductor B2 is reduced, and migration may occur between the conductor A1 and the conductor B2. By contrast, in Embodiment 3, as shown in
Further, silver (Ag), which is the conductor material of the conductor group B, is disadvantageous from the viewpoint of migration, and therefore needs to be protected with glass. However, where the width W6 of the conductor group A can be ensured, no problem arises even without glass protection. Therefore, there is no migration problem even when a printing shift occurs, as shown in
The above embodiments can be combined with each other if possible.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-051895, filed on Mar. 19, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-051895 | Mar 2019 | JP | national |
