Patent Application
20200241453
This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a to Japanese Patent Application No. 2019-012938, filed on Jan. 29, 2019, in the Japan Patent Office, the entire disclosure of which is incorporated by reference herein.
Aspects of the present disclosure relate to a fixing device and an image forming apparatus including the fixing device.
A fixing device in an electrophotographic image forming apparatus includes: a heating device such as a fixing roller having a built-in heater; and a temperature detector such as a thermistor that controls a fixing temperature. The fixing device (fixing unit) is often attachable to/detachable from the image forming apparatus for the purposes of: improving a paper jam handling property; and replacing a unit. The heating device and the temperature detector supply electric power from an apparatus body to the heater and transmit a detection temperature of a thermistor element portion to a controller of the apparatus body by connection between terminal portions at a drawer connector. The terminal portions are provided on the fixing device and the image forming apparatus body side of the drawer connector, respectively.
However, in a conventional drawer connector, defective contact such as increase in electrical resistance or defective electrical continuity has occurred sometimes. The defective contact is caused as follows: when a metal-plated layer of a terminal contact portion is exposed to high-temperature and high-humidity conditions and subjected to abrasion by fine sliding motions of a fixing device at the time of attachment/detachment of the fixing device or vibration during operation of an apparatus body, the metal-plated layer of the terminal contact portion is peeled off, and nickel plating on an underlying layer is exposed, and then the terminal portion is oxidized. As a result, a detection error of a thermistor detection temperature is caused.
In an aspect of the present disclosure, there is provided a fixing device that includes a fixing member, at least one temperature detector, and a device-side drawer connector. The at least one temperature detector is configured to detect a temperature of the fixing member, the at least one temperature detector including a plurality of lead wires. The device-side drawer connector has a terminal portion configured to fit with a terminal portion of a body-side drawer connector of an image forming apparatus body to connect the plurality of lead wires of the at least one temperature detector to the image forming apparatus body. The device-side drawer connector is configured to branch a signal wire of the plurality of lead wires of the at least one temperature detector into a plurality of systems. A plurality of earth wires of the plurality of lead wires of the at least one temperature detector is short-circuited to each other.
In an aspect of the present disclosure, there is provided an image forming apparatus including the fixing device.
The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted.
In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results.
Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable.
Referring now to the drawings, embodiments of the present disclosure are described. below. In the drawings for explaining the following embodiments, the same reference codes are allocated to elements (members or components) having the same function or shape and redundant descriptions thereof are omitted below.
Hereinafter, a color laser printer (hereinafter also simply referred to as “printer”) that is an image forming apparatus according to an embodiment of the present disclosure will be described.
Additionally, an optical writing unit 9 as a latent image forming device is provided. below the tandem image former. The optical writing unit 9 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surfaces of the respective photoconductors 21 with laser light while scanning the surfaces with the laser light based on image data.
Additionally, an intermediate transfer belt 1 of an endless belt type is provided as an intermediate transferor immediately above the tandem image former. The intermediate transfer belt 1 is passed around support rollers 1a and 1b, and a drive motor as a driving source is connected to a rotation shaft of the support roller 1a. functioning as a drive roller among these support rollers. When this drive motor is driven, the intermediate transfer belt 1 is rotationally moved in a counterclockwise direction in the drawing, and also the support roller 1b that can be driven is rotated. The intermediate transfer belt 1 includes, on an inner side of the intermediate transfer belt, primary transfer devices 11Y, 11C, 11M, and 11K to transfer, onto the intermediate transfer belt 1, the toner images on the photoconductors 21Y, 21C, 21M, and 21K.
Additionally, the intermediate transfer belt 1 includes a secondary transfer roller 4 as a secondary transfer device more on a downstream side than the primary transfer devices 11Y, 11C, 11M, and 11K in the driving direction of the intermediate transfer belt 1. The support roller 1b is arranged on an opposite side of the secondary transfer roller 4 while interposing the intermediate transfer belt 1, and functions as a pressing member. Additionally, a sheet tray 8, a sheet feeding roller 7, a registration roller 6, and the like are provided. Further provided are a fixing device 5 and an output roller pair 3 at a downstream portion of the secondary transfer roller 4 in an advancing direction of a recording medium S on which the toner image has been transferred by the secondary transfer roller 4. The fixing device 5 fixes the image on the recording medium S.
Next, operation of the printer will be described. The photoconductors 21Y, 21C, 21M, and 21K are respectively rotated in the individual image forming devices, and the surfaces of the photoconductors 21Y, 21C, 21M, and 21K are first uniformly charged by charging devices 17Y, 17C, 17M, and 17K along with the rotation of the photoconductors 21Y, 21C, 21M, and 21K. Subsequently, writing laser light is emitted from the optical writing unit 9 based on image data to form electrostatic latent images on the photoconductors 21Y, 21C, 21M, and 21K. After that, the toner is made to adhere by the developing devices 10Y, 10C, 10M, and 10K, and the electrostatic latent images are visualized to form respective monochromatic images of yellow, cyan, magenta, and black on the respective photoconductors 21Y, 21C, 21M, and 21K. Additionally, the support roller 1a as the drive roller is rotationally driven by the drive motor provided in the image forming apparatus to rotationally drive the other support roller 1b as a driven roller and the secondary transfer roller 4, and rotationally convey the intermediate transfer belt 1. Then, the visible images are sequentially transferred onto the intermediate transfer belt 1 at the primary transfer devices 11Y, 11C, 11M, and 11K. Thus, a composite color image is formed on the intermediate transfer belt 1. The surfaces of the photoconductors 21Y, 21C, 21M, and 21K after the image transfer have residual toner removed by the respective photoconductor cleaning devices to prepare for image formation again.
Further, a leading edge of the recording medium S is fed out from the sheet tray 8 by the sheet feeding roller 7, conforming to timing of image formation. Then, the recording medium S is conveyed to the registration roller 6 and stopped temporarily. Subsequently, the recording medium S is conveyed between the secondary transfer roller 4 and the intermediate transfer belt 1, conforming to the timing of image forming operation. Here, the intermediate transfer belt 1 and the secondary transfer roller 4 form a so-called secondary transfer nip while sandwiching the recording medium S, and the toner image on the intermediate transfer belt 1 is secondarily transferred onto the recording medium S at the secondary transfer roller 4.
After the image transfer, the recording medium S is sent to the fixing device 5, and the recording medium S is conveyed and nipped at a nip portion formed by a fixing member 51 and a pressure member 52 to heat and pressurize the toner image on the recording medium S and fix the toner image on the recording medium S. The fixing member 51 has a surface kept at a predetermined temperature, and the pressure member 52 faces the fixing member 51 and is pressed against the fixing member 51. Furthermore, the recording medium S ejected from the nip portion is separated by a separator and then ejected from the output roller pair 3 to the outside of the apparatus. On the other hand, the intermediate transfer belt 1 after the image transfer has residual toner remaining on the intermediate transfer belt 1, and the residual toner is removed by an intermediate transferor cleaning device 12 to prepare again for image formation by the tandem image former.
The signal wires 15a and 16a and the earth wires 15b and 16b of the thermistors 15 and 16 are connected to the fixing device side connector 55U on the fixing device 5 side of the drawer connector 55 via a relay connector, or directly connected to the fixing device side connector 55U. Thus, the signal wires 15a, 16a and the earth wires 15b, 16b are each connected to one terminal in the fixing device side connector 55U of the drawer connector 55.
On the other hand, terminals corresponding to the terminals of the fixing device side connector 55U side are also provided on the body-side connector 55H side of the apparatus body 50 side. The drawer connector 55 is a snap-in connector including a pair of male and female connectors. Therefore, when the fixing device 5 is set in the apparatus body 50, the terminal of the signal wire 15a and the terminal of the earth wire 15b are connected in a pair and the terminal of the signal wire 16a and the terminal of the earth wire 16b are connected in a pair, and a contact of one system (signal path) is formed by each of the pairs. A place where a terminal of the body-side connector 55H and a terminal of the fixing device side connector 55U are in contact with each other is a contact.
Accordingly, the fixing device 5 according to the present embodiment is the fixing device including one or a plurality of thermistors 15 and 16 as the temperature detectors that detect the temperature of the fixing member 51. The lead wire in each of the thermistors is connected by mutual fitting between the terminal portion on the fixing device 5 side and the terminal portion on the apparatus body 50 side at the drawer connector 55. The system in each of the signal wires 15a and 16a of the thermistors 15 and 16 is branched into the plurality of systems at the portion of the drawer connector 55, and the plurality of earth wires 15b and 16b is short-circuited to each other.
On the other hand, the earth wire 15h of the central thermistor 15 and the earth wire 16b of the end-portion thermistor 16 are short-circuited between the fixing device side connector 55U and the body-side connector 55H and between the central thermistor 15 and the end-portion thermistor 16 by the short-circuit wire 17. The short-circuit wire 17 may be arranged between the fixing device side connector 55U and the body-side connector 55H, may be arranged between the central thermistor 15 and the end-portion thermistor 16, or may be arranged between the fixing device side connector 55U, the body-side connector 55H, and the apparatus body 50.
Furthermore, branching of each of the signal wires 15a and 16a and short-circuiting of the earth wires 15b and lob in the fixing device side connector 55U of the fixing device 5 side are achieved via: a relay board provided in the fixing device 5; and the relay connector 31 provided in the relay board. Specifically, each of the signal wires 15a and 16a has the number of systems increased from the one system to the two systems, and the earth wires 15b and 16b are short-circuited by the short-circuit wire 17. Since the relay board is thus provided in the fixing device 5, each of the signal wires 15a and 16a can be branched by the relay connector 31 and the lead wires (wiring harness) provided in the relay board. Furthermore, assembling work efficiency can be improved. Furthermore, branching of each of the signal wires 1.5a and 16a at the body-side connector 55H of the apparatus body 50 side and short-circuiting of the earth wires 15b and 16b are achieved via a relay board provided in the apparatus body 50 and the relay connector 32 provided in the relay board.
Furthermore, a versatile thermistor as conventionally used can be used as it is, and the configuration of the present embodiment can be achieved by adding the relay connectors 31 and 32 to increase the number of signal wires. Therefore, a high development cost for a new component can be suppressed. Similarly, the earth wires can be short-circuited by adding the relay connectors (in other words, a system of each earth wire is increased to a plurality of earth wires). Therefore, space saving can also be achieved.
Moreover, in a case where resistance abnormality is detected as a result of resistance measurement at terminal portions of signal wires of the drawer connector 55, a notification to prompt a user to attach and detach the fixing device 5 relative to the apparatus body 50 can be displayed on an operation panel of the image forming apparatus. Thus, the resistance abnormality at the terminal portion of the drawer connector 55 is detected and the user is made to attach and detach the fixing device relative to the apparatus body 50. As a result, a foreign substance, such as an oxide generated at the terminal portion of the drawer connector and causing defective contact, can be removed by a wiping effect to restore the terminal portion/contact portion.
As described above, according to an embodiment of the present disclosure, each thermistor includes the two lead wires as in a conventional thermistor, and the lead wires are separated into the signal wire and the earth wire. Each signal wire is branched at the drawer connector of the fixing device, and the branched signal wires are connected to the terminals obtained by the system increase from one system to two systems. On the other hand, earth wires of the thermistors are short-circuited to each other. The body-side connector also includes the terminals of the branched signal wires in a manner corresponding to the terminals of the fixing device side connector. The branched signal wires are connected on the body side. Thus, in the present embodiment, the contacts (signal paths) of the two systems (the plurality of systems) are formed in the drawer connector.
Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.
Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above. Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC), digital signal processor (DSP), field programmable gate array (FPGA), and conventional circuit components arranged to perform the recited functions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-012938 | Jan 2019 | JP | national |
