Energization cut-off device, image forming device, and electrical apparatus

Abstract

To provide an energization cut-off device that can surely cut off energization without performing complicated control.SOLUTION: An energization cut-off device comprises: a heat generation unit 45 that generates heat in an energization state; an energization cut-off unit 47 that cuts off the energization between terminals according to temperature; and a heat dissipation unit 46 that is in contact with the heat generation unit 45 to dissipate heat. The energization cut-off unit 47 is connected in series to the heat generation unit 45, is in contact with the heat dissipation unit 46, and when heated by the heat dissipated from the heat dissipation unit 46, cuts off the energization to a connected load.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a current interruption device that interrupts current flow, and to an image forming apparatus and an electrical device that include the current interruption device. [Background technology]

[0002] Conventionally, in a fixing device used in an electrophotographic image forming apparatus such as a copier or printer, a toner image is fixed by applying pressure and heat to a sheet of paper on which an unfixed toner image has been formed. The fixing device is provided with a heater for heating the sheet of paper, and a thermal fuse is attached as a countermeasure in case of an abnormality in the heater control. In this way, electronic devices have adopted a configuration in which a thermal fuse is installed near an electronic component that easily generates heat, and the circuit is shut off if the temperature rises abnormally (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-330665 Summary of the Invention [Problem to be solved by the invention]

[0004] In the mounting structure of a conventional thermal fuse, a through hole is provided in a substrate on which an electronic component is mounted, the electronic component is mounted on the surface side of the substrate across the through hole, the thermal fuse is mounted so that it enters the through hole via a thermally conductive resin, and the leads on both ends of the thermal fuse are connected to the wiring on the surface side of the substrate via through holes in the substrate.

[0005] However, in the conventional thermal fuse mounting structure, the thermal fuse is inserted so as to be embedded in the thermal conductive resin, which has the problem that the thermal fuse cannot be easily replaced. Therefore, there is a demand for a thermal fuse mounting method that has a simpler structure different from the conventional one and can reliably cut off the current.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a current interruption device, an image forming apparatus, and an electrical device that can reliably cut off current without performing complicated controls. [Means for solving the problem]

[0007] The current interruption device of the present disclosure comprises a heat-generating portion that generates heat when current is applied, a current interruption portion that interrupts current between terminals depending on the temperature, and a heat dissipation portion that dissipates heat by contacting the heat-generating portion, wherein the current interruption portion is connected in series with the heat-generating portion and is in contact with the heat dissipation portion, and when heated by heat dissipation from the heat dissipation portion, it interrupts current to the connected load.

[0008] In the current interruption device according to the present disclosure, the current interruption section may be configured to be in contact with the heat dissipation section via a heat conduction member that conducts heat.

[0009] In the current interrupting device according to the present disclosure, the current interrupting portion may have a terminal extending therefrom, and the heat dissipation portion may have a notch in a portion facing the terminal of the current interrupting portion.

[0010] In the current interrupting device according to the present disclosure, the current interrupting portion may have a terminal extending therefrom, and the terminal may be covered with an insulating member.

[0011] In the current interruption device according to the present disclosure, the heat dissipation portion may have a fixing portion that fixes the current interruption portion.

[0012] In the current interruption device according to the present disclosure, the heat generating portion and the current interruption portion may be arranged to face each other with the heat dissipation portion therebetween.

[0013] The image forming apparatus according to the present disclosure is characterized by including the power interruption device according to the present disclosure.

[0014] The electrical device according to the present disclosure is characterized by including the current interruption device according to the present disclosure. [Effects of the Invention]

[0015] According to the present disclosure, the current interruption unit is activated by heat transferred via the heat dissipation unit, so current can be reliably interrupted without the need for complicated control. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view showing a configuration of an image forming apparatus according to a first embodiment of the present disclosure. [Figure 2] FIG. 1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus. [Figure 3] 2 is a schematic side view showing a substrate on which a heat generating portion, a heat dissipating portion, and a current interrupting portion are mounted. FIG. [Figure 4] FIG. 10 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted in an image forming apparatus according to a second embodiment of the present disclosure. [Figure 5] FIG. 11 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted in an image forming apparatus according to a third embodiment of the present disclosure. [Figure 6] FIG. 11 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted in an image forming apparatus according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] (First embodiment) Hereinafter, an image forming apparatus according to a first embodiment of the present disclosure will be described with reference to the drawings.

[0018] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to a first embodiment of the present disclosure.

[0019] The image forming device 100 is a multifunction device having a copy function, a scanner function, a facsimile function, and a printer function, and transmits an image of a document read by the image reading device 130 to an external device, and forms an image of a document read by the image reading device 130 or an image received from an external device in color or monochrome on a recording medium such as paper.

[0020] An original transport device 110 that is supported so as to be able to open and close freely is provided above the image reading device 130. The original transport device 110 transports one or more originals one by one. The image reading device 130 scans a scanning optical system 130b to read an original placed on an original placement table 130a, or reads an original transported by the original transport device 110 to generate image data.

[0021] The image forming apparatus 100 includes a fixing device 1, a developing device 2, a photosensitive drum 3, a drum cleaning device 4, a charger 5, an intermediate transfer belt device 7, a secondary transfer device 11, an optical scanning device 12, and a paper feed section 18.

[0022] Image forming apparatus 100 handles image data corresponding to color images using black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (e.g., black). Image forming apparatus 100 is provided with four developing devices 2, four photosensitive drums 3, four drum cleaning devices 4, and four chargers 5 for forming four types of toner images, and four image stations Pa, Pb, Pc, and Pd are configured corresponding to black, cyan, magenta, and yellow, respectively.

[0023] The optical scanning device 12 exposes the surface of the photosensitive drum 3 to light to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image on the surface of the photosensitive drum 3. The drum cleaning device 4 removes and collects residual toner on the surface of the photosensitive drum 3. The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential. Through the series of operations described above, a toner image of each color is formed on the surface of each photosensitive drum 3.

[0024] The intermediate transfer belt device 7 includes an intermediate transfer roller 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 so as to form four types of toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photosensitive drum 3 onto the intermediate transfer belt 71, which moves around in a circular motion.

[0025] The intermediate transfer belt 71 is stretched over an intermediate transfer drive roller 72 and an intermediate transfer driven roller 73. In the image forming apparatus 100, the toner images of each color formed on the surface of each photosensitive drum 3 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 71. The cleaning device 9 removes and collects waste toner remaining on the surface of the intermediate transfer belt 71 without being transferred to paper.

[0026] The secondary transfer device 11 sandwiches and transports a sheet of paper transported through the paper transport path 21 in the transfer nip portion TN between the secondary transfer roller 11a and the intermediate transfer belt 71. When the sheet of paper passes through the transfer nip portion TN, the toner image on the surface of the intermediate transfer belt 71 is transferred onto the sheet of paper, and the sheet of paper is transported to the fixing device 1.

[0027] The fixing device 1 includes a fixing belt 31 that rotates around an axis and a pressure roller 32. The fixing device 1 sandwiches a sheet of paper onto which a toner image has been transferred in a nip portion N between the fixing belt 31 and the pressure roller 32, and applies heat and pressure to fix the toner image to the sheet. The fixing device 1 includes a heating section 33 (see FIG. 2, which will be described later) that heats the fixing belt 31.

[0028] The paper feed unit 18 includes a paper feed cassette that holds recording media (paper) used for image formation, and is provided below the optical scanning device 12. The paper is pulled out of the paper feed unit 18 by a pickup roller 16 and transported to a paper transport path 21. The paper transported to the paper transport path 21 passes through the secondary transfer device 11 and the fixing device 1, and is then discharged to a paper output tray 19 by a discharge roller 17.

[0029] Conveyance rollers 13, registration rollers 14, and discharge rollers 17 are arranged on paper transport path 21. Conveyance rollers 13 facilitate the transport of paper. Registration rollers 14 transport paper at a speed equal to the process speed at which an image is formed on the paper. Registration rollers 14 are provided between paper feed unit 18 and secondary transfer device 11, and adjust the timing of paper transport so that the toner image is transferred to the paper by secondary transfer device 11. For example, registration rollers 14 wait (temporarily stop) while clamping the paper transported from paper feed unit 18, and then start transporting the paper at a constant speed in synchronization with secondary transfer device 11.

[0030] When an image is to be formed on the back side of the paper in addition to the front side, the conveying direction of the paper is changed by discharge rollers 17, and the paper is conveyed to reversing conveying path 22. In reversing conveying path 22, the paper is guided up to registration rollers 14 in a reversed state by reversing conveying rollers 15. Image forming apparatus 100 forms an image on the back side of the paper guided to registration rollers 14 in the same manner as on the front side, and discharges the paper to discharge tray 19.

[0031] FIG. 2 is a schematic diagram showing the schematic configuration of the image forming apparatus.

[0032] Image forming apparatus 100 includes a power supply circuit 41 connected to an external power source, a conversion circuit 42 that converts AC input from the primary side to DC and outputs the converted DC from the secondary side, and a control unit 43 that controls the output from the secondary side of conversion circuit 42. Conversion circuit 42 and relay 44 are connected in parallel to the output of power supply circuit 41, and fixing device 1 is connected via a current interrupter including relay 44. Specifically, beyond relay 44, heat generating unit 45, current interrupter 47, and fixing device 1 are connected in series in this order. While FIG. 2 shows heating unit 33 provided in fixing device 1 as a load in image forming apparatus 100, this is not limiting, and output from power supply circuit 41 may be supplied to other components provided in image forming apparatus 100.

[0033] The conversion circuit 42 has a function of rectifying current and a function of transforming voltage, and is a circuit that combines electronic components such as diodes, coils, etc. The conversion circuit 42 may output not only electric power but also a signal based on the frequency of the output electric power to the control unit 43.

[0034] The relay 44 is a switch that switches between ON and OFF in response to an instruction from the control unit 43. The heat generating unit 45 is an electronic component that generates heat when energized, such as a triac, and is a switch that switches between ON and OFF in response to an instruction from the relay 44. The current interrupting unit 47 is a thermal fuse that is always ON, and interrupts the current between terminals depending on the temperature.

[0035] The heat generating portion 45 and the current breaking portion 47 are disposed in close proximity to each other via the heat dissipation portion 46. The heat dissipation portion 46 is, for example, a heat sink that dissipates heat by contacting the heat generating portion 45. The heat from the heat dissipation portion 46 is conducted to the current breaking portion 47.

[0036] Next, the structure in the vicinity of heat generating portion 45, heat dissipating portion 46, and current interrupting portion 47 will be described with reference to FIG.

[0037] Fig. 3 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted. Note that Fig. 3 shows only a portion of substrate 50, and other components not shown may be mounted on substrate 50.

[0038] The heat generating unit 45, the heat dissipation unit 46, and the current interruption unit 47 are mounted on the same substrate 50, and each unit is electrically connected as appropriate via wiring provided on the substrate 50. In the configuration shown in FIG. 3, the heat dissipation unit 46 is a box-shaped heat sink, with one side surface in contact with the main body (heat generating body 45a) of the heat generating unit 45 and the other side surface in contact with the main body (interruption body 47a) of the current interruption unit 47. A heat generating terminal 45b such as a lead extends from the heat generating body 45a, and the tip of the heat generating terminal 45b is mounted on the substrate 50. Similarly, a interruption terminal 47b such as a lead extends from the interruption body 47a, and the tip of the interruption terminal 47b is mounted on the substrate 50.

[0039] A heat-conducting member 48 that conducts heat is provided between the current-cutting section 47 and the side surface of the heat-dissipating section 46, and the current-cutting section 47 is in indirect contact with the heat-dissipating section 46 via the heat-conducting member 48. In this way, by sandwiching the heat-conducting member 48 between the current-cutting section 47 and the heat-dissipating section 46, a gap is provided between them to ensure an insulating distance, while also assisting the conduction of heat.

[0040] As described above, heat generating portion 45, heat dissipation portion 46, and current interruption portion 47 are arranged in close proximity, so that heat generated by heat generating portion 45 is transferred to current interruption portion 47 via heat dissipation portion 46. When current interruption portion 47 is heated and exceeds a predetermined temperature, it cuts off the current to the connected load. In this way, current interruption portion 47 is activated by the heat transferred via heat dissipation portion 46, so current can be reliably cut off without the need for complicated control.

[0041] (Second embodiment) Next, an image forming apparatus according to a second embodiment of the present disclosure will be described with reference to the drawings. Note that the second embodiment has substantially the same configuration as the first embodiment shown in Figures 1 to 3, so a description thereof will be omitted and only the differences will be described.

[0042] FIG. 4 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted in an image forming apparatus according to a second embodiment of the present disclosure.

[0043] The second embodiment differs from the first embodiment in the structure of the heat dissipation portion 46 facing the current breaker portion 47. Specifically, in this embodiment, no heat conduction member 48 is provided between the heat dissipation portion 46 and the current breaker portion 47, and the current breaker portion 47 (particularly, the breaker body 47a) is in direct contact with the side surface of the heat dissipation portion 46. In addition, a notch 46a is provided on the side surface of the heat dissipation portion 46 in a portion facing the breaker terminal 47b. In this way, by providing the notch 46a in the heat dissipation portion 46, it is possible to prevent the breaker terminal 47b from coming into contact with the heat dissipation portion 46 and causing a short circuit.

[0044] (Third embodiment) Next, an image forming apparatus according to a third embodiment of the present disclosure will be described with reference to the drawings. Note that the third embodiment has substantially the same configuration as the first and second embodiments shown in Figures 1 to 4, so a description thereof will be omitted and only the differences will be described.

[0045] FIG. 5 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted in an image forming apparatus according to a third embodiment of the present disclosure.

[0046] The third embodiment differs from the second embodiment in the configuration of the current interrupter 47. Specifically, in this embodiment, the heat dissipation portion 46 does not have a notch 46a, and the interrupter terminal 47b is covered with an insulating member 47c made of, for example, rubber. By providing the insulating member 47c that covers the interrupter terminal 47b in this manner, it is possible to prevent the interrupter terminal 47b from coming into contact with the heat dissipation portion 46 and causing a short circuit.

[0047] (Fourth embodiment) Next, an image forming apparatus according to a fourth embodiment of the present disclosure will be described with reference to the drawings. Note that the fourth embodiment has substantially the same configuration as the first to third embodiments shown in Figures 1 to 5, so a description thereof will be omitted and only the differences will be described.

[0048] FIG. 6 is a schematic side view showing a substrate on which a heat generating section, a heat dissipating section, and a current interrupting section are mounted in an image forming apparatus according to a fourth embodiment of the present disclosure.

[0049] The heat dissipation unit 46 is a plate-shaped heat sink standing vertically on the substrate 50, with the main body (heat-generating main body 45a) of the heat-generating unit 45 in contact with one surface and the main body (circuit-breaking main body 47a) of the current-breaking unit 47 in contact with the opposite surface. As shown in FIG. 6 , when the heat dissipation unit 46 is viewed from the side of the surface with which the current-breaking unit 47 is in contact, the heat-generating unit 45 is positioned so as to overlap with the current-breaking unit 47. In other words, the heat-generating unit 45 and the current-breaking unit 47 are positioned so as to face each other with the heat dissipation unit 46 sandwiched between them. By arranging the heat-generating unit 45 and the current-breaking unit 47 as close as possible to each other so as to face each other in this way, heat can be reliably transferred.

[0050] An intermediate member 49 is provided in the heat dissipation section 46 at a portion facing the current breaker section 47. The intermediate member 49 is made of a material having thermal conductivity and insulating properties, and can transfer heat from the heat dissipation section 46 to the current breaker section 47 while insulating the heat dissipation section 46 from the current breaker section 47.

[0051] The heat dissipation part 46 is also provided with fixing parts 46b that fix the current breaker part 47. The fixing parts 46b are, for example, claw-shaped parts that hold the cutoff body 47a. By fixing the current breaker part 47 to the heat dissipation part 46 with the fixing parts 46b in this way, heat can be reliably transferred.

[0052] In this embodiment, the image forming apparatus 100 has been described as an example, but the invention is not limited to this, and the power interrupter may be incorporated into electrical equipment such as industrial equipment or factory equipment that uses an AC motor.

[0053] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0054] 1 Fixing device 41 Power supply circuit 42 Conversion circuit 43 Control Unit 44 Relay 45 Heat generating part 46 Heat radiation part 47 Power interrupter 48 Thermal Conduction Materials 49 Intermediate parts 50 boards 100 Image forming device

Claims

1. a heat generating portion that generates heat when energized; a current interruption unit that interrupts current between terminals depending on temperature; a heat dissipation portion that dissipates heat by contacting the heat generating portion, The current interruption unit is connected in series with the heat generating unit and is in contact with the heat dissipation unit, and when heated by heat dissipation from the heat dissipation unit, cuts off current to the connected load. A power interrupter characterized by the above.

2. The current interruption device according to claim 1, The current-cutoff unit is in contact with the heat dissipation unit via a heat-conducting member that conducts heat. A power interrupter characterized by the above.

3. The current interruption device according to claim 1, The current interruption unit has a terminal extending therefrom, The heat dissipation part has a notch formed in a part facing the terminal of the current interruption part. A power interrupter characterized by the above.

4. The current interruption device according to claim 1, The current interruption unit has a terminal extending therefrom, The terminal is covered with an insulating material. A power interrupter characterized by the above.

5. The current interruption device according to claim 1, The heat dissipation unit has a fixing portion that fixes the current interruption unit. A power interrupter characterized by the above.

6. The current interruption device according to claim 1, The heat generating portion and the current interrupting portion are disposed so as to face each other with the heat dissipating portion therebetween. A power interrupter characterized by the above.

7. An image forming apparatus comprising the power interrupter according to claim 1.

8. An electrical device comprising the current interruption device according to claim 1.

Images