WO2020027924A1

WO2020027924A1 - Imaging system

Info

Publication number: WO2020027924A1
Application number: PCT/US2019/036959
Authority: WO
Inventors: Yasuo Suzuki
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2018-07-31
Filing date: 2019-06-13
Publication date: 2020-02-06
Also published as: JP2020020932A

Abstract

An imaging system includes an endless belt to convey a printing medium, a heating element to heat the endless belt, a cooling element to cool the endless belt, and a thermoelectric converter. The heating element generates a high temperature region inside the imaging system, and the cooling element generates a low temperature region inside the imaging system. The thermoelectric converter has a first end portion thermally coupled with the high temperature region and a second end portion thermally coupled with the low temperature region, and generates power from a temperature difference between the first end portion and the second end portion.

Description

IMAGING SYSTEM

BACKGROUND

[0001] An image forming apparatus may include a fixing device which fixes a toner image adhering to a printing medium. The fixing device may include an endless belt which conveys a printing medium corresponding to a fixing target, a heating roll which heats the endless belt, a pressing roll which presses the endless belt against the heating roll, and a cooling structure which cools the endless belt having passed between the heating roll and the pressing roll. The printing medium which is conveyed on the endless belt is heated and pressed while passing between the heating roll and the pressing roll, and is further cooled by the cooling structure.

BRIEF DESCRIPTION OF DRAWINGS

[0002] FIG. 1 is a schematic diagram of an example image forming apparatus including an example fixing device.

[0003] FIG. 2 is a diagram illustrating an example fixing device.

[0004] FIG. 3 is a diagram illustrating an example thermoelectric converter of the example fixing device of FIG. 2.

[0005] FIG. 4 is a diagram illustrating an example fixing device.

DETAILED DESCRIPTION

[0006] In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. In some examples, an imaging system may include an image forming apparatus such as a printer, or a portion thereof such as a fixing device and/or the like. In some examples, the imaging system includes an image forming apparatus with a fixing device. The image forming apparatus may also include various devices relating to an image forming operation.

[0007] With reference to FIG. 1 , an example image forming apparatus 1 may form a color image by using magenta, yellow, cyan, and black colors. The image forming apparatus 1 may include a recording medium conveying device 10, a plurality of developing devices 20, a transfer device 30, a plurality of photosensitive bodies 40, and fixing devices 50 and 60. The recording medium conveying device 10 conveys a printing medium P. As an example, the printing medium P is a sheet. The photosensitive body 40 forms an electrostatic latent image, and a developing device 20 develops the electrostatic latent image formed on the outer periphery of the photosensitive body 40. The transfer device 30 secondarily transfers the toner image onto the printing medium P. The fixing devices 50 and 60 fix the toner image onto the printing medium P. The fixing device 50 may be a primary fixing device which performs a first fixing operation of the printing medium P. The fixing device 60 may be a secondary fixing device which performs a second fixing operation of the printing medium P.

[0008] As an example, the recording medium conveying device 10 includes a feeding roller 1 1 which conveys the printing medium P having an image formed thereon along a conveying route R1 . The printing medium P is stacked and accommodated in a cassette C and is picked up and conveyed by the feeding roller 1 1 . The feeding roller 1 1 may be provided in the vicinity of the outlet of the printing medium P of the cassette C. The recording medium conveying device 10 allows the printing medium P to reach a secondary transfer region R2 through the conveying route R1 at a timing in which the toner image transferred onto the printing medium P reaches the secondary transfer region R2.

[0009] The developing device 20 may be provided for each color. Each developing device 20 may include a developing roller 21 which carries a toner on the photosensitive body 40. In the developing device 20 toner and carrier may be adjusted so as to realize a predetermined mixing ratio and so that the toner is uniformly dispersed by mixing and stirring the toner and the carrier. A developing agent is carried on the developing roller 21. The developing roller 21 rotates so that the developing agent is conveyed to a region facing the photosensitive body 40. Then, the toner in the developing agent carried on the developing roller 21 moves to the electrostatic latent image of the photosensitive body 40 so that the electrostatic latent image is developed.

[0010] The transfer device 30 may convey the toner image formed by the developing device 20 and the photosensitive body 40 to the secondary transfer region R2. For example, an image developed on the photosensitive body 40 may be transferred onto the transfer device 30. As an example, the transfer device 30 may include a transfer belt 31 , suspension rollers 32a, 32b, 32c, and 32d, a primary transfer roller 33, and a secondary transfer roller 34. The transfer belt 31 may be suspended by the suspension rollers 32a, 32b, 32c, and 32d. The primary transfer roller 33 may be provided for each color. Each primary transfer roller 33 sandwiches the transfer belt 31 along with each photosensitive body 40. The secondary transfer roller 34 sandwiches the transfer belt 31 along with the suspension roller 32d.

[0011] The transfer belt 31 may include an endless belt which moves in a circulating manner by the suspension rollers 32a, 32b, 32c, and 32d. The primary transfer roller 33 presses the photosensitive body 40 from the inner peripheral side of the transfer belt 31 . The secondary transfer roller 34 presses the suspension roller 32d from the outer peripheral side of the transfer belt 31 . As an example, the photosensitive body 40 may be a photosensitive drum and may be provided for each color. The plurality of photosensitive bodies 40 are arranged in series along the movement direction of the transfer belt 31 . For example, the developing device 20, an exposure unit 41 , a charging device 42, and a cleaning device 43 may be provided to face the outer peripheral surface of each photosensitive body 40.

[0012] The example image forming apparatus 1 may include a process cartridge 2 in which the developing device 20, the photosensitive body 40, the charging device 42, and the cleaning device 43 may be arranged integrally, and an apparatus body 3 to and from which the process cartridge 2 is detachably attached. The process cartridge 2 is attachable to or detachable from the apparatus body 3, for example, in such a manner that a door of the apparatus body 3 is opened and the process cartridge 2 is inserted into or extracted from the apparatus body 3.

[0013] For example, the charging device 42 may uniformly charge the outer peripheral surface of the photosensitive body 40 to a predetermined potential. The charging device 42 may include a charging roller that rotates to follow the rotation of the photosensitive body 40. The exposure unit 41 exposes the outer peripheral surface of the photosensitive body 40 charged by the charging device 42 in response to the image formed on the printing medium P. A potential of a portion exposed by the exposure unit 41 on the outer peripheral surface of the photosensitive body 40 changes and hence an electrostatic latent image is formed on the outer peripheral surface of the photosensitive body 40.

[0014] In the plurality of developing devices 20, for example, toner tanks 25 are disposed so as to face each other. For example, magenta, yellow, cyan, and black toners may be accommodated in the respective toner tanks 25. Toner is supplied from each toner tank 25 to each developing device 20. Each developing device 20 develops an electrostatic latent image by the supplied toner and forms a toner image on the outer peripheral surface of the photosensitive body 40. The toner image formed on the outer peripheral surface of the photosensitive body 40 is primarily transferred onto the transfer belt 31 . The toner remaining on the outer peripheral surface of the photosensitive body 40 after primarily transfer is removed by the cleaning device 43.

[0015] The fixing device 50 may fix the toner image secondarily transferred from the transfer belt 31 onto the printing medium P onto the printing medium P. The fixing device 50 may include a heating roller 51 which heats the printing medium P and fixes the toner image onto the printing medium P, and a pressing roller 52 which presses the heating roller 51 . Both of the heating roller 51 and the pressing roller 52 may be formed in a cylindrical shape. As an example, a heat source such as a halogen lamp may be provided inside the heating roller 51 . A nip portion N1 which is a fixing region of the printing medium P may be provided between the heating roller 51 and the pressing roller 52. When the printing medium P passes through the nip portion N1 , the toner image is melted and fixed onto the printing medium P. [0016] The fixing device 60 may allow the image of the printing medium P to be glossy by smoothing the toner of the printing medium P onto which the toner image is melted and fixed by the fixing device 50. For example, the fixing device 60 may improve the glossiness of the image by melting and pressing the toner of the printing medium P having fine unevenness and smoothing the toner. The fixing device 60 may include a gloss control device which controls the gloss of the image formed on the printing medium P. A structure of the fixing device 60 is described further below. Furthermore, the image forming apparatus 1 may be provided with discharge rollers 45 and 46 which discharge the printing medium P of which the gloss of the image has been controlled by the fixing device 60, to the outside of the image forming apparatus 1 .

[0017] An example image forming method that may be carried out by the image forming apparatus 1 will be described. An example of a printing process that may be carried out by the image forming apparatus 1 will be described. When an image signal of a target recording image is input to the image forming apparatus 1 , the printing medium P stacked in the cassette C is picked up by the rotation of the feeding roller 1 1 and the printing medium P is conveyed along the conveying route R1 . The charging device 42 uniformly charges the outer peripheral surface of the photosensitive body 40 to a predetermined potential. An electrostatic latent image is formed on the outer peripheral surface of the photosensitive body 40 in such a manner that the exposure unit 41 irradiates a laser beam onto the outer peripheral surface of the photosensitive body 40 based on the image signal.

[0018] The developing device 20 performs a developing operation by forming a toner image on the photosensitive body 40. For example, the toner image may be primarily transferred from each photosensitive body 40 onto the transfer belt 31 in a region in which each photosensitive body 40 faces the transfer belt 31 . The toner images formed on the plurality of photosensitive bodies 40 may be sequentially laminated on the transfer belt 31 to form one laminated toner image. The laminated toner image may be secondarily transferred onto the printing medium P conveyed from the recording medium conveying device 10 in the secondary transfer region R2 in which the suspension roller 32d and the secondary transfer roller 34 face each other.

[0019] The printing medium P onto which the laminated toner image is secondarily transferred may be conveyed from the secondary transfer region R2 to the fixing device 50. The fixing device 50 melts and fixes the laminated toner image onto the printing medium P by applying a heat and a pressure to the printing medium P while the printing medium P is conveyed to pass through the nip portion N1 . The printing medium P onto which the laminated toner image is melted and fixed may be conveyed to the fixing device 60. The fixing device 60 may improve the glossiness of the image by melting and pressing the toner of the laminated toner image and smoothing the toner. The fixing device 60 hardens the toner by cooling the printing medium P having a smoothed laminated toner image. The printing medium P may be discharged to the outside of the image forming apparatus 1 by the discharge rollers 45 and 46.

[0020] An example fixing device 60 will be described, with reference to FIG. 2.

[0021] The fixing device 60 may include an endless belt 61 , a heating portion (or heating element) 62 and support rollers 63, 64 which are rotation bodies suspending (or supporting) the endless belt 61 , a pressing portion 65 which corresponds to a rotation body pressing the printing medium P, a cooling portion (or cooling element) 66 which cools the endless belt 61 , a thermoelectric converter 70, and a power storage unit 80. The endless belt 61 may pass along an outer surface of the heating element 62 so that the printing medium P is loaded thereon. The endless belt 61 conveys the printing medium P. As an example, the heating element 62, the support rollers 63 and 64, the cooling element 66, and the thermoelectric converter 70 may be provided inside the endless belt 61. The pressing portion 65 may be provided outside the endless belt 61 .

[0022] The heating element 62 may heat the endless belt 61 and generate a high temperature region A1 inside the image forming apparatus 1 . Meanwhile, the cooling element 66 cools the endless belt 61 and generates a low temperature region A2 inside the image forming apparatus 1 . The high temperature region A1 may be a region including the heating element 62 and may include the endless belt 61 heated by the heating element 62. Further, the low temperature region A2 may be a region including the cooling element 66 and may include, for example, the support roller 63 and the endless belt 61 cooled by the cooling element 66. A temperature difference between the temperature of the high temperature region A1 and the temperature of the low temperature region A2 may be of approximately 30°C to 140°C, inclusive (e.g. within a range equal to or higher than approximately 30°C and equal to or lower than approximately 140°C).

[0023] The heating element 62 may be a roll-shaped heating roller or a belt-shaped heating belt. A fixing region of the printing medium P located between the heating element 62 and the pressing portion 65 defines a nip portion N2. The toner T on the printing medium P may be smoothed when the printing medium P passes through the nip portion N2. For example, a contact pressure may be exerted between the heating element 62 and the pressing portion 65, in which nip portion N2 is formed by the contact pressure.

[0024] The endless belt 61 may be rotated by a rotation of the heating element 62 and the support rollers 63 and 64 being transmitted to the endless belt 61. For example, the support rollers 63 and 64 may support the endless belt 61 from the inside of the endless belt 61 , such that the endless belt 61 moves in a circulating manner along the outer peripheries of the heating element 62 and the support rollers 63 and 64. The printing medium P may be conveyed along the endless belt 61 and pass through the nip portion N2 and the cooling element 66. The printing medium P may be peeled off from the support roller 63 and be conveyed to the outside of the fixing device 60. The pressing portion 65 may include a roll-shaped pressing roll as an example, but may have a shape other than the roll shape in other examples.

[0025] The cooling element 66 may include a heat sink 67 which contacts an opposite side of the printing medium P in the endless belt 61 , and a fan 68 which blows air to the endless belt 61 through the heat sink 67. In some examples, the cooling element 66 may include a Peltier element, a heat pipe, and/or the like. The cooling element 66 may cool the toner T of the printing medium P which is smoothed while passing through the nip portion N2, to harden the toner. Since the smoothed toner T is hardened, the glossiness of the image quality of the printing medium P can be improved. The fan 68 may be operated by receiving power from the power storage unit 80.

[0026] The thermoelectric converter 70 is located between the heating element 62 and the endless belt 61 which is cooled by the cooling element 66, to generate power from a temperature difference between the heating element 62 and the cooled endless belt 61 . As an example, the temperature of the heating element 62 may be within a range of approximately 130°C to 165°C, inclusive (e.g. equal to or higher than approximately 130°C and equal to or lower than approximately 165°C), and the temperature of the endless belt 61 cooled by the cooling element 66 may be within a range of approximately 25°C to 45°C, inclusive (e.g. equal to or higher than approximately 25°C and equal to or lower than approximately 45°C). As an example, the power generated by the thermoelectric converter 70 may be stored in the power storage unit 80. For example, the power storage unit 80 is a battery or a capacitor.

[0027] FIG. 3 is an enlarged view of the example thermoelectric converter 70. With reference to FIGS. 2 and 3, the thermoelectric converter 70 may include a first end portion 71 which is thermally connected to the high temperature region A1 , a second end portion 72 which is thermally connected to the low temperature region A2, an electrode 73 which is provided between the first end portion 71 and the second end portion 72, and an n-type thermoelectric material 74 and a p-type thermoelectric material 75 which are connected to a pair of the electrodes 73.

[0028] The first end portion 71 may be provided at an adjacent position of the heating element 62. The second end portion 72 may be provided at an adjacent position of the endless belt 61 located inside the low temperature region A2. The first end portion 71 may contact the heating element 62, and the second end portion 72 may contact the endless belt 61 . In some examples, the first end portion 71 and/or the second end portion 72 are formed of ceramic and may be formed of an insulating material.

[0029] The thermoelectric converter 70 may generate an electromotive force from the temperature difference by the Seebeck effect. The thermoelectric converter 70 may generate an electromotive force from the temperature difference generated in the fixing device 60, and may generate an electromotive force from the residual heat generated, for example, at the time of stopping the fixing device 60. The fixing device 60 may stop when the fixing device 60 sleeps (e.g. in a lower-power state after a period of time of non-use or non-operation) or the image forming apparatus 1 stops operating.

[0030] As an example, the temperature of the first end portion 71 may be increased by the heating element 62, and the temperature of the second end portion 72 may be decreased by the endless belt 61. The n-type thermoelectric material 74 and the p-type thermoelectric material 75 connect the electrode 73 provided at the first end portion 71 , with the electrode 73 provided at the second end portion 72. The n-type thermoelectric material 74 and/or the p-type thermoelectric material 75 may include semiconductor elements. The thermoelectric converter 70 may be formed in a sheet shape, and a plurality of the n-type thermoelectric materials 74 and a plurality of the p-type thermoelectric materials 75 may be arranged between the first end portion 71 and the second end portion 72.

[0031] In the n-type thermoelectric material 74, the number of positive holes having a plus charge may be larger than the number of electrons having a minus charge, such that positive holes are gathered at the second end portion 72 due to the temperature difference between the first end portion 71 and the second end portion 72. Meanwhile, in the p-type thermoelectric material 75, the number of electrodes may be larger than the number of positive holes, such that electrons are gathered at the second end portion 72 due to the temperature difference between the first end portion 71 and the second end portion 72. Accordingly, an electromotive force may be generated due to a current passing through the n- type thermoelectric material 74, the p-type thermoelectric material 75, and the electrode 73. The thermoelectric converter 70 may include electrode outlets 76 and 77 in at least one of the plurality of electrodes 73. Accordingly, the electromotive force of the thermoelectric converter 70 may be output to the outside of the thermoelectric converter 70 through the electrode outlets 76 and 77.

[0032] The electromotive force of the thermoelectric converter 70 may be stored in the power storage unit 80 connected to the thermoelectric converter 70. Accordingly, the power storage unit 80 may store power obtained by the thermoelectric converter 70. The thermoelectric converter 70 may be directly connected to the fan 68 and may directly supply power thereto, in order to drive the fan 68. In this case, the power storage unit 80 can be omitted.

[0033] FIG. 4 illustrates an example fixing device 90. In the fixing device 90, the thermoelectric converter 70 is aligned with (e.g. positioned to face) the heating element 62 and the cooling element 66. The first end portion 71 may be provided at an adjacent position of the heating element 62, and the second end portion 72 may be provided at an adjacent position of the cooling element 66. For example, the first end portion 71 may contact the heating element 62. The second end portion 72 may contact the heat sink 67 of the cooling element 66.

[0034] Accordingly, the thermoelectric converter 70 reduces power to be supplied from outside the fixing devices 60 and 90 or the image forming apparatus 1 . The example thermoelectric converter 70 converts the relatively large temperature difference between the high temperature portion and the low temperature portion (e.g. the temperature difference between the fixing devices 60 and 90) into power. Accordingly, it is possible to more effectively use the heat present at a position or in region having this large temperature difference. Further, when the power storage unit 80 is provided, the power generated from the thermoelectric converter 70 can be stored into the power storage unit 80.

[0035] The power obtained by the thermoelectric converter 70 may be supplied to the fan 68 or devices other than the fan 68. In some examples, the power storage unit 80 may be provided in the cassette C which warms the printing medium P. In some examples, the power storage unit 80 may supply power to another device which warms the printing medium P. Further, the power obtained by the thermoelectric converter 70 may be used as power at the time of activating the fixing devices 60 and 90 or the image forming apparatus 1 . Accordingly, the power obtained from the thermoelectric converter 70 may be used for various uses. In some examples as described above, the power storage unit 80 may supply the power obtained by the thermoelectric converter 70 to the cooling element 66, in order to more efficiently use the power obtained from the thermoelectric converter 70 inside the fixing devices 60 and 90. [0036] In some examples, as described above, the thermoelectric converter 70 may be formed in a sheet shape. Accordingly, the degree of freedom in the arrangement of the thermoelectric converter 70 can be improved. For example, the sheet-shaped thermoelectric converter 70 may be wound on the heating element 62 or may adhere to the endless belt 61 . In some examples, the thermoelectric converter 70 may be formed in a shape other than the sheet shape. Further, since the thermoelectric converter 70 can be formed in a compact size, the thermoelectric converter 70 can be disposed in various places. As described above, the thermoelectric converter 70 may convert the residual heat generated at the time of stopping the fixing devices 60 and 90 into power, in order to more efficiently use the heat when the fixing devices 60 and 90 are not operated, thereby reducing waste of the generated heat.

[0037] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail. For example, either one of the endless belt 61 , the heating element 62, and the pressing portion 65 may have a shape that is not a rotation body.

Claims

1 . An imaging system comprising:

an endless belt to convey a printing medium;

a heating element to heat the endless belt and generate a high temperature region inside the imaging system;

a cooling element to cool the endless belt and generate a low temperature region inside the imaging system; and

a thermoelectric converter including a first end portion thermally coupled with the high temperature region and a second end portion thermally coupled with the low temperature region, the thermoelectric converter to generate power from a temperature difference between the first end portion and the second end portion.

2. The imaging system according to claim 1 , wherein the second end portion of the thermoelectric converter is adjacent to a portion of the endless belt located in the low temperature region.

3. The imaging system according to claim 1 , wherein the second end portion of the thermoelectric converter is adjacent to the cooling element.

4. The imaging system according to claim 1 , wherein the first end portion of the thermoelectric converter is adjacent to the heating element.

5. The imaging system according to claim 1 , further comprising:

a power storage unit to store the power generated by the thermoelectric converter.

6. The imaging system according to claim 5, the power storage unit to supply the power generated by the thermoelectric converter to the cooling element.

7. The imaging system according to claim 5, wherein the cooling element includes a heat sink and a fan to cool the endless belt, the power storage unit to supply the power to the fan.

8. The imaging system according to claim 1 , further comprising:

a fixing device including the endless belt, the heating element, the cooling element, and the thermoelectric converter, the fixing device to generate residual heat when an operation of the fixing device is stopped,

the thermoelectric converter to convert the residual heat into power when the operation of the fixing device is stopped.

9. The imaging system according to claim 1 , wherein the thermoelectric converter has a sheet shape.

10. The imaging system according to claim 1 , wherein a temperature difference between the high temperature region and the low temperature region is within a range of approximately 30°C to 140°C, inclusively.

1 1 . A fixing device for an image forming apparatus, comprising:

an endless belt to convey a printing medium;

12. The fixing device according to claim 1 1 , wherein the second end portion of the thermoelectric converter is adjacent to a portion of the endless belt located in the low temperature region.

13. The fixing device according to claim 11 , wherein the second end portion of the thermoelectric converter is adjacent to the cooling element.

14. The fixing device according to claim 11 , wherein the first end portion of the thermoelectric converter is adjacent to the heating element.

15. The fixing device according to claim 11 , further comprising: