JP7738828B2 - Heater and image forming apparatus - Google Patents

Description

Embodiments of the present invention relate to a heater and an image forming apparatus.

Image forming devices such as copiers and printers are equipped with heaters for fixing toner. Heaters are also installed in print/erase devices installed in rewritable card readers/writers and the like. Typically, such heaters have a long substrate, a heating element mounted on one side of the substrate and extending in the longitudinal direction of the substrate, and a pair of terminals electrically connected to each end of the heating element. Each of the pair of terminals is then electrically connected to a control circuit or the like installed outside the heater via a harness (connector and wiring). As a result, a harness must be connected to each end of the long heater, making it difficult to reduce the space, resources, and costs of the harness.

In this case, if a wiring pattern extending along the heating element is provided on the surface of the board where the heating element is provided, a pair of terminals can be placed on one end of the long board. In this way, a harness can be connected to one end of the long board. This allows for space-saving, resource-saving, and cost-reducing harnesses.

However, this approach requires arranging the heating element and wiring pattern side by side in the short direction (width) of the long substrate. This increases the short dimension (width) of the substrate, making it difficult to miniaturize the heater.

Therefore, there was a need to develop a technology that would allow terminals to be provided on one end of a board in the longitudinal direction using a simple configuration.

Japanese Patent Application Publication No. 02-65086

The problem that this invention aims to solve is to provide a heater and an image forming apparatus that have a simple configuration and that can provide a terminal on one end of the substrate in the longitudinal direction.

The heater according to this embodiment comprises a conductive substrate extending in one direction; a first insulating portion provided on a first surface of the substrate; a heating element provided on the first insulating portion and extending in the longitudinal direction of the substrate; a terminal provided on the first insulating portion, electrically connected to the heating element, and provided near one end of the substrate in the longitudinal direction of the substrate; wiring provided on the first insulating portion, electrically connected to the heating element and the conductive substrate, and provided near the other end of the substrate in the longitudinal direction of the substrate; and a second insulating portion provided on a second surface of the substrate opposite the first surface, and having insulating properties. The portion of the second surface near the end of the substrate on which the terminal is provided is exposed from the second insulating portion.

Embodiments of the present invention provide a heater and an image forming apparatus that have a simple configuration and can provide a terminal on one end of the substrate in the longitudinal direction.

FIG. 2 is a schematic diagram of the heater according to the present embodiment, viewed from one side in the Z direction. FIG. 10 is a schematic diagram of the heater as viewed from the other side in the Z direction. 2 is a schematic cross-sectional view of the heater taken along line AA in FIG. 1. FIG. 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention; FIG. 2 is a schematic diagram illustrating a fixing unit.

Embodiments will be illustrated below with reference to the drawings. Note that in each drawing, similar components are given the same reference numerals and detailed explanations will be omitted where appropriate. Also, the arrows X, Y, and Z in each drawing represent three mutually perpendicular directions. For example, the longitudinal direction of the substrate is the X direction, the lateral direction (width direction) of the substrate is the Y direction, and the direction perpendicular to the surface of the substrate is the Z direction.

(heater)
FIG. 1 is a schematic diagram of a heater 1 according to this embodiment, viewed from one side in the Z direction.
FIG. 2 is a schematic diagram of the heater 1 as viewed from the other side in the Z direction.
FIG. 3 is a schematic cross-sectional view of the heater 1 taken along line AA in FIG.
1 to 3, the heater 1 includes, for example, a substrate 10, an insulating portion 21 (corresponding to an example of a first insulating portion), an insulating portion 22 (corresponding to an example of a second insulating portion), a heating element 30, a wiring portion 41, wiring 42, and a protective portion 50. The insulating portion 21, the heating element 30, the wiring portion 41, wiring 42, and the protective portion 50 are provided on one surface 10a of the substrate 10 in the Z direction. The insulating portion 22 is provided on the other surface 10b of the substrate 10 in the Z direction.

Substrate 10 is plate-shaped and has surface 10a (an example of a first surface) and surface 10b (an example of a second surface) opposite surface 10a. Substrate 10 has a shape that extends in one direction (e.g., the X direction). The planar shape of substrate 10 is, for example, an elongated rectangle. The thickness of substrate 10 is, for example, approximately 0.5 mm to 1.0 mm. The width dimension W (short-side dimension; Y-direction dimension) of substrate 10 is, for example, approximately 5 mm to 15 mm. The length L (longitudinal dimension; X-direction dimension) of substrate 10 can be changed as appropriate depending on the size of the object to be heated (e.g., paper), etc.

The substrate 10 is made of a heat-resistant and electrically conductive material. Generally, substrates are made of ceramics such as aluminum oxide, but the heater 1 of this embodiment is provided with a substrate 10 that includes a metal. The metal can be, for example, stainless steel, an aluminum alloy, or the like.

As shown in Figures 1 and 3, the insulating portion 21 has insulating properties and is provided on the surface 10a of the substrate 10. The insulating portion 21 can be provided, for example, to cover the surface 10a of the substrate 10. The insulating portion 21 is provided to insulate the conductive substrate 10 from the heating element 30, the wiring portion 41, and the wiring 42. Therefore, the insulating portion 21 is provided between the substrate 10 and the heating element 30, the wiring portion 41, and the wiring 42. The insulating portion 21 can be formed, for example, from an inorganic material such as ceramic or glass material. The insulating portion 21 can be formed, for example, by thermal spraying or firing.

The heating element 30 converts the applied power into heat (Joule heat) and is provided on the insulating part 21 (on the surface of the insulating part 21 opposite to the substrate 10 side).
The heating element 30 extends, for example, in the X direction. For example, one heating element 30 can be provided at the center of the substrate 10 in the Y direction.
The heating element 30 can be formed using, for example, ruthenium oxide (RuO ₂ ), a silver-palladium (Ag—Pd) alloy, etc. The heating element 30 can be formed, for example, by applying a paste-like material onto the insulating part 21 using a screen printing method or the like, and then hardening it using a baking method or the like.

The wiring portion 41 is provided, for example, on the insulating portion 21. The wiring portion 41 has, for example, a terminal 41a and a wire 41b.
For example, the terminal 41a is electrically connected to the heating element 30 via a wiring 41b. For example, the terminal 41a is provided near one end 10c of the substrate 10 in the X direction.

Wiring 41b electrically connects terminal 41a and heating element 30. One end of wiring 41b is electrically connected to terminal 41a. The other end of wiring 41b is electrically connected to heating element 30.

The terminals 41a and wiring 41b are formed using a material containing, for example, silver or copper. For example, the terminals 41a and wiring 41b can be formed by applying a paste-like material onto the insulating portion 21 using a method such as screen printing, and then hardening it using a method such as baking.

The wiring 42 is provided, for example, on the insulating portion 21. The wiring 42 is electrically connected, for example, to the heating element 30 and the conductive substrate 10. For example, the wiring 42 is provided near the other end 10d of the substrate 10 in the X direction. For example, one end of the wiring 42 is electrically connected to the heating element 30. The other end of the wiring 42 is electrically connected to the substrate 10 via a hole or notch provided in the insulating portion 21. Note that the vicinity of the end 10d on the surface 10a of the substrate 10 may be exposed from the insulating portion 21, and the other end of the wiring 42 may be electrically connected to the surface 10a.

The wiring 42 is formed using a material containing, for example, silver or copper. For example, the wiring 42 can be formed by applying a paste-like material onto the insulating portion 21 using a method such as screen printing, and then hardening it using a method such as baking.

The protective portion 50 is provided, for example, on the insulating portion 21 and extends in the X direction. The protective portion 50 covers, for example, the heating element 30 and the wiring 41b. However, the terminal 41a is exposed from the protective portion 50. For example, as shown in FIG. 1, in the X direction, the distance L1 between the end 10c of the substrate 10 and the end of the protective portion 50 is greater than the distance L2 between the end 10c of the substrate 10 and the end of the terminal 41a on the protective portion 50 side. If the terminal 41a is exposed from the protective portion 50, a harness connector can be attached to the terminal 41a.

The protective portion 50 has functions such as insulating the heating element 30 and wiring 41b, transferring heat generated in the heating element 30 to the outside, and protecting the heating element 30 and wiring 41b from external forces, corrosive gases, and the like. The protective portion 50 is formed from a material that is heat-resistant and insulating, and has high chemical stability and thermal conductivity. The protective portion 50 is formed from an inorganic material such as ceramic or glass. In this case, the protective portion 50 can also be formed using a glass material to which a filler containing a material with high thermal conductivity, such as aluminum oxide, has been added. The thermal conductivity of the glass material to which a filler has been added can be, for example, 2 [W/(m·K)] or more.

The protective portion 50 can be formed, for example, by applying a paste-like material onto the insulating portion 21, heating element 30, wiring 41b, and wiring 42 using a method such as screen printing, and then hardening it using a method such as baking.

As shown in Figures 2 and 3, the insulating portion 22 is insulating and is provided on the surface 10b of the substrate 10. The insulating portion 22 can be provided, for example, to cover the surface 10b of the substrate 10. However, the vicinity of the end 10c of the surface 10b of the substrate 10, on which the terminal 41a of the substrate 10 is provided, is exposed from the insulating portion 22. If the vicinity of the end 10c of the surface 10b of the substrate 10 is exposed from the insulating portion 22, a harness connector can be attached to the conductive substrate 10.

For example, in the X direction, the distance L3 between the end 10c of the substrate 10 and the end of the insulating portion 22 can be greater than the distance L2 between the end 10c of the substrate 10 and the end of the terminal 41a on the protective portion 50 side. For example, the distance L3 may be the same as the distance L1 between the end 10c of the substrate 10 and the end of the protective portion 50.

The insulating portion 22 is provided to insulate the conductive surface 10b of the substrate 10. The thickness, material, and formation method of the insulating portion 22 can be the same as, for example, the thickness, material, and formation method of the insulating portion 21 described above.

The thickness of insulating part 22 can also be made thicker than the thickness of insulating part 21. For example, when heater 1 is used or manufactured (for example, when protective part 50 is baked), thermal stress occurs due to differences in the thermal expansion coefficients of the materials. This thermal stress may cause warping of heater 1. If heater 1 warps, the distance between heater 1 and the object to be heated may vary, resulting in uneven heating of the object to be heated.

In this case, the thermal stress generated by the substrate 10, the insulating portion 21, and the protective portion 50 on the side of the substrate 10's surface 10a can be offset by the thermal stress generated by the substrate 10 and the insulating portion 22 on the side of the substrate 10's surface 10b. If the thermal stresses are offset, the occurrence of warping in the heater 1 can be suppressed. In this case, if the thickness of the insulating portion 22 is increased, the value of the thermal stress generated on the side of the substrate 10's surface 10b can be made closer to the value of the thermal stress generated on the side of the substrate 10's surface 10a. Therefore, the occurrence of warping in the heater 1 can be more effectively suppressed. For example, the thickness of the insulating portion 22 can be approximately the sum of the thicknesses of the insulating portion 21 and the protective portion 50.

The heater 1 may also be provided with a detection unit that detects the temperature of the heating element 30. The detection unit may be, for example, a thermistor. The detection unit may be provided on at least one of the surface 10a side of the substrate 10 and the surface 10b side of the substrate 10.

In recent years, there has been a demand for smaller heaters, and for the harnesses (connectors and wiring) connected to heaters to be more space-saving, resource-efficient, and cost-effective. A typical heater has two terminals electrically connected to one end of a heating element extending in the longitudinal direction of the board, and another terminal electrically connected to the other end of the heating element. In such heaters, the harness is connected to both ends of the long board, making it difficult to reduce the space, resources, and cost of the harness.

Also proposed is a heater having a terminal electrically connected to one end of a heating element extending in the longitudinal direction of a substrate and a terminal electrically connected to the other end of the heating element via a wiring pattern. Such a heater allows a harness to be connected to one end of a long substrate. This allows for space-saving, resource-saving, and cost-effective harnesses.
However, in such a heater, the heating element and the wiring pattern are arranged side by side in the short side direction (width direction) of the substrate, which increases the width of the substrate and makes it difficult to miniaturize the heater.

In contrast, in the heater 1 according to this embodiment, a terminal 41a electrically connected to one end of the heating element 30 is provided near one end 10c of the substrate 10. The other end of the heating element 30 is electrically connected to the conductive substrate 10. The surface 10b of the substrate 10 near the end 10c serves as a terminal. In other words, the conductive substrate 10 functions as both a wiring pattern and a terminal.

In this way, terminals can be provided at one end of the board 10 in the longitudinal direction with a simple configuration. This allows for space-saving, resource-saving, and cost-reducing harnesses, while also reducing the width W of the board 10.

(Image forming apparatus)
Next, an example of the image forming apparatus 100 according to the present embodiment will be described.
In the following, a case where the image forming apparatus 100 is a copier will be described as an example. However, the image forming apparatus 100 is not limited to a copier, and may be any apparatus provided with a heater for fixing toner. For example, the image forming apparatus 100 may be a printer or the like. It may also be a rewritable card reader/writer or the like.

FIG. 4 is a schematic diagram illustrating the image forming apparatus 100 according to the present embodiment.
FIG. 5 is a schematic diagram illustrating the fixing unit 200. As shown in FIG.
As shown in FIG. 4, the image forming apparatus 100 includes, for example, a frame 110, an illumination unit 120, an imaging element 130, a photosensitive drum 140, a charging unit 150, a discharging unit 151, a developing unit 160, a cleaner 170, a storage unit 180, a conveying unit 190, a fixing unit 200, and a controller 210.

The frame 110 is box-shaped and houses an illumination unit 120, an imaging element 130, a photosensitive drum 140, a charging unit 150, a developing unit 160, a cleaner 170, part of a storage unit 180, a conveying unit 190, a fixing unit 200, and a controller 210 inside.
A window 111 made of a light-transmitting material such as glass may be provided on the top surface of the frame 110. An original 500 to be copied is placed on the window 111. A moving unit for moving the position of the original 500 may also be provided.

The illumination unit 120 is provided near the window 111. The illumination unit 120 has a light source 121 such as a lamp, and a reflecting mirror 122, for example.
The imaging element 130 is provided near the window 111 .
The photosensitive drum 140 is provided below the illumination unit 120 and the imaging element 130. The photosensitive drum 140 is rotatable. On the surface of the photosensitive drum 140, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer is provided.
The charging unit 150 , the discharging unit 151 , the developing unit 160 , and the cleaner 170 are provided around the photosensitive drum 140 .

The storage section 180 has, for example, a cassette 181 and a tray 182. The cassette 181 is removably attached to one side of the frame 110. The tray 182 is provided on the side of the frame 110 opposite the side on which the cassette 181 is attached. The cassette 181 stores paper 510 (e.g., blank paper) before copying. The tray 182 stores paper 511 on which a copy image 511a has been fixed.

The transport unit 190 is provided below the photosensitive drum 140. The transport unit 190 transports the paper 510 between the cassette 181 and the tray 182. The transport unit 190 has, for example, a guide 191 that supports the transported paper 510, and transport rollers 192-194 that transport the paper 510. The transport unit 190 can also be provided with a motor that rotates the transport rollers 192-194.

The fixing unit 200 is provided downstream of the photosensitive drum 140 (on the tray 182 side).
As shown in FIG. 5, the fixing unit 200 includes, for example, a heater 1, a stay 201, a film belt 202, and a pressure roller 203.
The heater 1 is attached to the stay 201 on the side of the conveyance line for the paper 510. The heater 1 can be embedded in the stay 201. For example, the side of the heater 1 on which the protective portion 50 is provided can be exposed from the stay 201.

The film belt 202 covers the stay 201 on which the heater 1 is mounted. The film belt 202 can be made from a heat-resistant resin such as polyimide.

The pressure roller 203 is disposed opposite the stay 201. The pressure roller 203 has, for example, a core 203a, a drive shaft 203b, and an elastic portion 203c. The drive shaft 203b protrudes from the end of the core 203a and is connected to a drive device such as a motor. The elastic portion 203c is disposed on the outer surface of the core 203a. The elastic portion 203c is formed from a heat-resistant elastic material. The elastic portion 203c can be formed from, for example, silicone resin.

The controller 210 is provided inside the frame 110. The controller 210 has, for example, a calculation unit such as a CPU (Central Processing Unit) and a storage unit in which a control program is stored. The calculation unit controls the operation of each element provided in the image forming apparatus 100 based on the control program stored in the storage unit. The controller 210 may also include an operation unit through which the user inputs copying conditions, etc., and a display unit that displays the operating status and abnormality indications, etc.
It should be noted that the control of each element provided in the image forming apparatus 100 can be performed using known techniques, and therefore detailed description thereof will be omitted.

The above describes several embodiments of the present invention, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

1 heater, 10 substrate, 10a surface, 10b surface, 10c end, 10d end, 21 insulating portion, 22 insulating portion, 30 heating element, 41 wiring portion, 41a terminal, 41b wiring, 42 wiring, 50 protective portion, 100 image forming device, 200 fixing portion

Claims (4)

a substrate having electrical conductivity and a shape extending in one direction;
a first insulating portion provided on a first surface of the substrate and having insulating properties;
a heating element provided on the first insulating portion and extending in the longitudinal direction of the substrate;
a terminal provided on the first insulating portion, electrically connected to the heating element, and provided near one end of the substrate in the longitudinal direction of the substrate;
a wiring provided on the first insulating portion, electrically connected to the heating element and the conductive substrate, and provided near the other end of the substrate in the longitudinal direction of the substrate;
a second insulating portion having insulating properties and provided on a second surface of the substrate opposite to the first surface;
Equipped with
The heater is exposed from the second insulating portion near the end of the second surface on the side where the terminal of the substrate is provided. a protective portion provided on the first insulating portion and covering the heating element;
The heater according to claim 1 , wherein the terminals are exposed from the protective portion. A heater as described in claim 1 or 2, wherein one heating element is provided at the center of the substrate in the short-side direction of the substrate. An image forming apparatus equipped with the heater described in any one of claims 1 to 3.