Fixing device

Abstract

To provide a fixing device which has a simple configuration that makes it difficult for a connector to come off a heater.SOLUTION: A unit holder is provided with an abutting portion configured to be in contact with a heater holder when a force is applied to a connector in a direction toward a roller.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a fixing device mounted on an electrophotographic recording type image forming apparatus such as a printer or a copier.

Background Art

[0002] As a fixing device mounted on an image forming apparatus, there is a device using a planar heater such as a ceramic heater. The planar heater has a planar substrate, a heating resistance pattern formed on the substrate, and an insulating protective layer covering the heating resistance pattern. At the end of the planar heater in the longitudinal direction of the heater, it is electrically connected to the heating resistance pattern, and an electrode portion to which a terminal of a power supply connector is connected is provided. The electric cable extending from the connector is connected to a unit connector provided in the fixing device that electrically connects the main body of the image forming apparatus and the fixing device. And the power supply of the heater and the main body of the image forming apparatus is electrically connected via the unit connector.

[0003] When assembling the fixing device in the factory, if an external force is applied to the connector, there is a concern that the connector may be detached from the heater or the contact between the terminal of the connector and the electrode of the heater may become poor. Patent Document 1 discloses a configuration in which by adding a locking member, it is difficult for the connector to be detached from the heater even when an external force is applied.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a fixing device having a simpler configuration than that of Patent Document 1 and in which it is difficult for the connector to be detached from the heater.

Means for Solving the Problems

[0006] To solve the above-mentioned problems, the present invention provides a heating unit comprising: a cylindrical film; an elongated planar heater disposed in the internal space of the film along the longitudinal direction of the film; a heater holder disposed in the internal space of the film and holding the heater along the longitudinal direction; and a unit holder provided at a position facing the end face of the film in the longitudinal direction. and A roller that forms a fixing nip section for gripping and transporting the recording material, a device frame that holds the heating unit and the roller by holding the unit holder and the axis of the roller, and a connector that is electrically connected to the heater on the side of the device frame opposite to the side on which the film is provided, wherein the connector is electrically connected to the heater and the connector This is the opposite direction to the direction in which the aforementioned connector is attached. A fixing device having a connector having a locking portion that prevents the connector from coming out by engaging with a locking portion of the unit holder when a force is applied in the direction that would cause the connector to come out, wherein the fixing nip portion fixes a toner image on the recording material to the recording material while transporting the recording material, wherein when a force is applied to the connector in the direction toward the roller, the unit holder is provided with a stopper portion against which the heater holder abuts. Furthermore, the abutment portion extends in the longitudinal direction to the region where the connector is located. It is characterized by the following: [Effects of the Invention]

[0007] According to the present invention, a fixing device can be provided that has a simple configuration and prevents the connector from easily detaching from the heater. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional view of an image forming apparatus [Figure 2] Perspective view of the fixing device [Figure 3] Enlarged view of part of the fixing device [Figure 4] Side view of the fixing device [Figure 5] Cross-sectional view of the heating unit [Figure 6]Perspective view of a heater holder that holds a heater. [Figure 7] Perspective view of the connector [Figure 8] Perspective view of the flange [Figure 9] Enlarged view of part of the fixing device [Figure 10] Partial enlarged view of the fixing device in Example 2 [Modes for carrying out the invention]

[0009] (Example 1) Figure 1 is a cross-sectional view of an image forming apparatus (laser beam printer) 100 equipped with a fixing device. A laser beam printer is a device that forms a toner image on a recording material using electrophotographic recording technology. Since electrophotographic recording technology is a well-known technology, the operation of the laser beam printer will be briefly explained using Figure 1.

[0010] Reference numeral 2 denotes the photosensitive drum, which is scanned with laser light corresponding to the image information emitted from the scanner unit 4. The electrostatic latent image formed on the photosensitive drum 2 is developed with toner contained in the developer unit 1. The toner image formed on the photosensitive drum 2 is transferred to the recording material S, which is transported to a transfer nip formed by the photosensitive drum 2 and the transfer roller 3. The recording material is contained in the paper feed cassette 5 and is fed one sheet at a time by the pickup roller 6. After that, it is transported toward the transfer nip by the transport roller 7 and the registration roller 8.

[0011] The recording material S onto which the toner image has been transferred is subjected to heat and pressure in the fuser unit 20. This fixes the toner image to the recording material S. Reference numeral 21 denotes the heating unit, reference numeral 22 denotes the pressure roller, and reference numeral N denotes the fuser nip.

[0012] In the case of single-sided printing, the recording material S that has passed through the fixing device 20 is discharged onto the paper discharge tray 15 by the paper discharge roller 9 and the paper discharge roller 10. Reference numeral 12 is a flapper that switches the traveling direction of the recording material S. In the case of double-sided printing, the recording material S is guided between the paper discharge roller 9 and the reversing roller 11 by the flapper 12, and then, due to the reverse rotation of the reversing roller 9, the recording material S is drawn into the double-sided conveyance path. Thereafter, the recording material S is conveyed by the conveyance rollers 13 and 14, and a toner image is formed on the second side of the recording material S in the same process as the first side. The recording material S on which toner images are formed on both sides is discharged onto the paper discharge tray 15.

[0013] Next, the fixing device 20 of the present embodiment will be described with reference to FIGS. 2 to 9. FIG. 2 is an overall view of the fixing device 20, FIG. 3 is a partially enlarged view of FIG. 2, and FIG. 4 is a left side view of FIG. 2.

[0014] The heating unit 21 and the pressure roller 22 are supported by a frame (device frame). The frame is composed of a first side plate 30, a second side plate 31, an upper stay 32, and a lower stay 33. The first side plate 30 and the second side plate 31 are respectively arranged at both ends in the longitudinal direction of the fixing device 20. The first side plate 30 has a U-shaped groove portion 30s for mounting the heating unit 21 and the pressure roller 22 (see FIG. 2), and the second side plate 31 also has a U-shaped groove portion 31s for mounting the heating unit 21 and the pressure roller 22 (see FIG. 4).

[0015] The pressure roller 22 is a roller having an elastic layer such as silicone rubber around the shaft portion 22a, and has a fluororesin layer on the surface. Bearings 34 are attached to both ends of the shaft portion 22a of the pressure roller 22. The pressure roller 22 is rotatably supported by the frame by fitting the bearings 34 into bearing holders 35 respectively fitted into the recesses 30s and 31s of the first side plate 30 and the second side plate 31.

[0016] As shown in FIG. 5, the heating unit 21 has a cylindrical film 40 and a heater 43 disposed along the longitudinal direction (generatrix direction) of the film 40 in the internal space of the film 40. In the internal space of the film 40, in addition to the heater, there are provided a heater holder 42 that holds the heater 43 and has a guide function for the rotation of the film 40, and a stay 41 that reinforces the heater holder 42. The heater 43, the heater holder 42, and the stay 41 are components elongated in the longitudinal direction of the film 40, and both ends of each protrude from both ends of the film 40. Further, at positions facing the end faces of the film 40, there are provided flanges 50R (50L) (the flange 50L is not shown). The flange 50R (50L) serves as a unit holder for holding the heating unit 21 on the frame. Also, the flange 50R (50L) of the present embodiment also has a function of restricting the lateral movement of the film 40 in the longitudinal direction. Perspective views of the flange 50R are shown in FIGS. 8(a) and (b). FIG. 8(b) is a view of FIG. 8(a) seen from the back side. The flange 50R (50L) is also provided with a receiving surface 50R6 for receiving the end face of the film 40 and an inner surface receiving portion 50R7 for receiving the inner peripheral surface of the longitudinal end of the film 40. The flange 50R (50L) is mounted into the groove portions 30s (31s) of the frame toward the pressure roller 22. Thereby, the heating unit 21 is mounted on the frame.

[0017] The film 40 is a flexible rotating body having a resin or metal as the material of the base layer and has a surface of a silicone rubber layer or a fluororesin. The heater holder 42 is made of a heat-resistant resin such as a liquid crystal polymer, and the stay 41 is made of a metal such as iron.

[0018] The heater 43 is a plate-shaped heater with a heating resistor printed on a ceramic substrate, and an electrode 43d for power supply is also printed at the longitudinal end of the heater 43. <0000​The flange 50R (50L) is pressed toward the pressure roller 22 by the pressure plate 51 and the pressure spring 52. The flange 50R has a guide groove 50R1 for mounting the flange 50R in the groove 30s of the frame, and a force receiving portion 50R5 that receives the pressure from the pressure plate 51. The flange 50L, not shown, also has these parts. The pressure received by the flange 50R (50L) is transmitted to the pressure roller 22 in the order of stay 41, heater holder 42, heater 43, and film 40. As a result, a fixing nip portion N (see Figure 1) is formed between the film 40 and the pressure roller 22. In other words, the fixing nip portion N is formed by the heater 43 and the pressure roller 22 via the film 40.

[0020] The pressure roller 22 rotates under power from a motor (not shown). The fixing film 40 rotates in a manner driven by the pressure roller 22.

[0021] The heater holder 42 is provided with a first protrusion 42a and a second protrusion 42b at its ends in the longitudinal direction of the heater. The connector 60, described later, is positioned relative to the heater holder 42 by inserting the first recess 60c and the second recess 60d of the connector 60 into these protrusions.

[0022] Next, we will describe the connector 60 that electrically connects the heater 43 to the power supply provided on the main body of the image forming apparatus 100.

[0023] As shown in Figures 2-4, the connector 60 is provided only on the flange 50R side. The connector 60 has a shape that clamps onto the heater holder 42 while it is holding the heater 43. The connector 60 has an arm portion 60a, and the arm portion 60a is provided with a connector locking portion 60b that prevents the connector 60 from coming loose. When the connector 60 is inserted into the heater holder 42, the arm portion 60a bends and the connector locking portion 60b engages with the holder locking portion 50R4, and the connector 60 is locked to the flange 50R.

[0024] To remove the connector 60 from the heater holder 42, the gripping portion 60g at the tip of the arm portion 60a is pressed with a finger, causing the arm portion 60a to bend and the connector locking portion 60b to be released from the holder locking portion 50R4. This allows the connector 60 to be removed in the opposite direction to the installation direction.

[0025] A conductive connection terminal 60e is housed inside the insulating housing of the connector 60. A springy contact portion 60f is provided at one end of the connection terminal 60e. The contact portion 60f makes contact with the electrode portion 43d of the heater 43, thereby electrically connecting the heater 43 and the connector 60. A cable CA is connected to the other end of the connection terminal 60e, and power can be supplied to the heater 43 by connecting cable CA to the power supply of the main body of the image forming apparatus 100.

[0026] Here, since the electrode 45 and the connection terminal 64 are treated as ignition sources, if there are parts made of materials that are not sufficiently flame-retardant in the surrounding area, for example, parts made of flame-retardant material UL94_HB, it is necessary to isolate those parts from the ignition sources. In this embodiment, the material of the heater holder 42 is made of a material with flame retardancy of UL94_V-0 or higher, and a shielding portion 50R2 is provided on the flange 50R to conceal the connection terminal 64 from surrounding parts and improve safety.

[0027] Incidentally, the fixing device 20 does not have a structure that supports the portion of the heating unit 21 that is outside the second side plate 31 in the longitudinal direction of the heater. That is, the portion of the heating unit 21 to which the connector 60 is attached is in a cantilever-like state. Therefore, when an external force is applied to the connector 60, the connector holding portion of the heater holder 42 is easily deformed. Deformation of the heater holder 42 in the direction D1 in Figure 9 reduces the amount of locking between the connector locking portion 60b and the holder locking portion 50R4, so there is a possibility that the connector 60 will come off in the direction opposite to the mounting direction.

[0028] Therefore, in this embodiment, the fixing device 20 has a portion of the flange 50 that the heater holder 42 abuts against when the heater holder 42 deforms in the D1 direction (butt portion 50R3). When an external force is applied to the connector 60, causing the heater holder 42 to deform in the D1 direction, the heater holder 42 comes into contact with the butt portion 50R3, suppressing the deformation of the heater holder 42. If an even larger force is applied and the heater holder 42 deforms further, the heater holder 42 and the flange 50R deform together as a single unit.

[0029] This structure suppresses fluctuations in the relative positional relationship between the connector 60 and the flange 50R even when external force is applied. In other words, because the fluctuation in the amount of locking between the connector locking portion 60b and the holder locking portion 50R4 is small, the connector 60 is less likely to come off.

[0030] As described above, the fixing device of this embodiment, which transports the recording material and fixes the toner image on the recording material at the fixing nip section, includes a heating unit, etc. The heating unit has a cylindrical film and an elongated planar heater arranged in the internal space of the film along the longitudinal direction of the film. Furthermore, the heating unit has a heater holder arranged in the internal space of the film that holds the heater along the longitudinal direction. The heating unit is provided at a position facing the end face of the film in the longitudinal direction.

[0031] The pressure roller (roller), together with the heating unit, forms a fixing nip section that grips and conveys the recording material.

[0032] The device frame holds the heating unit and the rollers by holding the unit holder and the roller shafts.

[0033] The connector is electrically connected to the heater on the side of the device frame opposite to the side on which the film is attached. The connector has a locking portion that prevents the connector from coming loose when a force is applied to the connector in a direction that would cause the connector to come loose while the connector is electrically connected to the heater, by engaging with a locking portion of the unit holder.

[0034] Furthermore, when a force is applied to the connector in the direction toward the roller, the unit holder is provided with a stopper portion against which the heater holder makes contact.

[0035] Furthermore, the unit holder has a shielding portion that conceals the connector's terminals.

[0036] (Example 2) Next, the fixing device of Example 2 will be described. Note that Example 2 differs from Example 1 only in the flange configuration. Parts that are the same as those in Example 1 or have the same function are indicated by the same reference numerals as in Example 1, and their descriptions are omitted. Figure 10 shows a perspective view of a part of the fixing device of Example 2. The amount of locking of the connector locking portion 60b will decrease not only when the heater holder 42 is deformed in the D1 direction, but also in the D2 direction (the rotation direction when viewed in the axial direction of the roller).

[0037] Therefore, the flange 500R mounted on the fixing device of Embodiment 2 has an engagement groove (second abutment portion) 500R8. The end of the heater holder 42 is inserted into the engagement groove 500R8. When the end of the heater holder 42 deforms in the D2 direction, the engagement groove 500R8 comes into contact with the heater holder 42, and the flange 500R and the heater holder 42 move and deform together. Therefore, even if the heater holder 42 deforms in the D2 direction, the relative positional relationship between the connector 60 and the holder locking portion 500R4 does not change, so the connector 60 will not come off. Reference numeral 500R1 denotes a guide groove, reference numeral 500R2 denotes a shielding portion, reference numeral 500R3 denotes an abutment portion, and reference numeral 500R5 denotes a force receiving portion, and each part has the same function as the flange 50R of Embodiment 1.

[0038] The flange 500R can accommodate deformation of the heater holder 42 in two directions, D1 and D2.

[0039] As described above, the unit holder of the fixing device in this embodiment has a second abutment portion against which the heater holder comes into contact when a rotational force is applied to the connector in the axial direction of the roller.

[0040] The two embodiments described above are devices in which only one connector is provided for supplying power to the heater, but the present invention can also be applied to devices in which connectors are provided at both ends of the heater in the longitudinal direction. [Explanation of Symbols]

[0041] 20 Fixing device 21 Heating Unit 22 Pressure rollers 42 Heater holder 50R flange 50R3 Butt section

Claims

1. A heating unit comprising: a cylindrical film; an elongated planar heater disposed within the internal space of the film along the longitudinal direction of the film; a heater holder disposed within the internal space of the film and holding the heater along the longitudinal direction; and a unit holder provided at a position facing the end face of the film in the longitudinal direction. A roller that forms a fixing nip section for gripping and conveying the recording material together with the heating unit, The device frame holds the heating unit and the roller by holding the unit holder and the roller shaft, A connector electrically connected to the heater on the side of the device frame opposite to the side on which the film is provided, the connector having a locking portion that, when a force is applied to the connector in the direction opposite to the direction in which the connector is attached, in a direction that causes the connector to come off while the connector is electrically connected to the heater, engages with a locking portion of the unit holder to prevent the connector from coming off, A fixing device having a fixing nip section that transports the recording material and fixes the toner image on the recording material to the recording material, When a force is applied to the connector in the direction toward the roller, the unit holder is provided with a stopper portion against which the heater holder abuts. The fixing device is characterized in that the abutment portion extends in the longitudinal direction to the region where the connector is located.

2. The fixing device according to claim 1, characterized in that the unit holder has a shielding portion that conceals the connection terminals of the connector.

3. The fixing device according to claim 1 or 2, characterized in that a second abutment portion is provided on the unit holder, which the heater holder contacts when a rotational force is applied to the connector as viewed in the axial direction of the roller.

Images